Evidence of oxidative stress in asthma and COPD: potential inhibitory effect of theophylline

To evaluate the potential inhibitory effect of theophylline on the pulmonar y oxidative stress in asthma and chronic obstructive pulmonary disease (COP D), we concomitantly measured the blood levels of theophylline, a nonselect ive phosphodiesterase (PDE) inhibitor and lipid peroxides as an index of ox idative stress. The plasma levels of lipid peroxides were significantly ele vated in patients with asthma (3.48 +/- 0.11 nmol ml(-1); mean +/- SEM; n = 21, P < 0.01), non- or ex-smoking patients with COPD (3.55 +/- 0.11 nmol m l(-1); n = 20, P < 0.01), and current-smoking patients with COPD (3.53 +/- 0.15 nmol ml(-1) n = 15, P < 0.01), respectively, as compared to those of n on-smoking controls (3.02 +/- 0.08 nmol ml(-1); n = 19). There was a signif icant negative correlation between the plasma level of lipid peroxides and the forced expiratory volume in 1 sec (FEV1)% of forced vital capacity in t hese subjects (r = -0.304; n = 75, P < 0.1). In asthmatics, there was a sig nificant negative correlation between the plasma level of lipid peroxides a nd the serum lever of theophylline (r = -0.495; n = 18, P < 0.05). These re sults suggest that there may be increased oxidative stress in patients with asthma and COPD, and indicate that oxidative stress could possibly attribu te to the pathophysiology of asthma and COPD in leading to airflow obstruct ion and that theophylline could potentially inhibit oxidative stress in the process of bronchopulmonary inflammation in asthmatics.