tPA in traumatic brain injury

描述(由申请人提供)：创伤性脑损伤(TBI)仍然是导致死亡和长期发病的主要原因。脑水肿是重型颅脑损伤的常见和不祥的后遗症，它是由于受影响区域的血脑屏障(BBB)完整性丧失和出血引起的。这一应用是基于最近的数据，该数据显示tPA-/-小鼠在脑损伤后相对免受脑水肿和皮质坏死的影响，我们发现tPA直接或间接地增加血脑屏障通透性，方法是通过纤溶外机制诱导血管松弛，涉及通过低密度脂蛋白相关受体(LRP)和整合素avb3的信号转导。在这里，我们建议研究tPA的超纤溶活性如何调节实验性脑外伤的血脑屏障通透性、血管松弛、脑水肿和神经预后。我们的方法包括对tPA介导的信号转导机制的基础研究，使用拮抗剂和tPA变体，通过三个相互关联的特定目标来分离其血管活性和催化特性。在具体目标1中，我们将研究avb3和LRP之间形成复合物所需的分子决定因素，以及tPA破坏这些复合物并诱导血脑屏障通透性和血管松弛的机制。在具体目标2中，将通过分离tPA的纤溶和信号转导活性的方法来阐明血管内血栓形成在创伤后脑损伤发展中的作用。在具体目标3中，将在野生型和tPA-/-小鼠身上检测拮抗剂对在脑外伤后遗症中选择性缺乏纤溶或超纤溶功能的LRP和avb3和tPA变体的影响。此外，一种将tPA输送到创伤血管的新方法将使用表达血小板tPA的转基因小鼠进行评估。总之，这些研究将提供对tPA在介导中枢神经系统损伤中的作用的新的理解，以及可能改善临床结果的新的细胞靶点和新的tPA制剂。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) remains a major cause of death and long-term morbidity. Cerebral edema is a common and ominous sequel of severe TBI which results from loss of blood-brain-barrier (BBB) integrity and hemorrhage in the affected zone. This application is predicated on recent data showing that tPA-/- mice are relatively protected from developing cerebral edema and cortical necrosis after TBI and our finding that tPA increases BBB permeability both directly and indirectly by inducing vasorelaxation through extra-fibrinolytic mechanisms that involve signal transduction through the low density lipoprotein related receptor (LRP) and the integrin avb3. Here, we propose to study how the extra-fibrinolytic activities of tPA modulate BBB permeability, vasorelexation, cerebral edema and neurological outcome in experimental TBI. Our approach includes basic research into the mechanism of tPA-mediated signal transduction using antagonists and tPA variants that dissociate its vasoactive and catalytic properties through three inter-related specific aims. In Specific Aim 1 we will study the molecular determinants required to form complexes between avb3 and LRP and mechanism by which tPA disrupts these complexes and induces BBB permeability and vasorelaxation. In Specific Aim 2 the effect of intravascular thrombosis on the development of post-traumatic brain injury will be elucidated using approaches to isolate the fibrinolytic and signal transduction activities of tPA. In Specific Aim 3 the effect of antagonists to LRP and avb3 and tPA variants selectively lacking fibrinolytic or extra-fibrinolytic function in the sequelae of TBI will be examined in wild type and tPA-/- mice. Also, a new approach to deliver tPA to traumatized vessels will be evaluated using platelet-tPA expressing transgenic mice. Together, these studies will provide new understanding of the role of tPA in mediating CNS injury and novel cellular targets and new formulations of tPA that may improve clinical outcome.