Department of Pathology, College of Medicine, University of Vermont, 89 Beaumont Ave., Burlington, VT 05405, USA.
Am J Respir Cell Mol Biol. 2013 Mar;48(3):337-45. doi: 10.1165/rcmb.2012-0393OC. Epub 2012 Dec 13.
The respiratory epithelium plays a critical role in innate defenses against airborne pathogens and pollutants, and alterations in epithelial homeostasis and repair mechanisms are thought to contribute to chronic lung diseases associated with airway remodeling. Previous studies implicated the nicotinamide adenine dinucleotide phosphate-reduced oxidase dual oxidase-1 (DUOX1) in redox signaling pathways involved in in vitro epithelial wound responses to infection and injury. However, the importance of epithelial DUOX1 in in vivo epithelial repair pathways has not been established. Using small interfering (si)RNA silencing of DUOX1 expression, we show the critical importance of DUOX1 in wound responses in murine tracheal epithelial (MTE) cells in vitro, as well as its contribution to epithelial regeneration in vivo in a murine model of epithelial injury induced by naphthalene, a selective toxicant of nonciliated respiratory epithelial cells (club cells [Clara]). Whereas naphthalene-induced club-cell injury is normally followed by epithelial regeneration after 7 and 14 days, such airway reepithelialization was significantly delayed after the silencing of airway DUOX1 by oropharyngeal administration of DUOX1-targeted siRNA. Wound closure in MTE cells was related to DUOX1-dependent activation of the epidermal growth factor receptor (EGFR) and the transcription factor signal transducer and activator of transcription-3 (STAT3), known mediators of epithelial cell migration and wound responses. Moreover, in vivo DUOX1 silencing significantly suppressed naphthalene-induced activation of STAT3 and EGFR during early stages of epithelial repair. In conclusion, these experiments demonstrate for the first time an important function for epithelial DUOX1 in lung epithelial regeneration in vivo, by promoting EGFR-STAT3 signaling and cell migration as critical events in initial repair.
呼吸道上皮细胞在抵御空气传播病原体和污染物的先天防御中起着关键作用，上皮细胞动态平衡和修复机制的改变被认为是与气道重塑相关的慢性肺部疾病的原因。先前的研究表明，烟酰胺腺嘌呤二核苷酸磷酸还原氧化酶双氧化酶-1（DUOX1）参与了体外上皮细胞对感染和损伤的伤口反应中的氧化还原信号通路。然而，上皮细胞 DUOX1 在体内上皮修复途径中的重要性尚未确定。我们使用 DUOX1 表达的小干扰 (si)RNA 沉默，表明 DUOX1 在体外小鼠气管上皮 (MTE) 细胞的伤口反应中非常重要，以及它在萘诱导的上皮损伤的小鼠模型中对体内上皮再生的贡献，萘是一种非纤毛呼吸上皮细胞（克拉拉细胞 [Clara]）的选择性毒物。虽然萘诱导的克拉拉细胞损伤通常在 7 天和 14 天后会被上皮再生所取代，但在通过口咽给予靶向 DUOX1 的 siRNA 沉默气道 DUOX1 后，这种气道再上皮化明显延迟。MTE 细胞的伤口闭合与 DUOX1 依赖性激活表皮生长因子受体 (EGFR) 和转录因子信号转导和转录激活因子 3 (STAT3) 有关，这是上皮细胞迁移和伤口反应的已知介质。此外，体内 DUOX1 沉默显著抑制了萘诱导的上皮修复早期 STAT3 和 EGFR 的激活。总之，这些实验首次证明了上皮细胞 DUOX1 在体内肺上皮再生中的重要功能，通过促进 EGFR-STAT3 信号转导和细胞迁移作为初始修复的关键事件。
