Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Department of Immunopathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Clin Exp Immunol. 2019 Feb;195(2):167-178. doi: 10.1111/cei.13229. Epub 2018 Nov 28.
Autoantibodies characteristic for anti-phospholipid syndrome (APS) and systemic lupus erythematosus (SLE) are anti-β -glycoprotein I (β GPI) antibodies and anti-DNA antibodies, respectively, and almost half of APS cases occur in SLE. Anti-β GPI antibodies are recognized to play a pivotal role in inducing a prothrombotic state, but the precise mechanism has not been fully elucidated. In a widely accepted view, binding of anti-β GPI antibodies to cell surface β GPI in monocytes and endothelial cells triggers the Toll-like receptor 4-myeloid differentiation primary response 88 (TLR)-4-MyD88) signaling pathway which leads to activation of p38 mitogen-activated protein kinase (MAPK), mitogen-activated protein kinase kinase 1/extracellular signal-regulated kinases (MEK-1/ERK) and/or nuclear factor kappa B (NF-κB) and expression of tissue factor (TF). However, resting cells do not express substantial amounts of TLR-4. Previously, we generated a mouse monoclonal anti-β GPI antibody WB-6 and showed that it induced a prothrombotic state - including TF expression on circulating monocytes - in normal mice. In the current study, we aimed to clarify the mechanism of interaction between WB-6 and resting monocytes, and found that WB-6 exhibits binding activity to DNA and enters living monocytes or a monocytic cell line and, to a lesser extent, vascular endothelial cells. Treatment of the cells with DNase I reduced the internalization, suggesting the involvement of cell surface DNA in this phenomenon. Monocytes harboring internalized WB-6 expressed TF and tumor necrosis factor (TNF)-α which, in turn, stimulated endothelial cells to express intercellular adhesion molecule 1 (ICAM-I) and vascular cell adhesion molecule 1 (VCAM-I). These results suggest the possibility that a subset of anti-β GPI antibodies with dual reactivity to DNA possesses ability to stimulate DNA sensors in the cytoplasm, in addition to the cell surface receptor-mediated pathways, leading to produce proinflammatory and prothrombotic states.
抗磷脂综合征（APS）和系统性红斑狼疮（SLE）的特征性自身抗体分别为抗β-糖蛋白 I（β GPI）抗体和抗 DNA 抗体，几乎一半的 APS 病例发生在 SLE 中。抗β GPI 抗体被认为在诱导血栓前状态中起关键作用，但确切的机制尚未完全阐明。在一种被广泛接受的观点中，抗β GPI 抗体与单核细胞和内皮细胞表面的β GPI 结合，触发 Toll 样受体 4-髓样分化初级反应 88（TLR）-4-髓样分化因子 88（MyD88）信号通路，导致 p38 丝裂原活化蛋白激酶（MAPK）、丝裂原活化蛋白激酶激酶 1/细胞外信号调节激酶（MEK-1/ERK）和/或核因子 kappa B（NF-κB）的激活以及组织因子（TF）的表达。然而，静止细胞不表达大量的 TLR-4。此前，我们生成了一种小鼠单克隆抗β GPI 抗体 WB-6，并表明它在正常小鼠中诱导了一种血栓前状态，包括循环单核细胞上 TF 的表达。在本研究中，我们旨在阐明 WB-6 与静止单核细胞相互作用的机制，发现 WB-6 表现出与 DNA 的结合活性，并进入活的单核细胞或单核细胞系，并且在较小程度上进入血管内皮细胞。用 DNA 酶 I 处理细胞可减少内化，表明细胞表面 DNA 参与了这一现象。含有内化 WB-6 的单核细胞表达 TF 和肿瘤坏死因子（TNF）-α，进而刺激内皮细胞表达细胞间黏附分子 1（ICAM-1）和血管细胞黏附分子 1（VCAM-1）。这些结果表明，具有双重反应性的抗β GPI 抗体亚类除了细胞表面受体介导的途径外，还具有刺激细胞质中 DNA 传感器的能力，导致产生促炎和血栓前状态。
