In this translational research project, the airway disease cystic fibrosis (CF) will be used as a model to study host-micro-organism interactions in the lung, in a context of chronic bacterial and/or fungal exposition, and different degrees of CFTR modulation through small molecules tackling CF at its very cause. The first work package (WP) will focus on host-micro-organism interactions and inflammatory determinants in allergic bronchopulmonary aspergillosis (ABPA), an inflammatory syndrome frequently complicating airway diseases, caused by an overzealous reaction of the immune system to inhaled fungal spores (WP1). A second aim will be to identify changes in CF airway inflammatory profile and host-pathogen interactions induced by CFTR modulation (WP2). Finally, the findings and insights resulting from the first two work packages, will be applied to explore host-pathogen interactions in (chronic) respiratory infections in non-CF lung disease, such as non-CF bronchiectasis, chronic pulmonary aspergillosis, and non-tuberculous mycobacterial pulmonary disease (WP3).