Mechanisms of virus-induced injury in the brain and spinal cord

描述（由申请人提供）： 病毒通过杀死或破坏脑和脊髓内的神经元的基本功能来诱导中枢神经系统（CNS）中的疾病。我们建议使用病毒诱导的CNS疾病的良好表征模型来研究病毒引起神经元细胞死亡和脑和脊髓损伤的机制。我们将描绘特定的细胞信号通路参与病毒诱导的死亡和组织损伤的中枢神经系统内，并评估这些信号通路作为病毒诱导的中枢神经系统疾病的治疗靶点。我们的实验有望为病毒诱导的中枢神经系统疾病找到新的治疗靶点。 细胞凋亡是病毒性脑炎期间病毒诱导的细胞死亡的既定机制，并且在实验性感染多种病毒后在脑中发生。细胞凋亡也是病毒诱导的人类心肌炎中运动神经元细胞死亡的机制。凋亡细胞死亡的执行者半胱天冬酶3的抑制导致病毒诱导的脑炎的严重程度降低。在具体目标1中，我们将测试以下假设：抑制导致凋亡性细胞死亡的信号传导途径将防止神经元死亡，并为感染各种临床相关病毒后病毒诱导的脑和脊髓疾病提供新的靶点。新生小鼠的呼肠孤病毒感染为理解脑和脊髓内的病毒发病机制提供了良好表征的模型系统。我们已经发现，外源性和内源性凋亡途径和JNK信号在呼肠孤病毒感染后的大脑中被激活，并有助于呼肠孤病毒诱导的神经元凋亡。我们建议确定这些途径是否也被激活：（i）在我们最近开发的呼肠孤病毒诱导的肌萎缩模型中：（ii） 在感染西尼罗河病毒（WNV）和单纯疱疹病毒（HSV）的小鼠脑中：（iii）病毒（呼肠孤病毒、WNV、HSV）感染后的离体脑切片培养物和（iv）来自病毒诱导的CNS疾病患者的人体组织中，并表征它们在病毒发病机制中的作用。 CNS的病毒感染导致先天免疫应答的激活，包括干扰素（IFN）的上调和IFN刺激基因（ISG）的表达增加。ISG影响细胞凋亡，尽管其发生的机制以及这些基因在病毒发病机制中的作用仍然未知。在具体目标2中，我们将研究具有假定凋亡功能的特异性ISG在病毒（呼肠孤病毒、WNV、HSV）诱导的小鼠脑和脊髓内发病机制中的作用，病毒感染离体脑切片培养物和病毒诱导的CNS疾病患者的组织后。 神经胶质增生（小胶质细胞和星形胶质细胞的活化）是神经炎症的标志。胶质增生已被证明在体外和体内感染日本脑炎病毒（JEV）和与胶质增生相关的炎症介质已在病毒性脑炎期间的脑中检测到。然而，神经胶质增生在急性病毒诱导的CNS疾病中的作用仍不完全清楚，特别是在脊髓内。虽然胶质增生可能通过促进感染细胞的清除而在抑制病毒复制中起作用，但已经提出这种保护性的胶质增生可能是通过抑制病毒复制来实现的。 从激活的神经胶质细胞释放的几种因子可能掩盖了这种作用，这些因子诱导神经变性和对旁观者细胞的严重损伤。在具体目标3中，我们假设神经胶质增生有助于CNS病毒感染后的发病机制。我们将通过研究病毒（呼肠孤病毒，WNV，HSV）诱导的小鼠脑和脊髓内的发病机制，病毒感染后的离体脑切片培养物和病毒诱导的CNS疾病患者的组织中的神经胶质增生的作用来测试这一假设。

DESCRIPTION (provided by applicant): Viruses induce disease in the central nervous system (CNS) by either killing or disrupting essential functions of neurons within the brain and spinal cord. We propose to use well characterized models of virus-induced CNS disease to investigate the mechanisms by which viruses cause neuronal cell death and injury to the brain and spinal cord. We will delineate the specific cell signaling pathways involved in virus-induced death and tissue injury within the CNS and evaluate these signaling pathways as therapeutic targets for virus-induced CNS disease. Our experiments are expected to lead to the identification of novel therapeutic targets for virus- induced CNS disease. Apoptosis is an established mechanism of virus-induced cell death during viral encephalitis and occurs in the brain following experimental infection with a wide variety of viruses. Apoptosis is also emerging as a mechanism of motor neuron cell death in virus-induced myelitis in humans. Inhibition of caspase 3, the executioner caspase of apoptotic cell death, results in decreased severity of virus-induced encephalitis. In specific aim 1 we will test the hypothesis that inhibition of the signaling pathways that lead to apoptotic cell death wil prevent neuronal death and provide novel targets for virus induced brain and spinal cord disease following infection with a variety of clinically relevant viruses. Reovirus infection of neonatal mice provides a well characterized model system for understanding viral pathogenesis within both the brain and spinal cord. We have already identified that the extrinsic and intrinsic apoptotic pathways and JNK signaling are activated in the brain following reovirus infection and contribute to reovirus-induced neuronal apoptosis. We propose to identify whether these pathways are also activated: (i) in our recently developed model of reovirus-induced myelitis: (ii) in the brains of mice infected with West Nile Virus (WNV) and herpes simplex virus (HSV): (iii) following virus (reovirus, WNV, HSV) infection of ex vivo brain slice cultures and: (iv) in human tissue from patients with virus-induced CNS disease, and to characterize their role in viral pathogenesis. Virus infection of the CNS results in activation of innate immune responses, including the up-regulation of interferon (IFN) and increased expression of IFN stimulated genes (ISG). ISG influence apoptosis, although the mechanism by which this occurs and the role of these genes in viral pathogenesis remains unknown. In specific aim 2 we will investigate the role of specific ISG, with putative apoptotic functions, in virus (reovirus, WNV, HSV)-induced pathogenesis within the mouse brain and spinal cord, following viral infection of ex vivo brain slice cultures and in tissue from patients with virus-induced CNS disease. Gliosis (activation of microglia and astrocytes) is a hallmark of neuroinflammation. Gliosis has been demonstrated in vitro and in vivo following infection with Japanese encephalitis virus (JEV) and inflammatory mediators associated with gliosis have been detected in the brain during viral encephalitis. However, the role of gliosis in acute virus-induced CNS disease remains incompletely understood, particularly within the spinal cord. Although gliosis may play a role in inhibiting virl replication by facilitating the removal of infected cells it has been proposed that this protective role may be overshadowed by the release of several factors from activated glia that induce neurodegeneration and severe injury to bystander cells. In specific aim 3 we hypothesize that gliosis contributes to pathogenesis following viral infections of the CNS. We will test this hypothesis by investigating the role gliosis in virus (reovirus, WNV, HSV)-induced pathogenesis within the mouse brain and spinal cord, following viral infection of ex vivo brain slice cultures and in tissue from patients with virus-induced CNS disease.