PDE4A and pulmonary fibrosis: Besides the anti-inflammatory effects of roflumilast, considered critical towards its clinical benefits in COPD, results from additional in vitro and in vivo studies have shown that the PDE4 inhibitor curbs a broad spectrum of lung fibroblast functions such as myofibroblast transition and ECM generation or epithelial to mesenchymal transition (EMT) in vitro and mitigates bleomyin-induced lung fibrosis in vivo [2,10–12].