Conflict of interest: F. Bonella reports consulting fees from Boehringer Ingelheim, Sanofi, Savara Pharma and CSL Behring, lecture honoraria from Boehringer Ingelheim and Sanofi, travel support from Boehringer Ingelheim, AstraZeneca and Atyr, and advisory board participation with Boehringer Ingelheim, Sanofi and GSK, outside the submitted work. E.D. Manali reports grants from Savara, lecture honoraria from Boehringer Ingelheim, Elpen, Demo, CSL Behring and Hoffman La Roche, and travel support from Boehringer Ingelheim, Hoffman La Roche, Elpen and CSL Behring, outside the submitted work. S.A. Papiris reports grants from Savara, lecture honoraria from Boehringer Ingelheim, Elpen, Demo, Pfizer and Hoffman La Roche, and travel support from Boehringer Ingelheim and Elpen, outside the submitted work.