David A Bergin, Killian Hurley, Adwait Mehta, Stephen Cox, Dorothy Ryan, Shane J O’Neill, Emer P Reeves*, Noel G McElvaney*Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland*These authors share joint senior authorshipAbstract: Bronchiectasis is an airway disease characterized by thickening of the bronchial wall, chronic inflammation, and destruction of affected bronchi. Underlying etiologies include severe pulmonary infection and cystic fibrosis (CF); however, in a substantial number of patients with non-CF-related bronchiectasis (NCFB), no cause is found. The increasing armamentarium of therapies now available to combat disease in CF is in stark contrast to the limited tools employed in NCFB. Our study aimed to evaluate similarities and differences in airway inflammatory markers in patients with NCFB and CF, and to suggest potential common treatment options. The results of this study show that NCFB bronchoalveolar lavage fluid samples possessed significantly increased NE activity and elevated levels of matrix metalloproteinases 2 (MMP-2) and MMP-9 compared to healthy controls (P < 0.01); however, the levels detected were lower than in CF (P < 0.01). Interleukin-8 (IL-8) concentrations were significantly elevated in NCFB and CF compared to controls (P < 0.05), but in contrast, negligible levels of IL-18 were detected in both NCFB and CF. Analogous concentrations of IL-10 and IL-4 measured in NCFB and CF were statistically elevated above the healthy control values (P < 0.05 and P < 0.01, respectively). These results indicate high levels of important proinflammatory markers in both NCFB and CF and support the use of appropriate anti-inflammatory therapies already employed in the treatment of CF bronchiectasis in NCFB.Keywords: bronchiectasis, cystic fibrosis, proteases, inflammation