Plasma protein thiols: an early marker of oxidative stress in asthma and chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) and asthma are both characterized by heterogeneous chronic airway inflammation and obstruction as well as oxidative stress (OS). However, it is unknown whether OS occurs in early disease and how to best assess its presence. Plasma OS markers (TBARS, PSH, taurine, GSH, ergothioneine and paraoxonase 1 activity) and lung function tests were measured in patients with mild stable asthma (n = 24) and mild stable COPD (n = 29) and in age- and sex-matched controls. Forced expiratory volume in 1 s (FEV1 ) was associated with age both in patients and control groups. By contrast, FEV1 was positively correlated with PSH only in COPD (ρ = 0·49, P = 0·007). In multiple logistic regression analysis, lower PSH was the only OS marker independently associated with increased odds of both asthma (OR = 0·32, 95% CI 0·13-0·78, P = 0·01) and COPD (OR = 0·50, 95% CI 0·26-0·95, P = 0·03). These findings suggest that proteins -SH are a sensitive OS marker in early COPD and asthma.

Arginines Plasma Concentration and Oxidative Stress in Mild to Moderate COPD.

BACKGROUND: Elevated plasma concentrations of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) have been observed in respiratory conditions such as asthma and cystic fibrosis. Since oxidative stress has been shown to increase the activity of arginine methylating enzymes, hence increased ADMA synthesis, and to reduce ADMA degrading enzymes, hence increased ADMA concentrations, we assessed methylated arginines concentrations in chronic obstructive pulmonary disease (COPD), a disease characterized by increased oxidative stress. METHODS: Plasma arginine, ADMA and symmetric dimethylarginine (SDMA), oxidative stress markers (thiobarbituric acid reactive substances, TBARS, and plasma proteins SH, PSH) and antioxidants (taurine and paraoxonase 1, PON1, activity) were measured in 43 COPD patients with mild (n = 29) or moderate (n = 14) disease and 43 age- and sex-matched controls. RESULTS: TBARS significantly increased with COPD presence and severity (median 2.93 vs 3.18 vs 3.64 µmol/L, respectively in controls, mild and moderate group, p<0.0001 by ANOVA) whereas PSH decreased (6.69±1.15 vs 6.04±0.85 vs 5.33±0.96 µmol/gr prot, p<0.0001 by ANOVA). Increased ADMA/arginine ratio, primarily due to reduced arginine concentrations, was also observed with COPD presence and severity (median 0.0067 vs 0.0075 vs 0.0100, p<0.0001 by ANOVA). In multiple logistic regression analysis, only TBARS (OR 0.44, 95% CI 0.25-0.77; p = 0.0045) and ADMA/Arginine ratio (OR 1.72, 95% CI 2.27-13.05; p = 0.02) were independently associated with COPD severity. CONCLUSION: COPD presence and severity are associated with increased oxidative stress and alterations in arginine metabolism. The reduced arginine concentrations in COPD may offer a new target for therapeutic interventions increasing arginine availability.