OP 57 Procoagulant extracellular vesicles impair trophoblast function by a thrombo-inflammatory pathway in preeclampsia

Abstract

Introduction Procoagulant extracellular vesicles (EV) and platelet activation have been associated with pregnancy complications. We have recently identified that EV cause preeclampsia by platelet mediated placental inflammasome activation. Whether this thrombo-inflammatory pathway alters trophoblast differentiation and function remains unknown. Objectives To identify whether the EV induced thrombo-inflammatory pathway modulates trophoblast proliferation, differentiation, and invasion in PE. Materials and methods We injected C57BL/6 mice with endothelial or platelet-derived EVs to study the role of EVs in vivo . Blood pressure, kidney histology (PAS staining and EM), proteinuria, sFlt-1 were assessed to evaluate PE. We exposed human and mouse trophoblast cells to EV and platelets to study their role in vitro . Trophoblast proliferation and cell death was studied using Ki-67 immunostaining, BrdU incorporation and TUNEL staining. RT-PCR for marker genes (PL-II, Tpbpa, Gcm1) was done to study trophoblast differentiation. Matrigel based tube formation assays were used to assess trophoblast invasion. Translational relevance was studied in human PE placenta. Results EV injection into pregnant mice results in platelet activation and PE and activated platelets accumulate in the placenta. EV treatment enhanced cell death and impaired trophoblast differentiation and proliferation both in vitro and in vivo . EV treatment resulted in impaired trophoblast tube formation indicating impaired trophoblast invasion. Platelet depletion and genetic (NFE2−/−, G α q−/−) or pharmaceutical (Apyrase, Aspirin) platelet inhibition abolished these effects. Furthermore, EV induced inflammasome activation in trophoblast cells, and NLRP3 or Casp-1 deficiency or IL-1 receptor antagonist (Anakinra) abolished the effects of EV. Inflammasome activation, platelet activation and cell death were positively correlated in human PE placenta. Conclusion These results demonstrate that EV mediated platelet activation impairs trophoblast function by reducing trophoblast proliferation, differentiation and invasion by platelet mediated inflammasome activation. These results support the pathophy.