Oxidative Dysfunction of LRP at the Blood-brain Barrier in Alzheimer's Disease

描述（由申请人提供）：神经血管假说指出，血管血脑屏障（BBB）处淀粉样蛋白（ABP）的脑-血流出受损是阿尔茨海默病（AD）患者ABP蓄积和认知障碍的重要机制。低密度脂蛋白受体相关蛋白-1（LRP）已被确定为ABP在BBB的主要外排泵。Zlokovic及其同事已经证明，LRP在AD患者和过表达淀粉样前体肽（APP）的Hsiao小鼠的BBB中是缺乏的。我们已经表明，ABP流出受损，在BBB的动物，ABP过表达和APP表达的敲低与反义恢复ABP的BBB流出。这表明ABP毒害其自身的转运蛋白LRP。我们的目标是确定ABP外排受损的机制是否是由ABP诱导的LRP氧化损伤引起的。ABP，特别是其寡聚体形式，诱导氧化应激，并通过该机制损害非BBB组织中除LRP之外的转运蛋白的功能。已知非BBB组织中的LRP容易被氧化，并且其在那些组织中转运其其他配体的能力在其氧化状态下受损。我们的假设是ABP通过氧化LRP来损害其自身在BBB的流出。我们将在3个具体目标中检验这一假设：具体目标1：在体内确定过表达APP的小鼠是否具有氧化的LRP，以及ABP流出是否可以通过降低ABP或抗氧化剂的治疗恢复到正常速率。具体目标二：在BBB单层模型中确定ABP和氧化在体外损害ABP的BBB外排中的作用，该模型使用来自不过表达APP的小鼠的脑内皮细胞。具体目的3：确定在死后短时间间隔获得的人脑组织中LRP的氧化修饰状态（采购经理人指数;具体地说，死亡后<4小时）与对照脑组织相比的差异，并将该信息与ABP 1 - 3水平和寡聚状态相关联。42，并将其与过度表达APP的小鼠的类似分析进行比较。

DESCRIPTION (provided by applicant): The neurovascular hypothesis states that an impaired brain-to-blood efflux of amyloid ¿ protein (ABP) at the vascular blood-brain barrier (BBB) is an important mechanism underlying ABP accumulation and cognitive impairments in patients with Alzheimer's disease (AD). Low-density lipoprotein receptor-related protein-1 (LRP) has been identified as the major efflux pump at the BBB for ABP. Zlokovic and co-workers have shown that LRP is deficient in the BBB of patients with AD and of Hsiao mice that overexpress amyloid precursor peptide (APP). We have shown that ABP efflux is impaired at the BBB in animals which overexpress ABP and that knockdown of APP expression with antisense restores BBB efflux of ABP. This suggests that ABP poisons its own transporter, LRP. Our goal is to determine whether the mechanism of impaired efflux of ABP is caused by ABP-induced oxidative damage to LRP. ABP, especially in its oligomeric form, induces oxidative stress and by this mechanism impairs the function of transporters other than LRP in non-BBB tissues. LRP in non-BBB tissues is already known to be readily oxidized and its ability to transport its other ligands in those tissues is impaired in its oxidative state. Our hypothesis is that ABP impairs its own efflux at the BBB by oxidizing LRP. We will test this hypothesis in 3 Specific Aims: Specific Aim 1: To determine in vivo whether mice that do overexpress APP have an oxidized LRP and whether ABP efflux can be restored to normal rates by treatments which reduce ABP or by antioxidants. Specific Aim 2: To determine the role of ABP and oxidation in impairing BBB efflux of ABP in vitro in a BBB monolayer model that uses brain endothelial cells derived from mice that do not overexpress APP. Specific Aim 3: To determine the status of oxidative modification of LRP in human brain tissue obtained at short post mortem intervals (PMI; specifically, < 4h after death) from patients with AD and mild cognitive impairment (MCI) relative to that from control brain tissue and correlate this information to the level and oligomeric status of ABP1-42 in those same brains and to compare this to a similar analysis for the mice that overepress APP.