Sufactant Protein-A and Lung Defense

描述（由申请方提供）：在美国和其他国家，细菌性肺炎引起的肺部炎症过程造成了相当大的发病率和死亡率临床负担。 许多被认为是潜在生物恐怖威胁的微生物会导致严重的肺部炎症。 在之前的资助期间，使用转基因小鼠的研究表明，表面活性剂蛋白A（SP-A）可以减少由微生物和微生物产物引起的炎症。 对肺炎或囊性纤维化（CF）患者的研究表明，SP-A浓度降低，表明SP-A调节微生物诱导的肺部炎症的程度。 本申请的目的是确定SP-A调节肺部炎症反应的机制。 最近的研究表明，Toll样受体（TLR）在诱导炎症反应中发挥重要作用。 TLR 4是LPS和革兰氏阴性菌的主要受体。 LPS与CD 14结合，LPS/CD 14与MD-2/TLR 4相互作用，形成细胞表面三联受体复合物，其转导细胞内信号，导致细胞因子和其他炎症调节剂的活化。SP-A不结合LPS的平滑形式，但SP-A在体内和体外阻断LPS诱导的细胞因子产生。 缺乏与光滑LPS的结合表明SP-A不能简单地隔离LPS与TLR复合物的相互作用。 TLR 4、CD 14和MD-2 RNA存在于肺泡巨噬细胞和小鼠肺上皮细胞中，支持SP-A通过TLR-4组分减少平滑LPS信号传导来改变肺中的炎症反应的中心假设。 将使用细胞转染或LPS和革兰氏阴性感染小鼠模型中的平滑LPS介导的NF-κ B诱导来测试该假设，以完成以下目的：（1）将在体外鉴定功能上相互作用以引起LPS介导的信号传导的SP-A抑制的SP-A结构和LPS受体组分;（2）SP-A抑制LPS介导的信号传导的机制将通过测试SP-A是否在体外改变LPS信号传导所必需的TLR 4组分之间的相互作用来确定;和（3）将鉴定SP-A抑制LPS或革兰氏阴性细菌介导的体内信号传导所需的SP-A结构域。 本申请旨在鉴定SP-A调节肺部炎症反应的新机制，目的是鉴定减少肺部炎症的新方法。

DESCRIPTION (provided by applicant): Pulmonary inflammatory processes due to bacterial pneumonia impose a considerable clinical burden of morbidity and mortality in the US and other countries. A number of microbes considered as potential bioterrorist threats cause severe pulmonary inflammation. During the previous funding period, studies using transgenic mice, demonstrated that surfactant protein-A (SP-A) reduces inflammation caused by microbes and microbial products. Studies from patients with pneumonia or cystic fibrosis (CF) demonstrated reduced concentrations of SP-A suggesting that SP-A modulates the extent of microbial induced pulmonary inflammation. The goal of the present application is to determine mechanisms whereby SP-A regulates pulmonary inflammatory responses. Recent studies have demonstrated important roles for toll-like receptors (TLR) in inducing inflammatory responses. TLR4 is a major receptor for LPS and gram-negative bacteria. LPS binds to CD14 and LPS/CD14 interacts with MD-2/TLR4 forming a cell surface tripartite receptor complex that transduces intracellular signals leading to activation of cytokines and other inflammatory modulators. SP-A does not bind smooth forms of LPS but SP-A blocks smooth LPS induced cytokine production in vivo and in vitro. The lack of binding to smooth LPS suggests that SP-A cannot simply be sequestering LPS from interactions with the TLR complex. TLR4, CD14, and MD-2 RNA are present in alveolar macrophages and mouse lung epithelial cells supporting the central hypothesis that SP-A alters inflammatory responses in the lung by reducing smooth LPS signaling through TLR-4 components. This hypothesis will be tested using smooth LPS mediated induction of NF-kappaB in cell transfections or LPS and gram-negative infection in mouse models to complete the following aims: (1) The SP-A structures and LPS receptor components that functionally interact to cause SP-A inhibition of LPS mediated signaling will be identified in vitro; (2) Mechanisms by which SP-A inhibits LPS mediated signaling will be determined by testing if SP-A alters interactions between TLR4 components necessary for LPS signaling in vitro; and (3) Structural domains of SP-A required for SP-A inhibition of LPS or gram-negative bacterial mediated signaling in vivo will be identified. The present application seeks to identify novel mechanisms of SP-A regulation of pulmonary inflammatory responses with the goal of identifying novel approaches to reducing pulmonary inflammation.