Abstract
BackgroundThe D prostanoid receptor 2 (DP2; also known as chemoattractant receptor–homologous molecule expressed on TH2 cells) is implicated in the pathogenesis of asthma, but its expression within bronchial biopsy specimens is unknown.ObjectivesWe sought to investigate the bronchial submucosal DP2 expression in asthmatic patients and healthy control subjects and to explore its functional role in epithelial cells.MethodsDP2 protein expression was assessed in bronchial biopsy specimens from asthmatic patients (n = 22) and healthy control subjects (n = 10) by using immunohistochemistry and in primary epithelial cells by using flow cytometry, immunofluorescence, and quantitative RT-PCR. The effects of the selective DP2 agonist 13, 14-dihydro-15-keto prostaglandin D2 on epithelial cell migration and differentiation were determined.ResultsNumbers of submucosal DP2+ cells were increased in asthmatic patients compared with those in healthy control subjects (mean [SEM]: 78 [5] vs 22 [3]/mm2 submucosa, P < .001). The bronchial epithelium expressed DP2, but its expression was decreased in asthmatic patients compared with that seen in healthy control subjects (mean [SEM]: 21 [3] vs 72 [11]/10 mm2 epithelial area, P = .001), with similar differences observed in vitro by primary epithelial cells. Squamous metaplasia of the bronchial epithelium was increased in asthmatic patients and related to decreased DP2 expression (rs = 0.69, P < .001). 13, 14-Dihydro-15-keto prostaglandin D2 promoted epithelial cell migration and at air-liquid interface cultures increased the number of MUC5AC+ and involucrin-positive cells, which were blocked with the DP2-selective antagonist AZD6430.ConclusionsDP2 is expressed by the bronchial epithelium, and its activation drives epithelial differentiation, suggesting that in addition to its well-characterized role in inflammatory cell migration, DP2 might contribute to airway remodeling in asthmatic patients.
Highlights
The D prostanoid receptor 2 (DP2; known as chemoattractant receptor–homologous molecule expressed on TH2 cells) is implicated in the pathogenesis of asthma, but its expression within bronchial biopsy specimens is unknown
Representative examples of DP2 expression in bronchial biopsy specimens from asthmatic patients and healthy control subjects are shown (Fig 1, A-D)
These findings demonstrate that activation of DP2 in T cells and the epithelium has the potential to drive key features of severe asthma
Summary
The D prostanoid receptor 2 (DP2; known as chemoattractant receptor–homologous molecule expressed on TH2 cells) is implicated in the pathogenesis of asthma, but its expression within bronchial biopsy specimens is unknown. Methods: DP2 protein expression was assessed in bronchial biopsy specimens from asthmatic patients (n 5 22) and healthy control subjects (n 5 10) by using immunohistochemistry and in primary epithelial cells by using flow cytometry, immunofluorescence, and quantitative RT-PCR. Results: Numbers of submucosal DP21 cells were increased in asthmatic patients compared with those in healthy control subjects (mean [SEM]: 78 [5] vs 22 [3]/mm submucosa, P < .001). The bronchial epithelium expressed DP2, but its expression was decreased in asthmatic patients compared with that seen in healthy control subjects (mean [SEM]: 21 [3] vs 72 [11]/10 mm epithelial area, P 5 .001), with similar differences observed in vitro by primary epithelial cells. Squamous metaplasia of the bronchial epithelium was increased in asthmatic patients and related to decreased DP2 expression
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