Role of Microglia in Protection Against West Nile Virus-induced CNS Injury: mechanisms and treatment strategies

病毒诱导的中枢神经系统（CNS）疾病的治疗是次优的，或 根本不存在西尼罗河病毒（WNV）是美国流行性脑炎最常见的原因。这 一项提案将研究小胶质细胞在CNS感染西尼罗河病毒期间的作用，并将评估小胶质细胞在中枢神经系统中的作用。 刺激作为WNV诱导的CNS疾病的潜在治疗策略。 CNS的病毒感染导致强烈的宿主神经炎症反应，包括 激活CNS免疫细胞（小胶质细胞）。小胶质细胞在病毒诱导的中枢神经系统疾病中的作用仍然存在 不清楚它们可能在促进感染细胞的清除和细胞的恢复方面起保护作用。 受损的神经元然而，由小胶质细胞释放的许多因子可能导致脑内的损伤。 CNS。事实上，一般的神经炎症和小胶质细胞活化是关键的致病因素， 神经损伤后和非感染性神经和神经变性 疾病我们的体内和体外模型将使我们能够比较小胶质细胞在脑和脊髓中的作用。 线.由于小胶质细胞是多种CNS损伤和疾病病理学的中心， 对于神经退行性疾病，所提出的实验可能具有广泛的临床意义。 我们最近发现，小胶质细胞的耗竭，与殖民地1， （CSFR 1）拮抗剂PLX 5622导致小鼠中WNV诱导的CNS疾病的严重程度增加， 与CNS病毒滴度增加相关。在本提案的具体目标1中，我们将使用PLX 5622靶向 消耗小胶质细胞以确定小胶质细胞是否在病毒进入细胞时影响病毒生长。 CNS、CNS内的病毒复制或病毒清除。小胶质细胞的功能是识别和清除入侵 病原体通过吞噬感染或受损的细胞，通过充当抗原呈递细胞， 产生完整的抗原特异性T细胞应答，并分泌免疫调节分子。在 具体目标2，我们将确定这些机制是小胶质细胞抑制WNV生长所必需的 在CNS。 在具体目标3中，我们将确定小胶质细胞刺激作为治疗策略的疗效， WNV诱导的CNS疾病。在这些研究中，我们将使用粒细胞-巨噬细胞集落刺激因子 （GM-CSF），一种造血生长因子和促炎细胞因子，其诱导、增殖和 激活小胶质细胞重组人GM-CSF已经被FDA批准用于治疗白色 血细胞计数低，例如某些类型的白血病或骨髓移植受者。GM-CSF 目前正在研究作为一种潜在的治疗与阿尔茨海默氏症有关的认知问题的方法 疾病小鼠将用重组人GM-CSF（Leukine）处理，并将监测以确定 病毒CNS滴度，病毒诱导的组织损伤和死亡，以及神经系统后遗症的持续性， 幸存的老鼠

Treatments for virus-induced diseases of the central nervous system (CNS) are sub-optimal or nonexistent. West Nile virus (WNV) is the most common cause of epidemic encephalitis within the US. This proposal will investigate the role of microglia during WNV infections of the CNS and will evaluate microglial stimulation as a potential treatment strategy for WNV-induced CNS disease. Virus infection of the CNS results in a robust host neuroinflammatory response, including the activation of CNS immune cells (microglia). The role of microglia in virus-induced CNS disease remains unclear. They likely play a protective role in facilitating the removal of infected cells and the recovery of damaged neurons. However, many of the factors released by microglia may contribute to injury within the CNS. Indeed, neuroinflammation in general and microglia activation in particular are key pathogenic components following neurologic injury and during noninfectious forms of neurologic and neurodegenerative disease. Our in vivo and ex vivo models will allow us to compare the role of microglia in the brain and spinal cord. Since microglia are central to a variety of CNS injury and disease pathologies, including neurodegenerative diseases, the proposed experiments will likely have wide reaching clinical implications. We have recently shown that depletion of microglia, with the colony stimulating factor receptor 1 (CSFR1) antagonist PLX5622, results in increased severity of WNV-induced CNS disease in mice that is associated with an increase in CNS viral titers. In Specific Aim 1 of this proposal we will use PLX5622 targeted depletion of microglia to determine whether microglia impact viral growth at the point of viral entry into the CNS, viral replication within the CNS, or viral clearance. Microglia function to identify and remove invading pathogens by phagocytosing infected or damaged cells, by acting as antigen presenting cells required to generate a complete antigen specific T cell response, and by secreting immune modulatory molecules. In Specific Aim 2 we will determine which of these mechanisms are required for microglia to inhibit WNV growth in the CNS. In Specific Aim 3 we will determine the efficacy of microglial stimulation as a treatment strategy for WNV-induced CNS disease. For these studies we will use granulocyte-macrophage colony-stimulating factor (GM-CSF), a haematopoietic growth factor and proinflammatory cytokine, that induces, proliferates, and activates microglia. Recombinant human GM-CSF is already FDA-approved to treat conditions in which white blood cell counts are low, such as in certain types of leukemia or bone marrow transplant recipients. GM-CSF and is currently being investigated as a potential treatment for cognitive problems related to Alzheimer's disease. Mice will be treated with recombinant human GM-CSF (Leukine) and will be monitored to determine viral CNS titers, virus-induced tissue injury and death, and the persistence of neurological sequelae in surviving mice.