Vitamin D supplementation up-regulates IL-6 and IL-17A gene expression in multiple sclerosis patients

•IL-6 and IL-17A gene expression up-regulate under vitamin D treatment.•No correlation was observed between EDSS scores with IL-6 and IL-17A expression.•Some MS patients are not responsive to vitamin D supplementation.•Personalizing medicine can tell why some MS patients do not respond to vitamin D supplementation.

Vitamin D regulates gene expression and affects target cell functions. IL-6 and IL-17A are pro-inflammatory cytokines associated with MS pathogenesis. The aim of this study was to investigate the vitamin D effects on the expression level of IL-6 and IL-17A in peripheral blood mononuclear cells (PBMCs) of multiple sclerosis (MS) patients. Also, we performed a correlation analysis between the gene expression and some clinical features such as serum level of vitamin D and the expanded disability status scale (EDSS). Significant up-regulation of IL-6 and IL-17A gene expression was shown under vitamin D treatment. Also, some gender specific correlations between the gene expression with vitamin D levels were detected in female RR-MS patients.