The Role of Intestinal Digestive Enzymes in Circulatory Shock

描述（由申请人提供）： 休克是重症监护病房发病和死亡的常见原因，死亡率为30- 100%。VA医院受到的影响尤其严重，部分原因是许多退伍军人的高龄和合并症。导致休克和心血管崩溃的机制尚未完全了解。同样，休克幸存者的极高发病率也没有治疗方法。然而，越来越清楚的是，肠道，特别是小肠，可能是理解这种情况及其后遗症的关键。我们最近发展了一种新的假说，描述了休克的可能重要机制，发现肠中的胰腺消化酶可能起主要作用。这一发现使得通过消化酶抑制来探索潜在的新治疗成为可能。我们最近的初步证据表明，肠腔消化酶的封锁，而不是体循环，可能会取消死亡率和发病率通常在实验模型中看到的循环休克。然而，肠腔中消化酶抑制的保护机制尚不清楚。我的假设是，正常完整的刷状缘上皮屏障在休克中被破坏，允许消化酶进入间质组织，导致肠壁破坏，炎症和基本细胞功能的破坏。局部缺血、内毒素或其他损伤损害粘膜屏障，导致消化酶进入肠壁、肠的自动消化和全身循环的炎性介质的产生。我在初步研究中发现，消化酶产生的低分子量产物可能会引起炎症和休克。我的第一个具体目标提出，以确定一些代表性的炎症肽来自消化酶本身，并证明其存在和重要性，在肠道和内脏动脉闭塞（SAO）休克动物的体循环。休克长期存活的关键问题是粘膜上皮重建到其正常低渗透性状态所需的时间。没有研究涉及与缺血性肠相关的休克的长期存活率或发病率。此外，没有系统的生存研究存在肠酶封锁在SAO休克。我的第二个具体目标是通过肠内酶阻断来确定胰腺消化酶在大鼠和小鼠实验模型中SAO休克后炎症和细胞毒性介质的产生以及长期存活和发病率中的作用。我将建立休克后抢救治疗的治疗窗口，并探讨口服预处理作为休克和高危外科手术临床干预方法的可行性。我还将探讨肠粘膜蛋白酶激活受体-2（PAR-2）作为休克后发病率和死亡率的特定机制的作用。这些结果将产生关于休克发病机制的基本新知识。他们将为消化酶在肠道缺血性损伤中的作用提供新的理解，并优化治疗策略以干扰其在休克中的活性，从而导致潜在的临床应用，以降低这种情况下的发病率和死亡率。

DESCRIPTION (provided by applicant): Shock is a common cause of morbidity and mortality in the intensive care unit, with a mortality of 30-100%. VA hospitals are particularly impacted, in part secondary to the advanced age and co-morbidities of many of the veterans. The mechanisms leading to shock and cardiovascular collapse are incompletely understood. Likewise, there is no treatment for the extremely high morbidity seen in survivors of shock. However, it is becoming increasingly clear that the gut, and particular the small bowel, may be the key to understanding this condition and its sequelae. We have recently developed a new hypothesis describing possible important mechanisms in shock with the discovery that pancreatic digestive enzymes in the bowel may play a major role. This finding has enabled exploration of a potentially new treatment by digestive enzyme inhibition. We have recent initial evidence that blockade of digestive enzymes in the intestinal lumen, but not the systemic circulation, may abolish mortality and morbidity normally seen in experimental models of circulatory shock. However, the mechanisms by which digestive enzyme inhibition in the gut lumen is protective are not known. My hypothesis is that the normally intact brush border epithelial barrier is breached in shock, allowing digestive enzymes access to interstitial tissue with resulting intestinal wall destruction, inflammation and breakdown of basic cell functions. Mucosal barrier compromised by ischemia, endotoxins, or other injury, leads to entry of digestive enzymes into the intestinal wall, auto-digestion of the intestine and generation of inflammatory mediators that circulate systemically. I have found in preliminary studies that low molecular weight products generated by digestive enzymes may induce inflammation and shock. My first Specific Aim proposes to identify a number of representative inflammatory peptides derived from digestive enzymes themselves and demonstrate their presence and importance in the gut and systemic circulation of animals in splanchnic arterial occlusion (SAO) shock. A key question in long-term survival in shock is the time required for reconstitution of mucosal epithelium to its normal low permeability state. No studies have addressed long-term survival or morbidity in shock associated with an ischemic intestine. Furthermore, no systematic survival studies exist with intestinal enzyme blockade in SAO shock. My second Specific aim will determine by enzyme blockade in the intestine the role of pancreatic digestive enzymes in the generation of inflammatory and cytotoxic mediators and in long-term survival and morbidity after SAO shock in rat and mouse experimental models. I will establish a window of treatment for rescue therapy after shock and explore the feasibility of oral pre-treatment as an approach to the development of clinical intervention in shock and high-risk surgical procedures. I will also explore the role of gut mucosal protease activated receptor-2 (PAR-2) as a specific mechanism that contributes to morbidity and mortality after shock. These results will generate fundamental new knowledge about the pathogenesis of shock. They will provide a new understanding for the role digestive enzymes play in initiating ischemic injury in the intestine and optimize treatment strategies to interfere with their activity in shock, leading to potential clinical applications to decrease morbidity and mortality in this condition.