Stable Compounds of Cigarette Smoke Induce Endothelial Superoxide Anion Production via NADPH Oxidase Activation

OBJECTIVE: Endothelial dysfunction is an early manifestation of cigarette smoke (CS) toxicity. We have previously demonstrated that CS impairs nitric oxide (NO)-mediated endothelial function via increased generation of superoxide anion (O2*). In these studies, we investigated whether stable compounds present in CS activate specific pathways responsible for the increased endothelial O2* production. METHODS AND RESULTS: Short exposure of bovine pulmonary artery endothelial cells (BPAECs), human pulmonary artery endothelial cells, and rat pulmonary arteries to CS extracts (CSEs) resulted in a large increase in O2* production (20-fold, 3-fold, and 2-fold increase, respectively; P<0.05 versus control), which was inhibited by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors diphenyleneiodinium, apocynin, and gp91 docking sequence-tat peptide but not by oxypurinol, the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester, or the mitochondrial respiration inhibitor rotenone. Exposure of BPAECs to acrolein, a stable thiol-reactive agent found in CS, increased O2* production 5-fold, which was prevented by prior inhibition of NADPH oxidase. CONCLUSIONS: These studies demonstrate that thiol-reactive stable compounds in CS can activate NADPH oxidase and increase endothelial O2* production, thereby reducing NO bioactivity and resulting in endothelial dysfunction. Clinically, these studies may contribute to the development of agents able to mitigate CS-mediated vascular toxicity.