Alpha,beta-unsaturated aldehydes in cigarette smoke release inflammatory mediators from human macrophages.

Smoking cigarettes is the major risk factor for chronic obstructive pulmonary disease (COPD). COPD is a condition associated with chronic pulmonary inflammation, characterized by macrophage activation, neutrophil recruitment, and cell injury. Many substances contained in cigarette smoke, including reactive oxygen species (ROS), have been proposed to be responsible for the inflammatory process of COPD. However, this issue remains unsettled. By gas chromatography/mass spectrometry (GC/MS) we show that acrolein and crotonaldehyde, two alpha,beta-unsaturated aldehydes, are contained in aqueous cigarette smoke extract (CSE) at micromolar concentrations and mimic CSE in evoking the release of the neutrophil chemoattractant IL-8 and of the pleiotropic inflammatory cytokine TNF-alpha from the human macrophagic cell line U937. In addition, acrolein (10-30 microM) released IL-8 also from cultured human alveolar macrophages and THP-1 macrophagic cells. 4-hydroxy-2-nonenal (30-100 microM), an endogenous alpha,beta-unsaturated aldehyde that is abundant in lungs of patients with COPD, stimulated the release of IL-8 from U937 cells, whereas the saturated aldehyde, acetaldehyde, was ineffective. CSE-evoked IL-8 release was remarkably (> 80%) inhibited by N-acetyl-cysteine (0.1-3 mM) or glutathione monoethyl ester (1-3 mM). Both compounds, by forming covalent adducts (Michael adducts), completely removed unsaturated aldehydes from CSE. Our data demonstrate that alpha,beta-unsaturated aldehydes are major mediators of cigarette smoke-induced macrophage activation, and suggest that they might contribute to pulmonary inflammation associated with cigarette smoke.

Pharmacological assessment of the duration of action of glycopyrrolate vs tiotropium and ipratropium in guinea-pig and human airways.

1. Our study was aimed at investigating the duration of the bronchodilator action of the antimuscarinc drug glycopyrrolate compared to tiotropium and ipratropium. In the guinea-pig isolated trachea, the time (t1/2) necessary for a contractile response to carbachol (0.3 microM) to return to 50% recovery after washout of the antagonist was studied. The offset of the antagonist effect of glycopyrrolate, tiotropium and ipratropium (10 nM each) was t1/2 = 4.0 +/- 0.5, > 4.5 and 0.5 +/- 0.1 h, respectively. At 4.5 h from the washout of the antagonist, the recovery of the response to carbachol was 50 +/- 8, 10 +/- 4 and 70 +/- 7%, respectively. 2. In the human isolated bronchus, the offset of the bronchodilator effects of glycopyrrolate (3 nM), tiotropium (1 nM) and ipratropium (10 nM) was t1/2 = 3.7 +/- 0.2; > 6 and 3.0 +/- 0.2 h, respectively. At 6.0 h from the washout of the antagonist, the recovery of the response to carbachol (1 microM) was 101 +/- 10, 27 +/- 3 and 110 +/- 10%, respectively. 4. In anaesthetized guinea-pigs, acetylcholine-induced bronchoconstriction was markedly reduced by intratracheal instillation of glycopyrrolate (3 nmol kg(-1); 88.1 +/- 4% inhibition), tiotropium (1.3 nmol kg(-1); 86.2 +/- 5% inhibition) or ipratropium (1.45 nmol kg(-1); 88.1 +/- 10% inhibition). These inhibitory effects assessed 3 or 24 h after antagonist administration were reduced to 69.9 +/- 5 and 29.7 +/- 6%; 28.3 +/- 5 and 14.2 +/- 5% for glycopyrrolate and ipratropium, respectively, whereas they remained stable (83.5 +/- 4; 70.6 +/- 6) for tiotropium. The residual inhibitory effect of glycopyrrolate was also assessed at 16 h from administration, and proved to be as low as that found at 24 h (31.2 +/- 10 vs 29.7 +/- 6%, respectively). 5. In conclusion, glycopyrrolate-induced bronchodilation has a longer duration than that of ipratropium, but less than that of tiotropium. The efficacy of a possible glycopyrrolate-based therapy for asthma or chronic obstructive pulmonary disease given once-a-day is not guaranteed by the present investigation.