Pseudomonas' effects on the gut barrier from surgery

描述（由申请人提供）： 在危重外科患者的肠道内仅仅存在人类机会性病原体铜绿假单胞菌就与过高的死亡率（~ 50%）相关-比对该病原体培养为阴性的生理学匹配的患者增加超过3倍。在这个提议中，我们提供了强有力的证据，在手术应激宿主的肠道内，介质被释放，直接向铜绿假单胞菌的分子机制发出信号，以表达毒性和致死性表型。我们假设，特定的宿主应激源性细菌信号化合物（BSC），包括阿片受体激动剂（吗啡，κ和δ受体激动剂）和干扰素-γ（IFN-γ），释放到肠道中，以响应手术应激。我们进一步假设，这些化合物直接结合到铜绿假单胞菌上的特定细菌膜受体，导致群体感应依赖性毒力决定因子PA-1凝集素的表达。我们先前已经证明，在手术应激的肠道内铜绿假单胞菌中PA-1的表达在该病原体中产生致死表型，诱导其强效细胞毒素的深刻上皮通透性缺陷。因此，本申请的具体目的是：1）确定铜绿假单胞菌响应于阿片激动剂和IFN-γ表达PA-1所需的基因和受体; 2）检验阿片激动剂和IFN-γ通过其PA-1凝集素的作用向铜绿假单胞菌发出信号以表达针对肠上皮的更具毒性的表型的假设;和3）分离、鉴定和纯化在应激期间释放到肠中的另外的宿主来源的细菌信号化合物，其向铜绿假单胞菌发出信号以表达PA-1凝集素。详细了解手术应激宿主和铜绿假单胞菌等经典机会主义者之间的分子对话，将导致这种高度耐药和致命病原体的新治疗靶点，以及在其最近点阻断感染过程的策略。

DESCRIPTION (provided by applicant): The mere presence of the human opportunistic pathogen, Pseudomonas aeruginosa within the intestinal tract of a critically ill surgical patient, is associated an excessive mortality rate (-50%)-a more than 3-fold increase above physiologically-matched patients who culture negative for this pathogen. In this proposal, we provide strong evidence that within the intestinal tract of a surgically stressed host, mediators are released that directly signal the molecular machinery of P. aeruginosa to express a virulent and lethal phenotype. We hypothesize that specific host stress-derived Bacterial Signaling Compounds (BSCs), including opioid agonists (morphine, kappa and delta receptor agonists) and Interferon-gamma (IFN-gamma), are released into the intestinal tract in response to surgical stress. We further hypothesize that these compounds directly bind to specific bacterial membrane receptors on P. aeruginosa that lead to the expression of the quorum sensing-dependent virulence determinant, the PA-I lectin. We have previously demonstrated that expression of PA-I in P. aeruginosa within the intestinal tract of a surgically stressed creates a lethal phenotype in this pathogen, inducing a profound epithelial permeability defect to its potent cytotoxins. Therefore, the Specific Aims of this application are: 1) To define the genes and receptors that are required for P. aeruginosa to express PA-I in response to opioid agonists and IFN-gamma; 2) To test the hypothesis that opioid agonists and IFN-y signal P. aeruginosa to express a more virulent phenotype against the intestinal epithelium through the action of its PA-I lectin; and 3) To isolate, identify, and purify additional host-derived bacterial signaling compounds released into the intestine during stress that signal P. aeruginosa to express the PA-I lectin. A detailed understanding of the molecular dialogue that develops between a surgically stressed host and a classic opportunist like P. aeruginosa will lead to novel therapeutic targets in this highly resistant and lethal pathogen and strategies to interdict in the infectious process at its most proximal point.