Influence of 1 Alpha, 25-Dihydroxyvitamin D3 on T Helper 17 Cells and Related Cytokines in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease. Emerging data suggests that T helper 17 (Th17) cells play a pathogenic role in SLE and the increased number of these cells correlates with disease activity. In recent years, 1α, 25-dihydroxyvitamin D3 (1,25VitD3) has been considered as an immunomodulatory factor. To investigate the effect of 1,25VitD3 on Th17 cells and on the expression of related cytokines in SLE patients. Thirty SLE patients (newly diagnosed or in remission) were sampled for 10 ml whole blood to isolate peripheral blood mononuclear cells (PBMCs) using Ficoll-Hypaque density gradient centrifugation. Isolated cells were cultured in the presence and absence of 50 nM 1,25VitD3. After incubation, cells were harvested and stimulated for 4-5 hours with phorbol myristate acetate (PMA) and ionomycin in the presence of brefeldin A. IL-17 secreting cells were analyzed by flowcytometry. RNA was extracted from cultured cells, cDNA was synthesized, and the expression levels of IL-6, IL-17, IL-23 and TGF-β genes were assessed by real-time PCR. The percentage of Th17 cells (CD3+CD8- IL-17+ T cells) decreased significantly in 1,25VitD3-treated cells (3.67 ± 2.43%) compared to untreated cells (4.65 ± 2.75%)( p=0.003). The expression of TGF-β up regulated (1.38-fold) and the expression of IL-6 (50%), IL-17 (27%) and IL-23 (64%) down regulated after 1,25VitD3 treatment. This study showed that 1,25VitD3 modulates Th17 related pathways in SLE patients and revealed the immunomodulatory effect of 1,25VitD3 on the Th17 mediated autoimmunity.