Chronic cigarette smoking-induced oxidative/nitrosative stress in human erythrocytes and platelets

Abstract

Cigarette smoke contains a number of highly unstable free radicals and these free radicals enhance reactive oxygen species (ROS) and reactive nitrogen species (RNS) production leading to oxidative/nitrosative stress. Increased oxidative/nitrosative stress plays an important role in the onset of various vascular diseases. The aim of this study is to evaluate smoking-induced nitrosative and oxidative stress and the role of hypoxia inducible factor 1 alpha (HIF-1α) in erythrocytes and platelets. For this study human male volunteers aged 35±8 years were recruited and divided into two groups, namely controls and smokers (12±2 cigarettes per day for 7-10 years). Blood was collected and analyzed for various metabolites and enzymes. Results showed a decreased plasma vitamin C and reduced glutathione (GSH) with increased lipid peroxidation, carbonyl groups, iron, hemoglobin and glycated hemoglobin content in smokers. Furthermore, smokers showed higher nitrite/nitrate levels with increased eNOS protein expression in erythrocytes, in contrast, platelets showed lower nitrite/nitrate levels with decreased eNOS protein expression compared to controls. Moreover, smokers showed diminished GSH and the activities of superoxide dismutase (SOD) glutathione peroxidase (GPx) and catalase (CAT) in both erythrocytes and platelets compared to controls. Real time PCR analysis of whole blood from smokers showed increased HIF-1α and erythropoietin (EPO) gene expression compared to controls. In summary, smoking increased oxidative stress by decreasing antioxidant status in both red cells and platelets. Besides, smokers showed up-regulated HIF-1α gene expression, which inturn drives the transcription of eNOS and EPO genes under oxidative/nitrosative stress conditions.