The Microglial Kv1.3 Channel in Alzheimer's Disease

描述（由申请人提供）：阿尔茨海默病（AD）在全球范围内折磨着大约2500万人，是老年人痴呆症的最常见原因。迫切需要新的治疗靶点的发现和相应的新化合物的开发。沉积在AD大脑中的一种叫做淀粉样蛋白-¿（A¿）的蛋白质被假设在AD的发病机制中起关键作用。Ab可以激活小胶质细胞清除A¿，但同时释放细胞毒性物质，造成神经元损伤。近年来发现电压门控钾通道Kv1.3 （KCNA3）在小胶质细胞活化中起重要作用。因此，我们打算研究Kv1.3是否在AD的小胶质细胞激活、神经毒性和淀粉样蛋白沉积中起作用。体外和原位实验发现，选择性Kv1.3阻滞剂PAP-1可阻断A¿激活的小胶质细胞诱导的神经毒性，但不阻断小胶质细胞吞噬A¿的有益作用。我们还在两种AD小鼠模型中发现与淀粉样斑块相关的小胶质细胞中有很强的Kv1.3免疫反应。我们的研究结果表明Kv1.3参与了阿尔茨海默病的小胶质细胞激活和神经毒性。在这笔拨款的帮助下，我们现在希望获得体内原理证明，Kv1.3可能是一个治疗靶点，其特异性抑制剂可能具有治疗AD的潜力。我们将确定：1；体内促炎刺激下的小胶质细胞激活和相关神经元损伤是否需要小胶质细胞Kv1.3通道活性？为了回答这个问题，我们将确定阻断Kv1.3活性是否会减少脂多糖或Ab低聚物治疗后小鼠的小胶质细胞激活和树突变性。我们还将研究小胶质细胞Kv1.3的活性及其对这些促炎刺激下小胶质细胞激活状态的影响。2. 选择性Kv1.3阻断剂PAP-1能否在体内抑制小胶质细胞激活并改善3xTg-AD小鼠模型的认知功能？为了解决这个问题，我们将进行一项治疗性试验，用PAP-1治疗3xTg-AD小鼠，并确定PAP-1对小胶质细胞激活状态、淀粉样蛋白沉积、tau病理和认知表现的影响。雷：小胶质细胞是大脑中发现的一种白细胞，已被证明与阿尔茨海默病的发病机制有关。我们的提议的目的是测试一种叫做Kv1.3的钾通道在小胶质细胞引起的损伤中是否重要。我们将在阿尔茨海默病动物模型中进一步测试Kv1.3抑制剂是否会降低小胶质细胞活性。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) afflicts approximately 25 million people worldwide and is the most common cause of dementia in the elderly. There is an urgent need for new therapeutic target discovery and corresponding new compound development. A protein deposited in AD brains called amyloid-¿ (A¿) has been hypothesized to play a critical role in AD pathogenesis. Ab can activate microglia to clear A¿ but at the same time releasing cytotoxic substances to cause neuronal damage. Recently it was found that the voltage-gated potassium channel Kv1.3 (KCNA3) plays an important role in microglia activation. Therefore we intend to study if Kv1.3 plays a role in microglia activation, neurotoxicity, and amyloid deposition in AD. We found in our in vitro and in situ experiments that the selective Kv1.3 blocker PAP-1 blocked the neurotoxicity induced by A¿- activated microglia, but did not block the beneficial effect of microglia to phagocytose A¿. We also found strong Kv1.3 immunoreactivities in microglia associated with amyloid plaques in two AD mouse models. Our results suggest the involvement of Kv1.3 in microglia activation and neurotoxicity in AD. With the help of this grant we now wish to obtain in vivo proof of principle that Kv1.3 could be a therapeutic target and its specific inhibitors may have a therapeutic potential for AD. We will determine: 1. Do microglia activation and associated neuronal damage in response to pro-inflammatory stimuli in vivo require microglial Kv1.3 channel activity? To answer this question we will determine if blockade of Kv1.3 activity reduces microglial activation and dendritic degeneration in mice after treatment with lipopolysscharides or Ab oligomers. We will also examine the microglial Kv1.3 activity and its influence on the microglial activation state in response to these pro-inflammatory stimuli. 2. Can a selective Kv1.3 blocker called PAP-1 inhibit microglia activation in vivo and improve cognitive function of an AD mouse model called 3xTg-AD mice? To address this question, we will perform a therapeutic trial by treating 3xTg-AD mice with PAP-1 and determine the effect of PAP-1 on microglia activation state, amyloid deposition, tau pathology, and cognitive performance. Lay: Microglia, a type of white blood cells found in the brain, have been shown to contribute to the pathogenesis of Alzheimer's disease. The aims of our proposal are to test whether a potassium channel called Kv1.3 is important in microglia-caused damage. We will further test whether an inhibitor for Kv1.3 reduces microglia activity in an animal model of Alzheimer's disease.