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Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis

The endothelial cells which form the inner cellular lining of the vasculature can act as non-professional phagocytes to ingest and remove emboli and aged/injured red blood cells (RBCs) from circulation. We previously demonstrated an erythrophagocytic phenotype of the brain endothelium for oxidativel...

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Autores principales: Sun, Jiahong, Vyas, Prema, Mann, Samar, Paganini-Hill, Annlia, Nunes, Ane C. F., Lau, Wei Ling, Cribbs, David H., Fisher, Mark J., Sumbria, Rachita K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8365766/
https://www.ncbi.nlm.nih.gov/pubmed/34409026
http://dx.doi.org/10.3389/fcell.2021.672009
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author Sun, Jiahong
Vyas, Prema
Mann, Samar
Paganini-Hill, Annlia
Nunes, Ane C. F.
Lau, Wei Ling
Cribbs, David H.
Fisher, Mark J.
Sumbria, Rachita K.
author_facet Sun, Jiahong
Vyas, Prema
Mann, Samar
Paganini-Hill, Annlia
Nunes, Ane C. F.
Lau, Wei Ling
Cribbs, David H.
Fisher, Mark J.
Sumbria, Rachita K.
author_sort Sun, Jiahong
collection PubMed
description The endothelial cells which form the inner cellular lining of the vasculature can act as non-professional phagocytes to ingest and remove emboli and aged/injured red blood cells (RBCs) from circulation. We previously demonstrated an erythrophagocytic phenotype of the brain endothelium for oxidatively stressed RBCs with subsequent migration of iron-rich RBCs and RBC degradation products across the brain endothelium in vivo and in vitro, in the absence of brain endothelium disruption. However, the mechanisms contributing to brain endothelial erythrophagocytosis are not well defined, and herein we elucidate the cellular mechanisms underlying brain endothelial erythrophagocytosis. Murine brain microvascular endothelial cells (bEnd.3 cells) were incubated with tert-butyl hydroperoxide (tBHP, oxidative stressor to induce RBC aging in vitro)- or PBS (control)-treated mouse RBCs. tBHP increased the reactive oxygen species (ROS) formation and phosphatidylserine exposure in RBCs, which were associated with robust brain endothelial erythrophagocytosis. TNFα treatment potentiated the brain endothelial erythrophagocytosis of tBHP-RBCs in vitro. Brain endothelial erythrophagocytosis was significantly reduced by RBC phosphatidylserine cloaking with annexin-V and with RBC-ROS and phosphatidylserine reduction with vitamin C. Brain endothelial erythrophagocytosis did not alter the bEnd.3 viability, and tBHP-RBCs were localized with early and late endosomes. Brain endothelial erythrophagocytosis increased the bEnd.3 total iron pool, abluminal iron levels without causing brain endothelial monolayer disruption, and ferroportin levels. In vivo, intravenous tBHP-RBC injection in aged (17–18 months old) male C57BL/6 mice significantly increased the Prussian blue-positive iron-rich lesion load compared with PBS-RBC-injected mice. In conclusion, RBC phosphatidylserine exposure and ROS are key mediators of brain endothelial erythrophagocytosis, a process which is associated with increased abluminal iron in vitro. tBHP-RBCs result in Prussian blue-positive iron-rich lesions in vivo. Brain endothelial erythrophagocytosis may provide a new route for RBC/RBC degradation product entry into the brain to produce iron-rich cerebral microhemorrhage-like lesions.
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spelling pubmed-83657662021-08-17 Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis Sun, Jiahong Vyas, Prema Mann, Samar Paganini-Hill, Annlia Nunes, Ane C. F. Lau, Wei Ling Cribbs, David H. Fisher, Mark J. Sumbria, Rachita K. Front Cell Dev Biol Cell and Developmental Biology The endothelial cells which form the inner cellular lining of the vasculature can act as non-professional phagocytes to ingest and remove emboli and aged/injured red blood cells (RBCs) from circulation. We previously demonstrated an erythrophagocytic phenotype of the brain endothelium for oxidatively stressed RBCs with subsequent migration of iron-rich RBCs and RBC degradation products across the brain endothelium in vivo and in vitro, in the absence of brain endothelium disruption. However, the mechanisms contributing to brain endothelial erythrophagocytosis are not well defined, and herein we elucidate the cellular mechanisms underlying brain endothelial erythrophagocytosis. Murine brain microvascular endothelial cells (bEnd.3 cells) were incubated with tert-butyl hydroperoxide (tBHP, oxidative stressor to induce RBC aging in vitro)- or PBS (control)-treated mouse RBCs. tBHP increased the reactive oxygen species (ROS) formation and phosphatidylserine exposure in RBCs, which were associated with robust brain endothelial erythrophagocytosis. TNFα treatment potentiated the brain endothelial erythrophagocytosis of tBHP-RBCs in vitro. Brain endothelial erythrophagocytosis was significantly reduced by RBC phosphatidylserine cloaking with annexin-V and with RBC-ROS and phosphatidylserine reduction with vitamin C. Brain endothelial erythrophagocytosis did not alter the bEnd.3 viability, and tBHP-RBCs were localized with early and late endosomes. Brain endothelial erythrophagocytosis increased the bEnd.3 total iron pool, abluminal iron levels without causing brain endothelial monolayer disruption, and ferroportin levels. In vivo, intravenous tBHP-RBC injection in aged (17–18 months old) male C57BL/6 mice significantly increased the Prussian blue-positive iron-rich lesion load compared with PBS-RBC-injected mice. In conclusion, RBC phosphatidylserine exposure and ROS are key mediators of brain endothelial erythrophagocytosis, a process which is associated with increased abluminal iron in vitro. tBHP-RBCs result in Prussian blue-positive iron-rich lesions in vivo. Brain endothelial erythrophagocytosis may provide a new route for RBC/RBC degradation product entry into the brain to produce iron-rich cerebral microhemorrhage-like lesions. Frontiers Media S.A. 2021-08-02 /pmc/articles/PMC8365766/ /pubmed/34409026 http://dx.doi.org/10.3389/fcell.2021.672009 Text en Copyright © 2021 Sun, Vyas, Mann, Paganini-Hill, Nunes, Lau, Cribbs, Fisher and Sumbria. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Cell and Developmental Biology
Sun, Jiahong
Vyas, Prema
Mann, Samar
Paganini-Hill, Annlia
Nunes, Ane C. F.
Lau, Wei Ling
Cribbs, David H.
Fisher, Mark J.
Sumbria, Rachita K.
Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis
title Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis
title_full Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis
title_fullStr Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis
title_full_unstemmed Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis
title_short Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis
title_sort insights into the mechanisms of brain endothelial erythrophagocytosis
topic Cell and Developmental Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8365766/
https://www.ncbi.nlm.nih.gov/pubmed/34409026
http://dx.doi.org/10.3389/fcell.2021.672009
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