Renin-Angiotensin system modulators modestly reduce vascular risk in persons with prior stroke

Quality of systematic reviews supporting the 2017 ACC/AHA and 2018 ESC/ESH guidelines for the management of hypertension

OBJECTIVE

To assess the methodological and reporting quality of systematic reviews (SRs) that informed recommendations in the recent American and European hypertension guidelines.

DESIGN AND SETTINGS

Meta-epidemiological study. We identified SRs that were cited for class I recommendations based on Level of Evidence-A in the 2017 American College of Cardiology/American Heart Association (ACC/AHA) and the 2018 European Society of Cardiology/European Society of Hypertension (ESC/ESH) hypertension guidelines.

MAIN OUTCOME MEASURES

Methodological and reporting quality of the SRs was assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) checklist and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, respectively.

RESULTS

A total of 40 SRs was included in the analysis (28 from 2017 ACC/AHA; 22 from 2018 ESC/ESH and 10 were included in both). Based on the AMSTAR-2 assessment, only 7.5% SRs were found to be of high methodological quality, 47.5% were of moderate, each 22.5% were of low and critically low quality. Based on the PRISMA checklist assessment, a mean of 24 items (SD (2.76) were reported appropriately, and only five SRs reported all 27 items appropriately.

CONCLUSION

Methodological and reporting quality of SRs were found to vary considerably. Lack of information on the funding source of included studies, use of a protocol, integration of risk of bias assessments while interpreting findings and reporting of excluded studies were major methodological deficiencies.

Soluble (pro)renin receptor induces endothelial dysfunction and hypertension in mice with diet-induced obesity via activation of angiotensin II type 1 receptor

Until now, renin-angiotensin system (RAS) hyperactivity was largely thought to result from angiotensin II (Ang II)-dependent stimulation of the Ang II type 1 receptor (AT1R). Here we assessed the role of soluble (pro)renin receptor (sPRR), a product of site-1 protease-mediated cleavage of (pro)renin receptor (PRR), as a possible ligand of the AT1R in mediating: (i) endothelial cell dysfunction in vitro and (ii) arterial dysfunction in mice with diet-induced obesity. Primary human umbilical vein endothelial cells (HUVECs) treated with a recombinant histidine-tagged sPRR (sPRR-His) exhibited IκBα degradation concurrent with NF-κB p65 activation. These responses were secondary to sPRR-His evoked elevations in Nox4-derived H2O2 production that resulted in inflammation, apoptosis and reduced NO production. Each of these sPRR-His-evoked responses was attenuated by AT1R inhibition using Losartan (Los) but not ACE inhibition using captopril (Cap). Further mechanistic exploration revealed that sPRR-His activated AT1R downstream Gq signaling pathway. Immunoprecipitation coupled with autoradiography experiments and radioactive ligand competitive binding assays indicate sPRR directly interacts with AT1R via Lysine199 and Asparagine295. Important translational relevance was provided by findings from obese C57/BL6 mice that sPRR-His evoked endothelial dysfunction was sensitive to Los. Besides, sPRR-His elevated blood pressure in obese C57/BL6 mice, an effect that was reversed by concurrent treatment with Los but not Cap. Collectively, we provide solid evidence that the AT1R mediates the functions of sPRR during obesity-related hypertension. Inhibiting sPRR signaling should be considered further as a potential therapeutic intervention in the treatment and prevention of cardiovascular disorders involving elevated blood pressure.

Receptors | Angiotensin Receptors

The renin-angiotensin-aldosterone system (RAS) is a vital hormone-receptor system that regulates cardiovascular and renal functions. In this article, we discuss exciting new findings in the RAS field. Recently solved active state crystal structures of Angiotensin II type 1 (AT1R) and type 2 receptor (AT2R) helped in understanding receptor activation mechanisms in detail. Also, considerable attention is given to the developments in characterizing the counter-regulatory RAS axis due to current hope for harnessing this axis for the development of protective therapies against various cardiovascular diseases. We describe the RAS component, angiotensin-converting enzyme 2 (ACE2) functioning as cellular entry receptor for the causative agent of COVID-19 pandemic, SARS-CoV-2. Altogether, these discoveries paved the way for developing novel therapies targeting different components of the RAS in the future.

Predictors of Recurrent Ischemic Stroke in Obese Patients With Type 2 Diabetes Mellitus: A Population-based Study

BACKGROUND

Diabetes and obesity are established risk factors for stroke. The current study aimed to assess risk factors of ischemic stroke recurrence in diabetic patients based on their body mass index (BMI).

METHODS

A total of 4005 diabetic patients who had a history of ischemic stroke were identified in a retrospective cross-sectional dataset from the Malaysian National Neurology Registry. Patients were classified based on BMI, and multivariable regression analysis was used to evaluate the association between risk factors and recurrent ischemic stroke.

RESULTS

Among obese patients, those with ischemic heart disease (aOR, 1.873; 95% CI, 1.131-3.103), received formal education (aOR, 2.236; 95% CI, 1.306-3.830), and received anti-diabetic medication (aOR, 1.788; 95% CI, 1.180-2.708) had a higher stroke recurrence risk, while receiving angiotensin receptors blockers (aOR, 0.261; 95% CI, 0.126-0.543) lowered the odds of recurrence. Overweight patients with hypertension (aOR, 1.011; 95% CI, 1.002-1.019) for over 10 years (aOR, 3.385; 95% CI, 1.088-10.532) and diabetes prior to the first stroke (aOR, 1.823; 95% CI, 1.020-3.259) as well as those received formal education (aOR, 2.403; 95% CI, 1.126-5.129) had higher odds of stroke recurrence, while receiving angiotensin-converting enzyme inhibitors (aOR, 0.244; 95% CI, 0.111-0.538) lowered the recurrence risk. Normal weight East Malaysians (aOR, 0.351; 95% CI, 0.164-0.750) receiving beta-blockers (aOR, 0.410; 95% CI, 0.174-0.966) had lower odds of stroke recurrence.

CONCLUSIONS

Ischemic heart disease, hypertension, receiving anti-hypertensive agents, and educational level were independent predictors of recurrent stroke in obese patients. Managing the modifiable risk factors can decrease the odds of stroke recurrence.

Estimating the risk of acute kidney injury associated with use of diuretics and renin angiotensin aldosterone system inhibitors: A population based cohort study using the clinical practice research datalink

Background

The risk of acute kidney injury (AKI) attributable to renin angiotensin aldosterone (RAAS) inhibitors and diuretics remains unclear.

Methods

We conducted a prospective cohort study using the Clinical Practice Research Datalink (2008–2015) linked to Hospital Episode Statistics – Admitted Patient Care and Office for National Statistics mortality data. Patients were included if they had one or more chronic diagnoses requiring medication. Exposed patients had a first ever prescription for RAAS inhibitors/diuretics during the study period. AKI risk associated with exposure was determined by multivariable Cox regression, propensity score-adjusted Cox regression and a prior event rate ratio (PERR) analysis.

Results

One hundred forty thousand nine hundred fifty-two individuals were included. Increased AKI risk in the exposed group was demonstrated in both the multivariable and propensity score-adjusted cox regressions (HR 1.23 (95% CI 1.04–1.45) and HR 1.24 (1.05–1.47) respectively). The PERR analysis provided a similar overall hazard ratio with a wider confidence interval (HR 1.29 (0.94–1.63)). The increased AKI risk in the exposed group was present only in those receiving two or more antihypertensives. Absolute AKI risk was small.

Conclusions

RAAS inhibitors/diuretics result in an increased risk of AKI. The absolute increase in AKI risk is small, however, and needs to be considered in the context of any potential benefits.

Use of antihypertensive medication after ischemic stroke in young adults and its association with long-term outcome

BACKGROUND

Knowledge on the use of secondary preventive medication in young adults is limited.

METHODS

We included 936 first-ever ischemic stroke 30-day survivors aged 15-49, enrolled in the Helsinki Young Stroke Registry, 1994-2007. Follow-up data until 2012 came from Finnish Care Register, Statistics Finland, and Social Insurance Institution of Finland. Usage thresholds were defined as non-users, low (prescription coverage <30%), intermediate (30-80%) and high users (>80%). Adjusted Cox regression allowed assessing the association of usage with all-cause mortality and recurrent vascular events.

RESULTS

Of our patients, 40.5% were non-users, 7.8% had low usage, 11.8% intermediate usage and 40.0% high usage. Median follow-up was 8.3 years. Compared to non-users, risk of mortality and recurrent stroke or TIA was lower for patients with low-intermediate (HR 0.40, 95% CI 0.22-0.65; HR 0.31, 95% CI 0.18-0.53) and high usage (HR 0.25, 95% CI 0.15-0.42; HR 0.30, 95% CI 0.19-0.46), after adjustment for confounders.

CONCLUSIONS

Use of antihypertensives was suboptimal in one-third of patients in whom antihypertensives were initially prescribed. Users were at lower risk of mortality and recurrent stroke or TIA compared to non-users. Key Messages The use of antihypertensive medication is suboptimal in one-third of patients in whom antihypertensive medication was initially prescribed after ischemic stroke at young age. The risk of mortality and recurrent stroke or TIA is lower for users of antihypertensive medication after ischemic stroke at young age compared to non-users, after adjustment for relevant confounders including pre-existing hypertension and prior use of antihypertensive medication. Specific guidelines on antihypertensive medication use after ischemic stroke at young age are lacking. However, our results may motivate doctors and patients in gaining better usage of antihypertensive medication, since better usage was associated with more favorable outcome in this study.

Estimated glomerular filtration rate predicts incident stroke among Ghanaians with diabetes and hypertension

Background

Sub-Saharan Africa is currently experiencing a high burden of both chronic kidney disease (CKD) and stroke as a result of a rapid rise in shared common vascular risk factors such as hypertension and diabetes mellitus. However, no previous study has prospectively explored independent associations between CKD and incident stroke occurrence among indigenous Africans. This study sought to fill this knowledge gap.

Methods

A prospective cohort study involving Ghanaians adults with hypertension or type II diabetes mellitus from 5 public hospitals. Patients were followed every 2 months in clinic for 18 months and assessed clinically for first ever stroke by physicians. Serum creatinine derived estimated glomerular filtration rates (eGFR) were determined at baseline for 2631 (81.7%) out of 3296 participants. We assessed associations between eGFR and incident stroke using a multivariate Cox Proportional Hazards regression model.

Results

Stroke incidence rates (95% CI) increased with decreasing eGFR categories of 89, 60–88, 30–59 and <29 ml/min corresponding to incidence rates of 7.58 (3.58–13.51), 14.45 (9.07–21.92), 29.43 (15.95–50.04) and 66.23 (16.85–180.20)/1000 person-years respectively. Adjusted hazard ratios (95%CI) for stroke occurrence according to eGFR were 1.42 (0.63–3.21) for eGFR of 60-89 ml/min, 1.88 (1.17–3.02) for 30-59 ml/min and 1.52 (0.93–2.43) for <30 ml/min compared with eGFR of >89 ml/min. Adjusted HR for stroke occurrence among patients with hypertension with eGFR<60 ml/min was 3.69 (1.49–9.13), p = .0047 and among those with diabetes was 1.50 (0.56–3.98), p = .42.

Conclusion

CKD is dose-dependently associated with occurrence of incident strokes among Ghanaians with hypertension and diabetes mellitus. Further studies are warranted to explore interventions that could attenuate the risk of stroke attributable to renal disease among patients with hypertension in SSA.

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We assessed association between incident stroke and estimated glomerular filtration rate.

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2631 participants stroke-free Ghanaian adults with hypertension or diabetes were followed for 14 months.

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There were 45 incident strokes.

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Incident stroke risk independently increased with declining eGFR.

The non-biphenyl-tetrazole angiotensin AT1 receptor antagonist eprosartan is a unique and robust inverse agonist of the active state of the AT1 receptor

BACKGROUND AND PURPOSE

Conditions such as hypertension and renal allograft rejection are accompanied by chronic, agonist-independent, signalling by angiotensin II AT1 receptors. The current treatment paradigm for these diseases entails the preferred use of inverse agonist AT1 receptor blockers (ARBs). However, variability in the inverse agonist activities of common biphenyl-tetrazole ARBs for the active state of AT1 receptors often leads to treatment failure. Therefore, characterization of robust inverse agonist ARBs for the active state of AT1 receptors is necessary.

EXPERIMENTAL APPROACH

To identify the robust inverse agonist for active state of AT1 receptors and its molecular mechanism, we performed site-directed mutagenesis, competition binding assay, inositol phosphate production assay and molecular modelling for both ground-state wild-type AT1 receptors and active-state N111G mutant AT1 receptors.

KEY RESULTS

Although candesartan and telmisartan exhibited weaker inverse agonist activity for N111G- compared with WT-AT1 receptors, only eprosartan exhibited robust inverse agonist activity for both N111G- and WT- AT1 receptors. Specific ligand-receptor contacts for candesartan and telmisartan are altered in the active-state N111G- AT1 receptors compared with the ground-state WT-AT1 receptors, suggesting an explanation of their attenuated inverse agonist activity for the active state of AT1 receptors. In contrast, interactions between eprosartan and N111G-AT1 receptors were not significantly altered, and the inverse agonist activity of eprosartan was robust.

CONCLUSIONS AND IMPLICATIONS

Eprosartan may be a better therapeutic option than other ARBs. Comparative studies investigating eprosartan and other ARBs for the treatment of diseases caused by chronic, agonist-independent, AT1 receptor activation are warranted.

Current topics in angiotensin II type 1 receptor research: Focus on inverse agonism, receptor dimerization and biased agonism

Although the octapeptide hormone angiotensin II (Ang II) regulates cardiovascular and renal homeostasis through the Ang II type 1 receptor (AT1R), overstimulation of AT1R causes various human diseases, such as hypertension and cardiac hypertrophy. Therefore, AT1R blockers (ARBs) have been widely used as therapeutic drugs for these diseases. Recent basic research and clinical studies have resulted in the discovery of interesting phenomena associated with AT1R function. For example, ligand-independent activation of AT1R by mechanical stress and agonistic autoantibodies, as well as via receptor mutations, has been shown to decrease the inverse agonistic efficacy of ARBs, though the molecular mechanisms of such phenomena had remained elusive until recently. Furthermore, although AT1R is believed to exist as a monomer, recent studies have demonstrated that AT1R can homodimerize and heterodimerize with other G-protein coupled receptors (GPCR), altering the receptor signaling properties. Therefore, formation of both AT1R homodimers and AT1R-GPCR heterodimer may be involved in the pathogenesis of human disease states, such as atherosclerosis and preeclampsia. Finally, biased AT1R ligands that can preferentially activate the β-arrestin-mediated signaling pathway have been discovered. Such β-arrestin-biased AT1R ligands may be better therapeutic drugs for cardiovascular diseases. New findings on AT1R described herein could provide a conceptual framework for application of ARBs in the treatment of diseases, as well as for novel drug development. Since AT1R is an extensively studied member of the GPCR superfamily encoded in the human genome, this review is relevant for understanding the functions of other members of this superfamily.

Angiotensin II Peptide Vaccine Protects Ischemic Brain Through Reducing Oxidative Stress

Background and Purpose—

Medication nonadherence is one of major risk factors for the poor outcome in ischemic stroke. Vaccination is expected to solve such a problem because of its long-lasting effects, but its effect on ischemic brain damage is still unknown. Here, we focused on vaccination for renin–angiotensin system and examined the effects of angiotensin II (Ang II) peptide vaccine in permanent middle cerebral artery occlusion model in rats.

Methods—

Male Wistar rats were exposed to permanent middle cerebral artery occlusion after 3× injections of Ang II peptide vaccine, and the serum or brain level of anti–Ang II antibody was examined. The effects of the vaccine were evaluated by differences in infarction volume, brain renin–angiotensin system components, and markers for neurodegeneration and oxidative stress.

Results—

Ang II vaccination successfully produced anti–Ang II antibodies in serum without concomitant change in blood pressure. Sufficient production of serum anti–Ang II antibody led to reduction of infarct volume and induced the penetration of anti–Ang II antibody in ischemic hemisphere, with suppressed expression of Ang II type 1 receptor mRNA. Vaccinated rats with sufficient antibody production showed the reduction of Fluoro-Jade B–positive cells, spectrin fragmentation, 4-hydroxynonenal-positive cells, and Nox 2 mRNA expression.

Conclusions—

Our findings indicate that Ang II vaccination exerts neuroprotective and antioxidative effects in cerebral ischemia, with renin–angiotensin system blockade by penetration of anti–Ang II antibodies into ischemic brain lesion. Ang II peptide vaccination could be a promising approach to treat ischemic stroke.

Efficacy of Calcium Channel Blockers Versus Other Classes of Antihypertensive Medication in the Treatment of Hypertensive Patients With Previous Stroke and/or Coronary Artery Disease: A Systematic Review and Meta-Analysis

Hypertensive patients, such as those with established coronary artery disease (CAD) or those who have suffered a stroke, are at increased risk of morbidity and mortality. This systematic literature review and meta-analysis assesses the long-term effects of calcium channel blockers (CCBs) compared with other classes of antihypertensive medications on major cardiovascular (CV) outcomes in these high-risk subgroups of hypertensive patients. Randomized, active controlled parallel group trials were included if they compared CCBs with α-blockers, β-blockers, angiotensin II receptor blockers, angiotensin-converting enzyme inhibitors, or diuretics, had a follow-up of ≥6 months, and had assessments of blood pressure (BP) and CV events [all-cause death, CV death, major CV events (myocardial infarction, MI; congestive heart failure, CHF; stroke; and CV death), MI, stroke, or CHF] in patients with baseline systolic/diastolic BP ≥140/≥90 mm Hg with either concomitant previous stroke and/or CAD. The final dataset included 19 publications reporting on 7 unique trials. In hypertensive patients with previous stroke, there was no difference between CCBs and comparators for any CV outcome. In those with CAD, there was no difference for all-cause death, CV death, major CV events, and MI for CCBs relative to comparators; however, a reduction in the risk of stroke and an increase in the risk of CHF were seen. For BP lowering, CCBs were at least as efficacious as comparators. The findings of our systematic review and analysis add to the body of evidence for the use of CCBs for the long-term treatment of hypertension in difficult-to-treat high CV risk populations.

Structure-Function Basis of Attenuated Inverse Agonism of Angiotensin II Type 1 Receptor Blockers for Active-State Angiotensin II Type 1 Receptor

Ligand-independent signaling by the angiotensin II type 1 receptor (AT1R) can be activated in clinical settings by mechanical stretch and autoantibodies as well as receptor mutations. Transition of the AT1R to the activated state is known to lower inverse agonistic efficacy of clinically used AT1R blockers (ARBs). The structure-function basis for reduced efficacy of inverse agonists is a fundamental aspect that has been understudied not only in relation to the AT1R but also regarding other homologous receptors. Here, we demonstrate that the active-state transition in the AT1R indeed attenuates an inverse agonistic effect of four biphenyl-tetrazole ARBs through changes in specific ligand-receptor interactions. In the ground state, tight interactions of four ARBs with a set of residues (Ser109(TM3), Phe182(ECL2), Gln257(TM6), Tyr292(TM7), and Asn295(TM7)) results in potent inverse agonism. In the activated state, the ARB-AT1R interactions shift to a different set of residues (Val108(TM3), Ser109(TM3), Ala163(TM4), Phe182(ECL2), Lys199(TM5), Tyr292(TM7), and Asn295(TM7)), resulting in attenuated inverse agonism. Interestingly, V108I, A163T, N295A, and F182A mutations in the activated state of the AT1R shift the functional response to the ARB binding toward agonism, but in the ground state the same mutations cause inverse agonism. Our data show that the second extracellular loop is an important regulator of the functional states of the AT1R. Our findings suggest that the quest for discovering novel ARBs, and improving current ARBs, fundamentally depends on the knowledge of the unique sets of residues that mediate inverse agonistic potency in the two states of the AT1R.

Interplay between brain stem angiotensins and monocyte chemoattractant protein-1 as a novel mechanism for pressor response after ischemic stroke

Pressor response after stroke commonly leads to early death or susceptibility to stroke recurrence, and detailed mechanisms are still lacking. We assessed the hypothesis that the renin-angiotensin system contributes to pressor response after stroke by differential modulation of the pro-inflammatory chemokine monocyte chemoattractant protein-1 (MCP-1) in the rostral ventrolateral medulla (RVLM), a key brain stem site that maintains blood pressure. We also investigated the beneficial effects of a novel renin inhibitor, aliskiren, against stroke-elicited pressor response. Experiments were performed in male adult Sprague-Dawley rats. Stroke induced by middle cerebral artery occlusion elicited significant pressor response, accompanied by activation of angiotensin II (Ang II)/type I receptor (AT1R) and AT2R signaling, depression of Ang-(1-7)/MasR and Ang IV/AT4R cascade, alongside augmentation of MCP-1/C-C chemokine receptor 2 (CCR2) signaling and neuroinflammation in the RVLM. Stroke-elicited pressor response was significantly blunted by antagonism of AT1R, AT2R or MCP-1/CCR2 signaling, and eliminated by applying Ang-(1-7) or Ang IV into the RVLM. Furthermore, stroke-activated MCP-1/CCR2 signaling was enhanced by AT1R and AT2R activation, and depressed by Ang-(1-7)/MasR and Ang IV/AT4R cascade. Aliskiren inhibited stroke-elicited pressor response via downregulating MCP-1/CCR2 activity and reduced neuroinflammation in the RVLM; these effects were potentiated by Ang-(1-7) or Ang IV. We conclude that whereas Ang II/AT1R or Ang II/AT2R signaling in the brain stem enhances, Ang-(1-7)/MasR or Ang IV/AT4R antagonizes pressor response after stroke by differential modulations of MCP-1 in the RVLM. Furthermore, combined administration of aliskiren and Ang-(1-7) or Ang IV into the brain stem provides more effective amelioration of stroked-induced pressor response.

Association of chronic kidney disease with cerebral microbleeds in patients with primary intracerebral hemorrhage

BACKGROUND AND PURPOSE

To investigate the relationship between chronic kidney disease (CKD) and MRI-defined cerebral microbleeds (CMB), a harbinger of future intracerebral hemorrhage (ICH), among patients with a recent history of primary ICH.

METHODS

Using data from a predominantly black cohort of patients with a recent ICH-enrolled in an observational study between September 2007 and June 2011, we evaluated the association between CKD (defined as estimated low glomerular filtration rate<60 mL/min per 1.73 m(2)) and CMB on gradient-echo MRI. Multivariable models were generated to determine the contribution of CKD to the presence, number, and location of CMB.

RESULTS

Of 197 subjects with imaging data, mean age was 59 years, 48% were women, 73% were black, 114 (58%) had ≥1 CMBs, and 52 (26%) had CKD. Overall, CKD was associated with presence of CMB (adjusted odds ratio, 2.70; 95% confidence interval [CI], 1.10-6.59) and number of CMB (adjusted relative risk, 2.04; 95% CI, 1.27-3.27). CKD was associated with CMB presence (adjusted odds ratio, 3.44; 95% CI, 1.64-7.24) and number (adjusted relative risk, 2.46; 95% CI, 1.11-5.42) in black patients, but not CMB presence (adjusted odds ratio, 3.00; 95% CI, 0.61-14.86) or number (adjusted relative risk, 1.03; 95% CI: 0.22-4.89) in non-Hispanic white patients (interactions by race were statistically not significant).

CONCLUSIONS

CKD is associated with a greater presence and number of CMB in ICH patients, particularly in patients of black race. Future studies should assess whether low estimated glomerular filtration rate may be a CMB risk marker or potential therapeutic target for mitigating the development of CMB.