Amplifying effect of chronic lisinopril therapy on diastolic function and the angiotensin-(1-7) Axis by the G1 agonist in ovariectomized spontaneously hypertensive rats.

G protein-coupled estrogen receptor (GPER) activation by G1 attenuates diastolic dysfunction from estrogen loss, which may be partly due to suppression of angiotensin II pathological actions. We aimed to determine the independent effects of 8 weeks of G1 (100 µg/kg/d, subcutaneous pellet), ACE-inhibition (ACEi; lisinopril 10 mg/kg, drinking water), or combination therapy versus vehicle in the ovariectomized (OVX) spontaneously hypertensive rat (SHR) on cardiac function and morphometrics (echocardiography), serum equilibrium of angiotensins (mass spectroscopy) and cardiac components of the RAS (Western blotting). G1 alone and when combined with ACEi enhanced myocardial relaxation (é: 30 and 17%) and diastolic wall strain (DWS: 76 and 68%) while reducing relative wall thickness (RWT: 20 and 33%) and filling pressures (E/é: 30 and 37%). Cardiac expression levels of Mas receptor (Mas-R) and ACE2 also increased in the presence of G1. Strong antihypertensive effects of lisinopril monotherapy were associated with reductions in RWT, collagen deposition and E/é without overtly altering é or DWS. Chronic ACEi also increased cardiac levels of Mas-R and AT1-R and tilted the circulating RAS toward the formation of Ang-(1-7), which was amplified in the presence of G1. In vitro studies further revealed that an inhibitor to prolyl endopeptidase (PEP), but not to neprilysin, significantly reduced serum Ang-(1-7) levels in G1-treated rats, suggesting that G1 might be increasing Ang-(1-7) formation via PEP. We conclude that activating GPER with G1 augments components of the cardiac RAS and improves diastolic function without lowering blood pressure, and that lisinopril-induced blood pressure control and cardiac alterations in OVX SHR are permissive in facilitating G1 to augment Ang-(1-7) in serum, thereby strengthening its cardioprotective benefits.

Physical Exercise and ACE2-Angiotensin-(1-7)-Mas Receptor Axis of the Renin Angiotensin System.

BACKGROUND: Many physiological responses of the Renin Angiotensin System (RAS) are associated with two opposite pathways: (1) a classical one formed by angiotensin-converting enzyme (ACE), Angiotensin II (Ang II) and Angiotensin type 1 (AT1) receptor, which is associated to vasoconstriction, cell proliferation, organ hypertrophy, sodium retention and aldosterone release and (2) a counter-regulatory or vasodilator pathway comprising angiotensin-converting enzyme 2 (ACE2), Angiotensin-(1-7) [Ang-(1-7)] and Mas receptor, which is involved in vasodilation, antiproliferation, anti-hypertrophy, cardioprotective and renoprotective actions. OBJECTIVE: This review aimed to bring up-to-date on the interactions between physical exercise and the vasodilator axis of the RAS (ACE2-Ang-(1-7)-Mas receptor axis). We also investigated the relation of acute and chronic exercise with blood pressure regulation and components of the vasodilator axis of the RAS. METHODS: We searched studies with animal models and humans in PUBMED, LILACS and IBECS. RESULTS: Experimental studies showed that physical training can stimulate ACE2-Ang-(1-7)-Mas receptor axis in parallel with the inhibition of ACE-Ang II-AT1 receptor pathway. However, up to now, the interaction between the counter-regulatory RAS axis and physical training is not investigated in humans. CONCLUSION: The activation of ACE2-Ang-(1-7)-Mas receptor axis may have a role in the beneficial effects of physical training in experimental models. Further studies with humans are necessary.

Neprilysin Is Required for Angiotensin-(1-7)'s Ability to Enhance Insulin Secretion via Its Proteolytic Activity to Generate Angiotensin-(1-2).

Recent work has renewed interest in therapies targeting the renin-angiotensin system (RAS) to improve ß-cell function in type 2 diabetes. Studies show that generation of angiotensin-(1-7) by ACE2 and its binding to the Mas receptor (MasR) improves glucose homeostasis, partly by enhancing glucose-stimulated insulin secretion (GSIS). Thus, islet ACE2 upregulation is viewed as a desirable therapeutic goal. Here, we show that, although endogenous islet ACE2 expression is sparse, its inhibition abrogates angiotensin-(1-7)-mediated GSIS. However, a more widely expressed islet peptidase, neprilysin, degrades angiotensin-(1-7) into several peptides. In neprilysin-deficient mouse islets, angiotensin-(1-7) and neprilysin-derived degradation products angiotensin-(1-4), angiotensin-(5-7), and angiotensin-(3-4) failed to enhance GSIS. Conversely, angiotensin-(1-2) enhanced GSIS in both neprilysin-deficient and wild-type islets. Rather than mediating this effect via activation of the G-protein-coupled receptor (GPCR) MasR, angiotensin-(1-2) was found to signal via another GPCR, namely GPCR family C group 6 member A (GPRC6A). In conclusion, in islets, intact angiotensin-(1-7) is not the primary mediator of beneficial effects ascribed to the ACE2/angiotensin-(1-7)/MasR axis. Our findings warrant caution for the concurrent use of angiotensin-(1-7) compounds and neprilysin inhibitors as therapies for diabetes.

Immunologic Effects of the Renin-Angiotensin System.

Inappropriate activation of the renin-angiotensin system (RAS) exacerbates renal and vascular injury. Accordingly, treatment with global RAS antagonists attenuates cardiovascular risk and slows the progression of proteinuric kidney disease. By reducing BP, RAS inhibitors limit secondary immune activation responding to hemodynamic injury in the target organ. However, RAS activation in hematopoietic cells has immunologic effects that diverge from those of RAS stimulation in the kidney and vasculature. In preclinical studies, activating type 1 angiotensin (AT1) receptors in T lymphocytes and myeloid cells blunts the polarization of these cells toward proinflammatory phenotypes, protecting the kidney from hypertensive injury and fibrosis. These endogenous functions of immune AT1 receptors temper the pathogenic actions of renal and vascular AT1 receptors during hypertension. By counteracting the effects of AT1 receptor stimulation in the target organ, exogenous administration of AT2 receptor agonists or angiotensin 1-7 analogs may similarly limit inflammatory injury to the heart and kidney. Moreover, although angiotensin II is the classic effector molecule of the RAS, several RAS enzymes affect immune homeostasis independently of canonic angiotensin II generation. Thus, as reviewed here, multiple components of the RAS signaling cascade influence inflammatory cell phenotype and function with unpredictable and context-specific effects on innate and adaptive immunity.

The tACE/Angiotensin (1-7)/Mas Axis Protects Against Testicular Ischemia Reperfusion Injury.

OBJECTIVE: To investigate whether exogenous angiotensin (Ang)-(1-7) administration can protect against the damaging consequences of testicular ischemia reperfusion (tIR) injury. MATERIALS AND METHODS: Eighteen male Sprague-Dawley rats were divided equally among the following 3 groups: sham, unilateral tIR injury (1 hour of ischemic treatment and 4 hours of reperfusion), and tIR + Ang-(1-7) (0.3 mg/kg). Testicular tissues obtained from the rats were evaluated for the expression of testicular angiotensin-converting enzyme (tACE), Ang-(1-7), and the Ang-(1-7)-specific receptor Mas by immunohistochemistry and enzyme-linked immunosorbent assay. Reduced spermatogenesis, induction of the caspase-8 pathway, and nitric oxide (NO) generation were assessed. The effects of tIR and Ang-(1-7) treatment on the PI3K/Akt antiapoptosis pathway were also investigated. RESULTS: Testicular morphological changes and reduced spermatogenesis associated with decreased expression of the tACE/Ang-(1-7)/Mas axis were observed during tIR. These effects were also accompanied by increased activity of caspase-3 and -8, downregulation of the survivin and BAD transcripts, and decreased NO formation. During tIR, PTEN expression was increased, leading to inactivation of the PI3K/Akt pathway. Acute treatment with Ang-(1-7) prior to reperfusion attenuated the tIR-induced damage described above. CONCLUSION: Expression of the tACE/Ang-(1-7)/Mas axis was downregulated during tIR. Administration of exogenous Ang-(1-7) prior to reperfusion rescued tACE and Mas expression and protected against germ cell apoptosis and oxidative stress. Increased NO generation and activation of the PI3K/Akt signaling pathway may have partially contributed to these effects. The tACE/Ang-(1-7)/Mas axis likely plays a role in the maintenance of normal testis physiology and spermatogenesis.

Cardiac ACE2/angiotensin 1-7/Mas receptor axis is activated in thyroid hormone-induced cardiac hypertrophy.

OBJECTIVES: Thyroid hormone (TH) promotes marked effects on the cardiovascular system, including the development of cardiac hypertrophy. Some studies have demonstrated that the renin-angiotensin system (RAS) is a key mediator of the cardiac growth in response to elevated TH levels. Although some of the main RAS components are changed in cardiac tissue on hyperthyroid state, the potential modulation of the counter regulatory components of the RAS, such as angiotensin-converting enzyme type 2 (ACE2), angiotensin 1-7 (Ang 1-7) levels and Mas receptor induced by hyperthyroidism is unknown. The aim of this study was to investigate the effect of hyperthyroidism on cardiac Ang 1-7, ACE2 and Mas receptor levels. METHODS: Hyperthyroidism was induced in Wistar rats by daily intraperitoneal injections of T4 for 14 days. RESULTS: Although plasma Ang 1-7 levels were unchanged by hyperthyroidism, cardiac Ang 1-7 levels were increased in TH-induced cardiac hypertrophy. ACE2 enzymatic activity was significantly increased in hearts from hyperthyroid animals, which may be contributing to the higher Ang 1-7 levels observed in the T4 group. Furthermore, elevated cardiac levels of Ang 1-7 levels were accompanied by increased Mas receptor protein levels. CONCLUSION: The counter-regulatory components of the RAS are activated in hyperthyroidism and may be contributing to modulate the cardiac hypertrophy in response to TH.

Angiotensin-(1-7)/Mas axis modulates fear memory and extinction in mice.

Inappropriate defense-alerting reaction to fear is a common feature of neuropsychiatric diseases. Therefore, impairments in brain circuits, as well as in molecular pathways underlying the neurovegetative adjustments to fear may play an essential role on developing neuropsychiatric disorders. Here we tested the hypothesis that interfering with angiotensin-(1-7) [Ang-(1-7)]/Mas receptor axis homeostasis, which appears to be essential to arterial pressure control, would affect fear memory and extinction. Mas knockout (MasKO) mice, in FVB/N background, showed normal cued fear memory and extinction, but increased freezing in response to context. Next, as FVB/N has poor performance in contextual fear memory, we tested MasKO in mixed 129xC57BL/6 background. MasKO mice behaved similarly to wild-type (WT), but memory extinction was slower in contextual fear conditioning to a weak protocol (1CS/US). In addition, delayed extinction in MasKO mice was even more pronounced after a stronger protocol (3CS/US). We showed previously that Angiotensin II receptor AT1 antagonist, losantan, rescued object recognition memory deficit in MasKO mice. Here, losartan was also effective. Memory extinction was accelerated in MasKO mice after treatment with losartan. In conclusion, we showed for the first time that Ang-(1-7)/Mas axis may modulate fear memory extinction. Furthermore, we suggest MasKO mice as an animal model to study post-traumatic stress disorder (PTSD).

Avaliação dos eixos ECA / ANG II / AT1 e ECA-2 / ANG (1-7) / MAS em fibroblastos de gengiva e ligamento periodontal humanos estimulados por IL-1ß e sua contribuição na produção e regulação de citocinas e quimiocinas / Evaluation ACE /ANG II /AT1 and ACE-2 /ANG (1-7) /MAS axis in gingival and periodontal ligament human fibroblasts stimulated with IL-1ß and its contribution in the production of cytokines and chemokines

O Sistema renina-angiotensina (SRA) tem sido relatado como um importante modulador de processos inflamatórios e imunológicos, incluindo a doença periodontal (DP). Estudos sugerem neste sistema um eixo alternativo (ECA-2 /ANG(1-7) /MAS) que atuaria como um contra-regulador de efeitos mediados pelo clássico eixo (ECA /ANGII /AT1). Sabe-se que bactérias periodontopatogênicas, como a Porphyromonas gingivalis (Pg), possuem componentes bioativos de membrana (ex. lipopolissacarídeos-LPS) capazes de induzir uma forte resposta imune no hospedeiro devido à liberação de citocinas nas células, entre elas Interleucina (IL)- 1ß. Neste contexto, fibroblastos são as células mais abundantes nos tecidos periodontais e possuem em sua superfície celular receptores necessários para o reconhecimento da invasão bacteriana, ativando cascatas intracelulares, que levam à produção de citocinas. O objetivo deste estudo foi verificar se os eixos ECA/ ANGII/ AT1 e ECA-2/ ANG(1-7)/ MAS contribuem para a produção e/ ou regulação de citocinas inflamatórias (CI) por fibroblastos de gengiva humana (HGF) e ligamento periodontal humano (HPLF) estimulados por IL-1ß. Após o pré-tratamento com Losartan e Ang (1-7) ou silenciamento mediado por RNA de interferência (RNAi) de AT1, HGF e HPLF foram estimulados por IL-1ß por 3 horas (RNAm) ou 24 horas (proteína). Expressão de RNAm para AT1, MAS, ECA, ECA-2, IL-1ß, TNF-α, IL-6, IL-8, IL-10, TGF-ß, CXCL12, RANK-L e OPG foram avaliados por RT-qPCR e das proteínas IL-6, IL-8, ECA e ECA-2 por ELISA. Foi realizado também Western Blot para detecção de AT1 e ECA nos extratos celulares e dosagem de nitrito no sobrenadante das culturas. Ambos os subtipos de fibroblastos mostraram aumento da expressão de RNAm para AT1, IL-1ß, IL-6, IL-8, TNF-α e OPG, quando estimulados por IL-1ß. No entanto, apenas em HPLF foi observado aumento para MAS, ECA e TGF-ß. Losartan e Ang (1-7) não modularam o transcrito, a secreção de CI e nem a produção de nitrito no sobrenadante das culturas, tanto em HGF como em HPLF. O silenciamento do receptor AT1 reduziu a secreção de IL-6 e IL-8 induzida por IL-1ß em cultura de HGF e HPLF e aumentou a expressão gênica de OPG somente em HGF. Estes resultados sugerem que o silenciamento de AT1, mas não o bloqueio farmacológico deste receptor pelo antagonista Losartan, em HGF e HPLF, pode controlar a produção de IL-6 e IL-8, que por sua vez contribuem para a patogênese periodontal.(AU)

The renin-angiotensin system (RAS) has been reported as an important modulator of inflammatory and immune responses, including periodontal disease (PD). Studies suggest an alternative axis as part of this system (ACE-2 / ANG (1-7) / MAS) that would act as counter-regulatory to the classical axis (ECA / ANGII / AT1). It is known that periodontal bacteria such as Porphyromonas gingivalis (Pg) have bioactive components in their membrane (such as lipopolysaccharide-LPS) capable of inducing a strong immune response in the host due to the release of cytokines in cells, including interleukin (IL) - 1ß. In this regard, fibroblasts are the most abundant cells in periodontal tissues and receptors needed for the recognition of bacterial invasion by activating intracellular cascades that lead to cytokine production. The aim of this study was to determine whether the axes ACE / ANGII / AT1 and ACE-2 / ANG (1-7) / MAS contribute to the production and / or regulation of inflammatory cytokines (IC) by fibroblasts of human gingiva (HGF) and human periodontal ligament (HPLF) stimulated IL-1ß. After pre-treatment with Losartan, Ang (1-7) or silencing mediated by RNA interference (RNAi) of AT1, HGF and HPLF were stimulated by IL-1ß for 3 hours (RNAm) or 24 hours (protein). Expression mRNA for AT1, MAS, ACE, ACE-2, IL-1ß, TNF-α, IL-6, IL-8, IL-10, TGF-ß, CXCL12, RANK-L and OPG was assessed by RT- qPCR and proteins IL-6, IL-8, ACE and ACE-2 by ELISA. Western Blot for the detection of AT1 and ECA and dosage of nitrite was also performed. Experiments stimulated by IL-1ß showed a positive control for gene expression AT1, IL-1ß, IL-6, IL-8, TNF-α and OPG in HGF and HPLF and MAS, ACE and TGF-ß only HPLF. Losartan and Ang (1-7) did not modulate the transcription and secretion of IC and no nitrite production in the culture supernatant of HGF and HPLF. The silencing AT1 reduced IL-6 secretion and IL-8 induced by IL- ß in cultured HGF and HPLF and increased OPG gene expression only HGF. These results suggest that silencing AT1, but not pharmacological blockade of this receptor by Losartan in HPLF and HGF, can control the production of IL-6 and IL-8, which in turn contribute to the pathogenesis of periodontal disease.(AU)

Novel players in cardioprotection: Insulin like growth factor-1, angiotensin-(1-7) and angiotensin-(1-9).

Insulin-like growth factor-1, angiotensin-(1-7) and angiotensin-(1-9) have been proposed to be important mediators in cardioprotection. A large body of evidence indicates that insulin like growth factor-1 has pleotropic actions in the heart (i.e., contractility, metabolism, hypertrophy, autophagy, senescence and cell death) and, conversely, its deficiency is associated with impaired cardiac function. Recently, we reported that insulin like growth factor-1 receptor is also located in plasma membrane invaginations with perinuclear localization, highlighting the role of nuclear Ca(2+) signaling in the heart. In parallel, angiotensin-(1-7) and angiotensin (1-9) acting through Mas receptor and angiotensin type 2 receptor have emerged as a novel anti-hypertensive molecules promoting vasodilatation and preventing heart hypertrophy. In this review we discuss the scientific evidence available regarding insulin-like growth factor-1, angiotensin-(1-7) and angiotensin-(1-9) in cardioprotection and its potential application as novel therapeutic targets for treating cardiac diseases.

Upregulation of Angiotensin (1-7)-Mediated Signaling Preserves Endothelial Function Through Reducing Oxidative Stress in Diabetes.

AIMS: Angiotensin-converting enzyme 2 (ACE2)-angiotensin (1-7) [Ang (1-7)]-Mas constitutes the vasoprotective axis and is demonstrated to antagonize the vascular pathophysiological effects of the classical renin-angiotensin system. We sought to study the hypothesis that upregulation of ACE2-Ang (1-7) signaling protects endothelial function through reducing oxidative stress that would result in beneficial outcome in diabetes. RESULTS: Ex vivo treatment with Ang (1-7) enhanced endothelium-dependent relaxation (EDR) in renal arteries from diabetic patients. Both Ang (1-7) infusion via osmotic pump (500 ng/kg/min) for 2 weeks and exogenous ACE2 overexpression mediated by adenoviral ACE2 via tail vein injection (10(9) pfu/mouse) rescued the impaired EDR and flow-mediated dilatation (FMD) in db/db mice. Diminazene aceturate treatment (15 mg/kg/day) activated ACE2, increased the circulating Ang (1-7) level, and augmented EDR and FMD in db/db mouse arteries. In addition, activation of the ACE2-Ang (1-7) axis reduced reactive oxygen species (ROS) overproduction determined by dihydroethidium staining, CM-H2DCFDA fluorescence imaging, and chemiluminescence assay in db/db mouse aortas and also in high-glucose-treated endothelial cells. Pharmacological benefits of ACE2-Ang (1-7) upregulation on endothelial function were confirmed in ACE2 knockout (ACE2 KO) mice both ex vivo and in vitro. INNOVATION: We elucidate that the ACE2-Ang (1-7)-Mas axis serves as an important signal pathway in endothelial cell protection in diabetic mice, especially in diabetic human arteries. CONCLUSION: Endogenous ACE2-Ang (1-7) activation or ACE2 overexpression preserves endothelial function in diabetic mice through increasing nitric oxide bioavailability and inhibiting oxidative stress, suggesting the therapeutic potential of ACE2-Ang(1-7) axis activation against diabetic vasculopathy. Antioxid.

ACE2 and Ang-(1-7) protect endothelial cell function and prevent early atherosclerosis by inhibiting inflammatory response.

BACKGROUND: Angiotensin-converting enzyme 2 (ACE2) is a counter-regulator against ACE by converting angiotensin II (Ang-II) to Ang-(1-7), but the effect of ACE2 and Ang-(1-7) on endothelial cell function and atherosclerotic evolution is unknown. We hypothesized that ACE2 overexpression and Ang-(1-7) may protect endothelial cell function by counterregulation of angiotensin II signaling and inhibition of inflammatory response. METHODS: We used a recombinant adenovirus vector to locally overexpress ACE2 gene (Ad-ACE2) in human endothelial cells in vitro and in apoE-deficient mice in vivo. The Ang II-induced MCP-1, VCAM-1 and E-selectin expression, endothelial cell migration and adhesion of human monocytic cells (U-937) to HUVECs by ACE2 gene transfer were evaluated in vitro. Accelerated atherosclerosis was studied in vivo, and atherosclerosis was induced in apoE-deficient mice which were divided randomly into four groups that received respectively a ACE2 gene transfer, Ad-ACE2, Ad-EGFP, Ad-ACE2 + A779, an Ang-(1-7) receptor antagonist, control group. After a gene transfer for 4 weeks, atherosclerotic pathology was evaluated. RESULTS: ACE2 gene transfer not only promoted HUVECs migration, inhibited adhesion of monocyte to HUVECs and decreased Ang II-induced MCP-1, VCAM-1 and E-selectin protein production in vitro, but also decreased the level of MCP-1, VCAM-1 and interleukin 6 and inhibit atherosclerotic plaque evolution in vivo. Further, administration of A779 increased the level of MCP-1, VCAM-1 and interleukin 6 in vivo and led to further advancements in atherosclerotic extent. CONCLUSIONS: ACE2 and Ang-(1-7) significantly inhibit early atherosclerotic lesion formation via protection of endothelial function and inhibition of inflammatory response.

The angiotensin-converting enzyme 2/angiotensin (1-7)/Mas axis protects against lung fibroblast migration and lung fibrosis by inhibiting the NOX4-derived ROS-mediated RhoA/Rho kinase pathway.

UNLABELLED: Reactive oxygen species (ROS) generated by NADPH oxidase-4 (NOX4) have been shown to initiate lung fibrosis. The migration of lung fibroblasts to the injured area is a crucial early step in lung fibrosis. The angiotensin-converting enzyme 2 (ACE2)/angiotensin (1-7) [Ang(1-7)]/Mas axis, which counteracts the ACE/angiotensin II (AngII)/angiotensin II type 1 receptor (AT1R) axis, has been shown to attenuate pulmonary fibrosis. Nevertheless, the exact molecular mechanism remains unclear. AIMS: To investigate the different effects of the two axes of the renin-angiotensin system (RAS) on lung fibroblast migration and extracellular matrix accumulation by regulating the NOX4-derived ROS-mediated RhoA/Rho kinase (Rock) pathway. RESULTS: In vitro, AngII significantly increased the NOX4 level and ROS production in lung fibroblasts, which stimulated cell migration and α-collagen I synthesis through the RhoA/Rock pathway. These effects were attenuated by N-acetylcysteine (NAC), diphenylene iodonium, and NOX4 RNA interference. Moreover, Ang(1-7) and lentivirus-mediated ACE2 (lentiACE2) suppressed AngII-induced migration and α-collagen I synthesis by inhibiting the NOX4-derived ROS-mediated RhoA/Rock pathway. However, Ang(1-7) alone exerted analogous effects on AngII. In vivo, constant infusion with Ang(1-7) or intratracheal instillation with lenti-ACE2 shifted the RAS balance toward the ACE2/Ang(1-7)/Mas axis, alleviated bleomycin-induced lung fibrosis, and inhibited the RhoA/Rock pathway by reducing NOX4-derived ROS. INNOVATION: This study suggests that the ACE2/Ang(1-7)/Mas axis may be targeted by novel pharmacological antioxidant strategies to treat lung fibrosis induced by AngII-mediated ROS. CONCLUSION: The ACE2/Ang(1-7)/Mas axis protects against lung fibroblast migration and lung fibrosis by inhibiting the NOX4-derived ROS-mediated RhoA/Rock pathway.

Olmesartan potentiates the anti-angiogenic effect of sorafenib in mice bearing Ehrlich's ascites carcinoma: role of angiotensin (1-7).

Local renin-angiotensin systems exist in various malignant tumor tissues; this suggests that the main effector peptide, angiotensin II, could act as a key factor in tumor growth. The underlying mechanisms for the anti-angiogenic effect of angiotensin II type 1 receptor blockers need to be further evaluated. The present study was carried out to investigate the anti-angiogenic effect of olmesartan alone or in combination with sorafenib, an angiotensin (1-7) agonist or an angiotensin (1-7) antagonist in Ehrlich's ascites carcinoma-bearing mice. The tumor was induced by intradermal injection of Ehrlich's ascites carcinoma cells into mice. Tumor discs were used to evaluate the microvessel density; the serum levels of vascular endothelial growth factor (VEGF) and serum insulin-like growth factor I (IGF-I); and their intratumoral receptors, VEGF receptor-2 and IGF-I receptor, respectively. All parameters were determined following the treatment course, which lasted for 21 days post-inoculation. Monotherapy with olmesartan and its combination with sorafenib resulted in a significant reduction in microvessel density and serum levels of VEGF and IGF-I, as well as their intratumoral receptors. In addition, the combination of olmesartan (30 mg/kg) with an angiotensin (1-7) agonist reduced the microvessel density, IGF-I serum levels and the levels of its intratumoral receptor. In conclusion, olmesartan reduced the levels of the angiogenesis markers IGF-I and VEGF and down-regulated the intratumoral expression of their receptors in a dose-dependent manner, and these effects were dependent on the angiotensin (1-7) receptor. These results suggest that olmesartan is a promising adjuvant to sorafenib in the treatment of cancer.

Receptor MAS protects mice against hypothermia and mortality induced by endotoxemia.

The renin-angiotensin (Ang) system is involved in maintaining cardiovascular function by regulating blood pressure and electrolyte homeostasis. More recently, alternative pathways within the renin-angiotensin system have been described, such as the ACE-2/Ang-(1-7)/Mas axis, with opposite effects to the ones of the ACE/Ang-II/AT1 axis. Correspondingly, our previous work reported that Ang-(1-7) via its receptor Mas inhibits the mRNA expression of the proinflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor-α increased by lipopolysaccharide (LPS) in mouse peritoneal macrophages. These data led us to investigate the functional role of the Ang-(1-7)/Mas axis in an in vivo LPS model. In this work, we present evidence that Ang-(1-7) via Mas significantly reduced the LPS-increased production of circulating cytokines, such as IL-6, IL-12, and CXCL-1. This inhibitory effect was mediated by Mas because it was not detectable in Mas-deficient (Mas) mice. Accordingly, IL-6, CXCL-1, and CXCL-2 levels were higher after LPS treatment in the absence of Mas. Mas mice were less resistant to LPS-induced endotoxemia, their survival rate being 50% compared with 95% in wild-type mice. Telemetric analyses showed that Mas mice presented more pronounced LPS-induced hypothermia with a 3°C lower body temperature compared with wild-type mice. Altogether, our findings suggest that Ang-(1-7) and Mas inhibit LPS-induced cytokine production and hypothermia and thereby protect mice from the fatal consequences of endotoxemia.

Cerebroprotective action of angiotensin peptides in stroke.

The goal of the present review is to examine the evidence for beneficial actions of manipulation of the RAS (renin-angiotensin system) in stroke, with particular focus on Ang-(1-7) [angiotensin-(1-7)] and its receptor Mas. The RAS appears to be highly involved in the multifactorial pathophysiology of stroke. Blocking the effects of AngII (angiotensin II) at AT1R (AngII type 1 receptor), through the use of commonly prescribed ACE (angiotensin-converting enzyme) inhibitors or AT1R blockers, has been shown to have therapeutic effects in both ischaemic and haemorrhagic stroke. In contrast with the deleterious actions of over activation of AT1R by AngII, stimulation of AT2Rs (AngII type 2 receptors) in the brain has been demonstrated to elicit beneficial effects in stroke. Likewise, the ACE2/Ang-(1-7)/Mas axis of the RAS has been shown to have therapeutic effects in stroke when activated, countering the effects of the ACE/AngII/AT1R axis. Studies have demonstrated that activating this axis in the brain elicits beneficial cerebral effects in rat models of ischaemic stroke, and we have also demonstrated the cerebroprotective potential of this axis in haemorrhagic stroke using stroke-prone spontaneously hypertensive rats and collagenase-induced striatal haemorrhage. The mechanism of cerebroprotection elicited by ACE2/Ang-(1-7)/Mas activation includes anti-inflammatory effects within the brain parenchyma. The major hurdle to overcome in translating these results to humans is devising strategies to activate the ACE2/Ang-(1-7)/Mas cerebroprotective axis using post-stroke treatments that can be administered non-invasively.