Induction of TLR-2 and TLR-5 expression by Helicobacter pylori switches cagPAI-dependent signalling leading to the secretion of IL-8 and TNF-α.
Induction of TLR-2 and TLR-5 expression by Helicobacter pylori switches cagPAI-dependent signalling leading to the secretion of IL-8 and TNF-α.
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DOI：
10.1371/journal.pone.0019614
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发表时间：
2011-05-09
期刊：
影响因子：
3.7
通讯作者：
Backert S
中科院分区：
文献类型：
--
作者：
Kumar Pachathundikandi S;Brandt S;Madassery J;Backert S
幽门螺杆菌是胃炎、胃溃疡甚至胃癌的病原体。强毒菌株携带编码 IV 型分泌系统 (T4SS) 的 cag 致病岛 (cagPAI)，用于注射 CagA 蛋白。然而，通过 Toll 样受体 (TLR) 感知这种病原体的机制以及不同病理发展中的下游信号通路尚不清楚。在这里，我们探讨了野生型幽门螺杆菌和同基因 cagPAI 突变体感染过程中 TLR-2 和 TLR-5 在 THP-1 细胞和 HEK293 细胞系（稳定转染 TLR-2 或 TLR-5）中的参与情况。幽门螺杆菌在 THP-1、HEK293-TLR2 和 HEK293-TLR5 细胞中触发 TLR-2 和 TLR-5 表达增强，但在 HEK293 对照中则不然。此外，THP-1细胞中IL-8和TNF-α细胞因子的分泌是以cagPAI依赖性方式诱导的。此外，我们发现 HEK293 细胞不能摄取 T4SS 传递的 CagA，因此非常适合在缺乏 T4SS 功能的情况下研究 TLR 信号传导。 HEK293对照细胞在感染期间不诱导TLR-2和TLR-5表达，仅分泌少量细胞因子，这与T4SS功能缺失一致。相比之下，HEK293-TLR2和HEK293-TLR5细胞非常有能力以不依赖于cagPAI的方式诱导IL-8和TNF-α细胞因子的分泌，这表明TLR-2或TLR-5的表达深刻地改变了感染时触发促炎信号传导的能力。使用磷酸特异性抗体和荧光素酶报告基因检测，我们进一步证明幽门螺杆菌以 TLR 依赖性方式诱导 IRAK-1 和 IκB 磷酸化，这是激活转录因子 NF-κB 所必需的。最后，通过表达从细胞质转位到细胞核的p65-GFP证实了HEK293-TLR2和HEK293-TLR5细胞中NF-κB的激活。这些数据表明，幽门螺杆菌诱导的 TLR-2 和 TLR-5 表达可以定性地将依赖于 cagPAI 的促炎症信号通路转变为不依赖于 cagPAI 的促炎信号通路，可能对幽门螺杆菌相关疾病的结果产生影响。
Helicobacter pylori is the causative agent for developing gastritis, gastric ulcer, and even gastric cancer. Virulent strains carry the cag pathogenicity island (cagPAI) encoding a type-IV secretion system (T4SS) for injecting the CagA protein. However, mechanisms of sensing this pathogen through Toll-like receptors (TLRs) and downstream signalling pathways in the development of different pathologies are widely unclear. Here, we explored the involvement of TLR-2 and TLR-5 in THP-1 cells and HEK293 cell lines (stably transfected with TLR-2 or TLR-5) during infection with wild-type H. pylori and isogenic cagPAI mutants. H. pylori triggered enhanced TLR-2 and TLR-5 expression in THP-1, HEK293-TLR2 and HEK293-TLR5 cells, but not in the HEK293 control. In addition, IL-8 and TNF-α cytokine secretion in THP-1 cells was induced in a cagPAI-dependent manner. Furthermore, we show that HEK293 cells are not competent for the uptake of T4SS-delivered CagA, and are therefore ideally suited for studying TLR signalling in the absence of T4SS functions. HEK293 control cells, which do not induce TLR-2 and TLR-5 expression during infection, only secreted cytokines in small amounts, in agreement with T4SS functions being absent. In contrast, HEK293-TLR2 and HEK293-TLR5 cells were highly competent for inducing the secretion of IL-8 and TNF-α cytokines in a cagPAI-independent manner, suggesting that the expression of TLR-2 or TLR-5 has profoundly changed the capability to trigger pro-inflammatory signalling upon infection. Using phospho-specific antibodies and luciferase reporter assays, we further demonstrate that H. pylori induces IRAK-1 and IκB phosphorylation in a TLR-dependent manner, and this was required for activation of transcription factor NF-κB. Finally, NF-κB activation in HEK293-TLR2 and HEK293-TLR5 cells was confirmed by expressing p65-GFP which was translocated from the cytoplasm into the nucleus. These data indicate that H. pylori-induced expression of TLR-2 and TLR-5 can qualitatively shift cagPAI-dependent to cagPAI-independent pro-inflammatory signalling pathways with possible impact on the outcome of H. pylori-associated diseases.
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影响因子：
8.7
作者：
Beutler B
通讯作者：
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影响因子：
7.7
作者：
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DOI：
10.1073/pnas.0502040102
发表时间：
2005-06-28
影响因子：
11.1
作者：
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通讯作者：
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