Marina Bykanova

Altered erythrocyte membrane protein composition mirrors pleiotropic effects of hypertension susceptibility genes and disease pathogenesis.

Objective: The study was designed to assess the effects of polymorphisms in genes associated with essential hypertension on the variation of erythrocyte membrane proteins (EMPs) in hypertensive patients. Methods: Major EMPs content was analyzed in blood from 1162 unrelated Russians (235 hypertensive patients, 176 healthy controls, and 751 random individuals from the Central Russia population). Essential hypertension patients were genotyped for 11 polymorphisms of essential hypertension susceptibility genes including ADD1 (rs4961), GNB3 (rs5443, rs16932941), NOS3 (rs1799983, rs2070744), ACE (rs5186), AGTR1 (rs5186), AGT (rs699, rs4762), MR (rs5534), and TGFB1 (rs1800471). EMP contents and their relationship with the genetic loci were analyzed using various statistical tests. Results: Sex-specific differences in EMP contents between the cases and controls were observed. Regardless of sex, hypertensives exhibited mainly decreased levels of alpha (SPTA1) and beta-spectrin (SPTB) and increased levels of glucose transporter (GLUT1) as compared with healthy subjects (P ⩽ 0.001). EMP correlated differently in essential hypertension patients and controls. Almost 70% of the joint variation in the EMP levels is explained by five gender-specific principal components. The essential hypertension susceptibility genes showed considerable effects on the levels of spectrins and glucose transporter. A joint variation of the genes explained about half the total polygenic variance in the GLUT1, SPTA1, and SPTB levels in hypertensives. Conclusions: The study showed that essential hypertension susceptibility genes are the important factors of the inherited EMP variation, and their pleitropic effects may be mirrored in the altered expression of genes encoding cytoskeletal proteins and those related to intracellular glucose metabolism.

Polymorphisms of CYP2C8, CYP2C9 and CYP2C19 and risk of coronary heart disease in Russian population

Epoxyeicosatrienoic acids (EETs) are important vasoactive products of arachidonic acid metabolism with a wide range of biological actions in the cardiovascular system. The present study investigated whether single nucleotide polymorphisms (SNP) of genes coding cytochrome P450 2C subfamily, enzymes involved in biosynthesis of EETs, are associated with the risk of coronary heart disease (CHD). A total of 1255 unrelated Russian subjects comprising 561 patients with angiographically diagnosed CHD and 694 age- and sex-matched healthy subjects were included in the study. DNA samples from all study participants were genotyped for six common SNPs rs7909236, rs1934953 of CYP2C8, rs9332242, rs4918758 and rs61886769 of CYP2C9 and rs4244285 of CYP2C19 using by the Mass-ARRAY 4 system. SNP rs4918758 of CYP2C9 was associated with decreased risk of CHD (codominant model) at a borderline significance with odds ratio adjusted for sex and age 0.61 (95% CI: 0.41-0.92, P=0.038, Q=0.20). SNP rs9332242 of CYP2C9 showed a trend towards association with increased CHD risk in cigarette smokers (P=0.049, Q=0.29). Log-likelihood ratio test (LRT) pointed out epistatic interactions between rs9332242 and rs61886769 of CYP2C9 (codominant model, Pinteraction=0.02), however, this P-value did not survive after correction for multiple tests. Bioinformatic analysis revealed a regulatory potential for a majority of the investigated SNPs. Our preliminary results demonstrate that polymorphisms of genes encoding CYP2C subfamily represent potential genetic markers of CHD susceptibility. Further studies are required to substantiate the contribution of these genes to the disease risk.

A Novel Polymorphism in the Promoter of the CYP4A11 Gene Is Associated with Susceptibility to Coronary Artery Disease

Enzymes CYP4A11 and CYP4F2 are involved in biosynthesis of vasoactive 20-hydroxyeicosatetraenoic acid and may contribute to pathogenesis of coronary artery disease (CAD). We investigated whether polymorphisms of the CYP4A11 and CYP4F2 genes are associated with the risk of CAD in Russian population. DNA samples from 1323 unrelated subjects (637 angiographically confirmed CAD patients and 686 age- and sex-matched healthy individuals) were genotyped for polymorphisms rs3890011, rs9332978, and rs9333029 of CYP4A11 and rs3093098 and rs1558139 of CYP4F2 by using the Mass-ARRAY 4 system. SNPs rs3890011 and rs9332978 of CYP4A11 were associated with increased risk of CAD in women: OR = 1.26, 95% CI: 1.02–1.57, P = 0.004, and Q = 0.01 and OR = 1.45, 95% CI: 1.13–1.87, P = 0.004, and Q = 0.01, respectively. Haplotype G-C-A of CYP4A11 was associated with increased risk of CAD (adjusted OR = 1.41, 95% CI: 1.12–1.78, and P = 0.0036). Epistatic interactions were found between rs9332978 of CYP4A11 and rs1558139 of CYP4F2 (P interaction = 0.025). In silico analysis allowed identifying that SNP rs9332978 is located at a binding site for multiple transcription factors; many of them are known to regulate the pathways involved in the pathogenesis of CAD. This is the first study in Europeans that reported association between polymorphism rs9332978 of CYP4A11 and susceptibility to coronary artery disease.

The contribution of CYP2C gene subfamily involved in epoxygenase pathway of arachidonic acids metabolism to hypertension susceptibility in Russian population

ABSTRACT Numerous studies demonstrated an importance of cytochrome P-450 epoxygenase pathway of arachidonic acids metabolism for the pathogenesis of essential hypertension (EH). The present study was designed to investigate whether common single-nucleotide polymorphisms (SNP) of CYP2C gene subfamily such as CYP2C8 (rs7909236 and rs1934953), CYP2C9 (rs9332242), and CYP2C19 (rs4244285) are associated with susceptibility to EH in Russian population. A total of 816 unrelated Russian individuals comprising 425 EH patients and 391 normotensive controls were included into the study. Genotyping of SNPs was performed using the MassARRAY 4 system. SNP rs7909236 of CYP2C8 was significantly associated with increased risk of EH (OR adjusted for sex and age was 2.99 95% CI 1.39-6.44, P = 0.005). SNPs rs1934953 CYP2C8 and rs4244285 of CYP2C19 showed association with EH risk but at a borderline statistical significance (P ≤ 0.04). Combination of genotypes CYP2C8 rs7909236 TT and CYP2C19 rs4244285 GG was associated with increased EH risk (OR 3.34 95%CI 1.48-7.51, P = 0.004). Genotype–phenotype correlation analysis showed that the levels of CYP2C8 mRNA were significantly correlated with SNP rs7909236 (P = 0.01). in silico functional prediction analysis revealed the functionality of majority of investigated SNPs. Thus, genes of CYP2C subfamily are important genetic determinants of susceptibility to essential hypertension in Russians.

[PP.07.16] THE RELATIONSHIP BETWEEN GENES INVOLVING IN ARYL HYDROCARBON RECEPTOR SIGNALING PATHWAY AND RISK OF ESSENTIAL HYPERTENSION

Objective: The purpose of this study was to investigate whether polymorphisms in genes involving aryl hydrocarbon receptor (AHR) signaling pathway are associated with the risk of essential hypertension (EH). Design and method: A genetic association study of the AHR signaling pathway gene polymorphisms with essential hypertension in Russian population. A total of 1908 unrelated Russian subjects including 1140 EH patients and 768 age and sex matched normotensive controls were recruited for this study. Seven common functional polymorphisms such AHR R554K (rs2066853), ARNT 567G > C (rs2228099), AHRR Pro185Ala (rs2292596), CYP1A1 I462 V (rs1048943), CYP1A2 154C > A (rs762551), CYP1B1 V432L (rs1056836), NQO1 P187S (rs1800566) were selected for the study. The polymorphisms were genotyped using TaqMan-based assays. Results: We found that carriers for variant genotypes (567GC plus CC) of the ARNT gene were at an increased risk of EH (odds ratio = 1.23; 95% confidence interval: 1.02–1.48, P = 0.03). Moreover, a genotype 154AA of the CYP1A2 gene was associated with decreased risk of EH (odds ratio = 0.74; 95% confidence interval: 0.55–0.98, P = 0.04). Conclusions: To the best of our knowledge, this is the first study reporting associations between AHR signaling pathway genes and the risk of essential hypertension. AHR signaling represents a very promising target for prevention and treatment of hypertension due to its role in heart and vascular physiology, blood pressure regulation and vascular nitric oxide generation. However, AHR is an orphan nuclear receptor with a primary function of mediating xenobiotic metabolism through transcriptional activation of Phase I and Phase II biotransformation enzymes, suggesting a potential role of this pathway in the mechanisms of air pollution-induced hypertension. Our preliminary study findings demonstrate a potential importance of polymorphic genes mediating adaptive and toxic responses to environmental xenobiotics such as halogenated aromatic hydrocarbons in the development of human hypertension. Further investigations are required to confirm the contribution of these genes to essential hypertension risk in independent populations, to assess gene-environment interactions underlying this susceptibility and to designate novel options for disease treatment and prevention. The study was supported by Russian Science Foundation (number 15–15-10010).

[PP.07.15] A PROMOTER POLYMORPHISM -271C > A OF THE CYP2C8 GENE IS ASSOCIATED WITH INCREASED RISK OF ESSENTIAL HYPERTENSION: A PILOT STUDY

Objective: The purpose of our pilot study was to investigate associations between polymorphisms of the CYP2C8 gene with susceptibility to essential hypertension (EH) in Russian population. Design and method: A genetic association study of common polymorphisms of the CYP2C8 gene with essential hypertension in Russian population. A total of 1 459 unrelated Russian individuals (Kursk region) including 845 EH patients and 614 age and sex matched healthy subjects with normal blood pressure were recruited for this study. Two common polymorphisms −271C > A (rs7909236) and 404G > A (rs1934953) of the CYP2C8 gene were genotyped using the MassARRAY 4 system. Results: Genotype frequencies of CYP2C8 gene polymorphisms were in agreement with Hardy–Weinberg equilibrium in all groups. We found that variant genotypes −271CA plus AA were significantly associated with increased hypertension risk (odds ratio = 1.31; 95% confidence interval: 1.04–1.64, P = 0.02). The association remained a statistically significant after adjustment for age, sex and body mass index by a multiple logistic regression analyses (P = 0.03). Moreover, a homozygous variant genotype 404AA tended to be associated with an increased risk of EH (odds ratio = 1.41; 95% confidence interval: 0.98–2.02, P = 0.06). However, no significant association was found between rs1934953 and EH after adjusting for the covariates. Conclusions: CYP2C8 is a cytochrome P450 enzyme involving in the generation epoxyeicosatrienic acids (EETs) from arachidonic acid, an important biochemical pathway creating mediators of inflammation and blood pressure regulation. A polymorphism −271C > A located in the promoter region of the CYP2C8 results in the creation of a C/EBPalpha transcription factor consensus sequence influencing a transcriptional activity of the gene. The −271C > A polymorphism of the CYP2C8 gene may contribute to hypertension susceptibility through the mechanisms related with biosynthesis of vascular EETs and those inducing oxidative stress by reactive oxygen species which are generated during the epoxidation of arachidonic acid by the CYP450 epoxygenase. Our pilot study is the first to show that the −271C > A polymorphism of the CYP2C8 gene is associated with increased risk of hypertension. The study was supported by Russian Science Foundation (number 15-15-10010).

[PP.07.13] THE C3435T POLYMORPHISM OF THE ABCB1 GENE INCREASES THE RISK OF ESSENTIAL HYPERTENSION IN CIGARETTE SMOKERS

Objective: The present study was designed to examine a relationship between common polymorphism C3435T of the ABCB1 gene and risk of essential hypertension (EH) and to test the hypothesis whether associations of the ABCB1 genotypes with disease risk is modified by smoking status. Design and method: A genetic association study of polymorphism C3435T of the ABCB1 gene with essential hypertension in Russian population. A total of 2 220 unrelated Russian individuals from Central Russia were recruited for this study. The study participants included 1 370 EH patients and 850 age and sex matched healthy subjects. Genotyping of polymorphism C3435T (rs1045642) of the ABCB1 gene was done through a TaqMan-based assay. Results: We found that the carriers of variant genotypes (i.e. 3435CT plus TT) of the ABCB1 gene possessed an increased risk of EH (odds ratio = 1.23; 95% confidence interval: 1.02–1.48, P = 0.03). The gene-smoking interaction analysis has revealed that a carriage of the 3435CT/TT genotypes is associated with increased EH risk only in cigarette smokers (OR = 1.42 95%CI 1.04–1.94, P = 0.03), whereas non-smoker carriers of these genotypes were not at disease risk. This association remained a statistically significant after adjustment for age, sex and body mass index by a multiple logistic regression analyses (P = 0.04). Conclusions: This is the first study reporting that the association of ABCB1 C3435T polymorphism with hypertension is modified by smoking status. ABCB1 is a membrane-associated P-glycoprotein regulating an ATP-dependent drug efflux pump for xenobiotic compounds with broad substrate specificity. The 3435T variant is known to cause a decreased activity/expression of P-glycoprotein. It was reported that the ABCB1 expression is downregulated in peripheral blood mononuclear cells of spontaneously hypertensive rats. Our study finding suggests that since P-glycoprotein functions as a transporter of xenobiotic compounds in the blood-brain barrier, a decreased ABCB1 activity/expression in smokers with the variant genotypes may cause high blood pressure possibly through an enhanced sympathetic stimulation due to the accumulation of tobacco-related toxicants in the brain. The study was supported by Russian Science Foundation (number 15–15–10010).