Intestinal epithelial vitamin D receptor signaling inhibits experimental colitis
Weicheng Liu, Yunzi Chen, Maya Aharoni Golan, Maria L. Annunziata, Jie Du, Urszula Dougherty, Juan Kong, Mark Musch, Yong Huang, Joel Pekow, Changqing Zheng, Marc Bissonnette, Stephen B. Hanauer, Yan Chun Li
Weicheng Liu, Yunzi Chen, Maya Aharoni Golan, Maria L. Annunziata, Jie Du, Urszula Dougherty, Juan Kong, Mark Musch, Yong Huang, Joel Pekow, Changqing Zheng, Marc Bissonnette, Stephen B. Hanauer, Yan Chun Li
View: Text | PDF
Research Article Gastroenterology

Intestinal epithelial vitamin D receptor signaling inhibits experimental colitis

Abstract

The inhibitory effects of vitamin D on colitis have been previously documented. Global vitamin D receptor (VDR) deletion exaggerates colitis, but the relative anticolitic contribution of epithelial and nonepithelial VDR signaling is unknown. Here, we showed that colonic epithelial VDR expression was substantially reduced in patients with Crohn’s disease or ulcerative colitis. Moreover, targeted expression of human VDR (hVDR) in intestinal epithelial cells (IECs) protected mice from developing colitis. In experimental colitis models induced by 2,4,6-trinitrobenzenesulfonic acid, dextran sulfate sodium, or CD4+CD45RBhi T cell transfer, transgenic mice expressing hVDR in IECs were highly resistant to colitis, as manifested by marked reductions in clinical colitis scores, colonic histological damage, and colonic inflammation compared with WT mice. Reconstitution of Vdr-deficient IECs with the hVDR transgene completely rescued Vdr-null mice from severe colitis and death, even though the mice still maintained a hyperresponsive Vdr-deficient immune system. Mechanistically, VDR signaling attenuated PUMA induction in IECs by blocking NF-κB activation, leading to a reduction in IEC apoptosis. Together, these results demonstrate that gut epithelial VDR signaling inhibits colitis by protecting the mucosal epithelial barrier, and this anticolitic activity is independent of nonepithelial immune VDR actions.

Authors

Weicheng Liu, Yunzi Chen, Maya Aharoni Golan, Maria L. Annunziata, Jie Du, Urszula Dougherty, Juan Kong, Mark Musch, Yong Huang, Joel Pekow, Changqing Zheng, Marc Bissonnette, Stephen B. Hanauer, Yan Chun Li

×

Figure 9

Epithelial VDR signaling abrogates PUMA induction by blocking NF-κB activation.

Options: View larger image (or click on image) Download as PowerPoint
Epithelial VDR signaling abrogates PUMA induction by blocking NF-κB acti...
(A) Western analysis of PUMA in HCT116 cells treated with TNF-α (100 ng/ml) ± 1,25(OH)2D3 (1,25VD, 20 nM). (B) PUMA gene promoter κB cis-element and its mutant sequences. (C) ChIP assay measuring p65 binding to the κB site in HCT116 cells treated with TNF-α ± 1,25(OH)2D3. **P < 0.01 versus the rest. (D) EMSA using 32P-labeled PUMA κB probe and nuclear extracts isolated from HCT116 cells treated with TNF-α ± 1,25(OH)2D3. (E) PUMA promoter luciferase reporter assays in HCT116 cells transfected with wild-type (WT) or mutant (Mut) PUMA κB luciferase reporter, followed by treatment with TNF-α ± 1,25(OH)2D3. (F) HCT116 cells were cotransfected with the WT or Mut PUMA κB luciferase reporter and IKKβ-expressing plasmid. Luciferase activity was determined after 1,25(OH)2D3 (+) or ethanol (–) treatment. §P < 0.001 versus the rest. (G) IKK kinase assays in HCT116 cells treated with TNF-α ± 1,25(OH)2D3. (H) HCT116 cells were transfected with empty vector (–) or HA-IKKβ plasmid (+), followed by treatment with ethanol (–) or 1,25(OH)2D3 (+). Note that PUMA protein was induced by IKKβ overexpression, and this induction was abolished by 1,25(OH)2D3. (I) Colonic mucosal IKK activity. Colonic mucosa were isolated from untreated (–) and TNBS-treated (+) WT, Tg, VDRKO and KO Tg mice on day 2 after TNBS treatment, and the lysates were subjected to IKK kinase assays and Western analyses for IKKα/β, PUMA, caspase 3, and p53 proteins. Each lane represents a pool of 4 to 5 mice of the same genotype and treatment.