V. Puzyrev

A Comparison of Genome-Wide DNA Methylation Patterns between Different Vascular Tissues from Patients with Coronary Heart Disease

Epigenetic mechanisms of gene regulation in context of cardiovascular diseases are of considerable interest. So far, our current knowledge of the DNA methylation profiles for atherosclerosis affected and healthy human vascular tissues is still limited. Using the Illumina Infinium Human Methylation27 BeadChip, we performed a genome-wide analysis of DNA methylation in right coronary artery in the area of advanced atherosclerotic plaques, atherosclerotic-resistant internal mammary arteries, and great saphenous veins obtained from same patients with coronary heart disease. The resulting DNA methylation patterns were markedly different between all the vascular tissues. The genes hypomethylated in athero-prone arteries to compare with atherosclerotic-resistant arteries were predominately involved in regulation of inflammation and immune processes, as well as development. The great saphenous veins exhibited an increase of the DNA methylation age in comparison to the internal mammary arteries. Gene ontology analysis for genes harboring hypermethylated CpG-sites in veins revealed the enrichment for biological processes associated with the development. Four CpG-sites located within the MIR10B gene sequence and about 1 kb upstream of the HOXD4 gene were also confirmed as hypomethylated in the independent dataset of the right coronary arteries in the area of advanced atherosclerotic plaques in comparison with the other vascular tissues. The DNA methylation differences observed in vascular tissues of patients with coronary heart disease can provide new insights into the mechanisms underlying the development of pathology and explanation for the difference in graft patency after coronary artery bypass grafting surgery.

Adult onset asthma and interaction between genes and active tobacco smoking: The GABRIEL consortium

Background Genome-wide association studies have identified novel genetic associations for asthma, but without taking into account the role of active tobacco smoking. This study aimed to identify novel genes that interact with ever active tobacco smoking in adult onset asthma. Methods We performed a genome-wide interaction analysis in six studies participating in the GABRIEL consortium following two meta-analyses approaches based on 1) the overall interaction effect and 2) the genetic effect in subjects with and without smoking exposure. We performed a discovery meta-analysis including 4,057 subjects of European descent and replicated our findings in an independent cohort (LifeLines Cohort Study), including 12,475 subjects. Results First approach: 50 SNPs were selected based on an overall interaction effect at p<10−4. The most pronounced interaction effect was observed for rs9969775 on chromosome 9 (discovery meta-analysis: ORint = 0.50, p = 7.63*10−5, replication: ORint = 0.65, p = 0.02). Second approach: 35 SNPs were selected based on the overall genetic effect in exposed subjects (p <10−4). The most pronounced genetic effect was observed for rs5011804 on chromosome 12 (discovery meta-analysis ORint = 1.50, p = 1.21*10−4; replication: ORint = 1.40, p = 0.03). Conclusions Using two genome-wide interaction approaches, we identified novel polymorphisms in non-annotated intergenic regions on chromosomes 9 and 12, that showed suggestive evidence for interaction with active tobacco smoking in the onset of adult asthma.

Genes for Fibrogenesis in the Determination of Susceptibility to Myocardial Infarction

A group of patients with ischemic heart disease and myocardial infarction (N = 156) and a reference population sample (N = 300) were genotyped for 58 single nucleotide polymorphisms (SNPs) in the genes involved in extracellular matrix function and collagen metabolism or associated with cardiovascular diseases and atherosclerotic plaque stability. Genotyping was performed by mass-spectrometry with two multiplex sets of 27 and 31 SNPs. The study revealed different genetic composition of predisposition to cardiovascular disease continuum (CVDC) syntropy (patients with concomitant conditions: hypercholesterolemia, hypertension, and type-II diabetes mellitus, N = 96) and to isolated myocardial infarction (without these conditions, N = 60). Only the KIAA1462 gene (rs3739998) showed associations with both CVDC syntropy (OR = 1.71; 95% CI 1.19–2.45; р = 0.003) and isolated infarction (OR = 1.58; 95% CI 1.05–2.40; р = 0.028). Isolated myocardial infarction was also associated with LIG1 (rs20579) (OR = 2.08; 95% CI 1.06–4.17; р = 0.028) and ADAMDEC1 (rs3765124) (OR = 1.63; 95% CI 1.07–2.50; р = 0.020). CVDC syntropy was associated with CDKN2BAS1 (rs1333049) (OR = 1.48; 95% CI 1.03–2.12; р = 0.029) and APOA2 (rs5082) (OR = 1.47; 95% CI 1.02–2.11; р = 0.035). So, genes involved in fibrogenesis contribute to predisposition to the myocardial infarction as well. Isolated myocardial infarction and CVDC syntropy can be considered as pathogenetically different cardiovascular conditions, with different genes that contribute to the susceptibility.

Association of mitochondrial DNA polymorphism with myocardial infarction and prognostic signs for atherosclerosis

We performed an association analysis for the mtDNA major common variants and haplogroups with incidence of myocardial infarction and essential prognostic characteristics in patients. A comparison of patients (N = 406) and control groups (N = 183) uncovered a higher frequency of HV0 haplogroup in patients (6.9% vs. 2.2%; p = 0.033). Patients with early infarction (before age of 55 in men) had a higher frequency of 16189C variant, compared to patients who endured first infarction at age older than 55 (24.1% vs. 12.5%; p = 0.008). In addition, haplogroup U2e was only detected in the subgroup with early infarction (4.4%; p = 0.004). Haplogroup U5 was less frequent in patients with early infarction (5.1% vs. 15.4%; p = 0.002). Observations during a 1-year follow-up uncovered that patients with recurring cardiovascular incidents had higher frequency of haplogroup H1 (20%, versus 4.5% in patients without complications, p = 0.002) and variant 16189C (30% versus 13.5%; p = 0.018). Haplogroup U5 was more frequent in the subgroup of patients with lower (<40%) ventricular ejection fraction (17.1%, compared to 8.2%; p = 0.034). Thus, our results indicate that mtDNA polymorphism contributes to coronary atherosclerosis. The obtained associations can be explained by the effect of polymorphisms on oxidative phosphorylation and the production of reactive oxygen species in mitochondria.

Fibrogenesis Genes and Susceptibility to Coronary Atherosclerosis

OBJECTIVESnTo study associations between genes of different functional classes, including fibrogenesis genes, with coronary atherosclerosis and specific features of its course.nnnMETHODSnWe included in this study 404 patients with confirmed chronic ischemic heart disease (IHD) who had undergone coronary artery bypass grafting. Two groups of participants were distinguished - those with (n=188) and without (n=216) history of myocardial infarction (MI). Control group consisted of inhabitants of the Siberia region (n=285). Associations were analyzed using 48 single nucleotide polymorphisms (SNP) located in genes earlier determined as associated with diseases of the cardiovascular continuum (diabetes mellitus, MI, atherosclerosis). Multiplex genotyping was performed using mass spectrometry. For statistical analyses we used Statistica v8.0 and R-language with stats and genetics packages.nnnRESULTSnWe identified several genetic markers contributing to susceptibility to development of atherosclerosis. Same markers were identified as determinants of the character of the course of atherosclerotic disease. Risk of development of atherosclerosis was higher in carriers of the following genotypes: TT of ITGB5 gene (rs1007856) - by 1.6 times (OR=1.59; р=0.0153); GG of ITGA4 gene - by 1.85 times (OR=1.85; р=0.0016); GG of IGFBP7 gene (rs11133482) - by 2.4 times (OR=2.36; р=0.0031). The following genotypes were identified as protective against MI and determining stable course of the disease: AA of TLR4 gene (rs4986790) (OR=0.47; р=0.0104).; CC of LDLR gene (rs2738446) (OR=0,53; р=0.0041); GG of OAS1 gene (rs1131454) (OR=0.50; р=0.0274).nnnCONCLUSIONnSusceptibility to coronary atherosclerosis and prognosis of disease progression were found to be associated with polymorphism of certain genes, involved in metabolism of the extracellular matrix and processes of fibrogenesis (ADAMDEC1, ITGA4, ITGB5, CDKN2B-AS1, IGFBP7), lipid metabolism (LDLR), immune system functioning (TLR4, OAS1) and DNA repair (LIG1).

Analysis of Heteroplasmy in the Major Noncoding Region of Mitochondrial DNA in the Blood and Atherosclerotic Plaques of Carotid Arteries

For identification of somatic mitochondrial DNA (mtDNA) mutations, the mtDNA major noncoding region (D-loop) sequence in blood samples and carotid atherosclerosis plaques from patients with atherosclerosis was analyzed. Five point heteroplasmic positions were observed in 4 of 23 individuals (17%). Only in two cases could heteroplasmy have resulted from somatic mutation, whereas three heteroplasmic positions were found in both vascular tissue and blood. In addition, length heteroplasmy in a polycytosine stretches was registered at nucleotide positions 303–315 in 16 individuals, and also in the 16184–16193 region in four patients. The results suggest that somatic mtDNA mutations can occur during atherosclerosis, but some heteroplasmic mutations may appear in all tissues, possibly being inherited.

Mitochondrial DNA polymorphism association with myocardial infarction and prognostic signs for atherosclerosis

We have performed association analysis for mtDNA most common variants and haplogroups with myocardial infarction and some prognostic characteristics in patients. Comparison of patients (N=406) and controls (N=183) has shown higher frequency of HV0 haplogroup in patients (6.9% vs. 2.2%; p=0.033). Patients with early infarction (before age 55), comparing to patiens older than 55 and the first infarction, had higher frequency of 16189C variant (24.1 vs. 12.5%; p=0.008); also, haplogroup U2e was registered only in the subgroup with early infarction (4.4%; p=0.004). On the other side, haplogroup U5 was less frequent in the patients with early infarction (5.1% vs. 15.4%; p=0.002). The patients with recurring cardiovascular incidents during one year follow-up had higher frequency of haplogroup H1 (20% versus 4.5% in the patients without complications, p=0.002) and variant 16189C (30% versus 13.5%; p=0.018). Haplogroup U5 was more frequent in the group of patients with left ventricular ejection fraction less than 40%: 17.1% comparing to 8.2% in the group with ejection fraction>40%; p=0.034. The results suggest that mtDNA polymorphism contributes to coronary atherosclerosis. The associations could be explained by the polymorphism effect on oxidative phosphorylation and reactive oxygen production in mitochondria.