Effects of angiotensin-converting enzyme inhibitors on spontaneous or stimulated generation of reactive oxygen species by bronchoalveolar lavage cells harvested from patients with or without chronic obstructive pulmonary disease

We examined the effects of angiotensin-converting enzyme (ACE) inhibitors o n spontaneous or stimulated generation of reactive oxygen species (ROS) by bronchoalveolar lavage (BAL) cells prepared from 6 patients with chronic ob structive pulmonary disease (COPD) and from age-matched control subjects wi thout COPD. The ROS produced by BAL cells were measured by the lucigenin-de pendent chemiluminescence method. The application of ACE inhibitors into cu lture media containing BAL cells inhibited spontaneous and stimulated gener ation of ROS by BAL cells from COPD patients and control subjects in an amb roxol-concentration-dependent manner. Alacepril, an ACE inhibitor bearing S H-group, inhibited the oxygen radical production and generation by BAL cell s from COPD patients in a dose-dependent fashion. Approximately 0.6-0.7 mM of alacepril inhibited 50% of the ROS production by BAL cells from COPD pat ients, whereas a slightly higher concentration (3 mM) of lisinopril, an ACE inhibitor not bearing an SH-group, was necessary to inhibit the production of ROS. These results suggest that an ACE inhibitor may act as an pulmonar y antioxidant in patients with COPD.