Mechanisms of Intestinal Apoptosis in Sepsis and Shock

脓毒症和休克中肠细胞凋亡的机制

• 批准号: 7119998
• 负责人: Craig M Coopersmith
• 金额: $ 33.62万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-06 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7119998
• 关键词: BCL2 gene /protein; Pseudomonas aeruginosa; apoptosis; bacteria infection mechanism; biological signal transduction; cell differentiation; gene expression; gene mutation; genetically modified animals; germ free condition; host organism interaction; intestinal mucosa; laboratory mouse; lymphocyte; membrane permeability; mitochondria; pneumonia; receptor expression; septic shock; septicemia

DESCRIPTION (provided by applicant): Sepsis kills at least 120,000 people annually in the United States. The gut has long been proposed to be the "motor" of the systemic inflammatory response, and increased intestinal apoptosis is a potential mechanism underlying the gut's role in critical illness. We have previously shown that gut epithelial apoptosis is increased in both animal models and human autopsy studies of sepsis. Further, intestinal overexpression of the anti-apoptotic protein Bcl-2 improves survival in murine models of gram negative pneumonia and appendicitis. The central hypothesis of this proposal is that gut apoptosis plays a critical role in mediating decreased host survival through both mitochondrial and receptor-mediated pathways in either gram positive or gram negative sepsis. We will first identify pathways through which pathogenic bacteria induce intestinal cell death utilizing a variety of infections to verify results are not model specific. The functional significance of this will be shown by determining if altering gut cell death via intestine-specific modulation of cell death pathways or downstream apoptotic signaling improves host survival. Next, we have demonstrated that sepsis-induced gut death is dependent on crosstalk with lymphocytes. Lymphocyte subsets responsible for this interaction will be determined, as will cellular, tissue, and systemic mechanisms underlying how lymphocytes alter gut epithelial apoptosis in sepsis. Finally, sepsis-induced gut apoptosis normally occurs in the presence of the intestine's endogenous bacteria. Since the gut's microflora influences host epithelial biology under basal conditions, we will determine its significance in sepsis by eliminating it. Using germ-free animals that lack endogenous bacteria and colonizing them with single members of the gut's own flora, we will determine how gut bacteria affect intestinal epithelial apoptosis if these mice are subsequently made septic. We will then rederive transgenic mice that overexpress gut Bcl-2 to be germ-free to determine the functional relationship between the intestine's endogenous flora and epithelial apoptosis in sepsis.

描述（由申请人提供）： 在美国，脓毒症每年导致至少 12 万人死亡。长期以来，肠道一直被认为是全身炎症反应的“发动机”，而肠道细胞凋亡的增加是肠道在危重疾病中发挥作用的潜在机制。我们之前已经表明，在脓毒症的动物模型和人体尸检研究中，肠上皮细胞凋亡均增加。此外，抗凋亡蛋白 Bcl-2 的肠道过度表达可提高革兰氏阴性肺炎和阑尾炎小鼠模型的存活率。该提议的中心假设是，肠道细胞凋亡在革兰氏阳性或革兰氏阴性脓毒症中通过线粒体和受体介导的途径在介导宿主存活率下降中发挥着关键作用。我们将首先利用各种感染来确定致病菌诱导肠道细胞死亡的途径，以验证结果不是模型特异性的。通过确定是否通过肠道特异性调节细胞死亡途径或下游凋亡信号传导来改变肠道细胞死亡是否可以提高宿主存活率，将显示其功能意义。接下来，我们证明脓毒症引起的肠道死亡依赖于与淋巴细胞的串扰。负责这种相互作用的淋巴细胞亚群将被确定，淋巴细胞如何改变败血症中肠上皮细胞凋亡的细胞、组织和系统机制也将被确定。最后，败血症诱导的肠道细胞凋亡通常发生在肠道内源性细菌存在的情况下。由于肠道微生物群在基础条件下影响宿主上皮生物学，因此我们将通过消除它来确定其在脓毒症中的重要性。使用缺乏内源性细菌的无菌动物，并用肠道自身菌群的单个成员定植它们，我们将确定如果这些小鼠随后出现败血症，肠道细菌如何影响肠上皮细胞凋亡。然后，我们将过度表达肠道 Bcl-2 的转基因小鼠重新衍生为无菌小鼠，以确定脓毒症中肠道内源菌群与上皮细胞凋亡之间的功能关系。