The Procoagulant Activity of Apoptotic Cells Is Mediated by Interaction with Factor XII.
The Procoagulant Activity of Apoptotic Cells Is Mediated by Interaction with Factor XII.
复制标题
凋亡细胞的促凝血活性是通过与因子 XII 相互作用介导的
DOI：
10.3389/fimmu.2017.01188
复制
发表时间：
2017
影响因子：
7.3
通讯作者：
Wu Y
中科院分区：
文献类型：
--
作者：
Yang A;Chen F;He C;Zhou J;Lu Y;Dai J;Birge RB;Wu Y
通过外化磷脂酰丝氨酸(PS)作为标志的凋亡细胞是促凝剂。然而，凋亡细胞激活凝血系统的机制尚不清楚。内源性凝血途径是由接触激活系统的凝血因子XII(FXII)启动的。本研究的目的是确定FXII是否参与了凋亡细胞的促凝血活性。通过Western blotting和显色底物分析，我们发现，在接触激活系统的另外两个成分--前激肽释放酶和高分子激肽原(HK)的存在下，FXII与凋亡细胞孵育，而与活细胞孵育，导致FXII的快速切割和激活。流式细胞仪检测显示，FXII以浓度依赖的方式与凋亡细胞结合，这种结合可被膜联蛋白V和PS脂质体抑制。表面等离子共振分析证实了FXII与PS的直接关联。FXII缺乏性血浆由凋亡细胞诱导的凝血时间显著延长，补给FXII可完全逆转这一现象。玉米胰酶抑制剂是一种FXII抑制剂，可以完全阻止细胞凋亡诱导的内源性张力酶复合体的形成。一直以来，凋亡细胞显著增加了正常血浆中凝血酶的生成，而这不受抑制性抗组织因子抗体的影响。然而，膜联蛋白V阻断PS、抑制FXII或FXII的缺失抑制了凋亡细胞诱导的凝血酶的产生。将纯化的FXII加入到FXII缺乏的血浆中，凝血酶的生成恢复到正常血浆水平。总之，FXII通过PS与凋亡细胞结合，并被激活，从而构成了一种新的机制，介导了凋亡细胞的促凝血活性。
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.