Evasion of Macrophage Lysosomes by L pneumophilia

描述（由申请人提供）：先天性和适应性免疫应答由巨噬细胞吞噬作用启动，巨噬细胞吞噬作用是一种尚未完全理解的复杂细胞途径。为了研究吞噬体成熟是如何被控制的，细菌病原体嗜肺军团菌可以被用作巨噬细胞功能的遗传探针。以往的研究支持L.嗜肺菌通过在其表面表达至少两种发育调节的活性来阻断吞噬体-溶酶体融合。 了解L. pneumophila将用于鉴定相应的分子。通过分离和表征影响巨噬细胞中dotA突变体的持久性、凝集素结合或烃结合的突变，以及通过比较有毒和无毒菌株的表面蛋白和碳水化合物的概况，在遗传学上寻找细菌表面上阻断吞噬体-溶酶体融合的因子。由指数期后细菌表达以阻断与溶酶体融合的因子也将通过基因座来鉴定，所述基因座的组成型表达拯救了调节突变体免于溶酶体杀伤。 通过了解L.当嗜肺菌逃避巨噬细胞的清除时，人们可以推断这些吞噬细胞如何常规地吞噬、消化和展示异物，然后招募专家来消除潜在的威胁。由于巨噬细胞是体液和细胞介导的免疫中的中心效应细胞，因此对其膜运输的分子描述可能为改善治疗剂的递送以预防和治疗各种人类疾病提供无数机会。

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.