Effect of cholesterol overload on gene expression of hepatic macrophages isolated from normal and NASH livers.. Effect of cholesterol overload on gene expression of hepatic macrophages isolated from normal and NASH livers.

Hepatocyte death plays a critical role in the disease progression from simple steatosis to non-alcoholic steatohepatitis (NASH). We have previously reported that hepatocyte death locally induces phenotypic changes in the macrophages surrounding the corpse and remnant lipids, thereby promoting liver fibrosis in a murine model of NASH. Here, we demonstrated free cholesterol was accumulated in macrophages around dead hepatocytes containing cholesterol crystals. In vitro experiments revealed that cholesterol-induced lysosomal stress triggered profibrotic activation in macrophages predisposed to the steatotic microenvironment. This study provides evidence that dysregulated cholesterol metabolism in macrophages would be a novel mechanism of NASH. Overall design: Hepatic macrophages were isolated from normal livers of wild-type mice fed a standard diet or steatotic livers of MC4R-KO mice fed a Western diet for 6 to 10 weeks using anti-F4/80 antibodies and magnetic separation columns. Macrophages were treated with cholesterol crystals at a dose of 500 μg/ml for 24 hours. RNA sequencing analysis was performed to compare the response to lysosomal stress induced by cholesterol crystals.