This observational longitudinal cohort study aims to assess the effect of monoclonal antibodies targeting interleukin 17 (anti-IL-17) on airway hyperreactivity and airway resistance. The study involves adult participants suffering from dermatological or rheumatological illness, who are planning to start treatment with monoclonal antibodies targeting interleukin 17 as a part of the treatment of these diseases. The primary outcome of this study will be changes in airway hyperresponsiveness to methacholine challenge reported as response-dose-ratio before and after initiation of anti-IL17 treatment regardless of presence of respiratory disease. Furthermore, the potential effect of anti-IL-17 on airway resistance will be assessed using conventional spirometry for measuring changes in FEV1 and Airwave oscillometry. A reduced degree of airway hyperreactivity and airway resistance after initiating ani-IL-17 could indicate effectiveness of anti-IL-17 in asthma patients which would have to be examined further in a population of asthma patients.