Molecular Control of Gut Permeability in Trauma

描述(由申请人提供)： 摘要创伤引起的炎症和多器官衰竭是美国士兵和退伍军人死亡和发病的主要原因。肠道屏障功能障碍通过提供血浆渗漏和细菌移位的主要部位，在创伤后并发症的发生中起关键作用。烧伤是一种主要的创伤形式，其对肠道通透性的反应尚未得到很好的描述，其细胞和分子机制仍然知之甚少。本研究的目的是阐明热损伤时肠道渗漏的细胞特异性机制。我们建议对烧伤引起的肠道微血管内皮细胞和粘膜上皮高通透性的分子基础进行研究。需要检验的假设是，肠道微循环中的炎症导致内皮细胞旁渗漏和中性粒细胞渗入固有层，导致粘膜屏障失效。其潜在机制涉及细胞-细胞连接的动态重塑，以及由nmMLCK引发的细胞骨架收缩。nmMLCK是一种在内皮细胞和上皮细胞中表达的非肌肉肌球蛋白轻链激酶。本研究的具体目的是：1)研究热损伤时肠道屏障调节的病理生理学；2)阐明肠道高通透性的分子机制。该研究设计采用了补充的体内、体外和体外模型，这些模型将分子和遗传方法结合到临床相关创伤条件下的生理实验中。该提案的一个独特之处在于，它提供了对肠道通透性的深入评估，并能够区分内皮屏障和上皮屏障的功能。这项研究的意义在于有可能建立一种新的分子途径来调节紧密连接和粘连连接。这项研究得出的数据将有助于胃肠外科的发展，并有助于开发有效的治疗方法或外科干预措施，防止创伤和烧伤患者的肠道屏障损伤。 公共卫生相关性： 创伤是美国士兵和退伍军人死亡和发病的主要原因。作为一种典型的创伤形式，热损伤是由战斗或反恐行动中的火焰/化学烧伤以及非工作相关的火灾或烫伤事故造成的。尽管重症监护和伤口管理得到了改善，但创伤后并发症仍然是一个威胁生命的问题，导致住院时间延长和费用增加。肠道在严重烧伤后多器官并发症的发生中起着重要作用。特别是，肠道屏障功能障碍是血液泄漏和细菌移位的主要部位，从而导致全身性炎症综合征和脓毒症。内脏渗漏的机制还知之甚少。本研究对烧伤引起的炎症过程中导致肠道高通透性的细胞和分子途径进行了全面的评价。这项研究工作对创伤或炎症性疾病的VA患者的肠屏障损伤的外科或医学干预措施的发展具有潜在的影响。

DESCRIPTION (provided by applicant): Abstract Trauma-induced inflammation and multiple organ failure are a major cause of mortality and morbidity in American soldiers and veterans. Gut barrier dysfunction plays a critical role in the development of posttraumatic complications by providing the major site for plasma leakage and bacterial translocation. The intestinal permeability response to burns, a major form of trauma, has not been well characterized, and its cellular and molecular mechanisms remain poorly understood. The goal of this study is to elucidate the cell-specific mechanisms of leaky guts during thermal injury. We propose to characterize the molecular basis of burn-induced hyperpermeability in the intestinal microvascular endothelium and mucosal epithelium. The hypothesis to be tested is that inflammation in the intestinal microcirculation induces endothelial paracellular leakage and neutrophil infiltration into lamina propria leading to mucosal barrier failure. The underlying mechanism involves dynamic remodeling of cell-cell junctions coupled with cytoskeleton contraction triggered by nmMLCK, the non-muscle myosin light chain kinase expressed in endothelial and epithelial cells. The specific aims developed in this proposal are: 1) to characterize the pathophysiology of gut barrier regulation in thermal injury, and 2) to elucidate the molecular mechanisms of gut hyperpermeability. The study design employs complimentary in vivo, ex vivo, and in vitro models that incorporate molecular and genetic approaches into physiological experiments under clinically relevant trauma conditions. A unique aspect of the proposal is that it provides an in-depth evaluation of gut permeability with the ability to discern the endothelial barrier from epithelial barrier function. The significance of this study lies in the potential to establish a new molecular pathway in the regulation of tight and adherens junctions. Data derived from this study would contribute to the advancement of gastrointestinal surgery with implications in the development of effective therapies or surgical interventions against gut barrier injury in patients with trauma and burns. PUBLIC HEALTH RELEVANCE: VA Relevance Trauma is a major cause of mortality and morbidity in American soldiers and veterans. As a typical form of trauma, thermal injury results from flame/chemical burns in combat or anti-terrorist actions as well as from non- work related fire or scald accidents. Despite the improved critical care and wound management, posttraumatic complications remain a life-threatening problem that causes extended hospital stay and charges. The gut plays an important role in the development of multiple organ complications following a severe burn. In particular, gut barrier failure contributes to systemic inflammatory syndrome and sepsis by serving as the major site of blood leakage and bacteria translocation. The mechanisms of leaky guts are poorly understood. This study provides a comprehensive evaluation of the cellular and molecular pathways leading to intestinal hyperpermeability during burn-induced inflammation. The research work has potential impact on the development of surgical or medical interventions against gut barrier injury in VA patients with trauma or inflammatory diseases.