255-LB: Liver Pyruvate Carboxylase Deletion in Mice Prevents Fibrosis from a NASH Diet

Obesity and T2D are closely associated with Nonalcoholic Fatty Liver Disease, which can advance to Nonalcoholic Steatohepatitis (NASH) with fibrosis. We previously found that liver pyruvate carboxylase (PC) is required for hepatic gluconeogenesis and the concentration of metabolites essential to mediating redox state and antioxidant function. Liver PC knockout (LPCKO) mice are protected from HFD-induced hyperinsulinemia and glucose intolerance despite retaining excess liver fat and exhibiting reduced antioxidant capacity. Here, we report that despite impaired antioxidant markers and increased inflammatory markers on a HFD, PC loss protected the liver from fibrosis and other indices of liver damage induced by a long-term NASH diet. LPCKO and control mice were fed a high fat, high cholesterol Western Diet (WD) for 13-14 months. After 10 mos. of WD, markers of insulin resistance were assessed by lactate/pyruvate, glucose, and insulin tolerance tests. After sacrifice, liver damage was assessed by serum markers and histology. Oxidative stress and inflammation were evaluated by gene expression, MDA concentration, GSH/GSSG and NADPH/NADP+ redox states, and H2O2 emission potential in isolated mitochondria. LPCKO-WD mice were more sensitive to an insulin tolerance test and exhibited lower fasting blood glucose and better glycemic control during a lactate/pyruvate or glucose tolerance test than controls. Liver malate/pyruvate indicated substantially lower NADPH/NADP+ in LPCKO-WD mice, but there were no differences in MDA levels, GSH/GSSG, and H2O2 emission potential. Despite similar hepatic steatosis, inflammation, and ballooning between LPCKO-WD and controls, fibrosis and serum markers of liver injury were markedly lower in LPCKO-WD mice. The data suggest that liver PC deletion improves glycemia and insulin resistance during chronic Western Diet exposure by reducing hepatic gluconeogenesis and prevents fibrosis independent of steatosis, inflammation, ballooning, and oxidative stress.