Vitamin D levels and cytokine profiles in patients with systemic lupus erythematosus

Objectives: To evaluate the expression of Th1, Th2, and Th17 cytokines in patients with systemic lupus erythematosus (SLE), and verify the association between serum cytokine levels and vitamin D concentration. Methods: The sample consisted of 172 patients with SLE. 25-Hydroxyvitamin D (25(OH) D) levels were measured by chemiluminescence and 25(OH) D levels <20 ng/mL were considered to reflect vitamin D deficiency. Serum cytokine levels were measured in once-thawed samples, using a Th1/Th2/Th17 CBA (cytometric beads array) kit. Results: One hundred and sixty-one (93.6%) patients were women and 128 (74.4%) were of European descent. Mean patient age was 40.5 +/- 13.8 years, and mean age at diagnosis was 31.5 +/- 13.4 years. At the time of study entry, patients had a median (IQR) SLEDAI of 2 (1-4) and SLICC of 0 (0-1). Mean 25(OH) D concentration was 25.4 +/- 11.04 ng/mL. Fifty-nine (34.3%) patients had a vitamin D deficiency. No statistically significant associations were identified between cytokine and vitamin D levels. The most significant finding was a positive correlation between INF-alpha levels and SLEDAI (rs = 0.22, p = 0.04). Conclusion: Although vitamin D deficiencies are highly prevalent in patients with SLE, vitamin D levels were not significantly associated with patient cytokine profiles. The positive correlation between IFN-alpha levels and SLEDAI showed in this study corroborates other findings in the literature. The present results did not replicate those of in vitro studies of the effect of vitamin D levels on cytokine profiles. Placebo-controlled intervention trials of the effect of vitamin D on cytokine profiles are still required before any definitive conclusions can be drawn regarding the association between these variables.