Anti-β2GPI/β2GPI induces neutrophil extracellular traps formation to promote thrombogenesis via the TLR4/MyD88/MAPKs axis activation

Antiphospholipid antibodies (aPLs) are a large group of heterogeneous antibodies that bind to anionic phospholipids alone or in combination with phospholipid binding proteins. Increasing evidence has converged to indicate that aPLs especially anti-β2 glycoprotein I antibody (anti-β2GPI) correlate with stroke severity and outcome. Though studies have shown that aPLs promote thrombus formation in a neutrophil-dependent way, the underlying mechanisms remain largely unknown. In the present study, we investigated the effect of anti-β2GPI in complex with β2GPI (anti-β2GPI/β2GPI) on neutrophil extracellular traps (NETs) formation and thrombus generation in vitro and in vivo. We found that anti-β2GPI/β2GPI immune complex induced NETs formation in a time- and concentration-dependent manner. This effect was mediated by its interaction with TLR4 and the production of ROS. We demonstrated that MyD88-IRAKs-MAPKs, an intracellular signaling pathway, was involved in anti-β2GPI/β2GPI-induced NETs formation. We also presented evidence that tissue factor was expressed on anti-β2GPI/β2GPI-induced NETs, and NETs could promote platelet aggregation in vitro. In addition, we identified that anti-β2GPI/β2GPI-induced NETs enhanced thrombus formation in vivo, and this effect was counteracted by using DNase I. Our data suggest that anti-β2GPI/β2GPI induces NETs formation to promote thrombogenesis via the TLR4/MyD88/MAPKs axis activation, and could be a potentially novel target for aPLs related ischemic stroke.