Generation of reactive oxygen metabolites by phagocytosing endothelial cells.
We have studied the ability of particulate stimuli to induce the release of reactive oxygen metabolites from sub-cultured monolayers of human endothelial cells. Basal release of superoxide (O2-) and hydrogen peroxide from undisturbed monolayers was very low (108 pmol O2- and 75 pmol H2O2 in 3 h from dishes of 3 X 10(5) cells). Addition of 1-micron diameter polystyrene microspheres, which were phagocytosed by the cells progressively, caused a dramatic increase in release of both metabolites; by 3 h, a 13.5- and 6.6-fold increase over controls was observed respectively (P less than 0.001). Addition of formaldehyde-fixed human platelets or chylomicron-size lipid particles also increased production of reactive oxygen species. Similar rises in H2O2 and O2- production were induced by treatment with 10(-7) M phorbol myristate acetate. Pretreatment of endothelial cells with neuraminidase, heparinase or heparitinase to alter their glycocalyx composition substantially enhanced the effect of microspheres on H2O2 and O2- generation. We conclude that the interactions of particles, including platelets and lipids, with endothelial cells leads to the generation of significant pericellular levels of reactive oxygen species. These metabolites can oxidise a wide variety of nearby molecules, leading to cell damage and altered uptake characteristics for lipoproteins containing peroxidized lipids. These effects are exacerbated when endothelial cell glycocalyx composition is disrupted.
Görög
P
P
Thrombosis Research Unit, King's College School of Medicine and Dentistry, London, U.K.
Pearson
J D
JD
Kakkar
V V
VV
D002478:Cells, Cultured; D003574:Cytochrome c Group / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010587:Phagocytosis; D013481:Superoxides / Q000378:metabolism*; D014470:Umbilical Cord
D003574:Cytochrome c Group; D013481:Superoxides; D006861:Hydrogen Peroxide