Can angiotensin II type 2 receptors have deleterious effects in cardiovascular disease? Implications for therapeutic blockade of the renin-angiotensin system

The Safety and Efficacy of the Early Use of Sacubitril/Valsartan After Acute Myocardial Infarction: A Meta-Analysis of Randomized Controlled Trials

Acute myocardial infarction (AMI) is a significant global cause of mortality, necessitating the exploration of innovative treatments against the condition. Angiotensin receptor blockers (ARBs), angiotensin-converting enzyme inhibitors (ACEIs), and angiotensin receptor-neprilysin inhibitors (ARNIs) such as sacubitril/valsartan have demonstrated promise in managing acute heart failure (HF). However, despite favorable evidence from clinical trials for the use of sacubitril/valsartan in AMI, its overall efficacy remains a subject of debate. Hence, we conducted this review and meta-analysis, by adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and aligned with European Society of Cardiology recommendations, to compare sacubitril/valsartan with traditional ACEI/ARB treatments for AMI. We employed Review Manager 5.4 for statistical analysis, the Risk of Bias Tool 2.0 was utilized for quality assessment, and publication bias was assessed using a funnel plot. A p-value <0.05 was considered statistically significant. Eight randomized controlled trials (RCTs) were included in this meta-analysis. Our findings revealed that participants treated with sacubitril experienced significantly improved outcomes in terms of HF (OR=0.79; 95% CI: 0.66-0.95; p=0.01; I2=23%), N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (MD = -1.58; 95% CI: -1.78 to -1.37, p<0.00001; I2=97%), and major adverse cardiovascular events (MACE) (OR=0.84; 95% CI: 0.72-0.99; p=0.03; I2=44%). However, left ventricular ejection fraction (LVEF) (MD=3.68; 95% CI: 3.35-4.01, p<0.00001; I2=71%) showed greater improvement in the control group compared to the experimental group. Our meta-analysis suggests that sacubitril offers a favorable balance between safety and effectiveness. Sacubitril significantly improved outcomes in terms of HF, MACE, and NT-proBNP levels when compared to the control group. However, improvement in LVEF was notably higher in the control group over the sacubitril/valsartan group.

Evaluation of the stopping angiotensin converting enzyme inhibitor compared to angiotensin receptor blocker (STOP ACEi trial) in advanced and progressive chronic kidney disease

In the STOP-ACEi trial, the outcome was similar whether or not renin-angiotensin system inhibitors (RASi) were discontinued. We now investigate whether the effect of withdrawing angiotensin converting enzyme inhibitors (ACEi) or angiotensin-receptor blockers (ARBs) differed. In this open label trial patients with estimated glomerular filtration rates (eGFR) under 30ml/min per 1.73 m2 and progressive chronic kidney disease (CKD) were randomized to stop or continue RASi. The primary outcome was eGFR at three years. The composite of kidney failure, over 50% fall in eGFR, or kidney replacement therapy (KRT) was also assessed. Of patients randomized, 99 stopped and 123 patients continued ACEi while 104 stopped and 77 continued ARB at baseline. At three years, the eGFR was similar whether or not patients were withdrawn from ACEi or from ARB. Kidney failure or initiation of KRT occurred in 65% of those stopping and 54% continuing ACEi (hazard ratio if stopped, 1.52; 95% Confidence Interval, 1.07 to 2.16) and in 60% on an ARB regardless of randomized group (hazard ratio if stopped, 1.23; 0.83 to 1.81). Kidney failure/Initiation of KRT with over 50% decline in eGFR occurred in 71% of those stopping and 59% continuing ACEi (relative risk if stopped, 1.19; 95% CI, 1.00 to 1.41) and in 65% stopping and 69% continuing ARB (relative risk if stopped, 0.96; 0.79 to 1.16). Thus, neither discontinuing ACEi nor ARB slowed the rate of decline in eGFR. Although discontinuation of ACEi appeared to have more unfavorable effects on kidney outcomes than stopping ARB, the trial was neither designed nor powered to show differences between agents.

Renin-Angiotensin-Aldosterone System Inhibitions and Cardiovascular Outcomes in Acute Myocardial Infarction With Renal Impairment

OBJECTIVE

To compare the clinical outcomes of patients with acute myocardial infarction with renal impairment (AMI-RI) treated with either angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) in real-world clinical settings.

PATIENTS AND METHODS

A total of 4790 consecutive patients with AMI-RI between November 1, 2011, and December 31, 2015, were subdivided into ACEI (n=2845) and ARB (n=1945) treatment groups. The primary end points were major adverse cardiac and cerebrovascular events, including all-cause mortality, nonfatal myocardial infarction, any revascularization, cerebrovascular accident, rehospitalization, and stent thrombosis. Propensity score matching (PSM) was used to adjust for group differences.

RESULTS

The ARB group had a significantly higher incidence of major adverse cardiac and cerebrovascular events (at 3-year follow-up) than the ACEI group according to the unadjusted analysis (3-year hazard ratio [HR], 1.60; 95% CI, 1.43 to 1.78) and the PSM-adjusted analysis (3-year HR, 1.34; 95% CI, 1.15 to 1.56). However, any revascularization (3-year HR, 1.21; 95% CI, 0.95 to 1.54) and rehospitalization (3-year HR, 1.21; 95% CI, 0.88 to 1.67) were not significantly different between groups in the PSM-adjusted analysis. Compared with the ARB group, the ACEI group had lower rates of all-cause mortality at estimated glomerular filtration rates of at least 15 or less than 90 mL/min/1.73 m2 in the unadjusted data and at least 60 or less than 90 mL/min/1.73 m2 in the PSM-adjusted analysis.

CONCLUSION

Treatment with ACEIs seemed to be more beneficial than treatment with ARBs for patients with AMI-RI; further prospective studies are required to confirm these results.

Angiotensin Regulation of Vascular Homeostasis: Exploring the Role of ROS and RAS Blockers

Extensive research has been conducted to elucidate and substantiate the crucial role of the Renin-Angiotensin System (RAS) in the pathogenesis of hypertension, cardiovascular disorders, and renal diseases. Furthermore, the role of oxidative stress in maintaining vascular balance has been well established. It has been observed that many of the cellular effects induced by Angiotensin II (Ang II) are facilitated by reactive oxygen species (ROS) produced by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. In this paper, we present a comprehensive overview of the role of ROS in the physiology of human blood vessels, specifically focusing on its interaction with RAS. Moreover, we delve into the mechanisms by which clinical interventions targeting RAS influence redox signaling in the vascular wall.

Alterations in Renin-Angiotensin System (RAS) Peptide Levels in Patients with HIV

Chronic HIV infection has long been associated with an increased risk for cardiovascular diseases. The metabolites of the renin−angiotensin system (RAS) such as angiotensin II (AngII) play an important role in regulating blood pressure and fluid dynamics. Cross-sectional analysis of HIV-positive individuals (n = 71, age > 40 years, stable ART > 3 months with HIV viral load < 50 copies/mL) were compared to a similar HIV seronegative group (n = 72). High-resolution B-mode ultrasound images of the right carotid bifurcation (RBIF) and right common carotid artery (RCCA) were conducted to measure the extent of carotid atherosclerotic vascular disease. Plasma RAS peptide levels were quantified using a liquid chromatography-mass spectrometry-based metabolomics assay. RAS peptide concentrations were compared between persons with HIV and persons without HIV, correlating their association with clinical and cardiac measures. Median precursor peptides (Ang(1-12) and AngI) were significantly higher in the HIV-positive group compared to the HIV-negative. Analyses of the patient subgroup not on antihypertensive medication revealed circulating levels of AngII to be four-fold higher in the HIV-positive subgroup. AngII and TNF-alpha levels were found to have a positive association with RCCA, and AngI/Ang(1-12) ratio and TNF-alpha levels were found to have a positive association with RBIF. In both predictive models, AngIII had a negative association with either RCCA or RBIF, which may be attributed to its ability to bind onto AT2R and thus oppose pro-inflammatory events. These results reveal systemic alterations in RAS as a result of chronic HIV infection, which may lead to the activation of inflammatory pathways associated with carotid thickening. RAS peptide levels and cytokine markers were associated with RCCA and RBIF measurements.

Walnut supplementation after fructose-rich diet is associated with a beneficial fatty acid ratio and increased ACE2 expression in the rat heart

Increased fructose consumption has been linked with chronic inflammation and metabolic syndrome (MetS). Activation of the renin-angiotensin system (RAS) and NF-κB have been detected in MetS. Walnuts are a rich source of polyunsaturated omega-3 fatty acids (n-3 PUFA) that were suggested to exert anti-inflammatory effects related to cardio-metabolic health. We hypothesized that walnut supplementation has the capacity to revert unfavorable fructose-rich diet (FRD)-induced activation of cardiac RAS and NF-κB in male rats. Due to the lack of similar studies, we investigated the effects of walnut supplementation (6 weeks) on the expression of four RAS molecules (ACE, ACE2, AT1R, and AT2R) and NF-κB in rat heart after FRD (10% w/v, 9 weeks). In addition, we followed the changes in the n-6/n-3 PUFA ratio in the total pool of heart lipids after both treatments to elucidate the walnut effects on fatty acids in the heart. 36 animals (9 per group) participated in the experiment. FRD significantly increased the ACE protein level in the heart (p &lt; 0.001). Walnut supplementation significantly increased the ACE2 protein level in the heart of FRD (p &lt; 0.001). In addition, walnut supplementation showed a significant main effect on the arachidonic acid/eicosapentaenoic acid ratio (p = 0.004). Walnut supplementation significantly reduced this ratio, in comparison with both, the control group (C vs. FW, p &lt; 0.05) and the FRD group (F vs. FW, p &lt; 0.05). However, walnut treatment failed to revert the significant effect of fructose (p &lt; 0.001) on the elevation of NF-κB protein level. Our results suggest a beneficial effect of walnut supplementation on ACE2 protein level and n-6/n-3 PUFA level in the heart of the animal model of MetS. Such results highlight the approach of omega-3-rich walnut supplementation in the stimulation of endogenous production of favorable molecules in the heart which could be an affordable nutritional treatment formaintenance of cardio-metabolic health.

The effect of calcium gluconate administration during cardiopulmonary bypass on hemodynamic variables in infants undergoing open-heart surgery

Background

The incidence of complications after heart surgery is a critical factor in disability, deaths, lengthening hospital stays, and increasing treatment costs. The metabolic balance of certain hormones and electrolytes is necessary for proper cardiac function. In children, various biochemical conditions may cause calcium depletion during heart surgery. The purpose of this study was to determine the effect of calcium gluconate administration during cardiopulmonary bypass on hemodynamic variables and clinical outcomes in infants undergoing open-heart surgery. This study was conducted at Rajaie Cardiovascular Medical and Research Center in 2021 using a controlled randomized clinical trial. A total of 60 patients with open-heart surgery weighing up to 10 kg were included in the study. The first group received an intravenous injection of calcium gluconate 20 min after opening the aortic clamp, and the second group was monitored as a control group. Data collection tools included checklists containing demographics, surgical information, and intensive care unit measures.

Results

The Chi-square test or Fisher's exact test showed that the frequency distribution of gender, blood group, Rhesus factor (RH), and clinical diagnosis in the two groups of intervention and control was not statistically significant (p < 0.05). The mean and standard deviation of Ejection Fraction (EF) changes (before and after) were 13.27 ± 9.16 in the intervention group and 8.31 ± 9.80 in the control group (p = 0.065). The results of two-way repeated measures ANOVA showed that mean systolic blood pressure (p = 0.030), mean diastolic blood pressure (p = 0.021), mean heart rate (p = 0.025), mean arterial pressure (p = 0.020), mean pH (p < 0.001), and mean hemoglobin (p = 0.018) in the intervention, and control groups were statistically significant.

Conclusions

In the present study, unlike systolic pressure, mean diastolic blood pressure decreased, and mean arterial pressure increased significantly. As a result, the slope of changes during the study period was different in the intervention and control groups.

Renin Angiotensin Blockers and Cardiac Protection: From Basis to Clinical Trials

Despite a similar beneficial effect on blood pressure lowering observed with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor (AT1R) blocker (ARBs), several clinical trials and meta-analyses have reported higher cardiovascular mortality and lower protection against myocardial infarction with ARBs when compared with ACEIs. The European guidelines for the management of coronary syndromes and European guidelines on diabetes recommend using ARBs in patients who are intolerant to ACEIs. We reviewed the main pharmacological differences between ACEIs and ARBs, which could provide insights into the differences in the cardiac protection offered by these 2 drug classes. The effect of ACEIs on the tissue and plasma levels of bradykinin and on nitric oxide production and bioavailability is specific to the mechanism of action of ACEIs; it could account for the different effects of ACEIs and ARBs on endothelial function, atherogenesis, and fibrinolysis. Moreover, chronic blockade of AT1 receptors by ARBs induces a significant and permanent increase in plasma angiotensin II and an overstimulation of its still available receptors. In animal models, AT4 receptors have vasoconstrictive, proliferative, and inflammatory effects. Moreover, in models with kidney damage, atherosclerosis, and/or senescence, activation of AT2 receptors could have deleterious fibrotic, vasoconstrictive, and hypertrophic effects and seems prudent and reasonable to reserve the use of ARBs for patients who have presented intolerance to ACE inhibitors.

Arterial Hypertension in Aortic Valve Stenosis: A Critical Update

Aortic stenosis (AS) is a very common valve disease and is associated with high mortality once it becomes symptomatic. Arterial hypertension (HT) has a high prevalence among patients with AS leading to worse left ventricle remodeling and faster degeneration of the valve. HT also interferes with the assessment of the severity of AS, leading to an underestimation of the real degree of stenosis. Treatment of HT in AS has not historically been pursued due to the fear of excess reduction in afterload without a possibility of increasing stroke volume due to the fixed aortic valve, but most recent evidence shows that several drugs are safe and effective in reducing BP in patients with HT and AS. RAAS inhibitors and beta-blockers provide benefit in selected populations based on their profile of pharmacokinetics and pharmacodynamics. Different drugs, on the other hand, have proved to be unsafe, such as calcium channel blockers, or simply not easy enough to handle to be recommended in clinical practice, such as PDE5i, MRA or sodium nitroprusside. The present review highlights all available studies on HT and AS to guide antihypertensive treatment.

ACE Inhibitor Benefit to Kidney and Cardiovascular Outcomes for Patients with Non-Dialysis Chronic Kidney Disease Stages 3-5: A Network Meta-Analysis of Randomised Clinical Trials

Background

The advantages of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) in reducing risk of cardiovascular events (CVEs) and delaying end-stage kidney disease (ESKD) in patients with chronic kidney disease (CKD) is well-known. However, the efficacy and safety of these agents in non-dialysis CKD stages 3–5 patients are still a controversial issue.

Methods

Two investigators (Yaru Zhang and Dandan He) independently searched and identified relevant studies from MEDLINE (from 1950 to October 2018), EMBASE (from 1970 to October 2018), and the Cochrane Library database. Randomised clinical trials in non-dialysis CKD3–5 patients treated with renin-angiotensin system (RAS) inhibitors were included. We used standard criteria (Cochrane risk of bias tool) to assess the inherent risk of bias of trials. We calculated the odds ratio (OR) and 95% confidence interval (CI) for each outcome by random-effects model. A 2-sided p value < 0.05 was considered statistically significant, and all statistical analyses were performed using STATA, version 15.0. This network meta-analysis was undertaken by the frequency model.

Results

Forty-four randomised clinical trials with 42,319 patients were included in our network meta-analysis. ACEIs monotherapy significantly decreased the odds of kidney events (OR 0.54, 95% CI 0.41–0.73), cardiovascular events (OR 0.73, 95% CI 0.64–0.84), cardiovascular death (OR 0.73, 95% CI 0.63–0.86) and all-cause death (OR 0.77, 95% CI 0.66–0.91) when compared to placebo. According to the cumulative ranking area (SUCRA), ACEI monotherapy had the highest probabilities of their protective effects on outcomes of kidney events (SUCRA 93.3%), cardiovascular events (SUCRA 77.2%), cardiovascular death (SUCRA 86%), and all-cause death (SUCRA 94.1%), even if there were no significant differences between ACEIs and other antihypertensive drugs, including calcium channel blockers (CCBs), β-blockers and diuretics on above outcomes except for kidney events. ARB monotherapy and combination therapy of an ACEI plus an ARB showed no more advantage than CCBs, β-blockers and diuretics in all primary outcomes. In the subgroup of non-dialysis diabetic kidney disease patients, no drugs, including ACEIs or ARBs, significantly lowered the odds of cardiovascular events and all-cause death. However, ACEIs were still better than other antihypertensive drugs including ARBs in all-cause death but not ARBs in cardiovascular events according to the SUCRA. Only ARBs had significant differences in preventing the occurrence of kidney events compared with placebo (OR 0.82, 95% CI 0.72–0.95). Both ACEI/ARB monotherapy and combination therapy had higher odds of hyperkalaemia. ACEIs had 3.81 times higher odds than CCBs (95% CI 1.58–9.20), ARBs had 2.08–5.10 times higher odds than placebo and CCBs and combination therapy of an ACEI and an ARB had 4.80–24.5 times higher odds than all other treatments. Compared with placebo, CCBs and β blockers, ACEI therapy significantly increased the odds of cough (OR 2.90, 95% CI 1.76–4.77; OR 8.21, 95% CI 3.13–21.54 and OR 1.80, 95% CI 1.08–3.00). There were no statistical differences in hypotension among all comparisons except ACEIs versus placebo.

Conclusions

Although ACEIs increased the odds of hyperkalaemia, cough and hypotension, they were still superior to ARBs and other antihypertensive drugs and had the highest benefits for the prevention of kidney events, cardiovascular outcomes, cardiovascular death and all-cause mortality in non-dialysis CKD3–5 patients. In patients with advanced diabetic kidney disease, ACEIs were superior to ARBs in lowering risk of all-cause death but not in kidney events and cardiovascular events.

Electronic supplementary material

The online version of this article (10.1007/s40265-020-01290-3) contains supplementary material, which is available to authorized users.

Hypertension Drug Therapy

Hypertension is still the number one global killer. No matter what causes are, lowering blood pressure can significantly reduce cardiovascular complications, cardiovascular death, and total death. Unfortunately, some hypertensive individuals simply do not know having hypertension. Some knew it but either not being treated or treated but blood pressure does not achieve goal. The reasons for inadequate control of blood pressure are many. One important reason is that we are not very familiar with antihypertensive agents and less attention has been paid to comorbidities, complications as well as the hypertension-modified target organ damage in patients with hypertension. The right antihypertensive drug was not given to the right hypertensive patients at right time. This reviewer studied comprehensively the literature, hopefully that the review will help improve antihypertensive drug selection and antihypertensive therapy.

Renin Activity in Heart Failure with Reduced Systolic Function-New Insights

Regardless of the cause, symptomatic heart failure (HF) with reduced ejection fraction (rEF) is characterized by pathological activation of the renin–angiotensin–aldosterone system (RAAS) with sodium retention and extracellular fluid expansion (edema). Here, we review the role of active renin, a crucial, upstream enzymatic regulator of the RAAS, as a prognostic and diagnostic plasma biomarker of heart failure with reduced ejection fraction (HFrEF) progression; we also discuss its potential as a pharmacological bio-target in HF therapy. Clinical and experimental studies indicate that plasma renin activity is elevated with symptomatic HFrEF with edema in patients, as well as in companion animals and experimental models of HF. Plasma renin activity levels are also reported to be elevated in patients and animals with rEF before the development of symptomatic HF. Modulation of renin activity in experimental HF significantly reduces edema formation and the progression of systolic dysfunction and improves survival. Thus, specific assessment and targeting of elevated renin activity may enhance diagnostic and therapeutic precision to improve outcomes in appropriate patients with HFrEF.

The Role of Renin-Angiotensin-Aldosterone System and Its New Components in Arterial Stiffness and Vascular Aging

Many cardiovascular diseases present renin-angiotensin-aldosterone system (RAAS) hyperactivity as an important pathophysiological mechanism to be target in the therapeutic approaches. Moreover, arterial stiffness is currently considered as a new independent risk factor for cardiovascular disease in different clinical conditions, including hypertension and chronic kidney disease. In fact, excessive stimulation of angiotensin type 1 (AT1) receptors, as well as mineralocorticoid receptors, results in cellular growth, oxidative stress and vascular inflammation, which may lead to arterial stiffness and accelerate the process of vascular aging. In the last decades, a vasoprotective axis of the RAAS has been discovered, and now it is well established that new components with antioxidant and anti-inflammatory properties play important roles promoting vasodilation, natriuresis and reducing collagen deposition, thus attenuating arterial stiffness and improving endothelial function. In this review, we will focus on these pathophysiological mechanisms and the relevance of RAAS inhibition by different strategies to increase arterial compliance and to decelerate vascular aging.

Role of Vitamin D in Cardiovascular Diseases

Vitamin D is critical in mineral homeostasis and skeletal health and plays a regulatory role in nonskeletal tissues. Vitamin D deficiency is associated with chronic inflammatory diseases, including diabetes and obesity, both strong risk factors for cardiovascular diseases (CVDs). CVDs, including coronary artery disease, myocardial infarction, hypertrophy, cardiomyopathy, cardiac fibrosis, heart failure, aneurysm, peripheral arterial disease, hypertension, and atherosclerosis, are major causes of morbidity and mortality. The association of these diseases with vitamin D deficiency and improvement with vitamin D supplementation suggest its therapeutic benefit. The authors review the findings on the association of vitamin D deficiency and CVDs.

Renoprotective Effect of Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers in Diabetic Patients with Proteinuria

BACKGROUND/AIMS

Limited evidence exists on the choice of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) in diabetic patients with nephropathy. We aim to assess the renal effectiveness and safety of these drugs among diabetic nephropathy patients.

METHODS

This retrospective cohort study was conducted with diabetic nephropathy patients who initiated ACEI or ARB monotherapy. The primary outcome was a composite of end stage of renal disease and renal transplantation, and the secondary outcome was all-cause mortality. The safety endpoint was hyperkalemia.

RESULTS

Three thousand seven hundred and thirty-nine ACEI users and 3,316 ARB users were identified. ARBs seemed to be inferior to ACEIs given their poorer renal outcome (HR 1.31; 95% CI, 1.15-1.50) and higher risk of hyperkalemia (HR 1.17; 95% CI, 1.04-1.32). Among the four ACEIs compared, captopril was an inferior treatment choice given its poorer renal outcomes (HR 1.42; 95% CI, 1.05-1.93) and higher mortality rate (HR 1.25; 95% CI, 1.01-1.55). Irbesartan appeared to be a poorer treatment choice among the three ARBs compared, given its inferior renal protective effect (HR 1.35; 95% CI, 1.03-1.78).

CONCLUSIONS

Our findings suggest ACEIs as a relatively more renoprotective and safer treatment as compared to ARBs. Captopril and irbesartan may be inferior to the other ACEIs and ARBs respectively.

The vasoprotective axes of the renin-angiotensin system: Physiological relevance and therapeutic implications in cardiovascular, hypertensive and kidney diseases

The renin-angiotensin system (RAS) is undisputedly one of the most prominent endocrine (tissue-to-tissue), paracrine (cell-to-cell) and intracrine (intracellular/nuclear) vasoactive systems in the physiological regulation of neural, cardiovascular, blood pressure, and kidney function. The importance of the RAS in the development and pathogenesis of cardiovascular, hypertensive and kidney diseases has now been firmly established in clinical trials and practice using renin inhibitors, angiotensin-converting enzyme (ACE) inhibitors, type 1 (AT₁) angiotensin II (ANG II) receptor blockers (ARBs), or aldosterone receptor antagonists as major therapeutic drugs. The major mechanisms of actions for these RAS inhibitors or receptor blockers are mediated primarily by blocking the detrimental effects of the classic angiotensinogen/renin/ACE/ANG II/AT₁/aldosterone axis. However, the RAS has expanded from this classic axis to include several other complex biochemical and physiological axes, which are derived from the metabolism of this classic axis. Currently, at least five axes of the RAS have been described, with each having its key substrate, enzyme, effector peptide, receptor, and/or downstream signaling pathways. These include the classic angiotensinogen/renin/ACE/ANG II/AT₁ receptor, the ANG II/APA/ANG III/AT₂/NO/cGMP, the ANG I/ANG II/ACE2/ANG (1-7)/Mas receptor, the prorenin/renin/prorenin receptor (PRR or Atp6ap2)/MAP kinases ERK1/2/V-ATPase, and the ANG III/APN/ANG IV/IRAP/AT₄ receptor axes. Since the roles and therapeutic implications of the classic angiotensinogen/renin/ACE/ANG II/AT₁ receptor axis have been extensively reviewed, this article will focus primarily on reviewing the roles and therapeutic implications of the vasoprotective axes of the RAS in cardiovascular, hypertensive and kidney diseases.

Histone demethylase KDM3a, a novel regulator of vascular smooth muscle cells, controls vascular neointimal hyperplasia in diabetic rats

BACKGROUND AND AIMS

Deregulation of histone demethylase KDM3a, an important regulator for H3K9 methylation, is correlated with obesity and abnormal metabolism in rodent models. However, the function of KDM3a in vascular remodeling under diabetic condition is unknown.

METHODS

Adenoviruses expressing KDM3a and lentiviruses expressing KDM3a-targeting siRNA were generated to study the role of KDM3a both in vivo and in vitro. The carotid artery balloon injury model was established in diabetic SD rats to evaluate the significance of KDM3a in vascular injury.

RESULTS

Diabetic vessels were associated with sustained loss of histone H3 lysine 9 di-methylation (H3K9me2) and elevation of KDM3a. This phenomenon was induced by high glucose (HG) and was persistently present even after removal from diabetic condition and high glucose in vascular smooth muscle cells (VSMCs). After 28-day balloon injury, KDM3a overexpression accelerated while KDM3a knockdown reduced neointima formation, following vascular injury in diabetic rats without glucose control. Microarray analysis revealed KDM3a altered the expression of vascular remodeling genes; particularly, it mediated the Rho/ROCK and AngII/AGTR1 pathways. In the in vivo study, HG and Ang II-stimulated proliferation and migration of VSMCs were enhanced by KDM3a overexpression, whereas markedly prevented by KDM3a knockdown. KDM3a regulated the transcription of AGTR1 and ROCK2 via controlling H3K9me2 in the proximal promoter regions.

CONCLUSIONS

Histone demethylase KDM3a promotes vascular neointimal hyperplasia in diabetic rats via AGTR1 and ROCK2 signaling pathways. Targeting KDM3a might represent a promising therapeutic approach for the prevention of coronary artery disease with diabetes.

Modulatory Effects of Egg White Ovotransferrin-Derived Tripeptide IRW (Ile-Arg-Trp) on Vascular Smooth Muscle Cells against Angiotensin II Stimulation

The renin angiotensin system (RAS) is a key mediator of blood pressure regulation. Angiotensin II (Ang II), the active component of RAS, is a potent vasoconstrictor that also causes abnormal proliferation, oxidative stress, and inflammation in vascular smooth muscle cells (VSMCs) that contribute to atherosclerotic changes. Egg white ovotransferrin-derived tripeptide IRW (Ile-Arg-Trp) was previously shown to exert antihypertensive effect by reducing Ang II synthesis as well as endothelial cell inflammation and endothelial dysfunction. However, the effects of IRW on VSMCs are still unclear. In the present study, we evaluated the antiproliferative, antioxidant, and anti-inflammatory effects of IRW on VSMCs in the presence of Ang II stimulation. It was found that IRW treatment could attenuate Ang II-stimulated proliferation, superoxide production, and inflammation in VSMCs. These beneficial effects appeared to involve modulation of the NF-κB pathway. These findings could further our understanding on the antihypertensive mechanism of IRW beyond vascular endothelium.

Reduced Kidney Function Is Associated With Cardiometabolic Risk Factors, Prevalent and Predicted Risk of Cardiovascular Disease in Chinese Adults: Results From the REACTION Study

Background

Chronic kidney disease (CKD) increases cardiovascular disease (CVD) risk. However, the association of mildly reduced kidney function with CVD risk is unclear.

Methods and Results

This study investigated the association of estimated glomerular filtration rate (eGFR) with prevalent CVDs, 10‐year Framingham risk for coronary heart disease (CHD), and 10‐year risk of atherosclerotic cardiovascular diseases (ASCVD) in 239 832 participants from the baseline of the Risk Evaluation of cAncers in Chinese diabeTic Individuals: a lONgitudinal study. With an interviewer‐assisted questionnaire, we collected information on CVD, including reported CHD, stroke, or myocardial infarction. Chronic Kidney Disease–Epidemiology Collaboration (CKD‐EPI) equation was used to calculate eGFR. Compared with individuals with normal eGFR (≥90 mL/min per 1.73 m²), those with decreased eGFR (75–89, 60–74, and <60 mL/min per 1.73 m²) had higher risk of prevalent obesity, diabetes mellitus, hypertension, and dyslipidemia in both men and women (P for trend all <0.001). Moreover, a significantly higher 10‐year Framingham risk for CHD and 10‐year risk for ASCVD was observed in both men and women with mildly decreased eGFR (60–89 mL/min per 1.73 m²).

Conclusions

Even mildly reduced eGFR (under 90 mL/min per 1.73 m²) is associated with elevated 10‐year Framingham risk for CHD and 10‐year ASCVD risk among Chinese adults.

Antihypertensive Drug Use, Blood Pressure Variability, and Incident Stroke Risk in Older Adults

Background and Purpose—

The aim was to determine the association between antihypertensive drug class and incident stroke controlling for long-term blood pressure (BP) variability (BPV) in people aged ≥65 years.

Methods—

The sample included 5951 participants (median age 74 years, 60% women) taking at least 1 drug for hypertension (3727/5951) or with systolic BP >140 mm Hg or diastolic BP >90 mm Hg. Participants were evaluated for incident fatal and nonfatal stroke to 12 years follow-up. BPV was calculated with the coefficient of variation method and regressed against 9 antihypertensive drug classes (BPV reg ). Hazard models were used to determine hazard ratios for incident stroke risk attributable to drug class, adjusted for BP, BPV reg , covariates, and delayed entry bias.

Results—

There were 273 incident strokes over a median of 9.1 years (interquartile range 6.4–10.4). Stroke risk was generally not reduced by BP-lowering drugs. Angiotensin receptor blockers (hazard ratio 1.56; 95% confidence interval 1.06–2.28; P =0.02) and β-blockers (hazard ratio 1.41; 95% confidence interval 1.03–1.92; P =0.03) were associated with an increased total stroke risk. Angiotensin receptor blockers and β-blockers were also associated with ischemic strokes after adjustment for systolic BPV. Diastolic BPV was associated with stroke risk in analyses stratified by systolic BP 140 to 160 mm Hg (per 0.10 increase in coefficient of variation, hazard ratio 1.59; 95% confidence interval 1.05–2.40; P =0.03).

Conclusions—

The angiotensin receptor blocker and β-blocker drug classes were associated with incident stroke and ischemic stroke in older adults. BPV was generally not associated with incident stroke.

Angiotensin II type 1 receptor blockers as a first choice in patients with acute myocardial infarction

BACKGROUND/AIMS

Angiotensin II type 1 receptor blockers (ARBs) have not been adequately evaluated in patients without left ventricular (LV) dysfunction or heart failure after acute myocardial infarction (AMI).

METHODS

Between November 2005 and January 2008, 6,781 patients who were not receiving angiotensin-converting enzyme inhibitors (ACEIs) or ARBs were selected from the Korean AMI Registry. The primary endpoints were 12-month major adverse cardiac events (MACEs) including death and recurrent AMI.

RESULTS

Seventy percent of the patients were Killip class 1 and had a LV ejection fraction ≥ 40%. The prescription rate of ARBs was 12.2%. For each patient, a propensity score, indicating the likelihood of using ARBs during hospitalization or at discharge, was calculated using a non-parsimonious multivariable logistic regression model, and was used to match the patients 1:4, yielding 715 ARB users versus 2,860 ACEI users. The effect of ARBs on in-hospital mortality and 12-month MACE occurrence was assessed using matched logistic and Cox regression models. Compared with ACEIs, ARBs significantly reduced in-hospital mortality(1.3% vs. 3.3%; hazard ratio [HR], 0.379; 95% confidence interval [CI], 0.190 to0.756; p = 0.006) and 12-month MACE occurrence (4.6% vs. 6.9%; HR, 0.661; 95% CI, 0.457 to 0.956; p = 0.028). However, the benefit of ARBs on 12-month mortality compared with ACEIs was marginal (4.3% vs. 6.2%; HR, 0.684; 95% CI, 0.467 to 1.002; p = 0.051).

CONCLUSIONS

Our results suggest that ARBs are not inferior to, and may actually be better than ACEIs in Korean patients with AMI.

The angiotensin II receptor antagonist, losartan, enhances regulator of G protein signaling 2 mRNA expression in vascular smooth muscle cells of Wistar rats

Angiotensin II (Ang II) reportedly enhances regulator of G-protein signaling 2 (RGS2), thus making a negative feedback loop for Ang II signal transduction. However, few studies have reported whether Ang II receptor (ATR) antagonists influence RGS2 mRNA expression. We investigated RGS2 mRNA expression when Ang II binding to ATR was blocked with Ang II subtype-1 receptor (AT1R) blockers using vascular smooth muscle cells from the thoracic aorta of male Wistar rats. RGS2 mRNA expression significantly increased with Ang II stimulation, and this increase was almost completely abolished by olmesartan, a potent AT1R-specific blocker. Ang II subtype-2 receptor (AT2R) was not involved in Ang II-mediated RGS expression. In contrast, the AT1R blocker, losartan, partially decreased Ang II-mediated RGS2 mRNA expression because this antagonist directly stimulated RGS2 mRNA expression in Ang II-free medium. EXP3174, which is an active metabolite of losartan, almost completely blunted Ang II-mediated RGS2 mRNA expression without direct stimulation of RGS2 mRNA expression. Moreover, pretreatment with olmesartan abolished Ang II-mediated RGS2 mRNA expression. Treatment with a protein kinase C inhibitor partially decreased losartan-mediated RGS2 mRNA expression. These results suggest that AT1R blockers inhibit RGS2 mRNA expression in response to Ang II via an AT1R-mediated mechanism. However, the AT1R blocker, losartan, behaves as a direct agonist for RGS2 mRNA expression via AT1R through protein kinase C-dependent and -independent pathways. In conclusion, losartan exhibits dual effects on RGS2 mRNA expression, and the direct upregulation of RGS2 mRNA expression may provide a new strategy for the treatment of hypertension.

Role of angiotensin II in stem cell therapy of cardiac disease

INTRODUCTION

The renin angiotensin system (RAS) is closely related to the cardiovascular system, body fluid regulation and homeostasis.

MATERIALS AND METHODS

Despite common therapeutic methods, stem cell/progenitor cell therapy is daily increasing as a term of regenerative medicine. RAS and its pharmacological inhibitors are not only involved in physiological and pathological aspects of the cardiovascular system, but also affect the different stages of stem cell proliferation, differentiation and function, via interfering cell signaling pathways.

RESULTS

This study reviews the new role of RAS, in particular Ang II distinct from other common roles, by considering its regulating impact on the different signaling pathways involved in the cardiac and endothelial tissue, as well as in stem cell transplantation.

CONCLUSIONS

This review focuses on the impact of stem cell therapy on the cardiovascular system, the role of RAS in stem cell differentiation, and the role of RAS inhibition in cardiac stem cell growth and development.

The Comparative Effectiveness of Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers in Patients With Diabetes

The evidence examining the effect of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) on mortality in high-risk patients is conflicting. To further examine this controversy, the authors compared outcomes between ACE inhibitors and ARBs in a large clinical diabetes registry. A retrospective cohort of 87,472 incident users followed for 105,702 patient-years was analyzed. Average age was 53.1±10.1 years, 54.2% were men, and 14.4% had cardiovascular disease. All-cause hospitalization or all-cause mortality, the composite primary endpoint, occurred in 10,943 (12.5%) patients. Compared with ACE inhibitors, the adjusted hazard for ARBs was 0.90 (95% confidence interval, 0.87-0.94) for all-cause hospitalization or mortality; 0.95 (0.65-1.40) for mortality; 0.90 (0.87-0.94) for all-cause hospitalization; and 0.81 (0.74-0.89) for cardiovascular admission. ARB use was associated with a reduced, not increased, risk of hospitalization/mortality relative to ACE inhibition. This was driven by lower hospitalization, with a null mortality result.

IL-1β and IL-18: inflammatory markers or mediators of hypertension?

Chronic inflammation in the kidneys and vascular wall is a major contributor to hypertension. However, the stimuli and cellular mechanisms responsible for such inflammatory responses remain poorly defined. Inflammasomes are crucial initiators of sterile inflammation in other diseases such as rheumatoid arthritis and gout. These pattern recognition receptors detect host-derived danger-associated molecular patterns (DAMPs), such as microcrystals and reactive oxygen species, and respond by inducing activation of caspase-1. Caspase-1 then processes the cytokines pro-IL-1β and pro-IL-18 into their active forms thus triggering inflammation. While IL-1β and IL-18 are known to be elevated in hypertensive patients, no studies have examined whether this occurs downstream of inflammasome activation or whether inhibition of inflammasome and/or IL-1β/IL-18 signalling prevents hypertension. In this review, we will discuss some known actions of IL-1β and IL-18 on leukocyte and vessel wall function that could potentially underlie a prohypertensive role for these cytokines. We will describe the major classes of inflammasome-activating DAMPs and present evidence that at least some of these are elevated in the setting of hypertension. Finally, we will provide information on drugs that are currently used to inhibit inflammasome/IL-1β/IL-18 signalling and how these might ultimately be used as therapeutic agents for the clinical management of hypertension.

Valsartan blocked alcohol-induced, Toll-like receptor 2 signaling-mediated inflammation in human vascular endothelial cells

BACKGROUND

Alcohol consumption induces inflammatory damage in vessels, and the underlying mechanism is unclear. Valsartan, as one of the angiotensin receptor blockers (ARBs), plays a role in the inhibition of inflammatory reactions in vascular dysfunction. This study is to investigate the role of Toll-like receptor 2 (TLR2) in alcohol-induced inflammatory damage in vascular endothelial cells in vitro and to explore the protective effect of valsartan on alcohol-induced and TLR2-mediated inflammatory damage.

METHODS

The human umbilical vein cell line (EA.hy926) were exposed to alcohol at 0 to 80 mM for 0 to 48 hours with or without valsartan pretreatment. The expression of TLR2 signaling, including TLR2, tumor necrosis factor receptor associated factor 6 (TRAF-6) and nuclear factor kappa B (NF-κB) p65 were detected by Western blot. The levels of proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), were determined by ELISA. To confirm the role of TLR2, we functionally up-regulated or down-regulated TLR2 by using TLR2 agonist or TLR2 small interfering RNA (siRNA), respectively. To further investigate the mechanism of alcohol on renin-angiotensin system, we detected the expression of angiotensin II receptor type 1 (AGTR1) in protein levels.

RESULTS

The expression of TLR2, TRAF-6, NF-κB p65, and the proinflammatory cytokines, TNF-α and IL-6, were significantly increased after alcohol exposure in EA.hy926 endothelial cells. This was enhanced by TLR2 agonist, and was inhibited by TLR2 siRNA transfection. The pretreatment of valsartan resulted in an inhibition of TLR2 signaling and proinflammatory cytokines. The expression of AGTR1 was up-regulated after alcohol exposure, and was blocked by valsartan pretreatment.

CONCLUSIONS

TLR2 signaling-mediated alcohol induced inflammatory response in human vascular epithelial cells in vitro, which was inhibited by valsartan.

Comparison of benazepril and losartan on endothelial function and vascular stiffness in patients with Type 2 diabetes mellitus and hypertension: A randomized controlled trial

INTRODUCTION

The purpose of this study was to compare the effects of benazepril and losartan on endothelial function and vascular stiffness, in patients with diabetes mellitus and hypertension.

MATERIALS AND METHODS

We included hypertensive diabetic patients with an office systolic blood pressure (BP) ⩾ 130 mmHg and/or diastolic BP ⩾ 80 mmHg. Patients were rolled over to amlodipine for 6 weeks, then we performed C-reactive protein assays, BP measurement and vascular tests; next, patients were randomized to benazepril or losartan. The tests were repeated after 12 weeks.

RESULTS

We randomized 14 patients to benazepril and 16 to losartan. There were no differences in systolic (139 versus 134 mmHg, p = 0.618) and diastolic (82 versus 80 mmHg, p = 0.950) BP at the end of the study. C-reactive protein values were lower in the benazepril group (0.38 versus 0.42 mg/dl, p = 0.020). There was a slightly higher flow-mediated vasodilation (FMD) response in the benazepril group (45% increase, p = 0.057) than in the losartan group (19% increase, p = 0.132). Both central systolic BP (129 versus 123 mmHg, p = 0.934) and carotid-femoral pulse wave velocity (cfPWV) (8.5 versus 8.5 m/s, p = 0.280) were the same between groups.

CONCLUSIONS

Hypertensive diabetic patients using benazepril had a greater reduction in C-reactive protein, and a slight improvement in FMD, than those taking losartan.

Update on the role of angiotensin in the pathophysiology of coronary atherothrombosis

BACKGROUND

Coronary atherothrombosis due to atherosclerotic plaque rupture or erosion is frequently associated with acute coronary syndromes (ACS). Significant efforts have been made to elucidate the pathophysiological mechanisms underlying acute coronary events.

MATERIALS AND METHODS

This narrative review is based on the material searched for and obtained via PubMed up to August 2014. The search terms we used were as follows: 'angiotensin, acute coronary syndromes, acute myocardial infarction' in combination with 'atherosclerosis, vulnerability, clinical trial, ACE inhibitors, inflammation'.

RESULTS

Among several regulatory components, the renin-angiotensin system (RAS) was shown as a key pathway modulating coronary atherosclerotic plaque vulnerability. Indeed, these molecules are involved in all stages of atherogenesis. Classically, the RAS is composed by a series of enzymatic reactions leading to the angiotensin (Ang) II generation and activity. However, the knowledge of RAS has expanded and become more complex. The discovery of novel components and their functions has revealed additional pathways that contribute to or counterbalance the actions of Ang II. In this review, we discussed on recent findings concerning the role of different angiotensin peptides in the pathophysiology of ACS and coronary atherothrombosis, exploring the link between these molecules and atherosclerotic plaque vulnerability.

CONCLUSIONS

Treatments selectively targeting angiotensins (including Mas and AT2 agonists, ACE2 recombinant, or Ang-(1-7) and almandine in oral formulations) have been tested in animal studies or in small human subgroups, expanding the perspective in the ACS prevention. These novel strategies, especially in the counter-regulatory axis ACE2/Ang-(1-7)/Mas, might be promising to reduce plaque vulnerability and inflammation.

RAS inhibitors' dose-dependent efficacy: myth or reality?

OBJECTIVE

Treatment of hypertension remains challenging in clinical practice. One major problem is incorrect utilization of the principal drug classes. Drugs from each class are currently used in accordance with an assumption that the blood pressure (BP) lowering effect is dose dependent. While this is true for most drugs, it is not appropriate for all drugs that block the renin-angiotensin system (RAS).

METHODS

This review is based on a PubMed/Cochrane database search for articles on the dose-dependent effect of RAS blockers on BP and cardiovascular protection.

RESULTS

Of the RAS blockers, most angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) have a flat dose-response curve for BP decrease, meaning an increase in dose prolongs duration of action, but does not yield greater potency. Perindopril is the only ACE inhibitor to show a real dose-response curve for BP decrease. While the effectiveness of RAS blockers on target organ damage is dose dependent and at least partially unrelated to BP control, there is evidence that the only way to obtain a beneficial effect is to use them at full dose. Thus, RAS blockers need to be used at the correct dose, based on the results of controlled clinical trials and meta-analysis. Furthermore, for all-cause mortality, ACE inhibitors have been shown to be better than ARBs, a specific efficacy supported by perindopril-based studies including ASCOT-BPLA (the Anglo-Scandinavian Cardiac Outcomes Trial-BP Lowering Arm), ADVANCE (the Action in Diabetes and Vascular disease: PreterAx and DiamicroN-MR Controlled Evaluation trial) and HYVET (HYpertension in the Very Elderly Trial).

CONCLUSION

In hypertensive patients, a strategy based on ACE inhibitors with dose-dependent efficacy such as perindopril as optimal treatment should lead both to improved BP control and to a better protection from target organ damage, thereby reducing the incidence of cardiovascular events.

HDL cholesterol subclasses, myocardial infarction, and mortality in secondary prevention: the Lipoprotein Investigators Collaborative

AIMS

High-density lipoprotein (HDL) is highly heterogeneous and the link of its subclasses to prognosis remains controversial. We aimed to rigorously examine the associations of HDL subclasses with prognosis in secondary prevention.

METHODS AND RESULTS

We collaboratively analysed data from two, complementary prospective cohorts: the TRIUMPH study of 2465 acute myocardial infarction patients, and the IHCS study of 2414 patients who underwent coronary angiography. All patients had baseline HDL subclassification by vertical-spin density gradient ultracentrifugation. Given non-linearity, we stratified by tertiles of HDL-C and its two major subclasses (HDL2-C, HDL3-C), then compared multivariable-adjusted hazard ratios for mortality and mortality/myocardial infarction. Patients were middle-aged to elderly (TRIUMPH: 58.2 ± 12.2 years; IHCS: 62.6 ± 12.6 years), and the majority were men (TRIUMPH: 68.0%; IHCS: 65.5%). IHCS had lower mean HDL-C levels (34.6 ± 10.1 mg/dL) compared with TRIUMPH (40 ± 10.6 mg/dL). HDL3-C accounted for >3/4 of HDL-C (mean HDL3-C/HDL-C 0.78 ± 0.05 in both cohorts). During 2 years of follow-up in TRIUMPH, 226 (9.2%) deaths occurred, while death/myocardial infarction occurred in 401 (16.6%) IHCS patients over 5 years. No independent associations with outcomes were observed for HDL-C or HDL2-C. In contrast, the lowest tertile of HDL3-C was independently associated with >50% higher risk in each cohort (TRIUMPH: with middle tertile as reference, fully adjusted HR for mortality of HDL3-C, 1.57; 95% CI, 1.13-2.18; IHCS: fully adjusted HR for mortality/myocardial infarction, 1.55; 95% CI, 1.20-2.00).

CONCLUSION

In secondary prevention, increased risk for long-term hard clinical events is associated with low HDL3-C, but not HDL2-C or HDL-C, highlighting the potential value of subclassifying HDL-C.

HDL-mediated mechanisms of protection in cardiovascular disease

Low plasma levels of HDL-cholesterol (HDL-C) represent a strong and independent risk factor for cardiovascular disease. HDL particles display a wide spectrum of atheroprotective activities, which include effluxing cellular cholesterol, diminishing cellular death, decreasing vascular constriction, reducing inflammatory response, protecting from pathological oxidation, combating bacterial infection, lessening platelet activation, regulating gene expression by virtue of microRNAs, and improving glucose metabolism. It remains presently indeterminate as to whether some biological activities of HDL are more relevant for the protection of the endothelium from atherogenesis when compared with others. The multitude of such activities raises the question of a proper assay to assess HDL functionality ex vivo. Together with clear understanding of molecular mechanisms underlying atheroprotective properties of HDL, such assay will provide a basis to resolve the ultimate question of the HDL field to allow the development of efficient HDL-targeting therapies.

The pathobiology of diabetic vascular complications--cardiovascular and kidney disease

With the increasing incidence of obesity and type 2 diabetes, it is predicted that more than half of Americans will have diabetes or pre-diabetes by 2020. Diabetic patients develop vascular complications at a much faster rate in comparison to non-diabetic individuals, and cardiovascular risk is increased up to tenfold. With the increasing incidence of diabetes across the world, the development of vascular complications will become an increasing medical burden. Diabetic vascular complications affect the micro- and macro-vasculature leading to kidney disease often requiring dialysis and transplantation or cardiovascular disease increasing the risk for myocardial infarction, stroke and amputations as well as leading to premature mortality. It has been suggested that many complex pathways contribute to the pathobiology of diabetic complications including hyperglycaemia itself, the production of advanced glycation end products (AGEs) and interaction with the receptors for AGEs such as the receptor for advanced glycation end products (RAGE), as well as the activation of vasoactive systems such as the renin-angiotensin aldosterone system (RAAS) and the endothelin system. More recently, it has been hypothesised that reactive oxygen species derived from NAD(P)H oxidases (Nox) may represent a common downstream mediator of vascular injury in diabetes. Current standard treatment of care includes the optimization of blood glucose and blood pressure usually including inhibitors of the renin-angiotensin system. Although these interventions are able to delay progression, they fail to prevent the development of complications. Thus, there is an urgent medical need to identify novel targets in diabetic vascular complications which may include the blockade of Nox-derived ROS formation, as well as blockade of AGE formation and inhibitors of RAGE activation. These strategies may provide superior protection against the deleterious effects of diabetes on the vasculature.

Comparative effectiveness of renin-angiotensin system blockers and other antihypertensive drugs in patients with diabetes: systematic review and bayesian network meta-analysis

OBJECTIVE

To assess the effects of different classes of antihypertensive treatments, including monotherapy and combination therapy, on survival and major renal outcomes in patients with diabetes.

DESIGN

Systematic review and bayesian network meta-analysis of randomised clinical trials.

DATA SOURCES

Electronic literature search of PubMed, Medline, Scopus, and the Cochrane Library for studies published up to December 2011.

STUDY SELECTION

Randomised clinical trials of antihypertensive therapy (angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), α blockers, β blockers, calcium channel blockers, diuretics, and their combinations) in patients with diabetes with a follow-up of at least 12 months, reporting all cause mortality, requirement for dialysis, or doubling of serum creatinine levels.

DATA EXTRACTION

Bayesian network meta-analysis combined direct and indirect evidence to estimate the relative effects between treatments as well as the probabilities of ranking for treatments based on their protective effects.

RESULTS

63 trials with 36,917 participants were identified, including 2400 deaths, 766 patients who required dialysis, and 1099 patients whose serum creatinine level had doubled. Compared with placebo, only ACE inhibitors significantly reduced the doubling of serum creatinine levels (odds ratio 0.58, 95% credible interval 0.32 to 0.90), and only β blockers showed a significant difference in mortality (odds ratio 7.13, 95% credible interval 1.37 to 41.39). Comparisons among all treatments showed no statistical significance in the outcome of dialysis. Although the beneficial effects of ACE inhibitors compared with ARBs did not reach statistical significance, ACE inhibitors consistently showed higher probabilities of being in the superior ranking positions among all three outcomes. Although the protective effect of an ACE inhibitor plus calcium channel blocker compared with placebo was not statistically significant, the treatment ranking identified this combination therapy to have the greatest probability (73.9%) for being the best treatment on reducing mortality, followed by ACE inhibitor plus diuretic (12.5%), ACE inhibitors (2.0%), calcium channel blockers (1.2%), and ARBs (0.4%).

CONCLUSIONS

Our analyses show the renoprotective effects and superiority of using ACE inhibitors in patients with diabetes, and available evidence is not able to show a better effect for ARBs compared with ACE inhibitors. Considering the cost of drugs, our findings support the use of ACE inhibitors as the first line antihypertensive agent in patients with diabetes. Calcium channel blockers might be the preferred treatment in combination with ACE inhibitors if adequate blood pressure control cannot be achieved by ACE inhibitors alone.

Metabolic actions of angiotensin II and insulin: a microvascular endothelial balancing act

Metabolic actions of insulin to promote glucose disposal are augmented by nitric oxide (NO)-dependent increases in microvascular blood flow to skeletal muscle. The balance between NO-dependent vasodilator actions and endothelin-1-dependent vasoconstrictor actions of insulin is regulated by phosphatidylinositol 3-kinase-dependent (PI3K)--and mitogen-activated protein kinase (MAPK)-dependent signaling in vascular endothelium, respectively. Angiotensin II acting on AT₂ receptor increases capillary blood flow to increase insulin-mediated glucose disposal. In contrast, AT₁ receptor activation leads to reduced NO bioavailability, impaired insulin signaling, vasoconstriction, and insulin resistance. Insulin-resistant states are characterized by dysregulated local renin-angiotensin-aldosterone system (RAAS). Under insulin-resistant conditions, pathway-specific impairment in PI3K-dependent signaling may cause imbalance between production of NO and secretion of endothelin-1, leading to decreased blood flow, which worsens insulin resistance. Similarly, excess AT₁ receptor activity in the microvasculature may selectively impair vasodilation while simultaneously potentiating the vasoconstrictor actions of insulin. Therapeutic interventions that target pathway-selective impairment in insulin signaling and the imbalance in AT₁ and AT₂ receptor signaling in microvascular endothelium may simultaneously ameliorate endothelial dysfunction and insulin resistance. In the present review, we discuss molecular mechanisms in the endothelium underlying microvascular and metabolic actions of insulin and Angiotensin II, the mechanistic basis for microvascular endothelial dysfunction and insulin resistance in RAAS dysregulated clinical states, and the rationale for therapeutic strategies that restore the balance in vasodilator and constrictor actions of insulin and Angiotensin II in the microvasculature.

Renin inhibitors and cardiovascular and renal protection: an endless quest?

Renin-angiotensin system (RAS) blockade with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) has become a major therapeutic approach in medicine since the end of the 1970's. Although these molecules were the first RAS blockers to be developed, it would have been physiologically and pharmacologically more pertinent to selectively inhibit renin itself. Indeed, the reaction between renin and its unique substrate, angiotensinogen, is the highly regulated and rate-limiting step of the RAS. The development of direct renin inhibitors (DRI) has been a slow and complex process and the synthesis of the first orally active DRI, aliskiren, was only achieved in the 2000's. Its pharmacological profile in patients with hypertension, diabetic nephropathy or heart failure, in addition to experimental evidence, suggests that aliskiren may be of value for the management of cardiovascular and renal diseases. However, the long-term, randomized, placebo-controlled, morbidity/mortality trial, ALTITUDE, which included 8,600 patients with type 2 diabetes, proteinuria and a high cardiovascular risk already treated with ACE inhibitors or ARBs was terminated in December 2011 because of futility and an increased incidence of serious adverse events in the aliskiren 300 mg arm. Other long-term studies are still ongoing to demonstrate the safety and efficacy of aliskiren to reduce cardiovascular morbidity and mortality in patients with heart failure and in elderly individuals (≥65 years) with systolic blood pressure of 130 to 159 mmHg, no overt cardiovascular disease, and a high cardiovascular risk profile. In the meantime, according to the European Medicines Agency recommendations, aliskiren should not be prescribed to diabetic patients in combination with ACE inhibitors or ARBs.

Different cross-talk sites between the renin-angiotensin and the kallikrein-kinin systems

Targeting the renin-angiotensin system (RAS) constitutes a major advance in the treatment of cardiovascular diseases. Evidence indicates that angiotensin-converting enzyme inhibitors and angiotensin AT1 receptor blockers act on both the RAS and the kallikrein-kinin system (KKS). In addition to the interaction between the RAS and KKS at the level of angiotensin-converting enzyme catalyzing both angiotensin II generation and bradykinin degradation, the RAS and KKS also interact at other levels: 1) prolylcarboxypeptidase, an angiotensin II inactivating enzyme and a prekallikrein activator; 2) kallikrein, a kinin-generating and prorenin-activating enzyme; 3) angiotensin-(1-7) exerts kininlike effects and potentiates the effects of bradykinin; and 4) the angiotensin AT1 receptor forms heterodimers with the bradykinin B2 receptor. Moreover, angiotensin II enhances B1 and B2 receptor expression via transcriptional mechanisms. These cross-talks explain why both the RAS and KKS are up-regulated in some circumstances, whereas in other circumstances both systems change in the opposite manner, expressed as an activated RAS and a depressed KKS. As the cross-talks between the RAS and the KKS play an important role in response to different stimuli, taking these cross-talks between the two systems into account may help in the development of drugs targeting the two systems.

Renin inhibition in the treatment of diabetic kidney disease

Inhibition of the RAAS (renin–angiotensin–aldosterone system) plays a pivotal role in the prevention and treatment of diabetic nephropathy and a spectrum of other proteinuric kidney diseases. Despite documented beneficial effects of RAAS inhibitors in diabetic patients with nephropathy, reversal of the progressive course of this disorder or at least long-term stabilization of renal function are often difficult to achieve, and many patients still progress to end-stage renal disease. Incomplete inhibition of the RAAS has been postulated as one of reasons for unsatisfactory therapeutic responses to RAAS inhibition in some patients. Inhibition of renin, a rate-limiting step in the RAAS activation cascade, could overcome at least some of the abovementioned problems associated with the treatment with traditional RAAS inhibitors. The present review focuses on experimental and clinical studies evaluating the two principal approaches to renin inhibition, namely direct renin inhibition with aliskiren and inhibition of the (pro)renin receptor. Moreover, the possibilities of renin inhibition and nephroprotection by interventions primarily aiming at non-RAAS targets, such as vitamin D, urocortins or inhibition of the succinate receptor GPR91 and cyclo-oxygenase-2, are also discussed.

Cardiovascular and cerebrovascular outcomes in elderly hypertensive patients treated with either ARB or ACEI

Background

Although angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) are equally important in the treatment of hypertension, there is less evidence whether they have equal cardiovascular and cerebrovascular protective effects, especially in elder hypertensive patients. This study aims to clarify this unresolved issue.

Methods

This cross-sectional study included clinical data on 933 aged male patients with hypertension who received either an ARB or ACEI for more than two months between January 2007 and May 2011. The primary outcome was the composite of cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke. The secondary endpoints were unstable angina, new atrial fibrillation, and transient ischemic attack.

Results

The median follow-up time was 24 months. Age, drug types, cerebral infarction history, renal dysfunction history were the independent predictors of the primary endpoint. The risk of an occurrence of a primary endpoint event was higher in the ARB group than the ACEI group [P = 0.037, hazard ratios (HR): 2.124, 95% confidence interval (95% CI): 1.048–4.306]. The Kaplan-Meier method also suggests that the rate of primary endpoint occurrence was higher in the ARB group than the ACEI group (P = 0.04). In regard to the secondary endpoints, there were no significant differences between the two treatment arms (P = 0.137, HR: 1.454, 95% CI: 0.888–2.380). Patient age and coronary heart disease history were independent predictors of the secondary endpoint.

Conclusion

ACEI were more effective than ARB in reducing cardiovascular and cerebrovascular morbidity and mortality in aged patients with hypertension.

Cardiovascular outcomes in high-risk patients without heart failure treated with ARBs: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Angiotensin II type 1 receptor antagonists (ARBs) are widely used as a substitute for angiotensin-converting enzyme inhibitors (ACEIs) to treat patients without heart failure, but their effect on cardiovascular morbidity and mortality has not been clearly determined. A systematic review and meta-analysis was undertaken to determine the impact of ARBs on cardiovascular outcomes in high-risk patients without heart failure.

METHODS

A computerized literature search was carried out using PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, and EMBASE, from January 1990 to April 2008. The following search terms were used: 'hypertension', 'clinical trial', 'sartan', 'ARB', 'angiotensin receptor antagonist', 'losartan', 'candesartan', 'valsartan', 'irbesartan', 'eprosartan', 'telmisartan', 'olmesartan', 'coronary disease', 'coronary heart disease', 'myocardial infarction', 'cardiovascular disease', 'cerebrovascular disease', and 'stroke'. Criteria for inclusion of clinical trials in our meta-analysis were the use of a randomized control group not receiving an ARB and the availability of outcome data for any one of four endpoints: myocardial infarction (MI), stroke, cardiovascular death, and all-cause death (these were not always pre-specified endpoints in all trials). Out of 45 potentially relevant studies, 37 trials met the inclusion criteria. We tabulated all occurrences of these four adverse outcomes.

RESULTS

Homogenous subgroups were combined by means of a fixed-effects model, while heterogenous subgroups were not combined. In the subgroup without heart failure, ARBs, when compared with the control group, had an odds ratio of 1.09 (95% CI 1.00, 1.18; p = 0.05) for MI. Other endpoints, namely, cardiovascular death and all-cause death, did not reach statistical significance. There was a clear trend for fewer strokes in the ARB group, but these studies were clearly heterogenous, and therefore a pooled risk estimate was not computed.

CONCLUSION

After pooling more than 89 000 patients, there is no evidence to suggest that ARBs confer cardiovascular protection akin to ACEIs, and the results that emerged are not in favor of ARB therapy in terms of its use as a substitute for ACEIs in non-heart failure patients. ARBs may have a small benefit in terms of stroke risk, but the studies are heterogenous, making it very difficult to quantify this effect. Given that ACEIs protect against both stroke and MI, caution is advised in the use of ARBs as a substitute for ACEIs in patients without a heart failure indication, who are tolerant of an ACEI.

Novel pathways and therapies in experimental diabetic atherosclerosis

Diabetic subjects are at a greater risk of developing major vascular complications due to abnormalities pertinent to the diabetic milieu. Current treatment options achieve significant improvements in glucose levels and blood pressure control, but do not necessarily prevent or retard diabetes-mediated macrovascular disease. In this review, we highlight several pathways that are increasingly being appreciated as playing a significant role in diabetic vascular injury. We focus particularly on the advanced glycation end product/receptor for advanced glycation end product (AGE/RAGE) axis and its interplay with the nuclear protein HMGB1. We discuss evidence implicating a significant role for the renin-angiotensin system, urotensin II and PPAR, as well as the importance of proinflammatory mediators and oxidative stress in cardiovascular complications. The specific targeting of these pathways may lead to novel therapies to reduce the burden of diabetic vascular complications.

Renin-Angiotensin System and AtrialFibrillation:Understanding the Connection

Atrial fibrillation (AF) arises as a result of a complex interaction of triggers, perpetuators and the substrate. The recurrence of AF may be partially related to a biologic phenomenon known as remodeling, in which the electrical, mechanical, and structural properties of the atrial tissue and cardiac cells are progressively altered,creating a more favorable substrate. Atrial remodeling is in part a consequence of arrhythmia itself. Therefore,to prevent and to treat AF, much attention has been directed to upstream therapies to alter the arrhythmia substrate and to reduce atrial remodeling. The renin-angiotensin-aldosterone system (RAAS) plays a keyrole in these strategies. In this review we analyze the experimental and clinical evidence regarding the efficacy of RAAS inhibitors in AF treatment. In the primary prevention of AF, meta-analyses have shown that risk of new-onset AF in patients with congestive heart failure and left ventricular dysfunction is reduced by RAAS inhibitors, whereas in hypertensive and post-myocardial infarction patients, the results are less evident. In the secondary prevention of AF, some large, prospective, randomized, placebo-controlled studieswith angiotensin II-receptor blockers returned negative results. Unfortunately, the approach of using RAASinhibitors as antiarrhythmic drugs to prevent both new-onset and recurrent AF is in decline because negativetrial results are accumulating, with the exception of the results in patients with congestive heart failure.

Effects of captopril and angiotensin II receptor blockers (AT1, AT2) on myocardial ischemia-reperfusion induced infarct size

The renin-angiotensin system (RAS) plays a major role in regulating the cardiovascular system, and disorders of the RAS contribute largely to the cardiac pathophysiology, including myocardial ischemia-reperfusion (MI/R) injury. Two subtypes of angiotensin II (Ang II) receptors have been defined on the basis of their differential pharmacological properties. The current study was undertaken to address the question as to whether the inhibition of the angiotensin converting enzyme (ACE) by captopril and the AT1 and AT2 receptor blockers losartan and PD123319 modulate MI/R-induced infarct size in an in vivo rat model. To produce necrosis, a branch of the descending left coronary artery was occluded for 30 min followed by two hours of reperfusion. ECG changes, blood pressure, and heart rate were measured during the experiment. Captopril (3 mg/kg), losartan (2 mg/kg), and PD123319 (20 μg/kg/min) were given in an IV 10 min before ischemia and were continued during the ischemic period. The infarcted area was measured by TTC staining. The volume of infarct and the risk zone was determined by planimetry. Compared to the control group (55.62±4.00%) both captopril and losartan significantly reduced the myocardial infarct size (30.50±3.26% and 37.75±4.44%), whereas neither PD123319 nor PD123319+losartan affected the infarct size volume (46.50±3.72% and 54.62±2.43%). Our data indicates that captopril and losartan exert cardioprotective activity after an MI/R injury. Also, infarct size reduction by losartan was halted by a blockade of the AT2 receptor. Therefore, the activation of AT2 receptors may be potentially protective and appear to oppose the effects mediated by the AT1 receptors.

FXR an emerging therapeutic target for the treatment of atherosclerosis

Atherosclerosis is the leading cause of illness and death. Therapeutic strategies aimed at reducing cholesterol plasma levels have shown efficacy in either reducing progression of atherosclerotic plaques and atherosclerosis-related mortality. The farnesoid-X-receptor (FXR) is a member of metabolic nuclear receptors (NRs) superfamily activated by bile acids. In entero-hepatic tissues, FXR functions as a bile acid sensor regulating bile acid synthesis, detoxification and excretion. In the liver FXR induces the expression of an atypical NR, the small heterodimer partner, which subsequently inhibits the activity of hepatocyte nuclear factor 4α repressing the transcription of cholesterol 7a-hydroxylase, the critical regulatory gene in bile acid synthesis. In the intestine FXR induces the release of fibroblast growth factor 15 (FGF15) (or FGF19 in human), which activates hepatic FGF receptor 4 (FGFR4) signalling to inhibit bile acid synthesis. In rodents, FXR activation decreases bile acid synthesis and lipogenesis and increases lipoprotein clearance, and regulates glucose homeostasis by reducing liver gluconeogenesis. FXR exerts counter-regulatory effects on macrophages, vascular smooth muscle cells and endothelial cells. FXR deficiency in mice results in a pro-atherogenetic lipoproteins profile and insulin resistance but FXR^−/– mice fail to develop any detectable plaques on high-fat diet. Synthetic FXR agonists protect against development of aortic plaques formation in murine models characterized by pro-atherogenetic lipoprotein profile and accelerated atherosclerosis, but reduce HDL levels. Because human and mouse lipoprotein metabolism is modulated by different regulatory pathways the potential drawbacks of FXR ligands on HDL and bile acid synthesis need to addressed in relevant clinical settings.