Abstract：
Thromboembolic events are common in patients with essential thrombocythemia (ET). However, the pathophysiological mechanisms underlying the increased thrombotic risk remain to be determined. Here, we perform the first phenotypical characterization of platelet expression using single-cell mass cytometry in six ET patients and six age- and sex-matched healthy individuals. A large panel of 18 transmembrane regulators of platelet function and activation were analyzed, at baseline and after ex-vivo stimulation with thrombin receptor-activating peptide (TRAP). We detected a significant overexpression of the activation marker CD62P (p-Selectin) (p = .049) and the collagen receptor GPVI (p = .044) in non-stimulated ET platelets. In contrast, ET platelets had a lower expression of the integrin subunits of the fibrinogen receptor GPIIb/IIIa CD41 (p = .036) and CD61 (p = .044) and of the von Willebrand factor receptor CD42b (p = .044). Using the FlowSOM algorithm, we identified 2 subclusters of ET platelets with a prothrombotic expression profile, one of them (cluster 3) significantly overrepresented in ET (22.13% of the total platelets in ET, 2.94% in controls, p = .035). Platelet counts were significantly increased in ET compared to controls (p = .0123). In ET, MPV inversely correlated with platelet count (r=-0.96). These data highlight the prothrombotic phenotype of ET and postulate GPVI as a potential target to prevent thrombosis in these patients.
Essential thrombocythemia (ET) is a rare disease characterized by an increased number of platelets in the blood. As a complication, many of these patients develop a blood clot, which can be life-threatening. So far, the reason behind the higher risk of blood clots is unclear. In this study, we analyzed platelet surface markers that play a critical role in platelet function and platelet activation using a modern technology called mass cytometry. For this purpose, blood samples from 6 patients with ET and 6 healthy control individuals were analyzed. We found significant differences between ET platelets and healthy platelets. ET platelets had higher expression levels of p-Selectin (CD62P), a key marker of platelet activation, and of the collagen receptor GPVI, which is important for clot formation. These results may be driven by a specific platelet subcluster overrepresented in ET. Other surface markers, such as the fibrinogen receptor GPIIb/IIIa CD41, CD61, and the von Willebrand factor receptor CD42b, were lower expressed in ET platelets. When ET platelets were treated with the clotting factor thrombin (thrombin receptor-activating peptide, TRAP), we found a differential response in platelet activation compared to healthy platelets. In conclusion, our results show an increased activation and clotting potential of ET platelets. The platelet surface protein GPVI may be a potential drug target to prevent abnormal blood clotting in ET patients.
Essential thrombocythemia (ET) is a rare disease characterized by an increased number of platelets in the blood. As a complication, many of these patients develop a blood clot, which can be life-threatening. So far, the reason behind the higher risk of blood clots is unclear. In this study, we analyzed platelet surface markers that play a critical role in platelet function and platelet activation using a modern technology called mass cytometry. For this purpose, blood samples from 6 patients with ET and 6 healthy control individuals were analyzed. We found significant differences between ET platelets and healthy platelets. ET platelets had higher expression levels of p-Selectin (CD62P), a key marker of platelet activation, and of the collagen receptor GPVI, which is important for clot formation. These results may be driven by a specific platelet subcluster overrepresented in ET. Other surface markers, such as the fibrinogen receptor GPIIb/IIIa CD41, CD61, and the von Willebrand factor receptor CD42b, were lower expressed in ET platelets. When ET platelets were treated with the clotting factor thrombin (thrombin receptor-activating peptide, TRAP), we found a differential response in platelet activation compared to healthy platelets. In conclusion, our results show an increased activation and clotting potential of ET platelets. The platelet surface protein GPVI may be a potential drug target to prevent abnormal blood clotting in ET patients.
摘要：
血栓栓塞事件在原发性血小板增多症（ET）患者中很常见。然而,血栓形成风险增加的病理生理机制仍有待确定.这里,我们在6例ET患者和6例年龄和性别匹配的健康个体中使用单细胞质量细胞计数对血小板表达进行了首次表型鉴定.分析了18个血小板功能和活化的跨膜调节剂，在基线和用凝血酶受体激活肽（TRAP）离体刺激后。我们在未刺激的ET血小板中检测到活化标志物CD62P（p-选择素）（p=.049）和胶原蛋白受体GPVI（p=.044）的显着过表达。相比之下,ET血小板的纤维蛋白原受体GPIIb/IIIaCD41（p=.036）和CD61（p=.044）的整联蛋白亚基和vonWillebrand因子受体CD42b（p=.044）的表达较低。使用FlowSOM算法，我们确定了2个具有血栓前表达谱的ET血小板亚群，其中之一（第3组）在ET中明显超标（ET中占总血小板的22.13％，对照组为2.94%，p=.035）。与对照组相比，ET中的血小板计数显着增加（p=.0123）。在ET,MPV与血小板计数呈负相关(r=-0.96)。这些数据突出了ET的血栓前表型，并假定GPVI是预防这些患者血栓形成的潜在目标。
原发性血小板增多症（ET）是一种罕见的疾病，其特征是血液中血小板数量增加。作为一个并发症，这些患者中的许多人形成血凝块，可能会危及生命.到目前为止,血栓风险较高背后的原因尚不清楚.在这项研究中,我们使用一种称为质量细胞仪的现代技术分析了在血小板功能和血小板活化中起关键作用的血小板表面标志物.为此,对6例ET患者和6例健康对照者的血样进行分析。我们发现ET血小板和健康血小板之间存在显着差异。ET血小板有较高的p-选择素（CD62P）表达，血小板活化的关键标志,和胶原蛋白受体GPVI，这对凝块形成很重要。这些结果可能是由ET中过度代表的特定血小板亚簇驱动的。其他表面标记,如纤维蛋白原受体GPIIb/IIIaCD41、CD61和血管性血友病因子受体CD42b，在ET血小板中表达较低。当ET血小板用凝血因子凝血酶（凝血酶受体激活肽，陷阱),我们发现,与健康血小板相比,血小板活化反应有差异.总之,我们的结果显示ET血小板的活化和凝血潜能增加.血小板表面蛋白GPVI可能是预防ET患者异常凝血的潜在药物靶标。
原发性血小板增多症（ET）是一种罕见的疾病，其特征是血液中血小板数量增加。作为一个并发症，这些患者中的许多人形成血凝块，可能会危及生命.到目前为止,血栓风险较高背后的原因尚不清楚.在这项研究中,我们使用一种称为质量细胞仪的现代技术分析了在血小板功能和血小板活化中起关键作用的血小板表面标志物.为此,对6例ET患者和6例健康对照者的血样进行分析。我们发现ET血小板和健康血小板之间存在显着差异。ET血小板有较高的p-选择素（CD62P）表达，血小板活化的关键标志,和胶原蛋白受体GPVI，这对凝块形成很重要。这些结果可能是由ET中过度代表的特定血小板亚簇驱动的。其他表面标记,如纤维蛋白原受体GPIIb/IIIaCD41、CD61和血管性血友病因子受体CD42b，在ET血小板中表达较低。当ET血小板用凝血因子凝血酶（凝血酶受体激活肽，陷阱),我们发现,与健康血小板相比,血小板活化反应有差异.总之,我们的结果显示ET血小板的活化和凝血潜能增加.血小板表面蛋白GPVI可能是预防ET患者异常凝血的潜在药物靶标。
