MOLECULAR PATHOGENESIS OF GUT INJURY IN MULTIPLE ORGAN FAILURE

肠道低灌流是创伤患者中常见的早期事件，有可能进展为多器官衰竭(MOF)。这种缺血/再灌流损伤引发局部炎症反应，可能促进早期和晚期MOF的演变。虽然人们对肠道对休克和缺血/再灌注损伤的病理生理反应知之甚少，但对这些损伤在肠道和远程器官中诱导的分子程序，或者这些反应可能被调节以获得治疗益处的机制，我们知之甚少。本项目旨在通过检测内毒素血症和肠系膜缺血/再灌注损伤动物模型中肠道、肺和肝脏以及培养的小肠上皮细胞和肌层巨噬细胞的应激反应来表征这些信号事件。这些动物和体外数据描述了脂多糖(LPS)注射和肠系膜缺血/再灌流后大鼠肠道、肺和肝脏的分子应激反应。本课程将分析应激激酶级联反应、可诱导转录因子及其靶向致炎基因的激活和细胞分布。在Aim 2中，将使用暴露于脂多糖或氧化应激的小肠上皮细胞和肠道巨噬细胞的培养，对在组织水平上识别的分子信号事件进行机械剖析。目的3研究α-黑素细胞刺激素(α-MSH)的作用，α-MSH是一种内源性抗炎肽，已知可消除缺血/再灌注损伤。α-MSH在各种形式的炎症中的有益作用，以及它影响多个促炎基因的能力，表明它在炎症级联反应的共同早期阶段发挥作用，可能是在基因转录水平上。因此，目标4试图描述α-MSH抑制分子应激反应激活的机制，该分子应激反应控制培养的巨噬细胞系和肠道巨噬细胞中促炎基因的表达。这些研究涉及与该中心所有项目的合作，它们应该为炎症信号改变肠道基因表达的机制提供重要的见解，更广泛地说，改变MOF的病理生物学。预计这些研究将有助于合理开发新的治疗方法，选择性地和有益地调节促进这种综合征的基因的表达。

Gut hypoperfusion is a common early event in trauma patients likely to progress to multiple organ failure (MOF). This ischemia/reperfusion injury precipitates a local hyperinflammatory response that likely promotes the evolution of both early and late MOF. While much is known about the pathophysiologic responses of the gut to shock and ischemia/reperfusion injury, little is known about the molecular programs induced in the gut and remote organs by these insults, or the mechanisms by which these responses may be regulated to therapeutic benefit. This project seeks to characterize these signaling events by examining the stress responses of the gut, lung, and liver in animal model of endotoxemia and mesenteric ischemia/reperfusion injury, and in cultured epithelial cells and muscularis macrophages from the small intestine. These animal and in vitro data characterize the molecular stress response of the gut, lungs, and liver in rats following lipopolysaccharide (LPS) administration and mesenteric ischemia/reperfusion. The activation and cellular distribution of stress-kinase cascades, inducible transcription factors, and their target pro-inflammatory genes will be analyzed. The molecular signaling events identified at the tissue level will be mechanistically dissected in Aim 2, using cultures of small intestinal epithelial cells and gut macrophages exposed to LPS or oxidant stress. Aim 3 will examine the effects of alpha-melanocyte stimulating hormone (alpha-MSH), an endogenous anti-inflammatory peptide known to abrogate ischemia/reperfusion injury. The salutary effects of alpha-MSH in diverse forms of inflammation, combined with its ability to influence multiple pro-inflammatory genes, suggest that it acts at common, early step in the inflammatory cascade, presumably at the level of gene transcription. Accordingly, Aim 4 seeks to characterize mechanism by which alpha-MSH inhibits activation of the molecular stress response controlling the expression of pro-inflammatory genes in cultured macrophage cell lines and intestinal macrophages. These studies involve collaborations with all projects of the Center, and they should provide important insights into the mechanisms by which inflammatory signals alter gene expression in the gut and, more broadly, the pathobiology of MOF. It is anticipated that these studies will facilitate the rational development of novel therapies that selectively and beneficially regulate the expression of genes promoting this syndrome.