Effects of Ammonium Chloride on Ozone-induced Airway Inflammation: the Role of Slc26a4 in the Lungs of Mice

Abstract

Background: Exposure to ozone (O 3) 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 O 3-induced airway injury. Thus, we evaluated the role of Slc26a4 and the protective effects of ammonium chloride (NH 4 Cl) in O 3-induced airway injury in mice. Methods: Six-week-old female BALB/c mice were exposed to filtered air or O 3 for 21 days (2 ppm for 3 hr/day). NH 4 Cl (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. Results: The levels Slc26a4 protein and mRNA significantly increased in lung tissues from Day 7 to Day 21 of O 3 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 NH 4 Cl 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. NH 4 Cl treatment also significantly attenuated the O 3-induced increases in IFN-γ, TNF-α, IL-17, IL-1β, and p20activated caspase-1. Conclusion: Slc26a4 may be involved in O 3-induced inflammatory and epithelial changes in the airways via activation of the inflammasome and the induction of IL-17 and IFN-γ. NH 4 Cl shows a potential as a therapeutic agent for controlling O 3-induced airway inflammation and epithelial damage by modulating Slc26a4 expression.

Establishment of an artificial particulate matter-induced lung disease model through analyzing pathological changes and transcriptomic profiles in mice

“…Among them, nine genes (Gpnmb, Trem2, Clec4d, Slc26a4, Ear6, Cd300lf, Ctsd, Ptgir, and Tacc3) were upregulated in the APM group relative to the DEP group in a dosedependent manner. The top nine genes have important roles in lung inflammation, asthma, COPD, pulmonary fibrosis, and lung cancer [35][36][37][38][39][40][41][42][43] . In this study, we observed common lung inflammation in the DEP and APM groups through histological assessment, and the severity was higher in the APM group relative to the DEP group.…”

Function-specific IL17A and Dexamethasone interactions in primary human airway epithelial cells

“…IL-17A is known to induce goblet cell hyperplasia and mucus production, which are prominent features of airway diseases, such as COPD, asthma, and cystic fibrosis [28][29][30]43 . Moreover, IL-17A is known to stimulate upregulation of SLC26A4, an anion exchange protein which is known to induce goblet cell hyperplasia in human lung mucoepidermoid carcinoma cells and murine airway epithelial cells [44][45][46][47] . Interestingly, SLC26A4 was found to be elevated in serum 48 , endobronchial biopsies 49 , and lung tissues of asthmatics 45 , and inversely associated with percentage of forced expiratory volume in 1 s (FEV 1 %), suggesting its role in airway disease 48 .…”

“…Moreover, IL-17A is known to stimulate upregulation of SLC26A4, an anion exchange protein which is known to induce goblet cell hyperplasia in human lung mucoepidermoid carcinoma cells and murine airway epithelial cells [44][45][46][47] . Interestingly, SLC26A4 was found to be elevated in serum 48 , endobronchial biopsies 49 , and lung tissues of asthmatics 45 , and inversely associated with percentage of forced expiratory volume in 1 s (FEV 1 %), suggesting its role in airway disease 48 . Our data shows that SLC26A4 is the most differentially expressed gene in response to IL-17A, suggesting its significant role in driving goblet cell hyperplasia in our model.…”