The Roles Of CPLA₂ And Chemokines MCP-1, MIP-1a In The Pathogenesis Of EAE

Objective:1 , To establish animal model of experimental autoimmune encephalomyelitis (EAE) induced by peptide myelin oligodendrocyte glycoprotein (MOG)35-55.2, To investigate the role of monocyte chemoattractant protein-1 (MCP-1)and macrophage inflammatory protein-la (MIP-1a) in the pathogenesis of EAE.3, To study the role of cytosolic phospholipase A2 (CPLA2) and itscorrelation with chemokines MCP-1, MlP-la in the pathogenesis of MOG-induced EAE and try to find a new therapeutic target to Multiple Sclerosis (MS).4, To understand the mechanism of action underlying the beneficial effect of IFN 8 in MS by investigating the effects of IFN β-1b on chemokines production in the central nervous system (CNS) of EAE mice.Methods:1 , C57BL/6 (H-2b) mice were induced to EAE by injecting subcutaneously MOG35.55 peptide in CFA . Both the clinical symptoms and histopathologic changes of the CNS were observed.2, The expressions of CPLA2, MCP-1 and MIP-1a in the spinal cord in different stages of EAE were observed and the cellular categories producing MCP-1 or MlP-la in CNS were identified respectively by immunohistochemistry.3, C57BL/6 mice were treated by intraperitoneal injections of 200μ1AACOCF3, a selective chemical inhibitor of cPLA2, at 2mM or 4mM or by injecting subcutaneously 200μl recombinant human IFN β-1b at 10,000 units on alternate days from the day of EAE induction until day 16. We compared the diffences of clinical symptoms and histopathologic changesamong groups. The expressions of MCP-1 and MlP-la and level of MCP-1 mRNA in the spinal cord among groups were also compared by immunohistochemistry and in situ hybridization.Results:1 ^ The experimental group all developed the typical symptoms of EAE ondays 16.1±3.9 post-immunization with the incidence of 100% and showed a chronic monophasic course. The infiltration of mononuclear cells in the perivasculars and the demyelination of the white matter were observed through optical microscope. No significant difference between female mice and male mice was observed in the incidence of disease, clinical course and histological findings in the CNS.2. Increased CPLA2 expression was seen in endothelial cells and immunecells at the site of EAE lesions early in the course of the disease. It became weaked at recovery stage of EAE.3> Reactive hypertrophic astrocytes were strongly immunoreactive for MCP-1, while MlP-la was produced mainly by microglia. The productions in the CNS of these two chemokines were increased to correlate with disease development.4^ IFN 6-lb reduced the disease activity, significantly decreased MCP-1 and MlP-la expressions and down-regulated MCP-1 mRNA level in the spinal cord of EAE mice.5 * AACOCF3 had dose-dependent actions on reducing the disease severity, decreasing the expressions of MCP-1 and MlP-la and down-regulating the level of MCP-1 mRNA in the lesions of EAE mice. When administrated with high dose, its therapeutic effect to EAE seemed superior to that of IFN 6-lb.Conclusions:1 > The EAE mice induced by MOG35.55 peptide was stable and had high incidence, which might be an ideal model to study MS.2. Chemokines MCP-1 and MlP-la are expressed in different glial cells in the CNS of EAE mice and are important proinflammatory cytokines for trafficing immune cells to infiltrate into CNS.3> CPLA2 may contribute to the influx of inflammatory cells into the CNS in...