Hyperglycemia-induced endothelial exosomes trigger trophoblast dysregulation and abnormal placentation through PUM2-mediated repression of SOX2.

Background: Hyperglycemia is closely related to adverse pregnancy outcomes including pre-eclampsia (PE), a life-threatening complication with a substantial morbidity and mortality. However, the pathogenesis of abnormal placentation in gestational diabetes mellitus (GDM)-associated PE remains elusive.

Method: Here we isolated exosomes from the human umbilical vein endothelial cells (HUVECs) treated with normal level of glucose (NG) and high levels of glucose (HG). The exosomes were added to HTR-8a/SVneo cells, a trophoblast cell line. High-throughput RNA-sequencing was performed to analyzed the changed RNAs in the exosomes and exosome-treated HTR-8a/SVneo cells. HTR-8a/SVneo cell phenotypes were evaluated from the aspects of cell proliferation, cell invasion and DNA damage.

Results: After treatment with HG, the changed RNAs in exosomes was enriched in RNA stabilization and oxidative stress. The altered RNAs in the HTR-8a/SVneo cells treated with exosomes from HG-induced HUVECs were enriched in pathways related to cell adhesion, migration, DNA damage response and angiogenesis. The HG-induced exosomes impaired the proliferation and invasion of HTR-8a cells and caused the DNA damage. HG up-regulated PUM2 in the exosomes and exosome-treated HTR-8a/SVneo cells. PUM2 interacted with SOX2 mRNA, resulting in the mRNA degradation. Overexpression of SOX2 prevented the damage to HTR-8a/SVneo cells caused by the exosomes from HG-induced HUVECs.

Conclusions: We demonstrate that high glucose-induced endothelial exosomes mediate abnormal phenotypes of trophoblasts through PUM2-mediated repression of SOX2. Our results reveal a novel regulatory mechanism of hyperglycemia in development of abnormal placentation and provide potential targets for preventing adverse pregnancy outcomes.