Neutrophil elastase induces MUC5AC gene expression in airway epithelium via a pathway involving reactive oxygen species
Neutrophil elastase induces MUC5AC gene expression in airway epithelium via a pathway involving reactive oxygen species
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DOI：
10.1165/ajrcmb.26.4.4473
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发表时间：
2002-04-01
影响因子：
6.4
通讯作者：
Voynow, JA
中科院分区：
文献类型：
--
作者：
Fischer, BM;Voynow, JA
嗜中性粒细胞为主的气道炎症和气道粘液阻塞是慢性气道疾病的主要病理特征，包括囊性纤维化和慢性支气管炎。中性粒细胞释放弹性蛋白酶，这是一种丝氨酸蛋白酶，可损害粘膜纤毛清除并刺激杯状细胞化生和粘蛋白产生。我们以前报道过中性粒细胞弹性蛋白酶通过增强mRNA的稳定性来增加主要呼吸道粘蛋白基因MUC5AC的表达。然而，弹性蛋白酶调节MUC5AC表达的分子机制尚不清楚。我们假设弹性蛋白酶处理产生的活性氧介导MUC5AC基因表达。为了验证这一假设，A549，呼吸道上皮细胞系，在存在或不存在氧自由基清除剂二甲基硫脲或铁螯合剂去铁胺的情况下用弹性蛋白酶处理。通过北方分析评估MUC5AC mRNA水平。两种抗氧化剂均显著抑制弹性蛋白酶诱导的MUC5AC基因表达。二甲基硫脲也抑制中性粒细胞弹性蛋白酶（NE）诱导的MUC5AC在正常人支气管上皮细胞表达的增加。为了确定弹性蛋白酶处理是否产生活性氧，A549和正常人支气管上皮细胞负载有二氯二氢荧光素，氧化应激的荧光指示剂。NE治疗增加了两种细胞类型的细胞荧光，指示细胞内活性氧的产生：我们得出结论，NE治疗增加MUC5AC基因表达的氧化剂依赖性机制。
Neutrophil-predominant airway inflammation and mucus obstruction of the airways are major pathologic features of chronic airway diseases, including cystic fibrosis and chronic bronchitis. Neutrophils release elastase, a serine protease that impairs mucociliary clearance and stimulates goblet cell metaplasia and mucin production. We previously reported that neutrophil elastase increases expression of a major respiratory mucin gene, MUC5AC, by enhancing mRNA stability. However, the molecular mechanisms of elastase-regulated MUC5AC expression are not known. We hypothesized that reactive oxygen species, generated by elastase treatment, mediate MUC5AC gene expression. To test this hypothesis, A549, a respiratory epithelial cell line, was treated with elastase in tine presence or absence of the oxygen radical scavenger, dimethylthiourea, or the iron chelator, desferrioxamine. MUC5AC mRNA levels were assessed by Northern analysis. Both antioxidants significantly inhibited elastase-induced MUC5AC gene expression. Dimethylthiourea also inhibited the neutrophil elastase (NE)-induced increase in MUC5AC expression in normal human bronchial epithelial cells. To determine whether elastase treatment generated reactive oxygen species, A549 and normal human bronchial epithelial cells were loaded with dichlorodihydrofluorescein, a fluorescent indicator of oxidative stress. NE treatment increased cellular fluorescence in both cell types, undicating generation of intracellular reactive oxygen species: We conclude that NE treatment increases MUC5AC gene expression by an oxidant-dependent mechanism.