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Supplement: Stalled capillary flow affects protein clearance by modulating interstitial fluid flow

补充：毛细血管血流停滞通过调节间质液流动影响蛋白质清除

基本信息

批准号：
10617575
负责人：
Nozomi Nishimura
金额：
$ 13.27万
依托单位：
CORNELL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-05-15 至 2024-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10617575
关键词：
Abeta clearance Acute Affect Alzheimer&apos s Disease Alzheimer&apos s disease model Alzheimer&apos s disease pathology Alzheimer&apos s disease patient Amyloid Amyloid beta-Protein Amyloid beta-Protein Precursor Antibodies Award Basement membrane Binding Biological Assay Blood Vessels Blood capillaries Blood flow Brain Brain region Cell Adhesion Molecules Cerebrovascular Circulation Chronic Cognitive deficits Color Complement Convection Data Dependovirus Disease Disease Progression Elements Endothelial Cells Endothelium Ensure Enzymes Equilibrium Exhibits Extracellular Protein Feedback Fluorescence Microscopy Generations Genes Genetic Engineering Health Hippocampus (Brain)Hour Image Impairment Incidence Individual Inflammatory Injections Intercellular Fluid Ischemia Knock-in Knock-in Mouse Knock-out Lead Leukocytes Link Liquid substance Lymphatic Maps Measurement Mechanics Membrane Proteins Memory Meningeal lymphatic system Modeling Molecular Morphologic artifacts Motion Mus Neurons Oxidative Stress Pathology Pericytes Photons Production Proteins Reactive Oxygen Species Role Side Signal Transduction Speed Stream Stroke Testing Therapeutic Time Tissues Tracer Vasodilation Viral Vector Virus Diseases Wild Type Mouse Work abeta accumulation abeta deposition adeno-associated viral vector arteriole brain volume cell injury cell type cerebral capillary cognitive function constriction design fluid flow fluorescence imaging glymphatic system hypoperfusion improved in vivo intravital imaging mouse model neuropathology neutrophil next generation novel novel therapeutics parent grant pressure prevent protein transport prototype relating to nervous system therapeutic target two-photon venule

项目摘要

Project Summary Cerebral blood flow (CBF) is reduced in Alzheimer’s disease (AD) patients and mouse models by ~20%, but there remains a limited understanding of the mechanisms causing this hypoperfusion or the potential therapeutic benefit of rescuing CBF deficits. Under the previous award, chronic in vivo two-photon excited fluorescence microscopy was used to study CBF in mouse models of AD. While no blood flow disruption in cortical arterioles or venules was observed, blood flow was found to be stalled in ~2% of cortical capillaries in mouse models of AD, as compared to ~0.4% in wild type controls. These capillary stalls appeared early in disease progression, were caused by arrested neutrophils, and had outsized impacts on CBF because they decreased flow speed in up- and down-stream vessels. Antibodies against the neutrophil surface protein Ly6G were serendipitously found to reduce the incidence of capillary stalls immediately, leading to a rescue of two-thirds of the CBF deficit, and, remarkably, to improved memory function within hours. Preliminary data further link this capillary stalling to cellular damage from reactive oxygen species (ROS). In this competitive renewal, the mechanisms underlying neutrophil arrest in capillaries in mouse models of AD and the consequences of improving CBF on AD-related pathology are explored. First, three different hypotheses about the mechanism of neutrophil arrest in capillary segments are tested: a focal constriction of the capillary by a pericyte that prevents neutrophil passage; binding of the neutrophil to increased inflammatory adhesion molecules on endothelial cells; or binding of the neutrophil to basement membrane and adhesion molecules exposed at widened gaps between endothelial cells. Second, the molecular and cellular origin of the ROS that leads to neutrophil arrest is determined using cell type-specific knockouts of ROS producing enzymes. Third, the impact of long-term CBF rescue on the deposition of amyloid- beta (Aβ), a driver of AD pathology, and on neuropathology will be quantified. Critical for this study are recently- developed knock-in mouse models of AD that may better capture the feedback of CBF reductions on expression of amyloid precursor protein (APP), which is cleaved to produce Aβ. Finally, cutting-edge three-photon excited fluorescence microscopy is used to enable imaging of the hippocampus to determine the role of capillary stalling in CBF deficits in one of the first regions of the brain that exhibits AD pathology. The hypothesis that brain hypoperfusion in AD is due to neutrophil arrest in capillaries is both novel and strongly supported by the findings under the previous award. The work proposed in this competitive renewal would uncover the mechanisms underlying that neutrophil arrest, which could suggest therapeutic targets to improve CBF that would be complementary to anti-amyloid and other treatment approaches for AD.

项目摘要阿尔茨海默病（AD）患者和小鼠模型的脑血流量（CBF）减少约20%，但对引起这种低灌注的机制或潜在的治疗方法的理解仍然有限，挽救CBF赤字的好处。根据先前的奖项，慢性体内双光子激发荧光显微镜用于研究AD小鼠模型中的CBF。皮质小动脉无血流中断或小静脉，发现血流在~2%的皮质毛细血管中停滞， AD，相比之下，野生型对照中约为0.4%。这些毛细血管阻塞出现在疾病进展的早期，是由中性粒细胞停滞引起的，对CBF有巨大的影响，因为它们降低了血流速度，上游和下游船只。偶然发现了抗中性粒细胞表面蛋白Ly 6 G的抗体立即降低毛细血管失速的发生率，从而挽救三分之二的CBF赤字，显著地，在几个小时内改善了记忆功能。初步数据进一步将这种毛细血管停滞与活性氧（ROS）的细胞损伤。在这种竞争性的更新中， AD小鼠模型中毛细血管中的中性粒细胞停滞以及改善CBF对AD相关的病理学进行了探索。首先，关于毛细血管中中性粒细胞阻滞机制的三种不同假设节段进行测试：毛细血管的一个局灶性收缩的周细胞，阻止中性粒细胞通过;结合中性粒细胞与内皮细胞上增加的炎性粘附分子的结合;或基底膜和粘附分子暴露在内皮细胞之间加宽的间隙中。第二、使用细胞类型特异性免疫组织化学方法确定导致中性粒细胞停滞的ROS的分子和细胞来源， ROS产生酶的敲除。第三，长期CBF救援对淀粉样蛋白沉积的影响- β（Aβ），AD病理学的驱动因素，以及对神经病理学的影响将被量化。对这项研究至关重要的是最近- 开发了AD的敲入小鼠模型，可以更好地捕获CBF减少对表达的反馈淀粉样前体蛋白（APP），它被切割产生Aβ。最后，尖端的三光子激发荧光显微镜用于使海马成像以确定毛细血管停滞的作用在表现出AD病理学的脑的第一区域中的CBF缺陷中。假设大脑 AD中的低灌注是由于毛细血管中的中性粒细胞阻滞，这是一种新的发现，并得到了研究结果的有力支持在前一个奖项。在这次竞争性更新中提出的工作将揭示潜在的中性粒细胞阻滞，这可能表明治疗目标，以改善CBF，补充抗淀粉样蛋白和其他治疗AD的方法。