The role of endometrial gland in regulating trophoblast functions and its association with the pathogenesis of pre-eclampsia

Abstract

Successful placentation requires delicate communication between endometrium and trophoblasts. The invasion of trophoblasts into the endometrium and integration into the endothelial cells network during early pregnancy is crucial to placentation. Dysregulation of these functions is associated with various pregnancy complications such as miscarriage and pre-eclampsia. The endometrial microenvironment exerts important influences on trophoblast cell functions. The precise effect of decidual gland secretome on trophoblast functions remains uncertain.

S100 Calcium-Binding Protein A9 (S100A9, also known as Calgranulin B) is a calcium- and zinc-binding protein that regulates various cellular events in cancer such as proliferation, differentiation, and migration/invasion. AQPs are integral membrane proteins that facilitate the transport of water across biological membranes along an osmotic gradient and also involved in cell migration, proliferation and carcinogenesis in tumor development and physiologic inflammatory processes. As members of AQPs, Aquaporin-1 (AQP1) and Aquaporin-9 (AQP9) facilitate migration and invasion through matrix metalloproteinase MMP2 and MMP9. Endometrial organoids were treated with hormones mimicking the environment of the proliferative phase (Estrogen, E2), secretory phase (E2+ Progesterone, P4) and early pregnancy (E2+P4+Human Chorionic Gonadotropin, hCG). miRNA-seq were performed on the treated organoid. Organoid secretions were also collected for mass spectrometric analysis. The invasion/migration of the trophoblasts after the treatment with organoid secretome were determined by transwell assay. I demonstrated that sex steroid hormones modulate aquaporins (AQP)1/9 and S100A9 secretions through miR-3194 activation in endometrial epithelial cells, which in turn enhanced trophoblast migration and invasion during early pregnancy.

S100P is a 95-amino-acid protein and a member of the S100 family. It stimulates both cell motility and invasion in different trophoblastic and first trimester EVT cell lines and enhances angiogenesis in various human malignancies and highly correlated with the formation of microvascular invasion (MVI). APOD, a 25 to 30 kDa glycosylated protein, member of the lipocalin superfamily is associated with lipid metabolism. Decreased APOD results in increased migration of trophoblasts in the placenta accrete. It also suppresses PI3K-Akt-eNOS signaling pathway interfering angiogenesis. RNA-seq and miRNA-seq were performed on the pre-eclampsia and normotensive tissue and organoid. Organoid secretions were also collected for mass spectrometric analysis. I further investigated how the secretomes could potentially pose a directional response of angiogenesis by HUVECs tube formation and regulate integration by EVTs into HUVECs. I demonstrated for the first time that the APOD and S100P are key regulators of HUVECs tube formation, EVTs invasion and integration in the physiology and pathology of pre-eclampsia.

By using a human endometrial organoid model, we demonstrated for the first time that the endometrial gland secretome is crucial to regulate the functions of human trophoblasts in early pregnancy and pre-eclampsia.