The Modulatory Effects of Vitamin D on the Expression of IL-12 and TGF-β in the Spinal Cord and Serum of Mice with Experimental Autoimmune Encephalomyelitis.

Background & objective: The immunoregulatory effects of transforming growth factor (TGF)-βand interleukin-12 (IL-12) and immunomodulatory actions of vitamin D (VD) were reported in several studies. This study aims to evaluate VD effects on IL-12 and TGF-β expression in experimental autoimmune encephalomyelitis (EAE).

Methods: EAE was induced in three groups of C57BL/6 mice by immunization with MOG and administered intra-peritoneally 200 ngVD, PBS or olive oil (OO) from day +3 to +30. One group was also considered as healthy control group. At day 31, cytokines expression in the spinal cord and their serum levels were determined using real time-PCR and ELISA, respectively.

Results: IL-12 gene expression and its serum levels in PBS-injected- or OO-administrated EAE groups were significantly higher than healthy group. IL-12 gene expression in EAE group treated with VD was significantly decreased compared to PBS-injected- or OO-administrated EAE groups (P<0.001 and P<0.02, respectively). Serum IL-12 levels were significantly reduced in VD-treated EAE mice compared to PBS-injected- or OO-administrated EAE groups (P<0.004 and P<0.05, respectively). No significant difference was observed between PBS-injected-EAE, OO-administrated EAE and healthy groups regarding the expression of TGF-β. In EAE mice treated with VD, TGF-β expression was significantly higher than healthy group and PBS-injected EAE mice (P<0.01 and P<0.04, respectively). VD-treated EAE group had also higher serum TGF-β levels than PBS-injected-, OO-administrated and healthy groups (P<0.05).

Conclusion: VD modulates the expression of IL-12 and TGF-β in spinal cord and serum of EAE mice.