Apoptotic T Cell Clearance From Murine Lungs

描述（申请人摘要）：必须清除凋亡T细胞 巨噬细胞有效地防止组织损伤，但摄取凋亡 细胞导致巨噬细胞下调自身的生产， 促炎细胞因子如TNF和IL-8以及趋化因子。因此，虽然 在缓解肺炎期间诱导凋亡的T细胞是有益的， 如果肺泡巨噬细胞摄取了 在遇到病原体之前或期间死亡的T细胞。事实上，研究 由该项目资助的一项新的观察表明，许多凋亡 在小鼠的肺中发现淋巴细胞。因此，肺，粘膜表面 经常暴露于病原体，在调节 巨噬细胞清除凋亡T细胞，同时维持宿主防御。是 这一挑战可能与正常状态有关， 单个肺泡巨噬细胞遇到孤立的凋亡T细胞，当 大量的T细胞死亡（例如，急性病毒性肺炎后， 慢性HIV感染）。该项目的新初步数据表明， 肺巨噬细胞对凋亡T细胞的摄取受到调节， 进化适应，以尽量减少免疫抑制作用， 否则会导致该部位频繁的病原体暴露。这个目标 项目是确定调控的分子基础和意义， 肺中凋亡T细胞的吞噬作用。它将测试以下内容 假说：宿主下调凋亡T细胞吞噬作用 小鼠肺泡巨噬细胞的结果都改变了粘附凋亡T细胞 细胞和相对于对照腹膜的改变的信号转导 巨噬细胞;有效清除凋亡的T细胞在解决 肺部炎症可能依赖于获得一种免疫表型， 主要是通过炎性细胞因子分化募集的单核细胞;和 摄入凋亡T细胞有损害肺部宿主的风险， 防御细菌和真菌病原体。两个原发性肺泡 和正常小鼠的腹腔巨噬细胞，以及两个永生化的小鼠 将使用巨噬细胞系（MH-S和J774A.1）。技术将包括 静态粘附和吞噬试验，特异性酶抑制剂， 免疫沉淀、蛋白质印迹、流式细胞术和体内免疫沉淀的应用。 真菌（新型隐球菌）和细菌（葡萄球菌）的小鼠模型 金黄色葡萄球菌）肺炎。预计这些结果将提供重要的 关于免疫调节的新信息， 正常和免疫受损宿主中的细菌和真菌感染， 自身免疫和肺纤维化的发展。

DESCRIPTION (Applicant's Abstract): Apoptotic T cells must be cleared efficiently by macrophages to prevent tissue damage, but ingestion of apoptotic cells causes macrophages to downregulate their own production of proinflammatory cytokines such as TNF and IL-8 and of chemokines. Hence, while ingesting apoptotic T cells during resolving pneumonia is beneficial, the same process could be immunosuppressive if pulmonary alveolar macrophages ingest dying T cells before or during encounters with pathogens. Indeed, studies funded by this project made the novel observation that many apoptotic lymphocytes are found in the lungs of mice. Thus, the lungs, a mucosal surface frequently exposed to pathogens, present a unique challenge in regulating macrophage clearance of apoptotic T cells while maintaining host defense. It is likely that this challenge is relevant both to the normal state, in which single alveolar macrophages encounter isolated apoptotic T cells, and when larger numbers of T cells die (e.g., following acute viral pneumonias and in chronic HIV infection). New preliminary data from this project suggest that ingestion of apoptotic T cells by lung macrophages is regulated, as an evolutionary adaptation, to minimize the immunosuppressive effect that could otherwise result at this site of frequent pathogen exposure. The goal of this project is to define the molecular basis and significance of regulated phagocytosis of apoptotic T cells in the lungs. It will test the following hypotheses: that downregulated phagocytosis of apoptotic T cells by resident murine alveolar macrophages results both from altered adhesion of apoptotic T cells and from altered signal transduction relative to control peritoneal macrophages; that effective clearance of apoptotic T cells during resolving lung inflammation depends on acquisition of an ingesting phenotype, probably mostly by differentiation of recruited monocytes by inflammatory cytokines; and that ingestion of apoptotic T cells carries a risk of impaired lung host defense against bacterial and fungal pathogens. Both primary resident alveolar and peritoneal macrophages from normal mice, and two immortalized murine macrophage cell lines (MH-S and J774A.1) will be used. Techniques will include static adhesion and phagocytosis assays, specific enzyme inhibitors, immunoprecipitation, Western blotting, flow cytometry, and use of in vivo murine models of fungal (Cryptococcus neoformans) and bacterial (Staphylococcus aureus) pneumonia. It is anticipated that the results will provide important new information about immunoregulation that will be relevant to viral, bacterial, and fungal infections in normal and immunocompromised hosts, development of autoimmunity and lung fibrosis.