Risk factor–gene interaction in carotid atherosclerosis: effect of gene polymorphisms of renin-angiotensin system

The Effect of ACE Gene Polymorphisms on Doppler Blood Flow Parameters of Carotid and Brachial Arteries in Patients With Myocardial Infarction

The authors investigated the relationship between the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and the blood flow characteristics of common carotid (CCA) and brachial arteries (BA) by color Doppler ultrasound (CDUS) in patients with acute anterior myocardial infarction (AAMI). Sixty four patients (11 women and 53 men), aged 25 to 77 years, with AAMI were studied. The ACE genotypes were established. Peak-systolic (PSV) and end-diastolic velocity (EDV) of right and left CCA, PSV of right BA, and intimal-medial thickness (IMT) of both CCAs were measured by CDUS. All results were evaluated statistically. The ACE genotypes were distributed as follows: 43.8% DD, 43.8% ID, and 12.5% II. PSVs of BA and both CCAs were lower in patients with DD and ID than with II (p<0.05). EDVs of both CCAs were also lower in the same groups, but statistically not significant (p>0.05). IMTs of both CCAs did not differ among patients with various ACE genotypes (p>0.05). These results suggest that ACE I/D polymorphism influences Doppler blood flow parameters of both BA and CCA, but does not affect IMT of CCA.

APOE polymorphism and carotid atherosclerosis in Korean population: the Dong-gu Study and the Namwon Study

OBJECTIVE

We evaluated the association between APOE polymorphism and carotid atherosclerosis in two large independent cohorts from South Korea.

METHODS

The datasets were from the Dong-gu Study (N = 9056) and the Namwon Study (N = 10,158). Carotid ultrasonography was performed to measure carotid intima-media thickness (IMT) and the presence of carotid plaques. The APOE polymorphism was determined by PCR-RFLP. We performed combined and separate analyses for the two datasets.

RESULTS

In the combined analysis, individuals with E2E2 or E2E3 genotype had a lower common carotid IMT compared with individuals with E3E3 genotype (0.684 mm vs. 0.736 mm, p = 0.007; 0.718 mm vs. 0.736 mm, p < 0.001, respectively). This association was very slightly attenuated but remained statistically significant after adjustment for blood lipids (0.690 mm vs. 0.736 mm, p = 0.033; 0.725 mm vs. 0.736 mm, p = 0.005, respectively). Compared with individuals with E3E3 genotype, individuals with E2E3 genotype had lower risk for carotid plaque (odds ratio (OR) = 0.83, 95% confidence interval (CI) = 0.75-0.93), while individuals with E3E4 genotype had a higher risk for carotid plaque (OR = 1.09, 95% CI = 1.00-1.20). After adjustment for blood lipids, ORs of E2E3 genotype for carotid plaque was slightly attenuated but remained significant (OR = 0.87 95% CI = 0.78-0.97), while OR of E3E4 genotype were slightly attenuated and not significant (OR = 1.08, 95% CI, 0.99-1.18).

CONCLUSIONS

We found that APOE polymorphism is associated with carotid atherosclerosis and this association was partly mediated through blood lipid. Our results suggest that APOE polymorphism may influence atherosclerosis through non-lipid pathways.

Subclinical atherosclerosis, airflow obstruction and emphysema: the MESA Lung Study

Airflow obstruction is an independent risk factor for cardiovascular events in the general population. The affected vascular bed and contribution of emphysema to cardiovascular risk are unclear. We examined whether an obstructive pattern of spirometry and quantitatively defined emphysema were associated with subclinical atherosclerosis in the carotid, peripheral and coronary circulations. The Multi-Ethnic Study of Atherosclerosis recruited participants aged 45-84 yrs without clinical cardiovascular disease. Spirometry, carotid intima-media thickness (IMT), ankle-brachial index (ABI) and coronary artery calcium (CAC) were measured using standard protocols. Percentage of emphysema-like lung was measured in the lung windows of cardiac computed tomography scans among 3,642 participants. Multiple linear regression was used to adjust for cardiac risk factors, including C-reactive protein. Decrements in forced expiratory volume in 1 s (FEV(1)) and FEV(1)/forced vital capacity ratio were associated with greater internal carotid IMT, particularly among smokers (p=0.03 and p<0.001, respectively) whereas percentage emphysema was associated with reduced ABI regardless of smoking history (p=0.004). CAC was associated with neither lung function (prevalence ratio for the presence of CAC in severe airflow obstruction 0.99, 95% CI 0.91-1.07) nor percentage emphysema. An obstructive pattern of spirometry and emphysema were associated distinctly and independently with subclinical atherosclerosis in the carotid arteries and peripheral circulation, respectively, and were not independently related to CAC.

The epidemiology of vascular dysfunction relating to chronic obstructive pulmonary disease and emphysema

Cor pulmonale has long been described in very severe chronic obstructive pulmonary disease (COPD) and emphysema. Cross-sectional results from population-based studies show that left ventricular filling and a variety of vascular measures in the systemic circulation are abnormal in preclinical COPD and emphysema and that a predominant vascular change in COPD and emphysema is endothelial and microvascular dysfunction. These findings suggest that pulmonary vascular changes may occur early in COPD and emphysema and might contribute to pathogenesis. However, longitudinal epidemiologic studies with direct measures of the pulmonary vasculature are lacking; therefore, inferences are limited at present. New imaging-based approaches to the assessment of the pulmonary vasculature are applicable to epidemiologic studies and may help in defining the relationship of pulmonary vascular damage to progression of COPD and emphysema. These measures may also provide imaging-based surrogate markers, and novel therapeutics targeted to the pulmonary vasculature might reduce symptoms and improve function in these common diseases.

Recurrence and long-term maternal health risks of hypertensive disorders of pregnancy: a population-based study

OBJECTIVE

The purpose of this study was to investigate the recurrence risk of hypertensive disorders in subsequent pregnancies and to explore the associations among hypertensive disorders of pregnancy and maternal cardiovascular risk factor profile and the development of cardiovascular diseases later in life.

STUDY DESIGN

We used population-based, cross-sectional data from the fourth survey of the Tromsø Study.

RESULTS

Preeclampsia in the first pregnancy increased the risk of recurrence in later pregnancies (relative risk, 6.6; 95% confidence interval, 5.5-7.9) compared with a normotensive first pregnancy. Women with a history of preeclampsia or nonproteinuric hypertension had an unfavorable cardiovascular risk profile. Hypertension was prevalent in 25% and 28% of the women, respectively. The carotid artery intima-media thickness and total carotid plaque area were significantly larger in women with previous preeclampsia.

CONCLUSION

A strong association between hypertensive disorders of pregnancy and an increased risk of atherosclerosis and cardiovascular diseases was demonstrated by the assessment of risk factors that can be potentially modified.

AT1 Receptor Gene Polymorphisms in relation to Postprandial Lipemia

Background. Recent data suggest that the renin-angiotensin system may be involved in triglyceride (TG) metabolism. We explored the effect of the common A1166C and C573T polymorphisms of the angiotensin II type 1 receptor (AT1R) gene on postprandial lipemia.Methods. Eighty-two subjects measured daytime capillary TG, and postprandial lipemia was estimated as incremental area under the TG curve. The C573T and A1166C polymorphisms of the AT1R gene were determined.Results. Postprandial lipemia was significantly higher in homozygous carriers of the 1166-C allele (9.39±8.36 mM*h/L) compared to homozygous carriers of the 1166-A allele (2.02±6.20 mM*h/L) (P<0.05). Postprandial lipemia was similar for the different C573T polymorphisms.Conclusion. The 1166-C allele of the AT1R gene seems to be associated with increased postprandial lipemia. These data confirm the earlier described relationships between the renin-angiotensin axis and triglyceride metabolism.

Carotid atheromatic plaque is commonly associated with hypopituitary men

Hypopituitarism increases the risks of many cardiovascular conditions and therefore, patients with this disease are more prone to cardiovascular disease. To our knowledge, there have been few studies on carotid artery plaque in male patients with hypopituitarism in assessing cardiovascular risks. The aim of this study was to specifically compare carotid artery plaque while examining other major cardiovascular risk factors between male patients with hypopituitarism and control subjects. Forty male patients aged 30-70 years with hypopituitarism and forty age, sex- matched control subjects were recruited at the Yonsei University Severance Hospital, Seoul, Korea. Carotid intima media thickness (IMT) and atheromatous plaque, anthropometry, lipid profile, and pituitary hormones were assessed. Atheromatous plaque in the carotid arteries was observed more frequently in patients with hypopituitarism than age- and sex-matched control subjects (59.5% vs. 2.5%, P<0.01) without differences of carotid IMTs. Patients with hypopituitarism also exhibited higher waist circumference, waist to hip ratio, total cholesterol and LDL cholesterol than control subjects. In subgroup analysis in male patients with hypopituitarism including GH deficiency, lower testosterone levels were associated with higher waist circumference (r=0.446, P=0.033). In conclusion, hypopituitary males exhibit an increased incidence of carotid artery plaque without differences of carotid IMTs, central obesity and higher total cholesterol level. Lower testosterone levels were associated with central obesity- a strong component of a metabolic syndrome, and unsubstituted testosterone deficiency might be an important cardiovascular risk factor in patients with hypopituitarism.

Pharmacogenetic interactions between Angiotensin-converting enzyme insertion/deletion polymorphism and response to cibenzoline in patients with hypertrophic obstructive cardiomyopathy

Cibenzoline, a Class I antiarrhythmic agent, can attenuate the left ventricular pressure gradient (LVPG) in patients with hypertrophic obstructive cardiomyopathy (HOCM). An association between the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene and the progression of left ventricular hypertrophy in patients with hypertrophic cardiomyopathy has been reported. The aim of this study was to investigate the pharmacogenetic interactions between the ACE insertion/deletion polymorphism and the response to cibenzoline in patients with HOCM. Twenty-four patients with HOCM participated in this study. The LVPG and left ventricular function were measured by echocardiography before and 2 hours after administration of a single oral dose of 200 mg cibenzoline. The ACE insertion/deletion polymorphism was genotyped. The frequencies of the genotypes D/D, D/I, and I/I were 16%, 42%, and 42%, respectively. Before administration of cibenzoline, the LVPG was higher in patients with the D allele than in those without it (105 +/- 47 mm Hg versus 64 +/- 24 mm Hg, P = 0.0195). After administration of cibenzoline, the LVPG significantly decreased to 41 +/- 27 mm Hg in those with the D allele (P = 0.0001) and to 33 +/- 24 mm Hg in those without it (P = 0.0003). The LVPG in patients with the D allele was significantly decreased by cibenzoline when compared with patients without the allele (64 +/- 45 mm Hg versus 31 +/- 17 mm Hg, P = 0.038). Patients with HOCM with the ACE D allele had a high LVPG. Cibenzoline was more effective in patients with HOCM with the ACE D allele.

The effects of apoA-I/C-III/A-IV, apoE and apoB polymorphisms on carotid artery intima-media thickness

Different apolipoprotein combinations explain most of the functional differences between plasma lipoproteins. This emphasizes the pivotal role of apolipoproteins in the homeostasis and physiological control of lipid metabolism. Genetic polymorphisms of apolipoprotein (apo)A-I/C-III/A-IV, apoE and apoB have been suggested to modulate plasma lipid levels as well as the risk of coronary artery disease and stroke. Carotid artery intima-media thickness has been shown to represent preclinical atherosclerosis and has, therefore, been used as a surrogate in quantifying the early stages of atherosclerosis. The effects of the polymorphisms in apoA-I/C-III/A-IV and apoB on carotid intima-media thickness are poorly known. The corresponding influence of apoE polymorphisms has been studied more extensively, but the results are not yet conclusive. In this review, these results are presented in detail and the potential reasons and mechanisms for the discrepancies are discussed.

The C609T variant of NQO1 is associated with carotid artery plaques in patients with type 2 diabetes

OBJECTIVE

Atherosclerosis in patients with type 2 diabetes has been linked to oxidative stress. NADP[1]:quinone oxidoreductase 1 (NQO1) plays a key role in cellular antioxidant defense. Recent reports suggest that highly expressed and inducible endogenous NQO1 from cardiovascular cells may act as a potential superoxide scavenger. We examined the relationship between the risk of NQO1 C609T polymorphism and carotid artery atherosclerosis in patients with type 2 diabetes.

METHODS

We recruited 601 (Seoul set) and 233 (Koyang set) unrelated patients with type 2 diabetes from independent groups. The C609T variant of NQO1 was genotyped by Taqman RT-PCR. Mean and maximum carotid intima-media thickness (IMT) and carotid artery plaques were measured by high-resolution ultrasonography.

RESULTS

Patients with the T allele exhibited a higher prevalence of atherosclerotic plaques than non-T allele carriers in both sets (Seoul set vs. Koyang set, p=0.021, p=0.023, respectively). After adjusting for age, sex, duration of diabetes, systolic blood pressure, body mass index, current smoking, HDL-cholesterol, LDL-cholesterol and HbA1c, subjects with the T allele had a significantly higher risk of carotid artery plaques (Seoul set vs. Koyang set, OR=1.65, p=0.015; OR=2.00, p=0.037, respectively) than subjects with the CC genotype.

CONCLUSION

These results suggest that the C609T polymorphism of NQO1 is associated with carotid artery plaques in type 2 diabetic patients.

Carotid plaque compared with intima-media thickness as a predictor of coronary and cerebrovascular disease

Atherosclerosis is the underlying cause of most myocardial infarction (MI) and ischemic strokes. B-mode ultrasound of carotid arteries provides measures of intima-media thickness (IMT) and plaques, both widely used as surrogate measures of cardiovascular disease. Although IMT and plaques are highly intercorrelated, IMT's role as a marker of atherosclerosis has been questioned, especially when measurements include the common carotid artery (CCA) only. Plaque and intima-media thickening may reflect different biological aspects of atherogenesis with distinctive relations to clinical vascular disease. Plaque measured in the carotid bulb or internal carotid artery is stronger related to hyperlipidemia and smoking and is a stronger predictor for MI, whereas CCA-IMT is stronger related to hypertension and ischemic stroke. Echolucent plaque morphology (ie, lipid-rich plaques) seems to increase the risk for MI and stroke. New evidence suggests that total plaque area is the most strongly predictive of cardiovascular risk of the ultrasound phenotypes.

Association between apolipoprotein E genotype and carotid intima-media thickness may suggest a specific effect on large artery atherothrombotic stroke

BACKGROUND AND PURPOSE

Apolipoprotein E genotype (APOE) influences cholesterol levels and ischemic heart disease. Although there is no convincing overall association with ischemic stroke, APOE may influence large artery (atherothrombotic) stroke, for which carotid intima-media thickness (CIMT) is an informative intermediate phenotype. We therefore performed a systematic review and meta-analysis of the association between APOE and CIMT.

METHODS

We sought all published studies assessing the association between APOE and CIMT. From each study, we extracted available data on study methods, subjects' characteristics, and mean (and standard deviation) CIMT for each genotype or genotype group. We calculated study-specific and random effects pooled differences in mean CIMT between genotype groups, and assessed heterogeneity between studies and predefined subgroups using I(2) and chi(2) statistics.

RESULTS

Meta-analysis of 22 published studies (30,879 subjects) showed a significant association between APOE and CIMT (pooled mean difference epsilon 4- versus epsilon 2-allele containing genotypes 46 microm, 95% CI 29 to 62, P<0.00001). We found evidence of small study (mainly publication) bias, with a diminished (but still highly statistically significant) association in studies of >1000 subjects (pooled mean difference 17 microm, 95% CI 12 to 23, P<0.00001). The association was larger among high vascular risk and eastern Asian populations, but this may simply reflect the smaller size of these studies.

CONCLUSIONS

Our results show a clear association of APOE with CIMT, even though publication bias means that this is overestimated by the published literature. These findings suggest the possibility of a specific association with large artery ischemic stroke.

A common VLDLR polymorphism interacts with APOE genotype in the prediction of carotid artery disease risk

The genetic factors associated with carotid artery disease (CAAD) are not fully known. Because of its role in lipid metabolism, we hypothesized that common genetic variation in the very low density lipoprotein receptor (VLDLR) gene is associated with severe CAAD (>80% stenosis), body mass index (BMI), and lipid traits in humans. VLDLR was resequenced for variation discovery in 92 subjects, and single nucleotide polymorphisms (tagSNPs) were chosen for genotyping in a larger cohort (n = 1,027). Of the 17 tagSNPs genotyped, one tagSNP (SNP 1226; rs1454626) located in the 5' flanking region of VLDLR was associated with CAAD, BMI, and LDL-associated apolipoprotein B (apoB). We also identified receptor-ligand genetic interactions between VLDLR 1226 and APOE genotype for predicting CAAD case status. These findings may further our understanding of VLDLR function, its ligand APOE, and ultimately the pathogenesis of CAAD in the general population.

Polymorphisms of the renin-angiotensin system are associated with blood pressure, atherosclerosis and cerebral white matter pathology

BACKGROUND

The renin-angiotensin system is involved in the development of hypertension, atherosclerosis and cardiovascular disease. We studied the association between the M235T polymorphism of the angiotensinogen gene (AGT) and the C573T polymorphism of the angiotensin II type 1 receptor (AT1R) and blood pressure, carotid atherosclerosis and cerebrovascular disease.

METHODS

We genotyped over 6000 subjects from the Rotterdam Study and more than 1000 subjects from the Rotterdam Scan Study. We used logistic regression and univariate analyses, adjusting for age and sex with, for AGT, the MM and, for AT1R, the TT genotype as reference.

RESULTS

We found that AGT-235T increased systolic (p for trend = 0.03) and diastolic blood pressure (p for trend = 0.04). The prevalence of carotid plaques was increased 1.25-fold (95% CI 1.02-1.52) in AGT-TT carriers. There was a significant increase in mean volume deep subcortical white matter lesions (WML) for AGT-TT carriers (1.78 ml vs 1.09 ml in the reference group; p = 0.008). A significant interaction was found between AGT and AT1R, further increasing the effect on periventricular and subtotal WML (p for interaction = 0.02). We found a non-significant increased risk of silent brain infarction for AGT-TT carriers and AT1R-CC carriers, but no effect on stroke.

CONCLUSION

We found an association between AGT and blood pressure, atherosclerosis and WML. Also, we found synergistic effects between AGT and AT1R on the development of WML. These findings raise the question of whether the renin-angiotensin system may be a therapeutic target for the prevention of cerebral white matter pathology.

Circle of Willis atherosclerosis: association with Alzheimer's disease, neuritic plaques and neurofibrillary tangles

The role of intracranial atherosclerosis in Alzheimer's disease (AD) has been a subject of debate since the first decade of the last century. The initial "vascular hypothesis" of AD was rejected after a series of mid-twentieth century gross anatomical postmortem studies that showed an inconstant relationship between intracranial atherosclerosis and senile dementia. These early studies did not utilize statistical methods, however, and the investigators did not appear to consider the possibility that intracranial atherosclerosis might have a probabilistic, rather than an absolute, effect on AD risk. Recent studies by three independent groups have found a significant statistical association between postmortem measures of circle of Willis atherosclerosis and AD. The present study was undertaken to further address the validity of this association in a large autopsy series, including cases diagnosed neuropathologically with vascular dementia (VaD) and non-AD dementias. Postmortem gross anatomical grading of circle of Willis atherosclerosis was performed in 397 subjects classified by neuropathological diagnosis, including 92 non-demented elderly controls, 215 with AD, 30 with VaD and 60 with non-AD dementias. Circle of Willis atherosclerosis was more severe in subjects with AD and VaD than in control subjects, while it was equivalent between control subjects and subjects with non-AD dementias. Increasing atherosclerotic grade increased the odds ratios (OR) for the diagnoses of both AD and VaD and also increased the ORs for both increased neuritic plaque density and higher Braak neurofibrillary tangle stage. The significance of these associations was retained after consideration of the effects of age, gender and the apolipoprotein E-epsilon4 allele. The results suggest that the statistical association between intracranial atherosclerosis and AD is not an artifact of diagnostic misclassification or of unequal distribution of the apolipoprotein E-epsilon4 allele.

Technology Insight: ultrasound measurement of carotid plaque--patient management, genetic research, and therapy evaluation

Various methods have been used to quantify atherosclerosis, beginning in the mid-1980s with ultrasound measurement of carotid intima-media thickness (IMT), and going on to coronary calcification assessed by electron-beam CT, measurement of carotid plaque by ultrasound, and measurement of carotid wall thickness by MRI. In recent years, it has become clear that carotid IMT, coronary calcification and carotid plaque reflect biologically and genetically different aspects of the atherosclerotic process, and will respond differentially to therapy. IMT represents mainly hypertensive medial hypertrophy; this measure is more predictive of stroke than of myocardial infarction, and is only weakly associated with traditional coronary risk factors. Carotid plaque area, on the other hand, is more strongly associated with traditional risk factors, and is more predictive of myocardial infarction than of stroke. A quantitative trait, called 'unexplained atherosclerosis', expresses the extent to which an individual has excess carotid plaque not explained by traditional risk factors, or the extent to which an individual is protected from traditional risk factors. Unexplained progression of plaque is an even more powerful tool for genetic research, because age, which accounts for the greatest proportion of baseline plaque, has much less influence on the rate of progression. Compared with IMT, measurement of carotid plaque volume by three-dimensional ultrasound reduces by two orders of magnitude the sample size and duration of treatment needed to evaluate new therapies. Measurement of carotid plaque is, therefore, an important tool for patient management, genetic research and evaluation of new therapies for stroke prevention.

New Insight Into the Association of Apolipoprotein E Genetic Variants With Carotid Plaques and Intima-Media Thickness

BACKGROUND AND PURPOSE

Carotid plaques and elevated carotid artery intima-media thickness (IMT) are major predictors of vascular morbidity and mortality. Our aim was to test their association with 2 polymorphisms of the apolipoprotein E (apoE) gene, epsilon and -219G/T.

METHODS

The study was performed on 5856 subjects aged > or =65 years recruited from the French population for the Three-City Study. Carotid ultrasound examination included an assessment of atherosclerotic plaques in the extracranial carotid arteries and a measurement of IMT in the common carotid arteries (CCA) at a site free of plaques. The genetic association was tested using genotype and haplotype analyses.

RESULTS

In a multivariate analysis including both polymorphisms and vascular risk factors, carotid plaques were more frequent in epsilon4 homozygotes (adjusted odds ratio=2.12, 95% CI=1.27 to 3.53) and less frequent in epsilon2 carriers (adjusted odds ratio=0.79, 95% CI=0.66 to 0.95) compared with epsilon3 homozygotes. Adjusting for and stratifying on lipid levels did not modify these results. CCA-IMT was higher in carriers of the epsilon34 genotype (mean CCA-IMT=0.744 mm versus 0.732 mm for the epsilon33 genotype, P=0.002), but the association disappeared after excluding subjects with carotid plaques. No association was found between the -219 polymorphism and either carotid plaques or CCA-IMT, and there was no interaction or cis-effect between -219 and epsilon.

CONCLUSIONS

This study, conducted on a large population cohort of French elderly, demonstrated that carotid plaques were significantly associated with the apoE epsilon polymorphism independently of the -219 polymorphism and vascular risk factors, in particular lipid levels.

Interaction between GNB3 C825T and ACE I/D polymorphisms in essential hypertension in Koreans

Essential hypertension (EH) is considered a typical polygenic disease, so the evaluation of gene-gene interactions rather than the determination of single gene effects is crucial to understanding any genetic influences. The G-protein beta3-subunit (GNB3) 825T allele, associated with enhanced G-protein signalling, is a strong candidate for interactions with polymorphisms, such as insertion/deletion (I/D) polymorphism of angiotensin I-converting enzyme (ACE) gene. We investigated whether there is an association between GNB3 C825T and ACE I/D polymorphisms for the development of EH. We carried out a case-control study of 688 hypertensive and 924 normotensive subjects recruited from South Korea. The GNB3 C825T and ACE I/D genotypes were determined by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism methods, respectively. The distributions of alleles and genotypes for the GNB3 C825T and ACE I/D polymorphisms were not found to be significantly associated with hypertensive status in either males or females. Logistic regression analysis indicated that the GNB3 825T allele carriers were positively associated with EH in males (odds ratio (OR) for TT/CT, 1.459; 95% confidence interval (CI), 1.048-2.033, P=0.0255). In analysis of gene-gene interaction, we found that there was a significant interaction between the GNB3 825T and ACE D alleles (P<0.05). OR for EH was significantly higher in 825T allele carriers with ACE D allele (OR, 1.490; 95% CI, 1.117-1.987, P=0.0067). A significant interaction between the GNB3 825T and the ACE D alleles may contribute to the predisposing effect for the development of EH in Koreans.

Renin-angiotensin system and haemostasis gene polymorphisms and outcome after coronary artery bypass graft surgery

BACKGROUND

Coronary artery bypass graft surgery is associated with a considerable 2-year mortality rate. Gene polymorphisms of the renin-angiotensin system may be associated with the risk of hypertension and cardiovascular disease. The angiotensin I-converting enzyme DD genotype has recently been identified as independent predictor of the outcome after coronary artery bypass graft surgery. Genetic factors of the clotting system may be related to the risk of myocardial infarction and restenosis after coronary interventions. The aims of the present study were to investigate whether gene polymorphisms of the renin-angiotensin system (angiotensinogen 235 M/T, angiotensin II type 1 receptor 1166 A/C) or the clotting system (glycoprotein IIIa PlA1/PlA2 and factor V Leiden 1691 G/A) are associated with the outcome after coronary artery bypass grafting.

METHODS

A study population of 247 patients was followed-up 2 years after coronary artery bypass graft surgery. The primary end-point was total mortality. The secondary end-point was mortality from cardiac cause or the need for myocardial revascularization (percutaneous coronary interventions or recurrent surgery) during follow-up. Geno typing was performed by polymerase chain reaction- and restriction fragment length polymorphism-based techniques.

RESULTS

An older age and the non-use of the internal mammary artery graft were identified as independent predictors of the primary end-point after coronary artery bypass grafting. A decreased left ventricular ejection fraction was an independent predictor for the secondary end-point. No association was found between any of the genetic factors and the outcomes after coronary artery bypass graft surgery in the main factor regression models. However, the angiotensin II type 1 receptor 1166 A/C gene polymorphism modulated the effects of age on the primary end-point, and the angiotensinogen 235 M/T gene polymorphism modulated the effects of age on the secondary end-point.

CONCLUSION

We conclude that there are interactions between the angiotensin II type 1 receptor 1166 A/C as well as the angiotensinogen 235 M/T gene polymorphism and age with respect to the outcome after coronary artery bypass graft surgery. The glycoprotein IIIa PlA1/PlA2 and the factor V Leiden 1691 G/A gene polymorphisms were not associated with mid-term mortality or cardiac morbidity after coronary artery bypass grafting.

Angiotensin-converting enzyme insertion/deletion polymorphism and retinal artery occlusion

PURPOSE

An insertion/deletion (I/D) polymorphism of the gene for angiotensin-converting enzyme (ACE) is associated with higher ACE plasma levels and activity. This enzyme is known to play an important role in blood pressure regulation and the ACE I/D gene polymorphism has been suggested as a risk factor for atherosclerotic vascular diseases. The purpose of the present study was to investigate a hypothesized association between the ACE I/D polymorphism and retinal artery occlusion (RAO).

METHODS

A total of 159 patients with RAO and 304 control subjects were enrolled in the present retrospective case-control study. ACE I/D genotypes were determined by polymerase chain reaction.

RESULTS

Allelic frequencies and genotype distribution of the ACE I/D polymorphism did not significantly differ between patients and control subjects (ACE DD 25.8% versus 28.0%; p = 0.36). A logistic regression analysis predicted the presence of RAO by arterial hypertension and current smoking status, but not by ACE I/D genotypes.

CONCLUSION

Our data suggest that the ACE I/D polymorphism is not a major risk factor for RAO.

The association between angiotensin-converting enzyme gene polymorphism and coronary calcification. The Rotterdam Coronary Calcification Study

BACKGROUND

An insertion/deletion (I/D) polymorphism in the gene encoding angiotensin-converting enzyme (ACE) has been associated with serum ACE levels. The association between the ACE I/D polymorphism and coronary heart disease is unclear. Electron-beam-computed tomography (EBT) is a technique to non-invasively quantify the amount of coronary calcification. We investigated the association between the ACE I/D polymorphism and coronary calcification.

METHODS AND RESULTS

The Rotterdam Coronary Calcification Study is a population-based study in subjects aged 55 years and over. EBT scanning was performed in 2013 participants. Coronary calcification was quantified according to the Agatston score. The ACE I/D polymorphism was available for 1976 subjects. Geometric mean calcium scores in men with the II, ID and DD genotype were 167, 207 and 219, respectively. However, the difference in calcium score (p=0.19 for ID versus II; p=0.15 for DD versus II) and the trend (ptrend=0.17) were not significant. Calcium scores in women with the II, ID and DD genotype were 44, 42 and 36, respectively. There were no significant differences in calcium score (p=0.78 for ID versus II; p=0.29 for DD versus II), neither was the trend (ptrend=0.27). After we stratified on cardiovascular risk factors, no associations were present.

CONCLUSION

The present study failed to show an association between the ACE I/D polymorphism and coronary calcification in the general population. Also, no significant associations were present between the ACE I/D polymorphism and coronary calcification in strata of cardiovascular risk factors.

POLYMORPHISMS OF APOLIPOPROTEIN E AND ANGIOTENSIN-CONVERTING ENZYME GENES AND CAROTID ATHEROSCLEROSIS IN HEAVY DRINKERS

AIMS

To investigate the influence of apolipoprotein E (APOE) and angiotensin-converting enzyme (ACE) gene polymorphisms on carotid artery atherosclerosis in alcoholism.

METHODS

Polymorphism of both genes was identified by DNA analysis in 130 male alcohol-dependent patients. Intima-media thickness (IMT) was measured ultrasonographically.

RESULTS

Multivariate regression analysis showed that of all the known risk factors the greatest impact on carotid atherosclerosis in alcoholics was exerted by age, hypertension, LDL cholesterol and fasting plasma glucose levels. Subjects carrying the APO E epsilon4 allele were more liable to develop atherosclerotic changes in carotid arteries compared with subjects with the epsilon3/3 genotype, which showed statistical significance in patients under 50 years of age. No association was shown between ACE I/D polymorphism and carotid atherosclerosis.

CONCLUSIONS

APO E polymorphism can increase the risk of carotid atherosclerosis development in an alcoholic subject. The association of the APO E epsilon4 allele with carotid atherosclerosis was significant in younger patients. Since the elevated carotid IMT is considered to be a good marker of increased risk of generalized atherosclerosis the consequences could involve both cardiac and cerebrovascular events.

F2-Isoprostane level is associated with the angiotensin II type 1 receptor -153A/G gene polymorphism

Recent studies have shown that F2-isoprostane levels-a marker for lipid peroxidation-are increased in human renovascular hypertension but not in essential hypertension. Angiotensin II specifically stimulates F2-isoprostane production through activation of the AT1 receptor. The objective was to determine whether there is a relationship between the level of oxidative stress evaluated by measuring urinary F2-isoprostanes levels and polymorphisms of genes involved in the renine angiotensin aldosterone system (RAAS) regulation. The population studied included 100 subjects, 65 of whom were healthy normotensives; the other 35 were suffering from untreated, essential hypertension. The polymorphisms studied concern the genes encoding angiotensin I-converting enzyme (ACE/in16del/ins), angiotensin II receptor type I (AGTR1/A+39C[A+1166C] and AGTR1/A-153G), angiotensinogen (AGT/M235T), and aldosterone synthase (CYP11B2/T344C). Oxidative stress was evaluated by measuring urinary F2-isoprostanes levels. The characteristics of the population were as follows: men/women = 46/56; age = 50 +/- 10 years; BMI = 24 +/- 3 kg/m2; SBP = 131.7 +/- 17.2 mm Hg; DBP = 84.6 +/- 10.4 mm Hg. In univariate analysis, urinary F2-isoprostane levels were significantly lower in the presence of the G allele of AGTR1/A-153G (56 +/- 17 vs 76 +/- 39 pmol/mmol creatinine; P < 0.001, and P < 0.01 after Bonferroni correction for 10 tests). In multivariate analysis, taking into account BP, age, gender, BMI, plasma glucose, and total cholesterol, the G allele of AGTR1/A-153G is linked independently to urinary F2-isoprostanes level (P < 0.01). Our data suggest that F2-isoprostane level depends at least in part on the A-153G polymorphism of the angiotensin II AT1 receptor gene. The clinical and prognostic relevance of this polymorphism requires further investigation.

Genetics of Ultrasonographic Carotid Atherosclerosis

The search for genes related to the cause of common complex disorders such as cardiovascular disease has been frustrating, partly because of the many factors known to contribute to cardiovascular disease and the potential "distance" of cardiovascular disease as a phenotype from genes and gene products. Linkage and association studies for phenotypes more proximal in the pathway from DNA sequence variation to overt clinical disease, such as ultrasound-defined carotid atherosclerosis, may potentially be more enlightening. Only one genetic variant previously reported to be associated with atherosclerosis or clinically evident cardiovascular disease, matrix metalloproteinase (MMP) 3, has shown consistently positive associations with carotid disease, although it has not been studied widely. Another, PON1 L55M, is weakly associated in subgroups only, and 2, ApoE and MTHFR, are equivocal. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis. This may reflect the known inconsistency in associations of genetic variants with clinical cardiovascular disease itself. Alternatively, genetic determinants of ultrasound-defined carotid atherosclerosis may differ from those of clinically manifest cardiovascular disease and may require pursuit through large-scale genomic studies of carotid atherosclerosis as a distinct phenotype. Only 1 genetic variant, MMP 3, has shown consistently positive associations with ultrasonographic carotid disease, although it has not been studied widely. Another, PON1 L55 mol/L, is weakly associated in subgroups only. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis.

The metabolic syndrome: A crossroad for genotype-phenotype associations in atherosclerosis

The metabolic syndrome comprises a set of metabolic and physiologic risk factors associated with elevated cardiovascular disease risk. The expression of each one of its major factors (hypertriglyceridemia, low high-density lipoprotein cholesterol levels, hypertension, abdominal obesity, and insulin resistance) has been found to be the result of complex interactions between genetic and environmental factors. Moreover, obesity may play a major role in triggering the metabolic syndrome by interacting with genetic variants at candidate genes for dyslipidemia, hypertension, and insulin resistance. In support of this hypothesis, several studies at multiple candidate genes have already demonstrated the significance of these interactions; however, the data and their reliability are still very limited, and in many cases replication studies are still lacking in the literature. Therefore, more studies with better epidemiologic design and standardized adiposity measures are needed to estimate the contribution of body weight and fat distribution to the genetic predisposition to the metabolic syndrome, which is the most common cardiovascular disease risk factor in industrialized societies.

A study of gene--environment interaction on the gene for angiotensin converting enzyme: a combined functional and population based approach

INTRODUCTION

Studies on the role of the insertion/deletion (I/D) polymorphism of the gene coding for angiotensin converting enzyme (ACE) in atherosclerosis have been inconsistent. In a meta-analysis, we recently showed that this relationship is stronger in high risk populations. In this paper, we used a combined functional and population based approach to investigate the gene-environment interaction of the ACE I/D polymorphism in relation to carotid artery wall thickness.

METHODS

The study was part of the Rotterdam Study, a prospective population based cohort study. In 5321 subjects, IMT was measured in the carotid arteries by ultrasonography and ACE genotype was determined by size analysis of polymerase chain reaction products.

RESULTS

In multiple regression analysis, I/D polymorphism and smoking were the main determinants for plasma ACE activity (r(2) = 0.28). There was a positive association between the D allele of the I/D polymorphism and carotid artery thickness among current smokers (p = 0.03). Subjects carrying only one of the risk factors (smoking or the D allele) did not show significant differences in IMT compared with the non-/former smokers group carrying two II alleles, while carriers of both risk factors had significant higher IMT. The association was not present in non-/former smokers.

DISCUSSION

The results provide further evidence that genetic and environmental factors interact in the formation of the arterial lesions. This study shows that large population based studies can be extremely helpful in unravelling the genetic origin of complex diseases such as atherosclerosis.

Angiotensin-converting enzyme gene polymorphism and carotid artery wall thickness: a meta-analysis

BACKGROUND AND PURPOSE

Many studies have investigated the association between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and carotid artery intima-media thickness (IMT); however, most studies were small and conducted in selective samples. The aim of this study was to evaluate this association by performing a meta-analysis on published articles.

METHODS

We searched Medline for articles studying the association between the ACE I/D polymorphism and carotid IMT. Twenty-six studies were found; 23 articles containing 9833 subjects were qualified to enter the meta-analysis. We classified those articles on the basis of their samples into high-risk and low-risk populations and white and Asian ethnic groups. IMT was used as a continuous variable, and data were analyzed with the Cochrane Review Manager.

RESULTS

A significant positive association was present between the D allele and common carotid IMT (weighted mean difference between DD and II genotypes, 0.23 mm x 10(-1); P<0.01). The association was stronger among high-risk populations. The point estimates of DD versus II were higher than those of ID versus II.

CONCLUSIONS

Our meta-analysis showed evidence of a positive association between the D allele of the ACE gene and common carotid IMT. The overall results were concordant in both ethnic groups.

Polymorphism of the Monocyte Chemoattractant Protein (MCP-1) Gene Is Associated with the Plasma Level of MCP-1 But Not with Carotid Intima-Media Thickness

Monocyte chemoattractant protein-1 (MCP-1) plays an important role in atherosclerosis. Recently, single nucleotide polymorphisms (SNPs) in the MCP-1 regulatory region have been identified, and an in vitro study demonstrated that the SNP at position -2518 of the MCP-1 gene affected transcription of the gene. The purpose of this study was to clarify the association of the plasma level of MCP-1 and the SNP of the MCP-1 gene with carotid atherosclerosis in community-based subjects. The study subjects consisted of 325 community residents, aged 50 years or older (mean age, 70.5 +/- 9.4 years) and free from any cardiovascular complications. Carotid intima-media thickness (IMT) was measured in the right common carotid artery using ultrasonography. The plasma level of MCP-1 was measured by enzyme-linked immunosorbent assay (ELISA). The SNP of the MCP-1 gene was determined by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique. The plasma level of MCP-1 was significantly associated with IMT (r = 0.12, p < 0.05) and carotid arterial dimension (r = 0.13, p < 0.05). There was a significant difference in plasma MCP-1 level between the genotypes (AA, 166 +/- 36 ng/ml; GG + AG, 184 +/- 56 ng/ml; p = 0.036). Analysis restricted to the subjects not receiving antihypertensive drugs or other medication further increased the statistical significance. However, carotid IMT and carotid arterial diameter were not significantly different among the MCP-1 genotypes. Stepwise regression analysis for plasma MCP-1 revealed that the MCP-1 genotype was an independent determinant of plasma MCP-1 level. These findings indicate that plasma MCP-1 is associated with carotid atherosclerosis. Although -2518 SNP is associated with the plasma level of MCP-1, it was not directly associated with carotid atherosclerosis.

An interaction between systolic blood pressure and angiotensin-converting enzyme gene polymorphism on carotid atherosclerosis

The insertion/deletion (I/D) polymorphism of the human angiotensin-converting enzyme (ACE) gene is a major determinant of circulating ACE activity, with the D allele being associated with higher ACE levels than the I allele. Thus, chronic exposure to high levels of circulating and tissue ACE may well predispose to vascular wall thickening and atherosclerosis. However, the effect of the ACE gene on carotid atherosclerosis remains controversial. We investigated the association between ACE gene I/D polymorphism and risk factor-dependent augmentation of carotid arterial remodeling in subjects with several risk factors for atherosclerosis. We evaluated sclerotic lesions of the common carotid artery with intima-media thickness (IMT) by ultrasonography in 184 patients (mean age +/- SD, 67 +/- 14 years old) and studied whether any risk factor-gene interactions were associated with carotid atherosclerosis. Out of the 184 subjects, 71 had the ACE II genotype, 87 the ID genotype and 26 the DD genotype. There was no significant difference in IMT among the three ACE genotypes. In total subjects, multiple regression analysis showed that age, total-cholesterol (T-C), and HDL-cholesterol (HDL-C) were significantly associated with IMT. However, the association between risk factors and IMT was genotype-specific. Systolic blood pressure (SBP) and HDL-C were significantly associated with IMT in ACE D carriers (DD+ID), but not in subjects with the ACE II genotype. Similarly, T-C was significantly associated with IMT only in subjects with the ACE II genotype. A general linear model of the interaction between the ACE genotype and the conventional risk factors showed that the SBP-ACE genotype interaction were significantly associated with IMT (F = 7.915; p = 0.005). This finding further supports the idea that analysis of risk factor-gene interaction could be a useful tool for deriving specific predictive information about the development of atherosclerosis.

Searching for the mountains of the moon: genome scans for atherosclerosis

Several research groups have begun mounting large, ambitious family studies to map genes for atherosclerosis, heart disease, and their major risk factors using whole genome linkage and/or disequilibrium scans. Some of the problems, pitfalls, and challenges of this exciting effort are examined and illustrated with lessons from an earlier mapping problem.

Polymorphisms of genes encoding components of the sympathetic nervous system but not the renin-angiotensin system as risk factors for orthostatic hypotension

OBJECTIVE

The genetic background of orthostatic hypotension, an important risk factor for future cardiovascular morbidity and mortality, was investigated.

DESIGN AND METHODS

The study subjects comprised 415 community-dwelling individuals, who were free from any cardiovascular complications, aged 50 years or older (mean age 70.5 +/- 9 years). Basal systolic blood pressure (SBP) was measured twice in supine posture after resting for more than 10 min. The orthostatic change in SBP was determined at 1 min and 3 min after standing up. The maximum change in SBP after standing was determined. Orthostatic hypotension was defined as a decline in SBP greater than 20 mmHg. The polymorphisms of genes encoding components of the renin-angiotensin system and sympathetic nervous system, which play pivotal roles in postural change in blood pressure regulation, were determined.

RESULTS

There were no significant associations between the maximum change in SBP, the prevalence of orthostatic hypotension and gene polymorphisms of angiotensin-converting enzyme I/D, angiotensinogen M235T and angiotensin II type 1 receptor A1166C. On the contrary, polymorphism of the Gs protein alpha-subunit (GNAS1) T131C was significantly associated with the maximum change in SBP after standing [1.9 +/- 16 versus -3.6 +/- 16 mmHg (TT + TC versus CC), P = 0.008]. The prevalence of orthostatic hypotension was significantly different among GNAS1 genotypes (chi squared = 10.12, P = 0.011) and G-protein beta 3 subunit (GNB3) genotypes (chi squared = 6.12, P = 0.020). Multiple logistic regression analysis showed that both GNAS1 CC genotype [odds ratio (OR) = 2.79, 95% confidence interval (CI) 1.35-5.79, P = 0.006] and GNB3 C allele (OR = 1.78, 95% CI 1.06-3.00, P = 0.030) were independent risks for orthostatic hypotension.

CONCLUSIONS

These findings indicate that genes encoding sympathetic nervous components could be involved in the predisposition for orthostatic hypotension.

Genotype-specific association between circulating soluble cellular adhesion molecules and carotid intima-media thickness in community residents: J-SHIPP study. Shimanami Health Promoting Program

Plasma levels of soluble forms of cellular adhesion molecules (CAMs) and their relationships with carotid intima-media thickness (IMT) were investigated in community residents. Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured by ELISA in 200 community residents in Japan. Carotid IMT showed a weak but significant positive correlation with the plasma levels of both sICAM-1 (r=0.175, p=0.013) and sVCAM-1 (r=0.19, p=0.0075). Gene polymorphisms of angiotensin converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) M235T, angiotensin II type 1 receptor (AT1R) A1166C and apolipoprotein E (apoE) were determined for each subject. The plasma level of sVCAM-1 tended to be lower in subjects with the ACE DD genotype than in those with the ACE ID and II genotypes (373+/-94, 421+/-133, 443+/-135 ng/ml, respectively, p=0.056). However, there were no genotype-specific differences in the plasma levels of soluble forms of CAMs for the other genes examined. In a separate analysis, the plasma level of sICAM-1 was significantly associated with carotid IMT in ACE D carriers (ID + DD) (r=0.28, p=0.002), AGT M carriers (MT + MM) (r=0.32, p=0.0045), and subjects with apoE4 (r=0.35, p=0.036). In contrast, the plasma level of sVCAM-1 showed significant positive correlations with carotid IMT in subjects with the ACE II genotype (r=0.33, p=0.0027) or AGT TT genotype (r= 0.22, p=0.015), and subjects with apoE E2/E3 or E3/E3 (r=0.16, p=0.043). Stepwise regression analysis showed that plasma sVCAM-1 was independently associated with carotid IMT in subjects with the ACE II genotype or apoE4 genotype. Similarly, the plasma level of sICAM-1 was independently associated with carotid IMT in AGT M carriers. These findings suggest that genetic background could be involved in the association between plasma CAMs and atherosclerosis.