Inhibition of neutrophil elastase by the bacterial serine protease inhibitor ecotin in cystic fibrosis airway samples

Abstract

Abstract Cystic fibrosis (CF), a prevalent fatal genetic condition in North America, disrupts respiratory function by impeding chloride ion transport across mucosal surfaces. This leads to the thickening of mucus, resulting in constant lung inflammation and elevated levels of neutrophils. Neutrophil elastase (NE), a potent serine protease crucial for host defense, is released by these neutrophils. However, in excess, NE can cause detrimental host tissue damage. Abundant in CF airways, NE is a key predictor of lung disease progression. While past studies have explored targeting NE in CF, no optimal inhibitors have reached clinics. Our study tested ecotin, a bacterial periplasmic serine protease inhibitor, for its potential to impede NE activity in CF airway samples and curb NE release from human neutrophils. Results show that ecotin significantly reduces NE activity in sputum samples obtained from several CF patients. Additionally, we found that ecotin inhibits NE release from neutrophils exposed to CF lung stimuli like Staphylococcus aureus bacteria. These results establish ecotin as a promising NE inhibitor in CF with clinical potential.