Transcriptional and Post-Transcriptional Anticholestatic Mechanisms of Obeticholic Acid in Lipopolysaccharide-Induced Cholestasis.

Background/Objectives: Sepsis-induced cholestasis is caused by the release of inflammatory cytokines from lipopolysaccharide (LPS), a component of Gram-negative bacteria. No established therapy exists for this condition. We ascertained the anticholestatic potential of obeticholic acid (OCA), a potent FXR agonist, in a rat model of LPS-induced cholestasis. Methods: Male Wistar rats were randomized into Control, OCA (20 mg/kg/day, i.p., 6 days), LPS (total dose of 6.5 mg/kg, i.p., in the last 2 days, respectively), and OCA + LPS groups. Then, we assessed the serum cholestasis marker, alkaline phosphatase (ALP), and taurocholate-stimulated bile salt output. mRNA/protein levels of the main apical and sinusoidal uptake and efflux carriers were assessed by either or both RT-qPCR and Western blot. Bsep and Mrp2 localization was assessed by immunohistochemistry followed by confocal microscopy and image analysis. Inflammatory cytokines were measured in serum by ELISA. Results: OCA significantly attenuates inflammatory cytokine release and normalizes serum ALP in LPS-treated rats. OCA also increased the biliary output of the Bsep substrate, taurocholate, and partially improved total Bsep at both mRNA and protein levels. Furthermore, OCA fully normalizes Bsep in the canalicular plasma membrane fraction, suggesting improved membrane localization, a finding further confirmed by confocal microscopy. OCA sustained the beneficial downregulation of uptake transporters Ntcp and Oatp2 or the upregulation of the efflux pump Mrp3, both of which serve to minimize hepatocellular bile-salt accumulation. Conclusions: OCA prevents bile-salt accumulation in LPS-induced cholestasis by enhancing Bsep expression and localization, and by mitigating inflammation. This makes OCA a promising therapeutic candidate for sepsis-induced cholestasis.