Cigarette smoking has been associated with an increase in the severity and prevalence of atherosclerosis in the abdominal aorta. To begin our investigation of this finding, we used an integrated approach combining gene expression profiling, protein analysis, cytokine measurements, and cytotoxicity determinations to examine molecular responses of cultured human aortic and coronary endothelial cells exposed to cigarette smoke condensate (CSC) and nicotine. Exposure of endothelial cells to CSC (30 and 60 microg/mL TPM) for 24 h resulted in minimal cytotoxicity, and the upregulation of genes involved in matrix degradation (MMP-1, MMP-8, and MMP-9), xenobiotic metabolism (HO-1 and CYP1A2), and downregulation of genes involved in cell cycle regulation (including TOP2A, CCNB1, CCNA, CDKN3). Exposure of cells to a high physiological concentration of nicotine resulted in few differentially expressed genes. Immunoblot analysis of proteins selected from genes shown to be differentially regulated by microarray analysis revealed similar responses. Finally, a number of inflammatory cytokines measured in culture media were elevated in response to CSC. Together, these results describe a complex proinflammatory response, possibly mediating the recruitment of leukocytes through cytokine signaling. Additionally, fibrous cap destabilization may be facilitated by matrix metalloproteinase upregulation.

Matrix metalloproteinase-1 (MMP-1) is involved in the degradation of extra-cellular matrix components and is thought to play a key role in atherogenesis. The objective of the present study was to determine: (1) whether MMP-1 differential gene expression observed in primary cultures of human aortic endothelial cells (HAEC) exposed to cigarette smoke condensate (CSC) was associated with a single nucleotide polymorphism (SNP) in its promoter region and (2) if the SNP altered atherosclerotic lesion development in smokers and nonsmokers. Genotype analysis of six HAEC lines revealed that those homozygous for the 1G-variant exhibited low levels of gene expression. Cells homozygous for the 2G-variant or heterozygous (1G/2G) had elevated levels of both mRNA and protein. These relative levels were also seen after CSC expo-sure. MMP-1 genotypes of 104 Caucasian males acquired from the Pathobiological Determinants of Atherosclerosis in Youth study were compared with the extent of atherosclerotic lesion development in the aorta. The results indicate that, although the MMP-1 SNP influences MMP-1 gene expression in cultured HAEC exposed to CSC, differences in lesion development were not observed based on this polymorphism in young Caucasian males.