Cholangiopathy and biliary fibrosis in Cyp2c70-deficient mice are fully reversed by ursodeoxycholic acid

Background and Aims - Bile acids (BAs) aid intestinal fat absorption and exert systemic actions by receptor-mediated signaling. BA receptors have been identified as drug targets for human diseases, but differences in BA metabolism between humans and mice hamper translation of pre-clinical outcomes. Cyp2c70-ablation in mice prevents synthesis of mouse/rat-specific muricholic acids (MCAs), but potential (patho)physiological consequences of their absence are unknown. We therefore assessed age- and gender-dependent effects of Cyp2c70-deficiency in mice. Methods - BA-related parameters, hepatic and intestinal gene expression patterns, liver morphology and intestinal barrier function were assessed in male and female Cyp2c70-/- mice and WT controls at different ages. Effects of ursodeoxycholic acid (UDCA) treatment were evaluated in young adult female mice. Results – Cyp2c70-/- mice were completely devoid of MCAs and showed high abundances of chenodeoxycholic and lithocholic acids. BA pool size was unaffected in young-adult male but reduced by 40% in female Cyp2c70-/- mice. Interestingly, plasma BAs and transaminases were highest in Cyp2c70-/- mice at weaning and spontaneously decreased with age. Although bile flow and biliary BA secretion were unchanged in young-adult Cyp2c70-/- mice, indicating absence of cholestasis, plasma BA and transaminase levels were still elevated. These young-adult Cyp2c70-/- mice displayed cholangiocyte proliferation, mild portal fibrosis, altered microbiome composition and increased gut permeability. Only the female Cyp2c70-/- mice developed bridging fibrosis with age (7-8 months). UDCA treatment normalized hepatic and intestinal functions and fully restored liver morphology in female Cyp2c70-/- mice. Conclusion – Cyp2c70-/- mice show transient neonatal cholestasis and develop cholangiopathic features which progress to bridging fibrosis in female mice only. These consequences of Cyp2c70-deficiency are fully restored by treatment with UDCA. Total RNA optained from liver 22 samples where compaired in 4 different groups ( WT , WT+UDCA , CYP2C70KO , CYP2C70KO+UDCA) , each group consisting of n=5,6 biological replicates