Inflammatory Biomarkers in induced Sputum Predict Chronic Obstructive Pulmonary Disease (COPD) Severity

Abstract Background: The progression of an abnormal inflammatory response plays a crucial role in the functional decline that occurs in COPD patients[1].Compared to serum biomarkers, inflammatory biomarkers in induced sputum would be a more reliable reflection of the inflammatory processes in the airways. Based on this, we explored the association of inflammatory biomarkers in induced sputum with lung function in COPD patients.Methods: 102 patients with COPD were recruited and underwent spirometry. According to the percentage of the predicted forced expiratory volume in 1 second value (FEV1%pred), participants with COPD were divided into a mild and moderate group (FEV1%pred≥ 50%, n=57) and a severe and extremely severe group (FEV1%pred<50%, n=45). Then we analyzed a series of inflammatory biomarkers in induced sputum and determined their association with lung function in COPD patients.Results: We found an increased levels of eosinophils percentage, MMP9 mRNA, LTB4R mRNA, and decreased levels of CC16 mRNA and miR-155 in the induced sputum of patients with severe and extremely severe COPD. In our analysis, sputum cell CC16 mRNA expression, but not CC16 secretion in the supernatant of the sputum, was closely and independently correlated with lung function decline in patients with COPD. Conclusion: The levels of numerous inflammatory biomarkers in induced sputum were associated with lung function decline in COPD，and the relative CC16 mRNA expression level with a cutoff of 1.09 could be a predictive biomarker of the severity of COPD.