Insilico engineering of transaminase variants for enhanced biocatalytic conversion of an ACE inhibitor precursor.

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ACE inhibitors to block MMP-9 activity: New functions for old inhibitors

Comparative Impacts of ACE (Angiotensin-Converting Enzyme) Inhibitors Versus Angiotensin II Receptor Blockers on the Risk of COVID-19 Mortality.

In addition to its function as dipeptidase, ACE can act as a signal transduction molecule following the binding of ACE inhibitors. The “ACE signaling pathway” affects endothelial gene expression via phosphorylation of ACE on Ser1270 and activation of the JNK/cJun-pathway. Since it is unclear how ACE inhibitors initiate these intracellular signaling events we determined whether ACE can dimerize and whether ACE dimer formation is required for ACE signaling. Native gel electrophoresis revealed that ACE exists in its monomeric form and as a dimer of 520 kDa in endothelial cells. ACE dimerization was confirmed using the split-ubiquitin assay as well as by chemical crosslinking. ACE inhibitors elicited a rapid, concentration-dependent increase in ACE dimerization that correlated with the ACE inhibitor induced ACE phosphorylation. ACE dimerization in vitro depends on an N-terminal carbohydrate recognition domain, but neither carbohydrates nor N-terminus shielding ACE antibodies were able to affect ACE dimerization in endothelial cells. However, inactivation of the C-domain active centre of ACE by mutation of the two Zn2+-complexing histidines prevented the basal and ramiprilat-induced ACE dimerization as well as ACE phosphorylation on Ser1270 and the subsequent activation of JNK. Mutation of the N-domain active centre was without effect on ACE dimerization or the initiation of signaling. Taken together, our data suggest that ACE inhibitors, most probably by binding to the C-domain active centre, initiate the “ACE signaling pathway” by promoting the formation of ACE dimers.

HomeHypertensionVol. 76, No. 5Plasma Angiotensin Peptide Profiling and ACE (Angiotensin-Converting Enzyme)-2 Activity in COVID-19 Patients Treated With Pharmacological Blockers of the Renin-Angiotensin System Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBPlasma Angiotensin Peptide Profiling and ACE (Angiotensin-Converting Enzyme)-2 Activity in COVID-19 Patients Treated With Pharmacological Blockers of the Renin-Angiotensin System Ulrich Kintscher, Anna Slagman, Oliver Domenig, Robert Röhle, Frank Konietschke, Marko Poglitsch and Martin Möckel Ulrich KintscherUlrich Kintscher Correspondence to Ulrich Kintscher, Charité–Universitätsmedizin Berlin, Institute of Pharmacology, Center for Cardiovascular Research, Hessische Strasse 3-4, 10115 Berlin, Germany. Email E-mail Address: [email protected] https://orcid.org/0000-0001-7386-0990 From the Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany (U.K., A.S., M.M., R.R., F.K.) Institute of Pharmacology, Center for Cardiovascular Research, Germany (U.K.) DZHK (German Centre for Cardiovascular Research), Partner Site Berlin (U.K.) , Anna SlagmanAnna Slagman From the Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany (U.K., A.S., M.M., R.R., F.K.) Department of Emergency and Acute Medicine, Campus Mitte and Campus Virchow Clinic (A.S., M.M.) , Oliver DomenigOliver Domenig Attoquant Diagnostics, Vienna, Austria (O.D., M.P.). , Robert RöhleRobert Röhle https://orcid.org/0000-0002-8130-6524 From the Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany (U.K., A.S., M.M., R.R., F.K.) Institute of Biometry and Clinical Epidemiology, Coordinating Center for Clinical Studies (R.R.) Berlin Institute of Health, Germany (R.R., F.K.) , Frank KonietschkeFrank Konietschke From the Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany (U.K., A.S., M.M., R.R., F.K.) Institute of Biometry and Clinical Epidemiology (F.K.) Berlin Institute of Health, Germany (R.R., F.K.) , Marko PoglitschMarko Poglitsch Attoquant Diagnostics, Vienna, Austria (O.D., M.P.). and Martin MöckelMartin Möckel https://orcid.org/0000-0002-7691-3709 From the Charité–Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany (U.K., A.S., M.M., R.R., F.K.) Department of Emergency and Acute Medicine, Campus Mitte and Campus Virchow Clinic (A.S., M.M.) Originally published27 Aug 2020https://doi.org/10.1161/HYPERTENSIONAHA.120.15841Hypertension. 2020;76:e34–e36Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: August 27, 2020: Ahead of Print Pharmacological blockade of the renin-angiotensin system (RAS) with ACE (angiotensin-converting enzyme) inhibitors or angiotensin type 1 receptor blockers (ARB) reduces morbidity and mortality in various cardiovascular diseases. One of the key RAS-modulating enzymes, ACE2, has recently gained increasing attention because it converts not only angiotensin (Ang) II to the alternative RAS metabolite Ang-(1–7) but also functions as the cellular entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2.1 At the beginning of the SARS-CoV-2 pandemic, some investigators suggested that because ACE inhibitor or ARB may lead to upregulation of ACE2 expression/activity, use of these agents in coronavirus disease 2019 (COVID-19) patients might be associated with worsened outcomes.1 Meanwhile, several observational studies have shown that neither the risk of COVID-19 nor its severity is negatively affected by ACE inhibitor or ARB.2,3 However, it remains unclear how RAS activity, particularly ACE2, is regulated in COVID-19 and how this is altered by ACE inhibitor/ARB therapy. In this study, we analyzed distinct RAS components in plasma from patients with COVID-19 ±ACE inhibitor/ARB therapy using liquid chromatography-mass spectrometry/mass spectrometry.The study was approved by the Charité-Universitäts-medizin, Berlin, Germany, Institutional Ethics Committee (EA2/204/19, Amendment 1) and registered in the German Registry for Clinical Studies (DRKS00019207). Surplus plasma samples were collected at the time of admission to the emergency room from 6 different patient groups (total, n=58 [women, 21]): SARS-CoV-2 negative control group (control, n=9 [4]), SARS-CoV-2 negative with ACE inhibitor (control-ACE inhibitor, n=10 [2]), SARS-CoV-2 negative with ARBs (control-ARB, n=8 [5]), COVID-19 without ACE inhibitor/ARB (COVID, n=12 [5]), COVID-19 with ACE inhibitor (COVID-ACE inhibitor, n=10 [2]), and COVID-19 with ARBs (COVID-ARB, n=9 [3]). Equilibrium levels of Ang-peptides (Ang I, Ang II, Ang-[1–7], and Ang-[1–5]) were measured using liquid chromatography-mass spectrometry/mass spectrometry technology (Attoquant Diagnostics).4 Ang-based markers for ACE (Ang II/Ang I) and plasma renin activity (Ang I+Ang II) were calculated from Ang-peptide levels. ACE2 activity was assayed by a classical kinetic approach applying its natural substrate (ex vivo spiked Ang II) and measuring the turnover to Ang-(1–7)±ACE2 inhibitor MLN-4760. The inhibitor-sensitive ACE2-specific turnover was converted to an ACE2 concentration using a calibration curve of recombinant human ACE2. Ang-peptide concentrations/ratios, ACE2 activity, and age between groups were compared using the Kruskal-Wallis test. In case of a significant result, the Dunn-Test for pairwise comparisons using Bonferroni correction was applied. A P of <0.05 was considered statistically significant, although results have to be considered exploratory.Patient CharacteristicsAge (years, mean±SD): control, 44.8±19.7; control-ACE inhibitor, 63.6±17.8; control-ARB, 73.1±11.4 (P=0.02 versus control); COVID, 50±15.1; COVID-ACE inhibitor, 61.4±20.9; COVID-ARB, 74.2±10.1 (P=0.02 versus COVID); COVID severity (n/group), as defined previously,3 severe (intensive care unit admission, mechanical ventilation, and death): COVID (2), COVID-ACE inhibitor (1), COVID-ARB (1); acute renal failure ([n/group] control-ARB [2], COVID [1], COVID-ARB [1]); diuretic use (n/group): control (0), control-ACE inhibitor (4), control-ARB (6), COVID (0), COVID-ACE inhibitor (1), and COVID-ARB (3). Coexisting conditions are outlined in the Figure (A).ResultsAng-peptide equilibrium concentrations did not significantly differ between the control and COVID groups without ACE inhibitor/ARB treatment (Figure [B], left). More importantly, Ang I+II, Ang II/Ang I, and ACE2 activity were not significantly different between both groups (Figure [C]). These data suggest that patients with COVID-19 are not those with increased RAS activity levels and that particularly COVID-19–induced alternative RAS activation, potentially mediated through circulating ACE2, is not a typical feature in our patient cohort.Download figureDownload PowerPointFigure. Patient characteristics, Ang (angiotensin) peptide profiles, and ACE (angiotensin-converting enzyme)-2 levels. A, The presence of cardiovascular disease (hypertension, coronary artery disease, and chronic heart failure) and type 2 diabetes mellitus depicted as percentage of patients in each group. B, Plasma Ang-peptide concentrations and renin-angiotensin system (RAS) enzymatic cascade are depicted as RAS Fingerprints. The concentration of indicated Ang metabolites is reflected by the size of the corresponding sphere. Blue arrows indicate enzymes that are known to carry out metabolic conversions between connected Ang metabolites. Numbers represent median concentrations (pmol/L) and interquartile ranges in parentheses. C, Ang-based markers for plasma renin activity: Ang I+Ang II and ACE: Ang II/Ang I were calculated from Ang-peptide levels. ACE2 activity was measured as described above. Data are shown as dot plots and median. Significant P values within each group (control and coronavirus disease 2019 [COVID]) are indicated. control: severe acute respiratory syndrome coronavirus 2 negative control group without ACE inhibitor/angiotensin type 1 receptor blocker (ARB) therapy; control+ACE inhibitor: severe acute respiratory syndrome coronavirus 2 negative control group with ACE inhibitor therapy; control+ARB: severe acute respiratory syndrome coronavirus 2 negative control group with ARB therapy; COVID: patients with COVID-19 without ACE inhibitor/ARB; COVID+ACE inhibitor: patients with COVID-19 with ACE inhibitor therapy; COVID+ARB: patients with COVID-19 with ARB therapy. ACEi indicates ACE inhibitor; and CTRL, control.Comparison of all groups, including ACE inhibitor/ARB treatment groups, revealed no significant differences of Ang I+II levels between the groups (Figure [C], upper left). Ang I+II is a reliable marker for plasma renin activity and did not change significantly, despite the use of ACE inhibitor/ARB, while median values were clearly increased in patients on ACE inhibitor/ARB. This is consistent with previous observations demonstrating a broad spectrum of intensity in compensatory renin secretion in patients treated with ACE inhibitor or ARB.4 As expected, patients in the control-ACE inhibitor and COVID-ACE inhibitor group showed increased Ang I and markedly suppressed Ang II levels (Figure [B]), resulting in a significant reduction of the Ang II/Ang I ratio (Figure [C], lower left). Ang-(1–5) levels did not significantly differ between groups, whereas Ang-(1–7) was significantly increased in the COVID-ACE inhibitor group versus COVID without ACE inhibitor/ARB (P=0.01) and versus COVID-ARB (P=0.045). ACE2 activity was significantly higher in patients with COVID-19 treated with ACE inhibitor compared with patients with COVID-19 without ACE inhibitor/ARB (Figure [C], right). ACE2 activity was also increased in the control-ACE inhibitor and control-ARB group but did not reach statistical significance (Figure [C], right). ARB treatment in COVID-19 did not significantly affect ACE2 activity (Figure [C], right).The main findings of this study are as follows: (1) patients with COVID-19 are not characterized by major changes in RAS activity in plasma including ACE2 activity, (2) ACE inhibitor therapy significantly suppressed Ang II/Ang I ratios, the Ang-based marker for ACE, in COVID-19 and in non–patients with COVID-19, and (3) plasma ACE2 activity is increased in patients with COVID-19 treated with ACE inhibitor. These data are consistent with previously published results in SARS-CoV-2–negative patients treated with ACE inhibitor or ARB demonstrating an Ang II/Ang I suppression and a more profound increase of Ang-(1–7) under ACE inhibitor compared with ARBs.4 The data published so far on plasma ACE2 activity and Ang-(1–7) levels in patients without COVID treated with ACE inhibitor or ARBs are controversial.1 Some studies showed an increase in circulating ACE2 activity and Ang-(1–7) levels that cannot be proven by other studies.1 In addition, increased ACE2 activity has been identified in multiple cardiovascular diseases such as hypertension, coronary artery disease, and chronic heart failure, which are usually treated with ACE inhibitor.1 Whether the ACE inhibitor treatment in our study plays a role in ACE2 upregulation or whether these changes are mediated by the increased presence of cardiovascular disease in this group requires further investigation. Furthermore, the clinical significance of the elevated ACE2 activity in patients with COVID-19 treated with ACE inhibitor is currently not completely understood. Whether plasma ACE2 level may be a reliable marker of the full-length membrane bound form1 and whether ACE2 serves as a marker for disease severity or endothelial regeneration in the lung5 need to be clarified in future studies. Some of the major limitations of this study include small sample sizes, lack of a power analysis, lack of any data on blood pressure when the plasma samples were obtained, and lack of any data on duration of illness. Finally, it should be emphasized that the majority of the study patients were not experiencing severe COVID-19. However, we provide for the first time a snapshot of distinct systemic RAS components in patients with COVID-19 under ACE inhibitor/ARB therapy that helps to understand the clinical data on a molecular pharmacological level.AcknowledgmentsWe thank Fabian Holert, Jana Eberst, and Beata Hoeft for the support with sample preparation/handling and clinical data collection.Sources of FundingThis study was supported by institutional funding from the Charité–Universitätsmedizin Berlin, Germany. U. Kintscher is supported by the DZHK (German Centre for Cardiovascular Research) and by the BMBF (German Ministry of Education and Research); BER 5.4 PR, the Deutsche Forschungsgemeinschaft (KI 712/10-1), the BMBF/BfR1328-564 m, and the Einstein Foundation/Foundation Charité (EVF-BIH-2018-440).DisclosuresO. Domenig and M. Poglitsch are employees of Attoquant Diagnostics, Vienna, Austria. U. Kintscher received research grants/speaker honoraria from Bayer. U. Kintscher received speaker honoraria from Berlin Chemie, Boehringer Ingelheim, Daiichi Sankyo, Novartis, Sanofi, and Servier and participated in advisory boards of Berlin Chemie, Boehringer Ingelheim, Novartis, and Sanofi. M. Möckel received research grants/speaker honoraria from Roche Diagnostics and BRAHMS ThermoFisher; M. Möckel received speaker honoraria from Boehringer Ingelheim, Daiichi Sankyo, Novartis, and Bristol Myers Squibb and participated in advisory boards of Daiichi Sankyo and Boehringer Ingelheim. The other authors report no conflicts.FootnotesCorrespondence to Ulrich Kintscher, Charité–Universitätsmedizin Berlin, Institute of Pharmacology, Center for Cardiovascular Research, Hessische Strasse 3-4, 10115 Berlin, Germany. Email ulrich.kintscher@charite.de

The renin-angiotensin-aldosterone system can be blocked at one of several points (Figure 1). Simultaneous blockade at more than one point can be therapeutically beneficial, as in the addition of an aldosterone antagonist to an angiotensin converting enzyme (ACE) inhibitor in patients with severe heart failure 1 or with left ventricular dysfunction following myocardial infarction 2. This makes good pharmacological sense, since angiotensin II is not the only stimulus to aldosterone secretion and when the synthesis or action of angiotensin II is blocked the concentration of circulating aldosterone falls initially but then climbs back toward pre-treatment values in some patients (‘aldosterone breakthrough’– see 3). Renin-angiotensin-aldosterone pathway and its inhibition by angiotensin converting enzyme (ACE) inhibitors, AT1 receptor antagonists (ARBs) and other drugs. Note the potential for increased effects of combinations of ACE inhibitors and ARBs via ARB antagonism of non-ACE-derived angiotensin II and potentiation by ACE inhibitors of ACE-inactivated vasodilator peptides. This editors’ view focuses on the divergence between potential effects and what is actually achieved in clinical practice. JG cells = juxta-glomerular cells in renal cortex. (Drugs are shown in red and enzymes in green). Monotherapy with an ACE inhibitor increases the concentration of circulating angiotensin I because of the loss of feedback inhibition of angiotensin II on renin secretion (Fig 1). Increased substrate (angiotensin I) may partially mitigate inhibition of ACE by a reversible competitive ACE inhibitor, restoring the concentration of active angiotensin II toward pretreatment levels 4, 5, This might be termed ‘angiotensin breakthrough’ by analogy with ‘aldosterone breakthrough’, and is one reason why combined blockade by an AT1 receptor antagonist (an angiotensin receptor blocker or ARB) together with an ACE inhibitor might confer added benefit. Additionally, other enzymes distinct from ACE and not blocked by ACE inhibitors can form angiotensin II – for example mast cell-derived chymase 6. Furthermore, ACE inhibition has pharmacological effects distinct from reducing angiotensin II, notably potentiation of bradykinin in vivo (for example in human resistance forearm vasculature 7) and possibly also other ACE-inactivated vasodilator peptides (ACE is not substrate-specific for angiotensin I). There are thus several distinct mechanisms by which the combination of an ACE inhibitor (which potentiates vasodilator mechanisms as well as reducing circulating angiotensin II) and an ARB (which blocks AT1 receptor-mediated actions of angiotensin II, whether derived from ACE, chymase or other mechanism) could be qualitatively superior to increasing the dose of either such drug administered as a single agent. Combined ACE inhibition with AT1 receptor antagonism has a greater effect than monotherapy on blood pressure and on left ventricular hypertrophy (assessed by measurements of heart weight) in spontaneously hypertensive rats 8. This supported the notion that these drug classes are at least additive and possibly synergistic, which is the basis for a concept of ‘dual blockade’ that is combining ACE inhibition with AT1 receptor antagonism. This strategy has been enthusiastically embraced by prescribers (academics as well as service providers) perhaps because of the seductiveness of the pharmacological rationale outlined above [9, and see below]. However, unlike the addition of aldosterone antagonists to ACE inhibitors 1, 2, hard clinical evidence of improved outcomes with of dual blockade with ARBs and ACE inhibitors is weak. A systematic review and meta-analysis demonstrated an additional effect on blood pressure of around 4/3 mm Hg of the combination versus monotherapy 10. This begs the question whether an increased dose of monotherapy might have had a similar effect and is modest compared with effects of adding a diuretic or a calcium channel blocker to an ACE inhibitor [see for example 11. A meta-analysis of effects of combination therapy on albumin excretion (a surrogate marker of glomerular injury) in patients with renal disease did show that dual blockade reduced protein excretion by 20–25% more than monotherapy 12, which was interpreted by many as encouraging evidence in favor of combination treatment. However, while the ONTARGET trial of the combination of telmisartan (ARB) with ramipril (ACE inhibitor) versus monotherapy showed that combined therapy achieved a mean blood pressure reduction 2.4/1.4 mm Hg greater in the combination group than in the group treated with ramipril alone and a greater effect on urinary albumin excretion, the combination showed no benefits in terms of the primary study endpoint (a composite of cardiovascular death, myocardial infarction, stroke and hospitalisation for heart failure), caused more symptoms attributable to hypotension, and increased the decline in renal function and need for dialysis compared with ACE inhibitor monotherapy13. In a trial in patients with myocardial infarction and heart failure there was an increase in adverse events and no survival benefit in patients randomised to combination therapy with valsartan plus captopril 14. Thus clinical endpoint evidence does not support combined use of ACE inhibitor with ARB, and incidentally also undermines the usefulness of albumin excretion rate as a surrogate marker of renal injury. Messerli concluded that ‘unless data emerge to the contrary, dual blockade should no longer be used in clinical practice’9. How has this slow-burning story influenced prescribing of ACE inhibitors and ARBs? In this issue of the Journal 15 Wan and colleagues describe trends in the co-prescription of ACE inhibitors and ARBs in Ireland between January 2000 and April 2009 (> a quarter of a million prescriptions): there has been a significant positive linear trend in co-prescription taking off in 2000–2001 and increasing thirty five-fold (from 0.16 to 5.72 per 1000 eligible population) in the past decade. There was no abrupt discontinuity noticeable following publication of the endpoint trials including COOPERATE (a trial reported in the Lancet in 2003 which purported to show clinical benefit of combination therapy on progression of non-diabetic renal disease but was subsequently retracted by the Lancet editors in 2009), VALIANT and ONTARGET, although a suggestion of a reduction in the rate of increase in co-prescription following publication of ONTARGET in 2008 (see Figure 1 in reference 15). The ‘dual-blockade strategy’ appears to be a juggernaut with considerable momentum, but without a clinical evidence base! What is the cause of these rather striking findings, and what is to be done to improve prescribing in this regard? In this editorial, which supports skeptical criticism of hypotheses (however ingenious and plausible) based on animal models, and increased reliance on clinical rather than surrogate endpoints, we hesitate to speculate as to the cause underlying these prescribing trends but we suspect our readers may be attracted to certain rather obvious possibilities! As regards what is to be done, the answer must surely be through better education in clinical pharmacology and prescribing skills, as we have argued previously 16.

IgA Nephropathy: A Disease in Search of a Large-Scale Clinical Trial to Reliably Inform Practice

Section 7: Heart Failure in Patients With Left Ventricular Systolic Dysfunction

R enin angiotensin system (RAS) antagonists, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin II receptor antagonists are increasingly used to treat cardiovascular and other diseases (1–6). These treatments induce a blockade of the RAS that may affect hemodynamics during anesthesia and surgery. In 1978, Miller et al. (7) reported that the RAS is involved in maintaining normal blood pressure during anesthesia. Although anesthesia is not invariably associated with a deleterious hemodynamic event in RAS-blocked patients (8–10), hemodynamic instability, described as unexpected episodes of hypotension, have been reported (11–13). Otherwise, stresses such as surgery or hypotension stimulate the generation of angiotensin II, which induces vasoconstriction (14) to maintain blood pressure but reduces blood flow to organs such as the kidneys and bowels. Accordingly, an angiotensin II-induced reduction in blood flow may contribute to acute renal failure (15) and splanchnic ischemia (16), which are obvious factors in postoperative morbidity (17). RAS blockade with ACE inhibitors decreases some consequences of the stress response on the regional circulation (9,18,19), which may then contribute to body protection. Much of the information regarding the physiology and pathophysiology of the RAS during anesthesia and surgery is based on the effects of ACE inhibitors. Because ACE inhibitors probably act mostly by blocking the RAS, similar effects should be obtained from angiotensin (AT) receptor antagonists. RAS antagonist pharmacology may help us to understand the hemodynamic risk of anesthesia in RAS-blocked patients, to identify predisposing factors, and to determine the potential benefit of RAS antagonists during anesthesia and surgery. Physiology of the RAS Generation of Angiotensin II

Renin inhibitors (RIs) reduce blood pressure more than placebo, with the magnitude of this effect thought to be similar to that for angiotensin converting enzyme (ACE) inhibitors. However, a drug's efficacy in lowering blood pressure cannot be considered as a definitive indicator of its effectiveness in reducing mortality and morbidity. The effectiveness and safety of RIs compared to ACE inhibitors in treating hypertension isunknown. To evaluate the benefits and harms of renin inhibitors compared to ACE inhibitors in people with primary hypertension. The Cochrane Hypertension Group Information Specialist searched the following databases for randomized controlled trials up to August 2020: the Cochrane Hypertension Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers about further published and unpublished work. The searches had no language restrictions. We included randomized, active-controlled, double-blinded studies (RCTs) with at least four weeks follow-up in people with primary hypertension, which compared renin inhibitors with ACE inhibitors and reported morbidity, mortality, adverse events or blood pressure outcomes. We excluded people with proven secondary hypertension. Two review authors independently selected the included trials, evaluated the risks of bias and entered the data for analysis. We include 11 RCTs involving 13,627 participants, with a mean baseline age from 51.5 to 74.2 years. Follow-up duration ranged from four weeks to 36.6 months. There was no difference between RIs and ACE inhibitors forthe outcomes: all-cause mortality:risk ratio (RR) 1.05, 95% confidence interval (CI) 0.93 to 1.18; 5 RCTs, 5962 participants; low-certainty evidence;total myocardial infarction: RR 0.86, 95% CI 0.22 to 3.39; 2 RCTs, 957 participants; verylow-certainty evidence;adverse events: RR 0.98, 95% CI 0.93 to 1.03; 10 RTCs, 6007 participants; moderate-certainty evidence;serious adverse events: RR 1.21, 95% CI 0.89 to 1.64; 10 RTCs, 6007 participants; low-certainty evidence;and withdrawal due to adverse effects: RR 0.85, 95% CI 0.68 to 1.06; 10 RTCs, 6008 participants;low-certainty evidence. No data were available for total cardiovascular events, heart failure, stroke, end-stage renal disease or change in heart rate. Low-certainty evidence suggestedthat RIs reduced systolic blood pressure: mean difference (MD) -1.72, 95% CI -2.47 to -0.97; 9 RCTs, 5001 participants; and diastolic blood pressure: MD -1.18, 95% CI -1.65 to -0.72; 9 RCTs, 5001 participants, to a greater extent than ACE inhibitors, but we judged this to be more likely due to bias than a true effect. AUTHORS' CONCLUSIONS: For the treatment of hypertension, we have low certainty that renin inhibitors (RI) and angiotensin converting enzyme (ACE) inhibitors do not differ forall-cause mortality andmyocardial infarction. We have low to moderate certainty that they do not differ foradverse events. Small reductions in blood pressure with renin inhibitors compared to ACE inhibitors are of low certainty. More independent, large, long-term trials are needed to compare RIs with ACE inhibitors, particularly assessingmorbidity and mortality outcomes, but also on blood pressure-lowering effect.

Objective: Gnetum gnemon L. (melinjo) seed extracts have been known to have some biological activities. One of them is ACE (angiotensinconverting enzyme) inhibitor. The present study was conducted to predict potential ACE inhibitory activity of several compounds isolated from Gnetum gnemon L. seeds by using in silico method. Methods: In this study, several compounds isolated from melinjo seeds were determined for their ACE inhibitory activity through molecular docking study and molecular dynamics simulations. Molecular docking experiment was performed by using AutoDock4Zn. Subsequently, molecular dynamics simulations using AMBER within 20 ns was conducted to analyze the interactions stability between zinc-ligand and ligand-amino acids in the active site of ACE since both of these mechanisms were known to play essential roles to inhibit ACE. Results: The results showed that resveratrol, gnetol, isorhapontigenin, gnetin C, trans-e-viniferin, gnemonol K, gnemonol M and aglycone of gnemonoside B exhibited ΔG values which were lower than or close to lisinopril, captopril, and enalaprilat. Some of these ligands were able to bind zinc ion via cation-pi interactions. According to the free-energy binding calculations using MM-GBSA and MM-PBSA methods, gnetin C showed the highest affinity for ACE among other ligands at a temperature of 300 K, while at a temperature of 310 K the highest affinity was exhibited by gnemonol K. Conclusion: According to the molecular docking and molecular dynamics simulations, several compounds isolated from melinjo seed showed potential ACE inhibitory activities, in which gnemonol K promised as the most potential compound to have ACE inhibitory activity. Key words: ACE, Cation-pi, Hypertension, Molecular docking, Molecular dynamics, Zinc ion.

Since the initial description of angiotensin II–mediated hypertension >40 years ago, basic and clinical investigations of the renin-angiotensin system (RAS) have resulted in a broader understanding of cardiovascular pathophysiology and significant advances in therapy. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor antagonists are now widely prescribed for the treatment of hypertension and left ventricular (LV) dysfunction; more recently, the aldosterone receptor antagonist, spironolactone, has proven beneficial in severe heart failure. This article will focus on our current understanding of the RAS and how pharmacological manipulation of this system can improve clinical outcomes in patients with cardiovascular disease. ### Pathophysiological Rationale for RAS Manipulation Renin is released by juxtuloglomerular cells in the kidney in response to renal hypoperfusion, decreased sodium delivery, and sympathetic activation (Figure 1). Angiotensinogen produced by the liver is cleaved by renin to yield the inactive decapeptide angiotensin I. Circulating angiotensin I is, in turn, converted to angiotensin II in the lungs by the action of ACE. ACE, or kininase II, also plays a key role in the kallikrein-kinin system by cleaving bradykinin to inactive peptides. In addition to the hormonal effects of circulating angiotensin II, all of the necessary components of the RAS exist in several organs and tissues, including the heart, kidneys, and vasculature. Figure 1. Pathophysiology of the RAS. SMC indicates smooth muscle cell. Angiotensin II exerts its actions in target organs and tissues by binding to both angiotensin II type 1 and 2 (AT1 and AT2) receptors, although adverse effects in humans seem to be mediated primarily by the AT1 receptor (Figure 1). In the kidney, angiotensin II causes sodium and water retention and efferent arteriolar vasoconstriction. Constriction of the systemic vasculature by angiotensin II causes hypertension, whereas coronary vasoconstriction may cause myocardial ischemia and arrhythmias. Angiotensin II–stimulated secretion of aldosterone by the adrenal cortex and arginine …

Late angio-oedema in patients taking angiotensin-converting-enzyme inhibitors.

Realistic Assessment of Drug-induced Adverse Events: A Double-edged Sword

ACE inhibitors and AT1 receptor antagonists: Is two better than one?