Clostridium Butyricum and butyrate enhance PD-1 inhibitor therapy in non-small cell lung cancer by regulating the HDAC1/ID2/IL-12R pathway.

BACKGROUND: PD-1 blockade has become an important immunotherapeutic strategy, its clinical efficacy in non-small cell lung cancer (NSCLC) remains suboptimal. This study explores the effect and mechanism of sodium butyrate (NaB) and Clostridium butyricum (C. butyricum) combined with PD-1 inhibitors in NSCLC. METHODS: We established an NSCLC mouse model and evaluated tumor size, histopathology, apoptosis, cell proliferation, inflammatory factors, immune cell populations, and proteins of the HDAC1/ID2/IL-12R axis in the tumor, along with gut microbiome profiling. RESULTS: A combination of NaB or C. butyricum with PD-1 inhibitors significantly inhibited tumor growth and increased spleen and thymus indices. The combinations promoted tumor cell apoptosis, reduced the number of Ki67-positive proliferating cells, and increased IL-2, IL-6, IL-12, TNF-α, and IFN-γ levels in tumor tissues and serum. Additionally, the infiltration of CD4+and CD8+ T cells in the tumor increased, while the Treg cells decreased. Importantly, the expressions of HDAC1 were markedly decreased, whereas ID2 and IL-12R levels increased in tumor tissues from NaB or C. butyricum with PD-1 inhibitor groups. Meanwhile, the combination of NaB or C. butyricum with PD‑1 inhibitors could alleviate the disturbance of gut microbiota by decreasing the Gordonibacter and increasing the WCHB1-32. Significantly, the anti-CD8 antibody attenuated the inhibition of tumor growth conferred by NaB and PD‑1 inhibitors in vivo. CONCLUSIONS: Collectively, NaB and C. butyricum enhanced the therapeutic action of PD‑1 inhibitors in murine models of NSCLC, possibly by modulating the HDAC1/ID2/IL-12R pathway, impacting intestinal microbiota and immune microenvironment.