黄芪多糖抑制小鼠EAE及调控BV-2神经小胶质细胞活化的实验研究

摘要

目的:研究黄芪多糖(APS)对实验性自身免疫性脑脊髓膜炎(EAE)的治疗作用以及对参与EAE发病机制的神经小胶质细胞活化的调控作用及其可能的作用机制.方法:动物实验:MOG35-55诱导C57BL/6小鼠建立EAE模型,予APS给药干预,通过5级临床症状评分观察APS对小鼠EAE的治疗作用.细胞实验:MTT法检测脂多糖(LPS)对于BV-2神经小胶质细胞的增殖抑制作用,筛选合适的LPS刺激浓度活化神经小胶质细胞,构建BV-2神经小胶质细胞活化的模型;倒置显微镜观察BV-2神经小胶质细胞形态学的改变;ELISA法检测BV-2神经小胶质细胞IFN-γ、TNF-α的分泌水平变化;观察不同浓度的APS对BV-2神经小胶质细胞活化的调控作用;APS干预后,Western blot、Real-time PCR方法分别检测BV-2神经小胶质细胞PD-L1蛋白和mRNA表达水平的变化.结果:APS能够有效治疗小鼠EAE的临床症状,成功建立了体外BV-2神经小胶质细胞活化模型,一定浓度的APS能够抑制BV-2神经小胶质细胞的活化,提高活化的BV-2细胞的生存活性,降低IFN-γ、TNF-α的分泌水平,促进活化的BV-2神经小胶质细胞PD-L1基因及蛋白表达上调.结论:APS对小鼠EAE具有明显的治疗作用,其发挥作用的机制可能是APS能够有效抑制神经小胶质细胞的活化,降低炎性细胞因子IFN-γ、TNF-α的分泌,对神经小胶质细胞有抗炎保护作用,PD-1/PD-L1通路可能是APS发挥抗炎作用的重要途径.%Objective:To investigate the therapeutic effects of astragalus polysaccharide (APS) on experimental autoimmune encephalomyelitis(EAE) and to explore the regulating effects on microglia activation that is associated with the pathogenesis of EAE and its possible mechanisms.Methods:Animal experiments:EAE model was induced by MOG35-55in C57BL/6 mice.APS was given by gavage.EAE was scored according to a 0-5 scale to observe the therapeutic effects of APS.Cell experiments:The effects of lipopolysac-charide (LPS) on cell viability of BV-2 microglial cell line were investigated by MTT assay and then the appropriate concentration of LPS to activate the BV-2 microglial cell line was selected.The microglia activation model was established.The changes in BV-2 microglial cell line morphology were observed with an inverted microscope.The cytokines of TNF-α and IFN-γ in the cell culture supernatant of BV-2 microglial cell line were detected by ELISA.The activated BV-2 microglial cells were treated with APS in different concentrations.The regulatory roles of the APS on the BV-2 microglial cell activation were observed.Western blot and Real-time PCR method were used to measure the protein and mRNA level of the PD-L1 on the cell surface of BV-2 microglial cells treated with APS.Results:APS could effectively ameliorate the symptoms in EAE mice and could suppress neuroinflammation of EAE significantly.The microglia activation model in vitro induced by LPS was successful.APS in certain concentration could inhibit the activation of microglia,increase the viabilily of the active microglia.Meanwhile,it could downregulated the level of the cytokines including IFN-γ and TNF-α and upregulated the expression of protein and mRNA of PD-L1 on activated microglia.Conclusion:APS can effectively inhibit the autoimmune reaction of EAE and effectively suppress the microglia activation induced by LPS,reduce the pro-duction of IFN-γ and TNF-α.APS plays a crucial role in reducing the inflammation induced by microglia activation.The potential mech-anisms might be related to the upregualtion of the PD-1/PD-L1 pathway.