From air pollution to lung cancer: Microbiota as a mediator in the malignant transformation of pulmonary nodules.

Air pollution contributes to the malignant transformation of pulmonary nodules and the development of lung cancer. Emerging evidence suggests that the lung is not a sterile environment, and that air pollution-induced dysbiosis may alter the composition and diversity of the lung microbiota. This review explores the pathway by which exposure to air pollution may contribute to respiratory tract dysbiosis, which in turn may alter the tumor microenvironment, disrupt immune homeostasis, and ultimately be implicated in the progression of pulmonary nodules. A model of "air pollution-microbiota dysbiosis-immune modulation-PN malignancy" is proposed. Regarding alterations in the tumor microenvironment and immune suppression, the roles of various cytokines (IL-1, IL-6, IFN-γ, TGF-β) and signaling pathways (PI3K/AKT, NF-κB, ERK) and the effects of immune suppression on T cells, natural killer cells, and macrophages were found. Additionally, the "oral-lung axis" contributes to the progression of PD-LC, with Porphyromonas gingivalis identified as a key biomarker and pathogenic driver. Additionally, treatment approaches such as immune checkpoint inhibition, antibiotic therapy, fecal microbiota transplantation, and probiotic therapy have all shown encouraging potential. This review highlights the pivotal role of dysbiosis in the air pollution-PN-LC axis, providing insights into novel pathogenic mechanisms and highlighting microbiota-targeted approaches for lung cancer prevention and treatment.