Mdivi-1,an Inhibitor Of Mitochondrial Fission,Reduces Oligodendrocyte Loss By Inhibiting The Intrinsic And Extrinsic Pathways Of Apoptosis In EAE Mice

Multiple sclerosis(MS)is an autoimmune demyelinating disease in the central nervous system(CNS).Oligodendrocyte(OLG)apoptosis is involved in triggering demyelination.Mitochondrial division inhibitor 1(Mdivi-1),a small molecule inhibitor of dynamin-related protein 1(Drp1),regulates mitochondrial fission.Our previous studies have shown that treatment with Mdivi-1 decreased the clinical score of experimental autoimmune encephalomyelitis(EAE),suppress spinal cord inflammation,and modulate systemic immune responses.However,it is not known whether Mdivi-1 is able to inhibit OLG apoptosis.For this reseason,the purpose of this research was designed to check the effects of Mdivi-1 on OLG apoptosis,and furthermore,the underlying mechanisms.MethodsTo prepare the animal models of EAE,30 female mice were classified into two groups:a dimethyl sulfoxide(DMSO)-treated EAE group and a Mdivi-1-treated EAE group.Then,luxol fast blue(LFB)staining,deoxyuride-5ˊ-triphosphate biotin nick end labelling(TUNEL)staining,and immunofluorescence staining with apoptotic signal proteins were performed to investigate the Mdivi-1 against demyelination and its associated mechanisms.Results1.Mdivi-1 administration suppressed the clinical symptom,alleviated the severity of EAE,inhibited inflammatory cell infiltration and demyelination in the spinal cord of of EAE,as well as protected the complexity of the OLG branches.2.Mdivi-1 administration effectively decreased the number of CC1~+TUNEL~+cells and the expression of Caspase-3,inhibited the expression of Bax,cytochrome C(Cytc),and Caspase-9,providing direct evidence for OLG apoptosis.Mdivi-1suppressed OLG apoptosis by inhibiting the expression of several proteins involved in the intrinsic apoptotic pathway.3.There was no significant difference of the expression of anti-apoptotic protein,Bcl-2,between the DMSO-treated control EAE mice and Mdivi-1-treated mice,demonstrating that Mdivi-1 treatment was able to inhibit the apoptotic proteins,but not improve the anti-apoptotic ability.4.Mdivi-1 administration also markedly reduced the high expression of FasL and Caspase-10 in the spinal cord of of EAE,indicating that Mdivi-1 can suppress the OLG extrinsic apoptotic pathway to keep myelin integrity.Conclusion:Taken together,our experiments demonstrate that Mdivi-1 administration suppressed the clinical symptom,alleviated the severity of EAE,inhibited inflammatory cell infiltration and demyelination in the spinal cord of EAE.Mdivi-1treatment prevents OLGs from apoptosis through inhibiting the intrinsic and extrinsic apoptotic pathways.