β-淀粉样肽通过血脑屏障的清除:对阿尔茨海默病治疗的意义。

Clearance of amyloid-beta peptide across the blood-brain barrier: implication for therapies in Alzheimer's disease.

作者信息

Deane R, Bell R D, Sagare A, Zlokovic B V

机构信息

Center for Neurodegenerative and Vascular Brain Disorders, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.

出版信息

CNS Neurol Disord Drug Targets. 2009 Mar;8(1):16-30. doi: 10.2174/187152709787601867.

Abstract

The main receptors for amyloid-beta peptide (Abeta) transport across the blood-brain barrier (BBB) from brain to blood and blood to brain are low-density lipoprotein receptor related protein-1 (LRP1) and receptor for advanced glycation end products (RAGE), respectively. In normal human plasma a soluble form of LRP1 (sLRP1) is a major endogenous brain Abeta 'sinker' that sequesters some 70 to 90 % of plasma Abeta peptides. In Alzheimer's disease (AD), the levels of sLRP1 and its capacity to bind Abeta are reduced which increases free Abeta fraction in plasma. This in turn may increase brain Abeta burden through decreased Abeta efflux and/or increased Abeta influx across the BBB. In Abeta immunotherapy, anti-Abeta antibody sequestration of plasma Abeta enhances the peripheral Abeta 'sink action'. However, in contrast to endogenous sLRP1 which does not penetrate the BBB, some anti-Abeta antibodies may slowly enter the brain which reduces the effectiveness of their sink action and may contribute to neuroinflammation and intracerebral hemorrhage. Anti-Abeta antibody/Abeta immune complexes are rapidly cleared from brain to blood via FcRn (neonatal Fc receptor) across the BBB. In a mouse model of AD, restoring plasma sLRP1 with recombinant LRP-IV cluster reduces brain Abeta burden and improves functional changes in cerebral blood flow (CBF) and behavioral responses, without causing neuroinflammation and/or hemorrhage. The C-terminal sequence of Abeta is required for its direct interaction with sLRP and LRP-IV cluster which is completely blocked by the receptor-associated protein (RAP) that does not directly bind Abeta. Therapies to increase LRP1 expression or reduce RAGE activity at the BBB and/or restore the peripheral Abeta 'sink' action, hold potential to reduce brain Abeta and inflammation, and improve CBF and functional recovery in AD models, and by extension in AD patients.

摘要

淀粉样β肽(Aβ)跨越血脑屏障(BBB)从脑到血以及从血到脑转运的主要受体分别是低密度脂蛋白受体相关蛋白1(LRP1)和晚期糖基化终产物受体(RAGE)。在正常人体血浆中,可溶性形式的LRP1(sLRP1)是主要的内源性脑Aβ“汇”,可螯合约70%至90%的血浆Aβ肽。在阿尔茨海默病(AD)中,sLRP1的水平及其结合Aβ的能力降低,这会增加血浆中游离Aβ的比例。这反过来可能通过降低Aβ外流和/或增加Aβ通过血脑屏障的内流来增加脑Aβ负担。在Aβ免疫治疗中,抗Aβ抗体对血浆Aβ的螯合增强了外周Aβ的“汇作用”。然而,与不穿透血脑屏障的内源性sLRP1不同,一些抗Aβ抗体可能会缓慢进入大脑,这会降低其汇作用的有效性,并可能导致神经炎症和脑出血。抗Aβ抗体/Aβ免疫复合物通过血脑屏障经FcRn(新生儿Fc受体)从脑迅速清除到血中。在AD小鼠模型中,用重组LRP-IV簇恢复血浆sLRP1可减轻脑Aβ负担,并改善脑血流(CBF)的功能变化和行为反应,而不会引起神经炎症和/或出血。Aβ的C末端序列是其与sLRP和LRP-IV簇直接相互作用所必需的,而这种相互作用被不直接结合Aβ的受体相关蛋白(RAP)完全阻断。增加BBB处LRP1表达或降低RAGE活性和/或恢复外周Aβ“汇”作用的疗法,有可能减少脑Aβ和炎症,并改善AD模型以及进而AD患者的CBF和功能恢复。

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