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，脑微血管通透性屏障出现可检测到的破坏，内皮细胞整合素-基质迅速丢失 受体。在淀粉样血管病中，微血管改变增加了微血管病变的风险。该竞争性更新提案待检验的假设指出：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）局灶性脑缺血破坏受体-基质相互作用，iii）受体-基质相互作用的中断导致血脑屏障表型的丧失。我们已经表明，内皮细胞粘附到完整的基底层基质是中央的屏障的完整性。屏障表型（例如紧密连接（TJ））和血管基质由内皮细胞和星形胶质细胞共同产生，并由两个细胞区室维持。的表达方式1整合素和星形胶质细胞上的肌营养不良蛋白聚糖，以及它们对局部缺血的反应，通过培养的原代内皮细胞和鼠源性星形胶质细胞来模拟。这些反应是基质依赖性的。基于成功完成的工作和初步数据，我们提出，1整合素可以决定TJ蛋白的表达，并构成血脑和基质屏障的“垂直”成分。本项目的目标是证明特定的整合素家族成员的作用是微血管屏障完整性所必需的，并且那些特定的整合素抑制剂、基因构建体和敲除、局灶性缺血和A <$1肽破坏受体-基质相互作用，产生屏障失效。具体目的是证明：1）汇合内皮上的整合素1与基质蛋白的相互作用通过TJ蛋白决定内皮细胞间的凝聚力，并且这些由星形胶质细胞调节，2）整合素1与基质蛋白的相互作用的机制。内皮细胞内整合素1信号介导基质粘附受体介导的TJ表达变化（无或有星形胶质细胞），3）实验性缺血通过改变内皮细胞整合素-基质相互作用显著改变内皮细胞TJ表达，和4）暴露内皮细胞（无或有星形胶质细胞） A肽通过整合素依赖性机制调节TJ表达和微血管通透性屏障表型。这些新的研究提供了一个合理的解释破坏微血管完整性后立即局灶性缺血和淀粉样血管病。由内皮整合素-基质粘附介导的“垂直”组分表明其破坏是血脑屏障丧失的原因。了解整合素-基质粘附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疾病中的微血管屏障功能。

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.