Differential proteomics of circulating extracellular vesicles of placental origin isolated from women with early‐onset preeclampsia reveal aberrant innate immune and hemostasis processes

Abstract Problem Early‐onset preeclampsia (EOPE) is a severe gestational hypertensive disorder with significant feto‐maternal morbidity and mortality due to uteroplacental insufficiency. Circulating extracellular vesicles of placental origin (EV‐P) are known to be involved in the pathophysiology of EOPE and might serve as an ideal reservoir for its specific biomarkers. Therefore, we aimed to characterize and perform comparative proteomics of circulating EV‐P from healthy pregnant and EOPE women before delivery. Method of Study The EV‐P from both groups were isolated using immunoaffinity and were characterized using transmission electron microscopy, dynamic light scattering, nanoparticle tracking analysis, and immunoblotting. Following IgG albumin depletion, the pooled proteins that were isolated from EV‐P of both groups were subjected to quantitative TMT proteomics. Results Circulating term EV‐P isolated from both groups revealed ∼150 nm spherical vesicles containing CD9 and CD63 along with placental PLAP and HLA‐G proteins. Additionally, the concentration of EOPE‐derived EV‐P was significantly increased. A total of 208 proteins were identified, with 26 among them being differentially abundant in EV‐P of EOPE women. This study linked the pathophysiology of EOPE to 19 known and seven novel proteins associated with innate immune responses such as complement and TLR signaling along with hemostasis and oxygen homeostasis. Conclusion The theory suggesting circulating EVs of placental origin could mimic molecular information from the parent organ—“the placenta”—is strengthened by this study. The findings pave the way for possible discovery of novel prognostic and predictive biomarkers as well as provide insight into the mechanisms driving the pathogenesis of EOPE.