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首页> 外文期刊>Infection and immunity >Enterococcus faecalis Bearing Aggregation Substance Is Resistant to Killing by Human Neutrophils despite Phagocytosis and Neutrophil Activation
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Enterococcus faecalis Bearing Aggregation Substance Is Resistant to Killing by Human Neutrophils despite Phagocytosis and Neutrophil Activation

机译：尽管吞噬作用和嗜中性粒细胞活化，但带有聚集物质的粪肠球菌却能抵抗人类嗜中性粒细胞的杀伤

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Enterococcus faecalis aggregation substance (AS) mediates efficient bacterium-bacterium contact to facilitate plasmid exchange as part of a bacterial sex pheromone system. We have previously determined that AS promotes direct, opsonin-independent binding of E. faecalis to human neutrophils (PMNs) via complement receptor type 3 and other receptors on the PMN surface. We have now examined the functional consequences of this bacterium-host cell interaction. AS-bearing E. faecalis was phagocytosed and internalized by PMNs, as determined by deconvolution fluorescence microscopy. However, these bacteria were not killed by PMNs, and internalized bacteria excluded propidium iodide, indicating intact bacterial membranes. Resistance to killing occurred despite activation of PMNs, as indicated by an increase in both functional and total surface Mac-1 expression, shedding of l-selectin, and an increase in PMN extracellular superoxide and phagosomal oxidant production. Deconvolution fluorescence microscopy also revealed that phagosomes containing AS-bearing bacteria were markedly larger than phagosomes containing opsonized E. faecalis, suggesting that some modification of phagosomal maturation may be involved in AS-induced resistance to killing. PMN phagosomal pH was significantly higher after ingestion of nonopsonized AS-bearing E. faecalis than after that of opsonized bacteria. The novel ability of AS to promote intracellular survival of E. faecalisinside PMNs suggests that AS may be a virulence factor used by strains of E. faecalis.
机译：粪肠球菌聚集物质（AS）介导有效的细菌与细菌接触，促进作为细菌性信息素系统一部分的质粒交换。我们先前已经确定AS促进 E的直接，调理素独立结合。粪便通过3型补体受体和PMN表面上的其他受体感染人中性粒细胞（PMN）。现在我们已经检查了这种细菌与宿主细胞相互作用的功能后果。带有AS的 E。通过反卷积荧光显微镜检测，粪便被PMN吞噬并内在化。但是，这些细菌并未被PMN杀死，并且内在细菌排除了碘化丙啶，表明细菌膜完整。尽管激活了PMNs，但仍产生了对杀伤的抗性，如功能性和总体表面Mac-1表达的增加，l-选择素的脱落以及PMN细胞外超氧化物和吞噬体氧化剂产量的增加所表明的。反卷积荧光显微镜检查还显示，含有AS细菌的吞噬体明显大于含有调理过的 E的吞噬体。粪便，表明吞噬体成熟的某些改变可能与AS诱导的杀伤抗性有关。摄入非调理的带AS的 E后，PMN吞噬体的pH值明显更高。粪便比调理细菌后要大。 AS促进 E细胞内存活的新颖能力。粪便中的PMNs提示AS可能是 E菌株使用的一种致病因子。粪便。

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