Roflumilast N-oxide, a PDE4 inhibitor, improves cilia motility and ciliated human bronchial epithelial cells compromised by cigarette smoke in vitro
Article first published online: 24 JUL 2012
© 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society
British Journal of Pharmacology
Volume 166, Issue 8, pages 2243–2262, August 2012
How to Cite
Milara, J., Armengot, M., Bañuls, P., Tenor, H., Beume, R., Artigues, E. and Cortijo, J. (2012), Roflumilast N-oxide, a PDE4 inhibitor, improves cilia motility and ciliated human bronchial epithelial cells compromised by cigarette smoke in vitro. British Journal of Pharmacology, 166: 2243–2262. doi: 10.1111/j.1476-5381.2012.01929.x
- Issue published online: 24 JUL 2012
- Article first published online: 24 JUL 2012
- Accepted manuscript online: 2 MAR 2012 02:34PM EST
- Received; 29 June 2011; Revised; 24 January 2012; Accepted; 22 February 2012
- bronchial epithelial cells;
- ciliary motility;
BACKGROUND AND PURPOSE Mucociliary malfunction occurs in chronic obstructive pulmonary disease (COPD) and compromised functions of ciliated bronchial epithelial cells may contribute to this. Cigarette smoke, a major risk factor for COPD, impairs ciliary beat frequency (CBF). cAMP augments CBF. This in vitro study addressed, in differentiated, primary human bronchial epithelial cells, whether roflumilast N-oxide, a PDE4 inhibitor, (i) augments CBF; (ii) prevents the reduction in CBF induced by cigarette smoke extract (CSE); and (iii) protects against the loss of the ciliated phenotype following long-term CSE exposure.
EXPERIMENTAL APPROACH Air-liquid interface cultured human bronchial epithelial cells were incubated with roflumilast N-oxide and exposed to CSE. CBF was assessed by digital high speed video microscopy (DHSV). Ciliated cells were characterized by β-tubulin IV staining and analyses of Foxj1 and Dnai2 mRNA and protein (real-time quantitative PCR, Western blotting).
KEY RESULTS Roflumilast N-oxide concentration-dependently triggered a rapid and persistent increase in CBF and reversed the decrease in CBF following CSE. Long-term incubation of bronchial epithelial cells with CSE resulted in a loss in ciliated cells associated with reduced expression of the ciliated cell markers Foxj1 and Dnai2. The PDE4 inhibitor prevented this loss in the ciliated cell phenotype and the compromised Foxj1 and Dnai2 expression. The enhanced release of IL-13 following CSE, a cytokine that diminishes the proportion of ciliated cells and in parallel, reduces Foxj1 and Dnai2, was reversed by roflumilast N-oxide.
CONCLUSION AND IMPLICATIONS Roflumilast N-oxide protected differentiated human bronchial epithelial cells from reduced CBF and loss of ciliated cells following CSE.