Research Laboratory, 3rd Department of Internal Medicine, Semmelweis University, Budapest, Hungary.
MTA-SE Research Group of Immunology and Hematology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary.
Front Immunol. 2020 May 5;11:794. doi: 10.3389/fimmu.2020.00794. eCollection 2020.
C1-inhibitor (C1-INH) is an important regulator of the complement, coagulation, fibrinolytic and contact systems. The quantity of protease/C1-INH complexes in the blood is proportional to the level of the activation of these four cascade-like plasma enzyme systems. Parallel determination of C1-INH-containing activation complexes could be important to understand the regulatory role of C1-INH in diseases such as hereditary angioedema (HAE) due to C1-INH deficiency (C1-INH-HAE). We developed in-house ELISAs to measure the concentration of complexes of C1-INH formed with active proteases: C1r, C1s, MASP-1, MASP-2, plasma kallikrein, factor XIIa, factor XIa, and thrombin, as well as to determine total and functionally active C1-INH. We measured the concentration of the complexes in EDTA plasma from 6 healthy controls, from 5 with type I and 5 with type II C1-INH-HAE patients during symptom-free periods and from five patients during HAE attacks. We also assessed the concentration of these complexes in blood samples taken from one C1-INH-HAE patient during the kinetic follow-up of a HAE attack. The overall pattern of complexed C1-INH was similar in controls and C1-INH-HAE patients. C1-INH formed the highest concentration complexes with C1r and C1s. We observed higher plasma kallikrein/C1-INH complex concentration in both type I and type II C1-INH-HAE, and higher concentration of MASP-1/C1-INH, and MASP-2/C1-INH complexes in type II C1-INH-HAE patients compared to healthy controls and type I patients. Interestingly, none of the C1-INH complex concentrations changed significantly during HAE attacks. During the kinetic follow-up of an HAE attack, the concentration of plasma kallikrein/C1-INH complex was elevated at the onset of the attack. In parallel, C1r, FXIIa and FXIa complexes of C1-INH also tended to be elevated, and the changes in the concentrations of the complexes followed rather rapid kinetics. Our results suggest that the complement classical pathway plays a critical role in the metabolism of C1-INH, however, in C1-INH-HAE, contact system activation is the most significant in this respect. Due to the fast changes in the concentration of complexes, high resolution kinetic follow-up studies are needed to clarify the precise molecular background of C1-INH-HAE pathogenesis.
C1 抑制剂（C1-INH）是补体、凝血、纤溶和接触系统的重要调节剂。血液中蛋白酶/C1-INH 复合物的数量与这四个级联样血浆酶系统的激活水平成正比。平行测定 C1-INH 含有的激活复合物对于理解 C1-INH 在遗传性血管水肿（HAE）等疾病中的调节作用可能很重要，因为 C1-INH 缺乏（C1-INH-HAE）。我们开发了内部 ELISA 来测量与活性蛋白酶形成的 C1-INH 复合物的浓度：C1r、C1s、MASp-1、MASp-2、血浆激肽释放酶、因子 XIIa、因子 XIa 和凝血酶，以及测定总 C1-INH 和功能活性 C1-INH。我们测量了 6 名健康对照者、5 名 I 型和 5 名 II 型 C1-INH-HAE 患者无症状期及 5 名患者 HAE 发作期间 EDTA 血浆中复合物的浓度。我们还评估了一名 C1-INH-HAE 患者在 HAE 发作的动力学随访期间血液样本中这些复合物的浓度。在 C1-INH-HAE 患者和健康对照者中，复合 C1-INH 的总体模式相似。C1-INH 与 C1r 和 C1s 形成最高浓度的复合物。我们观察到 I 型和 II 型 C1-INH-HAE 患者的血浆激肽释放酶/C1-INH 复合物浓度较高，II 型 C1-INH-HAE 患者的 MASp-1/C1-INH 和 MASp-2/C1-INH 复合物浓度较高与健康对照者和 I 型患者相比。有趣的是，在 HAE 发作期间，C1-INH 复合物浓度没有明显变化。在 HAE 发作的动力学随访期间，在发作开始时，血浆激肽释放酶/C1-INH 复合物的浓度升高。同时，C1r、FXIIa 和 FXIa 复合物也趋于升高，复合物浓度的变化遵循快速动力学。我们的结果表明，补体经典途径在 C1-INH 的代谢中起着关键作用，但在 C1-INH-HAE 中，接触系统的激活在这方面最为重要。由于复合物浓度的快速变化，需要进行高分辨率动力学随访研究，以阐明 C1-INH-HAE 发病机制的确切分子背景。
