Role of extracellular superoxide in neutrophil activation: interactions between xanthine oxidase and TLR4 induce proinflammatory cytokine production
Role of extracellular superoxide in neutrophil activation: interactions between xanthine oxidase and TLR4 induce proinflammatory cytokine production
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DOI：
10.1152/ajpcell.00454.2007
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发表时间：
2008-04-01
影响因子：
5.5
通讯作者：
Abraham, Edward
中科院分区：
文献类型：
--
作者：
Lorne, Emmanuel;Zmijewski, Jaroslaw W.;Abraham, Edward
活性氧（ROS）有助于中性粒细胞活化和急性炎症过程的发展，其中中性粒细胞发挥核心作用。然而，关于细胞外活性氧（尤其是超氧化物等细胞膜不可渗透物质）增强中性粒细胞促炎性特性的机制，目前的信息有限。为了解决这个问题，中性粒细胞暴露于黄嘌呤氧化酶和次黄嘌呤或鲁马嗪的超氧化物生成组合。细胞外超氧化物生成诱导核因子-κ B（NF-κ B）的核转位，并增加中性粒细胞产生NF-κ B依赖性细胞因子肿瘤坏死因子-α（TNF-α）和巨噬细胞抑制蛋白-2（MIP-2）。相反，当缺乏Toll样受体-4（TLR4）的中性粒细胞暴露于细胞外超氧化物时，TNF-α或MIP-2的表达没有变化。免疫沉淀，共聚焦显微镜，和荧光共振能量转移（FRET）的研究表明TLR4和黄嘌呤氧化酶之间的关联。中性粒细胞暴露于肝素减弱黄嘌呤氧化酶与细胞表面的结合以及与TLR4的相互作用。肝素还降低了黄嘌呤氧化酶诱导的NF-κ B核转位以及促炎细胞因子的产生。这些结果表明，细胞外超氧化物对中性粒细胞具有促炎作用，主要通过TLR 4依赖性机制起作用，该机制增强NF-κ B B的核转位并增加NF-κ B依赖性细胞因子的表达。
Reactive oxygen species ( ROS) contribute to neutrophil activation and the development of acute inflammatory processes in which neutrophils play a central role. However, there is only limited information concerning the mechanisms through which extracellular ROS, and particularly cell membrane-impermeable species, such as superoxide, enhance the proin-flammatory properties of neutrophils. To address this issue, neutrophils were exposed to superoxide generating combinations of xanthine oxidase and hypoxanthine or lumazine. Extracellular superoxide generation induced nuclear translocation of nuclear factor-kappa B ( NF-kappa B) and increased neutrophil production of the NF-kappa B-dependent cytokines tumor necrosis factor-alpha ( TNF-alpha) and macrophage inhibitory protein-2 ( MIP-2). In contrast, there were no changes in TNF-alpha or MIP-2 expression when neutrophils lacking Toll-like receptor-4 ( TLR4) were exposed to extracellular superoxide. Immunoprecipitation, confocal microscopy, and fluorescence resonance energy transfer ( FRET) studies demonstrated association between TLR4 and xanthine oxidase. Exposure of neutrophils to heparin attenuated binding of xanthine oxidase to the cell surface as well as interactions with TLR4. Heparin also decreased xanthine oxidase-induced nuclear translocation of NF-kappa B as well as production of proinflammatory cytokines. These results demonstrate that extracellular superoxide has proinflammatory effects on neutrophils, predominantly acting through an TLR4-dependent mechanism that enhances nuclear translocation of NF-kappa B and increases expression of NF-kappa B-dependent cytokines.