Gu Jiaqi, Zhao Yuxue, Wu Jing, Chen Yiwen, Yin Yiqian, Jia Xiaonan, Mao Lingxiang
Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China.
Department of Laboratory Medicine, The Affiliated People's Hospital, Jiangsu University, Zhenjiang, Jiangsu, China.
J Med Virol. 2023 Jan;95(1). doi: 10.1002/jmv.28120. Epub 2022 Sep 12.
Central nervous system (CNS) infections caused by Enterovirus 71 (EV71) pose a serious threat to children, causing severe neurogenic complications and even fatality in some patients. However, the pathogenesis of EV71 infections in the CNS remains unclear.
An in vitro blood-brain barrier (BBB) model was constructed by coculturing brain microvascular endothelial cells (BMECs) and astrocytes in transwell inserts for simulating CNS infections. EV71 virions and small extracellular vesicles (sEVs) derived from EV71-infected cells (EV71-sEVs) were isolated from the cell culture supernatant by density gradient centrifugation. The BBB model was separately infected with EV71 virions and EV71-sEVs. The mechanism of crossing the BBB was determined by inhibiting the different endocytic modes. A murine model of EV71 infection was constructed for confirming the results of in vitro experiments.
The EV71-sEVs containing viral components were endocytosed by BMECs and released on the abluminal side of the BBB model, where they infected the astrocytes without disrupting the BBB in the early stages of infection. The integrity of the tight junctions (TJs) between BMECs was breached via downregulation of PI3K/Akt signaling in the late stages of infection.
EV71 utilized the circulating sEVs for infecting the CNS by crossing the BBB.
肠道病毒71型（EV71）引起的中枢神经系统（CNS）感染对儿童构成严重威胁，可导致严重的神经源性并发症，甚至在某些患者中导致死亡。然而，EV71感染中枢神经系统的发病机制仍不清楚。
通过在Transwell小室中共培养脑微血管内皮细胞（BMECs）和星形胶质细胞构建体外血脑屏障（BBB）模型，以模拟中枢神经系统感染。通过密度梯度离心从细胞培养上清液中分离出EV71病毒粒子和源自EV71感染细胞的小细胞外囊泡（sEVs，即EV71-sEVs）。将BBB模型分别用EV71病毒粒子和EV71-sEVs感染。通过抑制不同的内吞模式来确定穿越血脑屏障的机制。构建EV71感染的小鼠模型以证实体外实验结果。
含有病毒成分的EV71-sEVs被BMECs内吞，并在BBB模型的腔外侧释放，在感染早期它们感染星形胶质细胞而不破坏血脑屏障。在感染后期，通过下调PI3K/Akt信号通路破坏了BMECs之间紧密连接（TJs）的完整性。
EV71利用循环的sEVs通过穿越血脑屏障来感染中枢神经系统。
