The Establishment Of The MOG Induced EAE Model And The Expression Of Cathepsin C In Acute And Chronic Phases

Objective: To establish mouse models of experimental autoimmuneencephalomyelitis (EAE) induced by peptide myelin oligodendrocyte glycoprotein(MOG35-55) and study of the expression of cathepsin C in acute and chronic phases.Methods:1. The establishment of EAE model: C57BL/6mice were immunized withMOG35～55peptide in complete freund’s adjuvant (CFA) subcutaneously, and injectedintraperitoneally with pertussis bacilli as EAE model, normal mice as control group, andimmunized with mixed emulsion except MOG peptide as sham group. Monitor bodyweight and record clinical scores based on behavior changes.2. Neuropathological observation: HE staining for observation of inflammatorycells infiltration in CNS; MBP（myelin basic protein，MBP）immunohistochemical (IHC)staining and Black Gold myelin staining for demyelinating changes; Iba-1and（myeloperoxidase，MPO）IHC staining for microglial changes and infiltration ofneutrophils.3. On21st day and41st day following the establishment of EAE model, cathepsinC expression was detected by IHC staining; MPO and Iba-1IHC staining followingcathepsin C in situ hybridization(ISH), respectively, for cellular localization ofcathepsin C.Result:1. General status and behavior score in EAE modelEAE mice showed depression, weight loss, flaccid tail, hind limbs weakness andhind limbs paralysis. The EAE mice developed the typical symptoms on10.3±1.58d,the average score was1.7±0.9. The most serious symptoms occurred on21day. Therewere no evident symptoms in control group and sham group. 2. Histopathological detectionHE staining showed typical “cuff” changes characterized by infiltratedinflammatory cells around the small blood vessels in CNS in EAE mice. MBP IHCstaining and Black Gold myelin staining showed in acute EAE model no demyelinationin the brain, while obvious demyelination in the spinal cord. In chronic model,demyelination was detected in both brain and spinal cord. MPO and Iba-1IHC stainingshowed microglia was activated and infiltration of neutrophils in EAE model. Nopathological changes were found in the control group and sham group.3.Expression of cathepsin C and cellular localizationCathepsin C was expressed exclusively in CAII neurons of hippocampus in thecontrol group and sham group. In EAE model, cathepsin C expression was detected indemyelinating areas in CNS. Iba-1, MPO IHC staining following cathepsin C ISHstaining showed that on21st day cathepsin C was expressed in microglia and infiltratingneutrophils; on41st day was mainly expressed by neutrophils.Conclusions:1.In the present study, MOG35-55-induced EAE mouse model was successful. Theinflammation in CNS and demyelination was progressive,with no relief.2. The expression of cathepsin C was enhanced in acute and chronic EAE model,indicating cathepsin C might be involved in inflammatory process and demyelination inCNS.