Bifidobacterium pseudolongum-generated acetate suppresses non-alcoholic fatty liver disease-associated hepatocellular carcinoma

Background & AimsRecent studies have highlighted the role of gut microbiome and metabolites in non-alcoholic fatty liver disease-associated hepatocellular carcinoma (NAFLD-HCC). We aimed to investigate the specific beneficial bacteria species as novel prophylaxis for NAFLD-HCC.MethodsThe role of Bifidobacterium pseudolongum was assessed in two NAFLD-HCC mice models induced by diethylnitrosamine with high-fat/high-cholesterol diet or with choline-deficient/high-fat diet. Germ-free mice were used for B. pseudolongum metabolic study. Stool, portal vein and liver tissues were collected from mice for non-targeted and targeted metabolomic profiles. B. pseudolongum conditioned medium (B.p CM) or candidate metabolite were co-cultured with two human NAFLD-HCC cell lines (HKCI2 and HKCI10).ResultsB. pseudolongum was the top depleted bacterium in NAFLD-HCC in mice. Oral gavage of B. pseudolongum significantly suppressed NAFLD-HCC formation in two mouse models (P<0.01). NAFLD-HCC cells co-incubation with B.p CM significantly suppressed cell proliferation, inhibited the G1/S phase transition and induced apoptosis. Acetate was identified as the critical metabolite generated from B. pseudolongum in B.p CM and confirmed in germ-free mice. Acetate inhibited cell proliferation and induced cell apoptosis in NAFLD-HCC cell lines and suppressed NAFLD-HCC tumor formation in vivo. B. pseudolongum restored heathy gut microbiome composition and improved gut barrier function. Mechanistically, B. pseudolongum-produced acetate entered portal vein to reach to the liver and bind to G coupled-protein receptor 43 (GPR43) on hepatocytes. GPR43 activation suppressed IL-6/JAK1/STAT3 signaling pathway, thereby preventing NAFLD-HCC progression.ConclusionsB. pseudolongum protected against NAFLD-HCC by secreting anti-tumor metabolite acetate through gut-liver axis. B. pseudolongum is a potential probiotic for NAFLD-HCC prevention.Impact and implicationsNon-alcoholic fatty liver disease-associated hepatocellular carcinoma (NAFLD-HCC) is an increasing healthcare burden worldwide. There is an urgent need to develop effective agents to prevent NAFLD-HCC progression. Herein, we show probiotic Bifidobacterium pseudolongum significantly suppressed NAFLD-HCC progression by secreting acetate, which bind to hepatic G coupled-protein receptor 43 (GPR43) through gut-liver axis and suppressed hepatic oncogenic IL-6/JAK1/STAT3 signaling pathway. Bifidobacterium pseudolongum is a potential novel probiotic for NAFLD-HCC prevention.