Abstract
Antiphospholipid antibody (aPL)‑mediated antiphospholipid syndrome (APS) is an autoimmune disease. Upon binding to aPL, the primary antigen of aPL, β2‑glycoprotein I (β2‑GP I), induces abnormal immune function, which further activates downstream signaling pathways in the cell and eventually leads to APS. The present study aimed to determine whether β2‑GP I antigen and anti‑β2‑glycoprotein I antibody (aβ2‑GP I), which belong to the aPL class of antibodies, may affect human chorionic epithelium cell (JEG‑3) proliferation, migration and invasion. Recombinant human (rh)β2‑GP I protein was expressed using a prokaryotic expression system and aβ2‑GP I antibody was purified from the blood serum of 10 patients with recurrent pregnancy loss. JEG‑3 cells were stimulated with rhβ2‑GP I and aβ2‑GP I separately or simultaneously, and serum immunoglobulin G of normal pregnant women was used as negative control. Using cell counting kit‑8, cell cycle and transwell assays in addition to EdU staining, it was determined that aβ2‑GP I/rhβ2‑GP I complex markedly increased JEG‑3 cell proliferation, migration and invasion. The results revealed that mRNA levels of inhibitor of nuclear factor (NF)‑κB kinase subunit (IKKβ), myeloid differentiation primary response protein MyD88 (MyD88), NF‑κB and NF‑κB inhibitor α (IκBα), as well as the protein levels of MyD88, IκBα and phospho(p)‑IκBα in JEG‑3 cells increased following incubation with the aβ2‑GP I/rhβ2‑GP I complex. The observed upregulation of p‑IκBα protein suggested that IκBα‑mediated inhibition of NF‑κB was weakened. Furthermore, JEG‑3 cells were transfected with PGMLV‑NF‑κB‑Lu vector. Luciferase activity in JEG‑3‑NFκB‑Luc1 and JEG‑3‑NFκB‑Luc2 cells was enhanced following treatment with aβ2‑GP I/rhβ2‑GP I complex. The present study demonstrated that aβ2‑GP I/rhβ2‑GP I complex activates NF‑κB through MyD88 signal transduction pathway, which further enhances JEG‑3 cell proliferation, migration and invasion.