McGraw Matthew D, Rioux Jaqueline S, Garlick Rhonda B, Rancourt Raymond C, White Carl W, Veress Livia A
Department of Pediatric Pulmonology, University of Colorado Denver, Aurora, Colorado, USA.
Pediatric Pulmonary Division, The Breathing Institute at Children's Hospital Colorado, Aurora, Colorado, USA.
Toxicol Sci. 2017 Jun 1;157(2):399-409. doi: 10.1093/toxsci/kfx057.
Sulfur mustard (SM) is a chemical warfare agent that causes chronic airway remodeling. This study's objective was to assess for changes to the bronchiolar epithelium after SM exposure to explain its contribution to chronic airway remodeling.
Adult male rats were exposed to a sublethal dose of SM inhalation (1.0-1.2 mg/kg) for 50 min. Histological sections of the bronchiolar epithelium were analyzed for changes using hematoxylin and eosin, trichrome, and immunofluorescent staining for acetylated tubulin (AT) and club cell secretory protein (CCSP). CCSP in bronchoalveolar lavage fluid was assessed using western blot. A bromodeoxyuridine (BRDU) assay was used to assess for epithelial proliferation, and real-time PCR measured changes in Notch mRNA expression.
SM caused significant proximal bronchiolar epithelial injury with epithelial denudation, loss of acetylated tubulin and CCSP staining, and reduced bronchoalveolar lavage fluid CCSP levels. bromodeoxyuridine (BRDU) + staining of proximal bronchiolar epithelial cells was not increased, but staining was increased in the distal bronchiolar epithelium. One month after injury, the proximal bronchiolar epithelium was not fully repaired. Significant collagen deposition surrounded proximal bronchioles with luminal obstruction, consistent with bronchiolitis obliterans. These changes corresponded with a downregulation of Notch1, Notch3, and Hes1 mRNA expressions.
This study demonstrates that SM exposure resulted in severe proximal airway epithelial injury, persistent morphological changes, impaired epithelial proliferation and, ultimately, bronchiolitis obliterans. These changes occurred at the same time that the Notch signaling genes were downregulated. Thus, the lung epithelium and the Notch signaling pathway may be worthy targets for the prevention of chronic airway remodeling after SM inhalation injury.
硫芥（SM）是一种可导致慢性气道重塑的化学战剂。本研究的目的是评估SM暴露后细支气管上皮的变化，以解释其对慢性气道重塑的作用。
成年雄性大鼠吸入亚致死剂量的SM（1.0 - 1.2毫克/千克）50分钟。使用苏木精和伊红、三色染色以及乙酰化微管蛋白（AT）和克拉拉细胞分泌蛋白（CCSP）的免疫荧光染色分析细支气管上皮的组织学切片变化。使用蛋白质印迹法评估支气管肺泡灌洗液中的CCSP。使用溴脱氧尿苷（BRDU）检测法评估上皮细胞增殖，实时聚合酶链反应测量Notch mRNA表达的变化。
SM导致近端细支气管上皮严重损伤，上皮剥脱，乙酰化微管蛋白和CCSP染色缺失，支气管肺泡灌洗液中CCSP水平降低。近端细支气管上皮细胞的溴脱氧尿苷（BRDU）+染色未增加，但远端细支气管上皮中的染色增加。损伤后1个月，近端细支气管上皮未完全修复。近端细支气管周围有明显的胶原沉积，管腔阻塞，符合闭塞性细支气管炎。这些变化与Notch1、Notch3和Hes1 mRNA表达的下调相对应。
本研究表明，SM暴露导致严重的近端气道上皮损伤、持续的形态学变化、上皮细胞增殖受损，最终导致闭塞性细支气管炎。这些变化与Notch信号基因下调同时发生。因此，肺上皮和Notch信号通路可能是预防SM吸入性损伤后慢性气道重塑的有价值靶点。
