Effect of Dupilumab on Nasal Epithelial Barrier Function in Patients With CRSwNP

Inclusion Criteria: * 18-99 years of age * Willingness to participate in the study * Suffer from chronic rhinosinusitis defined as in EPOS 2020 criteria, see main text * Group 1 (n=20, CRSsNP): Absence of nasal polyps * Group 2 (N=60, CRSwNP): Presence of nasal polyps as confirmed by endoscopy or CT and planned therapy with dupilumab * Presence or absence of non-steroidal anti-inflammatory drug (NSAID)-Exacerbated Respiratory Disease (N-ERD) * Patients with a history of treatment with monoclonal antibodies will only be included if at least a washout period of 6 months has passed Exclusion Criteria: * Pregnancy (as determined by ß-HCG test) or breast feeding * Patients with severe anatomic variations or deviations that do not allow access to all areas in the nasal cavity * Patients with cystic fibrosis or primary ciliary dyskinesia * Patients with permanent immunosuppression * A mental condition rendering the subject unable to understand the nature, scope, and possible consequences of the study * Patients with clinically meaningful comorbidity as determined by the evaluating committee * Patients with a history of exacerbation of chronic rhinosinusitis 4 weeks prior to the screening visit * Intake of a burst of systemic corticosteroids for the treatment of CRS 4 weeks prior to the screening visit