Reactive oxygen intermediates induce regulated secretion of von Willebrand factor from cultured human vascular endothelial cells

Abstract

Exocytosis from Weibel-Palade bodies, the secretory granules of vascular endothelial cells, causes the rapid release of von Willebrand factor (vWF), an adhesive glycoprotein involved in primary hemostasis, and cell surface expression of P-selectin, a membrane protein involved in neutrophil binding. Thus, exocytosis may represent a link between hemostasis and inflammation. We investigated the effect of reactive oxygen intermediates (ROIs) on vWF secretion. Incubation of cultured endothelial cells with xanthine oxidase (XO), which generates superoxide anions (O2-), induces a potent, rapid secretory response. However, vWF release was not observed in response to H2O2. Extracellular, subendothelial vWF deposits typically seen after exocytosis from Weibel-Palade bodies were observed after exposure to XO. XO caused a rapid, sustained increase in intracellular free calcium concentration ([Ca2+]i). vWF secretion was markedly inhibited by BAPTA-AM, a cell-permeant calcium chelator. Removal of extracellular calcium did not inhibit vWF release, although the sustained phase of the [Ca2+]i increase was suppressed. These results suggest that XO-induced vWF release is mediated by the initial increase in [Ca2+]i which is caused by calcium mobilization from intracellular stores rather than by calcium influx. Exocytosis from Weibel-Palade bodies may contribute to the pathogenic effect of ROIs in atherosclerosis and inflammation.

Retrospective comparison of thromboelastography results to postmortem evidence of thrombosis in critically ill dogs: 39 cases (2005–2010)

“…For example, activated neutrophils secrete reactive oxygen species that may induce endothelial cell injury, which has been shown in vitro to promote release of von Willebrand factor from the vascular endothelium. 54 Proinflammatory cytokines secreted by activated leukocytes are known to affect the coagulation and fibrinolytic systems. [30][31][32][33] Platelet-leukocyte interactions have also been shown to have a prothrombotic effect via upregulation and expression of tissue factor.…”

Granulocyte-macrophage colony-stimulating factor (GM-CSF): a chemoattractive agent for murine leukocytes in vivo

“…Increased rolling may occur indirectly through the generation of superoxide radicals from GM-CSF-activated, adherent neutrophils [34]. Superoxide can induce the expression of P-selectin on endothelial cells [35] and has been shown to increase selectin expression and recruit leukocytes in models of inflammation [36]. Of interest to this study, the SOD mimetic M40403 has been shown to reduce selectin expression and neutrophil infiltration in a model of experimental colitis [37].…”

Changes in the pattern of distribution of von Willebrand factor in rat aortic endothelial cells following thrombin generation in vivo

“…VWF is released from EC via either a constitutive or regulated pathway (Loesberg et al, 1983). The latter results from the release of VWF from WPB and occurs rapidly after EC stimulation with secretagogues including thrombin (Loesberg et al, 1983;Levine et al, 1982), the calcium ionophore A23187 (Loesberg et al, 1983), PMA (Loesberg et al, 1983), histamine (Hamilton & Sims, 1987), fibrin (Ribes et al, 1987), complement C5a (Foreman et al, 1994) and C5b-9 (Hattori et al, 1989) and reactive oxygen intermediates (Vischer et al, 1995). An average of only 5% of newly synthesized VWF is sorted into the WPB, while the remainder is constitutively secreted (Sporn et al, 1987).…”