ELANE and chronic obstructive pulmonary disease: Neutrophil elastase (NE) degrades constituent proteins of lung tissue, such as elastin (9), collagen (9), and E-cadherin (10), and acts as an exacerbating factor in acute and chronic pulmonary diseases, including acute respiratory distress syndrome (11), cystic fibrosis (12), and chronic obstructive pulmonary disease (13).