ABSTRACT: This study aimed to compare – at a multi-omics level, inflammation, protease abundance and activity, microbiome, and proteome in sputum samples from patients with cystic fibrosis (CF, n=38) or chronic obstructive pulmonary disease (COPD, n=18) and healthy controls (n=10) to identify shared and unique pathways between these respiratory conditions. Sputum analysis revealed elevated inflammatory cell counts in both CF and COPD patients, with neutrophils being the dominant cell type. Key inflammatory markers, including IL-1β, TNF-α, TGF-β1, IL-8, and LTB4, were increased in both disease groups, with the highest levels observed in CF. Conversely, COPD patients exhibited higher levels of IL-5, IL-6, and IL-10. Microbiome analysis showed distinct clusters for each group, with CF patients often characterized by a preponderance of Pseudomonas. Hierarchical clustering unveiled robust interdependencies between microbiome parameters and inflammation, a richer and more diverse microbiome was associated with a healthier microbial community. This study uncovered significant disparities in inflammation, microbiome composition, and proteome profiles among CF, COPD, and healthy control cohorts. Neutrophilic inflammation and protease activity emerged as common factors in both diseases highlighting proteases as good targets for both indications, while distinct microbial signatures were identified. These findings offer valuable insights into the underlying mechanisms of CF and COPD and may inform future clinical strategies.