Evasion of Macrophage Lysosomes by L pneumophilia

描述(申请人提供)：先天性和获得性免疫反应是由巨噬细胞吞噬启动的，这是一种尚未完全了解的复杂细胞途径。为了研究吞噬小体成熟是如何调控的，细菌病原体嗜肺军团菌可以作为巨噬细胞功能的遗传探针。以前的研究支持这一假说，嗜肺乳杆菌通过在其表面表达至少两种发育调节的活性来阻止吞噬小体-溶酶体融合。 嗜肺性乳杆菌何时、如何和在哪里表达吞噬小体成熟抑制物的知识将被用于鉴定相应的分子。通过分离和表征影响DOTA突变体在巨噬细胞中的持久性、凝集素结合或碳氢化合物结合的突变，以及通过比较毒力菌株和无毒菌株的表面蛋白质和碳水化合物的图谱，从遗传上寻找阻止吞噬小体-溶酶体融合的细菌表面因子。指数期后细菌表达的阻止与溶酶体融合的因子也将通过其结构性表达将调节突变体从溶酶体杀死中拯救出来的基因座来鉴定。 通过了解嗜肺乳杆菌如何逃避巨噬细胞的清除，人们可以推断这些吞噬细胞是如何例行公事地吞噬、消化和展示异物，然后聘请专家来消除潜在的威胁。由于巨噬细胞在体液免疫和细胞免疫中都是中心效应细胞，对其膜运输的分子描述可能为改善治疗药物的输送提供无数机会，以预防和治疗各种人类疾病。

DESCRIPTION (provided by applicant): Innate and adaptive immune responses are initiated by macrophage phagocytosis, a complex cellular pathway that is not yet fully understood. To investigate how phagosome maturation is governed, the bacterial pathogen Legionella pneumophila can be exploited as a genetic probe of macrophage function. Previous studies support the hypothesis that L. pneumophila blocks phagosome-lysosome fusion by expressing on its surface at least two activities that are developmentally regulated. Knowledge of when, how and where inhibitors of phagosome maturation are expressed by L. pneumophila will be applied to identify the corresponding molecules. Factors on the bacterial surface that block phagosome-lysosome fusion will be sought genetically by isolating and characterizing mutations that affect either persistence of dotA mutants in macrophages, lectin binding, or hydrocarbon binding, and biochemically by comparing the profiles of surface proteins and carbohydrates of virulent and avirulent strains. Factors expressed by post-exponential phase bacteria to block fusion with lysosomes will also be identified by loci whose constitutive expression rescues a regulatory mutant from lysosomal killing. By understanding how L. pneumophila evades clearance by macrophages, one can deduce how these phagocytes routinely engulf, digest, and display foreign material, then recruit specialists to eliminate potential threats. Because macrophages are central effector cells in both humoral and cell-mediated immunity, a molecular description of their membrane traffic is likely to provide a myriad of opportunities for improving delivery of therapeutics to prevent and treat a variety of human diseases.