Sputum and plasma neutrophil elastase in stable adult patients with cystic fibrosis in relation to chronic Pseudomonas colonization

<b>Background:</b> Neutrophil elastase (NE) has been implicated in the pathogenesis of airway inflammation in cystic fibrosis (CF) and impaired defenses against Pseudomonas aeruginosa (PA) infection. Sputum NE may act as a biomarker of neutrophilic inflammation in CF <b>Objectives:</b> To determine sputum and plasma NE levels in clinically stable adults CF patients, compared to plasma NE levels in healthy controls and to investigate their correlation with PA colonization and lung function <b>Methods:</b> A cross-sectional study. NE was measured on spontaneously expectorated sputum and plasma from 21 CF patients during routine visits CF clinic and plasma from 22 healthy controls. NE levels were measured by the magnetic bead-based multiplex assay <b>Results:</b> Patient’s age ranged from 18-40 years with a mean age of 24.29±5.28 years and 61.9% had pancreatic sufficiency. The median plasma NE was higher in CF patients compared to plasma NE in control subjects=0.067 and significantly higher than the sputum in CF patients&lt;0.001. A positive and significant correlation was found between plasma and sputum NE (Pearson r=0.533, p=0.013). Fifteen CF patients (76.2%) were colonized with PA. Both median sputum and plasma NE were found to be higher in CF patients with PA compared with non-PA, however this difference was statistically insignificant. Sputum and plasma were not correlated with PA and percentage predicted FEV1 <b>Conclusion:</b> These findings may suggest either sputum or plasma NE had a neutral inflammatory effect on PA or lung function in stable adult CF patients