Main objective: investigate gene expression differences in nasal epithelium and sputum between eosinophilic COPD exacerbations and other subtypes to better understand why some patients are more at risk for eosinophilic COPD exacerbations. Secondary objectives:~Investigate differences in microbiome composition and immunophenotyping profiles in peripheral blood per subtype.~Assess for clinical differences between all COPD exacerbation subtypes.~Assess if and how baseline meta-transcriptomics either in nasal epithelium or sputum and blood immunophenotyping can be utilized to predict COPD exacerbation subtype.~Determine if the microbiome in sputum and nasal epithelial material are comparable.~Determine if different subtypes of COPD exacerbations respond differently to standard treatment with oral prednisolone (40 mg daily) with or without antibiotics.~To evaluate if metabolic responses during recovery are different in patients with increased systemic inflammation compared to patients without systemic inflammation at exacerbation
Main objective: investigate gene expression differences in nasal epithelium and sputum between eosinophilic COPD exacerbations and other subtypes.