Vitamin D level and potential impact on immune cells in Beh�et�s disease

Introduction Vitamin D plays key roles in innate and adaptive immunity through the stimulation of Toll-like receptors, increasing proinflammatory cytokine production, and possibly skewing T helper (Th) responses. Data from human vitamin D supplementation studies have shown beneficial effects of vitamin D on immune function, in particular in the context of autoimmunity. Low levels of this hormone were observed in several autoimmune diseases including Behcet’s disease. The data relating vitamin D to autoimmune and inflammatory diseases are equivocal, with studies linking low vitamin D levels to dysregulation of Th1/Th2 and Th17/ Treg ratios. We summarised the effects of vitamin D on the immune system in Behcet’s disease. Conclusion Vitamin D research has confirmed important interactions between vitamin D and cells from the innate as well as from the adaptive immune system. All the data reported in this review show that vitamin D in Behcet’s disease inhibits Th17 cytokine production, enhances Treg cells, suppresses Th1 and promotes Th2 cytokine production and thus skews T cells towards Th2 polarisation.