Sputum neutrophil elastase in bronchiectasis: a Southern European cohort study

Bronchiectasis is a chronic respiratory disease with neutrophilic airway inflammation playing a prominent role in its pathophysiology [1]. The inflammatory process depends on the release of neutrophil elastase (NE) and subsequent formation of neutrophil extracellular traps to facilitate the neutralisation of pathogens. An excessive release of NE can lead to several damaging lung effects, including mucus gland stimulation, increase in sputum production, impairment in ciliary beat frequency, and extracellular matrix and airway epithelia destruction. The activity of NE (aNE) has been previously evaluated in sputum samples of a Scottish cohort of bronchiectasis patients [2]. The authors demonstrated that increased levels of aNE in sputum are associated with disease severity and poor clinical outcomes. This experience identified NE as one of the most promising biomarkers in bronchiectasis and, subsquently, a point-of-care assay for aNE was validated [3].