Ergothioneine alleviates hepatic steatosis by modulating PCYT2 to restore the phosphatidylethanolamine-ACOT8 homeostasis

Background Non-alcoholic fatty liver disease (NAFLD) represents a burgeoning global health burden with limited pharmacological options. Ergothioneine (EGT), a naturally occurring antioxidant, shows potential hepatoprotective effects; however, the exact mechanisms by which EGT regulates lipid metabolism in NAFLD remain elusive. Purpose This study aimed to investigate the therapeutic efficacy and potential mechanisms of EGT in high-fat diet (HFD)-induced NAFLD. Methods NAFLD was induced in Apo E −/− mice via a 12-week HFD regimen, with concurrent oral administration of low- (1.7 mg/kg) or high-dose (17 mg/kg) EGT. We integrated in vivo multi-omics profiling with in vitro assays to identify the metabolic pathways modulated by EGT. Results EGT administration robustly ameliorated HFD-induced hepatic steatosis, liver injury, and dyslipidemia. We identified a critical regulatory axis wherein EGT inhibits phosphatidylethanolamine cytidylyltransferase 2 (PCYT2) expression, thereby dampening the accumulation of pathogenic phosphatidylethanolamine (PE) species. This suppression of PE synthesis acts as a trigger to upregulate acyl-CoA thioesterase 8 (ACOT8), a key enzyme in lipid turnover. Notably, the protective effects of EGT against palmitic acid-induced lipid accumulation were blunted by the PE synthesis inhibitor meclizine, validating the PE-ACOT8 pathway as the primary target of EGT. Conclusion This study unveils a previously unrecognized mechanism by which EGT alleviates NAFLD: the restoration of the PCYT2/PE/ACOT8 signaling axis. By correcting phospholipid composition to upregulate ACOT8, EGT restores lipid homeostasis, presenting a compelling natural compound-based strategy for NAFLD intervention.