1. Department of Respiratory Diseases, University of Bari, 70124 Bari, Italy
2. Manchester Academic Health Science Centre, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester M13 9WL, UK
3. Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
4. Department of Internal Medicine, Unit of Respiratory Pathophysiology and Thoracic Endoscopy, Bio-Medical Campus, 00128 Rome, Italy