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与阿尔茨海默病（AD）患者相似的年龄依赖性方式形成老年斑。最近的证据表明，主动或被动免疫治疗显着防止淀粉样蛋白β沉积在转基因小鼠。除了预防新斑块形成之外，清除阿尔茨海默病患者中存在的淀粉样β 3沉积物对于有效治疗将是至关重要的。在治疗前后观察老年斑是测量现有沉积物清除率的唯一直接方法，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，允许纵向在体内成像的个别斑块。使用这种方法，我们证明了在向皮质单次施用抗体后3-5天，转基因小鼠中现有斑块的清除。在本申请中，我们提出测试有关清除机制的假设。目的1从我们的观察得出，加入F（ab '）2片段也可发生清除，表明Fc介导的机制不是必需的。我们提出了一个模型，其中清除结果从一个两步的过程，涉及解聚的淀粉样蛋白-13沉积物通过直接的生物物理相互作用，然后主动清除的淀粉样蛋白。目的2询问是否全身免疫，而不是局部应用抗体皮质，将导致清除;如果是这样，我们将确定必要的滴度和最佳表位。目的3利用了几个实验室的体外结果，证明淀粉样蛋白-13结合化合物可以防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是解聚剂。这些结果将对旨在消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产生重大影响。

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.