Background: The aetiology of Crohn's disease (CD) and ulcerative colitis (UC) is not known. Recent data suggest that vitamin D (VD) plays an important role in IBD. Pathways that are influenced by VD in IBD are poorly understood.
Methods: We performed a cross-sectional study. The cohort consisted of 87 IBD patients (47 CD and 40 UC) followed at the IBD centre of University Hospital Bratislava-Ružinov. We performed colonoscopy in each patient and took biopsies from inflammed and if applicable also from non-inflammed mucosa from sigma (CD, UC) and terminal ileum (CD). Serum concentration of 25(OH)VD was assessed in each patient at the time of colonoscopy. mRNA was extracted from mucosal biopsy samples for each cytokine and isolated by RLT buffer. mRNA was reversely transcribed. We normalized expression of the target genes to the expression of the house-keeping gene (GAPDH). Then we analysed the correlation between serum concentration 25(OH)VD and the expression of mRNA of inflammatory cytokines from biopsies samples.
Results: In CD we observed a positive correlation of serum concentration 25(OH)VD and mRNA expressions levels of TNFα (r2 =0.41, p=0.04), IL-6 (r2=0.45, p=0.02), IL-10 (r2=0.44, p=0.03), IL-23 (r2=0.55, p=0.02), TLR 2 (r2=0.04, p=0.04) in inflammed mucosa of terminal ileum. A positive correlation was also observed with CCR5 (r2=0.042, p=0.01) and CCR1 (r2=0.33, p=0.03) in non-inflammed mucosa from sigma. We also found a positive correlation between 25(OH)VD and IL-23 (r2=0.45, p=0.01), TLR4 (r2=0.42, p=0.02), CD 207 (r2=0.42, p=0.02), CCR1 (r2=0.52, p=0.002), CCR5 (r2=0.51 p=0.003) and CD 206 (r2=0.43, p=0.01) in non-inflammed mucosa of sigma in UC.
Conclusions: According to our results, VD significantly correlated with the levels of expression of several inflammatory cytokines including TNFα in colonic mucosa of patients with CD.