ORP2 regulates free cholesterol accumulation in hepatocytes during MASH.

BACKGROUND: Cholesterol crystals in hepatocytes are known to strongly associate with human metabolic dysfunction-associated steatohepatitis. However, it remains unclear which molecular pathway(s) regulates free cholesterol accumulation and the formation of cholesterol crystals in hepatocytes. In cultured cell lines, oxysterol-binding protein-related protein 2 (ORP2) functions to deliver cholesterol to the plasma membrane from endosomal compartments. METHODS: Here, we generated liver-specific ORP2 knockout (ORP2-LKO) mice and characterized their metabolic phenotypes on chow and high-fat diet. RESULTS: The ORP2-LKO mice developed much more severe hepatic steatosis than floxed control mice after high-fat diet feeding. They also demonstrated more severe liver inflammation and damage. Notably, free but not esterified cholesterol, as well as cholesterol crystals, accumulated in the ORP2-LKO liver. The expression of Cyp7a1 was significantly upregulated in the ORP2-LKO liver, accompanied by the accumulation of taurocholic acid. Our results thus unveil an important in vivo function of ORP2 in preventing free cholesterol from accumulating in the mouse liver. CONCLUSIONS: Our results suggest that impaired cholesterol trafficking may exacerbate the deposition of cholesterol crystals in hepatocytes, promoting the development of metabolic dysfunction-associated steatohepatitis.