Interaction among vitamin D3 analogue KH 1060, TNF-α, and vitamin D receptor protein in peripheral blood mononuclear cells of inflammatory bowel disease patients

Abstract Background The active form of vitamin D, 1,25(OH) 2 D 3 , exerts important effects on proliferation and differentiation of many cell types, and immunoregulatory activities in particular on T cell-mediated immunity. Aim The aim of this study was to investigate whether KH 1060, a vitamin D analogue, could decrease tumor necrosis factor-alpha (TNF-α) levels in patients with inflammatory bowel disease (IBD). Methods PBMC proliferation was determined by [ 3 H]thymidine incorporation. TNF-α levels were measured by ELISA kit; VDR, Bcl-2 and Bax protein levels with Western blot analysis. Results KH 1060 inhibited PBMC proliferation and decreased TNF-α levels in IBD patients and this effect was synergistic with anti-TNF-α. VDR protein levels were significantly increased by PBMC treatment with KH 1060 or anti-TNF-α or their combination in ulcerative colitis (UC) patients, and decreased in Crohn's disease (CD) patients, treating the cells with KH 1060. In UC patients an increase in Bcl-2 and Bax levels was observed incubating, PBMC with KH 1060 or anti-TNF-α or their combination. In CD patients a slight decrease in Bcl-2 levels was registered when anti-TNF alone or in association with KH 1060 was used. Bax protein levels were slightly increased in the presence of KH 1060 alone or in combination with anti-TNF. Conclusion This study shows that KH 1060 acts as an immunomodulator on PBMC, acting as TNF-α inhibitor. This finding provides strong evidence that vitamin D status could be an important regulator of immunity IBD.