ACE2 Protein Levels Research Articles

The role of angiotensin-converting enzyme-1 (ACE-1) in Alzheimer's disease, and its association with ACE1 genotype.

Overactivation of the classical renin-angiotensin system (cRAS) correlates with cognitive impairment and disease pathology in humans and mouse models of Alzheimer`s disease (AD) (Miners et al., 2008, Kehoe et al., 2018). ACE1, a gene identified by GWAS as a genetic risk factor for AD, encodes ACE-1, a rate-limiting enzyme in the cRAS pathway which generates disease-associated angiotensin II (Ang II) but also degrades and facilitates the clearance of Aβ. ACE-2 counter-balances the actions of cRAS and converts Ang-II to Ang(1-7) (Jiang et al., 2012). The relationship between ACE1, cRAS activation and disease pathology remains unclear. We investigated the relationship between the ACE1 variant (rs4343) (a proxy marker for the more commonly studied indel polymorphism) and disease pathology (Aβ and Tau), ACE-1 protein level and enzyme activity, in a large (n=434) post-mortem study. We studied 318 dementia cases comprising AD, mixed AD and vascular dementia and 116 age-matched controls from the South West Dementia Brain Bank, University of Bristol. ACE1 polymorphism was genotyped by PCR and gene expression determined by qPCR. ACE-1 protein level was measured by sandwich ELISA and enzyme activity by using a fluorogenic peptide activity assay in frontal and parietal lobes in samples for which we have previously obtained data on Aβ and tau pathology by computer-assisted field fraction analysis. ACE-1 protein level was lower in homozygous (I/I) at-risk individuals compared to homozygous (D/D) in AD and mixed dementia cases (p=0.0051). Individuals with I/I genotype had significantly higher (p=0.008) parenchymal Aβ load in the frontal cortex compared with I/D and D/D genotypes, but there is no evidence for an association with tau load in AD. Our study indicates that individuals that are homozygous I/I for ACE1 i.e. at risk have lower ACE-1 protein and enzyme activity and corresponding higher levels of Aβ consistent with a predicted protective role of ACE-1 in AD that acts beyond its central deleterious role in cRAS activation. We will further explore ACE-2 protein and activity levels as well as ACE2 genotype.

Enteric Coronavirus Infection and Treatment Modeled With an Immunocompetent Human Intestine-On-A-Chip.

Many patients infected with coronaviruses, such as SARS-CoV-2 and NL63 that use ACE2 receptors to infect cells, exhibit gastrointestinal symptoms and viral proteins are found in the human gastrointestinal tract, yet little is known about the inflammatory and pathological effects of coronavirus infection on the human intestine. Here, we used a human intestine-on-a-chip (Intestine Chip) microfluidic culture device lined by patient organoid-derived intestinal epithelium interfaced with human vascular endothelium to study host cellular and inflammatory responses to infection with NL63 coronavirus. These organoid-derived intestinal epithelial cells dramatically increased their ACE2 protein levels when cultured under flow in the presence of peristalsis-like mechanical deformations in the Intestine Chips compared to when cultured statically as organoids or in Transwell inserts. Infection of the intestinal epithelium with NL63 on-chip led to inflammation of the endothelium as demonstrated by loss of barrier function, increased cytokine production, and recruitment of circulating peripheral blood mononuclear cells (PBMCs). Treatment of NL63 infected chips with the approved protease inhibitor drug, nafamostat, inhibited viral entry and resulted in a reduction in both viral load and cytokine secretion, whereas remdesivir, one of the few drugs approved for COVID19 patients, was not found to be effective and it also was toxic to the endothelium. This model of intestinal infection was also used to test the effects of other drugs that have been proposed for potential repurposing against SARS-CoV-2. Taken together, these data suggest that the human Intestine Chip might be useful as a human preclinical model for studying coronavirus related pathology as well as for testing of potential anti-viral or anti-inflammatory therapeutics.

Paradoxical effects of cigarette smoke and COPD on SARS-CoV-2 infection and disease

BackgroundHow cigarette smoke (CS) and chronic obstructive pulmonary disease (COPD) affect severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection and severity is controversial. We investigated the effects of COPD and CS on the expression of SARS-CoV-2 entry receptor ACE2 in vivo in COPD patients and controls and in CS-exposed mice, and the effects of CS on SARS-CoV-2 infection in human bronchial epithelial cells in vitro.MethodsWe quantified: (1) pulmonary ACE2 protein levels by immunostaining and ELISA, and both ACE2 and/or TMPRSS2 mRNA levels by RT-qPCR in two independent human cohorts; and (2) pulmonary ACE2 protein levels by immunostaining and ELISA in C57BL/6 WT mice exposed to air or CS for up to 6 months. The effects of CS exposure on SARS-CoV-2 infection were evaluated after in vitro infection of Calu-3 cells and differentiated human bronchial epithelial cells (HBECs), respectively.ResultsACE2 protein and mRNA levels were decreased in peripheral airways from COPD patients versus controls but similar in central airways. Mice exposed to CS had decreased ACE2 protein levels in their bronchial and alveolar epithelia versus air-exposed mice. CS treatment decreased viral replication in Calu-3 cells, as determined by immunofluorescence staining for replicative double-stranded RNA (dsRNA) and western blot for viral N protein. Acute CS exposure decreased in vitro SARS-CoV-2 replication in HBECs, as determined by plaque assay and RT-qPCR.ConclusionsACE2 levels were decreased in both bronchial and alveolar epithelial cells from COPD patients versus controls, and from CS-exposed versus air-exposed mice. CS-pre-exposure potently inhibited SARS-CoV-2 replication in vitro. These findings urge to investigate further the controversial effects of CS and COPD on SARS-CoV-2 infection.

ACE2 correlates with immune infiltrates in colon adenocarcinoma: Implication for COVID-19

Novel coronavirus disease (COVID-19) pandemic has become a global health emergency. It has been reported that a few conditions, including cancer, predispose individuals to SARS-CoV-2 infection and severe form of COVID-19. These findings led us to evaluate the susceptibility of colon adenocarcinoma (COAD) patients to SARS-CoV-2 infection by investigating ACE2 expression in their tumor tissues. The expression analysis revealed that both mRNA and protein levels of ACE2 had increased in colon cancer samples than normal group. Next, the prognosis analysis has indicated that the upregulation of ACE2 was not correlated with patient survival outcomes. Further assessment displayed the hypomethylation of the ACE2 gene promoter in COAD patients. This methylation status has a strong negative correlation with ACE2 gene expression. The functional enrichment analysis of the genes that had similar expression patterns with ACE2 in colon cancer tissues demonstrated that they mainly enriched in Vitamin digestion and absorption pathway. Finally, we found that ACE2 gene expression had a significant association with the immune cell infiltration levels in COAD patients. In conclusion, it has plausible that COAD patients are more likely to be infected with SARS-CoV-2 and experience severe injuries. Moreover, COVID-19 would bring unfavorable survival outcomes for patients with colon cancer by way of immune cell infiltration linked process. The present study highlights the importance of preventiveactionsfor COAD patients during the COVID-19 pandemic.

Effect of ACE1 polymorphism rs1799752 on protein levels of ACE2, the SARS-CoV-2 entry receptor, in alveolar lung epithelium.

Increased protein levels of ACE2 in alveolar epithelium of subjects who are homozygous for the ACE1 insertion of rs1799752 might facilitate host cell entry of #SARSCoV2 and explain the higher prevalence of #COVID19 in certain regions https://bit.ly/3k6aAE8

Stroke increases the expression of ACE2, the SARS-CoV-2 binding receptor, in murine lungs

BackgroundThe newly emerged severe acute respiratory syndrome coronavirus (SARS-CoV-2) has caused a worldwide pandemic of human respiratory disease. Angiotensin-converting enzyme (ACE) 2 is the key receptor on lung epithelial cells to facilitate initial binding and infection of SARS-CoV-2. The binding to ACE2 is mediated via the spike glycoprotein present on the viral surface. Recent clinical data have demonstrated that patients with previous episodes of brain injuries are a high-risk group for SARS-CoV-2 infection. An explanation for this finding is currently lacking. Sterile tissue injuries including stroke induce the release of several inflammatory mediators that might modulate the expression levels of signaling proteins in distant organs. Whether systemic inflammation following brain injury can specifically modulate ACE2 expression in different vital tissues has not been investigated. MethodsFor the induction of brain stroke, mice were subjected to a surgical procedure for transient interruption of blood flow in the middle cerebral artery for 45 min and sacrificed after 1 and 3 days for analysis of brain, lung, heart, and kidney tissues. Gene expression and protein levels of ACE2, ACE, IL-6 and IL1β were measured by quantitative PCR and Western blot, respectively. The level of soluble ACE2 in plasma and bronchial alveolar lavage (BAL) was measured using an immunoassay. Immune cell populations in lymphoid organs were analyzed by flow cytometry. Post-stroke pneumonia in mice was examined by bacterial cultures from lung homogenates and whole blood. ResultsStrikingly, 1 day after surgery, we observed a substantial increase in the protein levels of ACE2 in the lungs of stroke mice compared to sham-operated mice. However, the protein levels of ACE2 were found unchanged in the heart, kidney, and brain of these animals. In addition, we found increased transcriptional levels of alveolar ACE2 after stroke. The increased expression of ACE2 was significantly associated with the severity of behavioral deficits after stroke. The higher protein levels of alveolar ACE2 persisted until 3 days of stroke. Interestingly, we found reduced levels of soluble ACE2 in plasma but not in BAL in stroke-operated mice compared to sham mice. Furthermore, stroke-induced parenchymal and systemic inflammation was evident with the increased expression of IL-6 and IL-1β. Reduced numbers of T-lymphocytes were present in the blood and spleen as an indicator of sterile tissue injury-induced immunosuppression. ConclusionsWe demonstrate specific augmented alveolar ACE2 levels and inflammation in murine lungs after experimental stroke. These pre-clinical findings suggest that patients with brain injuries may have increased binding affinity to SARS-CoV-2 in their lungs which might explain why stroke is a risk factor for higher susceptibility to develop COVID-19.

Hypoxia reduces cell attachment of SARS-CoV-2 spike protein by modulating the expression of ACE2, neuropilin-1, syndecan-1 and cellular heparan sulfate

ABSTRACT A main clinical parameter of COVID-19 pathophysiology is hypoxia. Here we show that hypoxia decreases the attachment of the receptor-binding domain (RBD) and the S1 subunit (S1) of the spike protein of SARS-CoV-2 to epithelial cells. In Vero E6 cells, hypoxia reduces the protein levels of ACE2 and neuropilin-1 (NRP1), which might in part explain the observed reduction of the infection rate. In addition, hypoxia inhibits the binding of the spike to NCI-H460 human lung epithelial cells by decreasing the cell surface levels of heparan sulfate (HS), a known attachment receptor of SARS-CoV-2. This interaction is also reduced by lactoferrin, a glycoprotein that blocks HS moieties on the cell surface. The expression of syndecan-1, an HS-containing proteoglycan expressed in lung, is inhibited by hypoxia on a HIF-1α-dependent manner. Hypoxia or deletion of syndecan-1 results in reduced binding of the RBD to host cells. Our study indicates that hypoxia acts to prevent SARS-CoV-2 infection, suggesting that the hypoxia signalling pathway might offer therapeutic opportunities for the treatment of COVID-19.

Lung and Kidney ACE2 and TMPRSS2 in Renin-Angiotensin System Blocker-Treated Comorbid Diabetic Mice Mimicking Host Factors That Have Been Linked to Severe COVID-19.

The causes of the increased risk of severe coronavirus disease 2019 (COVID-19) in people with diabetes are unclear. It has been speculated that renin-angiotensin system (RAS) blockers may promote COVID-19 by increasing ACE2, which severe acute respiratory syndrome coronavirus 2 uses to enter host cells, along with the host protease TMPRSS2. Taking a reverse translational approach and by combining in situ hybridization, primary cell isolation, immunoblotting, quantitative RT-PCR, and liquid chromatography-tandem mass spectrometry, we studied lung and kidney ACE2 and TMPRSS2 in diabetic mice mimicking host factors linked to severe COVID-19. In healthy young mice, neither the ACE inhibitor ramipril nor the AT1 receptor blocker telmisartan affected lung or kidney ACE2 or TMPRSS2, except for a small increase in kidney ACE2 protein with ramipril. In contrast, mice with comorbid diabetes (aging, high-fat diet, and streptozotocin-induced diabetes) had heightened lung ACE2 and TMPRSS2 protein levels and increased lung ACE2 activity. None of these parameters were affected by RAS blockade. ACE2 was similarly upregulated in the kidneys of mice with comorbid diabetes compared with aged controls, whereas TMPRSS2 (primarily distal nephron) was highest in telmisartan-treated animals. Upregulation of lung ACE2 activity in comorbid diabetes may contribute to an increased risk of severe COVID-19. This upregulation is driven by comorbidity and not by RAS blockade.

Paracetamol-Induced Glutathione Consumption: Is There a Link With Severe COVID-19 Illness?

COVID-19 pandemic is posing an unprecedented sanitary threat: antiviral and host-directed medications to treat the disease are urgently needed. A great effort has been paid to find drugs and treatments for hospitalized, severely ill patients. However, medications used for the domiciliary management of early symptoms, notwithstanding their importance, have not been and are not presently regarded with the same attention and seriousness. In analogy with other airways viral infections, COVID-19 patients in the early phase require specific antivirals (still lacking) and non-etiotropic drugs to lower pain, fever, and control inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol (PAC) are widely used as non-etiotropic agents in common airways viral infections and hence are both theoretically repurposable for COVID-19. However, a warning from some research reports and National Authorities raised NSAIDs safety concerns because of the supposed induction of angiotensin-converting enzyme 2 (ACE2) levels (the receptor used by SARS-CoV2 to enter host airways cells), the increased risk of bacterial superinfections and masking of disease symptoms. As a consequence, the use of NSAIDs was, and is still, discouraged while the alternative adoption of paracetamol is still preferred. On the basis of novel data and hypothesis on the possible role of scarce glutathione (GSH) levels in the exacerbation of COVID-19 and of the GSH depleting activity of PAC, this commentary raises the question of whether PAC may be the better choice.

Expression of ACE2, the SARS-CoV-2 Receptor, in Lung Tissue of Patients With Type 2 Diabetes

Increased expression of pulmonary ACE2, the SARS-CoV-2 receptor, could contribute to increased infectivity of COVID-19 in patients with diabetes, but ACE2 expression has not been studied in lung tissue of subjects with diabetes. We therefore studied ACE2 mRNA and protein expression in lung tissue samples of subjects with and without diabetes that were collected between 2002 and 2020 from patients undergoing lobectomy for lung tumors. For RT-PCR analyses, samples from 15 subjects with diabetes were compared with 91 randomly chosen control samples. For immunohistochemical staining, samples from 26 subjects with diabetes were compared with 66 randomly chosen control samples. mRNA expression of ACE2 was measured by quantitative RT-PCR. Protein levels of ACE2 were visualized by immunohistochemistry on paraffin-embedded lung tissue samples and quantified in alveolar and bronchial epithelium. Pulmonary ACE2 mRNA expression was not different between subjects with or without diabetes. In contrast, protein levels of ACE2 were significantly increased in both alveolar tissue and bronchial epithelium of patients with diabetes compared with control subjects, independent of smoking, chronic obstructive pulmonary disease, BMI, renin-angiotensin-aldosterone system inhibitor use, and other potential confounders. To conclude, we show increased bronchial and alveolar ACE2 protein expression in patients with diabetes. Further research is needed to elucidate whether upregulation of ACE2 expression in airways and lungs has consequences on infectivity and clinical outcomes of COVID-19.

MicroRNAs targeting the SARS-CoV-2 entry receptor ACE2 in cardiomyocytes

The World Health Organization (WHO) declared coronavirus disease 2019 (COVID-19) as a public health emergency of international concern as more than 15 million cases were reported by 24th July 2020. Angiotensin-converting enzyme 2 (ACE2) is a COVID-19 entry receptor regulating host cell infection. A recent study reported that ACE2 is expressed in cardiomyocytes. In this study, we aimed to explore if there are microRNA (miRNA) molecules which target ACE2 and which may be exploited to regulate the SARS-CoV-2 receptor. Our data reveal that both Ace2 mRNA and Ace2 protein levels are inhibited by miR-200c in rat primary cardiomyocytes and importantly, in human iPSC-derived cardiomyocytes. We report the first miRNA candidate that can target ACE2 in cardiomyocytes and thus may be exploited as a preventive strategy to treat cardiovascular complications of COVID-19.

Effect of angiotensin II and angiotensin-(1-7) on proliferation of stem cells from human dental apical papilla.

The effects of the renin-angiotensin system (RAS) on stem cells isolated from human dental apical papilla (SCAPs) are completely unknown. Therefore, the aim of this study was to identify RAS components expressed in SCAPs and the effects of angiotensin (Ang) II and Ang-(1-7) on cell proliferation. SCAPs were collected from third molar teeth of adolescents and maintained in cell culture. Messenger RNA expression and protein levels of angiotensin-converting enzyme (ACE), ACE2, and Mas, Ang II type I (AT1) and type II (AT2) receptors were detected in SCAPs. Treatment with either Ang II or Ang-(1-7) increased the proliferation of SCAPs. These effects were inhibited by PD123319, an AT2 antagonist. While Ang II augmented mTOR phosphorylation, Ang-(1-7) induced ERK1/2 phosphorylation. In conclusion, SCAPs produce the main RAS components and both Ang II and Ang-(1-7) treatments induced cell proliferation mediated by AT2 activation through different intracellular mechanisms.

Rapeseed protein-derived peptides, LY, RALP, and GHS, modulates key enzymes and intermediate products of renin\u2013angiotensin system pathway in spontaneously hypertensive rat

Rapeseed proteins are a rich source of bioactive peptides. LY, RALP and GHS were previously identified from rapeseed protein hydrolysates as potent ACE and renin inhibiting peptides. In this study, the rapeseed peptides were individually evaluated for their molecular mechanisms and regulatory effects on components of the renin–angiotensin system in spontaneously hypertensive rats (SHR), including the mRNA and/or protein levels of angiotensin-converting enzyme (ACE), renin, ACE2, angiotensin II and angiotensin-(1–7) in myocardial tissues. Oral administration of 30 mg peptides/kg body weight every 2 days for five weeks significantly decreased the systolic blood pressure and the myocardial mRNA and protein levels of ACE and renin in SHR. LY, RALP and GHS also increased the expression of ACE2, angiotensin-(1-7) and Mas receptor levels, which may have mediated their antihypertensive activity. Dipeptide LY also inhibited angiotensin II protein expression in the heart tissue. Taken together, the finding demonstrates the multi-target physiological effects of the rapeseed peptides, beyond ACE and renin inhibition, which enhances knowledge of the antihypertensive mechanisms of food protein-derived peptides.

Angiotensin-converting enzyme 2-angiotensin (1-7)-Mas axis prevents pancreatic acinar cell inflammatory response via inhibition of the p38 mitogen-activated protein kinase/nuclear factor-κB pathway.

The aim of the present study was to investigate the role of the angiotensin-converting enzyme (ACE)2-angiotensin‑(Ang)-(1-7)-Mas axis in the pathogenesis of pancreatitis and the association between this axis and the p38mitogen-activated protein kinase (p38MAPK)/nuclear factor(NF-κB) signaling pathway in pancreatic acinar cells. Mouse pancreatic acinar cancer (MPC-83) cells were stimulated with 10nM caerulein (CAE) to create an invitro model of acute pancreatitis, and collected for analysis at 2, 6, 12, 24 and 48h post stimulation. In addition, cells were pretreated with different concentrations of Ang‑(1‑7), Ang‑(1‑7) antagonist A779, p38MAPK inhibitor SB203580 or ACE2 inhibitor DX600 for 30min, and then stimulated with CAE for 24h. The ACE2, Mas receptor, p38MAPK, phosphorylated (p)-p38MAPK and NF-κB expression levels were evaluated using western blotting and immunofluorescence. p38MAPK, NF-κB, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-8 and IL-10 mRNA expression levels were assessed using reverse transcription-quantitative polymerase chain reaction. The results of the immunofluorescence assay demonstrated that ACE2 and p38MAPK were present mainly in the cytoplasm, while the Mas receptor was located mainly in the cell membrane. ACE2, p38MAPK and p-p38MAPK protein levels were significantly increased (P<0.05) following stimulation with CAE compared with those in the control group and peaked at 24h. Mas receptor protein levels were significantly upregulated (P<0.05) between 6 and 24h, peaking at 12h. Ang‑(1‑7) and SB203580 downregulated p-p38MAPK and NF-κB expression and the mRNA levels of inflammatory factors IL-6, TNF-α and IL-8, but upregulated the mRNA level of inflammatory factor IL-10 compared with those treated with CAE alone. These results were supported by the opposite outcomes observed for cells treated with A779 or DX600. Therefore, it was concluded that the ACE2-Ang‑(1‑7)-Mas axis significantly inhibits pancreatitis by inhibition of the p38MAPK/NF-κB signaling pathway.

Azilsartan ameliorates diabetic cardiomyopathy in young db/db mice through the modulation of ACE-2/ANG 1–7/Mas receptor cascade

Hyperglycemia up-regulates intracellular angiotensin II (ANG-II) production in cardiac myocytes. This study investigated the hemodynamic and metabolic effects of azilsartan (AZL) treatment in a mouse model of diabetic cardiomyopathy and whether the cardioprotective effects of AZL are mediated by the angiotensin converting enzyme (ACE)-2/ANG 1–7/Mas receptor (R) cascade. Control db/+ and db/db mice (n=5 per group) were treated with vehicle or AZL (1 or 3mg/kg/d oral gavage) from the age of 8 to 16weeks. Echocardiography was then performed and myocardial protein levels of ACE-2, Mas R, AT1R, AT2R, osteopontin, connective tissue growth factor (CTGF), atrial natriuretic peptide (ANP) and nitrotyrosine were measured by Western blotting. Oxidative DNA damage and inflammatory markers were assessed by immunofluorescence of 8-hydroxy-2′-deoxyguanosine (8-OHdG), tumor necrosis factor (TNF)-α and interleukin 6 (IL-6). Compared with db/+ mice, the vehicle-treated db/db mice developed obesity, hyperglycemia, hyperinsulinemia and diastolic dysfunction along with cardiac hypertrophy and fibrosis. AZL treatment lowered blood pressure, fasting blood glucose and reduced peak plasma glucose during an oral glucose tolerance test. AZL-3 treatment resulted in a significant decrease in the expression of cytokines, oxidative DNA damage and cardiac dysfunction. Moreover, AZL-3 treatment significantly abrogated the downregulation of ACE-2 and Mas R protein levels in db/db mice. Furthermore, AZL treatment significantly reduced cardiac fibrosis, hypertrophy and their marker molecules (osteopontin, CTGF, TGF-β1 and ANP). Short-term treatment with AZL-3 reversed abnormal cardiac structural remodeling and partially improved glucose metabolism in db/db mice by modulating the ACE-2/ANG 1–7/Mas R pathway.

Aliskiren Administration during Early Postnatal Life Sex-Specifically Alleviates Hypertension Programmed by Maternal High Fructose Consumption.

Key points summary Maternal high-fructose (HF) induces programmed hypertension in adult offspring.Early aliskiren administration prevents HF-induced hypertension in both sexes of adult offspring.HF regulates RAS components in the offspring kidney in a sex-specific manner.HF alters renal transcriptome, with female offspring being more sensitive.Deprogramming strategy to prevent hypertension might be sex-specific.Background: Maternal high fructose (HF) intake induced renal programming and hypertension in male adult offspring. We examined whether maternal HF intake causes programmed hypertension and whether aliskiren administration confers protection against the process in a sex-specific manner, with a focus on the transcriptome changes in the kidney using next-generation RNA sequencing (NGS) technology and renin-angiotensin system (RAS).Methods: Pregnant Sprague—Dawley rats received regular chow or chow supplemented with 60% fructose throughout pregnancy and lactation. Offspring were assigned to six groups: male control, male HF (MHF), MHF+Aliskiren, female control, female HF (FHF), and FHF+Aliskiren. Oral aliskiren 10 mg/kg/day was administered via gastric gavage between 2 and 4 weeks of age. Rats were sacrificed at 12 weeks of age.Results: Maternal HF intake induced programmed hypertension in 12-week-old offspring of both sexes. HF regulated renal transcriptome and RAS components in the offspring kidney in a sex-specific manner. Aliskiren administration prevented HF-induced programmed hypertension in both sexes of adult offspring. Aliskiren administration increased ACE2 and MAS protein levels in female kidneys exposed to maternal HF intake.Conclusion: Maternal HF induced programmed hypertension in both sexes of adult offspring, which was sex-specifically mitigated by early aliskiren administration. Better understanding of the sex-dependent mechanisms that underlie maternal HF-induced renal programming will help develop a novel sex-specific strategy to prevent programmed hypertension.

Chronic treatment with Ang-(1-7) reverses abnormal reactivity in the corpus cavernosum and normalizes diabetes-induced changes in the protein levels of ACE, ACE2, ROCK1, ROCK2 and omega-hydroxylase in a rat model of type 1 diabetes.

Angiotensin-(1-7) [Ang-(1-7)] may have beneficial effects in diabetes mellitus-induced erectile dysfunction (DMIED) but its molecular actions in the diabetic corpus cavernosum (CC) are not known. We characterized the effects of diabetes and/or chronic in vivo administration of Ang-(1-7) on vascular reactivity in the rat corpus cavernosum (CC) and on protein expression levels of potential downstream effectors of the renin-angiotensin-aldosterone system (RAAS) such as angiotensin-converting enzyme (ACE), ACE2, Rho kinases 1 and 2 (ROCK1 and ROCK2), and omega-hydroxylase, the cytochrome-P450 enzyme that metabolizes arachidonic acid to form the vasoconstrictor, 20-hydroxyeicosatetraenoic acid. Streptozotocin-treated rats were chronicically administered Ang-(1-7) with or without A779, a Mas receptor antagonist, during weeks 4 to 6 of diabetes. Ang-(1-7) reversed diabetes-induced abnormal reactivity to vasoactive agents (endothelin-1, phenylepherine, and carbachol) in the CC without correcting hyperglycemia. Six weeks of diabetes led to elevated ACE, ROCK1, ROCK 2, and omega-hydroxylase and a concomitant decrease in ACE2 protein expression levels that were normalized by Ang-(1-7) treatment but not upon coadministration of A779. These data are supportive of the notion that the beneficial effects of Ang-(1-7) in DMIED involve counterregulation of diabetes-induced changes in ACE, ACE2, Rho kinases, and omega-hydroxylase proteins in the diabetic CC via a Mas receptor-dependent mechanism.

Angiotensin II induced proteolytic cleavage of myocardial ACE2 is mediated by TACE/ADAM-17: A positive feedback mechanism in the RAS

Angiotensin converting enzyme (ACE) 2 is a key negative regulator of the renin–angiotensin system where it metabolizes angiotensin (Ang) II into Ang 1–7. We hypothesize that Ang II suppresses ACE2 by increasing TNF-α converting enzyme (TACE) activity and ACE2 cleavage. Ang II infusion (1.5mg/kg/day) in wild-type mice for 2weeks resulted in substantial decrease in myocardial ACE2 protein levels and activity with corresponding increase in plasma ACE2 activity, prevented by AT1R blockade. Ang II resulted in AT1R-mediated increase in myocardial TACE expression and activity, and membrane translocation of TACE. Ang II treatment in Huh7 cells exhibited AT1R-dependent metalloproteinase mediated shedding of ACE2 while transfection with siTACE prevented shedding of ACE2; cardiomyocyte-specific deletion of TACE also prevented shedding of ACE2. Reactive oxygen species played a key role since p47phoxKO mice were resistant to Ang II-induced TACE phosphorylation and activation with preservation of myocardial ACE2 which dampened Ang II-induced cardiac dysfunction and hypertrophy. In conclusion, Ang II induces ACE2 shedding by promoting TACE activity as a positive feedback mechanism whereby Ang II facilitates the loss of its negative regulator, ACE2. In HF, elevated plasma ACE2 activity likely represents loss of the protective effects of ACE2 in the heart.

Expression and significance of ACE2-Ang-(1-7)-Mas axis in the endometrium of patients with polycystic ovary syndrome

To explore the expression of renin-angiotensin system component (ACE-AngII-AT1/AT2 & ACE2-Ang-(1-7)-Mas) in endometrium of polycystic ovary syndrome (PCOS) patients and normal controls. Thirty cases of normal endometrium in proliferative and secretory phases respectively were selected for the protein levels of AngII, AT1, AT2, ACE2, Ang-(1-7) and Mas through immunohistochemistry. And the specimens of proliferative endometrium from 15 PCOS patients and 15 normal controls respectively were prepared for the expressions of AT1, AT2, ACE2 and Mas mRNA through relative quantitative -polymerase chain reaction (RQ-PCR). The histological phases of endometria were confirmed by hematoxylin & eosin staining under microscope. The expressions of AngII, AT1R, AT2R, ACE2, Ang-(1-7) and Mas showed periodical changes in endometrium throughout normal menstrual cycles and shared a similar trend. The expression was more pronounced in epithelial cells than that in stromal cells while it was also more dramatic in secretory phase than proliferative phase; The mRNA expressions of AT1, AT2, ACE2 and MAS were higher in PCOS endometrium than those in normal controls. Statistically significant differences existed between two groups (P < 0.01). There is local existence of RAS in endometrium; Increased expressions of AT1 mRNA, AT2 mRNA, ACE2 mRNA and Mas mRNA in endometrium of PCOS may influence endometrial development and play a role in the pathological process of PCOS.

Molecular Changes of the Angiotensin Converting Enzyme 2 Pathway in Myocardial Tissue from Heart Failure Patients Undergoing Heart Transplantation

Background: The angiotensin-converting enzyme homologue ACE2 and the peptide angiotensin 1-7 (Ang 1-7) have antifibrotic effects, but it is not understood whether they have a protective role in cardiac remodeling. We aimed to analyze the Ang 1-7 Mas receptor and ACE2 expresion levels and their relationship with fibrotic and remodeling factors in human heart failure (HF) and compared them with non-pathological human hearts.Methods: This was a human case-control study in which two groups of samples were analyzed. Controls were organ donors without cardiovascular pathology, but whose heart could not be used for transplantation. Cases were patients with end-stage HF and left ventricle samples were harvested right after the heart transplantation surgery. They were either kept with liquid nitrogen until their analysis or were processed for paraffin embedding. We quantified mRNA expression by real time PCR and ACE2 protein levels by western blot. The collagen deposition was stained by sirius red and quantified with morphometric analysis.Results: Expression of the MMP3 stromelysin mRNA was only detectable in 10 out of 33 pathological samples and in 1 out of 13 control samples. Expression of components of the ACE2 pathway and fibrotic factors were higher in patients with detectable MMP3 expression than in patients with non-detectable MMP3. No differences were found between patients with MMP3 expression or no MMP3 expression regarding etiology, functional class, ventricle dilatation or medication.Conclusions: Only a subset of myocardiums from HF patients is active in the remodeling process at the moment of heart transplantation, as indicated by the MMP3 expression and the higher levels of fibrotic factors. Angiotensin 1-7 Mas receptor expression and ACE2 protein levels are increased in this myocardium subset, suggesting a role for the ACE2 in this process. Overall, we encountered molecular differences in transplanted hearts from patients with similar clinical characteristics.