Matrix Metalloproteinases and Neurons in Focal Ischemia

描述（由申请人提供）：缺血性中风是由快速的深度神经元损伤和微血管完整性丧失引起的。本提案所要验证的假设表明，在大脑中动脉闭塞（MCA-O）和再灌注过程中，i)神经元的反应部分取决于微血管基板基质和非血管细胞外基质（ECM）缺血的反应，ii)阻断导致基板基质和细胞间ECM这些变化的特定蛋白酶将挽救微血管和神经元免受缺血性损伤。基于先前的工作和初步数据，我们提出降解基质硫酸肝素蛋白聚糖（HSPGs）和硫酸肝素（HSs）的酶与基质金属蛋白酶pro-MMP-2同时在MCA:O下产生，并负责微血管和神经元损伤。本项目的目的是证明特定的基质降解酶在局灶性脑缺血时微血管完整性和神经元存活中起重要作用。具体目标是：1)定位微血管基质中改变含HSPGs和硫酸肝素（包括精选组织蛋白酶和肝素酶）的蛋白酶的化学后表达，并将它们的出现与mmp -2前表达、基板和细胞间ECM完整性以及神经元存活联系起来；2)证明早期再灌注降低HSPG和HS蛋白酶的表达，从而恢复微血管内皮细胞和星形胶质细胞整合素、基底层、细胞间ECM和神经元完整性；3)证明抑制HSPG和hs降解蛋白酶活性可以挽救微血管内皮细胞和星形胶质细胞整合素、基底层、细胞间ECM和神经元完整性；4)抑制MMP-2或选定的组织蛋白酶和肝素酶活性可降低基质HSPG和HS降解，减少脑梗死体积。

DESCRIPTION (provided by applicant): Ischemic stroke results from rapid profound neuron injury and loss of microvascular integrity. The hypotheses to be tested by this Proposal state that during middle cerebral artery occlusion (MCA-O) and reperfusion, i) neuron responses are determined, in part, by the responses to ischemia of the microvessel basal lamina matrix and the nonvascular extracellular matrix (ECM), and ii) blocking specific proteases responsible for these changes in the basal lamina matrix and intercellular ECM will salvage the microvasculature and neurons from ischemic injury. Based upon previous work and preliminary data, we propose that enzymes which degrade matrix heparan sulfate proteoglycans (HSPGs) and heparan sulfates (HSs) are generated following MCA:O, simultaneously with the matrix metalloproteinase pro-MMP-2, and are responsible for microvessel and neuron injury. The goal of this Project is to demonstrate that specific matrix-degrading enzymes play significant roles in microvessel integrity and neuron survival during focal cerebral ischemia. The Specific Aims are to: 1) Localize the postischemic expression of proteases that alter matrix-containing HSPGs and heparan sulfates (including select cathepsins and heparanase) in the microvessel matrix, and relate their appearance to pro-MMP-2 expression, basal lamina and intercellular ECM integrity, and to neuron survival; 2) Demonstrate that early reperfusion reduces expression of HSPG and HS proteases, and thereby recovers microvessel endothelial cell and astrocyte integrins, basal lamina, intercellular ECM, and neuron integrity; 3) Demonstrate that inhibiting HSPG and HS-degrading protease activities can salvage microvessel endothelial cell and astrocyte integrins, basal lamina, intercellular ECM, and neuron integrity; and, 4) Demonstrate that inhibition of MMP-2 or selected cathepsin and heparanase activities decreases matrix HSPG and HS degradation, and reduces the volume of cerebral infarction. Studies of the contributions of HSPG/HS-degrading proteases to the loss of microvessel integrity and neuron injury represent an extension of the ongoing studies of this Proposal, and a new direction in stroke research. They are expected to add substantially to our understanding of the relationships between microvessel matrix and neuron survival in the brain. They also suggest the novel premise that during focal ischemia, neuron injury is mediated in part by changes in specific sensitive matrix components which maintain microvessel integrity and support neuron viability. These studies are likely to lead to new testable therapeutic approaches to preserve mlcrovascular and neuron function which will have relevance to other vascular neuron degenerative disorders.