Pathogenesis and Treatment of Experimental Peritonitis

描述（由申请方提供）：肠上皮是一种高度组织化的选择性屏障，可防止胃肠道内细菌进入。腹膜炎可导致肠道屏障受损，导致病原体移位穿过肠粘膜，导致全身性炎症恶化并建立炎症引起的上皮损伤的恶性循环。了解腹膜炎、脓毒症等肠屏障功能障碍的发病机制是外科研究的重要目标之一。炎症性肠屏障功能衰竭的机制知之甚少。环氧合酶-2（考克斯-2）的表达及其产物前列腺素E2（PGE 2）的积累是肠道炎症的关键事件。PGE 2通过其同源受体（EP 1-EP 4）发出信号，引发过多的反应，包括增加局部血液供应，发热和疼痛。PGE 2通过EP 1信号传导的结果之一是从细胞内储存的Ca 2+动员。已知Ca 2+激活肌球蛋白轻链激酶（MLCK），导致MLC磷酸化和肌动球蛋白收缩性。在多种上皮细胞中，MLC磷酸化导致密封细胞边界的紧密连接（TJ）的破坏。我们已经确定PGE 2导致Caco-2单层跨上皮电阻（TEER）的显著降低，并且这种作用由EP 1、磷脂酶C（PLC）、Ca 2+和MLCK介导。我们假设腹膜炎期间肠屏障的破坏涉及肠上皮中考克斯-2的表达、PGE 2的积累以及PGE 2通过EP 1-PLC-Ca 2 +-MLCK诱导的TJ破坏。我们提出三个具体目标：1。明确考克斯-2、PGE 2和EP 1信号在腹膜炎肠屏障功能障碍中的作用。2.探讨前列腺素E2诱导考克斯-2表达的机制。3.测试考克斯-2靶向治疗，旨在保护实验性腹膜炎期间的肠道屏障。这项研究将产生相当大的洞察考克斯-2和PGE 2在肠道屏障功能衰竭的发病机制中的作用，并帮助设计新的治疗方法，以维持肠道屏障的完整性，在全身炎症。 公共卫生相关性：肠道屏障功能障碍影响着数十万患有各种急性和慢性炎症性疾病的患者。如果不了解炎症性肠屏障衰竭的机制，就不能开发屏障支持治疗。我们建议阐明炎症性前列腺素E2（PGE 2）在实验性腹膜炎屏障功能障碍的作用。本研究的结果将有助于设计在腹膜炎、休克和脓毒症条件下的新屏障维持。

DESCRIPTION (provided by applicant): The intestinal epithelium is a highly organized selective barrier that prevents the entry of luminal bacteria from the GI tract. Peritonitis can lead to impairment of the gut barrier resulting in translocation of pathogens across the intestinal mucosa, leading exacerbation of the systemic inflammation and establishment a vicious cycle of inflammation-inflicted epithelial damage. Understanding the pathogenesis of gut barrier dysfunction in peritonitis, sepsis, etc, is one of the most important goals in surgical research. The mechanisms of inflammatory gut barrier failure are poorly understood. Expression of cyclooxygenase-2 (COX-2) and accumulation of its product prostaglandin E2 (PGE2) are critical events in the intestinal inflammation. PGE2 signals through its cognate receptors (EP1-EP4) to elicit a plethora of responses including increased local blood supply, fever and pain. One of the consequences of PGE2 signaling via EP1 is Ca2+ mobilization from the intracellular stores. It is known that Ca2+ activates myosin light chain kinase (MLCK), leading to MLC phosphorylation and actomyosin contractility. In a variety of epithelial cells, MLC phosphorylation causes disruption of tight junctions (TJ) that seal the cell borders. We have established that PGE2 causes dramatic decrease of transepithelial electric resistance (TEER) in Caco-2 monolayers, and that this effect is mediated by EP1, phospholipase C (PLC), Ca2+, and MLCK. We hypothesize that gut barrier breakdown during peritonitis involves expression of COX-2 in the intestinal epithelium, accumulation of PGE2, and PGE2-induced disruption of TJ via EP1-PLC-Ca2+-MLCK. We propose 3 specific aims: 1. To define the roles of COX-2, PGE2, and EP1 signaling in gut barrier failure during peritonitis. 2. To elucidate the mechanism of COX-2 induction by PGE2. 3. To test COX-2-targeting therapies aimed at protecting the gut barrier during experimental peritonitis. This study will yield considerable insight into the role of COX-2 and PGE2 in the pathogenesis of gut barrier failure and help design novel therapies to maintain gut barrier integrity during systemic inflammation. PUBLIC HEALTH RELEVANCE: Gut barrier failure affects hundreds of thousands of patients with a variety of acute and chronic inflammatory disorders. Barrier support treatments cannot be developed without understanding the mechanisms of inflammatory gut barrier failure. We propose to elucidate the role of inflammatory prostaglandin E2 (PGE2) in barrier dysfunction during experimental peritonitis. Results of this study will help to design new barrier maintenance under conditions of peritonitis, shock, and sepsis.