Properdin Is a Key Player in Lysis of Red Blood Cells and Complement Activation on Endothelial Cells in Hemolytic Anemias Caused by Complement Dysregulation
Properdin Is a Key Player in Lysis of Red Blood Cells and Complement Activation on Endothelial Cells in Hemolytic Anemias Caused by Complement Dysregulation
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DOI：
10.3389/fimmu.2020.01460
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发表时间：
2020-07-22
影响因子：
7.3
通讯作者：
Ferreira, Viviana P.
中科院分区：
文献类型：
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作者：
Chen, Jin Y.;Galwankar, Neeti S.;Ferreira, Viviana P.
补体系统旁路途径（AP）可在炎症性疾病中过度激活，特别是当存在补体调节缺陷时。例如，补体调节因子CD55和CD59的缺乏导致阵发性睡眠性血红蛋白尿症（PNH），而因子H突变易患非典型溶血性尿毒综合征（aHUS），两者均引起严重的血栓溶血。尽管依库珠单抗是治疗这些疾病的药物，但患者之间的获益差异很大。了解补体调节的分子机制对于开发新的治疗方法至关重要。备解素，正AP调节剂，通过稳定酶促转化酶而对补体扩增至关重要。在这项研究中，备解素在红细胞（RBC）溶解和内皮细胞调理作用在这些AP介导的疾病中的作用是通过使用PNH患者RBC和人原代内皮细胞的体外试验来解决的，其中使用我们产生和表征的新型单克隆抗体（MoAb）抑制备解素的效果与其他补体抑制剂进行了比较。在PNH的体外模型中，备解素抑制比抑制因子B、C3和C5更能防止患者PNH II型和III型RBC的溶血（摩尔IC（90）值分别低> 17倍、或> 81倍、或> 12倍）。当在体外HUS溶血模型中测试时，抗备解素MoAb的摩尔IC（90）值分别比因子B或C3的抑制低11倍和86倍（P <0.0001）。当在所有溶血测定中比较靶/抑制剂比率时，在大多数情况下，抑制备解素至少与其他补体抑制剂一样有效。此外，使用体外内皮细胞测定，数据表明备解素在促进暴露于血红素（溶血副产物）和rH19 - 20（抑制因子H细胞表面保护）的人内皮细胞上的补体活化中具有关键的新作用，如在aHUS中发生的那样。抑制备解素或C3在该系统中显着减少C3片段沉积75%。总之，数据表明备解素在促进人内皮细胞上的RBC溶解和补体活化中是关键的，有助于理解PNH和aHUS发病机制。需要进一步研究以确定抑制备解素在补体介导的疾病中的治疗价值，特别是那些以AP失调为特征的疾病。
The complement system alternative pathway (AP) can be activated excessively in inflammatory diseases, particularly when there is defective complement regulation. For instance, deficiency in complement regulators CD55 and CD59, leads to paroxysmal nocturnal hemoglobinuria (PNH), whereas Factor H mutations predispose to atypical hemolytic uremic syndrome (aHUS), both causing severe thrombohemolysis. Despite eculizumab being the treatment for these diseases, benefits vary considerably among patients. Understanding the molecular mechanisms involved in complement regulation is essential for developing new treatments. Properdin, the positive AP regulator, is essential for complement amplification by stabilizing enzymatic convertases. In this study, the role of properdin in red blood cell (RBC) lysis and endothelial cell opsonization in these AP-mediated diseases was addressed by developingin vitroassays using PNH patient RBCs and human primary endothelial cells, where the effects of inhibiting properdin, using novel monoclonal antibodies (MoAbs) that we generated and characterized, were compared to other complement inhibitors. Inin vitromodels of PNH, properdin inhibition prevented hemolysis of patient PNH type II and III RBCs more than inhibition of Factor B, C3, and C5 (>17-fold, or >81-fold, or >12-fold lower molar IC(90)values, respectively). When tested in anin vitroaHUS hemolysis model, the anti-properdin MoAbs had 11-fold, and 86-fold lower molar IC(90)values than inhibition of Factor B, or C3, respectively (P< 0.0001). When comparing target/inhibitor ratios in all hemolysis assays, inhibiting properdin was at least as efficient as the other complement inhibitors in most cases. In addition, usingin vitroendothelial cell assays, the data indicate a critical novel role for properdin in promoting complement activation on human endothelial cells exposed to heme (a hemolysis by-product) and rH19-20 (to inhibit Factor H cell-surface protection), as occurs in aHUS. Inhibition of properdin or C3 in this system significantly reduced C3 fragment deposition by 75%. Altogether, the data indicate properdin is key in promoting RBC lysis and complement activation on human endothelial cells, contributing to the understanding of PNH and aHUS pathogenesis. Further studies to determine therapeutic values of inhibiting properdin in complement-mediated diseases, in particular those that are characterized by AP dysregulation, are warranted.