Targeting cross-linked amyloid protein species as a therapy for AD.

描述（由申请人提供）：β -淀粉样蛋白沉积物中β -蛋白的过度积累是阿尔茨海默病（AD）的标志性事件。近年来，增强β -淀粉样蛋白清除的一些最有前途的治疗策略涉及抗β抗体的使用。在AD转基因动物模型中，β -淀粉样蛋白沉积可以通过外周输注外源性抗Abeta抗体（被动）或通过合成Abeta肽免疫诱导的自身免疫（主动）来抑制。不幸的是，后一种方法与潜在的致命并发症有关，包括人类中枢神经系统血管的炎症。虽然迄今为止的实验采用未修饰的单体β来检测自身免疫，但阿尔茨海默病大脑中高达40%的β库由低分子量低聚交联β -淀粉样蛋白物种（CAPS）组成。此外，许多证据表明可溶性CAPS是AD的主要神经毒性因子。我们最近报道，虽然AD患者血浆中针对单体β的自身抗体水平与非痴呆对照组相似，但AD患者血浆中针对CAPS的自身抗体水平显著降低。此外，AD的发病年龄与血浆对CAPS的免疫反应性相关。基于这些发现，我们假设针对CAPS的Abeta自身抗体亚库可能在正常情况下提供对AD发病机制的自然防御，但在AD患者中被耗尽。因此，补充抗caps抗体水平可能为AD提供潜在的治疗益处。在我们提出的研究中，我们计划a)鉴定具有最高神经毒性潜力的CAPS， b)使用重组噬菌体展示系统选择单链片段可变抗体（scFvs）特异性针对最具神经毒性的CAPS，从超过10^12种人源抗体的载体库中鉴定CAPS特异性免疫反应性scFvs，以及c)测试抗CAPS scFv抗体在皮层神经元原代培养中减弱CAPS神经毒性的活性。我们假设，用人源性抗体靶向可溶性cap可能比以前使用更通用的抗β抗体的基于疫苗的AD治疗策略具有明显的优势。最后，在被动免疫治疗方面，通过专门针对与AD病理最相关的Abeta物种，可能会开出较低的抗Abeta抗体滴度，从而减轻与炎症相关的潜在副作用。

DESCRIPTION (provided by applicant): Excessive accumulation of Abeta protein in beta-amyloid deposits is a hallmark event in Alzheimer's disease (AD). In recent years, some of the most promising therapeutic strategies for potentiating beta-amyloid clearance has involved the use of anti-Abeta antibodies. In transgenic animal models of AD beta-amyloid deposition can be inhibited by either peripheral infusion of exogenous anti-Abeta antibodies (passive) or autoimmunity induced by immunization with synthetic Abeta peptide (active). Unfortunately, the latter approach has been associated with potentially fatal complications involving inflammation of the CNS vasculature in humans. While experiments to date have employed unmodified monomeric Abeta to test for autoimmunity, up to 40 % of the Abeta pool in AD brain consists of low molecular weight oligomeric cross-linked beta-amyloid protein species (CAPS). Moreover, numerous lines of evidence have implicated soluble CAPS as the primary neurotoxic agent in AD. We have recently reported that while levels of autoantibodies to monomeric Abeta are similar in the plasma of AD and non-demented control subjects, autoantibodies to CAPS are significantly reduced in AD patients. In addition, age-at-onset for AD correlates with plasma immunoreactivity to CAPS. Based on these findings, we hypothesize that the sub-pool of Abeta autoantibodies targeted at CAPS may normally provide a natural defense against AD pathogenesis, but are depleted in AD patients. Accordingly, replenishing the level of anti-CAPS antibodies could potentially provide therapeutic benefit for AD. In the proposed study we plan to a) identify CAPS with the highest neurotoxic potential, b) select single-chain fragment variable antibodies (scFvs) specific for the most neurotoxic CAPS using recombinant phage display system to identify CAPS-specific immunoreactive scFvs from a vector library of over 10^12 human derived antibodies, and, c) test anti-CAPS scFv antibodies for activity in attenuating CAPS neurotoxicity in primary cultures of cortical neurons. We posit that targeting soluble CAPS with human derived antibodies may have distinct advantages over previous vaccine-based AD treatment strategies that have employed more generic anti-Abeta antibodies. Finally, with regard to passive immunization therapies, by specifically targeting the Abeta species that are most relevant to AD pathology, lower anti-Abeta antibody titers might be prescribed, thereby attenuating potential side-effects associated with inflammation.