A pharmacogenetic analysis of determinants of hypertension and blood pressure response to angiotensin-converting enzyme inhibitor therapy in patients with vascular disease and healthy individuals

Single nucleotide polymorphism (SNP) rs4291 of the angiotensin-converting enzyme (ACE) gene is associated with the response to losartan treatment in hypertensive patients

Arterial hypertension is characterized by systolic pressure ≥ 140 mmHg and/or diastolic pressure ≥ 90 mmHg and its treatment consists of the use of antihypertensive drugs, as losartan and hydrochlorothiazide. Blood pressure is regulated by angiotensin-converting enzyme (ACE) and polymorphisms in the ACE gene are associated to a greater predisposition to hypertension and response to treatment. The aim of this study was to evaluate the association of genetic polymorphisms of ACE rs4363, rs4291 and rs4335 and the response to antihypertensive drugs in hypertensive patients from Ouro Preto/MG, Brazil. A case-control study was carried out with 87 hypertensive patients being treated with losartan and 75 with hydrochlorothiazide, who answered a questionnaire and had blood samples collected. Biochemical analyzes were performed on serum using UV/Vis spectrophotometry and identification of ACE variants rs4363, rs4291 and rs4335 was performed by real-time PCR using the TaqMan® system. Univariate logistic regression test was performed to compare categorical data in STATA 13.0 software. The results showed that there was an influence of ACE polymorphisms on the response to losartan, demonstrating that AT or TT genotypes of rs4291 were more frequent in the group of controlled AH (54.9%), indicating that these individuals are 2.8 times more likely to of being controlled AH (95% CI 1.12-6.80, p. =0.026) compared to those with AA genotype. In contrast, no influence of ACE polymorphisms on the response to hydrochlorothiazide was observed. In conclusion, the presence of the T allele of the rs4291 variant was associated to controled blood pressure when losartan was used as an antihypertensive agent. These results show the importance of pharmacogenetic studies to detect genetic characteristics, enabling therapeutic individuality and reducing costs for the healthcare system.

The (pro)renin receptor as a pharmacological target in cardiorenal diseaes

The (pro)renin receptor ((P)RR) is not only a member of the renin-angiotensin system (RAS) but also exerts several RAS-independent functions due to its multiple signal transductions pathways. In this mini-review, we shortly discuss the molecular functions of this receptor and its pathophysiological significance with a focus on cardiorenal diseases. Finally, we provide a short summary regarding a drug discovery and drug development program on small molecule-based renin/ prorenin receptor blockers (RERBs).

Analysis of the Pattern, Alliance and Risk of rs1799752 (ACE I/D Polymorphism) with Essential Hypertension

Studies in spontaneously hypertensive rat had revealed an elevated level of ACE gene expression in the tissues and is substantiated by experimental clinical studies for a positive correlation between ACE I/D polymorphism and hypertension. Aim: To determine whether the polymorphic variant of ACE gene in intron 16 confers susceptibility to essential hypertension. I/D polymorphism at the locus intron 16 of the ACE gene were amplified from the genomic DNA of the total 571 (hypertensive patients, n: 279; controls, n: 292) participants using polymerase chain reaction and gel electrophoresis methods and were examined in a case-control approach. Suitable descriptive statistics was used for different variables. Result revealed significant heterogeneity under the allele (p: 0.0002) and genotype (p: 0.0001) contrast in hypertensive patients than in normal controls, with an increased frequency of D allele (62.72%; p < 0.0001; OR: 1.8144; 95% CI: 1.4327-2.2979) and DD genotype (41.93%; p: < 0.0001). A significant association was found in the DD variant with disease phenotype (p: 0.0018, 95% CI: 1.3303-3.4907; OR: 2.1549; Table 31) and is substantiated by the data of multivariate analysis, demonstrating a statistically significant increase in odds of hypertension with the ACE D/D genotype (OR: 2.09; 95% CI: 1.24-2.91). Conspicuously, subgroup analysis by gender did not change this pattern of results. Albeit the allele distribution resulted in a higher frequency of the D/D genotype in the cases than controls, testing genetic equilibrium between the observed and expected genotypes using Hardy-Weinberg equilibrium showed ACE gene variants were confirming to the law in hypertensive as well as in non-hypertensive participants. I/D polymorphism in the angiotensin-I-converting enzyme gene at the 16th intron can be useful for outcome predictions during diagnostic processes can be implicated in an individual's propensity for hypertension and thus implies that genetic variants of ACE I/D might serve as a predictor for the susceptibility to hypertension.

Gene Polymorphisms of the Renin-Angiotensin-Aldosterone System as Risk Factors for the Development of In-Stent Restenosis in Patients with Stable Coronary Artery Disease

This study investigated the renin-angiotensin-aldosterone system (RAAS) gene polymorphisms as possible genetic risk factors for the restenosis development in patients with drug-eluting stents. 113 participants had coronary artery disease and underwent stenting. The control group consisted of 62 individuals with intact coronary arteries. Patients were divided into two groups: with in-stent restenosis (ISR) and without it. The patients with ISR were classified into subgroups by the terms of the restenosis development and age. Real-time PCR and Restriction Fragment Length Polymorphism-PCR were used to genotype the study participants for RAAS gene polymorphisms. We found that the development of restenosis is generally associated with the minor A allele for renin (REN) rs2368564 and the major TT genotype for angiotensinogen (AGT) rs699. The heterozygous genotype for AGT rs4762 acts as a protective marker. A minor A allele for angiotensin II type 2 receptor (AGTR2) rs1403543 is associated with a risk of restenosis in people under 65 years old. Among patients with the early ISR, heterozygotes for angiotensin II type 1 receptor (AGTR1) rs5186 are more frequent, as well as A allele carriers for AGTR2 rs1403543. A minor homozygous genotype for REN rs41317140 and heterozygous genotype for aldosterone synthase (CYP11B2) rs1799998 are predisposed to the late restenosis. Thus, to choose the effective treatment tactics for patients with coronary artery disease, it is necessary to genotype patients for the RAAS polymorphisms, which, along with age and clinical characteristics, will allow a comprehensive assessment of the risk of the restenosis development after stenting.

Differential Effects of Combination of Renin-Angiotensin-Aldosterone System Inhibitors on Central Aortic Blood Pressure: A Cross-Sectional Observational Study in Hypertensive Outpatients

BACKGROUND

Central aortic blood pressure (CABP) indices, central hemodynamics, and arterial stiffness are better predictors of cardiovascular events as compared with brachial cuff pressure measurements alone. The present study is aimed at assessing the effects of different antihypertensive drug combination regimens involving renin-angiotensin-aldosterone system (RAAS) inhibitors on CABP indices in Indian patients with hypertension.

METHODS

This was a cross-sectional, single-center study conducted in patients treated for hypertension for >6 weeks using different treatment regimens involving the combination of RAAS inhibitors with drugs from other classes. CABP indices, vascular age, arterial stiffness, and central hemodynamics were measured in patients using the noninvasive Agedio B900 device (IEM, Stolberg, Germany) and compared between different treatment regimens.

RESULTS

A total of 199 patients with a mean age of 54.22 ± 10.15 years were enrolled, where 68.8% had hypertension for over three years and 50.25% had their systolic blood pressure (SBP) < 140 mmHg. Combination treatment with angiotensin II receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs) was given to 77.9% and to 20.1% patients, respectively. The mean vascular age was higher than the actual age (58.13 ± 12.43 vs. 54.22 ± 10.15, p = 0.001). The SBP and diastolic blood pressure (DBP) levels in patients treated with ACEI-based combinations were lower than those in patients treated with ARB-based combinations (p < 0.05). The mean central pulse pressure amplification, augmentation pressure, and augmentation index were lower in patients treated with ACEI-based combinations than those treated with other treatments (p = 0.001). In a subgroup analysis, patients given perindopril and calcium channel blockers (CCBs) or diuretics had significantly lower CABP and pulse wave velocity than those given other treatments (p < 0.05). A total of 6.5% patients experienced any side effects.

CONCLUSION

The majority of central hemodynamic parameters, including vascular age, were found to improve more effectively in patients treated with ACEIs than with ARBs. Our results indicate a gap between routine clinical practice and evidence-based guidelines in Indian settings and identify a need to reevaluate the current antihypertensive prescription strategy.

ACEI-induced cough: A review of current evidence and its practical implications for optimal CV risk reduction

Cough is one of the common adverse effects in patients receiving angiotensin-converting enzyme inhibitors (ACEIs). This review presents the current evidence on incidence and mechanisms of cough associated with ACEIs use, and proposes a practical approach for managing the same for optimal cardiovascular (CV) risk reduction. The incidence of dry cough in patients receiving ACEIs vary among individual ACEIs, and is the lowest with perindopril. Cough is thought to originate from multiple mechanisms, bradykinin theory is the most commonly appealed hypothesis. The strategies for optimal management could be temporarily discontinuation of ACEI upon a reported incidence of cough and reintroduction after its remission. However, studies have reported disappearance of cough despite continuing treatment. Another important approach could be adding calcium channel blockers to ACEIs. Switching to alternative drugs such as angiotensin receptor blockers should be suggested in case intolerable symptoms recur and after exclusion of all other possible causes of cough.

Pharmacogenetic analyses of variations of measures of cardiovascular risk in Alzheimer's dementia

Background & objectives:

Neurodegeneration affects blood pressure variations, while renal function and cerebral perfusion are impaired by vascular risk factors. This study was aimed to estimate variations of measures of cardiovascular risk in Alzheimer's dementia by pharmacogenetic analyses of the effects of angiotensin-converting enzyme (ACE) inhibitors and statins.

Methods:

Consecutive patients were prospectively followed to study variations of creatinine clearance and blood pressure for one year, estimated by correlating the effects of ACE inhibitors with the ACE Alu I/D polymorphism and genotypes or haplotypes of rs1800764 or rs4291, and the effects of statins with LDLR (low-density lipoprotein receptor) genotypes or haplotypes of rs11669576 (exon 8) or rs5930 (exon 10), or genotypes of rs2695121 (liver X receptor β gene). Variations of the coronary heart disease (CHD) risk according to these cardiovascular measures were also explored.

Results:

All polymorphisms of the 193 patients were in Hardy-Weinberg equilibrium. Genetic determinants of cardiovascular effects affected the individual variability of the response to ACE inhibitors and statins. ACE inhibitors, but not statins, reduced blood pressure for all patients. ACE inhibitors protected carriers of alleles that supposedly decrease serum ACE levels (rs1800764-T, rs4291-A, Alu II) regarding creatinine clearance variations (P<0.005), but carriers of Alu DD (P<0.02), rs1800764-C (P<0.05), or rs4291-AT (P<0.04) showed better blood pressure lowering effects. The presence of rs2695121-T (P=0.007) or rs5930-A (P=0.039) was associated with systolic blood pressure lowering, whereas rs5930-AA was protective against decrease in creatinine clearance (P=0.019). Statins lowered creatinine clearance for carriers of rs2695121-CT (P=0.026).

Interpretation & conclusions:

Pharmacological response of blood pressure and creatinine clearance to ACE inhibitors and statins may be genetically mediated.

The (pro)renin receptor in health and disease

The (pro)renin receptor ((P)RR) was first identified as a single-transmembrane receptor in human kidneys and initially attracted attention owing to its potential role as a regulator of the tissue renin-angiotensin system (RAS). Subsequent studies found that the (P)RR is widely distributed in organs throughout the body, including the kidneys, heart, brain, eyes, placenta and the immune system, and has multifaceted functions in vivo. The (P)RR has roles in various physiological processes, such as the cell cycle, autophagy, acid-base balance, energy metabolism, embryonic development, T cell homeostasis, water balance, blood pressure regulation, cardiac remodelling and maintenance of podocyte structure. These roles of the (P)RR are mediated by its effects on important biological systems and pathways including the tissue RAS, vacuolar H⁺-ATPase, Wnt, partitioning defective homologue (Par) and tyrosine phosphorylation. In addition, the (P)RR has been reported to contribute to the pathogenesis of diseases such as fibrosis, hypertension, pre-eclampsia, diabetic microangiopathy, acute kidney injury, cardiovascular disease, cancer and obesity. Current evidence suggests that the (P)RR has key roles in the normal development and maintenance of vital organs and that dysfunction of the (P)RR is associated with diseases that are characterized by a disruption of the homeostasis of physiological functions.

Contribution of Four Polymorphisms in Renin-Angiotensin-Aldosterone-Related Genes to Hypertension in a Thai Population

Introduction

The roles of genes in the renin-angiotensin-aldosterone system (RAAS) in hypertension, including angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II receptor type 1 (AGTR1), and aldosterone synthase (CYP11B2), have been widely studied across different ethnicities, but there has been no such investigation in Thai population.

Materials and Methods

Using 4,150 Thais recorded in the Electricity Generating Authority of Thailand (EGAT) study, we examined the association of rs1799752, rs699, rs5186, and rs1799998 located in or near ACE, AGT, AGTR1, and CYP11B2 genes in hypertension. We investigated their roles in hypertension using multivariate logistic regression and further examined their roles in blood pressure (BP) using quantile regression. Sex, age, and BMI were adjusted as potential confounders.

Results

We did not observe associations between hypertension and rs1799752 (P=0.422), rs699 (P=0.36), rs5186 (P=0.49), and rs1799998 (P=0.71). No evidence of association between these SNPs and BP was found across an entire distribution. A nonlinear relationship between age and BP was observed.

Conclusion

In Thai population, our study showed no evidence of association between RAAS-related genes and hypertension. While our study is the first and largest study to investigate the role of RAAS-related genes in hypertension in Thai population, restricted statistical power due to limited sample size is a limitation.

The prorenin receptor in the cardiovascular system and beyond

Since the prorenin receptor (PRR) was first reported, its physiological role in many cellular processes has been under intense scrutiny. The PRR is currently recognized as a multifunctional receptor with major roles as an accessory protein of the vacuolar-type H+-ATPase and as an intermediary in the Wnt signaling pathway. As a member of the renin-angiotensin system (RAS), the PRR has demonstrated to be of relevance in cardiovascular diseases (CVD) because it can activate prorenin and enhance the enzymatic activity of renin, thus promoting angiotensin II formation. Indeed, there is an association between PRR gene polymorphisms and CVD. Independent of angiotensin II, the activation of the PRR further stimulates intracellular signals linked to fibrosis. Studies using tissues and cells from a variety of organs and systems have supported its roles in multiple functions, although some remain controversial. In the brain, the PRR appears to be involved in the central regulation of blood pressure via activation of RAS- and non-RAS-dependent mechanisms. In the heart, the PRR promotes atrial structural and electrical remodeling. Nonetheless, animals overexpressing the PRR do not exhibit cardiac injury. In the kidney, the PRR is involved in the development of ureteric bud branching, urine concentration, and regulation of blood pressure. There is great interest in the PRR contributions to T cell homeostasis and to the development of visceral and brown fat. In this mini-review, we discuss the evidence for the pathophysiological roles of the PRR with emphasis in CVD.

RAS Genetic Variants in Interaction with ACE Inhibitors Drugs Influences Essential Hypertension Control

BACKGROUNDS AND AIMS

Essential Hypertension (EH) is a common disorder associated with increased cardiovascular morbidity and mortality in Malaysia. To investigate how genetic polymorphisms of the renin-angiotensin-aldosterone system (RAS) influence EH control with angiotensin-converting enzyme inhibitor drugs (ACEI).

METHODS

A case-control, cross-sectional population-based nested study (n = 142) included hypertensive subjects treated with ACEI drugs, either lisinopril or enalapril (20 mg, once daily) as monotherapy for 24 weeks. In total seven possible polymorphisms of RAS genes were genotyped. The association between those polymorphisms and the changes in blood pressure were observed in the 24 week treatment.

RESULTS

Statistically significant associations of I, G, T, M and G alleles of ACE (I/D, G2350A), AGT (M235T, T175M and G-6A) respectively were observed in essential hypertensive subjects. The decrease in systolic blood pressure and diastolic blood pressure after 24 weeks of treatment of the patients carrying II, GG, and TT genotypes were greater than the groups carrying DD, AA, MM, MM and GG of I/D, G2350A, M235T, T174M and G-6A genotypes respectively. In contrast, No significant difference was observed between renin gene polymorphisms (Bg/I and MboI) and hypertensives.

CONCLUSIONS

Although this study shows a possible association of polymorphisms of RAS genes with the risk of non-control of HT in ACEI-treated patients and indicates the importance of all this system's components in regulating HT, it needs to be replicated in other data sources.

(Pro)renin receptor as a therapeutic target for the treatment of cardiovascular diseases?

The discovery of the (pro)renin receptor [(P)RR] 15years ago stimulated ideas on prorenin being more than renin's inactive precursor. Indeed, binding of prorenin to the (P)RR induces a conformational change in the prorenin molecule, allowing it to display angiotensin-generating activity, and additionally results in intracellular signaling in an angiotensin-independent manner. However, the prorenin levels required to observe these angiotensin-dependent and -independent effects of the (P)RR are many orders above its in vivo concentrations, both under normal and pathological conditions. Given this requirement, the idea that the (P)RR has a function within the renin-angiotensin system (RAS) is now being abandoned. Instead, research is now focused on the (P)RR as an accessory protein of vacuolar H⁺-ATPase (V-ATPase), potentially determining its integrity. Acting as an adaptor between Frizzled co-receptor LRP6 and V-ATPase, the (P)RR appears to be indispensable for Wnt/β-catenin signaling, thus explaining why (P)RR deletion (unlike renin deletion) is lethal even when restricted to specific cells, such as cardiomyocytes, podocytes and smooth muscle cells. Furthermore, recent studies suggest that the (P)RR may play important roles in lipoprotein metabolism and overall energy metabolism. In this review, we summarize the controversial RAS-related effects of the (P)RR, and critically review the novel non-RAS-related functions of the (P)RR, ending with a discussion on the potential of targeting the (P)RR to treat cardiovascular diseases.

Analysis of Association of Angiotensin II Type 1 Receptor Gene A1166C Gene Polymorphism with Essential Hypertension

The A/C transversion at 1166 of the angiotensin II Type 1 Receptor (AT1R) gene per se does not characterize any functional diversity but has been associated with expression of the AT1R, consequently molecular variants of the gene may modulate the possible risk of essential hypertension. The present study was performed to determine the genotypic frequency of the A1166C polymorphism of the AT1R gene in essential hypertensive patients with the aim to assess the effect of variants of this polymorphism in hypertension. AT1R gene amplification was performed by PCR and A1166C polymorphism was determined by enzyme digestion methodologies in 224 consecutively enrolled essential hypertensive patients and 257 controls. Suitable descriptive statistics was used for different variables. Results revealed that genotype and allele distribution of the A1166C variant differed significantly in hypertensives and normotensives. Allele frequency at the A1166C position was 61%A and 39%C for control and 52%A and 48%C for patients. Observed frequencies were compatible with HWE expected frequencies in cases as well as in controls. rs5186 was found to be associated with hypertension (95% CI 1.1453-2.7932, p: 0.0106). The difference remained statistically significant after the multivariate adjustment (p < 0.05), with C/C variant conferring a risk of 1.74-fold of essential hypertension. This association was confirmed by inter-genotypic variations in the mean systolic and diastolic blood pressure in patients. In conclusion, genetic variation at the AT1R gene influences the risk of hypertension stratification and might serve as a predictive marker for the susceptibility to hypertension among affected families.

ACE Phenotyping as a Guide Toward Personalized Therapy With ACE Inhibitors

Background:

Angiotensin-converting enzyme (ACE) inhibitors (ACEI) are widely used in the management of cardiovascular diseases but with significant interindividual variability in the patient’s response.

Objectives:

To investigate whether interindividual variability in the response to ACE inhibitors is explained by the “ACE phenotype”—for example, variability in plasma ACE concentration, activity, and conformation and/or the degree of ACE inhibition in each individual.

Methods:

The ACE phenotype was determined in plasma of 14 patients with hypertension treated chronically for 4 weeks with 40 mg enalapril (E) or 20 mg E + 16 mg candesartan (EC) and in 20 patients with hypertension treated acutely with a single dose (20 mg) of E with or without pretreatment with hydrochlorothiazide. The ACE phenotyping included (1) plasma ACE concentration; (2) ACE activity (with 2 substrates: Hip-His-Leu and Z-Phe-His-Leu and calculation of their ratio); (3) detection of ACE inhibitors in patient’s blood (indicator of patient compliance) and the degree of ACE inhibition (ie, adherence); and (4) ACE conformation.

Results:

Enalapril reduced systolic and diastolic blood pressure in most patients; however, 20% of patients were considered nonresponders. Chronic treatment results in 40% increase in serum ACE concentrations, with the exception of 1 patient. There was a trend toward better response to ACEI among patients who had a higher plasma ACE concentration.

Conclusion:

Due to the fact that “20% of patients do not respond to ACEI by blood pressure drop,” the initial blood ACE level could not be a predictor of blood pressure reduction in an individual patient. However, ACE phenotyping provides important information about conformational and kinetic changes in ACE of individual patients, and this could be a reason for resistance to ACE inhibitors in some nonresponders.

The prevalence of unique SNPs in the renin-angiotensin system highlights the need for pharmacogenetics in Indigenous Australians

Genetic differences between ethnic populations affect susceptibility to disease and efficacy of drugs. This study examined and compared the prevalence of single nucleotide polymorphisms (SNPs) in genes of the renin-angiotensin system (RAS) in a desert community of Indigenous Australians and in non-Indigenous Australians. The polymorphisms were angiotensinogen, AGT G-217A (rs5049); AGT G+174A (rs4762); Angiotensin II type 1 receptor, AGTR1 A+1166C (rs5186); angiotensin converting enzyme, ACE A-240T (rs4291), ACE T-93C (rs4292); renin, REN T+1142C (rs5706). They were measured using allelic discrimination assays. The prevalence of REN T+1142C SNP was similar in the two populations; 99% were homozygous for the T allele. All other SNPs were differently distributed between the two populations (P < 0.0001). In non-Indigenous Australians, the A allele at position 204 of ACE rs4291 was prevalent (61.8%) whereas in the Indigenous Australians the A allele was less prevalent (28%). For rs4292, the C allele had a prevalence of 37.9% in non-Indigenous Australians but in Indigenous Australians the prevalence was only 1%. No Indigenous individuals were homozygous for the C allele of AGTR1 (rs5186). Thus the prevalence of RAS SNPs in this Indigenous Australian desert community was different from non-Indigenous Australians as was the prevalence of cytokine SNPs (as shown in a previous study). These differences may affect susceptibility to chronic renal and cardiovascular disease and may alter the efficacy of drugs used to inhibit the RAS. These studies highlight the need to study the pharmacogenetics of drug absorption, distribution, metabolism and excretion in Indigenous Australians for safe prescribing guidelines.

The Role of the (Pro)renin Receptor in Hypertensive Disease

Tissue angiotensin generation depends on the uptake of circulating (kidney-derived) renin and/or its precursor prorenin (together denoted as (pro)renin). Since tissue renin levels are usually higher than expected based upon the amount of (renin-containing) blood in tissue, an active uptake mechanism has been proposed. The (pro)renin receptor ((P)RR), discovered in 2002, appeared a promising candidate, although its nanomolar affinity for renin/prorenin is many orders of magnitude above their levels in blood. This review discusses (P)RR-related research since its discovery. First, encouraging in vitro findings supported detrimental effects of (pro)renin-(P)RR interaction, even resulting in angiotensin-independent signaling. Moreover, the putative (P)RR blocker "handle region peptide" (HRP) yielded beneficial effects in various cardiovascular animal models. Then doubt arose whether such interaction truly occurs in vivo, and (P)RR deletion unexpectedly turned out to be lethal. Moreover, HRP results could not be confirmed. Finally, it was discovered that the (P)RR actually is a component of vacuolar-type H(+)-ATPase, a multisubunit protein found in virtually every cell type which is essential for vesicle trafficking, protein degradation, and coupled transport. Nevertheless, selective (P)RR blockade in the brain with the putative antagonist PRO20 (corresponding with the first 20 amino acids of prorenin's prosegment) reduced blood pressure in the deoxycorticosteroneacetate (DOCA)-salt model, and (P)RR gene single nucleotide polymorphisms associate with hypertension. To what degree this relates to (pro)renin remains uncertain. The concept of (P)RR blockade in hypertension, if pursued, requires rigorous testing of any newly designed antagonist, and may not hold promise given the early death of tissue-specific (P)RR knockout animals.

The C4280A (rs5705) gene polymorphism of the renin (REN) gene is associated with risk of developing coronary artery disease, but not with restenosis after coronary stenting

The aim of the present study was to evaluate the role of AGT and REN gene polymorphisms as susceptibility markers for coronary artery disease (CAD) and/or restenosis after coronary stent placement in a group of Mexican patients. Five polymorphisms of the AGT (rs699, rs4762, rs5051, rs5049, rs5046) and two of the REN (rs5707, rs5705) genes were analyzed by 5' exonuclease TaqMan genotyping assays in 240 patients with CAD who underwent coronary artery stenting (76 with restenosis and 164 without restenosis). A group of 610 individuals without clinical and familial antecedents of cardiovascular diseases were included as controls. The results showed that the distribution of AGT and REN polymorphisms were similar in patients with and without restenosis. However, when the whole group of patients (with and without restenosis) was compared to healthy controls, under co-dominant, dominant, heterozygous and additive models, the REN A4280C (rs5705) polymorphism was associated with increased risk of CAD (OR=1.76, PCo-dom=0.006, OR=1.81, PDom=0.001, OR=1.75, PHet=0.003 and OR=1.59, PAdd=0.003, respectively). All models were adjusted for age, gender, diabetes, dyslipidemia, hypertension and smoking habit. The TC haplotype of the REN gene was associated with increased risk of CAD (OR=1.53, P=0.014). The data suggest that the REN C4280A (rs5705) polymorphism plays an important role in the risk of developing CAD with the highest risk for C allele, but do not support its role as a risk factor for developing restenosis after coronary stenting.

Hypertension: renin-angiotensin-aldosterone system alterations

Blockers of the renin-angiotensin-aldosterone system (RAAS), that is, renin inhibitors, angiotensin (Ang)-converting enzyme (ACE) inhibitors, Ang II type 1 receptor antagonists, and mineralocorticoid receptor antagonists, are a cornerstone in the treatment of hypertension. How exactly they exert their effect, in particular in patients with low circulating RAAS activity, also taking into consideration the so-called Ang II/aldosterone escape that often occurs after initial blockade, is still incompletely understood. Multiple studies have tried to find parameters that predict the response to RAAS blockade, allowing a personalized treatment approach. Consequently, the question should now be answered on what basis (eg, sex, ethnicity, age, salt intake, baseline renin, ACE or aldosterone, and genetic variance) a RAAS blocker can be chosen to treat an individual patient. Are all blockers equal? Does optimal blockade imply maximum RAAS blockade, for example, by combining ≥2 RAAS blockers or by simply increasing the dose of 1 blocker? Exciting recent investigations reveal a range of unanticipated extrarenal effects of aldosterone, as well as a detailed insight in the genetic causes of primary aldosteronism, and mineralocorticoid receptor blockers have now become an important treatment option for resistant hypertension. Finally, apart from the deleterious ACE-Ang II-Ang II type 1 receptor arm, animal studies support the existence of protective aminopeptidase A-Ang III-Ang II type 2 receptor and ACE2-Ang-(1 to 7)-Mas receptor arms, paving the way for multiple new treatment options. This review provides an update about all these aspects, critically discussing the many controversies and allowing the reader to obtain a full understanding of what we currently know about RAAS alterations in hypertension.

Renin-angiotensin system phenotyping as a guidance toward personalized medicine for ACE inhibitors: can the response to ACE inhibition be predicted on the basis of plasma renin or ACE?

PURPOSE & METHODS

Not all hypertensive patients respond well to ACE inhibition. Here we determined whether renin-angiotensin system (RAS) phenotyping, i.e., the measurement of renin or ACE, can predict the individual response to RAS blockade, either chronically (enalapril vs. enalapril + candesartan) or acutely (enalapril ± hydrochlorothiazide, HCT).

RESULTS

Chronic enalapril + candesartan induced larger renin rises, but did not lower blood pressure (BP) more than enalapril. Similar observations were made for enalapril + HCT vs. enalapril when given acutely. Baseline renin predicted the peak changes in BP chronically, but not acutely. Baseline ACE levels had no predictive value. Yet, after acute drug intake, the degree of ACE inhibition, like Δrenin, did correlate with ΔBP. Only the relationship with Δrenin remained significant after chronic RAS blockade. Thus, a high degree of ACE inhibition and a steep renin rise associate with larger acute responses to enalapril. However, variation was large, ranging >50 mm Hg for a given degree of ACE inhibition or Δrenin. The same was true for the relationships between Δrenin and ΔBP, and between baseline renin and the maximum reduction in BP in the chronic study.

CONCLUSIONS

Our data do not support that RAS phenotyping will help to predict the individual BP response to RAS blockade. Notably, these conclusions were reached in a carefully characterized, homogenous population, and when taking into account the known fluctuations in renin that relate to gender, age, ethnicity, salt intake and diuretic treatment, it seems unlikely that a cut-off renin level can be defined that has predictive value.

(Pro)renin receptor and V-ATPase: from Drosophila to humans

A decade ago, the (P)RR [(pro)renin receptor] was discovered and depicted as a potential activator of the tissue renin-angiotensin system. For this reason, the role of the (P)RR in cardiovascular diseases and diabetes has been particularly studied. However, the discovery of embryonic lethality after (P)RR gene deletion in mouse and zebrafish paved the way for additional roles of (P)RR in cell homoeostasis. Indeed, the (P)RR has been shown to associate with vacuolar H+-ATPase, hence its other name ATP6ap2. Developmental studies in Xenopus and Drosophila have revealed an essential role of this association to promote the canonical and non-canonical Wnt signalling pathways, whereas studies with tissue-specific gene deletion have pointed out a role in autophagy. The present review aims to summarize recent findings on the cellular functions of (P)RR emerging from various mutated and transgenic animal models.

Effect of NR3C2 genetic polymorphisms on the blood pressure response to enalapril treatment

AIM

The mineralocorticoid receptor (MR; also known as NR3C2) plays important roles in the modulation of blood pressure. The effect of NR3C2 polymorphisms on antihypertensive response to enalapril was investigated.

PATIENTS & METHODS

Two hundred and seventy nine essential hypertension patients treated with enalapril were genotyped for two NR3C2 tagSNPs, rs5522 and rs2070950, by Sequenom MassArray™ technology.

RESULTS

The reductions in diastolic blood pressure (DBP) were significantly greater in AA homozygotes compared with AG+GG genotype carriers for the rs5522 polymorphism (p = 0.009), and the reductions in DBP were greater in GG homozygotes compared with GC+CC genotype carriers for the rs2070950 polymorphism, with marginal significance (p = 0.065). Stepwise multiple regression analysis indicated that significant predictors of DBP reduction were baseline DBP (p < 0.001), waist:hip ratio (p = 0.001) and rs5522 genotype (p = 0.003).

CONCLUSION

NR3C2 rs5522 affects blood pressure response to enalapril treatment and may serve as a useful pharmacogenomic marker of antihypertensive response to enalapril in essential hypertension patients.

Genetic manipulation and genetic variation of the kallikrein-kinin system: impact on cardiovascular and renal diseases

Genetic manipulation of the kallikrein-kinin system (KKS) in mice, with either gain or loss of function, and study of human genetic variability in KKS components which has been well documented at the phenotypic and genomic level, have allowed recognizing the physiological role of KKS in health and in disease. This role has been especially documented in the cardiovascular system and the kidney. Kinins are produced at slow rate in most organs in resting condition and/or inactivated quickly. Yet the KKS is involved in arterial function and in renal tubular function. In several pathological situations, kinin production increases, kinin receptor synthesis is upregulated, and kinins play an important role, whether beneficial or detrimental, in disease outcome. In the setting of ischemic, diabetic or hemodynamic aggression, kinin release by tissue kallikrein protects against organ damage, through B2 and/or B1 bradykinin receptor activation, depending on organ and disease. This has been well documented for the ischemic or diabetic heart, kidney and skeletal muscle, where KKS activity reduces oxidative stress, limits necrosis or fibrosis and promotes angiogenesis. On the other hand, in some pathological situations where plasma prekallikrein is inappropriately activated, excess kinin release in local or systemic circulation is detrimental, through oedema or hypotension. Putative therapeutic application of these clinical and experimental findings through current pharmacological development is discussed in the chapter.

Genetic variation-optimized treatment benefit of angiotensin-converting enzyme inhibitors in patients with stable coronary artery disease: a 12-year follow-up study

OBJECTIVES

The objective of this study was to examine the relationship between renin-angiotensin system genotypes and the pharmacogenetics of angiotensin-converting enzyme (ACE) inhibitors in Chinese patients with coronary artery disease (CAD).

METHODS

Patients with angiographic CAD were recruited from 1995 to 2003. The baseline characteristics and genetic polymorphisms [ACE gene insertion/deletion (I/D) polymorphisms, six polymorphisms of the angiotensinogen (AGT) gene, and A-1166C polymorphisms of the angiotensin-II type I receptor gene (AGT1R)] were established. Patients were divided into two groups (ACE inhibitor or no ACE inhibitor) and followed for up to 12 years. Kaplan-Meier curves and Cox regression models were used to determine the survival and major cardiovascular events (MACE) event-free survival trends. Pharmacogenetic effects were determined by several Cox regression models.

RESULTS

Of the 784 patients, 432 were treated with ACE inhibitors and 352 were not. ACE inhibitors were associated with a lower MACE rate at 4000 days. In addition, the ACE I/D gene D and AGT1R gene C alleles were associated with a higher MACE rate on the basis of a multivariate regression analysis. This effect was attenuated by the pharmacogenetic interaction of ACE inhibitors and the ACE gene (ACE inhibitors* ACE gene, hazard ratio: 0.8, 95% confidence interval: 0.62-0.94, P=0.03).

CONCLUSIONS

ACE inhibitors were associated with a significant decrease in MACE in Chinese patients diagnosed with CAD. Genetic variants were also associated with event-free survival, but their effects were modified by the use of ACE inhibitors.

Renin-angiotensin system, hypertension, and chronic kidney disease: pharmacogenetic implications

About 80% of CKD (chronic kidney disease) patients are hypertensive, and kidney function and blood pressure are clearly related to both physiologic and pathologic conditions in a "vicious cycle". In this pathologic scenario, there is a renin-angiotensin system (RAS) hyperactivity associated to progression of renal damage. Current guidelines indicate as the first choice of antihypertensive intervention, the pharmacologic blockade of the RAS. Nonetheless, both response to treatment and renal protection have considerable inter-individual variability. The main aims of this review are to describe the genetic characteristics of RAS components and to identify the possible pharmacogenetic implications for RAS-blocker drugs in the hypertension-CKD scenario. To date, RAS polymorphisms have not been consistently associated to antihypertensive response and studies focusing on CKD are scarce. Nonetheless, pharmacogenetic studies for the RAS-blocker drugs could still be further explored, especially with new generation tools and focusing not only on the antihypertensive response, but also on renal protection as well.

Genetic influences of angiotensin-converting enzyme inhibitor response: an opportunity for personalizing therapy?

The angiotensin-converting enzyme (ACE) inhibitors are a cornerstone drug therapy in the current treatment of patients with hypertension, stable coronary artery disease and heart failure. Individualizing therapy of ACE inhibitors with clinical risk factors in low-risk patients with stable coronary artery disease is not feasible. The concept of pharmacogenetics, by studying patient factors more individually, offers a first glimpse in the quest for the 'holy grail' of personalized medicine. As such, genetic targets in the direct pharmacodynamic pathway of ACE inhibitors, the renin-angiotensin-aldosterone system, is a plausible candidate for such an approach. In the past few decades, results of pharmacogenetic studies were scarce and inconsistent. However, recently the first reports of larger pharmacogenetic studies are now confirming that the 'pharmacogenetic approach' might be feasible in the future. The current review focuses on the recent developments in pharmacogenetic research in response to ACE inhibitors in patients with stable coronary artery disease.

Genome-wide identification of structural variants in genes encoding drug targets: possible implications for individualized drug therapy

OBJECTIVE

The objective of the present study was to identify structural variants of drug target-encoding genes on a genome-wide scale. We also aimed at identifying drugs that are potentially amenable for individualization of treatments based on knowledge about structural variation in the genes encoding their targets.

METHODS

Information about human drug targets of all therapeutic drugs and nutraceuticals approved by the Food and Drug Administration and with an Anatomical Therapeutic Chemical (ATC) code, namely, 876, was obtained from the DrugBank and applied to interrogate the Database of Genomic Variants.

RESULTS

We identified 1721 structural variants, which affected 495 of 1005 different genes encoding drug targets. About 70% of the Food and Drug Administration-approved drugs had targets subjected to structural variation, in particular copy number variation. The distribution of drugs with targets encoded by copy number variable genes differed between ATC groups with pronounced over-representation in ATC group N, that is, nervous system drugs (P=3.75e-5). Several narrow therapeutic index drugs with targets subjected to genomic structural variation were identified. Information about the frequencies of the structural variants and drug consumption allowed us to identify potential candidates for implementation in pharmacogenetic testing and individualized drug treatments.

CONCLUSION

Structural variants in pharmacodynamic genes may play a larger role in determining individual variation in drug responses than currently believed. Inclusion of such genes in pharmacogenetic testing holds promising prospects as they may have large effect sizes.

Plasma levels of prorenin and renin in blacks and whites: their relative abundance and associations with plasma aldosterone concentration

BACKGROUND

All renin arises from prorenin. The proportion of renin relative to prorenin could influence overall renin-angiotensin-aldosterone activity. We sought to determine whether prorenin levels were related to extracellular volume, as reflected by the levels of plasma renin activity (PRA), and to aldosterone.

METHODS

We analyzed plasma levels of prorenin, renin, and aldosterone, as well as their interactions, in 129 young blacks and whites.

RESULTS

Blacks had lower plasma renin concentration (PRC) and PRA, but had prorenin levels similar to whites (69 pg/ml in blacks vs. 62 pg/ml in whites, P = 0.41). As a result, the renin-to-total renin ratio was significantly lower in blacks (11.5% in blacks as compared to 19.8% in whites; P = 0.0001). Because prorenin also resides in tissues including the adrenal where it can bind to a specific receptor to generate angiotensin II, we examined the relationship of prorenin levels to plasma aldosterone concentrations (PAC). While a positive association between PRC and PAC was found in both blacks and whites, PAC was positively related to prorenin in whites (P = 0.04) but negatively in blacks, an observation that we hypothesize was due to reduced prorenin-to-renin conversion in blacks.

CONCLUSIONS

We observed a disproportionately high level of prorenin in blacks. These high circulating prorenin levels however do not result in greater adrenal angiotensin II and aldosterone production in healthy young blacks.

Clinical and molecular approaches to individualize antihypertensive drug therapy

Interindividual variation of blood pressure (BP) responses to antihypertensive drugs is extensive. Several clinical, laboratory, and genetic predictors of BP responses to blood pressure-lowering agents have been suggested. We describe here the principal findings from the GENRES Study which is primarily a pharmacogenetic study of antihypertensive drug responses but also includes analysis of certain clinical and laboratory predictors. In this placebo-controlled, double-blinded, and randomized study, more than 200 male subjects with essential hypertension were treated with four antihypertensive drug monotherapies (amlodipine, bisoprolol, hydrochlorothiazide, and losartan) in a cross-over fashion, resulting in more than 800 treatment periods. Generally, placebo BP level was the best predictor of BP responses. In addition, higher baseline plasma renin activity predicted better BP response to losartan and bisoprolol, and weaker response to hydrochlorothiazide. A number of candidate gene polymorphisms analysed so far have given negative results in relation to BP responses, with the exception of an STK39 variant associating with losartan responsiveness. In future, genome-wide association studies on antihypertensive pharmacogenetics may identify novel pathways of BP regulation and provide new tools for both basic research and clinical use.

The role of renin-angiotensin-aldosterone system polymorphisms in phenotypic expression of MYBPC3-related hypertrophic cardiomyopathy

The phenotypic variability of hypertrophic cardiomyopathy (HCM) in patients with identical pathogenic mutations suggests additional modifiers. In view of the regulatory role in cardiac function, blood pressure, and electrolyte homeostasis, polymorphisms in the renin-angiotensin-aldosterone system (RAAS) are candidates for modifying phenotypic expression. In order to investigate whether RAAS polymorphisms modulate HCM phenotype, we selected a large cohort of carriers of one of the three functionally equivalent truncating mutations in the MYBPC3 gene. Family-based association analysis was performed to analyze the effects of five candidate RAAS polymorphisms (ACE, rs4646994; AGTR1, rs5186; CMA, rs1800875; AGT, rs699; CYP11B2, rs1799998) in 368 subjects carrying one of the three mutations in the MYBPC3 gene. Interventricular septum (IVS) thickness and Wigle score were assessed by 2D-echocardiography. SNPs in the RAAS system were analyzed separately and combined as a pro-left ventricular hypertrophy (LVH) score for effects on the HCM phenotype. Analyzing the five polymorphisms separately for effects on IVS thickness and Wigle score detected two modest associations. Carriers of the CC genotype in the AGT gene had less pronounced IVS thickness compared with CT and TT genotype carriers. The DD polymorphism in the ACE gene was associated with a high Wigle score (P=0.01). No association was detected between the pro-LVH score and IVS thickness or Wigle score. In conclusion, in contrast to previous studies, in our large study population of HCM patients with functionally equivalent mutations in the MYBPC3 gene we did not find major effects of genetic variation within the genes of the RAAS system on phenotypic expression of HCM.

The (pro)renin receptor. A decade of research: what have we learned?

The discovery of a (pro)renin receptor ((P)RR) in 2002 provided a long-sought explanation for tissue renin–angiotensin system (RAS) activity and a function for circulating prorenin, the inactive precursor of renin, in end-organ damage. Binding of renin and prorenin (referred to as (pro)renin) to the (P)RR increases angiotensin I formation and induces intracellular signalling, resulting in the production of profibrotic factors. However, the (pro)renin concentrations required for intracellular signalling in vitro are several orders of magnitude above (patho)physiological plasma levels. Moreover, the phenotype of prorenin-overexpressing animals could be completely attributed to angiotensin generation, possibly even without the need for a receptor. The efficacy of the only available putative (pro)renin receptor blocker handle region peptide remains doubtful, leading to inconclusive results. The fact that, in contrast to other RAS components, (P)RR knock-outs, even tissue-specific, are lethal, points to an important, (pro)renin-independent, function of the (P)RR. Indeed, recent research has highlighted ancillary functions of the (P)RR as an essential accessory protein of the vacuolar-type H⁺-ATPase (V-ATPase), and in this role, it acts as an intermediate in Wnt signalling independent of (pro)renin. In conclusion, (pro)renin-dependent signalling is unlikely in non-(pro)renin synthesizing organs, and the (P)RR role in V-ATPase integrity and Wnt signalling may explain some, if not all of the phenotypes previously associated with (pro)renin-(P)RR interaction.

Individualised therapy of angiotensin converting enzyme (ACE) inhibitors in stable coronary artery disease: overview of the primary results of the PERindopril GENEtic association (PERGENE) study

In patients with stable coronary artery disease (CAD) without overt heart failure, ACE inhibitors are among the most commonly used drugs as these agents have been proven effective in reducing the risk of cardiovascular events. Considerable individual variations in the blood pressure response to ACE inhibitors are observed and as such heterogeneity in clinical treatment effect would be likely as well. Assessing the consistency of treatment benefit is essential for the rational and cost-effective prescription of ACE inhibitors. Information on heterogeneities in treatment effect between subgroups of patients could be used to develop an evidence-based guidance for the installation of ACE-inhibitor therapy. Obviously, therapy should only be applied in those patients who most likely will benefit. Attempts to develop such treatment guidance by using clinical characteristics have been unsuccessful. No heterogeneity in risk reduction by ACE inhibitors has been observed in relation to relevant clinical characteristics. A new approach to such 'guided-therapy' could be to integrate more patient-specific characteristics such as the patients' genetic information. If proven feasible, pharmacogenetic profiling could optimise patients' benefit of treatment and reduce unnecessary treatment of patients. Cardiovascular pharmacogenetic research of ACE inhibitors in coronary artery disease patients is in a formative stage and studies are limited. The PERGENE study is a large pharmacogenetic substudy of the EUROPA trial, aimed to assess the achievability of pharmacogenetic profiling. We provide an overview of the main results of the PERGENE study in terms of the genetic determinants of treatment benefit and blood pressure response. The main results of the PERGENE study show a pharmacogenetic profile related to the treatment benefit of perindopril identifying responders and non-responders to treatment.

Association of angiotensin II type 1-receptor gene polymorphisms with the risk of developing hypertension in Mexican individuals

INTRODUCTION

Hypertension is a complex disease in which a significant interaction between genetic and environmental factors takes place. The renin-angiotensin system plays an important role regulating blood pressure to maintain homeostasis and vascular tone. In the present work, the role of angiotensin II type 1-receptor (AGTR1) gene polymorphisms as susceptibility markers for hypertension was evaluated.

MATERIALS AND METHODS

Five polymorphisms in the AGTR1 gene were genotyped by 5' exonuclease TaqMan genotyping assays in 239 hypertensive and 371 non-hypertensive individuals.

RESULTS

A similar distribution of rs275651, rs275652, rs275653, and rs5183 polymorphisms was observed in both studied groups. Different distribution of rs5182 genotypes was observed between the studied groups (p = 0.016). According to the co-dominant model, individuals with rs5182 CC genotype have a 1.83-fold increased risk of developing hypertension (p = 0.009). Polymorphisms were distributed in two blocks: block 1 included the rs275651, rs275652, and rs275653 polymorphisms, whereas block 2 included the rs5183 and rs5182 polymorphisms. Individuals with hypertension showed increased frequency of 'CA' haplotype of block 2 when compared to non-hypertensive individuals (p = 0.015, odds ratio = 1.33).

CONCLUSION

The results suggest that the rs5182 gene polymorphism could be involved in the risk of developing hypertension in Mexican individuals.