Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
Department of Environmental Health Sciences, Soonchunhyang University, Asan, Korea.
J Korean Med Sci. 2020 Aug 17;35(32):e272. doi: 10.3346/jkms.2020.35.e272.
Exposure to ozone (O₃) induces neutrophilic inflammation and goblet cell hyperplasia in humans and experimental animals. Because the solute carrier family 26-member 4 (Slc26a4; pendrin) gene induces mucin production and intraluminal acidification in the airways, it was hypothesized to be a key molecule in O₃-induced airway injury. Thus, we evaluated the role of Slc26a4 and the protective effects of ammonium chloride (NH₄Cl) in O₃-induced airway injury in mice.
Six-week-old female BALB/c mice were exposed to filtered air or O₃ for 21 days (2 ppm for 3 hr/day). NH₄Cl (0, 0.1, 1, and 10 mM) was administered intratracheally into the airways. Airway resistance was measured using a flexiVent system, and bronchoalveolar lavage fluid (BALF) cells were differentially counted. Slc26a4 and Muc5ac proteins and mRNA were measured via western blotting, real-time polymerase chain reaction, and immunostaining. Tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-17, IL-1β, and caspase-1 were analyzed via western blotting.
The levels Slc26a4 protein and mRNA significantly increased in lung tissues from Day 7 to Day 21 of O₃ exposure, with concomitant increases in lung resistance, numbers of goblet cells in lung tissues, and inflammatory cells and thiocyanate (SCN) levels in BALF in a time-dependent manner. Treatment with NH₄Cl significantly reduced these changes to levels similar to those of sham-treated mice, with a concomitant reduction of Slc26a4 proteins in lung lysates and SCN levels in BALF. Slc26a4 protein was co-expressed with muc5ac protein in the bronchial epithelium, as indicated by immunofluorescence staining. NH₄Cl treatment also significantly attenuated the O₃-induced increases in IFN-γ, TNF-α, IL-17, IL-1β, and p20-activated caspase-1.
Slc26a4 may be involved in O₃-induced inflammatory and epithelial changes in the airways via activation of the inflammasome and the induction of IL-17 and IFN-γ. NH₄Cl shows a potential as a therapeutic agent for controlling O₃-induced airway inflammation and epithelial damage by modulating Slc26a4 expression.
臭氧（O₃）暴露会引起人类和实验动物的中性粒细胞炎症和杯状细胞增生。由于溶质载体家族 26 成员 4（Slc26a4；pendrin）基因诱导气道中的黏液产生和管腔内酸化，因此它被假设为 O₃ 诱导的气道损伤的关键分子。因此，我们评估了 Slc26a4 的作用以及氯化铵（NH₄Cl）在 O₃ 诱导的气道损伤中的保护作用在小鼠中。
6 周龄雌性 BALB/c 小鼠暴露于过滤空气或 O₃ 21 天（每天 2 ppm，3 小时/天）。NH₄Cl（0、0.1、1 和 10 mM）通过气管内给药进入气道。使用 flexiVent 系统测量气道阻力，并对支气管肺泡灌洗液（BALF）细胞进行差异计数。通过 Western blot、实时聚合酶链反应和免疫染色测量 Slc26a4 和 Muc5ac 蛋白和 mRNA。通过 Western blot 分析肿瘤坏死因子（TNF）-α、干扰素（IFN）-γ、白细胞介素（IL）-17、IL-1β 和半胱天冬酶-1。
臭氧暴露第 7 天至第 21 天，肺组织中 Slc26a4 蛋白和 mRNA 水平显著增加，肺阻力、肺组织中杯状细胞数量以及 BALF 中的炎症细胞和硫氰酸盐（SCN）水平均呈时间依赖性增加。NH₄Cl 治疗显著降低了这些变化，使其与假手术处理的小鼠相似，同时降低了肺裂解物中的 Slc26a4 蛋白和 BALF 中的 SCN 水平。免疫荧光染色表明，Slc26a4 蛋白与支气管上皮中的 muc5ac 蛋白共表达。NH₄Cl 治疗还显著减弱了 O₃ 诱导的 IFN-γ、TNF-α、IL-17、IL-1β 和 p20 激活的半胱天冬酶-1 的增加。
Slc26a4 可能通过激活炎症小体并诱导 IL-17 和 IFN-γ，参与 O₃ 诱导的气道炎症和上皮变化。NH₄Cl 通过调节 Slc26a4 表达，显示出作为控制 O₃ 诱导的气道炎症和上皮损伤的治疗剂的潜力。
