Angiotensin II, from vasoconstrictor to growth factor: a paradigm shift.
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ABSTRACT:
SUBMITTER: Vukelic S
PROVIDER: S-EPMC3985550 | biostudies-literature | 2014 Feb
REPOSITORIES: biostudies-literature
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Angiotensin II, from vasoconstrictor to growth factor: a paradigm shift.
Vukelic Sasa S Griendling Kathy K KK
Circulation research 20140201 5
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Project description:Both the activation of the renin angiotensin aldosterone system (RAAS) and elevations of circulating Fibroblast Growth Factor-23 (FGF-23) have been implicated in the pathogenesis of left ventricular hypertrophy (LVH) in chronic kidney disease. To investigate potential cross-talk between RAAS and FGF-23, we administered angiotensin II (Ang II) to wild-type rodents and the Hyp mouse model of excess FGF-23. Ang II administration for four weeks to wild-type rodents resulted in significant increases in systolic blood pressure and LVH. Unexpectedly, FGF-23 circulating levels were increased by 1.5-1.7 fold in Ang II treated animals. In addition, Ang II treatment increased expression of FGF-23 message levels in bone, the predominant tissue for FGF-23 production, and induced expression of FGF-23 and its co-receptor α-Klotho in the heart, which normally does not express FGF-23 or α-Klotho in physiologically relevant levels. Hyp mice with elevated FGF-23 exhibited increased blood pressure and LVH at baseline. Ang II administration to Hyp mice resulted further increments in blood pressure and left ventricular hypertrophy, consistent with additive cardiovascular effects. These findings suggest that FGF-23 may participate in unexpected systemic and paracrine networks regulating hemodynamic and myocardial responses.
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Project description:ObjectiveChanges in maternal serum concentration of placental growth factor (PlGF) and vascular response to intravascular infusion of Angiotensin II (Ang II) follow a bell-shaped curve pattern during gestation. This study evaluates the effects of PlGF and soluble vascular endothelial growth factor receptor-1 (sFlt-1) on responses of human uterine arteries (UA) to Ang II.DesignExperimental.SettingBaylor College of Medicine and Texas Children's Hospital-Pavilion for Women.SampleUterine arteries samples (n = 14) were obtained from normotensive women undergoing caesarean hysterectomy at ≥32 weeks.MethodsUterine arteries rings were incubated with (1) Krebs solution; (2) PlGF at 1.45, 14.5, and 500 pg/ml; (3) sFlt-1 at 2 ng/ml; and (4) a combination of sFlt-1, and PlGF. Dose-contraction responses to Ang II were determined in UA rings incubated in the above-mentioned conditions. Responses were also measured in presence of L-NAME or inhibitors of endothelium-derived hyperpolarising factor: apamine and charybdotoxin. The t-test was used for comparisons.Main outcome measureChanges in vascular reactivity of UA rings.ResultsPlGF blunted (P = 0.03) and sFlt-1 increased (P <0.01) the UA maximum responses to Ang II. A combination of sFlt-1 and PlGF blunted UA responses to Ang II (P < 0.05). l-NAME, apamine, and charybdotoxin reversed the relaxation effects of PlGF on UA responses to Ang II (P < 0.05).ConclusionsPlGF contributes to the blunted vascular response to Angiotensin II during normotensive pregnancies and sFlt-1 appears to attenuate this effect. PlGF and sFlt-1 may contribute to the regulation of vascular tone during pregnancy by altering the vascular response to Angiotensin II.FundingBaylor College of Medicine.Tweetable abstractPlacental growth factor and soluble vascular endothelial growth factor receptor-1 modulate the uterine artery response to Angiotensin II in normotensive pregnant women.
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Project description:Angiotensin II (Ang II) promotes hepatic fibrosis by increasing extracellular matrix (ECM) synthesis. Connective tissue growth factor (CTGF) plays a crucial role in the pathogenesis of hepatic fibrosis and emerges as downstream of the profibrogenic cytokine transforming growth factor-β (TGF-β). We aimed to investigate the molecular events that lead from the Ang II receptor to CTGF upregulation in human hepatic stellate cells, a principal fibrogenic cell type. Ang II produced an early, AT1 receptor-dependent stimulation of CTGF expression and induced a rapid activation of PKC and its downstream p38 MAPK, thereby activating a nuclear factor-κB (NF-κB) and Smad2/3 cross-talk pathway. Chemical blockade of NF-κB and Smad2/3 signaling synergistically diminished Ang II-mediated CTGF induction and exhibited an additive effect in abrogating the ECM accumulation caused by Ang II. Furthermore, we demonstrated that CTGF expression was essential for Ang II-mediated ECM synthesis. Interestingly, the ability of dephosphorylated, but not phosphorylated JNK to activate Smad2/3 signaling revealed a novel role of JNK in Ang II-mediated CTGF overexpression. These results suggest that Ang II induces CTGF expression and ECM accumulation through a special TGF-β-independent interaction between the NF-κB and Smad2/3 signals elicited by the AT1/PKCα/p38 MAPK pathway.
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Project description:In the last hundred years surgery has experienced a dramatic increase of scientific knowledge and innovation. The need to consider best available evidence and to apply technical innovations, such as minimally invasive approaches, challenges the surgeon both intellectually and manually. In order to overcome this challenge, computer scientists and surgeons within the interdisciplinary field of "cognitive surgery" explore and innovate new ways of data processing and management. This article gives a general overview of the topic and outlines selected pre-, intra- and postoperative applications. It explores the possibilities of new intelligent devices and software across the entire treatment process of patients ending in the consideration of an "Intelligent Hospital" or "Hospital 4.0", in which the borders between IT infrastructures, medical devices, medical personnel and patients are bridged by technology. Thereby, the "Hospital 4.0" is an intelligent system, which gives the right information, at the right time, at the right place to the individual stakeholder and thereby helps to decrease complications and improve clinical processes as well as patient outcome.
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Project description:The present study examined whether 20-hydroxyeicosatetraenoic acid (HETE) contributes to the vasoconstrictor effect of angiotensin II (ANG II) in renal microvessels by preventing activation of the large conductance Ca(2+)-activated K(+) channel (KCa) in vascular smooth muscle (VSM) cells. ANG II increased the production of 20-HETE in rat renal microvessels. This response was attenuated by the 20-HETE synthesis inhibitors, 17-ODYA and HET0016, a phospholipase A2 inhibitor AACOF3, and the AT1 receptor blocker, Losartan, but not by the AT2 receptor blocker, PD123319. ANG II (10(-11) to 10(-6) M) dose-dependently decreased the diameter of renal microvessels by 41 ± 5%. This effect was blocked by 17-ODYA. ANG II (10(-7) M) did not alter KCa channel activity recorded from cell-attached patches on renal VSM cells under control conditions. However, it did reduce the NPo of the KCa channel by 93.4 ± 3.1% after the channels were activated by increasing intracellular calcium levels with ionomycin. The inhibitory effect of ANG II on KCa channel activity in the presence of ionomycin was attenuated by 17-ODYA, AACOF3, and the phospholipase C (PLC) inhibitor U-73122. ANG II induced a peak followed by a steady-state increase in intracellular calcium concentration in renal VSM cells. 17-ODYA (10(-5) M) had no effect on the peak response, but it blocked the steady-state increase. These results indicate that ANG II stimulates the formation of 20-HETE in rat renal microvessels via the AT1 receptor activation and that 20-HETE contributes to the vasoconstrictor response to ANG II by blocking activation of KCa channel and facilitating calcium entry.
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Project description:Chronic hypoxia augments pressure- and agonist-induced pulmonary vasoconstriction through myofilament calcium sensitization. NADPH oxidases contribute to the development of pulmonary hypertension, and both epidermal growth factor receptor and Src kinases can regulate NADPH oxidase. We tested the hypothesis that Src-epidermal growth factor receptor (EGFR) signaling mediates enhanced vasoconstrictor sensitivity after chronic hypoxia through NADPH oxidase-derived superoxide generation. Protocols employed pharmacological inhibitors in isolated, pressurized rat pulmonary arteries to examine the contribution of a variety of signaling moieties to enhanced vascular tone after chronic hypoxia. Superoxide generation in pulmonary arterial smooth muscle cells was assessed using the fluorescent indicator dihydroethidium. Indices of pulmonary hypertension were measured in rats treated with the EGFR inhibitor gefitinib. Inhibition of NADPH oxidase, Rac1 (Ras-related C3 botulinum toxin substrate 1), and EGFR abolished pressure-induced pulmonary arterial tone and endothelin-1 (ET-1)-dependent calcium sensitization and vasoconstriction after chronic hypoxia. Consistently, chronic hypoxia augmented ET-1-induced superoxide production through EGFR signaling, and rats treated chronically with gefitinib displayed reduced right ventricular pressure and diminished arterial remodeling. Src kinases were also activated by ET-1 after chronic hypoxia and contributed to enhanced basal arterial tone and vasoconstriction in response to ET-1. A role for matrix metalloproteinase 2 to mediate Src-dependent EGFR activation is further supported by our findings. Our studies support a novel role for an Src kinase-EGFR-NADPH oxidase signaling axis to mediate enhanced pulmonary vascular smooth muscle Ca2+ sensitization, vasoconstriction, and pulmonary hypertension after chronic hypoxia.
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Project description:The mechanisms by which angiotensin II (AngII) elevates blood pressure and enhances end-organ damage seem to be distinct. However, the signal transduction cascade by which AngII specifically mediates vascular remodeling such as medial hypertrophy and perivascular fibrosis remains incomplete. We have previously shown that AngII-induced epidermal growth factor receptor (EGFR) transactivation is mediated by disintegrin and metalloproteinase domain 17 (ADAM17), and that this signaling is required for vascular smooth muscle cell hypertrophy but not for contractile signaling in response to AngII. Recent studies have implicated endoplasmic reticulum (ER) stress in hypertension. Interestingly, EGFR is capable of inducing ER stress. The aim of this study was to test the hypothesis that activation of EGFR and ER stress are critical components required for vascular remodeling but not hypertension induced by AngII. Mice were infused with AngII for 2 weeks with or without treatment of EGFR inhibitor, erlotinib, or ER chaperone, 4-phenylbutyrate. AngII infusion induced vascular medial hypertrophy in the heart, kidney and aorta, and perivascular fibrosis in heart and kidney, cardiac hypertrophy, and hypertension. Treatment with erlotinib as well as 4-phenylbutyrate attenuated vascular remodeling and cardiac hypertrophy but not hypertension. In addition, AngII infusion enhanced ADAM17 expression, EGFR activation, and ER/oxidative stress in the vasculature, which were diminished in both erlotinib-treated and 4-phenylbutyrate-treated mice. ADAM17 induction and EGFR activation by AngII in vascular cells were also prevented by inhibition of EGFR or ER stress. In conclusion, AngII induces vascular remodeling by EGFR activation and ER stress via a signaling mechanism involving ADAM17 induction independent of hypertension.
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