Popov Viola M, Vladareanu Ana M, Bumbea Horia, Kovacs Eugenia, Savopol Tudor, Iordache Maria M, Moisescu Mihaela G
aHematology Department, Colentina Clinical Hospital, Bucharest bHematology Department, University Emergency Hospital Bucharest and Carol Davila University of Medicine and Pharmacy cBiophysics and Cellular Biotechnology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
Blood Coagul Fibrinolysis. 2015 Oct;26(7):743-9. doi: 10.1097/MBC.0000000000000287.
Platelet function is influenced by changes in membrane fluidity that has an important role in the expression of platelet receptors and in modulating the activity of proteins like phospholipase C or proteinkinase C. In freshly prepared platelets, membrane fluidity modifies the aggregation/agglutination function. Reactive oxygen species (ROS) represent another important parameter involved in platelet receptor activation. There is a certain association of high levels of ROS and iron overload. Patients with hemochromatosis have low platelet aggregation induced by thrombin; little is known about the anemia and effects of iron overload on platelet activation in myelodysplastic syndromes (MDS) patients. Study of platelet membrane fluidity and ROS production changes in patients with MDS and possible correlations with altered platelet function as reflected in aggregation curves and platelet receptor expression. To find out possible correlations of fluidity of platelet membrane and ROS level with hematologic parameters and iron levels. The prospective study included 34 patients with myelodysplastic syndromes classified according to French-American-British cooperative group proposals and 29 healthy volunteers. Platelet membrane fluidity was quantified by fluorescence anisotropy measurements using the marker 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene p-toluenesulfonate. ROS production was evaluated by fluorescence measurements using 2',7'-dichlorodihydrofluorescein diacetate. Platelet function was analyzed by optical aggregometry using the agonists adenosine diphosphate, collagen, ristocetin and epinephrine. The expression of platelet receptors CD41/CD61, CD42a/CD42b and CD62P/CD63 was evaluated by flow cytometry. Platelet membrane fluidity in patients with MDS was similar to that of healthy volunteers and did not vary according to the risk category. Patients with MDS had increased platelet ROS production compared with the control group without statistical correlation with membrane fluidity. We found a negative correlation of ROS levels with the severity of anemia (R = -0.587, P = 0.017). Platelet response was reduced in patients with MDS compared with volunteers, for all reagents. The response was different according to the risk category only in case of ristocetin or collagen. Patients with anemia presented a decreased platelet aggregation induced by collagen or ristocetin (collagen: R = 0.395, P = 0.003; ristocetin: R = 0.420, P = 0.002). The membrane fluidity of platelets from MDS patients appeared unmodified, but the ROS production was increased in all risk categories of MDS. The levels of ROS were correlated with the degree of anemia, which, in turn, had a negative impact on the platelet aggregation function induced by collagen or ristocetin.
血小板功能受膜流动性变化的影响，膜流动性在血小板受体表达以及调节磷脂酶C或蛋白激酶C等蛋白质活性方面发挥着重要作用。在新制备的血小板中，膜流动性会改变聚集/凝集功能。活性氧（ROS）是参与血小板受体激活的另一个重要参数。高水平的ROS与铁过载存在一定关联。血色素沉着症患者的凝血酶诱导的血小板聚集较低；关于骨髓增生异常综合征（MDS）患者的贫血以及铁过载对血小板激活的影响知之甚少。研究MDS患者的血小板膜流动性和ROS产生变化，以及与聚集曲线和血小板受体表达所反映的血小板功能改变之间的可能相关性。以找出血小板膜流动性和ROS水平与血液学参数及铁水平之间的可能相关性。前瞻性研究纳入了34例根据法国 - 美国 - 英国合作组方案分类的骨髓增生异常综合征患者和29名健康志愿者。使用标记物1 - （4 - 三甲基铵苯基） - 6 - 苯基 - 1,3,5 - 己三烯对甲苯磺酸盐通过荧光偏振测量来量化血小板膜流动性。使用2',7' - 二氯二氢荧光素二乙酸酯通过荧光测量来评估ROS产生。使用激动剂二磷酸腺苷、胶原、瑞斯托菌素和肾上腺素通过光学聚集测定法分析血小板功能。通过流式细胞术评估血小板受体CD41/CD61、CD42a/CD42b和CD62P/CD63的表达。MDS患者的血小板膜流动性与健康志愿者相似，且不随风险类别而变化。与对照组相比，MDS患者的血小板ROS产生增加，但与膜流动性无统计学相关性。我们发现ROS水平与贫血严重程度呈负相关（R = -0.587，P = 0.017）。与志愿者相比，MDS患者对所有试剂的血小板反应均降低。仅在瑞斯托菌素或胶原的情况下，反应因风险类别而异。贫血患者的胶原或瑞斯托菌素诱导的血小板聚集降低（胶原：R = 0.395，P = 0.003；瑞斯托菌素：R = 0.420，P = 0.002）。MDS患者血小板的膜流动性似乎未改变，但在MDS的所有风险类别中ROS产生均增加。ROS水平与贫血程度相关，而贫血又对胶原或瑞斯托菌素诱导的血小板聚集功能产生负面影响。
