B. thetaiotaomicron-derived acetic acid modulate immune microenvironment and tumor growth in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide, and emerging evidence suggests that the gut microbiota may play a role in its development and progression. In this study, the association between B. thetaiotaomicron, a gut microbiota species, and HCC recurrence, as well as patient clinical outcomes, was investigated. It was observed that B. thetaiotaomicron-derived acetic acid has the potential to modulate the polarization of pro-pro-inflammatory macrophagess, which promotes the function of cytotoxic CD8+ T cells. The increased biosynthesis of fatty acids was implicated in the modulation of pro-inflammatory macrophages polarization by B. thetaiotaomicron-derived acetic acid. Furthermore, B. thetaiotaomicron-derived acetic acid was found to facilitate the transcription of ACC1, a key enzyme involved in fatty acid biosynthesis, through histone acetylation modification in the ACC1 promoter region. Curcumin, an acetylation modification inhibitor, significantly blocked the inhibitory effects of B. thetaiotaomicron and acetic acid on HCC tumor growth. These findings highlight the potential role of gut microbiota-derived acetic acid in HCC recurrence and patient clinical outcomes, and suggest a complex interplay between gut microbiota, immune modulation, fatty acid metabolism, and epigenetic regulation in the context of HCC development. Further research in this area may provide insights into novel strategies for HCC prevention and treatment by targeting the gut microbiota and its metabolites.