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Thrombin in the Activation of the Fluid Contact Phase in Patients with Hereditary Angioedema Carrying the F12 P.Thr309Lys Variant
Clinical Reviews in Allergy & Immunology ( IF 9.1 ) Pub Date : 2021-03-16 , DOI: 10.1007/s12016-021-08840-x
R López-Gálvez 1 , M E de la Morena-Barrio 1 , A Miñano 1 , M Pathak 2 , C Marcos 3 , J Emsley 2 , T Caballero 4, 5, 6 , M López-Trascasa 6, 7 , V Vicente 1 , J Corral 1 , A López-Lera 5, 6
Affiliation  

Hereditary angioedema due to pathogenic FXII variants (HAE-FXII) is a rare dominant disease caused by increased activation of the plasma contact system. The most prevalent HAE-FXII variant, c.1032C > A p.Thr309Lys (FXII309Lys), results in a smaller FXII protein with increased sensitivity to fluid-phase activation by poorly understood mechanisms. We aimed to investigate the functionality of the FXII309Lys variant in 33 HAE-FXII patients, 25 healthy controls and 46 patients with congenital disorders of glycosylation (CDG). Activation of the plasma contact system was assessed by western blot and amidolytic assay in basal conditions or after treatment with either artificial or physiological activators. Recombinant wild-type and FXII309Lys variants were expressed in S2 insect (Drosophila) cells. Amidolytic and fibrin generation assays were performed in fresh plasma samples. FXII309Lys samples exhibited an increased electrophoretic mobility comparable with N-glycan-deficient FXII from CDG patients and asialo-FXII generated by neuraminidase treatment. They presented increased sensitivity to activation by dextran sulphate and silica which resulted in the generation of an aberrant 37-kDa heavy chain. We did not observe increased susceptibility of FXII309Lys to proteolysis by exogenous or tPA-generated plasmin. However, both exogenous and endogenous thrombin cleaved the FXII309Lys variant, releasing a 37-kDa fragment and resulting in enhanced proteolytic activation on the fluid phase. This model supports a sequential proteolytic activation process involving thrombin priming of FXII309Lys, followed by kallikrein cleavage and generation of active βFXIIa. The present results and the observation that angioedema episodes in HAE-FXII patients occur predominantly during hypercoagulable situations suggest a key role for thrombin.



中文翻译:

凝血酶激活携带 F12 P.Thr309Lys 变体的遗传性血管性水肿患者的液体接触阶段

由致病性 FXII 变异 (HAE-FXII) 引起的遗传性血管性水肿是一种罕见的显性疾病,由血浆接触系统的激活增加引起。最普遍的 HAE-FXII 变体 c.1032C > A p.Thr309Lys (FXII 309Lys ) 会导致较小的 FXII 蛋白通过知之甚少的机制增加对液相激活的敏感性。我们旨在研究 FXII 309Lys变体在 33 名 HAE-FXII 患者、25 名健康对照和 46 名先天性糖基化障碍 (CDG) 患者中的功能。在基础条件下或用人工或生理活化剂处理后,通过蛋白质印迹和酰胺分解测定评估血浆接触系统的活化。重组野生型和 FXII 309Lys变体在 S2 昆虫(果蝇)细胞中表达。在新鲜血浆样品中进行酰胺分解和纤维蛋白生成测定。FXII 309Lys样品表现出增加的电泳迁移率,可与来自 CDG 患者的 N-聚糖缺陷型 FXII 和神经氨酸酶处理产生的去唾液酸-FXII 相媲美。他们对硫酸葡聚糖和二氧化硅的活化表现出更高的敏感性,从而导致产生异常的 37-kDa 重链。我们没有观察到 FXII 309Lys对外源性或 tPA 生成的纤溶酶蛋白水解的敏感性增加。然而,外源性和内源性凝血酶都切割了 FXII 309Lys变体,释放一个 37-kDa 片段并导致流体相上的蛋白水解活化增强。该模型支持顺序蛋白水解激活过程,包括 FXII 309Lys的凝血酶引发,然后是激肽释放酶裂解和活性 βFXIIa 的产生。目前的结果和观察到 HAE-FXII 患者的血管性水肿发作主要发生在高凝状态下,这表明凝血酶的关键作用。

更新日期:2021-03-16
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