Showing papers on "Angiotensin II published in 2017"
Cleveland Clinic1, University of Ottawa2, Duke University3, Regions Hospital4, University of Tennessee5, Baylor University Medical Center6, Emory University7, University of California, Davis8, University of California, Los Angeles9, Riverside Methodist Hospital10, Northwestern University11, Guy's and St Thomas' NHS Foundation Trust12, University of Pittsburgh13, Yeshiva University14, University of Newcastle15, university of lille16, University of Melbourne17, University of Helsinki18, Lille University of Science and Technology19, Harvard University20, University of Maryland, Baltimore21
TL;DR: Angiotensin II effectively increased blood pressure in patients with vasodilatory shock that did not respond to high doses of conventional vasopressors.
Abstract: BackgroundVasodilatory shock that does not respond to high-dose vasopressors is associated with high mortality. We investigated the effectiveness of angiotensin II for the treatment of patients with this condition. MethodsWe randomly assigned patients with vasodilatory shock who were receiving more than 0.2 μg of norepinephrine per kilogram of body weight per minute or the equivalent dose of another vasopressor to receive infusions of either angiotensin II or placebo. The primary end point was a response with respect to mean arterial pressure at hour 3 after the start of infusion, with response defined as an increase from baseline of at least 10 mm Hg or an increase to at least 75 mm Hg, without an increase in the dose of background vasopressors. ResultsA total of 344 patients were assigned to one of the two regimens; 321 received a study intervention (163 received angiotensin II, and 158 received placebo) and were included in the analysis. The primary end point was reached by more patients in the angiote...
499 citations
TL;DR: GSK2586881 was well-tolerated in patients with ARDS, and the rapid modulation of RAS peptides suggests target engagement, although the study was not powered to detect changes in acute physiology or clinical outcomes.
Abstract: Renin-angiotensin system (RAS) signaling and angiotensin-converting enzyme 2 (ACE2) have been implicated in the pathogenesis of acute respiratory distress syndrome (ARDS). We postulated that repleting ACE2 using GSK2586881, a recombinant form of human angiotensin-converting enzyme 2 (rhACE2), could attenuate acute lung injury. We conducted a two-part phase II trial comprising an open-label intrapatient dose escalation and a randomized, double-blind, placebo-controlled phase in ten intensive care units in North America. Patients were between the ages of 18 and 80 years, had an American-European Consensus Criteria consensus diagnosis of ARDS, and had been mechanically ventilated for less than 72 h. In part A, open-label GSK2586881 was administered at doses from 0.1 mg/kg to 0.8 mg/kg to assess safety, pharmacokinetics, and pharmacodynamics. Following review of data from part A, a randomized, double-blind, placebo-controlled investigation of twice-daily doses of GSK2586881 (0.4 mg/kg) for 3 days was conducted (part B). Biomarkers, physiological assessments, and clinical endpoints were collected over the dosing period and during follow-up. Dose escalation in part A was well-tolerated without clinically significant hemodynamic changes. Part B was terminated after 39 of the planned 60 patients following a planned futility analysis. Angiotensin II levels decreased rapidly following infusion of GSK2586881, whereas angiotensin-(1–7) and angiotensin-(1–5) levels increased and remained elevated for 48 h. Surfactant protein D concentrations were increased, whereas there was a trend for a decrease in interleukin-6 concentrations in rhACE2-treated subjects compared with placebo. No significant differences were noted in ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, oxygenation index, or Sequential Organ Failure Assessment score. GSK2586881 was well-tolerated in patients with ARDS, and the rapid modulation of RAS peptides suggests target engagement, although the study was not powered to detect changes in acute physiology or clinical outcomes. ClinicalTrials.gov, NCT01597635
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497 citations
TL;DR: Targeting of gut microbiota by innovative probiotics, antibiotics, and fecal transplant, in combination with the current pharmacotherapy, may be a novel strategy for hypertension treatment.
Abstract: Rationale: Sympathetic nervous system control of inflammation plays a central role in hypertension The gut receives significant sympathetic innervation, is densely populated with a diverse microbial ecosystem, and contains immune cells that greatly impact overall inflammatory homeostasis Despite this uniqueness, little is known about the involvement of the gut in hypertension Objective: Test the hypothesis that increased sympathetic drive to the gut is associated with increased gut wall permeability, increased inflammatory status, and microbial dysbiosis and that these gut pathological changes are linked to hypertension Methods and Results: Gut epithelial integrity and wall pathology were examined in spontaneously hypertensive rat and chronic angiotensin II infusion rat models The increase in blood pressure in spontaneously hypertensive rat was associated with gut pathology that included increased intestinal permeability and decreased tight junction proteins These changes in gut pathology in hypertension were associated with alterations in microbial communities relevant in blood pressure control We also observed enhanced gut–neuronal communication in hypertension originating from paraventricular nucleus of the hypothalamus and presenting as increased sympathetic drive to the gut Finally, angiotensin-converting enzyme inhibition (captopril) normalized blood pressure and was associated with reversal of gut pathology Conclusions: A dysfunctional sympathetic–gut communication is associated with gut pathology, dysbiosis, and inflammation and plays a key role in hypertension Thus, targeting of gut microbiota by innovative probiotics, antibiotics, and fecal transplant, in combination with the current pharmacotherapy, may be a novel strategy for hypertension treatment
343 citations
TL;DR: Important facets of RAAS are discussed, its crosstalk with other crucial factors like estrogen, thyroid, cortisol, kallikrein-kinin system, Wnt/β-catenin signaling, and sodium-potassium pump, which can contribute to better management of an array of pathologies plaguing mankind.
330 citations
TL;DR: The roles and therapeutic implications of the vasoprotective axes of the RAS in cardiovascular, hypertensive and kidney diseases are reviewed.
317 citations
TL;DR: It is essential to improve the knowledge of the cellular and molecular mechanisms of the progress of renal fibrosis in order to achieve a reversion/elimination of kidney fibrosis.
Abstract: Chronic kidney disease (CKD) is a long-term condition in which the kidneys do not work correctly. It has a high prevalence and represents a serious hazard to human health and estimated to affects hundreds of millions of people. Diabetes and hypertension are the two principal causes of CKD. The progression of CKD is characterized by the loss of renal cells and their replacement by extracellular matrix (ECM), independently of the associated disease. Thus, one of the consequences of CKD is glomerulosclerosis and tubulointerstitial fibrosis caused by an imbalance between excessive synthesis and reduced breakdown of the ECM. There are many molecules and cells that are associated with progression of renal fibrosis e.g. angiotensin II (Ang II). Therefore, in order to understand the biopathology of renal fibrosis and for the evaluation of new treatments, the use of animal models is crucial such as: surgical, chemical and physical models, spontaneous models, genetic models and in vitro models. However, there are currently no effective treatments for preventing the progression of renal fibrosis. Therefore it is essential to improve our knowledge of the cellular and molecular mechanisms of the progress of renal fibrosis in order to achieve a reversion/elimination of renal fibrosis.
253 citations
TL;DR: Experimental studies clearly support the anti-inflammatory and anti-fibrotic effects of ACE2/ Ang-(1-7)/Mas axis, and clinical studies will be necessary to establish the therapeutic role of ACE1/Ang-1- 7/Mas axis in controlling inflammation in different human diseases.
Abstract: Background The renin angiotensin system (RAS) plays an important role in inflammation and fibrosis. The classical axis of the RAS, formed by angiotensin converting en-zyme (ACE), angiotensin II (Ang II) and angiotensin receptor type 1 (AT1), activates several cell functions and molecular signaling pathways related to tissue injury, inflammation and fibrosis. In sharp contrast, the RAS axis composed by angiotensin converting enzyme 2 (ACE2), angiotensin-(1-7) and Mas receptor exerts opposite effects in relation to inflammatory response and tissue fibrosis. Objective In this review, we have the aim to summarize recent findings on the anti-inflammatory and anti-fibrogenic role of ACE2/Ang-(1-7)/Mas axis in the context of basic research, experimental human dis-eases and clinical studies. Results Several studies showed that ACE2/Angiotensin-(1-7)/Mas axis reduces cytokine release and inhibits signaling pathways of tissue fibrosis in experimental models of human diseases including atherosclerosis, cerebral ischemia, obesity, chronic kidney disease, liver diseases and asthma. On the other hand, very few data was provided by clinical studies. Conclusion Experimental studies clearly support the anti-inflammatory and anti-fibrotic effects of ACE2/ Ang-(1-7)/Mas axis. Clinical studies, especially phase III and IV trials, will be necessary to establish the therapeutic role of ACE2/Ang-(1-7)/Mas axis in controlling inflammation in different human diseases.
245 citations
TL;DR: It is shown that peroxidase-catalyzed proximity labeling can be combined with isobaric tagging and mass spectrometry to enable quantitative, time-resolved measurement of GPCR agonist response in living cells.
198 citations
TL;DR: It is suggested that lower proximal reabsorption in female rats expedites excretion of a saline load and enhances NCC and ENaC abundance and activation, which may facilitate K+ secretion and set plasma K+ at a lower level.
Abstract: Compared with males, females have lower BP before age 60, blunted hypertensive response to angiotensin II, and a leftward shift in pressure natriuresis. This study tested the concept that this female advantage associates with a distinct sexual dimorphic pattern of transporters along the nephron. We applied quantitative immunoblotting to generate profiles of transporters, channels, claudins, and selected regulators in both sexes and assessed the physiologic consequences of the differences. In rats, females excreted a saline load more rapidly than males did. Compared with the proximal tubule of males, the proximal tubule of females had greater phosphorylation of Na+/H+ exchanger isoform 3 (NHE3), distribution of NHE3 at the base of the microvilli, and less abundant expression of Na+/Pi cotransporter 2, claudin-2, and aquaporin 1. These changes associated with less bicarbonate reabsorption and higher lithium clearance in females. The distal nephrons of females had a higher abundance of total and phosphorylated Na+/Cl- cotransporter (NCC), claudin-7, and cleaved forms of epithelial Na+ channel (ENaC) α and γ subunits, which associated with a lower baseline plasma K+ concentration. A K+-rich meal increased the urinary K+ concentration and decreased the level of renal phosphorylated NCC in females. Notably, we observed similar abundance profiles in female versus male C57BL/6 mice. These results define sexual dimorphic phenotypes along the nephron and suggest that lower proximal reabsorption in female rats expedites excretion of a saline load and enhances NCC and ENaC abundance and activation, which may facilitate K+ secretion and set plasma K+ at a lower level.
186 citations
TL;DR: The data suggest that diminished Sirt3 expression and redox inactivation of SIRT3 lead to SOD2 inactivation and contributes to the pathogenesis of hypertension.
Abstract: Rationale: Clinical studies have shown that Sirt3 (Sirtuin 3) expression declines by 40% by 65 years of age paralleling the increased incidence of hypertension and metabolic conditions further inactivate Sirt3 because of increased NADH (nicotinamide adenine dinucleotide, reduced form) and acetyl-CoA levels. Sirt3 impairment reduces the activity of a key mitochondrial antioxidant enzyme, superoxide dismutase 2 (SOD2) because of hyperacetylation. Objective: In this study, we examined whether the loss of Sirt3 activity increases vascular oxidative stress because of SOD2 hyperacetylation and promotes endothelial dysfunction and hypertension. Methods and Results: Hypertension was markedly increased in Sirt3-knockout (Sirt3 −/ − ) and SOD2-depleted (SOD2 +/ − ) mice in response to low dose of angiotensin II (0.3 mg/kg per day) compared with wild-type C57Bl/6J mice. Sirt3 depletion increased SOD2 acetylation, elevated mitochondrial O 2 · – , and diminished endothelial nitric oxide. Angiotensin II-induced hypertension was associated with Sirt3 S-glutathionylation, acetylation of vascular SOD2, and reduced SOD2 activity. Scavenging of mitochondrial H 2 O 2 in mCAT mice expressing mitochondria-targeted catalase prevented Sirt3 and SOD2 impairment and attenuated hypertension. Treatment of mice after onset of hypertension with a mitochondria-targeted H 2 O 2 scavenger, mitochondria-targeted hydrogen peroxide scavenger ebselen, reduced Sirt3 S-glutathionylation, diminished SOD2 acetylation, and reduced blood pressure in wild-type but not in Sirt3 −/− mice, whereas an SOD2 mimetic, (2-[2,2,6,6-tetramethylpiperidin-1-oxyl-4-ylamino]-2-oxoethyl) triphenylphosphonium (mitoTEMPO), reduced blood pressure and improved vasorelaxation both in Sirt3 −/− and wild-type mice. SOD2 acetylation had an inverse correlation with SOD2 activity and a direct correlation with the severity of hypertension. Analysis of human subjects with essential hypertension showed 2.6-fold increase in SOD2 acetylation and 1.4-fold decrease in Sirt3 levels, whereas SOD2 expression was not affected. Conclusions: Our data suggest that diminished Sirt3 expression and redox inactivation of Sirt3 lead to SOD2 inactivation and contributes to the pathogenesis of hypertension.
174 citations
TL;DR: The scientific evidence for interactions and potential roles for oxidative stress, inflammation and mitochondrial dysfunction in these target tissues which may mediate effects of RAS in metabolic diseases are reviewed.
TL;DR: This work describes a pathway by which sodium enters dendritic cells (DCs) through amiloride-sensitive channels including the alpha and gamma subunits of the epithelial sodium channel and the sodium hydrogen exchanger 1.
TL;DR: MIAT is identified as the first pro-fibrotic lncRNA in heart and unraveled the role of MIAT in the pathogenesis of MI, promising that normalization of MI AT level may prove to be a therapeutic option for the treatment of MI-induced cardiac fibrosis and the associated cardiac dysfunction.
Abstract: A long non-coding RNA (lncRNA), named myocardial infarction associated transcript (MIAT), has been documented to confer risk of myocardial infarction (MI). The aim of this study is to elucidate the pathophysiological role of MIAT in regulation of cardiac fibrosis. In a mouse model of MI, we found that MIAT was remarkably up-regulated, which was accompanied by cardiac interstitial fibrosis. MIAT up-regulation in MI was accompanied by deregulation of some fibrosis-related regulators: down-regulation of miR-24 and up-regulation of Furin and TGF-β1. Most notably, knockdown of endogenous MIAT by its siRNA reduced cardiac fibrosis and improved cardiac function and restored the deregulated expression of the fibrosis-related regulators. In cardiac fibroblasts treated with serum or angiotensin II, similar up-regulation of MIAT and down-regulation of miR-24 were consistently observed. These changes promoted fibroblasts proliferation and collagen accumulation, whereas knockdown of MIAT by siRNA or overexpression of miR-24 with its mimic abrogated the fibrogenesis. Our study therefore has identified MIAT as the first pro-fibrotic lncRNA in heart and unraveled the role of MIAT in the pathogenesis of MI. These findings also promise that normalization of MIAT level may prove to be a therapeutic option for the treatment of MI-induced cardiac fibrosis and the associated cardiac dysfunction.
TL;DR: The overall evidence emerging from both clinical trials and real world registry is in favor of a protective effect of metformin with respect to both coronary events and progression to heart failure.
Abstract: Background Metformin, the eldest and most widely used glucose lowering drug, is likely to be effective also on cardiac and vascular disease prevention. Nonetheless, uncertainty still exists with regard to its effects on the cardiovascular system as a whole and specifically on the myocardium, both at the organ and cellular levels. Methods We reviewed the available data on the cardiac and vascular effects of metformin, encompassing both in vitro, either tissue or isolated organ, and in vivo studies in experimental animals and humans, as well as the evidence generated by major clinical trials. Results At the cellular level metformin’s produces both AMP-activated kinase (AMPK) dependent and independent effects. At the systemic level, possibly also through other pathways, this drug improves endothelial function, protects from oxidative stress and inflammation, and from the negative effects of angiotensin II. On the myocardium it attenuates ischemia-reperfusion injury and prevents adverse remodeling induced by humoral and hemodynamic factors. The effects on myocardial cell metabolism and contractile function being not evident at rest or in more advanced stages of cardiac dysfunction, could be relevant during transient ischemia, during an acute increase in workload and in the early stages of diabetic/hypertensive cardiomyopathy as confirmed by few small clinical trials and some observational studies. The overall evidence emerging from both clinical trials and real world registry is in favor of a protective effect of metformin with respect to both coronary events and progression to heart failure. Conclusions Given this potential, its efficacy and its safety (and also its low cost) metformin remains the central pillar of the therapy of diabetes.
TL;DR: The sodium-hydrogen exchanger may play a central role in the interplay of diabetes mellitus and heart failure, contribute to the physiological and clinical progression of both diseases, and explain certain drug–drug and drug–disease interactions that have been reported in large-scale randomized clinical trials.
Abstract: The mechanisms underlying the progression of diabetes mellitus and heart failure are closely intertwined, such that worsening of one condition is frequently accompanied by worsening of the other; the degree of clinical acceleration is marked when the 2 coexist. Activation of the sodium-hydrogen exchanger in the heart and vasculature (NHE1 isoform) and the kidneys (NHE3 isoform) may serve as a common mechanism that links both disorders and may underlie their interplay. Insulin insensitivity and adipokine abnormalities (the hallmarks of type 2 diabetes mellitus) are characteristic features of heart failure; conversely, neurohormonal systems activated in heart failure (norepinephrine, angiotensin II, aldosterone, and neprilysin) impair insulin sensitivity and contribute to microvascular disease in diabetes mellitus. Each of these neurohormonal derangements may act through increased activity of both NHE1 and NHE3. Drugs used to treat diabetes mellitus may favorably affect the pathophysiological mechanisms of heart failure by inhibiting either or both NHE isoforms, and drugs used to treat heart failure may have beneficial effects on glucose tolerance and the complications of diabetes mellitus by interfering with the actions of NHE1 and NHE3. The efficacy of NHE inhibitors on the risk of cardiovascular events may be enhanced when heart failure and glucose intolerance coexist and may be attenuated when drugs with NHE inhibitory actions are given concomitantly. Therefore, the sodium-hydrogen exchanger may play a central role in the interplay of diabetes mellitus and heart failure, contribute to the physiological and clinical progression of both diseases, and explain certain drug-drug and drug-disease interactions that have been reported in large-scale randomized clinical trials.
TL;DR: Dysregulation of brain RAS plays a major role in aging-related changes and neurodegeneration by exacerbation of oxidative stress (OS) and neuroinflammation, which may be attenuated by pharmacological manipulation of RAS components.
Abstract: Microglia can transform into proinflammatory/classically activated (M1) or anti-inflammatory/alternatively activated (M2) phenotypes following environmental signals related to physiological conditions or brain lesions. An adequate transition from the M1 (proinflammatory) to M2 (immunoregulatory) phenotype is necessary to counteract brain damage. Several factors involved in microglial polarization have already been identified. However, the effects of the brain renin-angiotensin system (RAS) on microglial polarization are less known. It is well known that there is a “classical” circulating RAS; however, a second RAS (local or tissue RAS) has been observed in many tissues, including brain. The locally formed angiotensin is involved in local pathological changes of these tissues and modulates immune cells, which are equipped with all the components of the RAS. There are also recent data showing that brain RAS plays a major role in microglial polarization. Level of microglial NADPH-oxidase (Nox) activation is a major regulator the shift between M1/proinflammatory and M2/immunoregulatory microglial phenotypes so that Nox activation promotes the proinflammatory and inhibits the immunoregulatory phenotype. Angiotensin II, via its type 1 receptor (AT1), is a major activator of the NADPH-oxidase complex, leading to pro-oxidative and pro-inflammatory effects. However, these effects are counteracted by a RAS opposite arm constituted by Angiotensin II/AT2 receptor signaling and Angiotensin 1-7/Mas receptor signaling. In addition, activation of renin-prorenin receptors may contribute to activation of the proinflammatory phenotype. Aged brains showed upregulation of AT1 and downregulation of AT2 receptor expression, which may contribute to a pro-oxidative pro-inflammatory state and the increase in neuron vulnerability. Several recent studies have shown interactions between the brain RAS and different factors involved in microglial polarization, such as estrogens, Rho kinase, insulin-like growth factor-1, tumor necrosis factor α, iron, peroxisome proliferator-activated receptor gamma, and toll-like receptors. Metabolic reprogramming has recently been involved in the regulation of the neuroinflammatory response. Interestingly, we have recently observed a mitochondrial RAS, which is altered in aged brains. In conclusion, dysregulation of brain RAS plays a major role in aging-related changes and neurodegeneration by exacerbation of oxidative stress and neuroinflammation, which may be attenuated by pharmacological manipulation of RAS components
TL;DR: The present study demonstrates that estrogen affects the human atrial myocardium and mediates protective actions through estrogen receptors-(ER) dependent signaling, and demonstrates the existence of protective effects of estrogen in atrial tissue from elderly men which are at least in part, mediated by the regulation of local RAS homeostasis.
Abstract: Data from animal experiments and clinical investigations suggest that components of the renin-angiotensin system are markedly affected by sex hormones. However, whether estrogen affects human atrial myocardium has not been investigated yet. In this study, we determined the effects of estrogen on key components of atrial renin-angiotensin system: angiotensin-converting enzyme, responsible for generation of angiotensin II and angiotensin-converting enzyme 2, counteracting majority of AngII effects, and different renin-angiotensin system receptors, AT1R, AT2R, and MAS. First, the expression levels of estrogen receptors mRNA were determined in right atrial appendages obtained from patients undergoing heart surgery. The amounts of estrogen receptor α and estrogen receptor β mRNA were similar between women ( n = 14) and men ( n = 10). Atrial tissue slices (350 µm) were prepared from male donors which were exposed to estrogen (1-100 nM; n = 21) or stimulated at 4 Hz for 24 h in the presence or absence of 100 nM estrogen ( n = 16), respectively. The administration of estrogen did not change mRNA levels of estrogen receptors, but activated MAP kinases, Erk1/2. Furthermore, estrogen increased the amounts of angiotensin-converting enzyme 2-mRNA (1.89 ± 0.23; P < 0.05) but reduced that of angiotensin-converting enzyme-mRNA (0.78 ± 0.07, P < 0.05). In addition, the transcript levels of AT2R and MAS were upregulated by estrogen. Pacing of tissue slices significantly increased the angiotensin-converting enzyme/angiotensin-converting enzyme 2 ratio at both the mRNA and protein level. During pacing, administration of estrogen substantially lowered the angiotensin-converting enzyme/angiotensin-converting enzyme 2 ratio at the transcript (0.92 ± 0.21 vs. 2.12 ± 0.27 at 4 Hz) and protein level (0.94 ± 0.20 vs. 2.14 ± 0.3 at 4 Hz). Moreover, estrogen elicited anti-inflammatory and anti-oxidative effects on renin-angiotensin system-associated downstream effectors such as pro-oxidative LOX-1 and pro-inflammatory ICAM-1. An antagonist of estrogen receptor α reversed these anti-inflammatory and anti-oxidative effects of estrogen significantly. Overall, our results demonstrated that estrogen modifies the local renin-angiotensin system homeostasis and achieves protective effects in atrial myocardium from elderly men. Impact statement The present study demonstrates that estrogen affects the human atrial myocardium and mediates protective actions through estrogen receptors-(ER) dependent signaling. Estrogen substantially modulates the local RAS via downregulation of ACE and simultaneous upregulation of ACE2, AT2R and MAS expression levels. This is indicative of a shift of the classical RAS/ACE axis to the alternative, protective RAS/ACE2 axis. In support of this view, estrogen attenuated the expression of RAS-associated downstream effectors, LOX-1, and ICAM-1. A specific antagonist of ERα reversed the anti-inflammatory and anti-oxidative effects of estrogen in paced and non-paced atrial tissue slices. In summary, our data demonstrate the existence of protective effects of estrogen in atrial tissue from elderly men which are at least in part, mediated by the regulation of local RAS homeostasis.
TL;DR: A novel and unique aircraft noise stress model with increased blood pressure and vascular dysfunction associated with oxidative stress is established, enabling future studies of molecular mechanisms, mitigation strategies, and pharmacological interventions to protect from noise-induced vascular damage.
Abstract: Aims Epidemiological studies indicate that traffic noise increases the incidence of coronary artery disease, hypertension and stroke. The underlying mechanisms remain largely unknown. Field studies with nighttime noise exposure demonstrate that aircraft noise leads to vascular dysfunction, which is markedly improved by vitamin C, suggesting a key role of oxidative stress in causing this phenomenon. Methods and results We developed a novel animal model to study the vascular consequences of aircraft noise exposure. Peak sound levels of 85 and mean sound level of 72 dBA applied by loudspeakers for 4 days caused an increase in systolic blood pressure, plasma noradrenaline and angiotensin II levels and induced endothelial dysfunction. Noise increased eNOS expression but reduced vascular NO levels because of eNOS uncoupling. Noise increased circulating levels of nitrotyrosine, interleukine-6 and vascular expression of the NADPH oxidase subunit Nox2, nitrotyrosine-positive proteins and of endothelin-1. FACS analysis demonstrated an increase in infiltrated natural killer-cells and neutrophils into the vasculature. Equal mean sound pressure levels of white noise for 4 days did not induce these changes. Comparative Illumina sequencing of transcriptomes of aortic tissues from aircraft noise-treated animals displayed significant changes of genes in part responsible for the regulation of vascular function, vascular remodelling, and cell death. Conclusion We established a novel and unique aircraft noise stress model with increased blood pressure and vascular dysfunction associated with oxidative stress. This animal model enables future studies of molecular mechanisms, mitigation strategies, and pharmacological interventions to protect from noise-induced vascular damage.
TL;DR: Plasma angiotensin peptides represent a dynamic network that is altered in HF and in response to rhACE2, and an increased plasma Ang-(1-7) level is linked to ACE inhibitor use, whereas acute HF reduced Ang-2 levels and suppressed the Ang-7/Ang II ratio.
TL;DR: Results indicate that NLRP3 inflammasome activation response to histone acetylation and NFκB activation contributes to VSMC phenotype switching and proliferation and vascular remodeling in hypertension.
Abstract: Inflammation is involved in pathogenesis of hypertension. NLRP3 inflammasome activation is a powerful mediator of inflammatory response via caspase-1 activation. The present study was designed to determine the roles and mechanisms of NLRP3 inflammasome in phenotypic modulation and proliferation of vascular smooth muscle cells (VSMCs) in hypertension. Experiments were conducted in spontaneously hypertensive rats (SHR) and primary aortic VSMCs. NLRP3 inflammasome activation was observed in the media of aorta in SHR and in the VSMCs from SHR. Knockdown of NLRP3 inhibited inflammasome activation, VSMC phenotypic transformation and proliferation in SHR-derived VSMCs. Increased NFκB activation, histone acetylation and histone acetyltransferase expression were observed in SHR-derived VSMCs and in media of aorta in SHR. Chromatin immunoprecipitation analysis revealed the increased histone acetylation, p65-NFκB and Pol II occupancy at the NLRP3 promoter in vivo and in vitro. Inhibition of NFκB with BAY11-7082 or inhibition of histone acetyltransferase with curcumin prevented the NLRP3 inflammasome activation, VSMC phenotype switching and proliferation in VSMCs from SHR. Moreover, curcumin repressed NFκB activation. Silencing of NLRP3 gene ameliorated hypertension, vascular remodeling, NLRP3 inflammasome activation and phenotype switching in the aorta of SHR. These results indicate that NLRP3 inflammasome activation response to histone acetylation and NFκB activation contributes to VSMC phenotype switching and proliferation and vascular remodeling in hypertension.
TL;DR: An up to date overview of essential AT1 receptor signaling events and their functional significances in the cardiovascular system is summarized.
TL;DR: The ability to produce ACE2 is severely impaired, resulting in dominant ACE activities during ARDS and/or ventilatorinduced lung injury (VILI) and increasing evidence has emerged that reactive oxygen species (ROS), especially nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and hydrogen peroxide (H2O2), act as upstream regulators of RAS and ACE activity in various cells and tissues.
Abstract: Acute respiratory distress syndrome (ARDS) is a devastating inflammatory lung disorder that is frequently associated with multiple organ dysfunction leading to high mortality. The mechanisms underlying ARDS are multifactorial, and are thought to include the reninangiotensin system (RAS) [1, 2]. The RAS is a coordinated complex hormonal cascade that is composed of angiotensinogen, angiotensinconverting enzyme (ACE) and its homolog angiotensin converting enzyme 2 (ACE2), and angiotensin II (Ang II) type 1 and type 2 receptors (AT1, AT2). ACE cleaves the decapeptide Ang I into the octapeptide Ang II, while ACE2 cleaves a single residue from Ang II to generate Ang 1-7, which in turn blocks Ang II and inhibits ACE [3]. Thus, the ACE2 axis negatively regulates the ACE axis. Great attention has been focused on the role of the RAS in blood pressure homeostasis and cardiovascular function, but there is also increasing interest in understanding the pathophysiological role of the RAS in lung. While only 20% of capillary endothelial cells in all other organs, including the heart, express ACE, it is detectable in the entire capillary network of the alveoli in human lung [4]. Therefore, conversion of Ang I to Ang II can readily occur in the lung by abundant ACE in pulmonary vessels. This may contribute to rapid responses of vasoconstriction in the pulmonary circulation and low blood flow, leading to ventilation/perfusion mismatch in conditions such as tissue hypoxia. On the other hand, ACE2 is primarily produced in Clara cells and type II alveolar epithelial cells [5] and epithelial injury is a critical event in the development of ARDS in humans; thus, the ability to produce ACE2 is severely impaired, resulting in dominant ACE activities during ARDS and/or ventilatorinduced lung injury (VILI) [1, 6]. Increasing evidence has emerged that reactive oxygen species (ROS), especially nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and hydrogen peroxide (H2O2), act as upstream regulators of RAS and ACE activity in various cells and tissues [7]. The RAS in turn induces production of ROS that function as intracellular and intercellular second messengers to modulate many downstream signaling cascades. In normal conditions, the interplay between the ROS and RAS is important in maintaining pulmonary function and integrity. Under ARDS and VILI conditions, this vicious cycle feedback loop contributes to lung injury and remodeling through oxidative damage [6, 8]. Midkine (MK), a heparin-binding growth factor, has been recently demonstrated as a novel modulator of RAS in the context of ARDS and VILI [6]. The plasma concentration of MK increased dramatically in patients with ARDS [6], and an up-regulation of MK in lung epithelial cells is reported in response to cyclic mechanical stress [6]. Exposure to MK protein results in an enhanced ACE expression in primary human lung cells [9]. MK has been shown to stimulate the RAS by acting as an upstream signaling molecule of Ang II and mediates lung–kidney crosstalk leading to development of RASassociated fibrosis [9]. The RAS—specifically Ang II via AT1 and AT2 receptors—has a number of effects: (1) induction of pulmonary vasoconstriction and vascular permeability in response to hypoxia resulting in pulmonary edema; (2) stimulation of the lung production of inflammatory cytokines directly and indirectly by targeting bradykinin; (3) acceleration of the Fas-induced apoptosis in alveolar * Correspondence: zhangh@smh.ca Keenan Research Centre for Biomedical Science, St. Michael’s Hospital, Room 619, LKSKI, 30 Bond Street, Toronto, ON M5B 1W8, Canada Interdepartmental Division of Critical Care Medicine, Departments of Anesthesia and Physiology, University of Toronto, Toronto, ON, Canada
TL;DR: It is demonstrated that angiotensin II type 1 receptors promote ADAM17-mediated ACE2 shedding in the brain of hypertensive patients, leading to a loss in compensatory activity during neurogenic hypertension.
Abstract: Rationale: Neurogenic hypertension is characterized by an increase in sympathetic activity and often resistance to drug treatments We previously reported that it is also associated with a reduction of angiotensin-converting enzyme type 2 (ACE2) and an increase in a disintegrin and metalloprotease 17 (ADAM17) activity in experimental hypertension In addition, while multiple cells within the central nervous system have been involved in the development of neurogenic hypertension, the contribution of ADAM17 has not been investigated Objective: To assess the clinical relevance of this ADAM17-mediated ACE2 shedding in hypertensive patients and further identify the cell types and signaling pathways involved in this process Methods and Results: Using a mass spectrometry-based assay, we identified ACE2 as the main enzyme converting angiotensin II into angiotensin-(1–7) in human cerebrospinal fluid We also observed an increase in ACE2 activity in the cerebrospinal fluid of hypertensive patients, which was correlated with systolic blood pressure Moreover, the increased level of tumor necrosis factor-α in those cerebrospinal fluid samples confirmed that ADAM17 was upregulated in the brain of hypertensive patients To further assess the interaction between brain renin–angiotensin system and ADAM17, we generated mice lacking angiotensin II type 1 receptors specifically on neurons Our data reveal that despite expression on astrocytes and other cells types in the brain, ADAM17 upregulation during deoxycorticosterone acetate–salt hypertension occurs selectively on neurons, and neuronal angiotensin II type 1 receptors are indispensable to this process Mechanistically, reactive oxygen species and extracellular signal-regulated kinase were found to mediate ADAM17 activation Conclusions: Our data demonstrate that angiotensin II type 1 receptors promote ADAM17-mediated ACE2 shedding in the brain of hypertensive patients, leading to a loss in compensatory activity during neurogenic hypertension
TL;DR: This review highlights recent advances in defining the regulation and function of intrarenal RAS as a unique entity separate from systemic angiotensin II generation.
Abstract: The renin-angiotensin system (RAS) has a pivotal role in the maintenance of extracellular volume homeostasis and blood pressure through complex mechanisms. Apart from the well known systemic RAS, occurrence of a local RAS has been documented in multiple tissues, including the kidney. A large body of recent evidence from pharmacologic and genetic studies, particularly those using various transgenic approaches to manipulate intrarenal levels of RAS components, has established the important role of intrarenal RAS in hypertension. Recent studies have also begun to unravel the molecular mechanisms that govern intrarenal RAS activity. This local system is under the control of complex regulatory networks consisting of positive regulators of (pro)renin receptor, Wnt/β-catenin signaling, and PGE2/PGE2 receptor EP4 subtype, and negative regulators of Klotho, vitamin D receptor, and liver X receptors. This review highlights recent advances in defining the regulation and function of intrarenal RAS as a unique entity separate from systemic angiotensin II generation.
TL;DR: The findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture.
Abstract: Rationale: Atherosclerosis and aneurysms are leading causes of mortality worldwide. MicroRNAs (miRs) are key determinants of gene and protein expression, and atypical miR expression has been associated with many cardiovascular diseases; although their contributory role to atherosclerotic plaque and abdominal aortic aneurysm stability are poorly understood. Objective: To investigate whether miR-181b regulates tissue inhibitor of metalloproteinase-3 expression and affects atherosclerosis and aneurysms. Methods and Results: Here, we demonstrate that miR-181b was overexpressed in symptomatic human atherosclerotic plaques and abdominal aortic aneurysms and correlated with decreased expression of predicted miR-181b targets, tissue inhibitor of metalloproteinase-3, and elastin. Using the well-characterized mouse atherosclerosis models of Apoe−/− and Ldlr−/−, we observed that in vivo administration of locked nucleic acid anti-miR-181b retarded both the development and the progression of atherosclerotic plaques. Systemic delivery of anti-miR-181b in angiotensin II– infused Apoe−/− and Ldlr−/− mice attenuated aneurysm formation and progression within the ascending, thoracic, and abdominal aorta. Moreover, miR-181b inhibition greatly increased elastin and collagen expression, promoting a fibrotic response and subsequent stabilization of existing plaques and aneurysms. We determined that miR-181b negatively regulates macrophage tissue inhibitor of metalloproteinase-3 expression and vascular smooth muscle cell elastin production, both important factors in maintaining atherosclerotic plaque and aneurysm stability. Validation studies in Timp3−/− mice confirmed that the beneficial effects afforded by miR-181b inhibition are largely tissue inhibitor of metalloproteinase-3 dependent, while also revealing an additional protective effect through elevating elastin synthesis. Conclusions: Our findings suggest that the management of miR-181b and its target genes provides therapeutic potential for limiting the progression of atherosclerosis and aneurysms and protecting them from rupture.
TL;DR: This study will focus on the immunological functions of CD74 molecules and its roles in immune-relevant disorders.
Abstract: CD74 (MHC class II invariant chain, Ii) is a non-polymorphic type II transmembrane glycoprotein. It is clear that, in addition to be an MHC class II chaperone, CD74 has a diversity of biological functions in physiological and pathological situations. CD74 also participates in other non-MHC II protein trafficking, such as angiotensin II type I receptor. In addition, CD74 is a cell membrane high-affinity receptor for macrophage migration inhibitory factor (MIF), D-dopachrome tautomerase (D-DT/MIF-2) and bacterial proteins. CD74 also regulates T-cell and B-cell developments, dendritic cell (DC) motility, macrophage inflammation, and thymic selection. The activation of receptor complex CD74/CD44 may lead to multiple intracellular signal pathways, such as the activation of the extracellular signal regulated kinase (ERK) 1 and 2, the PI3K-Akt signal transduction cascade, NFκB, and the AMP-activated protein kinase (AMPK) pathway. CD74 plays important roles in many inflammatory diseases, such as liver fibrosis, type I diabetes, systemic lupus erythematosus, and Alzheimer disease. In this study, we will focus on the immunological functions of CD74 molecules and its roles in immune-relevant disorders.
TL;DR: The relevance and recent advances of current animal AAA models are discussed, including genetic or acquired defects in extracellular matrix, loss of vascular smooth muscle cells, and innate or adaptive immune response.
Abstract: Human abdominal aortic aneurysm (AAA) pathophysiology is not yet completely understood. In conductance arteries, the insoluble extracellular matrix, synthesized by vascular smooth muscle cells, ass...
TL;DR: In this article, the authors show that thirst and salt appetite are driven by distinct groups of angiotensin II receptor type 1a-positive excitatory neurons in the subfornical organ.
Abstract: Body fluid conditions are continuously monitored in the brain to regulate thirst and salt-appetite sensations. Angiotensin II drives both thirst and salt appetite; however, the neural mechanisms underlying selective water- and/or salt-intake behaviors remain unknown. Using optogenetics, we show that thirst and salt appetite are driven by distinct groups of angiotensin II receptor type 1a-positive excitatory neurons in the subfornical organ. Neurons projecting to the organum vasculosum lamina terminalis control water intake, while those projecting to the ventral part of the bed nucleus of the stria terminalis control salt intake. Thirst-driving neurons are suppressed under sodium-depleted conditions through cholecystokinin-mediated activation of GABAergic neurons. In contrast, the salt appetite-driving neurons were suppressed under dehydrated conditions through activation of another population of GABAergic neurons by Nax signals. These distinct mechanisms in the subfornical organ may underlie the selective intakes of water and/or salt and may contribute to body fluid homeostasis.
TL;DR: The RAS components are present in the extrarenal tissues including ocular tissue and have an imperative role in the ocular pathophysiology and clinical studies are needed to show the role of therapeutic modalities targeting RAS in the treatment of different ocular disorders.
Abstract: Purpose To review current literature on the renin-angiotensin system (RAS)-mediated pathogenic mechanisms and therapeutic targets in ocular diseases. Methods A comprehensive literature survey was performed on PubMed, Scopus, and Google Scholar databases published from 1977 to 2016. The search terms were a RAS, angiotensin, angiotensin receptor, prorenin, pro (renin) receptor, angiotensin converting enzyme inhibitor, angiotensin receptor blocker associated with ocular disorders like cataract, glaucoma, diabetic retinopathy (DR), macular degeneration, and uveitis. Articles were reviewed on the basis of the association between ocular disorders and RAS and relevant articles were discussed. Results The literature revealed that the individual RAS components including renin, angiotensins, angiotensin converting enzymes, and RAS receptors have been expressed in the specific ocular tissues like retina, choroid, and ciliary body. The activation of both circulatory and local RAS potentiate the various inflammatory and angiogenic signaling molecules, including vascular endothelial growth factor (VEGF), extracellular signal-regulated kinase, and advanced glycation end products (AGE) in the ocular tissues and leads to several blinding disorders like DR, glaucoma, and macular degeneration. The classical and newer RAS inhibitors have illustrated protective effects on blinding disorders, including DR, glaucoma, macular degeneration, uveitis, and cataract. Conclusions The RAS components are present in the extrarenal tissues including ocular tissue and have an imperative role in the ocular pathophysiology. The clinical studies are needed to show the role of therapeutic modalities targeting RAS in the treatment of different ocular disorders.
TL;DR: A continuum of renin-independent aldosteronism and mineralocorticoid receptor activity in normotension that ranges from subtle to overtly dysregulated and autonomous is indicated.
Abstract: Primary aldosteronism is a severe form of autonomous aldosteronism. Milder forms of autonomous and renin-independent aldosteronism may be common, even in normotension. We characterized aldosterone secretion in 210 normotensives who had suppressed plasma renin activity ( 12 μg/24 hours with urinary sodium excretion >200 mmol/24 hours. Across the population, there were strong and significant associations between higher aldosterone excretion rate and higher urinary potassium excretion, higher angiotensin II-stimulated aldosterone, and lower plasma renin activity, suggesting a continuum of renin-independent aldosteronism and mineralocorticoid receptor activity. Autonomous aldosterone secretion that fulfilled confirmatory criteria for primary aldosteronism was detected in 29 participants (14%). Normotensives with evidence suggestive of confirmed primary aldosteronism had higher 24-hour urinary aldosterone excretion rate (20.2±12.2 versus 6.2±2.9 μg/24 hours; P<0.001) as expected, but also higher angiotensin II-stimulated aldosterone (12.4±8.6 versus 6.6±4.3 ng/dL; P<0.001) and lower 24-hour urinary sodium-to-potassium excretion (2.69±0.65 versus 3.69±1.50 mmol/mmol; P=0.001); however, there were no differences in age, aldosterone-to-renin ratio, blood pressure, or renal plasma flow between the 2 groups. These findings indicate a continuum of renin-independent aldosteronism and mineralocorticoid receptor activity in normotension that ranges from subtle to overtly dysregulated and autonomous. Longitudinal studies are needed to determine whether this spectrum of autonomous aldosterone secretion contributes to hypertension and cardiovascular disease.