Neuroinflammation in Cholesterol-Induced AD Pathogenesis

描述（由申请人提供）：阿尔茨海默病（AD）是一种进行性神经退行性疾病，是老年人中最常见的痴呆形式。病理学的特征在于淀粉样前体蛋白（APR）的产物淀粉样β（Abeta）的积累。淀粉样蛋白级联假说提出，Abeta寡聚体通过激活小胶质细胞及其产生神经毒性分子直接和间接引起神经元损伤。最近的研究结果（遗传，实验和流行病学）表明胆固醇代谢异常和AD的发病机制之间的联系。该项目测试了以下假设：胆固醇稳态的失败促进了与Abeta生成增加相关的神经炎症反应的加剧，这反过来又导致了AD的神经变性特征。研究将使用：用途：高脂肪/胆固醇饮食喂养的高胆固醇血症、低密度脂蛋白受体敲除（LDLR-/-）小鼠、表达野生型人APR（类似于散发性AD）的小鼠品系以及两者之间的杂交。该项目的具体目标如下： 通过免疫组织化学检测活化的小胶质细胞和脑血管细胞与淀粉样蛋白水平和突触毒性（即，突触素免疫反应性丧失）。炎症介质（即，细胞因子、促氧化酶），Abeta肽，和参与胆固醇稳态的蛋白质（即，ApoE，ABCA 1）将通过生物化学和免疫化学技术进行定量。 使用细胞培养模型确定与受损脑胆固醇代谢相关的促炎和抗炎刺激的性质和作用。神经胶质和神经胶质-神经元共培养物的培养物将用于研究氧化脂蛋白和ApoE同种型（在存在或不存在Abeta的情况下）对神经胶质炎症反应的影响（即，介质的产生）和对神经元APR加工的影响。此外，核受体的氧固醇配体，即，将检查肝脏X受体（LXR）并探讨其机制。 通过检查神经病理学（即，A β肽水平和突触毒性）和行为变化（8臂水迷宫性能），同时减轻高胆固醇血症小鼠的神经炎症。这些研究的结果应该对开发新的有效的AD抗炎治疗方法有意义。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD), a progressive neurodegenerative condition, is the most prevalent form of dementia in the elderly. The pathology is characterized by an accumulation of amyloid beta (Abeta), the product of amyloid precursor protein (APR). The amyloid cascade hypothesis proposes that Abeta oligomers cause neuronal injury both directly and indirectly via an activation of microglia and their production of neurotoxic molecules. Recent findings (genetic, experimental, and epidemiological) suggest a link between abnormal cholesterol metabolism and the pathogenesis of AD. The project tests the hypothesis that failure of cholesterol homeostasis facilitates an exacerbated neuroinflammatory response in association with increased Abeta generation that, in turn, leads to neurodegeneration characteristic of AD. The studies will use: high fat/cholesterol diet fed hypercholesterolemic, low density lipoprotein receptor knockout (LDLR-/-) mice, a mouse strain expressing the wild type human APR (akin to sporadic AD), as well as the cross between the two. The specific objectives of the project are as follows: Determine neuroinflammatory changes in brain regions of high cholesterol-fed LDLR-/-, wtAPP and wtAPP/LDLR-/- mice by immunohistochemical detection of activated microglia and cerebrovascular cells in relation to amyloid levels and synaptotoxicity (i.e., loss of synaptophysin-immunoreactivity). Inflammatory mediators (i.e., cytokines, pro-oxidant enzymes), Abeta peptides, and proteins involved in cholesterol homeostasis (i.e., ApoE, ABCA1) will be quantified by biochemical and immunochemical techniques. Determine the nature and role of pro- and anti-inflammatory stimuli relevant to impaired brain cholesterol metabolism using cell culture models. Cultures of glia and glial-neuronal co-cultures will be used to investigate the effects of oxidized lipoproteins and ApoE isoforms (in the presence or absence of Abeta) on glial inflammatory response (i.e., production of mediators) and on neuronal APR processing. Also, the anti- inflammatory and anti-amyloidogenic effects of oxysterol ligands of a nuclear receptor, i.e., Liver X Receptor (LXR) will be examined and the mechanisms explored. Test the therapeutic potential of a synthetic LXR ligand (T0901317) with both cholesterol lowering and anti-inflammatory properties, and minocycline, a tetracycline derivative known to suppress microglial activation, by examining neuropathological (i.e., Abeta peptide levels and synaptotoxicity) and behavioral changes (8- arm water maze performance) in parallel to attenuated neuroinflammation in hypercholesterolemic mice. The outcome of these studies should have implications for developing novel and effective anti- inflammatory treatments for AD.