TB and Innate Immune Regulation of Lung Macrophages

描述（由申请方提供）：肺泡巨噬细胞（AM）来源于迁移到肺中的单核细胞，具有称为替代活化状态的独特生物学特征。由于模式识别受体[例如巨噬细胞甘露糖受体（MR）]的活性增加，AM显示出更大的吞噬能力;并且改变了对微生物的氧化反应。这些属性允许AM有效地清除肺泡内的微生物，同时最大限度地减少“附带”炎症损伤，但我们推测可能使它们成为适应炎症的细胞内病原体的特别好的靶点。表面活性蛋白A（SP-A）在对肺部病原体的先天免疫中是重要的。我们已经确定SP-A信号人类巨噬细胞增加MR功能和减少对刺激的氧化反应。SP-A还可以独特地驱动单核细胞分化以上调MR功能并改变氧化反应。我们的中心假设是SP-A与常驻AM和移民单核细胞的相互作用有助于决定AM的独特功能特性，这些特性在处理呼吸道病原体中很重要。在这方面，SP-A通过内-溶酶体途径运输并与E.在巨噬细胞吞噬溶酶体内卷曲。由于SP-A对大肠杆菌有直接的抗菌活性。卷曲，它可以独特地增强AM的吞噬溶酶体内的杀微生物活性。呼吸适应的细胞内病原体，如结核分枝杆菌（Mtb）破坏了几个先天宿主防御。结核分枝杆菌使用MR进入巨噬细胞，其吞噬体不与溶酶体融合，因此可能限制其与SP-A在该区域的相互作用。 我们的具体目标是：1）确定SP-A诱导的巨噬细胞中（A）MR活性的上调和（B）氧化反应的抑制的潜在机制; 2）确定两种关键的巨噬细胞生化介质在该过程中的作用：蛋白激酶C和磷酸肌醇-3-激酶; 3）确定SP-A对单核细胞分化的影响;比较SP-A和其它表面活性成分对胞外病原菌E.大肠杆菌和人巨噬细胞中的细胞内病原体Mtb。 我们将使用显微镜技术和生物化学测定来评估SP-A对人类单核细胞和巨噬细胞中的MR运输、氧化反应和信号传导以及用于微生物研究的细胞培养的影响。我们的总体目标将是更好地了解表面活性剂组分如何调节巨噬细胞生物学，以维持个体的健康，对抗呼吸道病原体，以及适应性细胞内病原体如何破坏这一过程。

DESCRIPTION (provided by applicant): Alveolar macrophages (AM) originate from monocytes that immigrate into the lung and have unique biological characteristics referred to as an alternative activation state. AM display a greater phagocytic capacity due to increased activity of pattern recognition receptors [e.g. the macrophage mannose receptor (MR)]; and altered oxidative responses to microbes. These attributes allow AM to effectively clear microbes within the alveolus while minimizing "collateral" inflammatory damage, but we speculate may make them particularly good targets for respiratory-adapted intracellular pathogens. Surfactant protein A (SP-A) is important in innate immunity to lung pathogens. We have determined that SP-A signals human macrophages to increase MR function and decrease oxidative responses to stimuli. SP-A can also uniquely drive monocyte differentiation to up-regulate MR function and alter oxidative responses. Our central hypothesis is that interactions of SP-A with both resident AM and immigrating monocytes help dictate the unique functional properties of AM that are important in the handling of respiratory pathogens. In this regard, SP-A traffics through the endo-lysosomal pathway and co-localizes with E. coil within the macrophage phagolysosome. Since SP-A has direct anti-microbial activity against E. coil, it may uniquely enhance microbicidal activity within the phagolysosome of the AM. Respiratory-adapted intracellular pathogens such as Mycobacterium tuberculosis (Mtb) subvert several innate host defenses. Mtb uses the MR to enter the macrophage and its phagosome does not fuse with lysosomes, thus potentially limiting its interaction with SP-A in this locale. Our Specific Aims are to: 1) determine the mechanisms underlying SP-A-induced (A) up-regulation of MR activity and (B) inhibition of oxidative responses in macrophages; 2) determine the role of two key macrophage biochemical mediators in this process: Protein Kinase C and Phosphoinositide-3-kinases; 3) determine the effects of SP-A on monocyte differentiation; and 4) compare the impact of SP-A and other surfactant components on survival of the extracellular pathogen E. coli and the intracellular pathogen Mtb in human macrophages. We will use microscopy techniques and biochemical assays to assess SP-A's effects on MR trafficking, oxidative responses and signaling in human monocytes and macrophages, and cell culture for microbe studies. Our overall goal will be to better understand how surfactant components regulate macrophage biology to maintain the health of the individual against respiratory pathogens and how respiratory-adapted intracellular pathogens subvert this process.