Correlation of plasma protein carbonyls and C-reactive protein with GOLD stage progression in COPD patients

Oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). To investigate the correlation between the progression of COPD and plasma biomarkers of chronic inflammation and oxidative injury, blood samples were obtained from healthy volunteers (HV, n = 14) and stabilized COPD patients. The patients were divided into three groups according to their GOLD stage (II, n = 34; III, n = 18; IV, n = 20). C-reactive protein (CRP), protein carbonyls (PC), malondialdehyde (MDA), susceptible lipoperoxidation of plasma substrates (SLPS), and myeloperoxidase activity (MPO) were measured. The plasma concentration of SLPS was measured as the amount of MDA generated by a metal ion-catalyzed reaction in vitro. PC, SLPS, and CPR were increased significantly (p < 0.001) in COPD patients when compared to HV. MDA concentrations and MPO activities were not significantly different from those of the HV group. In conclusion, increased oxidation of lipids and proteins resulting in a progressive increase in the amount of total plasma carbonyls and oxidative stress the presence of oxidative stress during COPD progression, concomitant with an increased oxidation of lipids and proteins resulting in a progressive and significant increase in the amount of total carbonyls formed from lipid-derived aldehydes and direct amino acid side chain oxidation in plasma, may serve as a biomarker and independent monitor of COPD progression and oxidative stress injury.