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首页> 外文期刊>Infection and immunity >Tumor necrosis factor alpha binding to bacteria: evidence for a high-affinity receptor and alteration of bacterial virulence properties.
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Tumor necrosis factor alpha binding to bacteria: evidence for a high-affinity receptor and alteration of bacterial virulence properties.

机译：肿瘤坏死因子α与细菌的结合：高亲和力受体和细菌毒力特性改变的证据。

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Human and murine receptors for tumor necrosis factor alpha (TNF-alpha) are present on most somatic cells and have been characterized and cloned. In contrast, very little is currently known about whether TNF-alpha can bind to pathogens and whether such binding results in important biological consequences for the infected host. We now report that a number of gram-negative bacteria have receptors for TNF-alpha. Using 125I-labeled TNF-alpha, we show that Shigella flexneri has 276 receptors for TNF-alpha, with a Kd of 2.5 nM. The binding of labeled TNF-alpha to these bacterial receptors can be inhibited by cold TNF-alpha but not by cold TNF-beta. Binding of 125I-TNF-alpha to S. flexneri was inhibited by trypsin treatment of bacterial cells or incubation at 52 degrees C for 3 min. Monoclonal antibody to either the 55-kDa or the 75-kDa TNF-alpha receptor, which are present on different eukaryotic cells, had no effect on 125I-TNF-alpha binding to bacteria. A number of gram-negative bacteria were capable of binding 125I-TNF-alpha. Gram-positive bacteria bound significantly less 125I-TNF-alpha than gram-negative bacteria. Pretreatment of S. flexneri with TNF-alpha resulted in enhanced bacterial invasion of HeLa cells and enhanced uptake by human and murine macrophages. Pretreatment of HeLa cells with antibody to the 55-kDa TNF-alpha receptor abrogated enhanced invasion of HeLa cells by TNF-alpha-bacterium complexes. These results suggest that TNF-alpha-bacterium complexes can interact with TNF-alpha receptors present on eukaryotic cells. This report shows that gram-negative bacteria have receptors for TNF-alpha and that a virulence property of a bacterium is altered as a consequence of cytokine binding.
机译：肿瘤坏死因子α（TNF-alpha）的人类和鼠类受体存在于大多数体细胞中，并已被表征和克隆。相反，关于TNF-α是否可以结合病原体以及这种结合是否对被感染的宿主产生重要的生物学后果，目前知之甚少。现在我们报告许多革兰氏阴性细菌具有TNF-α的受体。使用125 I标记的TNF-α，我们显示弗氏志贺氏菌具有276个TNF-α受体，Kd为2.5 nM。标记的TNF-α与这些细菌受体的结合可以被冷TNF-α抑制，但不能被冷TNF-β抑制。通过胰蛋白酶处理细菌细胞或在52°C下孵育3分钟，可抑制125I-TNF-α与弗氏链球菌的结合。存在于不同真核细胞中的针对55-kDa或75-kDaTNF-α受体的单克隆抗体对125I-TNF-α与细菌的结合没有影响。许多革兰氏阴性细菌能够结合125I-TNF-α。革兰氏阳性细菌比革兰氏阴性细菌结合的125I-TNF-α明显更少。用TNF-α对弗氏链球菌进行预处理导致HeLa细胞的细菌入侵增强，人和鼠巨噬细胞的摄取也增强。用针对55kDaTNF-α受体的抗体对HeLa细胞进行预处理，可以消除TNF-α-细菌复合物对HeLa细胞的侵袭。这些结果表明，TNF-α-细菌复合物可以与真核细胞上存在的TNF-α受体相互作用。该报告表明，革兰氏阴性细菌具有TNF-α受体，并且由于细胞因子的结合，细菌的毒性特性也发生了变化。

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