The mechanism responsible for the increased air-space permeability in cigarette smokers is unknown. The aim of this study was to assess the acute and chronic effects of cigarette smoking on epithelial permeability, inflammation, and oxidant stress in the air spaces of smokers. Fourteen cigarette smokers underwent 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA) lung scans after abstaining from smoking for 12 h (chronic smoking) and 1 h after smoking two cigarettes (acute smoking). Each smoker also underwent bronchoscopy and bronchoalveolar lavage (BAL) after either chronic (n = 8) or acute smoking (n = 7). Seven nonsmokers also underwent bronchoscopy and BAL. The time to 50% clearance of 99mTc-DTPA (t50) after chronic smoking was 16.7 +/- 1. 3 min (mean +/- SE), and was further reduced after acute smoking to 14.8 +/- 1.0 min (p < 0.01). Neutrophil numbers were increased in bronchoalveolar lavage fluid (BALF) in the acute smoking group as compared with the nonsmokers (p < 0.05). Superoxide release from mixed BAL leukocytes was increased after chronic (p < 0.01) and acute (p < 0.001) smoking, as were thiobarbituric acid-reactive species (TBARS), providing evidence of lipid peroxidation in plasma (chronic, p < 0.05; acute, p < 0.05). Trolox equivalent antioxidant capacity (TEAC) was reduced in plasma (p < 0.001) and increased in BALF (p < 0.05) in both smoking groups. The study therefore showed an acute increase in epithelial permeability and an increase in the number of neutrophils in the air spaces of cigarette smokers concomitant with evidence of increased oxidant stress.

The oxidant-antioxidant balance in the airspaces of the lungs may be critical in protecting the lungs from the effects of cigarette smoke. We studied the effect of cigarette smoke and its condensates on the detachment, attachment, and proliferation of the A549 human alveolar epithelial cell line, in an in vitro model of cell injury and regeneration and the protective effects of antioxidants. Whole and vapor phase cigarette smoke decreased 51Cr-labeled A549 cell attachment, increased cell detachment, and decreased cell proliferation, as assessed by [3H]thymidine uptake. Freshly isolated rat type II alveolar epithelial cells showed an enhanced susceptibility to smoke-induced cell lysis when compared with the A549 cell line. Reduced glutathione (GSH) (400 microM) protected against the effects of cigarette smoke exposure on cell attachment, proliferation, and detachment. Depletion of intracellular GSH with buthionine sulfoxamine enhanced the epithelial cell detachment injury produced by smoke condensates. We conclude that cigarette smoke and its condensates cause an oxidant-induced injury to A549 human type II alveolar epithelial cells. Both intra- and extracellular GSH have important roles in protecting epithelial cells from the injurious effects of cigarette smoke.

In order to study neutrophil traffic in the lungs of humans, we harvested autologous neutrophils and radiolabeled them with indium-111 prior to reinjection. The passage of these [111In]neutrophils through the pulmonary vasculature was compared with that of [99mTc]erythrocytes in normal elderly subjects and in patients with chronic obstructive pulmonary disease (COPD). Neutrophil sequestration within the lungs of seven normal subjects, 10 min after reinjection, correlated with local erythrocyte transit times in the lungs (tau = 0.72, p less than 0.001). This relationship was lost in patients with COPD. In seven patients studied during an acute exacerbation of COPD, neutrophil retention was higher during the first passage through the lungs (mean, 22.0 SD 14.1%) compared with 14 patients studied when their condition was stable (16.3 SD 3.4%, p less than 0.001), or to the normal elderly subjects (13.7 SD 7.0%, p less than 0.001). In addition, the subsequent rate of neutrophil washout from the lungs was slower in patients with acute COPD (1.93 SD 0.66 x 10(-3)s1) than in those with stable disease (3.08 SD 1.8 x 10(-3)s-1, p less than 0.02). Neutrophil retention in the lungs correlated inversely with the extent of emphysema, assessed quantitatively by CT scanning (tau = 0.68, p less than 0.05). Thus, patients presenting with acute exacerbations of COPD have an increased neutrophil burden in the pulmonary vasculature with the potential for increased lung proteolysis.

We have previously demonstrated a reduction in the deformability of neutrophils, exposed to whole particulate cigarette smoke in vitro, by measuring their ability to filter through a micropore membrane with pore dimensions similar to those of the average pulmonary capillary segment. In this study, we exposed neutrophils to the vapor phase of cigarette smoke and investigated the mechanism of the reduction in neutrophil filterability. Although both stimulated neutrophils and smoke-exposed neutrophils demonstrated an increase in filtration pressures, and thus a reduction in cell deformability, compared with control untreated cells, the spontaneous release of the reactive oxygen intermediates hydrogen peroxide and the superoxide anion was depressed following in vitro smoke exposure and there was no shape change to suggest that smoke-exposed cells were activated. The presence of erythrocytes, plasma, or the antioxidants albumin and glutathione prevented the reduction in cell filterability following smoke exposure, suggesting that in vitro smoke exposure, in our system, was mediated by oxidants. Indeed, the increase in filtration pressures, produced by smoke, could be mimicked by the addition of the oxidant hypochlorous acid. The cytoskeletal inhibitors cytochalasin B and D improved the filterability of smoke-exposed cells, suggesting that smoke may change neutrophil deformability through an effect on the actin component of the cytoskeleton. By contrast, colchicine, a specific inhibitor of the microtubules, had no effect. Preincubation with a monoclonal antibody to the CD18 antigen, to block this major neutrophil adhesive glycoprotein, did not alter the filtration pressure developed by stimulated or smoke-exposed neutrophils, suggesting that increased adhesivity was not the mechanism of the increase in filtration pressures observed following smoke exposure.(ABSTRACT TRUNCATED AT 250 WORDS)