Extracellular vesicles released upon stimulation with antiphospholipid antibodies: An actual direct procoagulant mechanism or a new factor in the lupus anticoagulant paradox?. Issue 133 (December 2022)

• Record Type: Journal Article
• Authors: Álvarez, Daniel; Rúa, Carolina; Velásquez Berrío, Manuela; Cataño, John Ubeimar; Escudero, Carlos; Cadavid J, Ángela P.
• Is Part Of: Journal of autoimmunity. Issue 133(2022)
• Publication Date: 2022-12
• Subjects: Antiphospholipid antibodies -- Cell-derived extracellular vesicles -- Lupus coagulation inhibitor -- Thrombosis -- Mitogen-activated protein kinase kinases -- Antiphospholipid syndrome; aPL Antiphospholipid antibodies -- EVs Extracellular vesicles -- EDEVs Endothelial cell-derived medium/large EVs -- aPL-EDEVs Endothelial cell-derived medium/large EVs released upon stimulation with aPL; Autoimmunity -- Periodicals; Autoimmune diseases -- Periodicals; Autoantibodies -- Periodicals; Autoimmune Diseases -- Periodicals; Auto-immunité -- Périodiques; Maladies auto-immunes -- Périodiques; Electronic journals; 616.978005
• DOI: 10.1016/j.jaut.2022.102905
• Languages: English
• ISSNs: 0896-8411

Abstract

Abstract: Antiphospholipid antibodies (aPL) lead to a hypercoagulable state in vivo . Paradoxically, some of these autoantibodies perform as inhibitors of the coagulation cascade in vitro (a phenomenon referred to as "lupus anticoagulant"). The presence of lupus anticoagulant has been related to an increased quantity of plasma extracellular vesicles, which may constitute a direct procoagulant mechanism in antiphospholipid syndrome. This study investigates whether or not endothelial cell-derived extracellular vesicles released upon stimulation with aPL (aPL-EDEVs) are related to a higher direct coagulation activity. Using an in vitro model of endothelium, flow cytometry and a recalcified plasma-based assay, we found that the coagulation activity of aPL-EDEVs is mainly conditioned by the lupus anticoagulant-like activity of autoantibodies. Nevertheless, in the presence of β2 glycoprotein I, a cofactor of aPL during the stimulation of endothelial cells, the coagulation activity of EDEVs is restored in a mitogen-activated protein kinase kinases 1 and 2 (MEK1/2)-dependent manner. This phenomenon was especially evident when using immunoglobulins G from patients with vascular and obstetric primary antiphospholipid syndrome who manifest refractoriness to treatment. Our findings suggest that the role of aPL-EDEVs in the antiphospholipid syndrome-related hypercoagulable state may not rely on their capacity to enhance clotting directly. While β2 glycoprotein I performs as a procoagulant cofactor and restores the coagulation activity of extracellular vesicles via MEK1/2 pathway, proportionally, autoantibodies interact with aPL-EDEVs and exhaust their coagulation properties. Further analysis is required to establish whether lupus anticoagulant-like autoantibodies opsonise extracellular vesicles and whether opsonised vesicles may lead to thrombosis by indirect means. Graphical abstract: The coagulation activity resulting from the interaction between recalcified plasma, antiphospholipid antibodies, and endothelial cell-derived extracellular vesicles released upon stimulation with antiphospholipid antibodies is mainly conditioned by autoantibodies with lupus anticoagulant-like activity. Nevertheless, β2 glycoprotein I can overcome this anticoagulant effect by increasing the number of released vesicles. The lupus anticoagulant-like activity directly exerted over extracellular vesicles and the β2 glycoprotein I-dependent procoagulant activity are directly proportional and have shown to be higher in antibodies from patients with vascular and obstetric primary antiphospholipid syndrome who manifest refractoriness to treatment. Inhibiting MEK1/2 pathway hinders the procoagulant action that β2GPI as an IgG cofactor exerts on the EDEV-rich supernatants although this does not occur through a drop in the amount of released EDEVs. aPL, antiphospholipid antibodies; LA, lupus anticoagulant; EDEVs, endothelial cell-derived medium/large extracellular vesicles; IgG, immunoglobulin G; RI, Vascular and obstetric APS (primary and refractory); β2GPI, β2 glycoprotein I; MEK1/2, mitogen-activated protein kinase kinases 1 and 2. Image 1 Highlights: The LA-like activity of autoantibodies prevails in the EV-rich supernatants from endothelial cells stimulated with aPL. This anticoagulant effect can be countered by using β2GPI as a cofactor of aPL upon endothelial cell stimulation. Along with β2GPI, the MEK1/2 pathway might be necessary to support the procoagulant properties of EVs in APS.