ABSTRACT
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.