Next Article in Journal
Identification of Novel MET Exon 14 Skipping Variants in Non-Small Cell Lung Cancer Patients: A Prototype Workflow Involving in Silico Prediction and RT-PCR
Previous Article in Journal
FOLFOXIRI Resistance Induction and Characterization in Human Colorectal Cancer Cells
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Cancers
Volume 14
Issue 19
10.3390/cancers14194813
cancers-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

The Lung Microbiota and Lung Cancer: A Growing Relationship

by
Maroun Bou Zerdan
1,2,
Joseph Kassab
3,
Paul Meouchy
4,
Elio Haroun
5,
Rami Nehme
6,
Morgan Bou Zerdan
7,
Gracia Fahed
7,
Michael Petrosino
1,
Dibyendu Dutta
5,* and
Stephen Graziano
5,*
1
Department of Internal Medicine, SUNY Upstate Medical University, Syracuse, NY 13210, USA
2
Department of Hematology and Oncology, Cleveland Clinic Florida, Weston, FL 33326, USA
3
Faculty of Medicine, Saint-Joseph University, Beirut 11072180, Lebanon
4
Department of Internal Medicine, Naef K. Basile Cancer Institute, American University of Beirut Medical Center, Beirut 11072020, Lebanon
5
Department of Medicine, Division of Hematology and Oncology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
6
Department of Medicine, University of Pavia, 27100 Pavia, Italy
7
Faculty of Medicine, American University of Beirut, Beirut 11072020, Lebanon
*
Authors to whom correspondence should be addressed.
Cancers 2022, 14(19), 4813; https://doi.org/10.3390/cancers14194813
Submission received: 10 June 2022 / Revised: 15 September 2022 / Accepted: 27 September 2022 / Published: 1 October 2022
Browse Figures
Review Reports Versions Notes

Abstract

:

Simple Summary

In the past few years, the microbiota has emerged as a major player in cancer management. The efficacy of chemotherapy or immunotherapy may be influenced by the concomitant use of antibiotics before, during, or shortly after treatment with immune checkpoint inhibitors. Despite this, the mechanism linking the microbiota, host immunity, and malignancies are not clear, and the role of microbiota manipulation and analyses in cancer management is underway. In this manuscript, we discuss the role of the microbiota in the initiation, progression, and treatment outcomes of lung cancer.

Abstract

The lung is home to a dynamic microbial population crucial to modulating immune balance. Interest in the role of the lung microbiota in disease pathogenesis and treatment has exponentially increased. In lung cancer, early studies suggested an important role of dysbiosis in tumor initiation and progression. These results have helped accelerate research into the lung microbiota as a potential diagnostic marker and therapeutic target. Microbiota signatures could represent diagnostic biomarkers of early-stage disease. Lung microbiota research is in its infancy with a limited number of studies and only single-center studies with a significant methodological variation. Large, multicenter longitudinal studies are needed to establish the clinical potential of this exciting field.

1. Introduction

The microbiota is a collection of bacteria, fungi, and viruses that reside in or on the human body [1]. It is part of the innate immune system and modulates several mechanisms of host defense [2]. Dysbiosis refers to an alteration in the composition, diversity, or metabolites of the microbiota, which predisposes the body to a variety of diseases [3]. In the past decade, the bulk of microbiota research was confined to the gut and the skin, while the lungs were previously thought to be sterile [4]. In reality, the lungs harbor a community of bacteria (2.2 × 103 bacterial genomes per cm2) that largely consists of Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria [5,6]. The constitution of this microbiota is determined by the (a) immigration, (b) elimination, and (c) replication rates of the microorganisms [4]. In a healthy lung, microbial immigration and elimination are the predominant regulators of the microbiota [4]. In a diseased lung, the regional growth conditions that affect replication rates are the main processes governing microbiota constitution [4]. Figure 1 shows examples of those dynamics affecting microbiota constitution in a healthy and diseased lung. Host–microbiota interactions have an important role in modulating both innate and adaptive immune responses [7]. While the mechanisms behind the microbiota’s role in immune function have been substantially studied in the gastrointestinal tract, lung microbiota can have similar immune-modulating effects because both the gut and lung environments have similar properties (i.e., mucosal barrier and continuous exposure to the outside) [3].
The interaction between the host microbiota and the innate immune system relies on pattern recognition receptors (PRRs) that attach to microbial antigens. This interaction is mutually beneficial because (a) the microbiota provides a baseline stimulation of the innate immune system while regulating the release of cytokines, and (b) the innate immune system compartmentalizes the commensal bacteria while preventing the overgrowth of pathogenic strains [8]. The cytokines released by the innate immune system are also important for the differentiation of CD4 T cells into pro-inflammatory or regulatory T cells, which further implies that the microbiota can modulate the adaptive immune response [7]. A cohort study by Segal et al. supported this concept by showing that a higher load of supraglottic bacteria in the broncho-alveolar lavage (BAL) was associated with increased inflammatory cytokines and Th17 lymphocytes [9].

2. Lung Microbiota and Non-Cancerous Diseases

Dysbiosis in the lungs results from an abnormal alteration in migration, elimination, and/or regional growth factors affecting the microbiota [4]. For instance, gastroesophageal reflux disease increases microbial migration, while impaired mucociliary clearance (e.g., from smoking) decreases microbial elimination [10]. More importantly, dysbiosis from changes in regional growth conditions alters the commensal microorganism population [7]. This change can be reversed if the noxious stimulus is removed, or it can be irreversible if enough inflammatory damage to epithelial cells has occurred [1,11]. The latter situation leads to a self-perpetuating dysbiosis–inflammatory cycle: dysbiosis leads to airway inflammation, which further alters the environmental growth conditions and contributes to dysbiosis [7]. In addition, airway inflammation increases mucus production and permeability, which further worsens the bacterial burden through (a) increasing the supply of nutrients to the lungs and (b) creating areas of increased temperature and hypoxia [4,7]. This promotes the expansion of pathogenic bacterial strains (e.g., Pseudomonas) that are adapted to these conditions [4]. The microbiota has been implicated in the pathogenesis of chronic lung diseases such as chronic obstructive lung disease (COPD), asthma, cystic fibrosis, and idiopathic pulmonary fibrosis (IPF) [12]. All of these diseases are characterized by periods of acute exacerbations that can be induced by dysbiosis [12]. For example, Dicker et al. found that reduced microbial diversity along with Proteobacteria dominance (predominantly Haemophilus) was associated with worse COPD phenotypes and more frequent exacerbations [13]. Dysbiosis has been implicated in the development of emphysema. In a study, Li et al. demonstrated that emphysematous changes in mice accelerated after 20 weeks of exposure to intestinal microbiota of COPD patients [14]. However, there is minimal information in the literature on the role of dysbiosis in emphysema in relation to lung cancer development. In asthma, environmental factors (pollen, allergens, and pollutants) can cause bacterial dysbiosis and thereby promote exacerbation by activating inflammatory pathways, promoting bronchoconstriction, and increasing bronchial hyperresponsiveness [15]. Moreover, cystic fibrosis patients with diverse microbiota containing a low abundance but high prevalence of commensals showed the lowest levels of inflammatory markers (IL-1β, IL-8, TNF-α) and the highest levels of forced expiratory volume (FEV)1% predicted [16]. Similarly, in patients with IPF, lung bacterial burden predicted disease progression, and microbiota diversity and composition correlated with increased alveolar profibrotic cytokines [17].

3. Lung Microbiota and Lung Cancer Pathogenesis

The airway microbiota has a unique role in the initiation and progression of lung cancer. Germ-free or antibiotic-treated mice are significantly protected from lung cancer development due to Kras mutation and p53 loss [18]. Meanwhile, commensal bacteria were able to stimulate an inflammatory response (by activating γδ T cells) associated with the development of lung adenocarcinoma [18]. McLean et al. hypothesized that dysbiosis could induce carcinogenesis through three pathways: (a) impaired immune balance, (b) chronic inflammation, and (c) the induction of oncogenic pathways [7]. First, dysbiosis can disrupt the baseline stimulation of the immune system in the lungs. On the one hand, the depletion of microbial diversity impairs the priming of antigen-presenting cells, which hinders their ability to react to tumor antigens [11]. On the other hand, bacterial overgrowth causes the overstimulation of the immune system and uncontrolled proliferation of IL-17–producing CD4 helper T cells, which are key factors in lung tumorigenesis [19]. Second, dysbiosis causes chronic inflammation through DNA-damaging metabolites and genotoxins released by the affected commensal organisms [20]. The inflammatory cells stimulated by dysbiosis can also release reactive oxygen and nitrogen species that lead to angiogenesis and carcinogenesis [21]. Finally, several studies found that some species from the microbiota can directly induce oncogenic pathways (Table 1). Apopa et al. showed that PARP1 is upregulated in non-small cell lung cancer (NSCLC) tissues in the presence of the cyanobacterial toxin microcystin (a toxin produced by cyanobacteria) [22]. Tsay et al. also linked Streptococcus and Veillonella to the induction of the PI3K and Extracellular signal-regulated protein kinase (ERK) pathways involved in lung cancer [23]. Despite these promising results associating specific microbes with carcinogenesis, it is still difficult to differentiate between the microorganisms that are truly inducing oncogenic pathways and those that are just opportunistic colonizers of the tumor microenvironment [7]. Making this distinction is crucial for investigating the microbiota as a therapeutic target for lung cancer.

3.1. Lung Cancer Initiation

The microbiota is involved in the pathogenesis of cancer in various ways. Nonetheless, its implication in the development of lung cancer is still not well unraveled. A common hypothesis is that the lung microbiota could be directly oncogenic. Many explanations include the enhancement of mucosal inflammation or the promotion of immune dysregulation [56] (Figure 2). The key mechanism for the oncogenic potential of the lung microbiota remains the development of an inflammatory niche that favors carcinogenesis associated with multifactorial etiologies, including but not limited to environmental influences and the presence of underlying chronic diseases [21]. For example, COPD patients are at a higher risk of lung cancer. This chronic disease induces a state of microbial dysbiosis that allows for increased colonization and sustainment of an ongoing inflammatory state leading to carcinogenesis and cancer development [57]. Pathophysiology is resumed as follows. Bacterial byproducts and N-formyl peptides are potent chemo-attractive molecules that enhance monocyte and neutrophil recruitment, further increasing lung inflammation, loss of alveolar adhesion, and the destruction of lung parenchyma [11]. IL-6, a pro-inflammatory cytokine, and IL-8, a neutrophil recruitment cytokine, both increased in the setting of infection, are involved in tumorigenesis. They activate the NF-κB-1 pathway and promote cancerous cell proliferation, migration, and invasion [58]. Further notable examples include Helicobacter pylori, which is hypothesized to be associated with lung cancer development by prompting the production of pro-inflammatory cytokines such as IL-1, IL-6, and TNFa [59]. Bacteroides fragilis, a Gram-negative, anaerobic bacilli, activates STAT3 by Type 17 T-helper cells in mice, which supports lung cancer cell proliferation and angiogenesis [60,61]. Bacterial toxins secreted by the lung microbiota may be associated with tumorigenesis and genotoxicity [21]. Bacteroides fragilis, for example, is also responsible for the synthesis of the cytolethal distending toxin and the cytotoxic necrotizing factor-1, both of which are associated with failure of the DNA repair system [42]. The chemicals produced by different microorganisms, such as superoxide dismutase, are also involved in genomic instability [62].
Bacterial products may be implicated in carcinogenesis. Inactivated Escherichia coli induces Toll-like receptor 4 (TLR4) activation, which favors the proliferation of NSCLC cells in vivo. Hypothesized mechanisms include the upregulation of p38 MAPK and ERK1/2 signaling [63] and the stimulation of calcineurin expression [60,61]. The dysregulated MAPK pathway over-activates RAF and RAS signaling molecules, leading to uncontrolled cell proliferation and resistance to apoptosis via the ERK protein, a transcription factor that mediates survival gene expression. Further supporting evidence to the hypothesis that dysbiosis in the tumor microenvironment may play a role in the metabolism and metabolic signaling of cancerous cells in the lung includes but is not limited to the following: Yu et al. demonstrated that the lung microbiota in lung cancer patients had an altered metabolic profile. There was a decrease in the amount of KEGG modules of energy metabolism and ATP-binding-cassette type transport with increased amino acid and lipid metabolism. These changes impact the expressions in epithelial respiratory cells, promoting carcinogenesis [64,65]. Another important pathway involved in the initiation of lung cancer includes the PI3K signaling pathway. Tsay et al. exposed human adenocarcinoma cells (A549) to bacterial products directly extracted from lung cancer patients that upregulated the genes involved in the PI3K pathway. Such changes are consistent with alternations observed in lung cancer patients as compared to the unaffected population [23]. PI3K activation is an early, reversible event in lung tumorigenesis. The PI3K/AKT pathway is an intracellular signaling pathway that regulates a variety of cellular functions, including cell survival, metabolism, and growth. Extracellular signaling molecules bind to several receptors located in the cell membrane, leading to receptor activation. This activates intracellular PI3K, which in turn converts PIP2 lipids to PIP3. AKT then binds to PIP3, which can be phosphorylated by PDK1 and mTOR at two distinct sites, leading to the full activation of AKT. pAKT phosphorylates several downstream molecules, including BAD, IKK, CREB, FOXO1, and mTORC1, that regulate numerous cellular processes. The dysfunction of this pathway can lead to the overactivation of the pathway and has been linked to numerous pathological processes, including tumorigenesis [66].
The lung microbiota can shape the immune microenvironment and favor tumor growth. Using an autochthonous genetically-engineered mouse model (GEMM) of lung adenocarcinoma, Jin et al. shed light on the role of the microbiota–immune crosstalk involved in inflammation and cancer genesis [18]. Disrupted local microbiota prompted the proliferation and activation of lung γδ T cells (which represent ‘unconventional’ T cells that represent a relatively small subset of T cells in peripheral blood) using an IL-1β and IL-23-dependent mechanism. This subset of T cells produces IL-17 (not to be confused with T-Helper 17 cells), which promotes neutrophil recruitment and inflammation within the tumor microenvironment [18]. The use of systemic antibiotic treatment to reduce microbiota burden and/or the blocking of the γδ T cells signaling pathways (with blocking of IL17 production) reduced tumor growth within the lung [18,67].

3.2. Lung Cancer Progression

The microbiota also plays an undoubtable role in lung cancer metastasis. Streptococcus and Veillonella can promote the metastasis of lung cancer cells by upregulating the ERK and PI3K pathways (as is also seen in the initiation of lung cancer) in epithelial respiratory cells [23]. Wang et al. demonstrated that, in patients infected by Mycobacteria tuberculosis, the ubiquitins found in host cells could activate protein–tyrosine–phosphatase A (PTPA), which favors the migration of human lung adenocarcinoma cells [68]. Additionally, inflammation-related mechanisms can further promote the metastasis of lung cancer. Gram-positive Pneumonia favors NSCLC dissemination via TLR2 activation [69]. As for immunity-related mechanisms, decreased bacterial load is associated with lower amounts of T-reg cells and enhanced helper T-cell and NK cell recruitment, resulting in reduced lung cancer metastases [67]. Human lung microbiota can also enhance angiogenesis via numerous inflammatory factors, further promoting the progression of the disease [70]. The described mechanisms of neovascularization include but are not limited to sprouting angiogenesis and vasculogenesis. The microbiota participates in the abovementioned angiogenesis mechanism via numerous mediators. Vascular endothelial growth factor (VEGF), endothelial cells (EC), inflammatory factors, and cells are the main components. Cui et al. demonstrated that mice treated with fecal microbiota transplantation showed an increased expression of VEGF that increased angiogenesis [71]. Moreover, in the CCSPcre/K-rasG12D mouse lung cancer model exposed to non-typable Haemophillus influenzae lysate weekly, the proportion of T-Helper 17 cells in the lung was significantly increased [19]. T-Helper 17 cells secrete numerous cytokines, most importantly IL-17, IL-21, and IL-22. IL-17 can promote angiogenesis by favoring the release of angiogenic mediators, cytokines, and chemokines. Helicobacter pylori can also promote the vascularization of lung carcinoma. VacA, an exotoxin produced by this incurvated rod, is found in the lung and can favor the release of IL-8 and IL-6 by lung cells [72,73]. In addition to being a neutrophilic chemotactic factor, IL-8 is a promoting factor for tumor angiogenesis [72,73]. Human papilloma virus (HPV) type 16 can also promote angiogenesis in lung cancer cells in vitro. Plausible explanations include the PI3K/Akt signaling pathway and c-Jun [72,73]. Finally, a study by Ushio et al. demonstrated that Mycoplasma-infected cells have a higher ability to metastasize in vivo than non-Mycoplasma-infected cells. It can be due to the changes in the expression of cell surface proteins which promote metastasis in cancer cells, and changes occurring in host cells influenced by Mycoplasma infection. Monoclonal antibodies targeting Mycoplasma proteins p37 and Ag 243-5 enhanced tumor cell invasiveness and decreased contact inhibition [74].

4. Microbiota as a Therapeutic Target in Lung Cancer

The current treatments of lung cancer are categorized into radiotherapy, chemotherapy, immunotherapy, and surgical resection [75]. However, despite the advances in lung cancer treatment, a substantial number of patients are diagnosed with advanced-stage disease and, unfortunately, suffer from poor prognosis and limited treatment options [76]. Therefore, it is essential to identify early diagnosis strategies and optimize the treatment options for lung cancer. The existing investigations about the clinical applications of microorganisms in lung cancer treatment are still in the early stages. However, deciphering the interplay between lung cancer and the lung/gut microbiota might revolutionize lung cancer treatment. In this section, we will summarize recent advances highlighting the microbiota as a therapeutic target for cancers, with a special focus on lung cancer.

4.1. Microbiota and Immunotherapy

Programmed death 1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) inhibitors are examples of monoclonal antibodies commonly used in cancer immunotherapy, particularly in advanced NSCLC [77,78,79]. These immune checkpoint inhibitors (ICIs) reverse immunosuppression in the tumor microenvironment by inhibiting the interaction of T cell suppressing receptors with their corresponding ligands on cancer cells.
In addition, ICIs modulate the immune system to enhance the capacity of effector T cells, mainly CD8+ cytotoxic T cells, to identify and recognize tumor-specific antigens, inducing cell death [80]. Recent studies have highlighted the role of microbiota as a leading actor in cancer immunotherapy response. Intestinal dysbiosis, whether due to a disease or due to antibiotic use, may negatively affect the immunotherapeutic response [81,82]. Antibiotics, in particular, can have dueling effects on cancer immunotherapy and treatment outcomes [83]. Since the gut microbiota influence local and systemic antitumor immune response by modulating PRRs, PAMPs, and DAMPs, dysbiosis may have a negative impact on immunotherapy. Dysbiosis can also preferentially select infectious strains of Clostridioides difficile, vancomycin-resistant enterococci (VRE), extended-spectrum beta-lactamase (ESBL) organisms, and carbapenem-resistant enterococci (CRE) bacteria and Candida species, in the gut. These organisms can severely affect treatment and survival outcomes. Alternately, antibiotics can semi-selectively correct dysbiosis that may have originally contributed to the malignancy and improve mucosal immune response to immunotherapy. The supplementation of gut commensals potentiates immunotherapy and decreases tumor burden. The oral gavage of Bacteroides fragilis in mice with melanoma stimulated a specific T cell response that enhanced the efficacy of CTLA-4 blockade [84]. Similarly, oral probiotic supplementation of Bifidobacterium re-sensitized tumors to anti-PDL1 therapy in melanoma-carrying mice by stimulating anti-tumor CD8+ cytotoxic T cell activity and inducing dendritic cell maturation [85].
Routy et al. analyzed the microbiota of 249 cancer patients diagnosed with either urothelial carcinoma, advanced NSCLC, or RCC on PD-1 immunotherapy. Antibiotics were given to 69 patients for common indications (dental, urinary, and pulmonary infections). Antibiotics-treated patients had reduced overall survival and shorter cancer recurrence time than those who did not receive antibiotics within the PD-1 treatment period. This suggests that antibiotic consumption can decrease the effectiveness of immunotherapy [86]. Commensals Akkermansia muciniphila and Enterococcus hira were abundant in the stools of PD-1 responders and were most significantly associated with favorable clinical outcomes in NSCLC [86]. PD-1 blockade was reinstated after fecal transfer from recovered patients into antibiotics-treated mice with melanoma. A similar result was observed after colonizing mice intestines with Akkermansia muciniphila and Enterococcus hira under several conditions of gut dysbiosis. An enhanced CD4 T cell and IL-12 response is probably responsible for the observed outcomes [86]. Other studies have also shown similar effects of gut microbiota on cancer immunotherapy [87,88]. In another study with advanced NSCLC patients with a good response to anti-PD1, higher gut microbiota diversity was observed compared to the non-responders [89]. The better immunotherapy response was due to an enhanced memory CD8+ T cell and natural killer cell subsets in the peripheral circulation of responders [89]. These studies reveal an important relationship between the efficacy of immunotherapy and dysbiosis of gut microbiota, which, if improved, can decrease the tumor burden and improve overall survival.

4.2. Microbiota and Chemotherapy

Similar to immunotherapy, studies have shown that the microbiota can positively or negatively influence the effectiveness of chemotherapeutic agents on various cancers, including lung neoplasms.
Among the members of lung microbiota, Mycoplasma preferentially colonizes tumors because of the nutrient-rich tumor microenvironment and its suitability for small, cell wall-lacking bacteria [90,91]. In fact, up to 100% of surgically removed lung cancer tissues have been found to be Mycoplasma-infected, indicating a strong association between Mycoplasma infection and carcinogenesis [92]. Intratumoral Mycoplasma decreases the efficacy of the nucleoside analog gemcitabine, a chemotherapeutic drug used in the treatment of NSCLC. Mycoplasma possesses a cytidine deaminase (CDA), which contributes to the degradation of gemcitabine [93] and, thus, decreases its efficacy. Moreover, Gammaproteobacteria, which also preferentially colonize tumors, have CDA such as Mycoplasma, and thus induce comparable resistance to certain antimetabolites [94].
The Gammaproteobacteria E. coli decreases gemcitabine efficacy in cell cultures, as well as abrogated the anti-tumor response to the antinucleotide in colon cancer mice models as compared with non-infected mice, which showed better response to gemcitabine [94]. Nonetheless, the fluoroquinolone antibiotic ciprofloxacin did restore gemcitabine efficacy in mice infected by CDA-producing bacteria, mainly Mycoplasma or Proteobacteria [94].
Although some microbial families in the lung may confer resistance to cancer therapy, others in the gut are needed for treatments to be fully effective. For instance, lung cancer mice models treated with an antibiotic cocktail, which destroys host commensal microflora, were found to be less responsive to cisplatin and had a significantly reduced survival rate; whereas mice supplemented with Lactobacillus probiotics followed by cisplatin therapy had smaller tumors with an improved survival rate [95]. Gene expression studies suggested that antibiotics impair the function of cisplatin by upregulating the expression of VEGF and downregulating the expression of BAX and CDKN1B. This dysregulation is commonly seen in lung cancer patients leading to angiogenesis and the inhibition of apoptosis, thus promoting tumor development [95]. Moreover, the expression of IFN-γ, granzymes (GZMB), and perforins (PRF1) in the CD8+ T cells in these mice models were reduced after antibiotic treatment, suggesting an immunostimulatory role of the commensal microbiota [95]. In opposition, lung cancer mice models treated with the combination of cisplatin and Lactobacillus had lower levels of VEGF, higher levels of apoptosis-promoting BAX, and enhanced the expression of CD8 T cells IFN-γ, GZMB, and PRF1; hence slowing tumor progression [95].
Additional evidence in human studies highlights the importance of healthy gut microbiota for effective cancer therapy. The chemotherapeutic agent cyclophosphamide generated better progression-free survival in advanced lung cancer patients whose gut microbiota contains Enterococcus hirae. In fact, cyclophosphamide induces damage to the epithelial barrier, leading to the generation of an effective anti-tumor IFN-γ and IL-17 response [96]. E. hirae can form a memory T-helper 1 cell response that enhances cyclophosphamide’s action and increase its efficacy.

5. Future Directions

The future of microbiota research in lung cancer is very promising and is progressing in two major directions. First, deciphering the microbiota constitution and how it evolves in the processes of lung cancer initiation and progression would help in developing early diagnostic markers. Second, the exploration and exploitation of the host–microbiota interactions may serve as potential targets for lung cancer treatment [24]. Microbiota can be manipulated in three ways to influence lung cancer treatment [97]. Fecal microbiota transplant (FMT) can reverse dysbiosis by restoring normal gut microbiota composition. It also reduces CDI and improves cancer therapy efficacy. Preclinical studies have demonstrated the potential of FMT in improving cancer treatment outcomes in colorectal cancer [98], melanoma [99], NSCLC, and renal cancer [86]. FMT also shows graft-vs-host disease (GvHD) resolution [100,101]. Multiple clinical trials utilizing FMT in patients with malignancies to improve chemotherapy or immune checkpoint inhibitor efficacy in AML, metastatic melanoma, prostate cancer, and renal cell carcinoma are underway.
Antibiotic stewardship can achieve semi-selective modification of intestinal microbiota. Reducing the usage of broad-spectrum antibiotics, especially early in the process of treatment, can be detrimental, as has been observed in both preclinical and clinical settings [87]. Antibiotic stewardship can preserve microbiota diversity and decrease unwanted microbial density and inflammation. For example, prophylactic treatment with the minimally absorbed antibiotic rifaximin is under investigation to assess the reduction of anticancer treatment-associated gastrointestinal toxicity and diarrhea in colon adenocarcinoma (NCT04003181), colorectal cancer (NCT03563586), and stage I-III human epidermal growth factor receptor 2 (HER2)-positive breast cancer (NCT04249622) [97].
The replenishment or enrichment of commensals to create a more balanced microbiota composition can also be achieved using pre- and probiotics. Such biologic modification of the gut microbiota population can improve dysbiosis-related complications in cancer and cancer treatment outcomes. For example, one of the major complications of cancer treatment is the damage to the mucosal barrier that not only diminishes chemo- and immunotherapy effects but also often contributes to bacteremia and candidemia. The probiotic supplementation of bacteria that improves intestinal barrier function can help mitigate such problems. Akkermansia muciniphila is a Gram-negative bacterium that fortifies the mucosal layer and maintains gut barrier function. A. muciniphila modulates TLR2- expressing cells [102], improve insulin sensitivity [103], and alter the response to anti-PD-1 treatment [86]. Other bacterial species that confer intestinal barrier function improvement by producing short-chain fatty acids are Faecalibacterium (butyrate producer) and Bifidobacterium (lactic acid and acetic acid producer). Pre- and probiotics that directly or indirectly enrich microbiota with gut barrier function improving bacteria are under investigation to determine their beneficial impact on cancer treatment. For example, Myrciaria dubia, a prebiotic that enriches A. muciniphila is being investigated for immune checkpoint inhibitions in NSCLC and melanoma patients (NCT05303493). The probiotic Lactobacillus Bifidobacterium V9(Kex02) is being explored for improving the efficacy of Carilizumab combined with platinum in NSCLC (NCT05094167). The combined mechanism of FMT and biologic modification of microbiota is in a clinical trial where pooled fecal microbiota with enriched Faecalibacterium prausnitzii, Bifidobacterium longum, A. muciniphila, and Fusobacterium spp. is being investigated to improve the effectiveness of PD-1 therapy in advanced lung cancer patients (NCT04924374).
While the prospects of microbiota exploitation in lung cancer treatment are promising, there are concerns regarding the standardization of the procedures [7]. Furthermore, the knowledge about the interactions between various members of the microbiota themselves and between the host cells under normal and stressed conditions such as cigarette smoking [24] is still eluding.

Author Contributions

Conceptualization, M.B.Z. (Maroun Bou Zerdan), S.G. and D.D.; writing—original draft preparation, M.B.Z. (Maroun Bou Zerdan), J.K., P.M., E.H. and R.N.; writing—review and editing, M.B.Z. (Morgan Bou Zerdan), M.P. and G.F. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Conflicts of Interest

The authors declare no conflict of interest.

Abbreviations

BALBroncho-alveolar lavage
BAXBcl-2-associated X protein
CDACytidine deaminase
CDK1NBCyclin-dependent kinase inhibitor 1B
COPDChronic obstructive lung disease
CTLA-4Cytotoxic T-lymphocyte-associated protein 4
ECendothelial cells
ERKExtracellular signal-regulated kinases
GEMMgenetically engineered mouse models
GZMBGranzyme B
Her2human epidermal growth factor receptor 2
FEVForced expiratory volume
FMTFecal microbiota transplant
ICIImmune checkpoint inhibitor
IFN-γInterferon gamma
ILInterleukin
IPFIdiopathic pulmonary fibrosis
KEGGKyoto Encyclopedia of Genes and Genomes
MAPKMitogen-activated protein kinase
NF-κB-1Nuclear factor kappa B subunit 1
NSCLCNon-small-cell lung cancer
RCCRenal cell carcinoma
PARP1Poly [ADP-ribose] polymerase 1
PD-1Programmed cell death protein 1
PD-L1Programmed death-ligand 1
PFR1Perforin 1
PI3KPhosphoinositide 3-kinase
PRRsPattern recognition receptors
PTPAprotein-tyrosine-phosphatase A
TNFTumor necrosis factor
STAT3Signal transducer and activator of transcription 3
TLR4Toll-like receptor 4
TNFaTumor necrosis factor alfa
VEGFVascular endothelial growth factor

References

  1. Ocáriz-Díez, M.; Cruellas, M.; Gascón, M.; Lastra, R.; Martínez-Lostao, L.; Ramírez-Labrada, A.; Paño, J.R.; Sesma, A.; Torres, I.; Yubero, A. Microbiota and Lung Cancer. Opportunities and Challenges for Improving Immunotherapy Efficacy. Front. Oncol. 2020, 10, 1945. [Google Scholar] [CrossRef] [PubMed]
  2. Ansaldo, E.; Farley, T.K.; Belkaid, Y. Control of immunity by the microbiota. Annu. Rev. Immunol. 2021, 39, 449–479. [Google Scholar] [CrossRef] [PubMed]
  3. Liu, N.-N.; Ma, Q.; Ge, Y.; Yi, C.-X.; Wei, L.-Q.; Tan, J.-C.; Chu, Q.; Li, J.-Q.; Zhang, P.; Wang, H. Microbiome dysbiosis in lung cancer: From composition to therapy. NPJ Precis. Oncol. 2020, 4, 1–12. [Google Scholar] [CrossRef] [PubMed]
  4. Dickson, R.P.; Erb-Downward, J.R.; Martinez, F.J.; Huffnagle, G.B. The microbiome and the respiratory tract. Annu. Rev. Physiol. 2016, 78, 481–504. [Google Scholar] [CrossRef] [Green Version]
  5. Sender, R.; Fuchs, S.; Milo, R. Revised estimates for the number of human and bacteria cells in the body. PLoS Biol. 2016, 14, e1002533. [Google Scholar] [CrossRef] [Green Version]
  6. Fabbrizzi, A.; Amedei, A.; Lavorini, F.; Renda, T.; Fontana, G. The lung microbiome: Clinical and therapeutic implications. Intern. Emerg. Med. 2019, 14, 1241–1250. [Google Scholar] [CrossRef] [Green Version]
  7. McLean, A.E.; Kao, S.C.; Barnes, D.J.; Wong, K.K.; Scolyer, R.A.; Cooper, W.A.; Kohonen-Corish, M.R. The Emerging Role of the Lung Microbiome and its importance in Non-Small Cell Lung Cancer Diagnosis and Treatment. Lung Cancer 2022, 165, 124–132. [Google Scholar] [CrossRef]
  8. Zheng, D.; Liwinski, T.; Elinav, E. Interaction between microbiota and immunity in health and disease. Cell Res. 2020, 30, 492–506. [Google Scholar] [CrossRef]
  9. Segal, L.N.; Clemente, J.C.; Tsay, J.-C.J.; Koralov, S.B.; Keller, B.C.; Wu, B.G.; Li, Y.; Shen, N.; Ghedin, E.; Morris, A. Enrichment of the lung microbiome with oral taxa is associated with lung inflammation of a Th17 phenotype. Nat. Microbiol. 2016, 1, 1–11. [Google Scholar] [CrossRef] [Green Version]
  10. Sommariva, M.; Le Noci, V.; Bianchi, F.; Camelliti, S.; Balsari, A.; Tagliabue, E.; Sfondrini, L. The lung microbiota: Role in maintaining pulmonary immune homeostasis and its implications in cancer development and therapy. Cell. Mol. Life Sci. 2020, 77, 2739–2749. [Google Scholar] [CrossRef] [Green Version]
  11. Bingula, R.; Filaire, M.; Radosevic-Robin, N.; Bey, M.; Berthon, J.-Y.; Bernalier-Donadille, A.; Vasson, M.-P.; Filaire, E. Desired turbulence? Gut-lung axis, immunity, and lung cancer. J. Oncol. 2017, 2017, 5035371. [Google Scholar] [CrossRef] [PubMed]
  12. O’Dwyer, D.N.; Dickson, R.P.; Moore, B.B. The lung microbiome, immunity, and the pathogenesis of chronic lung disease. J. Immunol. 2016, 196, 4839–4847. [Google Scholar] [CrossRef] [Green Version]
  13. Dicker, A.J.; Huang, J.T.; Lonergan, M.; Keir, H.R.; Fong, C.J.; Tan, B.; Cassidy, A.J.; Finch, S.; Mullerova, H.; Miller, B.E. The sputum microbiome, airway inflammation, and mortality in chronic obstructive pulmonary disease. J. Allergy Clin. Immunol. 2021, 147, 158–167. [Google Scholar] [CrossRef] [PubMed]
  14. Li, N.; Dai, Z.; Wang, Z.; Deng, Z.; Zhang, J.; Pu, J.; Cao, W.; Pan, T.; Zhou, Y.; Yang, Z. Gut microbiota dysbiosis contributes to the development of chronic obstructive pulmonary disease. Respir. Res. 2021, 22, 1–15. [Google Scholar] [CrossRef] [PubMed]
  15. Hufnagl, K.; Pali-Schöll, I.; Roth-Walter, F.; Jensen-Jarolim, E. Dysbiosis of the gut and lung microbiome has a role in asthma. Semin. Immunopathol. 2020, 42, 75–93. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  16. Frey, D.L.; Boutin, S.; Dittrich, S.A.; Graeber, S.Y.; Stahl, M.; Wege, S.; Herth, F.J.; Sommerburg, O.; Schultz, C.; Mall, M.A. Relationship between airway dysbiosis, inflammation and lung function in adults with cystic fibrosis. J. Cyst. Fibros. 2021, 20, 754–760. [Google Scholar] [CrossRef]
  17. O’Dwyer, D.N.; Ashley, S.L.; Gurczynski, S.J.; Xia, M.; Wilke, C.; Falkowski, N.R.; Norman, K.C.; Arnold, K.B.; Huffnagle, G.B.; Salisbury, M.L. Lung microbiota contribute to pulmonary inflammation and disease progression in pulmonary fibrosis. Am. J. Respir. Crit. Care Med. 2019, 199, 1127–1138. [Google Scholar] [CrossRef]
  18. Jin, C.; Lagoudas, G.K.; Zhao, C.; Bullman, S.; Bhutkar, A.; Hu, B.; Ameh, S.; Sandel, D.; Liang, X.S.; Mazzilli, S. Commensal microbiota promote lung cancer development via γδ T cells. Cell 2019, 176, 998–1013.e16. [Google Scholar] [CrossRef] [Green Version]
  19. Chang, S.H.; Mirabolfathinejad, S.G.; Katta, H.; Cumpian, A.M.; Gong, L.; Caetano, M.S.; Moghaddam, S.J.; Dong, C. T helper 17 cells play a critical pathogenic role in lung cancer. Proc. Natl. Acad. Sci. USA 2014, 111, 5664–5669. [Google Scholar] [CrossRef] [Green Version]
  20. Goto, T. Airway microbiota as a modulator of lung cancer. Int. J. Mol. Sci. 2020, 21, 3044. [Google Scholar] [CrossRef]
  21. Maddi, A.; Sabharwal, A.; Violante, T.; Manuballa, S.; Genco, R.; Patnaik, S.; Yendamuri, S. The microbiome and lung cancer. J. Thorac. Dis. 2019, 11, 280. [Google Scholar] [CrossRef] [PubMed]
  22. Apopa, P.L.; Alley, L.; Penney, R.B.; Arnaoutakis, K.; Steliga, M.A.; Jeffus, S.; Bircan, E.; Gopalan, B.; Jin, J.; Patumcharoenpol, P. PARP1 is up-regulated in non-small cell lung cancer tissues in the presence of the cyanobacterial toxin microcystin. Front. Microbiol. 2018, 9, 1757. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  23. Tsay, J.-C.J.; Wu, B.G.; Badri, M.H.; Clemente, J.C.; Shen, N.; Meyn, P.; Li, Y.; Yie, T.-A.; Lhakhang, T.; Olsen, E. Airway microbiota is associated with upregulation of the PI3K pathway in lung cancer. Am. J. Respir. Crit. Care Med. 2018, 198, 1188–1198. [Google Scholar] [CrossRef] [PubMed]
  24. Dong, Q.; Chen, E.S.; Zhao, C.; Jin, C. Host-microbiome interaction in lung cancer. Front. Immunol. 2021, 12, 1956. [Google Scholar] [CrossRef]
  25. Brenner, D.R.; McLaughlin, J.R.; Hung, R.J. Previous lung diseases and lung cancer risk: A systematic review and meta-analysis. PLoS ONE 2011, 6, e17479. [Google Scholar] [CrossRef]
  26. Seiler, C.L.; Song, J.M.; Fernandez, J.; Abrahante, J.E.; Kono, T.J.; Chen, Y.; Ren, Y.; Kassie, F.; Tretyakova, N.Y. Epigenetic changes in alveolar type II lung cells of A/J mice following intranasal treatment with lipopolysaccharide. Chem. Res. Toxicol. 2019, 32, 831–839. [Google Scholar] [CrossRef]
  27. Matson, V.; Fessler, J.; Bao, R.; Chongsuwat, T.; Zha, Y.; Alegre, M.-L.; Luke, J.J.; Gajewski, T.F. The commensal microbiome is associated with anti–PD-1 efficacy in metastatic melanoma patients. Science 2018, 359, 104–108. [Google Scholar] [CrossRef] [Green Version]
  28. Budden, K.F.; Shukla, S.D.; Rehman, S.F.; Bowerman, K.L.; Keely, S.; Hugenholtz, P.; Armstrong-James, D.P.; Adcock, I.M.; Chotirmall, S.H.; Chung, K.F. Functional effects of the microbiota in chronic respiratory disease. Lancet Respir. Med. 2019, 7, 907–920. [Google Scholar] [CrossRef]
  29. Dickson, R.P.; Erb-Downward, J.R.; Freeman, C.M.; McCloskey, L.; Falkowski, N.R.; Huffnagle, G.B.; Curtis, J.L. Bacterial topography of the healthy human lower respiratory tract. MBio 2017, 8, e02287-16. [Google Scholar] [CrossRef]
  30. Sabbula, B.R.; Anjum, F. Squamous Cell Lung Cancer. In StatPearls [Internet]; StatPearls Publishing: Tampa, FL, USA, 2021. [Google Scholar]
  31. Mantovani, A.; Allavena, P.; Sica, A.; Balkwill, F. Cancer-related inflammation. Nature 2008, 454, 436–444. [Google Scholar] [CrossRef]
  32. Torre, L.A.; Siegel, R.L.; Jemal, A. Lung cancer statistics. In Lung Cancer and Personalized Medicine; Springer: Cham, Switzerland, 2016; pp. 1–19. [Google Scholar]
  33. Herbst, R.S.; Baas, P.; Kim, D.-W.; Felip, E.; Pérez-Gracia, J.L.; Han, J.-Y.; Molina, J.; Kim, J.-H.; Arvis, C.D.; Ahn, M.-J. Pembrolizumab versus docetaxel for previously treated, PD-L1-positive, advanced non-small-cell lung cancer (KEYNOTE-010): A randomised controlled trial. Lancet 2016, 387, 1540–1550. [Google Scholar] [CrossRef]
  34. Moffatt, M.F.; Cookson, W.O. The lung microbiome in health and disease. Clin. Med. 2017, 17, 525. [Google Scholar] [CrossRef] [PubMed]
  35. Gur, C.; Ibrahim, Y.; Isaacson, B.; Yamin, R.; Abed, J.; Gamliel, M.; Enk, J.; Bar-On, Y.; Stanietsky-Kaynan, N.; Coppenhagen-Glazer, S. Binding of the Fap2 protein of Fusobacterium nucleatum to human inhibitory receptor TIGIT protects tumors from immune cell attack. Immunity 2015, 42, 344–355. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  36. Chu, S.; Cheng, Z.; Yin, Z.; Xu, J.; Wu, F.; Jin, Y.; Yang, G. Airway Fusobacterium is Associated with Poor Response to Immunotherapy in Lung Cancer. Onco Targets Ther. 2022, 15, 201. [Google Scholar] [CrossRef] [PubMed]
  37. Qian, K.; Deng, Y.; Krimsky, W.S.; Feng, Y.-G.; Peng, J.; Tai, Y.-H.; Peng, H.; Jiang, L.-H. Airway Microbiota in Patients With Synchronous Multiple Primary Lung Cancer: The Bacterial Topography of the Respiratory Tract. Front. Oncol. 2022, 12, 811279. [Google Scholar] [CrossRef] [PubMed]
  38. Surette, M.G. The cystic fibrosis lung microbiome. Ann. Am. Thorac. Soc. 2014, 11, S61–S65. [Google Scholar] [CrossRef]
  39. Segal, L.; Alekseyenko, A.; Clemente, J.; Kulkarni, R.; Wu, B.; Chen, H.; Berger, K.; Goldring, R.; Rom, W.; Blaser, M. Enrichment of lung microbiome with supraglottic taxa is associated with increased pulmonary inflammation. Microbiome 2013, 1, 19. [Google Scholar] [CrossRef] [Green Version]
  40. Atanasova, K.R.; Yilmaz, Ö. Looking in the Porphyromonas gingivalis cabinet of curiosities: The microbium, the host and cancer association. Mol. Oral Microbiol. 2014, 29, 55–66. [Google Scholar] [CrossRef] [Green Version]
  41. Liu, Y.; Yuan, X.; Chen, K.; Zhou, F.; Yang, H.; Yang, H.; Qi, Y.; Kong, J.; Sun, W.; Gao, S. Clinical significance and prognostic value of Porphyromonas gingivalis infection in lung cancer. Transl. Oncol. 2021, 14, 100972. [Google Scholar] [CrossRef]
  42. Martins, D.; Mendes, F.; Schmitt, F. Microbiome: A supportive or a leading actor in lung cancer? Pathobiology 2021, 88, 198–207. [Google Scholar] [CrossRef]
  43. Jungnickel, C.; Schnabel, P.A.; Bohle, R.; Wiewrodt, R.; Herr, C.; Bals, R.; Beisswenger, C. Nontypeable Haemophilus influenzae–Promoted Proliferation of Kras-Induced Early Adenomatous Lesions Is Completely Dependent on Toll-Like Receptor Signaling. Am. J. Pathol. 2017, 187, 973–979. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  44. Moon, D.C.; Choi, C.H.; Lee, S.M.; Lee, J.H.; Kim, S.I.; Kim, D.S.; Lee, J.C. Nuclear translocation of Acinetobacter baumannii transposase induces DNA methylation of CpG regions in the promoters of E-cadherin gene. PLoS ONE 2012, 7, e38974. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  45. Hattar, K.; Reinert, C.P.; Sibelius, U.; Gökyildirim, M.Y.; Subtil, F.S.; Wilhelm, J.; Eul, B.; Dahlem, G.; Grimminger, F.; Seeger, W. Lipoteichoic acids from Staphylococcus aureus stimulate proliferation of human non-small-cell lung cancer cells in vitro. Cancer Immunol. Immunother. 2017, 66, 799–809. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  46. Ren, Y.; Su, H.; She, Y.; Dai, C.; Xie, D.; Narrandes, S.; Huang, S.; Chen, C.; Xu, W. Whole genome sequencing revealed microbiome in lung adenocarcinomas presented as ground-glass nodules. Transl. Lung Cancer Res. 2019, 8, 235. [Google Scholar] [CrossRef] [PubMed]
  47. Huang, D.H.; He, J.; Su, X.F.; Wen, Y.N.; Zhang, S.J.; Liu, L.Y.; Zhao, H.; Ye, C.P.; Wu, J.H.; Cai, S. The airway microbiota of non-small cell lung cancer patients and its relationship to tumor stage and EGFR gene mutation. Thorac. Cancer 2022, 13, 858–869. [Google Scholar] [CrossRef]
  48. Higuchi, R.; Goto, T.; Hirotsu, Y.; Otake, S.; Oyama, T.; Amemiya, K.; Mochizuki, H.; Omata, M. Streptococcus australis and Ralstonia pickettii as Major Microbiota in Mesotheliomas. J. Pers. Med. 2021, 11, 297. [Google Scholar] [CrossRef]
  49. Druzhinin, V.; Matskova, L.; Demenkov, P.; Baranova, E.; Volobaev, V.; Minina, V.; Larionov, A.; Titov, V.; Fucic, A. Genetic damage in lymphocytes of lung cancer patients is correlated to the composition of the respiratory tract microbiome. Mutagenesis 2021, 36, 143–153. [Google Scholar] [CrossRef]
  50. Li, K.-j.; Chen, Z.-l.; Huang, Y.; Zhang, R.; Luan, X.-q.; Lei, T.-t.; Chen, L. Dysbiosis of lower respiratory tract microbiome are associated with inflammation and microbial function variety. Respir. Res. 2019, 20, 1–16. [Google Scholar] [CrossRef]
  51. Greathouse, K.L.; White, J.R.; Vargas, A.J.; Bliskovsky, V.V.; Beck, J.A.; von Muhlinen, N.; Polley, E.C.; Bowman, E.D.; Khan, M.A.; Robles, A.I. Interaction between the microbiome and TP53 in human lung cancer. Genome Biol. 2018, 19, 1–16. [Google Scholar] [CrossRef]
  52. Ran, Z.; Liu, J.; Wang, F.; Xin, C.; Xiong, B.; Song, Z. Pulmonary Micro-Ecological Changes and Potential Microbial Markers in Lung Cancer Patients. Front. Oncol. 2021, 10, 3085. [Google Scholar] [CrossRef]
  53. Leng, Q.; Holden, V.K.; Deepak, J.; Todd, N.W.; Jiang, F. Microbiota biomarkers for lung cancer. Diagnostics 2021, 11, 407. [Google Scholar] [CrossRef] [PubMed]
  54. Cheng, C.; Wang, Z.; Wang, J.; Ding, C.; Sun, C.; Liu, P.; Xu, X.; Liu, Y.; Chen, B.; Gu, B. Characterization of the lung microbiome and exploration of potential bacterial biomarkers for lung cancer. Transl. Lung Cancer Res. 2020, 9, 693. [Google Scholar] [CrossRef] [PubMed]
  55. Perrone, F.; Belluomini, L.; Mazzotta, M.; Bianconi, M.; Di Noia, V.; Meacci, F.; Montrone, M.; Pignataro, D.; Prelaj, A.; Rinaldi, S. Exploring the role of respiratory microbiome in lung cancer: A systematic review. Crit. Rev. Oncol. Hematol. 2021, 164, 103404. [Google Scholar] [CrossRef] [PubMed]
  56. Picardo, S.L.; Coburn, B.; Hansen, A.R. The microbiome and cancer for clinicians. Crit. Rev. Oncol. Hematol. 2019, 141, 1–12. [Google Scholar] [CrossRef]
  57. de Groot, P.M.; Wu, C.C.; Carter, B.W.; Munden, R.F. The epidemiology of lung cancer. Transl. Lung Cancer Res. 2018, 7, 220. [Google Scholar] [CrossRef]
  58. Lin, W.-W.; Karin, M. A cytokine-mediated link between innate immunity, inflammation, and cancer. J. Clin. Investig. 2007, 117, 1175–1183. [Google Scholar] [CrossRef] [Green Version]
  59. Koshiol, J.; Flores, R.; Lam, T.K.; Taylor, P.R.; Weinstein, S.J.; Virtamo, J.; Albanes, D.; Perez-Perez, G.; Caporaso, N.E.; Blaser, M.J. Helicobacter pylori seropositivity and risk of lung cancer. PLoS ONE 2012, 7, e32106. [Google Scholar] [CrossRef] [Green Version]
  60. Mao, Q.; Jiang, F.; Yin, R.; Wang, J.; Xia, W.; Dong, G.; Ma, W.; Yang, Y.; Xu, L.; Hu, J. Interplay between the lung microbiome and lung cancer. Cancer Lett. 2018, 415, 40–48. [Google Scholar] [CrossRef]
  61. Wu, S.; Rhee, K.-J.; Albesiano, E.; Rabizadeh, S.; Wu, X.; Yen, H.-R.; Huso, D.L.; Brancati, F.L.; Wick, E.; McAllister, F. A human colonic commensal promotes colon tumorigenesis via activation of T helper type 17 T cell responses. Nat. Med. 2009, 15, 1016–1022. [Google Scholar] [CrossRef]
  62. Carbonero, F.; Benefiel, A.C.; Alizadeh-Ghamsari, A.H.; Gaskins, H.R. Microbial pathways in colonic sulfur metabolism and links with health and disease. Front. Physiol. 2012, 3, 448. [Google Scholar] [CrossRef] [Green Version]
  63. Chow, S.C.; Gowing, S.D.; Cools-Lartigue, J.J.; Chen, C.B.; Berube, J.; Yoon, H.W.; Chan, C.H.; Rousseau, M.C.; Bourdeau, F.; Giannias, B. Gram negative bacteria increase non-small cell lung cancer metastasis via toll-like receptor 4 activation and mitogen-activated protein kinase phosphorylation. Int. J. Cancer 2015, 136, 1341–1350. [Google Scholar] [CrossRef] [PubMed]
  64. Yu, G.; Gail, M.H.; Consonni, D.; Carugno, M.; Humphrys, M.; Pesatori, A.C.; Caporaso, N.E.; Goedert, J.J.; Ravel, J.; Landi, M.T. Characterizing human lung tissue microbiota and its relationship to epidemiological and clinical features. Genome Biol. 2016, 17, 1–12. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  65. Liu, F.; Li, J.; Guan, Y.; Lou, Y.; Chen, H.; Xu, M.; Deng, D.; Chen, J.; Ni, B.; Zhao, L. Dysbiosis of the gut microbiome is associated with tumor biomarkers in lung cancer. Int. J. Biol. Sci. 2019, 15, 2381. [Google Scholar] [CrossRef]
  66. Gustafson, A.M.; Soldi, R.; Anderlind, C.; Scholand, M.B.; Qian, J.; Zhang, X.; Cooper, K.; Walker, D.; McWilliams, A.; Liu, G. Airway PI3K pathway activation is an early and reversible event in lung cancer development. Sci. Transl. Med. 2010, 2, 26ra25. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  67. Le Noci, V.; Guglielmetti, S.; Arioli, S.; Camisaschi, C.; Bianchi, F.; Sommariva, M.; Storti, C.; Triulzi, T.; Castelli, C.; Balsari, A. Modulation of pulmonary microbiota by antibiotic or probiotic aerosol therapy: A strategy to promote immunosurveillance against lung metastases. Cell Rep. 2018, 24, 3528–3538. [Google Scholar] [CrossRef] [Green Version]
  68. Wang, J.; Ge, P.; Qiang, L.; Tian, F.; Zhao, D.; Chai, Q.; Zhu, M.; Zhou, R.; Meng, G.; Iwakura, Y. The mycobacterial phosphatase PtpA regulates the expression of host genes and promotes cell proliferation. Nat. Commun. 2017, 8, 1–16. [Google Scholar] [CrossRef]
  69. Gowing, S.D.; Chow, S.C.; Cools-Lartigue, J.J.; Chen, C.B.; Najmeh, S.; Jiang, H.Y.; Bourdeau, F.; Beauchamp, A.; Mancini, U.; Angers, I. Gram-positive pneumonia augments non-small cell lung cancer metastasis via host toll-like receptor 2 activation. Int. J. Cancer 2017, 141, 561–571. [Google Scholar] [CrossRef] [Green Version]
  70. Liu, X.; Cheng, Y.; Zang, D.; Zhang, M.; Li, X.; Liu, D.; Gao, B.; Zhou, H.; Sun, J.; Han, X. The role of gut microbiota in lung cancer: From carcinogenesis to immunotherapy. Front. Oncol. 2021, 11, 3118. [Google Scholar] [CrossRef]
  71. Cui, M.; Xiao, H.; Li, Y.; Zhou, L.; Zhao, S.; Luo, D.; Zheng, Q.; Dong, J.; Zhao, Y.; Zhang, X. Faecal microbiota transplantation protects against radiation-induced toxicity. EMBO Mol. Med. 2017, 9, 448–461. [Google Scholar] [CrossRef]
  72. Nakashima, S.; Kakugawa, T.; Yura, H.; Tomonaga, M.; Harada, T.; Hara, A.; Hara, S.; Nakano, M.; Yamasaki, E.; Sakamoto, N. Identification of Helicobacter pylori VacA in human lung and its effects on lung cells. Biochem. Biophys. Res. Commun. 2015, 460, 721–726. [Google Scholar] [CrossRef] [Green Version]
  73. Zhang, E.; Feng, X.; Liu, F.; Zhang, P.; Liang, J.; Tang, X. Roles of PI3K/Akt and c-Jun signaling pathways in human papillomavirus type 16 oncoprotein-induced HIF-1α, VEGF, and IL-8 expression and in vitro angiogenesis in non-small cell lung cancer cells. PLoS ONE 2014, 9, e103440. [Google Scholar] [CrossRef] [PubMed]
  74. Hamada, S.; Ooshima, T.; Torii, M.; Imanishi, H.; Masuda, N.; Sobue, S.; Kotani, S. Dental Caries Induction in Experimental Animls by Clinical Strains of Streptococcus mutans Isolated from Japanese Children. Microbiol. Immunol. 1978, 22, 301–314. [Google Scholar] [CrossRef] [PubMed]
  75. Jones, G.S.; Baldwin, D.R. Recent advances in the management of lung cancer. Clin. Med. Lond 2018, 18, s41–s46. [Google Scholar] [CrossRef] [PubMed]
  76. Walters, S.; Maringe, C.; Coleman, M.P.; Peake, M.D.; Butler, J.; Young, N.; Bergstrom, S.; Hanna, L.; Jakobsen, E.; Kolbeck, K.; et al. Lung cancer survival and stage at diagnosis in Australia, Canada, Denmark, Norway, Sweden and the UK: A population-based study, 2004–2007. Thorax 2013, 68, 551–564. [Google Scholar] [CrossRef] [Green Version]
  77. Reck, M.; Rodriguez-Abreu, D.; Robinson, A.G.; Hui, R.; Csoszi, T.; Fulop, A.; Gottfried, M.; Peled, N.; Tafreshi, A.; Cuffe, S.; et al. Pembrolizumab versus Chemotherapy for PD-L1-Positive Non-Small-Cell Lung Cancer. N. Engl. J. Med. 2016, 375, 1823–1833. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  78. Brahmer, J.; Reckamp, K.L.; Baas, P.; Crino, L.; Eberhardt, W.E.; Poddubskaya, E.; Antonia, S.; Pluzanski, A.; Vokes, E.E.; Holgado, E.; et al. Nivolumab versus Docetaxel in Advanced Squamous-Cell Non-Small-Cell Lung Cancer. N. Engl. J. Med. 2015, 373, 123–135. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  79. Shen, K.; Cui, J.; Wei, Y.; Chen, X.; Liu, G.; Gao, X.; Li, W.; Lu, H.; Zhan, P.; Lv, T.; et al. Effectiveness and safety of PD-1/PD-L1 or CTLA4 inhibitors combined with chemotherapy as a first-line treatment for lung cancer: A meta-analysis. J. Thorac. Dis. 2018, 10, 6636–6652. [Google Scholar] [CrossRef]
  80. Pardoll, D.M. The blockade of immune checkpoints in cancer immunotherapy. Nat. Rev. Cancer 2012, 12, 252–264. [Google Scholar] [CrossRef] [Green Version]
  81. Gopalakrishnan, V.; Helmink, B.A.; Spencer, C.N.; Reuben, A.; Wargo, J.A. The Influence of the Gut Microbiome on Cancer, Immunity, and Cancer Immunotherapy. Cancer Cell 2018, 33, 570–580. [Google Scholar] [CrossRef] [Green Version]
  82. Zitvogel, L.; Ma, Y.; Raoult, D.; Kroemer, G.; Gajewski, T.F. The microbiome in cancer immunotherapy: Diagnostic tools and therapeutic strategies. Science 2018, 359, 1366–1370. [Google Scholar] [CrossRef] [Green Version]
  83. Ghanem, S.; Kim, C.; Dutta, D.; Salifu, M.; Lim, S. Antimicrobial therapy during cancer treatment: Beyond antibacterial effects. J. Intern. Med. 2021, 290, 40–56. [Google Scholar] [CrossRef] [PubMed]
  84. Vetizou, M.; Pitt, J.M.; Daillere, R.; Lepage, P.; Waldschmitt, N.; Flament, C.; Rusakiewicz, S.; Routy, B.; Roberti, M.P.; Duong, C.P.; et al. Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota. Science 2015, 350, 1079–1084. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  85. Sivan, A.; Corrales, L.; Hubert, N.; Williams, J.B.; Aquino-Michaels, K.; Earley, Z.M.; Benyamin, F.W.; Lei, Y.M.; Jabri, B.; Alegre, M.L.; et al. Commensal Bifidobacterium promotes antitumor immunity and facilitates anti-PD-L1 efficacy. Science 2015, 350, 1084–1089. [Google Scholar] [CrossRef] [Green Version]
  86. Routy, B.; Le Chatelier, E.; Derosa, L.; Duong, C.P.M.; Alou, M.T.; Daillere, R.; Fluckiger, A.; Messaoudene, M.; Rauber, C.; Roberti, M.P.; et al. Gut microbiome influences efficacy of PD-1-based immunotherapy against epithelial tumors. Science 2018, 359, 91–97. [Google Scholar] [CrossRef] [Green Version]
  87. Ahmed, J.; Kumar, A.; Parikh, K.; Anwar, A.; Knoll, B.M.; Puccio, C.; Chun, H.; Fanucchi, M.; Lim, S.H. Use of broad-spectrum antibiotics impacts outcome in patients treated with immune checkpoint inhibitors. Oncoimmunology 2018, 7, e1507670. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  88. Derosa, L.; Hellmann, M.D.; Spaziano, M.; Halpenny, D.; Fidelle, M.; Rizvi, H.; Long, N.; Plodkowski, A.J.; Arbour, K.C.; Chaft, J.E.; et al. Negative association of antibiotics on clinical activity of immune checkpoint inhibitors in patients with advanced renal cell and non-small-cell lung cancer. Ann. Oncol. 2018, 29, 1437–1444. [Google Scholar] [CrossRef]
  89. Jin, Y.; Dong, H.; Xia, L.; Yang, Y.; Zhu, Y.; Shen, Y.; Zheng, H.; Yao, C.; Wang, Y.; Lu, S. The Diversity of Gut Microbiome is Associated With Favorable Responses to Anti-Programmed Death 1 Immunotherapy in Chinese Patients With NSCLC. J. Thorac. Oncol. 2019, 14, 1378–1389. [Google Scholar] [CrossRef]
  90. Vande Voorde, J.; Balzarini, J.; Liekens, S. Mycoplasmas and cancer: Focus on nucleoside metabolism. EXCLI J. 2014, 13, 300–322. [Google Scholar]
  91. Jiang, S.; Zhang, S.; Langenfeld, J.; Lo, S.C.; Rogers, M.B. Mycoplasma infection transforms normal lung cells and induces bone morphogenetic protein 2 expression by post-transcriptional mechanisms. J. Cell Biochem. 2008, 104, 580–594. [Google Scholar] [CrossRef]
  92. Apostolou, P.; Tsantsaridou, A.; Papasotiriou, I.; Toloudi, M.; Chatziioannou, M.; Giamouzis, G. Bacterial and fungal microflora in surgically removed lung cancer samples. J. Cardiothorac. Surg. 2011, 6, 137. [Google Scholar] [CrossRef] [Green Version]
  93. Ciccolini, J.; Serdjebi, C.; Peters, G.J.; Giovannetti, E. Pharmacokinetics and pharmacogenetics of Gemcitabine as a mainstay in adult and pediatric oncology: An EORTC-PAMM perspective. Cancer Chemother. Pharmacol. 2016, 78, 1–12. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  94. Geller, L.T.; Barzily-Rokni, M.; Danino, T.; Jonas, O.H.; Shental, N.; Nejman, D.; Gavert, N.; Zwang, Y.; Cooper, Z.A.; Shee, K.; et al. Potential role of intratumor bacteria in mediating tumor resistance to the chemotherapeutic drug gemcitabine. Science 2017, 357, 1156–1160. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  95. Gui, Q.F.; Lu, H.F.; Zhang, C.X.; Xu, Z.R.; Yang, Y.H. Well-balanced commensal microbiota contributes to anti-cancer response in a lung cancer mouse model. Genet. Mol. Res. 2015, 14, 5642–5651. [Google Scholar] [CrossRef] [PubMed]
  96. Daillere, R.; Vetizou, M.; Waldschmitt, N.; Yamazaki, T.; Isnard, C.; Poirier-Colame, V.; Duong, C.P.M.; Flament, C.; Lepage, P.; Roberti, M.P.; et al. Enterococcus hirae and Barnesiella intestinihominis Facilitate Cyclophosphamide-Induced Therapeutic Immunomodulatory Effects. Immunity 2016, 45, 931–943. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  97. Dutta, D.; Lim, S.H. Bidirectional interaction between intestinal microbiome and cancer: Opportunities for therapeutic interventions. Biomark. Res. 2020, 8, 1–15. [Google Scholar] [CrossRef] [PubMed]
  98. Couturier-Maillard, A.; Secher, T.; Rehman, A.; Normand, S.; De Arcangelis, A.; Haesler, R.; Huot, L.; Grandjean, T.; Bressenot, A.; Delanoye-Crespin, A. NOD2-mediated dysbiosis predisposes mice to transmissible colitis and colorectal cancer. J. Clin. Investig. 2013, 123, 700–711. [Google Scholar] [CrossRef] [Green Version]
  99. Gopalakrishnan, V.; Spencer, C.N.; Nezi, L.; Reuben, A.; Andrews, M.; Karpinets, T.; Prieto, P.; Vicente, D.; Hoffman, K.; Wei, S.C. Gut microbiome modulates response to anti–PD-1 immunotherapy in melanoma patients. Science 2018, 359, 97–103. [Google Scholar] [CrossRef] [Green Version]
  100. Kakihana, K.; Fujioka, Y.; Suda, W.; Najima, Y.; Kuwata, G.; Sasajima, S.; Mimura, I.; Morita, H.; Sugiyama, D.; Nishikawa, H. Fecal microbiota transplantation for patients with steroid-resistant acute graft-versus-host disease of the gut. Blood J. Am. Soc. Hematol. 2016, 128, 2083–2088. [Google Scholar] [CrossRef]
  101. Qi, X.; Li, X.; Zhao, Y.; Wu, X.; Chen, F.; Ma, X.; Zhang, F.; Wu, D. Treating steroid refractory intestinal acute graft-vs.-host disease with fecal microbiota transplantation: A pilot study. Front. Immunol. 2018, 9, 2195. [Google Scholar] [CrossRef]
  102. Plovier, H.; Everard, A.; Druart, C.; Depommier, C.; Van Hul, M.; Geurts, L.; Chilloux, J.; Ottman, N.; Duparc, T.; Lichtenstein, L. A purified membrane protein from Akkermansia muciniphila or the pasteurized bacterium improves metabolism in obese and diabetic mice. Nat. Med. 2017, 23, 107–113. [Google Scholar] [CrossRef] [Green Version]
  103. Depommier, C.; Everard, A.; Druart, C.; Plovier, H.; Van Hul, M.; Vieira-Silva, S.; Falony, G.; Raes, J.; Maiter, D.; Delzenne, N.M. Supplementation with Akkermansia muciniphila in overweight and obese human volunteers: A proof-of-concept exploratory study. Nat. Med. 2019, 25, 1096–1103. [Google Scholar] [CrossRef] [PubMed]
Cancers 14 04813 g001 550
Figure 1. Three factors affecting the dynamics of host microbiota constitution in the lungs: immigration, elimination, and regional growth factors.
Figure 1. Three factors affecting the dynamics of host microbiota constitution in the lungs: immigration, elimination, and regional growth factors.
Cancers 14 04813 g001
Cancers 14 04813 g002 550
Figure 2. Lung Cancer and Microbiota. Local microbiota plays a critical role in the pathogenesis of lung cancer. Derived metabolites act as signaling molecules, directly amplifying tumor-intrinsic pathways. They can also induce immune dysregulation by favoring inflammation and immunosuppression.
Figure 2. Lung Cancer and Microbiota. Local microbiota plays a critical role in the pathogenesis of lung cancer. Derived metabolites act as signaling molecules, directly amplifying tumor-intrinsic pathways. They can also induce immune dysregulation by favoring inflammation and immunosuppression.
Cancers 14 04813 g002
Table
Table 1. Lung and Gut Bacterial Species in association to Lung Cancer.
Table 1. Lung and Gut Bacterial Species in association to Lung Cancer.
Bacterial ClassificationSampling MethodAssociation with Lung CancerPotential Mechanism of Association with Lung Cancer
Pseudomonas
[24,25,26,27,28,29]		Lung explants, BAL, Brush specimen, lung tissuesMarked presence in lung adenocarcinomaAssociated with an increase in macrophage population and IFN-γ in BAL sample. Amplification of neutrophil elastase activity. Enhanced/diminished population associated with smoking
Streptococcus
[24,25,27,30,31,32,33,34]		Lung explants, BAL, Brush specimen, lung tissuesMarked presence in lung cancer, specifically adenocarcinoma, squamous cell carcinoma, and increased risk of hepatic metastasis from NSCLC
Increased levels in the gut of small cell lung cancer patients 		Enhanced ERK and PI3K pathway. Increased presence of Th17 cells and neutrophils.
Enhanced/ diminished population in smokers
Prevotella
[24,25,30,31,32,33,34]		Lung explants, BAL, Brush specimenLow presence in the gut of NSCLC patients. Marked presence in the gut of squamous cell carcinoma patients
Marked presence in lung cancer and adenocarcinoma		Correlated to an inflammatory phenotype, including an enhanced Th17 lymphocyte and neutrophil response
Enhancement of ERK and PI3K pathway
Fusobacterium
[25,31,32,33,35,36,37]		Lung explants, BAL, Brush specimenPoor response in lung cancer to anti-PD-1 therapy if Fusobacterium is present in the airway.
One of the most abundant specific bacterial community members detected in synchronous multiple primary lung cancer sMPLC lesions.		Fap2 protein of Fusobacterium inhibits natural killer cell killing by interacting with an inhibitory receptor present on all human NK cells and on various T cells (TIGIT receptor)
Veillonella
[24,25,27,31,38,39]		Lung explants, BAL, Brush specimen, lung tissues, salivaObserved in both small cell lung cancer and adenocarcinomaCorrelated to an inflammatory phenotype, including an enhanced Th17 lymphocyte and neutrophil response.
Most abundant agent driving dysbiosis and amplification of IL17, PI3K, MAPK, and ERK pathways in the airway transcriptome
Prophyromonas
[25,26,31,40,41]		Lung explants, BAL, Brush specimenHigher P. gingivalis staining in carcinoma tissues of patients with small cell lung cancer, lung adenocarcinoma, and lung squamous cell carcinoma (35.00%, 26.89%, and 39.00%, respectively) compared to the adjacent lung tissuesActivation of cancer-associated transcription factors by modulating ATP-induced cytosolic, mitochondrial ROS, and antioxidant glutathione response through the inhibition of ATP/ P2X7-induced cell death by P. gingivalis.
Neisseria
[25,42]		Lung explants, BAL, Brush specimen, salivaReduced presence in lung cancerSuppress cell growth
Haemophilus
[25,26,43]		Lung explants, BALStimulates proliferation of early adenomatous lesions leading to alveolar adenomatous hyperplasia and adenocarcinomaUpregulation of IL-17C and neutrophil infiltration. Can also promote metastatic progression in combination with cigarette smoke (8)
Sphingomonas
[26,27]		BAL, Brush specimen, lung tissuesMarked presence in adenocarcinomaAssociated with an increase in macrophage population and prominent IFN-γ population
Acinetobacter
[25,26,34,44]		Lung explants, BALMarked presence in lung cancer and adenocarcinomaDNA methylation of CpG regions in the promoters of E-cadherin gene induced by A. baumannii transposase (Tnp) and down-regulation of this gene
Staphylococcus
[25,28,45]		Lung explants, BAL, Brush specimen, lung tissuesMarked presence in the gut of NSCLC patients responsive to NivolumabLipoteichoic acid induced cellular proliferation and liberation of interleukin (IL)-8.
Corynebacterium
[25,26,31,46]		Lung explants, BAL, Brush specimenNo significant difference in microbiota composition between ground glass pulmonary nodules and normal tissues except in adenocarcinoma (AD) -
Lactobacillus
[24,26,27,31]		BAL, Brush specimen, lung tissuesLow levels in the gut of NSCLC patients (8). High abundance in the gut of squamous cell carcinoma patientsGut microbiota’s role in regulating the lung’s immune response.
Actinobacillus
[24,26,31,47]		Lung explants, BAL, salivaIncrease in the gut of lung cancer patients and commonly found in the lungs and sputum of lung cancer patientsActinobacillus’ presence in the airway leads to chronic lung inflammation promoting the initiation and early development of lung cancer.
Propionibacterium
[26,47] 		BALMarked presence in the gut of NSCLC patients responsive to Nivolumab
Marked presence in squamous cell carcinoma		Gut microbiota’s role in regulating the lung’s immune response.
Ralstonia
[29,48]		Lung tissuesMarked presence in adenocarcinoma Plays a role in impairing the tumor microenvironment’s immunity
Megasphaera
[39,49]		BALMarked presence in lung cancer patientsPromotes somatic cell genome instability via high levels of chromosomal aberrations (CAs) and micronuclei (MN) frequency seen in peripheral blood lymphocytes of patients with lung cancer
Acidovorax
[50,51]		Lung tissuesA marked presence in squamous cell carcinoma patients compared with adenocarcinoma. Specific taxa are more common in smokers with TP53 mutationDegrades tobacco smoke compounds and thus promoting survival of transformed cells and subsequent tumor development.
Malignant transformation of the lung epithelium via DNA damage and mutations in TP53, mediated by microbial toxins or reactive oxygen/nitrogen.
Capnocytophaga
[52,53,54]		SalivaA marked increase in lungs of lung cancer patients compared to control Stimulation of chronic inflammation, thus promoting the development of lung cancer, especially lung squamous cell carcinoma
Cyanobacteria
[52,55]		Lung tissueA marked increase in lungs of adenocarcinoma patientsCyanobacteria toxin microcystin is associated with reduced CD36 and increased levels of PARP1
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Bou Zerdan, M.; Kassab, J.; Meouchy, P.; Haroun, E.; Nehme, R.; Bou Zerdan, M.; Fahed, G.; Petrosino, M.; Dutta, D.; Graziano, S. The Lung Microbiota and Lung Cancer: A Growing Relationship. Cancers 2022, 14, 4813. https://doi.org/10.3390/cancers14194813

AMA Style

Bou Zerdan M, Kassab J, Meouchy P, Haroun E, Nehme R, Bou Zerdan M, Fahed G, Petrosino M, Dutta D, Graziano S. The Lung Microbiota and Lung Cancer: A Growing Relationship. Cancers. 2022; 14(19):4813. https://doi.org/10.3390/cancers14194813

Chicago/Turabian Style

Bou Zerdan, Maroun, Joseph Kassab, Paul Meouchy, Elio Haroun, Rami Nehme, Morgan Bou Zerdan, Gracia Fahed, Michael Petrosino, Dibyendu Dutta, and Stephen Graziano. 2022. "The Lung Microbiota and Lung Cancer: A Growing Relationship" Cancers 14, no. 19: 4813. https://doi.org/10.3390/cancers14194813

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop