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大脑和脊髓内神经元的基本功能而导致中枢神经系统(CNS)疾病。我们建议使用具有良好特征的病毒诱导的中枢神经系统疾病的模型来研究病毒导致神经细胞死亡和对脑和脊髓的损伤的机制。我们将描述涉及病毒诱导的中枢神经系统内死亡和组织损伤的特定细胞信号通路，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细胞死亡的一种既定机制，在实验性感染各种病毒后发生在大脑中。在病毒诱导的人类脊髓炎中，细胞凋亡也是运动神经元细胞死亡的一种机制。抑制凋亡细胞死亡的执行者caspase3可降低病毒所致脑炎的严重程度。在特定的目标1中，我们将验证这样的假设，即抑制导致细胞凋亡的信号通路将防止神经元死亡，并为病毒感染各种临床相关病毒后引起的脑和脊髓疾病提供新的靶点。呼肠孤病毒感染新生小鼠为了解病毒在脑和脊髓内的发病机制提供了一个很好的模型系统。我们已经发现，呼肠孤病毒感染后，脑内外在和内在的细胞凋亡通路和JNK信号通路被激活，并参与了呼肠孤病毒诱导的神经细胞凋亡。我们建议确定这些通路是否也被激活：(I)在我们最近开发的呼肠孤病毒诱导的脊髓炎模型中：(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)感染后的体外脑片培养和(Iv)病毒诱导的中枢神经系统疾病患者的人体组织中，并表征它们在病毒致病机制中的作用。病毒感染中枢神经系统导致天然免疫反应的激活，包括干扰素上调和干扰素刺激基因表达增加。ISG影响细胞凋亡，尽管其发生机制以及这些基因在病毒发病机制中的作用尚不清楚。在特定的目标2中，我们将研究特定的ISG在病毒(呼肠孤病毒、西尼罗河病毒、单纯疱疹病毒)在病毒感染体外脑片培养物和病毒诱导的中枢神经系统疾病患者的脑片培养和组织中诱导的小鼠脑和脊髓内的致病中的作用。神经胶质细胞增多症(小胶质细胞和星形胶质细胞的激活)是神经炎症的标志。感染日本脑炎病毒(JEV)后，在体外和体内都发现了胶质细胞增生症，在病毒性脑炎期间，脑组织中检测到了与胶质细胞增多症相关的炎性介质。然而，胶质增生在病毒诱导的急性中枢神经系统疾病中的作用仍不完全清楚，尤其是在脊髓内。尽管胶质细胞增多症可能通过促进受感染细胞的移除而在抑制病毒复制方面发挥作用，但已有研究提出，这种保护作用 这种作用可能被激活的神经胶质细胞释放的几种因素所掩盖，这些因素导致神经退化和对旁观者细胞的严重损伤。在特定的目标3中，我们假设胶质增生在病毒感染中枢神经系统后的发病机制中起作用。我们将通过研究病毒(呼肠孤病毒、西尼罗河病毒、单纯疱疹病毒)在病毒感染体外脑片培养物和病毒诱导的中枢神经系统疾病患者的组织中在小鼠脑和脊髓中诱导的发病机制中的作用来检验这一假说。 公共卫生相关性： 病毒引起的中枢神经系统(CNS)疾病，包括脑(脑炎)和脊髓(脊髓炎)，在世界各地导致显著的发病率和死亡率。这笔赠款提出的实验旨在：(1)确定病毒诱导的大脑和脊髓神经元损伤的机制；(2)评估病毒诱导的中枢神经系统疾病的新治疗策略。病毒杀死中枢神经系统内神经元的机制可能对许多神经退行性疾病和获得性疾病(如肌萎缩侧索硬化症、帕金森氏症、阿尔茨海默氏症、创伤性脑和脊髓损伤)具有关键的致病作用，对退伍军人的健康具有重要意义。这是一项具有翻译成分的基础科学拨款，我们坚信这些内容既与当前重要的公共卫生问题(如西尼罗河病毒)直接相关，也与影响退伍军人的各种神经疾病具有重大的普遍相关性。

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. PUBLIC HEALTH RELEVANCE: Virus-induced diseases of the central nervous system (CNS), including the brain (encephalitis) and spinal cord (myelitis) induce significant morbidity and mortality throughout the world. This grant proposes experiments designed to: (1) identify mechanisms of virus-induced neuronal injury in the brain and spinal cord and: (2) evaluate novel therapeutic strategies for virus-induced CNS disease. The mechanisms by which viruses kill neurons within the CNS, is likely of critical pathogenetic importance to many neurodegenerative and acquired diseases (e.g. ALS, Parkinson's, Alzheimer's, traumatic brain and spinal cord injury) of major importance to veterans' health. This is a basic science grant with translational components that we strongly believe have direct relevance to both important current public health problems (e.g. WNV), and a basic science theme (neuronal cell death and its prevention) that is of significant general relevance to a wide variety of neurological diseases affecting veterans.