Proteomics of exhaled breath condensate in stable COPD and non-COPD controls using tandem mass tags (TMTs) quantitative mass spectrometry: A pilot study

Abstract Chronic obstructive pulmonary disease (COPD) is a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. Exhaled breath condensate (EBC) is now a safe and clinically significant measurement which has a huge potential to measure biomarkers in COPD. Previous studies profiled the pooled EBC samples from COPD or control participants due to technological limitations. In our study, 32 COPD patients and 28 control individuals were enrolled, and their EBC were collected. After matching with sex, age and smoking history, EBC samples of 19 COPD patients and 19 control individuals were analyzed using tandem mass tags (TMTs) quantitative mass spectrometry individually. A total of 257 proteins were identified. Compared with control group, 24 proteins (15 upregulated and 9 downregulated) were differentially expressed in COPD patients. The GO analysis of these differential proteins expressed mostly in the cytoplasm, and the KEGG analysis showed they had a predominant role in inflammatory response. And ACTB, UBC, TUBB and CCT2 involving in cell motility and cytoskeleton played important role in the interaction-net of these proteins. To sum up, we found some proteins might be novel biomarkers of EBC in COPD and TMTs was available to analyze proteomics in individual EBC samples. Significance It is still difficult to understand the mechanism of airway inflammation in COPD. Exhaled breath condensate(EBC) might be a great study object, but due to technological limitations, researchers preferred to use pooled EBC samples. This study analyzed individual EBC samples, which would deepen our understanding of the pathogenesis of COPD. And this method can be applied to individual EBC samples for further airway investigations of different purpose and different complexity.