Effects of cigarette smoke extract on mitochondrial function of macrophages

Abstract

Objective: To investigate the effects of cigarette smoke extract (CSE) on the mitochondrial function of macrophages. Methods: RAW264.7 macrophages were used for the experiment in this study. When the cell density was about 70%, the old culture medium was abandoned, and the 100% CSE stock solution was diluted with serum-free DMEM and FBS into 1%, 5%, 15%, 25% and 90% CSE and added to the well plate. The cell activity of RAW264.7 cells treated with CSE at different concentrations for 24 h was detected by CCK-8 method. Then the optimal CSE concentration was selected to treat cells for 0 h, 24 h, 48 h or 72 h respectively, and CCK-8 assay was used to detect the cell activity of CSE treated cells at different time groups. After the cells were treated with 0%, 5% and 25% CSE for 24 hours, cell necrosis and apoptosis was detected by Annexin V-FITC /PI staining; Mitochondrial membrane damage of RAW 264.7 was detected by mitochondrial membrane potential assay kit with JC-1; Macrophages were stained with ROS-specific dye DCFH-DA, and then Flow cytometer was used to determine the fluorescence and the proportion of ROS-positive macrophages; the enhanced ATP assay kit was used to detect the intracellular ATP concentration. Results: ①Compared with 0% CSE, cell viability was increased significantly in 1% CSE group (P＜0.01), cell viability was decreased significantly when CSE concentration was above 5% (P＜0.05); Macrophages were treated with 5% CSE, and cell viability was decreased significantly with the increase of treatment time (P＜0.01). ②Compared with 0% CSE, 5% CSE and 25% CSE mainly caused macrophage necrosis, decreased mitochondrial membrane potential, increased ROS production and decreased ATP significantly (P＜0.05 or P＜0.01), and the changes were more significant in 25% CSE treatment group(P＜0.05 or P＜0.01). Conclusion: CSE may affect mitochondrial function of macrophages, leading to decreased cell viability and necrosis.