Immunoregulation of Herpes Encephalitis By Microglia

描述(申请人提供)：单纯疱疹病毒1型(HSV)是HIV-1感染患者的一种重要的机会性病原体，也是正常宿主中枢神经系统毁灭性感染的原因。尽管对HSV的免疫应答一直是深入研究的主题，但免疫介导的病理在HSV相关脑损伤中的作用尚不清楚。在这一提议中，需要检验的中心假设是，小胶质细胞在应对HSV感染时产生的趋化因子引发了一系列神经免疫反应，导致疱疹脑炎期间出现的严重脑损伤。为了验证这一假设，将HSV感染小鼠大脑中的趋化因子产生与高纯度小鼠神经胶质细胞和神经细胞培养以及感染HSV的小鼠器官型脑片中的趋化因子进行比较。这种方法将使我们能够区分小胶质细胞趋化因子的产生与体细胞免疫系统的细胞产生的趋化因子。此外，器官型脑片培养的使用将使我们能够专门耗尽“功能丧失”实验中的小胶质细胞。然后，我们将研究小胶质细胞产生的免疫介质对培养的小鼠神经元的神经毒性作用。小胶质细胞驱动的白细胞进入大脑的研究将通过确定趋化因子的中和抗体是否抑制T细胞的渗透来进行。将通过确定体内T细胞的耗尽是否会延缓脑炎以及过继转移HSV特异性淋巴细胞是否恢复脑炎表型来研究T细胞渗透的神经致病作用。在有和没有HSV特异性CD4+和CD8+淋巴细胞转移的脑片培养中比较神经病理学，将使我们能够区分由病毒感染引起的损伤和由免疫致病机制引起的脑损伤。小胶质细胞趋化因子产生的下调通过外周苯二氮卓类受体(BDZ)介导的细胞失活将被检测。我们将确定用BDZ灭活小胶质细胞是否会抑制神经毒性因子的产生。最后，我们将研究BDZ配体在体内对趋化因子的产生、T细胞的转运以及脑炎发展的影响。这些体内、体外和体外模型将为我们提供研究疱疹脑炎期间发生的神经发病机制、神经炎症、神经毒性和神经免疫介导的病理的能力。从这些研究中获得的知识将增加我们对小胶质细胞和趋化因子网络在疱疹脑炎期间调节脑部炎症的作用的了解，最终目标是找到治疗这种严重脑部感染的新方法。

DESCRIPTION (provided by applicant): Herpes simplex virus 1 (HSV) is an important opportunistic pathogen in HIV-1-infected patients as well as the cause of a devastating CNS infection in normal hosts. Although immune responses to HSV have been the subject of intense investigation, the role of immune-mediated pathology in HSV-related brain damage is unknown. In this proposal, the central hypothesis to be tested is that chemokines produced by microglial cells in response to HSV infection initiate a cascade of neuroimmune responses that result in the serious brain damage seen during herpes encephalitis. To test this hypothesis, chemokine production in the brains of HSV-infected mice will be compared to that in cultures of highly purified murine glial and neuronal cells, and in murine organotypic brain slices infected with HSV. This approach will allow us to differentiate microglial cell chemokine production from that of cells of the somatic immune system. Additionally, the use of organotypic brain slice cultures will enable us to specifically deplete microglial cells for "loss-of-function" experiments. We will then investigate the neurotoxic effects of microglial cell-produced immune mediators on cultured murine neurons. Microglia-driven leukocyte trafficking into the brain will be investigated by determining if neutralizing antibodies to chemokines inhibit T-cell infiltration. The neuropathogenic role of T-cell infiltration will be studied by determining if depletion of T-cells in vivo will delay encephalitis and whether adoptive transfer of HSV-specific lymphocytes restores the encephalitis phenotype. Comparing neuropathology in brain slice cultures with and without the transfer of HSV-specific CD4 + and CD8 +lymphocytes, will allow us to distinguish between injury generated by viral infection and brain damage provoked by immunopathogenic mechanisms. Downregulation of microglial cell chemokine production through peripheral benzodiazepine (BDZ) receptor-mediated cellular deactivation will then be examined. We will determine if deactivation of microglia with BDZs suppresses the production of neurotoxic factors. Finally, we will study the effects of BDZ ligands on chemokine production, T-cell trafficking, and the development of encephalitis in vivo. These in vivo, in vitro, and ex vivo models will provide us with the ability to investigate neuropathogenesis, neuroinflammation, neurotoxicity, and neuroimmune-mediated pathology occurring during herpes encephalitis. Knowledge gained from these studies will increase our understanding of the role of microglial cells and chemokine networks that regulate brain inflammation during herpes encephalitis with the ultimate goal of finding new therapy for this serious brain infection.