COMPLEMENT MECHANISMS IN AMYLOID BETA PEPTIDE CLEARANCE

描述（由申请人提供）：炎症是破坏力和重建力的混合物，其平衡决定了生物体的整体效用或损失。通过了解哪些炎症机制在阿尔茨海默病（AD）中是有用的，哪些是有害的，我们可以找到更好的治疗这种疾病的方法。我们以前在目前的RO1下进行的AD炎症研究强调了毒性机制。在这里，我们专注于AD炎症的潜在有益机制，淀粉样β肽（Abeta）的补体调理作用，以及它如何在CNS和外周加工Abeta中发挥关键作用。具体目标1将使用AD小胶质细胞培养物研究脑Abeta清除中的补体机制，并使用hAPP过表达转基因小鼠与C3敲除小鼠杂交以评价这些机制在体内的作用。我们将证明，补体调理素和过敏毒素有助于驱动小胶质细胞的趋化性和吞噬的Abeta，并在他们的情况下，大脑积累的Abeta增加。由于补体调理作用是抗体介导的抗原清除的正常特征，因此研究还将研究补体与Abeta免疫的相互作用。具体目标2将结果扩展到外周Abeta清除。最近的研究表明，存在Abeta的外周池，并且不实质性地穿透脑的抗Abeta抗体隔离或去除循环Abeta，导致脑Abeta沉积减少。关键的问题是，Abeta会发生什么？补体清除循环免疫复合物的机制是众所周知的，我们希望证明它们在外周Abeta清除的背景下是有效的。过表达hAPP的小鼠与C3基因敲除小鼠的杂交应显示出外周以及CNS在Abeta去除方面的缺陷。在我们的小鼠模型中，由于补体机制缺陷引起的Abeta积累可能会导致神经变性增强。或者，补体溶解机制的抑制可能是神经保护性的。我们将比较外周补体和Abeta指标与神经退行性变指标，以评估总的来说，补体机制在AD中最终是否更有帮助而不是有害。这些研究还将检查补体缺乏与Abeta免疫的相互作用，这可能导致可能与当前临床试验相关的免疫复合物沉积问题。

DESCRIPTION (provided by applicant): Inflammation is a mixture of destructive and rebuilding forces, the balance of which dictates the overall utility or loss to the organism. By understanding which inflammatory mechanisms are useful in Alzheimer's disease (AD) and which are detrimental, we may arrive at better ways of treating the disorder. Our previous AD inflammation research under the present RO1 has emphasized toxicity mechanisms. Here, we focus on a potentially beneficial mechanism of AD inflammation, complement opsonization of amyloid beta peptide (Abeta), and how it may play a critical role in both CNS and peripheral processing of Abeta. Specific Aim 1 will use cultures of AD microglia to investigate complement mechanisms in the clearance of brain Abeta, and hAPP overexpressing transgenic mice crossed with C3-knockout mice to evaluate the operation of those mechanisms in vivo. We will show that complement opsonins and anaphylatoxins help drive microglial chemotaxis to and phagocytosis of Abeta, and that, in their absence, brain accumulation of Abeta increases. Since complement opsonization is a normal feature of antibody-mediated clearance of antigens, the studies will also investigate complement interactions with Abeta immunization. Specific Aim 2 will extend the findings to peripheral Abeta clearance. Recent studies have shown that peripheral pools of Abeta exist, and that an anti-Abeta antibody that does not materially penetrate the brain sequesters or removes circulating Abeta, resulting in decreased brain Abeta deposition. The critical question then becomes, what happens to the Abeta? Complement mechanisms in clearance of circulating immune complexes are well known, and we expect to demonstrate that they are operative in the context of peripheral Abeta clearance. Crosses of hAPP-overexpressing with C3- knockout mice should show peripheral as well as CNS deficits in Abeta removal. Abeta accumulation due to deficient complement mechanisms could engender enhanced neurodegeneration in our mouse model. Alternatively, the inhibition of complement lytic mechanisms could be neuroprotective. We will compare peripheral complement and Abeta measures with measures of neurodegeneration to evaluate whether, on balance, complement mechanisms are ultimately more helpful than harmful in AD. The studies will also examine interactions of complement deficiency with Abeta immunization, which could cause immune complex deposition problems that may be relevant to current clinical trials.