Mechanism of human endometrial stromal cells decidualization

Transcriptomic analysis of human endometrial stromal cells during early embryo invasion

PURPOSE

During early embryo invasion (48 h after embryo attachment), what functional changes accompany dynamic gene expression alterations in human endometrial stromal cells?

METHOD

In the present study, primary human endometrial stromal cells (phESCs) were cultured. After in vitro decidualization, primary human endometrial stromal cells (phESCs) were cultured with blastocysts for 48 h. During this process, blastocysts attached and invaded the phESCs (embryo-invaded primary human endometrial stromal cells, ehESCs). We performed comprehensive transcriptomic profiling of phESCs (two replicates) and ehESCs (five replicates) and analyzed the differentially expressed gene (DEGs) sets for gene ontology (GO) terms and Kyoto encyclopaedia of genes and genomes (KEGG) pathway enrichment. To analyse potential connectivity patterns between the transcripts in these DEG sets, a protein-protein interaction (PPI) network was constructed using the STRING database.

RESULTS

A total of 592 DEGs were identified between phESCs and ehESCs after embryo invasion. Primary human endometrial stromal cells underwent significant transcriptomic changes that occur in a stepwise fashion. Oxidative phosphorylation, mitochondrial organization, and P53 signalling pathways were significantly altered in phESCs after embryo invasion. EP300 may play a key role in regulating transcription via chromatin remodelling to facilitate the adaptive gene expression changes that occur during embryo invasion.

CONCLUSIONS

Our data identify dynamic transcriptome changes that occur in endometrial stromal cells within 48 h after embryo invasion. The pathways that we found to be enriched in phESCs after embryo invasion (oxidative phosphorylation, mitochondrial organization, and P53 signalling) may represent novel mechanisms underlying embryo implantation, and may illuminate the reasons that some women experience reproductive failure.Key messagesHuman endometrial stromal cells have undergone changes in gene expression regulation and signalling pathways during the embryo invasion.Mitochondrial-oxidative phosphorylation changes in human stromal cells manifested as down-regulation of gene expression in the electron transport chain.TP53 signalling pathway and transcriptional regulator EP300 assist stromal cells to get adaptive changes during embryo invasion phase.

Inhibition of TPPP3 attenuates β-catenin/NF-κB/COX-2 signaling in endometrial stromal cells and impairs decidualization

Embryo implantation and decidualization are critical events that occur during early pregnancy. Decidualization is synchronized by the crosstalk of progesterone and the cAMP signaling pathway. Previously, we confirmed the role of TPPP3 during embryo implantation in mice, but the underlying role and mechanism of TPPP3 in decidualization has not yet been understood. The current study was aimed to investigate the role of TPPP3 in decidualization in vivo and in vitro. For in vivo experiments, decidual reaction was artificially induced in the uteri of BALB/c mice. TPPP3 was found to be highly expressed during decidualization, whereas in the uteri receiving TPPP3 siRNA, decidualization was suppressed and the expression of β-catenin and decidual marker prolactin was reduced. In human endometrium, TPPP3 protein was found to be predominantly expressed in the mid-secretory phase (LH+7). In the primary culture of human endometrial stromal cells (hESCs), TPPP3 siRNA knockdown inhibited stromal-to-decidual cell transition and decreased the expression of the decidualization markers prolactin and IGFBP-1. Immunofluorescence and immunoblotting experiments revealed that TPPP3 siRNA knockdown suppressed the expression of β-catenin, NF-κB and COX-2 in hESCs during decidualization. TPPP3 inhibition also decreased NF-kB nuclear accumulation in hESCs and suppressed NF-κB transcriptional promoter activity. COX-2 expression was significantly decreased in the presence of a selective NF-kB inhibitor (QNZ) implicating that NF-kB is involved in COX-2 expression in hESCs undergoing decidualization. TUNEL assay and FACS analysis revealed that TPPP3 knockdown induced apoptosis and caused loss of mitochondrial membrane potential in hESCs. The study suggested that TPPP3 plays a significant role in decidualization and its inhibition leads to the suppression of β-catenin/NF-κB/COX-2 signaling along with the induction of mitochondria-dependent apoptosis.

Crosstalk between human endometrial stromal cells and decidual NK cells promotes decidualization in vitro by upregulating IL‑25

Embryo implantation is essential for a successful pregnancy, and leads to the decidualization of endometrial stromal cells (ESCs) in the secretory phase of the menstrual cycle. It has previously been demonstrated that decidual stromal cells (DSCs) co‑express interleukin (IL)‑25/IL‑17RB and that IL‑25 further promotes the proliferation of DSCs via activating c‑Jun n‑terminal kinase and protein kinase B signals, therefore the present study primarily focused on the role of IL‑25 in the process of decidualization in vitro. It was demonstrated that the expression of IL‑25/IL‑17RB in ESCs was decreased compared with DSCs. In addition, following decidualization, the expression levels of IL‑25/IL‑17RB in ESCs were significantly elevated. Recombinant human (rh) IL‑25 promoted the decidualization of ESCs in the presence of 8‑bromoadenosine 3',5'‑cyclic monophosphate sodium salt and 6α‑methyl17α‑acetoxyprogesterone, which was partially inhibited by anti‑human IL‑25 neutralizing antibody (anti‑IL‑25) or anti‑IL‑17RB. In addition, decidual natural killer (dNK) cells not only secreted IL‑25, however also further accelerated the decidualization in vitro. Therefore, these findings indicated that ESCs differentiate into DSCs in the presence of ovarian hormones, resulting in the upregulation of IL‑25/IL‑17RB expression in ESCs. Furthermore, IL‑25 secreted by ESCs and dNK cells further facilitates the decidualization of ESCs, which may form a positive feedback mechanism at the maternal‑fetal interface and thus contribute to the establishment and maintenance of normal pregnancy.

The endocannabinoid anandamide impairs in vitro decidualization of human cells

Endocannabinoids (eCBs) are endogenous mediators that along with the cannabinoid receptors (CB1 and CB2), a membrane transporter and metabolic enzymes form the endocannabinoid system (ECS). Several eCBs have been discovered with emphasis on anandamide (AEA). They are involved in several biological processes such as energy balance, immune response and reproduction. Decidualization occurs during the secretory phase of human menstrual cycle, which involves proliferation and differentiation of endometrial stromal cells into decidual cells and is crucial for the establishment and progression of pregnancy. In this study, a telomerase-immortalized human endometrial stromal cell line (St-T1b) and non-differentiated primary cultures of human decidual fibroblasts from term placenta were used to characterize the ECS using immunoblotting and qRT-PCR techniques. It was shown that St-T1b cells express CB1, but not CB2, and that both receptors are expressed in HdF cells. Furthermore, the expression of fatty acid amide hydrolase (FAAH), the main degrading enzyme of AEA, increased during stromal cell differentiation. AEA inhibited cell proliferation, through deregulation of cell cycle progression and induced polyploidy. Moreover, through CB1 binding receptor, AEA also impaired cell differentiation. Therefore, AEA is proposed as a modulator of human decidualization. Our findings may provide wider implications, as deregulated levels of AEA, due to Cannabis sativa consumption or altered expression of the metabolic enzymes, may negatively regulate human endometrial stromal cell decidualization with an impact on human (in)fertility.Free Portuguese abstract: A Portuguese translation of this abstract is freely available at http://www.reproduction-online.org/content/152/4/351/suppl/DC1.

RANKL-mediated harmonious dialogue between fetus and mother guarantees smooth gestation by inducing decidual M2 macrophage polarization

Decidual macrophages (dMφ) contribute to maternal–fetal tolerance. However, the mechanism of dMφ differentiation during pregnancy is still largely unknown. Here, we report that receptor activator for nuclear factor-κ B ligand (RANKL), secreted by human embryonic trophoblasts and maternal decidual stromal cells (DSCs), polarizes dMφ toward a M2 phenotype. This polarization is mediated through activation of Akt/signal transducer and activator of transcription 6 (STAT6) signaling, which is associated with the upregulation of histone H3 lysine-27 demethylase Jmjd3 and IRF4 in dMφ. Such differentiated dMφ can induce a Th2 bias that promotes maternal–fetal tolerance. Impaired expression of RANKL leads to dysfunction of dMφ in vivo and increased rates of fetal loss in mice. Transfer of RANK⁺Mφ reverses mouse fetal loss induced by Mφ depletion. Compared with normal pregnancy, there are abnormally low levels of RANKL/RANK in villi and decidua from miscarriage patients. These results suggest that RANKL is a pivotal regulator of maternal–fetal tolerance by licensing dMφ to ensure a successful pregnancy outcome. This observation provides a scientific basis on which a potential therapeutic strategy can be targeted to prevent pregnancy loss.

Regulation of the PI3K/Akt pathway during decidualization of endometrial stromal cells

Infertility is constantly increasing in Canada, where 16% of Canadian couples are experiencing difficulty conceiving. It is thought that infertility can emanate from the dysregulated communication between the embryo and the maternal endometrium. In order to allow for this window of implantation to be open at the right moment, endometrial stromal cells proliferate and differentiate by a mechanism called decidualization. Intracellular and molecular mechanisms involved in the regulation of apoptosis and cell proliferation during decidualization of the endometrium are yet to be fully understood. It has been well demonstrated previously that Akt is importantly involved in cell survival and glycogen synthesis. Akt1, Akt2 and Akt3 isoforms have distinct physiological roles; this could also be the case during decidualization and pregnancy. The aim of this study is to investigate the regulation of PI3K/Akt pathway during the decidualization process of endometrial stromal cells. Expression of Akt isoforms, Akt activity (phospho-Akt), pIκB and substrates of Akt during decidualization were measured. To our knowledge, these results are the first to suggest a decrease in levels of Akt isoforms as well as a downregulation of Akt activity in the process of decidualization of human endometrial stromal cells. We also uncovered that decidualization induced nuclear localization of p65 through the phosphorylation of IκB, its inhibitory subunit; however, Par-4, a recently uncovered regulator of cell differentiation, was displaced from the nucleus upon decidualization. Our results also suggest that HIESC cells exhibit decreased motility during decidualization and that PI3K pathway inhibition could be involved in this process. Finally, we demonstrate that specific Akt isoforms present unique effects on the successful induction of decidualization. Further analyses will involve investigations to understand the precise signaling mechanisms by which this pathway is regulated.

Effects of electroacupuncture on uterine morphology and expression of oestrogen receptors in ovariectomised rats

AIM

To observe the effects of electroacupuncture (EA) on uterine morphology and expression of oestrogen receptor (ER) α and β in ovariectomised (OVX) rats.

METHODS

Thirty female Sprague-Dawley rats with regular 4-day oestrus cycles were divided into a sham operation group (Control, n=10) and two OVX groups that remained untreated (OVX group, n=10) or received EA treatment (OVX+EA group, n=10). In the latter group, EA was applied at CV4, CV3, SP6 and bilateral Zigong (30 min per day) for 3 days. The effects of EA on uterine morphology were observed by H&E staining. Quantitative real-time reverse transcription-PCR (qRT-PCR) and Western blotting were used to measure ERα and ERβ mRNA and protein expression, respectively.

RESULTS

Relative to the (untreated) OVX group, EA treatment significantly increased the uterine wet weight to body weight (UWW/BW) ratio (0.47±0.04 vs 0.31±0.03 g/kg, p=0.04), and myometrial thickness (109.39±10.71 vs 60.81±8.1 μm, p=0.016) of OVX rats. Similarly, the total number of endometrial glands per cross section and endometrial thickness in the OVX +EA group was significantly increased compared to the (untreated) OVX group. EA treatment also increased protein (but not mRNA) expression of both ERα and ERβ in the uteri of OVX rats.

CONCLUSIONS

This study has demonstrated that EA treatment decreases uterine atrophy in OVX rats. This unique effect of EA on the uterus may be due to upregulation of serum levels of E₂ and differential regulation of sex steroid receptors ERα and ERβ.

Intracrine Androgens Enhance Decidualization and Modulate Expression of Human Endometrial Receptivity Genes

The endometrium is a complex, steroid-dependent tissue that undergoes dynamic cyclical remodelling. Transformation of stromal fibroblasts (ESC) into specialised secretory cells (decidualization) is fundamental to the establishment of a receptive endometrial microenvironment which can support and maintain pregnancy. Androgen receptors (AR) are present in ESC; in other tissues local metabolism of ovarian and adrenal-derived androgens regulate AR-dependent gene expression. We hypothesised that altered expression/activity of androgen biosynthetic enzymes would regulate tissue availability of bioactive androgens and the process of decidualization. Primary human ESC were treated in vitro for 1–8 days with progesterone and cAMP (decidualized) in the presence or absence of the AR antagonist flutamide. Time and treatment-dependent changes in genes essential for a) intra-tissue biosynthesis of androgens (5α-reductase/SRD5A1, aldo-keto reductase family 1 member C3/AKR1C3), b) establishment of endometrial decidualization (IGFBP1, prolactin) and c) endometrial receptivity (SPP1, MAOA, EDNRB) were measured. Decidualization of ESC resulted in significant time-dependent changes in expression of AKR1C3 and SRD5A1 and secretion of T/DHT. Addition of flutamide significantly reduced secretion of IGFBP1 and prolactin and altered the expression of endometrial receptivity markers. Intracrine biosynthesis of endometrial androgens during decidualization may play a key role in endometrial receptivity and offer a novel target for fertility treatment.

RANKL promotes the growth of decidual stromal cells in an autocrine manner via CCL2/CCR2 interaction in human early pregnancy

OBJECTIVE

Receptor-activator of NF-κB ligand (TNFSF11, also known as RANKL) and its receptor RANK are essential regulators on bone remodeling, mammary gland development and hormone-associated breast cancer development. However, the expression pattern and role of RANKL/RANK axis in decidual stromal cells (DSCs) are unclear in human early pregnancy.

STUDY DESIGN

We analyzed RANKL/RANK expression in DSCs by real-time PCR, immunhistochemistry, enzyme-linked immunosorbent assay (ELISA) and flow cytometry, respectively. Then BrdU cell proliferation assay, flow cytometry assay and ELISA were performed to investigate the effect of recombinant human RANKL and DSCs-derived RANKL on the proliferation, apoptosis, chemokine (C-C motif) ligand 2 (CCL2) secretion, C-C chemokine receptor type 2 (CCR2) and other target proteins expression in DSCs in vitro, respectively.

RESULTS

Here we show that DSCs co-express RANKL/RANK. Not only recombinant human (rh) RANKL but also the DSC-secreted RANKL stimulate proliferation and anti-apoptosis, and elevate CCL2 secretion and CCR2 expression of DSCs. Furthermore, the stimulatory effects on the proliferation, anti-apoptosis and the expression of Bcl-2 and Ki67 and inhibitory signaling on Fas ligand (FasL) in DSCs induced by RANKL can be partly reversed by the way of blocking CCL2 and or CCR2.

CONCLUSIONS

Our results have revealed that RANKL/RANK signal promotes Bcl-2 and Ki67 and decreases FasL expression, and further as a positive regulator for stimulating the proliferation and growth of DSCs through up-regulating CCL2/CCR2 signal, which finally contributes to the establishment and maintenance of physiological pregnancy.

Effect of cyclic AMP and estrogen/progesterone on the transcription of DNA methyltransferases during the decidualization of human endometrial stromal cells

Progesterone, estrogen and cyclic adenosine monophosphate (cAMP) together regulate the decidualization of human endometrial stromal cells in a time-dependent manner. The role of DNA methylation and the three active DNA methyltransferases (DNMTs) in the regulation of decidualization is gaining interest but the exact role of this epigenetic mechanism during decidualization is largely unknown. We aimed to understand the effect of the main regulators of decidualization on the expression of the DNMTs and in turn on the expression of steroid hormone receptors during the decidualization. We conducted a time-course analysis from 6 h to 10 days to examine the change in gene expression of the DNMTs and the steroid hormone receptors over time in response to estradiol, medroxy-progesterone acetate (MPA) and dibutyryl-cAMP (db-cAMP) in a human endometrial stromal cells (HESC) cell line. Only the combination treatment with MPA-mix (estradiol + MPA + db-cAMP) up-regulated ERα, PGR, progesterone receptor B (PRB) and androgen receptor at 24 h. Both decidualization pathways of db-cAMP and estradiol/MPA, independently and combined, consistently down-regulated DNMT3B mRNA expression from 6 h till 10 days, whereas DNMT1 and DNMT3A mRNA expression were down-regulated transiently. Forced expression of DNMT3B in HESC for 10 days attenuated IGFBP1 mRNA and protein expression; and forced expression of DNMT3B combined with MPA-mix treatment synergistically increased the expression of PRB at 24 h. The HESC morphology and proliferation remained unchanged in response to forced expression of DNMT3B. In conclusion, mRNA expression of the DNMTs during decidualization is dynamic, so that expression varies according to the cAMP or estradiol/MPA pathway treatments that regulate them in a time-dependent manner. Although forced expression of DNMT3B by itself is insufficient to inhibit decidualization, forced expression of DNMT3B in combination with MPA-mix synergistically up-regulated PRB, as well as attenuated the expression of IGFBP1, the decidualization marker.

Modulation of the expression of the transcription factors T-bet and GATA-3 in immortalized human endometrial stromal cells (HESCs) by sex steroid hormones and cAMP

T-bet and GATA-3 are known to regulate cytokine expression in T lymphocytes, and cytokines have been implicated in endometrial regulation and implantation. Previous work showed that female steroid hormones modulate the expression of T-bet in endometrial epithelial cells, suggesting a mechanism for local immune regulation in the human endometrium. We hypothesized that stromal cells are involved in immune regulation, as they have been shown to exert paracrine effects on other endometrial cells and compartments and also secrete cytokines. The objective of this study was to examine the modulation of the gene expression of T-bet and GATA-3, and of the cytokines interferon γ (IFN-γ) and interleukin 4 (IL-4), by female steroid hormones, in human endometrial stromal cells (HESC) in long-term cultures (30 days) mimicking the normal menstrual cycle. T-bet and GATA-3 messenger RNA (mRNA) expression was detected by real-time polymerase chain reaction, and intracellular protein production was demonstrated by immunoblotting. In addition, secretion of IL-4 and IL-15 was measured by enzyme-linked immunosorbent assay. T-bet and IL-4 mRNA expression increased and GATA-3 decreased under decidualization conditions; IFN-γ was not detected. Secretion of IL-15 increased during decidualization, and IL-15 upregulated T-bet gene expression. In conclusion, gene expression of T-bet and GATA-3 by endometrial stromal cells is under hormonal conditions mimicking decidualization, and the results are consistent with an autocrine regulatory mechanism of IL-15 secretion and T-bet expression.

FOXO1 expression and regulation in endometrial tissue during the menstrual cycle and in early pregnancy decidua

AIMS

To determine FOXO1 (forkhead box O1) expression in the human endometrium during the menstrual cycle and decidua of early pregnancy, as well as FOXO1 regulation in endometrial stromal cells (ESC).

METHODS

Immunohistochemistry, RT-qPCR, and Western blot analyses evaluated cellular localization and altered FOXO1 expression in the endometrium during the menstrual cycle and decidua of early pregnancy (proliferative phase, n = 12; early-secretory phase, n = 7; mid-secretory phase, n = 10; late-secretory phase, n = 10; early pregnancy, n = 12). Using RT-qPCR and Western blot, we studied the regulation of FOXO1 by 8-bromo-cAMP, 4-pregnene-3,20-dione, 17β-estradiol, and human chorionic gonadotrophin in ESC (n = 5).

RESULTS

The expression level of FOXO1 in human endometrial tissue fluctuated with the menstrual cycle. If pregnancy occurred, the expression of FOXO1 was further increased (p < 0.05) and cAMP regulated FOXO1 expression in ESC. In addition, 4-pregnene-3,20-dione cooperatively stimulated FOXO1 expression with cAMP. We also observed FOXO1 expression during in vitro cAMP-induced decidualization.

CONCLUSIONS

The pattern of FOXO1 expression suggests a potential role for FOXO1 in implantation and decidualization.

Cell lineage specific distribution of H3K27 trimethylation accumulation in an in vitro model for human implantation

Female mammals inactivate one of their two X-chromosomes to compensate for the difference in gene-dosage with males that have just one X-chromosome. X-chromosome inactivation is initiated by the expression of the non-coding RNA Xist, which coats the X-chromosome in cis and triggers gene silencing. In early mouse development the paternal X-chromosome is initially inactivated in all cells of cleavage stage embryos (imprinted X-inactivation) followed by reactivation of the inactivated paternal X-chromosome exclusively in the epiblast precursors of blastocysts, resulting temporarily in the presence of two active X-chromosomes in this specific lineage. Shortly thereafter, epiblast cells randomly inactivate either the maternal or the paternal X-chromosome. XCI is accompanied by the accumulation of histone 3 lysine 27 trimethylation (H3K27me3) marks on the condensed X-chromosome. It is still poorly understood how XCI is regulated during early human development. Here we have investigated lineage development and the distribution of H3K27me3 foci in human embryos derived from an in-vitro model for human implantation. In this system, embryos are co-cultured on decidualized endometrial stromal cells up to day 8, which allows the culture period to be extended for an additional two days. We demonstrate that after the co-culture period, the inner cell masses have relatively high cell numbers and that the GATA4-positive hypoblast lineage and OCT4-positive epiblast cell lineage in these embryos have segregated. H3K27me3 foci were observed in ∼25% of the trophectoderm cells and in ∼7.5% of the hypoblast cells, but not in epiblast cells. In contrast with day 8 embryos derived from the co-cultures, foci of H3K27me3 were not observed in embryos at day 5 of development derived from regular IVF-cultures. These findings indicate that the dynamics of H3K27me3 accumulation on the X-chromosome in human development is regulated in a lineage specific fashion.

Interleukin 11 and activin A synergise to regulate progesterone-induced but not cAMP-induced decidualization

Blastocyst implantation, placentation and the establishment of pregnancy in the human are dependent on the adequate decidualization of endometrial stromal cells. Locally produced and temporally regulated products such as interleukin 11 (IL11), and activin A are involved in this process; however, the molecular interactions that regulate decidualization are largely unknown. Here, we investigated whether IL11 and activin A interact to promote human endometrial stromal cell (HESC) decidualization using an in vitro model. HESCs, induced to decidualize by cAMP or progesterone, were treated with IL11, activin A or IL11 plus activin A combined and decidual progress was examined using prolactin as a decidual marker. Treatment with combined IL11 plus activin A enhanced progesterone-induced decidualization above control or treatment with IL11 or activin A alone. Treatment had no effect on cAMP-decidualized HESC. Investigation of IL11 and activin A stimulation of (respectively) activin A and IL11 expression in undifferentiated HESC was by real-time PCR and ELISA. Activin A treatment induced IL11 secretion and phosphorylation of the activin A signalling component, SMAD2 (measured by ELISA). Inclusion of the TGFbeta 1 receptor inhibitor, SB431542, in the activin A treatment, reduced pSMAD2 and IL11 secretion. This study suggests that activin A is an early inducer of decidualization, regulating the secretion of IL11. This data provides insight into the processes underlying decidualization, which are important for understanding implantation and placentation and have potential clinical applications for the regulation of fertility.

The activation of matrix metalloproteinase-2 induced by protein kinase C alpha in decidualization

This study investigated the protein kinase C (PKC) and matrix metalloproteinase-2 (MMP-2) in the development of deciduomata in pseudo-pregnant and pregnant rats. The results showed that the expression of MMP-2 was significantly increased from day 2 to day 5 in pseudo-pregnancy and from day 7 to day 9 in pregnancy. To further investigate the correlation between MMP-2 and protein kinase C alpha (PKC alpha), the expression of MMP-2 in the 12-O-tetradecanoylphorbol 13-acetate (TPA)-treated organotypic culture of decidual tissue was determined. The results showed that the active form of MMP-2 was significantly increased in the TPA-treated cultures. Moreover, this response was inhibited by the PKC inhibitor H7, the PKC alpha specific inhibitor Gö-6976 and the translation inhibitor cycloheximide, but not by the transcription inhibitor actinomycin D or the replication inhibitor mitomycin C. In addition, TPA also reversed the MMP-2 expression after by progesterone pretreatment in the primary decidual cells. These findings indicate that PKC alpha may play an important role in the regulation of the MMP-2 expression during decidualization.

Decidualization attenuates the contractility of eutopic and ectopic endometrial stromal cells: implications for hormone therapy of endometriosis

CONTEXT

Decidualization of the endometrium involves the morphological and biochemical reprogramming of the estrogen-primed proliferative endometrial stromal compartment under the continuing influence of progesterone.

OBJECTIVES

The aim of this study was to evaluate the involvement of the extracellular matrix contractility of eutopic and ectopic endometrial stromal cells during the tissue remodeling processes associated with decidualization.

DESIGN

The effect of decidualization on the contractile profile of the endometriotic cyst stromal cells and eutopic endometrial stromal cells with or without endometriosis in the three-dimensional collagen gel culture was investigated using laser scanning microscopy, collagen gel contraction assays, and Western blot analysis.

RESULTS

Decidualized ectopic and eutopic endometrial stromal cells in the three-dimensional collagen gel culture mimicked the morphology of decidual tissue in vivo. In vitro decidualization inhibited the contractility of these eutopic and ectopic endometrial stromal cells. Down-regulation of integrin alpha1beta1 and alpha2beta1 expression, suppression of Ras homology A (Rho A), Rho-associated coiled-coil-forming protein kinase (ROCK)-I and ROCK-II expression, inhibition of the differentiation into the myofibroblastic phenotype, and induction of differentiation into epithelioid decidual phenotype were observed in these cells during decidualization.

CONCLUSIONS

It is suggested that the attenuation of eutopic endometrial stromal cell-mediated contractility by decidualization is a novel and integral mechanism of the physiological endometrial tissue remodeling process during menstrual cycles. Although ectopic endometrial stromal cells have enhanced contractile profile, decidualization can attenuate the contractility of these cells. These findings may be one of the action mechanisms by which oral contraceptives and progestins ameliorate endometriosis.

Factor XII gene expression in endometrial stromal cells during decidualisation

Decidualisation of endometrial stromal cells (ESC) is a prerequisite for the implantation of human embryos. Identification of genes that are upregulated or downregulated during decidualisation could lead to a better understanding of the molecular mechanisms involved in this process. In the present study, we examined differences in gene expression between decidualised and non-decidualised cells using microarray analysis and found that Factor XII (FXII) gene expression was upregulated during decidualisation. Furthermore, we also examined the expression of FXII by human ESC before and during pregnancy, as well as its expression by cells that had undergone decidualisation in vitro. Weak expression of FXII mRNA was detected in the non-pregnant endometrium that increased gradually from the proliferative to the secretory endometrium. During pregnancy, FXII mRNA expression was markedly increased in decidualised endometrium. When sex steroids (200 pg mL–1 of 17β-oestradiol and 100 ng mL–1 of progesterone) were used to induce in vitro decidualisation of ESC, the expression of FXII mRNA increased by approximately 25.3-fold compared with that in non-decidualised ESC. Using western blotting, we confirmed the presence of FXII protein (80 kDa) in ESC after in vitro decidualisation. Increased expression of FXII in ESC during decidualisation suggests that the kallikrein–kininogen–kinin system may be activated during the implantation of human embryos.

A distinct cohort of the TGFbeta superfamily members expressed in human endometrium regulate decidualization

BACKGROUND

Successful blastocyst implantation requires the differentiation of human endometrial stromal cells (HESC), a process known as decidualization. Activin A, a transforming growth factor beta (TGFbeta) superfamily member, enhances HESC decidualization and localizes to decidual cells in human endometrium. Other TGFbeta superfamily members, including BMP2, BMP4, BMP7, GDF5, GDF8, GDF11, TGFbetas and Nodal, may also play a role during decidualization. This study aimed to identify these TGFbeta family members in human endometrium, and to determine whether they are involved in human decidualization.

METHODS

Protein localization of TGFbeta family members was examined in secretory phase human endometrium and first trimester decidua by immunohistochemistry. mRNA expression was examined in HESC. Activin inhibitors (Activin-M108A/SB431542) with differing specificities for the other TGFbeta members under consideration were applied during HESC decidualization in vitro. The secretion levels of potential TGFbeta superfamily members were measured during decidualization, and recombinant proteins added to examine their effect.

RESULTS

This study has identified BMP2, BMP4, BMP7, GDF5, GDF8 and GDF11 but not Nodal in secretory phase human endometrium, but only BMP2, GDF5 and TGFbeta1 protein were detected in decidual cells. All ligands except Nodal were expressed by cultured HESC. Both inhibitors significantly reduced decidualization validating the role of activin, but potentially also other TGFbeta members, during decidualization. BMP2 and TGFbeta1 secretion increased during HESC decidualisation and exogenous administration of these proteins significantly enhanced decidualization in vitro.

CONCLUSIONS

Like activin, BMP2 and TGFbeta1 are likely to be involved in HESC decidualization. This is the first study to identify and localize BMP4, BMP7, GDF5, GDF8 and GDF11 in secretory phase human endometrium. Understanding the factors critical for the implantation process is needed for improving fertility and pregnancy outcomes.

Transforming growth factor (TGF)-beta1-induced human endometrial stromal cell decidualization through extracellular signal-regulated kinase and Smad activation in vitro: peroxisome proliferator-activated receptor gamma acts as a negative regulator of TGF-beta1

OBJECTIVE

To investigate the effect of transforming growth factor (TGF)-beta1 on the extracellular signal-regulated kinase (ERK) and Smad pathway and the role of peroxisome proliferator-activated receptor (PPAR)-gamma in cultured human endometrial stromal cells.

DESIGN

Experimental study.

SETTING

Infertility center of a tertiary university hospital. MATERIAL(S): Human endometrial tissues obtained by hysterectomy from patients with conditions other than endometrial diseases.

INTERVENTION(S)

Endometrial stromal cells were cultured under normal laboratory conditions. TGF-beta1, rosiglitazone (PPARgamma agonist), and PD98059 (ERK inhibitor) were added to endometrial stromal cell culture according to experimental purposes.

MAIN OUTCOME MEASURE(S)

Cell count, PRL expression, Smad and ERK phosphorylation, cyclooxygenase (COX)-2 expression, and prostaglandin E(2) (PGE(2)) release.

RESULT(S)

TGF-beta1 inhibited cellular proliferation and induced the expressions of COX-2, PGE(2), and PRL of cultured human endometrial stromal cells. These effects may be mediated by Smad and ERK phosphorylation. Treatment with rosiglitazone, a PPARgamma agonist, reversed the TGF-beta1 effect by antagonizing the activation of ERK and Smad that was induced by TGF-beta1.

CONCLUSION(S)

PPARgamma plays a negative role by directly acting on Smad and ERK phosphorylation in human endometrial cell decidualization that is induced by TGF-beta1 in vitro.

Facilitation of decidualization by locally produced ghrelin in the human endometrium

Ghrelin acting via the growth hormone secretagogue receptor (GHS-R) stimulates GH secretion from pituitary glands. Both ligand and receptor are present in the pituitary, hypothalamus and many peripheral tissues including the uterus. This study demonstrates the cyclical expression of GHS-R and ghrelin in human endometrium. mRNA and protein for ghrelin and GHS-R were examined using RT-PCR and immunohistochemistry. Both ghrelin and GHS-R mRNA levels were highest in the secretory phase, with lower levels in the mid-proliferative phase and even lower expression in the menstrual phase. Immunoreactive ghrelin and GHS-R were confined predominantly to glandular epithelial and stromal cells with the greatest intensity of staining in secretory phase samples, consistent with the RT-PCR data. Additionally, we examined ghrelins effect on the decidualization of human endometrial stromal cells (HESCs) combined with sex steroid and cAMP treatments using prolactin (PRL) and insulin-like growth factor binding protein-1 (IGFBP-1) production as markers of decidualization. Ghrelin administered in combination with sex steroids to HESC, resulted in an increase in PRL and IGFBP-1 production above that obtained with cAMP, or sex steroids alone (P<0.001) whereas ghrelin in combination with cAMP inhibits the action of cAMP. These findings have potential clinical applications for the regulation of fertility.

A uterine decidual cell cytokine ensures pregnancy-dependent adaptations to a physiological stressor

In the mouse, decidual cells differentiate from uterine stromal cells in response to steroid hormones and signals arising from the embryo. Decidual cells are crucially involved in creating the intrauterine environment conducive to embryonic development. Among their many functions is the production of cytokines related to prolactin (PRL), including decidual prolactin-related protein (DPRP). DPRP is a heparin-binding cytokine, which is abundantly expressed in uterine decidua. In this investigation, we have isolated the mouse Dprp gene, characterized its structure and evaluated its biological role. Dprp-null mice were made by replacing exons 2 to 6 of the Dprp gene with an in-frame enhanced green fluorescent protein (EGFP) gene and a neomycin (neo) resistance cassette. Heterozygous intercross breeding of the mutant mice yielded the expected mendelian ratio. Pregnant heterozygote females expressed EGFP within decidual tissue in locations identical to endogenous Dprp mRNA and protein expression. Homozygous Dprp-null mutant male and female mice were viable, exhibited normal postnatal growth rates, were fertile and produced normal litter sizes. A prominent phenotype was observed when pregnant Dprp-null mice were exposed to a physiological stressor. DPRP deficiency interfered with pregnancy-dependent adaptations to hypoxia resulting in pregnancy failure. Termination of pregnancy was associated with aberrations in mesometrial decidual cells, mesometrial vascular integrity, and disruptions in chorioallantoic placenta morphogenesis. The observations suggest that DPRP participates in pregnancy-dependent adaptations to a physiological stressor.

Interleukin 11 signaling components signal transducer and activator of transcription 3 (STAT3) and suppressor of cytokine signaling 3 (SOCS3) regulate human endometrial stromal cell differentiation

The differentiation of endometrial stromal cells into decidual cells (decidualization) is critical for embryo implantation, but the mechanisms remain poorly defined. Numerous paracrine agents including IL-11 promote human endometrial stromal cell (HESC) decidualization. IL-11 signaling is transduced by the signal transducers and activators of transcription (STAT) proteins. Suppressors of cytokine signaling (SOCS) proteins are stimulated in response to cytokine-inducible STAT phosphorylation, acting in a negative-feedback mechanism to hinder cytokine receptor activity. This study examined the role of IL-11 signal transduction components in HESC decidualization in an ex vivo model. Cells were induced to differentiate with estrogen plus medroxyprogesterone acetate (E+P) or cAMP (assessed by prolactin secretion) and resulted in increased STAT3 and SOCS3. E+P maximally stimulated STAT3, whereas cAMP maximally stimulated SOCS3 during decidualization, suggesting E+P and cAMP differentially regulated the signaling components. IL-11 stimulated the phosphorylation (p) of STAT3 and SOCS3 mRNA and protein. Antiprogestin (onapristone) added to decidualizing cells attenuated STAT3 protein but increased SOCS3 mRNA and protein, suggesting regulation via both ligand-dependent and -independent progesterone-receptor pathways. SOCS3 overexpression in HESC reduced IL-11-induced pSTAT3 and retarded decidualization, indicating that SOCS3 is a critical regulator of differentiation. Immunoreactive pSTAT3 and SOCS3 were all present in decidualized stromal cells, epithelial cells, and leukocytes in human endometrium. These data support a role for IL-11 via pSTAT3 and SOCS3 in initiating and progressing decidualization.

Stromal cells from endometriotic lesions and endometrium from women with endometriosis have reduced decidualization capacity

OBJECTIVE

To evaluate the phenotype, proliferative, and differentiation capacities in vitro of stromal cells derived from peritoneal, ovarian, and deeply infiltrating endometriosis.

DESIGN

Experimental study using phase contrast microscopy, immunocytochemistry, and functional bioassays.

SETTING

University-based laboratory.

PATIENT(S)

Women with and without endometriosis undergoing surgery for benign indications.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The stability in vitro of stromal cells derived from peritoneal (n = 18), ovarian (n = 29), and deeply infiltrating (n = 14) endometriotic lesions, as well as endometrium from women with (n = 5) and without endometriosis (n = 5) was evaluated by detection of endometrial markers. The proliferative and differentiation capacity of the cells was assessed by the use of cell doubling estimation and in vitro decidualization assays.

RESULT(S)

The expression of the progesterone receptor and CD10 in stromal cells derived from the three types of endometriotic lesions is retained in culture up to passage 10. The doubling time of stromal cells from deeply infiltrating lesions is lower than that of endometrial stromal cells. Levels of prolactin and insulin-like growth factor binding protein-1 (IGFBP-1) are reduced in supernatants from stromal cells derived from the three types of lesions and from the endometrium of women with endometriosis.

CONCLUSION(S)

The peritoneal, ovarian, and deeply infiltrating endometriotic stromal cell lines we describe retain in vivo tissue markers. Loss of differentiation capacity of the endometriotic cell lines and endometrial cells from women with endometriosis may influence the capacity for proliferation and survival of these cells in the ectopic environment.

Progesterone-dependent release of transforming growth factor-beta1 from epithelial cells enhances the endometrial decidualization by turning on the Smad signalling in stromal cells

Endometrial decidualization results from the differentiation of stromal cells in an ovarian steroid-sensitive manner. Human endometrial tissues obtained from fertile women at various stages of the menstrual cycle were subjected to immunohistochemistry to localize the components of the transforming growth factor-beta (TGF-beta) system. TGF-beta receptor-I and -II expression was higher in stromal cells than in epithelial cells during the secretory phase while no such variation was observed during the proliferative phase. The expression of phosphorylated Smad3 (pSmad2/3), an activated form of a component of the TGF-beta signalling pathway, and translocation of pSmad2/3 from the cytoplasm to the nucleus were more pronounced in secretory endometrium. In coculture of human endometrial epithelial with stromal cells, each isolated from the proliferative endometrium, administration of progesterone stimulated decidualization as well as TGF-beta signalling activation in stromal cells. Progesterone also significantly elevated the concentration of TGF-beta1 in the coculture medium. Careful manipulation of the coculture, i.e. selective addition and omission of the cellular components, showed that this progesterone-induced increase in secretion of TGF-beta1 come mainly from epithelial cells. Moreover, administration of TGF-beta1 (10 ng/ml) directly to cultured stromal cells enhanced the expression of prolactin as well as pSamd2/3 even without progesterone. Taken together, our present data support the notion that progesterone induces stromal decidualization indirectly, i.e. by enhancing the expression and secretion of TGF-beta1 from epithelial cells. The secreted, epithelial-derived TGF-beta1 then acts on adjacent stromal cells, at least in part, to turn on Smad signalling that could lead to stromal decidualization.

Antiprogestins as a model for progesterone withdrawal

The key physiological function of the endometrium is preparation for implantation; and in the absence of pregnancy, menstruation and repair. The withdrawal of progesterone is the initiating factor for breakdown of the endometrium. The modulation of sex steroid expression and function with pharmacological agents has provided an invaluable tool for studying the functional responses of the endometrium to sex steroids and their withdrawal. By administration of the antiprogestin mifepristone, it is possible to mimic progesterone withdrawal and study local events in early pregnancy decidua that may play a role in the process of early pregnancy failure. Our data indicate that antagonism of progesterone action at the receptor level results in an up-regulation of key local inflammatory mediators, including NF-kappaB, interleukin-8 (IL-8), monocyte chemotactic peptide-1 (MCP-1), cyclooxygenase 2 (COX-2) and others in decidua. Bleeding induced by mifepristone in the mid-luteal phase of the cycle is associated with changes in the endometrium similar to those that precede spontaneous menstruation including up-regulation of COX-2 and down-regulation of PGDH. Administration of antagonists of progesterone provide an excellent model to study the mechanisms involved in spontaneous and induced abortion as well as providing information which may help devise strategies for treating breakthrough bleeding associated with hormonal contraception.

Ghrelin is involved in the decidualization of human endometrial stromal cells

Successful implantation involves a complex interaction between the endometrium and the embryo. It is well known that several neuropeptides are expressed in the endometrium and placenta during embryonal implantation, suggesting an important role as chemical mediators of the feto-maternal relationship. Ghrelin has recently been identified as the endogenous ligand for the GH secretagogue receptor. Ghrelin is a peptide hormone with many physiological functions, and its expression in the human placenta has been reported. To investigate the involvement of ghrelin in embryonal implantation, we assessed the spatio-temporal expression pattern of ghrelin and its receptor in the human endometrium and placenta through the normal menstrual cycle and in early pregnancy. We also examined the effect of ghrelin on the decidualization of endometrial stromal cells (ESC). Weak expression of ghrelin mRNA was detected in the nonpregnant endometrium, and it was dramatically increased in the decidualized endometrium. A GH secretagogue receptor mRNA was detected in the endometrium throughout the normal menstrual cycle and in early pregnancy, but not in the first trimester placenta. Immunohistochemical analysis using an antighrelin antibody revealed strong signals in decidual cells and extravillous trophoblast cells. Coculture with first trimester placenta up-regulated ghrelin mRNA expression by primary cultured ESC, although sex steroids and 8-bromo-cAMP had no effect. In addition, ghrelin enhanced the decidualization of ESC induced by 8-bromo-cAMP (8-Br-cAMP) in vitro. Thus, ghrelin is a novel paracrine/autocrine factor that is involved in cross-talk between the endometrium and embryo during embryonal implantation.

Potential roles for endometrial inhibins, activins and follistatin during human embryo implantation and early pregnancy

The human endometrium is a remarkably dynamic tissue, undergoing cycles of proliferation, differentiation and breakdown every 28 days. In preparation for embryo implantation, the endometrium differentiates or decidualizes, involving widespread morphological and functional differentiation of endometrial stromal cells. If pregnancy occurs, the decidua regulates trophoblast invasion and forms the maternal component of the placenta. Uterine remodeling has long been known to be regulated by the ovarian steroid hormones 17beta-estradiol and progesterone; however, only recently has the importance of paracrine factors in mediating the cellular and biochemical changes been recognized. Many growth factors and cytokines, such as inhibins and activins, whose expression is generally limited to developmental and pathological states, are produced by actively remodeling endometrial cells, and play crucial roles in regulating endometrial cell function. Here, we present evidence for integral roles for the inhibin and activin family in the paracrine regulation of endometrial receptivity, decidualization and implantation.

Quantitative analysis of adhesion molecules on cellular constituents of the human uterine microenvironment under the influence of estrogen and progesterone

The uterus contains all the components of a tertiary lymphoid compartment. We hypothesize that specific leukocyte recruitment to the endometrium during the secretory phase of the menstrual cycle and early pregnancy limits the type of immunocyte that gains access. The present study utilized flow cytometry to define and quantify adhesion molecules possibly used by decidual infiltrating lymphocytes (DIL) as homing receptors, uterine microvascular myometrial endothelial cells (UtMVE-Myo) as addressins, and secretory endometrial stroma cells (STO) as retainment factors. Human umbilical cord vein endothelial cells and peripheral blood lymphocytes were used as control cells for comparison studies. DIL were composed of predominantly lymphocyte function-associated antigen (LFA)-1+, intercellular adhesion molecule (ICAM)-1+, LFA-2+, LFA-3+, gp150,95+, alpha1beta1+, Hermes cell adhesion molecule (H-CAM)+, and neural cell adhesion molecule (N-CAM)+ (CD56(bright)) memory/effector natural killer cells. A significant number of UtMVEC-Myo expressed platelet endothelial cell adhesion molecule (PECAM)-1, a percentage were uniquely LFA-3+, and alpha4 integrin expression was uniquely high. An increased number of STO uniquely expressed alpha3, beta3, and LFA-3, whereas alpha2, alpha4, alphaVbeta3, and H-CAM were significantly increased. Possible unique adhesions of DIL:UtMVEC-Myo included SLe(x):PECAM, vascular cell adhesion molecule-1:alpha4, and LFA-2:LFA-3, whereas DIL:STO included LFA-2:LFA-3 and N-CAM:N-CAM. Unique molecules on DIL may also associate with extracellular matrix (ECM) or complement on UtMVEC-Myo or STO to form gp150,95:fibrinogen/iC3b/C3dg, alpha1beta1:laminin (LM)/collagen (CO), and ICAM-1:fibronectin (FN) interactions. Bridges of ECM may also form between DIL and UtMVEC-Myo adhesion molecules including ICAM-1:FN:ICAM-1 and alpha4beta1:FN:alpha4beta1. DIL:ECM:STO interactions may involve alpha2beta1:CO:alpha2beta1, alpha3beta1:LM/CO/FN:alpha3beta1, alphaVbeta3:VN:alphaVbeta3, and H-CAM:hyaluronate:H-CAM. It is likely that many adhesion molecules play a role in the recruitment and retainment of specialized lymphocytes within the uterine microenvironment. (Mackay et al., 1990).

IL-15 regulation in human endometrial stromal cells

A greater knowledge of IL-5 regulation within human endometrium is important in understanding key reproductive events and uterine Natural Killer cell function. In the present study, expression of IL-15 mRNA was shown to be up-regulated by both PGE(2) and IFN-gamma in cultures of human endometrial stromal cells (ESC). Release of IL-15 protein was also shown to be under the control of PGE(2) and IFN-gamma using an enzyme-linked immunosorbent assay for IL-15. In addition, 8-Bromo cAMP was able to increase IL-15 release from ESCs (P < 0.005) implying the actions of PGE(2) may be via this second messenger. Addition of a progestin appeared to enhance these effects. Real-time quantitative PCR has demonstrated an up-regulation in IL-15 mRNA expression in the late secretory phase of the menstrual cycle (P < 0.005) and a progressive rise in IFN-gamma expression throughout the secretory phase and into first trimester decidua. These results suggest that IL-15 regulation in the human endometrium is complex and that hormonal control may be indirect.

Temporal relationships among uterine pituitary adenylate cyclase-activating polypeptide, decidual prolactin-related protein and progesterone receptor mRNAs expressions during decidualization and gestation in rats

Pituitary adenylate cyclase-activating peptide (PACAP), a novel compound with vasoactive intestinal polypeptide-like activity, was recently shown to be localized in the neuronal endings of the human uterus. The purpose of the present study was to assess the functional presence of PACAP mRNA in the decidual endometrium and its relationship to the expression levels of decidual prolactin-related protein (dPRP) and the progesterone receptor mRNAs during decidualization and pregnancy in Sprague-Dawley rats. PACAP was constitutively and temporally expressed in the decidual endometrium and gravid uterus. The time-dependent correlated expression levels of PACAP, dPRP and the progesterone receptor were induced by the neurogenic reproductive signals, i.e. the vagino-cervical/deciduogenic stimuli of decidualization and by the normal equivalent stimuli of mating/blastocyst implantation of gestation. Correlation among the mRNA expression levels of PACAP, dPRP and the progesterone receptor and the coordinated inhibitory actions of the anti-progesterone (RU-486) suggest that there is also correlated time-dependent steroid regulation of the mRNA levels of PACAP, dPRP and the progesterone receptor in the decidual and pregnant uteri. One possible functional meaning for the time-related localization of endometrial/uterine PACAP could be to facilitate endometrial blood flow and increase the availability of metabolic substrates to the developing deciduoma or embryo. The study demonstrates the potential importance of PACAP expression in the regulation of the maternal feto-placental component and suggests a prominent reproductive role for the neuropeptide in mammalian pregnancy.

Paracrine effects of a uterine agglutinin are mediated via the sialic acids present in the rat uterine endometrium

A 32 kDa estrogen-induced, sialic acid-specific agglutinin (P-SAS) was isolated from rat endometrium in its proestrus stage. To investigate the functional importance of P-SAS in the uterine milieu, specific binding assays were carried out with 125I-labeled P-SAS and different cellular components of the uterus (epithelial, stromal and myometrial cells), that were isolated from different stages of the estrus cycle. The results indicate that although the protein is secreted from the epithelial cells in the estrogenic phase, it binds specifically to the stromal cells, especially to those isolated from the diestrus stage of the estrus cycle. The specific binding, however, is seen to decrease with the progression of pregnancy. Scatchard analysis performed with varying amounts of 125I-P-SAS in the presence of excess cold P-SAS revealed that the binding occurs with a Ka = 1.69 x 10(8) M(-1). As P-SAS binds specifically to sialic acids on the stromal cell surface, further characterization of the sialic acid molecule to which P-SAS binds was carried out by gas liquid chromatography (GLC). The studies revealed that P-SAS preferentially binds to N-glycolylneuraminic acid, which is attached to the penultimate sugar of the stromal cell surface glycoprotein chain via alpha2,6 linkage. As P-SAS is further known to be mitogenic, the effect of P-SAS on cultured stromal cells was studied in vitro. The growth regulatory assays revealed that P-SAS induced 3H-thymidine uptake by stromal cells in culture. Thus, from the above observations, paracrine effects of P-SAS on the stromal cells and on the subsequent growth and development of the uterus can be assumed.

Production and physiological function of granulocyte colony-stimulating factor in non-pregnant human endometrial stromal cells

Effects of granulocyte colony-stimulating factor (G-CSF) on proliferation and differentiation of normal human endometrial stromal cells were investigated in an in vitro decidualization culture of stromal cells. Unstimulated stromal cells secreted little prolactin and G-CSF, whereas 8-Br-cAMP-stimulated stromal cells secreted higher levels. There was no relationship, however, between the levels of prolactin and G-CSF secreted from the stimulated cells. Detectable levels of prolactin secretion were not found in two of six stromal cell cultures stimulated with 8-Br-cAMP; however, these two culture supernatants contained high concentrations of G-CSF. Co-stimulation of the stromal cells with 8-Br-cAMP and G-CSF enhanced prolactin secretion from the stimulated cells in a G-CSF concentration-dependent manner without any change in viable cell numbers. However, G-CSF did not affect prolactin secretion or viable cell numbers of 8-Br-cAMP-stimulated decidualized cells. These results indicate that G-CSF enhances cAMP-mediated decidualization of human endometrial stromal cells in an autocrine or paracrine fashion.

The decidualizing effect of progesterone may involve direct transcriptional activation of corticotrophin-releasing hormone from human endometrial stromal cells

The hypothalamic neuropeptide corticotrophin-releasing hormone (CRH) is also produced by human endometrial cells and is directly involved in the decidualization process as a paracrine inducer. The aim of the present work was to examine the effect of progesterone, the main decidualizing factor, on endometrial CRH, in primary cultures of human endometrial stromal cells. The effect of progesterone was examined by measuring the effects of medroxyprogesterone acetate (MPA) on (i) the concentration of immunoreactive CRH in isolated human endometrial stromal cells and (ii) the activity of the CRH promoter in human endometrial stromal cells transfected with a 0.9 kb fragment of the 5'-flanking region of the human CRH gene coupled to luciferase reporter. The data show that MPA increased the production and secretion of immunoreactive CRH from stromal cells and induced the activity of the CRH promoter, both in a dose-dependent manner. These effects were partially reversed by a molar excess of the antiprogestin RU 486 and were completely abolished in the presence of 100 nmol/l of the cAMP inhibitor, Rp-cAMP. The effect of progesterone on the CRH promoter requires the existence of an intact CRH sequence since experiments carried out with a deleted palindromic cAMP response element (CRE: 5'-TGACGTCA) at -224 bp of the CRH promoter resulted in a complete loss of MPA effect. In conclusion, these data provide evidence that progesterone induces the transcription of CRH gene in human endometrial stroma. This effect coupled with the decidualizing properties of progesterone and CRH may indicate that progesterone and CRH form a decidualizing local pathway within the human endometrium.

Human endometrial cancers contain follicle-stimulating hormone receptors: a preliminary study

In order to investigate whether human endometrial cancers contain follicle-stimulating hormone (FSH) receptors, cancer fragments were collected at hysterectomy in six post-menopausal women affected by histologically confirmed endometrial malignancy. Cryostat sections were prepared for in situ binding investigation. Positive endometrial glandular cells were registered in all cancers; 125I-FSH binding sites seemed to increase with the increasing tumor grade. Our data demonstrated for the first time that human endometrial cancers contain specific FSH receptors.

Corticotropin releasing factor decidualizes human endometrial stromal cells in vitro. Interaction with progestin

Decidualization of endometrial cells is a hormone-dependent process of differentiation which occurs during the menstrual cycle and pregnancy. Recent in vitro studies have revealed that cAMP and its generators induce decidualization of stromal cells isolated from proliferative endometrium and that progestins enhance the effect of cAMP. Since corticotropin releasing factor (CRF) generates cAMP and prostaglandins in other organs, in the present study the effect of CRF, a hypothalamic factor also produced by decidua and fetal membranes, on in vitro decidualization of endometrial stromal cells was evaluated. The addition of CRF to a culture medium of stromal cells induced in vitro decidualization, as indicated by morphologic changes from elongated fibroblast-like cells into larger and round cells and by the release of prolactin in the medium. The effect of CRF on stromal cells and on prolactin release was significantly augmented by the coincubation in the presence of medroxyprogesterone acetate. This observation indicates CRF as a novel factor of decidualization and confirms that progestins act as enhancers of the expression of decidual products.