Pathogenesis and Treatment of Experimental Peritonitis

描述(由申请人提供)： 肠粘膜屏障紊乱可能在肠炎的发病机制中起重要作用。 全身感染危重病人。宿主防御机制的紊乱导致肠道诱导型一氧化氮合酶(INOS)持续上调，可能导致肠粘膜屏障功能的深刻变化。有证据表明，过氧亚硝酸盐(ONOO-)是NO与过氧化氢反应形成的一种强有力的氧化剂，可能是NO在内毒素血症、炎症性肠病(IBD)或坏死性小肠结肠炎等炎症条件下引起细胞病变的关键反应性氮中间体。我们的目的是确定过量产生NO或ONOO-可能促进组织损伤(肠细胞凋亡或坏死)和抑制组织修复机制(通过肠细胞迁移和增殖恢复上皮)，从而导致肠屏障功能衰竭的机制。我们提出了两个具体目标。目的：阐明ONOO诱导肠上皮细胞凋亡的可能机制。我们将研究ONOO-在不同的肠道细胞系中的细胞病变效应以及可能涉及的生化途径(线粒体失调、半胱氨酸天冬氨酸氨基转移酶和PARS激活)。目的II：探讨NO或ONOO-抑制组织修复、上皮修复和增殖的机制。我们将研究ONOO-如何通过肠细胞迁移影响上皮修复，肠细胞迁移是修复粘膜损伤的增殖反应之前的关键阶段。迁移可能部分受Rho-GTP酶的调节，Rho-GTP酶改变肌动蛋白细胞骨架。我们将在体外确定Rho是否是肠细胞迁移和应激纤维形成所必需的。我们将通过硝化酪氨酸激酶Src家族关键成员的关键酪氨酸残基来检验ONOO可以抑制迁移和增殖的假设：SRC；粘着斑激酶(FAK)；以及 P13K。我们将尝试用各种细胞保护剂调节Rho、Src激酶或线粒体信号通路，以增强体内与过量NO/ONOO-产生相关的肠道屏障功能(内毒素血症IBD)。

DESCRIPTION (provided by applicant): Derangement in the intestinal mucosal barrier may play an important role m the pathogenesis of systemic infection critically ill patients. Perturbations in the host defense mechanisms that result in sustained upregulation of inducible nitric oxide synthase (iNOS) in the gut may lead to profound alterations in intestinal mucosal barrier function. Evidence suggests that peroxynitrite (ONOO-), a potent oxidant formed by the reaction of NO with mperoxide, may be a key reactive nitrogen intermediate responsible for the eytopathic effects of NO in inflammatory conditions such as endotoxemia, inflammatory bowel disease (IBD), or necrotizing enterocolitis. Our objective is to determine the mechanisms by which overproduction of NO or ONOO- may promote tissue injury enterocyte apoptosis or necrosis) and inhibit tissue repair mechanisms (epithelial restitution via enterocyte migration and proliferation), thereby leading to gut barrier failure. We propose two specific aims. Aim I: To elucidate the potential mechanisms by which ONOO induces enterocyte apoptosis. We will examine the cytopathic effect of ONOO- in various enterocytic cell lines and the biochemical pathways that may be involved (mitochondrial dysregulation, caspases, and PARS activation). Aim II: To investigate the mechanisms by which NO or ONOO- inhibits tissue repair mechanisms, epithelial restitution and proliferation. We will examine how ONOO- affects epithelial restitution by enterocyte migration, the critical phase that precedes the proliferative response to repair the mucosal injury. Migration may be regulated in part by Rho-GTPases, which modify the actin cytoskeleton. We will determine whether Rho is required for enterocyte migration and stress fiber formation in vitro. We will test the hypothesis that ONOO can inhibit migration and proliferation by nitrating critical tyrosine residues of key members of the Src family of tyrosine kinases: Src; focal adhesion kinase (FAK); and P13K. We will attempt to modulate Rho, Src kinase, or mitochondrial signaling pathways with various cytoprotective agents to enhance intestinal barrier function in conditions associated with excessive NO/ONOO- production (endotoxemia IBD) in vivo.