MAX deficiency impairs human endometrial decidualization through down-regulating OSR2 in women with recurrent spontaneous abortion

Affinity-tagged SMAD1 and SMAD5 mouse lines reveal transcriptional reprogramming mechanisms during early pregnancy

Endometrial decidualization, a prerequisite for successful pregnancies, relies on transcriptional reprogramming driven by progesterone receptor (PR) and bone morphogenetic protein (BMP)-SMAD1/SMAD5 signaling pathways. Despite their critical roles in early pregnancy, how these pathways intersect in reprogramming the endometrium into a receptive state remains unclear. To define how SMAD1 and/or SMAD5 integrate BMP signaling in the uterus during early pregnancy, we generated two novel transgenic mouse lines with affinity tags inserted into the endogenous SMAD1 and SMAD5 loci (Smad1HA/HA and Smad5PA/PA). By profiling the genome-wide distribution of SMAD1, SMAD5, and PR in the mouse uterus, we demonstrated the unique and shared roles of SMAD1 and SMAD5 during the window of implantation. We also showed the presence of a conserved SMAD1, SMAD5, and PR genomic binding signature in the uterus during early pregnancy. To functionally characterize the translational aspects of our findings, we demonstrated that SMAD1/5 knockdown in human endometrial stromal cells suppressed expressions of canonical decidual markers (IGFBP1, PRL, FOXO1) and PR-responsive genes (RORB, KLF15). Here, our studies provide novel tools to study BMP signaling pathways and highlight the fundamental roles of SMAD1/5 in mediating both BMP signaling pathways and the transcriptional response to progesterone (P4) during early pregnancy.

Affinity-tagged SMAD1 and SMAD5 mouse lines reveal transcriptional reprogramming mechanisms during early pregnancy

Endometrial decidualization, a prerequisite for successful pregnancies, relies on transcriptional reprogramming driven by progesterone receptor (PR) and bone morphogenetic protein (BMP)-SMAD1/SMAD5 signaling pathways. Despite their critical roles in early pregnancy, how these pathways intersect in reprogramming the endometrium into a receptive state remains unclear. To define how SMAD1 and/or SMAD5 integrate BMP signaling in the uterus during early pregnancy, we generated two novel transgenic mouse lines with affinity tags inserted into the endogenous SMAD1 and SMAD5 loci (Smad1HA/HA and Smad5PA/PA). By profiling the genome-wide distribution of SMAD1, SMAD5, and PR in the mouse uterus, we demonstrated the unique and shared roles of SMAD1 and SMAD5 during the window of implantation. We also showed the presence of a conserved SMAD1, SMAD5, and PR genomic binding signature in the uterus during early pregnancy. To functionally characterize the translational aspects of our findings, we demonstrated that SMAD1/5 knockdown in human endometrial stromal cells suppressed expressions of canonical decidual markers (IGFBP1, PRL, FOXO1) and PR-responsive genes (RORB, KLF15). Here, our studies provide novel tools to study BMP signaling pathways and highlight the fundamental roles of SMAD1/5 in mediating both BMP signaling pathways and the transcriptional response to progesterone (P4) during early pregnancy.

USP7 promotes decidualization of ESCs by STAT3/PR axis during early pregnancy

Decidualization is an essential process for embryo implantation during early pregnancy. Defective decidualization is a critical leading cause of early pregnancy loss (EPL). Ubiquitin-specific protease 7 (USP7) is a deubiquitinating enzyme that is involved in uterine function. This study aimed to explore the underlying mechanism by which USP7 regulates decidualization in EPL. We found that USP7 was downregulated in the decidual tissue of EPL patients. Upregulation of USP7 enhanced decidualization in endometrial stromal cells (ESCs), with increased decidualized biomarkers IGFBP1 and PRL and progesterone receptor A/B (PR-A/B) expression. Moreover, we found that signal transducer and activator of transcription 3 (STAT3) is a direct target of USP7 in ESCs. USP7 bound to STAT3 by deubiquitination and increased STAT3 levels in ESCs. Suppression of STAT3 impeded the USP7-promoted cell viability, decidualization, and PR-A/B expression of ESCs. USP7 promoted the decidualization of ESCs through the STAT3/PR signaling pathway during early pregnancy, which provides new insight into the pathological mechanism of EPL and may contribute to the clinical treatment of EPL.

Icaritin attenuates recurrent spontaneous abortion in mice by modulating Treg/Th17 imbalance via TGF-β/SMAD signaling pathway

Recurrent spontaneous abortion (RSA) is a challenging global issue. Although the cause is unknown, increasing evidence suggests that immunological factors play a crucial role in RSA development. Icaritin (ICT), a natural compound derived from Epimedium, has demonstrated diverse biological activities, including anti-inflammatory, anti-cancer, and immunomodulatory effects. In this study, we aimed to investigate the potential therapeutic role of ICT in mitigating RSA in a mouse model. Specifically, we sought to determine whether ICT could modulate the Treg/Th17 cell imbalance via the TGF-β/SMAD signaling pathway and contributed to improved pregnancy outcomes. We conducted experiments on a mouse model with RSA and administered ICT orally. We then examined the effects of ICT on various types of immune cells including Treg and Th17 cells, and assessed the pregnancy outcomes. We also investigated the potential signaling pathway ICT exerted its effects. Our findings revealed that treatment with ICT led to an increase in Treg cells and a decrease in Th17 cells, which restored immune homeostasis and contributed to improved pregnancy outcomes. Furthermore, our data demonstrated that ICT's effects were mediated through the activation of TGF-β/SMAD signaling components. In conclusion, our study suggested that ICT ameliorated RSA by modulating Treg/Th17 cell imbalance via the TGF-β/SMAD signaling pathway. GENERAL SIGNIFICANCE: Our results highlighted the potential of ICT as a novel therapeutic agent for RSA, offering new insights into the underlying mechanisms and opening avenues for future research and clinical translation.

ATOH8 Expression Is Regulated by BMP2 and Plays a Key Role in Human Endometrial Stromal Cell Decidualization

During the secretory phase of the menstrual cycle, elongated fibroblast-like mesenchymal cells in the uterine endometrium begin to transdifferentiate into polygonal epithelioid-like (decidual) cells. This decidualization process continues more broadly during early pregnancy, and the resulting decidual tissue supports successful embryo implantation and placental development. This study was carried out to determine if atonal basic helix-loop-helix transcription factor 8 (ATOH8) plays a role in human endometrial stromal fibroblast (ESF) decidualization. ATOH8 messenger RNA and protein expression levels significantly increased in human ESF cells undergoing in vitro decidualization, with the protein primarily localized to the nucleus. When ATOH8 expression was silenced, the ability of the cells to undergo decidualization was significantly diminished. Overexpression of ATOH8 enhanced the expression of many decidualization markers. Silencing the expression of ATOH8 reduced the expression of FZD4, FOXO1, and several known FOXO1-downstream targets during human ESF cell decidualization. Therefore, ATOH8 may be a major upstream regulator of the WNT/FZD-FOXO1 pathway, previously shown to be critical for human endometrial decidualization. Finally, we explored possible regulators of ATOH8 expression during human ESF decidualization. BMP2 significantly enhanced ATOH8 expression when cells were stimulated to undergo decidualization, while an ALK2/3 inhibitor reduced ATOH8 expression. Finally, although the steroids progesterone plus estradiol did not affect ATOH8 expression, the addition of cyclic adenosine monophosphate (cAMP) analogue alone represented the major effect of ATOH8 expression when cells were stimulated to undergo decidualization. Our results suggest that ATOH8 plays a crucial role in human ESF decidualization and that BMP2 plus cAMP are major regulators of ATOH8 expression.

Expression of the odd-2 Gene in C. elegans

The odd-2 gene in C. elegans is an orthologue of the odd-skipped gene in Drosophila and the odd-skipped related genes in mammals. The mammalian genes have been shown to be expressed in a variety of tissues and cancers. It was previously reported that ODD-2 is expressed in the intestine and shows some expression outside of the intestine in the tail region. Using a partial ODD-2 ::GFP fusion, we hypothesize that the expression outside of the intestine may be in rectal gland cells, and we also report that ODD-2 may be expressed in the germline sheath cells.

Role of kisspeptin in decidualization and unexplained recurrent spontaneous abortion via the ERK1/2 signalling pathway

INTRODUCTION

This study aimed to study the expression and function of kisspeptin during human uterine decidualization in recurrent spontaneous abortion (RSA) and the underlying mechanism.

METHODS

All patients were recruited from the Clinical Reproductive Center of the Second Affiliated Hospital of Soochow University. Mice models of RSA (CBA/J × DBA/2) and normal pregnancy (CBA/J × BALB/c) were established, respectively. Kisspeptin expression in the serum and decidual tissues of women with RSA were detected. The function of kisspeptin during decidualization in human endometrial stromal cells (HESCs) was assessed by enhancing and silencing kisspeptin expression. CBA/J × DBA/2 pregnant mice were injected with kisspeptin polypeptide, kisspeptin receptor blocker, and expression of decidualization markers was observed. The regulation of ERK1/2 signalling pathway were verified.

RESULTS

Serum kisspeptin levels were significantly lower in patients with RSA than in normal pregnant individuals, as was the expression of kisspeptin, p-ERK, and decidualization indicators in the decidua. Additionally, kisspeptin inhibition downregulated the expression of decidualization markers in HESCs. In mice with RSA, kisspeptin was significantly downregulated, and p-ERK expression at the maternal-foetal interface was significantly decreased. Moreover, exogenous kisspeptin supplementation improved the levels of IGFBP-1 and dPRL, upregulated p-ERK expression, and reduced the abortion rate.

DISCUSSION

Kisspeptin is involved in promoting uterine decidualization via the ERK1/2 signalling pathway.

Single-Cell Immunobiology of the Maternal-Fetal Interface

Pregnancy success requires constant dialogue between the mother and developing conceptus. Such crosstalk is facilitated through complex interactions between maternal and fetal cells at distinct tissue sites, collectively termed the "maternal-fetal interface." The emergence of single-cell technologies has enabled a deeper understanding of the unique processes taking place at the maternal-fetal interface as well as the discovery of novel pathways and immune and nonimmune cell types. Single-cell approaches have also been applied to decipher the cellular dynamics throughout pregnancy, in parturition, and in obstetrical syndromes such as recurrent spontaneous abortion, preeclampsia, and preterm labor. Furthermore, single-cell technologies have been used during the recent COVID-19 pandemic to evaluate placental viral cell entry and the impact of SARS-CoV-2 infection on maternal and fetal immunity. In this brief review, we summarize the current knowledge of cellular immunobiology in pregnancy and its complications that has been generated through single-cell investigations of the maternal-fetal interface.