Published online Apr 7, 2016. doi: 10.3748/wjg.v22.i13.3581
Peer-review started: October 26, 2015
First decision: November 13, 2015
Revised: December 5, 2015
Accepted: January 18, 2016
Article in press: January 18, 2016
Published online: April 7, 2016
AIM: To determine serum vitamin D levels and colonic vitamin D receptor (VDR) expression in inflammatory bowel disease (IBD) and non-IBD patients and correlate these with histopathology.
METHODS: Puerto Rican IBD (n = 10) and non-IBD (n = 10) patients ≥ 21 years old scheduled for colonoscopy were recruited. Each patient completed a questionnaire and provided a serum sample and a colonic biopsy of normal-appearing mucosa. For IBD patients, an additional biopsy was collected from visually diseased mucosa. Serum vitamin D levels were measured by ultra-performance liquid chromatography and mass spectrometry. Hematoxylin and eosin stained tissue sections from colonic biopsies were classified histologically as normal or colitis (active/inactive), and scored for the degree of inflammation present (0-3, inactive/absent to severe). Tissue sections from colonic biopsies were also stained by immunohistochemistry for VDR, for which representative diagnostic areas were photographed and scored for staining intensity using a 4-point scale.
RESULTS: The IBD cohort was significantly younger (40.40 ± 5.27, P < 0.05) than the non-IBD cohort (56.70 ± 1.64) with a higher prevalence of vitamin D deficiency (40% vs 20%, respectively) and insufficiency (70% vs 50%, respectively). Histologic inflammation was significantly higher in visually diseased mucosa from IBD patients (1.95 ± 0.25) than in normal-appearing mucosa from control patients (0.25 ± 0.08, P < 0.01) and from IBD patients (0.65 ± 0.36, P < 0.05) and correlated inversely with VDR expression in visually diseased colonic tissue from IBD patients (r = -0.44, P < 0.05) and from IBD patients with Crohn’s disease (r = -0.69, P < 0.05), but not in normal-appearing colonic tissue from control patients or IBD patients. Control and IBD patient serum vitamin D levels correlated positively with VDR expression in normal colon from control and IBD patients (r = 0.38, P < 0.05) and with patient age (r = 0.54, P < 0.01).
CONCLUSION: Levels of serum vitamin D correlate positively with colonic VDR expression in visually normal mucosa whereas inflammation correlates negatively with colonic VDR expression in visually diseased mucosa in Puerto Rican patients.
Core tip: Our study examines for the first time the relationship between serum vitamin D levels, colonic vitamin D receptor (VDR) expression, and histologic disease activity. We show in Puerto Rican patients that colonic VDR expression and inflammation are negatively correlated in endoscopically and histologically diseased colon and that serum vitamin D levels positively correlate with VDR expression in endoscopically and histologically normal colon. These findings contribute to our understanding of the role of vitamin D and VDR in patients with inflammatory bowel disease and could affect the current care of these patients.