Elevated concentrations of CXCL8 in the nasal mucosal lining fluid of COPD patients as an accessible surrogate measure of bronchial levels

Introduction: CXCL8 is a neutrophil chemoattractant involved in the pathogenesis of COPD with increased levels reported in both induced sputum and BAL fluid. The upper respiratory tract is histologically and immunologically related to the bronchi and exposed to the same noxious stimuli in COPD. It may represent a more easily accessible surrogate measure of CXCL8 and other inflammatory biomarkers. Hypothesis: Concentrations of CXCL8 are increased in the nasal mucosal lining fluid (MLF) of COPD patients compared with controls and are a surrogate measure for bronchial CXCL8. Methods: A synthetic absorptive matrix (SAM; nasosorption) was used to sample the nasal MLF of 13 stable COPD patients, 12 healthy non-smokers (NS) and 10 smokers (Sm). Less severe COPD patients (FEV₁≥50%; n=8) underwent bronchoscopy to obtain paired samples of bronchial MLF using SAM (bronchosorption). Concentrations of CXCL8 were measured in the eluates by ELISA. Results: Nasal CXCL8 was higher in COPD when compared to NS but not Sm (Table). Mean (± SEM) concentrations of bronchial CXCL8 were 0.9±0.2 ng/ml in COPD and levels correlated with paired nasal samples (r=-0.88, p<0.01). Concentrations of nasal CXCL8 also correlated with FEV₁ % predicted in COPD (r=-0.83, p<0.001) but not age, pack years, FEV₁ or FVC. Conclusion: Nasal CXCL8 is elevated in COPD and may reflect bronchial levels. Measuring CXCL8 by nasosorption may provide a non-invasive biomarker to further explore inflammation during stable disease, exacerbations or modulation by novel treatments.