Diagnostic Value of Imaging and Serological Biomarkers in Pulmonary Sarcoidosis

Round 1

Reviewer 1 Report

An adequate differential diagnosis of the expressed parameters is not proposed. How do ACE inhibitors or angiotensin antagonists used in high blood pressure affect ACE levels?

Are hematopoietic cell ratios not affected in other infectious or granulomatous processes?

Calcium alterations must be accompanied by an adequate study of renal, bone and parathyroid function, to ensure that the disorder can be primarily related to sarcoidosis.

How these parameters are impacted after treatment is not described.

Author Response

Dear reviewer:

Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes in the manuscript. The yellow part that has been revised according to your comments. Revision notes, point to point, are given as follows:

Comments 1: An adequate differential diagnosis of the expressed parameters is not proposed. How do ACE inhibitors or angiotensin antagonists used in high blood pressure affect ACE levels?

Thanks for the reviewer's suggestion, the following supplement is made to the effect of ACEI on ACE level.

Response 1: Widely used antihypertensive drugs, such as ACE inhibitors (ACEI), can reduce serum ACE levels, resulting in false negative results. In a large sarcoidosis study, it was found that ACE activity could be measured at different serum dilutions to explore the effect of ACEI on ACE levels. With increasing dilution, the concentration of ACEI in serum gradually decreased, resulting in a gradual loss of inhibitory effect. Ideally, significant dilution of serum could be used to simulate the state of patients without taking drugs, so that the level of uninhibited enzyme activity in patients' serum could be determined objectively without interrupting drug therapy. However, Angiotensin Receptor Blocker (ARB) do not affect ACE activity.

Comments 2: Are hematopoietic cell ratios not affected in other infectious or granulomatous processes?

Thanks to the questions raised by the reviewer, we add the following to analyze changes in hematopoietic cell ratio in other infectious or granulomatous processes.

Response 2: Platelet-to-lymphocyte ratio (PLR) is an inflammatory marker in immune-mediated, metabolic, prethrombotic, and neoplastic diseases. In the respiratory system, PLR has diagnostic value for respiratory syncytial virus (RSV) infection in children under 2 years old and influenza A virus infection in children (all P<0.001). Among children under 2 years of age, the median PLR was 72.17 (49.63-108.26) in the RSV-positive group, and 119.31 (90.32-223.07) in the RSV-negative group. The results showed that the PLR level in the RSV-positive group was significantly lower than that in the RSV-negative group (p<0.001). When the PLR level was below 73, the specificity for diagnosing RSV infection in children was more than 90%. However, PLR levels were increased in patients with sarcoidosis. Studies on influenza A virus infection in children showed that PLR levels were also increased, and the cut-off value was 124, with sensitivity and specificity of 56.70% and 89.60%, respectively; while the cut-off value of PLR for predicting sarcoidosis was 158.

In a systematic review and meta-analysis, studies have shown that neutrophil-to-lymphocyte ratio (NLR) can be used for the diagnosis of acute appendicitis and the assessment of the severity of the disease. NLR >4.7 was identified as a predictor of acute appendicitis, with a sensitivity of 88.89%, a specificity of 90.91%, and an AUC of 0.96 (P < 0.0001). While, in the study of Celalettin Korkmaz et al., it was found that the NLR level in patients with sarcoidosis (3.26±2.13) was significantly higher than that in the control group (2.45±2.41), with a cut-off value of 2.07 (P < 0.001). In addition, this study also showed a strong positive correlation between NLR and BAL CD4+/CD8+ ratio (r = 0.65, P = 0.01).

When using these serological biomarkers, it is necessary to exclude the case of comorbidity such as acute inflammation and malignant tumor. In most cases, biopsy is still needed to confirm the diagnosis, so these biomarkers are only supportive. More prospective studies are needed to explore the cut-off value of serological biomarkers in the diagnosis of sarcoidosis in the future.

Comments 3: Calcium alterations must be accompanied by an adequate study of renal, bone and parathyroid function, to ensure that the disorder can be primarily related to sarcoidosis.

Thanks to the reviewer's suggestion, we add the following to confirm that hypercalcemia is associated with sarcoidosis.

Response 3: Hypercalcemia is caused by increased bone resorption, decreased renal calcium clearance, and increased gastrointestinal calcium uptake. The parathyroid hormone (PTH) and vitamin D regulate bone mobilization, renal excretion, and intestinal calcium uptake to maintain calcium homeostasis. About 90% of patients with hypercalcemia have primary hyperparathyroidism or malignant tumors. Other causes of hypercalcemia include granulomatous diseases (such as sarcoidosis), genetic diseases, and medications (such as thiazide diuretics) and so on. Therefore, hypercalcemia is not a specific manifestation of sarcoidosis, and other possible causes need to be investigated. In primary hyperparathyroidism, the level of parathyroid hormone (PTH) is elevated. Measuring the 24-hour urinary calcium level can help assess the kidney's ability to process calcium. Elevated serum alkaline phosphatase (ALP) levels may be associated with abnormal bone metabolism. The joint detection of these indicators can be used to Identify the cause of hypercalcemia.

Comments 4: How these parameters are impacted after treatment is not described.

Thanks to the reviewer's suggestion, we add the changes of indicators after treatment to make the article more complete.

Response 4: A study of patients with sarcoidosis treated with methotrexate showed that serum levels of angiotensin converting enzyme (ACE) and soluble IL-2 receptor (sIL-2R) were reduced after 6 months of treatment and correlated with increased lung function.

In a study on the relationship between hematological parameters and treatment response in patients with sarcoidosis, 75 patients were observed, 42 (56%) of whom received methylprednisolone, methotrexate, infliximab Medications such as monoclonal antibodies, topical steroids, or nonsteroidal anti-inflammatory drugs. Results showed progression in 3 patients. However, there were no significant differences in NLR and PLR outcomes between patients who responded to treatment and those who did not improve (P=0.39, P=0.51, respectively).

Thank you for the above suggestions and we look forward to your input into my manuscript. Thanks again for your comments and suggestions!

Reviewer 2 Report

first I would like to congratulate the authors on completion of this manuscript.   I think this review has a very limited scope and should be improved

1. please expand the acronym CT - computed tomography in the heading or sub headings

2. in imaging please mention about the role of FDG-PET CT in sarcoid, role of cardiac mri in cardiac sarcoid, mai brain in neurosarcoid

3. please mention common symptoms of sarcoid in addition to mentioning that symptoms vary

4. also add role of other serum biomarkers like neuter-in, YKL40, sCD 163, serum amyloid, chitotriosidase

5. can also add biomarkers in bronchoalveolar lavage fluid like cd4/cd8 ratio, KL6, CXCL 9,10,11 etc

6. add section about future biomarkers like DOTA-PET, mTOR signaling, JAK/STAT signaling etc

7. add a table to summarize the biomarkers

8. consider adding example hrct chest or pet-ct image in sarcoid

biopsy still is required in majority of cases to make a definitive diagnosis and these biomarkers are only supportive

minor English revision is needed

Author Response

Please see attached.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has improved significantly. Few suggestions. In the biomarker table, separate the imaging studies from the serum biomarkers (give different headings to both). Change section 3 heading from ‘outlook’ to ‘conclusion’

Proofread and minor english editing required

Author Response

Please refer to the attachment.

Author Response File: Author Response.pdf