Intestinal Inflammation Alters the Expression of Hepatic Bile Acid Receptors Causing Liver Impairment.

OBJECTIVES: The gut-liver axis has been recently investigated in depth in relation to intestinal and hepatic diseases. Key actors are bile acid (BA) receptors, as farnesoid-X-receptor (FXR), pregnane-X-receptor (PXR) and G-protein-coupled-receptor (TGR5), that control a broad range of metabolic processes as well as inflammation and fibrosis.The present study aims to investigate the impact of intestinal inflammation on liver health with a focus on FXR, PXR and TGR5 expression. The strategy to improve liver health by reducing gut inflammation is also considered. Modulation of BA receptors in the inflamed colonic tissues of Inflammatory Bowel Disease (IBD) pediatric patients is analyzed. METHODS: A dextran-sulphate (DSS) colitis animal model was built. Co-cultures with Caco2 and HepG2 cell lines were set up. Modulation of BA receptors in biopsies of IBD pediatric patients was assessed by Real-time-PCR and immunohistochemistry. RESULTS: Histology showed inflammatory cell infiltration in the liver of DSS mice, where FXR and PXR were significantly decreased and oxidative stress was increased. Exposure of Caco2 to inflammatory stimuli resulted in the reduction of BA receptor expression in HepG2. Caco2 treatment with dipotassium glycyrrhizate (DPG) reduced these effects on liver cells. Inflamed colon of patients showed altered FXR, PXR and TGR5 expression. CONCLUSIONS: this study strongly suggests that gut inflammation affects hepatic cells by altering BA receptor levels as well as increasing the production of pro-inflammatory cytokines and oxidative stress. Hence, reducing gut inflammation is needed non only to improve the intestinal disease but also to protect the liver.