Phagocytosis of Cryptococcus neoformans by, and Nonlytic Exocytosis from, Acanthamoeba castellanii
Phagocytosis of Cryptococcus neoformans by, and Nonlytic Exocytosis from, Acanthamoeba castellanii
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DOI：
10.1128/aem.00812-10
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发表时间：
2010-09-01
影响因子：
4.4
通讯作者：
Casadevall, Arturo
中科院分区：
文献类型：
--
作者：
Chrisman, Cara J.;Alvarez, Mauricio;Casadevall, Arturo
新型隐球菌是一种有荚膜的病原酵母，具有多种毒力因子，包括多糖荚膜。在哺乳动物感染期间，新型隐球菌和巨噬细胞之间相互作用的结果对于决定宿主的命运至关重要。先前的研究表明，新型隐球菌与巨噬细胞和变形虫的相互作用之间存在相似性，从而提出了真菌对哺乳动物的毒力源于变形虫捕食者的选择的观点。在这项研究中，我们研究了新型隐球菌与土壤阿米巴阿米巴卡氏阿米巴的相互作用。野生型、无荚膜突变体和互补菌株的吞噬效率比较表明，荚膜对阿米巴原虫具有抗吞噬作用。荚膜增大与吞噬作用的显着减少有关，表明这种现象可以防止被吞噬性捕食者摄入。 C. 新型隐球菌变种新型变形虫细胞被观察到在摄入后数小时离开变形虫，其过程类似于最近描述的巨噬细胞的非裂解性胞吐作用。变形虫的隐球菌胞吐作用取决于菌株和肌动蛋白，并且需要真菌活力。此外，在某些菌株中，胶囊的存在与挤出的可能性呈负相关。总之，阿米巴原虫的非裂解性胞吐作用提供了与真菌-巨噬细胞相互作用的观察结果的另一个相似之处。这些结果为以下观点提供了额外的支持：在哺乳动物感染过程中观察到的某些毒力机制起源于环境相互作用，并通过环境相互作用进行选择。
Cryptococcus neoformans, an encapsulated, pathogenic yeast, is endowed with a variety of virulence factors, including a polysaccharide capsule. During mammalian infection, the outcome of the interaction between C. neoformans and macrophages is central to determining the fate of the host. Previous studies have shown similarities between the interaction of C. neoformans with macrophages and with amoebae, resulting in the proposal that fungal virulence for mammals originated from selection by amoeboid predators. In this study, we investigated the interaction of C. neoformans with the soil amoeba Acanthamoeba castellanii. Comparison of phagocytic efficiency of the wild type, nonencapsulated mutants, and complemented strains showed that the capsule was antiphagocytic for amoebae. Capsular enlargement was associated with a significant reduction in phagocytosis, suggesting that this phenomenon protects against ingestion by phagocytic predators. C. neoformans var. neoformans cells were observed to exit amoebae several hours after ingestion, in a process similar to the recently described nonlytic exocytosis from macrophages. Cryptococcal exocytosis from amoebae was dependent on the strain and on actin and required fungal viability. Additionally, the presence of a capsule was inversely correlated with the likelihood of extrusion in certain strains. In summary, nonlytic exocytosis from amoebae provide another parallel to observations in fungus-macrophage interactions. These results provide additional support for the notion that some mechanisms of virulence observed during mammalian infection originated, and were selected for, by environmental interactions.