CVB3感染对星形胶质细胞表达agrin的影响及意义

目的检测柯萨奇B3病毒（coxsackievirus group B type3，CVB3）感染体外培养的星形胶质细胞后集聚蛋白（agrin）的表达变化及其意义。方法采用免疫细胞化学的方法鉴定培养的星形胶质细胞，在显微镜下观察CVB3感染后的细胞形态，并用RT-PCR方法扩增CVB3RNA的正负链以确证感染成功，用RT-PCR检测CVB3感染细胞后agrin的动态表达变化。用脂质体将agrin反义质粒pcDNA3-As-AG转染到星形胶质细胞，并用RT-PCR检测转染的细胞中agrin的表达。3H-TdR掺人法测定CVB3不同感染时间点的星形胶质细胞裂解液和经agrin反义质粒pcDNA-As-AG转染细胞后的细胞裂解液对T细胞增殖的影响。结果（1）CVB3感染星形胶质细胞后agrin的表达水平下调。（2）病毒感染后随着agrin表达量的降低，星形胶质细胞裂解液对T细胞的活化增殖作用也降低。未转染和空质粒转染的细胞裂解液对T细胞的活化增殖有促进作用，而用反义核酸技术下调星形胶质细胞agrin表达后，星形胶质细胞裂解液对T细胞增殖的促进作用也随之下降，进一步证实agrin表达水平的下调可影响T细胞的活化和增殖。结论CVB3感染星形胶质细胞后agrin表达水平下凋，降低对T细胞活化增殖的能力，这可能是CVB3病毒性脑炎中，病毒逃逸机体免疫清除的一种机制。

The alteration of agrin expression in CVB3 infected astrocytes and its significance

Purpose To detect the alteration of agrin expression in CVB3 infected astrocytes and explore its significance. Methods Primarily cultured astrocytes were identified by immunocytochemistry,the morphology of CVB3 infected astrocytes was observed at different time points and the infection was reconfirmed with the evidence of the existence of positive and negative strands of CVB3.The expression of agrin was detected by RT-PCR.Astrocytes were transfected with agrin anti-sense plasmid pcDNA3-As-AG by liposome and the influence of cell lysates on T cell proliferation was observed by 3H-TdR incorporation assay in CVB3 infected or agrin anti-sense plasmid transfected astrocytes. Results CVB3 infection down-regulated agrin expression in astrocytes,the cell lysates in infected astroyctes decreased T cell proliferation.Agrin expression was reduced in anti-sense plasmid pcDNA3-As-AG transfected astrocytes,and the transfected cell lysates also decreased T cell proliferation.It is indicated that the decrease agrin expression in astrocytes could influence T cell proliferation. Conclusions Agrin expression is down-regulated in astrocytes infected by CVB3,so as to decreased T cell proliferation.It might be a novel mechanism by which CVB3 escapes from immune clearance in viral encephalitis.