Vitamin D Modulates the Expression of IL-27 and IL-33 in the Central Nervous System in Experimental Autoimmune Encephalomyelitis

Background: It has been reported that vitamin D has broad anti-inflammatory and immunomodulatory effects. Objective: To evaluate the effects of vitamin D on the expression of IL-27 and IL-33 in a model of experimental autoimmune encephalomyelitis (EAE). Methods: EAE was induced in C57BL/6 mice by immunization with myelin oligodendroglial glycoprotein mixed with complete Freundʹs adjuvant. The mice were administered with PBS or olive oil, intraperitoneally, in the control groups and vitamin D (200 ng every two days) in the treatment group, from day +3 to +30. At day 31, the mice were scarified and their spinal cords and brains were harvested. The expression of the IL-27 and IL-33 mRNA in the spinal cord was measured using real time-PCR. Results: In PBS- or olive oil-treated EAE mice the expression of IL-27 P28 mRNA was significantly lower than that in the healthy control group (p<0.002). In both PBS- and olive oil-treated EAE groups, the expression of IL-27 EBI3 mRNA was also lower than that observed in the healthy group, but the differences were not significant. In vitamin D-treated EAE group, the expression of IL-27 P28 and IL-27 EBI3 were significantly higher compared with the olive oil-treated EAE groups (p<0.002 and p<0.04, respectively). The expression of IL-33 was significantly higher in PBS-or olive oil-treated EAE groups compared with healthy mice (p<0.05 and p<0.02, respectively). Vitamin D significantly decreased the expression of IL-33 compared with PBSor olive oil-treated EAE mice (p<0.04, p<0.02, respectively). The PBS- or e oiloliv-treated EAE mice showed the clinical symptoms of EAE at days 9 and 10, respectively. The vitamin D-treated EAE group exhibited the symptoms at day 12 post immunization. The maximum mean clinical score and mean pathological scores were also significantly lower in vitamin Dtreated EAE group, in comparison with PBS- or olive oil treated EAE mice (p<0.001). Conclusion: Vitamin D may modulate the expression of IL-27 and IL-33 in the spinal cord of EAE mice and also ameliorate the clinical symptoms of the disease.