Article
Neutrophil-derived microparticles induce myeloperoxidase-mediated damage of vascular endothelial cells
Registro en:
PITANGA, T. N. et al. Neutrophil-derived microparticles induce myeloperoxidase-mediated damage of vascular endothelial cells. BMC Cell Biology, v. 15, n. 1, p.1-9, 2014.
1471-2121
10.1186/1471-2121-15-21
Autor
Pitanga, Thassila Nogueira
França, Luciana Souza de Aragão
Rocha, Viviane Costa Junqueira
Meirelles, Thayna
Borges, Valeria de Matos
Gonçalves, Marilda de Souza
Pontes-de-Carvalho, Lain Carlos
Dutra, Alberto Augusto Noronha
dosSantos, Washington Luis Conrado
Resumen
Background: Upon activation neutrophil releases microparticles - small plasma membrane vesicles that contain cell
surface proteins and cytoplasmic matter, with biological activities. In this study we investigated the potential role of
myeloperoxidase in the endothelial cell injury caused by neutrophil-derived microparticles.
Results: Microparticles were produced by activating human neutrophils with a calcium ionophore and
characterized by flow cytometry and transmission and scanning electron microscopy. Myeloperoxidase activity was
measured by luminol-dependent chemiluminescence. Neutrophil microparticles-induced injuries and morphological
alterations in human umbilical vein endothelial cells (HUVECs) were evaluated by microscopy and flow cytometry.
Neutrophil microparticles were characterized as structures bounded by lipid bilayers and were less than 1 μm in
diameter. The microparticles also expressed CD66b, CD62L and myeloperoxidase, which are all commonly expressed on
the surface of neutrophils, as well as exposition of phosphatidylserine. The activity of the myeloperoxidase present on the
microparticles was confirmed by hypochlorous acid detection. This compound is only catalyzed by myeloperoxidase in
the presence of hydrogen peroxide and chloride ion. The addition of sodium azide or taurine inhibited and reduced
enzymatic activity, respectively. Exposure of HUVEC to neutrophil microparticles induced a loss of cell membrane integrity
and morphological changes. The addition of sodium azide or myeloperoxidase-specific inhibitor-I consistently reduced
the injury to the endothelial cells. Taurine addition reduced HUVEC morphological changes.
Conclusions: We have demonstrated the presence of active myeloperoxidase in neutrophil microparticles and that the
microparticle-associated myeloperoxidase cause injury to endothelial cells. Hence, the microparticle-associated
myeloperoxidase-hydrogen peroxide-chloride system may contribute to widespread endothelial cell damage in
conditions of neutrophil activation as observed in vasculitis and sepsis.