Gamma-glutamyltransferase and C-reactive protein in stable chronic obstructive pulmonary disease

Systemic inflammation and oxidative stress are the most important features of chronic obstructive pulmonary disease (COPD). The presence of oxidative stress in the airways of smokers, the largest population of COPD patients, is a consequence of direct inhalation of cigarette smoke and increased inflammation-related production of reactive oxygen species. On the other hand, oxidative stress appears to be the key component of many processes associated with chronic inflammation. We intend to examine whether serum C-reactive protein (CRP) concentration and gamma-glutamyltransferase (GGT) activity might be used as auxiliary markers in monitoring level of oxidative stress and inflammation in clinically stable COPD. We also investigated influence of cigarette smoking on these two systemic parameters. Catalytic activity of GGT and concentration of CRP were determined in sera of COPD patients (N = 109) and in healthy controls (N = 51) by using standard spectrophotometric method and immunoturbidimetric method, respectively. Concentration of CRP and activity of GGT were increased in COPD patients, as compared to healthy controls (p < 0.05). We found a significant positive correlation between those two parameters in COPD patients (r = 0.202, p = 0.0371). Our results showed no difference in GGT activity (p = 0.606) or CRP concentration (p = 0.573) between groups of patients when subdivided according to the severity of the disease. Smoking did not have a significant impact on CRP and GGT values in COPD patients and healthy controls. We showed an increase of serum CRP and GGT values in COPD patients, and we suggest that serum GGT activity might also represent an inflammation/oxidative stress marker. It seems that COPD patients present higher serum CRP and GGT values than healthy subjects independently from their smoking habits.