Introduction: Lung cancer is one of the most serious types of cancer with high rates of incidence and mortality. The gut microbiota has clinical implications on regulating the efficacy of natural anticancer agents. The aim of this study is to investigate the gut microbiota-mediated therapy as a helpful treatment for lung cancer.
Methods: This review article was performed within articles published at PubMed, Science Direct, Google Scholar, SID, and Cochrane until September 2022. The keywords were lung cancer, microbiota, and treatment. By searching this database; 53 articles were found, 19 of them by Reading titles and abstracts were removed. 34 articles were selected under the inclusion criteria. All articles were chosen from English and Persian articles.
Results: Finally, 34 articles were included in the study. Microbiota-derived antigens participated in pulmonary immune homeostasis. Ruminococcus gnavus stimulated secretion of IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) by colon tissues, those cytokines activated DCs and ILC2 to produce cytokines IL-4, IL-5, and IL-13 that traveled through the bloodstream to the lungs and could lead to infiltration of the lung parenchyma by eosinophils and mast cells. Butyrate-producing gut bacteria dampened lung group 2 innate lymphoid cell (ILC2) function, thus weakening the development of airway hyperreactivity. A reduction of intestinal microbial diversity and metabolic-related biological activities manifested in the intestinal flora of patients with lung cancer compared with healthy subjects. The enrichment of Bifidobacterium longum, Alistipes putredinis and Prevotella copri could lead to better immune checkpoint inhibitors efficacy. Parabacteroides and Methanobrevibacter predicted better lung cancer control. Bifidobacterium enhanced dendritic cell (DC) function and intensified accumulation of CD8(+) T cells in the tumor beds; thus, they exhibited antitumor capacity to the same degree as PD-L1 inhibitor, that combination treatment eliminated tumor outgrowth. Lactobacillus plantarum CIRM653 reduced the counts of lung innate immune cells, such as macrophages and neutrophils, TNF-α and IL-6, as well as triggering an immunosuppressive Treg cell response in the lungs that alleviated the lung inflammatory response in mouse models infected with Klebsiella pneumoniae . Clostridium butyricum, Lactobacillus rhamnosus GG, Bifidobacterium longum, Saccharomyces cerevisiae UFMG A-905 and Akkermansia muciniphila played a major role in lung health.
Conclusion: The microbiota components and metabolites affect host immune homeostasis locally and systematically. Manipulating the intestinal flora is a potential option for enhancing the efficacy of lung cancer treatment. However, need to be more research done on this topic.