Mechanisms of amyloid-beta clearance.

描述（由申请人提供）：过表达APP的转基因小鼠模型以年龄依赖的方式发展老年斑，类似于阿尔茨海默病（AD）患者。最近的证据表明，主动或被动免疫治疗显著防止淀粉样蛋白沉积在转基因小鼠。清除阿尔茨海默病患者体内现有的淀粉样蛋白- β 3沉积物，以及预防新的斑块形成，将是有效治疗的关键。观察治疗前后的老年斑是测量现有沉积物清除的唯一直接方法，但直到最近这还不可能。我们已经开发了新的多光子显微镜技术，可以对单个斑块进行纵向体内成像。使用这种方法，我们证明了转基因小鼠在单次将抗体应用于皮质后3-5天清除现有斑块。在这个应用中，我们建议测试关于清除机制的假设。Aim 1从我们的观察中得出，添加F（ab’）2片段也可以发生清除，这表明fc介导的机制不是必需的。我们提出了一个模型，通过直接的生物物理相互作用，通过主动去除淀粉样蛋白，清除淀粉样蛋白13沉积物的两步过程。目的2询问是否全身免疫，而不是局部应用抗体到皮质，将导致清除；如果是这样，我们将确定必要的滴度和最佳的表位。Aim 3利用了几个实验室的体外实验结果，证明淀粉样蛋白-13结合化合物可以阻止或逆转淀粉样蛋白原纤维的形成。我们将在体内测试它们是否为分解剂。该结果将强烈影响旨在去除老年斑和阿尔茨海默病相关神经损伤的治疗方法的发展。

DESCRIPTION (provided by applicant): Transgenic mouse models over-expressing APP develop senile plaques in an age-dependent fashion similar to those found in patients with Alzheimer's disease (AD). Recent evidence shows that active or passive immunotherapy dramatically pevents amyloid-beta deposition in transgenic mice. Clearance of existing amyloid-beta3 deposits present in Alzheimer's disease patients, in addition to prevention of new plaque formation, will be critical for an effective treatment. Observing senile plaques before and after treatment is the only direct way to measure clearance of existing deposits, but until recently this has not been possible. We have developed novel multiphoton microscopy techniques that allow longitudinal in vivo imaging of individual plaques. Using this approach, we demonstrated clearance of existing plaques in transgenic mice 3-5 days after a single application of antibodies to the cortex. In this application, we propose to test hypotheses about the mechanism of clearance. Aim 1 follows from our observation that clearance can also occur with addition of F(ab')2 fragments, suggesting that Fc-mediated mechanisms are not necessary. We propose a model whereby clearance results from a two-step process involving disaggregation of amyloid-13 deposits via direct biophysical interaction followed by active removal of the amyloid. Aim 2 asks whether systemic immunization, rather than topical application of antibody to cortex, will lead to clearance; if so, we will determine necessary titers and optimal epitopes. Aim 3 takes advantage of in vitro results from several laboratories demonstrating that amyloid-13 binding compounds prevent or reverse formation of amyloid fibrils. We will test whether they are disaggregating agents in vivo. The results will strongly impact the development of treatments aimed at removing senile plaques and the associated neurological damage in Alzheimer's disease.