Angiotensin System Components Research Articles

Genetic knockdown of brain-derived neurotrophic factor in the nervous system attenuates angiotensin II-induced hypertension in mice.

Introduction:Brain-derived neurotropic factor (BDNF) is expressed throughout the central nervous system and peripheral organs involved in the regulation of blood pressure, but the systemic effects of BDNF in the control of blood pressure are not well elucidated.Materials and methods:We utilized loxP flanked BDNF male mice to cross with nestin-Cre female mice to generate nerve system BDNF knockdown mice, nestin-BDNF (+/–), or injected Cre adenovirus into the subfornical organ to create subfornical organ BDNF knockdown mice. Histochemistry was used to verify injection location. Radiotelemetry was employed to determine baseline blood pressure and pressor response to angiotensin II (1000 ng/kg/min). Real-time polymerase chain reaction was used to measure the expression of renin–angiotensin system components in the laminal terminalis and peripheral organs.Results:Nestin-BDNF (+/–) mice had lower renin–angiotensin system expression in the laminal terminalis and peripheral organs including the gonadal fat pad, and a lower basal blood pressure. They exhibited an attenuated hypertensive response and a weak or similar modification of renin–angiotensin system component expression to angiotensin II infusion. Subfornical organ BDNF knockdown was sufficient for the attenuation of angiotensin II-induced hypertension.Conclusion:Central BDNF, especially subfornical organ BDNF is involved in the maintenance of basal blood pressure and in augmentation of hypertensive response to angiotensin II through systemic regulation of the expression of renin–angiotensin system molecules.

Perinatal α-tocopherol overload programs alterations in kidney development and renal angiotensin II signaling pathways at birth and at juvenile age: Mechanisms underlying the development of elevated blood pressure

α-Tocopherol (α-Toc) overload increases the risk of dying in humans (E.R. Miller III et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality Ann Int Med. 142 (2005) 37–46), and overload during early development leads to elevation of blood pressure at adult life, but the mechanism(s) remains unknown. We hypothesized that α-Toc overload during organogenesis affects the renal renin angiotensin system (RAS) components and renal Na+ handling, culminating with late elevated blood pressure. Pregnant Wistar rats received α-Toc or the superoxide dismutase mimetic tempol throughout pregnancy. We evaluated components of the intrarenal renin angiotensin system in neonate and juvenile offspring: Ang II-positive cells, Ang II receptors (AT1 and AT2), linked protein kinases, O2− production, NADPH oxidase abundance, lipid peroxidation and activity of Na+-transporting ATPases. In juvenile offspring we followed the evolution of arterial blood pressure. Neonates from α-Toc and tempol mothers presented with accentuated retardment in tubular development, pronounced decrease in glomerular Ang II-positive cells and AT1/AT2 ratio, intense production of O2− and upregulation of the α, ε and λ PKC isoforms. α-Toc decreased or augmented the abundance of renal (Na++K+)ATPase depending on the age and α-Toc dose. In juvenile rats the number of Ang II-positive cells returned to control values as well as PKCα, but co-existing with marked upregulation in the activity of (Na++K+) and Na+-ATPase and elevated arterial pressure at 30 days. We conclude that the mechanisms of these alterations rely on selective targeting of renal RAS components through genic and pro-oxidant effects of the vitamin.

GPER Agonist G1, but Not Other Specific ERs Improves Diastolic Function and Attenuates Cardiac RAS Activation in Estrogen‐deficient SHR

IntroductionLeft ventricular diastolic dysfunction (LVDD) increases the risk of developing heart failure with preserved ejection fraction (HFpEF), the predominant type of heart failure seen in women. Emerging epidemiologic evidence suggests that early menopause is positively associated with incident HF, which suggests potential protective roles of estrogens in LVDD development and progression. There are three estrogen receptors (ER) expressed in the heart, ER‐α, ER‐β, and G‐protein coupled ER (GPER). We previously found that GPER plays greater protective roles in cultured myocyte and mast cell lines than ER‐α or ER‐β, by inhibiting Ang II‐induced cell hypertrophy and serum‐induced cell proliferation, respectively. Moreover, estrogen loss‐induced LVDD in the hypertensive mRen2. Lewis rat was linked to increases in cardiac mast cell number, chymase, and Ang II. The aim of this study was to investigate how different specific agonists of estrogen receptors (ER‐α agonist PPT; ER‐β agonist DPN; and GPER agonist G‐1) influence diastolic function and cardiac renin angiotensin system (RAS) components.MethodsTwenty‐four SHR females underwent bilateral ovariectomy (OVX) at 12 weeks of age; 8 weeks post‐surgery, rats were randomized (n=6/group) to receive equipotent, daily treatments (0.24 μMol/kg/day, s.c.) of one of the above ER agonists (PPT‐ 94 μg/kg; DPN‐ 58 μg/kg; G‐1‐100 μg/kg), or vehicle (peanut oil). Following four weeks of treatment, rats were anesthetized (isoflurane) for direct blood pressure and Doppler echo measures of diastolic function, defined by e′ and E/e′. LV tissue for RAS activity and expression were evaluated. Data were analyzed by one‐way ANOVA. P<0.05 was significant.ResultsAs expected, the doses chosen for the specific ER agonists did not overtly affect blood pressure. Of the ER agonists, G‐1 had the most profound and significant impact on diastolic function, increasing myocardial relaxation (e′) and decreasing Doppler‐derived LV filling pressures (E/e′) by 53% and 24% versus control, respectively. Neither DPN nor PPT modified the altered cardiac function induced by OVX. GPER activation by G‐1 had a significant inhibitory effect on cardiac ACE activity when compared to vehicle, while the other Ang II‐forming pathway in the heart, Ang‐1–12/chymase, was not overtly altered by ER activation. All three agonists suppressed cardiac ACE2 activity. AT1R gene expression was increased in OVX‐vehicle by 47 to 61% when compared to hearts from OVX‐ERs (P=0.051) (Figure).ConclusionThese data imply that of the three estrogen receptors, GPER has a unique role in the preservation of diastolic function and modulation of the cardiac RAS, which would contribute to the protection in LVDD disease progression after estrogen loss, if pharmacologically activated.Support or Funding InformationNIH AG033727 (LG) and NIH HL 051952 (CMF and LG) INCT‐INOFAR ‐ Proc. 465249/2014‐0 (GZS and RTS) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (JS) Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq) (GZS and RTS)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The protective arm of the renin–angiotensin system may counteract the intense inflammatory process in fetuses with posterior urethral valves

ObjectivePosterior urethral valve is the most common lower urinary tract obstruction in male children. A high percentage of patients with posterior urethral valve evolve to end-stage renal disease. Previous studies showed that cytokines, chemokines, and components of the renin–angiotensin system contribute to the renal damage in obstructive uropathies. The authors recently found that urine samples from fetuses with posterior urethral valve have increased levels of inflammatory molecules. The aim of this study was to measure renin–angiotensin system molecules and to investigate their correlation with previously detected inflammatory markers in the same urine samples of fetuses with posterior urethral valve. MethodsUrine samples from 24 fetuses with posterior urethral valve were collected and compared to those from 22 healthy male newborns at the same gestational age (controls). Renin–angiotensin system components levels were measured by enzyme-linked immunosorbent assay. ResultsFetuses with posterior urethral valve presented increased urinary levels of angiotensin (Ang) I, Ang-(1-7) and angiotensin-converting enzyme 2 in comparison with controls. ACE levels were significantly reduced and Ang II levels were similar in fetuses with posterior urethral valve in comparison with controls. ConclusionsIncreased urinary levels of angiotensin-converting enzyme 2 and of Ang-(1-7) in fetuses with posterior urethral valve could represent a regulatory response to the intense inflammatory process triggered by posterior urethral valve.

Novel angiotensin receptor blocker, azilsartan induces oxidative stress and NFkB-mediated apoptosis in hepatocellular carcinoma cell line HepG2

Overexpression of renin angiotensin system (RAS) components and nuclear factor-kappa B (NF-kB) has a key role in various cancers. Blockade of RAS and NF-kB pathway has been suggested to reduce cancer cell proliferation. This study aimed to investigate the role of angiotensin II and NF-kB pathway in liver hepatocellular carcinoma cell line (HepG2) proliferation by using azilsartan (as a novel Ag II antagonist) and Bay 11-7082 (as NF-kB inhibitor). HepG2 cells were treated with different concentrations of azilsartan and Bay 11-7082. Cytotoxicity was determined after 24, 48, and 72 h by MTT assay. Reactive oxygen spices (ROS) generation and cytochrome c release were measured following azilsartan and Bay11- 7082 treatment. Apoptosis was analyzed qualitatively by DAPI staining and quantitatively through flow cytometry methodologies and Bax and Bcl-2 mRNA and protein levels were assessed by real time PCR and ELISA methods, respectively. The cytotoxic effects of different concentration of azilsartan and Bay11- 7082 on HepG2 cells were observed as a reduction in cell viability, increased ROS formation, cytochrome c release and apoptosis induction. These effects were found to correlate with a shift in Bax level and a downward trend in the expression of Bcl-2. These findings suggest that azilsartan and Bay11- 7082 in combination or alone have strong potential as an agent for prevention or treatment of liver cancer after further studies.

Shifts in renin–angiotensin system components, angiogenesis, and oxidative stress-related protein expression in the lamina cribrosa region of streptozotocin-induced diabetic mice

This study aimed to analyse shifts in renin-angiotensin system (RAS) components, angiogenesis, and oxidative stress-related protein expression in the lamina cribrosa (LC) region in streptozotocin (STZ)-induced diabetic mice. Six months after diabetes induction, the retinal vessels of male C57BL/6J mice were observed by colour photography, fundus fluorescein angiography (FFA), and immunofluorescent staining following incubation with CD31. Immunofluorescence for glial fibrillary acidic protein (GFAP), alpha-smooth muscle actin (α-SMA),and NG2 was also performed. Angiotensin-converting enzyme 1 (ACE1), angiotensin II type I receptor (AT1R), renin, hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR2), and haeme oxygenase 1 (HO-1) expression levels were confirmed by immunohistochemical and western blotting analyses. Compared with control mice, diabetic mice had significantly higher blood glucose concentrations (p < 0.001) and significantly lower body weights (p < 0.001). Colour photography and FFA did not reveal any vessel abnormalities in the diabetic mice; however, immunostaining of whole-mount retinas revealed an increased number of retinal vessels. Furthermore, histopathological staining showed significant reduction in the whole retinal thickness. GFAP expression was slightly higher, whereas fewer NG2+ pericytes were observed in diabetic mice than in control mice. ACE1, AT1R, renin, HIF-1α, VEGF, VEGFR2, and HO-1 expression were up-regulated in the LC of the STZ-induced diabetic mice. Collectively, ACE 1, AT1R, HIF-1α, VEGF, VEGFR2, and HO-1 activation in the LC region in diabetic mice may be involved in diabetes via the RAS and induction of angiogenesis and oxidative stress.

Tumor necrosis factor α-converting enzyme inhibitor attenuates lipopolysaccharide-induced reactive oxygen species and mitogen-activated protein kinase expression in human renal proximal tubule epithelial cells

Tumor necrosis factor-α (TNFα) and the angiotensin system are involved in inflammatory diseases and may contribute to acute kidney injury. We investigated the mechanisms by which TNFα-converting enzyme (TACE) contributes to lipopolysaccharide (LPS)-induced renal inflammation and the effect of TACE inhibitor treatment on LPS-induced cellular injury in human renal proximal tubule epithelial (HK-2) cells. Mice were treated with LPS (10 mg/kg, i.p.) and HK-2 cells were cultured with or without LPS (10 µg/ml) in the presence or absence of a type 1 TACE inhibitor (1 µM) or type 2 TACE inhibitor (10 µM). LPS treatment induced increased serum creatinine, TNFα, and urinary neutrophil gelatinase-associated lipocalin. Angiotensin II type 1 receptor, mitogen activated protein kinase (MAPK), and TACE increased, while angiotensin-converting enzyme-2 (ACE2) expression decreased in LPS-induced acute kidney injury and LPS-treated HK-2 cells. LPS induced reactive oxygen species and the down-regulation of ACE2, and these responses were prevented by TACE inhibitors in HK-2 cells. TACE inhibitors increased cell viability in LPS-treated HK-2 cells and attenuated oxidative stress and inflammatory cytokines. Our findings indicate that LPS activates renin angiotensin system components via the activation of TACE. Furthermore, inhibitors of TACE are potential therapeutic agents for kidney injury.

Obesity and malnutrition similarly alter the renin–angiotensin system and inflammation in mice and human adipose

The main goal of the present study was to evaluate the metabolic profile, inflammatory markers and the gene expression of the renin–angiotensin system (RAS) components in the visceral adipose tissue of eutrophic, obese and malnourished individuals and mice models of obesity and food restriction. Male Swiss mice were divided into eight groups and fed different levels of food restriction (20%, 40%, or 60%) using standard or high-fat diet. Metabolic profile and adipose tissues were assessed. The expression of AGT (Angiotensinogen), ACE (Angiotensin-converting enzyme), ACE2 (Angiotensin-converting enzyme 2), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in the mice epididymal adipose tissue and the human visceral adipose tissue was assessed. The main findings showed reduced body weight, improved metabolism, decreased adipose tissues weight and reduced adipocyte area in mice submitted to food restriction. Diminished expression of IL-6, TNF-α, AGT, AT1 and ACE was detected in the 20% and 40% food restriction animal groups, although they were increased in the 60% malnourished group. Increased expression of IL-6, TNF-α, AGT and ACE in obese and malnourished individuals was observed. Adipocytes size was increased in obese individuals and reduced in malnutrition. In conclusion, we found that food restriction of 20% and 40% improved the metabolic profile, ameliorated the inflammatory status and down-regulated the RAS in mice. Severe 60% food restriction (malnutrition), however, stimulated a proinflammatory state and increased AGT and ACE expression in the adipose tissue of mice. A similar profile was observed in the adipose tissue of obese and malnourished humans, supporting the critical role of inflammation and RAS as mediators of metabolic disorders.

Angiotensin type 1 receptor A1166C polymorphism and systemic lupus erythematosus: correlation with cellular immunity and oxidative stress markers.

Angiotensin II, one of the rennin-angiotensin system components, is important in the cardiovascular hemodynamic and plays an important role in the development of cardiovascular disease in systemic lupus erythematosus (SLE) patients. The angiotensin II, through interaction with angiotensin II type 1 receptor (AGTR1), promotes proliferation, inflammation and fibrosis. The single nucleotide polymorphism of the AGTR1 (dbSNP: rs5186) gene can be associated with development and progression of SLE disease. The aims of this study were to compare the frequency of AGTR1 rs5186 in SLE patients with healthy individuals and to evaluate possible association between AGTR1 A1166C gene polymorphism and serum level of lipids, neopterin and malondialdehyde in SLE patients from a population of West Iran. One hundred SLE patients and 98 healthy subjects were studied. The AGTR1 A1166C polymorphism was detected by polymerase chain reaction- restriction fragment length polymorphism method and the serum lipid profile was obtained by enzymatic method. Neopterin and malondialdehyde were detected using high-performance liquid chromatography. We did not detect significant association between AGTR1 A1166C polymorphism and the risk of SLE. The levels of triglyceride (225 ± 118 mg/dl), neopterin (30 ± 24 nmol/l) and malondialdehyde (25 ± 9.6 nmol/l) in SLE patients were significantly higher than those in control subjects (139 ± 56 mg/dl, p = 0.03, 6.4 ± 2, p = 0.03, 9.4 ± 2.5 nmol/l, p = 0.01, respectively). Individuals with AGTR1 AC + CC genotype had higher levels of total cholesterol and malondialdehyde compared with those with AGTR1 AA genotype. SLE patients with either AGTR1 AA or AGTR1AC + CC genotype had significantly higher malondialdehyde or neopterin levels compared with the corresponding control subjects. In conclusion, although the present study did not find any association between AGTR1 A1166C polymorphism and the risk of SLE, the presence of this polymorphism was associated with higher levels of malondialdehyde and higher concentration of neopterin in patients.

Immunohistochemical expression of intrarenal renin angiotensin system components in response to tempol in rats fed a high salt diet.

AIMTo determine the effect of tempol in normal rats fed high salt on arterial pressure and the balance between antagonist components of the renal renin-angiotensin system.METHODSSprague-Dawley rats were fed with 8% NaCl high-salt (HS) or 0.4% NaCl (normal-salt, NS) diet for 3 wk, with or without tempol (T) (1 mmol/L, administered in drinking water). Mean arterial pressure (MAP), glomerular filtration rate (GFR), and urinary sodium excretion (UVNa) were measured. We evaluated angiotensin II (Ang II), angiotensin 1-7 (Ang 1-7), angiotensin converting enzyme 2 (ACE2), mas receptor (MasR), angiotensin type 1 receptor (AT1R) and angiotensin type 2 receptor (AT2R) in renal tissues by immunohistochemistry.RESULTSThe intake of high sodium produced a slight but significant increase in MAP and differentially regulated components of the renal renin-angiotensin system (RAS). This included an increase in Ang II and AT1R, and decrease in ACE-2 staining intensity using immunohistochemistry. Antioxidant supplementation with tempol increased natriuresis and GFR, prevented changes in blood pressure and reversed the imbalance of renal RAS components. This includes a decrease in Ang II and AT1R, as increase in AT2, ACE2, Ang (1-7) and MasR staining intensity using immunohistochemistry. In addition, the natriuretic effects of tempol were observed in NS-T group, which showed an increased staining intensity of AT2, ACE2, Ang (1-7) and MasR.CONCLUSIONThese findings suggest that a high salt diet leads to changes in the homeostasis and balance between opposing components of the renal RAS in hypertension to favour an increase in Ang II. Chronic antioxidant supplementation can modulate the balance between the natriuretic and antinatriuretic components of the renal RAS.

Expression of renin-angiotensin system (RAS) components in endometrial cancer.

A dysfunctional endometrial renin–angiotensin system (RAS) could aid the growth and spread of endometrial cancer. To determine if the RAS is altered in endometrial cancer, we measured RAS gene expression and protein levels in 30 human formalin-fixed, paraffin-embedded (FFPE) endometrioid carcinomas and their adjacent endometrium. All components of the RAS were expressed in most tumours and in adjacent endometrium; mRNA levels of (pro)renin receptor (ATP6AP2), angiotensin II type 1 receptor (AGTR1), angiotensin-converting enzyme (ACE1) and angiotensin-converting enzyme 2 (ACE2) mRNA levels were greater in tumour tissue than adjacent non-cancerous endometrium (P = 0.023, 0.008, 0.004 and 0.046, respectively). Prorenin, ATP6AP2, AGTR1, AGTR2 and ACE2 proteins were abundantly expressed in both cancerous and adjacent non-cancerous endometrium. Staining was most intense in cancerous glandular epithelium. One potential target of the endometrial RAS, transforming growth factor beta-1 (TGFB1), which is essential for epithelial-to-mesenchymal transition, was also upregulated in endometrial cancer tissue (P = 0.001). Interestingly, TGFB1 was strongly correlated with RAS expression and was upregulated in tumour tissue. This study is the first to characterise the mRNA and protein expression of all RAS components in cancerous and adjacent non-cancerous endometrium. The greater expression of ATP6AP2, AGTR1 and ACE1, key elements of the pro-angiogenic/proliferative arm of the RAS, suggests that the RAS plays a role in the growth and spread of endometrial cancer. Therefore, existing drugs that inhibit the RAS and which are used to treat hypertension may have potential as treatments for endometrial cancer.

Abstract P625: Improvement of Autonomic Function and C-Reactive Protein in Military Personnel with Traumatic Stress After Use Of a Closed Loop Neurotechnology

Objective: Evaluate changes in autonomic cardiovascular control and inflammatory markers associated with use of High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM) in subjects enrolled in a pilot study for symptoms of military-related traumatic stress (MTS). Introduction: Symptoms associated with MTS include insomnia, depression, anxiety, activated inflammatory response and impaired autonomic control. HIRREM is a noninvasive, closed-loop acoustic stimulation technology that identifies dominant brain frequencies and translates them in real time into audible tones of variable pitch and timing, to support self-updating and self-optimization of brain activity. Methods: Eighteen service members or Veterans (1 female), mean (SD) age 40.9 (7.0), with MTS symptoms for 6 years (3.4), received 19.5 (1.1) HIRREM sessions over 12 days. Continuous recordings of blood pressure and heart rate, for analysis of baroreflex sensitivity (BRS) and heart rate variability (HRV), were done before and immediately after completion of the HIRREM intervention. Blood samples were also collected (n = 14) for measurement of catecholamines, cytokines, C-reactive protein and the renin angiotensin system (RAS) components. Paired t-tests were performed. After HIRREM, there was improved BRS measured as HF alpha (9.6 ms/mmHg, SE 3.1, p = 0.005), Sequence Down (7.6 ms/mmHg, 2.4, p = 0.005), Sequence Up (8.4 ms/mmHg, 3.0, p = 0.01), and Sequence All (7.6 ms/mmHg, 2.2, p = 0.002), as well as HRV; SDNN (12.0 ms, 3.5, p = 0.02), rMSSD (13.2 ms, 3.0, p &lt; 0.001), LF power (1023.0 ms 2 , 346, p = 0.007), HF power (398.0 ms 2 , 142.0, p = 0.01), and total power (1420.8 ms 2 , 450.8, p = 0.005). C-reactive protein (36%, p = 0.057) was also reduced. There were no significant changes in the catecholamine, cytokines or RAS. There were no adverse events or dropouts. Conclusions: These interim results suggest improved autonomic cardiovascular regulation, across multiple measures of BRS and HRV, and reduction in CRP associated with the use of HIRREM for symptoms of MTS. Confirmation of these results in a larger cohort may provide important insights regarding both the mechanisms associated with the beneficial effects of HIRREM, and the functional disturbances underlying MTS.

Angiotensin type 2 receptor null mice express reduced levels of renal angiotensin II type 2 receptor/angiotensin (1-7)/Mas receptor and exhibit greater high-fat diet-induced kidney injury.

Introduction:Renin–angiotensin system (RAS) components exert diverse physiological functions and have been sub-grouped into deleterious angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/angiotensin type 1 receptor (AT1R) and protective ACE2/angiotensin (1-7) (Ang-(1-7))/Mas receptor (MasR) axes. We have reported that chronic activation of angiotensin type 2 receptor (AT2R) alters RAS components and provides protection against obesity-related kidney injury.Materials and methods:We utilized AT2R knockout (AT2KO) mice in this study and evaluated the renal expression of various RAS components and examined the renal injury after placing these mice on high fat diet (HFD) for 16 weeks.Results:The cortical ACE2 activity and MasR expression were significantly decreased in AT2KO mice compared to wild type (WT) mice. LC/MS analysis revealed an increase in renal Ang II levels and a decrease in Ang-(1-7) levels in AT2KO mice. Cortical expression of ACE and AT1R was increased but renin activity remained unchanged in AT2KO compared with WT mice. WT mice fed HFD exhibited increased systolic blood pressure, higher indices of kidney injury, mesangial matrix expansion score, and microalbuminuria, which were further increased in AT2KO mice.Conclusion:This study suggests that deletion of AT2R decreases the expression of the beneficial ACE2/Ang-(1-7)/MasR and increases the deleterious ACE/Ang II/AT1R axis of the renal RAS in mice. Further, AT2KO mice are more susceptible to HFD-induced renal injury.

Role of the Collecting Duct Renin Angiotensin System in Regulation of Blood Pressure and Renal Function.

Recent evidence suggests that the renal tubular renin angiotensin system regulates urinary Na(+) and water excretion and blood pressure. Three key components of the tubular renin angiotensin system, namely renin, prorenin receptor, and angiotensin-II type 1 receptor, are localized to the collecting duct. This system may modulate collecting duct Na(+) and water reabsorption via angiotensin-II-dependent and angiotensin-II-independent pathways. Further, the system may be of greatest relevance in hypertensive states and particularly those characterized by high circulating angiotensin-II. In this review, we summarize the current knowledge on the synthesis, regulation, and function of collecting duct-derived renin angiotensin system components and examine recent developments with regard to regulation of blood pressure and renal fluid and Na(+) excretion.

Renin Angiotensin System Components and Cancer: Reports of Association

Renin-Angiotensin System (RAS) is involved with hypertension and other cardiovascular diseases. However, the association of RAS components to cancer still causes suspicion. To try to clarify this, here we aimed to show this association for three important components: Angiotensin Converting Enzyme 1 (ACE1), Angiotensin Type 1 Receptor (AGTR1) and Angiotensin Type 2 Receptor (AGTR2). The first articles show that association of RAS components with cancer dates back to the 70’s. ECA1 and AGTR1 have close association with cancer and ACE1 inhibitors or AGTR1 blockers are candidates to treatment of some tumors. Moreover, the action of AGTR2 is still controversial, but most studies show that the increased expression of AGTR2 can attack the cancer cells. In breast cancer, these components have also been widely studied and many works have shown that the correlation exists. Therefore specific target using these RAS components could be a beneficial, novel therapy to various tumors.

Effect of oxygen on the expression of renin–angiotensin system components in a human trophoblast cell line

During the first trimester, normal placental development occurs in a low oxygen environment that is known to stimulate angiogenesis via upregulation of vascular endothelial growth factor (VEGF). Expression of the placental renin–angiotensin system (RAS) is highest in early pregnancy. While the RAS and oxygen both stimulate angiogenesis, how they interact within the placenta is unknown. We postulated that low oxygen increases expression of the proangiogenic RAS pathway and that this is associated with increased VEGF in a first trimester human trophoblast cell line (HTR-8/SVneo). HTR-8/SVneo cells were cultured in one of three oxygen tensions (1%, 5% and 20%). RAS and VEGF mRNA expression were determined by qPCR. Prorenin, angiotensin converting enzyme (ACE) and VEGF protein levels in the supernatant, as well as prorenin and ACE in cell lysates, were measured using ELISAs. Low oxygen significantly increased the expression of both angiotensin II type 1 receptor (AGTR1) and VEGF (both P < 0.05). There was a positive correlation between AGTR1 and VEGF expression at low oxygen (r = 0.64, P < 0.005). Corresponding increases in VEGF protein were observed with low oxygen (P < 0.05). Despite no change in ACE1 mRNA expression, ACE levels in the supernatant increased with low oxygen (1% and 5%, P < 0.05). Expression of other RAS components did not change. Low oxygen increased AGTR1 and VEGF expression, as well as ACE and VEGF protein levels, suggesting that the proangiogenic RAS pathway is activated. This highlights a potential role for the placental RAS in mediating the proangiogenic effects of low oxygen in placental development.

Evaluation of Serum Levels of Renin Angiotensin System Components in Asthmatic Patients

Evaluation of Serum Levels of Renin Angiotensin System Components in Asthmatic Patients

Abstract 621: Chymase-mediated Angiotensin II Formation in the Heart of Rats Overexpressing the Human Angiotensinogen Gene

The creation of a transgenic rat model harboring the human angiotensinogen gene [TGR(hAGT)L1623] allows for the identification of alternate angiotensin II (Ang II) enzymatic pathways as rat renin has little, if any, hydrolytic activity on the human angiotensinogen protein. An initial study showing that hypertension associated with cardiac hypertrophy occurs in TGR(hAGT)L1623 rats led us to characterize the cardiac expression of renin angiotensin system components in 9 male TGR(hAGT)L1623 and 11 Sprague Dawley (SD) control rats. Cardiac Ang II content was higher in TGR(hAGT)L1623 rats when compared with SD rats (37±5 fmol/mg protein vs. 9.6±0.9 fmol/mg protein, respectively; P &lt; 0.001). Although content of rat angiotensin-(1-12) [Ang-(1-12)] was comparable in both transgenic and control rats, chymase activity in the heart of both groups of rats was almost 9-fold higher when compared to cardiac angiotensin-converting enzyme (ACE) activity [chymase activity: 9.6±0.8 fmol/min/mg protein vs. 1.2±0.4 fmol/min/mg protein ACE activity in TGR(hAGT)L1623]. No significant differences in plasma renin concentration (PRC) was found between TGR(hAGT)L1623 and control SD rats (1.37±0.21 fmol/mL vs. 1.47±0.31 fmol/mL, respectively). Our findings further suggest that chymase enzyme (not ACE) is primarily responsible for generating Ang II in rat heart tissue. TGR(hAGT)L1623 rats represent a novel tool to investigate the direct contribution of renin-independent Ang II formation via chymase or other Ang II forming enzymes that expressed in the rat heart possess hydrolytic activity on human angiotensinogen.

Mutual amplification of corticosteroids and angiotensin systems in human vascular smooth muscle cells and carotid atheroma.

The involvement of the renin-angiotensin-aldosterone system (RAAS) and cortisol in increased cardiovascular risk is well known. If numerous relationships between RAAS and corticosteroids have been described, their interactions within the arterial wall, especially during the transdifferentiation of vascular smooth muscle cells (VSMCs) and the atheroma formation, are not established. Here, we clarified the relationships between mRNA levels of corticosteroid and angiotensin system components using cortisol, fludrocortisone, and angiotensin II treatments of cultured VSMCs maintained in a contractile phenotype or induced to a lipid storing phenotype. We then determined the quantitative relationships between the mRNA content of these components measured with reverse transcription polymerase chain reaction (RT-PCR), in the atheroma plaque and nearby macroscopically intact tissue (MIT) from 27 human carotid endarterectomy samples. In both VSMC phenotypes, cortisol markedly increased both angiotensinogen (AGT) and AT1-receptor (AT1R) mRNA levels. These effects of cortisol were mediated via glucocorticoid receptor-α (GRα) without any illicit activation of the mineralocorticoid receptor (MR). Angiotensin II increased GRα, 11βHSD1, CYP11B1, as well as CYP11B2 mRNAs and decreased AT1R in contractile VSMC; only GRα and CYP11B2 were increased in lipid storing VSMCs, while MR and AGT mRNAs decreased. In endarterectomy specimens, positive correlations between mRNA levels of AGT and aldosterone synthase or 11βHSD1 in MIT and of AT1R and MR in atheroma were detected. The arterial tissue angiotensin system is a target for local glucocorticoids and arterial glucocorticoids for angiotensin II. Both systems appear activated in lipid storing VSMCs and strongly correlated in vivo, and their mutual amplification may contribute to the development of atheroma. Cortisol increases angiotensin II signaling in VSMCs via GRα. Angiotensin II stimulates cortisol signaling through increased GRα and 11β-HSD1. Corticoid and angiotensin receptors are strongly correlated in the arterial wall. These correlations are maintained at different stages of atheroma development. An auto-amplification loop between angiotensin and cortisol signaling favors atherogenesis.

Voluntary exercise during 6 weeks induces pathological cardiovascular responses in MAS‐deficient mice (881.4)

Physical training induces numerous physiological adaptations in the cardiovascular and skeletal muscle system related to changes in gene expression including modulation of the renin angiotensin system (RAS) components. Thus, the aim of this study was to evaluate the effect of running wheel training in knockout mice for the angiotensin‐(1‐7) receptor (MAS‐KO). For this we used C57Bl6 male mice (8‐12 weeks old) WT and MAS‐ KO divided into voluntary exercise group or sedentary control (N = 4‐8 per group). The aerobic training lasted 6 weeks and the amount of exercise was measured by the number of rotations per day. The gene expression responses of factors related to physiological and pathological adaptations and RAS components in the left ventricle, skeletal muscle and adipose tissue were evaluated by real‐time PCR (qPCR). Blood pressure (BP) was measured before and during the period of physical training using radio‐telemetry. The plasma levels of angiotensin peptides were determined by mass spectrometry. The results showed that in WT and MAS‐KO mice aerobic training promotes cardiac hypertrophy but in MAS‐KO it induced the expression of genes related to pathological conditions (ANP and BNP) and high plasmatic AngII / AngI ratio (0.204 vs. 0,126 pg/ml). The chronic aerobic exercise promoted an increase in skeletal muscle expression of FNDC5, irisin precursor, only in WT. In contrast, angiotensin‐(1‐7) receptor deficiency mice showed reduced FNDC5 expression in skeletal muscle (gastrocnemius and soleus) and no differences in inguinal adipose tissue UCP1 expression, opposite responses to that observed in WT mice. The MAS‐KO group presented slightly elevated baseline mean BP (105.5 ± 6.55 vs. 98.48 ± 7.65 mmHg for MAS‐KO and WT). A paradoxal increase in BP after 4 weeks of voluntary running was observed im Mas‐deficient group. It was concluded that voluntary exercise during 6 weeks induces pathological cardiovascular responses in MAS‐KO mice.Grant Funding Source: CAPES/PROBRAL