Regulation and function of STAT3 during pneumonia

简介(申请人提供)：肺炎是美国感染性死亡的主要原因，也是导致急性肺损伤的最常见因素。社区获得性肺炎最常见的致病菌是肺炎链球菌，而院内获得性肺炎通常由革兰氏阴性肠杆菌引起，如大肠埃希氏菌。在预防肺损伤的同时抗击细菌需要细胞因子-转录因子网络介导的精确调控基因表达。我们的长期目标是阐明这些信号网络，以便可以操纵细胞因子和转录因子来改善宿主防御和防止肺损伤。在细菌性肺炎中，细胞因子IL-6对中性粒细胞募集和细菌清除起着至关重要的作用。转录因子STAT3可被IL-6激活，在预防高氧性肺损伤中起关键作用。我们的主要目标是确定STAT3在肺炎期间是否在肺中被激活，破译肺炎期间调节STAT3激活的上游途径，以及确定增加STAT3活性是否在肺炎期间保护肺。根据我们的初步研究结果，我们提出了一个中心假设，即在大肠杆菌和肺炎链球菌感染期间，STAT3被不同的上游细胞因子途径激活，以增加中性粒细胞的募集和防止肺损伤。为了验证这一中心假设，我们开发了一些策略来研究体内肺中的基因诱导和转录因子功能，并使用蛋白质组学来研究体内肺中激活的转录因子。通过这些方法，我们将追求以下特定目标：(1)测试假设，即在肺炎期间，STAT3的激活需要IL-6；(2)测试假设，在肺炎链球菌肺炎期间，STAT3由多种IL-6家族细胞因子激活，这些细胞因子的表达需要通过TNFpha和IL-1的受体来激活NF-kappaB；(3)测试假设，在肺炎期间，STAT3的活性增加中性粒细胞的募集，并减少肺损伤；以及(4)寻找肺炎期间依赖于IL-6的除STAT3以外的转录调节因子。阐明IL-6和STAT3在肺炎中的调节和作用，将为改善肺部感染患者的宿主防御和预防肺损伤提供分子靶点。

DESCRIPTION (provided by applicant): Pneumonia is the leading cause of infectious deaths in the U.S. and the most common factor underlying acute lung injury. Community acquired pneumonias are most often caused by Streptococcus pneumoniae, whereas nosocomial pneumonias are commonly caused by Gram-negative enteric bacteria such as Escherichia coli. Fighting bacteria while preventing lung injury requires precisely regulated gene expression mediated by cytokine-transcription factor networks. Our long-term goals are to elucidate these signaling networks so that cytokines and transcription factors may be manipulated to improve host defense and prevent lung injury. The cytokine IL-6 is essential to neutrophil recruitment and bacterial clearance during bacterial pneumonia. The transcription factor STAT3 can be activated by IL-6, and is critical to preventing lung injury after hyperoxia. Our broad objectives are to determine whether STAT3 is activated in the lungs during pneumonia, to decipher the upstream pathways regulating STAT3 activation during pneumonia, and to determine whether increasing STAT3 activity protects the lungs during pneumonia. Based on results from our preliminary studies, we have formulated the central hypothesis that STAT3 is activated by different upstream cytokine pathways during E. coli and S. pneumoniae pneumonias to increase neutrophil recruitment and prevent lung injury. To test this central hypothesis, we have developed strategies for studying gene induction and transcription factor function in the lungs in vivo, using plasmid transfection, and for identifying transcription factors activated in the lungs in vivo, using proteomics. With these approaches, we will pursue the following specific aims: (1) to test the hypothesis that STAT3 activation requires IL-6 during E. coli pneumonia, (2) to test the hypothesis that, during S. pneumoniae pneumonia, STAT3 is activated by multiple IL-6 family cytokines whose expression requires NF-KappaB activation from receptors for TNFalpha and IL-1, (3) to test the hypothesis that STAT3 activity in the lungs increases neutrophil recruitment and decreases lung injury during pneumonia, and (4) to identify transcriptional regulators other than STAT3 that depend on IL-6 during pneumonia. Elucidating the regulation and function of IL-6 and STAT3 during pneumonia will provide molecular targets for improving host defense and preventing lung injury in patients with or at risk for lung infections.