Preimplantation factor modulates trophoblastic invasion throughout the decidualization of human endometrial stromal cells

Esther Dos Santos,Lucie Arnould,Valérie Sérazin,Hadia Moindjie,Eytan R Barnea,Yoann Rodriguez,Marie-Noëlle Dieudonné,Khadija Fathallah,François Vialard

doi:10.1186/s12958-021-00774-5

Abstract

BackgroundSuccessful human embryo implantation requires the differentiation of endometrial stromal cells (ESCs) into decidual cells during a process called decidualization. ESCs express specific markers of decidualization, including prolactin, insulin-like growth factor-binding protein-1 (IGFBP-1), and connexin-43. Decidual cells also control of trophoblast invasion by secreting various factors, such as matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases. Preimplantation factor (PIF) is a recently identified, embryo-derived peptide with activities at the fetal-maternal interface. It creates a favorable pro-inflammatory environment in human endometrium and directly controls placental development by increasing the human trophoblastic cells’ ability to invade the endometrium. We hypothesized that PIF’s effects on the endometrium counteract its pro-invasive effects.MethodsWe tested sPIF effect on the expression of three decidualization markers by RT-qPCR and/or immunochemiluminescence assay. We examined sPIF effect on human ESC migration by performing an in vitro wound healing assay. We analyzed sPIF effect on endometrial control of human trophoblast invasion by performing a zymography and an invasion assay.ResultsFirstly, we found that a synthetic analog of PIF (sPIF) significantly upregulates the mRNA expression of IGFBP-1 and connexin-43, and prolactin secretion in ESCs - suggesting a pro-differentiation effect. Secondly, we showed that the HTR-8/SVneo trophoblastic cell line’s invasive ability was low in the presence of conditioned media from ESCs cultured with sPIF. Thirdly, this PIF’s anti-invasive action was associated with a specifically decrease in MMP-9 activity.ConclusionTaken as a whole, our results suggest that PIF accentuates the decidualization process and the production of endometrial factors that limit trophoblast invasion. By controlling both trophoblast and endometrial cells, PIF therefore appears to be a pivotal player in the human embryo implantation process.

Highlights

Successful human embryo implantation requires the differentiation of endometrial stromal cells (ESCs) into decidual cells during a process called decidualization
After having validated our in vitro differentiation protocol (Fig. 1A-C), we studied synthetic analog of PIF (sPIF)’s effect on this process
Effect of sPIF on mRNA expression of endometrial Tissue inhibitor of metalloproteinases (TIMP) Lastly, we focused on the mRNA expression of the invasion inhibitors TIMP-1 and TIMP-2, both of which are strongly expressed in human endometrium

Summary

Introduction

Successful human embryo implantation requires the differentiation of endometrial stromal cells (ESCs) into decidual cells during a process called decidualization. Decidualization occurs in response to the ovarian hormones 17β-estradiol (E2) and progesterone (P4) It is accompanied by the secretion of prolactin and insulin-like growth factorbinding protein-1 (IGFBP-1), and the expression of the gap junction connexin-43 (CX-43) in human ESCs [8, 9]. Decidual ECM remodeling events have been observed These processes are associated with MMP-2,-9 secretion and the modulation of TIMP-1,-2 gene expression in human ESCs [10,11,12]. This type of ECM remodeling enhances ESC motility and facilitates trophoblastic infiltration into the endometrial stroma [13]. The mechanisms underlying decidualization and decidual ECM remodeling are complex and have not yet been clearly elucidated

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