Stard1 promotes cholestatic liver injury and disease progression by sensitizing to bile acid hepatotoxicity.

Background And Aims: Cholestatic liver diseases (CLD) are often accompanied by hepatocellular injury, fibrosis, and cirrhosis due to the intracellular accumulation of solutes that cannot be excreted into bile, including bile acids (BAs). These are synthesized in hepatocytes from cholesterol mainly via the classic pathway and in a lower proportion through the mitochondrial acidic pathway. The latter requires STARD1-dependent cholesterol transport to the mitochondrial inner membrane for metabolism, whose contribution to BA-induced hepatotoxicity and CLD is unknown.

Approach And Results: Here we show that patients with primary biliary cholangitis exhibit increased expression of STARD1 compared to control subjects. Mice with hepatocyte-specific Stard1 deletion (Stard1Δhep) were more resistant to experimental models of complete (bile duct ligation, BDL) and chemical obstructive cholestasis-induced liver injury, inflammation and fibrosis than Stard1f/f mice. Stard1Δhep mice exhibited reduced hepatic BAs and mitochondrial cholesterol accumulation but increased mitochondrial GSH (mGSH) levels following BDL compared to Stard1f/f mice. Pharmacological mGSH depletion sensitized primary mouse hepatocytes to a mix of BAs mimicking the profile seen in Stard1f/f mice after BDL leading to increased inflammatory response and cytotoxicity.

Conclusions: These findings highlight a role for STARD1 in cholestatic liver injury and suggest that its targeting may be of relevance for CLD.