The Therapeutic Effects Of1,25-dihydroxyvitamin D3Induced Tolerogenic Dendritic Cells On The Experimental Autoimmune Encephalomyelitis Of Mice

Background and Objective: Autoimmune diseases are the result of an imbalanced immuneregulatory network. Tolerogenic dendritic cells (TolDCs) are key players of this network byinducing and maintaining both central and peripheral tolerance. Therefore, ex vivo generatedTolDCs are considered as therapeutic vaccines to re-establish antigen-specific tolerance inautoimmune disorders. The treatment with TolDCs is a promising, cell-based strategy to regulateautoimmune diseases such as multiple sclerosis (MS) in an antigen-specific way. The purpose ofthis study was to analyze the in vivo effect of1,25-dihydroxyvitamin D3(1,25(OH)2D3) inducedTolDCs on experimental autoimmune encephalomyelitis (EAE), an animal model of MS.Methods: Encephalomyelitis was induced in C57BL/6mice by immunization withMOG35-55emulsified in complete Freund’s adjuvant containing4mg/mL of Mycobacteriumtuberculosis H37RA. The clinical expression of EAE was graded on a clinical index scale0–5.Bone marrow-derived DCs cultured in the presence of1,25(OH)2D3and pulsed with peptide35-55of the myelin oligodendrocyte glycoprotein (MOG35-55) were administrated preclinically,and therapeutically to EAE-induced mice. Flow cytometer analysis was performed to detectcertain specific molecular markers of TolDC, including MHC-II, CD40, CD80, CD83and CD86.After the adoptive transfer of normal DCs and1,25(OH)2D3induced DCs (VdDCs), wecompared the clinical scores of4different groups-the blank control group, the negative controlgroup, the normal-DC treated group and the VdDC treated group.Results: EAE was actively induced in mice and the onset of the disease was on the12thdaypost immunization. The percentage of CD11c+DC in VdDCs is92.8%while that in normal DCsis71.9%. The VdDC treatment decreased the expression of MHC-II (P=0.0002<0.001) andCD86(P<<0.001) in relation to the treatment of normal DCs, which is a tolerogenic profile ofthe VdDCs. This study provided evidence that the adoptive transfer of both the normal bonemarrow-derived DCs (P=0.0092<0.05) and the1,25(OH)2D3-induced TolDCs(P=6.88×10-9<0.001) could ameliorate the severity of the clinical signs comparing to negative control group, when TolDCs lead to a more significant decrease in the clinical scores(P=0.0024<0.05). Furthermore, The VdDC treatment (14.6±0.4days, P=5.47×10-4<0.001)postponed the onset of EAE compared with the untreated control (12.5±0.3days) group whilethe normal treatment (12.3±0.4, P=0.859>0.016) didn’t.Conclusions:①We successfully induced EAE in mice;②1,25(OH)2D3induced DCspresented a tolerogenic profile with decreased MHC-II and CD86expression;③The adoptivetransfer of1,25(OH)2D3induced TolDCs can not only ameliorate the clinical course of EAE, butalso postpone the onset of the disease.