Voigtlaender M, Holstein K, Spath B, Bokemeyer C, Langer F
II. Medizinische Klinik und Poliklinik, Hubertus Wald Tumorzentrum - Universitäres Cancer Center Hamburg (UCCH), Universitätsklinikum Eppendorf, Hamburg, Germany.
Haemophilia. 2016 Nov;22(6):e537-e544. doi: 10.1111/hae.13074. Epub 2016 Oct 20.
Despite similar residual factor VIII activity, patients with haemophilia A (HA) show significant interindividual variability with regard to bleeding frequency and severity, suggesting that additional factors modulate thrombin generation and fibrin deposition. Protein disulphide isomerase (PDI) is an abundant oxidoreductase that exerts pleiotropic effects in primary and secondary haemostasis and contributes to thrombosis and vascular inflammation.
We conducted a pilot study to explore a potential role of platelet PDI in patients with HA.
Expression and release of platelet PDI were studied by flow cytometry and enzyme-linked immunosorbent assay, respectively.
Compared to healthy male controls (n = 12), patients with HA (n = 24) showed significantly increased expression of PDI antigen on ADP- or TRAP-6-, but not on buffer-treated platelets, a finding that could not be explained by enhanced platelet activation, as indicated by expression of the α-granule protein, CD62P (P-selectin). While platelet agonists did not affect PDI secretion in healthy male controls, increased levels of PDI antigen were found in supernatants of TRAP-6-treated platelets from patients with HA. Importantly, in two patients with exceedingly high TRAP-6-induced PDI release over baseline, findings were consistent when platelets were isolated and stimulated on a separate occasion. No obvious association was found between platelet PDI and bleeding phenotype in this patient cohort.
Agonist-induced expression and release of platelet PDI were increased in patients with HA. Larger studies are needed to clarify if variations in this platelet response contribute to the diversity in bleeding frequency and severity among patients with congenital factor VIII deficiency.
尽管血友病A（HA）患者的残余因子VIII活性相似，但在出血频率和严重程度方面存在显著的个体差异，这表明其他因素可调节凝血酶生成和纤维蛋白沉积。蛋白质二硫键异构酶（PDI）是一种丰富的氧化还原酶，在初级和次级止血中发挥多效作用，并参与血栓形成和血管炎症。
我们进行了一项初步研究，以探讨血小板PDI在HA患者中的潜在作用。
分别通过流式细胞术和酶联免疫吸附测定法研究血小板PDI的表达和释放。
与健康男性对照（n = 12）相比，HA患者（n = 24）在经ADP或TRAP-6处理的血小板上PDI抗原的表达显著增加，但在缓冲液处理的血小板上未增加，这一发现无法用血小板活化增强来解释，α颗粒蛋白CD62P（P-选择素）的表达表明了这一点。虽然血小板激动剂对健康男性对照中的PDI分泌没有影响，但在HA患者经TRAP-6处理的血小板上清液中发现PDI抗原水平升高。重要的是，在两名TRAP-6诱导的PDI释放比基线水平极高的患者中，当在另一个时间点分离并刺激血小板时，结果是一致的。在该患者队列中，未发现血小板PDI与出血表型之间存在明显关联。
HA患者中激动剂诱导的血小板PDI表达和释放增加。需要进行更大规模的研究，以阐明这种血小板反应的变化是否导致先天性因子VIII缺乏患者出血频率和严重程度的差异。
