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Exogenous estrogens and progestins may affect the components of the renin–angiotensin–aldosterone system (RAAS). Changes in ventricular blood volume are associated with increased secretion of N-terminal pro-hormone B-type natriuretic peptide (NT-proBNP), which may also be affected by hormonal contraceptives. In this study, we aimed to compare components of the RAAS and NT-proBNP between groups using different hormonal contraceptives, including the combination pill, the injection or implant, and controls (no contraception) in black and white women of fertile age (20 – 30 years). Secondly, we determined whether blood pressure and NT-proBNP are associated with the RAAS components. We included 397 black and white women not using contraceptives, 120 using the combination pill, and 103 receiving an injection/implant. RAAS Triple-A analysis was carried out with LC-MS/MS quantification, and blood pressure measurements (ABPM) taken over 24 h. We found that serum aldosterone was higher (475.7 vs. 249.2 pmol/L; p

Small interfering RNA (siRNA) targeting liver angiotensinogen (AGT) lowers blood pressure, but its effectiveness in hypertensive chronic kidney disease is unknown. Considering that the kidney may generate its own AGT, we assessed the effectiveness of liver-targeted AGT siRNA in the 5/6th Nx (5/6th nephrectomy) rat—a hypertensive chronic kidney disease model. Five weeks after 5/6th Nx (baseline), rats were subjected to vehicle, AGT siRNA, AGT siRNA+losartan, losartan, or losartan+captopril. Baseline mean arterial pressure was 160±6 mm Hg. Over the course of 4 weeks, mean arterial pressure increased further by ≈15 mm Hg during vehicle treatment. This rise was prevented by AGT siRNA. Losartan reduced mean arterial pressure by 37±6 mm Hg and increased plasma Ang (angiotensin) II. Both AGT siRNA and captopril suppressed these effects of losartan, suggesting that its blood pressure–lowering effect relied on stimulation of vasodilator Ang II type 2 receptors by high Ang II levels. Proteinuria and cardiac hypertrophy increased with vehicle, and these increases were comparably abrogated by all treatments. No intervention improved glomerular filtration rate, while siRNA and losartan equally diminished glomerulosclerosis. AGT siRNA±losartan reduced plasma AGT by >95%, and this was accompanied by almost complete elimination of Ang II in kidney and heart, without decreasing renal AGT mRNA. Multiple linear regression confirmed both mean arterial pressure and renal Ang II as independent determinants of proteinuria. In conclusion, AGT siRNA exerts renoprotection in the 5/6th Nx model in a blood pressure–independent manner. This relies on the suppression of renal Ang II formation from liver-derived AGT. Consequently, AGT siRNA may prove beneficial in human chronic kidney disease.

Background The myocardium exhibits an adaptive tissue-specific renin-angiotensin system (RAS), and local dysbalance may circumvent the desired effects of pharmacologic RAS inhibition, a mainstay of heart failure with reduced ejection fraction (HFrEF) therapy. Objectives This study sought to investigate human myocardial tissue RAS regulation of the failing heart in the light of current therapy. Methods Fifty-two end-stage HFrEF patients undergoing heart transplantation (no RAS inhibitor: n = 9; angiotensin-converting enzyme [ACE] inhibitor: n = 28; angiotensin receptor blocker [ARB]: n = 8; angiotensin receptor neprilysin-inhibitor [ARNi]: n = 7) were enrolled. Myocardial angiotensin metabolites and enzymatic activities involved in the metabolism of the key angiotensin peptides angiotensin 1-8 (AngII) and Ang1-7 were determined in left ventricular samples by mass spectrometry. Circulating angiotensin concentrations were assessed for a subgroup of patients. Results AngII and Ang2-8 (AngIII) were the dominant peptides in the failing heart, while other metabolites, especially Ang1-7, were below the detection limit. Patients receiving an ARB component (i.e., ARB or ARNi) had significantly higher levels of cardiac AngII and AngIII (AngII: 242 [interquartile range (IQR): 145.7 to 409.9] fmol/g vs 63.0 [IQR: 19.9 to 124.1] fmol/g; p Conclusions The failing heart contains considerable levels of classical RAS metabolites, whereas AngIII might be an unrecognized mediator of detrimental effects on cardiovascular structure. The results underline the importance of pharmacologic interventions reducing circulating AngII actions, yet offer room for cardiac tissue-specific RAS drugs aiming to limit myocardial AngII/AngIII peptide accumulation and actions.

Brain renin–angiotensin system (RAS) activation is thought to mediate deoxycorticosterone acetate (DOCA)-salt hypertension, an animal model for human primary hyperaldosteronism. Here, we determined whether brainstem angiotensin II is generated from locally synthesized angiotensinogen and mediates DOCA-salt hypertension. To this end, chronic DOCA-salt-hypertensive rats were treated with liver-directed siRNA targeted to angiotensinogen, the angiotensin II type 1 receptor antagonist valsartan, or the mineralocorticoid receptor antagonist spironolactone (n = 6–8/group). We quantified circulating angiotensinogen and renin by enzyme-kinetic assay, tissue angiotensinogen by Western blotting, and angiotensin metabolites by LC-MS/MS. In rats without DOCA-salt, circulating angiotensin II was detected in all rats, whereas brainstem angiotensin II was detected in 5 out of 7 rats. DOCA-salt increased mean arterial pressure by 19 ± 1 mmHg and suppressed circulating renin and angiotensin II by >90%, while brainstem angiotensin II became undetectable in 5 out of 7 rats (

The aldosterone/renin ratio (ARR) is currently considered the most reliable approach for case detection of primary aldosteronism (PA). ACE (Angiotensin-converting enzyme) inhibitors are known to raise renin and lower aldosterone levels, thereby causing false-negative ARR results. Because ACE inhibitors lower angiotensin II levels, we hypothesized that the aldosterone/equilibrium angiotensin II (eqAngII) ratio (AA2R) would remain elevated in PA. Receiver operating characteristic curve analysis involving 60 patients with PA and 40 patients without PA revealed that the AA2R was not inferior to the ARR in screening for PA. When using liquid chromatography-tandem mass spectrometry to measure plasma aldosterone concentration, the predicted optimal AA2R cutoff for PA screening was 8.3 (pmol/L)/(pmol/L). We then compared the diagnostic performance of the AA2R with the ARR among 25 patients with PA administered ramipril (5 mg/day) for 2 weeks. Compared with basally, plasma levels of equilibrium angiotensin I (eqAngI) and direct renin concentration increased significantly ( P P P

IL (Interleukin)-1 antagonism decreases blood pressure in obese individuals. The underlying mechanisms are unknown. Based on experimental data, we hypothesized an effect of IL-1 antagonism via modulation of the renin-angiotensin-aldosterone system. In this explorative study, we examined shorter- (2 days) and longer-term effects (4 weeks) of IL-1 antagonism (anakinra/Kineret) on renin-angiotensin system peptide profiles and on hemodynamic parameters assessed by noninvasive measurement in obese (body mass index ≥30 kg/m 2 ) individuals from 2 interventional trials (a prospective interventional trial [n=73] and a placebo controlled-double blinded interventional trial [n=67]). A total of 140 patients were included. Systolic blood pressure decreased after short-term (absolute difference −5.2 mm Hg [95% CI, −8.5 to −1.8]; P =0.0006) and after longer-term treatment with anakinra (absolute difference −3.9 mm Hg [95% CI, −7.59 to −0.21]; P =0.04), with no change in blood pressure in the placebo group. Upon IL-1 antagonism, equilibrium levels of Ang II (angiotensin II), Ang I, aldosterone, and renin remained unchanged. In contrast, Ang (1–7) peptide levels increased after 4 weeks (between-group difference 16.35 pmol/L [95% CI, 1.22–30.17], P =0.03), as well as the Ang (1–7)/Ang II ratio (between-group difference 0.42 [95% CI, 0.17–0.67], P =0.02) in comparison to placebo. Consistently, the stroke systemic vascular resistance index significantly decreased in the anakinra group (between-group difference of −62.65 dyn/sec per cm −5 per m 2 [95% CI, −116.94 to −18.36], P =0.008, consistent with a 25% decrease). IL-1 antagonism increased the vasodilatory Ang (1–7) peptide after 4 weeks of treatment in obese individuals, paralleled by a decrease in peripheral vascular resistance. These findings point to an IL-1 mediated blood pressure-lowering mechanism via modulation of Ang (1–7). Registration— URL: https://www.clinicaltrials.gov . Unique identifiers: NCT02227420 and NCT02672592.

Background Many medications (including most antihypertensives) and physiological factors affect the aldosterone/renin ratio (ARR) when screening for primary aldosteronism (PA). We sought to validate a novel equilibrium angiotensin II (eqAngII) assay and compare correlations between the aldosterone/angiotensin II ratio (AA2R) and the current ARR under conditions affecting the renin-angiotensin system. Methods Among 78 patients recruited, PA was excluded in 22 and confirmed in 56 by fludrocortisone suppression testing (FST). Peripheral levels of eqAngII, plasma renin activity (PRA) and direct renin concentration (DRC) were measured. Results EqAngII showed good consistency with DRC and PRA independent of PA diagnosis, posture, and fludrocortisone administration. EqAngII showed close (P Conclusions Dynamic changes of eqAngII and the AA2R show good consistency and close correlations with renin and the ARR. The eqAngII assay shows better sensitivity than DRC and PRA assays, especially at low concentrations. Whether the AA2R can reduce the impact of some factors that influence the diagnostic power of the ARR warrants further study.

ACE (angiotensin-converting enzyme)-2 as the target for SARS-CoV-2 also negatively regulates the renin-angiotensin system. Pathological activation of ADAM17 (A disintegrin and metalloproteinase-17) may potentiate inflammation and diminish ACE2-mediated tissue protection through proteolytic shedding, contributing to SARS-CoV-2 pathogenesis. We aim to examine plasma soluble ACE2 and angiotensin profiles in relation to outcomes by enrolling consecutive patients admitted for COVID-19 with baseline blood collection at admission and repeated sampling at 7 days. The primary outcome was 90-day mortality, and secondary outcomes were the incidence of end-organ injuries. Overall, 242 patients were included, the median age was 63 (52–74) years, 155 (64.0%) were men, and 57 (23.6%) patients reached the primary end point. Baseline soluble ACE2 was elevated in COVID-19 but was not associated with disease severity or mortality. In contrast, an upward trajectory of soluble ACE2 at repeat sampling was independently associated with an elevated risk of mortality and incidence of acute myocardial injury and circulatory shock. Similarly, an increase in soluble tumor necrosis factor receptor levels was also associated with adverse outcomes. Plasma Ang I, Ang 1-7 (angiotensin 1–7) levels, and the Ang 1-7/Ang II (angiotensin II) ratio were elevated during SARS-CoV-2 infection related to downregulation of ACE activity at baseline. Moreover, patients having an upward trajectory of soluble ACE2 were characterized by an imbalance in the Ang 1-7/Ang II ratio. The observed dysregulation of ACE2 and angiotensin peptides with disease progression suggest a potential role of ADAM17 inhibition and enhancing the beneficial Ang 1-7/Mas axis to improve outcomes against SARS-CoV-2 infection.

Uncontrolled hypertension is caused by various factors including compliance issues, patient specific drug uptake and elimination profiles or secondary forms of hypertension, resulting in blood pressure control rates of less that 50%. RAAS Triple-A profiling is a high-throughput mass-spectrometry based assay for Angiotensin I (Ang I), Angiotensin II (Ang II) and Aldosterone in serum samples. Hormone levels are used to calculate markers for plasma-renin-activity (PRA-S), plasma angiotensin-converting-enzyme activity (ACE-S) and adrenal aldosterone secretion (AA2-Ratio). The integrated analysis of these molecular markers together with drug prescription information allows to identify the underlying cause of uncontrolled hypertension, including primary aldosteronism and insufficiency in drug adherence or dosing for ACE inhibitors (ACEi) and angiotensin receptor blockers (ARBs). 500 participants with prescribed antihypertensive drugs were selected from the “Cooperative Health Research in South Tyrol” (CHRIS) study, a population-based study from an Alpine rural environment. Five age- and sex-matched groups (N=100 each) selected were individuals on single therapy with ARBs, ACEi or beta blockers, and on single pill dual therapy of ACEi or ARBs in combination with diuretics. Three age and sex-matched control groups of 100 participants each were included, being normotensive, hypertensive (treated with non-antihypertensive drugs) and hypertensive participants without any prescribed medication. RAAS Triple-A analysis was performed in all individuals and reference values for Ang I, Ang II, Aldosterone, PRA-S, ACE-S and AA2-Ratio were established in appropriate sub-populations. Drug monitoring by LC-MS/MS based quantification of anti-hypertensive drugs in serum was used as a gold standard to determine cut-off values for compliance with ARB and ACEi therapy and ROC analysis was performed using angiotensin-based biomarkers.

Supplemental Digital Content is available in the text., Combined inhibition of NEP (neutral endopeptidase) and ACE (angiotensin-converting enzyme), without unwanted effects, remains an attractive therapeutic strategy in cardiovascular medicine. Omapatrilat, a dual NEP inhibitor–ACE inhibitor, was a promising antihypertensive drug but failed in trials due to angioedema, an effect possibly caused by inhibition of both the N- and C-domains of ACE. Here, we aimed to determine whether lisinopril-tryptophan (lisW-S), a C-domain specific ACE inhibitor that preserves the N-domain catalytic activity, together with sacubitril (NEP inhibitor), differentially influences cardiovascular function and vascular permeability in hypertension compared with omapatrilat and lisinopril+sacubitril which inhibits both the ACE C- and N-domains. Ang II (angiotensin II)–dependent hypertensive mice (transgenic mice expressing active human renin in the liver [also known as LinA3]) received vehicle, sacubitril, lisW-S, lisinopril, lisinopril+sacubitril, or lisW-S+sacubitril for 4 weeks. Systolic blood pressure was increased in LinA3 mice, along with cardiac hypertrophy/dysfunction, impaired endothelium-dependent vasorelaxation, hypercontractile responses, vascular remodeling, and renal inflammation. LisW-S+sacubitril, lisinopril+sacubitril, and omapatrilat reduced systolic blood pressure and normalized cardiovascular remodeling and vascular hypercontractile responses in LinA3 mice. Although lisinopril+sacubitril and omapatrilat improved Ach-induced vasorelaxation, lisW-S+sacubitril had no effect. Endothelial permeability (Evans Blue assessment) was increased in omapatrilat but not in LisW-S+sacubitril–treated mice. In conclusion, lisW-S combined with sacubitril reduced systolic blood pressure and improved cardiac dysfunction in LinA3 mice, similar to omapatrilat but without effects on endothelium-dependent vasorelaxation. Moreover, increased vascular leakage (plasma extravasation) induced by omapatrilat was not evident in mice treated with lisW-S+sacubitril. Targeting ACE C-domain and NEP as a combination therapy may be as effective as omapatrilat in lowering systolic blood pressure, but without inducing vascular permeability and endothelial injury.

Despite the success of renin-angiotensin system (RAS) blockade by angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor (AT1R) blockers, current therapies for hypertension and related cardiovascular diseases are still inadequate. Identification of additional components of the RAS and associated vasoactive pathways, as well as new structural and functional insights into established targets, have led to novel therapeutic approaches with the potential to provide improved cardiovascular protection and better blood pressure control and/or reduced adverse side effects. The simultaneous modulation of several neurohumoral mediators in key interconnected blood pressure–regulating pathways has been an attractive approach to improve treatment efficacy, and several novel approaches involve combination therapy or dual-acting agents. In addition, increased understanding of the complexity of the RAS has led to novel approaches aimed at upregulating the ACE2/angiotensin-(1-7)/Mas axis to counter-regulate the harmful effects of the ACE/angiotensin II/angiotensin III/AT1R axis. These advances have opened new avenues for the development of novel drugs targeting the RAS to better treat hypertension and heart failure. Here we focus on new therapies in preclinical and early clinical stages of development, including novel small molecule inhibitors and receptor agonists/antagonists, less conventional strategies such as gene therapy to suppress angiotensinogen at the RNA level, recombinant ACE2 protein, and novel bispecific designer peptides.

The renin-angiotensin system plays an important role in the development and progression of heart failure (HF). In addition to the classical renin-angiotensin pathway, an alternative pathway produces Angs (angiotensins), which counteract the negative effects of Ang II. We hypothesized that Ang profiling could provide insights into the pathogenesis and prognosis of HF with preserved ejection fraction. We aimed to investigate the effects of Angs on outcome in HF with preserved ejection fraction. Consecutive patients were included into a prospective single-center registry. Clinical, laboratory, and imaging parameters were assessed and serum samples were taken at baseline and measured by mass spectroscopy. Serum equilibrium levels were analyzed in regard to the combined clinical end point of cardiovascular death or HF hospitalization. In total, 155 patients were included during a median follow-up time of 22.5 (interquartile range, 4.0–61.0) months, 52 individuals (34%) reached the combined end point. We identified higher levels of Ang 1–7 and Ang 1–5 as predictors for poor outcome. After adjusting for potential confounding factors, Ang 1–5 remained predictive for poor outcome. In addition to Ang 1–7 and Ang 1–5, the novel ACE (angiotensin-converting enzyme) independent Ang composite marker [Ang 1–7+Ang 1–5] was shown to predict adverse events. We conclude that Angs of the alternative renin-angiotensin system seem to play a role in HF with preserved ejection fraction and are linked to outcome in patients with HF and preserved ejection fraction. Ang 1–5 and the alternative renin-angiotensin system composite marker [Ang 1–7+Ang 1–5] are independent predictors of outcome.

Significance Vascular diseases remain a major health burden, and AAAs lack effective medical therapy. We demonstrate a seminal role for APLN in AAA pathogenesis based on loss-of-function and gain-of-function approaches and included human vascular SMCs and AA tissue obtained from patients. We identified NEP as a dominant inactivating enzyme for native APLN-17. This allowed us to design and synthesize a stable and bioactive APLN analog resistant to NEP degradation that showed profound therapeutic effects against AAA. Our study clearly defines the APLN pathway as a central node in the pathogenesis of AAA and elucidate a therapeutic strategy of enhancing the APLN pathway by using a stable APLN analog to treat AAA., Abdominal aortic aneurysm (AAA) remains the second most frequent vascular disease with high mortality but has no approved medical therapy. We investigated the direct role of apelin (APLN) in AAA and identified a unique approach to enhance APLN action as a therapeutic intervention for this disease. Loss of APLN potentiated angiotensin II (Ang II)-induced AAA formation, aortic rupture, and reduced survival. Formation of AAA was driven by increased smooth muscle cell (SMC) apoptosis and oxidative stress in Apln−/y aorta and in APLN-deficient cultured murine and human aortic SMCs. Ang II-induced myogenic response and hypertension were greater in Apln−/y mice, however, an equivalent hypertension induced by phenylephrine, an α-adrenergic agonist, did not cause AAA or rupture in Apln−/y mice. We further identified Ang converting enzyme 2 (ACE2), the major negative regulator of the renin-Ang system (RAS), as an important target of APLN action in the vasculature. Using a combination of genetic, pharmacological, and modeling approaches, we identified neutral endopeptidase (NEP) that is up-regulated in human AAA tissue as a major enzyme that metabolizes and inactivates APLN-17 peptide. We designed and synthesized a potent APLN-17 analog, APLN-NMeLeu9-A2, that is resistant to NEP cleavage. This stable APLN analog ameliorated Ang II-mediated adverse aortic remodeling and AAA formation in an established model of AAA, high-fat diet (HFD) in Ldlr−/− mice. Our findings define a critical role of APLN in AAA formation through induction of ACE2 and protection of vascular SMCs, whereas stable APLN analogs provide an effective therapy for vascular diseases.

Deletion of the prorenin receptor (PRR) in adipose tissue elevates systolic blood pressure (SBP) and the circulating soluble form of PRR (sPRR) in male mice fed a high-fat (HF) diet. However, sex differences in the contribution of adipose-PRR and sPRR to the regulation of the renin-angiotensin system (RAS) in key organs for blood pressure control are undefined. Therefore, we assessed blood pressure and the systemic and intrarenal RAS status in adipose-PRR knockout (KO) female mice. Blockade of RAS with losartan blunted SBP elevation in HF diet-fed adipose-PRR KO mice. ANG II levels were significantly increased in the renal cortex of HF diet-fed adipose-PRR KO female mice, but not systemically. HF diet-fed adipose-PRR KO mice exhibited higher vasopressin levels, water retention, and lower urine output than wild-type (WT) mice. The results also showed that deletion of adipose-PRR increased circulating sPRR and total hepatic sPRR contents, suggesting the liver as a major source of elevated plasma sPRR in adipose-PRR KO mice. To mimic the elevation of circulating sPRR and define the direct contribution of systemic sPRR to the regulation of the RAS and vasopressin, C57BL/6 female mice fed a standard diet were infused with recombinant sPRR. sPRR infusion increased plasma renin levels, renal and hepatic angiotensinogen expression, and vasopressin. Together, these results demonstrate that the deletion of adipose-PRR induced an elevation of SBP likely mediated by an intrarenal ANG II-dependent mechanism and that sPRR participates in RAS regulation and body fluid homeostasis via its capacity to activate the RAS and increase vasopressin levels. NEW & NOTEWORTHY The elevation of systolic blood pressure appears to be primarily mediated by cortical ANG II in high-fat diet-fed adipose-prorenin receptor knockout female mice. In addition, our data support a role for soluble prorenin receptor in renin-angiotensin system activation and vasopressin regulation.

Background Renin–angiotensin–aldosterone system (RAAS) blockade with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) is the cornerstone of antihypertensive treatment in patients with chronic kidney disease (CKD) and diabetes mellitus. Mineralocorticoid receptor antagonists (MRA) on top of conventional RAAS blockade confer cardio- and renoprotective effects. Yet, the detailed effects of this therapeutic approach on key RAAS effectors have not been elucidated to date. Methods In this exploratory placebo-controlled study, 15 patients with CKD stages 2–3 and albuminuria due to diabetic kidney disease (DKD) were randomized to receive the MRA eplerenone or placebo in addition to ACEi therapy. Employing mass-spectrometry, we quantified plasma angiotensin levels [Ang I, Ang II, Ang-(1–7), Ang-(1–5), Ang III, Ang IV], renin and aldosterone in patients before and after 8 weeks of MRA treatment. Results While blood pressure and kidney function were similar in the placebo and eplerenone treatment group during the study period, distinct differences in RAAS regulation occurred: eplerenone treatment resulted in an increase in plasma renin activity, Ang I and aldosterone concentrations, indicating global RAAS activation. In addition, eplerenone on top of ACEi profoundly upregulated the alternative RAAS effector Ang-(1–7). Conclusions Combined eplerenone and ACEi therapy increases Ang-(1–7) levels in patients with CKD indicating a unique nephroprotective RAAS pattern with considerable therapeutic implications. Supplementary Information The online version contains supplementary material available at 10.1007/s13300-021-01118-7.

Angiotensin II (AngII), a major effector of the renin-angiotensin system, exerts critical roles in regulating vascular function. AngII infusion induces abdominal aortic aneurysms (AAAs) and exacerbates atherosclerosis in hypercholesterolemic mice. We determined the effects of AngII infusion on endogenous AngII regulation and AngII-mediated AAAs and atherosclerosis. AngII infusion increased renal, but not plasma, AngII concentrations in male mice. AngI concentrations were decreased modestly in kidney, but more profoundly in plasma, during AngII infusion. Bovine AngII (DRVYVHPF) has one amino acid difference from mouse AngII (DRVYIHPF) that can be distinguished by LC-MS/MS. Therefore, we determined exogenous versus endogenous peptides in mice infused with bovine AngII. Bovine AngII infusion reduced endogenous renal AngII concentrations. To determine whether the residual endogenous AngII exerted an effect on AAAs and atherosclerosis in mice infused with AngII, aliskiren (a direct renin inhibitor) was administered to AngII-infused male LDL receptor deficient mice. Although aliskiren did not attenuate AAAs in AngII-infused mice, atherosclerotic lesion size was reduced. In conclusion, endogenous AngII concentrations are reduced during AngII infusion but still contribute to atherosclerosis, but not AAA, in AngII-infused hypercholesterolemic mice.

Drugs which interact with the renin angiotensin aldosterone system (RAAS) aim to reduce the negative effects of angiotensin (Ang) II. Treatment with these drugs anticipate a compensatory up-regulation of renin, however, it has been shown that there is a large variability in circulating plasma renin (PRA), even in patients with optimal medical therapy in patients with heart failure (HF) with reduced ejection fraction (HFrEF). Our aim was to measure plasma renin activity (PRA-S), its response to RAAS inhibitor (RAASi) therapies and its effects on outcome in patients with HF with preserved ejection fraction (HFpEF). For this purpose, 150 HFpEF patients were included into a prospective single-center registry. Equilibrium (eq) angiotensin metabolites were measured from serum samples using mass spectroscopy. PRA-S (eqAng I + eqAng II) was calculated and compared in respect to the primary endpoint defined as all-cause death. PRA-S in patients with RAASi therapy was not significantly higher than in patients without RAASi (p = 0.262). Even after adjusting for confounding factors, PRA-S remained predictive for all-cause death in the multivariable model with a hazard ratio of 2.14 (95%CI 1.20–3.82, p = 0.010). We conclude that high PRA-S is associated with poor prognosis in patients with HFpEF, regardless of RAASi treatment, which could ultimately result in hyperactivated RAAS and consecutive negative effects on the cardiovascular and renal system, leading to poor outcome in patients with HFpEF.

Objective The branch of the renin--angiotensin system constituting angiotensin-(1-7) [Ang-(1-7)], the Ang II type 2 receptor, the Mas receptors and the Ang-(1-7)-forming enzyme ACE-2, by counteracting the Ang II type 1 receptor (AT1R)-mediated effects, are held to be cardiovascular protective in several conditions. However, whether Ang-(1-7) and ACE-2 are detectable in human adrenocortical tissues and whether they affect aldosterone and cortisol biosynthesis was unknown. Methods We measured angiotensin peptides with liquid chromatography tandem-mass spectrometry and ACE-2 mRNA with digital droplet (dd)PCR in human aldosterone-producing adenoma (APA) and APA-adjacent tissue obtained from patients with primary aldosteronism. We also investigated the effects of Ang-(1-7) and the ACE-2 activator diminazene aceturate (DIZE) on aldosterone synthase (CYP11B2) and 11β-hydroxylase (CYP11B1) gene expression, in the absence or presence of the AT1R antagonist irbesartan, or of the MasR antagonist A779. Results APA and APA-adjacent adrenocortical tissues express ACE-2 mRNA and contain detectable amounts of Ang II and Ang-(2-8), but not of Ang I, Ang-(1-5), Ang (3-8) and Ang-(1-7). Ang-(1-7) did not blunt CYP11B1 and CYP11B2 mRNA both under unstimulated and under Ang II-stimulated conditions. At supraphysiological concentrations (10-4 mol/l), Ang-(1-7) stimulated both CYP11B1 and CYP11B2 mRNA via the AT1R. The ACE-2 activator DIZE increased by 1.5-fold ACE-2 mRNA but did not blunt Ang II- upregulated CYP11B1 and CYP11B2 expression. Conclusion These results do not support the hypothesis that the ACE-2/Ang-(1-7)/MasR axis play a protective role by counteracting enhanced aldosterone secretion in humans.

(1) Background: Recently, influences of antihypertensive treatment on the renin–angiotensin–aldosterone system (RAAS) has gained attention, regarding a possible influence on inflammatory and anti-inflammatory pathways. We aimed to study the effects of newly initiated antihypertensive drugs on angiotensin (Ang) II and Ang (1–7) as representers of two counter-regulatory axes. (2) Methods: In this randomized, open-label trial investigating RAAS peptides after the initiation of perindopril, olmesartan, amlodipine, or hydrochlorothiazide, Ang II and Ang (1–7) equilibrium concentrations were measured at 8 a.m. and 12 a.m. at baseline and after four weeks of treatment. Eighty patients were randomized (1:1:1:1 fashion). (3) Results: Between the four substances, we found significant differences regarding the concentrations of Ang II (p &lt, 0.0005 for 8 a.m., 12 a.m.) and Ang (1–7) (p = 0.019 for 8 a.m., &lt, 0.0005 for 12 a.m.) four weeks after treatment start. Ang II was decreased by perindopril (p = 0.002), and increased by olmesartan (p &lt, 0.0005), amlodipine (p = 0.012), and hydrochlorothiazide (p = 0.001). Ang (1–7) was increased by perindopril and olmesartan (p = 0.008/0.002), but not measurably altered by amlodipine and hydrochlorothiazide (p = 0.317/ 0.109). (4) Conclusion: The initiation of all first line antihypertensive treatments causes early and distinct alterations of equilibrium angiotensin levels. Given the additional AT1R blocking action of olmesartan, RAAS peptides shift upon initiation of perindopril and olmesartan appear to work in favor of the anti-inflammatory axis compared to amlodipine and hydrochlorothiazide.

Development of liver fibrosis is paralleled by contraction of hepatic stellate cells (HSC), the main profibrotic hepatic cells. Yet, little is known about the interplay of neprilysin (NEP) and its substrate neuropeptide Y (NPY), a potent enhancer of contraction, in liver fibrosis. We demonstrate that HSC are the source of NEP. Importantly, NPY originates majorly from the splanchnic region and is cleaved by NEP in order to terminate contraction. Interestingly, NEP-deficiency (Nep-/-) showed less fibrosis but portal hypertension upon liver injury in two different fibrosis models in mice. We demonstrate the incremental benefit of Nep-/- in addition to AT1R blocker (ARB) or ACE-inhibitors for fibrosis and portal hypertension. Finally, oral administration of Entresto®, a combination of ARB and NEP-inhibitor, decreased hepatic fibrosis and portal pressure in mice. These results provide a mechanistic rationale for translation of NEP-AT1R-blockade in human liver fibrosis and portal hypertension.

Background Established heart failure (HF) treatments have shown no effects in HF and preserved ejection fraction (HFpEF). Subgroup analyses of the HFpEF populations suggest that certain patients benefit from HF treatments. This underlines the importance of individualized therapy regimens in HFpEF. Sodium-glucose transporter 2 (SGLT-2) inhibitors are emerging as a promising treatment of HF. The mechanisms leading to improved outcomes include 1) treatment of diabetes, 2) osmodiuresis preventing volume overload, 3) enhancement of the cardio protective Angiotensin (Ang) 1–7 pathway, instead of Ang II. We aimed to characterize patients by factors which are modified by SGLT-2 inhibitors to identify individuals who may benefit from these drugs. Methods HFpEF patients were included in a single center registry. Baseline evaluation included assessment of HbA1c, fluid status measured by body composition monitor and plasma angiotensin concentration. A “SGLT-2 score” with a maximum of 3 points was calculated using the following parameters: 1) HbA1c >6.5%, 2) overhydration, defined as a fluid overload of >1,5L and 3) plasma renin activity (PRA) levels above the median as a parameter of over-all RAS activity. Primary outcome was defined as all-cause death or HF hospitalization. All parameters used in the “SGLT-2 score” were independently predictive for the chosen endpoint. Kaplan Meier analyses was used to show the association between the score and outcomes. Results 90 patients were included in this registry. Median HbA1c was 6.0%, median fluid status was 1.2L and the median Ang II levels in the “high PRA-group” were 5.35.1 pmol/L. After a mean follow up time of 44.0±38.7 months, 60 patients (66.6%) reached the endpoint. Kaplan Meier analysis showed an association between SGLT-2 score and outcome (p=0.003). Conclusion Patients with HbA1c >6.5%, overhydration and high RAS activity have poor outcomes. We propose the future use of this score to identify a subgroup of HFpEF patients who may benefit from SGLT-2 inhibitors. Kaplan Meier analysis Funding Acknowledgement Type of funding source: None

Background ACE2 and Ang 1–7 are endogenous negative regulators of the renin-angiotensin system (RAS) exerting cardioprotective effects in models of heart failure (HF). Recombinant ACE2 markedly increased plasma Ang 1–7 and lowered Ang II levels in clinical trials. Elevated plasma ACE2 activity is associated with adverse outcomes in HF patients. However, the direct effects of systemic and tissue ACE2 activation on angiotensin peptides in relation to long-term HF outcomes has yet to be examined. Purpose To generate insights into the ACE2 mediated cardioprotective arm through the relative levels of its substrates and products using the plasma Ang 1–7/Ang II ratio, and assess its prognostic utility in HF patients. Methods 110 HF patients were prospectively enrolled from outpatient clinics and the emergency department. Comprehensive circulating and equilibrium levels of plasma angiotensin peptides were assessed using novel liquid chromatography-mass spectrometry/mass spectroscopy techniques. Plasma aldosterone, BNP, active renin activity and clinical profiles were captured at baseline. Patients were stratified into above and below median cohorts based on equilibrium and circulating levels of Ang 1–7/Ang II ratio, as a surrogate for ACE2 functionality. During a median follow-up of 5.1±0.8 years, composite clinical outcomes were assessed through all-cause in-patient hospitalizations and mortality. Results Circulating and equilibrium angiotensin peptide levels strongly correlated in our patient cohort. All-cause mortality for HF patients with equilibrium Ang 1–7/Ang II ratios above the median showed higher survival rates compared to below median patients (76.4% vs. 50.9%; p=0.004); similar results were observed for circulating Ang 1–7/Ang II ratios (72.7% vs. 54.5%; p=0.041). Adjusting for covariates, elevated equilibrium (HR: 0.24; 95% CI: 0.09 to 0.69; p=0.008) and circulating (HR: 0.35; 95% CI: 0.13 to 0.94; p=0.036) Ang 1–7/Ang II ratios was associated with improved survival. Lower hospitalization duration was also associated with elevated equilibrium (p Conclusions We extensively profiled plasma angiotensin peptides in HF patients and identified elevated ACE2 signature, reflected through the Ang 1–7/Ang II ratio, as an independent and incremental predictor of beneficial outcomes, higher survival rate, and decreased hospitalization duration. These findings provide important clinical evidence supporting strategies aiming to promote the beneficial ACE2/Ang 1–7/Mas receptor axis concurrent with RAS blockade therapies inhibiting the detrimental ACE/Ang II/AT1 receptor axis. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Alberta Innovates, Canadian Institute of Health Research

Background: ACE2 (angiotensin-converting enzyme 2) and Ang 1–7 (angiotensin 1–7) are endogenous negative regulators of the renin-angiotensin system exerting cardioprotective effects in models of heart failure. Recombinant human ACE2 markedly increased plasma Ang 1–7 and lowered Ang II levels in phase II clinical trials. We hypothesize that the dynamic state of this renin-angiotensin system protective arm could influence long-term outcomes in patients with heart failure. Methods: One hundred ten patients with heart failure were prospectively enrolled from our outpatient clinic and the emergency department. Comprehensive circulating and equilibrium levels of plasma angiotensin peptide profiles were assessed using novel liquid chromatography-mass spectrometry/mass spectroscopy techniques. Plasma aldosterone, B-type natriuretic peptide, active renin concentration, and clinical profiles were captured at baseline. During a median follow-up of 5.1 years (interquartile range, 4.7–5.7 years), composite clinical outcomes were assessed using all-cause in-patient hospitalizations and mortality. Results: Circulating and equilibrium angiotensin peptide levels strongly correlated in our patient cohort. Adjusting for covariates, elevated equilibrium (hazard ratio, 0.38 [95% CI, 0.18–0.81] P =0.012), and circulating (hazard ratio, 0.38 [95% CI, 0.18–0.80] P =0.011) Ang 1–7/Ang II ratios were associated with improved survival. Lower hospitalization duration was also associated with elevated equilibrium ( P P =0.023) Ang 1–7/Ang II ratios. Importantly, individual Ang 1–7 and Ang II peptide levels failed to predict all-cause mortality or hospitalization duration in our patient cohort. Conclusions: We extensively profiled plasma angiotensin peptides in patients with heart failure and identified elevated Ang 1–7/Ang II ratio, as an independent and incremental predictor of beneficial outcomes, higher survival rate, and decreased hospitalization duration. These findings provide important clinical evidence supporting strategies aiming to promote the beneficial Ang 1–7/Mas axis concurrent with renin-angiotensin system blockade therapies inhibiting the detrimental Ang II/AT 1 receptor axis.

Rationale: Kidney homeostasis is critically determined by the coordinated activity of the renin-angiotensin system (RAS), including the balanced synthesis of its main effector peptides Ang (angiotensin) II and Ang (1–7). The condition of enzymatic overproduction of Ang II relative to Ang (1–7) is termed RAS dysregulation and leads to cellular signals, which promote hypertension and organ damage, and ultimately progressive kidney failure. ACE2 (angiotensin-converting enzyme 2) and NEP (neprilysin) induce the alternative, and potentially reno-protective axis by enhancing Ang (1–7) production. However, their individual contribution to baseline RAS balance and whether their activities change in chronic kidney disease (CKD) has not yet been elucidated. Objective: To examine whether NEP-mediated Ang (1–7) generation exceeds Ang II formation in the healthy kidney compared with diseased kidney. Methods and Results: In this exploratory study, we used liquid chromatography-tandem mass spectrometry to measure Ang II and Ang (1–7) synthesis rates of ACE, chymase and NEP, ACE2, PEP (prolyl-endopeptidase), PCP (prolyl-carboxypeptidase) in kidney biopsy homogenates in 11 healthy living kidney donors, and 12 patients with CKD. The spatial expression of RAS enzymes was determined by immunohistochemistry. Healthy kidneys showed higher NEP-mediated Ang (1–7) synthesis than Ang II formation, thus displaying a strong preference towards the reno-protective alternative RAS axis. In contrast, in CKD kidneys higher levels of Ang II were recorded, which originated from mast cell chymase activity. Conclusions: Ang (1–7) is the dominant RAS peptide in healthy human kidneys with NEP rather than ACE2 being essential for its generation. Severe RAS dysregulation is present in CKD dictated by high chymase-mediated Ang II formation. Kidney RAS enzyme analysis might lead to novel therapeutic approaches for CKD.

Dipeptidyl peptidase 3 (DPP3) is a zinc-dependent hydrolase involved in degrading oligopeptides with 4–12 amino acid residues. It has been associated with several pathophysiological processes, including blood pressure regulation, pain signaling, and cancer cell defense against oxidative stress. However, the physiological substrates and the cellular pathways that are potentially targeted by DPP3 to mediate these effects remain unknown. Here, we show that global DPP3 deficiency in mice (DPP3−/−) affects the renin–angiotensin system (RAS). LC–MS–based profiling of circulating angiotensin peptides revealed elevated levels of angiotensin II, III, IV, and 1–5 in DPP3−/− mice, whereas blood pressure, renin activity, and aldosterone levels remained unchanged. Activity assays using the purified enzyme confirmed that angiotensin peptides are substrates for DPP3. Aberrant angiotensin signaling was associated with substantially higher water intake and increased renal reactive oxygen species formation in the kidneys of DPP3−/− mice. The metabolic changes and altered angiotensin levels observed in male DPP3−/− mice were either absent or attenuated in female DPP3−/− mice, indicating sex-specific differences. Taken together, our observations suggest that DPP3 regulates the RAS pathway and water homeostasis by degrading circulating angiotensin peptides.

Primary aldosteronism (PA) is recognized as the most frequent cause of secondary hypertension, and its screening is expected to become a routine evaluation in most patients with hypertension. The interference of antihypertensive therapies with the aldosterone-to-renin ratio (ARR) during screening process is a major confounder. Renin-Angiotensin-Aldosterone System Triple-A (RAAS Triple-A) testing is a novel mass-spectrometry based assay for quantification of Angiotensin I (Ang I), Angiotenisn II (Ang II) and Aldosterone in a single sample of serum by RAAS equilibrium analysis. Obtained hormone levels are used to calculate markers for plasma-renin-activity (PRA-S, Ang I + Ang II), plasma angiotensin-converting-enzyme activity (ACE-S, Ang II-to-Ang I ratio) and adrenal function (AA2-Ratio, Aldosterone-to-Ang II ratio), with the latter being useful to screen for PA in hypertension. We performed a comparative evaluation of the diagnostic performance of the AA2-Ratio and 5 renin-based diagnostic ratios, differing in methods to determine aldosterone levels and renin activity in a cohort of 110 patients with hypertension (33 patients with confirmed primary aldosteronism and 77 with essential hypertension). All ratios showed comparable areas under the curves ranging between 0.924 and 0.970 without significant differences between each other. The evaluation of the ACE-S revealed persistent drug intake in some patients as cause for suppressed renin-based diagnostic ratios, while the AA2-Ratio remained unaffected. The Youden index optimal cutoff value for the AA2-Ratio was 6.6 ([pmol/L]/[pmol/L]) with a sensitivity of 90% and a specificity of 93%, proving non-inferiority compared with the ARR while pointing to the potential for an interference-free application in patients under ACE inhibitor therapy. This study shows for the first time the accuracy and reliability of RAAS Triple-A analysis for the screening of primary aldosteronism that can be applied in clinical routine.

Context Current threshold values for primary aldosteronism (PA) diagnostic testing are based on measuring aldosterone (PAC) using immunoassays. Quantification of PAC by liquid chromatography-tandem mass spectrometry (LC-MS/MS) yields lower values. Objective To compare aldosterone measurement by radioimmunoassay (RIA) with LC-MS/MS and evaluate performances of proposed LC-MS/MS–specific cutoffs for PA screening and confirmatory testing. Patients and Intervention Forty-one patients underwent aldosterone/renin ratio (ARR) testing to screen for, and fludrocortisone suppression testing (FST) to confirm or exclude, PA. Renin (DRC) was measured by chemiluminescent immunoassay. Results Median serum PACLC-MS/MS was 27.8% lower (P < 0.05) than plasma PACRIA in 164 pairs of FST samples. A positive correlation (Spearman coefficient, 0.894, P < 0.01; Pearson r coefficient, 0.861, P < 0.01) was observed between the two assays. Thirty-seven patients showed consistent FST diagnoses (29 positive, 8 negative), whereas four showed inconsistent FSTs by the two assays. Good agreement (κ coefficient, 0.736; P < 0.01) was observed between the current FST diagnostic PACRIA cutoff of 165 pmol/L and the proposed PACLC-MS/MS cutoff of 133 pmol/L. Among 37 patients with consistent FST results, no differences were observed in sensitivity (89.7% vs 93.1%) or specificity (87.5% vs 87.5%) for PA screening between the current ARR cutoff of 70 pmol/mU (PACRIA/DRC) and the proposed cutoff of 55 pmol/mU (PACLC-MS/MS/DRC). Conclusions Adjustment of the current cutoffs for PA diagnostic testing is necessary if PAC is measured by LC-MS/MS. Our preliminary results suggest that the proposed LC-MS/MS cutoffs for ARR and FST perform as well as current RIA cutoffs.

Significant neuroprotective effects of angiotensin II type 2 (AT 2 ) receptor (AT 2 receptor) agonists in ischemic stroke have been previously demonstrated in multiple studies. However, the routes of agonist application used in these pre-clinical studies, direct intracerebroventricular (ICV) and systemic administration, are unsuitable for translation into humans; in the latter case because AT 2 receptor agonists are blood-brain barrier (BBB) impermeable. To circumvent this problem, in the current study we utilized the nose-to-brain (N2B) route of administration to bypass the BBB and deliver the selective AT 2 receptor agonist Compound 21 (C21) to näive rats or rats that had undergone endothelin 1 (ET-1)-induced ischemic stroke. The results obtained from the present study indicated that C21 applied N2B entered the cerebral cortex and striatum within 30 min in amounts that are therapeutically relevant (8.4-9 nM), regardless of whether BBB was intact or disintegrated. C21 was first applied N2B at 1.5 h after stroke indeed provided neuroprotection, as evidenced by a highly significant, 57% reduction in cerebral infarct size and significant improvements in Bederson and Garcia neurological scores. N2B-administered C21 did not affect blood pressure or heart rate. Thus, these data provide proof-of-principle for the idea that N2B application of an AT 2 receptor agonist can exert neuroprotective actions when administered following ischemic stroke. Since N2B delivery of other agents has been shown to be effective in certain human central nervous system diseases, the N2B application of AT 2 receptor agonists may become a viable mode of delivering these neuroprotective agents for human ischemic stroke patients.

BACKGROUND Blockade of the renin–angiotensin system (RAS) represents a main strategy in the therapy of heart failure with reduced ejection fraction (HFrEF), but the role of active renin concentration (ARC) for guiding therapy in the presence of an RAS blockade remains to be established. This study assessed angiotensin profiles of HFrEF patients with distinct RAS activations as reflected by ARC. METHODS Two cohorts of stable chronic HFrEF patients on optimal medical treatment (OMT) were enrolled. We assessed ARC and all known circulating angiotensin metabolites, including AngI and AngII, by mass spectrometry to investigate the effect of different therapy modalities. Low- and high-renin HFrEF patients were identified by ARC screening and subsequently characterized by their angiotensin profiles. RESULTS Although different modes of RAS blockade resulted in typical AngII/AngI ratios, concentrations of (AngI+AngII) strongly correlated with ARC [r = 0.95, P < 0.001] independent of therapy mode. Despite RAS blocker treatment with angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin II type 1 receptor blockers (ARB), which anticipated ARC upregulation, about 30% of patients showed lower/normal range ARC values. ARC did not correlate with N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations and New York Heart Association (NYHA) stages. Angiotensin concentrations were profoundly diminished for the low-ARC group compared with the high-ARC group: AngI [6.4 ng/L (IQR: 2.1–12.5) vs 537.9 ng/L (IQR: 423.1–728.4), P < 0.001 for ACE-I; and 4.5 ng/L (IQR: 1.4–11.2) vs 203.0 ng/L (IQR: 130.2–247.9), P = 0.003 for ARB] and AngII [ CONCLUSIONS In addition to NT-proBNP and NYHA stages, ARC enables classification of HFrEF patients receiving OMT into more distinguished neurohumoral HFrEF phenotypes, offering a rationale for adaptive therapeutic interventions.

Introduction Ring fixation of C1 can be performed using pedicle screws and a rod in case of unstable Jefferson or lateral mass fractures of C1. Materials and methods In a case series of three patients, we stabilized C1 fractures surgically using a modified technique of C1 ring fixation by using monoaxial instead of polyaxial screws. Functional outcome and pain was recorded postoperatively. Results In this very small case series, we observed good results concerning pain and functional outcome. All fractures were bony healed within 13 weeks. In one case, a screw penetrated the spinal canal and had to be repositioned. A mild irritation of C2 nerve root occurred in two cases postoperatively. Conclusion C1 Ring fusion with monoaxial screws provides a good ability to reduce the fracture indirectly by the screws and the rod itself.

Rationale: Neurogenic hypertension is characterized by an increase in sympathetic activity and often resistance to drug treatments. We previously reported that it is also associated with a reduction of angiotensin-converting enzyme type 2 (ACE2) and an increase in a disintegrin and metalloprotease 17 (ADAM17) activity in experimental hypertension. In addition, while multiple cells within the central nervous system have been involved in the development of neurogenic hypertension, the contribution of ADAM17 has not been investigated. Objective: To assess the clinical relevance of this ADAM17-mediated ACE2 shedding in hypertensive patients and further identify the cell types and signaling pathways involved in this process. Methods and Results: Using a mass spectrometry-based assay, we identified ACE2 as the main enzyme converting angiotensin II into angiotensin-(1–7) in human cerebrospinal fluid. We also observed an increase in ACE2 activity in the cerebrospinal fluid of hypertensive patients, which was correlated with systolic blood pressure. Moreover, the increased level of tumor necrosis factor-α in those cerebrospinal fluid samples confirmed that ADAM17 was upregulated in the brain of hypertensive patients. To further assess the interaction between brain renin–angiotensin system and ADAM17, we generated mice lacking angiotensin II type 1 receptors specifically on neurons. Our data reveal that despite expression on astrocytes and other cells types in the brain, ADAM17 upregulation during deoxycorticosterone acetate–salt hypertension occurs selectively on neurons, and neuronal angiotensin II type 1 receptors are indispensable to this process. Mechanistically, reactive oxygen species and extracellular signal-regulated kinase were found to mediate ADAM17 activation. Conclusions: Our data demonstrate that angiotensin II type 1 receptors promote ADAM17-mediated ACE2 shedding in the brain of hypertensive patients, leading to a loss in compensatory activity during neurogenic hypertension.

Direct renin inhibition (DRI) is clinically inferior to other blockers of the renin-angiotensin system (RAS). Thus far, the underlying molecular causes of this finding remain unknown.Twenty four patients with non-diabetic chronic kidney disease (CKD) stages III-IV and albuminuria were randomized to DRI or angiotensin receptor blocker (ARB). Employing a novel mass-spectrometry method, the concentrations of renin, aldosterone and plasma angiotensin peptides [Ang I, Ang II, Ang-(1-7), Ang-(1-5), Ang-(2-8), Ang-(3-8)] were quantified before and after an 8-week treatment.While blood pressure, renal function and albuminuria decreased comparably in both groups, profound RAS component differences were observed: DRI led to a massive renin increase, while suppressing both vasoconstrictive (Ang I and Ang II) and vasodilatory RAS metabolites (Ang-(1-7) and Ang-(1-5)). In contrast, ARB led to a four-fold increase of Ang I and Ang II, while Ang-(1-7) and Ang-(1-5) increased moderately but significantly. With ARB treatment, a decreased aldosterone-to-Ang II ratio suggested efficacy in blocking AT1 receptor.DRI therapy abolishes all RAS effector peptides. ARB increases both vasoconstrictive and vasodilative angiotensins, while this is accompanied by efficient blockade of vasoconstrictive effects. These differential molecular regulations should be considered when selecting optimal antihypertensive and disease-modifying therapy in CKD patients. Key messages Direct renin inhibition leads to a complete and lasting abolition of both classical and alternative RAS components. Angiotensin receptor blockade leads to effective receptor blockade and up-regulation of alternative RAS components. Differential molecular regulations of the RAS should be considered when selecting optimal antihypertensive and disease-modifying therapy in CKD patients.

INTRODUCTION: Black populations may be more likely to have primary aldosteronism (PA) due to adrenal hyperplasia or other forms of adrenal hyperactivity, with suppressed renin levels and high levels of aldosterone, which may contribute to the development of hypertension. METHODS: This sub-study involved 35 black men matched for age, gender and race, and aged 20–65 years, living in the North West Province of South Africa. RAAS triple-A analysis was carried out with LC-MS/MS quantification. Blood pressure, electrocardiography and other variables were determined with known methods. RESULTS: Hypertensive subjects with higher aldosterone levels showed an increased aldosterone–angiotensin II ratio (AA2 ratio) compared to the hypertensive subjects with low aldosterone levels (10.2 vs 3.0 pmol/l; p = 0.003). The serum potassium concentration was significantly lower in the high-aldosterone group and the serum sodium–potassium ratio was significantly higher compared to the low-aldosterone group (3.9 vs 4.5, p = 0.016, 34.8 vs 31.8, p = 0.032, respectively). Furthermore, aldosterone was positively associated with both left ventricular hypertrophy (Cornell product) (Spearman R = 0.560; p = 0.037) and kidney function [albumin-to-creatinine ratio (ACR)] (Spearman R = 0.589, p = 0.021) in the hypertensive high-serum aldosterone group. CONCLUSIONS: The AA2 ratio, a novel screening test that is currently being validated for PA case detection, was used to identify a PA-like phenotype in black men. Excess aldosterone was associated with endothelial dysfunction and left ventricular hypertrophy, independent of blood pressure.

This study investigated associations of brachial and central blood pressure (BP) with detailed renin-angiotensin-aldosterone system (RAAS) components in a healthy young population stratified according to ethnicity and sex. We included healthy black men (n = 285) and women (n = 304) and white men (n = 278) and women (n = 305) aged 20-30 years old. We derived central systolic BP (cSBP), measured clinic and 24-h systolic and diastolic BP. Aldosterone and equilibrium angiotensin levels were assessed and used for calculating angiotensin-derived markers for plasma renin activity (PRA-S, Angiotensin I + Angiotensin II), angiotensin-converting enzyme (ACE-S, Angiotensin II/Angiotensin I), and two markers for adrenal effects of angiotensin II, the aldosterone-to-renin ratio (ARR-S, Aldosterone/PRA-S) and the aldosterone-to-angiotensin II-ratio (AA2-R, Aldosterone/Angiotensin II). Young black men and women presented with lower RAAS components and higher cSBP compared to their white counterparts (all p ≤ 0.001). In multivariable-adjusted regression analyses, positive associations of cSBP with ARR-S and AA2-R and negative associations with PRA-S and angiotensin II were found for black women (all p ≤ 0.001); this pattern was also observed for 24-h and clinic BP (p ≤ 0.045). A similar trend of RAAS associations was present in black men but only for clinic BP (all p ≤ 0.047). In white men, negative associations between clinic SBP and PRA-S, angiotensin II and aldosterone were detected (all p ≤ 0.048). No associations were observed in white women. Positive associations of central and peripheral BP with the ratio of aldosterone to PRA-S and angiotensin II only in healthy, young black adults suggest that relative aldosterone excess may contribute to early hypertension development in this group.

International audience; Primary aldosteronism (PA) is the most frequent form of secondary arterial hypertension. Mutations in different genes increase aldosterone production in PA, but additional mechanisms may contribute to increased cell proliferation and aldosterone producing adenoma (APA) development. We performed transcriptome analysis in APA and identified retinoic acid receptor alpha (RARα) signaling as a central molecular network involved in nodule formation. To understand how RARα modulates adrenal structure and function, we explored the adrenal phenotype of male and female Rarα knockout mice. inactivation of Rarα in mice led to significant structural disorganization of the adrenal cortex in both sexes, with increased adrenal cortex size in female mice and increased cell proliferation in males. Abnormalities of vessel architecture and extracellular matrix were due to decreased Vegfa expression and modifications in extracellular matrix components. On the molecular level, Rarα inactivation leads to inhibition of non-canonical Wnt signaling, without affecting the canonical Wnt pathway nor PKA signaling. Our study suggests that Rarα contributes to the maintenance of normal adrenal cortex structure and cell proliferation, by modulating Wnt signaling. Dysregulation of this interaction may contribute to abnormal cell proliferation, creating a propitious environment for the emergence of specific driver mutations in PA. Primary aldosteronism (PA) is the most common and curable form of secondary arterial hypertension, with prevalence estimations of up to 10% of cases in referred hypertensive patients, 4% of patients in primary care 1,2 and 20% of patients with resistant hypertension 3,4. Rapid diagnosis and treatment are important to prevent severe cardiovas-cular consequences of long term aldosterone exposure, which are independent of blood pressure levels and are due

Primary aldosteronism is recognized as the most frequent cause of secondary hypertension, and its screening is expected to become a routine evaluation in most patients with hypertension. The interference of antihypertensive therapies with the aldosterone-to-renin ratio during screening process is a major confounder. Renin-angiotensin-aldosterone system Triple-A analysis is a novel liquid chromatography/tandem mass spectrometry diagnostic assay that allows simultaneous quantification of aldosterone, equilibrium Ang I (angiotensin I), and Equilibrium Ang II in a single sample of serum. We performed a comparative evaluation of the diagnostic performance of the aldosterone-to-Ang II ratio and 5 renin-based diagnostic ratios, differing in methods to determine aldosterone levels and renin activity in a cohort of 110 patients with hypertension (33 patients with confirmed primary aldosteronism and 77 with essential hypertension). All ratios showed comparable areas under the curves ranging between 0.924 and 0.970 without significant differences between each other. The evaluation of the Ang II-to-Ang I ratio revealed persistent drug intake in some patients as cause for suppressed renin-based diagnostic ratios, while aldosterone-to-Ang II ratio remained unaffected. The Youden index optimal cutoff value for the aldosterone-to-Ang II ratio was 6.6 ([pmol/L]/[pmol/L]) with a sensitivity of 90% and a specificity of 93%, proving noninferiority compared with the aldosterone-to-renin ratio while pointing to the potential for an interference-free application in patients under ACE (angiotensin-converting enzyme) inhibitor therapy. This study shows for the first time the accuracy and reliability of renin-angiotensin-aldosterone system triple-A analysis for the screening of primary aldosteronism that can be applied in clinical routine.

Background Prognosis of patients with HFrEF remains poor despite recent advances in pharmacologic therapy as the introduction of the angiotensin-receptor neprilysin-inhibitor (ARNI). The Renin-Angiotensin-System (RAS) is dysregulated in HF with elevated AngII levels as a central driver of disease progression. The myocardium is capable of synthesizing all RAS components resulting in tissue specific angiotensin levels. Neprilysin (NEP) catalyzes the generation of Ang1–7 which counteracts the deleterious effects of AngII. Myocardial tissue angiotensins of the failing heart and the role of long-lasting RAS-inhibitor therapy and particularly NEP inhibition on tissue RAS have not been investigated yet. Methods Concentrations of AngI, AngII, Ang1–7, AngIII, Ang1–5 and AngIV (RAS-fingerprints) were investigated in myocardial samples of end-stage HFrEF patients undergoing heart transplantation with a mass-spectrometry based method. Patients were stratified according to background therapy with RAS-inhibitors and variables were compared by a non-parametrical test. Results A total of 30 patients were included (n=6 without RAS-blockade, n=16 with ACE-I, n=6 with ARB and n=2 with ARNI). Median age was 55 (IQR 45–63) years and 87% of patients were male. 40% of patients had an ischemic etiology of HF, median NT-proBNP levels were 3498pg/ml (IQR 1761–8400). Tissue RAS patterns were visually similar between all groups (Figure 1). Myocardial AngI, Ang1–7, Ang1–5 and AngIV levels were below the detection limit for all samples. Median tissue AngII and AngIII concentrations across all samples were 83.1pg/ml (IQR 29.3–196.6) and 26.4pg/ml (IQR 5.0–64.5). Despite different background RAS-inhibitor therapy, AngII and AngIII levels were comparable between all groups [median (IQR) in pg/ml – AngII: 51.5 (41.5–123.8) vs. 72.4 (28.5–177.6) vs. 176.1 (22.4–286.8) vs. 266.0 (108.2–423.8); p=ns and 26.4 (5.0–89.2) vs. 23.2 (5.0–59.3) vs. 39.4 (5.0–94.3) vs. 105.9 (46.5–165.3); p=ns for no therapy, ACE-I, ARB and ARNI respectively]. Figure 1. RAS-fingerprints of the failing heart according to RAS-inhibiton. Numbers in brackets indicate the specific angiotensin peptides. Side of spheres and numbers beside represent absolute concentrations of angiotensins (pg/ml, median value). Conclusions Although in the plasma of HFrEF patients only AngI and AngII are detectable at substantial concentrations, the predominant angiotensins of the failing heart are AngII and AngIII. AngII levels are high in the failing heart supporting the hypothesis that excess AngII is involved in disease progression. AngIII similarly increases cardiac sympathetic activity assumedly potentiating further deteoriation. The modality of long established RAS-inhibitor therapy in end-stage HF, particularly the inhibition of NEP, seems to have no (more) influence on myocardial tissue RAS regulation. The impact of NEP inhibition by ARNI on tissue RAS enzymes and mechanism of action need to be further investigated.

Background In heart failure with reduced ejection fraction (HFrEF) the renin-angiotensin-system (RAS) is dysregulated and serves as therapeutic target. Research has been focusing on plasma RAS. Information on tissue RAS is scarce although assumedly more crucial for myocardial function. Among known angiotensins, only AngII and AngIII are detectable in the failing heart. Plasma samples in HFrEF show high AngI and AngII levels with clearly distinguishable AngI/AngII ratios for different RAS-inhibitors. AngII and AngIII levels in the myocardium were comparable for different RAS-inhibitors, i.e. no RAS-blocker, ACE-inhibitor, ARB or angiotensin-receptor neprilysin-inhibitor (ARNI). Here we aimed to elucidate the metabolic regulation of tissue RAS enzymes for these four different modalities of RAS-inhibition. Methods Enzyme regulation and metabolic activities were investigated in myocardial samples of end-stage HFrEF patients undergoing heart transplantation with a mass-spectrometry based method. Concentrations of respective angiotensin metabolites AngI, AngII, Ang1–7, AngIII, Ang1–5 and AngIV (RAS-fingerprints) were investigated after adding AngI or AngII and incubation to display metabolic patterns of the main plasma angiotensins. Metabolic activities of distinct enzymes have been assessed for the no therapy and ACE-I subgroups. Patients were stratified according to background therapy with RAS-inhibitors. Results A total of 30 patients were included (n=6 without RAS-blockade, n=16 with ACE-I, n=6 with ARB, n=2 with ARNI). Median age was 55 (IQR 45–63) years, 87%were male. Etiology of HF was ischemic in 40%, median NT-proBNP levels were 3498pg/ml (IQR 1761–8400). Patterns for tissue RAS metabolism of AngI and AngII was visually similar for all groups, indicating comparable regulation of tissue RAS enzymes independent from therapy (Figure 1). The formation of AngII from AngI was mainly chymase dependent with conversion rates of 99.4 (IQR 77.0–254.1) (pg/μg protein)/h for ACE-I and 141.8 (IQR 67.9–369.2) (pg/μg protein)/h for no RAS-blockade, whereas ACE-related generation of AngII was under the detection limit. The formation of Ang1–7 from AngI was mediated by NEP and PEP. The contribution of NEP was significantly higher [5022 (IQR 5002–5286) (pg/μg)/h vs 3555 (IQR 3351–3849) (pg/μg)/h, p=0.005 for the ACE-I group and 4729 (IQR 4438–6135) (pg/μg)/h vs 3601 (IQR 3052–4182) (pg/μg)/h, p=0.012 for no RAS-blockade]. No differences in tissue enzymatic activities between ACE-I and no therapy, as already indicated by the metabolization patterns occurred. Figure 1 Conclusions Enzymatic tissue RAS regulation in end-stage HF seems to be independent from the mode of established RAS-inhibitor therapy.In contrast to plasma, AngII formation of the tissue is mainly chymase dependent, whereas ACE seems to play an unsignificant role. NEP has a substantial role in generating beneficial Ang1–7 from AngI. The impact of NEP inhibition by ARNI on tissue RAS and mechanism of action have to be further investigated.

According to new European guidelines, first-line anti-hypertensive therapies include either an ACE inhibitor (ACEi) or an angiotensin receptor blocker (ARB) in a single pill combination with a calcium channel blocker (CCB) or a diuretic. Insufficient therapeutic effects could be caused by various factors ranging from compliance issues, patient specific PK/PD profiles, or secondary forms of hypertension resulting in blood pressure control rates in the range of 50% of patients on therapy. RAAS Triple-A testing is based on a high-throughput mass-spectrometry assay for quantification of Angiotensin I (Ang I), Angiotenisn II (Ang II) and Aldosterone in standard serum or plasma samples by RAAS equilibrium analysis. Obtained hormone levels are used to calculate markers for plasma-renin-activity (PRA-S), plasma angiotensin-converting-enzyme activity (ACE-S) and adrenal function (AA2-Ratio). The diagnostic performance of the AA2-Ratio in screening for primary aldosteronism (PA) has been compared to the aldosterone-to-renin ratio (ARR) as putative gold standard in resistant hypertensive patients, revealing major advantages of the AA2-Ratio especially in terms of usability and drug interference. A diagnostic scheme for the stratification of first-line non-responding hypertensive patients has been developed to improve the control rates for hypertension and to provide an easy-to-handle diagnostic tool for physicians involved in first-line treatment of hypertension. RAAS Triple-A analysis for the first time provides insights into a patient’s RAAS at the level of effector hormones, molecular regulation and patient specific pharmacologic responses to anti-hypertensive therapies and has the potential to result in significant changes in hypertension care in clinical practice by introducing personalized treatments based on an easy and effective diagnostic tool.

Angiotensin-converting-enzyme-inhibitors (ACEi) are widely used for treating hypertension and cardiovascular diseases and block Angiotensin-II (Ang-II) formation from Angiotensin-I (Ang-I). The therapeutic response to ACE inhibition critically depends on in vivo pharmacologic efficacy and affected by dosing, patient compliance and patient specific compensatory mechanisms, all being relevant topics for the clinical management of hypertension. Samples were collected from 19 hypertensive patients and 7 confirmed primary aldosteronism (PA) patients. Hypertensive patients were investigated at baseline and after 4 weeks on therapy with a single daily dose of perindopril. PA patients were sampled before and after 14 day administration of ramipril. All samples were analysed by LC-MS/MS based RAAS Triple-A testing which involves the calculation of ACE-S, the ratio between plasma equilibrium levels of Ang-II and Ang-I as a novel marker for circulating ACE activity. ACE activity was further measured by analyzing the time dependent conversion of spiked Ang-I (LC-MS/MS) and by performing a clinical colorimetric ACE assay. Treatment adherence was confirmed by quantification of plasma drug levels. ACE-S was significantly lower in all patients on perindopril or ramipril therapy compared to baseline (MEDIANS: 0.35 vs. 2.75 pM/pM, p The novel angiotensin based marker ACE-S can be used to monitor pharmacologic efficacy of ACE inhibitors independent of their chemical structure. As part of the RAAS Triple-A test that is currently validated in screening for secondary forms of hypertension, ACE-S has the potential to support the clinical management of first-line non-responders in terms of optimizing ACEi dosing and visualizing patient specific compensatory mechanisms, thereby improving the overall control rates in hypertension.

Deoxycorticosterone acetate (DOCA)-salt is suggested to increase blood pressure via selective upregulation of the brain renin-angiotensin system (RAS), while suppressing the circulating RAS. Yet, we have observed parallel downregulation of plasma and brain renin in mice. Here, we quantified brainstem angiotensinogen (AGT) and angiotensin (Ang) levels in rats exposed to DOCA (200mg; 60-day release) and 0.9% NaCl as drinking water for 7 weeks. To determine the contribution of AGT (liver vs. kidney/brain), Ang II type 1 receptors (AT1R) and blood pressure to tissue Ang II content, rats received vehicle, liver-targeted AGT siRNA (10 mg/kg fortnightly; s.c.), valsartan (31 mg/kg/day; s.c.) or spironolactone (80 mg/kg/day; s.c.) during the final 3 weeks, the latter fully normalizing blood pressure (n=3-9 per group). Plasma renin and AGT were determined by enzyme-kinetic assay, tissue AGT by western blotting, and Ang I and II by LC-MS/MS. Plasma renin, AGT, Ang I and II in rats not exposed to DOCA-salt were 24±8ng Ang I/mL per h, 731±51nM, 123±38pM and 109±43pM. AGT was present in liver, kidney and brainstem. Kidney Ang I and II were 540±135and 510±97fmol/g, while brainstem Ang I and II were undetectable in all and 50% of the rats, respectively (