Anti-β2 glycoprotein I （anti-β2GP I） antibodies are important contributors to thrombosis, especially in patients with antiphospholipid syndrome （APS）. However, the mechanism by which anti-β2GP I antibodies are involved in the pathogenesis of thrombosis is not fully understood. In this report, we investigated the role of anti- β2GP I antibodies in complexes with β2GP I as mediators of platelet activation, which can serve as a potential source contributing to thrombosis. We examined the involvement of the apolipoprotein E receptor 2＇ （apoER2＇） and glycoprotein I ba （GP I bα） in platelet activation induced by the anti-β2GP I/β2GP I complex. The interaction between the anti-β2GP I/β2GP I complex and platelets was examined using in vitro methods, in which the Fc portion of the antibody was immobilized using protein A coated onto a microtiter plate. Platelet activation was assessed by measuring GP II b/III a activation and F-selectin expression and thromboxane B2 production as well as p38 mitogen-activated protein kinase phosphorylation. Our results revealed that the anti-β2GPI/β2GPI complex was able to activate platelets, and this activation was inhibited by either the anti-GP I bα antibody or the apoER2＇ inhibitor. Results showed that the anti-β2GPI/β2GPl complex induced platelet activation via GP I bα and apoER2＇, which may then contribute to the prothrombotic tendency in APS patients.
Wenjing ZhangFei GaoDonghe LuNa SunXiaoxue YinMeili JinYanhong Liu
Anti-β2 glycoprotein I(anti-β2GPI)antibodies are important contributors to the development of thrombosis.Anti-β2GPI antibody complexes withβ2GPI are well known to activate monocytes and endothelial cells via the intracellular NF-kB pathway with prothrombotic implications.By contrast,the interaction of anti-β2GPI/β2GPI complexes with platelets has not been extensively studied.The p38 mitogen-activated protein kinase(MAPK)pathway has been recognized to be an important intracellular signaling pathway in the coagulation cascade and an integral component of arterial and venous thrombosis.The present study reveals that levels of anti-β2GPI/β2GPI complexes in sera are positively associated with p38MAPK phosphorylation of platelets in thrombotic patients.Furthermore,SB203580 inhibits anti-β2GPI/β2GPI complex-induced platelet activation.Thrombus formation decreased in p38MAPK−/−mice after treatment with anti-β2GPI/β2GPI complexes.In conclusion,p38MAPK may be a treatment target for anti-β2GPI antibody-associated thrombotic events.
Wenjing ZhangCaijun ZhaXiumin LuRuichun JiaFei GaoQi SunMeili JinYanhong Li
