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Role of the ACE2/Angiotensin 1-7 Axis of the Renin-Angiotensin System in Heart Failure.

ABSTRACT: Heart failure (HF) remains the most common cause of death and disability, and a major economic burden, in industrialized nations. Physiological, pharmacological, and clinical studies have demonstrated that activation of the renin-angiotensin system is a key mediator of HF progression. Angiotensin-converting enzyme 2 (ACE2), a homolog of ACE, is a monocarboxypeptidase that converts angiotensin II into angiotensin 1-7 (Ang 1-7) which, by virtue of its actions on the Mas receptor, opposes the molecular and cellular effects of angiotensin II. ACE2 is widely expressed in cardiomyocytes, cardiofibroblasts, and coronary endothelial cells. Recent preclinical translational studies confirmed a critical counter-regulatory role of ACE2/Ang 1-7 axis on the activated renin-angiotensin system that results in HF with preserved ejection fraction. Although loss of ACE2 enhances susceptibility to HF, increasing ACE2 level prevents and reverses the HF phenotype. ACE2 and Ang 1-7 have emerged as a key protective pathway against HF with reduced and preserved ejection fraction. Recombinant human ACE2 has been tested in phase I and II clinical trials without adverse effects while lowering and increasing plasma angiotensin II and Ang 1-7 levels, respectively. This review discusses the transcriptional and post-transcriptional regulation of ACE2 and the role of the ACE2/Ang 1-7 axis in cardiac physiology and in the pathophysiology of HF. The pharmacological and therapeutic potential of enhancing ACE2/Ang 1-7 action as a novel therapy for HF is highlighted.

SUBMITTER: Patel VB

PROVIDER: S-EPMC4939482 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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Role of the ACE2/Angiotensin 1-7 Axis of the Renin-Angiotensin System in Heart Failure.

Patel Vaibhav B VB Zhong Jiu-Chang JC Grant Maria B MB Oudit Gavin Y GY

Circulation research 20160401 8

Heart failure (HF) remains the most common cause of death and disability, and a major economic burden, in industrialized nations. Physiological, pharmacological, and clinical studies have demonstrated that activation of the renin-angiotensin system is a key mediator of HF progression. Angiotensin-converting enzyme 2 (ACE2), a homolog of ACE, is a monocarboxypeptidase that converts angiotensin II into angiotensin 1-7 (Ang 1-7) which, by virtue of its actions on the Mas receptor, opposes the molec ...[more]

PMID: 27081112

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Project description:ObjectivesThe purpose of this study was to assess the relationship between biomarkers of renin-angiotensin-aldosterone system (RAAS) activation and decongestion strategies, worsening renal function, and clinical outcomes.BackgroundHigh-dose diuretic therapy in patients with acute heart failure (AHF) is thought to activate the RAAS; and alternative decongestion strategies, such as ultrafiltration (UF), have been proposed to mitigate this RAAS activation.MethodsThis study analyzed 427 AHF patients enrolled in the DOSE-AHF (Diuretic Optimization Strategies in Acute Heart Failure) and CARRESS-HF (Cardiorenal Rescue Study in Acute Decompensated Heart Failure) trials. We assessed the relationship between 2 markers of RAAS activation (plasma renin activity [PRA] and aldosterone) from baseline to 72 h and 96 h and decongestion strategy: high- versus low-dose and continuous infusion versus bolus furosemide for DOSE-AHF and UF versus stepped pharmacologic care for CARRESS-HF. We determined the relationships between RAAS biomarkers and 60-day outcomes.ResultsPatients with greater RAAS activation at baseline had lower blood pressures, lower serum sodium levels, and higher blood urea nitrogen (BUN) concentration. Continuous infusion furosemide and UF were associated with greater PRA increases (median: +1.66 vs. +0.66 ng/ml/h with continuous vs. bolus infusion, respectively, p = 0.021; +4.05 vs. +0.56 ng/ml/h with UF vs. stepped care, respectively, p = 0.014). There were no significant differences in RAAS biomarker changes with high- versus low-dose diuretic therapy (both: p > 0.5). Neither baseline log PRA nor log aldosterone was associated with increased death or HF hospitalization (hazard ratio [HR] for a doubling of 1.05; 95% confidence interval [CI]: 0.98 to 1.13; p = 0.18; and HR: 1.13; 95% CI: 0.99 to 1.28; p = 0.069, respectively). The change in RAAS biomarkers from baseline to 72 and 96 h was not associated with outcomes (both: p > 0.5).ConclusionsHigh-dose loop diuretic therapy did not result in RAAS activation greater than that with low-dose diuretic therapy. UF resulted in greater PRA increase than stepped pharmacologic care. Neither PRA nor aldosterone was significantly associated with short-term outcomes in this cohort. (Determining Optimal Dose and Duration of Diuretic Treatment in People With Acute Heart Failure [DOSE-AHF]; NCT00577135; Effectiveness of Ultrafiltration in Treating People With Acute Decompensated Heart Failure and Cardiorenal Syndrome [CARRESS]; NCT00608491).

Project description:Rationale & objectiveHeart failure treatment relies on loop diuretics to induce natriuresis and decongestion, but the therapy is often limited by diuretic resistance. We explored the association of renin-angiotensin-aldosterone system (RAAS) activation with diuretic response.Study designObservational cohort.Setting & populationEuvolemic ambulatory adults with chronic heart failure were administered torsemide in a monitored environment.PredictorsPlasma total renin, active renin, angiotensinogen, and aldosterone levels. Urine total renin and angiotensinogen levels.OutcomesSodium output per doubling of diuretic dose and fractional excretion of sodium per doubling of diuretic dose.Analytical approachRobust linear regression models estimated the associations of each RAAS intermediate with outcomes.ResultsThe analysis included 56 participants, and the median age was 65 years; 50% were women, and 41% were Black. The median home diuretic dose was 80-mg furosemide equivalents. In unadjusted and multivariable-adjusted models, higher levels of RAAS measures were generally associated with lower diuretic efficiency. Higher plasma total renin remained significantly associated with lower sodium output per doubling of diuretic dose (β = -0.41 [-0.76, -0.059] per SD change) with adjustment; higher plasma total and active renin were significantly associated with lower fractional excretion of sodium per doubling of diuretic dose (β = -0.48 [-0.83, -0.14] and β = -0.51 [-0.95, -0.08], respectively) in adjusted models. Stratification by RAAS inhibitor use did not substantially alter these associations.LimitationsSmall sample size; highly selected participants; associations may not be causal.ConclusionsAmong multiple measures of RAAS activation, higher plasma total and active renin levels were consistently associated with lower diuretic response. These findings highlight the potential drivers of diuretic resistance and underscore the need for high-quality trials of decongestive therapy enhanced by RAAS blockade.

Project description:An activated renin-angiotensin system (RAS) within the central nervous system has been implicated in sympathoexcitation during various disease conditions including congestive heart failure (CHF). In particular, activation of the RAS in the paraventricular nucleus (PVN) of the hypothalamus has been recognized to augment sympathoexcitation in CHF. We observed a 2.6-fold increase in angiotensinogen (AGT) in the PVN of CHF. To elucidate the molecular mechanism for increased expression of AGT, we performed in silico analysis of the 3'-untranslated region (3'-UTR) of AGT and found a potential binding site for microRNA (miR)-133a. We hypothesized that decreased miR-133a might contribute to increased AGT in the PVN of CHF rats. Overexpression of miR-133a in NG108 cells resulted in 1.4- and 1.5-fold decreases in AGT and angiotensin type II (ANG II) type 1 receptor (AT1R) mRNA levels, respectively. A luciferase reporter assay performed on NG108 cells confirmed miR-133a binding to the 3'-UTR of AGT. Consistent with these in vitro data, we observed a 1.9-fold decrease in miR-133a expression with a concomitant increase in AGT and AT1R expression within the PVN of CHF rats. Furthermore, restoring the levels of miR-133a within the PVN of CHF rats with viral transduction resulted in a significant reduction of AGT (1.4-fold) and AT1R (1.5-fold) levels with a concomitant decrease in basal renal sympathetic nerve activity (RSNA). Restoration of miR-133a also abrogated the enhanced RSNA responses to microinjected ANG II within the PVN of CHF rats. These results reveal a novel and potentially unique role for miR-133a in the regulation of ANG II within the PVN of CHF rats, which may potentially contribute to the commonly observed sympathoexcitation in CHF.NEW & NOTEWORTHY Angiotensinogen (AGT) expression is upregulated in the paraventricular nucleus of the hypothalamus through posttranscriptional mechanism interceded by microRNA-133a in heart failure. Understanding the mechanism of increased expression of AGT in pathological conditions leading to increased sympathoexcitation may provide the basis for the possible development of new therapeutic agents with enhanced specificity.

Project description:WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: The progression and pharmacological response of heart failure-affected patients are subject to interindividual variability. It is also acknowledged that the genotype frequency of certain gene polymorphisms varies across different ethnic groups and that a difference in gene polymorphism frequencies between healthy and heart failure patients seems to exist. WHAT THIS STUDY ADDS: This study investigated associations between 10 gene polymorphisms of RAAS-related genes with an individual's susceptibility to heart failure. Our data suggest that the angiotensinogen (AGT) 235 single nucleotide polymorphism (SNP) may be associated with heart failure in our population and that the AGT(M174)-AGT(T235) haplotype, as well as the AGT/angiotensin-converting enzyme (ACE) gene combination, may play an important role in disease predisposition. AIMS: Racial differences in survival outcomes point towards a genetic role in the pathophysiology of heart failure. Furthermore, contemporary evidence links genetics to heart failure (HF) predisposition. We tested for a difference in prevalence of 10 renin-angiotensin-aldosterone system (RAAS)-related gene polymorphisms between a homogenous population of HF patients and healthy controls. METHODS: One hundred and eleven healthy volunteers and 58 HF patients were included in this study. The healthy control group consisted of males aged between 18 and 35 years old. The HF group consisted of patients (89.7% male) who were 63.8 +/- 7.9 years old, were in New York Heart Association (NYHA) class II-III and had a documented left ventricular ejection fraction (LVEF) <or= 40% within the previous 6 months. Despite being treated maximally for their condition with angiotensin-converting-enzyme (ACE)-inhibitors and beta-adrenoceptor blockers, they continued to be symptomatic and, as such, were a highly specialized and homogeneous patient population. Both groups were composed of Canadian Caucasians. The analyzed polymorphisms were: ACE (I/D), angiotensin-II-receptor-type-1 (AGTR1)(A1166C), angiotensinogen (AGT)(M235T and T174M), endothelial-nitric-oxide-synthase (eNOS)(T-786C and Glu298Asp), adrenergic-receptor-â2 (ADRB2)(Gln27Glu), bradykinin-receptor-beta2 (BDKRB2)(+9/-9), aldosterone-synthase (CYP11B2)(T-344C) and adducin-1 (ADD1)(Gly460Trp). RESULTS The AGT (T235) allele (P = 0.0025, OR 2.02, 95% CI 1.24, 3.30) was found to be more prevalent in our HF group. The AGT (174M)-AGT (235T) haplotype was also associated with the HF phenotype (P = 0.0069). Exploratory evaluation of gene-gene combinations revealed an indicative association of the AGT (T235)/ACE(D) combined polymorphisms in the HF group (P = 0.02, OR 2.12, 95% CI 1.11, 4.06). CONCLUSIONS: This study demonstrates that the SNPs of AGT may be associated with HF in our population and that the AGT/ACE gene combination may play an important role in disease predisposition.

Dataset Information

Role of the ACE2/Angiotensin 1-7 Axis of the Renin-Angiotensin System in Heart Failure.

Publications

Role of the ACE2/Angiotensin 1-7 Axis of the Renin-Angiotensin System in Heart Failure.

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