Angiotensin-converting enzyme 2 alleviates liver fibrosis through the renin-angiotensin system

The present letter to the editor is related to the study titled‘Angiotensin-converting enzyme 2 improves liver fibrosis in mice by regulating autophagy of hepatic stellate cells’.Angiotensin-converting enzyme 2 can alleviate liver fibrosis by regulating autophagy of hepatic stellate cells and affecting the renin-angiotensin system.

Hepatic angiotensin-converting enzyme 2 expression in metabolic dysfunction-associated steatotic liver disease and in patients with fatal COVID-19

BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD),characterised by hepatic lipid accumulation,causes inflammation and oxidative stress accompanied by cell damage and fibrosis.Liver injury(LI)is also frequently reported in patients hospitalised with coronavirus disease 2019(COVID-19),while preexisting MASLD increases the risk of LI and the development of COVID-19-associated cholangiopathy.Mechanisms of injury at the cellular level remain unclear,but it may be significant that severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)which causes COVID-19,uses angiotensin-converting expression enzyme 2(ACE2),a key regulator of the‘anti-inflammatory’arm of the renin-angiotensin system,for viral attachment and host cell invasion.AIM To determine if hepatic ACE2 levels are altered during progression of MASLD and in patients who died with severe COVID-19.METHODS ACE2 protein levels and localisation,and histological fibrosis and lipid droplet accumulation as markers of MASLD were determined in formalin-fixed liver tissue sections across the MASLD pathological spectrum(isolated hepatocellular steatosis,metabolic dysfunction-associated steatohepatitis(MASH)+/-fibrosis,end-stage cirrhosis)and in post-mortem tissues from patients who had died with severe COVID-19,using ACE2 immunohistochemistry and haematoxylin and eosin and picrosirius red staining of total collagen and lipid droplet areas,followed by quantification using machine learning-based image pixel classifiers.RESULTS ACE2 staining is primarily intracellular and concentrated in the cytoplasm of centrilobular hepatocytes and apical membranes of bile duct cholangiocytes.Strikingly,ACE2 protein levels are elevated in non-fibrotic MASH compared to healthy controls but not in the progression to MASH with fibrosis and in cirrhosis.ACE2 protein levels and histological fibrosis are not associated,but ACE2 and liver lipid droplet content are significantly correlated across the MASLD spectrum.Hepatic ACE2 levels are also increased in COVID-19 patients,especially those showing evidence of LI,but are not correlated with the presence of SARS-CoV-2 virus in the liver.However,there is a clear association between the hepatic lipid droplet content and the presence of the virus,suggesting a possible functional link.CONCLUSION Hepatic ACE2 levels were elevated in nonfibrotic MASH and COVID-19 patients with LI,while lipid accumulation may promote intra-hepatic SARS-CoV-2 replication,accelerating MASLD progression and COVID-19-mediated liver damage.

Role of renin-angiotensin system/angiotensin converting enzyme-2 mechanism and enhanced COVID-19 susceptibility in type 2 diabetes mellitus

Coronavirus disease 2019(COVID-19)is a disease that caused a global pandemic and is caused by infection of severe acute respiratory syndrome coronavirus 2 virus.It has affected over 768 million people worldwide,resulting in approx-imately 6900000 deaths.High-risk groups,identified by the Centers for Disease Control and Prevention,include individuals with conditions like type 2 diabetes mellitus(T2DM),obesity,chronic lung disease,serious heart conditions,and chronic kidney disease.Research indicates that those with T2DM face a hei-ghtened susceptibility to COVID-19 and increased mortality compared to non-diabetic individuals.Examining the renin-angiotensin system(RAS),a vital regulator of blood pressure and pulmonary stability,reveals the significance of the angiotensin-converting enzyme(ACE)and ACE2 enzymes.ACE converts angiotensin-I to the vasoconstrictor angiotensin-II,while ACE2 counters this by converting angiotensin-II to angiotensin 1-7,a vasodilator.Reduced ACE2 exp-ression,common in diabetes,intensifies RAS activity,contributing to conditions like inflammation and fibrosis.Although ACE inhibitors and angiotensin receptor blockers can be therapeutically beneficial by increasing ACE2 levels,concerns arise regarding the potential elevation of ACE2 receptors on cell membranes,potentially facilitating COVID-19 entry.This review explored the role of the RAS/ACE2 mechanism in amplifying severe acute respiratory syndrome cor-onavirus 2 infection and associated complications in T2DM.Potential treatment strategies,including recombinant human ACE2 therapy,broad-spectrum antiviral drugs,and epigenetic signature detection,are discussed as promising avenues in the battle against this pandemic.

Angiotensin-converting enzyme 2 improves liver fibrosis in mice by regulating autophagy of hepatic stellate cells

BACKGROUND Liver fibrosis is the common pathological process associated with the occurrence and development of various chronic liver diseases.At present,there is still a lack of effective prevention and treatment methods in clinical practice.Hepatic stellate cell(HSC)plays a key role in liver fibrogenesis.In recent years,the study of liver fibrosis targeting HSC autophagy has become a hot spot in this research field.Angiotensin-converting enzyme 2(ACE2)is a key negative regulator of reninangiotensin system,and its specific molecular mechanism on autophagy and liver fibrosis needs to be further explored.AIM To investigate the effect of ACE2 on hepatic fibrosis in mice by regulating HSC autophagy through the Adenosine monophosphate activates protein kinases(AMPK)/mammalian target of rapamycin(mTOR)pathway.METHODS Overexpression of ACE2 in a mouse liver fibrosis model was induced by injection of liver-specific recombinant adeno-associated virus ACE2 vector(rAAV2/8-ACE2).The degree of liver fibrosis was assessed by histopathological staining and the biomarkers in mouse serum were measured by Luminex multifactor analysis.The number of apoptotic HSCs was assessed by terminal deoxynucleoitidyl transferase-mediated dUTP nick-end labeling(TUNEL)and immunofluorescence staining.Transmission electron microscopy was used to identify the changes in the number of HSC autophagosomes.The effect of ACE2 overexpression on Wu Y et al.ACE2 improves liver fibrosis through autophagy WJG https://www.wjgnet.com 4976 September 7,2023 Volume 29 Issue 33 autophagy-related proteins was evaluated by multicolor immunofluorescence staining.The expression of autophagy-related indicators and AMPK pathway-related proteins was measured by western blotting.RESULTS A mouse model of liver fibrosis was successfully established after 8 wk of intraperitoneal injection of carbon tetrachloride(CCl4).rAAV2/8-ACE2 administration reduced collagen deposition and alleviated the degree of liver fibrosis in mice.The serum levels of platelet-derived growth factor,angiopoietin-2,vascular endothelial growth factor and angiotensin II were decreased,while the levels of interleukin(IL)-10 and angiotensin-(1-7)were increased in the rAAV2/8-ACE2 group.In addition,the expression of alpha-smooth muscle actin,fibronectin,and CD31 was down-regulated in the rAAV2/8-ACE2 group.TUNEL and immunofluorescence staining showed that rAAV2/8-ACE2 injection increased HSC apoptosis.Moreover,rAAV2/8-ACE2 injection notably decreased the number of autophagosomes and the expression of autophagy-related proteins(LC3I,LC3II,Beclin-1),and affected the expression of AMPK pathway-related proteins(AMPK,p-AMPK,p-mTOR).CONCLUSION ACE2 overexpression can inhibit HSC activation and promote cell apoptosis by regulating HSC autophagy through the AMPK/mTOR pathway,thereby alleviating liver fibrosis and hepatic sinusoidal remodeling.

Impact of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers on the mortality in sepsis: A meta-analysis

BACKGROUND The effect of angiotensin-converting enzyme inhibitors(ACEIs)or angiotensin receptor blockers(ARBs)on the mortality of patients with sepsis is not well characterized.AIM To elucidate the association between prior ACEI or ARB exposure and mortality in sepsis.METHODS The PubMed,EMBASE,Web of Science,and Cochrane Library databases were searched for all studies of premorbid ACEI or ARB use and sepsis mortality until November 302019.Two reviewers independently assessed,selected,and ab-stracted data from studies reporting ACEIs or ARBs,sepsis,and mortality.The primary extracted data consisted of premorbid ACEI or ARB exposure,mortality,and general patient data.Two reviewers independently assessed the risk of bias and quality of evidence.RESULTS A total of six studies comprising 281238 patients with sepsis,including 49799 cases with premorbid ACEI or ARB exposure were eligible for analysis.Pre-morbid ACEIs or ARBs exposure decreased the 30-d mortality in patients with sepsis.Moreover,the use of ACEIs or ARBs was associated with approximately a 6%decreased risk of 30-d mortality.CONCLUSION The results of this systematic review suggest that ACEI or ARB exposure prior to sepsis may be associated with reduced mortality.Further high-quality cohort studies and molecular mechanism experiments are required to confirm our results.

Angiotensin-converting Enzyme Gene Insertion/Deletion Polymorphism in Children with Henoch-Schonlein Purpua Nephritis

This study investigated the relationship between angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism and the occurrence, severity, prognosis of HSPN. The polymorphism of ACE gene in 103 HSPN cases and 100 healthy children was studied by using the polymerase chain reactions (PCR). Its relation to the clinical manifestation, pathological classification and prognosis of HSPN was analyzed accordingly. The results showed that: (1) there was a significantly higher frequency for DD genotype in HSPN children (P<0.01); (2) DD genotype was more frequently seen in HSPN children with gross hematuria and massive proteinuria (P<0.05), while DI genotype was more common in HSPN children group with renal insufficiency (P<0.05); (3) although mesangial proliferative lesion was most frequently observed in 21 biopsied HSPN children, and DD genotype frequency was still higher in children with severe pathology (Class Ⅲ Ⅳ); (4)II genotype was significantly frequent in HSPN children with complete remission in the follow-up of 32 HSPN children. It was concluded that the deletion allele of ACE gene might play a role, at least to some extent, in the occurrence, deterioration and progression in juvenile HSPN.

Serum angiotensin-converting enzyme level for evaluating significant fibrosis in chronic hepatitis B

AIM To evaluate the diagnostic performance of angiotensinconverting enzyme(ACE)on significant liver fibrosis in patients with chronic hepatitis B(CHB). METHODS In total,100 patients with CHB who underwent liver biopsy in our hospital were enrolled,and 70 patients except for 30 patients with hypertension,fatty liver or habitual alcoholic consumption were analyzed.We compared histological liver fibrosis and serum ACE levels and evaluated the predictive potential to diagnose significant liver fibrosis by comparison with several biochemical marker-based indexes such as the aspartate aminotransferase(AST)-to-platelet ratio index(APRI),the fibrosis index based on four factors(FIB-4),the Mac-2 binding protein glycosylation isomer(M2BPGi)level and the number of platelets(Plt). RESULTS Serum ACE levels showed moderately positive correlation with liver fibrotic stages(R2=0.181).Patients with significant,advanced fibrosis and cirrhosis(F2-4)had significantly higher serum ACE levels than those with early-stage fibrosis and cirrhosis(F0-1).For significant fibrosis(≥F2),the 12.8 U/L cut-off value of ACE showed 91.7%sensitivity and 75.0%specificity.The receiver-operating characteristic(ROC)curves analysis revealed that the area under the curve(AUC)value of ACE was 0.871,which was higher than that of APRI,FIB-4,M2BPGi and Plt. CONCLUSION The serum ACE level could be a novel noninvasive,easy,accurate,and inexpensive marker of significant fibrosis stage in patients with CHB.

Effects of angiotensin-converting enzyme inhibitor and angiotensin Ⅱ receptor blocker on one-year outcomes of patients with atrial fibrillation: insights from a multicenter registry study in China

Objective To evaluate the effect of angiotensin-converting enzyme inhibitor(ACEI)/angiotensin Ⅱ receptor blocker(ARB)therapy on the prognosis of patients with atrial fibrillation(AF).Methods A total of 1,991 AF patients from the AF registry were divided into two groups according to whether they were treated with ACEI/ARB at recruitment.Baseline characteristics were carefully collected and analyzed.Logistic regression was utilized to identify the predictors of ACEI/ARB therapy.The primary endpoint was all-cause mortality,while the secondary endpoints included cardiovascular mortality,stroke and major adverse events(MAEs)during the one-year follow-up period.Univariable and multivariable Cox regression were performed to identify the association between ACEI/ARB therapy and the one-year outcomes.Results In total,759 AF patients(38.1%)were treated with ACEI/ARB.Compared with AF patients without ACEI/ARB therapy,patients treated with ACEI/ARB tended to be older and had a higher rate of permanent AF,hypertension,diabetes mellitus,heart failure(HF),left ventricular ejection fraction(LVEF)<40%,coronary artery disease(CAD),prior myocardial infarction(MI),left ventricular hypertrophy,tobacco use and concomitant medications(all P<0.05).Hypertension,HF,LVEF<40%,CAD,prior MI and tobacco use were determined to be predictors of ACEI/ARB treatment.Multivariable analysis showed that ACEI/ARB therapy was associated with a significantly lower risk of one-year all-cause mortality[hazard ratio(HR)(95%CI):0.682(0.527-0.882),P=0.003],cardiovascular mortality[HR(95%CI):0.713(0.514-0.988),P=0.042]and MAEs[HR(95%CI):0.698(0.568-0.859),P=0.001].The association between ACEI/ARB therapy and reduced mortality was consistent in the subgroup analysis.Conclusions In patients with AF,ACEI/ARB was related to significantly reduced one-year all-cause mortality,cardiovascular mortality and MAEs despite the high burden of cardiovascular comorbidities.

Interferon augments the anti-fibrotic activity of an angiotensin-converting enzyme inhibitor in patients with refractory chronic hepatitis C

AIM： To evaluate the effect of combination treatment with the interferon （IFN） and angiotensin-converting enzyme inhibitor （ACE-Ⅰ） on several fibrotic indices in patients with refractory chronic hepatitis C （CHC）. METHODS： Perindopril （an ACE-Ⅰ; 4 mg/d） and/or natural IFN （3 MU/L; 3 times a week） were administered for 12 mo to refractory CHC patients, and several indices of serum fibrosis markers were analyzed. RESULTS： ACE-Ⅰ decreased the serum fibrosis markers, whereas single treatment with IFN did not exert these inhibitory effects. However, IFN significantly augmented the effects of ACE-Ⅰ, and the combination treatment exerted the most potent inhibitory effects. The serum levels of alanine transaminase and HCV-RNA were not significantly different between the groups, whereas the plasma level of transforming growth factor-β was significantly attenuated almost in parallel with suppression of the serum fibrosis markers. CONCLUSION： The combination therapy of an ACE-Ⅰand IFN may have a diverse effect on disease progression in patients with CHC refractory to IFN therapy through its anti-fibrotic effect.

Role of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in cryoballoon ablation outcomes for paroxysmal atrial fibrillation

BACKGROUND Cryoballoon ablation(CBA)is recommended for patients with paroxysmal atrial fibrillation(AF)refractory to antiarrhythmic drugs.However,only 80%of patients benefit from initial CBA.There is growing evidence that pretreatment with angiotensin-converting enzyme inhibitors(ACEIs)and angiotensin receptor blockers(ARBs)decreases the recurrence of AF postablation,particularly in nonparoxysmal AF undergoing radiofrequency ablation.The role of ACEIs and ARBs in patients with paroxysmal AF in CBA remains unknown.We decided to investigate the role of ACEIs and ARBs in preventing the recurrence of atrial arrhythmia(AA)following CBA for paroxysmal AF.AIM To investigate the role of ACEIs and ARBs in preventing recurrence of AA following CBA for paroxysmal AF.METHODS We followed 103 patients(age 60.6±9.1 years,29%women)with paroxysmal AF undergoing CBA 1-year post procedure.Recurrence was assessed by documented AA on electrocardiogram or any form of long-term cardiac rhythm monitoring.A multivariable Cox proportional hazard model was used to assess if ACEI or ARB treatment predicted the risk of AA recurrence.RESULTS After a 1-year follow-up,19(18.4%)participants developed recurrence of AA.Use of ACEI or ARB therapy was noted in the study population.Patients on ACEI/ARB had a greater prevalence of hypertension and coronary artery disease.On a multivariate model adjusted for baseline demographics and risk factors for AF,ACEI or ARB therapy did not prevent recurrence of AA following CBA(P=0.72).Similarly,on Kaplan–Meier analysis pretreatment with ACEI/ARB did not predict the time to first recurrence of AA(P=0.2173).CONCLUSION In our study population,preablation treatment with an ACEI or ARB had no influence on the recurrence of AA following CBA for paroxysmal AF.

Hyperkalemia of Angiotensin-converting Enzyme Inhibitors or Angiotensin Receptor Blockers in Hemodialysis: A Meta-analysis

The safety of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) used in hemodialysis (HD) patients was evaluated.Medline,Embase,the Cochrane Library,some databases of clinical trial registries,grey literatures,other reference lists of eligible articles and review articles for the randomized clinical trials (RCTs) on comparison of ACEIs/ARBs or placebo in HD patients were retrieved.RCTs reporting the risk of hyperkalemia by using ACEIs/ARBs in HD patients were selected.Eight articles met the eligibility criteria and were subjected to meta-analysis by using the Cochrane Collaboration’s RevMan 4.2 software package.The results showed that there was no significant difference in hyperkalemia in HD patients between ACEIs or ARBs group and control group (ACEIs vs.control:RD=0.03,95% CI=-0.13?0.18,Z=0.34,P=0.73;ARBs vs.control:RD=-0.02,95% CI=-0.07?0.03,Z=0.75,P=0.45).However,there was no significant difference in the serum potassium between ACEIs or ARBs group and control group in HD patients (ACEIs vs.control:WMD=0.10,95% CI=0.06?0.15,Z=4.64,P<0.00001;ARBs vs.control:WMD=-0.24,95% CI=-0.37--0.11,Z=3.58,P=0.0003).The use of ACEIs or ARBs could not cause an increased risk of hyperkalemia in HD patients,however the serum potassium could be increased with use of ACEIs in HD patients.Therefore the serum potassium concentration should still be closely monitored when ACEIs are taken during the maintenance HD.

Increasing angiotensin-converting enzyme(ACE)2/ACE axes ratio alleviates early pulmonary vascular remodeling in a porcine model of acute pulmonary embolism with cardiac arrest

BACKGROUND:Acute pulmonary embolism(APE)with cardiac arrest(CA)is characterized by high mortality in emergency due to pulmonary arterial hypertension(PAH).This study aims to determine whether early pulmonary artery remodeling occurs in PAH caused by massive APE with CA and the protective effects of increasing angiotensin-converting enzyme(ACE)2-angiotensin(Ang)(1-7)-Mas receptor axis and ACE-Ang II-Ang II type 1 receptor(AT1)axis(ACE2/ACE axes)ratio on pulmonary artery lesion after return of spontaneous circulation(ROSC).METHODS:To establish a porcine massive APE with CA model,autologous thrombus was injected into the external jugular vein until mean arterial pressure dropped below 30 mmHg(1 mmHg=0.133 kPa).Cardiopulmonary resuscitation and thrombolysis were delivered to regain spontaneous circulation.Pigs were divided into four groups of five pigs each:control group,APE-CA group,ROSC-saline group,and ROSC-captopril group,to examine the endothelial pathological changes and expression of ACE2/ACE axes in pulmonary artery with or without captopril.RESULTS:Histological analysis of samples from the APE-CA and ROSC-saline groups showed that pulmonary arterioles were almost completely occluded by accumulated endothelial cells.Western blotting analysis revealed a decrease in the pulmonary arterial ACE2/ACE axes ratio and increases in angiopoietin-2/angiopoietin-1 ratio and expression of vascular endothelial growth factor(VEGF)in the APE-CA group compared with the control group.Captopril significantly suppressed the activation of angiopoietin-2/angiopoietin-1 and VEGF in plexiform lesions formed by proliferative endothelial cells after ROSC.Captopril also alleviated endothelial cell apoptosis by increasing the B-cell lymphoma-2(Bcl-2)/Bcl-2-associated X(Bax)ratio and decreasing cleaved caspase-3 expression.CONCLUSION:Increasing the ACE2/ACE axes ratio may ameliorate pulmonary arterial remodeling by inhibiting the apoptosis and proliferation of endothelial cells after ROSC induced by APE.

A new angiotensin-converting enzyme inhibitor from Peperomia pellucida(L.) Kunth

Objective:To isolate,identify,and evaluate a new angiotensin-converting enzyme inhibitor from Peperomia pellucida(L.)Kunth herbs.Methods:A dried sample of Peperomia pellucida herb was successively macerated with n-hexane and ethyl acetate.The ethyl acetate extract solution was evaporated to obtain the crude extract.Vacuum liquid column chromatography and thin layer chromatography were performed to obtain two pure compounds.Then,both compounds were elucidated and identified using the spectroscopic method.Angiotensin-converting enzyme inhibitory activity studies of both compounds were determined using angiotensin-converting enzyme kit WST-1 with spectrophotometer microplate reader 96-well at 450 nm wavelength.Results:Two bioactive compounds were successfully isolated from Peperomia pellucida herb,including a new compound of 2,3,5-trimethoxy-9-(12,14,15-trimethoxybenzyl)-1 H-indene and pellucidin A.Both compounds demonstrated angiotensin-converting enzyme inhibitory activity,with IC50 values of 72 μM(27.95 μg/mL)and 1 1μM(4.4 μg/mL),respectively.Conclusions:In the present study,two active angiotensin-converting enzyme inhibitors were successfully isolated and purified from Peperomia pellucida which is used as an antihypertensive in traditional medicine,and support its use as an angiotensin-converting enzyme-inhibiting drug.

Effects of angiotensin receptor blockers and angiotensin-converting enzyme inhibitors on COVID-19

BACKGROUND The World Health Organization reported that 28637952 people worldwide had been infected with severe acute respiratory syndrome coronavirus 2,the causative agent of coronavirus disease 2019(COVID-19),by September 13.AIM The aim was to investigate whether long-term use of renin-angiotensin-aldosterone system(RAAS)inhibitors for the treatment of hypertension aggravates the performance of COVID-19 patients with hypertension.METHODS This was a retrospective analysis of lung computed tomography(CT)data and laboratory values of COVID-19 patients with hypertension who were admitted to Huoshenshan Hospital,Wuhan,Hubei Province,between February 18 and March 31,2020.Patients were divided into two groups.Group A included 19 people who were long-term users of RAAS inhibitors for hypertension;and group B included 28 people who were randomly selected from the database and matched with group A by age,sex,basic diseases,and long-term use of other antihypertensive drugs.All patients underwent a series of CT and laboratory tests.We compared the most severe CT images of the two groups and the laboratory examination results within 2 d of the corresponding CT images.RESULTS The time until the most severe CT images from the onset of COVID-19 was 30.37±14.25 d group A and 26.50±11.97 d in group B.The difference between the two groups was not significant(t=1.01,P=0.32).There were no significant differences in blood laboratory values,C-reactive protein,markers of cardiac injury,liver function,or kidney function between the two groups.There was no significant difference in the appearance of the CT images between the two groups.The semiquantitative scores of each involved lobe were 11.84±5.88 in group A and 10.36±6.04 group B.The difference was not significantly different(t=0.84,P=0.41).CONCLUSION Chest CT is an important imaging tool to monitor the characteristics of COVID-19 and the degree of lung injury.Chronic use of RAAS inhibitors is not related to the severity of COVID-19,and it does not worsen the clinical process.

Angiotensin-converting enzyme gene polymorphism and middle cerebral artery stenosis in a Chinese Han population

The angiotensin-converting enzyme gene is a candidate gene of stroke. The present study involved 62 healthy volunteers and 148 patients with middle cerebral artery stenosis as confirmed by brain color ultrasound from a Han population in North China, and determined the peripheral blood angiotensin-converting enzyme genotype using PCR-restriction fragment length polymorphism analysis. The results showed that the frequencies of the DD genotype and D allele were increased in patients with middle cerebral artery stenosis, but the difference was not statistically significant compared with healthy controls. The findings of this study on the relationship between stroke genes and middle cerebral artery stenosis indicate no significant correlation between the frequencies of the DO genotype and D allele of angiotensin-converting enzyme and middle cerebral artery stenosis in this Han population from North China. In the future, studies will be carried out to investigate correlations between multiple stroke candidate gene synergy and middle cerebral artery stenosis to provide a foundation for the development of gene therapy.

Angiotensin-converting enzyme 2 connects COVID-19 with cancer and cancer immunotherapy

The coronavirus disease 2019(COVID-19)pandemic caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has resulted in more than two million deaths.Underlying diseases,including cancer,are high-risk factors for severe COVID-19 outcomes.Angiotensin-converting enzyme 2(ACE2),as a SARS-CoV-2 host cell receptor,plays a crucial role in SARS-CoV-2 invading human cells.ACE2 also has significant associations with cancer.Recent studies showed that ACE2 was inversely correlated with the activities of multiple oncogenic pathways and tumor progression phenotypes,and was positively correlated with antitumor immune response and survival prognosis in diverse cancers,suggesting a potential protective role of ACE2 in cancer progression.Positive expression of ACE2 is also correlated with programmed death-ligand 1(PD-L1)in cancer.The positive associations of ACE2 expression with antitumor immune signatures and PD-L1 expression indicate that ACE2 expression is a positive predictor for the response to immune checkpoint inhibitors(ICIs).This was evidenced in multiple cancer cohorts treated with ICIs.Thus,ACE2 may build potential connections between COVID-19 and cancer and cancer immunotherapy.The potential connections suggest that ACE2 inhibitors may not be a good option for treating COVID-19 patients with cancer,particularly in cancer patients who are receiving immunotherapy.Furthermore,the relationships between ACE2,COVID-19,and cancer are worth confirming by more experimental and clinical data,considering that many cancer patients are at high risk for COVID-19.

New perspectives on angiotensin-converting enzyme 2 and its related diseases

Since the worldwide outbreak of coronavirus disease 2019,angiotensin-converting enzyme 2(ACE2)has received widespread attention as the cell receptor of the severe acute respiratory syndrome coronavirus 2 virus.At the same time,as a key enzyme in the renin-angiotensin-system,ACE2 is considered to be an endogenous negative regulator of vasoconstriction,proliferation,fibrosis,and proinflammation caused by the ACE-angiotensin II-angiotensin type 1 receptor axis.ACE2 is now implicated as being closely connected to diabetes,cardiovascular,kidney,and lung diseases,and so on.This review covers the available information on the host factors regulating ACE2 and discusses its role in a variety of pathophysiological conditions in animal models and humans.

Plasma Levels of Angiotensin-Converting Enzymes 1 and 2 and <i>AGTR</i>2 (T1247G and A5235G) Gene Polymorphisms Are Associated to Breast Cancer Progression

Background: Breast cancer is the most common type of cancer among women. Diagnosed and treated timely, patients may have good prognostics. In Brazil, in 2012, the estimate of new cases was 52,680 and the number of registered deaths in 2012 was 12,852. The Renin-Angiotensin System (RAS) is known for its role in arterial hypertension and in other cardiovascular diseases. Angiotensin-Converting Enzyme 2 (ACE2) is the key to Ang-(1-7) formation, and counterbalances the ACE1/AngII/AGTR1 axis actions. RAS components have complex interactions with different tissues and their actions are not restricted to the cardiovascular system. Recently, the RAS has been associated with different types of cancers and in particular with gynecological cancers. Objectives: Our aim is to investigate possible associations between allelic distribution of two genetic polymorphisms in the AGTR2 receptor with ACEs 1 and 2 plasma levels among women with breast cancer. Patients and Methods: Patients with breast cancer were genotyped for two polymorphisms of the AGTR2 (T1247G and A5235G). Genotyping assays (TaqMan) were performed with genomic DNA extracted from blood cells. ACEs plasma level measurements were conducted in women from the breast-cancer group (N = 53). ACEs were measured in the plasma of these patients using ELISA kits. Results: SNPs genotype distribution is correlated with ACEs plasma levels. ACEs plasma levels are also correlated with clinical variables and ACE2 high levels are associated with better prognostics. Conclusions: Changes in circulating levels of ECA1/AngII ECA2/ Ang-(1-7) determine the magnitude of the inflammatory response that an individual can trigger and the variation in ACE 1 and 2 plasma level measurements in the blood of breast cancer patients suggests an association with the process of mammary carcinogenesis. Thus, the RAS may be associated with the process of mammary carcinogenesis by both genotypic variations of RAS components and by circulating levels of ACEs.

AT1a Receptor Has Interacted with Angiotensin-converting Enzymes 2 mRNA Expression in Mouse Brainstem

Objectives To examine in vivo interactions between angiotensin Ⅱ （Ang Ⅱ ） AT1 a receptor （AT1 aR）, angiotensin-converting enzymes （ACE） and ACE2 using small hairpin RNA （shRNA） gene-silencing methods in mice brainstem nucleus tractus solitarius （NTS）. Methods C57BL mice （n = 8 ） were used as animal model. Method of micro-injection in the nucleus of NTS was adopted. After ten days, mice were killed and their brain tissue were fixed and sectioned. The expression levels of AT1 aR, ACE and ACE2 mRNA at both sides of NTS were examined by in situ hybridization. Based on compared t-test, the changing for mRNA expression was examined. Results After the expression of ATlaR mRNA was significantly inhibited （61.6% ± 6.8% ） by ATlaR-shRNA, it was associated with decreases in ACE2 mRNA expression from （ 1.05 ± 0. 12） μCi/mg to （0. 74 ± 0.09 ） μCi/mg （ 29.0% ± 14. 5% , P 〈 0. 01 ） on the same side of the brainstem. ACE mRNA expression was consistent at both sides （ 0. 50 μCi/mg ± 0. 09μCi/mg and 0. 53 μCi/mg ± 0. 08 μCi/mg）, with insignificant difference （ P 〉 0. 05 ）. Conclusions The gene silencing result showed that there were interactions between brainstem AT1 aR and ACE2. ACE mRNA expression was not altered by RNA interference treatment at AT1 aR.

Interaction and Relationship Between Angiotensin ConvertingEnzyme Gene and Environmental Factors Predisposing toEssential Hypertension in MongolianPopulation of China

Objective To investigate the association of specific functional gene ACE (I/D) variants of the renin-angiotensin system with essential hypertension (EH) and interaction between ACE (I/D) gene and risk factors for EH in a genetically homogenous Mongolia rural population of China. Methods Individuals (n=1099) were recruited from general population of Kezuohouqi Banner in Inner Mongolian Autonomous Region. Results The association was found between ACE genotype DD plus ID and EH, with an interaction between ACE genotype DD plus ID and cigarette smoking in an additive model. Cigarette smoking index and ACE gene showed a low exposure-gene (LEG) effect on EH, with interaction indices from 7.10 to 1.16. Interaction between ACE genotype DD plus ID and alcohol drinking on EH appeared an additive model. Alcohol drinking index and ACE gene showed a low exposure-gene (LEG) effect on EH, with interaction indices from 1.66 to 1.09. BMI and ACE gene showed a low exposure-gene (LEG) effect on EH, with interaction indices from 6.15 to 2.49. Interactions between ACE genotype and WHR on EH showed a multiplicative model. In a short, there was an interaction between ACE gene and cigarette smoking, alcohol drinking and BMI on EH, especially in a low dose-exposure effect Conclusion It is important for individuals who carry ACE D allele gene to prevent EH, and furthermore, to prevent and control coronary heart disease, in a view of population-based prevention.