Role of Matrix Metalloproteinases in Spinal Cord Injury

基质金属蛋白酶在脊髓损伤中的作用

• 批准号: 7052777
• 负责人: LINDA J. NOBLE
• 金额: $ 34.21万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-30 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7052777
• 关键词: angiogenesis; basal lamina; collagenase; elastases; enzyme activity; extracellular matrix; flow cytometry; gene mutation; genetically modified animals; inflammation; laboratory mouse; molecular pathology; neural plasticity; neutrophil; protease inhibitor; spinal cord injury; tight junctions; vascular endothelium permeability; white matter; wound healing

DESCRIPTION (provided by applicant): The injured spinal cord is exposed to early barrier disruption and inflammation as well as complex repair processes that collectively define an environmental terrain that influences axonal plasticity and governs the extent of functional recovery. This proposal examines the dual roles of matrix metalloproteinases (MMPs), a family of proteolytic enzymes, in promoting both early tissue damage and fostering wound healing in the injured spinal cord. We will focus on a class of MMPs, the gelatinases, which are expressed in the spinal cord and are upregulated in response to spinal cord injury. MMP-9/gelatinase B is dramatically increased in the acutely injured cord and promotes disruption of the blood-spinal cord barrier and neutrophil infiltration. We hypothesize that MMP-9, produced by infiltrating leukocytes, disrupts the barrier and promotes early inflammation by degrading substrates critical to the integrity of the barrier and by inactivating alpha1-protease inhibitor, the inhibitor to neutrophil elastase. The end results are transient barrier dysfunction and tissue damage, resulting in part from the uncontrolled proteolytic activity of neutrophil elastase. MMP-2/gelatinase A, unlike MMP-9, is not actively expressed in the acutely injury spinal cord. Rather, MMP-2 activity is most prominent between 7 and 14 days post injury, a period corresponding to revascularization and glial scar formation. We hypothesize that MMP-2 modulates angiogenesis and glial scar formation and thus defines an environment that influences both axonal plasticity and functional recovery. To test these hypotheses, we will use a reproducible model of spinal cord contusion injury and several strategies for modulating MMP and neutrophil elastase activity. We will compare barrier permeability and inflammation in spinal cord injured mice with null mutations in MMP-9 and neutrophil elastase to injured mice that express these proteases. Reconstitution studies will be used to determine the extent to which MMP-9 expressing leukocytes disrupt the barrier, infiltrate the cord, and promote early tissue damage. /n vivo studies and in vitro bioassays will be used to compare wound healing including angiogenesis, glial scar formation, and axonal sparing/plasticity in spinal cord injured MMP-2 null mice and wildtype littermates.

描述（由申请人提供）：受伤的脊髓暴露于早期屏障破坏和炎​​症以及复杂的修复过程中，这些过程共同定义了影响轴突可塑性并控制功能恢复程度的环境地形。该提案研究了基质金属蛋白酶（MMP）（一种蛋白水解酶家族）在促进早期组织损伤和促进受伤脊髓伤口愈合方面的双重作用。我们将重点关注一类 MMP，即明胶酶，它们在脊髓中表达，并在脊髓损伤时上调。 MMP-9/明胶酶 B 在急性损伤的脊髓中显着增加，并促进血脊髓屏障的破坏和中性粒细胞浸润。我们假设，浸润白细胞产生的 MMP-9 会破坏屏障，并通过降解对屏障完整性至关重要的底物以及灭活 α1 蛋白酶抑制剂（中性粒细胞弹性蛋白酶抑制剂）来促进早期炎症。最终结果是短暂的屏障功能障碍和组织损伤，部分原因是中性粒细胞弹性蛋白酶的蛋白水解活性不受控制。 与 MMP-9 不同，MMP-2/明胶酶 A 在急性损伤的脊髓中不活跃表达。相反，MMP-2 活性在损伤后 7 至 14 天期间最为突出，这一时期对应于血运重建和神经胶质疤痕形成。我们假设 MMP-2 调节血管生成和神经胶质疤痕形成，从而定义一个影响轴突可塑性和功能恢复的环境。 为了检验这些假设，我们将使用可重复的脊髓挫伤模型和几种调节 MMP 和中性粒细胞弹性蛋白酶活性的策略。我们将比较 MMP-9 和中性粒细胞弹性蛋白酶无效突变的脊髓损伤小鼠与表达这些蛋白酶的损伤小鼠的屏障通透性和炎症。重建研究将用于确定表达 MMP-9 的白细胞破坏屏障、浸润脊髓和促进早期组织损伤的程度。体内研究和体外生物测定将用于比较脊髓损伤的 MMP-2 缺失小鼠和野生型同窝小鼠的伤口愈合，包括血管生成、神经胶质疤痕形成和轴突保留/可塑性。