Neutrophil Elastase Represses IL-8/CXCL8 Synthesis in Human Airway Smooth Muscle Cells through Induction of NF-κB Repressing Factor
Neutrophil Elastase Represses IL-8/CXCL8 Synthesis in Human Airway Smooth Muscle Cells through Induction of NF-κB Repressing Factor
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DOI：
10.4049/jimmunol.0803729
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发表时间：
2009-07-01
影响因子：
4.4
通讯作者：
Kuo, Han-Pin
中科院分区：
文献类型：
--
作者：
Ho, Shu-Chuan;Lee, Kang-Yun;Kuo, Han-Pin
核因子-kappaB抑制因子(NRF)是一种核转录因子kappa B的核转录抑制因子，在特异性核因子-kappaB靶向基因，包括干扰素-β、IL-8/CXCL8和诱导型一氧化氮合酶的基础沉默中具有结构性表达。关于NRF的调节及其在刺激反应中的作用，人们知之甚少。气道平滑肌(ASM)是炎症介质的丰富来源，可能调节呼吸道炎症的发生和发展。我们先前已经报道，NE激活原代人ASM中的核因子-kappa B，导致转化生长因子-β1的诱导。在本研究中，我们描述了NE不是诱导核因子-kappa B反应基因IL-8/CXCL8，而是抑制hASM细胞中IL-8/CXCL8的释放和mRNA的表达。用放线菌素D进行的转录阻断研究显示，在NE存在或不存在的情况下，IL-8/CXCL8 mRNA的降解率相似，提示在转录水平上参与了这一过程。RT-PCR和Western blotting表明，从机制上讲，NE抑制效应是通过诱导NRF介导的，而NRF随后被招募到天然的IL-8/CXCL8启动子上，导致RNA聚合酶II从启动子上移除，染色质免疫沉淀分析表明。小干扰RNA阻断NRF可阻断NE对IL-8/CXCL8表达的抑制。相反，去甲肾上腺素不能诱导A549和BEAS-2B细胞表达NRF，而NE只刺激核因子-kappaB的活化和IL-8/CXCL8的诱导。NRF表达载体强迫A549细胞表达NRF可抑制IL-8/CXCL8的表达。因此，我们描述了NE诱导的NRF的一种新的负性调节机制，该机制仅限于hASM，并介导抑制IL-8/CXCL8的表达。免疫学杂志，2009,183：411-420。
NF-kappa B repressing factor (NRF), a nuclear inhibitor of NF-kappa B, is constitutively expressed and is implicated in the basal silencing of specific NF-kappa B targeting genes, including IFN-beta, IL-8/CXCL8, and iNOS. Little is known about the regulation of NRF and its role in response to stimuli. Airway smooth muscle (ASM) is a rich source of inflammatory mediators that may regulate the development and progression of airway inflammation. We have previously reported that NE activates NF-kappa B in primary human ASM (hASM), leading to induction of TGF-beta 1. In this study, we describe that, instead of inducing the NF-kappa B response gene IL-8/CXCL8, NE suppressed IL-8/CXCL8 release and mRNA expression in hASM cells. Transcriptional blockade studies using actinomycin D revealed a similar degradation rate of IL-8/CXCL8 mRNA in the presence or absence of NE, suggesting an involvement at the transcription level. Mechanistically, the NE repressive effect was mediated by inducing NRF, as shown by RT-PCR and Western blotting, which was subsequently recruited to the native IL-8/CXCL8 promoter leading to removal of RNA polymerase II from the promoter, as demonstrated by chromatin immunoprecipitation assays. Knockdown of NRF by small interfering RNA prevented NE-induced suppression of IL-8/CXCL8 expression. In contrast, NE did not induce NRF expression in A549 and Beas-2B cells, where NE only stimulates NF-kappa B activation and IL-8/CXCL8 induction. Forced expression of NRF in A549 cells by an NRF expression plasmid suppressed IL-8/CXCL8 expression. Hence, we describe a novel negative regulatory mechanism of NE-induced NRF, which is restricted to hASM and mediates the suppression of IL-8/CXCL8 expression. The Journal of Immunology, 2009, 183: 411-420.