Mechanisms of neuronal injury during virus infection of the CNS

食源性和水源性微小核糖核酸病毒，如肠道病毒71型，是一个全球健康问题。神经学 与神经致死性非脊髓灰质炎小核糖核酸病毒感染相关的并发症是一个严重的持续健康问题 问题，特别是在儿童中。不幸的是，小核糖核酸病毒对中枢神经系统的损伤机制 神经系统(CNS)尚不清楚。我们认为先天免疫反应是导致 急性感染期间神经元死亡。这与普遍的假设相反，即神经元丢失是 完全由病毒介导的。虽然我们不怀疑一些神经元直接死于病毒感染， 我们的初步发现表明，某些群体，如海马区的CA1锥体神经元， 被先天免疫反应杀死，而不是被病毒杀死。我们已经建立了一个小鼠模型。 利用微小核糖核酸病毒感染中枢神经系统直接检测泰勒氏小鼠脑脊髓炎病毒的作用 中性粒细胞在启动神经细胞凋亡中的作用。我们的初步证据表明，在急性发作期间 微小核糖核酸病毒感染中枢神经系统，许多未感染的CA1区锥体神经元经历与凋亡相关的死亡 与氧化损伤、钙蛋白酶活性和半胱氨酸酶活性有关；这种损伤严重降低了大鼠的认知能力 一项空间记忆测试。我们进一步观察到，中性粒细胞在数小时内渗入海马体。 感染。减少中性粒细胞的渗透是神经保护的，而过继将激活的中性粒细胞转移到 中性粒细胞反应缺陷的小鼠会导致海马区损伤。最后，使用钙蛋白酶抑制剂进行治疗 保护海马神经元免于死亡并保留认知功能而不限制 调节宿主防御和病毒清除所必需的炎症反应。在此基础上 观察我们假设中性粒细胞通过钙蛋白依赖的机制杀死海马神经元 在中枢神经系统急性小核糖核酸病毒感染期间。我们打算解决以下实验性问题：1) 中性粒细胞是杀死海马神经元的必要条件和充分条件吗？ 中性粒细胞对急性中枢神经系统感染的反应导致海马神经元死亡？我们建议 几项创新，包括使用活体动物成像和中性粒细胞收养转移，以解决 这些问题。我们建议的关键概念是，虽然炎症在宿主防御中起关键作用 病毒感染后，炎症反应可能会间接杀死神经元，从而进行治疗干预 旨在防止神经元死亡而不挫败炎症的病毒控制可能会保护宿主的功能。

Foodborne and waterborne picornaviruses such as enterovirus 71 are a global health issue. Neurologic complications associated with neurovirulent non-polio picornavirus infection are a serious ongoing health problem, especially in children. Unfortunately, the mechanisms of picornavirus-induced injury to the central nervous system (CNS) are unclear. We propose that the innate immune response is an important cause of neuron death during acute infection. This is in contrast to the prevailing hypothesis that neuron loss is mediated solely by virus. While we do not doubt that some neurons die directly as the result of viral infection, our preliminary findings suggest that certain populations, such as CA1 pyramidal neurons in the hippocampus, are killed by the innate immune response rather than by the virus. We have established a mouse model of picornavirus infection of the CNS using the Theiler's murine encephalomyelitis virus to directly test the role of neutrophils in the initiation of neuronal apoptosis. Our preliminary evidence indicates that during acute picornaviral infection of the CNS, many uninfected CA1 pyramidal neurons undergo apoptotic death associated with oxidative injury, calpain activity, and caspase activity; this injury severely reduces cognitive performance in a spatial memory test. We have further observed that neutrophils infiltrate the hippocampus within hours of infection. Reduced neutrophil infiltration is neuroprotective, while adoptive transfer of activated neutrophils into mice with a defective neutrophil response induces hippocampal injury. Finally, treatment with calpain inhibitors protects hippocampal neurons from death and preserves cognitive function without constraining the inflammatory response that is necessary to mediating host defense and viral clearance. On the basis of these observations we hypothesize that neutrophils kill hippocampal neurons via a calpain-dependent mechanism during acute picornaviral infections of the CNS. We intend to address the following experimental questions: 1) are neutrophils necessary and sufficient to kill hippocampal neurons?; 2) is calpain the key executioner of hippocampal neurons during death induced by the neutrophil response to acute CNS infection? We propose several innovations, including the use of live animal imaging and adoptive transfer of neutrophils, to address these questions. The key concept of our proposal is that while inflammation critically mediates host defense to virus infection, the inflammatory response may indirectly kill neurons, and therefore therapeutic interventions aimed at preventing neuronal death without thwarting inflammatory control of virus may preserve host function.