Identification of differently metylated genes potentially related to human atherosclerosis

Abstract

Aim. Identification of the genes, different in the level of DNA methylation among the cells of intact or atherosclerotic arteries in patients with coronary and carotid atherosclerosis. Material and methods. Into the study group, atherosclerosis patients were included, who had undergone coronary bypass surgery or carotid endarterctomy, and relatively healthy individuals. The assessment of methylation level of various 27578 CpG-sites/14475 genes was done with the microchip Infinium Human Methylation27 BeadChip (Illumina) in the specimens of atherosclerotically changed coronary (n=6), carotid (n=6), intact internal thoracal arteries (n=8) and large saphenous veins (n=8). Level of methylation in the locus 2q31.1 (HOXD4/HOXD3/ MIR10B) was measured with bisulphite pyrosequencing of DNA in the vessels specimens and leucocytes of the same patients (n=130), as in the leucocytes of relatively healthy men (n=110). Results. In the cells of atherosclerotically changed arteries, comparing to intact vessels, the change of methylation level by 20% and more is found for 46 CpG-sites/ 42 genes (pFDR <0,05). Of those 8 genes (TLR4, TRAF1, ABCB11, NPR2, ALOX12, TMEM182, ALX4 и FABP1) are known candidates for atherosclerosis or its risk factors by the results of genetics studies. Most number of CpG sites, where the highest decrease of methylation found in the cells of atherosclerotically changed arteries comparing to the intact, were located in the locus 2q31.1, with the genes HOXD4/HOXD3/MIR10B. In leucocytes of patients the level of methylation of one of the CpG-sites in locus 2q31.1 (HOXD4/HOXD3/MIR10B) higher in smokers (18±5%), than non-smokers (14±6%; p<0,05), and level of methylation of one of CpG-sites in this area of genome is lower in those who had previous ischemic stroke (18±8%) comparing to those with no stroke anamnesis (20±7%; p<0,05). Conclusion. Lowest part of the identifiable differently methylated genes among the cells of lesioned arteries and intact vessels is related to atherosclerosis or its risk factors as a result of genetic studies on genetic associations. It is found that the change of methylation level in locus 2q31.1 (HOXD4/HOXD3/MIR10B) is associated with atherosclerotic lesion of arteries, and in leucocytes of patients the grade of methylation in the studied region of genome is related to smoking and ischemic stroke.