PLATELET-ENDOTHELIAL CELL INTERACTIONS IN ALZHEIMERS

阿尔茨海默病患者的血小板-内皮细胞相互作用

• 批准号: 2051939
• 负责人: Elizabeth R Simons
• 金额: $ 28.84万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-09-29 至 1996-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2051939
• 关键词: Alzheimer's disease; acidity /alkalinity; amyloid proteins; beta glucuronidase; biological signal transduction; brain disorder diagnosis; calcium flux; cell cell interaction; cell sorting; diagnosis design /evaluation; enzyme linked immunosorbent assay; fluorimetry; granule; human subject; lysosomes; membrane potentials; membrane structure; neuritic plaques; phospholipase A2; platelet activation; platelets; proteolysis; radioimmunoassay; thrombin; tissue /cell culture; vascular endothelium

Although the characteristic deposits of beta-amyloid protein in the brain of Alzheimer's Disease (AD) patients were described many years ago, the discovery that such patients also have beta-amyloid deposits in the vasculature is more recent. There is a strong indication that this proteins's origin is the amyloid precursor protein which has recently been discovered to be present, in relatively large quantities, in the platelet alpha-granules. The mechanism of platelet activation, and subsequent degranulation, as well as the ways in which this precursor's release in AD patients differ from those of normal controls, remain unelucidated, as does the alternative possibility that the platelet activation process and the precursor protein release are normal but that the processing of the precursor into the amyloid protein is abnormal. The origin of this processing enzyme(s), also remains controversial. Since the amyloid deposits are found in the vasculature, the possibility that AD platelets interact differently with the endothelial cells of the vascular wall must be considered. Thus, since deposits of the abnormal degradation product of APP are found in AD but not in normal patients of comparable age, there may be a difference in the platelets' APP content, stimulus response, processing of released products and/or interactions with or in the presence of endothelial cells. Based on our extensive experience in the study of early platelet responses to agonists, we have already begun to investigate the contents, stimulus response, signal transduction and degranulation of AD and normal age- matched platelets, with young adults as controls. In preliminary studies to date we have been able to demonstrate that AD platelets exhibit normal resting membrane potentials and cytoplasmic Ca++ concentrations, but low cytoplasmic pH. Stimulation with thrombin appears to lead to abnormally high levels of granule product release, in conjunction with normal membrane potential and [Ca++] in changes. The granule release appears to be greater in AD than in normal platelets in the presence of endothelial cells as well, and appear to penetrate through that layer when confluent human umbilical vein endothelial cells are involved; cells with tighter junctions, better models of the blood brain barrier, are being prepared. We plan to examine this finding in greater detail, and to use our multiparameter flow kinetic technique which will permit determination of several of these platelet-related events simultaneously, in all the cells or in subpopulations, on very small samples (<1 million cells). We already have permission to study a 75 inpatient, 50 out-patient AD population at the V.A. hospital in Bedford, MA and are getting such permission for the Boston City Hospital's AD hospice which has more female and minority patients. We hope that our studies will delineate differences in AD platelets' interactions with and/or stimulation responses in the presence of endothelial cells. Differences in platelet stimulus responses, per se, may allow the detection of AD, possibly at a very early stage, in living individuals. Differences in their interaction with or processing in the presence of endothelial cells may explain the presence of vascular plaques.

虽然β-淀粉样蛋白在大脑中的特征沉积物 多年前描述了阿尔茨海默氏病（AD）患者 发现此类患者在 脉管系统是最近的。 有很大的迹象表明 蛋白质的起源是淀粉样蛋白的前体蛋白，最近是 被发现存在于血小板中相对较大的存在 α颗粒。 血小板激活的机制，随后 脱粒，以及该先驱在广告中释放的方式 患者与正常对照组的不同，保持不合案 血小板激活过程和 前体蛋白释放是正常的，但处理 进入淀粉样蛋白的前体是异常的。 这个的起源 加工酶（S）也仍然有争议。 自淀粉样蛋白以来 沉积物在脉管系统中发现，AD血小板的可能性 与血管壁的内皮细胞相互作用不同 被考虑。 因此，由于异常降解产物的沉积 应用在AD中发现，但在正常患者中却没有，可能会在 在血小板的应用内容，刺激响应中有所不同， 处理发布的产品和/或与或在存在的情况下进行交互 内皮细胞。 根据我们在研究早期血小板反应的研究中的丰富经验 对于激动剂，我们已经开始研究内容，刺激 AD的反应，信号转导和脱粒和正常年龄 匹配的血小板，年轻人作为对照。 在初步研究中 迄今为止，我们已经能够证明AD血小板表现正常 静息膜电位和细胞质Ca ++浓度，但低 细胞质pH。 用凝血酶刺激似乎会导致异常 高水平的颗粒产品释放，与正常膜结合 电位和[CA ++]的变化。 颗粒释放似乎更大 在存在内皮细胞的情况下，AD中的AD比正常血小板 好吧，当人类融合时似乎穿过该层 脐静脉内皮细胞涉及；细胞更紧密 正在准备连接点，更好的血脑屏障模型。 我们计划更详细地研究这一发现，并使用我们的发现 多参数流动动力学技术将允许确定 这些与血小板相关的事件中的几个同时在所有细胞中 或在亚群中，在很小的样品上（<100万个细胞）。 我们已经 有权研究75个住院，50个门诊广告人群 V.A.马萨诸塞州贝德福德的医院，并获得了这样的许可 波士顿市医院的广告临终关怀医院拥有更多的女性和少数民族 患者。 我们希望我们的研究能够描述广告血小板的差异 在存在的情况下与和/或刺激反应的相互作用 内皮细胞。 血小板刺激反应的差异本身可能 允许在很早的阶段发现AD 个人。 它们与他们与处理或处理的互动差异 内皮细胞的存在可能解释了血管斑块的存在。