Diagnosis of respiratory diseases using the proteomic analysis of exhaled breath condensate

Abstract

Investigation of exhaled breath condensate (EBC) is a noninvasive diagnostic method in respiratory diseases. The objective of this study was to compare EBC protein spectrum in healthy volunteers and in patients with chronic obstructive pulmonary disease (COPD), pneumonia and lung cancer (NSCLC), as well as to assess a role of proteomic analysis of EBC for diagnosis and differential diagnosis of these diseases. Methods. We examined 18 patients with COPD, 13 patients with community-acquired pneumonia, 26 patients with lung cancer and 24 healthy non-smoking volunteers. EBC was collected using ECoScreen system (VIASYS Healthcare, Germany) and a standardized method. EBC-samples were lyophilized, hydrolyzed and analyzed by HPLC and tandem mass spectrometry. To identify proteins, we used Mascot (Matrix Science, UK) and IPI-human (version 3.82) databases provided by the European Bioinformatics Institute. Results. Proteomic analysis of EBC identified more than 300 different proteins; most of them were types I and II cytoskeletal keratins. Cytokeratin 5, 6, and 14 concentrations in EBC of NSCLC patients were significantly higher than that in healthy volunteers. Dermcidin, immunoglobulin alpha, kininogen, cytoplasmic actin, serum albumin, and Zn-alpha2-glycoprotein were identified in EBC of healthy volunteers and patients with COPD and pneumonia. High concentration of peroxiredoxin in EBC of COPD patients could be due to severe oxidative stress. High levels of acute-phase and hypoxia proteins (annexins A1 and A2, HSP90B, cystatins M and B, collagen and histones fragments) were detected in EBC of pneumonia patients. Also, β- и α-subunit of hemoglobin, nuclear ubiquitin casein (NUCKS), POTEE, high mobility group protein (HMG-I/HMG-Y) and lactoferrin were identified in EBC of NSCLC patients. Conclusion. We found that EBC in healthy nonsmokers and in patients with COPD, pneumonia and NSCLC had characteristic protein spectrum. Most of the identified proteins could be used for diagnosis of these diseases.