The Procoagulant Activity of Apoptotic Cells Is Mediated by Interaction with Factor XII

Abstract

Apoptotic cells, by externalizing phosphatidylserine (PS) as a hallmark feature, are procoagulant. However, the mechanism by which apoptotic cells activate coagulation system remains unknown. Intrinsic coagulation pathway is initiated by coagulation factor XII (FXII) of contact activation system. The purpose of this study was to determine whether FXII is involved in procoagulant activity of apoptotic cells. Using western blotting and chromogenic substrate assay, we found that incubation with apoptotic cells, but not with viable cells, resulted in rapid cleavage and activation of FXII in the presence of prekallikrein and high molecular weight kininogen (HK), other two components of contact activation system. As detected by flow cytometry, FXII bound to apoptotic cells in a concentration-dependent manner, which was inhibited by annexin V and PS liposome. Direct association of FXII with PS was confirmed in a surface plasmon resonance assay. Clotting time of FXII-deficient plasma induced by apoptotic cells was significantly prolonged, which was fully reversed by replenishment with FXII. Corn trypsin inhibitor, a FXII inhibitor, completely prevented apoptotic cells-induced intrinsic tenase complex formation. Consistently, apoptotic cells significantly increased thrombin production in normal plasma, which was not affected by an inhibitory anti-tissue factor antibody. However, blocking of PS by annexin V, inhibition of FXII, or the deficiency of FXII suppressed apoptotic cells-induced thrombin generation. Addition of purified FXII to FXII-deficient plasma recovered thrombin generation to the normal plasma level. In conclusion, FXII binds to apoptotic cells via PS and becomes activated, thereby constituting a novel mechanism mediating the procoagulant activity of apoptotic cells.

Zika Virus Infection Induces Elevation of Tissue Factor Production and Apoptosis on Human Umbilical Vein Endothelial Cells

“…Previous studies indicated that cell apoptosis could activate the coagulation system (Greeno et al, 1996; Yang et al, 2017). In addition, several studies showed that ZIKV infection of several primary cells induced cell death (Quicke et al, 2016; Anfasa et al, 2017).…”

“…It is noteworthy that approximately 20% of dead cells were found in the mock control after 48 h of culture, which might be explained by the donor since we observed differences among various donors (data not showed). It has been shown that apoptotic cells are procoagulant (Bombeli et al, 1997; Bouvy et al, 2014; Yang et al, 2017). Although the mechanism of how apoptotic cells activate coagulation system remains to be determined, it was shown that both adherent and detached apoptotic HUVECs become procoagulant by increased expression of phosphatidylserine (PS) and the loss of anticoagulant components such as TM and TFPI (Bombeli et al, 1997).…”

Influence of factor XII deficiency on activated partial thromboplastin time (aPTT) in critically ill patients

“…As a consequence of infection and inflammation, FXII seems to be consumed by direct activation of FXII by pathogens [26] as well by activation by apoptotic cells via the externalized phosphatidylserines (PS) [27], extracellular nucleic acids such as RNA and DNA [28–30] as happens during neutrophil extracellular trap (NET) formation [31]. Furthermore, activated platelets and the platelet-derived microparticles (PMP) activate FXII via the exposed polyphosphates, such as phosphatidylserine (PS) [32].…”

Endothelial Dysfunction in Kidney Transplantation

“…Nevertheless, the impact of apoptosis may vary according to cell type and in certain conditions also favor inflammatory responses. Apoptotic endothelial cells externalize phosphatidylserine ( 80 ), which binds Factor XII to promote coagulation ( 81 ). Apoptotic endothelial cells also interact with other cell types through the release of extracellular vesicles which can in turn promote inflammation.…”