Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Mainz, Mainz, Germany.
Center for Thrombosis and Hemostasis, University Medical Center Mainz, Mainz, Germany.
J Thromb Haemost. 2017 Dec;15(12):2367-2376. doi: 10.1111/jth.13865. Epub 2017 Nov 1.
Essentials Antiphospholipid antibodies (aPL) are heterogeneous and induce different cellular responses. We analyzed signaling events induced by different monoclonal and patient aPL in monocytes. Two major signaling pathways involving either NADPH-oxidase or LRP8 were identified. Our data suggest that these two pathways mediate the majority of aPL effects on monocytes.
Background Antiphospholipid antibodies (aPLs) contribute to the pathogenesis of the antiphospholipid syndrome (APS) by induction of an inflammatory and procoagulant state in different cell types, and several signaling pathways have been described. Objectives To investigate whether signaling depends on the epitope specificity of aPLs. Methods Cellular effects of three human monoclonal aPLs with distinctly different epitope specificities were analyzed in vitro. Expression of tumor necrosis factor-α mRNA by mouse and human monocytes was the major readout. Analysis included cells from genetically modified mice, and the use of specific inhibitors in human monocytes. Data were validated with IgG isolated from 20 APS patients. Results Cofactor-independent anticardiolipin aPLs activated monocytes by induction of endosomal NADPH oxidase. Activation could be blocked by hydroxychloroquine (HCQ). Anti-β -glycoprotein I aPL activated monocytes by interacting with LDL receptor-related protein 8 (LRP8). This could be blocked by rapamycin. Analysis of 20 APS patients' IgG showed that all IgG fractions activated the same two pathways as the monoclonal aPL, depending on their epitope patterns as determined by ELISA. Monocyte activation by APS IgG could be blocked completely by HCQ and/or rapamycin, suggesting that in most, if not all, APS patients there is no other relevant signaling pathway. Conclusions aPLs activate two major proinflammatory signal transduction pathways, depending on their epitope specificity. HCQ and rapamycin, either alone or in combination, completely suppress signaling by APS IgG. These observations may provide a rationale for specific treatment of APS patients according to their aPL profile.
抗磷脂抗体（aPL）通过在不同细胞类型中诱导炎症和促凝状态，促进抗磷脂综合征（APS）的发病机制，并且已经描述了几种信号通路。
研究信号转导是否依赖于 aPL 的表位特异性。
在体外分析三种具有明显不同表位特异性的人源单克隆 aPL 的细胞作用。以小鼠和人单核细胞的肿瘤坏死因子-α mRNA 的表达为主要检测指标。分析包括来自基因修饰小鼠的细胞，以及在人单核细胞中使用特定抑制剂。使用从 20 名 APS 患者中分离的 IgG 对数据进行了验证。
无共因子依赖性抗心磷脂 aPL 通过诱导内体 NADPH 氧化酶激活单核细胞。该激活可以被羟氯喹（HCQ）阻断。抗β-糖蛋白 I aPL 通过与 LDL 受体相关蛋白 8（LRP8）相互作用激活单核细胞。这可以被雷帕霉素阻断。对 20 名 APS 患者 IgG 的分析表明，所有 IgG 片段都根据 ELISA 确定的表位模式激活了与单克隆 aPL 相同的两种途径。APS IgG 对单核细胞的激活可以被 HCQ 和/或雷帕霉素完全阻断，这表明在大多数（如果不是全部）APS 患者中，不存在其他相关的信号通路。
aPL 根据其表位特异性激活两种主要的促炎信号转导途径。HCQ 和雷帕霉素单独或联合使用可完全抑制 APS IgG 的信号转导。这些观察结果可能为根据 aPL 谱对 APS 患者进行特异性治疗提供依据。
