Molecular Control of Gut Permeability in Trauma

描述（由申请人提供）： 创伤引起的炎症和多器官功能衰竭是美国军人和退伍军人死亡和发病的主要原因。肠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展中起关键作用。肠通透性反应烧伤，一种主要形式的创伤，尚未得到很好的表征，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漏的细胞特异性机制。我们建议表征烧伤引起的肠微血管内皮细胞和粘膜上皮细胞通透性增高的分子基础。待检验的假设是肠微循环中的炎症诱导内皮细胞旁渗漏和中性粒细胞浸润到固有层中，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（内皮和上皮细胞中表达的非肌肉肌球蛋白轻链激酶）触发的细胞骨架收缩。本研究的具体目标是：1）描述热损伤中肠道屏障调节的病理生理学特征，2）阐明肠道通透性增高的分子机制。研究设计采用了体内、离体和体外模型，这些模型将分子和遗传方法纳入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，能够区分内皮屏障和上皮屏障功能。本研究的意义在于可能建立一个新的分子途径调节紧密连接和粘附连接。本研究的数据将有助于胃肠道手术的发展，并对创伤和烧伤患者肠道屏障损伤的有效治疗或手术干预的发展产生影响。

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.