Potential Effects Of Hyperglycem Versus Oxidized Low-density Lipoprotein Versus On Atherosclerosis Related Genes

Back Groud and OBJECTIVES: Lipid peroxidation and Diabetes are two primary risk factor proposed to be involved in the pathogenesis of atherosclerosis (AS). Synergy between the two exists at different stages in the development of AS. Among various forms of lipid, oxidized low-density lipoprotein (ox-LDL) is generally acknowledged to be the primary risk factor for the development of AS. Individuals with diabetes have increased rates of all forms of cardiovascular disorders including atherosclerosis.One manifestation of diabetes is glucose metabolic disturbance, in most time it is hyperglycem. In this study, we investigated the potential effects of ox-LDL and on converting monocytes/macrophages to foam cells and analyzed the gene expression profiling changes into THP-1 derived cells upon exposure to ox-LDL and hyperglycem, which may provide a novel strategy for the prevention and treatment of coronary artery disease.METHODS: THP-1 cells were used as the model of monocytes in vitro. They were exposed to Phorbol 12-myristate 13-acetate (PMA 160nmol/L) for 48 hours and then divide to three groups.In one group THP-1 cells were exposed to glucose(30mmol/L) for 72 hours. In second group THP-1 cells were exposed to ox-LDL(50ug/mL) for 72 hours.In last group THP-1 cells were exposed to glucose(30mmol/L)+ Ox-LDL(50ug/mL) ,were exposed to Ox-LDL(50ug/mL) for 72 hours as control.Formation of foam cells were identified by Oil-red-O stain and the observation through electronic microscope. Gene expression profiles were investigated, using BiostarH-40s cDNA microarray (consisting of 4096 sequence-verified human cDNA).RESULTS: THP-1 cells differentiated into mature macrophages after exposed to PMA for 48 hours. 1: In Group one THP-1 cells neither oil-red-O stain nor observation through electronic microscope indicated the formation of foam cells.2:In group two THP-1 cells further exposure to Ox-LDL for 72 hours led to the formation of foam cells which was indicated by oil-red-0 stain. The lipid droplets in the cells were observed under electronic microscope. By comparing transcript profiles of exposed/unexposed cells, 87 genes with more than 3 fold of altered expression levelsin response to Ox-LDL exposure were identified, among which, 58 were down-regulated and 29 were up-regulated. Those genes were mainly involved in lipid metabolism, initiation and development of inflammation, cell apoptosis and protection of injury.3:In group three THP-1 cells after the macrophages exposed to glucose(30mmol/L)+ Ox-LDL(50ug/mL)for 72 hours led to the formation of foam cells which was indicated by oil-red-0 stain. The lipid droplets in the cells were observed under electronic microscope. Under the criteria of 3 fold, 109genes with altered expression levels in response to exposure glucose+ Ox-LDL were identified, among which, 78 were down-regulated and 31 were up-regulated. CONCLUSION: 1. Hyperglycem alone can not convert the THP-1 cells to foam cells.2.Foam cells form when THP-1 cells are incubated with Ox-LDL. The microarray offers the opportunity to make a parallel hybridization of thousands different genes simultaneously and thus provides unprecedented resolution for relatively unbiased genetic profiling. The gene expression profiling changes identified in this study are involved in lipid metabolism, inflammation, cell apoptosis and stress which may be relative to the initiation and development of AS.3. Hyperglycem advance Foam cells form when THP-1 cells are incubated with Ox-LDL. Our study identified candidate genes and markers for further studies into the pathogenesis of atherosclerosis.