SP-A Receptor Regulation in Lung Innate Defense

肺先天防御中 SP-A 受体的调节

• 批准号: 6904594
• 负责人: ANN MARIE LEVINE
• 金额: $ 36.38万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6904594
• 关键词: Streptococcus agalactiae; alveolar macrophages; bacteria infection mechanism; bactericidal immunity; biological models; biological signal transduction; cell line; cell surface receptors; clearance rate; complement receptor; flow cytometry; free radical oxygen; gene targeting; genetically modified animals; laboratory mouse; microorganism culture; phagocytosis; phosphatidylinositol 3 kinase; protein biosynthesis; protein structure function; pulmonary surfactants; receptor binding; site directed mutagenesis; transfection; western blottings

DESCRIPTION (provided by applicant): This application will test the hypothesis that surfactant protein-A (SP-A), a pulmonary collectin, plays a critical role in protecting the lung from bacterial infection by modulating surface receptors on alveolar macrophages. Preliminary data presented in this application provides a clear relationship between SP-A and complement receptor type 3 (CR3) providing a strong inference that SP-A effects are mediated through CR3. We propose that SP-A serves complex regulatory roles in the lung, binding to cell surface receptors present on alveolar macrophages influencing binding, uptake, and killing of microorganisms. CR3 is an important phagocyte receptor for recognition of microbial pathogens and is responsible for mediating phagocytosis, degranulation, and respiratory bursts by phagocytic cells. CR3 mediated phagocytosis is important in clearance of group B streptococcus (GBS) and Haemophilus influenza, both important pathogens in childhood disease. This application will utilize models in which the synthesis of SP-A is altered genetically, using SP-A-/- and SP-A+/+ mice to determine if CR3 expression on alveolar macrophages is altered in the absence of SP-A. This application will test the central hypothesis that SP-A enhances phagocytosis and activates alveolar macrophages by modulating surface receptors mediating these events. Specific Aim 1 will test the hypothesis that SP-A regulates expression of CR3 on alveolar macrophages by mobilizing intracellular CR3 pools. Specific Aim 2 will test the hypothesis that SP-A binds to CR3 on alveolar macrophages and will determine the specific SP-A domain that enhances CR3 expression. Specific Aim 3 will test the hypothesis that SP-A opsonized GBS or H. influenza activate CR3 to enhance macrophage phagocytosis and oxygen radical production. Signaling pathways important in SP-A enhanced CR3 mediated phagocytosis will be studied in vitro using CR3 transfected cells and in vivo with alveolar macrophages from SP-A-/-, CR3-/-, SP-A-/-CR3-/- and wild type mice. These studies will help clarify the role of SP-A in innate defense of the lung and provide the basis for future therapies to maintain endogenous or supply exogenous SP-A to prevent morbidity from bacterial infection.

描述（由申请人提供）：本申请将检验以下假设：表面活性剂蛋白A（SP-A）是一种肺收集蛋白，在保护肺部通过调节肺泡巨噬细胞上的表面受体来保护肺部免受细菌感染起着关键作用。 本应用程序中介绍的初步数据提供了SP-A与3型补体受体（CR3）之间的明确关系，提供了强烈的推断，即SP-A效应是通过CR3介导的。 我们建议SP-A在肺中起复杂的调节作用，与存在于影响结合，摄取和杀死微生物的肺泡巨噬细胞上的细胞表面受体结合。 CR3是识别微生物病原体的重要吞噬受体，并负责介导吞噬细胞的吞噬，脱粒和呼吸道爆发。 CR3介导的吞噬作用对于清除B组链球菌（GBS）和流感嗜血杆菌的清除，这都是儿童疾病中重要的病原体。 该应用将利用模型，其中使用sp-a - / - 和sp-a+/+小鼠在遗传上改变了SP-A的合成，以确定在没有SP-A的情况下是否改变了肺泡巨噬细胞上的CR3表达。 该应用将检验中心假设，即SP-A通过调节介导这些事件的表面受体来增强吞噬作用并激活肺泡巨噬细胞。 具体目标1将测试SP-A通过动员细胞内CR3池在肺泡巨噬细胞上调节CR3表达的假设。 具体目标2将检验SP-A在肺泡巨噬细胞上与CR3结合的假设，并将确定增强CR3表达的特定SP-A结构域。 特定的目标3将检验SP-A调子GB或H. h. h. h. h. h. h. the the的假设，使CR3激活CR3，以增强巨噬细胞吞噬作用和氧自由基的产生。 在SP-A增强CR3介导的吞噬作用中重要的信号通路将在体外研究使用CR3转染的细胞和体内，并在体内具有SP-A - / - ，CR3 - / - ，SP-A - / - / - CR3 - / - 和野生型小鼠的肺泡巨噬细胞。 这些研究将有助于阐明SP-A先天防御肺部的作用，并为将来的疗法维持内源性或提供外源性SP-A的疗法提供基础，以防止细菌感染发病。