NR1I2 and primary biliary cholangitis: Notably, UDCA does not activate FXR7,11,239 and has low affinity to GR,228 but may activate PXR indirectly after its conversion to LCA by intestinal flora.8,9 In addition, UDCA induced expression of protective cathelicidin via activation of VDR in cultured biliary epithelial cells and induced both VDR and cathelicidin gene expression in livers of PBC patients.82