Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden.
Department of Clinical Sciences, Lund University, Skåne University Hospital, Malmö, Sweden.
J Thromb Haemost. 2019 Apr;17(4):585-595. doi: 10.1111/jth.14405. Epub 2019 Mar 11.
Essentials Protein S and FV-Short are synergistic cofactors to Tissue Factor Pathway Inhibitor α (TFPIα). An assay for the TFPIα synergistic cofactor activity of protein S with FV-Short was developed. The assay was specific for the synergistic TFPIα-cofactor activity of free protein S. Protein S deficient individuals with known mutations were correctly distinguished from controls. SUMMARY: Background Protein S is an anticoagulant cofactor to both activated protein C and tissue factor pathway inhibitor (TFPIα). The TFPIα-cofactor activity of protein S is stimulated by a short isoform of factor V (FV-Short), the two proteins functioning in synergy. Objective Using the synergistic TFPIα-cofactor activity between protein S and FV-Short to develop a functional test for plasma protein S. Patients/Methods TFPIα-mediated inhibition of FXa in the presence of FV-Short, protein S and negatively charged phospholipid vesicles was monitored in time by synthetic substrate S2765. TFPIα, FXa and FV-Short were purified proteins, whereas diluted plasma from protein S deficient patients or controls were used as source for protein S. Results The assay was specific for free protein S demonstrating good correlation to free protein S plasma levels (r = 0.92) with a Y-axis intercept of -5%. Correlation to concentrations of total protein S (free and C4BPβ+-bound) was lower (r = 0.88) and the Y-axis intercept was +46%, which is consistent with the specificity for free protein S. The test distinguished protein S-deficient individuals from 6 families with known ProS1 mutations from family members having no mutation. Protein S levels of warfarin-treated protein S deficient cases were lower than protein S in cases treated with warfarin for other causes. Conclusions We describe a new assay measuring the TFPIα-cofactor activity of plasma protein S. The test identifies type I/III protein S deficiencies and will be a useful tool to detect type II protein S deficiency having defective TFPIα-cofactor activity.
蛋白质 S 和 FV-Short 是组织因子途径抑制剂 α (TFPIα) 的协同辅助因子。开发了一种用于测定蛋白质 S 与 FV-Short 对 TFPIα 协同辅助因子活性的测定法。该测定法特异性针对游离蛋白质 S 的协同 TFPIα 辅助因子活性。具有已知突变的蛋白质 S 缺乏个体与对照个体正确区分。
背景 蛋白质 S 是激活蛋白 C 和组织因子途径抑制剂 (TFPIα) 的抗凝辅助因子。蛋白质 S 的 TFPIα 辅助因子活性受因子 V 短异构体 (FV-Short) 的刺激，两种蛋白协同作用。
目的 使用蛋白质 S 和 FV-Short 之间的协同 TFPIα 辅助因子活性，开发一种用于血浆蛋白质 S 的功能测试。
患者/方法 在 FV-Short、蛋白质 S 和带负电荷的磷脂囊泡存在下，通过合成底物 S2765 监测 TFPIα 介导的 FXa 抑制。TFPIα、FXa 和 FV-Short 是纯化蛋白，而稀释的来自蛋白质 S 缺乏症患者或对照的血浆用作蛋白质 S 的来源。
结果 该测定法特异性针对游离蛋白质 S，与游离蛋白质 S 血浆水平（r=0.92）具有良好相关性，Y 轴截距为-5%。与总蛋白质 S（游离和 C4BPβ+-结合）的浓度相关性较低（r=0.88），Y 轴截距为+46%，这与游离蛋白质 S 的特异性一致。该测试将蛋白质 S 缺乏个体与 6 个具有已知 ProS1 突变的家族成员从无突变的家族成员中区分开来。华法林治疗的蛋白质 S 缺乏症病例的蛋白质 S 水平低于其他原因接受华法林治疗的病例。
结论 我们描述了一种测量血浆蛋白质 S 的 TFPIα 辅助因子活性的新测定法。该测试可识别 I/III 型蛋白质 S 缺乏症，并将成为检测具有缺陷 TFPIα 辅助因子活性的 II 型蛋白质 S 缺乏症的有用工具。
