1. Department of Respiratory Medicine and Infectious Disease, Hannover Medical School , Carl-Neuberg-Str. 1, Hannover 30625 , Germany
2. German Center for Lung Research, Biomedical Research in Endstage and Obstructive Lung Disease , Hannover , Germany
3. Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, Saarland University , Kirrberger Str. 1, Homburg 66421 , Germany