PNNL

Abstract

BACKGROUND: Nitric oxide is a physiologically regulator of endothelial function and hemodynamics. Oxidized products of nitric oxide can form nitrotyrosine, which is a marker of nitrative stress. Cigarette smoking decreases exhaled nitric oxide, and the underlying mechanism may be important in the cardiovascular toxicity of cigarette smoke, although it is not clear if this effect results from decreased nitric oxide production or oxidation of nitric oxide to reactive, nitrating, species. These processes would be expected to have opposite effects on nitrotyrosine levels, a marker of nitrative stress. OBJECTIVE: In this study, we determine the effects of smoking and chronic obstructive pulmonary disease (COPD) on circulating levels of nitrotyrosine, and thereby gain insight into the processes regulating nitrotyrosine formation. METHODS: A custom antibody microarray platform was used to analyze the levels of 3-nitrotyrosine modifications on 24 proteins in plasma. Plasma samples from 458 individuals were analyzed. RESULTS: Nitrotyrosine levels in circulating proteins were uniformly reduced in smokers but increased in COPD patients. We also observed a persistent suppression of nitrotyrosine in former smokers. CONCLUSIONS: Smoking broadly suppresses the levels of 3-nitrotyrosine in plasma proteins, suggesting that cigarette smoke suppresses endothelial nitric oxide production. In contrast, the increase in nitrotyrosine levels in COPD patients most likely results from inflammatory processes. This study provides the first evidence that smoking has irreversible effects on endothelial production of nitric oxide, and provides insight into how smoking could induce a loss of elasticity in the vasculature and a long-term increase in the risk of cardiovascular disease.