Trauma to developing brain-injury and repair mechanisms

创伤导致脑损伤和修复机制的发展

• 批准号: 8064528
• 负责人: LINDA J. NOBLE
• 金额: $ 49.92万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8064528
• 关键词: Acute; Address; Adoptive Transfer; Adult; Age; Animals; Basal lamina; Behavioral; Behavioral Assay; Biological Assay; Blood - brain barrier anatomy; Blood Vessels; Brain; Brain Injuries; Cause of Death; Cessation of life; Child; Childhood Injury; Clinical Research; Cognitive; Cognitive deficits; Complement; Corpus Callosum; Coupled; Data; Demyelinations; Development; Environment; Event; Extracellular Matrix; Family; Flow Cytometry; Foundations; Functional disorder; Gelatin; Gelatin Zymography; Gelatinase B; Gelatinases; Genetic; Hippocampus (Brain); Impaired cognition; Inflammation; Inflammatory Response; Injury; Interstitial Collagenase; Knockout Mice; Leukocyte Elastase; Leukocytes; Magnetic Resonance Imaging; Matrix Metalloproteinases; Mediating; Mediator of activation protein; Modeling; Morbidity - disease rate; Morphogenesis; Mus; Neurological status; Neuronal Injury; Neurons; Neutrophil Infiltration; Outcome; Pathogenesis; Pattern; Peptide Hydrolases; Permeability; Physiological; Process; Protease Inhibitor; Proteins; Proteolysis; Rattus; Recovery; Recovery of Function; Resistance; SB 3CT compound; Signal Transduction; Structure; Techniques; Testing; Tight Junctions; Time; Tissues; Tracer; Transgenic Mice; Trauma; Traumatic Brain Injury; Up-Regulation; Western Blotting; base; behavior measurement; brain volume; cell injury; clinically relevant; cognitive recovery; disability; improved; indexing; inhibitor/antagonist; injured; injury and repair; member; nerve injury; neuroprotection; neutrophil; neutrophil elastase inhibitor; null mutation; overexpression; postnatal; repaired; response to injury; social skills; therapeutic target; white matter damage

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) in children is the leading cause of death and disability. Although clinical studies have shown that the developing brain is particularly vulnerable to injury, the basis for this vulnerability remains unclear. Here we will determine if matrix metalloproteinase (MMP)-9 is a key initiator of early tissue damage and that modulation of its activity will confer early neuroprotection and establish an environment that is favorable to brain development and cognitive recovery. The gelatinase MMP-9 is a member of the MMP family of proteolytic enzymes that are secreted in an inactive form and are activated in the extracellular matrix (ECM) by a variety of mechanisms. While MMPs are critical for normal brain functioning, excessive and uncontrolled activity leads to dysregulated proteolysis, culminating in cell injury/death. Here we will determine if MMP-9 initiates an early self-perpetuating injury response that is coupled to activity of neutrophil elastase and neutrophil infiltration. We hypothesize that MMP-9 mediates early tissue damage by inactivating a1-protease inhibitor, the primary physiologic inhibitor of neutrophil elastase, thus supporting neutrophil elastase-mediated neuronal injury and furthering leukocyte recruitment. Using complimentary pharmacologic and genetic strategies, together with adoptive transfer, we will examine the cooperativity between MMP-9 and neutrophil elastase in signaling neutrophil recruitment and mediating early cell injury. Aim 1 will test the hypothesis that elevated MMP-9 contributes to disruption of the blood-brain barrier, neural injury, and white matter damage. Aim 2 will test the hypothesis that MMP-9, conveyed by infiltrating neutrophils, promotes disruption of the blood-brain barrier. Aim 3 will determine if MMP-9 inactivates a1-protease inhibitor, an inhibitor of neutrophil elastase, thus allowing neutrophil elastase to produce tissue injury and further neutrophil recruitment. Aim 4 will test the hypothesis that blockade of early gelatinase activity in the acutely injured brain will result in long-term structural and behavioral recovery. To test these hypotheses we will use a murine model of TBI at postnatal day 21 and several strategies to modulate MMP-9 and neutrophil elastase activity. We will compare early indices of tissue damage including barrier dysfunction in brain injured wildtype (WT) mice to transgenic mice with a null mutation in MMP-9 or overexpress tissue inhibitor of matrix metalloproteinase-1. The interdependency of MMP-9 and neutrophil elastase in initiating a self-perpetuating injury response will be examined using adoptive transfer techniques in WT and MMP-9 and neutrophil elastase null animals. With state-of-the-art magnetic resonance imaging and a comprehensive battery of behavioral assays, we will further determine if early pharmacologic blockage of gelatinase activity supports structural recovery and improves long-term cognitive outcomes. Together, these studies provide an important foundation for understanding the unique vulnerability of the young brain to TBI and for developing the most appropriate therapies for the brain-injured child. PUBLIC HEALTH RELEVANCE: Although traumatic brain injury (TBI) is the most frequent cause of acquired brain injury and morbidity in children and adversely impacts cognitive development, there has been little progress toward understanding how best to support recovery processes. Using genetic and pharmacologic approaches in a murine model of TBI, we will determine how unchecked, matrix metalloproteinase (MMP)-9 directed proteolysis establishes an environment that is unfavorable to recovery and if early blockade of this activity supports cognitive recovery. These studies establish the basis for developing a MMP-targeted therapeutic for the brain-injured child.

描述（由申请人提供）：儿童创伤性脑损伤（TBI）是导致死亡和残疾的主要原因。尽管临床研究表明发育中的大脑特别容易受到伤害，但这种脆弱性的基础仍不清楚。在这里，我们将确定基质金属蛋白酶 (MMP)-9 是否是早期组织损伤的关键引发剂，对其活性的调节将赋予早期神经保护作用，并建立有利于大脑发育和认知恢复的环境。明胶酶 MMP-9 是蛋白水解酶 MMP 家族的成员，以非活性形式分泌，并通过多种机制在细胞外基质 (ECM) 中激活。虽然 MMP 对正常大脑功能至关重要，但过度和不受控制的活动会导致蛋白水解失调，最终导致细胞损伤/死亡。在这里，我们将确定 MMP-9 是否启动早期自我持续性损伤反应，该反应与中性粒细胞弹性蛋白酶的活性和中性粒细胞浸润相关。我们假设 MMP-9 通过灭活α1-蛋白酶抑制剂（中性粒细胞弹性蛋白酶的主要生理抑制剂）介导早期组织损伤，从而支持中性粒细胞弹性蛋白酶介导的神经元损伤并进一步促进白细胞募集。使用互补的药理学和遗传策略，以及过继转移，我们将检查 MMP-9 和中性粒细胞弹性蛋白酶在中性粒细胞募集信号和介导早期细胞损伤中的协同作用。目标 1 将检验以下假设：MMP-9 升高会导致血脑屏障破坏、神经损伤和白质损伤。目标 2 将检验以下假设：由浸润性中性粒细胞传递的 MMP-9 会促进血脑屏障的破坏。目标 3 将确定 MMP-9 是否会使 α1-蛋白酶抑制剂（一种中性粒细胞弹性蛋白酶抑制剂）失活，从而使中性粒细胞弹性蛋白酶产生组织损伤并进一步招募中性粒细胞。目标 4 将检验以下假设：阻断急性损伤大脑中的早期明胶酶活性将导致长期结构和行为恢复。为了检验这些假设，我们将使用出生后第 21 天的 TBI 小鼠模型以及几种调节 MMP-9 和中性粒细胞弹性蛋白酶活性的策略。我们将比较早期组织损伤指标，包括脑损伤野生型 (WT) 小鼠的屏障功能障碍与 MMP-9 无效突变或过表达基质金属蛋白酶-1 组织抑制剂的转基因小鼠。将使用过继转移技术在 WT 和 MMP-9 以及中性粒细胞弹性蛋白酶无效动物中检查 MMP-9 和中性粒细胞弹性蛋白酶在启动自我持续损伤反应中的相互依赖性。借助最先进的磁共振成像和全面的行为分析，我们将进一步确定明胶酶活性的早期药理学阻断是否支持结构恢复并改善长期认知结果。总之，这些研究为了解年轻大脑对 TBI 的独特脆弱性以及为脑损伤儿童开发最合适的治疗方法提供了重要基础。 公共健康相关性：尽管创伤性脑损伤 (TBI) 是儿童获得性脑损伤和发病的最常见原因，并对认知发展产生不利影响，但在了解如何最好地支持康复过程方面进展甚微。在 TBI 小鼠模型中使用遗传和药理学方法，我们将确定未经检查的基质金属蛋白酶 (MMP)-9 定向蛋白水解如何建立不利于恢复的环境，以及早期阻断这种活动是否支持认知恢复。这些研究为开发针对脑损伤儿童的 MMP 靶向疗法奠定了基础。