Obeticholic Acid Protects Against Cholestatic Liver Injury Induced by Lithocholic Acid via Inhibiting Exogenous Cell Apoptosis

Abstract Background: Lithocholic acid (LCA) is one kind of endogenous bile acids which is a typical index in primary biliary cholangitis (PBC). It could cause severe cholestatic liver injury in rodents. Obeticholic acid (OCA) is a major treatment for PBC. However, its effect and mechanism in LCA-induced liver injury was still unclear beside of bile acid regulation. This study aims to evaluate the hepatoprotective effect and mechanism of OCA against LCA-induced cholestatic liver injury. Results: LCA-induced upregulations of ALT, AST, ALP and TBA were reduced and the bile acid profiles in serum, liver and bile were improved significantly by OCA. This bile acid regulating effect of OCA was mainly based on increasing the expression of bile acid efflux transporters bile salt export pump (BSEP), multidrug resistant associated protein 2 (MRP2), MRP3 and multi-drug resistance 3 (MDR3) instead of bile acid synthesis inhibition. Furthermore, it was found that OCA reduced the activation and expression of Caspase 8/3 signaling pathway without the change of p-MLKL and BAX in LCA-induced cholestatic model. And the inhibition of Caspase 8/3 signaling pathway depended on the activation of Farnesoid X receptor (FXR) to inhibit Caspase 8 cleavage to form a active complex.Conclusions: This study found OCA improved LCA-induced cholestatic liver injury via FXR-induced exogenous cell apoptosis, which provided a new evidence for the application of OCA to ameliorate PBC in clinical.