NR1H4 and infection: Obeticholic acid (OCA) is a highly selective FXR agonist that is FDA-approved for treatment of primary biliary cholangitis.20 OCA inhibits primary BA synthesis by activating intestinal FXR signaling.20,35 To examine its role as a potential therapy for CDI, we treated C. difficile-infected mice daily with OCA, starting 12 h after infection (Fig. 7a).