24-nor-ursodeoxycholic acid ameliorates inflammatory response and liver fibrosis in a murine model of hepatic Schistosomiasis

Background & Aims: Intrahepatic granuloma formation and fibrosis characterize the pathological features of Schistosoma mansoni (S.m.) infection. Based on previously observed substantial anti-fibrotic effects of 24-nor-ursodeoxycholic acid (norUDCA) in Abcb4/Mdr2-/-mice with cholestatic liver injury and biliary fibrosis, we hypothesized that norUDCA improves inflammation-driven liver fibrosis in S.m. infection.

Methods: Adult NMRI mice were infected with 50 S.m. cercariae and after 12 weeks received either norUDCA- or ursodeoxycholic acid (UDCA)-enriched diet (0.5% wt/wt) for 4 weeks. Bile acid effects on liver histology, serum biochemistry, key regulatory cytokines, hepatic hydroxyproline content as well as granuloma formation were compared to naive mice and infected controls. In addition, effects of norUDCA on, primary T-cell activation/proliferation and maturation of the antigen-presenting-cells (dendritic cells, macrophages) were determined in vitro.

Results: UDCA as well as norUDCA attenuated the inflammatory response in livers of S.m. infected mice but exclusively norUDCA changed cellular composition and reduced size and of hepatic granulomas as well as TH2-mediated hepatic fibrosis in vivo. Moreover norUDCA affected surface expression level of major histocompatibility complex (MHC) class II of macrophages and dendritic cells as well as activation/proliferation of T-lymphocytes in vitro, whereas UDCA had no effect.

Conclusion: This study demonstrates pronounced anti-inflammatory and anti-fibrotic effects of norUDCA compared to UDCA in S.m. induced liver injury and indicates that norUDCA directly represses antigen presentation of antigen presenting cells and subsequent T-cell activation in vitro. Therefore norUDCA represents a promising drug for the treatment of this important cause of liver fibrosis.