Tong Dongxia, Yu Muxin, Guo Li, Li Tao, Li Jihe, Novakovic Valerie A, Dong Zengxiang, Tian Ye, Kou Junjie, Bi Yayan, Wang Jinghua, Zhou Jin, Shi Jialan
Department of Hematology, First Hospital, Harbin Medical University, 23 Youzheng Street, Nangang District, Harbin, 150001, China.
Department of Cardiology, First Hospital, Harbin Medical University, Harbin, China.
Ann Hematol. 2018 Apr;97(4):605-616. doi: 10.1007/s00277-018-3228-6. Epub 2018 Jan 13.
The mechanisms of thrombogenicity in essential thrombocythemia (ET) are complex and not well defined. Our objective was to explore whether phosphatidylserine (PS) exposure on blood cells and endothelial cells (ECs) can account for the increased thrombosis and distinct thrombotic risks among mutational subtypes in ET. Using flow cytometry and confocal microscopy, we found that the levels of PS-exposing erythrocytes, platelets, leukocytes, and serum-cultured ECs were significantly higher in each ET group [JAK2, CALR, and triple-negative (TN) (all P < 0.001)] than those in controls. Among ET patients, those with JAK2 mutations showed higher levels of PS-positive erythrocytes, platelets, neutrophils, and serum-cultured ECs than TN patients or those with CALR mutations, which show similar levels. Coagulation function assays showed that higher levels of PS-positive blood cells and serum-cultured ECs led to markedly shortened coagulation time and dramatically increased levels of FXa, thrombin, and fibrin production. This procoagulant activity could be largely blocked by addition of lactadherin (approx. 70% inhibition). Confocal microscopy showed that the FVa/FXa complex and fibrin fibrils colocalized with PS on ET serum-cultured ECs. Additionally, we found a relationship between D-dimer, prothrombin fragment F1 + 2, and PS exposure. Our study reveals a previously unrecognized link between hypercoagulability and exposed PS on cells, which might also be associated with distinct thrombotic risks among mutational subtypes in ET. Thus, blocking PS-binding sites may represent a new therapeutic target for preventing thrombosis in ET.
原发性血小板增多症（ET）中血栓形成的机制复杂且尚未完全明确。我们的目的是探讨血细胞和内皮细胞（ECs）上磷脂酰丝氨酸（PS）的暴露是否可以解释ET中不同突变亚型之间血栓形成增加和独特的血栓形成风险。使用流式细胞术和共聚焦显微镜，我们发现每个ET组[JAK2、CALR和三阴性（TN）（所有P < 0.001）]中暴露PS的红细胞、血小板、白细胞和血清培养的ECs水平均显著高于对照组。在ET患者中，JAK2突变患者的PS阳性红细胞、血小板、中性粒细胞和血清培养的ECs水平高于TN患者或CALR突变患者，后两者水平相似。凝血功能检测表明，较高水平的PS阳性血细胞和血清培养的ECs导致凝血时间显著缩短，FXa、凝血酶和纤维蛋白生成水平显著增加。添加乳凝集素可在很大程度上阻断这种促凝活性（约70%抑制）。共聚焦显微镜显示，FVa/FXa复合物和纤维蛋白原纤维与ET血清培养的ECs上的PS共定位。此外，我们发现D-二聚体、凝血酶原片段F1 + 2与PS暴露之间存在关联。我们的研究揭示了高凝状态与细胞上暴露的PS之间以前未被认识到的联系，这也可能与ET中不同突变亚型之间独特的血栓形成风险有关。因此，阻断PS结合位点可能代表预防ET血栓形成的新治疗靶点。
