Effect and mechanism of the aβ2-GP I/rhβ2-GP I complex on JEG-3 cell proliferation, migration and invasion

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.