Prevotella ‐Derived Butyrate Inhibits CD8 + T‐Cell Glycolysis via AKT / mTOR Signalling to Alleviate MASH

ABSTRACT Background and Aims Metabolic associated steatohepatitis (MASH) is a critical stage of MAFLD, lacking effective therapies. Gut microbiota and their metabolites, particularly short‐chain fatty acids (SCFAs), are increasingly recognised as modulators of hepatic metabolism and immune responses. We investigated whether Prevotella could ameliorate MASH by regulating CD8 + T‐cell metabolism. Methods Faecal samples from MASH patients and healthy controls were analysed by 16S rDNA sequencing and untargeted metabolomics. MASH mouse models, germ‐free mice and ex vivo CD8 + T‐cell cultures were used to assess the effects of Prevotella and butyrate on glycolysis, PI3K/AKT/mTOR signalling and liver pathology. Metabolic activity was measured using ECAR, 2‐NBDG uptake and lactate production; molecular changes were evaluated by qPCR, western blotting and flow cytometry. Results 16S rDNA sequencing revealed a significant reduction of Prevotella abundance in MASH patients compared with healthy controls, which was inversely correlated with hepatic steatosis and CD8 + T‐cell infiltration. In MCD diet‐induced MASH mice, oral administration of Prevotella alleviated hepatic lipid accumulation and collagen deposition. In germ‐free mice, colonisation with Prevotella similarly improved liver histology. Mechanistically, Prevotella suppressed glycolytic activity in CD8 + T cells, as shown by decreased 2‐NBDG uptake, ECAR measurements and reduced expression of glycolytic enzymes (HK2, PKM2, LDHA). Additionally, Prevotella downregulated the PI3K/AKT/mTOR signalling pathway in CD8 + T cells, linking its metabolic effects to immune modulation. Notably, the combination of Prevotella with a glycolysis inhibitor did not further enhance its therapeutic efficacy compared with Prevotella alone, indicating that suppression of glycolysis is a major mechanism underlying Prevotella 's protective effects. Conclusion Prevotella mitigates MASH by downregulating the PI3K/AKT/mTOR–glycolysis axis in CD8 + T cells via butyrate‐dependent mechanisms, highlighting its potential as a microbial therapeutic candidate for MASH.