Isoproterenol suppresses cytokine-induced RANTES secretion in human lung epithelial cells through the inhibition of c-jun N-terminal kinase pathway

It has been reported that β2-agonists may potentially exert some anti-inflammatory action in addition to bronchodilation that may contribute to their beneficial effects on asthma control. Bronchial epithelial cells are well known to respond to a range of stimuli by producing various biologically active mediators that can influence airway inflammation. RANTES (regulated on activation, normal T cells expressed and secreted) plays an important role in the pathophysiology of airway inflammation of asthmatics through its chemotactic activity for eosinophils. In this study, the authors investigated whether cytokine-induced RANTES release from BEAS-2B human bronchial epithelial cells could be modulated by β-agonist isoproterenol (ISO). The possible involvement of c-jun N-terminal kinase (JNK) pathway was also studied. Combination of tumor necrosis factor-α and interleukin-1β (cytokine mix) increased RANTES release from BEAS-2B cells and stimulated JNK activity. Similar to JNK inhibitor SP600125, ISO inhibited not only the production of RANTES but also the activation of JNK pathway in cytokine mix-stimulated BEAS-2B cells. The effect of ISO was mediated by the β2-adrenoceptor, since it was blocked by ICI 118,551, a selective β2-receptor antagonist, but not by atenolol, a selective β1-receptor antagonist. Adenylyl cyclase activator forskolin reproduced the effects of ISO. Isoproterenol was found to inhibit the release of RANTES from the human bronchial epithelial cells, at least in part, through the inhibition of JNK signaling pathway.