Neurovascular Adhesion Receptors and Barrier Integrity

描述（由申请人提供）：缺血性卒中导致微血管完整性迅速严重丧失。局灶性缺血后早期可检测到脑微血管通透性屏障的破坏，以及基底膜基质成分的快速变化。本提案待检验的假设陈述：i）微血管内皮细胞和星形胶质细胞上的基质受体与基底层的基质组分的相互作用是血脑屏障表型的主要决定因素，ii）大脑中动脉闭塞（MCAO）引起的局灶性缺血破坏了受体-基质相互作用，和iii）受体-基质相互作用的中断导致血脑屏障表型的丧失。通透性屏障的表型涉及内皮细胞间的紧密连接。但是，内皮细胞和星形胶质细胞对完整基底层基质的粘附也可能是重要的。血管基质由内皮细胞和星形胶质细胞在发育过程中共同产生，并由内皮细胞和星形胶质细胞通过其基质粘附受体维持。可以将脑微血管内皮细胞和星形胶质细胞结合到基底层基质的粘附受体包括特异性整合素和α和β肌营养不良聚糖。基于以前的工作和初步数据，我们提出，整合素和肌营养不良蛋白聚糖的血脑和基质屏障的完整性的核心。本项目的目的是证明这两种粘附受体家族的特定成员的作用是微血管屏障功能完整性所必需的，并且局灶性缺血、缺氧和破坏这些受体-基质相互作用的特异性抑制剂会导致屏障失效。具体目标是：1）证明通过细胞受体（整联蛋白和肌营养不良蛋白聚糖）的细胞粘附决定内皮细胞-基质-星形胶质细胞和血脑屏障的完整性; 2）证明MCAO或缺氧显著改变内皮细胞-星形胶质细胞界面处的整联蛋白-基质和肌营养不良蛋白聚糖-基质相互作用;和3）证明细胞粘附受体-基质相互作用的破坏独立于金属蛋白酶表达而发生。这些研究提供了一种新的合理的解释破坏脑内皮细胞屏障的小分子和微血管的完整性后立即局灶性缺血。选择整合素和肌营养不良蛋白聚糖的星形胶质细胞末端足的特定用途，和内皮细胞的1整合素的特定用途表明新的前提，即局灶性缺血对它们的早期破坏是导致血脑屏障丧失的原因。了解其表达和破坏的机制可能会导致新的可测试的方法来保护或选择性地改变其他神经血管退行性疾病的屏障功能和微血管完整性。

DESCRIPTION (provided by applicant): Ischemic stroke produces rapid profound loss of microvascular integrity. Early following focal ischemia detectable disruption in the permeability barrier of cerebral microvessels, and rapid changes in the matrix composition of their basal lamina occur. The hypotheses to be tested by this proposal state i) that the interaction of matrix receptors on microvessel endothelial cells and astrocytes with the matrix components of the basal lamina are a major determinant of the blood-brain barrier phenotype, ii) that focal ischemia by middle cerebral artery occlusion (MCAO) disrupts receptor-matrix interactions, and iii) that interruptions of the receptor-matrix interaction results in loss of the blood brain barrier phenotype. The phenotype of the permeability barrier involves the inter-endothelial tight junctions. But, adhesion of endothelial cells and astrocytes to the intact basal lamina matrix is also likely to be important. The vascular matrix is generated by endothelial cells and astrocytes in concert during development, and is maintained by both endothelial cells and astrocytes through their matrix adhesion receptors. Adhesion receptors which could bind cerebral microvascular endothelial cells and astrocytes to the basal lamina matrix include specific integrins and the a and ¿ dystroglycans. Based upon previous work and preliminary data, we propose that both integrins and dystroglycans are central to the integrity of the blood-brain and matrix barriers. The goal of this Project is to demonstrate that the action of specific members of these two adhesion receptor families is required for the integrity of the microvessel barrier functions, and that focal ischemia, hypoxia, and specific inhibitors that disrupt these receptor - matrix interactions, produce barrier failure. The Specific Aims are to: 1) Demonstrate that cell adhesion via cell receptors (integrins and dystroglycans) determine endothelial cell-matrix-astrocyte and blood brain barrier integrity; 2) Demonstrate that MCAO or hypoxia significantly alter integrin-matrix and dystroglycan-matrix interactions at the endothelial cell-astrocyte interface; and 3) Demonstrate that the disruption of the cell adhesion receptor-matrix interactions occur independent of metalloproteinase expression. These studies provide a novel plausible explanation for the disruption of both the cerebral endothelial cell barrier to small molecules and the microvascular integrity immediately following focal ischemia. The specific use of select integrins and dystroglycans by astrocyte end-feet, and of ¿1 integrins by endothelial cells suggests the novel premise that their early disruption by focal ischemia is responsible for loss of the blood brain barrier. Understanding the mechanisms of their expression and disruption is likely to lead to new testable approaches to preserve or selectively alter barrier function and microvessel integrity in other neurovascular degenerative disorders.