Extracellular Matrix Mediates Axonal Integrity Following Brain Trauma

细胞外基质介导脑外伤后轴突的完整性

• 批准号: 7406059
• 负责人: Linda L. Phillips
• 金额: $ 32.59万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-15 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7406059
• 关键词: Action Potentials; Acute; Affinity; American; Animals; Antibiotics; Antiplasmin; Attenuated; Axon; Binding; Biological Assay; Biotechnology; Blood - brain barrier anatomy; Brain; Calcineurin; Caliber; Caseins; Cell Adhesion Molecules; Cells; Cognitive deficits; Confocal Microscopy; Corpus Callosum; Cyclosporine; Diagnostic Imaging; Diffuse; Diffuse Axonal Injury; Disruption; Electrons; Elevation; End Point; Enzymes; Etiology; Evolution; Exhibits; Extracellular Matrix; Extracellular Matrix Proteins; FN-439; Fiber; Fluorescence; Gel; Gelatin; Gelatinase A; Immunoprecipitation; Immunosuppressive Agents; In Situ; In Situ Hybridization; In Vitro; Injury; Integral Membrane Protein; Ireland; Ligands; Light; Link; Localized; MMP3 gene; Matrix Metalloproteinases; Mediating; Metalloproteases; Methods; Microscopic; Minocycline; Mitochondria; Modeling; Muscle fasciculation; Neuropil; Pathology; Pathway interactions; Pattern; Peptides; Phase; Physiological; Pilot Projects; Plasmin; Plasminogen; Population; Principal Investigator; Proteins; Publishing; Recovery; Research Personnel; Reverse Transcriptase Polymerase Chain Reaction; Role; Sampling; Screening procedure; Series; Slice; Standards of Weights and Measures; Stromelysin 1; Tenascin; Testing; Time; Tissue Sample; Traumatic Brain Injury; Up-Regulation; Western Blotting; axon growth; base; case control; cell type; contactin; contactins; day; enzyme activity; excitotoxicity; functional outcomes; in vivo; injured; mRNA Expression; myelination; neurofascin; neuroserpin; novel therapeutics; phosphacan; programs; protein distribution; protein expression; research study; response; therapeutic target; treatment effect; white matter; white matter damage; white matter injury

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) results in long term debilitation for millions of Americans. A consistent feature of this pathology is traumatic axonal injury (TAI), diffuse in profile and challenging to study. To date, TAI etiology is best documented in large caliber, myelinated axons, which consistently exhibit plasmalemmal, cytoskeletal and mitochondria! pathology. From diagnostic imaging it is clear that the corpus callosum and other subcortical white matter tracts are vulnerable to TAI. These pathways contain both large myelinated and small unmyelinated axons, where fiber type is systematically associated with sensorimotor and associative cortices. Given that TBI induces long-term cognitive deficits, and that TAI in subcortical white matter is poorly understood, our recently published studies have explored the physiological and morphological response of corpus callosum axons to diffuse TBI. Those results show rapid evolution of TAI and greater vulnerability of unmyelinated fibers. In parallel, pilot studies we also find upregulation of extracellular matrix (ECM) proteins and their regulatory metalloproteinases (MMPs) with callosal TAI. Such observations are consistent with the fact that these proteins mediate axonal growth, myelination and fasciculation. Based upon this information, we propose to explore the role of MMP/ECM pathways during degenerative and recovery phases of TAI. We will test the hypothesis that MMP/ECM proteins influence the progression of white matter TAI following TBI and that their activation is regulated by fibrinolytic proteins which permeate the neuropil through breaches in the blood brain barrier. Using the callosal TAI model, we will document protein/mRNA expression of tenascin and phosphacan, ECM proteins known to be present in white matter, and MMPs 2, 3 and 9, known to modify ECM after injury. Temporal profile of MMP activity will be correlated with enzyme expression and screening for adhesion molecule binding partners of these proteins will be performed. Next, we will similarly assess the response of fibrinolytic pathway proteins tPA and plasminogen to callosal TAI. Finally, we will pharmacologically manipulate either fibrinolytic/MMP enzyme activity or degree of axonal protection after injury and test for cause/effect relationships between fibrinolytic/MMP molecules and axonal integrity using functional and morphological endpoints. These studies will establish the role of MMP/ECM proteins in TAI and provide new therapeutic targets forTBI.

描述(申请人提供)：创伤性脑损伤(TBI)导致数百万美国人长期虚弱。这种病理的一贯特征是创伤性轴索损伤(TAI)，呈弥漫性，研究具有挑战性。到目前为止，TAI的病因学最好的记录是大口径的有髓轴突，这些轴突始终表现为浆膜、细胞骨架和线粒体！病理学。从诊断性成像可以清楚地看出，胼胝体和其他皮质下白质束易受TAI的影响。这些通路包括大的有髓轴突和小的无髓轴突，其中纤维类型与感觉运动和联合皮质系统地联系在一起。鉴于颅脑损伤会导致长期的认知功能障碍，而皮质下白质中的TAI又鲜为人知，我们最近发表的研究探讨了弥漫性脑损伤对胼胝体轴突的生理和形态反应。这些结果表明TAI的快速演变和无髓纤维的更大易损性。同时，我们还发现，与之平行的先导性研究还发现，膝盖骨TAI上调了细胞外基质(ECM)蛋白及其调节性金属蛋白酶(MMPs)的表达。这些观察结果与这些蛋白质介导轴突生长、髓鞘形成和束状化的事实相一致。基于这些信息，我们建议探讨基质金属蛋白酶/细胞外基质通路在TAI退行性变和恢复期的作用。我们将验证一种假设，即基质金属蛋白酶/细胞外基质蛋白影响脑损伤后白质TAI的进展，其激活受到纤溶蛋白的调节，纤溶蛋白通过血脑屏障的破坏渗透到神经膜。我们将使用膝盖骨TAI模型，记录Tenascin和Phopacan、已知存在于白质中的ECM蛋白以及已知在损伤后改变ECM的MMP2、3和9的蛋白/mRNA的表达。基质金属蛋白酶活性的时间分布将与酶的表达相关，并将进行这些蛋白质的黏附分子结合伙伴的筛选。接下来，我们将类似地评估纤溶途径蛋白tPA和纤溶酶原对膝盖骨TAI的反应。最后，我们将从药理上操纵纤溶/基质金属蛋白酶的活性或损伤后轴突保护的程度，并使用功能和形态终点测试纤溶/基质金属蛋白酶分子与轴突完整性之间的因果关系。这些研究将确定基质金属蛋白酶/细胞外基质蛋白在脑外伤中的作用，并为脑外伤提供新的治疗靶点。