MyD88靶控IL-1R1/TLR4通路在脑炎后癫痫模型中对癫痫发作的影响

There is no breakthrough in the treatment of epilepsy. It is of great significance to research the pathogenesis of epilepsy from the etiologic perspective to improve epilepsy control rate. Inflammatory mediators IL-1β and HMGB1 had proconvulsive effects in chemical-induced seizure model via its receptor IL-1R1 and TLR4, respectively. MyD88 is an essential adaptor molecule in the IL-1R1/TLR4 signaling.Our preliminary research revealed that MyD88 was up-regulated in the brain of epileptic rats, and inhibition of MyD88 function had anti-seizure effects. However, the underlying mechanism remains unclear. Based on those finding, by establishing Theiler’s mouse encephalomyelitis virus induced post-encephalitic seizure model,the present study would firstly determine the inflammatory state of the epileptic brain and MyD88 expression level as well as other molecules, then detect the effect of MyD88 inhibition on IL-1R1/TLR4 mediated proconvulsive pathway using Plexon in vivo recording system, and finally explore whether Src kinase mediated NR2B phosphorylation is the underlying mechanism through patch clamp. We hypothesis that intervention of MyD88 could reduce neuronal hyperexcitability, and attenuate the proconvulsant effects exerted by IL-1β and HMGB1, thereby blocking the vicious cycle of IL-1R1/TLR4 mediated inflammatory pathway on neural network hyperexcitability. This study put emphasis on exploring in etiologically relevant post-encephalitic seizure model, and make preliminary research for investigating epileptogenesis.

癫痫的治疗未取得突破性进展，从病因学角度研究其致病机制对提高癫痫控制率有重大意义。在化学诱导的癫痫模型中炎症介质IL-1β和HMGB1通过IL-1R1和TLR4发挥促惊厥作用，MyD88是IL-1R1/TLR4通路中关键接头分子。我们前期发现MyD88在癫痫鼠脑组织表达升高，抑制MyD88功能可抗癫痫发作，但机制不明。在此基础上，本项目立足于泰勒鼠脑脊髓炎病毒诱导的脑炎后癫痫模型，测定脑内炎症状态及MyD88等分子表达水平，采用Plexon系统在体记录干预MyD88对IL-1R1/TLR4促惊厥通路的影响，采用膜片钳技术探讨Src调节NR2B磷酸化是否为其机制。本研究将证实：干预MyD88降低神经元兴奋性，抑制IL-1β和HMGB1诱导的促惊厥作用，阻断IL-1R1/TLR4炎症通路对神经网络兴奋性影响的恶性循环。本研究强调在病因相关的脑炎后癫痫模型中进行探索，并为研究癫痫形成做准备。

癫痫的治疗未取得突破性进展，研究其致病机制对提高癫痫控制率有重大意义。在化学诱导的癫痫模型中炎症介质IL-1β和HMGB1通过IL-1R1和TLR4发挥促惊厥作用，MyD88是IL-1R1/TLR4通路中关键接头分子。本研究发现MyD88在癫痫鼠脑组织表达升高，抑制MyD88功能可抗癫痫发作。为探讨MyD88及下游信号分子HMGB1和IL-1β在癫痫发病机制中的作用，本研究从表达、功能、机制三个层次对此问题进行分析，从实验动物到临床两个方面进行验证。本研究主要结论：(1) MyD88在癫痫鼠脑组织表达升高，抑制MyD88功能可抗癫痫发作。（2）MyD88的小分子抑制剂ST2825在急性匹罗卡品模型中可减少行为学上及脑电图上的癫痫发作，减轻小胶质细胞的活化；ST2825在急性戊四氮模型中也能减少癫痫发作。（3）MyD88的上游信号分子IL-1β和HMGB1在急性皮罗卡品和急性PTZ模型中均具有促惊厥作用，ST2825能抑制IL-1β和HMGB1的促惊厥作用。（4）NR2B亚基的选择性抑制剂艾芬地尔可抑制癫痫发作活动，并可抑制IL-1β和HMGB1的促惊厥作用，NR2B Tyr1472可能是其作用的靶点。（5）HMGB1在药物难治性癫痫及症状学癫痫病因患者CSF中表达升高，脑脊液中的HMGB1在预测癫痫病因和预后方面具有一定的价值。本项研究（1）探索IL-1R1/TLR4-MyD88信号通路在癫痫发生发展中的作用，为深入理解癫痫的发病机制和新药研发提供理论基础；（2）发现HMGB1可作为药物难治性癫痫患者的生物标志物，为药物难治性患者的早期诊断和积极治疗提供临床依据。