β2 adrenergic agonist suppresses eosinophil-induced epithelial-to-mesenchymal transition of bronchial epithelial cells

BACKGROUND Epithelial-mesenchymal transition is currently recognized as an important mechanism for the increased number of myofibroblasts in cancer and fibrotic diseases. We have already reported that epithelial-mesenchymal transition is involved in airway remodeling induced by eosinophils. Procaterol is a selective and full β2 adrenergic agonist that is used as a rescue of asthmatic attack inhaler form and orally as a controller. In this study, we evaluated whether procaterol can suppress epithelial-mesenchymal transition of airway epithelial cells induced by eosinophils. METHODS Epithelial-mesenchymal transition was assessed using a co-culture system of human bronchial epithelial cells and primary human eosinophils or an eosinophilic leukemia cell line. RESULTS Procaterol significantly inhibited co-culture associated morphological changes of bronchial epithelial cells, decreased the expression of vimentin, and increased the expression of E-cadherin compared to control. Butoxamine, a specific β2-adrenergic antagonist, significantly blocked changes induced by procaterol. In addition, procaterol inhibited the expression of adhesion molecules induced during the interaction between eosinophils and bronchial epithelial cells, suggesting the involvement of adhesion molecules in the process of epithelial-mesenchymal transition. Forskolin, a cyclic adenosine monophosphate-promoting agent, exhibits similar inhibitory activity of procaterol. CONCLUSIONS Overall, these observations support the beneficial effect of procaterol on airway remodeling frequently associated with chronic obstructive pulmonary diseases.