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Dominici FP, Gironacci MM, Narvaez Pardo JA. Therapeutic opportunities in targeting the protective arm of the renin-angiotensin system to improve insulin sensitivity: a mechanistic review. Hypertens Res 2024; 47:3397-3408. [PMID: 39363004 DOI: 10.1038/s41440-024-01909-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 08/04/2024] [Accepted: 09/02/2024] [Indexed: 10/05/2024]
Abstract
In recent years, the knowledge of the physiological and pathophysiological roles of the renin-angiotensin system (RAS) in glucose metabolism has advanced significantly. It is now well-established that blockade of the angiotensin AT1 receptor (AT1R) improves insulin sensitivity. Activation of the AT2 receptor (AT2R) and the MAS receptor are significant contributors to this beneficial effect. Elevated availability of angiotensin (Ang) II) for interaction with the AT2R and increased Ang-(1-7) formation during AT1R blockade mediate these effects. The ongoing development of selective AT2R agonists, such as compound 21 and the novel Ang III peptidomimetics, has significantly advanced the exploration of the role of AT2R in metabolism and its potential as a therapeutic target. These agents show promise, particularly when RAS inhibition is contraindicated. Additionally, other RAS peptides, including Ang IV, des-Asp-Ang I, Ang-(1-9), and alamandine, hold therapeutic capability for addressing metabolic disturbances linked to type 2 diabetes. The possibility of AT2R heteromerization with either AT1R or MAS receptor offers an exciting area for future research, particularly concerning therapeutic strategies to improve glycemic control. This review focuses on therapeutic opportunities to improve insulin sensitivity, taking advantage of the protective arm of the RAS.
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Affiliation(s)
- Fernando P Dominici
- Departamento de Química Biológica and IQUIFIB (UBA-CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | - Mariela M Gironacci
- Departamento de Química Biológica and IQUIFIB (UBA-CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jorge A Narvaez Pardo
- Departamento de Química Biológica and IQUIFIB (UBA-CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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Wangensteen R, Gómez-Guzmán M, Banegas I, Rodríguez-Gómez I, Jiménez R, Duarte J, García-Estañ J, Vargas F. Vasoconstrictor and Pressor Effects of Des-Aspartate-Angiotensin I in Rat. Biomedicines 2022; 10:biomedicines10061230. [PMID: 35740253 PMCID: PMC9220223 DOI: 10.3390/biomedicines10061230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 12/04/2022] Open
Abstract
This study investigated the vasoactive effects of des-aspartate-angiotensin-I (DAA-I) in male Wistar rats on whole body vascular bed, isolated perfused kidneys, and aortic rings. Dose–response curves to DAA-I were compared with those to angiotensin II (Ang II). The Ang II-type-1 (AT1) receptor blocker, losartan, was used to evaluate the role of AT1 receptors in the responses to DAA-I. Studies were also conducted of the responsiveness in aortic rings after endothelium removal, nitric oxide synthase inhibition, or AT2 receptor blockade. DAA-I induced a dose-related systemic pressor response that was shifted to the right compared with Ang II. Losartan markedly attenuated the responsiveness to DAA-I. DAA-I showed a similar pattern in renal vasculature and aortic rings. In aortic rings, removal of endothelium and nitric oxide inhibition increased the sensitivity and maximal response to DAA-I and Ang II. AT2 receptor blockade did not significantly affect the responsiveness to DAA-I. According to these findings, DAA-I increases the systemic blood pressure and vascular tone in conductance and resistance vessels via AT1 receptor activation. This vasoconstrictor effect of DAA-I participates in the homeostatic control of arterial pressure, which can also contribute to the pathogenesis of hypertension. DAA-I may therefore be a potential therapeutic target in cardiovascular disease.
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Affiliation(s)
- Rosemary Wangensteen
- Area of Physiology, Department of Health Sciences, University of Jaén, 23071 Jaén, Spain; (R.W.); (I.B.)
| | - Manuel Gómez-Guzmán
- Department of Pharmacology, University of Granada, 18071 Granada, Spain; (M.G.-G.); (R.J.); (J.D.)
| | - Inmaculada Banegas
- Area of Physiology, Department of Health Sciences, University of Jaén, 23071 Jaén, Spain; (R.W.); (I.B.)
| | | | - Rosario Jiménez
- Department of Pharmacology, University of Granada, 18071 Granada, Spain; (M.G.-G.); (R.J.); (J.D.)
| | - Juan Duarte
- Department of Pharmacology, University of Granada, 18071 Granada, Spain; (M.G.-G.); (R.J.); (J.D.)
| | - Joaquín García-Estañ
- Department of Physiology, Faculty of Medicine, IMIB, University of Murcia, 30120 Murcia, Spain;
| | - Félix Vargas
- Department of Physiology, University of Granada, 18071 Granada, Spain;
- Correspondence: ; Tel.: +34-958243520
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Gatineau E, Gong MC, Yiannikouris F. Soluble Prorenin Receptor Increases Blood Pressure in High Fat-Fed Male Mice. Hypertension 2019; 74:1014-1020. [PMID: 31378099 PMCID: PMC6739191 DOI: 10.1161/hypertensionaha.119.12906] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/25/2019] [Indexed: 01/13/2023]
Abstract
Obesity-related hypertension is a major public health concern. We recently demonstrated that plasma levels of the soluble form of the prorenin receptor (sPRR) were elevated in obesity-associated hypertension. Therefore, in the present study, we investigated the contribution of sPRR to blood pressure (BP) elevation in the context of obesity. High fat-fed C57BL/6 male mice were infused with vehicle or sPRR (30 µg/kg per day) via subcutaneously implanted osmotic minipump for 4 weeks. BP parameters were recorded using radiotelemetry devices. Male mice infused with sPRR exhibited higher systolic BP and mean arterial pressure and lower spontaneous baroreflex sensitivity than mice infused with vehicle. To define mechanisms involved in systolic BP elevation, mice were injected with an AT1R (Ang II [angiotensin II] type 1 receptor) antagonist (losartan), a muscarinic receptor antagonist (atropine), a β-adrenergic antagonist (propranolol), and a ganglionic blocker (chlorisondamine). Losartan did not blunt sPRR-induced elevation in systolic BP. Chlorisondamine treatment exacerbated the decrease in mean arterial pressure in male mice infused with sPRR. These results demonstrated that sPRR induced autonomic nervous dysfunction. Interestingly, plasma leptin levels were increased in high fat-fed C57BL/6 male mice infused with sPRR. Overall, our results indicated that sPRR increased systolic BP through an impairment of the baroreflex sensitivity and an increase in the sympathetic tone potentially mediated by leptin in high fat-fed C57BL/6 male mice.
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Affiliation(s)
- Eva Gatineau
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Ming C. Gong
- Department of Physiology, University of Kentucky, Lexington, KY
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Abstract
In an earlier single-dose escalation study to evaluate the safety and pharmacokinetics of orally administered des-aspartate-angiotensin I (DAA-I) in healthy subjects, the plasma level of DAA-I could not be determined because DAA-I is rapidly degraded in the circulation. The present study investigated the oral bioavailability of DAA-I by measuring the prostaglandin E2 metabolite (PGEM) in the plasma samples of the same trial. PGEM is a stable derivative of PGE2, which has been shown to be a biomarker of DAA-I. The data show that plasma from two of the three subjects who were orally administered the efficacious preclinical dose of 0.70 mg/kg DAA-I exhibited a significant PGEM peak at 5–6 h postdose. Plasma of subjects who were administered 0.08 and 1.5 mg/kg DAA-I, the subefficacious and two-times efficacious dose, respectively, did not exhibit a similar PGEM peak. This observation is concordant with the known in vivo actions of DAA-I, especially its hypoglycemic action where maximum efficacy occurred at a dose of 0.7 mg/kg, and decreased to nil at the two-times efficacious dose. The onset of the PGEM peak at 5–6 h postdose was closed to the 4-h onset of absorption of [C14]DAA-I seen in preclinical rat studies, albeit the absorption kinetics between rodents and humans are not identical. The occurrence of polymorphism of enzymes involved in the formation and degradation of PGE2 is common, and this has been attributed to contributing to the variation in response, onset and peak PGEM observed among the three subjects who were administered the efficacious dose.
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Sportiello L, Rafaniello C, Sullo MG, Nica M, Scavone C, Bernardi FF, Colombo DM, Rossi F. No substantial gender differences in suspected adverse reactions to ACE inhibitors and ARBs: results from spontaneous reporting system in Campania Region. Expert Opin Drug Saf 2017; 15:101-107. [PMID: 27875922 DOI: 10.1080/14740338.2016.1225720] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Today, there is a poor knowledge about gender differences in adverse drug reactions (ADRs) to cardiovascular drugs such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). Therefore, the aim of this study was to analyze spontaneous reports of suspected ADRs induced by ACE-inhibitors and ARBs, between January 2001 and June 2015, recorded in a Region of Southern Italy (Campania Region). METHODS We performed a descriptive gender-related analysis of regional safety data, obtained from the spontaneous reporting system. RESULTS In the considered period, 772 suspected ADRs to ACE inhibitors and ARBs (in monotherapy or in combination) were reported with a slightly higher frequency in men compared with women. In both genders, the most involved category was ARBs in combination, whereas the most prescribed active substance was ramipril. General and administration site conditions, vascular disorders and modification of laboratory parameters were more common in men, while respiratory disorders were most common in women. In 88.2% of cases, not serious ADRs were described more by men than women. CONCLUSIONS This analysis suggested no substantial gender differences. Further studies such as randomized population studies or meta-analysis of ACE inhibitors and ARBs randomized studies are needed to clarify whether gender differences exist in the safety profile of these drugs.
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Affiliation(s)
- Liberata Sportiello
- a Regional Centre of Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine , Second University of Naples , Naples , Italy
| | - Concetta Rafaniello
- a Regional Centre of Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine , Second University of Naples , Naples , Italy
| | - Maria Giuseppa Sullo
- a Regional Centre of Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine , Second University of Naples , Naples , Italy
| | - Mihaela Nica
- b Novartis Farma Italia , Value & Access Department , Varese , Italy
| | - Cristina Scavone
- a Regional Centre of Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine , Second University of Naples , Naples , Italy
| | - Francesca Futura Bernardi
- a Regional Centre of Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine , Second University of Naples , Naples , Italy
| | | | - Francesco Rossi
- a Regional Centre of Pharmacovigilance and Pharmacoepidemiology, Department of Experimental Medicine , Second University of Naples , Naples , Italy
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Sim MK, Lee KO. Author's Reply to Srinivas: "A Single Dose-Escalation Study to Evaluate the Safety and Pharmacokinetics of Orally Administered Des-Aspartate Angiotensin I in Healthy Subjects". Drugs R D 2016; 17:243-244. [PMID: 27905016 PMCID: PMC5318324 DOI: 10.1007/s40268-016-0156-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Meng-Kwoon Sim
- Department of Pharmacology, Yong Loo Lin School of Medicine, Block MD 3 Level 4 #04-01, 16 Medical Drive, Singapore, 117600 Singapore
| | - Kok-Onn Lee
- Department of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228 Singapore
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Comment on: "A Single Dose-Escalation Study to Evaluate the Safety and Pharmacokinetics of Orally Administered Des-aspartate Angiotensin I in Healthy Subjects". Drugs R D 2016; 17:241-242. [PMID: 27905015 PMCID: PMC5318323 DOI: 10.1007/s40268-016-0155-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Lee KO, Khoo CM, Chowbay B, Chan YH, Sim MK. A Single Dose-Escalation Study to Evaluate the Safety and Pharmacokinetics of Orally Administered Des-Aspartate Angiotensin I in Healthy Subjects. Drugs R D 2016; 16:317-326. [PMID: 27681888 PMCID: PMC5114201 DOI: 10.1007/s40268-016-0143-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Des-aspartate-angiotensin I (DAA-I) is an endogenous angiotensin peptide and a prototype angiotensin receptor agonist (ARA). It acts on the angiotensin AT1 receptor and antagonises the deleterious actions of angiotensin II. DAA-I attenuates animal models of human disease in which angiotensin II has been implicated, such as cardiac hypertrophy, neointima formation, arteriosclerosis, renal failure, post-infarction injuries, diabetes, viral infection, chemical-induced inflammation, heat stroke, cancer, and gamma radiation lethality. DAA-I crosses Caco-2 cells and is effective at sub-nanomolar concentrations. These two properties are responsible for its oral efficacy. A single dose-escalation study was conducted to evaluate the safety, tolerability and pharmacokinetics of orally administered DAA-I in 18 healthy subjects. DAA-I was safe and well tolerated by the subjects, who were administered either 0.08, 0.70 or 1.50 mg/kg of the compound. The heart rate and systolic and diastolic blood pressures determined at each post-dose measurement remained within the clinically acceptable range. Across all cohorts, DAA-I had no substantial effect on blood pressures compared with placebo. Electrocardiographs (ECGs) were normal, and none of the subjects complained of chest discomfort. All clinical laboratory tests obtained before and after DAA-I and placebo treatment were normal. Pharmacokinetic analysis over a 12-h period following DAA-I administration did not show any increase of its level beyond basal concentration. This is in line with studies showing that intravenously administered DAA-I is rapidly metabolized and has a short half-life. We postulate that, during its short systemic sojourn, DAA-I exerts its actions via biased agonism on the angiotensin AT1 receptor. The ClinicalTrial.gov assignment number for this study is NCT02666196.
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Affiliation(s)
- Ko-Onn Lee
- Department of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228, Singapore
| | - Chin-Meng Khoo
- Department of Medicine, National University of Singapore, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228, Singapore
| | - Balram Chowbay
- Laboratory of Clinical Pharmacology, Division of Medical Sciences, Humphrey Oei Institute of Cancer Research, National Cancer Centre, Singapore, Singapore
- Clinical Pharmacology Core, Sing Health, Singapore, Singapore
- Office of Clinical Sciences, Duke-NUS Graduate Medical School Singapore, Singapore, Singapore
| | - Yiong-Huak Chan
- Biostatistics Unit, Yong Loo Lin School of Medicine, National University Health System, 1E Kent Ridge Road, NUHS Tower Block Level 11, Singapore, 119228, Singapore
| | - Meng-Kwoon Sim
- Department of Pharmacology, Yong Loo Lin School of Medicine, Block MD 3 Level 4 #04-01, 16 Medical Drive, Singapore, 117600, Singapore.
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Morinelli TA, Luttrell LM, Strungs EG, Ullian ME. Angiotensin II receptors and peritoneal dialysis-induced peritoneal fibrosis. Int J Biochem Cell Biol 2016; 77:240-50. [PMID: 27167177 PMCID: PMC5038354 DOI: 10.1016/j.biocel.2016.04.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 12/22/2022]
Abstract
The vasoactive hormone angiotensin II initiates its major hemodynamic effects through interaction with AT1 receptors, a member of the class of G protein-coupled receptors. Acting through its AT1R, angiotensin II regulates blood pressure and renal salt and water balance. Recent evidence points to additional pathological influences of activation of AT1R, in particular inflammation, fibrosis and atherosclerosis. The transcription factor nuclear factor κB, a key mediator in inflammation and atherosclerosis, can be activated by angiotensin II through a mechanism that may involve arrestin-dependent AT1 receptor internalization. Peritoneal dialysis is a therapeutic modality for treating patients with end-stage kidney disease. The effectiveness of peritoneal dialysis at removing waste from the circulation is compromised over time as a consequence of peritoneal dialysis-induced peritoneal fibrosis. The non-physiological dialysis solution used in peritoneal dialysis, i.e. highly concentrated, hyperosmotic glucose, acidic pH as well as large volumes infused into the peritoneal cavity, contributes to the development of fibrosis. Numerous trials have been conducted altering certain components of the peritoneal dialysis fluid in hopes of preventing or delaying the fibrotic response with limited success. We hypothesize that structural activation of AT1R by hyperosmotic peritoneal dialysis fluid activates the internalization process and subsequent signaling through the transcription factor nuclear factor κB, resulting in the generation of pro-fibrotic/pro-inflammatory mediators producing peritoneal fibrosis.
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Affiliation(s)
- Thomas A Morinelli
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States.
| | - Louis M Luttrell
- Division of Endocrinology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States; Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, United States
| | - Erik G Strungs
- Division of Endocrinology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States
| | - Michael E Ullian
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States; Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, United States
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Des-aspartate-angiotensin I causes specific release of PGE2 and PGI2 in HUVEC via the angiotensin AT1 receptor and biased agonism. Eur J Pharmacol 2015; 768:173-81. [PMID: 26524410 DOI: 10.1016/j.ejphar.2015.10.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/23/2015] [Accepted: 10/28/2015] [Indexed: 11/23/2022]
Abstract
DAA-I (des-aspartate-angiotensin I), an endogenous angiotensin, had been shown earlier to ameliorate animal models of cardiovascular diseases via the angiotensin AT1 receptor and prostaglandins. The present study investigated further the action of DAA-I on the release of PGE2, PGI2, PGF2α and TXA2 in HUVEC. 10(-11)-10(-8)M DAA-I and 15min incubation specifically released PGE2 and PGI2. The release was inhibited by losartan and indomethacin but not by PD123319 and NS398 indicating that the angiotensin AT1 receptor and COX-1 mediate the release. At concentrations higher than 10(-7)M, DAA-I mimics the action of angiotensin II by releasing TXA2 but had no effect on the production of PGF2α. At similar concentrations and 4h incubation, DAA-I increased the release of the 4 prostaglandins via the angiotensin AT1 receptor and COX-2, again mimicking the action of angiotensin II. HUVEC that were preincubated with DAA-I or angiotensin II, released similar profiles of prostaglandins when incubated with arachidonic acid after the angiotensin had been washed off. We postulate that the internalized DAA-I/receptor complex remains active and mediates the conversion of arachidonic acid to the respective prostaglandins. The release of PGE2 and PGI2 via the angiotensin AT1 receptor and COX-1 is a novel specific action of DAA-I and is likely responsible for its beneficial effects seen in earlier studies. This specific action is definable as a biased agonism of the angiotensin AT1 receptor, which identifies DAA-I as a novel biased agonist and potential therapeutic that is able to produce specific prostaglandins at nanomolar concentrations.
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Role of the Renin-Angiotensin-Aldosterone System and Its Pharmacological Inhibitors in Cardiovascular Diseases: Complex and Critical Issues. High Blood Press Cardiovasc Prev 2015; 22:429-44. [PMID: 26403596 DOI: 10.1007/s40292-015-0120-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 01/11/2023] Open
Abstract
Hypertension is one of the major risk factor able to promote development and progression of several cardiovascular diseases, including left ventricular hypertrophy and dysfunction, myocardial infarction, stroke, and congestive heart failure. Also, it is one of the major driven of high cardiovascular risk profile in patients with metabolic complications, including obesity, metabolic syndrome and diabetes, as well as in those with renal disease. Thus, effective control of hypertension is a key factor for any preventing strategy aimed at reducing the burden of hypertension-related cardiovascular diseases in the clinical practice. Among various regulatory and contra-regulatory systems involved in the pathogenesis of cardiovascular and renal diseases, renin-angiotensin system (RAS) plays a major role. However, despite the identification of renin and the availability of various assays for measuring its plasma activity, the specific pathophysiological role of RAS has not yet fully characterized. In the last years, however, several notions on the RAS have been improved by the results of large, randomized clinical trials, performed in different clinical settings and in different populations treated with RAS inhibiting drugs, including angiotensin converting enzyme (ACE) inhibitors and antagonists of the AT1 receptor for angiotensin II (ARBs). These findings suggest that the RAS should be considered to have a central role in the pathogenesis of different cardiovascular diseases, for both therapeutic and preventive purposes, without having to measure its level of activation in each patient. The present document will discuss the most critical issues of the pathogenesis of different cardiovascular diseases with a specific focus on RAS blocking agents, including ACE inhibitors and ARBs, in the light of the most recent evidence supporting the use of these drugs in the clinical management of hypertension and hypertension-related cardiovascular diseases.
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Wang H, Sethi G, Loke WK, Sim MK. Des-Aspartate-Angiotensin I Attenuates Mortality of Mice Exposed to Gamma Radiation via a Novel Mechanism of Action. PLoS One 2015; 10:e0138009. [PMID: 26378927 PMCID: PMC4574738 DOI: 10.1371/journal.pone.0138009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 08/24/2015] [Indexed: 01/09/2023] Open
Abstract
ACE inhibitors and ARBs (angiotensin receptor blockers) have been shown to attenuate radiation injuries in animal models of lethal gamma irradiation. These two classes of drug act by curtailing the actions of angiotensin II-linked inflammatory pathways that are up-regulated during gamma radiation in organ systems such as the brain, lung, kidney, and bone marrow. ACE inhibitors inhibit ACE and attenuate the formation of angiotensin II from angiotensin I; ARBs block the angiotensin AT1 receptor and attenuate the actions of angiotensin II that are elicited through the receptor. DAA-I (des-aspartate-angiotensin I), an orally active angiotensin peptide, also attenuates the deleterious actions of angiotensin II. It acts as an agonist on the angiotensin AT1 receptor and elicits responses that oppose those of angiotensn II. Thus, DAA-I was investigated for its anticipated radioprotection in gamma irradiated mice. DAA-I administered orally at 800 nmole/kg/day for 30 days post exposure (6.4 Gy) attenuated the death of mice during the 30-day period. The attenuation was blocked by losartan (50 nmole/kg/day, i.p.) that was administered sequential to DAA-I administration. This shows that the radioprotection was mediated via the angiotensin AT1 receptor. Furthermore, the radioprotection correlated to an increase in circulating PGE2 of surviving animals, and this suggests that PGE2 is involved in the radioprotection in DAA-I-treated mice. At the hematopoietic level, DAA-I significantly improved two syndromes of myelosuppression (leucopenia and lymphocytopenia), and mice pre-treated with DAA-I prior to gamma irradiation showed significant improvement in the four myelodysplastic syndromes that were investigated, namely leucopenia, lymphocytopenia, monocytopenia and thrombocytopenia. Based on the known ability of PGE2 to attenuate the loss of functional hematopoietic stem and progenitor cells in radiation injury, we hypothesize that PGE2 mediated the action of DAA-I. DAA-I completely attenuated the increase in circulating level of two inflammatory cytokines, TNFα and IL-6, in irradiated mice; and this shows that DAA-I exerted additional anti-inflammatory actions, which could also have contributed to its radioprotection. These findings show that DAA-I acts via a novel mechanism of action on the angiotensin AT1 receptor to specifically release PGE2, which mediates radioprotection in the gamma irradiated mice.
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Affiliation(s)
- Hong Wang
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD11, 10 Medical Drive, Singapore, Singapore
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD11, 10 Medical Drive, Singapore, Singapore
| | - Weng-Keong Loke
- Agent Diagnostic and Therapeutics Laboratory, Defence & Environmental Research Institute, DSO National Laboratories, 11 Stockport Road, Singapore, Singapore
| | - Meng-Kwoon Sim
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Block MD11, 10 Medical Drive, Singapore, Singapore
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