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Renin-Angiotensin System (RAS) is a peptidergic system, canonically known for its role in blood pressure regulation. Furthermore, a non-canonical RAS regulates pathophysiological phenomena, such as inflammation since it consists of two main axes: the pro-inflammatory renin/(pro)renin receptor ((P)RR) axis, and the anti-inflammatory angiotensin-converting enzyme 2 (ACE2)/Angiotensin-(1-7) (Ang-(1-7))/Mas Receptor (MasR) axis. Few phytochemicals have shown to exert angiotensinergic and anti-inflammatory effects through some of these axes; nevertheless, anti-inflammatory drugs, such as phytocannabinoids have not been studied regarding this subject. Among phytocannabinoids, β-Caryophyllene stands out as a dietary phytocannabinoid with antiphlogistic activity that possess a unique sesquiterpenoid structure. Although its cannabinergic effect has been studied, its angiotensinergic effect reminds underexplored. This study aims to explore the angiotensinergic effect of β-Caryophyllene on inflammation and stress at a systemic level. After intranasal Lipopolysaccharide (LPS) installation and oral treatment with β-Caryophyllene, the concentration and activity of key RAS elements in the serum, such as Renin, ACE2 and Ang-(1-7), along with the stress hormone corticosterone and pro/anti-inflammatory cytokines, were measured in mice serum. The results show that β-Caryophyllene treatment modified RAS levels by increasing Renin and Ang-(1-7), alongside the reduction of pro-inflammatory cytokines and corticosterone levels. These results indicate that β-Caryophyllene exhibits angiotensinergic activity in favor of anti-inflammation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Chronic kidney disease is one of the leading causes of morbidity and mortality especially among the aged population. A decline in kidney function with ageing comparable to ageing-related processes in human kidneys has also been described in Sprague-Dawley (SD) rats. The renin-angiotensin-system (RAS) plays a pivotal role in the pathophysiology of cardiovascular and kidney disease and is a successful therapeutic target. The discovery of angiotensin-(1-7) (Ang(1-7)), mainly produced by angiotensin-converting enzyme 2 (ACE2), and its receptor MAS offered a new view on the RAS. This ACE2/Ang(1-7)/MAS axis counteracts most deleterious actions of the RAS in the kidney. In order to evaluate if activation of this axis has a protective effect in ageing-induced kidney disease we generated a transgenic rat model (TGR(SM22hACE2)) overexpressing human ACE2 in vascular smooth muscle cells. These animals showed a specific transgene expression pattern and increased ACE2 activity in the kidney. Telemetric recording of cardiovascular parameters and evaluation of kidney function by histology and urine analysis revealed no alterations in blood pressure regulation and basal kidney function in young transgenic rats when compared to young SD rats. However, with ageing, SD rats developed a decline in kidney function characterized by severe albuminuria which was significantly less pronounced in TGR(SM22hACE2) rats. Concomitantly, we detected lower mRNA expression levels of kidney damage markers in aged transgenic animals. Thus, our results indicate that vascular ACE2-overexpression protects the kidney against ageing-induced decline in kidney function, supporting the kidney-protective role of the ACE2/Ang(1-7)/MAS axis., (Copyright © 2023 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

The renin-angiotensin system (RAS) is a key hormonal system. In recent years, the functional analysis of the novel axis of the RAS (ACE2/Ang-(1-7)/Mas receptor) revealed that its activation can become protective against several pathologies, including cardiovascular diseases. Mas knockout mice (Mas-KO) represent an important tool for new investigations. Indeed, extensive biological research has focused on investigating the functional implications of Mas receptor deletion. However, although the Mas receptor was identified in neonatal cardiomyocytes and also in adult ventricular myocytes, only few reports have explored the Ang-(1-7)/Mas signaling directly in cardiomyocytes to date. This study investigated the implication of Mas receptor knockout to the cytokine profile, energy metabolism, and electrical properties of mice-isolated cardiomyocytes. Here, we demonstrated that Mas-KO mice have modulation in some cytokines, such as G-CSF, IL-6, IL-10, and VEGF in the left ventricle. This model also presents increased mitochondrial number in cardiomyocytes and a reduction in the myocyte diameter. Finally, Mas-KO cardiomyocytes have altered action potential modulation after diazoxide challenge. Such electrical finding was different from the data showed for the TGR(A1-7)3292 (TGR) model, which overexpresses Ang-(1-7) in the plasma by 4.5, used by us as a control. Collectively, our findings exemplify the importance of understanding the ACE2/Ang-(1-7)/Mas pathway in cardiomyocytes and heart tissue. The Mas-KO mice model can be considered an important tool for new RAS investigations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Aims: Rhabdomyolysis (RM) is a critical condition with a high mortality rate, but effective management is still deficient. Till date, there are no studies that have addressed the effect of angiotensin 1-7 in this condition, hence, the rationale of this study was to evaluate the potential protective effect of Angiotensin 1-7 (Ang1-7), on rhabdomyolysis (RM) induced kidney injury in rats and detecting the underlying mechanistic insights., Main Methods: Forty adult male albino rats were divided into groups; the control group, RM group, RM+Ang1-7 group, and RM+Ang1-7+ A779 group. Sera and urine samples were collected for analysis of renal and muscle injury markers. Kidney tissues were taken for estimation of oxidative, inflammatory, and apoptotic markers as well as angiotensin-II (Ang II) and Ang1-7. Renal histology and expression of inducible nitric oxide synthase-1 (iNOS), real-time PCR for angiotensin-converting enzyme-2 (ACE-2), nuclear erythroid factor-2 (Nrf-2), Toll like receptor 4 (TLR-4) and NF-kB in kidney tissues were also measured., Key Findings: Induction of RM caused renal oxidative stress injury, inflammation, apoptosis and marked deterioration in kidney functions as well as reduction of Ang1-7 and raised Angiotensin-II level in kidney tissues. Administration of Ang1-7 to the RM group reversed all the affected parameters which were blocked by A779 administration (Mas receptor blocker)., Significance: We concluded that Ang1-7 could be a potential therapeutic agent that could mitigate RM-induced renal injury. The underlying mechanisms may involve Stimulation of the ACE-2/Ang1-7/MasR axis and modulation of TLR-4/NF-kB/iNOS and Nrf-2/heme‑oxygenase -1 pathways., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Aims: We aimed to investigate whether Saccharomyces boulardii strain might exert renoprotective effects by modulating renal renin angiotensin system, oxidative stress and intestinal microbiota in streptozotocin-diabetic mice., Main Methods: Thirty-six C57BL/6 male mice were divided into four groups: control (C), control + probiotic (CP), diabetes (D), diabetes + probiotic (DP). Diabetes was induced by one intraperitoneal injection of streptozotocin and Saccharomyces boulardii was administered by oral gavage for 8 weeks. Blood glucose, albuminuria and urinary volume were measured. Renal levels of angiotensin peptides (angiotensin I, II and 1-7) and the activities of angiotensin-converting enzyme (ACE) and ACE2 were determined, besides that, renal morphology, serotonin and dopamine levels and also microbiota composition were analyzed., Key Findings: Probiotics significantly increased C-peptide secretion and reduced blood glucose of diabetic animals. Saccharomyces boulardii also improved renal antioxidant defense, restored serotonin and dopamine concentration, and activated the renin-angiotensin system (RAS) vasodilator and antifibrotic axis. The modulation of these markers was associated with a beneficial impact on glomerular structure and renal function of diabetic treated animals. The phenotypic changes induced by Saccharomyces boulardii were also related to modulation of intestinal microbiota, evidenced by the decreased abundance of Proteus and Escherichia-Shigella, considered diabetic nephropathy biomarkers., Significance: Therefore, probiotic administration to streptozotocin-induced diabetic mice improves kidney structure and function in a murine model and might represent a reasonable strategy to counteract nephropathy-associated maladaptive responses in diabetes., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Aims: Angiotensin-converting enzyme (ACE) 2 is the receptor for severe acute respiratory syndrome coronavirus 2 which causes coronavirus disease 2019 (COVID-19). Viral cellular entry requires ACE2 and transmembrane protease serine 2 (TMPRSS2). ACE inhibitors (ACEIs) or angiotensin (Ang) receptor blockers (ARBs) influence ACE2 in animals, though evidence in human lungs is lacking. We investigated ACE2 and TMPRSS2 in type II pneumocytes, the key cells that maintain lung homeostasis, in lung parenchymal of ACEI/ARB-treated subjects compared to untreated control subjects., Main Methods: Ang II and Ang-(1-7) levels and ACE2 and TMPRSS2 protein expression were measured by radioimmunoassay and immunohistochemistry, respectively., Key Findings: We found that the ratio Ang-(1-7)/Ang II, a surrogate marker of ACE2 activity, as well as the amount of ACE2-expressing type II pneumocytes were not different between ACEI/ARB-treated and untreated subjects. ACE2 protein content correlated positively with smoking habit and age. The percentage of TMPRSS2-expressing type II pneumocytes was higher in males than females and in subjects under 60 years of age but it was not different between ACEI/ARB-treated and untreated subjects. However, there was a positive association of TMPRSS2 protein content with age and smoking in ACEI/ARB-treated subjects, with high TMPRSS2 protein levels most evident in ACEI/ARB-treated older adults and smokers., Significance: ACEI/ARB treatment influences human lung TMPRSS2 but not ACE2 protein content and this effect is dependent on age and smoking habit. This finding may help explain the increased susceptibility to COVID-19 seen in smokers and older patients with treated cardiovascular-related pathologies., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Aims: We aimed to determine whether resistance training (RT) regulates renal renin-angiotensin system (RAS) components and inflammatory mediators in diabetic rats., Main Methods: Male Wistar rats (3 months old) were randomly assigned into four groups: non-trained (NT), trained (T), non-trained + diabetes (NTD) and trained +diabetes (TD). Diabetes was induced by streptozotocin (50 mg/kg, Sigma Chemical Co., St. Louis, MO, USA), before RT protocol. Trained rats performed RT protocol on a 110-cm ladder (8 ladder climbs, once/day, 5 days/week, 8 weeks), carrying a load corresponding to 50-80% of maximum carrying capacity. Blood glucose, albuminuria and urinary volume were measured. Renal levels of angiotensin peptides (angiotensin I, II and 1-7), inflammatory markers, and also the activities of angiotensin-converting enzyme (ACE) and ACE2 were determined., Key Findings: Blood glucose and urinary volume were elevated in diabetic animals, and RT decreased albuminuria, renal Ang I and Ang II levels in diabetic rats. RT shifted the balance of renal RAS toward ACE2/Ang 1-7 axis in TD group, and mitigated the high levels of interleukin (IL)-10, IL-1β and cytokine-induced neutrophil chemoattractant 1 (CINC) in the context of diabetes. Strong positive correlations were found between albuminuria and Ang II, IL-10 and IL-1β. On the other hand, intrarenal Ang 1-7 levels were negatively correlated with IL-10 and IL-1β levels., Significance: RT improved kidney function by modulating intrarenal RAS toward ACE2/Ang 1-7 axis and inflammatory cytokines. RT represents a reasonable strategy to improve the renal complications induced by diabetes, counteracting nephropathy-associated maladaptive responses., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Pulmonary fibrosis is a devastating lung disease with multifactorial etiology characterized by alveolar injury, fibroblast proliferation and excessive deposition of extracellular matrix proteins, which progressively results in respiratory failure and death. Accumulating evidence from experimental and clinical studies supports a central role of the renin angiotensin aldosterone system (RAAS) in the pathogenesis and progression of idiopathic pulmonary fibrosis. Angiotensin II (Ang II), a key vasoactive peptide of the RAAS mediates pro-inflammatory and pro-fibrotic effects on the lungs, adversely affecting organ function. Recent years have witnessed seminal discoveries in the field of RAAS. Identification of new enzymes, peptides and receptors has led to the development of several novel concepts. Of particular interest is the establishment of a protective axis of the RAAS comprising of Angiotensin converting enzyme 2 (ACE2), Angiotensin-(1-7) [Ang-(1-7)], and the Mas receptor (the ACE2/Ang-(1-7)/Mas axis), and the discovery of a functional role for the Angiotensin type 2 (AT 2 ) receptor. Herein, we will review our current understanding of the role of RAAS in lung fibrogenesis, provide evidence on the anti-fibrotic actions of the newly recognized RAAS components (the ACE2/Ang-(1-7)/Mas axis and AT 2 receptor), discuss potential strategies and translational efforts to convert this new knowledge into effective therapeutics for PF., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Aims: Exercise training increases circulating and tissue levels of angiotensin-(1-7) [Ang-(1-7)], which was shown to attenuate inflammation and fibrosis in different diseases. Here, we evaluated whether Ang-(1-7)/Mas receptor is involved in the beneficial effects of aerobic training in a chronic model of asthma., Material and Methods: BALB/c mice were subjected to a protocol of asthma induced by ovalbumin sensitization (OVA; 4 i.p. injections) and OVA challenge (3 times/week for 4 weeks). Simultaneously to the challenge period, part of the animals was continuously treated with Mas receptor antagonist (A779, 1 μg/h; for 28 days) and trained in a treadmill (TRE; 60% of the maximal capacity, 1 h/day, 5 days/week during 4 weeks). PGC1-α mRNA expression (qRT-PCR), plasma IgE and lung cytokines (ELISA), inflammatory cells infiltration (enzymatic activity assay) and airway remodeling (by histology) were evaluated., Key Findings: Blocking the Mas receptor with A779 increased IgE and IL-13 levels and prevented the reduction in extracellular matrix deposition in airways in OVA-TRE mice. Mas receptor blockade prevented the reduction of myeloperoxidase activity, as well as, prevented exercise-induced IL-10 increase. These data show that activation of Ang-(1-7)/Mas receptor pathway is involved in the anti-inflammatory and anti-fibrotic effects of aerobic training in an experimental model of chronic asthma., Significance: Our results support exercise training as a non-pharmacological tool to defeat lung remodeling induced by chronic pulmonary inflammation. Further, our result also supports development of new therapy based on Ang-(1-7) or Mas agonists as important tool for asthma treatment in those patients that cannot perform aerobic training., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The article describes the possible pathophysiological origin of COVID-19 and the crucial role of renin-angiotensin system (RAS), providing several "converging" evidence in support of this hypothesis. SARS-CoV-2 has been shown to initially upregulate ACE2 systemic activity (early phase), which can subsequently induce compensatory responses leading to upregulation of both arms of the RAS (late phase) and consequently to critical, advanced and untreatable stages of COVID-19 disease. The main and initial actors of the process are ACE2 and ADAM17 zinc-metalloproteases, which, initially triggered by SARS-CoV-2 spike proteins, work together in increasing circulating Ang 1-7 and Ang 1-9 peptides and downstream (Mas and Angiotensin type 2 receptors) pathways with anti-inflammatory, hypotensive and antithrombotic activities. During the late phase of severe COVID-19, compensatory secretion of renin and ACE enzymes are subsequently upregulated, leading to inflammation, hypertension and thrombosis, which further sustain ACE2 and ADAM17 upregulation. Based on this hypothesis, COVID-19-phase-specific inhibition of different RAS enzymes is proposed as a pharmacological strategy against COVID-19 and vaccine-induced adverse effects. The aim is to prevent the establishment of positive feedback-loops, which can sustain hyperactivity of both arms of the RAS independently of viral trigger and, in some cases, may lead to Long-COVID syndrome., (Copyright © 2021. Published by Elsevier Ltd.)

Nephrotoxicity is a rapid deterioration of kidney function due to exposure to nephrotoxic drugs as gentamicin. Gentamicin increases the generation of reactive oxygen species (ROS) leading to inflammatory responses and nuclear factor-κB (NF-κB) activation. The renal renin-angiotensin system (RAS) is considered a crucial regulator for physiological homeostasis and disease progression through the classic ACE/Ang-II/AT1 axis and its antagonist, ACE2/Ang-(1-7)/Mas axis which exerts an important role in the kidney. The present study evaluates the protective effects of the angiotensin-converting enzyme 2 (ACE2) activator; xanthenone; against experimental nephrotoxicity induced by gentamicin. Rats were divided into 4 groups, normal control, xanthenone (2 mg/kg, s.c), gentamicin (100 mg/kg, i.p. for one week) and xanthenone + gentamicin groups. Blood urea nitrogen (BUN) and serum creatinine levels were measured. The kidney tissues were used for estimating glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), NF-κB, Angiotensin II (AngII), and Ang-(1-7). In addition, histopathological examination and Western blot analysis of ACE2 expression were done. Xanthenone significantly restored serum levels of BUN and creatinine. Xanthenone exerted significant antioxidant effect as revealed by increased GSH content and SOD activity together with reduced MDA content. It exerted anti-inflammatory effect by significant reduction in TNF-α, NF-κB and IL-6 expression compared to gentamicin group. Xanthenone increased Ang-(1-7) and ACE2 expression while significantly decreased Ang-II expression. Histopathologically, xanthenone markedly counteracted gentamicin-induced renal aberrations. Activation of ACE2/Ang-(1-7) by xanthenone produced significant antioxidant and anti-inflammatory effects that counteracted gentamicin-induced nephrotoxicity., (Copyright © 2021. Published by Elsevier Inc.)

Aims: Angiotensin-1-7 [Ang-(1-7)] is an essential peptide of the renin-angiotensin system that promotes benefits modulating effects in different tissues. Similarly, interleukin-10 (IL-10) exhibits an immunomodulatory action on the vasculature. This study aimed to evaluate whether Ang-(1-7) levels attenuates vascular contractile response, mediated by IL-10-pathway (JAK1/STAT3/IL-10)., Main Methods: Aortas from male mice C57BL/6J and knockout for IL-10 (IL-10 -/- ) were incubated with Ang-(1-7) [10 μM] or vehicle, during 5 min, 1 h, 6 h, 12 h, and 24 h. Concentration-response curves to phenylephrine, western blotting, and flow cytometry analysis was performed to evaluate the contractile response, protein expression, and IL-10 levels, respectively., Key Findings: Incubation with Ang-(1-7) produced a time-dependent increase in Janus kinases 1 (JAK1) expression, as well as increased expression and activity of the signal transducer and activator of transcription 3 (STAT3) protein. However, this effect was not observed in knockout animals for IL-10. After 12 h of Ang-(1-7) treatment, arteries from control mice displayed decreased vascular reactivity to phenylephrine, but this effect was not observed in the absence of endogenous IL-10. Additionally, incubation with Ang-(1-7) augments IL-10 levels after 6 h, 12 h, and 24 h of incubation., Significance: These results demonstrated the role of Ang-(1-7) in the IL-10 signaling pathway and its effects in the vascular contractility response. Thus, these findings suggest a new synergic action where Ang-(1-7) and IL-10 converge into a protective mechanism against vascular dysfunction., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Cardiac fibrosis is associated with most of heart diseases, but its molecular mechanism remains unclear. Anoctamin-1 (ANO1), a calcium-activated chloride channels (CaCCs) protein, plays a critical role in various pathophysiological processes. In the current study, we identified ANO1 expression in myocardial infarction (MI) model of rat and verified the role of ANO1 in cardiac fibrosis using transcriptomics combined with RNAi assays. we found that ANO1 expression was increased during the first two weeks, and decreased in the third week after MI. Fluorescence double labeling showed that ANO1 was mainly expressed in cardiac fibroblasts (CFs) and displayed an increased expression in CFs with proliferation tendency. The proliferation and secretion of CFs were markedly inhibited by knockdown of ANO1. RNA-Seq showed that most of the downregulation genes were related to the proliferation of CFs and cardiac fibrosis. After ANO1 knockdown, the expressions of angiotensin II type 1 receptor (AT1R) and cell nuclear proliferation antigen were markedly reduced, and the phosphorylation levels of MEK and ERK1/2 was decreased significantly, indicating that ANO1 regulate cardiac fibrosis through ATIR-mediated MAPK signaling pathway. These findings would be useful for the development of therapeutic strategies targeting ANO1 to treat and prevent cardiac fibrosis., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death globally. Cumulative evidence has implicated renin-angiotensin system (RAS) in the pathogenesis of COPD. This study aimed to investigate potential protective effects of angiotensin II type-2 receptor (AT2R) activation in cigarette smoke (CS)-induced COPD models. Compound 21 (C21), a selective and potent non-peptide small molecule AT2R agonist, was evaluated for anti-inflammatory, anti-oxidative and anti-remodeling activities in a two-week (acute) and an eight-week (chronic) CS-induced COPD models. C21 inhibited CS-induced increases in macrophage and neutrophil counts, pro-inflammatory cytokines and oxidative damage markers in bronchoalveolar lavage (BAL) fluid, and TGF-β1 in lung tissues, from COPD models. C21 restored phosphatase activities and reduced phospho-p38 MAPK, phospho-ERK and p65 subunit of NF-κB levels in CS-exposed lung tissues. C21 also suppressed CS-induced increases in α-Sma, Mmp9, Mmp12 and hydroxyproline levels in lung tissues, and neutrophil elastase activity in BAL fluid. C21 modulated RAS in CS-exposed lungs by downregulating Ang II but upregulating Ang-(1-7) and Mas receptor levels. C21 prevented CS-induced emphysema and improved lung functions in chronic COPD model. We report here for the first time the protective effects of AT2R agonist C21 against CS-induced COPD, and provide strong evidence for further development of AT2R agonist for the treatment of COPD., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Previous studies have suggested that pyroptosis may play an important role in LPS-induced acute lung injury (ALI), but the exact mechanism of pyroptosis induction and the role of Angiotensin-converting enzyme 2 (ACE2)/Ang (1-7)/Mas axis in pyroptosis has not been investigated yet. The present study aimed to establish a mice model of ALI and clarify the involvement of pyroptosis and ACE2/Ang (1-7)/Mas axis. The results showed that LPS induced pyroptosis in lung, demonstrated by increased expression of Gasdermin D (GSDMD), cleaved GSDMD, IL-1β, and Caspase-1. Treatment of Ang (1-7) significantly reduced the severity of ALI and pyroptosis, while AngII significantly exaggerated them. Furthermore, ACE2 activator resorcinolnaphthalein (RES) significantly reduced the severity of ALI and pyroptosis, but ACE2 inhibitor MLN-4760 and Mas inhibitor A779 significantly exaggerated them, suggesting that the ACE2/Ang (1-7)/Mas axis was involved in the pyroptosis in LPS-induced ALI. In addition, Ang (1-7) and RES significantly decreased the levels of NLRP3, which were increased by AngII and A779. NLRP3 knockout significantly reduced the severity of ALI and pyroptosis. In conclusion, pyroptosis played an important role in ALI induced by LPS. The ACE2/Ang (1-7)/Mas axis negatively regulated the pyroptosis and protected mice against LPS-induced ALI through NLRP3 inhibition. The present study expanded our understating of the role of ACE2/Ang (1-7)/Mas axis in ALI by providing a novel explanation that it may regulate the pyroptosis in ALI., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Exposure to ambient fine particulate matter (PM 2.5 ) is associated with various adverse health outcomes. Although several mechanisms have been proposed including oxidative stress and inflammatory responses, the exact mechanism is still unknown. Few studies have investigated the mechanism linking PM 2.5 and blood pressure (BP). In this study, we measured urinary metabolites and BP -related renin-angiotensin-aldosterone system (RAAS) to investigate the associations between ambient PM 2.5 exposure and BP in healthy C57BL/6 mice., Methods: The C57BL/6 mice were exposed to ambient concentrated PM 2.5 or filtered air (FA) for 16 weeks. Systolic BP and diastolic BP were measured by noninvasive BP system. The urine metabolites were quantified using the untargeted metabolomics approach. The expression of RAAS-related proteins angiotensin-converting enzyme (ACE)2, angiotensin (Ang) II, Ang (1-7) and aldosterone (ALD) were measured using Western blot and ELISA kits., Results: The metabolomics analysis demonstrated that PM 2.5 exposure induced significant changes of some metabolites in urine, including stress hormones, amino acids, fatty acids, and lipids. Furthermore, there was an elevation of BP, increase of serous Ang II and ALD, along with the decrease of ACE2 and Ang (1-7) in kidney in the PM 2.5 -exposed mice compared with FA-exposed mice., Conclusions: The results demonstrated that PM 2.5 exposure-induced BP elevation might be associated with RAAS activation. Meanwhile, PM 2.5 exposure-induced changes of stress hormone and lipid metabolism might mediate the activation of RAAS. The results suggested that the systemic stress hormone and lipid metabolism was associated with the development of hypertension., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Coronavirus disease 2019 has markedly varied clinical presentations, with most patients being asymptomatic or having mild symptoms. However, severe acute respiratory disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is common and associated with mortality in patients who require hospitalization. The etiology of susceptibility to severe lung injury remains unclear. Angiotensin II, converted by angiotensin-converting enzyme (ACE) from angiotensin I and metabolized by ACE 2 (ACE2), plays a pivotal role in the pathogenesis of lung injury. ACE2 is identified as an essential receptor for SARS-CoV-2 to enter the cell. The binding of ACE2 and SARS-CoV-2 leads to the exhaustion and down-regulation of ACE2. The interaction and imbalance between ACE and ACE2 result in an unopposed angiotensin II. Considering that the ACE insertion (I)/deletion (D) gene polymorphism contributes to the ACE level variability in general population, in which mean ACE level in DD carriers is approximately twice that in II carriers, we propose a hypothesis of genetic predisposition to severe lung injury in patients with coronavirus disease 2019. It is plausible that the ACE inhibitors and ACE receptor blockers may have the potential to prevent and to treat the acute lung injury after SARS-CoV-2 infection, especially for those with the ACE genotype associated with high ACE level., (Copyright © 2020 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Although renin-angiotensin system (RAS) imbalance is manifested in cardiomyopathies with different etiologies, the impact of RAS effectors on Chagas cardiomyopathy and skeletal myositis is poorly understood. Given that diminazene aceturate (DMZ) shares trypanocidal, angiotensin-converting enzyme 2 (ACE2) and angiotensin-(1-7) stimulatory effects, we investigated the impact of DMZ on cardiomyocytes infection in vitro, renin-angiotensin system, Chagas cardiomyopathy and skeletal myositis in vivo. Cardiomyocytes and T. cruzi were used to evaluate DMZ toxicity in vitro. The impact of 20-days DMZ treatment (1 mg/kg) was also investigated in uninfected and T. cruzi-infected mice as follows: control uninfected and untreated, uninfected treated with DMZ, infected untreated and infected treated with DMZ. DMZ had low toxicity on cardiomyocytes, induced dose-dependent antiparasitic activity on T. cruzi trypomastigotes, and reduced parasite load but not infection rates in cardiomyocytes. DMZ increased ACE2 activity and angiotensin-(1-7) plasma levels but exerted no interference on angiotensin-converting enzyme (ACE) activity, ACE, ACE2 and angiotensin II levels in uninfected and infected mice. DMZ treatment also reduced IFN-γ and IL-2 circulating levels but was ineffective in attenuating parasitemia, MCP-1, IL-10, anti-T. cruzi IgG, nitrite/nitrate and malondialdehyde production, myocarditis and skeletal myositis compared to infected untreated animals. As the antiparasitic effect of DMZ in vitro did not manifest in vivo, this drug exhibited limited relevance to the treatment of Chagas disease. Although DMZ is effective in upregulating angiotensin-(1-7) levels, this molecule does not act as a potent modulator of T. cruzi infection, which can establish heart and skeletal muscle parasitism, lipid oxidation and inflammatory damage, even in the presence of high concentrations of this RAS effector., Competing Interests: Declaration of competing interest None to declare., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Aim: This work aims to explore the role of diminazene aceturate (DIZE) in the enhancement of angiotensin-converting enzyme-2 (ACE2) to prevent the inflammatory and fibrotic response induced by γ-irradiation through activating the protective axis ACE2/angiotensin (1-7)/Mas receptor (ACE2/Ang(1-7)/Mas)., Methods: Male rats were injected i.p. with 15 mg/kg DIZE daily for 7 days pre and post-irradiation, where 7.5 Gy of γ-radiation as a single dose was used., Key Findings: Gamma radiation induced a significant elevation of renal biochemical parameters: urea, creatinine and blood urea nitrogen (BUN) in serum with a significant disturbance in oxidative stress markers: elevation in malondialdehyde (MDA) associated with a depletion of reduced glutathione (GSH) and superoxide dismutase (SOD). Beside elevation in the level of angiotensin II (AngII) that lead to remarkably increases in the levels of the renal inflammatory mediators: tumor necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB) and interleukin-1β (IL-1β) as well as renal fibrogenic markers: transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), and hydroxyproline content in the renal tissues. DIZE caused marked expansion in the expression of ACE2 consequently decreased the expression of AngII and increased the expression of Ang(1-7) which through its Mas receptor ameliorates the biochemical and histopathological damage induced by radiation., Significance: DIZE-induced stimulation of ACE2 subdues the renal deleterious consequences induced by γ-radiation via activation of ACE2/Ang(1-7)/Mas axis in rats., Competing Interests: Declaration of competing interest Authors report no declaration of interest. This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: This study aimed to investigate OIP5-AS1 effects on microangiopathy in diabetic mouse., Methods: The expression levels of OIP5-AS1, miR-200b, and ACE2 expression were measured by RT-qPCR. Western blot was conducted to detect The ACE2 and Ang-(1-7) expression. Luciferase reporter assays were used to identify the interaction between miR-200b and OIP5-AS1 or ACE2. Morris water maze test was performed for detecting cognitive function., Results: Our results indicated that diabetic mice exhibited much lower OIP5-AS1 expression in the hippocampus than normal mice. Diabetic mice of OIP5-AS1 KO group showed remarkably lower OIP5-AS1 expression in the hippocampus, longer escape latency and lower percentage of CD31+ cells in the hippocampusthan those of WT group. OIP5-AS1 knockdown directly up-regulated miR-200b expression and ACE2 was directly inhibited by miR-200b. Relative to normal mice, diabetic mice had markedly higher miR-200b expression and lower ACE2 expression in the hippocampus. Diabetic mice of OIP5-AS1 KO group were with obviously higher miR-200b expression and lower ACE2 expression in the hippocampus than those of WT group. Compared with diabetic mice of OIP5-AS1 KO group, those of WT group, OIP5-AS1 KO + miR-200b inhibitor group and OIP5-AS1 KO + ACE2 group had obviously shorter escape latency and higher percentage of CD31 + cells and more caspase-3 protein expression in the hippocampus., Conclusions: OIP5-AS1 attenuated microangiopathy in diabetic mouse by regulating miR-200b/ACE2., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Activation of the intracrine renin angiotensin systems (RAS) is increasingly recognized as contributing to human pathologies, yet non-canonical renin-independent mechanisms for angiotensin II (Ang II) biosynthesis remain controversial. Direct Ang II generation from angiotensin-(1-12) [Ang-(1-12)] by chymase is an essential intracrine source for regulation of cardiac function. Using a transgenic rat model that overexpresses the human angiotensinogen gene [TGR(hAGT)L1623] and displays increased cardiac Ang II levels, this study aimed to provide evidence for intracrine activation of L-type calcium currents (I Ca-L ) mediated by the Ang-(1-12)/chymase axis., Methods and Results: On patch clamp, I Ca-L density was significantly higher in TGR(hAGT)L1623 (-6.4 ± 0.3 pA/pF) compared to Sprague Dawley (SD) cardiomyocytes (-4.8, ± 0.5 pA/pF). Intracellular administration of Ang II and Ang-(1-12) elicited a I Ca-L increase in both SD and TGR(hAGT)L1623 cardiomyocytes, albeit blunted in transgenic cells. I Ca-L activation by intracellular Ang II and Ang-(1-12) was abolished by the specific Ang II type 1 receptor blocker E-3174. Co-administration of a chymase inhibitor prevented activation of I Ca-L by Ang-(1-12). Confocal micrographs revealed abundant chymase (mast cell protease 5) immunoreactive protein in SD and TGR(hAGT)L1623 cardiomyocytes., Conclusions: Our data demonstrate the existence in cardiomyocytes of a calcium channel modulatory activity responsive to Ang II generated by the Ang-(1-12)/chymase axis that signals via intracellular receptors. Chronically elevated Ang II in TGR(hAGT)L1623 hearts leading to increased intracellular calcium through I Ca-L suggests that activation of this Ang-(1-12)/chymase-governed cardiac intracrine RAS may contribute to the pathological phenotypes observed in the humanized model of chronic hypertension and cardiac hypertrophy., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective: Previous studies demonstrated that deficiency of angiotensin-converting enzyme 2 (ACE2) augmented angiotensin II (AngII)-induced atherosclerosis and abdominal aortic aneurysm (AAA) formation in hypercholesterolemic mice. Effects of ACE2 deficiency could arise from increased concentrations of its substrate, AngII, or decreased concentrations of its product, angiotensin-(1-7) [Ang-(1-7)]. Infusion of Ang-(1-7), a Mas receptor (MasR) ligand, to hypercholesterolemic male mice reduced AngII-induced atherosclerosis, suggesting a protective role of the Ang-(1-7)/MasR axis. However, it is unclear whether endogenous Ang-(1-7) acts at MasR to influence AngII-induced vascular diseases. The purpose of this study was to define the role of MasR deficiency in AngII-induced atherosclerosis and AAA formation and severity in hypercholesterolemic male mice., Methods: MasR +/+ and MasR -/- male mice on a low-density lipoprotein receptor-deficient (Ldlr -/- ) or apolipoprotein E-deficient (Apoe -/- ) background were infused with AngII at either 600 or 1000 ng/kg/min by osmotic minipump for 28 days. Atherosclerosis was quantified at study end point as percentage lesion surface area of the aortic arch in Ldlr -/- mice. Abdominal aortic internal diameters were quantified by ultrasound, and maximal external AAA diameters were quantified at study end point. Blood pressure was quantified by radiotelemetry and a tail cuff-based technique. Serum cholesterol concentrations and vascular tissue characterization were examined at study end point., Results: MasR deficiency did not influence body weight, systolic blood pressure at baseline and during AngII infusion, or serum cholesterol concentrations in either Apoe -/- or Ldlr -/- mice. MasR deficiency increased AngII-induced atherosclerosis in aortic arches of Ldlr -/- mice (P < .05), associated with increased oxidative stress and apoptosis in aortic root sections (P < .05). MasR deficiency also augmented internal and external AAA diameters and increased aortic ruptures of both Ldlr -/- and Apoe -/- mice (P < .05). These effects were associated with increased elastin breaks and T-lymphocyte and macrophage accumulation into abdominal aortas of AngII-infused MasR-deficient mice (P < .05)., Conclusions: These results demonstrate that MasR deficiency augmented AngII-induced atherosclerosis and AAA rupture through mechanisms involving increased oxidative stress, inflammation, and apoptosis, suggesting that MasR activation may provide therapeutic efficacy against vascular diseases., (Copyright © 2019 Society for Vascular Surgery. All rights reserved.)

Angiotensin processing peptidases (carboxypeptidase A (CPA) and chymase) are stored in cardiac mast cell (MC) secretory granules in large quantity and are co-released into the extracellular environment after activation/degranulation. In the human heart, chymase is primarily responsible for angiotensin II (Ang II) generation from the alternate substrate angiotensin-(1-12) (Ang-(1-12)). We investigated the individual and combined hydrolytic specificity of CPA and chymase enzymes (1:1 and 1:⅓ ratio) in the processing of the human Ang-(1-12) (hAng-(1-12)) substrate. To determine the K m and V max , the CPA and recombinant human chymase (rhChymase) enzymes were incubated with increasing concentrations of hAng-(1-12) substrate (0-300 μM). We found that CPA alone sequentially metabolized hAng-(1-12) substrate into angiotensin-(1-9) (Ang-(1-9), 53%), Ang II (22%) and angiotensin-(1-7) (Ang-(1-7), 11%) during a 15 min incubation. In the presence of rhChymase alone, 125 I-hAng-(1-12) was directly metabolized into Ang II (89%) and no further hydrolysis of Ang II was detected. In the presence of both CPA + rhChymase enzymes (1:1 or 1:⅓ ratio), the amount of Ang II formation from 125 I-hAng-(1-12) within a 5 min incubation period were 68% or 65%, respectively. In the presence of both (CPA + rhChymase), small amounts of Ang-(1-9) and Ang-(1-7) were generated from 125 I-hAng-(1-12). The K m and V max values were 150 ± 5 μM and 384 ± 23 nM/min/mg of CPA and 40 ± 9 μM and 116 ± 20 nM/min/mg of rhChymase. The catalytic efficiency (V max /K m ratio) was higher for rhChymase/hAng-(1-12) compared to CPA/hAng-(1-12). Compared to CPA, chymase has a much higher affinity to hydrolyze the hAng-(1-12) substrate directly into Ang II. In addition, Ang II and Ang-(1-7) are the end products of chymase and CPA, respectively. Overall, our findings suggest that the Ang II generation from hAng-(1-12) is primarily mediated by chymase rather than CPA., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Aims: Acute respiratory distress syndrome (ARDS), one of the serious form of acute lung injury (ALI), is the primary cause of death in patients with ALI. Sini decoction (SND) is a widely used Traditional Chinese Medicine (TCM). However, the application of SND in ALI is rarely reported. Previous studies have found that renin-angiotensin-aldosterone system (RAAS) played vital and bidirectional roles in ALI. Therefore, the aim of the present study was to investigate protective effect of SND on ALI model induced by E. coli, as well as to further explore relations between RAAS and SND., Materials and Methods: The ALI model was evaluated by morphological observations and biochemical assays. The expression levels of angiotensin converting enzyme (ACE), Angiotensin II type 1 receptor (AT1R) and angiotensin converting enzyme 2 (ACE2) were examined by Western blotting. The expression levels of angiotensinII (AngII) and angiotensin-(1-7) (Ang-(1-7)) were measured through ELISA. MasR, IL-6, IL-1β and TNFα were all measured using qRT-PCR., Key Findings: SND significantly ameliorated E. coli-induced ALI, including reducing inflammatory factors in lung tissue and the activity of MPO in serum. Furthermore, SND could obviously decrease the expression of ACE, AngII and AT1R, which were induced by E. coli. On the other hand, SND could markedly activate ACE2-Ang-(1-7)-Mas pathway., Significance: In this paper, we demonstrated that SND alleviates E. coli induced acute lung injury in mice via equilibrating ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The ACE2/Ang1-7/MAS axis was involved in the cell proliferation, migration and apoptosis of many types of reproductive tissues. The research was conducted on prostate epithelial cells, immortalized by Simian Virus 40. We examined the influence of Ang 1-7 on biological properties of PNT1A cells after 24- or 48-h treatment. The employed selective antagonists of angiotensin receptors allowed evaluation of the receptor mediating Ang1-7 action. Our data clearly indicate that Ang1-7 can decrease cell proliferation and epithelial-to-mesenchymal transition of PNT1A cells via inactivation of PI3K axis and modulation of expression of the NF-kB gene family. Furthermore, it counteracts oxidant stress and inflammation in prostate cells by inhibition of VEGF expression and MMPs activation as well as by modulating the level of ERα and ERβ. On the other hand, this heptapeptide can promote cell survival by alteration of expression of anti- and pro-apoptotic members as well as compensatory up-regulation of AR expression. Summary, the results confirm the existence of a complicated dependence networks between the various elements of the local RAS and steroid hormone receptor pathways in prostate gland. Furthermore, shows the chances of using ACE2/Ang1-7/MAS pathway as a novel therapeutic target in prevention and treatment of prostate diseases., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Aims: HIIT (high-intensity interval training) has the potential to reduce cardiometabolic risk factors, but the effects on cardiac remodeling and local RAS (renin-angiotensin system) in mice fed high-fat or high-fructose diets still need to be fully addressed., Main Methods: Sixty male C57BL/6 mice (12weeks old) were randomly divided into three groups, control (C), High-fat (HF), or High-fructose diet (HRU) and were monitored for eight weeks before being submitted to the HIIT. Each group was randomly assigned to 2 subgroups, one subgroup was started on a 12-week HIIT protocol (T=trained group), while the other subgroup remained non-exercised (NT=not-trained group)., Key Findings: HIIT reduced BM and systolic blood pressure in high-fat groups, while enhanced insulin sensitivity after high-fat or high-fructose intake. Moreover, HIIT reduced left ventricular hypertrophy in HF-T and HFRU-T. Notably, HIIT modulated key factors in the local left ventricular renin-angiotensin-system (RAS): reduced protein expression of renin, ACE (Angiotensin-converting enzyme), and (Angiotensin type 2 receptor) AT2R in HF-T and HFRU-T groups but reduced (Angiotensin type 1 receptor) AT1R protein expression only in the high-fat trained group. HIIT modulated ACE2/Ang (1-7)/Mas receptor axis. ACE2 mRNA gene expression was enhanced in HF-T and HFRU-T groups, complying with elevated Mas (Mas proto-oncogene, G protein-coupled receptor) receptor mRNA gene expression after HIIT., Significance: This study shows the effectiveness of HIIT sessions in producing improvements in insulin sensitivity and mitigating LV hypertrophy, though hypertension was controlled only in the high-fat-fed submitted to HIIT protocol. Local RAS system in the heart mediates these findings and receptor MAS seems to play a pivotal role when it comes to the amelioration of cardiac structural and functional remodeling due to HIIT., (Copyright © 2017 Elsevier Inc. All rights reserved.)

We have previously demonstrated that the intrathecal (i.t.) administration of angiotensin (Ang) II into mice produces a nociceptive behaviour consisting of scratching, biting and licking accompanied by the phosphorylation of p38 MAPK in the spinal cord, which was mediated through AT1 receptors. Both the p38 MAPK phosphorylation and subsequent nociceptive behaviour were attenuated by the i.t. co-administration of Ang (1-7), an N-terminal fragment of Ang II, that acted via Mas receptors. On the other hand, a C-terminal fragment of Ang II, namely Ang III, was also shown to induce a nociceptive behaviour by acting upon AT1 receptors on spinal astrocytes and neurons, and was found to be more potent than Ang II. However, the inhibitory effect of Ang (1-7) on the Ang III-induced nociceptive behaviour remains unclear. Thus, here we examined whether Ang (1-7) can attenuate the Ang III-induced nociceptive behaviour and activation of spinal p38 MAPK. The i.t. administration of Ang (1-7) (1-100fmol) dose-dependently attenuated the Ang III (1pmol)-induced nociceptive behaviour in mice. Moreover, the inhibitory effect of Ang (1-7) at a dose of 100fmol was prevented by A779 (30fmol), a Mas receptor antagonist. Western blot analysis showed that the phosphorylation of p38 MAPK induced by the i.t. administration of Ang III (1pmol) was also attenuated by Ang (1-7) (100fmol), and this inhibition was prevented by A779 (30fmol). Furthermore, we showed that in the lumbar superficial dorsal horn, Mas receptors are expressed in neurons and microglia but absent from astrocytes. Together, these results suggest that the i.t. administration of Ang (1-7) attenuates the nociceptive behaviour and accompanying p38 MAPK phosphorylation induced by Ang III, and that this effect is likely mediated through Mas receptors on spinal neurons., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Blockers of the renin-angiotensin system are effective in the treatment of experimental and clinical diabetic nephropathy. An approach different from blocking the formation or action of angiotensin II (1-8) that could also be effective involves fostering its degradation. Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase that cleaves angiotensin II (1-8) to form angiotensin (1-7). Therefore, we examined the renal effects of murine recombinant ACE2 in mice with streptozotocin-induced diabetic nephropathy as well as that of amplification of circulating ACE2 using minicircle DNA delivery prior to induction of experimental diabetes. This delivery resulted in a long-term sustained and profound increase in serum ACE2 activity and enhanced ability to metabolize an acute angiotensin II (1-8) load. In mice with streptozotocin-induced diabetes pretreated with minicircle ACE2, ACE2 protein in plasma increased markedly and this was associated with a more than 100-fold increase in serum ACE2 activity. However, minicircle ACE2 did not result in changes in urinary ACE2 activity as compared to untreated diabetic mice. In both diabetic groups, glomerular filtration rate increased significantly and to the same extent as compared to non-diabetic controls. Albuminuria, glomerular mesangial expansion, glomerular cellularity, and glomerular size were all increased to a similar extent in minicircle ACE2-treated and untreated diabetic mice, as compared to non-diabetic controls. Recombinant mouse ACE2 given for 4 weeks by intraperitoneal daily injections in mice with streptozotocin-induced diabetic nephropathy also failed to improve albuminuria or kidney pathology. Thus, a profound augmentation of ACE2 confined to the circulation failed to ameliorate the glomerular lesions and hyperfiltration characteristic of early diabetic nephropathy. These findings emphasize the importance of targeting the kidney rather than the circulatory renin angiotensin system to combat diabetic nephropathy., (Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

The octa-peptide angiotensin II (Ang II, (H 2 NAspArgValTyrIleHisProPheCOOH)) is one of the key player on blood pressure regulation in mammals. Predominantly binding to the Angiotensin type 1 and 2 receptors, the hormone is one of several peptide ligands binding to G protein coupled receptors (GPCR). The active hormone derives from a high molecular weight precursor sequentially cleaved by the proteases renin and the angiotensin converting enzyme (ACE). The chemical nature of the amino acid sequence has an impact on the behavior in the proximity of membranes, demonstrated using different membrane model systems and biophysical methods. Applying electrochemical impedance spectroscopy and small angle X-ray scattering a detailed view on the adhesion of the peptide with model membrane surfaces was performed. The role of specific amino acids involved in the interaction with the phospholipid head group were investigated and, studying a truncated version of Ang II, Ang (1-7), the key role of the C-terminal phenylalanine was proven. Truncation of the C-terminal amino acid abolishes the binding of the peptide to the membrane surface. A shift in pH, altering the protonation state of the central histidine residue impairs the adhesion of Ang II., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We showed previously that rat angiotensin-(1-12) [Ang-(1-12)] is metabolized by chymase and angiotensin converting enzyme (ACE) to generate Angiotensin II (Ang II). Here, we investigated the affinity of cardiac chymase and ACE enzymes for Ang-(1-12) and Angiotensin I (Ang I) substrates. Native plasma membranes (PMs) isolated from heart and lung tissues of adult spontaneously hypertensive rats (SHR) were incubated with radiolabeled (125)I-Ang-(1-12) or (125)I-Ang I, in the absence or presence of a chymase or ACE inhibitor (chymostatin and lisinopril, respectively). Products were quantitated by HPLC connected to an in-line flow-through gamma detector. The rate of (125)I-Ang II formation from (125)I-Ang-(1-12) by chymase was significantly higher (heart: 7.0 ± 0.6 fmol/min/mg; lung: 33 ± 1.2 fmol/min/mg, P < 0.001) when compared to (125)I-Ang I substrate (heart: 0.8 ± 0.1 fmol/min/mg; lung: 2.1 ± 0.1 fmol/min/mg). Substrate affinity of (125)I-Ang-(1-12) for rat cardiac chymase was also confirmed using excess unlabeled Ang-(1-12) or Ang I (0-250 μM). The rate of (125)I-Ang II formation was significantly lower using unlabeled Ang-(1-12) compared to unlabeled Ang I substrate. Kinetic data showed that rat chymase has a lower Km (64 ± 6.3 μM vs 142 ± 17 μM), higher Vmax (13.2 ± 1.3 μM/min/mg vs 1.9 ± 0.2 μM/min/mg) and more than 15-fold higher catalytic efficiency (ratio of Vmax/Km) for Ang-(1-12) compared to Ang I substrate, respectively. We also investigated ACE mediated hydrolysis of (125)I-Ang-(1-12) and (125)I-Ang I in solubilized membrane fractions of the SHR heart and lung. Interestingly, no significant difference in (125)I-Ang II formation by ACE was detected using either substrate, (125)I-Ang-(1-12) or (125)I-Ang I, both in the heart (1.8 ± 0.2 fmol/min/mg and 1.8 ± 0.3 fmol/min/mg, respectively) and in the lungs (239 ± 25 fmol/min/mg and 248 ± 34 fmol/min/mg, respectively). Compared to chymase, ACE-mediated Ang-(1-12) metabolism in the heart was several fold lower. Overall our findings suggest that Ang-(1-12), not Ang I, is the better substrate for Ang II formation by chymase in adult rats. In addition, this confirms our previous observation that chymase (rather than ACE) is the main hydrolyzing enzyme responsible for Ang II generation from Ang-(1-12) in the adult rat heart., Competing Interests: All authors have no potential conflicts of interest relevant to this article. Disclosure No potential conflicts of interest relevant to this article., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The Renin Angiotensin System (RAS) is a pivotal physiological regulator of heart and kidney homeostasis, but also plays an important role in the pathophysiology of heart and kidney diseases. Recently, new components of the RAS have been discovered, including angiotensin converting enzyme 2 (ACE2), Angiotensin(Ang)-(1-7), Mas receptor, Ang-(1-9) and Alamandine. These new components of RAS are formed by the hydrolysis of Ang I and Ang II and, in general, counteract the effects of Ang II. In experimental models of heart and renal diseases, Ang-(1-7), Ang-(1-9) and Alamandine produced vasodilation, inhibition of cell growth, anti-thrombotic, anti-inflammatory and anti-fibrotic effects. Recent pharmacological strategies have been proposed to potentiate the effects or to enhance the formation of Ang-(1-7) and Ang-(1-9), including ACE2 activators, Ang-(1-7) in hydroxypropyl β-cyclodextrin, cyclized form of Ang-(1-7) and nonpeptide synthetic Mas receptor agonists. Here, we review the role and effects of ACE2, ACE2 activators, Ang-(1-7) and synthetic Mas receptor agonists in the control of inflammation and fibrosis in cardiovascular and renal diseases and as counter-regulators of the ACE-Ang II-AT1 axis. We briefly comment on the therapeutic potential of the novel members of RAS, Ang-(1-9) and alamandine, and the interactions between classical RAS inhibitors and new players in heart and kidney diseases., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Emotional stress is now considered a risk factor for several diseases including cardiac arrhythmias and hypertension. It is well known that the activation of neuroendocrine and autonomic mechanisms features the response to emotional stress. However, its link to cardiovascular diseases and the regulatory mechanisms involved remain to be further comprehended. The renin-angiotensin system (RAS) plays an important role in homeostasis on all body systems. Specifically in the brain, the RAS regulates a number of physiological aspects. Recent data indicate that the activation of angiotensin-converting enzyme/angiotensin II/AT1 receptor axis facilitates the emotional stress responses. On the other hand, growing evidence indicates that its counterregulatory axis, the angiotensin-converting enzyme 2 (ACE2)/(Ang)iotensin-(1-7)/Mas axis, reduces anxiety and attenuates the physiological responses to emotional stress. The present review focuses on angiotensin-(1-7)/Mas axis as a promising target to attenuate the physiological response to emotional stress reducing the risk of cardiovascular diseases., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The study aimed to identify proteins regulated by the cardiovascular protective peptide angiotensin-(1-7) and to determine potential intracellular signaling cascades. Human endothelial cells were stimulated with Ang-(1-7) for 1 h, 3 h, 6 h, and 9 h. Peptide effects on intracellular signaling were assessed via antibody microarray, containing antibodies against 725 proteins. Bioinformatics software was used to identify affected intracellular signaling pathways. Microarray data was verified exemplarily by Western blot, Real-Time RT-PCR, and immunohistochemical studies. The microarray identified 110 regulated proteins after 1 h, 119 after 3 h, 31 after 6 h, and 86 after 9 h Ang-(1-7) stimulation. Regulated proteins were associated with high significance to several metabolic pathways like “Molecular Mechanism of Cancer” and “p53 signaling” in a time dependent manner. Exemplarily, Western blots for the E3-type small ubiquitin-like modifier ligase PIAS2 confirmed the microarray data and displayed a decrease by more than 50% after Ang-(1-7) stimulation at 1 h and 3 h without affecting its mRNA. Immunohistochemical studies with PIAS2 in human endothelial cells showed a decrease in cytoplasmic PIAS2 after Ang-(1-7) treatment. The Ang-(1-7) mediated decrease of PIAS2 was reproduced in other endothelial cell types. The results suggest that angiotensin-(1-7) plays a role in metabolic pathways related to cell death and cell survival in human endothelial cells.

Angiotensin II (Ang II) has been shown to activate multiple downstream pathways resulting in endothelial dysfunction and oxidative stress. Baicalin, a natural flavone, exerts anti-oxidant and anti-apoptotic effects in cardiovascular diseases. In the present study, we hypothesized that baicalin has beneficial effects in Ang II-induced endothelial cells injury. Here, we shown that baicalin improved endothelial fuction impaired by Ang II through promoting endothelial-dependent vasodilation and suppressing the apoptosis of HUVECs in which baicalin decreased the expression of bax and cleaved caspase-3, and increased bcl-2 expression. Additionally, baicalin significantly conversed Ang II to angiotensin-1-7 [Ang-(1-7)] by activating angiotensin-converting enzyme 2 (ACE2) and Mas receptor mRNA expression and protein expression. Moreover, treatment with baicalin significantly reduced cell oxidative damage induced by Ang II through MDA/ROS decrease and NO/T-AOC increase. This antioxidant capacity was related to the increases of PI3K, phosphor-AKT (Ser-473) and phosphor-eNOS (Ser-1177). In conclusion, our results implicate that baicalin could protect endothelial cells from Ang II-induced endothelial dysfunction and oxidative stress via modulating the expression of bax, bcl-2 and cleaved caspase-3, activating ACE2/Ang-(1-7)/Mas axis and up-regulating PI3K/AKT/eNOS pathway., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background and Objective: We recently found that exogenous angiotensin-(1-7) [Ang-(1-7)] inhibits Angiotensin II (Ang-II)-induced atherosclerotic lesion formation and enhances plaque stability. Our objective was to evaluate the role of endogenous activated Ang-(1-7) during atherosclerosis., Methods and Results: In mice, the effects of endogenous Ang-(1-7) on atherogenesis in early stage and plaque stability in late stage were observed in ApoE knockout (ApoE-/-) mice fed with a high fat diet. Blockage of endogenous Ang-(1-7) with A779, an Ang-(1-7) antagonist, did not increase early plaque lesion formation, however, it remarkably enhanced contents of lipids and macrophages and decreased contents of vascular smooth muscle cells (VSMCs) and collagens in late lesions. The expressions of proinflammatory cytokines, and the expressions and activities of matrix metalloproteinases were significantly elevated in A779-treated group than those in vehicle-treated group in late lesions. Exogenous Ang-(1-7) treatment attenuated early atherosclerotic plaque formation and enhanced late plaques stability in this model. The contents of Ang-II and Ang-(1-7) and activity of ACE2 in late atherosclerotic plaques were higher than those of early atherosclerotic lesions., Conclusion: Endogenous activated Ang-(1-7) enhanced late atherosclerotic plaques stability but did not affect early atherosclerotic plaque formation. Therapies to elevate endogenous Ang-(1-7) may be a potentially effective approach to attenuate atherosclerotic plaques vulnerability., (Copyright © 2015. Published by Elsevier Ireland Ltd.)

Somatic angiotensin-I converting enzyme (sACE) is a broadly distributed peptidase which plays a role in blood pressure and electrolyte homeostasis by the conversion of angiotensin I into angiotensin II. N-domain isoforms (nACE) with 65 and 90 kDa have been described in body fluids, tissues and mesangial cells (MC), and a 90 kDa nACE has been described only in spontaneously hypertensive rats. The aim of this study was to investigate the existence of proteolytic enzymes that may act in the hydrolysis of sACE generating nACEs in MC. After the confirmation of the presence of ACE sheddases in Immortalized MC (IMC), we purified and characterized these enzymes using fluorogenic substrates specifically designed for ACE sheddases. Purified enzyme identified as a serine protease by N-terminal sequence was able to generate nACE. In the present study, we described for the first time the presence of ACE sheddases in IMC, identified as serine proteases able to hydrolyze sACE in vitro. Further investigations are necessary to elucidate the mechanisms responsible for the expression and regulation of ACE sheddases in MC and their roles in the generation of nACEs, especially the 90 kDa form possibly related to hypertension., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Chronic, unhealed diabetic foot ulcer (DFU) is one of the most severe complications of diabetes mellitus (DM). Naringin, a flavanone glycoside antioxidant, was reported to have antidiabetic and anti-apoptotic properties. In the present study DM was induced experimentally by streptozotocin (STZ, 55 mg/kg, i.p.). In surgically introduced wounds on the dorsal surface of the hind paw of rats, the healing potential of naringin was investigated. Rats were treated with naringin (20, 40 and 80 mg/kg, p.o.), insulin (10 IU/kg, s.c.) and tetrachlorodecaoxide (TCDO) (1 drop, twice a day, topically) for 16 days. The wound area was measured every second day, and on day 17 various biochemical parameters were determined in serum, wound tissue, and histopathological examination of the wound was performed. Naringin (40 and 80 mg/kg) significantly (P<0.05) improved wound area, serum glucose level, glycated Hb and serum insulin. Naringin treatment at 40 and 80 mg/kg resulted in significant (P<0.05) up-regulation of mRNA expression of growth factor (IFG-1, TGF-β and VEGF-c), Ang-1 and collagen-1 whereas mRNA expression of inflammatory mediators (TNF-α, IL-1β and IL-6) was down-regulated. Furthermore, naringin significantly (P<0.05) attenuated STZ-induced apoptosis and stimulated angiogenesis in the wound tissue. Further results suggest that angiogenesis was improved via naringin-mediated inhibition of hyperglycemia, oxidative stress, down-regulation of inflammatory mediator expression and up-regulation of growth factor expression, leading to improved wound healing of DFU., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Abnormal regulation of the renin angiotensin system such as enhanced renal AT1R function and reduced ACE2 activity contributes to obesity-related hypertension. Here, we tested whether long-term AT2R activation affects renal function in obesity using lean and obese Zucker rats treated with the AT2R agonist CGP42112A for 2 weeks. This caused blood pressure to decrease by 13 mm Hg, which was associated with increased urinary sodium excretion in the obese rats. Cortical ACE2 expression and activity, the Mas receptor (MasR), and its ligand angiotensin-(1-7) were all increased in CGP-treated obese compared with control rats. Candesartan-induced natriuresis, a measure of AT₁R function, was reduced but cortical AT₁R expression and angiotensin II levels were similar in CGP-treated obese compared with control rats. Renin and AT2R expression in obese rats was not affected by CGP treatment. In HK-2 cells in vitro, CGP treatment caused increased ACE2 activity and MasR levels but decreased AT₁R levels and renin activity. Thus, long-term AT2R activation shifts the opposing arms of renin angiotensin system and contributes to natriuresis and blood pressure reduction in obese animals. Our study highlights the importance of AT2R as a target for treating obesity-related hypertension.

There is now unequivocal evidence that the angiotensin-converting enzyme 2(ACE2)-Ang-(1-7)-Mas axis is a key component of the renin-angiotensin system (RAS) cascade, which is closely correlated with ischemic insult occurrence. Our previous studies demonstrated that the Ang-(1-7), was an active member of the brain RAS. However, the ACE2-Ang-(1-7)-Mas axis expression after cerebral ischemic injury are currently unclear. In the present study, we investigated the time course of ACE2-Ang-(1-7) and Mas receptor expression in the acute stage of cerebral ischemic stroke. The content of Ang-(1-7) in ischemic tissues and blood serum was measured by specific EIA kits. Real-time PCR and western blot were used to determine messenger RNA (mRNA) and protein levels of the ACE2 and Mas. The cerebral ischemic lesion resulted in a significant increase of regional cerebral and circulating Ang-(1-7) at 6-48 h compared with sham operation group following focal ischemic stroke (12h: 7.276±0.320 ng/ml vs. 2.466±0.410 ng/ml, serum; 1.024±0.056 ng/mg vs. 0.499±0.032, brain) (P<0.05). Both ACE2 and Mas expression were markedly enhanced compared to the control in the ischemic tissues (P<0.05). Mas immunopositive neurons were also seen stronger expression in the ischemic cortex (19.167±2.858 vs. 7.833±2.483) (P<0.05). The evidence collected in our present study will indicate that, ACE2-Ang-(1-7)-Mas axis are upregulated after acute ischemic stroke and would play a pivotal role in the regulation of acute neuron injury in ischemic cerebrovascular diseases., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

This study explored the effect of imidapril on the right ventricular remodeling induced by low ambient temperature in broiler chickens. Twenty-four broiler chickens were randomly divided into 3 groups (n = 8), including the control group, low temperature group, and imidapril group. Chickens in the control group were raised at normal temperature, whereas chickens in the low temperature group and imidapril group were exposed to low ambient temperature (12 to 18°C) from 14 d of age until 45 d of age. At the same time, chickens in the imidapril group were gavaged with imidapril at 3 mg/kg once daily for 30 d. The thickness of the right ventricular wall was observed with echocardiography. The BW and wet lung weight as well as weight of right and left ventricles and ventricular septum were measured. Both wet lung weight index and right ventricular hypertrophy index were calculated. Pulmonary arterial systolic pressure was assessed according to echocardiography. The expression of ACE and ACE2 mRNA in the right ventricular myocardial tissue was quantified by real-time PCR. Proliferating cell nuclear antigen-positive cells were detected by immunohistostaining. The concentration of angiotensin (Ang) II and Ang (1-7) in the right ventricular myocardial tissue was measured with ELISA. The results showed that right ventricular hypertrophy index, wet lung weight index, pulmonary arterial systolic pressure, expression of ACE mRNA in the right ventricular tissue, Ang II concentration, and the thickness of the right ventricular wall in the low temperature group increased significantly compared with those in the control group and imidapril group. The ACE2 mRNA expression increased 36%, whereas Ang (1-7) concentration decreased significantly in the low temperature group compared with that in the control group and imidapril group. In conclusion, imidapril inhibits right ventricular remodeling induced by low ambient temperature in broiler chickens.

Introduction: We investigated the expression of angiotensin receptors in early pregnancy and established whether normal pregnancy or preeclampsia alters the expression and distribution of the uteroplacental AT1R, AT2R and mas/AT1-7R at late gestation., Methods: The percentage of each receptor subtype present in tissues from virgin rats and from normotensive and RUPP hypertensive pregnant rats was established by in vitro receptor autoradiography. Receptor mRNA levels were determined by quantitative PCR at early and late pregnancy., Results: AT1R mRNA levels were up-regulated in the interimplantation (IIS) site at day 7 of gestation. AT2R mRNA levels were decreased at day 5 and 7 in the IIS but increased in the implantation site (IS) at day 5 and 7 as compared to the IIS at day 5. Mas/AT1-7R mRNA was increased in early pregnancy. In normal pregnancy and RUPP the mRNA for all angiotensin receptors was reduced in the uterus at late gestation. The AT1R accounted for the majority of binding in the uterus of virgin and the placenta of pregnant and RUPP. In RUPP pregnancy there was a significant competition with d-Ala in the placenta labyrinth., Discussion and Conclusion: The expression of angiotensin receptors suggests their involvement in the maintenance of early stages of pregnancy. During late gestation down-regulation of Ang receptors in the uterus may arise from feedback down-regulation by Ang II. In the placenta the levels of AT1Rs are equivalent in the RUPP model. The increased binding of mas/AT1-7R at late gestation in RUPP may represent a compensatory mechanism to reduce uteroplacental vascular resistance., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objectives: The renin-angiotensin system (RAS) is implicated in placentation. We determined which RAS pathways are present in two trophoblast cell lines (HTR-8/SVneo and BeWo cells) and the effects of cAMP, which stimulates renal renin., Study Design: The effect of cAMP on RAS gene expression and on prorenin and angiotensin peptides in HTR-8/SVneo and BeWo cells were investigated., Results: In HTR-8/SVneo cells, prorenin mRNA (REN) and protein, (pro)renin receptor (ATP6AP2) and angiotensin II type 1 receptor (AGTR1) were stimulated by cAMP (P < 0.05, P < 0.05, P < 0.001 and P < 0.05, respectively). HTR-8/SVneo cells also expressed angiotensinogen (AGT) and angiotensin converting enzyme 1 (ACE1), but did not express AGTR2 or ACE2 nor the Ang 1-7 receptor (MAS1). BeWo cells did not express REN, and REN was not inducible by cAMP, but cAMP increased ACE2 and MAS1 (both P < 0.05) and decreased AGT (P < 0.05). BeWo cells expressed AGT, ACE1, ACE2 and MAS1 but not ATP6AP2, AGTR1 nor AGTR2. There was net destruction of Ang II in media from HTR-8/SVneo and BeWo incubations and net production of Ang 1-7 by BeWo and untreated HTR-8/SVneo cells., Conclusion: HTR-8/SVneo cells express REN and produce prorenin as well as expressing other RAS genes likely to regulate Ang II/AT(1)R interactions and respond to cAMP, like renal renin-secreting cells. They are more similar to early gestation placentae and are therefore useful for studying effects of renin/ACE/Ang II/AT₁R on cell function. BeWo cells express the ACE2/Ang 1-7/Mas pathway, which is sensitive to cAMP and therefore are useful for studying the effects of ACE2/Ang 1-7/Mas on trophoblast function., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase that degrades angiotensin II with high efficiency leading to the formation of angiotensin-(1-7). ACE2 within the kidneys is largely localized in tubular epithelial cells and in glomerular epithelial cells. Decreased glomerular expression of this enzyme coupled with increased expression of ACE has been described in diabetic kidney disease, both in mice and humans with type 2 diabetes. Moreover, both ACE2 genetic ablation and pharmacological ACE2 inhibition have been shown to increase albuminuria and promote glomerular injury. Studies using recombinant ACE2 have shown the ability of ACE2 to rapidly metabolize Ang II in vivo and form the basis for future studies to examine the potential of ACE2 amplification in the therapy of diabetic kidney disease and cardiovascular disease.

A large body of evidence demonstrates that angiotensin II and angiotensin receptors are required for the pathogenesis of experimental lung fibrosis. Angiotensin has a number of profibrotic effects on lung parenchymal cells that include the induction of growth factors for mesenchymal cells, extracellular matrix molecules, cytokines and increased motility of lung fibroblasts. Angiotensin is also proapoptotic for lung epithelial cells, and is synthesized by a local system (i.e., entirely within the lung tissue) after lung injury by a variety of agents of both xenobiotic and endogenous origins. Recent evidence shows that the counterregulatory molecule angiotensin 1-7, the product of the enzyme ACE-2, inhibits epithelial cell apoptosis and thus acts as an antifibrotic epithelial survival factor. This manuscript reviews the evidence supporting a role for angiotensin in lung fibrogenesis and discusses the signalling mechanisms underlying its action on lung parenchymal cells important in the pathogenesis of pulmonary fibrosis., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Unlabelled: Previous studies showed that angiotensin (Ang) II and Ang-(1-7) concentrations were reduced in the implantation site at day 7 of pregnancy in Sprague-Dawley rats as compared to the site immediately adjacent to it, which does not have the embryo attached, clearly showing the importance of the blastocyst in the regulation of renin-angiotensin system (RAS)., Objective: The objective of this study was to evaluate the regulation of the RAS in the decidualized uterus in the pseudopregnant rat, a model without the presence of a conceptus., Methods: Ovariectomized, adult female rats were sensitized for the decidual cell reaction with steroid treatments; decidualization was induced by oil-injection of the right horn; the left horn served as a control. The uterine content of Ang I, Ang II, and Ang-(1-7) was examined in the decidualized and non-decidualized uteri., Results: Both Ang-(1-7) and Ang II and ACE and ACE2 mRNA were significantly reduced in the decidualized horn as compared to the non-decidualized horn. Immunocytochemical characterization of Ang II, Ang-(1-7), ACE and ACE2 demonstrated that Ang-(1-7), Ang II, and ACE2 polarize to the anti-mesometrial pole with decidualization., Conclusion: The decidualization process elicits marked reduction in uterine Ang II and Ang-(1-7) content as compared to the non-decidualized horn. The differential immunocytochemical expression of Ang II and Ang-(1-7) with ACE2, but not ACE in the anti-mesometrial pole of the decidualized horn may favor the formation and action of Ang-(1-7) in the anti-mesometrial pole, an area which plays a role in triggering the decidualization process., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In the present study, Angiotensin I (Ang I) will be used as model peptide to assess on-column alteration of conformation phenomena. Adsorptive behavior of Ang I on various commercial hydrophobic interaction surfaces (Butyl, Octyl and Phenyl - Sepharose), under different conditions, was investigated. In order to calculate the cis-trans isomerization rate constants of Ang I on the stationary phase's surface, the first and second moments of the proline peptide elution profiles were determined. The activation energies for the isomerization process on Phenyl and Butyl Sepharose were also calculated. Results suggest that the stationary phase catalyzes Ang I isomerization and that catalysis is dependent on hydrophobic interaction ligand nature., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Aims: Perivascular adipose tissue (PVAT) is known to secrete vascular relaxation factors, and angiotensin 1-7 [Ang-(1-7)] acting on the endothelium is one of the endothelium-dependent relaxation factors. Mas protein is the receptor for Ang-(1-7). Using aorta from Mas-knockout (K/O) and wild type (FVB) mice, we wished to establish the essential role of Mas receptors in mediating the endothelium-dependent relaxation response induced by relaxation factors from PVAT., Main Methods: Thoracic aortic rings from K/O and FVB mice were prepared with or without PVAT (PVAT+ and PVAT-) and/or intact endothelium (E+) or with the endothelium removed (E-) for functional studies. The contraction and relaxation responses of these vessels to agonist in the presence of different receptor antagonists were studied., Key Findings: PVAT attenuated the contraction induced by phenylephrine (PHE) in the presence of endothelium only in vessels from FVB mice. Mas receptor antagonists D-Ala-Ang-(1-7) (A779) or D-Pro(7)-Ang-(1-7) enhanced the contraction induced by PHE only in vessels from FVB mice. Ang-(1-7) caused a relaxation response only in E+vessels from FVB mice. Transfer of donor solution from PVAT+ vessels to PVAT- recipient vessels caused a relaxation response among FVB vessels and not among vessels from K/O mice., Significance: Mas receptors are essential in mediating the endothelium-dependent relaxation response induced by PVAT, therefore highlighting the important role of Ang-(1-7) in the control of vascular functions through PVAT., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Angiotensin converting enzyme 2 (ACE2) is a component of the renin-angiotensin system (RAS) which converts Ang II, a potent vasoconstrictor peptide into Ang 1-7, a vasodilator peptide which may act as a negative feedback hormone to the actions of Ang II. The discovery of this enzyme added a new level of complexity to this system. The mesangial cells (MC) have multiple functions in glomerular physiology and pathophysiology and are able to express all components of the RAS. Despite of being localized in these cells, ACE2 has not yet been purified or characterized. In this study ACE2 from mice immortalized MC (IMC) was purified by ion-exchange chromatography. The purified enzyme was identified as a single band around 60-70 kDa on SDS-polyacrylamide gel and by Western blotting using a specific antibody. The optima pH and chloride concentrations were 7.5 and 200 mM, respectively. The N-terminal sequence was homologous with many species ACE2 N-terminal sequences as described in the literature. ACE2 purified from IMC was able to hydrolyze Ang II into Ang 1-7 and the K(m) value for Ang II was determined to be 2.87 ± 0.76 μM. In conclusion, we purified and localized, for the first time, ACE2 in MC, which was able to generate Ang 1-7 from Ang II. Ang 1-7 production associated to Ang II degradation by ACE2 may exert a protective effect in the renal hemodynamic., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The present study attempted to evaluate the effects of chronic intermittent hypoxia (CIH) associated with sleep restriction in hemodynamic parameters and the plasma renin-angiotensin system. Wistar-Hannover rats were submitted to isolated CIH exposure (1000-1600 h), sleep restriction (1600-1000 h), defined as 18-h paradoxical sleep deprivation followed by 6-h sleep permission period and CIH associated to sleep restriction for 21 days. The CIH and sleep restriction group showed a preferential increase in renal sympathetic nervous system (rSNA) associated with a reduction in plasma angiotensin (1-7) concentrations. However, CIH-sleep restriction rats did not modify rSNA and showed a higher angiotensin (1-7) concentration when compared to isolated CIH and sleep restriction. These results suggest that CIH and sleep restriction impaired the cardiovascular system, and its association to sleep loss can modify these effects by partially restoring circulating angiotensin (1-7)., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Although it has been suggested that the renin-angiotensin (RA) system and cathepsins contribute to the development and vulnerability of atherosclerotic plaque, the interaction of the RA system and cathepsins is unclear. Thus, we investigated the effects of an angiotensin II type 1 receptor (AT1) antagonist, olmesartan, on the levels of cathepsins in brachiocephalic atherosclerotic plaque and plaque stabilization in apolipoprotein E (apoE)-deficient mice receiving a high-fat diet. Under a high fat diet, treatment with olmesartan (3 mg/kg per day) maintained collagen and elastin at high levels and attenuated the plaque development and cathepsin S (Cat S) level in the atherosclerotic plaque of apoE-deficient mice. The administration of olmesartan suppressed the accumulation of macrophages in plaque. Immunoreactivities of Cat S and AT1 were observed in macrophages. The amount of Cat S mRNA and the macrophage-mediated collagenolytic and elastolytic activities in cultured macrophages were increased by exposure to angiotensin II (Ang II), and these effects were diminished by olmesartan and the NADPH-oxidase inhibitor apocynin. These results suggested that Cat S derived from macrophages is involved in the mechanisms of atherosclerotic plaque vulnerability, and AT1 blocker maintained the plaque stabilization alongside the suppression of Cat S and macrophage activities., (Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.)