RESUMO
BACKGROUND:Astrocytes play an important role in the pathology of central nervous system diseases.The phenotypic and functional changes in astrocytes suggest that it may be an effective therapeutic target for central nervous system diseases.Our previous studies have confirmed that astragaloside can inhibit the lipopolysaccharide-induced astrocyte inflammatory response.Whether astragaloside can regulate the phenotype and function of astrocytes through Notch-1 and its downstream signaling pathway remains unclear. OBJECTIVE:To explore the effect of astragaloside on astrocyte activation and inflammatory response induced by inflammation and its possible mechanism. METHODS:Cerebral cortex astrocytes derived from neonatal C57BL/6 mouse were cultured in vitro.CCK-8 assay was used to determine the optimum concentration of astragaloside and Notch active inhibitor DAPT.The astrocytes were divided into five groups:PBS group,lipopolysaccharide group,lipopolysaccharide + astragaloside group,lipopolysaccharide + DAPT group and lipopolysaccharide + DAPT + astragaloside group.The secretion level of inflammatory factors was detected by ELISA,and the level of nitric oxide was detected by Griess method.The astrocytes and splenic mononuclear cells were co-cultured in Transwell chamber to observe the migration of CD4T cells.The expression of astrocyte activation marker GFAP,A1 marker C3 and A2 marker S100A10 as well as Notch 1 and Jag-1 was detected by immunofluorescence staining.The expressions of CFB,C3,S100A10,PTX3,Notch-1,Jag-1,and Hes were detected by western blot assay. RESULTS AND CONCLUSION:(1)According to the results of CCK8 assay,the final concentration of astragaloside was selected as 25 μmol/L and the final concentration of DAPT was 50 μmol/L for follow-up experiments.(2)Compared with PBS group,interleukin-6,interleukin-12 and nitric oxide secretion levels in the lipopolysaccharide group were significantly increased(P<0.05,P<0.05,P<0.01).Compared with the lipopolysaccharide group,interleukin-6(all P<0.05),interleukin-12(P>0.05,P<0.05,P<0.05)and nitric oxide(P<0.05,P<0.01,P<0.01)secretion significantly reduced in the lipopolysaccharide + astragaloside group,lipopolysaccharide +DAPT group,lipopolysaccharide + DAPT + astragaloside group.(3)Compared with the PBS group,the expression of GFAP that is the marker of activated astrocytes and the migration of CD4 T cells were significantly increased in the lipopolysaccharide group(P<0.01).Compared with the lipopolysaccharide group,astrocyte activation was significantly inhibited and CD4 T cell migration was significantly reduced in the lipopolysaccharide + astragaloside,lipopolysaccharide +DAPT,lipopolysaccharide + DAPT + astragaloside group(P<0.05,P<0.05,P<0.01).(4)Compared with the PBS group,the expressions of A1 markers C3 and CFB in the lipopolysaccharide group were increased(P<0.01,P<0.05),and the expressions of A2 markers S100A10 and PTX3 were decreased(P<0.01,P<0.05).Compared with the lipopolysaccharide group,C3(all P<0.01)and CFB(both P<0.05)were significantly reduced and S100A10(all P<0.01)and PTX3(P<0.05,P<0.05 and P>0.05)were increased in the lipopolysaccharide + astragaloside,lipopolysaccharide +DAPT,lipopolysaccharide + DAPT + astragaloside group.(5)Compared with the PBS group,the expressions of Jag-1,Notch-1 and Hes in the lipopolysaccharide group were significantly increased(all P<0.01).Compared with the lipopolysaccharide group,the expressions of Jag-1(all P<0.01),Notch-1(all P<0.01)and Hes(P<0.05,P<0.01 and P<0.01)were significantly reduced in the lipopolysaccharide + astragaloside,lipopolysaccharide +DAPT,lipopolysaccharide + DAPT + astragaloside group.(6)The results indicate that astragaloside can promote the transformation of astrocytes from A1 to A2 by regulating Notch-1 signaling pathway,reduce the secretion of inflammatory factors and the migration of CD4 T cells,and thus inhibit astrocyte activation and inflammatory response.