Hepatocyte FoxO1 Deficiency Protects From Liver Fibrosis via Reducing Inflammation and TGF-β1-mediated HSC Activation

Abstract

The O-class of the forkhead transcription factor FoxO1 is a crucial factor mediating insulin→PI3K→Akt signaling and governs diverse cellular processes. However, the role of hepatocyte FoxO1 in liver fibrosis has not been well-established. In his study, we investigated the role of hepatocyte FoxO1 in liver fibrosis and uncovered the underlying mechanisms. Liver fibrosis was established by carbon tetrachloride (CCL4) administration and compared between liver-specific deletion of FoxO1 deletion (F1KO) and control (CNTR) mice. Using genetic and bioinformatic strategies invitro and invivo, the role of hepatic FoxO1 in liver fibrosis and associated mechanisms was established. Increased FoxO1 expression and FoxO1 signalingactivation were observed in CCL4-induced fibrosis. Hepatic FoxO1 deletion largely attenuated CCL4-induced liver injury and fibrosis compared with CNTR mice. F1KOmice showed ameliorated CCL4-induced hepatic inflammation and decreased TGF-β1 mRNA and protein levels compared with those of CNTR mice. In primary hepatocytes, FoxO1 deficiency reduced TGF-β1 expression andsecretion. Conditioned medium (CM) collected from wild-type hepatocytes treated with CCL4 activated humanHSC cell line (LX-2); such effect was attenuated byFoxO1 deletion in primary hepatocytes or neutralization of TGF-β1 in the CM using TGF-β1 antibody. Hepatic FoxO1overexpression in CNTR mice promoted CCL4-induced HSC activation; such effect was blocked in L-TGF-β1KO mice. Hepatic FoxO1 mediates CCL4-inducled liver fibrosis via upregulating hepatocyte TGF-β1 expression, stimulating hepatic inflammation and TGF-β1-mediated HSC activation. Hepatic FoxO1 may be a therapeutic target for prevention and treatment of liver fibrosis.