Background Systemic lupus erythematosus (SLE) is a systemic autoimmune inflammatory disease which presents heterogeneous clinical manifestations. Patients with SLE develop autoimmune response mediated by T and B cells that are manifested by the production of cytokines and autoantibodies. Vitamin D has an immunomodulatory effect, acting in innate and adaptative immune systems, could change the Th1, Th2 and Th17 cytokine profiles.
Objectives To evaluate the expression of Th1, Th2 and Th17 cytokine profiles in SLE patients and verify possible associations with serum vitamin D levels.
Methods 172 patients with SLE followed at the outpatient clinic of Rheumatology at Hospital de Clinicas de Porto Alegre were included. The levels of 25-hydroxyvitamin D [(25(OH)D)] were measured by chemiluminescence. Serum levels <20 ng/ml were considered as vitamin D deficiency. Normal vitamin D levels were defined as ≥20ng/ml. Cytokines were measured in serum after thawing the samples on a single occasion, using Kit CBA Th1/Th2/Th17 (BD™ Biosciences, USA).
Results 161 (94%) patients were women and 128 (74.4%) were classified as caucasian ethnicity. The mean age of was 40.5±13.8 years and the mean age at diagnosis was 31.5±13.4 years. At the time of study entry, patients had median (IQR) SLEDAI of 2 (1-4) and SLICC of 0 (0-1). Mean 25(OH)D levels were 25.4±11.04 ng/ml. Fifty-nine (34.3%) patients had vitamin D deficiency and 113 (65.7%) had normal levels. Serum levels of cytokines are shown in Table 1. No associations and statistically significant correlations between cytokine levels and dosages of vitamin D were found. Only levels of INF-α and SLEDAI showed a positive and significant correlation (rs=0.22, p=0.04). Linear regression analysis was performed to control for possible confounding factors, specially medications used.
Conclusions Vitamin D deficiency is prevalent in patients with SLE, however, no statistically significant correlations and associations between vitamin D levels and cytokine profile were found. We confirm the positive correlation between IFN-α and SLEDAI, according to the literature. In vitro effect of vitamin D on the cytokine profile was not reproduced in this study. Research with vitamin D and cytokine profile in controlled intervention trials with placebo are needed to investigate this hypothesis before any definitive conclusions can be made.
Disclosure of Interest None declared