Appendix 8-1. The study of ACE2 and heart diseases
Authors Year Experimental model and study design Key findings
Crackower et al. 2002
Showed ace2 maps to a defined quantitative trait locus (QTL) on the X chromosome in three different rat models of hypertension.
In all hypertensive rat strains, ACE2 messenger RNA and protein expression were markedly reduced.
Targeted disruption of ACE2 in mice results in a severe cardiac contractility defect, increased angiotensin II levels, and up-regulation of hypoxia-induced genes in the heart.
Donoghue et al. 2003
The hypothesis that cardiac ACE2 activity contributes to features of ventricular remodeling associated with the renin-angiotensin system by generating transgenic mice with increased cardiac ACE2 expression.
The gap junction proteins connexin40 and connexin43 were down-regulated in the transgenic hearts, indicating that ACE2-mediated gap junction remodeling may account for the observed electrophysiologic disturbances.
Goulter et al. 2004
Assessed changes in gene expression of ACE2, ACE, AT1R and renin in human ventricular
myocardium from donors with non-diseased hearts, idiopathic dilated cardiomyopathy (IDC) and ischemic cardiomyopathy (ICM).
ACE and ACE2 is up-regulated in human IDC and ICM. ACE2 may be a relevant target for the treatment of heart failure and may have important functional consequences in heart failure.
Campbell et al. 2004
Ang I, Ang II, Ang 1-9 and Ang 1-7 were measured in arterial and coronary sinus blood of heart failure subjects receiving ACE inhibitor therapy and in normal subjects not receiving ACE inhibitor therapy.
The failure of Ang 1-9 levels to increase in response to increased Ang I levels indicated little role for ACE2 in Ang I metabolism. The levels of Ang 1-7 were more linked to those of Ang I than Ang II, consistent with its formation by endopeptidase-mediated metabolism of Ang I, rather than by ACE2-mediated metabolism of Ang II.
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Ishiyama et al. 2004
Investigated in Lewis normotensive rats the effect of coronary artery ligation on the expression of ACE and ACE2 and AT1R 28 days after MI. Losartan, olmesartan, or the vehicle (isotonic saline) was administered via osmotic minipumps for 28 days after coronary artery ligation or sham operation.
Coronary artery ligation was associated with increased plasma concentrations of Ang I, Ang II, Ang 1-7, and serum aldosterone, and reduced AT1R mRNA. The effect of Ang II blockade on cardiac ACE2 mRNA that may be due to direct blockade of AT1R receptors or a modulatory effect of increased Ang 1-7.
Ferrario et al. 2005
Blood pressure, cardiac rate, and plasma and cardiac tissue levels of Ang II and Ang 1-7, together with cardiac ACE2, neprilysin, AT1R, and mas receptor mRNAs, were measured in Lewis rats 12 days after continuous administration of vehicle, lisinopril, losartan, or both drugs combined in their drinking water.
Selective blockade of either Ang II synthesis or activity induced increases in cardiac ACE2 gene expression and cardiac ACE2 activity, whereas the combination of losartan and lisinopril was associated with elevated cardiac ACE2 activity but not cardiac ACE2 mRNA.
The antihypertensive action of AT1 antagonists may in part be due to increased Ang II metabolism by ACE2.
Karram et al. 2005
Examined the effects of experimental CHF induced by an aortocaval fistula (ACF) and of its treatment with Ang II and aldosterone inhibitors and
antagonists on the relative levels of ACE and ACE2.
ACF increased the cardiac levels of ACE, local Ang II and aldosterone, and decreased those of ACE2. ACE isoform shift may represent an important component of the development of cardiac remodeling in response to hemodynamic overload, and its correction may contribute to the beneficial therapeutic effects of renin-angiotensin-aldosterone system inhibitors.
Burrell et al. 2005
Rats were killed at days 1, 3, and 28 after MI, or treated for 4 weeks with the ACE inhibitor ramipril.
Cardiac gene and protein expression of ACE and ACE2 were assessed by quantitative real-time RT-PCR and immunohistochemistry/activity assays/in vitro autoradiography, respectively.
Both ACE and ACE2 mRNA increased in the
border/infarct area compared with the viable area after MI. ACE2 protein localized to macrophages, vascular endothelium, smooth muscle, and myocytes. The increase in ACE2 after MI suggests that it plays an important role in the negative modulation of the RAS in the generation and degradation of angiotensin peptides after cardiac injury.
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Huentelman et al 2005
Evaluate whether overexpression of ACE2 could protect the heart from Ang II-induced hypertrophy and fibrosis. Lentiviral vector encoding mouse ACE2 (lenti-mACE2) or GFP was injected intracardially in 5-day-old SD rats.
Transduction with lenti-mACE2 resulted in significant attenuation of the increased HW:BW and myocardial fibrosis induced by Ang II infusion. These observations demonstrate that ACE2 overexpression results in protective effects on Ang II-induced cardiac hypertrophy and fibrosis.
Díez-Freire et al. 2006
Determined whether ACE2 gene transfer could decrease high blood pressure (BP) and would improve cardiac dysfunctions induced by
hypertension in the spontaneously hypertensive rat (SHR) model. Systolic BP, cardiac functions, and perivascular fibrosis were evaluated 4 mo after ACE2 gene transduction.
ACE2 gene transfer resulted in a significant attenuation of high BP and left ventricular wall thickness in the SHR. In addition, in lenti-ACE2-treated SHR, left ventricular end diastolic and end systolic diameters were increased. Finally, lenti-ACE2 treatment resulted in a significant attenuation of perivascular fibrosis in the SHR.
Gurley et al. 2006
To clarify the physiological roles of ACE2,
generated mice with targeted disruption of the ace2.
ACE2-deficient mice were viable, fertile, and lacked any gross structural abnormalities.
Acute Ang II infusion, plasma concentrations of Ang II increased almost 3-fold higher in ACE2-deficient mice than in controls, blood pressures were substantially higher in the ACE2-deficient mice than in WT. ACE2 is a functional component of the RAS and metabolizing Ang II and thereby contributing to regulation of blood pressure.
Yamamoto et al. 2006
Used ACE2-/y mice to analyze the role of ACE2 in the response to pressure overload, twelve-week-old ACE2-/y mice and wild-type (WT) mice received transverse aortic constriction (TAC) or sham operation.
In response to TAC, ACE2-/y mice developed cardiac hypertrophy and dilatation, displayed decreased cardiac contractility and increased fetal cardiac gene induction, compared with WT mice. Cardiac Ang II concentration and activity of mitogen-activated protein (MAP) kinases were markedly increased in ACE2-/y mice in response to TAC.
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Ocaranza et al. 2006
The early and long-term effects of coronary artery ligation on the plasma and left ventricular
angiotensin-converting enzyme (ACE and ACE2) activities, ACE and ACE2 mRNA levels, circulating angiotensin (Ang) levels [Ang I, Ang-(1-7),
Ang-(1-9), and Ang II], and cardiac function were evaluated 1 and 8 weeks after experimental MI in adult SD rats.
At week 1, circulating Ang II and Ang 1-9 as well as left ventricular and plasma ACE and ACE2 activities increased in myocardial-infarcted rats as compared with controls. At 8 weeks post-MI, circulating ACE and Ang II remained higher, but plasma and left ventricular ACE2 and circulating Ang 1-9 were lower than in controls. The decrease in ACE2 expression and activity and circulating Ang 1-9 levels in late ventricular dysfunction post-MI were prevented with enalapril.
Batlle et al. 2006
Analyzed left ventricular biopsies from 30 patients with heart failure undergoing heart transplantation and 12 organ donors. The mRNA levels of ACE, ACE2, chymase and endothelial nitric oxide
synthase (eNOS), were quantified by real-time PCR and mast cell density was assessed by
immunohistochemistry.
There was higher ACE and chymase mRNA expression and mast cell density in failing than in control
myocardium and no changes in ACE2 expression were detected. eNOS mRNA levels were lower in failing hearts. ACE2 mRNA expression is not altered in human end-stage HF.
Agata et al. 2006
Overexpression of ACE2 may be related to a reduction in Ang II level and the cardioprotective effect of olmesartan. Administration olmesartan for 4 weeks to 12-week-old stroke-prone spontaneously hypertensive rats (SHRSP) significantly reduced blood pressure and left ventricular weight compared to those in SHRSP given a vehicle.
Olmesartan significantly increased the cardiac ACE2 expression level compared to that in Wistar Kyoto rats and SHRSP treated with a vehicle. Olmesartan may exhibit an ACE inhibitory action in addition to an Ang II receptor blocking action, prevent an increase in Ang II, and protect cardiovascular remodeling through an increase in cardiac nitric oxide production and endogenous Ang 1-7 via overexpression of ACE2.
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Grobe et al. 2007
Cardiac fibroblasts from SD rat hearts were grown to confluence and transduced with a lentiviral vector containing murine ACE2 cDNA under
transcriptional control by the EF1α (elongation factor 1α) promoter (lenti-ACE2). Transduction of fibroblasts with lenti-ACE2 resulted in a viral dose-dependent increase in ACE2 activity.
The endogenous ACE2 activity is observed in cardiac myocytes, but not in cardiac fibroblasts. ACE2 overexpression was associated with a significant attenuation of basal and
hypoxia/re-oxygenation-induced collagen production, and TGF-β expression by the fibroblasts.
Bäcklund et al. 2007
Male Wistar rats were randomised to receive either streptozotocin (diabetic group) or citrate buffer (control group) intravenously. MI was produced four weeks later by ligating the left descending coronary artery. ACE and ACE 2, AT1R, AT2R, and
connective tissue growth factor (CTGF) mRNA expression were determined.
Myocardial ACE 2 and AT2R mRNA expression levels were significantly lower in diabetic compared to non-diabetic rats after MI. In contrast, AT1R, ACE and CTGF mRNA levels were up-regulated in diabetic as compared with non-diabetic rats after MI. This unbalanced activation of the RAS may influence the pathophysiology of myocardial injury in diabetes after MI.
Pan et al. 2007
Examined expression of ACE2 in the fibrillating atria of pigs and its involvement in fibrotic
pathogenesis during AF. Nine adult pigs underwent continuous rapid atrial pacing to induce sustained AF and six pigs were sham controls (i.e., sinus rhythm; SR).
The relative amount of collagen type I and ACE activity in the atria with AF were significantly increased as compared with that in the SR, but ACE2 gene and protein expression in the AF subjects were significantly decreased compared with those in the SR subjects
Takeda et al. 2007
The blood pressure (BP) , plasma renin activity (PRA), plasma aldosterone concentration (PAC), heart weight, endothelium-dependent relaxation (EDR), and mRNA of collagen III, angiotensinogen, ACE, and ACE2 in the heart were measured in Dahl salt-sensitive hypertensive (DS) rats and in Dahl salt-resistant (DR) rats fed high or low salt diets.
A high salt diet increased BP (140%), heart/body weight (132%), and collagen III mRNA levels (146%) and decreased PRA and PAC concomitant with increased expression of cardiac angiotensinogen mRNA and decreased mRNA levels of ACE2 in DS rats. In DS rats, blockade of aldosterone or Ang II protects cardiac hypertrophy and fibrosis by inactivation of the local RAAS in the heart.
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Grobe et al. 2007
Hypothesized that chronic infusion of Ang 1-7 would prevent cardiac remodeling induced by chronic infusion of Ang II. Infusion of Ang II into adult SD rats resulted in significantly increased blood pressure, myocyte hypertrophy, and midmyocardial interstitial fibrosis.
Chronic infusion of Ang II, co-infusion of Ang 1-7 resulted in significant attenuations of myocyte
hypertrophy and interstitial fibrosis, without significant effects on blood pressure, but had no effect on AT1R or AT2R in cardiac tissue with or without co-infusion of Ang 1-7. Indicated an anti-remodeling role for Ang 1-7 in cardiac tissue maybe at least partially mediated through an Ang 1-7 receptor.
Trask et al. 2007
The enzyme participates in the cardiac processing of Ang II and Ang 1-7 is equivocal. Utilized the
Langendorff preparation to characterize the ACE2 pathway in isolated hearts from male normotensive SD [Tg(-)] and hypertensive [mRen2]27 [Tg(+)] rats.
During a 60-min recirculation period with 10 nM Ang II, the presence of Ang 1-7 was assessed in the cardiac effluent.
Ang 1-7 generation from Ang II was similar in both the normal and hypertensive hearts. ACE2 inhibition (MLN-4760, 1 µM) significantly reduced Ang 1-7 production in the Tg(+) rats, whereas the inhibitor had no significant effect in the Tg(-) rats. Predominant expression of cardiac ACE2 activity in the Tg(+) may be a compensatory response to the extensive cardiac remodeling.
Burchill et al. 2008
Assessed whether ACE2 plays a role in the cardiac remodeling that occurs in experimental acute kidney injury (AKI). SD rats had sham (control) or subtotal nephrectomy surgery (STNx). Control rats received vehicle, and STNx rats received the ACE inhibitor (ACEi) ramipril or vehicle orally after surgery. Rats with AKI had polyuria proteinuria and hypertension.
Cardiac structural changes were present and
characterized by LVH, fibrosis and increased cardiac brain natriuretic peptide (BNP) and cardiac ACE2 mRNA. Ramipril decreased blood pressure, LVH, fibrosis and BNP mRNA, and reduced in cardiac ACE2 activity. ACE2 may have a cardioprotective role in AKI, particularly since amelioration of adverse cardiac effects with ACE inhibition was associated with normalization of cardiac ACE2 activity.
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Wang et al. 2008
Coarctation of suprarenal abdominal aorta was reproduced in 8 week-old male SD rats and then randomized into 4 groups, including a sham group, a suprarenal aortic coarctation group, and suprarenal aortic coarctation with low and high-dose
Telmisartan treatment groups. Changes in both protein quantity and gene expressions of Ang II, ACE2 and ACE were determined.
Suprarenal abdominal aortic coarctation induced a significant increase in the plasma and myocardium AngII concentration and expressions of gene and protein of ACE and ACE2. Telmisartan further increased the concentration of AngII in plasma and myocardium in a dose-dependent manner, and induced a dose-dependent increase in both protein and gene expression of ACE2.
Lovren et al. 2008
Hypothesized that ACE2 is a novel target to limit endothelial dysfunction and atherosclerosis. To perform in vitro gain and loss of function
experiments in endothelial cells and evaluated in vivo angiogenesis and atherosclerosis in
apolipoprotein E-knockout mice treated with Ad-ACE2.
Overexpression of ACE2 in human endothelial cells stimulated endothelial cell migration and tube
formation, promoted capillary formation and neovessel maturation in vivo, reduced atherosclerosis in
apolipoprotein E-knockout mice and attenuated Ang II-induced reactive oxygen species production in part through decreasing the expression of p22phox.
Nakamura et al. 2008
Generated mice with targeted disruption of the ace2 gene and compared the cardiovascular function of ACE2-/y mice with that of their wild-type littermates.
ACE2-deficient mice were viable and fertile and lacked any gross structural abnormalities, displayed significantly enlarged hearts with impaired systolic and diastolic function.
The Ang II level was elevated in the plasma and heart of ACE2-/y mice. Pharmacological blockade of AT1R with candesartan attenuated the development of cardiac dysfunction in ACE2-/y mice. These results suggest that enhanced stimulation of AT1R may play a role in the development of cardiac dysfunction observed in ACE2-deficient mice.
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Der et al. 2008
Used a gene overexpression approach to investigate the role of ACE2 in cardiac function and remodeling after MI. Rats received an intracardiac injection of lentivirus containing ACE2 cDNA, followed by permanent coronary artery ligation (CAL) of the left anterior descending artery. Cardiac functions, viability, and pathophysiology were assessed.
Lenti-ACE2-treated CAL rats showed a 60% reduction in delayed contrast-enhanced LV volume after
gadodiamide injection, indicating early ischemic protection of myocardium by ACE2. Lenti-ACE2 rats demonstrated a complete rescue of cardiac output, a 41% rescue of ejection fraction, a 44% rescue in
contractility, a 37% rescue in motion, and a 53% rescue in LV anterior (infracted) wall thinning compared with control CAL rats.
Epelman et al. 2008
Developed a sensitive and specific assay to measure sACE2 activity in human plasma and screened a heterogeneous group of patients suspected of having clinical HF.
Increasing sACE2 plasma activity strongly correlated with a clinical diagnosis of HF, worsening left
ventricular ejection fraction, and increasing B-type natriuretic peptide levels. The sACE2 activity was increased in patients with both ischemic and
nonischemic cardiomyopathies and also in patients with clinical HF.
Garabelli et al. 2008
Determined the metabolism of angiotensins in wild-type (WT), ACE-/- and ACE2 null mice (ACE2-/-).
Ang II was converted almost exclusively to Ang 1-7 in the cardiac membranes of WT and ACE-/- strains, although generation of Ang 1-7 was greater in the ACE-/- mice. The ACE2 inhibitor MLN4760 significantly attenuated Ang II metabolism and the subsequent formation of Ang 1-7 in both strains. In the ACE2-/- hearts, Ang II metabolism and the generation of Ang 1-7 were significantly attenuated.
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Qin et al. 2008
Suprarenal abdominal aortic coarctation was performed to create the pressure overload induced left ventricular hypertrophy model in rats. Rats were randomly divided into: (A) normal control group;
(B) normal control group treated with atorvastatin;
(C) sham group; (D) atorvastatin given orally by gastric gavage for 4 weeks; (E) vehicle group. ACE2 mRNA and its protein expression were detected by real-time RT-PCR and Western blot.
ACE2 mRNA and its protein expression increase significantly in hypertrophic myocardium in rats;
atorvastatin can attenuate cardiac hypertrophy due to pressure overload in rats effectively, and part of this anti-hypertrophy effect may be attributed to decrease ACE2 mRNA and protein expression.
Guy et al. 2008
Revealed the functional expression of ACE2 in human cardiac myofibroblasts, cells that are essential to the maintenance of normal cardiac architecture and also play a key role in myocardial remodeling, and demonstrate the presence of ACE2 as an ectoenzyme and reveal that ACE2 undergoes phorbol-12-myristate-13-acetate-inducible
ectodomain shedding from the membrane.
ACE2 to be expressed constitutively in cardiac
myofibroblasts there were no detectable levels in either vascular smooth muscle cells or vascular endothelium, indicating that ACE2 expression is not ubiquitous.
Reported co-expression of ACE and ACE2 in human cardiac myofibroblasts and may therefore present a model primary system for study of the comparative cell biology of ACE2 and ACE and their potentially
opposing roles in myocardial remodeling.
Nadu et al. 2008
Investigated the expression of specific ECM proteins in cardiac hypertrophy induced by isoproterenol in TGR(A1-7)3292 rats. Additionally, changes in circulating and tissue RAS were analyzed. Left ventricles (LV) were used for quantification of collagen type I, III, and fibronectin.
TGR(A1-7)3292 presented lower Ang II levels and angiotensinogen expression and a higher ACE2 expression in LV. Isoproterenol treatment increased cardiac Ang II concentration only in normal rats, which was associated with an increase in ACE2 and a decrease in Mas expression.
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Gallagher et al. 2008
Cardiac ACE2 is elevated following treatment of coronary artery-ligated rats with AT1R blockers (ARBs). Cardiac myocytes and fibroblasts were isolated from neonatal rats to determine the
molecular mechanisms for the ACE2 up-regulation by ARB treatment.
Ang II significantly reduced ACE2 activity and down-regulated ACE2 mRNA in cardiac myocytes, effects blocked by the ARB losartan, indicating that Ang II regulates ACE2. Ang II also reduced ACE2 mRNA in cardiac fibroblasts. Ang II or Endothelin-1 (ET-1) activates extracellular signal-regulated kinase (ERK1/2) to reduce ACE2.
Hernández et al. 2008
To identify compounds that enhance ACE2 activity using a novel conformation-based rational drug discovery strategy and to evaluate whether such compounds reverse hypertension-induced pathophysiologies.
The xanthenone and resorcinolnaphthalein that enhanced ACE2 activity in a dose-dependent manner.
Acute in vivo administration of the xanthenone resulted in a dose-dependent transient and robust decrease in blood pressure. Chronic infusion of the xanthenone resulted in a modest decrease in the spontaneously
Acute in vivo administration of the xanthenone resulted in a dose-dependent transient and robust decrease in blood pressure. Chronic infusion of the xanthenone resulted in a modest decrease in the spontaneously