| 1. |
- Porpino, Suenia K. P., et al.
(författare)
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Nitric oxide generation by the organic nitrate NDBP attenuates oxidative stress and angiotensin II-mediated hypertension
- 2016
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Ingår i: British Journal of Pharmacology. - : Wiley. - 0007-1188 .- 1476-5381. ; 173:14, s. 2290-2302
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Tidskriftsartikel (refereegranskat)abstract
- Background and PurposeNO deficiency and oxidative stress are crucially involved in the development or progression of cardiovascular disease, including hypertension and stroke. We have previously demonstrated that acute treatment with the newly discovered organic nitrate, 2-nitrate-1,3-dibuthoxypropan (NDBP), is associated with NO-like effects in the vasculature. This study aimed to further characterize the mechanism(s) and to elucidate the therapeutic potential in a model of hypertension and oxidative stress. Experimental ApproachA combination of ex vivo, in vitro and in vivo approaches was used to assess the effects of NDBP on vascular reactivity, NO release, NADPH oxidase activity and in a model of hypertension. Key ResultsEx vivo vascular studies demonstrated NDBP-mediated vasorelaxation in mesenteric resistance arteries, which was devoid of tolerance. In vitro studies using liver and kidney homogenates revealed dose-dependent and sustained NO generation by NDBP, which was attenuated by the xanthine oxidase inhibitor febuxostat. In addition, NDBP reduced NADPH oxidase activity in the liver and prevented angiotensin II-induced activation of NADPH oxidase in the kidney. In vivo studies showed that NDBP halted the progression of hypertension in mice with chronic angiotensin II infusion. This was associated with attenuated cardiac hypertrophy, and reduced NADPH oxidase-derived oxidative stress and fibrosis in the kidney and heart. Conclusion and ImplicationsThe novel organic nitrate NDBP halts the progression of angiotensin II-mediated hypertension. Mechanistically, our findings suggest that NDBP treatment is associated with sustained NO release and attenuated activity of NADPH oxidase, which to some extent requires functional xanthine oxidase.
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| 2. |
- Carlström, Mattias, et al.
(författare)
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Cross-talk Between Nitrate-Nitrite-NO and NO Synthase Pathways in Control of Vascular NO Homeostasis
- 2015
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Ingår i: Antioxidants and Redox Signaling. - : Mary Ann Liebert Inc. - 1523-0864 .- 1557-7716. ; 23:4, s. 295-306
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Inorganic nitrate and nitrite from endogenous and dietary sources have emerged as alternative substrates for nitric oxide (NO) formation in addition to the classic L-arginine NO synthase (NOS)-dependent pathway. Here, we investigated a potential cross-talk between these two pathways in the regulation of vascular function. Results: Long-term dietary supplementation with sodium nitrate (0.1 and 1mmol kg(-1) day(-1)) in rats caused a reversible dose-dependent reduction in phosphorylated endothelial NOS (eNOS) (Ser1177) in aorta and a concomitant increase in phosphorylation at Thr495. Moreover, eNOS-dependent vascular responses were attenuated in vessels harvested from nitrate-treated mice or when nitrite was acutely added to control vessels. The citrulline-to-arginine ratio in plasma, as a measure of eNOS activity, was reduced in nitrate-treated rodents. Telemetry measurements revealed that a low dietary nitrate dose reduced blood pressure, whereas a higher dose was associated with a paradoxical elevation. Finally, plasma cyclic guanosine monophosphate increased in mice that were treated with a low dietary nitrate dose and decreased with a higher dose. Innovation and Conclusions: These results demonstrate the existence of a cross-talk between the nitrate-nitrite-NO pathway and the NOS-dependent pathway in control of vascular NO homeostasis. Antioxid. Redox Signal. 23, 295-306.
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| 3. |
- Gao, Xiang, et al.
(författare)
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Adenosine A1 receptor-dependent and independent pathways in modulating renal vascular responses to angiotensin II
- 2015
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 213:1, s. 268-276
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Renal afferent arterioles are the effector site for autoregulation of glomerular perfusion and filtration. There is synergistic interaction between angiotensin II (ANG II) and adenosine (Ado) in regulating arteriolar contraction, however, the mechanisms are not clear. In this context, this study investigated the contribution of A1 receptor dependent and independent signaling mechanisms.METHODS: Isolated perfused afferent arterioles from transgenic mice (A1+/+ and A1-/-) were used for vascular reactivity studies. Cultured vascular smooth muscle cells (VSMC) were used for phosphorylation studies of signaling proteins that induce arteriolar contraction.RESULTS: Maximal arteriolar contraction to ANG II was attenuated in A1-/- (22%) compared with A1+/+ (40%). Simultaneous incubation with low dose Ado (10-8 mol/L) enhanced ANG II-induced contraction in A1+/+ (58%), but also in A1-/- (42%). An Ado transporter inhibitor (NBTI) abolished this synergistic effect in A1-/-, but not in wild-type mice. Incubation with Ado+ANG II increased p38 phosphorylation in aortic VSMC from both genotypes, but treatment with NBTI only blocked phosphorylation in A1-/-. Combination of ANG II+Ado also increased MLC phosphorylation in A1+/+ but not significantly in A1-/-, and NBTI had no effects. In agreement, Ado+ANG II-induced phosphorylation of p38 and MLC in rat preglomerular VSMC was not affected by NBTI. However, during pharmacological inhibition of the A1 receptor simultaneous treatment with NBTI reduced phosphorylation of both p38 and MLC to control levels.CONCLUSION: Interaction between ANG II and Ado in VSMC normally involves A1 receptor signaling, but this can be compensated by receptor independent actions that phosphorylate p38 MAPK and MLC.
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| 4. |
- Gao, Xiang, et al.
(författare)
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NADPH Oxidase in the Renal Microvasculature Is a Primary Target for Blood Pressure-Lowering Effects by Inorganic Nitrate and Nitrite
- 2015
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Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 65:1, s. 161-
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Tidskriftsartikel (refereegranskat)abstract
- Renal oxidative stress and nitric oxide (NO) deficiency are key events in hypertension. Stimulation of a nitrate-nitrite-NO pathway with dietary nitrate reduces blood pressure, but the mechanisms or target organ are not clear. We investigated the hypothesis that inorganic nitrate and nitrite attenuate reactivity of renal microcirculation and blood pressure responses to angiotensin II (ANG II) by modulating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and NO bioavailability. Nitrite in the physiological range (10(-7)-10(-5) mol/L) dilated isolated perfused renal afferent arterioles, which were associated with increased NO. Contractions to ANG II (34%) and simultaneous NO synthase inhibition (56%) were attenuated by nitrite (18% and 26%). In a model of oxidative stress (superoxide dismutase-1 knockouts), abnormal ANG II-mediated arteriolar contractions (90%) were normalized by nitrite (44%). Mechanistically, effects of nitrite were abolished by NO scavenger and xanthine oxidase inhibitor, but only partially attenuated by inhibiting soluble guanylyl cyclase. Inhibition of NADPH oxidase with apocynin attenuated ANG II-induced contractility (35%) similar to that of nitrite. In the presence of nitrite, no further effect of apocynin was observed, suggesting NADPH oxidase as a possible target. In preglomerular vascular smooth muscle cells and kidney cortex, nitrite reduced both basal and ANG II-induced NADPH oxidase activity. These effects of nitrite were also abolished by xanthine oxidase inhibition. Moreover, supplementation with dietary nitrate (10(-2) mol/L) reduced renal NADPH oxidase activity and attenuated ANG II-mediated arteriolar contractions and hypertension (99+/-2-146+/-2 mm Hg) compared with placebo (100+/-3-168+/-3 mm Hg). In conclusion, these novel findings position NADPH oxidase in the renal microvasculature as a prime target for blood pressure-lowering effects of inorganic nitrate and nitrite.
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| 5. |
- Peleli, Maria, et al.
(författare)
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Cystathionine gamma-lyase (CTH) inhibition attenuates glioblastoma formation
- 2023
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Ingår i: Redox Biology. - : Elsevier. - 2213-2317. ; 64
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Glioblastoma (GBM) is the most common type of adult brain tumor with extremely poor survival. Cystathionine-gamma lyase (CTH) is one of the main Hydrogen Sulfide (H2S) producing enzymes and its expression contributes to tumorigenesis and angiogenesis but its role in glioblastoma development remains poorly understood.Methods: and Principal Results: An established allogenic immunocompetent in vivo GBM model was used in C57BL/6J WT and CTH KO mice where the tumor volume and tumor microvessel density were blindly measured by stereological analysis. Tumor macrophage and stemness markers were measured by blinded immunohisto-chemistry. Mouse and human GBM cell lines were used for cell-based analyses. In human gliomas, the CTH expression was analyzed by bioinformatic analysis on different databases.In vivo, the genetic ablation of CTH in the host led to a significant reduction of the tumor volume and the protumorigenic and stemness transcription factor sex determining region Y-box 2 (SOX2). The tumor microvessel density (indicative of angiogenesis) and the expression levels of peritumoral macrophages showed no significant changes between the two genotypes. Bioinformatic analysis in human glioma tumors revealed that higher CTH expression is positively correlated to SOX2 expression and associated with worse overall survival in all grades of gliomas. Patients not responding to temozolomide have also higher CTH expression. In mouse or human GBM cells, pharmacological inhibition (PAG) or CTH knockdown (siRNA) attenuates GBM cell proliferation, migration and stem cell formation frequency.Major Conclusions: Inhibition of CTH could be a new promising target against glioblastoma formation.
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| 6. |
- Peleli, Maria, et al.
(författare)
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Endothelial-Tumor Cell Interaction in Brain and CNS Malignancies
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 21:19
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Forskningsöversikt (refereegranskat)abstract
- Glioblastoma and other brain or CNS malignancies (like neuroblastoma and medulloblastoma) are difficult to treat and are characterized by excessive vascularization that favors further tumor growth. Since the mean overall survival of these types of diseases is low, the finding of new therapeutic approaches is imperative. In this review, we discuss the importance of the interaction between the endothelium and the tumor cells in brain and CNS malignancies. The different mechanisms of formation of new vessels that supply the tumor with nutrients are discussed. We also describe how the tumor cells (TC) alter the endothelial cell (EC) physiology in a way that favors tumorigenesis. In particular, mechanisms of EC-TC interaction are described such as (a) communication using secreted growth factors (i.e., VEGF, TGF-beta), (b) intercellular communication through gap junctions (i.e., Cx43), and (c) indirect interaction via intermediate cell types (pericytes, astrocytes, neurons, and immune cells). At the signaling level, we outline the role of important mediators, like the gasotransmitter nitric oxide and different types of reactive oxygen species and the systems producing them. Finally, we briefly discuss the current antiangiogenic therapies used against brain and CNS tumors and the potential of new pharmacological interventions that target the EC-TC interaction.
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| 7. |
- Peleli, Maria, et al.
(författare)
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Enhanced XOR activity in eNOS-deficient mice Effects on the nitrate-nitrite-NO pathway and ROS homeostasis
- 2016
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 99, s. 472-484
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Tidskriftsartikel (refereegranskat)abstract
- Xanthine oxidoreductase (XOR) is generally known as the final enzyme in purine metabolism and as a source of reactive oxygen species (ROS). In addition, this enzyme has been suggested to mediate nitric oxide (NO) formation via reduction of inorganic nitrate and nitrite. This NO synthase (NOS)-independent pathway for NO generation is of particular importance during certain conditions when NO bioavailability is diminished due to reduced activity of endothelial NOS (eNOS) or increased oxidative stress, including aging and cardiovascular disease. The exact interplay between NOS- and XOR-derived NO generation is not fully elucidated yet. The aim of the present study was to investigate if eNOS deficiency is associated with changes in XOR expression and activity and the possible impact on nitrite, NO and ROS homeostasis. Plasma levels of nitrate and nitrite were similar between eNOS deficient (eNOS(-/-)) and wildtype (wt) mice. XOR activity was upregulated in eNOS(-/-) compared with wt, but not in nNOS(-/-), iNOS(-/-) or wt mice treated with the non-selective NOS inhibitor L-NAME. Following an acute dose of nitrate, plasma nitrite increased more in eNOS(-/-) compared with wt, and this augmented response was abolished by the selective XOR inhibitor febuxostat. Livers from eNOS(-/-) displayed higher nitrite reducing capacity compared with wt, and this effect was attenuated by febuxostat. Dietary supplementation with nitrate increased XOR expression and activity, but concomitantly reduced superoxide generation. The latter effect was also seen in vitro after nitrite administration. Treatment with febuxostat elevated blood pressure in eNOS(-/-), but not in wt mice. A high dose of dietary nitrate reduced blood pressure in na ve eNOS(-/-) mice, and again this effect was abolished by febuxostat. In conclusion, eNOS deficiency is associated with an upregulation of XOR facilitating the nitrate-nitrite-NO pathway and decreasing the generation of ROS. This interplay between XOR and eNOS is proposed to play a significant role in NO homeostasis and blood pressure regulation.
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| 8. |
- Peleli, Maria, et al.
(författare)
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In adenosine A(2B) knockouts acute treatment with inorganic nitrate improves glucose disposal, oxidative stress, and AMPK signaling in the liver
- 2015
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Accumulating studies suggest that nitric oxide (NO) deficiency and oxidative stress are central pathological mechanisms in type 2 diabetes (T2D). Recent findings demonstrate therapeutic effects by boosting the nitrate-nitrite-NO pathway, which is an alternative pathway for NO formation. This study aimed at investigating the acute effects of inorganic nitrate on glucose and insulin signaling in adenosine A2B receptor knockout mice (A(2B)(-/-), a genetic mouse model of impaired metabolic regulation. Methods: Acute effects of nitrate treatment were investigated in aged wild-type (WT) and A(2B)(-/-) mice. One hour after injection with nitrate (0.1 mmol/kg, i.p.) or placebo, metabolic regulation was evaluated by intraperitoneal glucose and insulin tolerance tests. NADPH oxidase-mediated superoxide production and AMPK phosphorylation were measured in livers obtained from non-treated or glucose-treated mice, with or without prior nitrate injection. Plasma was used to determine insulin resistance (HOMA-IR) and NO signaling. Results: A(2B)(-/-) displayed increased body weight, reduced glucose clearance, and attenuated overall insulin responses compared with age-matched WT mice. Nitrate treatment increased circulating levels of nitrate, nitrite and cGMP in the A(2B)(-/-), and improved glucose clearance. In WT mice, however, nitrate treatment did not influence glucose clearance. HOMA-IR increased following glucose injection in the A(2B)(-/-), but remained at basal levels in mice pretreated with nitrate. NADPH oxidase activity in livers from A(2B)(-/-), but not WT mice, was reduced by nitrate treatment. Livers from A(2B)(-/-) displayed reduced AMPK phosphorylation compared with WT mice, and this was increased by nitrate treatment. Finally, injection with the anti-diabetic agent metformin induced similar therapeutic effects in the A(2B)(-/-) as observed with nitrate. Conclusion: The A(2B)(-/-) mouse is a genetic mouse model of metabolic syndrome. Acute treatment with nitrate improved the metabolic profile in it, at least partly via reduction in oxidative stress and improved AMPK signaling in the liver.
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| 9. |
- Peleli, Maria, et al.
(författare)
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Inhibition of cystathionine-gamma lyase dampens vasoconstriction in mouse and human intracerebral arterioles
- 2023
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Ingår i: Acta Physiologica. - : John Wiley & Sons. - 1748-1708 .- 1748-1716. ; 239:1
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Tidskriftsartikel (refereegranskat)abstract
- AimIn extracerebral vascular beds cystathionine-gamma lyase (CSE) activity plays a vasodilatory role but the role of this hydrogen sulfide (H2S) producing enzyme in the intracerebral arterioles remain poorly understood. We hypothesized a similar function in the intracerebral arterioles. MethodsIntracerebral arterioles were isolated from wild type C57BL/6J mouse (9-12 months old) brains and from human brain biopsies. The function (contractility and secondary dilatation) of the intracerebral arterioles was tested ex vivo by pressure myography using a perfusion set-up. Reverse transcription polymerase chain reaction was used for detecting CSE expression. ResultsCSE is expressed in human and mouse intracerebral arterioles. CSE inhibition with L-propargylglycine (PAG) significantly dampened the K+-induced vasoconstriction in intracerebral arterioles of both species (% of maximum contraction: in human control: 45.4 & PLUSMN; 2.7 versus PAG: 27 & PLUSMN; 5.2 and in mouse control: 50 & PLUSMN; 1.5 versus PAG: 33 & PLUSMN; 5.2) but did not affect the secondary dilatation. This effect of PAG was significantly reversed by the H2S donor sodium hydrosulfide (NaSH) in human (PAG + NaSH: 38.8 & PLUSMN; 7.2) and mouse (PAG + NaSH: 41.7 & PLUSMN; 3.1) arterioles, respectively. The endothelial NO synthase (eNOS) inhibitor, N & omega;-Nitro-l-arginine methyl ester (L-NAME), and the inhibitor of soluble guanylate cyclase (sGC), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) reversed the effect of PAG on the K+-induced vasoconstriction in the mouse arterioles and attenuated the K+-induced secondary dilatation significantly. ConclusionCSE contributes to the K+-induced vasoconstriction via a mechanism involving H2S, eNOS, and sGC whereas the secondary dilatation is regulated by eNOS and sGC but not by CSE.
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| 10. |
- Peleli, Maria
(författare)
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NADPH oxidase and xanthine oxidoreductase as targets and regulators of the nitrate-nitrite-nitric oxide pathway
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Overproduction of reactive oxygen species (ROS) by NADPH oxidase (NOX) and xanthine oxidoreductase (XOR) with a concomitant decrease in the bioavailability of nitric oxide (NO) from eNOS contributes to the development of cardiovascular and metabolic disorders. Extensive research has proven the existence of an alternative NOS-independent pathway for NO production. This nitrate-nitrite-NO pathway starts with inorganic nitrate which is derived from the diet and from oxidized NO. Nitrate is reduced to nitrite mainly by oral commensal bacteria and then to NO and other bioactive nitrogen oxides in blood and tissues. The aim of the current thesis was to investigate the therapeutic role of the nitrate-nitrite-NO pathway in models of hypertension, metabolic dysfunction and inflammation focusing on whether the main ROS-producing enzymes NOX and XOR could be targets or even regulators of the this pathway. We show that NOX in the renal microvasculature is a primary target for the blood pressure lowering effects of dietary nitrate in Angiotensin-II (AngII)-mediated hypertension. In agreement, NOX activity and AngII-induced receptor signaling are downregulated by nitrate in aged and hypertensive rats. Moreover, nitrate targets the elevated liver NOX activity of aged and metabolically dysregulated mice with an improvement of AMPK activity. Finally, we show that nitrite can act on cells of the innate immune response. In particular, NOX mediated superoxide production is strongly attenuated in activated macrophages with a concomitant reduction on iNOS gene expression and peroxynitrite production. Mechanistically, we observed that symbiotic bacteria and XOR together are responsible for the bioactivation of dietary nitrate to form NO. In addition, the effects of nitrate and nitrite are not only NOS independent but actually potentiated when eNOS activity is pharmacologically, genetically or naturally impaired. Interestingly, the absence of eNOS is associated with a higher XOR activity that partly compensates for the disrupted NO homeostasis and elevated blood pressure in these mice. Also, the blood pressure response to dietary nitrate is augmented in eNOS-/- mice and abolished upon XOR inhibition. Interestingly, nitrate and nitrite were able to switch the function of XOR towards lower ROS and higher NO production which could significantly contribute to the antihypertensive effects. In conclusion, administration of nitrate or nitrite is associated with a number of therapeutic cardiovascular and metabolic effects in animal models of disease. We propose that NOX and XOR are two main targets and possible regulators of the nitrate-nitrite-NO pathway. This pathway is triggered in situations with higher NOX and XOR activity and acts in parallel with the NOS dependent NO production to uphold NO homeostasis.
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