Antagonizing EZH2 combined with vitamin D3 exerts a synergistic role in anti-fibrosis through bidirectional effects on hepatocytes and hepatic stellate cells

Abstract

Background and aim: Whether vitamin D3 (VD3) supplementation is associated with improved liver fibrosis is controversial.

Methods: Liver fibrosis models were treated with VD3, active VD (1,25-OH₂ Vitamin D3), or collaboration with GSK126 (Ezh2 inhibitor), respectively. Hepatic stellate cells (HSCs) were co-cultured with hepatocytes and then stimulated with TGF-β. Autophagy of hepatocytes was determined after the intervention of 1,25-OH₂ Vitamin D3 and GSK126. Also, the active status of HSCs and the mechanism with 1,25-OH₂ Vitamin D3 and GSK126 intervention were detected.

Results: 1,25-OH₂ Vitamin D3, but not VD3, is involved in anti-fibrosis and partially improves liver function, which might be associated with related enzymes and receptors (especially CYP2R1), leading to decreased of its biotransformation. GSK126 plays a synergistic role in anti-fibrosis. The co-culture system showed increased hepatocyte autophagy after HSCs activation. Supplementation with 1,25-OH₂ Vitamin D3 or combined GSK126 reduced these effects. Further studies showed that 1,25-OH₂ Vitamin D3 promoted H3K27 methylation of DKK1 promoter through VDR/Ezh2 due to the weakening for HSCs inhibitory signal.

Conclusions: VD3 bioactive form 1,25-OH₂ Vitamin D3 is responsible for the anti-fibrosis, which might have bidirectional effects on HSCs by regulating histone modification. The inhibitor of Ezh2 plays a synergistic role in this process.

Keywords: hepatic stellate cell; hepatocyte; liver fibrosis; vitamin D.