Immune-mediated mechanisms and maternal-fetal interface dysfunction in obstetric antiphospholipid syndrome

Obstetric antiphospholipid syndrome (OAPS) is a complex autoimmune disorder that significantly compromises pregnancy, manifesting as recurrent miscarriage, stillbirth, placental insufficiency, and preeclampsia. Its increasing prevalence underscores the pressing need to elucidate its multifaceted pathogenic mechanisms to improve maternal and fetal outcomes. While traditionally attributed to thrombosis driven by antiphospholipid antibodies (aPL), emerging evidence indicates that OAPS can disrupt placental perfusion, impair trophoblast proliferation and invasion, and compromise placental angiogenesis even in the absence of overt thrombotic events. Beyond direct effects on trophoblasts and vascular remodeling, aPLs profoundly perturb the immune milieu at the maternal–fetal interface, encompassing complement activation, excessive formation of neutrophil extracellular traps (NETs), dysfunction of decidual natural killer cells and macrophages, and dysregulated B cell responses. These immune-mediated alterations collectively establish a sustained pro-inflammatory environment that undermines placental development and predisposes to adverse pregnancy outcomes. This review provides a comprehensive synthesis of the immunopathogenic mechanisms of OAPS that extend beyond thrombosis, and emphasizes the intricate crosstalk between immune cells and the complement-NET axis. A deeper understanding of these immune-mediated pathways may inform the development of targeted therapeutic strategies to optimize maternal and fetal outcomes in affected pregnancies.