Targeting the apoE/ABeta Interaction as a Novel AD Therapy

描述（由申请人提供）：我们的主要假设是一种治疗药物阻断载脂蛋白E和？-淀粉样蛋白将有效减少和预防6-淀粉样蛋白（A?）相关的阿尔茨海默病（AD）病理。的吗?-淀粉样蛋白级联假说认为，A?？肽在阿尔茨海默病的早期发病机制中起关键作用。A的过量？组装成有毒的低聚物，随后沉积在脑实质和血管壁上，产生脑淀粉样血管病（CAA）。A之间的直接结合？载脂蛋白E （apoE）已被确定为促进A？并调节其通过血脑屏障（BBB）的清除。apoE/AB相互作用的程度似乎是同工异构体特异性的，这为apoE4等位基因与散发性AD风险增加之间的联系提供了一种解释。我们已经证明阻断apoE/AB结合与合成肽- a ？12-28P，模仿apoE在A上的结合位点？在AD转基因（Tg）小鼠中，减少了实质AB沉积和CAA的负担，并防止了记忆障碍（Sadowski等）。美国,2004;165:937;Sadowski et al.， PNAS, 2006；103:18787)。相反，anti-A？疫苗接种方法只能预防实质甲型肝炎？沉积而不影响CAA负担。此外，接种疫苗似乎增加了AD - Tg动物血管周围出血的风险，而用a12 - 28p治疗的AD - Tg动物没有血管周围出血的风险。在这项拨款申请中，我们计划开发apoE/A？相互作用将基于A？银幕上序列。目的是提高治疗效果、血脑屏障渗透和生物稳定性。由于肽模拟物固有的仿生特性，它们的抗降解性和易于化学修饰，这种策略在过去已经成功地用于开发许多有治疗前景的化合物。选定的拟肽化合物将在AD - Tg模型中进行测试，包括表达不同人类apoE亚型的模型。这将用于预测各种人类载脂蛋白e亚型携带者的治疗反应。为了确定这种形式的治疗是否可以导致已经存在的a ？我们将对A？经颅双光子显微镜观察AD - Tg小鼠斑块。虽然阻断apoE/A的主要目标？相互作用是为了防止A？纤维组装和沉积也有其他几个潜在的好处，我们在这个应用中调查的方法。因此，我们将确定阻断apoE/A？A上的相互作用？和apoE清除血脑屏障，A？低聚物和纤维的形成，以及apoE/A在神经元内的积累？复合物。这项提议的总体目标是使这种新的治疗方法更接近临床研究，并确定一种先导的拟肽化合物，这种化合物可以进一步开发用于安全、长期的人体应用。

DESCRIPTION (provided by applicant): Our main hypothesis is that a therapeutic agent blocking the interaction between apolipoprotein E and ?-amyloid will be effective in reducing and preventing 6-amyloid (A?) related pathology of Alzheimer's disease (AD).The ?-amyloid (A?) cascade hypothesis maintains that accumulation of the A??peptide constitutes a critical event in the early pathogenesis of AD. An excess of A? assembles into toxic oligomers and subsequently into deposits in the brain's parenchyma and in walls of vessels producing cerebral amyloid angiopathy (CAA).The direct binding between A? and apolipoprotein E (apoE) has been identified as an important factor promoting the deposition of A? in the CMS and regulating its clearance across the blood-brain-barrier (BBB).The magnitude of apoE/AB interaction appears to be isoform specific, providing one explanation for the linkage between the apoE4 allele and an increased risk of sporadic AD. We have demonstrated that blocking the apoE/AB binding with a synthetic peptide - A?12-28P, that mimics the apoE binding site on A? and was modified for in vivo application, reduces the burden of parenchynal AB deposits and CAA, as well as preventing memory impairment in AD transgenic (Tg) mice (Sadowski et al. AJP, 2004; 165:937; Sadowski et al., PNAS, 2006; 103:18787). In contrast, anti-A? vaccination approaches prevent only parenchymal A? deposition without affecting the CAA burden. In addition, vaccination appears to increase the risk of perivascular hemorrhages which were absent in AD Tg animals treated with A?12-28P. In this grant proposal, we are planning to develop non-toxic peptidomimetic antagonists of the apoE/A? interaction which will be based on the A?12-28 sequence. The objectives are to improve therapeutic efficacy, BBB penetration, and biostability. Due to the inherent biomimetic character of peptidomimetics, their resistance to degradation, and ease of chemical modification, this strategy has been successfully employed in the past to develop a number of therapeutically promising compounds. Selected peptidomimetic compounds will be tested in AD Tg models including those expressing differing human apoE isoforms. This will be done to predict the therapeutic response in carriers of the various human apoE isoforms. To determine whether this form of therapy can lead to a reduction of already existing A? deposits we will perform in vivo imaging of A? plaques in AD Tg mice using transcranial two-photon microscopy. Although the primary goal of blocking the apoE/A? interaction is to prevent A? fibrillar assembly and deposition there are also several other potential benefits of this approach which we investigate in this application. Thus, we will determine the effect of blocking the apoE/A? interaction on A? and apoE clearance across the BBB, the equilibrium between A? oligomers and fibril formation, and intraneuronal accumulation of apoE/A? complexes. The overall goal of this proposal is to bring this novel therapeutic approach closer to clinical studies and to identify a lead peptidomimetic compound, which could be further developed for safe, long-term application in humans.