Mechanisms of Bacterial Induced Lung Injury

肺炎是败血症最常见的原因，也是急性肺损伤(ALI)最常见的原因。该项目的总体目标是调查人类遗传异常和细菌毒力基因在临床肺损伤和肺炎发生中的作用。我们选择了一个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，特别是危重患者和ALI风险患者的肺部感染中具有潜在的重要性。甘露糖结合凝集素(MBL)缺乏是最常见的免疫缺陷之一，与黏膜获得性病原体引起的严重肺部疾病有关。铜绿假单胞菌是呼吸机相关性肺炎最常见的革兰氏阴性菌 (VAP)。铜绿假单胞菌中III型分泌系统基因的产物会导致实验动物的急性肺损伤，而从危重患者中分离的铜绿假单胞菌菌株会产生III型分泌蛋白。我们将建立一项前瞻性队列调查，以检验MBL基因异常与严重ALI风险增加相关的假设(目标1)。我们还将对铜绿假单胞菌菌株的分子特征和感染铜绿假单胞菌的呼吸机患者毒力基因的遗传表达进行前瞻性队列调查(目标2)。铜绿假单胞菌定植的患者(通过监测气管抽吸物培养确定)将定期进行BAL，以确定定植是否可以通过肺上皮损伤的生化标记物与VAP区分。还将对因铜绿假单胞菌引起的VAP和/或ALI的患者进行BAL；这些BAL液的结果将与从定居患者获得的BAL进行比较。这一目标将考验 假设从定植到肺部感染的转变与III型分泌物毒力基因的表达有关。然后，我们将比较从VAP和/或ALI患者那里获得的铜绿假单胞菌菌株与从只感染铜绿假单胞菌的患者那里获得的菌株，并量化这些菌株在空气中滴注到小鼠体内所造成的肺损伤(目标3)。这一最终目标将使我们能够利用动物来回答一个临床问题：定植菌株和在VAP患者中发现的菌株是否在生物学效应方面有所不同。患者和小鼠的BAL液将用于其他项目(L和3)，以评估促凝血途径和抗纤溶途径。 远处的空域。还将在蛋白质组学核心中对这些液体进行评估，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.