Angiotensin-converting Enzyme Deletion Research Articles

Influence of genetic polymorphisms in vascular endothelial-related genes on the clinical outcome of axitinib in patients with metastatic renal cell carcinoma

ABSTRACT Objective Axitinib is an oral multi-target tyrosine kinase inhibitor used for the treatment of renal cell carcinoma (RCC). Because of the severe adverse events (AEs) associated with axitinib, patients often need dose reductions or discontinue its use, highlighting the need for effective biomarkers to assess efficacy and/or AEs. The aim of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in genes involved in the pharmacodynamic action of axitinib and clinical prognosis and AEs in metastatic RCC (mRCC) patients. Methods This study included 80 mRCC patients treated with first-, second-, or third-line axitinib (5 mg orally twice daily). Clinical parameters and genetic polymorphisms were examined in 75 cases (53 males and 22 females). We assessed three SNPs in each of three candidate genes namely, angiotensin-converting enzyme (ACE), nitric oxide synthase 3 (NOS3), and angiotensin II receptor type 1 (AT1R), all of which are involved in axitinib effects on vascular endothelial function. Results Axitinib-treated patients carrying the ACE deletion allele suffered more frequently from hand-foot syndrome and a deterioration in kidney function (p = .045 and p = 0.005, respectively) whereas those carrying the NOS3 G allele suffered more frequently from proteinuria and multiple AEs (p = .025 and p = 0.036, respectively). Conclusions Our study found that the ACE deletion allele and the NOS3 G allele are associated with increased AEs.

Manipulation of components of the renin angiotensin system in renal proximal tubules fails to alter atherosclerosis in hypercholesterolemic mice.

Whole body manipulation of the renin-angiotensin system (RAS) consistently exerts profound effects on experimental atherosclerosis development. A deficit in the literature has been a lack of attention to the effects of sex. Also, based on data with gene-deleted mice, the site of RAS activity that influences lesion formation is at an unknown distant location. Since angiotensin (AngII) concentrations are high in kidney and the major components of the RAS are present in renal proximal tubule cells (PTCs), this study evaluated the role of the RAS in PTCs in atherosclerosis development. Mice with an LDL receptor -/- background were fed Western diet to induce hypercholesterolemia and atherosclerosis. We first demonstrated the role of AT1 receptor antagonism on atherosclerosis in both sexes. Losartan, an AngII type 1 (AT1) receptor blocker, had greater blood pressure-lowering effects in females than males, but equivalent effects between sexes in reducing atherosclerotic lesion size. To determine the roles of renal AT1a receptor and angiotensin-converting enzyme (ACE), either component was deleted in PTCs after weaning using a tamoxifen-inducible Cre expressed under the control of an Ndrg1 promoter. Despite profound deletion of AT1a receptor or ACE in PTCs, the absence of either protein did not influence development of atherosclerosis in either sex. Conversely, mice expressing human angiotensinogen and renin in PTCs or expressing human angiotensinogen in liver but human renin in PTCs did not change atherosclerotic lesion size in male mice. Whole-body AT1R inhibition reduced atherosclerosis equivalently in both male and female mice; however, PTC-specific manipulation of the RAS components had no effects on hypercholesterolemia-induced atherosclerosis.

Abstract 448: Angiotensin-converting Enzyme In Renal Proximal Tubular Cells Does Not Affect Atherosclerosis In Male And Female Hypercholesterolemic Mice

Objective: Angiotensin-converting enzyme (ACE) generates Angiotensin II (AngII), the bioactive angiotensin peptide that contributes to atherosclerosis. ACE is present in proximal tubular cells (PTCs), and AngII concentrations are higher in kidney than in plasma. The purpose of this study was to determine whether ACE in PTCs contributed to atherosclerosis in both male and female mice. Approach and Results: ACE f/f x Ndrg1-Cre ERT2 -/- (PTC-ACE+/+) and ACE f/f x Ndrg1-Cre ERT2+/- (PTC-ACE -/-) mice were generated by breeding female ACE floxed mice (ACE f/f) xNdrg1-Cre ERT2-/- and male ACE f/f x Ndrg1-Cre ERT2+/- transgenic mice. Both male and female littermates in an LDL receptor -/- background were used to study atherosclerosis. PTC-ACE+/+ and PTC-ACE-/- littermates were administered with of tamoxifen (150 mg/kg/day) for 5 consecutive days at the age of 4-6 weeks to ACE deletion in PTCs. Two weeks after the last injection of tamoxifen, mice were fed a Western diet for 12 weeks. Blood pressure was measured using a tail-cuff system during the study. Systolic blood pressure was not different between the two genotypes (PTC-ACE+/+ vs -/-: 124±3 vs 121±2 mmHg in male, P=0.3; and 114±3 vs 115±3 mm Hg in female, P=0.9). All mice were hypercholesterolemic, and plasma cholesterol concentrations were not different between the two genotypes (PTC-ACE +/+ vs -/-: 1524±108 vs 1680±66 mg/dl in male, P=0.2; 1175±47 vs 1210±55 mg/dl in female, P=0.6). ACE mRNA abundance measured by qPCR of ACE in kidneys was less in the PTC-ACE-/- mice (PTC-ACE +/+ vs -/-: 1.03±0.11 vs 0.33±0.04 in male, P=0.001; 1.14±0.21 vs 0.64±0.09 in female, P=0.02). In PTC-ACE-/- mice, immunostaining of ACE in kidney sections showed that ACE was deleted in S1 and S2 PTCs, but remained in S3 of the outer medulla. Atherosclerosis was measured using an en face method. PTC-ACE+/+ and PTC-ACE-/- mice had comparable atherosclerotic lesion size in the ascending and aortic arch regions (PTC-ACE+/+ vs -/-: 11.4±1.4% vs 13.4±1.7% in male, P=0.4; 14.9±2.2% vs 15.7±3.7% in female, P=1.0). Conclusion: PTC-specific ACE deficiency did not affect atherosclerosis in hypercholesterolemic mice.

Angiotensin-Converting Enzyme Genotype-Specific Immune Response Contributes to the Susceptibility of COVID-19: A Nested Case-Control Study.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19), which has resulted in a global pandemic. Methodology: We used a two-step polymerase chain reaction to detect the ACE genotype and ELISA kits to detect the cytokine factor. We also used proteomics to identify the immune pathway related to the ACE protein expression. Result: In this study, we found that the angiotensin-converting enzyme (ACE) deletion polymorphism was associated with the susceptibility to COVID-19 in a risk-dependent manner among the Chinese population. D/D genotype distributions were higher in the COVID-19 disease group than in the control group (D/D odds ratio is 3.87 for mild (p value < 0.0001), 2.59 for moderate (p value = 0.0002), and 4.05 for severe symptoms (p value < 0.0001), logic regression analysis. Moreover, genotype-specific cytokine storms and immune responses were found enriched in patients with the ACE deletion polymorphism, suggesting the contribution to the susceptibility to COVID-19. Finally, we identified the immune pathway such as the complement system related to the ACE protein expression of patients by lung and plasma proteomics. Conclusion: Our results demonstrated that it is very important to consider gene polymorphisms in the population to discover a host-based COVID-19 vaccine and drug design for preventive and precision medicine.

Abstract P160: Deficiency Of Angiotensin-converting Enzyme In Renal Proximal Convoluted Tubules Does Not Attenuate Atherosclerosis In Mice

Objective: Angiotensin-converting enzyme (ACE) is the enzyme to generate Angiotensin II (AngII), an important contributor to atherosclerosis. ACE is present in all 3 segments (S1, S2, and S3) of proximal tubular cells (PTCs), and AngII concentrations are higher in kidney than in plasma. The purpose of this study was to determine whether ACE in PTCs contributes to atherosclerosis in mice. Approach and Results: Female ACE floxed mice and male Ndrg1-Cre ERT2 +/- transgenic mice were bred to generate ACE f/f x Ndrg1-Cre ERT2 -/- (PTC-ACE +/+ ) and ACE f/f x Ndrg1-Cre ERT2 +/- (PTC-ACE -/- ) littermates. Male PTC-ACE +/+ (n=7) and PTC-ACE -/- (n=10) littermates in an LDL receptor -/- background were used for atherosclerosis study. After Cre genotyping using tail DNA, mice (both Cre ERT2 -/- and Cre ERT2 +/- ) were injected with 150 mg/kg/day of tamoxifen for 5 consecutive days at the age of 4-6 weeks. Two weeks after the last injection of tamoxifen, mice were fed a Western diet (Envigo, Diet #TD.88137) for 12 weeks to induce hypercholesterolemia. Blood pressure was measured using a tail-cuff system. No difference of blood pressure was detected between the two genotypes (PTC-ACE +/+ vs. PTC-ACE -/- : 126 ± 4 vs. 125 ± 3 mmHg; P = 0.763). All study mice were hypercholesterolemic, but plasma cholesterol concentrations were not different between the two genotypes (PTC-ACE +/+ vs. PTC-ACE -/- : 1376 ± 119 vs. 1543 ± 93 mg/dl; P = 0.28). PTC-specific deletion of ACE was confirmed after termination using immunostaining of ACE. In mice with Ndrg1-Cre ERT2 transgene, immunostaining of ACE in kidney section showed an absence of ACE in S1 and S2 of PTCs, but ACE protein in S3 remained. Deletion of ACE in S1 and S2 of PTCs did not change hypercholesterolemia-induced atherosclerosis in the ascending and aortic arch regions (PTC-ACE +/+ vs. PTC-ACE -/- : 9.6 ± 0.9% vs. 7.0 ± 1.9%; P = 0.13 by Mann-Whitney Rank Sum Test), as measured using an en face method. Conclusion: ACE deficiency in S1 and S2 of renal proximal tubular cells had no effect on atherosclerosis in hypercholesterolemic mice. Since ACE is more abundant in S3 than in S1 and S2 of PTCs, it would be important to determine the role of ACE in the S3 segment.

Ethnic Prevalence of Angiotensin-Converting Enzyme Deletion (D) Polymorphism and COVID-19 Risk: Rationale for Use of Angiotensin-Converting Enzyme Inhibitors/Angiotensin Receptor Blockers

RationaleHypertension, obesity and diabetes are major risk factors associated with morbidities underlying COVID-19 infections. Regression analysis correlated presence of ACE insertion/deletion (I/D) polymorphism to COVID-19 incidence and mortality. Furthermore, COVID-19 prevalence correlated to allele frequency of angiotensin-converting enzyme (ACE) deletion (D) polymorphism within the European population.ObjectiveHomozygous ACE deletion polymorphism is associated with increase in ACE and angiotensin II (Ang-II), sustained levels can result in inflammation, fibrosis and organ damage. The ACE DD polymorphism is also associated with hypertension, acute respiratory distress and diabetic nephropathy, all considered high risk for COVID-19 infection and outcomes. The study objective was to describe a biological framework associating ethnic prevalence of ACE deletion polymorphism to COVID-19 comorbidities providing rationale for therapeutic utility of ACE-I/ARBs to improve outcomes.Method and ResultsThe Allele Frequency Database (ALFRED) was queried for frequency of rs4646994 representing ACE I/D polymorphism. In a total of 349 worldwide population samples, frequency of ACE D allele was higher in European, Asian, and Africans cohorts. In the USA, the frequency of ACE D allele was higher in non-Hispanic Black compared with non-Hispanic White and Mexican Americans.ConclusionCOVID-19 binding mediated reduction/inactivation of ACE-II can increase ACE/Ang-II signalling pathway and related pathologies. The presence of ACE DD polymorphism with COVID-19 infection likely augments ACE/Ang-II activities, increasing severity of COVID-19 morbidities and impacts outcomes. Thus, ethnic prevalence of ACE DD polymorphism can explain in part the severity of COVID-19 morbidity providing rationale for the use of ACE-I/ARBs to improve outcomes.

Different effects of the deletion of angiotensin converting enzyme 2 and chronic activation of the renin-angiotensin system on muscle weakness in middle-aged mice.

Inhibition of the renin-angiotensin system (RAS) has been shown to alleviate muscle atrophy both under pathological conditions and during physiological aging. We recently reported that the deletion of angiotensin converting enzyme 2 (ACE2), which converts Angiotensin II to Angiotensin-(1-7) in mice, leads to the early manifestation of aging-associated muscle weakness along with the increased expression of p16INK4a, a senescence-associated gene, and increased central nuclei in the tibialis anterior (TA) muscle in middle age. As ACE2 is multifunctional and functions beyond its role in the RAS, we investigated whether activation of the RAS primarily contributes to muscle weakness in ACE2 knockout (KO) mice by comparing these mice to Tsukuba hypertensive (TH) mice that overproduce human angiotensin II. The grip strength of young (6 months) and middle-aged (15 months) TH mice was consistently lower than that of wild-type mice at the same ages. Middle-aged TH mice were continuously lean with extremely reduced adiposity. Central nuclei in the gastrocnemius (GM) muscle were increased in ACE2KO mice, while no apparent morphological change was observed in the GM muscles of TH mice. Increased expression of p16INK4a along with alterations in the expression of several sarcopenia-associated genes were observed in the GM muscles of ACE2KO mice but not TH mice. These findings suggest that chronic overactivation of the RAS does not primarily contribute to the early aging phenotypes of skeletal muscle in ACE2KO mice.

ACE insertion/deletion genetic polymorphism, serum ACE levels and high dietary salt intake influence the risk of obesity development among the Saudi adult population

Introduction:Angiotensin-converting enzyme (ACE), which contributes to adipocyte growth, differentiation and function, has recently been linked with both salt metabolism and obesity development. Therefore, this study has aimed to investigate the putative relationship between ACE genetic polymorphism, serum ACE levels and salt consumption on the risk of developing obesity in the Saudi population.Materials and methods:ACE genotype status of 267 adult Saudi volunteers (124 obese and 143 non-obese) was correlated with their serum ACE activity and dietary salt intake amounts.Results:Obesity was more prevalent in deletion-deletion genotype individuals (p<0.03), under dominant, co-dominant and monoallelic conditions (p<0.04). Deletion allele corresponds to serum ACE activity in obese patients (p<0.05). The amount of salt intake (<6 g/d) was significantly associated with obesity and particularly high in deletion-deletion and insertion-deletion genotype carriers (p<0.001). STITCH analysis underlined interactions of the ACE protein with sodium molecule, REN, ACE2, KNG1 and AGTR1 in a biological network.Conclusions:Our findings suggest the positive association between ACE deletion genotype, serum ACE activity and sodium intake with risk of obesity development in the Saudi population.

A clinical dose of angiotensin-converting enzyme (ACE) inhibitor and heterozygous ACE deletion exacerbate Alzheimer's disease pathology in mice

Inhibition of angiotensin-converting enzyme (ACE) is a strategy used worldwide for managing hypertension. In addition to converting angiotensin I to angiotensin II, ACE also converts neurotoxic β-amyloid protein 42 (Aβ42) to Aβ40. Because of its neurotoxicity, Aβ42 is believed to play a causative role in the development of Alzheimer's disease (AD), whereas Aβ40 has neuroprotective effects against Aβ42 aggregation and also against metal-induced oxidative damage. Whether ACE inhibition enhances Aβ42 aggregation or impairs human cognitive ability are very important issues for preventing AD onset and for optimal hypertension management. In an 8-year longitudinal study, we found here that the mean intelligence quotient of male, but not female, hypertensive patients taking ACE inhibitors declined more rapidly than that of others taking no ACE inhibitors. Moreover, the sera of all AD patients exhibited a decrease in Aβ42-to-Aβ40-converting activity compared with sera from age-matched healthy individuals. Using human amyloid precursor protein transgenic mice, we found that a clinical dose of an ACE inhibitor was sufficient to increase brain amyloid deposition. We also generated human amyloid precursor protein/ACE+/- mice and found that a decrease in ACE levels promoted Aβ42 deposition and increased the number of apoptotic neurons. These results suggest that inhibition of ACE activity is a risk factor for impaired human cognition and for triggering AD onset.

Relationship between Angiotensin Converting Enzyme Gene Polymorphism and Carotid Atherosclerotic Plaque: A Study Based on Vessel Wall Magnetic Resonance Imaging

Objective To investigate the relationship between angiotensin converting enzyme(ACE) gene polymorphism and carotid plaque composition,vessel wall morphology,and clinical symptoms based on vessel wall magnetic resonance imaging. Methods Totally 75 hypertensive patients(75 internal carotid artery plaques) with maximum plaque thickness≥1.5 mm,according to the ACE insertion(I) or deletion(D) gene polymorphism,were divided into ACE 2 genotype group(n=37) and ACE ID/DD genotype group(n=38). The influences of plaque composition,vessel wall morphology,clinical symptoms,and use of ACE inhibitor or angiotensin receptor blocker(ACEI/ARB) on vessel wall morphology were analyzed. Results Compared with ACE 2 genotype group,the ACE ID/DD genotype group had significantly higher incidence of ischemic stroke(Χ2=3.921,P=0.048). The plaque composition and vessel wall morphology showed no significant difference between these two groups. Inside ACE ID/DD genotype group,the carotid remodeling index was significantly lower in users of ACEI/ARB than non-users of ACEI/ARB(1.85±0.60 vs. 2.48±0.40;t=3.854,P=0.001).Conclusion In primary hypertension,ACE ID/DD genotype may be associated with carotid atherosclerotic plaque.

Identification of genetic markers for skill and athleticism in sub-elite Australian football players: a pilot study.

Natural genetic variation contributes towards athletic performance in various strength/power and endurance based sports. To date, no studies have explored the genetic predisposition towards skill and athletic performance in Australian Football (AF) players. The present pilot study recruited 30 sub-elite AF players who completed tests of endurance, power and technical skill. Specific polymorphisms in nine genes were screened, and assessed for a possible association with athletic and skill traits. Statistical analysis using generalized linear models identified a number of polymorphisms predictive of endurance and technical skill. The angiotensin-converting enzyme (ACE), normally responsible for regulation of body fluid volume, was a significant factor in predicting 'all round' athletic performance and skill. Specifically, the deletion allele (DD) of ACE was identified as a predictor for AF power (P≤0.008), endurance (P=0.001) and skill assessments (P≤0.003). In addition, polymorphisms in the brain-derived neurotrophic factor, D2 dopamine receptor, and catechol-O-methyltransferase genes were also shown to contribute to kicking skill outcomes (P≤0.044). This is the first study to implicate the ACE deletion allele for a multidimensional sport in such a way. Further, the results from this study have identified several new candidate genes in predicting athletic and technical skill outcomes.

Angiotensin-Converting Enzyme in Smooth Muscle Cells Promotes Atherosclerosis-Brief Report.

Angiotensin-converting enzyme (ACE) is present in many cell types of atherosclerotic lesions. This study determined whether ACE activity in endothelial and smooth muscle cells (SMCs), 2 major resident cell types of the aorta, contributes to hypercholesterolemia-induced atherosclerosis. All study mice were in low-density lipoprotein receptor(-/-) background. To determine the contribution of ACE on endothelial cells to atherosclerosis, female ACE floxed mice were bred to male Tie2-Cre transgenic mice. Endothelial cell-specific deletion of ACE significantly decreased serum ACE activity, but had no effect on systolic blood pressure and atherosclerosis. Because ACE protein is present on SMCs, the most abundant cell type of the aorta, we then determined whether ACE on SMCs contributes to atherosclerosis. ACE was depleted from SMCs by breeding female ACE floxed mice with male SM22-Cre transgenic mice. SMC-specific deficiency of ACE did not affect ACE activity in serum, but ablated its presence and activity in the aortic media. Although SMC-specific deficiency of ACE had no effect on systolic blood pressure, it significantly attenuated hypercholesterolemia-induced atherosclerosis in both male and female mice. These studies provide direct evidence that ACE derived from endothelial cells does not play a critical role in atherosclerosis. Rather, SMC-derived ACE contributes to atherosclerosis, independent of circulating ACE activity and blood pressure.

Deletion of angiotensin-converting enzyme 2 exacerbates renal inflammation and injury in apolipoprotein E-deficient mice through modulation of the nephrin and TNF-alpha-TNFRSF1A signaling.

BackgroundThe renin-angiotensin system (RAS) has been implicated in atherosclerotic lesions and progression to chronic kidney diseases. We examined regulatory roles of angiotensin-converting enzyme 2 (ACE2) in the apolipoprotein E (ApoE) knockout (KO) kidneys.MethodsThe 3-month-old wild-type, ApoEKO, ACE2KO and ApoE/ACE2 double-KO (DKO) mice in a C57BL/6 background were used. The ApoEKO mice were randomized to daily deliver either Ang II (1.5 mg/kg) and/or human recombinant ACE2 (rhACE2; 2 mg/kg) for 2 weeks. We examined changes in pro-inflammatory cytokines, renal ultrastructure, and pathological signaling in mouse kidneys.ResultsDownregulation of ACE2 and nephrin levels was observed in ApoEKO kidneys. Genetic ACE2 deletion resulted in modest elevations in systolic blood pressure levels and Ang II type 1 receptor expression and reduced nephrin expression in kidneys of the ApoE/ACE2 DKO mice with a decrease in renal Ang-(1-7) levels. These changes were linked with marked increases in renal superoxide generation, NADPH oxidase (NOX) 4 and proinflammatory factors levels, including interleukin (IL)-1beta, IL-6, IL-17A, RANTES, ICAM-1, Tumor necrosis factor-alpha (TNF-alpha) and TNFRSF1A. Renal dysfunction and ultrastructure injury were aggravated in the ApoE/ACE2 DKO mice and Ang II-infused ApoEKO mice with increased plasma levels of creatinine, blood urea nitrogen and enhanced levels of Ang II in plasma and kidneys. The Ang II-mediated reductions of renal ACE2 and nephrin levels in ApoEKO mice were remarkably rescued by rhACE2 supplementation, along with augmentation of renal Ang-(1-7) levels. More importantly, rhACE2 treatment significantly reversed Ang II-induced renal inflammation, superoxide generation, kidney dysfunction and adverse renal injury in ApoEKO mice with suppression of the NOX4 and TNF-alpha-TNFRSF1A signaling. However, rhACE2 had no effect on renal NOX2 and TNFRSF1B expression and circulating lipid levels.ConclusionsACE2 deficiency exacerbates kidney inflammation, oxidative stress and adverse renal injury in the ApoE-mutant mice through modulation of the nephrin, NOX4 and TNF-alpha-TNFRSF1A signaling. While rhACE2 supplementation alleviates inflammation, renal dysfunction and glomerulus injury in the ApoE-mutant mice associated with upregulations of Ang-(1-7) levels and nephrin expression and suppression of the TNF-alpha-TNFRSF1A signaling. Strategies aimed at enhancing the ACE2/Ang-(1-7) actions may have important therapeutic potential for atherosclerotic renal injury and kidney diseases.

Association of ACE insertion or deletion polymorphisms with the risk of coronary restenosis after percutaneous coronary intervention: A meta-analysis.

Previous case-control studies on the relationship between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphisms and coronary restenosis did not reach the same conclusion. In the present study, we aimed to further evaluate the relationship between the ACE gene I/D polymorphisms and coronary restenosis, after percutaneous coronary intervention (PCI). By searching PubMed, EMBase, the Chinese Biomedical Literature Database and Wanfang database, we selected 16 case-control studies related to ACE gene I/D polymorphism and coronary restenosis after PCI. To test for heterogeneity in each study, we utilized the Q-test and I(2) test. To merge the odds ratio (OR) and 95% CI, we utilized the random effects model during the analyses. The present study included 4693 subjects: 1241 patients with coronary restenosis and 3452 without coronary restenosis. By meta-analysis, we found there was significant association of ACE gene I/D polymorphism with coronary restenosis (D allele versus I allele: OR = 1.92; 95% CI (1.40-2.43); p < 0.001). A subgroup analysis, by stratification according to ethnicity, also showed that this association was found not only in the Caucasian population ((D allele versus I allele: OR = 1.94; 95% CI (1.38-2.80); p < 0.001)), but also in the Asian population ((D allele versus I allele: OR = 1.83; 95% CI (1.05-3.20); p = 0.03)). After stratification according to age, we found that the D allele carriers have a higher risk for development of coronary restenosis in subjects < 60 years old (OR = 2.13; 95% CI: 1.40-3.24; p = 0.0004); while in the subjects ⩾ 60 years old, the association was present with bordering significance (OR = 1.48; 95%CI: 0.98-2.25; p = 0.06). The present study suggested that the ACE gene I/D polymorphism was associated with coronary restenosis, regardless of age and ethnicity.

Angiotensin II receptor blockade or deletion of vascular endothelial ACE does not prevent vascular dysfunction and remodeling in 20-HETE-dependent hypertension.

Increased vascular 20-HETE is associated with hypertension and activation of the renin-angiotensin system (RAS) through induction of vascular angiotensin-converting enzyme (ACE) expression. Cyp4a12tg mice, whose Cyp4a12-20-HETE synthase expression is under the control of a tetracycline (doxycycline, DOX) promoter, were used to assess the contribution of ACE/RAS to microvascular remodeling in 20-HETE-dependent hypertension. Treatment of Cyp4a12tg mice with DOX increased systolic blood pressure (SBP; 136 ± 2 vs. 102 ± 1 mmHg; P < 0.05), and this increase was prevented by administration of 20-HEDGE, lisinopril, or losartan. DOX-induced hypertension was associated with microvascular dysfunction and remodeling of preglomerular microvessels, which was prevented by 20-HEDGE, a 20-HETE antagonist, yet only lessened, but not prevented, by lisinopril or losartan. In ACE 3/3 mice, which lack vascular endothelial ACE, administration of 5α-dihydrotestosterone (DHT), a known inducer of 20-HETE production, increased SBP; however, the increase was about 50% of that in wild-type (WT) mice (151 ± 1 vs. 126 ± 1 mmHg). Losartan and 20-HEDGE prevented the DHT-induced increase in SBP in WT and ACE 3/3 mice. DHT treatment increased 20-HETE production and microvascular remodeling in WT and ACE 3/3 mice; however, remodeling was attenuated in the ACE 3/3 mice as opposed to WT mice (15.83 ± 1.11 vs. 22.17 ± 0.92 μm; P < 0.05). 20-HEDGE prevented microvascular remodeling in WT and ACE 3/3 mice, while losartan had no effect on microvascular remodeling in ACE 3/3. Taken together, these results suggest that RAS contributes to 20-HETE-mediated microvascular remodeling in hypertension and that 20-HETE-driven microvascular remodeling independent of blood pressure elevation does not fully rely on ACE activity in the vascular endothelium.

Deletion of angiotensin-converting enzyme 2 promotes the development of atherosclerosis and arterial neointima formation

Angiotensin-converting enzyme 2 (ACE2) is known as a negative regulator of the renin-angiotensin system. We aimed to determine the roles of ACE2 on the development of vascular diseases. Using two diversely different models of vascular diseases, hyperlipidaemia-induced atherosclerosis in apolipoprotein E knockout (KO) mice and mechanical injury-induced arterial neointimal hyperplasia in C57Bl6 mice, we examined whether ACE2 deficiency could affect formation of the vascular lesions. ACE2 deficiency resulted in significantly larger vascular lesions in both aortic atherosclerotic plaques and arterial neointima formation, compared with ACE2(+) control. These ACE2-deficient vascular lesions exhibited enhanced accumulation of macrophages into the lesions and proliferation of vascular smooth muscle cells (VSMCs), accompanied with increased angiotensin-II (Ang-II) levels and enhanced expression of vascular inflammation-related genes, including vascular cell adhesion molecule (VCAM)-1, monocyte chemoattractant protein (MCP)-1, and matrix metalloproteinase (MMP)9 in aorta/artery tissues. Primary bone marrow macrophages and aortic VSMCs isolated from ACE2 KO mice also displayed enhanced pro-inflammatory responsiveness such as up-regulated gene/protein expression of VCAM-1, MCP-1, and MMP9 to stimulation with tumour necrosis factor-α and Ang-II. The similar phenotype was shown in human macrophages and aortic VSMCs that were transfected with ACE2-specific siRNA. In ACE2-deficient VSMCs, inhibition of c-Jun N-terminal kinase (JNK) by pharmacological blockade with SP600125 or genetic knockdown with JNK-specific siRNA significantly attenuated their pro-inflammatory phenotype. ACE2 deficiency promotes the development of vascular diseases associated with Ang-II-mediated vascular inflammation and activation of the JNK signalling, leading to the notion that ACE2 potentially confers protection against vascular diseases.

The Association of Angiotensin-Converting Enzyme Gene Insertion/Deletion Polymorphisms with Acute Mountain Sickness Susceptibility: A Meta-Analysis

Altitude exposure in nonacclimatized subjects may lead to acute mountain sickness (AMS). AMS is defined as headache upon recent arrival to altitude and may be accompanied by loss of appetite, nausea or vomiting, dizziness, fatigue, and poor sleep. Susceptibility for AMS varies and has been linked to angiotensin-converting enzyme (ACE) gene polymorphisms. We performed a meta-analysis of studies to assess the association between the ACE deletion (D) and insertion (I) alleles and AMS from published data. A fixed effects model was applied and study quality was assessed in duplicate. Five studies with a total of 333 AMS cases and 373 healthy controls were assessed. Our results revealed no significant differences in risk for AMS between carriers of ACE deletion and insertion polymorphism alleles.

Angiotensin-converting enzyme (ACE) serum levels and gene polymorphism in Egyptian patients with systemic lupus erythematosus

To investigate the association of angiotensin-converting enzyme (ACE) gene polymorphism and serum ACE level among Egyptian SLE patients and its relation to disease activity parameters. We enrolled 50 Egyptian female systemic lupus erythematosus (SLE) patients and 29 healthy controls. Measurement of serum ACE level was done using ELISA, and the ACE genotype was determined by polymerase chain reaction using genomic DNA from peripheral blood. A significant difference was found in ACE genotypes between SLE patients and controls (χ(2 )= 7.84, p = 0.02). The frequency of ACE DD versus (DI and II) genotypes was significantly higher in SLE patients compared with controls (χ(2 )= 5.57, p = 0.018 and OR for risk of SLE was 3.1 with 95% confidence interval: 1.198.06). Mean serum ACE level was significantly higher in the SLE group compared with controls (p = 0.006). Subjects with DD genotype had a significantly higher mean level than those with DI (p = 0.015) and II genotypes (p = 0.02). Lupus nephritis patients had a significantly higher frequency of DD versus DI and II genotypes compared with lupus patients without nephritis (Fisher's exact test, p = 0.025) and controls (χ (2) =8.74, p = 0.003). SLE patients with vasculopathy had a significantly higher frequency of DD versus DI/II genotypes compared with SLE patients without vasculopathy (Fisher's exact test, p = 0.04) and controls (χ(2 )= 9.84 and p = 0.002). Mean serum ACE level was significantly higher in the lupus nephritis and SLE patients with vasculopathy compared with controls (p = 0.008, p = 0.001, respectively). Significant positive correlations were found between serum ACE level and serum creatinine and 24 h proteinuria (p = 0.03, 0.009, respectively). SLE patients with DD genotype had a statistically significant higher mean SLEDAI score than those with (DI/II) genotypes (p = 0.02). Significant positive correlation was found between serum ACE levels and SLEDAI scores (p = 0.04). ACE genotype and subsequently serum ACE level could be associated with the disease activity of Egyptian SLE patients; in addition, ACE deletion polymorphism might be used as one of the predictive factors for the activity of SLE. Further studies on a larger number of patients should be done to determine the exact prevalence of ACE gene polymorphism among Egyptian SLE patients.

Alternative pathways for angiotensin II generation in the cardiovascular system

The classical renin-angiotensin system (RAS) consists of enzymes and peptides that regulate blood pressure and electrolyte and fluid homeostasis. Angiotensin II (Ang II) is one of the most important and extensively studied components of the RAS. The beneficial effects of angiotensin converting enzyme (ACE) inhibitors in the treatment of hypertension and heart failure, among other diseases, are well known. However, it has been reported that patients chronically treated with effective doses of these inhibitors do not show suppression of Ang II formation, suggesting the involvement of pathways alternative to ACE in the generation of Ang II. Moreover, the finding that the concentration of Ang II is preserved in the kidney, heart and lungs of mice with an ACE deletion indicates the important role of alternative pathways under basal conditions to maintain the levels of Ang II. Our group has characterized the serine protease elastase-2 as an alternative pathway for Ang II generation from Ang I in rats. A role for elastase-2 in the cardiovascular system was suggested by studies performed in heart and conductance and resistance vessels of normotensive and spontaneously hypertensive rats. This mini-review will highlight the pharmacological aspects of the RAS, emphasizing the role of elastase-2, an alternative pathway for Ang II generation.

Angiotensin-converting enzyme deletion allele is beneficial for the longevity of Europeans

The human angiotensin converting enzyme (ACE) gene is one of the most investigated candidate genes for cardiovascular diseases (CVD), but the understanding of its role among the elderly is vague. Therefore, this study focuses at: (a) testing the association of ACE polymorphism with CVD risk factors among the elderly, and (b) detecting the possible unequal distribution of ACE genotypes between senescent and younger segments of the European populations. The association of ACE I/D polymorphism with CVD health status [hypertension (HT), obesity, dislypidemia] in 301 very old subjects (88.2 ± 5 years; F/M = 221/80) was tested by means of logistic regression analysis. The meta-analysis of D allele frequency in general vs. elderly (80+ years) groups was conducted using all publicly available data for European populations comprising both age cohorts. Multiple multinomial logistic regression revealed that within this elderly sample, age (younger olds, 80-90 years), female sex (OR = 3.13, 95% CI = 1.59-6.19), and elevated triglycerides (OR = 2.53, 95% CI = 1.29-4.95) were positively associated with HT, while ACE polymorphism was not. It was also established that the DD genotype was twice as high in 80+ cohort compared to general population of Croatia (p < 0.00001). This trend was confirmed by the meta-analysis that showed higher D allele frequencies in olds from nine of ten considered European populations (OR = 1.19, 95% CI = 1.08-1.31). The data in elderly cohort do not confirm previously reported role of ACE DD genotype to the development of HT. Moreover, meta-analysis indicated that ACE D allele has some selective advantage that contributes to longevity in majority of European populations.