Abstract
BACKGROUND: Metabolic dysfunction-associated steatotic liver disease (MASLD) stands as the most widespread chronic liver disorder globally. Histone β-hydroxybutyrylation (Kbhb)-a novel post-translational modification of histones driven by β-hydroxybutyrate (BHB)-has recently been recognized as a key epigenetic modulator. Our study aimed to explore how BHB influences the expression of hepatic lipid metabolism-associated genes in MASLD, and to determine whether histone Kbhb acts as the mechanistic mediator underlying these effects. METHODS: For in vivo experiments, db/db mice fed a high-fat diet were utilized as the MASLD model. Following BHB intervention, changes in glycolipid metabolism and lipid accumulation in liver were assessed. Hepatic expression of lipid oxidation-related genes (e.g., PPARα) was quantified via qPCR; hepatic Pan-Kbhb and H3K9bhb levels were detected using immunohistochemistry and immunofluorescence. For in vitro experiments, a palmitic acid (PA)-induced AML12 hepatocyte model was established. After BHB treatment, intracellular lipid accumulation was visualized via Oil Red O and BODIPY staining; PPARα and downstream lipid oxidation gene expression was measured by qPCR and Western blotting. Total protein and histone Kbhb were evaluated using immunofluorescence and Western blotting. RESULTS: BHB effectively mitigated lipid accumulation in the livers of db/db mice and PA-induced AML12 cells, while upregulating PPARα and its downstream lipid oxidation-related target genes. Simultaneously, BHB elevated total protein Kbhb and histone H3K9bhb modifications in hepatic cells. Critically, blocking Kbhb (via A485, an inhibitor of the acyltransferase P300, or an acyl-CoA synthetase 2 inhibitor) led to significant downregulation of PPARα and its target gene expression. CONCLUSION: BHB alleviates lipid accumulation in the liver of MASLD by promoting the expression of PPARα and its downstream lipid oxidation-related genes in the hepatocytes, which is associated with histone Kbhb modification.