Neurovascular Adhesion Receptors and Barrier Integrity

描述(由申请人提供)：缺血性中风会导致微血管完整性的迅速严重丧失。局灶性脑缺血后早期，可检测到脑微血管通透性屏障的破坏，其基底膜的基质成分迅速变化。这一提议要检验的假设如下：i)微血管内皮细胞和星形胶质细胞上的基质受体与基底膜的基质成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)所致的局灶性脑缺血破坏了受体-基质的相互作用，以及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间紧密连接。但是，内皮细胞和星形胶质细胞与完整的基底板基质的粘附性也可能是重要的。血管基质是由血管内皮细胞和星形胶质细胞在发育过程中共同产生的，并由内皮细胞和星形胶质细胞通过其基质黏附受体维持。黏附受体可将脑微血管内皮细胞和星形胶质细胞与基底膜基质结合，包括特异的整合素、α和β-肌营养不良多糖。根据以前的工作和初步数据，我们认为整合素和营养不良多糖都是血脑屏障和基质屏障完整性的核心。该项目的目的是证明这两个黏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，以及局灶性缺血、缺氧和破坏这些受体-基质相互作用的特定抑制剂会导致屏障失效。其具体目的是：1)证明通过细胞受体(整合素和营养不良多糖)的细胞黏附决定内皮细胞-基质-星形胶质细胞和血脑屏障的完整性；2)证明MCAO或低氧显著改变内皮细胞-星形胶质细胞界面的整合素-基质和营养不良糖-基质相互作用；以及3)证明细胞黏附受体-基质相互作用的破坏不依赖于金属蛋白酶的表达。这些研究为局灶性缺血后脑内皮细胞屏障对小分子的破坏和微血管的完整性提供了一个新的可信的解释。星形胶质细胞末端足部对选择的整合素和营养不良多糖的特殊使用，以及内皮细胞对1整合素的特殊使用，表明了一个新的前提，即局灶性脑缺血对它们的早期破坏是导致血脑屏障丧失的原因。了解它们表达和破坏的机制可能会导致新的可测试的方法，以保持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.