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，内皮细胞�1整合素基质迅速丧失。 感受器。在淀粉样血管病中，微血管的改变增加了微出血的风险。这一竞争性更新方案将检验的假设是：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)局灶性脑缺血破坏受体-基质相互作用，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。我们已经证明，内皮细胞与完整的基底板基质的黏附是屏障完整性的核心。屏障表型(如紧密连接(TJ))和血管基质由内皮细胞和星形胶质细胞共同产生，并由两个细胞室维持。原代培养的小鼠内皮细胞和星形胶质细胞在原代培养的内皮细胞和星形胶质细胞上模拟�1整合素和星形胶质细胞��-dystroglan的表达及其对局灶性缺血的反应。这些反应依赖于矩阵。基于成功完成的工作和初步数据，我们认为�-1整合素可以决定TJ蛋白的表达，并构成血脑屏障和基质屏障的“垂直”成分。本项目的目的是证明特定的�1整合素家族成员的作用是微血管屏障完整性所必需的，这些特定的整合素抑制剂、基因结构和敲除、局灶性缺血和A�1肽破坏受体-基质相互作用，导致屏障失效。其具体目的是证明：1)融合内皮细胞上�1整合素与基质蛋白的相互作用决定了TJ蛋白对内皮细胞间凝聚力的影响，并受星形胶质细胞的调节；2)内皮细胞内�1整合素信号转导机制介导基质黏附受体介导的TJ表达变化(不含或与星形胶质细胞)；3)实验性缺血通过改变内皮细胞�1整合素与基质的相互作用显著改变内皮细胞的TJ表达；以及4)内皮细胞(不含或与星形胶质细胞)暴露。 �多肽通过�1整合素依赖机制调节TJ表达和微血管通透性屏障表型。这些新的研究为局灶性缺血和淀粉样血管病变后微血管完整性的破坏提供了一个可信的解释。内皮细胞�-1整合素-基质黏附介导的“垂直”成分提示其破坏是血脑屏障丧失的前提。了解�-1整合素-基质黏附的机制可能会导致新的可测试的方法来保存或选择性地改变其他神经血管疾病的微血管屏障功能。

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 occurs, with rapid loss of the endothelial cell �1 integrin-matrix receptors. In amyloid angiopathy, microvessel alterations increase the risk of microhemorrhages. The hypotheses to be tested by this competing renewal Proposal state that i) the interaction of matrix receptors on microvessel endothelial cells (and astrocytes) with matri components of the basal lamina are a major determinant of the blood-brain barrier phenotype, ii) focal cerebral ischemia disrupts receptor-matrix interactions, and iii) interruptions of receptor-matrix interactions result in loss of the blood brain barrier phenotype. We have shown that adhesion of endothelial cells to the intact basal lamina matrix is central to the integrity of the barrier. The barrier phenotype (e.g. tight junctions (TJs)) and vascular matrix are generated by endothelial cells and astrocytes in concert, and are maintained by both cell compartments. The expression of �1 integrins on endothelial cells and ��-dystroglycan on astrocytes in vivo, and their responses to focal ischemia, are mimicked by primary endothelial cells and astrocytes of murine origin in culture. These responses are matrix-dependent. Based upon successful completed work and preliminary data, we propose that �1 integrins can determine TJ protein expression, and constitute the "vertical" component of the blood- brain and matrix barriers. The goal of this Project is to demonstrate that the actions of specific �1 integrin family members are required for the integrity of the microvessel barrier, and those specific integrin inhibitors, geneic constructs and knockdowns, focal ischemia, and A�1 peptides disrupt the receptor-matrix interactions, producing barrier failure. The Specific Aims are to demonstrate that: 1) the interactions of �1 integrins on confluent endothelium with matrix proteins determine inter-endothelial cell cohesion by the TJ proteins, and these are modulated by astrocytes, 2) mechanisms of �1 integrin signaling within endothelial cells mediate the matrix adhesion receptor-mediated changes in TJ expression (without or with astrocytes), 3) experimental ischemia significantly alters endothelial cell TJ expression by altering the endothelial cell �1 integrin-matrix interactions, and 4) the exposure of endothelial cells (without or with astrocytes) to A�-peptides modulates TJ expression and the microvessel permeability barrier phenotype via �1 integrin-dependent mechanisms. These novel studies provide a plausible explanation for the disruption of microvessel integrity immediately following focal ischemia and by amyloid angiopathy. The "vertical" component mediated by endothelial �1 integrin-matrix adhesion suggests the premise that its disruption is responsible for loss of the blood-brain barrier. Understanding the mechanisms of the �1 integrin-matrix adhesion is likely to lead to new testable approaches to preserve or selectively alter microvessel barrier function in other neurovascular disorders.