NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin

<i>Aim</i>: The primary endothelial NADPH oxidase isoform 4 (NOX4) is notably induced during hypoxia, with emerging evidence suggesting its vasoprotective role through H<sub>2</sub>O<sub>2</sub> production. Therefore, we aimed to elucidate NOX4′s significance in e...

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Main Authors: Heike Brendel, Jennifer Mittag, Anja Hofmann, Helene Hempel, Sindy Giebe, Patrick Diaba-Nuhoho, Steffen Wolk, Christian Reeps, Henning Morawietz, Coy Brunssen
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:Antioxidants
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Online Access:https://www.mdpi.com/2076-3921/13/10/1178
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author Heike Brendel
Jennifer Mittag
Anja Hofmann
Helene Hempel
Sindy Giebe
Patrick Diaba-Nuhoho
Steffen Wolk
Christian Reeps
Henning Morawietz
Coy Brunssen
author_facet Heike Brendel
Jennifer Mittag
Anja Hofmann
Helene Hempel
Sindy Giebe
Patrick Diaba-Nuhoho
Steffen Wolk
Christian Reeps
Henning Morawietz
Coy Brunssen
author_sort Heike Brendel
collection DOAJ
description <i>Aim</i>: The primary endothelial NADPH oxidase isoform 4 (NOX4) is notably induced during hypoxia, with emerging evidence suggesting its vasoprotective role through H<sub>2</sub>O<sub>2</sub> production. Therefore, we aimed to elucidate NOX4′s significance in endothelial function under hypoxia. <i>Methods</i>: Human vessels, in addition to murine vessels from <i>Nox4<sup>−/−</sup></i> mice, were explored. On a functional level, Mulvany myograph experiments were performed. To obtain mechanistical insights, human endothelial cells were cultured under hypoxia with inhibitors of hypoxia-inducible factors. Additionally, endothelial cells were cultured under combined hypoxia and laminar shear stress conditions. <i>Results</i>: In human occluded vessels, NOX4 expression strongly correlated with prostaglandin I2 synthase (<i>PTGIS</i>). Hypoxia significantly elevated NOX4 and PTGIS expression and activity in human endothelial cells. Inhibition of prolyl hydroxylase domain (PHD) enzymes, which stabilize hypoxia-inducible factors (HIFs), increased NOX4 and PTGIS expression even under normoxic conditions. <i>NOX4</i> mRNA expression was reduced by HIF1a inhibition, while <i>PTGIS</i> mRNA expression was only affected by the inhibition of HIF2a under hypoxia. Endothelial function assessments revealed hypoxia-induced endothelial dysfunction in mesenteric arteries from wild-type mice. Mesenteric arteries from <i>Nox4<sup>−/−</sup></i> mice exhibited an altered endothelial function under hypoxia, most prominent in the presence of cyclooxygenase inhibitor diclofenac to exclude the impact of prostacyclin. Restored protective laminar shear stress, as it might occur after thrombolysis, angioplasty, or stenting, attenuated the hypoxic response in endothelial cells, reducing HIF1a expression and its target <i>NOX4</i> while enhancing <i>eNOS</i> expression. <i>Conclusions</i>: Hypoxia strongly induces NOX4 and PTGIS, with a close correlation between both factors in occluded, hypoxic human vessels. This relationship ensured endothelium-dependent vasodilation under hypoxic conditions. Protective laminar blood flow restores eNOS expression and mitigates the hypoxic response on NOX4 and PTGIS.
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spelling doaj-art-665eb58dafb74c9d82a5012dd29931e52025-08-20T02:11:08ZengMDPI AGAntioxidants2076-39212024-09-011310117810.3390/antiox13101178NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing ProstacyclinHeike Brendel0Jennifer Mittag1Anja Hofmann2Helene Hempel3Sindy Giebe4Patrick Diaba-Nuhoho5Steffen Wolk6Christian Reeps7Henning Morawietz8Coy Brunssen9Division of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular and Endovascular Surgery, Department of Visceral, Thoracic and Vascular Surgery, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular and Endovascular Surgery, Department of Visceral, Thoracic and Vascular Surgery, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular and Endovascular Surgery, Department of Visceral, Thoracic and Vascular Surgery, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, GermanyDivision of Vascular Endothelium and Microcirculation, Department of Medicine III, Faculty of Medicine and University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, Germany<i>Aim</i>: The primary endothelial NADPH oxidase isoform 4 (NOX4) is notably induced during hypoxia, with emerging evidence suggesting its vasoprotective role through H<sub>2</sub>O<sub>2</sub> production. Therefore, we aimed to elucidate NOX4′s significance in endothelial function under hypoxia. <i>Methods</i>: Human vessels, in addition to murine vessels from <i>Nox4<sup>−/−</sup></i> mice, were explored. On a functional level, Mulvany myograph experiments were performed. To obtain mechanistical insights, human endothelial cells were cultured under hypoxia with inhibitors of hypoxia-inducible factors. Additionally, endothelial cells were cultured under combined hypoxia and laminar shear stress conditions. <i>Results</i>: In human occluded vessels, NOX4 expression strongly correlated with prostaglandin I2 synthase (<i>PTGIS</i>). Hypoxia significantly elevated NOX4 and PTGIS expression and activity in human endothelial cells. Inhibition of prolyl hydroxylase domain (PHD) enzymes, which stabilize hypoxia-inducible factors (HIFs), increased NOX4 and PTGIS expression even under normoxic conditions. <i>NOX4</i> mRNA expression was reduced by HIF1a inhibition, while <i>PTGIS</i> mRNA expression was only affected by the inhibition of HIF2a under hypoxia. Endothelial function assessments revealed hypoxia-induced endothelial dysfunction in mesenteric arteries from wild-type mice. Mesenteric arteries from <i>Nox4<sup>−/−</sup></i> mice exhibited an altered endothelial function under hypoxia, most prominent in the presence of cyclooxygenase inhibitor diclofenac to exclude the impact of prostacyclin. Restored protective laminar shear stress, as it might occur after thrombolysis, angioplasty, or stenting, attenuated the hypoxic response in endothelial cells, reducing HIF1a expression and its target <i>NOX4</i> while enhancing <i>eNOS</i> expression. <i>Conclusions</i>: Hypoxia strongly induces NOX4 and PTGIS, with a close correlation between both factors in occluded, hypoxic human vessels. This relationship ensured endothelium-dependent vasodilation under hypoxic conditions. Protective laminar blood flow restores eNOS expression and mitigates the hypoxic response on NOX4 and PTGIS.https://www.mdpi.com/2076-3921/13/10/1178NADPH oxidase 4hypoxiaPTGISendothelial functionhuman endothelial cellslaminar flow
spellingShingle Heike Brendel
Jennifer Mittag
Anja Hofmann
Helene Hempel
Sindy Giebe
Patrick Diaba-Nuhoho
Steffen Wolk
Christian Reeps
Henning Morawietz
Coy Brunssen
NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin
Antioxidants
NADPH oxidase 4
hypoxia
PTGIS
endothelial function
human endothelial cells
laminar flow
title NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin
title_full NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin
title_fullStr NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin
title_full_unstemmed NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin
title_short NADPH Oxidase 4: Crucial for Endothelial Function under Hypoxia—Complementing Prostacyclin
title_sort nadph oxidase 4 crucial for endothelial function under hypoxia complementing prostacyclin
topic NADPH oxidase 4
hypoxia
PTGIS
endothelial function
human endothelial cells
laminar flow
url https://www.mdpi.com/2076-3921/13/10/1178
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