Sputum myeloperoxidase in chronic obstructive pulmonary disease

BACKGROUND Airway inflammation, especially neutrophilic airway inflammation, is a cardinal pathophysiologic feature in chronic obstructive pulmonary disease (COPD) patients. The ideal biomarkers characterizing the inflammation might have important potential clinical applications in disease assessment and therapeutic intervention. Sputum myeloperoxidase (MPO) is recognized as a marker of neutrophil activity. The purpose of this meta-analysis is to determine whether sputum MPO levels could reflect disease status or be regulated by regular medications for COPD. METHODS Studies were identified by searching PubMed, Embase, the Cochrane Database, CINAHL and http://www.controlled-trials.com for relevant reports published before September 2012. Observational studies comparing sputum MPO in COPD patients and healthy subjects or asthmatics, or within the COPD group, and studies comparing sputum MPO before and after treatment were all included. Data were independently extracted by two investigators and analyzed using STATA 10.0 software. RESULTS A total of 24 studies were included in the meta-analysis. Sputum MPO levels were increased in stable COPD patients when compared with normal controls, and this increase was especially pronounced during exacerbations as compared with MPO levels during the stable state. Theophylline treatment was able to reduce MPO levels in COPD patients, while glucocorticoid treatment failed to achieve the same result. CONCLUSION Sputum MPO might be a promising biomarker for guiding COPD management; however, further investigations are needed to confirm this.