Loss of Integrin αvβ8 in Murine Hepatocytes Accelerates Liver Regeneration

Recent fate-mapping studies in mice have provided substantial evidence that mature adult hepatocytes are a major source of new hepatocytes after liver injury. In other systems, integrin avb8 has a major role in activating transforming growth factor (TGF)-b, a potent inhibitor of hepatocyte proliferation. We hypothesized that depletion of hepatocyte integrin avb8 would increase hepatocyte proliferation and accelerate liver regeneration after injury. Using Itgb8 flox/flox ;Alb-Cre mice to deplete hepatocyte avb8, after partial hepatectomy, hepatocyte proliferation and liver-to-body weight ratio were significantly increased in Itgb8 flox/flox ;Alb-Cre mice compared with control mice. Antibody-mediated blockade of hepatocyte avb8 in vitro, with assessment of TGF-b signaling pathways by real-time quantitative PCR array, supported the hypothesis that integrin avb8 inhibition alters hepatocyte TGF-b signaling toward a proregenerative phenotype. A diethylnitrosamine-induced model of hepatocellular carcinoma, used to examine the possibility that this pro-proliferative phenotype might be oncogenic, revealed no difference in either tumor number or size between Itgb8 flox/flox ;Alb-Cre and control mice. Immunohistochemistry for integrin avb8 in healthy and injured human liver demonstrated that human hepatocytes express integrin avb8. Depletion of hepatocyte integrin avb8 results in increased hepatocyte proliferation and accelerated liver regeneration after partial hepatectomy in mice. These data demonstrate that targeting integrin avb8 may represent a promising therapeutic strategy to drive liver regeneration in patients with a broad range of liver diseases.