Mechanisms of Bacterial Induced Lung Injury

肺炎是脓毒症的最常见原因，也是急性肺损伤（ALI）的最常见原因。本项目的总体目标是研究人类遗传异常和细菌毒力基因对临床肺损伤和肺炎发展的贡献。我们选择了一种特定的人类遗传异常和一组细菌毒力基因（III型分泌系统）进行研究，因为它们在肺部感染中具有潜在的重要性，特别是在危重患者和有ALI风险的患者中。甘露糖结合凝集素（MBL）缺陷是最常见的免疫缺陷之一，并已与严重的肺部疾病，由于粘膜获得性病原体。铜绿假单胞菌是呼吸机相关性肺炎最常见的革兰氏阴性病原体 （VAP）。铜绿假单胞菌中III型分泌系统基因的产物在实验动物中引起急性肺损伤，并且从危重患者中分离的铜绿假单胞菌菌株产生III型分泌蛋白。我们将建立一项前瞻性队列研究，以检验MBL基因异常与重度ALI风险增加相关的假设（目的1）。我们还将对铜绿假单胞菌菌株的分子特征和铜绿假单胞菌定殖的通气患者中毒力基因的遗传表达进行前瞻性队列研究（目的2）。铜绿假单胞菌定植（通过气管抽吸物的监测培养确定）的患者将定期接受BAL，以确定是否可以通过肺上皮损伤的生化标志物将定植与VAP区分开来。还将对铜绿假单胞菌导致的VAP和/或ALI患者进行BAL;将这些BAL液的结果与从定植患者中获得的BAL结果进行比较。这一目标将考验 假设从定植到肺部感染的转化与III型分泌毒力基因的表达相关。然后，我们将从患有VAP和/或ALI的患者获得的铜绿假单胞菌菌株与从仅被铜绿假单胞菌定殖的患者获得的菌株进行比较，并量化由将菌株空域滴注到小鼠中引起的肺损伤（目的3）。这最终的目标将使我们能够利用动物来回答一个临床问题;是否殖民菌株和VAP患者中发现的菌株在生物学效应方面存在差异。来自患者和小鼠的BAL液将用于其他项目（1和3），以评估促凝血途径和抗纤维蛋白溶解途径。 远端的空气空间。还将在蛋白质组学核心中对液体进行评价，以确定是否可以在VAP和/或ALI患者的BAL液体中测量细菌毒力蛋白，以及是否也可以在这些患者的BAL液体中发现上皮损伤的标志物。

Pneumonia is the most common cause of sepsis and the most common cause of acute lung injury (ALI). The overall objective of this project is to investigate the contribution of human genetic abnormalities and bacterial virulence genes to the development of clinical lung injury and pneumonia. We have chosen a specific human genetic abnormality and a group of bacterial virulence genes (type III secretion system) to investigate because of their potential importance in lung infections, particularly lung infections in critically ill patients, and in patients at risk for ALI. Mannose binding lectin (MBL) deficiency is one of the most common immunodeficiencies and has been associated with severe lung disease due to mucosally-acquired pathogens. P.aeruginosa is the most frequent Gram negative pathogen associated with ventilator-associated pneumonia (VAP). The products of Type III secretion system genes in P.aeruginosa cause acute lung injury in experimental animals and P.aeruginosa strains isolated from critically ill patients produce type III secretion proteins. We will establish a prospective cohort investigation to test the hypothesis that genetic abnormalities in MBL are associated with an increased risk of severe ALI (Aim 1). We will also establish a prospective cohort investigation of the molecular characteristics of P.aeruginosa strains and the genetic expression of virulence genes in ventilated patients who are colonized with P.aeruginosa (Aim 2). Patients with P. aeruginosa colonization (established by surveillance cultures of tracheal aspirates) will undergo periodic BAL to determine whether colonization can be distinguished from VAP by a biochemical marker of lung epithelial injury. BAL will also be done on patients with VAP and/or ALI due to P.aeruginosa; the results of these BAL fluids will be compared to the BAL obtained from colonized patients. This aim will test the hypothesis that transformation from colonization to lung infection is associated with the expression of the Type III secretion virulence genes. We will then compare the P.aeruginosa strains obtained from patients with VAP and/or ALI to the strains obtained from patients who are only colonized with P.aeruginosa and quantify the lung injury caused by the airspace instillation of the strains into mice (Aim 3). This final aim will allow us to utilize animals to answer a clinical question; whether the colonizing strains and the strains found in patients with VAP differ in terms of their biologic effects. BAL fluids from patients and from the mice will be utilized in other projects (l&3) to evaluate the procoagulant pathway and the antifibrinolytic pathway in the distal airspaces. The fluids will also be evaluated in the proteomics core to determine whether bacterial virulence proteins can be measured in BAL fluids from patients with VAP and/or ALI and whether markers of epithelial injury can also be found in the BAL fluids of these patients.