Regionally distinct astrocyte interferon signaling promotes blood-brain barrier integrity and limits immunopathology during neurotropic viral infection

The role of astrocytes in innate immunity during viral infections of the central nervous system (CNS) remains to be fully elucidated. Here, we demonstrate that type I interferon (IFN) receptor (IFNAR) signaling in astrocytes regulates blood-brain barrier permeability and protects the cerebellum from infection and immunopathology. Mice with astrocytes lacking IFNAR signaling showed decreased survival after West Nile virus infection that was not due to expanded viral tropism or increased replication. Pattern recognition receptors and IFN-stimulated genes (ISGs) had higher basal and IFN-induced expression in human and mouse cerebellar astrocytes compared to cerebral cortical astrocytes. Our data identify cerebellar astrocytes as key responders to viral infection and highlight distinct innate immune programs in astrocytes from evolutionarily disparate regions of the CNS. Primary human astrocytes were maintained on collagen-coated tissue culture plates in a complete astrocyte medium (ScienCell Laboratories) in 2% FBS. Prior to isolation of RNA, cells were treated for 4 hours with 10U/ml recombinant human IFN-β or a PBS vehicle. Cells were then lysed in buffer RLT (Qiagen).

星形胶质细胞（astrocytes）在中枢神经系统（CNS）病毒感染期间的固有免疫作用仍有待完全阐明。在此，我们证实星形胶质细胞中的I型干扰素（IFN）受体（IFNAR）信号通路可调控血脑屏障通透性，并保护小脑免受病毒感染及免疫病理损伤。缺失IFNAR信号通路的星形胶质细胞小鼠在感染西尼罗河病毒后存活率下降，且该现象并非由病毒嗜性扩大或复制增强所导致。与大脑皮层星形胶质细胞相比，人类及小鼠小脑星形胶质细胞中的模式识别受体与干扰素刺激基因（ISGs）具有更高的基础表达水平及IFN诱导表达水平。本研究数据明确小脑星形胶质细胞是病毒感染的关键应答细胞，并凸显了中枢神经系统不同进化区域星形胶质细胞所具有的差异化固有免疫程序。原代人星形胶质细胞于胶原蛋白包被的组织培养板中，使用完全星形胶质细胞培养基（ScienCell Laboratories）及2%胎牛血清（FBS）进行培养。在提取核糖核酸（RNA）前，细胞用10U/ml重组人IFN-β或PBS对照处理4小时。随后将细胞在RLT缓冲液（Qiagen）中裂解。