Systemic inflammation and systemic oxidative stress in patients with acute exacerbations of COPD

BACKGROUND: In patients with chronic obstructive pulmonary disease (COPD), the inflammatory processes and oxidative stress are closely linked in the lung compartment. However, the relationships between systemic inflammation and parameters of oxidative stress in the systemic circulation during acute exacerbations of COPD remain to be explored. OBJECTIVE: To analyze relationships between erythrocytic glutathione peroxidase (GPx), a marker of systemic oxidative stress, and parameters reflecting systemic inflammation, such as circulating neutrophils, C-reactive protein (CRP), and interleukin (IL)-6, in patients with acute exacerbations of COPD. PATIENTS AND METHODS: We measured erythrocytic GPx activity, circulating neutrophil count, and serum high-sensitivity (hs) CRP and IL-6 in 177 patients admitted to the hospital due to an acute exacerbation of COPD (91 males, mean age 66.8+/-0.9 years, mean FEV1 45.3+/-1.3% predicted). RESULTS: From GOLD Stage II to Stage III and IV, erythrocytic GPx activity significantly decreased [mean+/-SEM: from 44.3+/-1.7 U/g Hb to 40.8+/-1.1 U/g Hb and to 38.4+/-1.5 U/g Hb, p = 0.037], while serum hsCRP increased [median (25th, 75th percentile): from 9.6 (3.0, 23.0) mg/l to 23.3 (6.4, 46.8) mg/l, and to 26.7 (6.5, 117.2) mg/l, p = 0.004]. Erythrocytic GPx activity was significantly inversely related to both, log neutrophil count (r = -0.219, p = 0.003) and log hsCRP (r = -0.199, p = 0.008). CONCLUSIONS: Our study suggests an association between systemic inflammation and systemic oxidative stress reflected by erythrocytic GPx in patients with acute exacerbations of COPD.