Raschi Elena, Testoni Cinzia, Bosisio Daniela, Borghi Maria O, Koike Takao, Mantovani Alberto, Meroni Pier Luigi
Istituto di Ricovero e Aura a Carattere Scientifico Istituto Auxologico Italiano, Allergy and Clinical Immunology Unit, Department of Internal Medicine, University of Milan, Italy.
Blood. 2003 May 1;101(9):3495-500. doi: 10.1182/blood-2002-08-2349. Epub 2003 Jan 16.
Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the persistent presence of antiphospholipid antibodies (aPLs) and recurrent thrombosis or fetal loss. The thrombophilic state has been partially related to the induction of a proinflammatory and procoagulant endothelial cell (EC) phenotype induced by anti-beta(2)-glycoprotein I (beta(2)-GPI) antibodies that bind beta(2)-GPI expressed on the EC surface. Anti-beta(2)-GPI antibody binding has been shown to induce nuclear factor-kappa B (NF-kappa B) translocation leading to a proinflammatory EC phenotype similar to that elicited by interaction with microbial products (lipopolysaccharide [LPS]) and proinflammatory cytokines (interleukin 1 beta [IL-1 beta], tumor necrosis factor alpha [TNF-alpha]). However, the upstream signaling events are not characterized yet. To investigate the endothelial signaling cascade activated by anti-beta(2)-GPI antibodies, we transiently cotransfected immortalized human microvascular endothelial cells (HMEC-1) with dominant-negative constructs of different components of the pathway (Delta TRAF2, Delta TRAF6, Delta MyD88) together with reporter genes (NF-kappa B luciferase and pCMV-beta-galactosidase). Results showed that both human anti-beta(2)-GPI IgM monoclonal antibodies as well as polyclonal affinity-purified anti-beta(2)-GPI IgG display a signaling cascade comparable to that activated by LPS or IL-1. Delta TRAF6 and Delta MyD88 significantly abrogate antibody-induced as well as IL-1- or LPS-induced NF-kappa B activation, whereas Delta TRAF2 (involved in NF-kappa B activation by TNF) does not affect it. Moreover, anti- beta(2)-GPI antibodies and LPS followed the same time kinetic of IL-1 receptor-activated kinase (IRAK) phosphorylation, suggesting an involvement of the toll-like receptor (TLR) family. Our findings demonstrate that anti-beta(2)-GPI antibodies react with their antigen likely associated to a member of the TLR/IL-1 receptor family on the EC surface and directly induce activation.
抗磷脂综合征（APS）是一种自身免疫性疾病，其特征为抗磷脂抗体（aPLs）持续存在以及反复发生血栓形成或胎儿丢失。这种血栓形成倾向部分与抗β2糖蛋白I（β2-GPI）抗体诱导的促炎和促凝内皮细胞（EC）表型有关，该抗体可结合内皮细胞表面表达的β2-GPI。已表明抗β2-GPI抗体结合可诱导核因子-κB（NF-κB）易位，导致促炎内皮细胞表型，类似于与微生物产物（脂多糖[LPS]）和促炎细胞因子（白细胞介素1β[IL-1β]、肿瘤坏死因子α[TNF-α]）相互作用所引发的表型。然而，上游信号事件尚未明确。为了研究抗β2-GPI抗体激活的内皮信号级联反应，我们将永生化人微血管内皮细胞（HMEC-1）与该信号通路不同组分的显性负性构建体（ΔTRAF2、ΔTRAF6、ΔMyD88）以及报告基因（NF-κB荧光素酶和pCMV-β-半乳糖苷酶）进行瞬时共转染。结果显示，人抗β2-GPI IgM单克隆抗体以及多克隆亲和纯化的抗β2-GPI IgG均显示出与LPS或IL-1激活的信号级联反应相当。ΔTRAF6和ΔMyD88显著消除抗体诱导的以及IL-1或LPS诱导的NF-κB激活，而参与TNF诱导的NF-κB激活的ΔTRAF2则不影响该激活。此外，抗β2-GPI抗体和LPS遵循与IL-1受体激活激酶（IRAK）磷酸化相同的时间动力学，提示Toll样受体（TLR）家族参与其中。我们的研究结果表明，抗β2-GPI抗体与其抗原反应，该抗原可能与内皮细胞表面TLR/IL-1受体家族的一个成员相关，并直接诱导激活。
