Aerobic fitness is associated with extracellular DNA levels in the sputum of patients with cystic fibrosis

Abstract

Cystic fibrosis (CF) is a genetic disease that affects multiple organs and systems. It is characterized by a progressive decline in pulmonary function and by the presence of exercise intolerance, which is associated with airway obstruction and the presence of chronic inflammation and recurrent infections. 1,2 Elevated levels of extracellular DNA, mainly originating from neutrophil extracellular traps (NETs), have been described in both bronchoalveolar lavage and sputum of CF patients. [3][4][5] The presence of DNA changes the viscosity and elasticity of the mucus, contributing to airway obstruction. In addition to this, the presence of chronic airway neutrophilic inflammation is considered an important factor for the early development of lung disease. 6 DNA levels in airway fluid samples from individuals with CF are already known to negatively correlate with lung function. 7 This suggests that the DNA found in airway fluids may contribute to lung disease from the beginning of life. A recent study showed that subjects with levels of DNA in the sputum greater than 243 μg/mL had a significant decrease in forced expiratory volume in the first second (FEV 1 ) and greater need for hospitalisation. 8