Cytotrophoblast extracellular vesicles enhance decidual cell secretion of immune modulators via TNF-alpha.

The placenta releases large quantities of extracellular vesicles (EVs) that likely facilitate communication between the embryo/fetus and the mother. We isolated EVs from second trimester human cytotrophoblasts (CTBs) by differential ultracentrifugation and characterized them by transmission electron microscopy, immunoblotting, and mass spectrometry. The 100,000 xg pellet was enriched for vesicles with a cup-like morphology typical of exosomes. They expressed markers specific to this vesicle type, CD9 and HRS, and the trophoblast proteins placental alkaline phosphatase and HLA-G. Global profiling by mass spectrometry showed that placental EVs were enriched for proteins that function in transport and viral processes. A cytokine array revealed that the CTB 100,000 xg pellet contained a significant amount of TNF-α. CTB EVs increased decidual stromal cell (dESF) transcription and secretion of NF-κB targets, including IL-8, as measured by qRT-PCR and cytokine array. A soluble form of the TNF-α receptor inhibited the ability of CTB 100,000 xg EVs to increase dESF secretion of IL-8. Overall, the data suggest that CTB EVs enhance decidual cell release of inflammatory cytokines, which we theorize is an important component of successful pregnancy.