Claudio Rodriguez Gonzalez ¹ Sylvia Merkert ^2,3,4 David Tschritter ⁵ Jan Hegermann ^3,6 Matthias Mörgelin ⁷ Manuel M. Nietert ⁵ Prof. Dr. Ulrich Martin ^2,3,4 Burkhard Tümmler ^1,3 Antje Munder ^1,3 Nico Lachmann ^1,3,4,8*

• ¹ Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
• ² Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG), Hannover Medical School, Hannover, Germany
• ³ Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover Medical School, Hannover, Germany
• ⁴ REBIRTH, Research Center for Translational and Regenerative Medicine, Hannover Medical School, Hannover, Germany
• ⁵ Department of Medical Bioinformatics, University Medical Center Göttingen, Göttingen, Germany
• ⁶ Research Core Unit Electron Microscopy, Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
• ⁷ Colzyx AB, Medicon Village, Lund, Sweden
• ⁸ Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany

Cystic fibrosis (CF) is a hereditary autosomal recessive disease driven by deleterious variants of the CFTR gene, leading, among other symptoms, to increased lung infection susceptibility.Mucus accumulation in the CF lung is, as of yet, considered as one important factor contributing to its colonization by opportunistic pathogens such as Pseudomonas aeruginosa. However, in recent years evidence was provided that alveolar macrophages, which form the first line of defense against airborne pathogens, seem to be intrinsically defective with regard to bactericidal functionality in the CF lung. To assess the impact of CFTR deficiency in human macrophages only insufficient systems are available. To address this problem and to evaluate the role of CFTR in human macrophages, we successfully differentiated human induced pluripotent stem cells (iPSC) from a CF p.Phe508del homozygous individual and a healthy donor into primitive macrophages (iMac ΔF508 and iMac WT ), respectively, and compared the bactericidal functionality in the relevant cell type. iMac ΔF508 showed impaired P. aeruginosa clearance and intracellular killing capacity in comparison to iMac WT . Furthermore, iMac ΔF508 exhibited a less acidic lysosomal pH, and upon P. aeruginosa infection, there were signs of mitochondrial fragmentation and autophagosome formation together with a hyperinflammatory phenotype and deficient type I interferon response. In summary, we present a defective phenotype in iMac ΔF508 upon P. aeruginosa infection, which will constitute an ideal platform to further study the role of macrophages in the context of CF.