Matrix Metalloproteinases and Neurons in Focal Ischemia

缺血性中风是由于神经元迅速严重损伤和微血管完整性丧失所致。的 本提案待检验的假设指出，在大脑中动脉闭塞（MCA-O）期间， i）神经元反应部分地由对脑缺血的反应决定， 微血管基底层基质和非血管细胞外基质（ECM），和ii）阻断 负责基底层基质和细胞间ECM变化的特异性蛋白酶 能从缺血性损伤中挽救微血管和神经元根据以前的工作和 根据初步数据，我们提出降解基质硫酸乙酰肝素蛋白聚糖（HSPGs）的酶 和硫酸乙酰肝素（HS）生成后，MCA：O，同时与基质 基质金属蛋白酶原MMP-2，并负责微血管和神经元损伤。这个目标 本项目旨在证明特定的基质降解酶在微血管中发挥重要作用 完整性和神经元存活。具体目标是：（1）使后- 改变含有基质的HSPG和硫酸乙酰肝素的蛋白酶（包括选择的 组织蛋白酶和乙酰肝素酶），并将其外观与pro-MMP-2 表达，基底层和细胞间ECM完整性，以及神经元存活; 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 细胞和星形胶质细胞整合素、基底膜、细胞间ECM和神经元完整性; 3）证明 抑制HSPG和HS降解蛋白酶活性可挽救微血管内皮细胞和星形胶质细胞 整联蛋白、基底层、细胞间ECM和神经元完整性;和，4）证明MMP-2抑制 或选择的组织蛋白酶和乙酰肝素酶活性降低基质HSPG和HS降解， 脑梗死体积。 HSPG/HS降解蛋白酶在微血管完整性和神经元损伤中作用的研究 损伤的研究是本建议正在进行的研究的延伸，也是卒中研究的新方向。 他们预计将大大增加我们对微血管基质之间关系的理解， 和大脑中神经元的存活。他们还提出了一个新的假设，即在局灶性缺血期间， 损伤部分由维持微血管的特异性敏感基质成分的变化介导 完整性和支持神经元活力。这些研究可能会导致新的可测试的治疗方法 保护微血管和神经元功能，这将与其他血管神经元相关 退行性疾病

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 post- ischemic 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.