Effects Of Angiotensin-converting Enzyme 2 Research Articles

Untargeted metabolomics uncovers metabolic dysregulation and tissue sensitivity in ACE2 knockout mice

Angiotensin-converting enzyme 2 (ACE2) polymorphisms are associated with increased risk of type 2 diabetes mellitus (T2DM), obesity and dyslipidemia, which have been determined in various populations. Consistently, ACE2 knockout (ACE2 KO) mice display damaged energy metabolism in multiple tissues, especially the key metabolic tissues such as liver, skeletal muscle and epididymal white adipose tissue (eWAT) and show even more severe phenotype under high-fat diet (HFD) induced metabolic stress. However, the effects of ACE2 on global metabolomics profiling and the tissue sensitivity remain unclear. To understand how tissues independently and collectively respond to ACE2, we performed untargeted metabolomics in serum in ACE2 KO and control wild type (WT) mice both on normal diet (ND) and HFD, and in three key metabolic tissues (liver, skeletal muscle and eWAT) after HFD treatment. The results showed significant alterations in metabolic profiling in ACE2 KO mice. We identified 275 and 168 serum metabolites differing significantly between WT and ACE2 KO mice fed on ND and HFD, respectively. And the altered metabolites in the ACE2 KO group varied from 90 to 196 in liver, muscle and eWAT. The alterations in ND and HFD serum were most similar. Compared with WT mice, ACE2 KO mice showed an increase in N-phenylacetylglutamine (PAGln), methyl indole-3-acetate, 5-hydroxytryptophol, cholic acid, deoxycholic acid and 12(S)-HETE, while LPC (19:0) and LPE (16:1) decreased. Moreover, LPC (20:0), LPC (20:1) and PC (14:0e/6:0) were reduced in both ND and HFD serum, paralleling the decreases identified in HFD skeletal muscle. Interestingly, DL-tryptophan, indole and Gly-Phe decreased in both ND and HFD serum but were elevated in HFD liver of ACE2 KO mice. A low level of l-ergothioneine was observed among liver, muscle, and epididymal fat tissue of ACE2 KO mice. Pathway analysis demonstrated that different tissues exhibited different dysregulated metabolic pathways. In conclusion, these results revealed that ACE2 deficiency leads to an overall state of metabolic distress, which may provide a new insight into the underlying pathogenesis in metabolic disorders in both ACE2 KO mice and in patients with certain genetic variant of ACE2 gene.

Angiotensin‑converting enzyme‑2 improves diabetic nephropathy by targeting Smad7 for ubiquitin degradation.

Angiotensin‑converting enzyme 2(ACE2), an important component of the renin‑angiotensin system, protects against renal tubulointerstitial fibrosis, but its level of involvement in the mechanism of diabetic nephropathy(DN) currently remains unclear. Herein, the effects of ACE2 in DN and the associated mechanisms were investigated using serum and renal biopsy specimens from patients with DN and control participants, and human renal proximal tubular epithelial cells (HRPTEpiCs). The present study determined that the circulating concentration of ACE2 was high, but renal ACE2 expression was markedly lower, and there was abundant expression of Arkadia, an E3 ubiquitin ligase, in patients with DN. Invitro, ACE2 attenuated high‑glucose‑induced tubular epithelial to mesenchymal cell transition(EMT), which was demonstrated by increased expression of α‑SMA and loss of E‑cadherin expression, as demonstrated by western blot analysis and reverse transcription‑quantitative PCR. Adenovirus‑mediated ACE2 overexpression was also revealed to significantly inhibit Arkadia expression and alleviated high‑glucose‑induced EMT, while ACE2 inhibition had the opposite effects. Furthermore, western blot analysis demonstrated that ACE2‑alleviated EMT was associated with downregulated Arkadia and increased SMAD family member 7(Smad7) protein, followed by TGF‑β/Smad pathway inhibition in HRPTEpiCs. In conclusion, ACE2 is protective in DN, which may be due to the inhibition of Arkadia‑mediated Smad7 degradation, whereby TGF‑β/Smad‑mediated EMT is ameliorated in high‑glucose‑stimulated HRPTEpiCs.

Coronavirus Disease 2019 and Hypertension: The Role of Angiotensin-Converting Enzyme 2 and the Renin-Angiotensin System.

Hypertension emerged from early reports as a potential risk factor for worse outcomes for persons with coronavirus disease 2019 (COVID-19). Among the putative links between hypertension and COVID-19 is a key counter-regulatory component of the renin-angiotensin system (RAS): angiotensin-converting enzyme 2 (ACE2). ACE2 facilitates entry of severe acute respiratory syndrome coronavirus 2, the virus responsible for COVID-19, into host cells. Because RAS inhibitors have been suggested to increase ACE2 expression, health-care providers and patients have grappled with the decision of whether to discontinue these medications during the COVID-19 pandemic. However, experimental models of analogous viral pneumonias suggest RAS inhibitors may exert protective effects against acute lung injury. We review how RAS and ACE2 biology may affect outcomes in COVID-19 through pulmonary and other systemic effects. In addition, we briefly detail the data for and against continuation of RAS inhibitors in persons with COVID-19 and summarize the current consensus recommendations from select specialty organizations.

Renal denervation improves vascular endothelial dysfunction by inducing autophagy via AMPK/mTOR signaling activation in a rat model of type 2 diabetes mellitus with insulin resistance.

Recent clinical and animal studies have shown that renal denervation (RDN) improves insulin sensitivity and endothelial dysfunction. However, the specific mechanism remains incompletely understood. The purpose of this study is to investigate the effects of RDN on endothelial dysfunction of type 2 diabetes mellitus (T2DM) rat models with insulin resistance and to explore the underlying molecular mechanisms. Male Sprague-Dawley rats were fed with or without high-fat diet allocated in different groups, combined with low-dose streptozotocin which induces a rat model to develop T2DM with insulin resistance. RDN was conducted 1week after the rat models fully developed T2DM. The animals were sub-divided into four groups randomly: control group (CON, n = 6), diabetic group (T2DM, n = 6), diabetic with sham surgery group (Sham, n = 6) and diabetic with RDN group (RDN, n = 6). Rats in all groups were studied at baseline, both preoperatively and 4weeks after RDN, respectively. Western blot was used to detect the expression of angiotensin-converting enzyme 2 (ACE2) protein and the expression of autophagy-related proteins Beclin1, LC3 and p62 and autophagy signaling pathway AMPK/mTOR proteins and apoptosis-related protein caspase-3 in the aorta endothelial cells. In addition, the effects of ACE2 on autophagy of human umbilical vein insulin resistance endothelial cell culture in vitro were also studied. RDN decreased plasma and renal tissue norepinephrine levels. The Von Willebrand factor level was also decreased, while the plasma level of nitric oxide (NO) was significantly increased after RDN. Compared with the T2DM group and the Sham group, the endothelium-dependent and endothelium-independent diastolic function of the RDN group was improved significantly, the expression of Beclin1, LC3, ACE2 and eNOS proteins was higher, and the level of p62 protein was decreased. Furthermore, we found that RDN can activate the expression of p-AMPK and inhibit the expression of p-mTOR. In cell culture experiment, ACE2 activated p-AMPK and inhibited p-mTOR, thus promoting autophagy. RDN may not only increase the expression of ACE2 in the vascular endothelium, but also can via ACE2 activate p-AMPK and inhibit p-mTOR, thus promoting autophagy and improving endothelial dysfunction.

COVID-19 As An Endothelial Disease and Its Relationship to Vascular Endothelial Growth Factor (VEGF) and Iodide

Recently, attention around COVID-19 has shifted from respiratory symptoms to endothelial and other symptoms. Angiotensin-converting enzyme 2 (ACE2) is the entry receptor for SARS-CoV-2. SARS-CoV-2 is known to downregulate ACE2. Vascular endothelial growth factors (VEGFs) are considered a key factor in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). VEGF concentrations were observed to be significantly higher in both ICU and non-ICU COVID-19 patients than in healthy controls. Although VEGFs promote angiogenesis, neurogenesis and neuroprotection, they also induce vascular leakiness and permeability. ACE2 antagonizes VEGF-A to reduce vascular permeability during acute lung injury. Also in breast cancer cells, ACE2 downregulated the expression of VEGF-A. Since SARS-CoV-2 downregulates ACE2, it likely cancels the VEGF-A-antagonizing effect of ACE2, leading to upregulation of VEGF and thus increase of vascular permeability and aggravation of endothelial damage. VEGF might be upregulated also in normoxic conditions. Iodide is a VEGF modulator, increasing lymphatic system related VEGF-C/D expression while simultaneously suppressing endothelial cell related VEGF-A/B expression. It may thus revert VEGF-A/B increase caused by SARS-CoV-2 downregulation of ACE2. Protein kinase B (Akt) induces protective nitric oxide (NO) production in endothelial cells, including inhibition of thrombosis and platelet aggregation. In one study, excess iodide activated PI3K/Akt pathway. In addition, iodide was demonstrated to accumulate in upper airway secretions and inhibit viral infections by participating in a nonspecific, broad spectrum mechanism applicable to multiple types of viruses. Also, in a mouse model, iodide was observed to protect against ischemia-reperfusion injury, which may be relevant for e.g. COVID-19 associated acute limb ischemia. It has also been suggested that inorganic iodides act as antioxidants through an ancient direct mechanism. Recently, a computer simulation suggested that iodide may protect against SARS-CoV-2 directly by exhausting the electron donor property of the S protein by acting as a strong electron sink. There is initial evidence to warrant comprehensive clinical and basic research on the related pathways and possible benefits of iodide for treatment of COVID-19.

Angiotensin 1-7 alleviates aging-associated muscle weakness and bone loss, but is not associated with accelerated aging in ACE2-knockout mice.

The angiotensin-converting enzyme 2 (ACE2)-angiotensin 1-7 (A1-7)-A1-7 receptor (Mas) axis plays a protective role in the renin-angiotensin system (RAS). We recently found that ACE2 knockout (ACE2KO) mice exhibit earlier aging-associated muscle weakness, and that A1-7 alleviates muscle weakness in aging mice. In the present study, we investigated the role of the A1-7-Mas pathway in the effect of ACE2 on physiological aging. Male wild-type, ACE2KO, and Mas knockout (MasKO) mice were subjected to periodical grip strength measurement, followed by administration of A1-7 or vehicle for 4 weeks at 24 months of age. ACE2KO mice exhibited decreased grip strength after 6 months of age, while grip strength of MasKO mice was similar to that of wild-type mice. A1-7 improved grip strength in ACE2KO and wild-type mice, but not in MasKO mice. Muscle fibre size was smaller in ACE2KO mice than that in wild-type and MasKO mice, and increased with A1-7 in ACE2KO and WT mice, but not in MasKO mice. Centrally nucleated fibres (CNFs) and expression of the senescence-associated gene p16INK4a in skeletal muscles were enhanced only in ACE2KO mice and were not altered by A1-7. ACE2KO mice, but not MasKO mice, exhibited thinning of peripheral fat along with increased adipose expression of p16INK4a A1-7 significantly increased bone volume in wild-type and ACE2KO mice, but not in MasKO mice. Our findings suggest that the impact of ACE2 on physiological aging does not depend on the endogenous production of A1-7 by ACE2, while overactivation of the A1-7-Mas pathway could alleviate sarcopenia and osteoporosis in aged mice.

Abstract P195: Overexpression of ACE2 Boosts the Therapeutic Effects of Endothelial Progenitor Cells Derived Exosomes on Hemorrhagic Stroke

We have previously demonstrated that angiotensin converting enzyme 2 (ACE2) could boost the therapeutic effects of endothelial progenitor cell (EPCs) on ischemic stroke. Here, we tested whether ACE2 could enhance the effects of EPC derived exosomes (EXs) on intracerebral hemorrhagic stroke (ICH). A bolus of EPC-EXs or ACE2-EPC-EXs (1 x 10 11 EXs/100 ul) labeled with PKH26 was intravenously administrated to ICH mice (C57BL/6) 24 hrs after collagenase (VII-S; 0.075 U/0.5 μl) injection. ACE2 blocker, DCX 600 was used to verify the effects of ACE2. The neurological deficit score (NDS), hemorrhage volume, brain water content, and blood brain barrier (BBB) permeability were measured at day 24 hrs after injection. The levels of ACE2, inflammatory factors in the brain were measured. We found (table): 1) Both EPC-EXs and ACE2-EPC-EXs were dominantly uptaken by the brain endothelial cells, neurons and astrocytes in peri-infarct area; 2) ACE2-EPC-EXswere more effective than EPC-EXs in decreasing hemorrhage volume, brain edema, BBB permeability and improving NDS; 3) As compared to EPC-EXs, ACE2-EPC-EXs resulted in an up-regulation of ACE2, and more down-regulated TNF-α, NFкB, IκBα expressions. 4) DCX 600 could block the protective effects of ACE2-EPC-EXs. The data suggest that infusion of ACE2-EPC-EXsexhibited protective role for anti-inflammatory effect of ACE2 mediating TNF-α/NFкB in mice after ICH.

RhACE2 - playing an important role in inhibiting apoptosis induced by Ang II in HUVECs.

Background:Henoch-Schonlein purpura (HSP) is a common hemorrhagic disease, which manifests the inflammation in the body's most microvasculars. Angiotensin II (Ang II) can induce the damage and apoptosis of vascular endothelial cells while angiotensin converting enzyme 2 (ACE2) can antagonist the action of Ang II. However, the effect of ACE2 on Ang II-induced endothelial damage remains unknown.Objective:To evaluate the effect of recombinant human angiotensin converting enzyme 2 (rhACE2) on the Ang II-induced damage of human umbilical vein endothelial cells (HUVECs) and the release of inflammatory mediator in vitro.Methods:Cultured HUVECs were randomly divided into 6 groups: the control group, rhACE2 group, Ang II group, and Ang II+ rhACE2 groups (3 subgroups). The cell vitality, cell cycle, apoptosis rate of the HUVECs and the levels of reactive oxygen species (ROS), interleukin 8 (IL-8), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1) and lactate dehydrogenase (LDH) were measured, respectively.Results:Compared with the control group, the cell viability and the rate of S phase cells in Ang II group significantly decreased (P < .05) while the apoptosis percentage and the levels of ROS, IL-8, TNF-α, TGF-β1, and LDH in Ang II group significantly increased (P < .05). There were no significant differences between the control group and rhACE2 group. Compared with the Ang II group, the cell viability and the rate of S phase cells in Ang II+rhACE2 groups were higher (P < .05) and the apoptosis percentage, the level of ROS, IL-8, TNF-α, TGF-β1, LDH in Ang II+rhACE2 groups were lower (P < .05).Conclusions:Ang II can induce the apoptosis of HUVECs and the release of inflammatory mediator, while rhACE2 can inhibit the detrimental effects of Ang II. The results of this study suggest that rhACE2 has a protective effect on HSP, which is probably a new way for the prevention and treatment of HSP.

A12839 Angiotensin 1-7 functionally recovers aging-induced locomotive dysfunction, but is not associated with accelerated aging phenotypes in angiotensin-converting-enzyme 2 knockout mice

Objectives: The angiotensin-converting enzyme 2 (ACE2)-angitotensin 1-7 (A1-7)-A1-7 receptor (Mas) axis has been shown to have a protective role in the renin-angiotensin system (RAS). We recently found that ACE2 knockout (KO) mice exhibit earlier aging-associated muscle weakness, and A1-7 restores muscle weakness in aging mice. As ACE2 has a multifunctional role outside the RAS, we investigated the dependence on the A1-7-Mas pathway in the effect of ACE2 on physiological aging including locomotive dysfunction with muscle weakness and osteoporosis in mice. Methods: Wildtype (WT), ACE2KO, and MasKO mice were subjected to periodical grip strength measurement, followed by administration of A1–7 (100 ng/kg/min) or saline for 4 weeks with an osmotic pump in 24-month-old mice. Results: ACE2KO mice exhibited decreased grip strength compared with WT mice after 6 months of age, while MasKO mice had grip strength similar to WT mice during aging. A1-7 infusion at 24 months old improved grip strength with increased muscle size in WT and ACE2KO mice but not in MasKO mice. A1–7 significantly increased bone volume in WT and ACE2KO mice, but not in MasKO mice. Histological and gene expression analysis revealed that tissue aging including skin and adipose tissue was accelerated in aging ACE2KO mice, but not in MASKO mice, compared to WT mice. Conclusion: A1-7 improves muscle weakness and osteoporosis in aged mice via a Mas-dependent pathway. In contrast, the different aging phenotypes between ACEKO and MasKO mice suggest the A1-7-independent effect of ACE2 on senescence.

Abstract 037: Global ACE2 Over-Expression is Protective Against a Dysfunctional Brain-Gut-Lung Axis in Hypoxia-Induced Pulmonary Hypertension

Background and Objectives: Angiotensin converting enzyme 2 (ACE2), key enzyme of the vasoprotective axis of the renin angiotensin system, has been implicated in many pulmonary diseases including pulmonary hypertension (PH). Plasma levels of ACE2 in group-1 pulmonary hypertensive patients are decreased and activation of this enzyme by small molecule activators, overexpression or administration of recombinant ACE2, all have beneficial outcomes on PH. Furthermore, involvement of neuroinflammation and impaired brain-gut-lung axis have been proposed in PH. These observations have led us to propose that beneficial effect of ACE2 are, at least in part, due to attenuation of neuroinflammation and rebalancing of gut microbiota and improvement in pathology. Methods: ACE2 knock-in (ACE2KI) and wild-type mice (WT; C57BL/6) were subjected to hypoxia (10% FIO2) or room air for 4 weeks (n=8-10/group). Right ventricular systolic pressure (RVSP), and electrocardiography were performed, tissues examined by standard histological techniques, and stool collected for 16S rRNA analysis at 4 weeks. Results: Hypoxia-induced significantly increased RVSP in WT but not ACE2KI mice (20±1.6 vs 32±1.9, p&lt;0.001 and 24.3±1.5 vs 21±1.3mmHg, respectively). This was accompanied in WT, but not ACEKI, by ~5-fold increase in sympathetic activation (LF/HF; p&lt;0.001) and ~2-fold increase (p&lt;0.01) in microglia activation in the paraventricular nucleus (PVN) of the hypothalamus. There was increased fibrotic area (p&lt;0.01) and muscularis layer thickening (p&lt;0.001) and decreased villi length (p&lt;0.01) and goblet cells (p&lt;0.001) in the small intestine of WT but not ACE2KI mice following hypoxia. Finally, beta diversity of gut microbiome of WT, but not ACE2KI, mice was significantly altered by hypoxia (ANOSIM P=0.001). Conclusions: Microglial activation in PVN, sympathetic activation, gut pathology and altered gut microbiome are associated with hypoxia-induced PH. Global overexpression of ACE2 prevents all of these parameters. The involvement of organs other than lungs, and ACE2, present novel therapeutic potentials for PH.

Abstract 080: Role of High-mobility Group Box 1 in Angiotensin Converting Enzyme 2 -Mediated Cardioprotective Effects in a Mouse Model of Myocardial Ischemia

Backgrounds: High-mobility group box 1 (HMGB1) activates inflammation process, and its elevation is associated with adverse clinical outcomes in patients with myocardial infarction (MI). Previous studies have demonstrated that angiotensin-converting enzyme 2 (ACE2), a key member of vasoprotective axis of the renin angiotensin system, provides protection against MI. However, the involvement of HMGB1 in ACE2-mediated protective effects in cardiovascular diseases has yet to be elucidated. Thus, we hypothesized that the cardioprotective effects of ACE2 are, in part, by inhibition of cardiac HMGB1 and inflammatory pathways. Methods and results: Transgenic (TG) mice that ubiquitously overexpress ACE2 were used for the study. ACE2 levels in the hearts of TG mice were 58-times higher than wild type (WT). Mice were subjected to coronary artery ligation surgery and cardiac functions were evaluated by echocardiography 4 weeks post MI. MI resulted in a 53% decrease in ejection fraction (EF) and a 42% infarct area of left free wall. However, ACE2 TG mice showed 60% improvement of EF over WT mice. This was associated with a 55% decrease in the infarct area. Additionally, MI caused a three times increase in plasma HMGB1 levels which was associated with elevated macrophage infiltration and proinflammatory cytokine levels. In comparison to WT-MI mice, ACE2 overexpression attenuated the increase in plasma HMGB1 by 25% and reduced the proinflammatory cytokine levels to normal in the TG mice. To investigate the modulatory effects of ACE2 on HMGB1, adult cardiomyocytes incubated with an ACE2 activator (DIZE), a selective ACE2 inhibitor (C16), and a combination of DIZE and C16 were exposed to hypoxic condition for three hours. Hypoxia (H) caused 35% cell death and 44% increase in the HMGB1 level (H: 23.6± 0.8 vs normoxia: 16.4± 1.2, ng/ml). DIZE significantly attenuated the cell death (2% cell death) and 37% decrease in HMGB1 levels (DIZE+H: 14.8± 2.5 ng/ml), which was blocked by a selective ACE2 inhibitor (C16+DIZE+H: 20.8± 2.9ng/ml). Conclusions: The protective effect of ACE2 against ischemia is correlated with decrease in HMGB1 and its downstream pro-inflammatory cascades. Thus, HMGB1 could be useful target for the development of novel treatment for MI.

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

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

Angiotensin-Converting Enzyme 2 Inhibits Apoptosis of Pulmonary Endothelial Cells During Acute Lung Injury Through Suppressing MiR-4262

Background/Aims: Angiotensin converting enzyme 2 (ACE2) treatment suppresses the severity of acute lung injury (ALI). The effects of ACE2 in ALI have been shown to not only result from its antagonizing hydrolyzing angiotensin II (AngII), which is responsible for reduction in the vascular tension and pulmonary accumulation of inflammatory cells, but also result from a role of ACE2 in suppressing the ALI-induced apoptosis of pulmonary endothelial cells (PECs). Nevertheless, the underlying mechanisms of the role of ACE2 on PEC apoptosis are not completely understood. Methods: Here, we used a bleomycin-induced mouse model for ALI that has been published in our previous studies. We analyzed the mRNA and protein levels of an anti-apoptotic protein Bcl-2 in the ALI-mice that have been treated w/o ACE2. We analyzed miR-4262 levels in the mouse lung in these mice. Bcl-2-targeting miRNAs were predicted using bioinformatics algorithms and a luciferase reporter assay was applied to examine the effects of miR-4262 on the Bcl-2 protein translation upon their binding to 3'-UTR of Bcl-2 mRNA. Adeno-associated viruses carrying either miR-4262 mimics or antisense were injected into ALI-mice without ACE2, and their effects on the apoptosis in mouse lung cells were analyzed by Western blot. Results: ACE2 inhibited the ALI-induced apoptosis of pulmonary cells in vivo partially through upregulation of Bcl-2 protein, but not Bcl-2 mRNA. ACE2 appeared to significantly suppress the upregulation of miR-4262 in mouse lung after ALI. MiR-4262 was found to target 3'-UTR of Bcl-2 mRNA to inhibit its protein translation in PECs. In vivo administration of antisense of miR-4262 decreased apoptosis of pulmonary cells and severity of the ALI in mice. Conclusion: ACE2-induced suppression of miR-4262 partially contribute to the inhibition of the PEC apoptosis after ALI through Bcl-2. MiR-4262 may be a novel promising treatment target for ALI and ARDS.

Gene transfer of angiotensin converting enzyme 2 to the paraventricular nucleus improves attenuated nitric oxide mechanism in rats with chronic heart failure

In the present study, we investigated the effects of angiotensin converting enzyme 2 (ACE2) gene transfer on nitric oxide (NO) mechanism contributed to the elevated sympathoexcitation in the rats with coronary ligation model of chronic heart failure (CHF). Adenovirus vectors encoding either ACE2 (AdACE2) or EGFP (AdEGFP) were transfered into the paraventricular nucleus (PVN) in vivo. 3 days after application of AdACE2, the expression of ACE2 in the PVN was confirmed by immunohistochemistry. In alpha‐chloralose and urethane anesthetized rats, AdACE2 significantly improved the attenuated renal sympathetic nerve activity (RSNA), blood pressure (BP) and heart rate (HR) responses to neuronal NO synthase (nNOS) inhibitor L‐NMMA in the rats with CHF (RSNA: 29±5% vs 10±1%, P&lt;0.05) compared to CHF‐AdEGFP group. AdACE2 transfection significantly normalized the decreased nNOS protein levels (Δ30±4%) in the PVN in CHF rats. Furthermore, neuronal NG‐108 cells were stimulated with AdACE2 or AdEGFP in a dose‐dependent manner. nNOS protein expression increased in a dose‐dependent manner after AdACE2 transfection. The highest dose showed an approximately 50% increase in nNOS protein expression compared to the control dose. We conclude that the up‐regulation of ACE2 by gene transfer significantly stimulates nNOS production and the effects of ACE2 on the NO mechanism in the PVN may play an important role in the altered balance and tone of sympathetic outflow in the CHF condition.

Angiotensin converting enzyme-2 confers endothelial protection and attenuates atherosclerosis

The endothelium plays a central role in the maintenance of vascular homeostasis. One of the main effectors of endothelial dysfunction is ANG II, and pharmacological approaches to limit ANG II bioactivity remain the cornerstone of cardiovascular therapeutics. Angiotensin converting enzyme-2 (ACE2) has been identified as a critical negative modulator of ANG II bioactivity, counterbalancing the effects of ACE in determining net tissue ANG II levels; however, the role of ACE2 in the vasculature remains unknown. In the present study, we hypothesized that ACE2 is a novel target to limit endothelial dysfunction and atherosclerosis. To this aim, we performed 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 AdACE2. ACE2-deficient mice exhibited impaired endothelium-dependent relaxation. Overexpression of ACE2 in human endothelial cells stimulated endothelial cell migration and tube formation, and limited monocyte and cellular adhesion molecule expression; effects that were reversed in ACE2 gene silenced and endothelial cells isolated from ACE2-deficient animals. ACE2 attenuated ANG II-induced reactive oxygen species production in part through decreasing the expression of p22phox. The effects of ACE2 on endothelial activation were attenuated by pharmacological blockade of ANG-(1-7) with A779. ACE2 promoted capillary formation and neovessel maturation in vivo and reduced atherosclerosis in apolipoprotein E-knockout mice These data indicate that ACE2, in an ANG-(1-7)-dependent fashion, functions to improve endothelial homeostasis via a mechanism that may involve attenuation of NADPHox-induced reactive oxygen species production. ACE2-based treatment approaches may be a novel approach to limit aberrant vascular responses and atherothrombosis.