Background: To investigate the function of the intestinal Vdr gene in inflammatory bowel disease (IBD), in conjunction with the discovery of possible metabolic markers for IBD using intestine-specific Vdr knockout mice.
Methods: Vdr(ΔIEpC) mice were generated, phenotyped and treated with a time-course of 3% dextran sulfate sodium (DSS) to induce colitis. Colitis was diagnosed by evaluating clinical symptoms and intestinal histopathology. Gene expression analysis was carried out. In addition, metabolic markers of IBD were explored by metabolomics.
Results: Vdr(ΔIEpC) mice showed abnormal body size, colon structures and feces color. Calcium, collagen, and intestinal proliferation-related gene expression were all decreased, and serum alkaline phosphatase was highly increased. In the acute model which was treated with 3% DSS for six days, Vdr(ΔIEpC) mice showed a high score of IBD symptoms; enlarged mucosal layer and damaged muscularis layer. In the recovery experiment model, where mice were treated with 3% DSS for four days and water for three days, Vdr(ΔIEpC) mice showed a high score of IBD symptoms; severe damage of mucosal layer and increased expression of genes encoding proinflammatory cytokines. Feces metabolomics revealed decreased concentrations of taurine, taurocholic acid, taurodeoxycholic acid and cholic acid in Vdr(ΔIEpC) mice.
Conclusions: Disruption of the intestinal Vdr gene showed phenotypical changes that may exacerbate IBD. These results suggest that VDR may play an important role in IBD.
General significance: VDR function has been implicated in IBD. This is of value for understanding the etiology of IBD and for development of diagnostic biomarkers for IBD.
Published by Elsevier B.V.