PAI-1 4G/5G and ACE I/D gene polymorphisms and the occurrence of myocardial infarction in patients on intermittent dialysis

Plasminogen Activator Inhibitor-1 Activity and 4G/5G Polymorphism in Hemodialysis

Introduction

Chronic insufficiency alters homeostasis, in part due to endothelial inflammation. Plasminogen activator inhibitor-1 (PAI-1) is increased in renal disease, contributing to vascular damage. We assessed PAI-1 activity and PAI-1 4G/5G polymorphism in hemodialysis (HD) subjects and any association between thrombotic vascular access (VA) events and PAI-1 polymorphism.

Methods

Prospective, observational study in 36 HD patients: mean age: 66.6 ± 12.5 yr, males n=26 (72%), time on HD: 28.71 ± 22.45 months. Vascular accesses: 10 polytetrafluoroethylene grafts (PTFEG), 22 arteriovenous fistulae (AVF), four dual lumen catheters (CAT). Control group (CG): 40 subjects; mean age: 60.0 ± 15 yrs, males n=30 (75%). Group A (GA): thrombotic events (n=12), and group B (GB): No events (n=24). Groups were no different according to age (69.2 ± 9.12 vs. 65.3 ± 14.5 yrs), gender (males: 7; 58.3% vs. 18; 81.8%), time on HD (26.1 ± 14.7 vs. 30.1 ± 38.7 months), causes of renal failure. Time to follow-up for access thrombosis: 12 months.

Results

PAI-1 levels in HD: 7.21 ± 2.13 vs. CG: 0.42 ± 0.27 U/ml (p<0.0001). PAI-1 4G/5G polymorphic variant distribution in HD: 5G/5G: 6 (17%), 4G/5G: 23 (64%); 4G/4G: 7 (19%) and in CG: 5G/5G: 14 (35%); 4G/5G: 18 (45%); 4G/4G: 8 (20%). C-reactive protein (CRP) in HD: 24.5 ± 15.2 mg/L vs. in CG 2.3 ± 0.2 mg/L (p<0.0001). PAI-1 4G/5G variants: GA: 5G/5G: 3; 4G/5G: 8; 4G/4G: 1; GB: 5G/5G: 3; 4G/5G: 15; 4G/4G: 6. Thrombosis occurred in 8/10 patients (80%) with PTFEG, 3/22 (9%) in AVF, and 1/4 (25%) in CAT. Among the eight PTFEG patients with thrombosis, seven were PAI 4G/5G.

Conclusions

PAI-1 levels were elevated in HD patients, independent of their polymorphic variants, 4G/5G being the most prevalent variant. Our data suggest that in patients with PTFEG the 4G/5G variant might be associated with an increased thrombosis risk.

Influence of ACE I/D Polymorphism on Circulating Levels of Plasminogen Activator Inhibitor 1, D-Dimer, Ultrasensitive C-Reactive Protein and Transforming Growth Factor β1 in Patients Undergoing Hemodialysis

BACKGROUND

There is substantial evidence that chronic renal and cardiovascular diseases are associated with coagulation disorders, endothelial dysfunction, inflammation and fibrosis. Angiotensin-Converting Enzyme Insertion/Deletion polymorphism (ACE I/D polymorphism) has also be linked to cardiovascular diseases. Therefore, this study aimed to compare plasma levels of ultrassensible C-reactive protein (usCRP), PAI-1, D-dimer and TGF-β1 in patients undergoing HD with different ACE I/D polymorphisms.

METHODS

The study was performed in 138 patients at ESRD under hemodialysis therapy for more than six months. The patients were divided into three groups according to the genotype. Genomic DNA was extracted from blood cells (leukocytes). ACE I/D polymorphism was investigated by single polymerase chain reaction (PCR). Plasma levels of D-dimer, PAI-1 and TGF-β1 were measured by enzyme-linked immunosorbent assay (ELISA), and the determination of plasma levels of usCRP was performed by immunonephelometry. Data were analyzed by the software SigmaStat 2.03.

RESULTS

Clinical characteristics were similar in patients with these three ACE I/D polymorphisms, except for interdialytic weight gain. I allele could be associated with higher interdialytic weight gain (P = 0.017). Patients genotyped as DD and as ID had significantly higher levels of PAI-1 than those with II genotype. Other laboratory parameters did not significantly differ among the three subgroups (P = 0.033). Despite not reaching statistical significance, plasma levels of usCRP were higher in patients carrying the D allele.

CONCLUSION

ACE I/D polymorphisms could be associated with changes in the regulation of sodium, fibrinolytic system, and possibly, inflammation. Our data showed that high levels of PAI-1 are detected when D allele is present, whereas greater interdialytic gain is associated with the presence of I allele. However, further studies with different experimental designs are necessary to elucidate the mechanisms involved in these associations.

Interaction between angiotensin-converting enzyme gene insertion/deletion polymorphism and angiotensin-converting enzyme inhibition on survival in hemodialyzed patients

The association between ACE (angiotensin-converting enzyme) gene insertion/deletion (I/D) polymorphism and mortality has been inconsistently observed in earlier studies in patients on maintenance hemodialysis. We hypothesized that the effect of ACE gene I/D polymorphism on mortality may be influenced by concurrent ACE inhibitor therapy in this population. In this prospective, multicenter cohort, observational study, data was collected from 716 prevalent chronic hemodialysis patients, blood samples were genotyped for I/D single nucleotide polymorphism. Patient mortality was assessed in tree genotype groups insertion/insertion, insertion/deletion and deletion/deletion (I/I, I/D, and D/D) using multivariate Cox proportional hazard models. The most frequent genotype was I/D (42.6%), followed by D/D (37.7%) and I/I (19.7%) genotypes. The mean age was 54.9±15.5 years, 53.2% of all patients were male and in the total group the prevalence of diabetes was 19.3%. ACE inhibitor therapy was prescribed for 47.9% of all patients. The median duration of dialysis before blood sampling was 23.8 months (IQR 11.2-47.1). Patients were followed for 10 years, the median follow-up time was 29.8 months (IQR 12.6-63.4). Patient characteristics were well balanced among the genotype groups. D/D genotype, was associated with inferior survival (I/I vs D/D: log-rank test: P=0.04) in patients not receiving ACE inhibitor therapy, and the presence of this therapy diminished this difference. There was no difference in survival among unselected patients with different genotypes. In multivariate Cox regression models, D/D genotype (compared to I/I) was a significant predictor of mortality only in patients without ACE inhibitor therapy (HR 0.67, 95% CI 0.46-0.97, P=0.03). Our data suggests that hemodialyzed patients with the deletion/deletion (D/D) genotype might have inferior outcome, and ACE inhibitor therapy may be associated with improved survival in this subgroup.

Survival and predictive factors of lethality in hemodialysis: D/I polymorphism of the angiotensin I-converting enzyme and of the angiotensinogen M235T genes

BACKGROUND

End-stage kidney disease patients continue to have markedly increased cardiovascular disease morbidity and mortality. Analysis of genetic factors connected with the renin-angiotensin system that influences the survival of the patients with end-stage kidney disease supports the ongoing search for improved outcomes.

OBJECTIVE

To assess survival and its association with the polymorphism of renin-angiotensin system genes: angiotensin I-converting enzyme insertion/deletion and angiotensinogen M235T in patients undergoing hemodialysis.

METHODS

Our study was designed to examine the role of renin-angiotensin system genes. It was an observational study. We analyzed 473 chronic hemodialysis patients in four dialysis units in the state of Rio de Janeiro. Survival rates were calculated by the Kaplan-Meier method and the differences between the curves were evaluated by Tarone-Ware, Peto-Prentice, and log rank tests. We also used logistic regression analysis and the multinomial model. A p value ≤ 0.05 was considered to be statistically significant. The local medical ethics committee gave their approval to this study.

RESULTS

The mean age of patients was 45.8 years old. The overall survival rate was 48% at 11 years. The major causes of death were cardiovascular diseases (34%) and infections (15%). Logistic regression analysis found statistical significance for the following variables: age (p = 0.000038), TT angiotensinogen (p = 0.08261), and family income greater than five times the minimum wage (p = 0.03089), the latter being a protective factor.

CONCLUSIONS

The survival of hemodialysis patients is likely to be influenced by the TT of the angiotensinogen M235T gene.

Angiotensin-converting enzyme insertion/deletion polymorphism contributes high risk for chronic kidney disease in Asian male with hypertension--a meta-regression analysis of 98 observational studies

Background

Associations between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphisms and chronic kidney disease (CKD) have been extensively studied, with most studies reporting that individuals with the D allele have a higher risk. Although some factors, such as ethnicity, may moderate the association between ACE I/D polymorphisms and CKD risk, gender-dependent effects on the CKD risk remain controversial.

Objectives

This study investigated the gender-dependent effects of ACE I/D polymorphisms on CKD risk.

Data sources

PubMed, the Cochrane library, and EMBASE were searched for studies published before January 2013.

Study eligibility criteria, participants, and interventions

Cross-sectional surveys and case–control studies analyzing ACE I/D polymorphisms and CKD were included. They were required to match the following criteria: age >18 years, absence of rare diseases, and Asian or Caucasian ethnicity.

Study appraisal and synthesis methods

The effect of carrying the D allele on CKD risk was assessed by meta-analysis and meta-regression using random-effects models.

Results

Ethnicity [odds ratio (OR): 1.24; 95% confidence interval (CI): 1.08–1.42] and hypertension (OR: 1.55; 95% CI: 1.04–2.32) had significant moderate effects on the association between ACE I/D polymorphisms and CKD risk, but they were not significant in the diabetic nephropathy subgroup. Males had higher OR for the association between ACE I/D polymorphisms and CKD risk than females in Asians but not Caucasians, regardless of adjustment for hypertension (p<0.05). In subgroup analyses, this result was significant in the nondiabetic nephropathy group. Compared with the I allele, the D allele had the highest risk (OR: 3.75; 95% CI: 1.84–7.65) for CKD in hypertensive Asian males.

Conclusions and implications of key findings

The ACE I/D polymorphisms may incur the highest risk for increasing CKD in hypertensive Asian males.

Genetic polymorphisms of the RAS-cytokine pathway and chronic kidney disease

Chronic kidney disease (CKD) in children is irreversible. It is associated with renal failure progression and atherosclerotic cardiovascular (CV) abnormalities. Nearly 60% of children with CKD are affected since birth with congenital or inherited kidney disorders. Preliminary evidence primarily from adult CKD studies indicates common genetic risk factors for CKD and atherosclerotic CV disease. Although multiple physiologic pathways share common genes for CKD and CV disease, substantial evidence supports our attention to the renin angiotensin system (RAS) and the interlinked inflammatory cascade because they modulate the progressions of renal and CV disease. Gene polymorphisms in the RAS-cytokine pathway, through altered gene expression of inflammatory cytokines, are potential factors that modulate the rate of CKD progression and CV abnormalities in patients with CKD. For studying such hypotheses, the cooperative efforts among scientific groups and the availability of robust and affordable technologies to genotype thousands of single nucleotide polymorphisms (SNPs) across the genome make genome-wide association studies an attractive paradigm for studying polygenic diseases such as CKD. Although attractive, such studies should be interpreted carefully, with a fundamental understanding of their potential weaknesses. Nevertheless, whole-genome association studies for diabetic nephropathy and future studies pertaining to other types of CKD will offer further insight for the development of targeted interventions to treat CKD and associated atherosclerotic CV abnormalities in the pediatric CKD population.

Plasminogen activator inhibitor type 1 gene polymorphisms and haplotypes are associated with plasma plasminogen activator inhibitor type 1 levels but not with myocardial infarction or stroke

BACKGROUND

The 4G allele in the promoter region of the plasminogen activator inhibitor type 1 (PAI-1) gene is associated with higher plasma PAI-1 levels and activity, but its association with cardiovascular diseases is unclear. We investigated the association of polymorphisms and common haplotypes of the PAI-1 gene with plasma PAI-1 levels, as well as the risk of myocardial infarction and stroke.

METHODS AND RESULTS

This study is a prospective analysis of 2995 community-based participants (41% blacks and 51% women) aged 70 to 79 years old in the Health, Aging, and Body Composition Study. From 1997/1998 to 2001, 177 myocardial infarction events and 101 stroke events were identified. In addition to the 4G/5G polymorphism, 2 potential functional variants and other 4 haplotype-tagging variants were genotyped. In general linear models, the 4G allele was associated with higher PAI-1 levels after adjusting for age, sex, race, and site (26, 29, and 32 ng/mL for 5G/5G, 4G/5G, and 4G/4G, respectively; P for trend < .0001), but none of the other 6 polymorphisms was associated with PAI-1 levels. Haplotype analysis produced similar results. However, in Cox proportional hazard models, neither the polymorphisms nor the common haplotypes of the PAI-1 gene was associated with the risk of either myocardial infarction or stroke.

CONCLUSIONS

The 4G allele is associated with higher PAI-1 levels, but this study does not support an association of the PAI gene polymorphisms with the risk of either myocardial infarction or stroke.

The risk of dialysis access thrombosis is related to the transforming growth factor-beta1 production haplotype and is modified by polymorphisms in the plasminogen activator inhibitor-type 1 gene

Transforming growth factor-beta1 (TGF-beta1) and plasminogen activator inhibitor-type 1 (PAI-1) might play a role in the development of fibrosis and stenosis of hemodialysis vascular accesses. We studied polymorphisms in the TGFbeta1 (869T>C; 915G>C), and PAI-1 (4G/5G) genes in 416 hemodialysis patients (107 access thrombosis cases, 309 controls), to determine if they are related to vascular access thrombosis. Three TGF-beta1 production haplotypes (low, intermediate, and high) were defined according to the combination of polymorphisms found. The adjusted odds ratio (OR) and 95% confidence interval (CI) for access thrombosis in low TGF-beta1 producers was 7.31 (2.15-24.88; P = .001). The interaction between low TGF-beta1 production haplotype and the 4G/4G PAI-1 genotype was strongly associated with access thrombosis (adjusted OR 19.3; 95% CI 2.82-132.40; P = .003). Mean access thrombosis-free survival times in years (95% CI) were 14.65 (12.05-17.25), 11.96 (8.67-15.25), and 4.94 (3.06-6.83) in high, intermediate, and low TGF-beta1 producers, respectively (P = .044). Analysis of the synergy index and the case-only cross-product supported the presence of an interaction. We concluded that low TGF-beta1 production haplotype is a risk factor for hemodialysis access thrombosis and that in the presence of the 4G/4G PAI-1 genotype there is an additional increase in risk.

ACE I/D polymorphism is associated with mortality in a cohort study of patients starting with dialysis

BACKGROUND

In dialysis patients, only a few follow-up studies have addressed the relationship between the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene and mortality, but the available data are contradictory.

METHODS

A cohort of 453 consecutive patients starting dialysis between January 1999 and January 2002 and participating in a Dutch multicenter prospective study was examined. Patients who died within 3 months after the start of dialysis were excluded. Patients were followed until date of death or censoring in November 2003.

RESULTS

The ACE II, ID, and DD genotype frequencies were 24.3% (N = 110), 50.1% (N = 227), and 25.6% (N = 116). Besides a slightly higher number of Caucasians in the DD group, all other patient characteristics of the 3 ACE groups were similar at the start of dialysis. After adjustment for age, comorbidity, and ethnic background, patients with the ID and DD genotype showed an increased hazard ratio (HR) for all-cause mortality of 1.55 (95% CI 1.00-2.42) and 2.30 (95% CI 1.41-3.75), compared to patients with the II genotype. Slightly lower HRs were found for cardiovascular mortality. All groups of primary kidney disease showed a 2- to 3-fold increased adjusted HR for DD.

CONCLUSION

The DD genotype identifies dialysis patients at an increased risk for mortality.

Molecular Genetic Testing of Polymorphisms Associated With Venous Thrombosis

The growing knowledge of genetic polymorphisms predisposing to venous thrombosis has increased the demand for genetic testing of associated risk factors. This has prompted the need for simple, fast, reliable, and cost-effective genotyping methods for identification of those mutations. In the past decade, a large variety of DNA mutation analysis methods have been developed for detection of genetic variants associated with venous thrombosis, including PCR-based and PCR-independent technologies. Each of these technologies possesses unique advantages, but all have a common goal of simplifying and expediting mutation analysis. This review describes some of the commonly used technologies and commercially available platforms employed in clinical laboratories for genetic testing of thrombophilia. The choice of a technology for each individual laboratory would primarily depend on the specific requirements for the assay's accuracy, reliability, speed, throughput, and cost-effectiveness.

Gene polymorphism association studies in dialysis: cardiovascular disease

Cardiovascular disease (CVD) is the most important cause of morbidity and mortality in dialysis patients. The high prevalence of CVD is due to the cumulative effects of multiple risk factors from the early stages of chronic kidney disease (CKD). Familial predispositions to CVD, CKD, and their respective risk factors are well known, and it is likely that genetic factors determine the interindividual variability in risks for disease. Advances in genomic technology have facilitated the study of genetic variation--most commonly single nucleotide polymorphisms (SNPs) in candidate genes--and their associations with disease. This review examines CVD in dialysis patients as a model of a complex disease, discusses the approach to gene polymorphism association studies, including the roles of gene-environment and gene-gene interactions and provides an overview of available studies.

Model for gene-environment interaction: the case for dialysis

Organ complications in end-stage renal disease (ESRD) such as cardiovascular disease, anemia, bone disease, malnutrition, inflammation, and infections occur in many organ systems and are caused by a multitude of underlying disease-, uremia-, and therapy-related factors, and with a wide range of manifestations and severity. Interindividual variability in the pathophysiologic response of the uremic host to environmental factors, including renal replacement therapy, may be governed to a significant degree by genetic susceptibility factors. Specific genes regulate the pathophysiologic responses of organ systems affected by ESRD and can serve as candidate genes for the host-environment interaction. This review summarizes emerging clinical and translational research work in the field of genetic polymorphism of candidate genes and their effects on the development of organ complications in ESRD. Methodologic limitations of the existing published data, the need for large prospective cohort studies, and potential future risks for the use of genomic information in resource allocation are also highlighted.

Distribution of PAI-1 promoter 4G/5G polymorphism in healthy Chinese and functional characterization using a luciferase reporter vector

The aim of this study was to analyze the distribution of plasminogen activator inhibitor-1 (PAI-1) promoter 4G/5G polymorphism in healthy Chinese and compare the transcription activity of the two PAI-1 promoters using luciferase reporter vector pGL(3). PAI-1 promoter 4G/5G polymorphism was analyzed in 77 healthy Chinese using allele-specific polymerase chain reaction (PCR). The PAI-1 promoters from individuals homozygous for the insertion (5G) and deletion (4G) were cloned into luciferase reporter vector pGL(3), respectively. The transcription activities of the two promoters (PAI-1-4G and PAI-1-5G) were then compared using the luciferase reporter vectors expressed in ECV304 and HepG(2) cell lines. Among the 77 healthy Chinese the genotype frequency for 4G/4G, 4G/5G, and 5G/5G was 49.1, 44.1, and 6.5%, respectively. Both of the two PAI-1 promoters cloned into luciferase reporter vector pGL(3), expressed very well both in ECV304 and HepG(2), and have similar basic transcription activity. Thrombin (10-20 U/ml) has no effects on the transcription activity of the two promoters expressed in ECV304, while in the HepG(2) cell line interleukin-1 (IL-1) 158 U/ml increased the transcription activity of PAI-1-4G by 67% (p<0.05, n=5) without effects on PAI-1-5G transcription activity. The distribution of PAI-1 promoter 4G/5G polymorphism in Chinese is obviously different from that in Caucasians with the 4G allele more frequently found in Chinese. PAI-1 promoter 4G/5G polymorphism does not alter basic transcription activity and 4G promoter has increased response to IL-1.

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.