The effects of cigarette smoking and smoking cessation on high-density lipoprotein functions: implications for coronary artery disease.

Background Smoking cessation was associated with improved prognosis of coronary artery disease. This study was designed to investigate the effect of smoking cessation on high-density lipoprotein functionality in coronary artery disease patients. Methods In this prospective, randomized and parallel controlled study, coronary artery disease smokers ( n = 28) and healthy smokers ( n = 30) were divided into smoking cessation group and continuous smoking group, respectively. Blood samples were collected before and after three-month smoking cessation. Plasma high-density lipoprotein was isolated by density gradient centrifugation. The ability of high-density lipoprotein against copper-induced oxidation of lipoprotein was determined to evaluate the antioxidative property of high-density lipoprotein, and the macrophage migration inhibited by high-density lipoprotein was tested to identify the antichemotactic property of high-density lipoprotein. High-density lipoprotein-induced macrophage cholesterol efflux was measured by fluorescence spectrometry using NBD cholesterol analogue. Healthy non-smoking volunteers were enrolled as the baseline control. Results The baseline antioxidative, antichemotactic ability of high-density lipoprotein and high-density lipoprotein-induced cellular cholesterol efflux in coronary artery disease smokers and healthy smokers were significantly attenuated when compared with those in healthy non-smokers. After three-month smoking cessation, both the antioxidative ability and antichemotactic ability of high-density lipoprotein were improved significantly in coronary artery disease smokers. However, high-density lipoprotein-induced cellular cholesterol efflux was not increased by smoking cessation. In in vitro experiments, carbon monoxide reduced the antioxidative ability and nicotine enhanced the antichemotactic ability of high-density lipoprotein. Conclusions Smoking cessation is an effective measure to improve high-density lipoprotein functions in coronary artery disease smokers. Our study re-emphasizes the importance of smoking cessation in the secondary prevention of coronary artery disease.