The lung microbiota: role in maintaining pulmonary immune homeostasis and its implications in cancer development and therapy

Abstract

Like other body districts, lungs present a complex bacteria community. An emerging function of lung microbiota is to promote and maintain a state of immune tolerance, to prevent uncontrolled and not desirable inflammatory response caused by inhalation of harmless environmental stimuli. This effect is mediated by a continuous dialog between commensal bacteria and immune cells resident in lungs, which express a repertoire of sensors able to detect microorganisms. The same receptors are also involved in the recognition of pathogens and in mounting a proper immune response. Due to its important role in preserving lung homeostasis, the lung microbiota can be also considered a mirror of lung health status. Indeed, several studies indicate that lung bacterial composition drastically changes during the occurrence of pulmonary pathologies, such as lung cancer, and the available data suggest that the modifications of lung microbiota can be part of the etiology of tumors in lungs and can influence their progression and response to therapy. These results provide the scientific rationale to analyze lung microbiota composition as biomarker for lung cancer and to consider lung microbiota a new potential target for therapeutic intervention to reprogram the antitumor immune microenvironment. In the present review, we discussed about the role of lung microbiota in lung physiology and summarized the most relevant data about the relationship between lung microbiota and cancer.

Lung microbiome and coronavirus disease 2019 (COVID-19): Possible link and implications

“…Activation of lung immune cells that initiates innate and adaptive immunity requires microbe exposure [58] . The function of one of the vital effector and regulator cells of the lung, γδ T cells, depends on pathogen invasion [47] , [59] .…”

Versatile role of curcumin and its derivatives in lung cancer therapy

“…The escape of cancer cells from immune surveillance is associated with their tolerance and enhanced proliferation (Sommariva et at., 2020). The CD4+ CD25+ forkhead box protein‐3 (FOXP3) regulatory T cells (Treg) contribute to immune tolerance of cancer cells by production of TGF‐β and other cytokines to ensure the growth of cancer cells and their escape from cancer‐specific cytotoxic CD8+ T cells (B.‐Q.…”

Perspectives on Probiotics and Bronchopulmonary Dysplasia

“…The incipient composition of the lung microbiota cannot be neglected because it is closely related to the onset of mucosal immunity (18), the development of immune tolerance in the lungs (19), and healthy breathing (15). Several reports have shown alterations in the stability and diversity of the respiratory tract microbiota in BPD.…”