Division of Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA; Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia.
Division of Rheumatology, Department of Medicine, McGill University, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
Clin Immunol. 2023 Oct;255:109714. doi: 10.1016/j.clim.2023.109714. Epub 2023 Jul 30.
Beta-2 glycoprotein I (βGPI) is a phospholipid-binding plasma protein and prominent autoantigen in antiphospholipid syndrome (APS). Here, we tested the hypothesis that βGPI might bind to not only phospholipids, but also cell-free DNA and neutrophil extracellular traps (NETs). We report that βGPI interacts with cell-free DNA from different species, as well as NETs, in a dose-dependent manner, retarding their migration in an agarose-gel electrophoretic mobility shift assay. We confirm the direct binding interaction of βGPI with DNA and NETs by ELISA. We also demonstrate that βGPI colocalizes with NET strands by immunofluorescence microscopy. Finally, we provide evidence that βGPI-DNA complexes can be detected in the plasma of APS patients, where they positively correlate with an established biomarker of NET remnants. Taken together, our findings indicate that βGPI interacts with DNA and NETs, and suggest that this interaction may play a role as a perpetuator and/or instigator of autoimmunity in APS.
β2-糖蛋白 I（βGPI）是一种与磷脂结合的血浆蛋白，也是抗磷脂综合征（APS）中的主要自身抗原。在这里，我们验证了βGPI 不仅可以与磷脂结合，还可以与无细胞游离 DNA 和中性粒细胞胞外诱捕网（NETs）结合的假说。我们发现，βGPI 以剂量依赖的方式与不同种属的无细胞游离 DNA 以及 NETs 相互作用，在琼脂糖凝胶电泳迁移率变动分析中阻碍其迁移。我们通过 ELISA 确认了 βGPI 与 DNA 和 NETs 的直接结合相互作用。我们还通过免疫荧光显微镜证明了βGPI 与 NET 链的共定位。最后，我们提供了证据表明βGPI-DNA 复合物可在 APS 患者的血浆中检测到，并且与公认的 NET 残余物的生物标志物呈正相关。总之，我们的研究结果表明βGPI 与 DNA 和 NETs 相互作用，并提示这种相互作用可能在 APS 中作为自身免疫的持续因素和/或引发因素发挥作用。
