National Brain Research Centre, Manesar, Haryana-122050, India.
Immunobiology. 2010 Nov;215(11):884-93. doi: 10.1016/j.imbio.2009.12.003. Epub 2009 Dec 24.
Japanese encephalitis virus (JEV) is a neurotropic flavivirus that is the causative agent of a major mosquito-borne encephalitis in the world. Evasion of peripheral immune system facilitates the entry of the virus into the central nervous system (CNS) where it causes extensive neuronal inflammatory damage that leads to death or severe neuropschychiatric sequel in survivors. It has been proposed that after entry into the body, the virus is carried into the CNS by peripheral immune cells that act as Trojan horses. In this study we investigate whether macrophages can be considered as such a Trojan horse. We also investigate the role of minocycline, a synthetic tetracycline, in such processes. Minocycline has been found to be broadly protective in neurological disease models featuring inflammation and cell death but there has been no report of it having any modulatory role in peripheral macrophage-mediated immune response against viral infection. Persistence of internalized virus within macrophages was visualized by immunofluorescent staining. Cytotoxicity assay revealed that there was no significant cell death after 24 h and 72 h infection with JEV. Proinflammatory cytokine levels were elevated in cells that were infected with JEV but it was abrogated following minocycline treatment. Reactive oxygen species level was also increased after JEV infection. Nitric oxide level was found to increase after 72 h post infection but remained unchanged after 24h. The cellular levels of signaling molecules such as PI3 kinase, phophoAkt and phospho p38MAP kinase were found to be altered after JEV infection and minocycline treatment. JEV infection also affected the VEGF-MMP pathway. Increased activity of MMP-9 was detected from JEV-infected macrophage culture supernatants after 72 h; minocycline treatment resulted in reduced activity. Thus it seems that minocycline dampens peripheral immune reactions by decreasing proinflammatory cytokine release from infected macrophages and the virus survives within macrophages long enough to be carried into the CNS, even though minocycline inhibits cell survival.
日本脑炎病毒（JEV）是一种神经嗜性黄病毒，是世界上主要由蚊子传播的脑炎的病原体。逃避外周免疫系统有助于病毒进入中枢神经系统（CNS），在那里它引起广泛的神经元炎症损伤，导致死亡或幸存者的严重神经精神后遗症。有人提出，进入体内后，病毒被作为特洛伊木马的外周免疫细胞携带到中枢神经系统。在这项研究中，我们研究了巨噬细胞是否可以被视为这样的特洛伊木马。我们还研究了米诺环素（一种合成四环素）在这些过程中的作用。米诺环素已被发现对具有炎症和细胞死亡的神经疾病模型具有广泛的保护作用，但尚无报道称其在针对病毒感染的外周巨噬细胞介导的免疫反应中具有调节作用。通过免疫荧光染色可视化内化病毒在巨噬细胞内的持续存在。细胞毒性测定显示，感染 JEV 后 24 小时和 72 小时没有明显的细胞死亡。感染 JEV 的细胞中促炎细胞因子水平升高，但米诺环素处理后被阻断。感染 JEV 后还增加了活性氧水平。感染 JEV 后 72 小时发现一氧化氮水平增加，但 24 小时后不变。感染 JEV 后，细胞内信号分子如 PI3 激酶、磷酸化 Akt 和磷酸化 p38MAP 激酶的水平也发生了改变，米诺环素处理后也发生了改变。JEV 感染还影响了 VEGF-MMP 途径。感染 JEV 的巨噬细胞培养上清液中检测到 MMP-9 活性增加，72 小时后；米诺环素处理导致活性降低。因此，似乎米诺环素通过减少感染巨噬细胞中促炎细胞因子的释放来抑制外周免疫反应，并且病毒在巨噬细胞内存活足够长的时间被携带到中枢神经系统，尽管米诺环素抑制细胞存活。
