A role for the complement system in seizure induced neuronal and dendritic injury

项目摘要 癫痫是一种癫痫发作疾病，通常伴有认知障碍。长时间持续性癫痫发作 （癫痫持续状态; SE）通过重塑增加颞叶癫痫（TLE）发展的风险 在脆弱的神经元网络，如海马的突触连接。大量证据 支持SE诱导的海马突触树突重塑通过谷氨酸 兴奋性毒性、凋亡和来自许多细胞内信号级联的异常激活与 经常导致癫痫发作的神经元过度兴奋。尽管有这些发现， 直接影响神经过度兴奋性仍然难以捉摸。SE的组织病理学的一个突出标志， 癫痫是介导神经炎症和吞噬反应的小胶质细胞的激活。公 已知小胶质细胞介导的神经炎症机制有助于癫痫发作;然而， 它们的吞噬反应的潜在作用。在SE期间和之后，小胶质细胞使多个物理 与皮质和海马树突接触，这是我们最近在人类难治性 癫痫这些接触可能导致树突状结构的吞噬作用，从而修饰细胞。 神经元连接最近的研究发现，免疫补体C1 q和C3蛋白 系统发送“吃我”信号，引导小胶质细胞吞噬正常细胞中的神经元突触。 大脑发育此外，C1 q和C3与海马的病理性切除有关 神经退行性疾病模型中的突触结构。我们和其他人发现C1 q-C3的增加 难治性人类癫痫和实验模型SE后的mRNA和蛋白水平所以我们 假设脑出血诱导的免疫补体系统激活有助于海马 突触树突修饰，促进神经元/网络过度兴奋，癫痫发作和记忆缺陷。 我们将追求以下目标，目标1： SE和TLE的小鼠模型;目的2：确定SE诱导的C3激活对神经元的作用。 和突触树突状细胞的变化在海马TLE的小鼠模型;目的3：为了确定 SE诱导的C3激活对小鼠癫痫发作和海马依赖性记忆缺陷的作用 TLE模型这项研究将提供一个强有力的框架，了解吞噬作用的先天性 免疫补体系统和小胶质细胞在SE诱导的癫痫回路的产生。我们的科学 这些发现很可能为直接调节肿瘤细胞的潜在治疗价值提供证据。 补体级联减少癫痫发作和认知共病。重要的是，因为FDA- 批准的补体抑制剂目前被用于人类免疫性疾病，我们的研究 这可能为快速追踪这些药物用于癫痫的再利用提供证据。 1

Project Summary Epilepsy is a seizure disorder that is often comorbid with cognitive disabilities. Prolonged-continuous seizures (status epilepticus; SE) increase the risk for the development of temporal lobe epilepsy (TLE) by remodeling synaptic connectivity in vulnerable neuronal networks such as those of the hippocampus. Extensive evidence supports that SE-induced hippocampal synaptodendritic remodeling orchestrated through glutamate excitotoxicity, apoptosis, and aberrant activation from a number of intracellular signaling cascades is linked to the neuronal hyperexcitability that often results in seizures. Despite these findings, the mechanisms that directly impact neural hyperexcitability remain elusive. A prominent hallmark in the histopathology of SE and epilepsy is activation of microglia, which mediate neuroinflammatory and phagocytic responses. It is well known that microglia-mediated neuroinflammatory mechanisms contribute to seizures; however, a gap remains on the potential role of their phagocytic responses. During and after SE microglia make multiple physical contacts with cortical and hippocampal dendrites, a phenomenon that we recently found in human refractory epilepsy. These contacts may result in the phagocytosis of dendritic structures and thereby modification of neuronal connectivity. Recent studies discovered that C1q and C3 proteins from the immune complement system send “eat-me” signals that guide microglia to phagocytose extranumerary synapses in the normal developing brain. In addition, C1q and C3 are associated with the pathological removal of hippocampal synaptic structures in models of neurodegenerative disorders. We and others found increases in C1q-C3 mRNA and protein levels in intractable human epilepsy and after SE in experimental models. Therefore, we hypothesized that seizure-induced activation of the immune complement system contributes to hippocampal synaptodendritic modifications that promote neuronal/network hyperexcitability, seizures, and memory deficits. We will pursue the following Aims, Aim1: To characterize complement activation and associated responses in a mouse model of SE and TLE; Aim2: To determine the contribution of SE-induced C3 activation to neuronal and synaptodendritic changes in the hippocampus in a mouse model of TLE; Aim3: To determine the contribution of SE-induced C3 activation to seizures and hippocampal-dependent memory deficits in a mouse model of TLE. This study will provide a strong framework for understanding the phagocytic role of the innate immune complement system and microglia in the SE-induced generation of epileptic circuits. Our scientific discoveries are likely to provide evidence for the potential therapeutic value of directly modulating the complement cascade to attenuate seizures and cognitive comorbidities in epilepsy. Importantly, because FDA- approved complement inhibitors are currently being used for immunological illnesses in humans, our study may provide evidence to fast track the repurposing of these drugs for their use in epilepsy. 1