Red blood cells serve as intravascular carriers of myeloperoxidase

TY - JOUR

T1 - Red blood cells serve as intravascular carriers of myeloperoxidase

AU - Adam, Matti

AU - Gajdova, Silvie

AU - Kolarova, Hana

AU - Kubala, Lukas

AU - Lau, Denise

AU - Geisler, Anne

AU - Ravekes, Thorben

AU - Rudolph, Volker

AU - Tsao, Philip S

AU - Blankenberg, Stefan

AU - Baldus, Stephan

AU - Klinke, Anna

N1 - Copyright © 2014 Elsevier Ltd. All rights reserved.

PY - 2014/9

Y1 - 2014/9

N2 - Myeloperoxidase (MPO) is a heme enzyme abundantly expressed in polymorphonuclear neutrophils. MPO is enzymatically capable of catalyzing the generation of reactive oxygen species (ROS) and the consumption of nitric oxide (NO). Thus MPO has both potent microbicidal and, upon binding to the vessel wall, pro-inflammatory properties. Interestingly, MPO - a highly cationic protein - has been shown to bind to both endothelial cells and leukocyte membranes. Given the anionic surface charge of red blood cells, we investigated binding of MPO to erythrocytes. Red blood cells (RBCs) derived from patients with elevated MPO plasma levels showed significantly higher amounts of MPO by flow cytometry and ELISA than healthy controls. Heparin-induced MPO-release from patient-derived RBCs was significantly increased compared to controls. Ex vivo experiments revealed dose and time dependency for MPO-RBC binding, and immunofluorescence staining as well as confocal microscopy localized MPO-RBC interaction to the erythrocyte plasma membrane. NO-consumption by RBC-membrane fragments (erythrocyte "ghosts") increased with incrementally greater concentrations of MPO during incubation, indicating preserved catalytic MPO activity. In vivo infusion of MPO-loaded RBCs into C57BL/6J mice increased local MPO tissue concentrations in liver, spleen, lung, and heart tissue as well as within the cardiac vasculature. Further, NO-dependent relaxation of aortic rings was altered by RBC bound-MPO and systemic vascular resistance significantly increased after infusion of MPO-loaded RBCs into mice. In summary, we find that MPO binds to RBC membranes in vitro and in vivo, is transported by RBCs to remote sites in mice, and affects endothelial function as well as systemic vascular resistance. RBCs may avidly bind circulating MPO, and act as carriers of this leukocyte-derived enzyme.

AB - Myeloperoxidase (MPO) is a heme enzyme abundantly expressed in polymorphonuclear neutrophils. MPO is enzymatically capable of catalyzing the generation of reactive oxygen species (ROS) and the consumption of nitric oxide (NO). Thus MPO has both potent microbicidal and, upon binding to the vessel wall, pro-inflammatory properties. Interestingly, MPO - a highly cationic protein - has been shown to bind to both endothelial cells and leukocyte membranes. Given the anionic surface charge of red blood cells, we investigated binding of MPO to erythrocytes. Red blood cells (RBCs) derived from patients with elevated MPO plasma levels showed significantly higher amounts of MPO by flow cytometry and ELISA than healthy controls. Heparin-induced MPO-release from patient-derived RBCs was significantly increased compared to controls. Ex vivo experiments revealed dose and time dependency for MPO-RBC binding, and immunofluorescence staining as well as confocal microscopy localized MPO-RBC interaction to the erythrocyte plasma membrane. NO-consumption by RBC-membrane fragments (erythrocyte "ghosts") increased with incrementally greater concentrations of MPO during incubation, indicating preserved catalytic MPO activity. In vivo infusion of MPO-loaded RBCs into C57BL/6J mice increased local MPO tissue concentrations in liver, spleen, lung, and heart tissue as well as within the cardiac vasculature. Further, NO-dependent relaxation of aortic rings was altered by RBC bound-MPO and systemic vascular resistance significantly increased after infusion of MPO-loaded RBCs into mice. In summary, we find that MPO binds to RBC membranes in vitro and in vivo, is transported by RBCs to remote sites in mice, and affects endothelial function as well as systemic vascular resistance. RBCs may avidly bind circulating MPO, and act as carriers of this leukocyte-derived enzyme.

KW - Acute Coronary Syndrome/blood

KW - Animals

KW - Aorta/drug effects

KW - Biological Transport

KW - Cells, Cultured

KW - Endothelium, Vascular/drug effects

KW - Erythrocytes/metabolism

KW - Heart/drug effects

KW - Heart Failure/blood

KW - Heparin/chemistry

KW - Humans

KW - Male

KW - Mice

KW - Mice, Inbred C57BL

KW - Nitric Oxide/metabolism

KW - Organ Culture Techniques

KW - Peroxidase/blood

KW - Protein Binding

KW - Tissue Culture Techniques

KW - Vascular Resistance/drug effects

U2 - 10.1016/j.yjmcc.2014.06.009

DO - 10.1016/j.yjmcc.2014.06.009

M3 - SCORING: Journal article

C2 - 24976018

VL - 74

SP - 353

EP - 363

JO - J MOL CELL CARDIOL

JF - J MOL CELL CARDIOL

SN - 0022-2828

ER -