Pseudomonas aeruginosa induces type-III-secretion-mediated apoptosis of macrophages and epithelial cells
Pseudomonas aeruginosa induces type-III-secretion-mediated apoptosis of macrophages and epithelial cells
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DOI：
10.1128/iai.67.10.5530-5537.1999
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发表时间：
1999-10-01
影响因子：
3.1
通讯作者：
Engel, JN
中科院分区：
文献类型：
--
作者：
Hauser, AR;Engel, JN
铜绿假单胞菌是一种革兰氏阴性条件致病菌，对多种真核细胞具有细胞毒性。为了研究该细菌对巨噬细胞的影响，我们在体外用铜绿假单胞菌菌株PA 103感染J774A.1细胞和原代骨髓来源的小鼠巨噬细胞，PA 103在感染2小时内引起巨噬细胞的III型分泌依赖性杀伤。只有一部分的杀伤需要假定的细胞毒素ExoU。通过三个标准，末端脱氧核苷酸转移酶介导的dUTP-生物素缺口末端标记法，细胞质核小体测定，和Hoechst染色，ExoU独立的，但III型分泌依赖的杀伤表现出凋亡的功能。细胞外细菌能够诱导细胞凋亡，并且铜绿假单胞菌的一些实验室和临床分离株诱导的这种形式的细胞死亡水平显著高于其他分离株。有趣的是，HeLa细胞，而不是Madin-Darby犬肾细胞在这些试验条件下对III型分泌介导的细胞凋亡敏感。这些发现与铜绿假单胞菌III型分泌系统转运至少两种杀死巨噬细胞的因子的模型一致：导致坏死的ExoU和诱导细胞凋亡的第二种尚未鉴定的效应蛋白。这种杀死可能有助于这种生物体在感染患者中持续存在和传播的能力。
Pseudomonas aeruginosa is a gram-negative opportunistic pathogen that is cytotoxic towards a variety of eukaryotic cells. To investigate the effect of this bacterium on macrophages, we infected J774A.1 cells and primary bone-marrow-derived murine macrophages with the P. aeruginosa strain PA103 in vitro, PA103 caused type-III-secretion-dependent killing of macrophages within 2 h of infection. Only a portion of the killing required the putative cytotoxin ExoU. By three criteria, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling assays, cytoplasmic nucleosome assays, and Hoechst staining, the ExoU-independent but type-III-secretion-dependent killing exhibited features of apoptosis. Extracellular bacteria were capable of inducing apoptosis, and some laboratory and clinical isolates of P. aeruginosa induced significantly higher levels of this form of cell death than others. Interestingly, HeLa cells but not Madin-Darby canine kidney cells were susceptible to type-III-secretion-mediated apoptosis under the conditions of these assays. These findings are consistent with a model in which the P. aeruginosa type III secretion system transports at least two factors that kill macrophages: ExoU, which causes necrosis, and a second, as yet unidentified, effector protein, which induces apoptosis. Such killing may contribute to the ability of this organism to persist and disseminate within infected patients.