Tumor necrosis factor alpha receptor 1 deficiency in hepatocytes does not protect from non-alcoholic steatohepatitis, but attenuates insulin resistance in mice

Abstract

BACKGROUND End-stage liver disease caused by non-alcoholic steatohepatitis (NASH) is the second leading indication for liver transplantation. To date, only moderately effective pharmacotherapies exist to treat NASH. Understanding the pathogenesis of NASH is therefore crucial for the development of new therapies. The inflammatory cytokine tumor necrosis factor alpha (TNF-α) is important for the progression of liver disease. TNF signaling via TNF receptor 1 (TNFR1) has been hypothesized to be important for the development of NASH and hepatocellular carcinoma in whole-body knockout animal models. AIM To investigate the role of TNFR1 signaling in hepatocytes for steatohepatitis development in a mouse model of diet-induced NASH. METHODS NASH was induced by a western-style fast-food diet in mice deficient for TNFR1 in hepatocytes (TNFR1ΔHEP) and their wild-type littermates (TNFR1fl/fl). Glucose tolerance was assessed after 18 wk and insulin resistance after 19 wk of feeding. After 20 wk mice were assessed for features of NASH and the metabolic syndrome such as liver weight, liver steatosis, liver fibrosis and markers of liver inflammation. RESULTS Obesity, liver injury, inflammation, steatosis and fibrosis was not different between TNFR1ΔHEP and TNFR1fl/fl mice. However, Tnfr1 deficiency in hepatocytes protected against glucose intolerance and insulin resistance. CONCLUSION Our results indicate that deficiency of TNFR1 signaling in hepatocytes does not protect from diet-induced NASH. However, improved insulin resistance in this model strengthens the role of the liver in glucose homeostasis.