Long COVID and the Neuroendocrinology of Microbial Translocation Outside the GI Tract: Some Treatment Strategies

Round 1

Reviewer 1 Report

The paper is interesting and well written. 

I just suggest:

- some formatting and style correction (for example at page 8)

- please complete the last sentence at page 3 and this section (Efferocytosis and biological barriers - intestinal barrier)

kind regards

 

Author Response

MDPI formatting cut the sentence on page 3 and put it under Figure 1. In the original manuscript the sentence was complete (highlighted in yellow) and the text under Fig.1 was much shorter and did not include references.

Also, the formatting style is not in the original (please see the attached original)

 

Author Response File: Author Response.docx

Reviewer 2 Report

Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

Also, write the names of the genes/proteins in italics for a better read.

"Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2. 

You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

Chapter 5 could be a sub-chapter for Chapter 4.

Chapters 7-11 can be sub-chapters for Chapter 6.

Please use a table or two for a better classification of the information.

A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

The conclusion can be longer and contain the actual conclusion of the study.

Also, an extensive language style and check is required.

 

 

 

 

Author Response

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

Q: Also, an extensive language style and check is required.

A: Sent to MDPI # 52105

 

 

 

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

x

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

 

Q: Please explain how this review was created and what type of review is it. What was the main purpose of it. Also the databases used with inclusion and exclusion criteria. The time of doing this review and the period of the search of the review in the databases. Please use a PRISMA Flow Diagram.

A: This is a narrative review and PRISMA flow diagram was not utilized. The purpose of the review is to summarize what is currently known about host immune responses to translocated gut microbes and how this relates to fatiguing illnesses, including long COVID. We have used Google Scholar and PubMed and since the literature on this topic is very limited, we did not exclude any year of publication or any articles that connected chronic fatigue to microbial translocation. The following phrase was introduced in the abstract: “The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID.”

 

Q: Please review the instructions for the authors. Ie, references (2)(3)(4)(5)- it is not an accepted format.

A: The [2-5] format was used throughout the text.

 

Q: Also, write the names of the genes/proteins in italics for a better read.

Q: Genes and proteins were italicized.

 

Q: "Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce" - here is a sudden stop...

A: This happened during MDPI formatting. A portion of this sentence was placed under the figure. In the original this sentence goes: “Cell membrane pores lead to ePS, a global immunosuppressive signal, that may help the virus subvert host defenses (92). The subsequent, syncytia formation can then induce premature cellular senescence and the release of senescence-associated secretory phenotype (SASP), a pathological secretome that disrupts endothelial barriers by promoting premature ECs senescence, a phenotype documented in both ME/CFS and COVID-19 (42)[93-95]. “The text under the figure is much shorter in the original: Fig. 1 The SARS-CoV-2 receptor binding site (RBS) contains a double arginine insert (PRRA) or arginine motif, that perforates the cell membrane, triggering Ca2+ influx from both the endoplasmic reticulum (ER) and the extracellular compartment. Upregulated cytosolic Ca2+ activates TMEN16F, externalizing phosphatidylserine (ePS), a “eat me” or “fuse me” signal that leads to cell death (if the damage is irreparable) or cell-cell fusion (if the cell is less damaged). Cell-cell fusion or syncytia formation induces premature cellular senescence, disrupting biological barriers. The virus benefits from ePS as a global immunosuppressive signal, allowing undetected entry into host cells.

 

Q: Do not put so much information and even references in the caption of the figure. ie Figure 1. and the information before "(not shown)" from figure 2.

Figure 1 text was mistakenly changed during formatting. Please see above.

I shortened the text under figure 2. It now reads: “Fig.2 SARS-CoV-2 attachment to ACE-2, blocks this enzyme, causing angiotensin II (ANG II) accumulation by inhibiting its hydrolysis. Upregulated ANG II, increases both cortisol and HMGB1, disrupting the efferocytosis of senescent cells. Accumulation of senescent cells triggers inflammation and biological barrier disruption, a common pathology found not only in the disorders marked by chronic fatigue but also in neuropsychiatric and autoimmune diseases. “

 

 

 

Q: You can put the underline parts ie "Intestinal barrier: Many viruses, including" as sub-chapters.

A: Sub-chapters were used here, in chapter 5 and also 7-11.

Q: Please check the information in the paragraph before Chapter 3, it is using another font. Also for Chapter 5.

A: Yes, this was done during the formatting. It is not in the original manuscript.

 

Q: Chapter 5 could be a sub-chapter for Chapter 4.

A: Added

 

Q: Chapters 7-11 can be sub-chapters for Chapter 6.

A: Added

 

Q: Please use a table or two for a better classification of the information.

A: Table 1 was included.

Q: A chapter Discussions before conclusions is needed in order to explain the findings and to compare your findings with the findings of other studies on the same subject.

A: Discussion section was added:

“The concept of microbial translocation as a key mechanism of chronic systemic immune activation, and disease was studied extensively in the HIV infection, a condition associated with chronic fatigue and increased prevalence of ME/CFS (294)(295). COVID-19, like HIV, causes intestinal barrier disruption, impaired efferocytosis, and accumulation of senescent, apoptotic, and necrotic cells that were previously associated with dysfunctional immune responses (296)(297).  Indeed, the newly discovered innate lymphoid cells 3 (ILC3) that release interleukin 22 (IL22), a protector of intestinal barrier, have been implicated in both COVID-19 and HIV, linking dysfunctional mucosal immunity to these viral infections (298)(299).  As loss of IL22 was associated with premature cellular senescence, this mechanism may account for the dysfunctional efferocytosis and gut barrier dysfunction in long COVID (300). Moreover, both IL22 and IL10 protect gut mucosal immunity and act on the same receptors, loss of these cytokines may trigger the pathogenesis of long COVID and ME/CFS (301)(302).  These findings are in line not only with our earlier hypothesis but also with the results novel studies that have connected dysfunctional efferocytosis with fatiguing illnesses, including FM, ME/CFS, and GWIs [303-305]. “

 

Q: The conclusion can be longer and contain the actual conclusion of the study.

A: The conclusion section was expanded and includes this paragraph: “This research connects long COVID to other fatiguing illnesses, including FM, ME/CFS, and GWIs, emphasizing the role of microbial translocation outside the GI tract as the driver of these pathologies. In contrast, correcting the barrier function could ameliorate clinical symptoms as demonstrated in GWIs (293).”

 

 

Q: Also, an extensive language style and check is required.

A: Sent to MDPI:

 

 

 

 

 

 

 

 

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Congratulations