A Randomized Controlled Trial on the Effect of Vitamin D3 on Inflammation and Cathelicidin Gene Expression in Ulcerative Colitis Patients

Background: Inflammatory bowel disease (IBD) is an intestinal chronic inflammatory condition and includes Crohn's disease (CD) and ulcerative colitis (UC). It has been proposed that Vitamin D supplementation may have a beneficial role in IBD. Aim: To characterize the effects of Vitamin D on cathelicidin (hCAP/LL37) gene expression, ESR, and serum hs-CRP levels. Materials and Methods: Ninety UC patients on remission were randomized to receive 300,000 IU intramuscular Vitamin D or 1 mL normal saline as placebo, respectively. Before and 90 days after intervention, serum levels of 25(OH) -Vitamin D3, PTH, Calcium, ESR, and hs-CRP were measured. Cathelicidin gene expression was also quantified using qRT-PCR. Results: Baseline serum 25-OH-Vitamin D3 levels were not different between the two groups and after intervention, increased only in Vitamin D group (P < 0.001). Hs-CRP levels were lower in Vitamin D group after intervention (Before: 3.43 +/- 3.47 vs 3.86 +/- 3.55 mg/L, P = 0.56; after: 2.31 +/- 2.25 vs 3.90 +/- 3.97 mg/L, P = 0.023). ESR decreased significantly in Vitamin D group (Before: 12.4 +/- 6.1 vs 12.1 +/- 5.3 mm/h, P = 0.77; after: 6.7 +/- 4.5 vs 11.4 +/- 5.5 mm/h, P < 0.001). The mean fold change in hCAP18 gene expression in Vitamin D group was significantly higher than placebo group. (Mean +/- SD: 3.13 +/- 2.56 vs 1.09 +/- 0.56; median +/- interquartile range: 2.17 +/- 3.81 vs 0.87 +/- 0.53, P < 0.001). Conclusion: Decreases in ESR and hs-CRP levels and increase in LL37 gene expression support the hypothesis that Vitamin D supplementation may have a beneficial role in UC patients.