The endothelial nitric oxide synthase (Glu298Asp and -786T>C) gene polymorphisms are associated with coronary in-stent restenosis

Association of Endothelial Nitric Oxide Synthase and Angiotensin-Converting Enzyme Genes Polymorphism With In-Sent Restenosis of Bare Metal Stents vs Drug-Eluting Stents in Egyptians

Despite its unequivocal superiority compared with balloon angioplasty, coronary stenting did not abolish restenosis. We aimed to evaluate the associations between a common single nucleotide polymorphism occurring in endothelial nitric oxide synthase (eNOS) and angiotensin-converting enzyme (ACE) genes and the risk of in-stent restenosis (ISR) of bare metal stents vs drug-eluting stents (BMS vs DES) implanted in Egyptian patients. Two hundred patients who had coronary stenting were divided into group I (n = 98) who received a BMS and group II (n = 102) who received a DES. eNOS and ACE genes polymorphism were analyzed by polymerase chain reaction (PCR). We found that the GA and AA genotypes of the eNOS gene were associated with the ISR with both BMS and DES. However, the ACE gene was not associated with ISR. We concluded that eNOS gene polymorphism is associated with ISR. Hypertension, stent length, and AA genotype of the eNOS gene were found to be independent predictors of the occurrence of ISR after both BMS and DES use.

Endothelial nitric oxide synthase polymorphism and venous thromboembolism: A meta-analysis of 9 studies involving 3993 subjects

BACKGROUND

Endothelial nitric oxide synthase (eNOS) polymorphism may influence the risk of venous thromboembolism (VTE). However, data from published studies with low statistical power are inconclusive. The present meta-analysis aimed to assess the relationship between eNOS polymorphism and the risk of VTE.

METHOD

Case-control studies evaluating the association between the eNOS polymorphism and VTE were searched in PubMed, Embase, Web of Science, Google Scholar, Wanfang, Chinese National Knowledge Infrastructure (CNKI), the Chongqing VIP Chinese Science and Technology Periodical Database (VIP), and Chinese Biomedical Literature Database (CBM).

RESULTS

A total of 1588 cases and 2405 controls from 9 studies were included in the analysis. The results showed that eNOS G894T polymorphism was related to VTE susceptibility and the difference was statistically significant [T vs G: OR = 1.41, 95% CI (1.13, 1.75), P = 0.002; TT + GG vs TG: OR = 0.71, 95% CI (0.60, 0.84), P = 0.000; TT + TG vs GG: OR = 1.45, 95% CI (1.23, 1.70), P = 0.000]. Additionally, eNOS Intron 4 VNTR polymorphism was related to VTE susceptibility and the difference was statistically significant [4b4b vs 4a4a + 4a4b: OR = 2.77, 95% CI (1.01, 7.61), P = 0.048].

CONCLUSION

ENOS G894T and eNOS Intron 4 VNTR polymorphisms were associated with VTE susceptibility, especially in Asian populations. However, multicenter studies with larger samples should be conducted to further clarify this association and verify our findings.

The Utility of New Biomarker-based Predictive Model for Clinical Outcomes Among ST-elevation Myocardial Infarction Patients

Aim:

To determine the discriminative potency of score to prognosticate poor clinical outcomes in ST-Segment Elevation Myocardial Infarction (STEMI) patients.

Methods:

From the entire population of STEMI (n=268), we enrolled 177 individuals with acute STEMI who underwent complete revascularization with primary Percutaneous Coronary Intervention (PCI). Clinical assessment, echocardiography, Doppler, and biomarkers’ measure were performed at baseline.

Results:

Combined endpoint (Major Cardiovascular Events - MACEs [composite of cardiovascular death, recurrent myocardial infarction, newly diagnosed Heart Failure] and hospitalization) was determined in 75 patients with acute STEMI population (40.6%). Newly onset heart failure (HF) was reported in 46 patients (26.0%), Cardiovascular (CV) death occurred in 12 patients (6.8%), MACEs were determined in 58 patients (32.8%), and recurrent hospitalization due to CV reasons was found in 17 (9.6%). The conventional risk predictive models were engineered by a combination of TIMI risk score +acute HF Killip class ≥ II + the levels of NT-pro brain natriuretic peptide > 300 pg / mL and troponin >0.05 ng/mL. We developed a new predictive model based on the presentation of T786С genotype of endothelial NO syntase gene (rs 2070744), А1166С in angiotensin-ІІ receptor-1 gene (rs5186) and serum levels of soluble suppressor tumorigenicity ≥35 pg/mL, vascular endothelial growth factor ≤172 pg/mL and macrophage inhibitory factor ≥2792.7 pg/mL. STEMI patients who had >5 score points demonstrated significantly worse prognosis than those who had ≤5 score points.

Conclusion:

Here we have reported that a new original predictive model is better than a conventional model in discriminative ability to predict combined clinical outcome in STEMI patients.

Pharmacogenetic Implications of eNOS Polymorphisms (Glu298Asp, T786C, 4b/4a) in Cardiovascular Drug Therapy

Endothelial nitric oxide synthase (NOS3 or eNOS) is the enzyme responsible for the highest production of nitric oxide, with the greatest impact on the cardiovascular system, encoded by the eNOS gene, which presents various polymorphisms. ENOS gene polymorphisms play an important role in the response to drugs affecting nitric oxide (NO) signaling. This review discusses the pharmacogenetic impact of eNOS polymorphisms on the response to drugs affecting NO activity: angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, calcium blockers, beta-blockers, diuretics, phosphodiesterase inhibitors, and statins. The identification of biomarkers that accurately predict particular phenotypes is a challenge that needs additional large studies, in different populations. Efforts should be oriented towards a more accurate evaluation of the effects of eNOS genetic variants on biochemical parameters reflecting eNOS gene expression and enzymatic activity, in different diseases, as well as following drug treatment. This approach will allow for a better understanding of the role of eNOS genetic variants in cardiovascular disease progression and for cardiovascular drug therapy optimization.

The Endothelial Nitric Oxide Synthase (NOS3-786T>C) Genetic Polymorphism in Chronic Heart Failure: Effects of Mutant -786C allele on Long-term Mortality

BACKGROUND

Nitric oxide plays an important role in the regulation of basal vascular tone and cardiac myocyte function. We investigated the NOS3-786T>C polymorphism in chronic heart failure (CHF) and its effects on long-term mortality.

METHODS

Ninety-one patients with CHF who were referred to the Department of Cardiology of Siyami Ersek Cardiovascular and Thoracic Surgery Center for cardiopulmonary exercise testing between April 2001 and January 2004 and 30 controls were enrolled in this study. Patient were followed prospectively for a period of 1 to 12 years.

RESULTS

Patients and controls were divided into three groups: TT, TC and CC, according to their NOS3-786T>C polymorphism. We noted that there was no significant difference in the genotype distribution between patients and controls. There was also no significant difference in endothelial nitric oxide synthase (eNOS) gene polymorphism between ischemic HF and nonischemic HF. During the follow-up period, 61 (67%) deaths occurred. The nonsurvivor group had lower left ventricular ejection fraction (LVEF) (p = 0.01), reduced peak oxygen consumption (p = 0.04) and were of older age (p = 0.001). Age, LVEF, peak oxygen consumption and genotype were found to be predictors of mortality (p < 0.05). Additionally, mortality was significantly increased in -786CC genotype patients compared to TT genotype patients (hazard ratio = 2.2; p = 0.03). By multivariate analysis, age and eNOS genotype were determined to be significant independent predictors of death. Additionally, Kaplan-Meier analysis confirmed that homozygote -786C genotype was associated with an increased risk of death (χ2 = 4.6, p = 0.03).

CONCLUSIONS

Our findings showed that the NOS3-786T>C polymorphism was associated with an increased risk of mortality in patients with CHF.

Association of the Endothelial Nitric Oxide Synthase Gene T786C Polymorphism with In-Stent Restenosis in Chinese Han Patients with Coronary Artery Disease Treated with Drug-Eluting Stent

Background and aim

Many studies have reported that genetic variants correlate with higher risk for coronary artery disease (CAD) or in-stent restenosis (ISR) after bare metal stent (BMS) implantation. However, there is limited data assessing the impact of these variants on ISR in patients treated with drug-eluting stent (DES). The purpose of this study was to investigate the effects of genetic risk factors on ISR in Chinese Han patients treated with DES.

Methods

A total of 425 patients with a diagnosis of CAD who underwent successful revascularization in native coronary arteries with DES were included in this retrospective study. Genotyping was performed on six single nucleotide polymorphisms (SNPs) in the endothelial nitric oxide synthase gene (eNOS), the angiotensin converting enzyme gene (ACE), the angiotensin II type 1 receptor gene (AT1R), the transforming growth factor beta gene (TGF-β), and the vascular endothelial growth factor gene (VEGF). Quantitative coronary angiography (QCA) was performed during the follow-up period to detect ISR. Logistic regression models were used to test for association.

Results

Fifty-four patients (12.7%) developed ISR during the follow-up period. Of the six analyzed SNPs, the frequency of the C allele of T786C polymorphism in eNOS was significantly higher in the ISR group (22.2%) compared to the non-ISR group (12.7%) (p<0.01). In the ISR group, the frequency of the TT, TC, and CC genotypes was 61.1%, 33.3%, and 5.6%, respectively, and in the non-ISR group, the frequencies were 76.8%, 21.0%, and 2.2%, respectively. The multivariable analysis adjusted for potential confounders and revealed that the T786C polymorphism increased the risk of ISR in both additive and dominant models with odds ratios of 1.870 (95% confidence interval [CI]: 1.079–3.240, p = 0.03) and 2.045 (95% CI: 1.056–3.958, p = 0.03), respectively.

Conclusion

The eNOS T786C polymorphism was associated with ISR in Chinese Han patients treated with DES. Genotyping may be helpful to identify patients with higher risks of ISR after DES implantation.

Relationship of the rs1799752 polymorphism of the angiotensin-converting enzyme gene and the rs699 polymorphism of the angiotensinogen gene to the process of in-stent restenosis in a population of Polish patients with stable coronary artery disease

PURPOSE

The renin-angiotensin-aldosterone system may influence in-stent restenosis (ISR) via angiotensin II, which stimulates the production of growth factors for smooth muscle cells. The aim of this work is to assess the influence of the rs1799752 polymorphism of the angiotensin-converting enzyme (ACE) gene and the rs699 polymorphism of the angiotensinogen (AGT) gene on the ISR in Polish patients with stable coronary artery disease (SCAD) who underwent stent implantation.

MATERIAL/METHODS

Two hundred and sixty-five patients with SCAD were included in the study. All patients underwent stent implantation upon admission to the hospital and had subsequent coronary angiography performed. The patients were divided into two groups - those with significant ISR (n=53) and those without ISR (n=212). The ACE polymorphism was assessed using the classical PCR method and the AGT polymorphism was determined using the TaqMan method for SNP genotyping.

RESULTS

No difference in the frequency of angiographically significant ISR occurrence associated with the different ACE and AGT gene polymorphisms was observed. In a multivariable analysis, after correction for clinical variables, the relationship between the ACE and AGT genotypes within the scope of the analyzed polymorphisms and the process of restenosis was not found using a dominant, recessive and log-additive model. Late lumen loss was also independent of the genotypes of the polymorphisms before and after correction with angiographic variables.

CONCLUSIONS

The rs1799752 polymorphism and the rs699 polymorphism had no relationship with the occurrence of angiographically significant ISR and late lumen loss in a group of Polish patients who underwent metal stent implantation.

Genetic risk factors for restenosis after percutaneous coronary intervention in Kazakh population

BACKGROUND

After coronary stenting, the risk of developing restenosis is from 20 to 35 %. The aim of the present study is to investigate the association of genetic variation in candidate genes in patients diagnosed with restenosis in the Kazakh population.

METHODS

Four hundred fifty-nine patients were recruited to the study; 91 patients were also diagnosed with diabetes and were excluded from the sampling. DNA was extracted with the salting-out method. The patients were genotyped for 53 single-nucleotide polymorphisms. Genotyping was performed on the QuantStudio 12K Flex (Life Technologies). Differences in distribution of BMI score among different genotype groups were compared by analysis of variance (ANOVA). Also, statistical analysis was performed using R and PLINK v.1.07. Haplotype frequencies and LD measures were estimated by using the software Haploview 4.2.

RESULTS

A logistic regression analysis found a significant difference in restenosis rates for different genotypes. FGB (rs1800790) is significantly associated with restenosis after stenting (OR = 2.924, P = 2.3E-06, additive model) in the Kazakh population. CD14 (rs2569190) showed a significant association in the additive (OR = 0.08033, P = 2.11E-09) and dominant models (OR = 0.05359, P = 4.15E-11). NOS3 (rs1799983) was also highly associated with development of restenosis after stenting in additive (OR = 20.05, P = 2.74 E-12) and recessive models (OR = 22.24, P = 6.811E-10).

CONCLUSIONS

Our results indicate that FGB (rs1800790), CD14 (rs2569190), and NOS3 (rs1799983) SNPs could be genetic markers for development of restenosis in Kazakh population. Adjustment for potential confounder factor BMI gave almost the same results.

Association of ACE insertion or deletion polymorphisms with the risk of coronary restenosis after percutaneous coronary intervention: A meta-analysis

OBJECTIVE

Previous case-control studies on the relationship between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphisms and coronary restenosis did not reach the same conclusion. In the present study, we aimed to further evaluate the relationship between the ACE gene I/D polymorphisms and coronary restenosis, after percutaneous coronary intervention (PCI).

METHODS

By searching PubMed, EMBase, the Chinese Biomedical Literature Database and Wanfang database, we selected 16 case-control studies related to ACE gene I/D polymorphism and coronary restenosis after PCI. To test for heterogeneity in each study, we utilized the Q-test and I(2) test. To merge the odds ratio (OR) and 95% CI, we utilized the random effects model during the analyses.

RESULTS

The present study included 4693 subjects: 1241 patients with coronary restenosis and 3452 without coronary restenosis. By meta-analysis, we found there was significant association of ACE gene I/D polymorphism with coronary restenosis (D allele versus I allele: OR = 1.92; 95% CI (1.40-2.43); p < 0.001). A subgroup analysis, by stratification according to ethnicity, also showed that this association was found not only in the Caucasian population ((D allele versus I allele: OR = 1.94; 95% CI (1.38-2.80); p < 0.001)), but also in the Asian population ((D allele versus I allele: OR = 1.83; 95% CI (1.05-3.20); p = 0.03)). After stratification according to age, we found that the D allele carriers have a higher risk for development of coronary restenosis in subjects < 60 years old (OR = 2.13; 95% CI: 1.40-3.24; p = 0.0004); while in the subjects ⩾ 60 years old, the association was present with bordering significance (OR = 1.48; 95%CI: 0.98-2.25; p = 0.06).

CONCLUSIONS

The present study suggested that the ACE gene I/D polymorphism was associated with coronary restenosis, regardless of age and ethnicity.

Influence of the angiotensin converting enzyme insertion or deletion genetic variant and coronary restenosis risk: evidence based on 11,193 subjects

The insertion/deletion (I/D) polymorphism of the gene encoding angiotensin converting enzyme is a controversial risk factor for restenosis after percutaneous transluminal coronary angioplasties (PTCA) in patients. Genetic association studies can be problematic to reproduce due to insufficient power, phenotypic heterogeneity, population stratification, small effect of the variant and even publication biases. To derive a more precise estimation of the relationship as well as to quantify the between-study heterogeneity and potential bias, a meta-analysis including 11,193 patients from 33 published cohort studies was performed. In a combined analysis, the summary per-allele odds ratio for restenosis was 1.31 (95% CI: 1.08-1.58, P = 0.006), and 1.22 (95% CI: 0.95-1.56, P = 0.12), for PTCA-stent and PTCA-balloon, respectively. In the subgroup analysis by ethnicity, significantly increased restenosis risks after PTCA-stent were found in Asians for the polymorphism; whereas no significant associations were found among Caucasians. As for restenosis risks after PTCA-balloon, no evidence of any gene-disease association was obtained in the stratified analyses according to ethnicity and study size. In conclusion, this meta-analysis demonstrated that the DD homozygous of ACE I/D polymorphism was significantly associated with elevated restenosis susceptibility after PTCA-stent among Asian populations.

Genetic polymorphism of angiotensin converting enzyme and risk of coronary restenosis after percutaneous transluminal coronary angioplasties: evidence from 33 cohort studies

Background

In the past decade, a number of cohort studies studies have been carried out to investigate the relationship between the insertion/deletion polymorphism of the gene encoding angiotensin-converting enzyme and risk of restenosis after percutaneous transluminal coronary angioplasties in patients. However, these studies have yielded contradictory results. Genetic association studies addressing this issue are frequently hampered by insufficient power. We therefore performed a meta-analysis of the published studies to clarify this inconsistency and to establish a comprehensive picture of the relationship between ACE I/D polymorphism and post-PTCA restenosis risk.

Methods

Databases including Pubmed, EMBASE, ISI Web of Science, EBSCO, Cochrane Library databases and CNKI were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. The random-effects model was applied, addressing heterogeneity and publication bias.

Results

A total of 33 cohort studies involving 11,099 subjects were included. In a combined analysis, the OR for post-PTCA restenosis of the ACE DD genotype was 1.61 (95% CI: 1.27–2.04; P<10⁻⁵). In the subgroup analysis by intervention, significantly increased risks were also found in PTCA-stent and PTCA-balloon for the DD genotype of the polymorphism.

Conclusions

Our meta-analysis showed that the DD genotype of ACE I/D polymorphism was significantly associated with increased risk of restenosis, particularly for PTCA-stent.

Association of single nucleotide polymorphisms in the gene encoding platelet endothelial cell adhesion molecule-1 with the risk of myocardial infarction: a systematic review and meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) within the platelet endothelial cell adhesion molecule-1 (PECAM-1) gene have been proposed as predisposing factors for myocardial infarction (MI) but published reports have given conflicting findings.

OBJECTIVE

The present study aimed to clarify the association between SNPs in PECAM-1 and MI using a meta-analysis of published studies.

METHODS

Medline, HuGE Navigator and SCOPUS Library databases were searched to identify case-control studies which examined the association of SNPs in PECAM-1 and MI. Data were extracted using standardized methods. Combined odds ratios (OR) with 95% confidence intervals (CI) for the association of SNPs with MI were calculated using a random effect approach and under additive, dominant and recessive models of inheritance.

RESULTS

A total of 7 studies comprising 3886 cases and 4097 controls fulfilled the inclusion criteria. Three SNPs in PECAM-1 were investigated, namely rs668 (Leu125Val), rs12953 (Ser563Asn) and rs1131012 (Arg670Gly). The GG genotype of rs1131012 was associated with a reduced risk of MI under a recessive (OR: 0.81; 95%CI: 0.69-0.94; p=0.010), but not additive and dominant models (p>0.05). This association was robust in sensitivity analyses and not subject to heterogeneity. No significant association was detected between rs668 and rs12953 with MI under any of the inheritance models.

CONCLUSION

The results of the current meta-analysis suggest that homozygous polymorphic genotype (GG) of the rs1131012 SNP may confer protection against MI. The impact of this variant on the expression and function of PECAM-1 needs to be elucidated in future investigations.

Genetic polymorphism of NOS3 with susceptibility to deep vein thrombosis after orthopedic surgery: a case-control study in Chinese Han population

Deep vein thrombosis is one of the common complications of orthopedic surgery. Studies indicated that genetic factors played a considerable role in the pathogenesis of deep vein thrombosis. Endothelial nitric oxide synthase which encoded by nitric oxide synthase 3 (NOS3), can generate nitric oxide in endothelial cells. As a predominant regulator for vascular homeostasis, nitric oxide might be involved in the pathogenesis of thrombosis. It had been proved that the NOS3 polymorphism (rs1799983) was associated with the development of cardiovascular diseases. Our objective was to evaluate the association between the NOS3 polymorphism (rs1799983) and deep vein thrombosis after orthopedic surgery in Chinese Han population. The polymorphism was genotyped in 224 subjects with deep vein thrombosis after orthopedic surgery and 580 controls. Allele and genotype frequencies were compared between subjects with deep vein thrombosis and control subjects. The allele and genotype frequencies of the NOS3 polymorphism (rs1799983) were significantly different between subjects with deep vein thrombosis and control subjects. There were also significant differences when the subjects were stratified by gender, surgery type and hypertension status. These findings suggested that the NOS3 polymorphism (rs1799983) was associated with susceptibility to the deep vein thrombosis after orthopedic surgery in Chinese Han population, and NOS3 might play a role in the development of deep vein thrombosis after orthopedic surgery.

Association between polymorphisms of eNOS and GPx-1 genes, activity of free-radical processes and in-stent restenosis

Our aim was to examine correlations between polymorphisms in five antioxidant enzymes genes, activity of free-radical processes, and the risk of restenosis after coronary artery stenting with bare metal stents (BMS). A total of 101 male patients who underwent intracoronary stenting using BMS and coronary angiography follow-up of 6 months were enrolled in: group with in-stent restenosis (n = 44) and without restenosis (n = 57). The content of lipoperoxides and malondialdehyde (MDA) in Low-density lipoprotein (LDL), activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) in erythrocytes, and genotypes polymorphisms of the CAT gene (-262C/T), paraoxonase-1 (PON-1) gene (163T/A and 575A/G), endothelial nitric oxide synthase (eNOS) gene (298G/T (rs#1799983) and -786T/C), GPx-1 gene (599C/T (rs#1050450)), and glutathione-S-transferase (GSTP) gene (313A/G) were determined. In carriers of the minor allele of 599C/T polymorphism of the GPx-1 gene, activity of GPx in erythrocytes was lower by 17 % than in wild allele homozygotes, while the content of lipoperoxides in LDL was higher by 74 %. T-allele of 599C/T polymorphism of the GPx-1 gene (OR = 2.9; 95 % CI: 1.23-6.82) and T-allele of 298G/T polymorphism of the eNOS gene (OR = 2.79; 95 % CI: 1.17-6.66) were associated with the risk of in-stent restenosis. Minor alleles of polymorphisms 298G/T of the eNOS gene and 599C/T of the GPx-1 gene are associated with an increased risk of in-stent restenosis. Minor allele of the GPx-1 gene 599C/T polymorphism leads to a decrease of the GPx activity and increase of the activity of free-radical processes.

Systematic testing of literature reported genetic variation associated with coronary restenosis: results of the GENDER Study

Background

Coronary restenosis after percutaneous coronary intervention still remains a significant problem, despite all medical advances. Unraveling the mechanisms leading to restenosis development remains challenging. Many studies have identified genetic markers associated with restenosis, but consistent replication of the reported markers is scarce. The aim of the current study was to analyze the joined effect of previously in literature reported candidate genes for restenosis in the GENetic DEterminants of Restenosis (GENDER) databank.

Methodology/Principal Findings

Candidate genes were selected using a MEDLINE search including the terms ‘genetic polymorphism’ and ‘coronary restenosis’. The final set included 36 genes. Subsequently, all single nucleotide polymorphisms (SNPs) in the genomic region of these genes were analyzed in GENDER using set-based analysis in PLINK. The GENDER databank contains genotypic data of 2,571,586 SNPs of 295 cases with restenosis and 571 matched controls. The set, including all 36 literature reported genes, was, indeed, significantly associated with restenosis, p = 0.024 in the GENDER study. Subsequent analyses of the individual genes demonstrated that the observed association of the complete set was determined by 6 of the 36 genes.

Conclusion

Despite overt inconsistencies in literature, with regard to individual candidate gene studies, this is the first study demonstrating that the joint effect of all these genes together, indeed, is associated with restenosis.

Genetic causation of neointimal hyperplasia in hemodialysis vascular access dysfunction

The major cause of hemodialysis vascular access failure is venous stenosis resulting from neointimal hyperplasia. Genetic factors have been shown to be associated with cardiovascular disease and peripheral vascular disease (PVD) in the general population. Genetic factors may also play an important role in vascular access stenosis and development of neointimal hyperplasia by affecting pathways that lead to inflammation, endothelial function, oxidative stress, and vascular smooth muscle proliferation. This review will discuss the role of genetics in understanding neointimal hyperplasia development in hemodialysis vascular access dysfunction and other disease processes with similar neointimal hyperplasia development such as coronary artery disease and PVD.

Association of the 894G>T polymorphism in the endothelial nitric oxide synthase gene with risk of venous thromboembolism in Chinese population

INTRODUCTION

Endothelium derived nitric oxide (NO) is a key mediator of vascular homeostasis. Endothelial nitric oxide synthase (eNOS) gene, by affecting the expression and functional activity of the eNOS enzyme, thereby reducing NO availability, may be implicated in venous thromboembolism (VTE). We investigated the eNOS G894T polymorphism in VTE patients in the Chinese population.

MATERIALS AND METHODS

A case-control study was conducted in a general hospital. Blood samples, collected from 462 consecutive patients with VTE and 462 healthy controls, were used for DNA extraction. Single nucleotide polymorphisms (SNP) of eNOS (894G/T) were determined by allele specific-polymerase chain reaction (ARMS-PCR) analysis.

RESULTS

The eNOS 894G/T polymorphism alleles distribution was in agreement with the principle of Hardy-Weinberg equilibrium. The prevalence of homozygote, heterozygote and pathological homozygote for the eNOS G894T polymorphism in VTE patients was 79.7%, 18.1% and 2.2%, respectively (controls: 86.6%，12.3% and 1.1%). T allele distribution in the VTE (11.3%) and especially the male VTE patients (12.5%) was more common than in healthy controls (7.3%). The frequency of GT+TT genotype was significantly higher among the age≤55years patients in VTE group than in controls (20.1% vs. 12.2%, P=0.033).

CONCLUSION

Our result demonstrates that the 894G/T polymorphism variant of eNOS is a risk factor for VTE in Chinese population.

Role of Genetic Polymorphism of Angiotensin-Converting Enzyme, Plasminogen Activator Inhibitor-1 and Endothelial Nitric Oxide Synthase in the Prognosis of Coronary Artery Disease

Background

This study was to investigate the effects of multiple genetic polymorphisms and conventional risk factors in the prognosis of coronary artery disease (CAD).

Methods

One hundred and fifty five patients with CAD were prospectively recruited, they were subgrouped as single vessel disease (SVD) and multiple vessel disease (MVD). All patients were detected I/D polymorphism of angiotensin-converting enzyme (ACE) gene, 4G/5G polymorphism of plasminogen activator inhibitor-1 (PAI-1) gene, and G894→T mutation of endothelial nitric oxide synthase (eNOS) gene. The patients were followed up for 10-65 months, mean 35 months. End points were major adverse cardiovascular events (MACE), including angina, myocardial infarction, and cardiac sudden death.

Results

During the follow-up period, MACE developed in 81 patients, 73 patients with angina, seven with myocardial infarction, and one with cardiac sudden death. CAD patients with MVD were more probable of developing MACE during follow-up. Distribution of PAI-1 gene polymorphism was significantly different between SVD and MVD patients, p < 0.001. The frequency of DD genotype of ACE and 4G/4G genotype of PAI-1 in patients with MACE were significantly higher than those in patients without MACE, p < 0.001 and p = 0.002, respectively. Incidence of diabetes mellitus was significantly higher in patients with MACE than in patients without MACE, P = 0.03. Cox regression analysis showed that diabetes mellitus (HR 2.36, 95% CI 1.33-4.46, p = 0.003), 4G/4G polymorphism of PAI-1 gene (HR 3.45, 95% CI 1.71-6.56, p = 0.009), and D/D polymorphism of ACE gene (HR 2.99, 95% CI 1.84-5.76, p = 0.005), were independent predictors of the MACE.

Conclusions

Our results showed that the conventional risk factors and genetic polymorphisms have significant influence on prognosis of CAD patients. CAD patients with diabetes mellitus, DD genotype of ACE, and 4G/4G genotype of PAI-1 suggested poor prognosis.

A promoter polymorphism of the endothelial nitric oxide synthase gene is associated with reduced mRNA and protein expression in failing human myocardium

BACKGROUND

Alterations of endothelial nitric oxide synthase (eNOS) enzyme activity via eNOS gene polymorphisms have been associated with significant cardiovascular morbidity and mortality. Both the thymidine to cytosine transition mutation (T(-786)-->C) in the promoter region and the missense mutation in the exon 7 coding region of the eNOS gene (G(894)-->T) have been associated with several cardiovascular disease states. We hypothesized that heart transplant recipients who carried at least 1 allele of either of the polymorphisms would have reduced myocardial tissue expression of eNOS measured in the explanted heart.

METHODS AND RESULTS

Genomic DNA was isolated from myocardial tissue samples obtained from 43 explanted human hearts using standard methods. Regions of the eNOS gene were amplified from genomic DNA with a polymerase chain reaction using specific primers. Protein expression of eNOS was measured by Western blot analysis. There was a statistically significant decrease in mean eNOS expression in samples containing at least one allele for the T(-786)-->C promoter polymorphism (P=.04) compared with patients homozygous for the T allele. There was no change in eNOS expression associated with the G(894)-->T exonic polymorphisms.

CONCLUSIONS

Our data show in failing human myocardium that the T(-786)-->C promoter polymorphism is associated with reduced eNOS expression, whereas the G(894)-->T polymorphism of exon 7 is not associated with change in either eNOS mRNA or protein expression. Reduced eNOS expression associated with the promoter polymorphism may contribute to the vascular, contractile, and autonomic responses to ventricular failure.

Is Polymorphism within eNOS Gene Associated With the Late Onset of Myocardial Infarction? A Pilot Study

Introduction

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is a potent vasodilator. Several polymorphisms in the eNOS gene have been described, some of them being linked with the increased risk of cardiovascular disease, coronary heart disease (CHD), and coronary spasm.

Methods and Results

We studied 3 polymorphisms within the gene of eNOS (-786T/C, G10T, and 894 G/T) in patients with their first myocardial infarction (MI) younger than 45 years and in healthy volunteers. We found the relation between the occurrence of eNOS 894G allele and the Gensini score, which describes the severity of CHD ( P = .020).

Conclusions

The fact that first clinical manifestation of MI occurred in G carriers when the atherosclerotic plaque was much more advanced than in T carriers may suggest that wild-type genotype provided a better compensatory mechanisms due to NO synthesis and/or release. The polymorphisms within eNOS gene G10T, 894G/T, and −786T/C were not associated with the increased risk of MI.

ACE (I/D) polymorphism and response to treatment in coronary artery disease: a comprehensive database and meta-analysis involving study quality evaluation

BACKGROUND

The role of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in modifying the response to treatment modalities in coronary artery disease is controversial.

METHODS

PubMed was searched and a database of 58 studies with detailed information regarding ACE I/D polymorphism and response to treatment in coronary artery disease was created. Eligible studies were synthesized using meta-analysis methods, including cumulative meta-analysis. Heterogeneity and study quality issues were explored.

RESULTS

Forty studies involved invasive treatments (coronary angioplasty or coronary artery by-pass grafting) and 18 used conservative treatment options (including anti-hypertensive drugs, lipid lowering therapy and cardiac rehabilitation procedures). Clinical outcomes were investigated by 11 studies, while 47 studies focused on surrogate endpoints. The most studied outcome was the restenosis following coronary angioplasty (34 studies). Heterogeneity among studies (p < 0.01) was revealed and the risk of restenosis following balloon angioplasty was significant under an additive model: the random effects odds ratio was 1.42 (95% confidence interval:1.07-1.91). Cumulative meta-analysis showed a trend of association as information accumulates. The results were affected by population origin and study quality criteria. The meta-analyses for the risk of restenosis following stent angioplasty or after angioplasty and treatment with angiotensin-converting enzyme inhibitors produced non-significant results. The allele contrast random effects odds ratios with the 95% confidence intervals were 1.04(0.92-1.16) and 1.10(0.81-1.48), respectively. Regarding the effect of ACE I/D polymorphism on the response to treatment for the rest outcomes (coronary events, endothelial dysfunction, left ventricular remodeling, progression/regression of atherosclerosis), individual studies showed significance; however, results were discrepant and inconsistent.

CONCLUSION

In view of available evidence, genetic testing of ACE I/D polymorphism prior to clinical decision making is not currently justified. The relation between ACE genetic variation and response to treatment in CAD remains an unresolved issue. The results of long-term and properly designed prospective studies hold the promise for pharmacogenetically tailored therapy in CAD.

Association of the 894G>T polymorphism in the endothelial nitric oxide synthase gene with risk of acute myocardial infarction

BACKGROUND

This study was designed to investigate the association of the 894G>T polymorphism in the eNOS gene with risk of acute myocardial infarction (AMI), extent of coronary artery disease (CAD) on coronary angiography, and in-hospital mortality after AMI.

METHODS

We studied 1602 consecutive patients who were enrolled in the GEMIG study. The control group was comprised by 727 individuals, who were randomly selected from the general adult population.

RESULTS

The prevalence of the Asp298 variant of eNOS was not found to be significantly and independently associated with risk of AMI (RR = 1.08, 95%CI = 0.77-1.51, P = 0.663), extent of CAD on angiography (OR = 1.18, 95%CI = 0.63-2.23, P = 0.605) and in-hospital mortality (RR = 1.08, 95%CI = 0.29-4.04, P = 0.908).

CONCLUSION

In contrast to previous reports, homozygosity for the Asp298 variant of the 894G>T polymorphism in the eNOS gene was not found to be associated with risk of AMI, extent of CAD and in-hospital mortality after AMI.

Hyperinsulinemia and impaired leptin-adiponectin ratio associate with endothelial nitric oxide synthase polymorphisms in subjects with in-stent restenosis

Little is known about the association of endothelial nitric oxide synthase (NOS3) gene polymorphisms and the presence of insulin resistance and the early evolution of atherosclerosis in nondiabetic subjects with cardiovascular disease (CAD) and stent implantation. The present study was performed in an attempt to better understand whether metabolic, endothelial, and angiographic findings characteristic of subjects with cardiovascular disease and in-stent restenosis are related to NOS3 variants. This is a case-control study performed from 2002 to 2006. All subjects admitted to the study were recruited in the Nord-Centre of Italy, most from Milan and its surrounding towns. Measures of glucose tolerance, insulin sensitivity, markers of endothelial dysfunction, forearm vasodilation, and adipokine levels were determined and associated to the frequency of two single-nucleotide polymorphisms of NOS3, i.e., Glu298Asp (rs1799983, G/T) and rs753482 (intron 18 A/C). A total of 747 subjects, not known to have diabetes, were evaluated: 333 subjects had asymptomatic CAD, 106 subjects had unstable angina and were evaluated for in-stent restenosis 6 mo after stent placement, and 308 were control subjects. The presence of TT and CC minor alleles was significantly greater in case groups compared with control subjects. At phenotypic level, subjects with the polymorphisms were characterized by hyperinsulinemia and reduced reactive hyperemia, whereas increased leptin and decreased adiponectin levels were present in subjects with restenosis in the presence of reduced minimal lumen diameter and length of stenosis almost doubled. Hyperinsulinemia, endothelial dysfunction, and a more atherogenic profile seem to be peculiar features of subjects with asymptomatic CAD and restenosis carrying NOS3 gene variants.

Association of endothelial nitric oxide synthase promoter region (T-786C) gene polymorphism with acute coronary syndrome and coronary heart disease

BACKGROUND

Nitric oxide (NO) is an endothelium derived relaxing factor (EDRF) which has an important role for regulating the heart-vessel physiology. The objective of this study was to evaluate the effects of the eNOS T-786C polymorphism on lipid parameters and the development of acute coronary syndrome (ACS) and coronary heart disease (CHD) for the first time in a Turkish study group. We have analyzed the genotype frequencies of the T-786C polymorphism of the eNOS gene in 10 ACS patients (5 men, 5 women), 20 CHD patients (14 men, 6 women), and 31 controls (10 men, 21 women), who were angiographically proven to have normal coronaries.

RESULTS

The demographic, biochemical and left ventricule systolic dysfunction data of the ACS, CHD patients and controls were analyzed as a function of eNOS T-786C genotypes. The eNOS gene T-786C polymorphism frequencies for T/T, C/T and C/C genotypes were respectively 10%, 40%, 50% in subjects with ACS; 75%, 20%, 5% in subjects with CHD and 67.7%, 25.8%, 6.5% in the control group. Significant difference was observed in genotype frequencies between the study groups for T-786C polymorphism (p = 0.001). The CC genotype frequency was found to be the most prevalent in ACS group in comparison to CHD and control groups (p = 0.001). TT was the most frequently observed genotype in both CHD patients and controls (p = 0.001). Left ventricule systolic dysfunction frequency was found to be highest in C/T genotype carriers (66.7%) in patients (ACS+CHD). None of the patients with LVSD were carrying the normal genotype (T/T). The eNOS T-786C polymorphism was not found to be effective over any analyzed lipid variable in patients (ACS+CHD). The HDL-cholesterol levels were found to be lower in CHD group were compared to controls (p < 0.01), whereas glucose and leucocyte levels of the ACS and CHD groups were both higher than controls (p < 0.001).

CONCLUSION

The significantly high frequency of eNOS -786C/C genotype in ACS patients than in those of controls, indicate the genotype association with ACS. The finding of significantly high frequency of T/T genotype in the CHD group, may support the relationship of CC genotype with ACS without CHD. The high frequency of the mutant (C/C) and heterozygous (C/T) genotypes found may be linked to left ventricule remodeling after MI.

ALOX5AP variants are associated with in-stent restenosis after percutaneous coronary intervention

BACKGROUND

Use of drug-eluting stents (DES) has reduced in-stent restenosis after percutaneous coronary intervention (PCI); however, DES are associated with late stent thrombosis. There is no accurate way to predict in-stent restenosis, although risk factors for atherosclerosis overlap those for in-stent restenosis. Therefore, we evaluated atherosclerosis candidate genes for association with in-stent restenosis.

METHODS

We identified 46 consecutive cases that had undergone PCI with bare-metal stents who subsequently developed symptomatic in-stent restenosis of the target lesion (>/=75% luminal narrowing) within 6 months. Forty-six age-, race-, vessel-diameter- and sex-matched controls without in-stent restenosis after PCI with bare-metal stent were also identified. Single-nucleotide polymorphisms (SNPs, N=82) from 39 candidate atherosclerosis genes were genotyped. Multivariable logistic regression models were used to test for association.

RESULTS

Five SNPs were associated with in-stent restenosis. Three ALOX5AP SNPs were most strongly associated, two with increased risk (OR 3.74, p=0.01; OR 3.46, p=0.02), and the third with decreased risk of in-stent restenosis (OR 0.09, p=0.004). Two ALOX5AP haplotypes were associated with in-stent restenosis (HapB: OR 3.13, p=0.03); and a haplotype similar to HapA: OR 0.14, p=0.0009).

CONCLUSIONS

ALOX5AP, a gene within the inflammatory leukotriene pathway linked to and associated with coronary atherosclerosis, is also associated with in-stent restenosis. Genotyping these variants may help identify those at risk for in-stent restenosis who would benefit most from use of DES.

Endothelial nitric oxide synthase gene polymorphisms in non-arteritic anterior ischemic optic neuropathy

BACKGROUND

To examine the association between the polymorphisms of the endothelial nitric oxide synthase (eNOS) gene and the occurrence of non-arteritic anterior ischemic optic neuropathy (NAION).

METHODS

We studied 15 patients with NAION (mean age, 62 years; 60% male). We investigated two polymorphisms of the eNOS gene, Glu298Asp polymorphism of exon 7 and T(-786)C polymorphism of the promoter region. The genotype distribution in NAION was compared with the control (mean age, 63 years; 63% male) distribution.

RESULTS

There was no significant difference in the genotype distribution of the Glu298Asp polymorphism between the NAION and control groups (P = 1.000), whereas the genotype dis-tribution of the T(-786)C polymorphism varied significantly between the patients with NAION and control subjects (P = 0.002). After adjusting on covariates, individuals with the CC genotype of the T(-786)C polymorphism were more likely to develop NAION compared with those with TT genotype (odds ratio = 0.09: 95% CI 0.01-0.86).

CONCLUSIONS

We found an increased prevalence of T(-786)C polymorphism of the eNOS gene in patients with NAION. Our data suggest that the T(-786)C polymorphism of the eNOS gene may be an important risk factor in the development of NAION in Japanese subjects.

Genetic risk for restenosis after coronary stenting

OBJECTIVES

The purpose of the present study was to identify gene polymorphisms that confer susceptibility to restenosis after bare-metal stenting of coronary arteries, and thereby to predict the genetic risk for this condition.

METHODS AND RESULTS

The study population comprised 461 unrelated Japanese individuals (350 men, 111 women) who underwent stent implantation, including 107 subjects who developed in-stent restenosis and 354 subjects without this condition. The genotypes for 142 polymorphisms of 121 candidate genes were determined with a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Multivariate logistic regression analysis with adjustment for the prevalence of diabetes mellitus revealed that the 1615G-->A polymorphism of BCHE, the 7,067,365C-->A polymorphism of INSR, the C-->T polymorphism of GPX1, the G-->A polymorphism of ROS1, and the G-->A polymorphism of MMP9 were associated (P<0.05) with in-stent restenosis. Further analysis with adjustment both for the prevalence of diabetes mellitus and for quantitative coronary angiographic measurements revealed that the BCHE, GPX1, and ROS1 genotypes were independently associated (P<0.05) with in-stent restenosis.

CONCLUSIONS

Determination of the genotypes for BCHE, GPX1, and ROS1 may prove informative for assessment of the genetic risk for in-stent restenosis.

Endothelial nitric oxide synthase gene polymorphisms and cardiovascular disease: a HuGE review

This review examines the association of a subset of endothelial nitric oxide synthase gene (NOS3) polymorphisms (Glu298Asp, intron 4, and -786T>C) with cardiovascular disease. The Glu298Asp polymorphism within exon 7 is the only common nonsynonymous variant. The variants have been associated with low plasma nitric oxide concentrations and reduced vascular reactivity; difficulties in measuring those phenotypes means that their functional role remains unclear. A large meta-analysis of NOS3 polymorphisms in coronary heart disease revealed per-allele odds ratios of 1.17 (95% confidence interval: 1.07, 1.28) for Glu298Asp, 1.17 (95% confidence interval: 1.07, 1.28) for -786T>C, and 1.12 (95% confidence interval: 1.01, 1.24) for intron 4. However, there was evidence that small studies with more striking results could affect the associations of the Glu298Asp and -786T>C polymorphisms with coronary heart disease. Associations of NOS3 polymorphisms with hypertension, preeclampsia, stroke, and diabetes remain uncertain. To date, no reliable gene-gene or gene-environmental interactions have been described. Use of these variants in predictive testing is unlikely to be useful, although the population attributable fraction could be substantial if the modest associations are causal. The need for large-scale genetic association studies using tagging polymorphisms is warranted to confirm or refute a role of the NOS3 gene in coronary heart disease.

Present status of outcome prediction of invasive coronary treatment by using genetic markers

A growing number of studies suggest that the outcome after invasive coronary treatment may be in part genetically determined. Here, we review the present status of outcome prediction of invasive coronary treatments by using genetic markers. Although some studies found an association between one or another genetic marker with one or another clinical endpoint, many other studies found no such relations; to date, none of the genetic markers that have been investigated in association studies are used in routine clinical practice to prospectively assess the prognosis following invasive coronary treatment or to decide upon therapeutic strategies. Many associations between genetic markers and certain clinical endpoints were initially reported in small studies but could not be confirmed in larger ones. Some of these discrepancies may be explained by publication bias. Some genetic variants may have true effects on clinical endpoints, which, albeit biologically interesting, do not bear much clinical relevance. On the other hand, many-if not most-studies that have been published to date are more or less grossly underpowered and very rarely report on the results of an a priori power analysis. Thus, there is still a need for further high-quality studies designed to investigate the specific contribution of genetic factors to the outcome after invasive coronary interventions.

Toll-like receptor (TLR)-9 promotor polymorphisms and atherosclerosis

BACKGROUND

Currently, the primary cause of atherosclerosis remains controversial: while oxidized or enzymatically altered LDL is widely accepted as one cause of the inflamed lesion, microorganisms such as C. pneumoniae or cytomegalovirus (CMV) also have recently been postulated to be involved in the pathogenesis of atherosclerosis. Microbial products activate innate immune cells of the host via Toll-like receptors (TLRs). Common polymorphisms of the TLR-2 and TLR-4 genes have been shown to be associated with an increased risk for restenosis after PTCA, and a lower risk of carotid atherosclerosis, respectively. Microbial DNA has been shown to activate immune cells via the cytosolic TLR-9. Specially, C. pneumonia and CMV as intracellular pathogens may be potent trigger of TLR-9 signaling. Therefore, we investigated whether the two common promotor polymorphisms of the TLR-9 gene are correlated with atherogenesis.

METHODS

The T-1237C and the T-1486C polymorphisms were analyzed by Real Time PCR in 202 (derivation study, age 58.1, SD 10.0) and 182 (validation study, age 59.7, SD 9.6) patients that underwent angioplasty and 188 healthy controls (age 52.5, SD 6.1). Restenosis was defined as >50% luminal diameter reduction at follow-up angiography.

RESULTS

We found the two polymorphism being able to create new potential binding sites for transcription factors, however, no association of the TLR-9 polymorphisms with atherogenesis or restenosis was detectable.

CONCLUSION

Our data indicate that the two TLR-9 promotor polymorphisms are not involved in atherogenesis.

The GLU298ASP variant of nitric oxide synthase interacts with asymmetric dimethyl arginine in determining cardiovascular mortality in patients with end-stage renal disease

OBJECTIVES

Impaired nitric oxide generation and accumulation of the endogenous inhibitor of nitric oxide synthase (NOS), asymmetric dimethylarginine (ADMA), have been identified as strong predictors of cardiovascular outcomes in patients with end-stage renal disease (ESRD). We evaluated the role of endothelial NOS (eNOS) gene polymorphisms and its interaction with plasma ADMA in the high cardiovascular complications rate of these patients.

METHODS

The relationship between the Glu298Asp variant of eNOS and all-cause and cardiovascular mortality was assessed in a cohort study including 261 ESRD patients that were followed up for an average of 42 months.

RESULTS

During the follow-up period, 138 patients died, 81 of them (i.e. 59% of total deaths) of cardiovascular causes. On univariate Cox's regression analysis, eNOS genotype tended to be related to all-cause death but failed to reach formal statistical significance (P for trend=0.11). However, eNOS genotype showed a significant association with cardiovascular mortality in statistical models, including traditional risk factors and factors peculiar to ESRD, and became even stronger when plasma ADMA was forced into the Cox model (P=0.006). Furthermore, the risk of cardiovascular death was maximum in heterozygotes and homozygotes patients carrying the risk allele and in those having high ADMA levels (hazard ratio=2.71, 95% confidence interval 1.38-5.35, P=0.004) compared to those having just one of these two risk factors.

CONCLUSIONS

The T allele of the Glu298Asp polymorphism predicts cardiovascular mortality and interacts with plasma ADMA in determining this outcome in dialysis patients.

Relevance of the NOS3 T–786C and G894T variants for cholinergic and adrenergic coronary vasomotor responses in man

OBJECTIVE

We investigated the impact of the -786C allele at the promoter and the 894T allele in exon 7 of the gene encoding the endothelial nitric oxide synthase (NOS3) on coronary vasomotor responses to exogenous and endogenous stimuli.

METHODS

In 47 individuals undergoing coronary angiography for chest pain, but without significant stenosis in the left anterior descending artery (LAD), nitroglycerine and acetylcholine were infused intracoronarily, and a cold pressor test (CPT) was performed. Coronary blood flow (CBF) in the LAD was calculated from quantitative coronary angiography and intracoronary Doppler measurements. Aortic and coronary sinus lactate levels were determined in 18 individuals. To analyze the impact of NOS3 genotypes, a logistic regression model was used.

RESULTS

In response to acetylcholine (p = 0.002) and CPT (p = 0.015) CBF reduction was associated with homocygosity for the -786C allele. Myocardial lactate uptake was reversed into net lactate production in CC homocygotes. No independent effects of the G894T polymorphism were observed in the present study. Haplotype analysis revealed a significant linkage disequilibrium between both polymorphisms (p < 0.001).

CONCLUSIONS

Our findings suggest a pathophysiologically relevant role for the T-786C polymorphism in human coronary vasomotion. The observed linkage disequilibrium between both NOS3 genotypes deserves further research in future studies.

A frequent toll-like receptor (TLR)-2 polymorphism is a risk factor for coronary restenosis

Restenosis is a major problem for patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Inflammatory processes and genetic factors have been suggested to be involved in the pathogenesis of both atherosclerosis and restenosis. The recently discovered family of Toll-like receptors (TLRs) consists of molecules that initiate signaling after host-pathogen interactions. Recently it has been shown that the TLRs are involved in the development and progression of atherosclerosis by interfering with lipid metabolisms and by mediating inflammation. TLR-2 is a key innate immunity receptor for sensing both endogenous inflammatory mediators and ligands of several microbial pathogens postulated to be involved in atherosclerosis. A frequent single nucleotide polymorphism (SNP) for the TLR-2 gene, resulting in a non-functional receptor, has been described. By genotyping two independent groups of patients receiving PTCA, followed by stent implantation in one group, we found a significantly enhanced frequency of the TLR-2 Arg753Gln SNP in patients with restenosis as compared to those without restenosis (PTCA: 7.21 versus 2.45%, P = 0.014; PTCA/stent: 6.86 versus 1.53%, P = 0.013). In contrast, a common TLR-4 SNP was similarly distributed among the patient groups investigated. We furthermore compared the frequency of both SNPs in the patients with an age-matched group of individuals without atherosclerosis and found a trend towards a lower frequency of the TLR-4 SNP in the atherosclerotic group (PTCA: 5.58; PTCA/stent: 3.85 versus 7.14%). We conclude that in restenosis a functional TLR-2 is protective and potentially involved in a reaction pattern preventing restenosis. Screening for the TLR-2 Arg753Gln SNP may be of importance for stratifying a patient's risk and for preventive and therapeutic measures.

Nitric oxide insufficiency and atherothrombosis

Nitric oxide (NO) is a structurally simple compound that participates in a wide range of biological reactions to maintain normal endothelial function and an antithrombotic intravascular milieu. Among its principal effects are the regulation of vascular tone, vascular smooth muscle cell proliferation, endothelial-leukocyte interactions, and the antiplatelet effects of the endothelium. Impaired NO bioavailability represents the central feature of endothelial dysfunction, the earliest stage in the atherosclerotic process, and also contributes to the pathogenesis of acute vascular syndromes by predisposing to intravascular thrombosis. The causes of NO insufficiency can be grouped into two fundamental mechanisms: inadequate synthesis and increased inactivation of NO. Polymorphisms in the endothelial NO synthase gene and decreased substrate or cofactor availability for this enzyme are the main mechanisms that compromise the synthesis of NO. Inactivation of NO occurs mainly through its interaction with reactive oxygen species and can be favored by a deficiency of antioxidant enzymes such as glutathione peroxidase. In this review, we present an overview of NO synthesis and biological chemistry, discuss the mechanisms of action of NO in regulating endothelial and platelet function, and explore the causes of NO insufficiency, as well as the evidence linking these causes to the pathophysiology of endothelial dysfunction and atherothrombosis.

Genetic predictive factors in restenosis

Restenosis is still the main drawback of percutaneous transluminal coronary angioplasty (PTCA). It is thought to be a multifactorial process where recoil of the vessel, neointimal proliferation and thrombus formation are thought to play a role. Until now it has proven difficult to predict restenosis on clinical and procedural grounds, however, genetic epidemiology might provide more insights. In this review several genetic variables, i.e. polymorphisms that were determined in relation to restenosis are described. The single nucleotide polymorphisms (SNPs) described in the literature so far involve; the renin-angiotensin system, platelet aggregation, the inflammatory response, matrix metalloproteinases, smooth muscle cell proliferation, lipids and oxidative stress and nitric oxide. Nowadays DNA-microarrays have been developed which make it possible to test 50 or 60 polymorphisms at once. However, the risk of error due to multiple testing should be kept in mind. The results of the studies described should be interpreted with care. Many of the published studies are of relatively small sample size, which sometimes show more positive outcomes than the larger studies, this is possibly due to publication bias towards more positive results. The small sample size studies also exhibit wide confidence intervals. On the other hand, one must take into account that the process of restenosis is a multifactorial one and it is likely that multiple genes are involved. Thus, relatively small odds ratios relating to single gene contribution to restenosis can be of paramount importance when encompassed in the overall picture. Although still much research has to be done, stratification according to genetic make-up may enable tailoring of the interventional treatment to the individual patient.

Rapid and inexpensive real-time PCR for genotyping functional polymorphisms within the Toll-like receptor -2, -4, and -9 genes

The discovery of the human Toll-like receptors (TLRs) and the recognition of their pivotal role in sensing microbial pathogens during the last 5 years have resulted in a renewed appreciation of innate immunity. Due to their central role in both, triggering innate immunity as well as linking innate and adaptive immunity, genetic variations within the TLR genes, known to be associated with a variety of infectious diseases, are currently of great interest. Several single nucleotide polymorphisms (SNPs) within TLR genes have been described and seem to be associated with susceptibility to inflammatory diseases. However, methods for genotyping SNPs within the TLR genes, e.g. direct sequencing or polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) analysis, are time-consuming. In this work, we report novel real-time PCR methods for genotyping five TLR SNPs within TLR-2, TLR-4 and TLR-9 that have been associated with various diseases using fluorescence labeled hybridization probes and the LightCycler instrument. In addition, we provide protocols employing a standard Taq polymerase in order to reduce substantially the costs for real-time PCR.

Genetics of thrombophilia: impact on atherogenesis

PURPOSE OF REVIEW

The goal of this review is to present an update on basic and epidemiological findings associating variants in prothrombotic genes with atherogenesis and atherothrombotic disease.

RECENT FINDINGS

The relation between atherosclerosis and thrombosis has long been recognized but only recently has it been understood that certain hemostatic factors affect not only thrombus formation, but also have a direct atherogenic role. Atherosclerosis is a complex disorder that results from the interaction of multiple genetic and environmental factors. Numerous polymorphisms and mutations in genes related to the hemostatic system and to vascular redox determinants that modulate nitric oxide bioavailability have been identified in the past decade; their role in atherogenesis and the risk of cardiovascular disease, however, remain uncertain. We will discuss the functional implications and association with disease risk of polymorphisms in coagulation factors (fibrinogen, prothrombin, and factor V); fibrinolytic factors (plasminogen activator inhibitor 1 and lipoprotein(a)); platelet surface receptors; and vascular redox determinants (methylenetetrahydrofolate reductase, endothelial nitric oxide synthase, and the antioxidant enzymes cellular glutathione peroxidase and paraoxonase).

SUMMARY

Overall, these genetic variants have a modest effect on risk when considered individually but gain potency when acting synergistically with other genetic or environmental risk factors. We conclude that a better characterization of these interactions, in addition to the identification of potential novel genetic determinants, constitute key issues in the future understanding of the pathogenesis of atherothrombosis.