Unit of Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, Fribourg, Switzerland.
Institute of Virology and Immunology, Sensemattstrasse 293, Mittelhäusern, Switzerland.
Sci Rep. 2019 Mar 18;9(1):4833. doi: 10.1038/s41598-019-41302-1.
The neurotropic Japanese encephalitis virus (JEV) is responsible for Japanese encephalitis, an uncontrolled inflammatory disease of the central nervous system. Microglia cells are the unique innate immune cell type populating the brain that cross-communicate with neurons via the CXCR1-CXCL1 axis. However, microglia may serve as a viral reservoir for JEV. Human microglia are able to transmit JEV infectivity to neighbouring cells in a cell-to-cell contact-dependent manner. Using JEV-treated human blood monocyte-derived microglia, the present study investigates molecular mechanisms behind cell-to-cell virus transmission by human microglia. For that purpose, JEV-associated microglia were co-cultured with JEV susceptible baby hamster kidney cells under various conditions. Here, we show that microglia hosting JEV for up to 10 days were able to transmit the virus to susceptible cells. Interestingly, neutralizing anti-JEV antibodies did not completely abrogate cell-to-cell virus transmission. Hence, intracellular viral RNA could be a contributing source of infectious virus material upon intercellular interactions. Importantly, the CXCL1-CXCR1 axis was a key regulator of cell-to-cell virus transmission from JEV-hosting human microglia. Our findings suggest that human microglia may be a source of infection for neuronal populations and sustain JEV brain pathogenesis in long-term infection. Moreover, the present work emphasizes on the critical role of the CXCR1-CXCL1 axis in JEV pathogenesis mediating transmission of infectious genomic JEV RNA.
神经亲和性日本脑炎病毒 (JEV) 是引起日本脑炎的罪魁祸首,日本脑炎是一种中枢神经系统不受控制的炎症性疾病。小胶质细胞是唯一存在于大脑中的固有免疫细胞类型,通过 CXCR1-CXCL1 轴与神经元进行交叉通讯。然而,小胶质细胞可能是 JEV 的病毒储存库。人类小胶质细胞能够以细胞间接触依赖的方式将 JEV 感染性传递给邻近细胞。本研究使用 JEV 处理的人类血单核细胞衍生的小胶质细胞,研究了人类小胶质细胞通过细胞间传播病毒的分子机制。为此,在各种条件下,将携带 JEV 的小胶质细胞与 JEV 易感的幼仓鼠肾细胞共培养。在这里,我们表明,携带 JEV 长达 10 天的小胶质细胞能够将病毒传播给易感细胞。有趣的是,中和抗 JEV 抗体并不能完全阻断细胞间病毒传播。因此,细胞内病毒 RNA 可能是细胞间相互作用时传染性病毒物质的来源。重要的是,CXCL1-CXCR1 轴是 JEV 感染的人类小胶质细胞向易感细胞进行细胞间病毒传播的关键调节剂。我们的研究结果表明,人类小胶质细胞可能是神经元群体感染的来源,并在长期感染中维持 JEV 大脑发病机制。此外,本研究强调了 CXCR1-CXCL1 轴在 JEV 发病机制中作为传染性 JEV RNA 传播的关键调节因子的重要作用。