From the authors

We would like to thank C. Mehats and colleagues for their comments regarding our paper on phosphodiesterase (PDE)4 inhibition in hyperoxia-induced bronchopulmonary dysplasia (BPD) 1. In our article, we stated that inhibition of PDE4 with cilomilast leads to an improved alveolarisation in hyperoxia-induced lung injury in mice 1. C. Mehats and colleagues raised concerns about our study design and the obtained results. We would like to respond to the issues in question. The first point of criticism addresses differences regarding the therapeutic impact of the PDE4 inhibitor cilomilast in our study of mice, as compared to rolipram in the study of MEhats et al. 2, which was conducted on rats. MEhats et al. 2 demonstrated that treatment of hyperoxia-exposed rats with 0.5 mg·kg−1·day−1 rolipram prolonged the survival of the treated rats …