Matrix Metalloproteinases and Neurons in Focal Ischemia

缺血性卒中是由迅速的深层神经元损伤和微血管完整性丧失引起的。这个 这一建议将检验的假设表明，在大脑中动脉闭塞(MCA-O)期间 和再灌流，i)神经元的反应部分地由神经元对缺血的反应决定 微血管基板基质和非血管细胞外基质(ECM)，以及ii)阻断 导致基底板基质和细胞间ECM变化的特定蛋白水解酶 将挽救缺血损伤的微血管和神经元。基于以前的工作和 初步数据，我们提出了降解基质硫酸乙酰肝素蛋白多糖(HSPGs)的酶 和硫酸乙酰肝素(HSS)在MCA：O之后与基质同时生成 金属蛋白酶原-基质金属蛋白酶-2，并与微血管和神经元损伤有关。这样做的目的是 该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 局灶性脑缺血期间的完整性和神经元存活。具体目标是：1)本地化后- 改变含有基质的HSPG和硫酸乙酰肝素的蛋白水解酶的缺血表达(包括SELECT 组织蛋白和肝素酶)在微血管基质中的表达，并将它们的出现与前-基质金属蛋白酶-2联系起来。 表达、基底膜和细胞间ECM的完整性，以及对神经元存活的影响；2)表明早期 再灌流减少HSPG和HS蛋白的表达，从而恢复微血管内皮细胞 细胞和星形胶质细胞整合素、基底板、细胞间ECM和神经元完整性；3)证明 抑制HSPG和HS降解酶活性可挽救微血管内皮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；以及，4)证明了对基质金属蛋白酶-2的抑制。 或选定的组织蛋白酶和乙酰肝素酶活性可减少基质HSPG和HS的降解，并减少 脑梗塞体积。 HSPG/HS降解酶在微血管完整性和神经元损伤中作用的研究 损伤代表了对这一提议正在进行的研究的延伸，也是中风研究的一个新方向。 它们有望大大加深我们对微血管基质之间关系的理解。 以及大脑中神经元的存活。他们还提出了一个新的前提，即在局灶性缺血期间，神经元 损伤在一定程度上是由维持微血管的特定敏感基质成分的变化介导的 完整性和支持神经元的生存能力。这些研究可能导致新的可测试的治疗方法。 保护微血管和神经元的功能，这将与其他血管神经元相关 退化性疾病。

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.