Differences in immunity and survival among non-small cell lung cancer patients: a gut microbiota perspective.

OBJECTIVE: This study aimed to investigate the relationship between key gut microbiota [Enterococcus, Escherichia coli (E. coli), Bifidobacterium, and Lactobacillus] and immune function in Chinese patients with non-small cell lung cancer (NSCLC). METHODS: This study included 208 patients with NSCLC enrolled between March 2021 and June 2023. Fecal samples were collected from patients for quantitative analysis of Enterococcus, E. coli, Bifidobacterium, and Lactobacillus. Additionally, peripheral blood samples were collected from patients, and levels of T lymphocyte subsets (CD3(+), CD4(+), and CD8(+)) were measured using flow cytometry. Analysis was conducted based on 6-month immune checkpoint inhibitor (ICI) efficacy and survival outcomes to examine the relationship between gut microbiota, immune function, and prognosis in NSCLC patients. Pearson correlation coefficients were used to investigate the interrelationships between microbial abundance and immune variables. RESULTS: In the immune checkpoint inhibitor (ICI) responders (R group), higher proportions of Bifidobacteria and Lactobacilli were observed, whereas non-responders (NR group) exhibited increased proportions of Enterococcus and E. coli. Furthermore, Bifidobacteria and Lactobacilli showed positive correlations with T cell counts but negative correlations with inflammatory cytokine levels. Opposing relationships were seen for Enterococcus and E. coli, which correlated negatively with T cells and positively with IL-6 and TNF-α (P < 0.05). CONCLUSION: In NSCLC, Bifidobacterium and Lactobacillus promote beneficial immune feedback loops by activating T cells and exerting anti-inflammatory effects, thereby supporting antitumor immunity.