Cytotoxic necrotizing factor type 1 delivered by outer membrane vesicles of uropathogenic Escherichia coli attenuates polymorphonuclear leukocyte antimicrobial activity and chemotaxis
Cytotoxic necrotizing factor type 1 delivered by outer membrane vesicles of uropathogenic Escherichia coli attenuates polymorphonuclear leukocyte antimicrobial activity and chemotaxis
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DOI：
10.1128/iai.00637-06
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发表时间：
2006-08-01
影响因子：
3.1
通讯作者：
O'Brien, Alison D.
中科院分区：
文献类型：
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作者：
Davis, Jon M.;Carvalho, Humberto M.;O'Brien, Alison D.
细胞毒性坏死因子 1 型 (CNF1) 是一种由许多尿路致病性大肠杆菌 (UPEC) 菌株产生的毒素，通过使这些靶蛋白内的单个氨基酸脱酰胺，持续激活 Rho 家族的小 GTP 酶。这种激活的 GTP 酶不仅会刺激受影响细胞内的肌动蛋白聚合，而且正如我们之前报道的那样，还会降低小鼠多形核白细胞 (PMN) 的膜流动性。在同一研究中，我们发现这种膜运动的减弱阻碍了补体受体 CD11b/CD18 在 PMN 上的聚集，进而降低了 PMN 的吞噬能力和与表达 CNF1 的 UPEC 直接接触的 PMN 以及接近野生型 UPEC 的 PMN 的杀菌活性。后一个观察结果向我们表明，CNF1 是从邻近细菌释放的，尽管在本文所述的研究开始时，尚未描述从 UPEC 输出 CNF1 的具体机制。在这里，我们提供了证据，表明 CNF1 是从表达 CNF1 的 UPEC 菌株 CP9（血清型 O4/H5/K54）中释放出来的，与外膜囊泡（OMV）形成复合物，并且这些携带 CNF1 的囊泡将具有生物活性的 CNF1 转移到 PMN 并减弱吞噬细胞功能。此外，我们发现携带 CNF1 的囊泡以剂量依赖性方式作用于 PMN，抑制其对甲酰基 Met-Leu-Phe 的趋化反应，而纯化的 CNF1 则不然。我们得出的结论是，OMV 提供了一种将 CNF1 从 UPEC 菌株传递到 PMN 的方法，从而对这些生物体的急性炎症反应的功效产生负面影响。
Cytotoxic necrotizing factor type 1 (CNF1), a toxin produced by many strains of uropathogenic Escherichia coli (UPEC), constitutively activates small GTPases of the Rho family by deamidating a single amino acid within these target proteins. Such activated GTPases not only stimulate actin polymerization within affected cells but also, as we previously reported, decrease membrane fluidity on mouse polymorphonuclear leukocytes (PMNs). In that same investigation we found that this diminished membrane movement impedes the clustering of the complement receptor CD11b/CD18 on PMNs and, in turn, decreases PMN phagocytic capacity and microbicidal activity on PMNs in direct contact with CNF1-expressing UPEC as well as on those in proximity to wild-type UPEC. The latter observation suggested to us that CNF1 is released from neighboring bacteria, although at the time of initiation of the study described here, no specific mechanism for export of CNF1 from UPEC had been described. Here we present evidence that CNF1 is released from the CNF1-expressing UPEC strain CP9 (serotype O4/H5/K54) in a complex with outer membrane vesicles (OMVs) and that these CNF1-bearing vesicles transfer biologically active CNF1 to PMNs and attenuate phagocyte function. Furthermore, we show that CNF1-bearing vesicles act in a dose-dependent fashion on PMNs to inhibit their chemotactic response to formyl-Met-Leu-Phe, while purified CNF1 does not. We conclude that OMVs provide a means for delivery of CNF1 from a UPEC strain to PMNs and thus negatively affect the efficacy of the acute inflammatory response to these organisms.