Hepatic Lysosomal Acid Lipase Overexpression Worsens Hepatic Inflammation in Mice Fed a Western Diet

Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipid droplets (LD) in hepatocytes. NAFLD development and progression is associated with an increase in hepatic cholesterol and decreased autophagy and lipophagy flux. Previous studies have shown that the expression of lysosomal acid lipase (gene=LIPA, protein=LAL), which can hydrolyze both triglyceride and cholesteryl esters, is inversely correlated with the severity of NAFLD. In addition, ablation of LAL activity results in profound NAFLD. Based on this, we predicted that overexpressing LIPA in the livers of mice fed a Western diet (FPC) would prevent the development of NAFLD. As expected, mice fed the FPC diet exhibited numerous markers of NAFLD including hepatomegaly, lipid accumulation, and inflammation. Unexpectedly, LAL overexpression did not attenuate steatosis and had only minor effects on neutral lipid composition. However, LAL overexpression exacerbated inflammatory gene expression and infiltration of immune cells in mice fed the FPC diet. LAL overexpression also resulted in abnormal phagosome accumulation and lysosomal lipid accumulation depending upon the dietary treatment. Hepatic overexpression of LAL drove immune cell infiltration and inflammation and did not attenuate the development of NAFLD suggesting that targeting LAL expression is not a viable route to treat NAFLD. 18 samples were analyzed. 6 from each of the following groups: GFP expressing mice fed a control diet, GFP expressing mice fed the FPC diet, and LIPA expressing mice fed the FPC diet.