Interleukin-8 up-regulation by neutrophil elastase is mediated by MyD88/IRAK/TRAF-6 in human bronchial epithelium
Interleukin-8 up-regulation by neutrophil elastase is mediated by MyD88/IRAK/TRAF-6 in human bronchial epithelium
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DOI：
10.1074/jbc.m103543200
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发表时间：
2001-09-21
影响因子：
4.8
通讯作者：
McElvaney, NG
中科院分区：
文献类型：
--
作者：
Walsh, DE;Greene, CM;McElvaney, NG
囊性纤维化在肺中的特征在于由嗜中性粒细胞弹性蛋白酶（NE）显著介导的嗜中性粒细胞主导的炎症。先前的工作表明NE诱导支气管上皮细胞白细胞介素-8（IL-8）基因表达和蛋白分泌。我们试图确定NE上调支气管上皮细胞IL-8的细胞内机制。结果表明，NE刺激16 HBE 14 o（-）细胞可诱导IL-8蛋白的产生和基因的表达。这两种反应被废除放线菌素D，表明调控是在转录水平。电泳迁移率改变实验显示NE刺激16 HBE 14 o（-）细胞后核因子κ B（NF κ B）被激活。Western blot分析表明NE激活NF κ B之前是I κ B蛋白的磷酸化和降解，主要是I κ B β。此外，我们观察到白细胞介素-1受体相关激酶（IRAK）在NE刺激的16 HBE 14 o（-）细胞中降解。通过发光测定法对IL-8报告基因活性的定量表明，显性负性MyD 88（MyD 88 Delta）或TRAF-6（TRAF-6 Delta）抑制响应于NE的IL-8报告基因表达。此外，MyD 88 Delta抑制NE诱导的IRAK降解。这些结果表明，NE通过涉及MyD 88和TRAF-6的IRAK信号通路诱导支气管上皮细胞中的IL-8基因上调，导致I kappaB β降解和NF kappaB核转位。这些发现可能对囊性纤维化疾病的治疗有意义。
Cystic fibrosis is characterized in the lungs by neutrophil-dominated inflammation mediated significantly by neutrophil elastase (NE). Previous work has shown that NE induces interleukin-8 (IL-8) gene expression and protein secretion in bronchial epithelial cells. We sought to determine the intracellular mechanisms by which NE up-regulates IL-8 in bronchial epithelial cells. The data show that stimulation of 16HBE14o(-) cells with NE induced IL-8 protein production and gene expression. Both responses were abrogated by actinomycin D, indicating that regulation is at the transcriptional level. Electrophoretic mobility shift assays demonstrated that nuclear factor kappaB (NF kappaB) was activated in 16HBE14o(-) cells stimulated with NE. Western blot analysis demonstrated that activation of NF kappaB by NE was preceded by phosphorylation and degradation of I kappaB proteins, principally I kappaB beta. In addition, we observed that interleukin-1 receptor-associated kinase (IRAK) was degraded in 16HBE14o(-) cells stimulated with NE. Quantification of IL-8 reporter gene activity by luminometry demonstrated that dominant negative MyD88 (MyD88 Delta) or TRAF-6 (TRAF-6 Delta) inhibited IL-8 reporter gene expression in response to NE. Furthermore, MyD88 Delta inhibited NE-induced IRAK degradation. These results show that NE induces IL-8 gene up-regulation in bronchial epithelial cells through an IRAK signaling pathway involving both MyD88 and TRAF-6, resulting in degradation of I kappaB beta and nuclear translocation of NF kappaB. These findings may have implications for therapeutic treatments in the cystic fibrosis condition.