Extracellular vesicle transport of brain-derived proteins to the blood in Alzheimer disease

总结 越来越多的证据表明，细胞外囊泡（EV），膜囊泡，可以是 由大多数细胞类型分泌，介导细胞间通讯，在细胞间通讯中发挥重要作用。 阿尔茨海默病（AD）的起始和/或进展。具体而言，已经证明， β淀粉样蛋白（Aβ）、tau和其他与AD密切相关的蛋白质的细胞间转移 发病机制，以及朊病毒样传播的AD病理在中枢神经系统 中枢神经系统（CNS）的免疫调节至少部分地经由EV介导。此外，携带独特疾病的电动汽车- 特异性和功能上重要货物在体内可在血液、脑脊液（CSF） 和其他体液最近，我们和其他人已经证明，电动汽车不仅可以 通过血脑屏障（BBB），虽然运输机制尚不清楚，但 此外，基于血液但CNS特异性的EV分子可以是生物标志物的有价值的来源， 神经退行性疾病，包括AD。在这项研究中，我们将首先使用我们先进的蛋白质组学 筛选AD相关神经元亚群或脑特异性EV表面标志物的技术 区域，以确定更多的中枢神经系统和AD特异性EV标志物，并在平行适应我们的纳米粒子 分选和单分子定量技术，以实现CNS衍生的高纯度分离 血浆中的EV和此类EV中的蛋白质的高精度定量，以解决几个主要的 当前领域的挑战。使用当前已知的（例如，L1 CAM）和更多的CNS-和AD- 特异性CNS衍生的EV表面标志物，以及现有和进一步开发的EV分离 和定量技术，然后我们将比较AD相关的生物标志物在L1 CAM含有 EV或来自人类患者血浆中AD相关神经元亚群的EV， 重点关注经典AD蛋白和已知EV候选蛋白，特别是Aβ，tau， α-突触核蛋白及其各种亚型;必要时可研究其他新靶点。为 已证实的AD相关EV蛋白，我们将进一步研究其在动物体内的纵向变化 模型并探索它们从大脑转运到血液的机制（例如， 在细胞和动物模型中穿过BBB）以及改变它们作为新的未来AD的潜在方法 治疗目标。拟议中的实验可能会建立一个基础， 廉价和广泛可用的测试，以帮助AD诊断和/或疾病跟踪。另夕h 提出的一系列研究是阐明新的潜在清除的重要的第一步 潜在的毒性CNS蛋白种类的途径，并最终可能提供关键机会， 治疗上解决与AD中的神经变性相关的病理学。

Summary Growing evidence suggests that extracellular vesicles (EVs), membrane vesicles that can be secreted by most cell types to mediate intercellular communication, play important roles in the initiation and or progression of Alzheimer disease (AD). Specifically, it has been demonstrated that cell-to-cell transfer of amyloid beta (Aβ), tau, and other proteins critically involved in AD pathogenesis, as well as the prion-like propagation of AD pathology within the central nervous system (CNS) is mediated at least in part via EVs. Additionally, EVs carrying unique, disease- specific, and functionally important cargo are detectable in vivo in blood, cerebrospinal fluid (CSF) and other body fluids. More recently, we and others have demonstrated not only that EVs may cross the blood-brain barrier (BBB), though the transportation mechanism remains unclear, but also that blood-based but CNS-specific EV molecules can be a valuable source of biomarkers for neurodegenerative diseases, including AD. In this study, we will first use our advanced proteomics techniques to screen for EV surface markers specific to AD-related neuronal subpopulations or brain regions to identify more CNS- and AD- specific EV markers, and in parallel adapt our nanoparticle sorting and single-molecule quantification technologies to enable high-purity isolation of CNS-derived EVs in plasma and high-precision quantification of proteins in such EVs to address several major challenges in the current field. Using the currently known (e.g., L1CAM) and more CNS- and AD- specific, CNS-derived EV surface markers, as well as the existing and further developed EV isolation and quantification technologies, we will then compare AD-related biomarkers in L1CAM-containing EVs or those from AD-related neuronal subpopulations in blood plasma from human patients, focusing on the performance of classic AD proteins and known EV candidates, specifically, Aβ, tau, α-synuclein, and their various isoforms; additional novel targets may be studied when necessary. For the verified AD-related EV proteins, we will further examine their longitudinal changes in animal models and explore the mechanisms by which they are transported from the brain to blood (e.g., crossing BBB) in cellular and animal models and potential ways to alter them as novel future AD treatment targets. The proposed experiments will likely establish the foundation leading to an inexpensive and widely available test to aid in AD diagnosis and/or disease tracking. Additionally, the proposed set of studies is an important initial step toward elucidating a novel potential clearance pathway for potential toxic CNS protein species and ultimately it may provide critical opportunities for therapeutically addressing the pathology associated with neurodegeneration in AD.