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

描述(由申请人提供)：神经血管假说认为，血管血脑屏障(BBB)上淀粉样蛋白(ABP)的脑血外流受损是导致ABP积聚和阿尔茨海默病(AD)患者认知障碍的重要机制。低密度脂蛋白受体相关蛋白-1(LRP)被认为是ABP在血脑屏障的主要外排泵。Zlokovic和他的同事已经证明，在AD患者和过度表达淀粉样前体多肽(APP)的小鼠的血脑屏障中，LRP是缺乏的。我们已经证明，在过度表达ABP的动物中，ABP的外流在血脑屏障处受到损害，而反义APP表达的敲除可以恢复ABP的BBB外流。这表明总部基地毒害了自己的转运体LRP。我们的目的是确定ABP外流受损的机制是否由ABP引起的LRP氧化损伤所致。ABP，特别是其寡聚形式，诱导氧化应激，并通过这一机制损害非血脑屏障组织中LRP以外的转运蛋白的功能。已知非血脑屏障组织中的LRP很容易被氧化，其在这些组织中运输其他配体的能力在其氧化状态下受到损害。我们的假设是，ABP通过氧化LRP来损害其自身在血脑屏障的外流。我们将在3个具体目标中检验这一假设：具体目标1：在体内确定过度表达APP的小鼠是否有氧化的LRP，以及是否可以通过降低ABP的治疗或抗氧化剂将ABP外流恢复到正常水平。具体目的2：在体外使用不过度表达APP的小鼠脑内皮细胞的血脑屏障单层模型中，确定ABP和氧化在损害ABP的血脑屏障外流中的作用。具体目标3：确定死后短时间(PMI；具体地说，死亡后4h)从AD和轻度认知障碍(MCI)患者脑组织中获得的LRP氧化修饰的状态相对于来自对照脑组织的LRP的状态，并将此信息与相同脑组织中ABP1-42的水平和寡聚体状态相关联，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.