Role of inflammasomes in Alzheimer's Disease

项目摘要/摘要 神经炎症是阿尔茨海默病(AD)的重要组成部分。然而，分子 炎症调节AD进展的机制尚未确定。我们发现β-淀粉样蛋白 1-42激活NLRP3炎症体，AD患者一致有激活的证据 他们大脑中的炎症体。为了测试NLRP3炎症体在AD中的作用，我们培育了APP/PS1小鼠(AN 以淀粉样蛋白为基础的小鼠AD模型)转化为NLRP3、ASC或caspase-1 KOS(这三种蛋白组成 NLRP3炎症小体)，并观察到这些小鼠完全免受许多AD特征的影响 包括学习/记忆缺陷和长时程增强异常。 NLRP3炎性小体调节IL-1β和IL-18这两种高度致炎细胞因子的表达 在小胶质细胞中大量产生；此外，星形胶质细胞强烈表达前IL-18。IL-1β是 淀粉样斑块周边有大量的小胶质细胞，可引起发烧，这是一种强烈的急性期 反应、败血症综合征和嗜热性细胞死亡。IL-18是IL-1超家族的成员之一。与IL不同的是- 1β，IL-18不激活核因子-kappaB，也不具有致热活性。目前尚不清楚是IL-1β还是IL-18 在炎症体缺陷的APP/PS1小鼠中，减少是保护性表型的原因。我们 产生了IL-18KO/APP/PS1小鼠，令人惊讶的是，这些小鼠发展出了致命性癫痫障碍，这 经左乙拉西坦治疗后完全逆转。正如流行病学研究表明的那样，这是高度相关的 几乎三分之二的AD患者在他们的疾病过程中的某个时候会癫痫发作。 在目标1中，我们将研究炎性小体依赖性下垂在小胶质细胞中的作用。 应用特异性缺失炎症体的转基因小鼠研究AD的发病机制 APP/PS1背景下的小胶质细胞。我们还将测试Gasdermin D(A)缺陷的APP/PS1小鼠 Caspase-1底物和上睑下垂的最终效应分子)。在目标2中，我们将检查IL-18是否 抵消IL-1β在AD相关癫痫发作中的致痫作用。我们将使用遗传方法 (在其他AD小鼠模型中删除IL-18)以及药理学方法(IL-1β功能丧失 方法)对IL-18KO/APP/PS1小鼠进行癫痫发作评估。在目标3中，我们将确定 IL-18在降低神经元网络活动和调节突触传递中的作用。我们将确定以下类型 通过对IL-18KO/APP/PS1小鼠进行形态和超微结构研究 电生理检查以及免疫组织化学生化分析。我们将具体地 使用IL-18转基因小鼠品系检测小胶质细胞IL-18的作用。成功完成这些任务 AIMS将阐明炎症体产生的细胞因子在AD中的作用，并可能导致新的翻译 旨在特别阻止导致AD的炎症的方法，以及机械靶向 影响AD患者生活质量的癫痫发作。

PROJECT SUMMARY/ABSTRACT Neuroinflammation is an important component of Alzheimer's disease (AD). However, the molecular mechanism by which inflammation modulates AD progression is not defined. We discovered that beta-amyloid 1-42 activates NLRP3 inflammasomes and that AD patients uniformly have evidence of activated inflammasomes in their brains. To test the role of NLRP3 inflammasomes in AD, we bred APP/PS1 mice (an amyloid-based murine model of AD) into NLRP3, ASC, or caspase-1 KOs (the three proteins comprising the NLRP3 inflammasome) and observed that these mice were completely protected from numerous AD features including learning/memory deficits and abnormalities in long-term potentiation. NLRP3 inflammasomes regulate the expression of IL-1beta and IL-18, two highly proinflammatory cytokines abundantly produced in microglial cells; in addition, astrocytes are strong expresses of pro-IL-18. IL-1beta is abundant in microglial cells on the periphery of amyloid plaques and can cause fever, a strong acute phase response, sepsis syndrome, and pyroptotic cell death. IL-18 is a member of the IL1 superfamily. Unlike IL- 1beta, IL-18 does not activate NF-kappaB or have pyrogenic activity. It is unknown if IL-1beta or IL-18 reduction was responsible for the protective phenotype in inflammasome-deficient APP/PS1 mice. We generated IL-18KO/APP/PS1 mice and, surprisingly, these mice developed a lethal seizure disorder, which was completely reversed by levetiracetam therapy. This is highly relevant as epidemiologic studies suggest that almost two-thirds of AD patients have seizures at some point during the course of their disease. In Aim 1, we will examine the role of inflammasome-dependent pyroptosis in microglial cells in the pathogenesis of AD using transgenic mice in which the inflammasome has been specifically deleted from microglial cells on an APP/PS1 background. We will also test APP/PS1 mice deficient for Gasdermin D (a caspase-1 substrate and the final effector molecule of pyroptosis). In Aim 2, we will examine if IL-18 counterbalances the proepileptic effects of IL-1beta in AD-related seizures. We will use a genetic approach (deleting IL-18 in other AD mouse models) as well as a pharmacological approach (an IL-1beta loss-of-function approach) in IL-18KO/APP/PS1 mice and assess animals for seizures. In Aim 3, we will determine the role of IL-18 in reducing neuronal network activity and modulating synaptic transmission. We will identify the types of synapses that are dysregulated in IL-18KO/APP/PS1 mice by performing morphological and electrophysiological studies as well as biochemical analysis using immunohistochemistry. We will specifically examine the role of microglial IL-18 using a floxed IL-18 transgenic mouse line. Successful completion of these Aims will elucidate the role of inflammasome-generated cytokines in AD, and could result in novel translational approaches designed to specifically halt the inflammation that drives AD, as well as mechanistically target seizures that affect the quality of life of AD patients.