scholarly journals Brain ACE2 activation following brain aminopeptidase A blockade by firibastat in salt-dependent hypertension

2021 ◽  
Vol 135 (6) ◽  
pp. 775-791
Author(s):  
Reda Hmazzou ◽  
Yannick Marc ◽  
Adrien Flahault ◽  
Romain Gerbier ◽  
Nadia De Mota ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Renin Angiotensin System ◽  
Vasopressin Release ◽  
Angiotensin System ◽  
Angiotensin Converting Enzyme 2 ◽  
Zinc Metalloprotease ◽  
Angiotensin Iii ◽  
Membrane Bound ◽  
Aminopeptidase A ◽  
The Brain

Abstract In the brain, aminopeptidase A (APA), a membrane-bound zinc metalloprotease, generates angiotensin III from angiotensin II. Brain angiotensin III exerts a tonic stimulatory effect on the control of blood pressure (BP) in hypertensive rats and increases vasopressin release. Blocking brain angiotensin III formation by the APA inhibitor prodrug RB150/firibastat normalizes arterial BP in hypertensive deoxycorticosterone acetate (DOCA)-salt rats without inducing angiotensin II accumulation. We therefore hypothesized that another metabolic pathway of brain angiotensin II, such as the conversion of angiotensin II into angiotensin 1-7 (Ang 1-7) by angiotensin-converting enzyme 2 (ACE2) might be activated following brain APA inhibition. We found that the intracerebroventricular (icv) administration of RB150/firibastat in conscious DOCA-salt rats both inhibited brain APA activity and induced an increase in brain ACE2 activity. Then, we showed that the decreases in BP and vasopressin release resulting from brain APA inhibition with RB150/firibastat were reduced if ACE2 was concomitantly inhibited by MLN4760, a potent ACE2 inhibitor, or if the Mas receptor (MasR) was blocked by A779, a MasR antagonist. Our findings suggest that in the brain, the increase in ACE2 activity resulting from APA inhibition by RB150/firibastat treatment, subsequently increasing Ang 1-7 and activating the MasR while blocking angiotensin III formation, contributes to the antihypertensive effect and the decrease in vasopressin release induced by RB150/firibastat. RB150/firibastat treatment constitutes an interesting therapeutic approach to improve BP control in hypertensive patients by inducing in the brain renin–angiotensin system, hyperactivity of the beneficial ACE2/Ang 1-7/MasR axis while decreasing that of the deleterious APA/Ang II/Ang III/ATI receptor axis.

A new strategy for treating hypertension by blocking the activity of the brain renin–angiotensin system with aminopeptidase A inhibitors

2014 ◽  
Vol 127 (3) ◽  
pp. 135-148 ◽  
Author(s):  
Ji Gao ◽  
Yannick Marc ◽  
Xavier Iturrioz ◽  
Vincent Leroux ◽  
Fabrice Balavoine ◽  
...  
Keyword(s):  
Antihypertensive Agents ◽  
Renin Angiotensin System ◽  
Site Directed Mutagenesis ◽  
Hypertensive Rats ◽  
Vasopressin Release ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Obesity And Diabetes ◽  
Aminopeptidase A ◽  
The Brain

Hypertension affects one-third of the adult population and is a growing problem due to the increasing incidence of obesity and diabetes. Brain RAS (renin–angiotensin system) hyperactivity has been implicated in the development and maintenance of hypertension in several types of experimental and genetic hypertension animal models. We have identified in the brain RAS that APA (aminopeptidase A) and APN (aminopeptidase N), two membrane-bound zinc metalloproteases, are involved in the metabolism of AngII (angiotensin II) and AngIII (angiotensin III) respectively. The present review summarizes the main findings suggesting that AngIII plays a predominant role in the brain RAS in the control of BP (blood pressure). We first explored the organization of the APA active site by site-directed mutagenesis and molecular modelling. The development and the use in vivo of specific and selective APA and APN inhibitors EC33 and PC18 respectively, has allowed the demonstration that brain AngIII generated by APA is one of the main effector peptides of the brain RAS, exerting a tonic stimulatory control over BP in conscious hypertensive rats. This identified brain APA as a potential therapeutic target for the treatment of hypertension, which has led to the development of potent orally active APA inhibitors, such as RB150. RB150 administered orally in hypertensive DOCA (deoxycorticosteroneacetate)-salt rats or SHRs (spontaneously hypertensive rats) crosses the intestinal, hepatic and blood–brain barriers, enters the brain, generates two active molecules of EC33 which inhibit brain APA activity, block the formation of brain AngIII and normalize BP for several hours. The decrease in BP involves two different mechanisms: a decrease in vasopressin release into the bloodstream, which in turn increases diuresis resulting in a blood volume reduction that participates in the decrease in BP and/or a decrease in sympathetic tone, decreasing vascular resistance. RB150 constitutes the prototype of a new class of centrally acting antihypertensive agents and is currently being evaluated in a Phase Ib clinical trial.

Aminopeptidase A, which generates one of the main effector peptides of the brain renin-angiotensin system, angiotensin III, has a key role in central control of arterial blood pressure

2000 ◽  
Vol 28 (4) ◽  
pp. 435-440 ◽  
Author(s):  
A. Reaux ◽  
X. Iturrioz ◽  
G. Vazeux ◽  
M.-C. Fournie-Zaluski ◽  
C. David ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Renin Angiotensin System ◽  
Central Control ◽  
Angiotensin System ◽  
Arterial Blood ◽  
Angiotensin Iii ◽  
Aminopeptidase A ◽  
The Brain

Overactivity of the brain renin-angiotensin system (RAS) has been implicated in the development and maintenance of hypertension in several experimental animal models. We have recently reported that, in the murine brain RAS, angiotensin II (AngII) is converted by aminopeptidase A (APA) into angiotensin III (AngIII), which is itself degraded by aminopeptidase N (APN), both peptides being equipotent to increase vasopressin release and arterial blood pressure when injected by the intracerebroventricular (i.c.v.) route. Because AngII is converted in vivo into AngIII, the exact nature of the active peptide is not precisely known. To delineate their respective roles in the central control of cardiovascular functions, specific and selective APA and APN inhibitors are needed to block the metabolic pathways of AngII and AngIII respectively. In the absence of such compounds for APA, we first explored the organization of the APA active site by site-directed mutagenesis. This led us to propose a molecular mechanism of action for APA similar to that proposed for the bacterial enzyme thermolysin deduced from X-ray diffraction studies. Secondly, we developed a specific and selective APA inhibitor, compound EC33 [(S)-3-amino-4-mercaptobutylsulphonic acid], as well as a potent and selective APN inhibitor, PC18 (2-amino-4-methylsulphonylbutane thiol). With these new tools we examined the respective roles of AngII and AngIII in the central control of arterial blood pressure. A central blockade of APA with the APA inhibitor EC33 suppressed the pressor effect of exogenous AngII, suggesting that brain AngII must be converted into AngIII to increase arterial blood pressure. Furthermore, EC33, injected alone i.c.v. but not intravenously, caused a dose-dependent decrease in arterial blood pressure by blocking the formation of brain AngIII but not systemic AngIII. This is corroborated by the fact that the selective APN inhibitor PC 18 administered alone via the i.c.v. route increased arterial blood pressure. This pressor response was blocked by prior treatment with the angiotensin type 1 receptor antagonist losartan, showing that blocking the action of APN on AngIII metabolism leads to an increase in endogenous AngIII levels, resulting in arterial blood pressure increase through an interaction with angiotensin type 1 receptors. These results demonstrate that AngIII is a major effector peptide of the brain RAS, exerting a tonic stimulatory control over arterial blood pressure. Thus APA, the enzyme responsible for the formation of brain AngIII, represents a potential central therapeutic target that justifies the development of APA inhibitors, crossing the blood-brain barrier, as central anti-hypertensive agents.

scholarly journals Pathological Role of Angiotensin II in Severe COVID-19

TH Open ◽  
2020 ◽  
Vol 04 (02) ◽  
pp. e138-e144 ◽  
Author(s):  
Wolfgang Miesbach
Keyword(s):  
Angiotensin Ii ◽  
Angiotensin Converting Enzyme ◽  
Treatment Options ◽  
Renin Angiotensin System ◽  
Target Cells ◽  
Converting Enzyme ◽  
Angiotensin System ◽  
Angiotensin Converting Enzyme 2 ◽  
Renin Angiotensin ◽  
Novel Coronavirus

AbstractThe activated renin–angiotensin system induces a prothrombotic state resulting from the imbalance between coagulation and fibrinolysis. Angiotensin II is the central effector molecule of the activated renin–angiotensin system and is degraded by the angiotensin-converting enzyme 2 to angiotensin (1–7). The novel coronavirus infection (classified as COVID-19) is caused by the new coronavirus SARS-CoV-2 and is characterized by an exaggerated inflammatory response that can lead to severe manifestations such as acute respiratory distress syndrome, sepsis, and death in a proportion of patients, mostly elderly patients with preexisting comorbidities. SARS-CoV-2 uses the angiotensin-converting enzyme 2 receptor to enter the target cells, resulting in activation of the renin–angiotensin system. After downregulating the angiotensin-converting enzyme 2, the vasoconstrictor angiotensin II is increasingly produced and its counterregulating molecules angiotensin (1–7) reduced. Angiotensin II increases thrombin formation and impairs fibrinolysis. Elevated levels were strongly associated with viral load and lung injury in patients with severe COVID-19. Therefore, the complex clinical picture of patients with severe complications of COVID-19 is triggered by the various effects of highly expressed angiotensin II on vasculopathy, coagulopathy, and inflammation. Future treatment options should focus on blocking the thrombogenic and inflammatory properties of angiotensin II in COVID-19 patients.

scholarly journals The Prorenin and (Pro)renin Receptor: New Players in the Brain Renin-Angiotensin System?

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Wencheng Li ◽  
Hua Peng ◽  
Dale M. Seth ◽  
Yumei Feng
Keyword(s):  
Renin Angiotensin System ◽  
Ang Ii ◽  
Future Perspectives ◽  
Vasopressin Release ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Treatment Of Hypertension ◽  
High Level ◽  
The Brain

It is well known that the brain renin-angiotensin (RAS) system plays an essential role in the development of hypertension, mainly through the modulation of autonomic activities and vasopressin release. However, how the brain synthesizes angiotensin (Ang) II has been a debate for decades, largely due to the low renin activity. This paper first describes the expression of the vasoconstrictive arm of RAS components in the brain as well as their physiological and pathophysiological significance. It then focus on the (pro)renin receptor (PRR), a newly discovered component of the RAS which has a high level in the brain. We review the role of prorenin and PRR in peripheral organs and emphasize the involvement of brain PRR in the pathogenesis of hypertension. Some future perspectives in PRR research are heighted with respect to novel therapeutic target for the treatment of hypertension and other cardiovascular diseases.

scholarly journals Correcting the imbalanced protective RAS in COVID-19 with angiotensin AT2-receptor agonists

2020 ◽  
Vol 134 (22) ◽  
pp. 2987-3006 ◽  
Author(s):  
U. Muscha Steckelings ◽  
Colin Sumners
Keyword(s):  
Virus Disease ◽  
Renin Angiotensin System ◽  
Host Cells ◽  
Angiotensin System ◽  
Organ Systems ◽  
Membrane Bound ◽  
Compound 21 ◽  
The Brain ◽  
Entry Mechanism ◽  
Stimulation Of

Abstract The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that is responsible for the global corona virus disease 2019 (COVID-19) pandemic enters host cells via a mechanism that includes binding to angiotensin converting enzyme (ACE) 2 (ACE2). Membrane-bound ACE2 is depleted as a result of this entry mechanism. The consequence is that the protective renin–angiotensin system (RAS), of which ACE2 is an essential component, is compromised through lack of production of the protective peptides angiotensin-(1-7) and angiotensin-(1-9), and therefore decreased stimulation of Mas (receptor Mas) and angiotensin AT2-receptors (AT2Rs), while angiotensin AT1-receptors (AT1Rs) are overstimulated due to less degradation of angiotensin II (Ang II) by ACE2. The protective RAS has numerous beneficial actions, including anti-inflammatory, anti-coagulative, anti-fibrotic effects along with endothelial and neural protection; opposite to the deleterious effects caused by heightened stimulation of angiotensin AT1R. Given that patients with severe COVID-19 exhibit an excessive immune response, endothelial dysfunction, increased clotting, thromboses and stroke, enhancing the activity of the protective RAS is likely beneficial. In this article, we discuss the evidence for a dysfunctional protective RAS in COVID and develop a rationale that the protective RAS imbalance in COVID-19 may be corrected by using AT2R agonists. We further review preclinical studies with AT2R agonists which suggest that AT2R stimulation may be therapeutically effective to treat COVID-19-induced disorders of various organ systems such as lung, vasculature, or the brain. Finally, we provide information on the design of a clinical trial in which patients with COVID-19 were treated with the AT2R agonist Compound 21 (C21). This trial has been completed, but results have not yet been reported.

scholarly journals Functional Complexes of Angiotensin-Converting Enzyme 2 and Renin-Angiotensin System Receptors: Expression in Adult but Not Fetal Lung Tissue

2020 ◽  
Vol 21 (24) ◽  
pp. 9602
Author(s):  
Rafael Franco ◽  
Alejandro Lillo ◽  
Rafael Rivas-Santisteban ◽  
Ana I. Rodríguez-Pérez ◽  
Irene Reyes-Resina ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Cell Surface ◽  
Angiotensin Converting Enzyme ◽  
Ligand Binding ◽  
Renin Angiotensin System ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Converting Enzyme ◽  
Angiotensin System ◽  
Angiotensin Converting Enzyme 2

Angiotensin-converting enzyme 2 (ACE2) is a membrane peptidase and a component of the renin-angiotensin system (RAS) that has been found in cells of all organs, including the lungs. While ACE2 has been identified as the receptor for severe acute respiratory syndrome (SARS) coronaviruses, the mechanism underlying cell entry remains unknown. Human immunodeficiency virus infects target cells via CXC chemokine receptor 4 (CXCR4)-mediated endocytosis. Furthermore, CXCR4 interacts with dipeptidyl peptidase-4 (CD26/DPPIV), an enzyme that cleaves CXCL12/SDF-1, which is the chemokine that activates this receptor. By analogy, we hypothesized that ACE2 might also be capable of interactions with RAS-associated G-protein coupled receptors. Using resonance energy transfer and cAMP and mitogen-activated protein kinase signaling assays, we found that human ACE2 interacts with RAS-related receptors, namely the angiotensin II type 1 receptor (AT1R), the angiotensin II type 2 receptor (AT2R), and the MAS1 oncogene receptor (MasR). Although these interactions led to various alterations of signal transduction, but, more importantly, ligand binding to AT1R resulted in the downregulation of ACE2 cell surface expression, while ligand binding to AT2R, but not to MasR, resulted in upregulation of ACE2 cell surface expression. Proximity ligation assays performed in situ revealed macromolecular complexes containing ACE2 and AT1R, AT2R or MasR in adult but not fetal mouse lung tissue. These findings highlight the relevance of RAS in SARS-CoV-2 infection and the role of ACE2-containing complexes as potential therapeutic targets.

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