Surgical Studies of Gut Permeability

摘要 保护性肠粘膜屏障是一个专门的领域，对 与不同的腔内有害物质和微生物群相互作用。急性肠胃病 屏障功能障碍通常发生在患有严重外科疾病的患者中，例如 创伤、热损伤、败血症、休克、大手术和缺血 后处理。肠屏障功能障碍导致肠毒素移位 物质和细菌进入血流，在某些情况下，会导致多个 器官功能障碍综合征(MODS)和死亡。保护肠道的有效疗法 屏障的完整性有限，因为对急性肠道的机制知之甚少。 各种危重手术条件下的屏障功能障碍。最近，细胞间串扰 在细胞外小泡(EVS)分泌的指导下，EVS已经获得了越来越多的 请注意。EV从多种细胞类型释放，包括肠上皮细胞(IECS)， 可以将各种生物活性分子转移到邻近或远处的组织，因此 扮演以前未被认识到的职能角色。这次竞争性更新的目标是 应用是确定肠道病毒非编码RNA(NcRNAs)在肠道病毒感染中的作用和机制。 危重手术条件下肠屏障功能的控制 一系列多学科的研究。我们的初步数据显示， 非编码库RNAs(VtRNAs)是由发布的EV中存在的关键转录 脓毒症患者和小鼠肠道病毒vtRNAs水平升高 暴露在败血症压力下。异位表达的vtRNAs可降低TECH的水平 并破坏肠道屏障功能。携带母体基因缺失的小鼠 H19基因的外显子1(H19-/-)表现出诱导的自噬和减少释放 脓毒症应激后vtRNA丰富的EVS。基于这些令人兴奋的观察，我们 现在提出了范式转换假说，即电动汽车中的vtRNAs由IECS在 对严重手术应激的反应在急性胰腺炎的发病机制中起重要作用 肠屏障功能障碍，EV从IECS释放受长ncRNA严格调控 H19和RNA结合蛋白HUR通过自噬。提出了三个具体目标来 检验假设：1)定义由以下因素产生的电动汽车的vtRNA货物的角色 人肠细胞在危重手术中对肠屏障功能的调节 应激；2)确定在EV vtRNAs中起重要作用的新靶点 关键手术应激反应的肠上皮屏障功能障碍；以及3) 检测H19和HUR是否通过改变H19和HUR对IECS中富含vtRNA的EV的形成进行调节 自噬。完成这些具体目标将揭示新的机制 危重病患者急性肠屏障功能障碍的发病机制 外科疾病。它还将提供开发新的生物标记物所需的信息 恶化的急性肠道屏障功能障碍和/或MODS，并有针对性地发展 治疗以保护肠道屏障的完整性。

Abstract The protective intestinal mucosal barrier is a specialized domain responding to and interacting with different luminal noxious substances and the microbiome. Acute gut barrier dysfunction occurs commonly in patients with critical surgical disorders such as trauma, thermal injury, sepsis, shock, massive surgical operations, and ischemic postconditioning. Gut barrier dysfunction leads to the translocation of luminal toxic substances and bacteria to the blood stream and, in some instances, results in multiple organ dysfunction syndrome (MODS) and death. Effective therapies to preserve gut barrier integrity are limited, because of poorly understood mechanisms of acute gut barrier dysfunction in various critical surgical conditions. Recently, intercellular crosstalk directed by the secretion of extracellular vesicles (EVs) has been gaining increasing attention. EVs released from many cell types, including intestinal epithelial cells (IECs), can transfer a variety of bioactive molecules to neighboring or distant tissues and hence play previously unrecognized functional roles. The goal of this competitive renewal application is to determine the role and mechanism of EV noncoding RNAs (ncRNAs) in the control of intestinal barrier function under critical surgical conditions by carrying out a series of multi-disciplinary studies. Our preliminary data indicate that the small noncoding vault RNASs (vtRNAs) are critical transcripts present in EVs released from IECs, and that the levels of EV vtRNAs increase in patients with sepsis and mice exposed to septic stress. Ectopically expressed vtRNAs decrease the levels of tight junctions and disrupt the intestinal barrier function. Mice bearing a maternal deletion of exon 1 in the H19 gene (H19-/-) exhibit induced autophagy and decreased release of vtRNA-enriched EVs after septic stress. Building on these exciting observations, we now propose the paradigm-shifting hypothesis that vtRNAs in EVs secreted by IECs in response to critical surgical stress play an important role in the pathogenesis of acute gut barrier dysfunction, and that EV release from IECs is tightly regulated by long ncRNA H19 and RNA-binding protein HuR via autophagy. Three specific aims are proposed to test the hypothesis: 1) to define the roles of the vtRNA cargo of EVs generated from human enterocytes in the regulation of intestinal barrier function during critical surgical stress; 2) to identify novel targets of EV vtRNAs that play an important role in triggering intestinal epithelial barrier dysfunction in response to critical surgical stress; and 3) to test if H19 and HuR regulate the formation of vtRNA-rich EVs in IECs by altering autophagy. Completion of these specific aims will uncover novel mechanisms underlying the pathogenesis of acute gut barrier dysfunction in patients with critical surgical disorders. It will also shed information needed to develop new biomarkers for deteriorating acute gut barrier dysfunction and/or MODS and to develop targeted therapeutics to preserve gut barrier integrity.