Shiga toxin produced by enterohemorrhagic Escherichia coli inhibits PI3K/NF-κB signaling pathway in globotriaosylceramide-3-negative human intestinal epithelial cells
Shiga toxin produced by enterohemorrhagic Escherichia coli inhibits PI3K/NF-κB signaling pathway in globotriaosylceramide-3-negative human intestinal epithelial cells
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DOI：
10.4049/jimmunol.178.12.8168
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发表时间：
2007-06-15
影响因子：
4.4
通讯作者：
Martin, Christine
中科院分区：
文献类型：
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作者：
Gobert, Alain P.;Vareille, Marjolaine;Martin, Christine
肠出血性大肠杆菌 (EHEC) 产生的志贺毒素 (Stx) 与表达 globotriaosylceramide-3 (Gb-3) 的内皮细胞结合，并通过抑制翻译来诱导细胞死亡。尽管如此，Stx 对缺乏受体 Gb-3 的人类肠细胞的影响仍鲜为人知。在这项研究中，我们质疑 EHEC 衍生的 Stx 是否可以调节 Gb-3 阴性人上皮细胞系 T84 中的细胞信号传导。 EHEC产生的Stx被细胞固定并内化。 EHEC 感染后，在 T84 细胞中观察到 NV-kappa B 的微弱激活。感染缺乏 stx1 和 stx2（编码 Stx 的基因）的同基因突变体的细胞表现出增强的 NF-κ B DNA 结合活性。因此，与野生型菌株相比，感染 Stx 突变体的 T84 细胞中 NF-κ B 依赖性 CCL20 和 IL-8 基因转录和趋化因子产生增强。通过研究 Stx 调节 NF-kappa B 激活的机制，我们发现 PI3K/Akt 信号通路不是由 EHEC 诱导的，而是由缺乏 Stx 的菌株增强的。在 EHEC Delta Stx 感染的 T84 细胞中对 PI3K/Akt 信号传导的药理学抑制导致 NF-κ B 激活以及 CCL20 和 IL-8 mRNA 表达完全降低。这表明 PI3K/Akt/NF-kappa B 途径的诱导可能由 EHEC 诱导，但在 Gb-3 阴性上皮细胞中被 Stx 抑制。因此，Stx 是一种未被识别的人类肠上皮细胞先天免疫反应调节剂。
Shiga toxin (Stx) produced by enterohemorrhagic Escherichia coli (EHEC) binds to endothelial cells expressing globotriaosylceramide-3 (Gb-3) and induces cell death by inhibiting translation. Nonetheless, the effects of Stx on human enterocytes, which lacks receptor Gb-3, remain less known. In this study, we questioned whether EHEC-derived Stx may modulate cellular signalization in the Gb-3-negative human epithelial cell line T84. Stx produced by EHEC was fixed and internalized by the cells. A weak activation of NV-kappa B was observed in T84 cells after EHEC infection. Cells infected with an isogenic mutant lacking stx1 and stx2, the genes encoding Stx, displayed an increased NF-kappa B DNA-binding activity. Consequently, the NF-kappa B-dependent CCL20 and IL-8 gene transcription and chemokine production were enhanced in T84 cells infected with the Stx mutant in comparison to the wild-type strain. Investigating the mechanism by which Stx modulates NF-kappa B activation, we showed that the PI3K/Akt signaling pathway was not induced by EHEC but was enhanced by the strain lacking Stx. Pharmacological inhibition of the PI3K/Akt signalization in EHEC Delta Stx-infected T84 cells yielded to a complete decrease of NF-kappa B activation and CCL20 and IL-8 mRNA expression. This demonstrates that the induction of the PI3K/Akt/NF-kappa B pathway is potentially induced by EHEC, but is inhibited by Stx in Gb-3-negative epithelial cells. Thus, Stx is an unrecognized modulator of the innate immune response of human enterocytes.