Molecular Biology of Hemorrhagic Shock

描述（由申请人提供）：创伤是这个国家54岁以下人群死亡的主要原因。除了严重的头部损伤外，出血/组织创伤及其后果是这些通常是年轻健康个体发病和死亡的最重要原因。本中心拨款提案旨在促进我们对创伤和出血后导致器官损伤和功能障碍的分子机制的理解。我们的重点是导致炎症反应的激活和传播的事件，认为炎症反应的大小是损伤后早期器官损伤/功能障碍和延迟免疫功能障碍的主要决定因素。因此，了解这些刺激事件不仅可以有效地限制早期器官损伤，还可以限制晚期败血症和多器官衰竭（MOF）的易感性。我们认为，了解失血性休克导致的器官损伤的关键之一是表征创伤事件后导致炎症变化开始和传播的最早分子事件。从之前的资助周期来看，我们知道炎症和应激信号的启动在休克诱导后很快发生，这些反应的放大涉及一系列重叠事件。我们最近对近端步骤的研究提供了令人信服的证据，表明先天免疫系统（toll样受体）的模式识别受体（PRR）在损伤后早期参与，并启动和驱动炎症反应。TLR4和TLR9是激活炎症信号所必需的，而TLR2和TLR4是明显不受调节的，如果被微生物配体触发，可以诱导过度的炎症反应。我们PI的数据显示了TLR2和TLR9的组织特异性表达和功能模式。TLR信号的内源性激活因子被称为损伤相关分子模式（DAMP）分子，似乎可以驱动TLR4和TLR9的初始激活。核蛋白高迁移率组盒-1 （HMGB1）显然参与了这一过程，并作为一个原型的例子

DESCRIPTION (provided by applicant): Trauma is the leading cause of death in this country in people under the age of 54 years. Except for major head injury, hemorrhage/tissue trauma and its consequences are the most important causes of morbidity and mortality in these often young, otherwise healthy individuals. This Center Grant proposal seeks to advance our understanding of the molecular mechanisms leading to organ injury and dysfunction following trauma and hemorrhage. Our focus is on the events leading to the activation and propagation of inflammatory response with the view that the magnitude of the inflammatory response is the primary determinant of both early organ damage/dysfunction and delayed immune dysfunction following injury. Thus, understanding the inciting events could lead to effective approaches to limit not only the early organ damage but also the susceptibility to late sepsis and multiple organ failure (MOF). We propose that one of the keys to understanding organ injury resulting from hemorrhagic shock is to characterize the earliest molecular events leading to the initiation and propagation of inflammatory changes following the traumatic event. From previous funding cycles, we know that the initiation of inflammatory and stress signaling occurs quickly after the induction of shock and that the amplification of these responses involves a series of overlapping events. Our most recent efforts to identify the proximal steps have provided compelling evidence that pattern recognition receptors (PRR) of the innate immune system (Toll-like receptors) are engaged early following injury and both initiate and drive the inflammatory response. TLR4 and TLR9 are required for the activation of inflammatory signaling, while TLR2 and TLR4 are markedly unregulated and can induce an exaggerated inflammatory response if triggered by microbial ligands. Data from our PI's indicate tissue-specific expression and function patterns for TLR2 and TLR9. Endogenous activators of TLR signaling known as Damage-Associated Molecular Pattern (DAMP) molecules appear to drive the initial activation of TLR4 and TLR9. The nuclear protein high mobility group box-1 (HMGB1) is clearly involved in this process, and serves as an example of a prototypic DAMP in our trauma models. Thus, the danger signaling exemplified by the DAMP-PRR interaction represents a paradigm for the activation of the immune system post-injury. Much of the downstream signaling and organ response follows downstream from these initiating events. Our mechanism-driven approach has proven useful to identify some of the key pathways and mediators. However, as the quantity of information has expanded, we have recognized the need to integrate this information via a series of mathematical models that predict the relationship among key events. Constant refinement of these models will come from the incorporation of new experimental data and validation of experimental data in the clinical setting. Ultimately, these models guide the generation of new hypotheses. Just as the early molecular signaling events in trauma and shock are highly integrated, so is our research approach. Each of the five projects pursues a defined aspect of the host response to trauma and shock. All of the projects are integrated through well-established collaborative channels and co-reliance on three well-organized cores. Project I (Billiar) pursues the mechanisms involved in the activation of the systemic and hepatic inflammatory response emphasizing the roles of TLR4, TLR9, and HMGB1. Project II (Hackam) explores the roles of TLR4 and TLR9 in the dysfunction and damage to the Gl mucosa. Project III (Bauer) studies the mediators leading to gut motor function failure. This project explores the consequences of TLR2 upregulation on intestinal motility changes. Project IV (Fan) examines the pathways leading to the activation of the inflammasome post-injury, with a particular emphasis on TLR4 and HMGB1 in this process. Project V (Vodovotz/Ochoa) integrates the experimental findings into mathematical models of the injury response. Project V also links projects l-VI with the clinical side by gathering clinical data on trauma patients for incorporation into our most translational mathematical model, used for simulated clinical trials of promising therapies as well as for patient-specific outcome prediction. These collaborations and the overall goal of the center will be promoted significantly by the common use of three well-organized cores. The Animal Models Core (Core B) will provide a source of tissues from animals (primarily mice) subjected to standardized protocols of hemorrhagic shock and hemorrhage with tissue trauma under the supervision of technically experienced core personnel. This approach maintains consistency of the models between the projects and permits a detailed comparison of results. The Structural Imaging Core (Core C) will provide extraordinary expertise in state-of-the-art tissue imaging, including immunohistochemistry, confocal microscopy, electron microscopy, quantitative morphology, and in situ hybridization. Since each of the projects tests an individual hypothesis that seeks to identify the molecular events in tissues in hemorrhagic or traumatic shock, efficient and accurate structural imaging to localize these changes is essential to each investigator. The Administrative Core (Core A) will provide the critical organization needed to assure productive collaboration and communication. Based on our progress thus far, we are fully confident that our approach will continue to lead to productive collaboration and effective testing of a novel and important hypotheses.