Dissecting the role of gut microbial-derived metabolites on epilepsy

项目摘要 癫痫是一种常见的神经系统疾病，全球发病率超过6500万。有一般的 一致认为癫痫是由过度兴奋的神经元网络引起的，大多数治疗策略都有 专注于通过靶向神经元突触蛋白来减少兴奋。即使有可用的抗癫痫药物 药物治疗仍然没有治愈的方法，30%的患者对治疗有抵抗力。历史上，癫痫一直被认为是 然而，这种以大脑为中心的观点忽略了这样一个事实，即 神经系统的功能受身体新陈代谢状态的影响。目前的研究认识到 微生物通过改变肠道中的代谢因素来影响大脑，肠道是“肠道-脑轴”。大多数 到目前为止，证据是相关的，表明肠道微生物区系的变化可以影响癫痫的结果。 然而，关于肠道微生物导致癫痫发作的具体机制，人们的认识还存在差距。 可能提供治疗癫痫的新方法的发展。病毒感染引起的癫痫是最常见的 这是世界范围内癫痫的常见原因，由于死亡率高，在啮齿动物身上往往很难建立模型。 然而，泰勒氏小鼠脑脊髓炎病毒(TMEV)是一种低死亡率的由病毒诱导的临床型 脑叶癫痫。颅内注射TMEV导致海马神经元功能障碍，广泛皮质 约50%的成年C57BL/6小鼠在感染后6天出现星形胶质细胞增生症和癫痫发作高峰。而在中央 神经系统炎症被认为是癫痫表型发展的潜在调节因素 TMEV感染的分子机制尚不清楚。从这个模型获得的数据令人惊讶地表明 在具有癫痫表型的TMEV感染小鼠中，大多数分类没有得到充分代表，其中包括属 与细菌代谢物S-马酚的产生有关。这些细菌将饮食中的大豆苷元转化为 S-QUOL可激活大电导钙激活钾通道和电压激活钾通道。 BK通道的激活在控制神经元兴奋性方面起着重要作用，因此代表着一种 治疗癫痫的新靶点。这项提议将确定微生物衍生的 代谢物S-马酚可增加三甲氧乙胺注射小鼠癫痫发作的发生率。它进一步检验了S- 产马胆醇微生物物种对癫痫敏感性和神经元的神经保护作用 经激活BK通道注射TMEV后的超兴奋性。这一假设将使用 脑电和电生理记录、质谱学和16S RNA测序相结合。至 确定这些发现是否广泛适用于其他类型的癫痫，我们将检查三种模型 癫痫、TMEV、红藻氨酸和遗传性癫痫模型。这项工作迈出了关键的一步，将 特定的微生物转移到神经元兴奋性、癫痫和癫痫，并将识别微生物代谢物 可以作为治疗干预的靶向。

Project Summary Epilepsy is a common neurological disorder, with a worldwide prevalence of over 65 million. There is general agreement that epilepsy is caused by hyperexcitable neuronal networks and most therapeutic strategies have focused on decreasing excitation by targeting neuronal synaptic proteins. Even with the available antiepileptic drugs, there is still no cure and 30% of patients are resistant to treatment. Historically, epilepsy has been viewed as driven solely by defects in brain processes; however, this brain-centric perspective neglects the fact that the function of the nervous system is affected by the metabolic state of the body. Current research recognizes that microorganisms influence the brain by modifying metabolic factors in the gut, the “gut-brain axis.” Most of the evidence thus far is correlative showing that changes in the gut microbiota can affect seizure outcomes. However, there is a gap in knowledge regarding specific mechanisms by which gut microbes contribute to seizure development that may offer novel approaches to treat epilepsy. Viral infection-induced epilepsy is the most common cause of epilepsy worldwide and is often difficult to model in rodents due to high mortality rates. However, the Theiler's murine encephalomyelitis virus (TMEV) is a low-mortality viral-induced model of temporal lobe epilepsy. Intracranial TMEV injection leads to hippocampal neuronal dysfunction, widespread cortical astrogliosis, and seizure-genesis peaking at 6 days post infection in ~50% of adult C57BL/6 mice. While central nervous system inflammation has been posited as a potential modulator of seizure phenotype development in TMEV infection, the molecular mechanism is unclear. Data obtained from this model surprisingly indicated that the majority of taxonomies underrepresented in TMEV-infected mice with seizure phenotypes contained genera associated with the production of the bacterial metabolite S-equol. These bacteria convert dietary daidzein into S-equol, which has been shown to activate large conductance Ca2+- and voltage-activated K+ (BK) channels. Activation of BK channels play an important role in controlling neuronal excitability and therefore represents a novel target for the treatment of epilepsy. This proposal will determine if depletion of the microbial-derived metabolite, S-equol, increase seizure occurrence in TMEV-injected mice. It further tests the hypothesis that S- equol-producing microbial species confer neuroprotection against seizure susceptibility and neuronal hyperexcitability following TMEV injection via activation of BK channels. This hypothesis will be tested using a combination of EEG and electrophysiology recordings, mass spectrometry and 16S RNA sequencing. To determine whether these findings are broadly applicable to other types of epilepsy we will examine three models of epilepsy, TMEV, kainic acid and a genetic epilepsy model. This work takes a critical step causally linking specific microbial shifts to neuronal excitability, seizures and epilepsy and will identify microbial metabolites that can be targeted for therapeutic intervention.