Abstract 067: Downregulation Of Vascular Factor-erythroid 2-related Factor-2 And Associated Antioxidant Enzymes In Hypertension

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Rheure A Lopes ◽  
Karla B Neves ◽  
Augusto Montezano ◽  
Rita Tostes ◽  
Rhian Touyz

Oxidative stress plays an important role in vascular dysfunction in hypertension. While mechanisms regulating vascular pro-oxidants are emerging, there is a paucity of information on anti-oxidant systems. Factor-erythroid 2-related factor-2 (Nrf2) is a master regulator of antioxidants and its role in hypertension remains elusive. We assessed vascular Nrf2 in hypertension by studying mesenteric vessels and VSMCs from WKY and SHRSP rats. Cells were stimulated with Ang II (10-7M) in the absence/presence of Nrf2 activators (bardoxolone or L-sulforaphane). ROS generation was assessed by chemiluminescence and amplex red. mRNA expression of anti-oxidant enzymes was assessed by qPCR. Nrf2 activity was analyzed by ELISA. Nrf2 activity was decreased in arteries (18%) and VSMCs (48%) in SHRSP (p<0.05 vs WKY). mRNA levels of antioxidant enzymes were reduced in SHRSP (SOD 1 (64%), catalase (60%), peroxiredoxin 1 (75%) and glutathione peroxidase (54%) Ang II increased Nrf2 activity in VSMCs from WKY (197%, 4h) and SHRSP (44%, 4h) (p<0.05, vs. vehicle). This was associated with increased antioxidant mRNA expression in WKY rats (SOD1-32%, catalase-42%, thioredoxin-71%, peroxiredoxin 1-90%, quinone oxidoreductase-84%; p<0.05 vs. vehicle) but not in SHRSP. ROS production and glucose-6-phosphate dehydrogenase (source of NADPH) mRNA levels were increased in SHRSP. Ang II-induced ROS generation in VSMCs from WKY and SHRSP was blocked by Nrf2 activators. Vascular function assessment, by wire myography, demonstrated that increased contractility (Emax Phe: WKY 113.4±5,67 vs. SHRSP 159.0±8.29) and decreased endothelial-dependent relaxation (Emax ACh: WKY 88.7±3.13 vs. SHRSP 74.7±3.25, p<0.05) in SHRSP were corrected by bardoxolone and L-sulforaphane. In conclusion, vascular dysfunction in SHRSP is associated with oxidative stress, decreased Nrf2 activity and reduced Nrf2-regulated antioxidant enzymes. A similar molecular phenotype was observed in Ang II-stimulated VSMCs. Nrf-2 agonists ameliorated vascular dysfunction in SHRSP. Our findings suggest that Nrf-2 downregulation may contribute to redox-sensitive vascular dysfunction and could be a therapeutic target in hypertension. Financial Support: ScWB.

2009 ◽  
Vol 21 (9) ◽  
pp. 122
Author(s):  
M. L. Jones ◽  
P. J. Mark ◽  
T. A. Mori ◽  
B. J. Waddell

Placental oxidative stress plays a key role in the pathophysiology of placenta-related disorders including preeclampsia. Protection from oxidative stress is provided by antioxidant enzymes which inactivate reactive oxygen species (ROS). The rat placenta consists of two major zones, the junctional (JZ) and labyrinth (LZ), and because only the LZ grows in late gestation we hypothesized it generates more ROS and thus requires greater antioxidant protection. Our previous studies on expression of the antioxidants superoxide dismutase (SOD)-1, SOD-2 and catalase support this hypothesis. Here, we extend these observations to include mRNA expression of SOD-3 and thioredoxin reductases (Txnrd-1, -2, -3) and activities of SOD, hydrogen peroxide (H2O2) scavenging and xanthine oxidase (XO). Placental oxidative damage was assessed by measurement of F2-isoprostanes and TBARS concentrations. We also measured the effects of maternal dexamethasone treatment, since glucocorticoid excess is known to induce oxidative damage in other tissues. Placentas were collected from untreated mothers on days 16 and 22 (term=day 23) and on day 22 after dexamethasone treatment from day 13 (1 μg/ml drinking water). SOD-3, Txnrd-1, -2, and -3 mRNAs were measured in JZ and LZ by qRT-PCR. F2-isoprostanes were measured by GC-MS and kit assays were used to measure TBARS and the activities of SOD, H2O2 scavenging and XO. In both placental zones, expression of SOD-3 and Txnrd-1 mRNAs and H2O2 scavenging activity decreased from day 16 to 22, whereas XO activity increased. Dexamethasone treatment increased H2O2 scavenging in both zones, but had no effect on SOD or XO activities or antioxidant mRNA expression. Despite predicted increases in placental ROS generation in late pregnancy and after dexamethasone, neither F2-isoprostanes nor TBARS were increased. These and our previous data suggest that endogenous protection against oxidative stress is abundant in the rat placenta and provides protection against potential oxidative insults including glucocorticoid excess.


Hypertension ◽  
2015 ◽  
Vol 66 (suppl_1) ◽  
Author(s):  
Francisco J Rios ◽  
Augusto C Montezano ◽  
Lucas Van Der Mey ◽  
Heather Y Small ◽  
Carmine Savoia ◽  
...  

VEGF/VEGFR inhibitors, used as anti-angiogenic drugs to treat cancer, induce severe hypertension. Molecular mechanisms whereby VEGF inhibitors cause hypertension are unclear, but nitric oxide (NO) and oxidative stress may be involved. We questioned whether reactive oxygen species (ROS) and Ang II, important regulators of vascular function in hypertension, also play a role in VEGF inhibitor-induced vascular dysfunction. Human microvascular endothelial cells (HMECs) were stimulated with vatalanib (VAT-VEGFR inhibitor) and gefitinib (GEF-EGFR inhibitor) in the absence/presence of Ang II. Activation of eNOS and MAPKs were assessed by immunoblotting. Antioxidant enzyme mRNA was analysed by qPCR. Microparticle levels were measured by flow cytometry. Endothelial microparticles, biomarkers of endothelial damage, tend to increase in subjects treated with VEGFR inhibitors. Phosphorylation of eNOS activation site (Ser1177) (28.3% ± 7.1) was decreased by VAT, while no changes were observed after exposure of HMECs to GEF (p<0.05). VAT decreased mRNA expression of Nox4 (0.5 ± 0.2) and H2O2-regulating antioxidants enzymes such as catalase (0.4 ± 0.1) and glutathione peroxidase (0.4 ± 0.1), while increased mRNA levels of Nox5 (3.35±1.1) (p<0.05 vs. veh). Ang II stimulation increased eNOS (171.2% ± 17.4) and ERK1/2 (177.5% ± 38.5) activation (p<0.05); all effects were blocked only by GEF. Inhibition of VEGFR also blocked Ang II effects on SOD1 (1.33 ± 0.1), HO-1 (1.6 ± 0.3) and NQO1 (1.6 ± 0.3) mRNA levels (p<0.05). In addition, Ang II increased Nox4 mRNA expression through VEGFR-dependent mechanisms. VEGFR1/2 and AT2R, but not AT1R, were expressed in HMEC. Ang II effects on eNOS phosphorylation were inhibited by PD123319 (AT2R antagonist) but not by losartan (AT1R antagonist). In conclusion, our data identify novel mechanisms whereby AngII, possibly through AT2R-dependent VEGFR transactivation, regulates eNOS activation, MAPK signalling and H2O2-related antioxidant enzymes. In addition to changes in NO availability, VEGFR inhibition may interfere with the redox status of endothelial cells, leading to vascular dysfunction and hypertension.


2020 ◽  
Vol 52 (07) ◽  
pp. 532-539 ◽  
Author(s):  
Chong-gui Zhu ◽  
Ying Luo ◽  
Hao Wang ◽  
Jun-Yi Li ◽  
Jie Yang ◽  
...  

AbstractAlthough glucagon-like peptide-1 (GLP-1) analogue has been reported to suppress oxidative stress in non-alcoholic fatty liver disease (NAFLD), an effective therapeutic agent for NAFLD is currently unavailable. Therefore, in this study, we aimed to investigate the protective effects of the GLP-1 analogue liraglutide against lipotoxicity-induced oxidative stress in HepG2 cells and to elucidate the underlying mechanisms. HepG2 cells were cultured for 48 hours and treated with a free fatty acid (FFA) mixture: FFA mixture and liraglutide or FFA mixture, liraglutide, and exendin (9–39). Lipid accumulation was examined by oil red O staining. Oxidative stress was assessed by measuring the levels of intracellular reactive oxygen species using 2′,7′-dichlorofluorescein diacetate and thiobarbituric acid-reactive substances, whereas antioxidant capacity was assessed by measuring the activity of superoxide dismutase and catalase. Expression of the nuclear factor erythroid-2-related factor 2 (NRF2) gene and the genes encoding antioxidant enzymes was analyzed using quantitative RT-PCR. Cellular and nuclear NRF2 expression levels were assessed using immunofluorescence cell staining and western blotting. Liraglutide treatment reduced high fat-induced lipid formation and the levels of oxidative stress markers and increased antioxidant enzyme activity in HepG2 cells. Liraglutide treatment increased the mRNA expression of NRF2 target genes, induced NRF2 nuclear translocation, and increased nuclear NRF2 levels without altering NRF2 mRNA expression. Collectively, these results indicate that liraglutide exhibits a protective effect against lipotoxicity-induced oxidative stress, possibly via modulation of NRF2 and expression of antioxidant enzymes in liver cells.


2016 ◽  
Vol 41 (2) ◽  
Author(s):  
Eyüp Altınöz ◽  
Cemal Ekici ◽  
Berna Özyazgan ◽  
Yılmaz Çiğremiş

AbstractObjective: The aim of the present study is to evaluate the effect of crocin on mRNA expression of antioxidant enzymes, SOD, CAT and GPX in the brain of the STZ induced diabetic rats.Methods: Thirty animals randomized in three groups containing ten animals in each group as follows; control (non-diabetic rats), DM (STZ-induced untreated diabetic rats), DM+crocin (STZ-induced diabetic rats treated with crocin,). Crocin was given at a dose of 20 mg/kg bw/day by gavage for 21 days.Results: STZ injection caused a significant increase in mRNA expression of antioxidant enzymes, SOD, CAT and GPX when compared to control group. Crocin given to diabetic rats significantly decreased mRNA expression of antioxidant enzymes, SOD, CAT and GPX when compared to DM group.Conclusion: The present study demonstrates that crocin can modulate mRNA expression of antioxidant enzymes, SOD, CAT and GPX and oxidative stress in the brain of the STZ induced diabetic rats.


Author(s):  
JaeSang Ko ◽  
Ji-Young Kim ◽  
Min Kyung Chae ◽  
Eun Jig Lee ◽  
Jin Sook Yoon

We examined endoplasmic reticulum (ER) stress-related gene expression in orbital tissues from patients with Graves’ orbitopathy (GO) and the effects of silencing protein kinase RNA-like endoplasmic reticulum kinase (PERK) in primary orbital fibroblast cultures to demonstrate the therapeutic potential of PERK-modulating agents in GO management. The expression of ER stress related genes in orbital tissue harvested from individuals with or without GO was studied using real-time polymerase chain reaction. The role of PERK in GO pathogenesis was examined through small-interfering RNA (siRNA)-mediated silencing in cultured primary orbital fibroblasts. Intracellular reactive oxygen species (ROS) levels induced in response to cigarette smoke extract (CSE) or hydrogen peroxide were measured using 5-(and 6)-carboxy-20,70-dichlorodihydrofluorescein diacetate staining and flow cytometry. Cells were stained with Oil Red O, and adipogenesis-related transcription factor expression was evaluated through western blotting after adipogenic differentiation. PERK, activating transcription factor 4 (ATF4), and CCAAT-enhancer-binding protein (C/EBP)-homologous protein(CHOP)mRNA levels were significantly higher in GO orbital tissues than in non-GO orbital tissues. PERK silencing inhibited CSE- or hydrogen peroxide-induced ROS generation. After adipogenic differentiation, GO orbital fibroblasts revealed decreased lipid droplets and downregulation of C/EBPα, C/EBPβ, and peroxisome proliferator-activator gamma (PPARγ) in PERK siRNA-transfected cells. The orbital tissues of patients with GO were exposed to chronic ER stress and subsequently exhibited enhanced unfolded protein response (especially through the PERK pathway). PERK silencing reduced oxidative stress and adipogenesis in GO orbital fibroblasts in vitro. Our results imply that PERK-modulating agents can potentially be used to manage GO.


2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Kayoko Miyata ◽  
Ryousuke Satou ◽  
L Gabriel Navar

Introduction: We have demonstrated that Ang II augments angiotensinogen (AGT) expression in rat preglomerular vascular smooth muscle cells (VSMCs). However, it is unclear if endothelial cells (ECs) are involved in augmentation of AGT in renal afferent arterioles. Hypothesis: We assessed the hypothesis that the ECs respond to paracrine signals that Ang II contribute to AGT augmentation in VSMCs. Objective: We established primary cultures of preglomerular ECs and examined the effects of Ang II and/or culture medium from ECs on AGT expression in preglomerular VSMCs. Methods and Results: We established primary cultures of preglomerular ECs, isolated from afferent arterioles of Sprague-Dawley rats. The cells were identified as ECs by being positive for a marker, CD34 and endothelial NOS and negative for alpha-SMA (a marker for VSMCs) and P4H-b (a marker for Fibroblasts) by immnostaining. The expression levels of AGT mRNA and renin mRNA in preglomerular ECs were examined by real-time RT-PCR. Ang II (100 pmol/L) increased AGT mRNA levels (1.34 +/- 0.16, by 100 pmol/L, N=4) and Renin mRNA levels (6.16 +/- 0.96, by 100 nmol/L, N=4) in ECs. On the other hand, the same dose of Ang II suppressed Renin mRNA expression in isolated Juxtaglomerular cells (JGs). These results indicate that preglomerular ECs are respond to Ang II and exclude the possible contamination of JGs into ECs. 100 pmol/L of Ang II increased AGT mRNA expression levels (1.37 +/- 0.03, relative ratio, N=4) in preglomerular VSMCs and the culture medium of ECs without Ang II treatment also more increased AGT mRNA expression (1.62 +/- 0.13, relative ratio, N=4) in preglomerular VSMCs. The AGT mRNA expression augmentation was enhanced when preglomerular VSMCs were treated with culture medium of Ang II-treated preglomerular ECs (2.39 +/- 0.41, relative ratio, N=4). The synergistic effects of Ang II and preglomerular ECs were also observed in PAI-1 expression in preglomerular VSMCs. Conclusion: These data demonstrate that preglomerular ECs contribute to Ang II-upregulation of AGT in renal afferent arterioles leading to further Ang II augmentation, which leads to increases in inflammatory and sclerotic factors in preglomerular VSMCs.


Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Dan Wang ◽  
Christopher S Wilcox

Introduction and hypothesis: Following bodily entry, the SARS-CoV-2 virus undergoes pulmonary replication with release of circulating viral spike protein 1 (SP1) into the bloodstream. Uptake of SP1 by endothelial cells might provoke vascular dysfunction and thrombosis. We hypothesized that spironolactone could prevent microvascular complications from circulating SP1 in COVID-19. Methods: male C57Bl/6 mice received spironolactone (100 mg · kg -1 · d -1 PO x 3d) or vehicle and intravenous injections of recombinant full-length human SP1 (10 μg per mouse) or vehicle. They were euthanized after 3 days. Mesenteric resistant arterioles (n=4 per group) were dissected and mounted on isometric myographs. Acetylcholine-induced EDRF responses and L-NAME-inhibitable NO generation (DAF-FM fluorescence) were studied in pre-constricted vessels and contraction to endothelin 1 (ET1) or thromboxane (U-46, 619) and ET1-induced ROS (PEG-SOD inhibitable ethidium: dihydroethidium fluorescence) were studied by fluorescence microscopy in other vessels. Results: SP1 reduced acetylcholine-induced EDRF (17 ± 3 vs 27 ± 5 % mean ± sem; P < 0.05) and NO generation (0.21 ± 0.03 vs 0.36 ± 0.04, F 1 /F 0 ; P < 0.05) while increasing contraction to ET1 (10 -7 mol·l -1 : 124 ± 13 vs 89 ± 4 %; P < 0.05) and U-46, 619 (10 -6 mol·l -1 :114± 5 vs 87± 6 %; P < 0.05) and ET1-induced ROS generation(0.30± 0.08 vs 0.09± 0.03; P < 0.05). Spironolactone did not modify any of these responses in vessels from normal mice but prevented all the effects of SP1. Conclusion: these preliminary studies provide a novel model to study COVID-19 vasculopathy. They indicate that spironolactone can provide protection from microvascular oxidative stress, endothelial dysfunction and enhanced contractility and might thereby moderate COVID-19 complications.


2009 ◽  
Vol 116 (9) ◽  
pp. 731-739 ◽  
Author(s):  
Peter Wilson ◽  
James Morgan ◽  
John W. Funder ◽  
Peter J. Fuller ◽  
Morag J. Young

Coronary, vascular and perivascular inflammation in rats following MR (mineralocorticoid receptor) activation plus salt are well-characterized precursors for the appearance of cardiac fibrosis. Endogenous corticosterone, in the presence of the 11βHSD2 (11β hydroxysteroid dehydrogenase type 2) inhibitor CBX (carbenoxolone) plus salt, produces similar inflammatory responses and tissue remodelling via activation of MR. MR-mediated oxidative stress has previously been suggested to account for these responses. In the present study we thus postulated that when 11βHSD2 is inhibited, endogenous corticosterone bound to unprotected MR in the vessel wall may similarly increase early biomarkers of oxidative stress. Uninephrectomized rats received either DOC (deoxycorticosterone), CBX or CBX plus the MR antagonist EPL (eplerenone) together with 0.9% saline to drink for 4, 8 or 16 days. Uninephrectomized rats maintained on 0.9% saline for 8 days served as controls. After 4 days, both DOC and CBX increased both macrophage infiltration and mRNA expression of the p22phox subunit of NADPH oxidase, whereas CBX, but not DOC, increased expression of the NOX2 (gp91phox) subunit. eNOS [endothelial NOS (NO synthase)] mRNA expression significantly decreased from 4 days for both treatments, and iNOS (inducible NOS) mRNA levels increased after 16 days of DOC or CBX; co-administration of EPL inhibited all responses to CBX. The responses characterized over this time course occurred before measurable increases in cardiac hypertrophy or fibrosis. The findings of the present study support the hypothesis that endogenous corticosterone in the presence of CBX can activate vascular MR to produce both inflammatory and oxidative tissue responses well before the onset of fibrosis, that the two MR ligands induce differential but overlapping patterns of gene expression, and that elevation of NOX2 subunit levels does not appear necessary for full expression of MR-mediated inflammatory and fibrogenic responses.


2018 ◽  
Vol 19 (9) ◽  
pp. 2621
Author(s):  
Maxime Pellegrin ◽  
Karima Bouzourène ◽  
Jean-François Aubert ◽  
Aimable Nahimana ◽  
Michel Duchosal ◽  
...  

Angiotensin (Ang) II triggers vulnerable atherosclerotic plaque development. Bone marrow (BM)-derived cells are key players in atherogenesis but whether Ang II induces plaque vulnerability directly through Ang II type 1 receptor (AT1R) activation on these cells remains to be clarified. In the present study, we investigated whether a lack of AT1R on BM-derived cells might affect Ang II-mediated vulnerable plaque development. The 2-kidney, 1-clip (2K1C) model (Ang II-dependent mouse model of advanced atherosclerosis and vulnerable plaques) was generated in ApoE−/− mice transplanted with AT1aR−/− or AT1aR+/+ BM. Plasma cholesterol as well as hepatic mRNA expression levels of genes involved in cholesterol metabolism were significantly lower in 2K1C mice transplanted with AT1aR−/− BM than in controls. Atherosclerotic lesions were significantly smaller in AT1aR−/− BM 2K1C mice (−79% in the aortic sinus and −71% in whole aorta compared to controls). Plaques from AT1aR−/− BM 2K1C mice exhibited reduced lipid core/fibrous cap and macrophage/smooth muscle cells ratios (−82% and −88%, respectively), and increased collagen content (+70%), indicating a more stable phenotype. Moreover, aortic mRNA levels of pro-inflammatory cytokines IL-12p35, IL-1β, and TNF-α were significantly reduced in AT1aR−/− BM 2K1C mice. No significant differences in either the number of circulating Ly6Chigh inflammatory monocytes and Ly6Clow resident anti-inflammatory monocyte subsets, or in mRNA levels of aortic M1 or M2 macrophage markers were observed between the two groups. No significant differences were observed in splenic mRNA levels of T cell subsets (Th1, Th2, Th17 and Treg) markers between the two groups. In conclusion, direct AT1R activation by Ang II on BM-derived cells promotes hepatic mRNA expression of cholesterol-metabolism-related genes and vascular mRNA expression of pro-inflammatory cytokines that may lead to plaque instability.


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