Human Decidualization Research Articles

YAP1 and WWTR1 are required for murine pregnancy initiation.

Endometrial stromal cell decidualization is required for pregnancy success. Although this process is integral to fertility, many of the intricate molecular mechanisms contributing to decidualization remain undefined. One pathway that has been implicated in endometrial stromal cell decidualization in humans in vitro, is the Hippo signaling pathway. Two previously conducted studies showed that the effectors of the Hippo signaling pathway, YAP1 and WWTR1, are required for decidualization of primary endometrial stromal cells in vitro. To investigate the in vivo role of YAP1 and WWTR1 in decidualization and pregnancy initiation, we generated Progesterone receptor Cre mediated mutation of a combination of Yap1 and Wwtr1 alleles. Female Yap1 and Wwtr1 triple allele mutants exhibited subfertility, a compromised decidualization response, decreased endometrial receptivity, delayed embryonic development, and a unique transcriptional profile at 7.5 days post coitus. Bulk mRNA sequencing revealed aberrant maternal remodeling evidenced by significant alterations in extracellular matrix encoding genes at 7.5 days post-coitus in mutant dams and enrichment for terms associated with fertility-compromising diseases like pre-eclampsia and endometriosis. In addition, differentially expressed genes overlapped directionally with Estrogen receptor and Epidermal growth factor receptor regulated genes as identified by microarray. Our results indicate that Yap1 and Wwtr1 are necessary for successful mammalian pregnancy initiation.

Metabolic reprogramming and heterogeneity during the decidualization process of endometrial stromal cells

The human endometrial decidualization is a transformative event in the pregnant uterus that involves the differentiation of stromal cells into decidual cells. While crucial to the establishment of a successful pregnancy, the metabolic characteristics of decidual cells in vivo remain largely unexplored. Here, we integrated the single-cell RNA sequencing (scRNA-seq) datasets on the endometrium of the menstrual cycle and the maternal-fetal interface in the first trimester to comprehensively decrypt the metabolic characteristics of stromal fibroblast cells. Our results revealed that the differentiation of stromal cells into decidual cells is accompanied by increased amino acid and sphingolipid metabolism. Furthermore, metabolic heterogeneity exists in decidual cells with differentiation maturity disparities. Decidual cells with high metabolism exhibit higher cellular activity and show a strong propensity for signaling. In addition, significant metabolic reprogramming in amino acids and lipids also occurs during the transition from non-pregnancy to pregnancy in the uteri of pigs, cattle, and mice. Our analysis provides comprehensive insights into the dynamic landscape of stromal fibroblast cell metabolism, contributing to our understanding of the metabolism at the molecular dynamics underlying the decidualization process in the human endometrium.

Dysregulation of endometrial stromal serotonin homeostasis leading to abnormal phosphatidylcholine metabolism impairs decidualization in patients with recurrent implantation failure.

Does abnormal serotonin homeostasis contribute to impaired endometrial decidualization in patients with recurrent implantation failure (RIF)? Abnormal serotonin homeostasis in patients with RIF, which is accompanied by decreased monoamine oxidase (MAO) expression, affects the decidualization of endometrial stromal cells and leads to embryo implantation failure. Previous studies have indicated that the expression of MAO, which metabolizes serotonin, is reduced in the endometrium of patients with RIF, and serotonin can induce disruption of implantation in rats. However, whether abnormal serotonin homeostasis leads to impaired decidualization in patients with RIF and, if so, the mechanism involved, remains unclear. Endometrial samples from 25 patients with RIF and 25 fertile patients were used to investigate the expression levels of monoamine oxidase A (MAOA), monoamine oxidase B (MAOB), and serotonin. We isolated human endometrial stromal cells to investigate the role of MAOA, MAOB, and serotonin in inducing decidualization in vitro and further explored the underlying mechanism using RNA-sequencing (RNA-seq) and liquid chromatography-mass spectrometry (LC/MS) analyses. The levels of serotonin in the endometrium of patients with RIF were detected by ELISA and immunohistofluorescence, and the key genes involved in abnormal serotonin metabolism were analyzed via combination with single-cell sequencing data. The effects of MAOA or MAOB on the decidualization of stromal cells were investigated using an in vitro human endometrial stromal cell-induced decidualization model and a mouse artificially induced decidualization model. The potential mechanisms by which MAOA and MAOB regulate decidualization were explored by RNA-seq and LC/MS analysis. We found that women with RIF have abnormal serotonin metabolism in the endometrium and attenuated MAO in endometrial stromal cells. Endometrial decidualization was accompanied by increased MAO in vivo and in vitro. However attenuated MAO caused an increased local serotonin content in the endometrium, impairing stromal cell decidualization. RNA-seq and LC/MS analyses showed that abnormal lipid metabolism, especially phosphatidylcholine metabolism, was involved in the defective decidualization caused by MAO deficiency. Furthermore, decidualization defects were rescued by phosphatidylcholine supplementation. RNA-seq information and raw data can be found at NCBI Bioproject number PRJNA892255. This study revealed that impaired serotonin metabolic homeostasis and abnormally reduced MAO expression were among the reasons for RIF. However, the source and other potential functions of serotonin in the endometrium remain to be further explored. This study provides new insights into the mechanisms of serotonin homeostasis in human endometrial decidualization and new biomarkers or targets for the treatment of patients with RIF. X. Sheng is supported by grants from the National Natural Science Foundation of China (82001629), the Wenzhou Basic Public Welfare Research Project (Y20240030), the Youth Program of Natural Science Foundation of Jiangsu Province (BK20200116), and Jiangsu Province Postdoctoral Research Funding (2021K277B). H.S. is supported by grants from the National Natural Science Foundation of China (82030040). G.Y. is supported by grants from the National Natural Science Foundation of China (82171653). The authors declare no conflicts of interest.

Decreased thrombospondin-1 impairs endometrial stromal decidualization in unexplained recurrent spontaneous abortion†.

Inappropriate endometrial stromal decidualization has been implied as an important reason of many pregnancy-related complications, such as unexplained recurrent spontaneous abortion, preeclampsia, and intrauterine growth restriction. Here, we observed that thrombospondin-1, an adhesive glycoprotein, was significantly downregulated in endometrial decidual cells from patients with unexplained recurrent spontaneous abortion. The immortalized human endometrial stromal cell line was used to investigate the possible THBS1-mediated regulation of decidualization. In vitro experiments found that the expression level of THBS1 increased with the normal decidualization process. Knockdown of THBS1 could decrease the expression levels of prolactin and insulin-like growth factor binding protein-1, two acknowledged human decidualization markers, whereas THBS1 overexpression could reverse these effects. The RNA sequencing results demonstrated that the extracellular regulated protein kinases signaling pathway was potentially affected by the knockdown of THBS1. We further confirmed that the regulation of THBS1 on decidualization was achieved through the ERK signaling pathway by the treatment of inhibitors. Moreover, knockdown of THBS1 in pregnant mice could impair decidualization and result in an increased fetus resorption rate. Altogether, our study demonstrated a crucial role of THBS1 in the pathophysiological process of unexplained recurrent spontaneous abortion and provided some new insights into the research of pregnancy-related complications.

Yes Associated Transcriptional Regulator 1 (YAP1) and WW Domain Containing Transcription Regulator (WWTR1) are required for murine pregnancy initiation.

Endometrial stromal cell decidualization is required for pregnancy success. Although this process is integral to fertility, many of the intricate molecular mechanisms contributing to decidualization remain undefined. One pathway that has been implicated in endometrial stromal cell decidualization in humans in vitro is the Hippo signaling pathway. Two previously conducted studies showed that the effectors of the Hippo signaling pathway, YAP1 and WWTR1, were required for decidualization of primary stromal cells in culture. To investigate the in vivo role of YAP1 and WWTR1 in decidualization and pregnancy initiation, we generated a Progesterone Cre mediated partial double knockout (pdKO) of Yap1 and Wwtr1. Female pdKOs exhibited subfertility, a compromised decidualization response, partial interruption in embryo transport, blunted endometrial receptivity, delayed implantation and subsequent embryonic development, and a unique transcriptional profile. Bulk mRNA sequencing revealed aberrant maternal remodeling evidenced by significant alterations in extracellular matrix proteins at 7.5 days post-coitus in pdKO dams and enrichment for terms associated with fertility-compromising diseases like pre-eclampsia and endometriosis. Our results indicate a required role for YAP1 and WWTR1 for successful mammalian uterine function and pregnancy success.

The Long Non-Coding RNA Gene AC027288.3 Plays a Role in Human Endometrial Stromal Fibroblast Decidualization.

During the secretory phase of the menstrual cycle, endometrial fibroblast cells begin to change into large epithelial-like cells called decidual cells in a process called decidualization. This differentiation continues more broadly in the endometrium and forms the decidual tissue during early pregnancy. The cells undergoing decidualization as well as the resulting decidual cells, support successful implantation and placentation during early pregnancy. This study was carried out to identify new potentially important long non-coding RNA (lncRNA) genes that may play a role in human endometrial stromal fibroblast cells (hESF) undergoing decidualization in vitro, and several were found. The expression of nine was further characterized. One of these, AC027288.3, showed a dramatic increase in the expression of hESF cells undergoing decidualization. When AC027288.3 expression was targeted, the ability of the cells to undergo decidualization as determined by the expression of decidualization marker protein-coding genes was significantly altered. The most affected markers of decidualization whose expression was significantly reduced were FOXO1, FZD4, and INHBA. Therefore, AC027288.3 may be a major upstream regulator of the WNT-FOXO1 pathway and activin-SMAD3 pathways previously shown as critical for hESF decidualization. Finally, we explored possible regulators of AC027288.3 expression during human ESF decidualization. Expression was regulated by cAMP and progesterone. Our results suggest that AC027288.3 plays a role in hESF decidualization and identifies several other lncRNA genes that may also play a role.

Progesterone-induced progesterone receptor membrane component 1 rise-to-decline changes are essential for decidualization.

Decidualization of endometrial cells is the prerequisite for embryo implantation and subsequent placenta formation and is induced by rising progesterone levels following ovulation. One of the hormone receptors contributing to endometrial homeostasis is Progesterone Receptor Membrane Component 1 (PGRMC1), a non-classical membrane-bound progesterone receptor with yet unclear function. In this study, we aimed to investigate how PGRMC1 contributes to human decidualization. We first analyzed PGRMC1 expression profile during a regular menstrual cycle in RNA-sequencing datasets. To further explore the function of PGRMC1 in human decidualization, we implemented an inducible decidualization system, which is achieved by culturing two human endometrial stromal cell lines in decidualization-inducing medium containing medroxyprogesterone acetate and 8-Br-cAMP. In our system, we measured PGRMC1 expression during hormone induction as well as decidualization status upon PGRMC1 knockdown at different time points. We further conferred proximity ligation assay to identify PGRMC1 interaction partners. In a regular menstrual cycle, PGRMC1 mRNA expression is gradually decreased from the proliferative phase to the secretory phase. In in vitro experiments, we observed that PGRMC1 expression follows a rise-to-decline pattern, in which its expression level initially increased during the first 6days after induction (PGRMC1 increasing phase) and decreased in the following days (PGRMC1 decreasing phase). Knockdown of PGRMC1 expression before the induction led to a failed decidualization, while its knockdown after induction did not inhibit decidualization, suggesting that the progestin-induced 'PGRMC1 increasing phase' is essential for normal decidualization. Furthermore, we found that the interactions of prohibitin 1 and prohibitin 2 with PGRMC1 were induced upon progestin treatment. Knocking down each of the prohibitins slowed down the decidualization process compared to the control, suggesting that PGRMC1 cooperates with prohibitins to regulate decidualization. According to our findings, PGRMC1 expression followed a progestin-induced rise-to-decline expression pattern during human endometrial decidualization process; and the correct execution of this expression program was crucial for successful decidualization. Thereby, the results of our in vitro model explained how PGRMC1 dysregulation during decidualization may present a new perspective on infertility-related diseases.

#123 : Caveolin-1 Function and Regulation in Mouse Uterus During Early Pregnancy and Under Human In Vitro Decidualization

Background and Aims: Endometrial decidualization is a step in establishing and maintaining pregnancy. Senescence was considered to accompany with decidualization. Failure to clear senescence during decidualization could cause pregnancy abnormalities. Caveolin-1, as a scaffold protein, play a role in senescence, but the expression, regulation and function were not very clear in uterine endometrium. Here, we investigated the profile of Caveolin-1 in mouse and human decidualization to tease out the potential relationship among the Caveolin-1, senescence and decidualization. Method: ICR strain mice and immortalized human endometrial stromal cells (ESCs) were used. Immunofluorescence, Western-Blot, Real-time PCR were used to detect the levels of molecules. Results: In endometrium of mice during early pregnancy, the expression of Caveolin-1 gradually decreased in stroma and epithelium before embryo implantation. However, the level of Caveolin-1 converts in stromal cell after implantation. Estrogen could stimulate expression of Caveolin-1 in epithelium and progesterone could up-regulate level of Caveolin-1 in endometrial stromal cells. In vitro, expression of Caveolin-1 was up-regulated during decidualization in mESCs, while the level of Caveolin-1 was reduced during decidualization in hESCs. siRNA of Caveolin-1 could promote the expression of IGFBP-1 (decidualization biomarker) and senescence in hESCs, while over-expression of Caveolin-1 had the opposite results. In mESCs, Caveolin-1 seems to play a different role in decidualization, over-expression of Caveolin-1 could promote decidualization and senescence in mESCs, but siRNA depressed it. Blastocysts-derived TNF and hCG stimulated Caveolin-1 in mice and depressed it in human decidual cells, respectively. Caveolin-1 levels are also regulated by high glucose and insulin. Conclusion: Caveolin-1 play a role in ESCs decidualization, but the mode of action was different between species. A low level of Caveolin-1 will benefit for human decidualization, disorder of Caveolin-1 could impair decidualization.

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.

The effect of obesity on uterine receptivity is mediated by endometrial extracellular vesicles that control human endometrial stromal cell decidualization and trophoblast invasion

AbstractThe objectives of the present study were to determine whether obesity impacts human decidualization and the endometrial control of trophoblast invasion (both of which are required for embryo implantation) and evaluate the potential involvement of endometrial extracellular vesicles (EVs) in the regulation of these physiological processes. Using primary human cell cultures, we first demonstrated that obesity is associated with significantly lower in vitro decidualization of endometrial stromal cells (ESCs). We then showed that a trophoblastic cell line's invasive ability was greater in the presence of conditioned media from cultures of ESCs from obese women. The results of functional assays indicated that supplementation of the culture medium with EVs from nonobese women can rescue (at least in part) the defect in in vitro decidualization described in ESCs from obese women. Furthermore, exposure to endometrial EVs from obese women (vs. nonobese women) was associated with significantly greater invasive activity by HTR‐8/SVneo cells. Using mass‐spectrometry‐based quantitative proteomics, we found that EVs isolated from uterine supernatants of biopsies from obese women (vs. nonobese women) presented a molecular signature focused on cell remodelling and angiogenesis. The proteomics analysis revealed two differentially expressed proteins (fibronectin and angiotensin‐converting enzyme) that might be involved specifically in the rescue of the decidualization capacity in ESCs from obese women; both of these proteins are abundantly present in endometrial EVs from nonobese women, and both are involved in the decidualization process. In conclusion, our results provided new insights into the endometrial EVs’ pivotal role in the poor uterine receptivity observed in obese women.

P-376 Restoration of mRNA expression level of endometrial MEIS1, as a co-factor of HOXA10, after laparoscopic salpingectomy of women with hydrosalpinx

Abstract Study question Do salpingectomy could restore HOXA10 co-factor MEIS1 expression in endometrial tissues of hydrosalpinx patients? Summary answer Laparoscopic salpingectomy could restore endometrial HOXA10-cofactor- MEIS1 expression level, in addition to HOXA10, in hydrosalpinx women. What is known already Hydrosalpinx is defined as a distally blocked and dilated fallopian tube which has been filled with serous fluid. Evidence suggests that hydrosalpinx is associated with adverse effect on endometrial receptivity by abnormal expression of key molecules such as HOXA10 in the pre-implantation endometrium. Previous data showed salpingectomy results in statistically significant increase in endometrial HOXA10 expression. MEIS1 is a three-amino-acid loop extension (TALE) family homeobox gene which has been proven to be a novel coactivator of HOXA10 during human and mouse endometrial decidualization. MEIS1-HOXA10 complex binds to the promoters of the target genes which are beneficial for human stromal cell decidualization. Study design, size, duration This prospective study was conducted from January 2021 to January 2022 to determine whether salpingectomy would reverse HOXA10-cofactor- MEIS1 expression levels after salpingectomy. All women signed the informed consent and did not receive any hormonal medication during the last three months. In this study 10 infertile women with moderate to severe hydrosalpinx proven by hysterosalpingography or laparoscopy undergoing salpingectomy were recruited. Ten healthy fertile age-matched women considered as control group. Participants/materials, setting, methods Ten infertile women, aged 20-40, with sonovisible hydrosalpinx (diameter >10mm), AMH>1.2 ng/dL, BMI (18–28 kg/m2) and regular menstrual cycle indicated by mid-luteal progesterone levels of > 10 ng/mL were included. Ten healthy fertile age-matched women with a history of successful pregnancy considered as control group. Mid–luteal-phase endometrial sampling (by pipelle) was performed at the time of surgery and second sampling was obtained forth-post treatment cycle. RNA extraction and cDNA synthesis were done. Main results and the role of chance Quantitative mRNA expression of MEIS1 was determined by real-time PCR technique. Gene expression data were analyzed based on 2 –ΔΔCT to estimate the relative fold change value. The non-parametric Wilcoxon signed rank test was used for data analysis. P value less than 0.05 was considered statistically significant.There was a significant reduction in the expression levels of MEIS1 gene in the endometrial samples of hydrosalpinx group before surgical removal. The obtained data showed that salpingectomy resulted in a statistically significant increase (about 6-fold) in endometrial MEIS1 expression (P = 0.02). Moreover, there was not significant difference in MEIS1 mRNA expression of hydrosalpinx group after salpingectomy and the control group (P > 0.05). Limitations, reasons for caution Larger sample size for the confirmation of these data is needed. Epigenetic evaluation of hydrosalpinx endometrial tissues especially in HOXA10 promoter is recommended. Wider implications of the findings This study suggests that the restoration of MEIS1 gene expression observed in hydrosalpinx women after salpingectomy can be considered as a molecular mechanism by which salpingectomy results in improvement of pregnancy rate in IVF cycle. Trial registration number not applicable

P-313 Dysregulation of endometrial stromal serotonin homeostasis impairs decidualization in patients with recurrent implantation failure via phosphatidylcholine metabolism

Abstract Study question Does abnormal serotonin homeostasis contribute to impaired endometrial decidualization in patients with recurrent implantation failure (RIF)? Summary answer Abnormal serotonin homeostasis in patients with RIF, which is accompanied by decreased expression of monoamine oxidase (MAO), affects decidualization of endometrial stromal cells. What is known already Previous studies have found that the expression of MAO, which metabolizes serotonin, is reduced in the endometrium of patients with RIF, and serotonin can induce disruption of implantation in rats. However, whether abnormal serotonin homeostasis leads to impaired decidualization in patients with RIF and the mechanism remains unclear. Study design, size, duration Endometrial samples from 31 patients with RIF and 31 fertile patients were used to investigate the expression levels of MAOA, MAOB, and serotonin. We isolated human endometrial stromal cells to investigate the role of MAOA, MAOB and serotonin in inducing decidualization in vitro and further explored the mechanism using RNA-seq and LC/MS analyses. Participants/materials, setting, methods The levels of serotonin in the endometrium of patients with RIF were detected by ELISA and immunohistofluorescence, and the key genes of abnormal serotonin metabolism were analyzed combined with single-cell sequencing data. The effects of MAO on the decidualization of stromal cells were investigated using human endometrial stromal cells in vitro induced decidualization model and mouse artificially induced decidualization model. The potential mechanisms of MAO regulating decidualization were explored by RNA-seq and LC/MS analysis. Main results and the role of chance We found that women with RIF have abnormal serotonin metabolism in the endometrium and attenuated MAO in endometrial stromal cells. Endometrial decidualization was accompanied by increased MAO in vivo and in vitro. Attenuated MAO caused increased local serotonin content in the endometrium, impairing stromal cell decidualization. RNA-seq and LC/MS analyses showed that abnormal lipid metabolism, especially phosphatidylcholine metabolism, was involved in MAO-deficiency induced defective decidualization. Furthermore, decidualization defects were rescued by phosphatidylcholine supplementation. Limitations, reasons for caution This study found that impaired serotonin metabolic homeostasis and abnormally reduced MAO expression were one of the reasons for repeated implantation failure. However, the source and other potential function of serotonin in the endometrium remain to be further explored. Wider implications of the findings This study shows new insights into the mechanisms of serotonin homeostasis in human endometrial decidualization and provides new biomarkers or targets for the treatment of patients with RIF. Trial registration number not applicable

P-313 Dysregulation of endometrial stromal serotonin homeostasis impairs decidualization in patients with recurrent implantation failure via phosphatidylcholine metabolism

Abstract Study question Does abnormal serotonin homeostasis contribute to impaired endometrial decidualization in patients with recurrent implantation failure (RIF)? Summary answer Abnormal serotonin homeostasis in patients with RIF, which is accompanied by decreased expression of monoamine oxidase (MAO), affects decidualization of endometrial stromal cells. What is known already Previous studies have found that the expression of MAO, which metabolizes serotonin, is reduced in the endometrium of patients with RIF, and serotonin can induce disruption of implantation in rats. However, whether abnormal serotonin homeostasis leads to impaired decidualization in patients with RIF and the mechanism remains unclear. Study design, size, duration Endometrial samples from 31 patients with RIF and 31 fertile patients were used to investigate the expression levels of MAOA, MAOB, and serotonin. We isolated human endometrial stromal cells to investigate the role of MAOA, MAOB and serotonin in inducing decidualization in vitro and further explored the mechanism using RNA-seq and LC/MS analyses. Participants/materials, setting, methods The levels of serotonin in the endometrium of patients with RIF were detected by ELISA and immunohistofluorescence, and the key genes of abnormal serotonin metabolism were analyzed combined with single-cell sequencing data. The effects of MAO on the decidualization of stromal cells were investigated using human endometrial stromal cells in vitro induced decidualization model and mouse artificially induced decidualization model. The potential mechanisms of MAO regulating decidualization were explored by RNA-seq and LC/MS analysis. Main results and the role of chance We found that women with RIF have abnormal serotonin metabolism in the endometrium and attenuated MAO in endometrial stromal cells. Endometrial decidualization was accompanied by increased MAO in vivo and in vitro. Attenuated MAO caused increased local serotonin content in the endometrium, impairing stromal cell decidualization. RNA-seq and LC/MS analyses showed that abnormal lipid metabolism, especially phosphatidylcholine metabolism, was involved in MAO-deficiency induced defective decidualization. Furthermore, decidualization defects were rescued by phosphatidylcholine supplementation. Limitations, reasons for caution This study found that impaired serotonin metabolic homeostasis and abnormally reduced MAO expression were one of the reasons for repeated implantation failure. However, the source and other potential function of serotonin in the endometrium remain to be further explored. Wider implications of the findings This study shows new insights into the mechanisms of serotonin homeostasis in human endometrial decidualization and provides new biomarkers or targets for the treatment of patients with RIF. Trial registration number not applicable Study funding No Funding source Funding by national/international organization(s)

Resveratrol reliefs DEHP-induced defects during human decidualization

Di-(2-Ethylhexyl) phthalate (DEHP) is widely used as an additive in many plastic products. Studies have revealed that DEHP persistent exposure can affect embryonic development and lead to adverse female reproductive disorders. The establishment of pregnancy involves extensive changes in the endometrial tissue, including massive extracellular matrix (ECM) remodeling. Decidualization of the endometrium provides a suitable environment for subsequent growth by causing changes in the morphology of the uterine stromal cells, is a key process in human pregnancy. Resveratrol (RSV) is a natural polyphenolic plant antitoxin with a wide range of pharmacological effects. Growing evidence indicates that RSV has therapeutic effects on certain female reproductive disorders. In this study, the effect of DEHP on cell viability was investigated by cell proliferation assay. Cell decidualization was induced in vitro, and the downregulation of molecules associated with decidualization was confirmed through quantitative real-time PCR and western blot analysis. Immunofluorescence analysis revealed alteration in cell morphology, and found that administration of DEHP sufficiently induced ERα entry into the nucleus. The effect of DEHP on cells was fully verified by RNA-seq analysis. Interestingly, an upregulation of decidual molecules was observed after rescue with RSV, which was confirmed by RNA-seq transcriptome analysis and quantitative real-time PCR assay. Additionally, the expression of ECM remodeling-related genes was significantly restored by RSV administration. The study revealed the potential mechanisms of DEHP-induced decidualization defects and the functional relieving roles of RSV while providing a perspective therapeutic candidate for alleviating the DEHP-induced deficiencies in decidualization.

Human Chorionic Gonadotropin-Stimulated Interleukin-4-Induced-1 (IL4I1) Promotes Human Decidualization via Aryl Hydrocarbon Receptor.

Decidualization is necessary for the successful establishment of early pregnancy in rodents and humans. Disturbed decidualization results in recurrent implantation failure, recurrent spontaneous abortion, and preeclampsia. Tryptophan (Trp), one of the essential amino acids in humans, has a positive effect on mammalian pregnancy. Interleukin 4-induced gene 1 (IL4I1) is a recently identified enzyme that can metabolize L-Trp to activate aryl hydrocarbon receptor (AHR). Although IDO1-catalyzed kynurenine (Kyn) from Trp has been shown to enhance human in vitro decidualization via activating AHR, whether IL4I1-catalyzed metabolites of Trp are involved in human decidualization is still unknown. In our study, human chorionic gonadotropin stimulates IL4I1 expression and secretion from human endometrial epithelial cells through ornithine decarboxylase-induced putrescine production. Either IL4I1-catalyzed indole-3-pyruvic acid (I3P) or its metabolite indole-3-aldehyde (I3A) from Trp is able to induce human in vitro decidualization by activating AHR. As a target gene of AHR, Epiregulin induced by I3P and I3A promotes human in vitro decidualization. Our study indicates that IL4I1-catalyzed metabolites from Trp can enhance human in vitro decidualization through AHR-Epiregulin pathway.

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

IntroductionThis study aimed to study the expression and function of kisspeptin during human uterine decidualization in recurrent spontaneous abortion (RSA) and the underlying mechanism. MethodsAll 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. ResultsSerum 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. DiscussionKisspeptin is involved in promoting uterine decidualization via the ERK1/2 signalling pathway.

Primary Cilia Restrain PI3K-AKT Signaling to Orchestrate Human Decidualization

Endometrial decidualization plays a pivotal role during early pregnancy. Compromised decidualization has been tightly associated with recurrent implantation failure (RIF). Primary cilium is an antenna-like sensory organelle and acts as a signaling nexus to mediate Hh, Wnt, TGFβ, BMP, FGF, and Notch signaling. However, whether primary cilium is involved in human decidualization is still unknown. In this study, we found that primary cilia are present in human endometrial stromal cells. The ciliogenesis and cilia length are increased by progesterone during in vitro and in vivo decidualization. Primary cilia are abnormal in the endometrium of RIF patients. Based on data from both assembly and disassembly of primary cilia, it has been determined that primary cilium is essential to human decidualization. Trichoplein (TCHP)-Aurora A signaling mediates cilia disassembly during human in vitro decidualization. Mechanistically, primary cilium modulates human decidualization through PTEN-PI3K-AKT-FOXO1 signaling. Our study highlights primary cilium as a novel decidualization-related signaling pathway.

An IGF1-expressing endometrial stromal cell population is associated with human decidualization

Decidualization refers to the process of transformation of endometrial stromal fibroblast cells into specialized decidual stromal cells that provide a nutritive and immunoprivileged matrix essential for blastocyst implantation and placental development. Deficiencies in decidualization are associated with a variety of pregnancy disorders, including female infertility, recurrent implantation failure (RIF), and miscarriages. Despite the increasing number of genes reportedly associated with endometrial receptivity and decidualization, the cellular and molecular mechanisms triggering and underlying decidualization remain largely unknown. Here, we analyze single-cell transcriptional profiles of endometrial cells during the window of implantation and decidual cells of early pregnancy, to gains insights on the process of decidualization. We observed a unique IGF1+ stromal cell that may initiate decidualization by single-cell RNA sequencing. We found the IL1B+ stromal cells promote gland degeneration and decidua hemostasis. We defined a subset of NK cells for accelerating decidualization and extravillous trophoblast (EVT) invasion by AREG-IGF1 and AREG-CSF1 regulatory axe. Further analysis indicates that EVT promote decidualization possibly by multiply pathways. Additionally, a systematic repository of cell-cell communication for decidualization was developed. An aberrant ratio conversion of IGF1+ stromal cells to IGF1R+ stromal cells is observed in unexplained RIF patients. Overall, a unique subpopulation of IGF1+ stromal cell is involved in initiating decidualization. Our observations provide deeper insights into the molecular and cellular characterizations of decidualization, and a platform for further development of evaluation of decidualization degree and treatment for decidualization disorder-related diseases.

ENDOMETRIAL ADHESION G-PROTEIN COUPLED RECEPTOR EXPRESSION IS ALTERED BY OVARIAN STIMULATION

Ovarian stimulation (OS) is associated with altered endometrial histological development and gene expression which may impact receptivity in fresh embryo transfers. We sought to determine the effect of OS on the expression of endometrial genes encoding adhesion G protein-coupled receptors (ADGRs). While ADGRG2 has been identified as a regulator of human endometrial decidualization and receptivity, less is known regarding the roles of other ADGRs in the human endometrium. We hypothesized that in a natural cycle (NC) ADGRs are expressed in the secretory endometrium but following OS their expression is altered.

A novel lncRNAlncSAMD11-1: 1 interacts with PIP4K2A to promote endometrial decidualization by stabilizing FoxO1 nuclear localization.

Decidualization is essential for a successful pregnancy and determines embryo implantation and pregnancy maintenance. Abnormal decidualization is one of the main causes of recurrent implantation failure (RIF). Studies have shown that large amounts of long noncoding RNAs (lncRNAs) are abnormally expressed in endometrial samples from patients with RIF. However, the functional contributions of lncRNAs to decidualization in RIF have not been explored. In this study, we found that lncSAMD11-1:1 was significantly declined in the endometria of patients with RIF. The knockdown of lncSAMD11-1:1 in human endometrial stromal cells (hESCs) restrained decidualization and embryo implantation in vitro, while the overexpression of lncSAMD11-1:1 facilitated hESC decidualization and embryo implantation in vitro and ameliorated decidualization in RIF patients. Mechanistically, lncSAMD11-1:1 and phosphatidylinositol-5-phosphate 4-kinase type 2 alpha (PIP4K2A) translocated out of nucleus and bound to each other during decidualization, thereby inhibiting the phosphorylation of AKT and promoting FoxO1 nuclear localization. These data suggest that lncSAMD11-1:1 might be a critical novel lncRNA functionally required for human decidualization, and the dysregulation of lncSAMD11-1:1 in the endometrium may be a new predisposing factor of RIF.