Association between aldosterone synthase (CYP11B2) gene polymorphism and left ventricular volume in patients with dilated cardiomyopathy

Association of -344C/T polymorphism in the aldosterone synthase (CYP11B2) gene with cardiac and cerebrovascular events in Chinese patients with hypertension

Objective

Several recent studies have shown that the aldosterone synthase gene (CYP11B2) −344C/T polymorphism is related to cardiovascular diseases. However, whether the −344C allele influences the incidence of cardiovascular diseases in Chinese patients with hypertension is unclear.

Methods

Chinese patients with essential hypertension were genotyped for the −344C/T polymorphism in CYP11B2 (n = 755; CC, n = 112; CT, n = 361; TT, n = 282) and followed for 11 years for major adverse cardiovascular events (MACEs), including stroke, onset of coronary artery disease (CAD), and CAD-related death. Established cardiovascular risk factors were used to adjust the multivariate Cox analysis.

Results

After a mean follow-up period of 7.60 ± 1.12 years, a significantly higher incidence of MACEs was seen in patients with the CC genotype than in those with the CT and TT genotypes. The CC variant was significantly and independently predictive of MACEs (hazard ratio = 2.049), CAD (hazard ratio = 1.754), and stroke (hazard ratio = 2.588), but not CAD-related stroke or death.

Conclusion

The CYP11B2 −344 CC genotype is a risk factor for CAD and stroke, independent of other established cardiovascular risk factors in Chinese patients with hypertension.

Association of the -344T/C polymorphism in aldosterone synthase gene promoter with left ventricular structure in Chinese Han: A meta-analysis

No consensus view has been published on the relationship between the aldosterone synthase gene (CYP11B2) -344C/T polymorphism and left ventricular hypertrophy (LVH) in Chinese Han. We undertook a meta-analysis to investigate the potential association of this polymorphism and left ventricular structure-related phenotypes, including left ventricular mass (LVM), left ventricular mass index (LVMI), left ventricular end systolic diameter (LVESD), left ventricular end diastolic dimension (LVEDD), left ventricular posterior wall thickness (LVPWT), and interventricular septal wall thickness (IVS). Studies in English and Chinese were found based on a systematic search of Medline, Embase, CNKI, and Wanfang databases. The dominant model (TT vs. TC+CC) and homozygote model (TT vs. CC) were selected to examine the association between the -344C/T polymorphism and LVH. The random-effects model was used to pool data. From a total of 3104 participants, despite the investigation of six echocardiographic indicators, we found no significant association between the -344C/T variant and LVH in the whole group and the subgroup analyses by blood pressure. However, in the subgroup of northern Han Chinese, TT genotype had higher LVPWT than CC genotype and TC genotype (p_{heterogeneity} = 0.4, p_value = 0.04, 95% CI 0.09 (0.00, 0.18)). In addition, no evidence of publication bias was observed. In conclusion, our meta-analysis indicated that subjects with TT genotype might have higher risk of developing LVH in northern Han Chinese.

Role of common sarcomeric gene polymorphisms in genetic susceptibility to left ventricular dysfunction

Mutations in sarcomeric genes are common genetic cause of cardiomyopathies. An intronic 25-bp deletion in cardiac myosin binding protein C (MYBPC3) at 3' region is associated with dilated and hypertrophic cardiomyopathies in Southeast Asia. However, the frequency of sarcomeric gene polymorphisms and associated clinical presentation have not been established with left ventricular dysfunction (LVD). Therefore, the aim of the present study was to explore the association of MYBPC3 25-bp deletion, titin (TTN) 18 bp I/D, troponin T type 2 (TNNT2) 5 bp I/D and myospryn K2906N polymorphisms with LVD. This study includes 988 consecutive patients with angiographically confirmed coronary artery disease (CAD) and 300 healthy controls. Among the 988 CAD patients, 253 with reduced left ventricle ejection fraction (LVEF≤45%) were categorized as LVD. MYBPC3 25-bp deletion, TTN 18 bp I/D and TNNT2 5 bp I/D polymorphisms were determined by direct polymerase chain reaction method, while myospryn K2906N polymorphism by TaqMan assay. Our results showed that MYBPC3 25-bp deletion polymorphism was significantly associated with elevated risk of LVD (LVEF <45) (healthy controls versus LVD: OR=3.85, P <0.001; and nonLVD versus LVD: OR=1.65, P = 0.035), while TTN 18 bp I/D, TNNT2 5 bp I/D and myospryn K2906N polymorphisms did not show any significant association with LVD. The results also showed that MYBPC3 25-bp deletion polymorphism was significantly associated with other parameters of LV remodelling, i.e. LV dimensions (LV end diastole dimension, LVEDD: P = 0.037 and LV end systolic dimension, LVESD: P = 0.032). Our data suggests that MYBPC3 25-bp deletion may play significant role in conferring LVD as well as CAD risk in north Indian population.

Aldosterone and cardiovascular remodelling: focus on myocardial failure

Heart failure is a clinical syndrome that may result from different disease states or conditions that injure the myocardium. The activation of circulating neurohormones, particularly aldosterone, may play a pivotal role in left ventricular (LV) remodelling. The Randomized Aldactone Evaluation Study and Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival trial have emphasised the clinical importance of aldosterone. This review addresses some of the proposed mechanisms of LV remodelling in heart failure.

Determined to Fail--the Role of Genetic Mechanisms in Heart Failure

Genetic variants contribute to several steps during heart failure pathophysiology. The mechanisms include frequent polymorphisms that increase the susceptibility to heart failure in the general population and rare variants as causes of an underlying cardiomyopathy. In this review, we highlight recent discoveries made by genetic approaches and provide an outlook onto the role of epigenetic modifiers of heart failure.

Relationship of Genetic Polymorphisms of Aldosterone Synthase Gene Cytochrome P450 11B2 and Mineralocorticoid Receptors with Coronary Artery Disease in Taiwan

The aldosterone synthase gene, cytochrome P450 11B2 (CYP11B2), and mineralocorticoid receptor (MR) genes have been reported to be associated with coronary artery disease (CAD). In this study, we investigated the association of single nucleotide polymorphisms (SNPs) of CYP11B2 (CYP11B2 T-344C) and MR (MR C3514G and MR C4582A) with CAD in Taiwanese. Six hundred and nine unrelated male and female subjects who received elective coronary angiography were recruited from Chung Shan Medical University Hospital. The enrolled subjects were those who had a positive noninvasive test. CYP11B2 T-344C, MR C3514G and MR C4582A were determined by polymerase chain reaction-restriction fragment length polymorphism. We found that women with CYP11B2 C/C had a higher risk of developing CAD. However, there were no significant differences in the genotype distributions of MR C3514G and MR C4582A between the women with and without CAD. In multivariate analysis, CYP11B2 T-344C was most significantly associated with CAD in Taiwanese women. In conclusions, CYP11B2 C/C was more significantly associated with the development of CAD than diabetes mellitus or hypertension. This implies that CYP11B2 C/C plays a more important role than some conventional risk factors in the development of CAD in Taiwanese women.

Impact of repeated intravenous bone marrow mesenchymal stem cells infusion on myocardial collagen network remodeling in a rat model of doxorubicin-induced dilated cardiomyopathy

Bone marrow mesenchymal stem cells (MSCs) transplantation improved cardiac function and reduced myocardial fibrosis in both ischemic and non-ischemic cardiomyopathies. We evaluated the effects of repeated peripheral vein injection of MSCs on collagen network remodeling and myocardial TGF-β1, AT1, CYP11B2 (aldosterone synthase) gene expressions in a rat model of doxorubicin (DOX)-induced dilated cardiomyopathy (DCM). Thirty-eight out of 53 SD rats survived at 10 weeks post-DOX injection (2.5 mg/kg/week for 6 weeks, i.p.) were divided into DCM blank (without treatment, n = 12), DCM placebo (intravenous tail injection of 0.5 mL serum-free culture medium every other day for ten times, n = 13), and DCM plus MSCs group (intravenous tail injection of 5 × 10(6) MSCs dissolved in 0.5 mL serum-free culture medium every other day for 10 times, n = 13). Ten untreated rats served as normal controls. At 20 weeks after DOX injection, echocardiography, myocardial collagen content, myocardial expressions of types I and III collagen, TGF-β1, AT1, and CYP11B2 were compared among groups. At 20 weeks post-DOX injection, 8 rats (67%) survived in DCM blank group, 9 rats (69%) survived in DCM placebo group while 13 rats (100 %) survived in DCM plus MSCs group. Left ventricular end-diastolic diameter was significantly higher and ejection fraction was significantly lower in DCM blank and DCM placebo groups compared to normal control rats, which were significantly improved in DCM plus MSCs group (all p < 0.05 vs. DCM blank and DCM placebo groups). Moreover, myocardial collagen volume fraction, types I and III collagen, myocardial mRNA expressions of TGF-β1, AT1, CYP11B2, and collagen I/III ratio were all significantly lower in DCM plus MSCs group compared to DCM blank and DCM placebo groups (all p < 0.05). Repeated intravenous MSCs transplantation could improve cardiac function by attenuating myocardial collagen network remodeling possibly through downregulating renin-angiotensin-aldosterone system in DOX-induced DCM rats.

Association of aldosterone synthase polymorphism (CYP11B2 -344T>C) and genetic ancestry with atrial fibrillation and serum aldosterone in African Americans with heart failure

The objective of this study was to examine the extent to which aldosterone synthase genotype (CYP11B2) and genetic ancestry correlate with atrial fibrillation (AF) and serum aldosterone in African Americans with heart failure. Clinical data, echocardiographic measurements, and a genetic sample for determination of CYP11B2 -344T>C (rs1799998) genotype and genetic ancestry were collected from 194 self-reported African Americans with chronic, ambulatory heart failure. Genetic ancestry was determined using 105 autosomal ancestry informative markers. In a sub-set of patients (n = 126), serum was also collected for determination of circulating aldosterone. The CYP11B2 -344C allele frequency was 18% among the study population, and 19% of patients had AF. Multiple logistic regression revealed that the CYP11B2 -344CC genotype was a significant independent predictor of AF (OR 12.7, 95% CI 1.60-98.4, p = 0.0150, empirical p = 0.011) while holding multiple clinical factors, left atrial size, and percent European ancestry constant. Serum aldosterone was significantly higher among patients with AF (p = 0.036), whereas increased West African ancestry was inversely correlated with serum aldosterone (r = -0.19, p = 0.037). The CYP11B2 -344CC genotype was also overrepresented among patients with extreme aldosterone elevation (≥90th percentile, p = 0.0145). In this cohort of African Americans with chronic ambulatory heart failure, the CYP11B2 -344T>C genotype was a significant independent predictor of AF while holding clinical, echocardiographic predictors, and genetic ancestry constant. In addition, increased West African ancestry was associated with decreased serum aldosterone levels, potentially providing an explanation for the lower risk for AF observed among African Americans.

Association of 25 bp deletion in MYBPC3 gene with left ventricle dysfunction in coronary artery disease patients

Rationale

Mutations in MYBPC3 encoding cardiac myosin binding protein C are common genetic cause of hereditary cardiac myopathies. An intronic 25-bp deletion in MYBPC3 at 3′ region is associated with dilated (DCM) and hypertrophic (HCM) cardiomyopathies in Southeast Asia. However, the frequency of MYBPC3 25 bp deletion and associated clinical presentation has not been established in an unrelated cohort of left ventricular dysfunction (LVD) secondary to coronary artery disease (CAD) patients.

Objective

We sought to determine the role of MYBPC3 25 bp polymorphism on LVD in two cohorts of CAD patients.

Methods and Results

The study included 265 consecutive patients with angiographically confirmed CAD and 220 controls. MYBPC3 25 bp polymorphism was determined by polymerase chain reaction. Our results showed that carrier status of MYBPC3 25 bp deletion was associated with significant compromised left ventricle ejection fraction (LVEF ≤45) in CAD patients (p value  =  <0.001; OR = 4.49). To validate our results, we performed a replication study in additional 140 cases with similar clinical characteristics and results again confirmed consistent findings (p = 0.029; OR = 3.3). Also, presence of the gene deletion did not have significant association in CAD patients with preserved ejection fraction (LVEF>45) (p value  = 0.1; OR  = 2.3).

Conclusion

The frequency of MYBPC3 DW genotype and D allele was associated with compromised LVEF implying that genetic variants of MYBPC3 encoding mutant structural sarcomere protein could increase susceptibility to left ventricular dysfunction. Therefore, 25 bp deletion in MYBPC3 may represent a genetic marker for cardiac failure in CAD patients from Southeast Asia.

Aldosterone synthase gene (CYP11B2) promoter polymorphism as a risk factor for ischaemic stroke in Tunisian Arabs

INTRODUCTION

We investigated the contribution of aldosterone synthase CYP11B2 polymorphism (C-344T) to the age-related changes in blood pressure in stroke patients.

SUBJECTS AND METHODS

Study subjects comprised 329 stroke patients (121 normotensive, 208 hypertensive) and 444 healthy controls. Genotyping was done by PCR-RFLP, and the contribution of CYP11B2 polymorphism to the risk of stroke was analysed by regression analysis.

RESULTS

The T allele, and CT, TT, and CT + TT genotypes, independently of sex and age, were significantly associated with increased stroke risk. Varied distributions of CYP11B2 genotypes were noted among patients with respect to gender, age and hypertension status, being pronounced in hypertensive patients. Both systolic and diastolic blood pressure were positively correlated with the presence of T allele. Mean systolic and diastolic blood pressure were significantly higher among young (< 60 years) CT and TT genotype carriers. Regression analysis confirmed the positive association of CT and TT genotypes and systolic blood pressure, and the negative association of diastolic blood pressure with odds of stroke development. Taking normotensive patients as reference, regression analysis identified TT genotype, age and female gender to be independently associated with increased odds of stroke.

CONCLUSION

Compared to CC genotype, CT and TT CYP11B2 genotypes are independently associated with increased stroke index.

Aldosterone synthase gene polymorphism as a determinant of atrial fibrillation in patients with heart failure

We analyzed the possible association between aldosterone synthase (CYP11B2) T-344C polymorphism, which is associated with increased aldosterone activity, and the prevalence of atrial fibrillation (AF) in 196 consecutive patients who had symptomatic systolic heart failure (HF; left ventricular ejection fraction <40%) for > or =3 months before recruitment. Genomic DNA was extracted from peripheral blood leukocytes using a standard protocol. Subjects were genotyped for the CYP11B2 polymorphism using the polymerase chain reaction/restriction fragment length polymorphism approach. AF was present in 63 patients (33%) with HF. We found the -344 CC genotype to be a strong independent marker for AF. Almost 1/2 (45%) of patients with this genotype had AF compared with 1/4 (27%) with -344 TT and TC genotypes (p = 0.01). A multivariate stepwise logistic regression model that included age, gender, New York Heart Association class, CYP11B2 -344CC genotype, and echocardiographic measurements of left ventricular ejection fraction, left atrial dimension, left ventricular end-diastolic diameter, and mitral regurgitation severity showed that the CYP11B2 CC genotype (adjusted for age and left atrial size) was an independent predictor of AF (adjusted odds ratio 2.35, 95% confidence interval 1.57 to 3.51, p = 0.03). In conclusion, CYP11B2 T-344C promoter polymorphism predisposes to clinical AF in patients with HF.

Usefulness of the aldosterone synthase gene polymorphism C-344-T to predict cardiac remodeling in African-Americans versus non-African-Americans with chronic systolic heart failure

A common polymorphism exists for the aldosterone synthase (CYP11B2) gene at position 344 (C-344-T). The 344-C allele has been associated with increased aldosterone synthase activity. We hypothesized that the aldosterone synthase gene polymorphism is associated with adverse cardiac remodeling in an ambulatory, chronic heart failure population. The CYP11B2 C-344T genotype was determined in 104 patients with heart failure who were in New York Heart Association classes I to IV, had left ventricular ejection fractions <40%, and were prospectively recruited from an urban heart failure clinic (65% African-American, 69% had a nonischemic cause, with a mean left ventricular ejection fraction of 22 +/- 9%). The 344-C allele frequency was 0.34 (45.2% TT, 42.3% CT, and 12.5% CC) and was significantly lower in African-American (0.27) versus Non-African-American patients (0.44, p = 0.018). Baseline and 1-year follow-up echocardiograms were obtained in 74 patients. Improvement was defined as a decrease in left ventricular end-systolic diameter (LVESD). At follow-up, the 344-C allele was associated with improved LVESD (p = 0.013). In addition, analysis by race showed that this effect was observed only in African-American patients (p <0.006). In multivariate logistic regression, controlling for cause, gender, and spironolactone use, the TT genotype (i.e., absence of 344-C allele) was associated with a fivefold lower rate of improvement in LVESD in African-Americans (p = 0.014). In conclusion, the 344-C allele of the aldosterone synthase gene polymorphism was associated with improved cardiac remodeling over time for African-Americans with chronic systolic heart failure. Although this genetic-driven increase in aldosterone activity should predispose to worse cardiac remodeling, it may represent a more susceptible state and enhanced response to therapy in this racial subgroup.

Cytochrome P450 enzymes: Central players in cardiovascular health and disease

Cardiovascular disease (CVD) is a human health crisis that remains the leading cause of death worldwide. The cytochrome P450 (CYP) class of enzymes are key metabolizers of both xenobiotics and endobiotics. Many CYP enzyme families have been identified in the heart, endothelium and smooth muscle of blood vessels. Furthermore, mounting evidence points to the role of endogenous CYP metabolites, such as epoxyeicosatrienoic acids (EETs), hydroxyeicosatetraenoic acids (HETEs), prostacyclin (PGI(2)), aldosterone, and sex hormones, in the maintenance of cardiovascular health. Emerging science and the development of genetic screening have provided us with information on the differences in CYP expression among populations and groups of individuals. With this information, a link between CYP expression and activity and CVD, such as hypertension, coronary artery disease (CAD), myocardial infarction, heart failure, stroke, and cardiomyopathy and arrhythmias, has been established. In fact many currently used therapeutic modalities in CVD owe their therapeutic efficacy to their effect on CYP metabolites. Thus, the evidence for the involvement of CYP in CVD is numerous. Concentrating on treatment modalities that target the CYP pathway makes ethical sense for the affected individuals and decreases the socioeconomic burden of this disease. However, more research is needed to allow the integration of this information into a clinical setting.

Cytochrome p450 enzymes and cardiovascular disease

The cytochrome p450 (CYP) superfamily is responsible for the oxidation, peroxidation, and (or) reduction of vitamins, steroids, xenobiotics, and the majority of cardiovascular drugs in an oxygen- and NADPH-dependent manner. Although hepatic CYP have been studied extensively, the role of CYP in cardiovascular physiology and disease is poorly understood. Increasing evidence suggests that these enzymes play an important role in the pathogenesis of a number of cardiovascular diseases. The current review summarizes the understanding as to the role that dysregulated CYP expression and (or) activity may play in the onset and progression of cardiovascular disease.

Multiple Polymorphisms in the renin- angiotensin-aldosterone system (ACE, CYP11B2, AGTR1) and their contribution to hypertension in African Americans and Latinos in the multiethnic cohort

OBJECTIVE

When compared with other U.S. populations, African Americans have excess hypertension. Genetic variants in elements of the renin-angiotensin-aldosterone system (RAAS), namely the angiotensin-converting enzyme (ACE), aldosterone synthase (CYP11B2), and angiotensin II type 1 receptor (AGTR1) genes, have been associated with risk of hypertension in some populations.

METHODS

We genotyped the D/I polymorphism in the ACE gene, the C(-344)T polymorphism in the CYP11B2 gene, and the C(-535)T polymorphism in the AGTR1 gene among African American and Latino members of the Multiethnic Cohort Study (MEC) to determine their association with hypertension.

RESULTS

We observed no significant increase in the risk of hypertension for either African Americans or Latinos homozygous or heterozygous for the D allele of the ACE gene. Among African Americans we observed carriers of the (-344)T allele of CYP11B2 to be at increased risk of hypertension (versus CC genotype: TC genotype, OR = 1.66 [95% CI: 1.01-2.72]; TT genotype, OR = 1.74 [95% CI: 1.07-2.82]). There was also an increase in risk of hypertension associated with the AGTR1 T allele for African Americans (versus CC genotype: TC genotype, OR = 2.62 [95% CI: 1.46-4.72]; TT genotype, OR = 2.67 [95% CI: 1.51-4.74]). The associations observed with CYP11B2 and AGTR1 genotypes were not observed among Latinos.

CONCLUSION

These data suggest that the (-535)T allele of AGTR1 and (-344)T allele of CYP11B2 may increase hypertension risk among African Americans but not among Latinos. Characterization of the linkage disequilibrium and haplotype patterns in the RAAS pathway genes will be crucial to understanding differences in hypertension susceptibility in these ethnic populations.

Genetic polymorphisms and heart failure

Heart failure is a complex clinical syndrome. There is evidence for a genetic contribution to the pathophysiology of heart failure. Considering the fundamental role of neurohormonal factors in the pathophysiology and progression of cardiac dysfunction and hypertrophy, variants of genes involved in this system are logical candidate genes in heart failure. In this report, genetic polymorphisms of the major neurohormonal systems in heart failure will be discussed. Studies on polymorphisms of the renin-angiotensin-aldosterone system (RAAS), adrenergic receptor polymorphisms, endothelin (receptor) polymorphisms, and a group of miscellaneous polymorphisms that may be involved in the development or phenotypic expression of heart failure will be reviewed. Research on left ventricular hypertrophy is also included. The majority of genetic association studies focused on the ACE I/D polymorphism. Initial genetic associations have often been difficult to replicate, mainly due to problems in study design and lack of power. Promising results have been obtained with genetic polymorphisms of the RAAS and sympathetic system. Considering the evidence so far, a modifying role for these polymorphisms seems more likely than a role of these variants as susceptibility genes. Besides the need for larger studies to examine the effects of single nucleotide polymorphisms and haplotypes, future studies also need to focus on the complexity of these systems and study gene-gene interactions and gene-environment interactions.

Genetic predisposition to heart failure

This review describes the numerous and complex molecular systems that are either known players or candidates in heart failure(HF). All systems whose genetic background has been investigated to date in HF are listed and discussed. Discussion also includes functional notes and known genetic polymorphisms already investigated in HF or candidates that have not yet been investigated. Despite substantial research on HF, relatively few coordinated studies have been conducted that assign precise risk to specific genetic polymorphisms. Identification of risk associated with genetic variations and subsequent translation of genetic knowledge into clinical practice will likely progress only in cases of large coordinated studies based on identical standards. The potential result will be a more accurate definition of HF identified as an evolving complex of cardiovascular diseases.