Targeting the apoE/ABeta Interaction as a Novel AD Therapy

描述(申请人提供)：我们的主要假设是，阻断载脂蛋白E和β-淀粉样蛋白之间的相互作用的治疗剂将有效地减少和预防6-淀粉样蛋白(A？)阿尔茨海默病(AD)的相关病理。级联假说认为，A？？肽的积聚在AD的早期发病机制中是一个关键事件。A的超额？聚集成有毒的低聚物，然后沉积在脑实质和引起脑淀粉样血管病(CAA)的血管壁中。载脂蛋白E(ApoE)被认为是促进A？ApoE/AB相互作用的大小似乎是异构体特异性的，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。我们已经证明了用模拟载脂蛋白E结合部位的合成肽-A？12-28P来阻断apoE/AB的结合。并被修改用于体内应用，减少实质AB沉积和CAA的负担，以及防止AD转基因(TG)小鼠的记忆损伤(Sadowski等人)。AJP，2004年；165.937；Sadowski等人，PNAS，2006年；第103：18787)。相比之下，抗-A？疫苗接种方法只预防实质A型流感？在不影响CAA负担的情况下沉积。此外，接种疫苗似乎增加了血管周围出血的风险，这在接受A？12-28P治疗的AD TG动物中是不存在的。在这项拨款提案中，我们计划开发无毒的apoE/A的模拟肽拮抗剂？相互作用将基于A？12-28序列。其目的是提高治疗效果、血脑屏障渗透率和生物稳定性。由于多肽类药物固有的仿生特性、抗降解和易于化学修饰，这一策略在过去已被成功地应用于开发出许多具有治疗前景的化合物。选定的模拟多肽化合物将在AD TG模型中进行测试，包括那些表达不同人类载脂蛋白E亚型的模型。这将用于预测不同人类载脂蛋白E亚型携带者的治疗反应。以确定这种形式的治疗是否可以减少已经存在的A？存款我们将在体内进行A？经颅双光子显微镜观察AD TG小鼠的斑块。尽管阻止apoE/A的主要目标是什么？互动是为了预防A？纤维组装和沉积我们在这一应用中也研究了这种方法的其他几个潜在的好处。因此，我们将确定阻断apoE/A？A上的交互？和载脂蛋白E跨血脑屏障的清除量，A？寡聚体和纤维的形成以及apoE/A在神经元内的积聚？复合体。这项建议的总体目标是使这一新的治疗方法更接近临床研究，并确定一种先导性多肽化合物，该化合物可以进一步开发用于安全、长期应用于人类。

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.