Background: 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.
Objective: To investigate the effect of 1,25VitD3 on Th17 cells and on the expression of related cytokines in SLE patients.
Method: 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.
Results: 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.
Conclusion: 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.