Inhibition of histone deacetylase 3 alleviates lithocholic acid-induced intrahepatic cholestasis by enhancing expression of bile acid and lipid homeostasis-related genes

There is a lack of effective therapies for cholestatic liver injury. Recent studies have shown that pan-inhibitors of histone deacetylases (HDACs) play a protective role in cholestasis and fibrosis, but the dynamic changes and role of histone deacetylase 3 (HDAC3) under these conditions remain unclear. In the current study, the expression of acetylation-modifying enzymes, including HDAC3, in livers from lithocholic acid (LCA)-induced intrahepatic and bile duct ligation (BDL)-induced extrahepatic cholestatic mice, as well as in cholestatic patients, was examined. HDAC3 was aberrantly upregulated in the livers of cholestatic mice and patients. Functional studies in LCA- and BDL-induced cholestatic mouse models using RGFP966, a specific HDAC3 inhibitor, were then performed. Pharmacological inhibition of HDAC3 significantly alleviated liver injury in LCA-induced cholestasis but had no protective effect on BDL-induced cholestasis, as assessed by survival tests, gross examination, H&E staining, serum biochemical assays, cytokine expression, and immunohistochemical staining of immune cell biomarkers. Mechanistically, HDAC3 inhibition upregulated genes involved in bile acid and lipid homeostasis in LCA-induced cholestatic mice, as determined by RNA-Seq and validated by RT‒qPCR and Western blotting. The upregulation of these genes, together with increased levels of acetylation of histone H3 at lysine 9 (H3K9Ac) and lysine 27 (H3K27Ac), was validated in transformed human liver epithelial-2 (THLE-2) cells treated with RGFP966. In summary, this study demonstrated that HDAC3 is a potential therapeutic target for LCA-induced intrahepatic cholestasis, with inhibition exerting protective effects through genes involved in bile acid and lipid homeostasis, possibly via epigenetic regulation.