Modulation of Pulmonary Vascular Permeability and Inflammation by Mesenchymal Stem Cells (MSCs) in Hemorrhagic Shock

 5失血性休克(HS)是创伤后迅速失血所致的一种疾病，其特征之一是出现全身反应，导致内皮损伤、炎症、异常凝血、组织浮肿和终末性器官损伤。HS与急性肺损伤(ALI)和急性呼吸窘迫综合征(ARDS)的高发病率有关(14-20%的ICU患者)，导致显著的发病率和死亡率。8，9 8-13除了复苏范例和支持治疗外，目前几乎没有治疗创伤中的肺水肿和ARDS的治疗方法。14间充质干细胞(MSCs)已被证明在以血管损害和炎症为特征的多种情况下具有治疗潜力。1，15-31我们的研究小组表明，IV MSCs降低了创伤性脑损伤(TBI)后的血脑屏障(BBB)通透性，并降低了HS1后的肺通透性和炎症。15骨髓间充质干细胞如何工作的机制在很大程度上是未知的。包括我们自己在内的许多小组已经证明，MSCs的有益作用是由可溶性因子介导的。4，32在我们过去的研究中，我们发现了一种由MSCs产生和诱导的可溶性因子-TIMP3(TIMP3)-它可以通过调节内皮黏附连接和血管稳定性来概括MSCs对内皮通透性的保护作用。在我们目前的研究中，我们有证据表明TIMP3可以单独调节失血性休克所致的肺血管通透性。我们的数据支持TIMP3收紧血肺血管屏障的假设。我们的总体机制假设是静脉(IV)MSCs通过产生和诱导HS后TIMP3来降低肺通透性，降低肺水肿，改善肺功能。我们假设IVTIMP3将概括IVMSCs的保护作用。我们的目标是明确MSCs在失血性休克诱导的血管通透性和炎症中的作用机制，并探讨MSC衍生蛋白TIMP3的作用和治疗潜力。目的1通过研究TIMP3和MSC介导的肺内皮细胞通透性中TIMP3的功能、结构域和信号通路，阐明TIMP3的作用机制。目的2旨在通过建立失血性休克和创伤小鼠模型，回答IV MSCs(表达和不表达TIMP3)和TIMP3是否降低HS诱导的肺通透性的问题。目的研究TIMP3和MSCs在TIMP3基因敲除小鼠中的作用。我们在这一领域的研究工作的最终长期目标是将我们的发现从床边转化为创伤的治疗选择，以减轻患者的预后。

 DESCRIPTION (provided by applicant): Traumatic injury is the leading cause of death and disability in children and adults worldwide in both civilian and military populations.5 One of the hallmarks of hemorrhagic shock (HS), a condition resulting from rapid blood loss after traumatic injury, is the onset of a systemic response that results in endothelial injury, inflammation, aberrant coagulation, tissue edema and end organ injury. HS is associated with a high incidence of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) (14-20% of ICU patients) that results in significant morbidity and mortality.8, 9 8-13 Aside from resuscitatio paradigms and supportive therapy there are currently few treatments to treat lung edema and ARDS in trauma.14 Mesenchymal stem cells (MSCs) have been shown to have therapeutic potential in multiple conditions characterized by vascular compromise, and inflammation.1, 15-31 Our group has shown that IV MSCs attenuate blood brain barrier (BBB) permeability after traumatic brain injury (TBI) and also lung permeability and inflammation after HS.1, 15 The mechanisms of how MSCs work are largely unknown. Many groups including our own have shown that the beneficial effects of MSCs are mediated by soluble factors.4, 32 In our past studies, we identified a soluble factor produced and induced by MSCs - TIMP3 (Tissue Inhibitor of Matrix Metalloproteinase-3) - that can recapitulate the protective effects of MSCs on endothelial permeability by modulating endothelial adherens junctions and vascular stability. In our current studies, we have evidence suggesting that TIMP3 can separately modulate pulmonary vascular permeability induced by hemorrhagic shock. Our data support the hypothesis that TIMP3 tightens the blood-lung vascular barrier. Our overall mechanistic hypothesis is that intravenous (IV) MSCs decrease lung permeability, lung edema and improve lung function through production and induction of TIMP3 after HS. We hypothesize that IV TIMP3 will recapitulate the protective effects of IV MSCs. It is our goal to define the mechanisms of action of MSCs in hemorrhagic shock induced vascular permeability and inflammation and to investigate the role and therapeutic potential of the MSC derived protein - TIMP3. Aim 1 is an in vitro aim that is designed to elucidate mechanisms of action of TIMP3 through investigations of function, domains and signaling pathways involved in TIMP3 and MSC mediated effects on pulmonary endothelial permeability. Aim 2 is designed to answer the question of whether IV MSCs (with and without TIMP3 expression) and TIMP3 attenuate HS induced lung permeability using an established mouse model of hemorrhagic shock and trauma. Aim 3 is designed to study the effects of TIMP3 and MSCs in the TIMP3 knock-out mouse. The final long-term goal of our research effort in this area is to translate our findings from "bench t bedside" to provide a treatment option in trauma that can mitigate patient outcomes.