COPD	chronic obstructive pulmonary disease
AAT	alpha-1 antitrypsin
FEV1	forced expiratory volume in 1 s
FVC	forced expiratory volume
TNF	tumor necrosis factor
MMP	matrix metalloproteinase
MP	mass spectrometry
2-DE	two-dimensional gel electrophoresis
LC-MS/MS	liquid chromatography-tandem mass spectrometry
FFE	free-flow electrophoresis
CRP	C-reactive protein
PCT	procalcitonin
NE	neutrophil elastase
GOLD	global initiative for chronic obstructive lung disease
CRF	case report form
BMI	body mass index
WHO	The World Health Organization