The proliferative phase endometrium in IVF/ICSI: an in-cycle molecular analysis predictive of the outcome following fresh embryo transfer.

STUDY QUESTION: Does an early proliferative phase endometrial biopsy harvested during ovarian stimulation harbour information predictive of the outcome following fresh embryo transfer (ET) in that same cycle? SUMMARY ANSWER: Transcriptome analysis of the whole-tissue endometrium did not reveal significant differential gene expression (DGE) in relation to the outcome; however, the secretome profile of isolated, cultured and in vitro decidualized endometrial stromal cells (EnSCs) varied significantly between patients who had a live birth compared to those with an implantation failure following fresh ET in the same cycle as the biopsy. WHAT IS KNOWN ALREADY: In the majority of endometrial receptivity research protocols, biopsies are harvested during the window of implantation (WOI). This, however, precludes ET in that same cycle, which is preferable as the endometrium has been shown to adapt over time. Endometrial biopsies taken during ovarian stimulation have been reported not to harm the chances of implantation, and in such biopsies DGE has been observed between women who achieve pregnancy versus those who do not. The impact of the endometrial proliferative phase on human embryo implantation remains unclear, but deserves further attention, especially since in luteal phase endometrial biopsies, a transcriptional signature predictive for repeated implantation failure has been associated with reduced cell proliferation, possibly indicating proliferative phase involvement. Isolation, culture and in vitro decidualization (IVD) of EnSCs is a frequently applied basic research technique to assess endometrial functioning, and a disordered EnSC secretome has previously been linked with failed implantation. STUDY DESIGN, SIZE, DURATION: This study was nested in a randomized controlled trial (RCT) investigating the effect of endometrial scratching during the early follicular phase of ovarian stimulation on clinical pregnancy rates after IVF/ICSI. Of the 96 endometrial biopsies available, after eliminating those without fresh ET and after extensive matching in order to minimize the risk of potential confounding, 18 samples were retained to study two clinical groups: nine biopsies of patients with a live birth versus nine biopsies of patients with an implantation failure, both following fresh ET performed in the same cycle as the biopsy. We studied the proliferative endometrium by analysing its transcriptome and by isolating, culturing and decidualizing EnSCs in vitro. We applied this latter technique for the first time on proliferative endometrial biopsies obtained during ovarian stimulation for in-cycle outcome prediction, in an attempt to overcome inter-cycle variability. PARTICIPANTS/MATERIALS, SETTING, METHODS: RNA-sequencing was performed for 18 individual whole-tissue endometrial biopsies on an Illumina HiSeq1500 machine. DGE was analysed three times using different approaches (DESeq2, EdgeR and the Wilcoxon rank-sum test, all in R). EnSC isolation and IVD was performed (for 2 and 4 days) for a subset of nine samples, after which media from undifferentiated and decidualized cultures were harvested, stored at -80°C and later assayed for 45 cytokines using a multiplex suspension bead immunoassay. The analysis was performed by partial least squares regression modelling. MAIN RESULTS AND THE ROLE OF CHANCE: After correction for multiple hypothesis testing, DGE analysis revealed no significant differences between endometrial samples from patients who had a live birth and those with an implantation failure following fresh ET. However secretome analysis after EnSC isolation and culture, showed two distinct clusters that clearly corresponded to the two clinical groups. Upon IVD, the secretome profiles shifted from that of undifferentiated cells but the difference between the two clinical groups remained yet were muted, suggesting convergence of cytokine profiles after decidualization. LIMITATIONS, REASONS FOR CAUTION: Caution is warranted due to the limited sample size of the study and the in vitro nature of the EnSC experiment. Validation on a larger scale is necessary, however, hard to fulfil given the very limited availability of in-cycle proliferative endometrial biopsies outside a RCT setting. WIDER IMPLICATIONS OF THE FINDINGS: These data support the hypothesis that the endometrium should be assessed not only during the WOI and that certain endometrial dysfunctionalities can probably be detected early in a cycle by making use of the proliferative phase. This insight opens new horizons for the development of endometrial tests, whether diagnostic or predictive of IVF/ICSI treatment outcome. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by Fonds Wetenschappelijk Onderzoek (FWO, Flanders, Belgium, 11M9415N, 1 524 417N), Wetenschappelijk Fonds Willy Gepts (WFWG G160, Universitair Ziekenhuis Brussel, Belgium) and the National Medicine Research Council (NMRC/CG/M003/2017, Singapore). There are no conflicts of interests. TRIAL REGISTRATION NUMBER: NCT02061228.

Expression of adhesion and extracellular matrix genes in human blastocysts upon attachment in a 2D co-culture system.

STUDY QUESTION: What are the changes in human embryos, in terms of morphology and gene expression, upon attachment to endometrial epithelial cells? SUMMARY ANSWER: Apposition and adhesion of human blastocysts to endometrial epithelial cells are predominantly initiated at the embryonic pole and these steps are associated with changes in expression of adhesion and extracellular matrix (ECM) genes in the embryo. WHAT IS KNOWN ALREADY: Both human and murine embryos have been co-cultured with Ishikawa cells, although embryonic gene expression associated with attachment has not yet been investigated in an in vitro implantation model. STUDY DESIGN, SIZE, DURATION: Vitrified human blastocysts were warmed and co-cultured for up to 48 h with Ishikawa cells, a model cell line for receptive endometrial epithelium. PARTICIPANTS/MATERIALS, SETTING, METHODS: Six days post-fertilization (6dpf) human embryos were co-cultured with Ishikawa cells for 12, 24 (7dpf) or 48 h (8dpf) and attachment rate and morphological development investigated. Expression of 84 adhesion and ECM genes was analysed by quantitative PCR. Immunofluorescence microscopy was used to assess the expression of three informative genes at the protein level. Data are reported on 145 human embryos. Mann-Whitney U was used for statistical analysis between two groups, with P < 0.05 considered significant. MAIN RESULTS AND THE ROLE OF CHANCE: The majority of embryos attached to Ishikawa cells at the level of the polar trophectoderm; 41% of co-cultured embryos were loosely attached after 12 h and 86% firmly attached after 24 h. Outgrowth of hCG-positive embryonic cells at 8dpf indicated differentiation of trophectoderm into invasive syncytiotrophoblast. Gene expression analysis was performed on loosely attached and unattached embryos co-cultured with Ishikawa cells for 12 h. In contrast to unattached embryos, loosely attached embryos expressed THBS1, TNC, COL12A1, CTNND2, ITGA3, ITGAV and LAMA3 and had significantly higher CD44 and TIMP1 transcript levels (P = 0.014 and P = 0.029, respectively). LAMA3, THBS1 and TNC expressions were validated at the protein level in firmly attached 7dpf embryos. Thrombospondin 1 (THBS1) resided in the cytoplasm of embryonic cells whereas laminin subunit alpha 3 (LAMA3) and tenascin C (TNC) were expressed on the cell surface of trophectoderm cells. Incubation with a neutralizing TNC antibody did not affect the rate of embryo attachment or hCG secretion. LARGE SCALE DATA: None. LIMITATIONS, REASONS FOR CAUTION: This in vitro study made use of an endometrial adenocarcinoma cell line to mimic receptive luminal epithelium. Also, the number of embryos was limited. Contamination of recovered embryos with Ishikawa cells was unlikely based on their differential gene expression profiles. WIDER IMPLICATIONS OF THE FINDINGS: Taken together, we provide a 'proof of concept' that initiation of the implantation process coincides with the induction of specific embryonic genes. Genome-wide expression profiling of a larger sample set may provide insights into the molecular embryonic pathways underlying successful or failed implantation. STUDY FUNDING AND COMPETING INTEREST(S): A.A. was supported by a grant from the 'Instituut voor Innovatie door Wetenschap en Technologie' (IWT, 121716, Flanders, Belgium). This work was supported by the 'Wetenschappelijk Fonds Willy Gepts' (WFWG G142 and G170, Universitair Ziekenhuis Brussel). The authors declare no conflict of interest.

Potential role of endometrial stem/progenitor cells in the pathogenesis of early-onset endometriosis.

The pathogenesis of early-onset endometriosis has recently been revisited, sparked by the discovery of endometrial stem/progenitor cells and their possible role in endometriosis, and because maternal pregnancy hormone withdrawal following delivery induces uterine bleeding in the neonate. The neonatal uterus has a large cervix to corpus ratio which is functionally blocked with mucous, supporting the concept of retrograde shedding of neonatal endometrium. Only 5% show overt bleeding. Furthermore, the presence of endometriosis in pre-menarcheal girls and even in severe stage in adolescents supports the theory that early-onset endometriosis may originate from retrograde uterine bleeding soon after birth. Endometrial stem/progenitor cells have been identified in menstrual blood suggesting that they may also be shed during neonatal uterine bleeding. Thus, we hypothesized that stem/progenitor cells present in shedding endometrium may have a role in the pathogenesis of early-onset endometriosis through retrograde neonatal uterine bleeding. During the neonatal and pre-pubertal period, shed endometrial stem/progenitor cells are postulated to survive in the pelvic cavity in the absence of circulating estrogens supported by niche cells also shed during neonatal uterine bleeding. According to this hypothesis, during thelarche, under the influence of rising estrogen levels, endometrial stem/progenitor cells proliferate and establish ectopic endometrial lesions characteristic of endometriosis. This New Research Horizon review builds on recent discussions on the pathogenesis of early-onset endometriosis and raises new avenues for research into this costly condition.

TGFß1 and SGK1-sensitive store-operated Ca2+ entry and Orai1 expression in endometrial Ishikawa cells.

The serum-and-glucocorticoid-inducible-kinase-1 (SGK1) is ubiquitously expressed and under genomic control by cell stress, hormones and further mediators. A most powerful stimulator of SGK1 expression is transforming growth factor TGFß1. SGK1 is activated by insulin and growth factors via phosphatidylinositol-3-kinase and the 3-phosphoinositide-dependent kinase PDK1. As shown recently, SGK1 increases the store-operated Ca(2+) entry (SOCE), which is accomplished by the pore-forming ion channel unit Orai. Most recent observations further revealed that SGK1 plays a critical role in the regulation of fertility. SGK1 is up-regulated in the luminal epithelium of women with unexplained infertility but down-regulated in decidualizing stromal cells of patients with recurrent pregnancy loss. The present study explored whether Orai1 is expressed in endometrium and sensitive to regulation by SGK1 and/or TGFß1. To this end, Orai1 protein abundance was determined by western blotting and SOCE by fura-2 fluorescence. As a result, Orai1 was expressed in human endometrium and in human endometrial Ishikawa cells. Orai1 expression and SOCE in Ishikawa cells were increased by transfection with constitutively active (S422D)SGK1 but not by transfection with inactive (K127N)SGK1. The difference of SOCE between (S422D)SGK1 and (K127N)SGK1-transfected cells was virtually abrogated in the presence of Orai1 inhibitor 2-aminoethoxydiphenyl borate (2-APB, 50 µM). Similar to (S422D)SGK1 transfection TGFß1 treatment up-regulated both Orai1 protein abundance and SOCE. In conclusion, Orai1 is expressed in the human endometrium and is up-regulated by SGK1 and TGFß1. The present observations thus uncover a novel element in SGK1-sensitive regulation of endometrial cells.

Interventions to improve reproductive outcomes in women with elevated natural killer cells undergoing assisted reproduction techniques: a systematic review of literature.

STUDY QUESTION: Is there any scientific evidence to support the routine use of adjuvant therapies for women with elevated natural killer (NK) cells undergoing assisted reproduction techniques (ARTs) in order to improve live birth rate? SUMMARY ANSWER: Due to the poor quality evidence, this review does not support the use of described adjuvant treatments in women found to have elevated absolute numbers or activity of NK cells undergoing ART. WHAT IS KNOWN ALREADY: Deregulation in the numbers of NK cells and/or their activity, in the blood as well as in the endometrium, has been associated with various manifestations of reproductive failure. NK cell analysis is becoming increasingly popular as a test offered to investigate the causes of reproductive failure. Adjuvant therapies influencing the NK cells have been postulated as therapeutic options for couples where deregulation of this component of the maternal immune system is suspected as the cause of infertility or implantation failure. STUDY DESIGN, SIZE, DURATION: Systematic review. Embase, LILACS, MEDLINE, PsycINFO, CENTRAL and CINAHL databases from 1946 to present were searched with no language restrictions. PARTICIPANTS/MATERIALS, SETTING, METHODS: Studies evaluating the use of adjuvant therapies in women undergoing ART where NK cell numbers and/or activity were assessed were considered eligible for inclusion. MAIN RESULTS AND THE ROLE OF CHANCE: Only three studies (one in abstract form only) meeting the inclusion criteria were identified: two reported the use of intravenous immunoglobulins (IVIg) and one the use of oral prednisolone. All studies demonstrated a beneficial effect of the interventions on clinical pregnancy rates with a risk ratio (RR) of 1.63 [95% confidence interval (CI) 1.00-2.66] for prednisolone and 3.41 (95%CI 1.90-6.11) for IVIg. Studies assessing the efficacy of IVIg have also reported live birth rate with an RR of 3.94 (95% CI 2.01-7.69) favoring the intervention. Data heterogeneity was substantial however (I(2) = 66%) suggesting a cautious interpretation of the results. LIMITATIONS, REASONS FOR CAUTION: Differing study populations, lack of statistical power, method of data presentation (per couple or per cycle), the use of additional medications and differing dosage regimes contribute to data heterogeneity and suggest a cautious approach to data interpretation. WIDER IMPLICATIONS OF THE FINDINGS: This review identified some data showing that adjuvant therapies (mainly IVIg) in this selected population seem to confer some benefit on ART outcome. However, overall, the review does not support the use of prednisolone, IVIg or any other adjuvant treatment in women undergoing ART who are found to have elevated absolute numbers or activity of NK cells, purely due to the paucity of, or poor quality of, the evidence. Agreement as to the most reliable NK cell testing method must be made by the scientific community as well as 'normal' NK cell levels unequivocally defined. Well designed, sufficiently powered RCTs with an appropriate population selection and using the same NK cell testing methodology are required to ascertain the actual benefit of using adjuvant therapy treatment for elevated NK cell levels or activity in the context of pregnancy outcome following IVF. STUDY FUNDING/COMPETING INTEREST(S): None.

Molecular aspects of implantation failure.

Despite expanding global experience with advanced reproductive technologies, the majority of IVF attempts do not result in a successful pregnancy, foremost as a result of implantation failure. The process of embryo implantation, a remarkably dynamic and precisely controlled molecular and cellular event, appears inefficient in humans and is poorly understood. However, insights gained from clinical implantation failure, early pregnancy loss, and emerging techologies that enable molecular interrogation of endometrial-embryo interactions are unravelling this major limiting step in human reproduction. We review current molecular concepts thought to underlie implantation failure, consider the contribution of embryonic and endometrial factors, and discuss the clinical value of putative markers of impaired endometrial receptivity. Finally we highlight the nature of the dialogue between the maternal endometrium and the implanting embryo and discuss the concept of natural embryo selection. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

Ultrasound assessment of the peri-implantation uterus: a review.

Emerging evidence suggests that early embryo implantation is a more active maternal process than hitherto appreciated, involving active encapsulation of the implanting blastocyst by maternal decidual cells and coordinated changes in the underlying inner myometrium, known as the junctional zone. These concepts raise the possibility that early ultrasound markers predictive of adverse pregnancy outcome could be identified. In this review we assess the role of ultrasound in predicting the likelihood of different pregnancy outcomes and highlight potential novel markers that could be tested.

Expression and function of the luteinizing hormone choriogonadotropin receptor in human endometrial stromal cells.

The human luteinising hormone choriogonadotropin receptor (LHCGR) is a G-protein coupled receptor activated by both human chorionic gonadotropin (hCG) and luteinizing hormone (LH), two structurally related gonadotropins with essential roles in ovulation and maintenance of the corpus luteum. LHCGR expression predominates in ovarian tissues where it elicits functional responses through cyclic adenosine mononucleotide (cAMP), Ca2+ and extracellular signal-regulated kinase (ERK) signalling. LHCGR expression has also been localized to the human endometrium, with purported roles in decidualization and implantation. However, these observations are contentious. In this investigation, transcripts encoding LHCGR were undetectable in bulk RNA sequencing datasets from whole cycling endometrial tissue and cultured human endometrial stromal cells (EnSC). However, analysis of single-cell RNA sequencing data revealed cell-to-cell transcriptional heterogeneity, and we identified a small subpopulation of stromal cells with detectable LHCGR transcripts. In HEK-293 cells expressing recombinant LHCGR, both hCG and LH elicited robust cAMP, Ca2+ and ERK signals that were absent in wild-type HEK-293 cells. However, none of these responses were recapitulated in primary EnSC cultures. In addition, proliferation, viability and decidual transformation of EnSC were refractory to both hCG and LH, irrespective of treatment to induce differentiation. Although we challenge the assertion that LHCGR is expressed at a functionally active level in the human endometrium, the discovery of a discrete subpopulation of EnSC that express LHCGR transcripts may plausibly account for the conflicting evidence in the literature.

Correction: FOXO3a represses VEGF expression through FOXM1-dependent and -independent mechanisms in breast cancer.

In the published version of this article, the images for cytoplasmic and nuclear FGF7 in MDA-MB-231 cells were duplicated and mistaken for total FGF7 in SKBR-3 and MDA-MB-231 cells.

Inhibition of steroid sulphatase activity in endometriotic implants by 667 COUMATE: a potential new therapy.

BACKGROUND: Local biosynthesis of estrogens is thought to be important for the maintenance and growth of endometriotic implants. In addition to the formation of estrogen via the aromatase pathway, steroid sulphatase (STS), which is responsible for the hydrolysis of estrogen sulphates, may be an important source of estrogens in endometriosis. METHODS: Eutopic and ectopic endometrial samples from 14 women with minimal or mild (MM) endometriosis and from 13 women with moderate to severe (MS) endometriosis were analysed for aromatase and STS activities. RESULTS: Aromatase and STS activity were detected in all samples. STS enzyme activity in both eutopic and ectopic endometrium was considerably higher and less variable than aromatase activity. Moreover, STS, but not aromatase, activity in endometriotic implants correlated with the severity of the disease (mean +/- SEM: 203 +/- 38 nmol/4 h/g wet weight tissue in MM disease versus 423 +/- 44 nmol/4 h/g wet weight tissue in MS endometriosis, P < 0.001). The STS inhibitor 667 COUMATE almost completely blocked STS activity (>99%) in both eutopic and ectopic tissues. CONCLUSIONS: The high levels of STS activity detected in ectopic endometrium and the correlation with severity of disease suggest that STS inhibitors could be useful for the treatment of endometriosis.

Inhibition of steroid sulfatase activity in endometriotic implants by STX64 (667Coumate): a potential new therapy.

Endometriosis is a common and debilitating condition of women in their reproductive age that is associated with pain and infertility. Current medical treatments are only partially effective and associated with wide-ranging side effects. New understanding of local estrogen production by endometriotic tissue and the availability of powerful suppressing drugs may herald a new era in the treatment of this condition.

An altered endometrial CD8 tissue resident memory T cell population in recurrent miscarriage.

When trying to conceive 1% of couples have recurrent miscarriages, defined as three or more consecutive pregnancy losses. This is not accounted for by the known incidence of chromosomal aneuploidy in miscarriage, and it has been suggested that there is an immunological aetiology. The endometrial mucosa is populated by a variety of immune cells which in addition to providing host pathogen immunity must facilitate pregnancy. Here we characterise the endometrial CD8-T cell population during the embryonic window of implantation and find that the majority of cells are tissue resident memory T cells with high levels of CD69 and CD103 expression, proteins that prevent cells egress. We demonstrate that unexplained recurrent miscarriage is associated with significantly decreased expression of the T-cell co-receptor CD8 and tissue residency marker CD69. These cells differ from those found in control women, with less expression of CD127 indicating a lack of homeostatic cell control through IL-7 signalling. Nevertheless this population is resident in the endometrium of women who have RM, more than three months after the last miscarriage, indicating that the memory CD8-T cell population is altered in RM patients. This is the first evidence of a differing pre-pregnancy phenotype in endometrial immune cells in RM.

Death or survival--progesterone-dependent cell fate decisions in the human endometrial stroma.

The human endometrium undergoes cyclical waves of proliferation, differentiation and apoptosis in response to the rise and fall in ovarian oestradiol and progesterone levels. These hormonal responses in endometrial cells must be tightly kept in check to safeguard tissue homeostasis throughout reproductive life. The discovery that differentiating endometrium highly expresses the tumour suppressor p53, the forkhead transcription factor FOXO1, and promyelocytic leukaemia zinc finger protein (PLZF) has provided new insights into the molecular basis of life and death decisions in response to sex steroid hormones.

Regulated expression of putative membrane progestin receptor homologues in human endometrium and gestational tissues.

Rapid non-genomic actions of progesterone are implicated in many aspects of female reproduction. Recently, three human homologues of the fish membrane progestin receptor (mPR) have been identified. We combined bioinformatic analysis with expression profiling to define further the role of these mPRs in human reproductive tissues. Sequence analysis confirmed that the mPRs belong to a larger, highly conserved family of proteins, termed 'progestin and adiponectin receptors' (PAQRs). A comparison of the expression of mPR transcripts with that of two related PAQR family members, PAQRIII and PAQRIX, in cycling endometrium and pregnancy tissues revealed markedly divergent expression levels and profiles. For instance, endometrial expression of mPRalpha and gamma and PAQRIX was cycle-dependent whereas the onset of parturition was associated with a marked reduction in myometrial mPRalpha and beta transcripts. Interestingly, mPRalpha and PAQRIX were most highly expressed in the placenta, and the tissue expression levels of both genes correlated inversely with that of the nuclear PR. Phylogenetic analysis demonstrated that PAQRIX belongs to the mPR subgroup of proteins. We also validated a polyclonal antibody raised against the carboxy-terminus of human mPRalpha. Immunohistochemical analysis demonstrated more intense immunoreactivity in placental syncytiotrophoblasts than in endometrial glands or stroma. The data suggest important functional roles for mPRalpha, and possibly PAQRIX, in specific reproductive tissues, particularly those that express low levels of nuclear PR.

The perinatal origins of major reproductive disorders in the adolescent: Research avenues.

The fetal endometrium becomes responsive to steroid hormones around the fourth month of pregnancy starting with an oestrogenic phase, which is followed late in pregnancy by a secretory phase. Based on post-mortem studies, the endometrium at birth is secretory in only one-third of neonates and proliferative in the remaining cases. Decidual or menstrual changes are rare in fetal endometrium despite high circulating steroid hormone levels, which drop rapidly after birth. Hence, acquisition of progesterone responsiveness appears to be dependent on endometrial maturation and relative immaturity may persist in a majority of girls until the menarche and early adolescence. Two major reproductive disorders have been linked with either advanced or delayed endometrial maturation. First, early-onset endometriosis may be caused by menstruation-like bleeding in the neonate, leading to tubal reflux and ectopic implantation of endometrial stem/progenitor cells. Second, persistence of partial progesterone resistance in adolescent girls may compromise deep placentation and account for the increased risk of major obstetrical syndromes, including preeclampsia, fetal growth retardation and preterm birth. The concept of neonatal origins of common reproductive disorders poses important research challenges but also subsumes potential new preventative strategies.

Progesterone and the Repression of Myometrial Inflammation: The Roles of MKP-1 and the AP-1 System.

Progesterone (P4) maintains uterine quiescence during pregnancy and its functional withdrawal is associated with increased prostaglandin synthesis and the onset of labor. In primary human myometrial cells, the glucocorticoid receptor (GR) rather than the P4 receptor mediates P4 antagonism of IL-1ß-induced cyclooxygenase-2 (COX-2) expression, the rate-limiting enzyme in prostaglandin synthesis. We now report that P4 also acts via GR to induce MAPK phosphatase (MKP)-1 and knockdown of MKP-1 impairs the ability of P4 to repress IL-1ß-dependent COX-2 induction. Microarray analysis revealed that P4 repressed preferentially activator protein-1-responsive genes in response to IL-1ß. Consistent with these observations, we found that the ability of P4 to reduce c-Jun activation was lost upon GR as well as MKP-1 knockdown. Interestingly, c-Jun levels in human myometrial cells declined upon GR and MKP-1 knockdown, which suggests the presence of an activator protein-1 feedback loop. This is supported by our observation that c-Jun levels declined after an initial rise in primary myometrial cells treated with phorbol 12-myrisatate 13-acetate, a potent activator of c-Jun N-terminal kinase. Finally, we show that MKP-1 is an intermediate in P4-mediated repression of some but not all IL-1ß-responsive genes. For example, P4 repression of IL11 and IRAK3 was maintained upon MKP-1 knockdown. Taken together, the data show that P4 acts via GR to drive MKP-1 expression, which in turn inhibits IL-1ß-dependent c-Jun activation and COX-2 expression.

Progesterone receptor regulates decidual prolactin expression in differentiating human endometrial stromal cells.

Human endometrial stromal (ES) cells in culture express PRL, a marker of decidualization, in response to sustained activation of protein kinase A (PKA). Cotreatment with the progestin medroxyprogesterone acetate (MPA) enhanced decidual PRL gene activation in the presence of elevated intracellular cAMP levels. This synergy became apparent, at protein and promoter level, after a lag period of 2 days and increased in a time-dependent manner thereafter. Pretreatment with cAMP advanced the time at which synergy between cAMP and MPA was apparent, suggesting that PKA activation sensitized ES cells to the effects of progestins. Analysis of the progesterone receptor (PR) indicated that PR-A was the predominant form in differentiating ES cells, but its abundance decreased markedly during the course of the decidualization response. The decline in PR levels was of functional relevance, as expression of PR-B or PR-A, by transient transfection, dramatically inhibited the activity of a decidual PRL promoter-reporter construct in response to cAMP. Furthermore, the expression of endogenous PRL protein in response to cAMP or cAMP plus MPA was substantially decreased by constitutive expression of green fluorescence protein-tagged PR, which was localized in the nucleus even in the absence of added ligand. Ligand-independent PR inhibition of the decidual PRL promoter was receptor specific, independent of known PR phosphorylation sites, and required minimally a functional DNA-binding domain. Transient expression of steroid receptor coactivator-1e (SRC-1e), but not SRC-1a, allowed synergy between cAMP and MPA without the requirement of sensitization by pretreatment with cAMP. This raised the possibility that SRC-1e was a component of cAMP-dependent sensitization of ES cells, but there was no evidence of altered messenger RNA expression of either SRC-1 isoform during decidualization. In conclusion, cellular PR levels determine the onset of the decidualization response. Initiation of this process requires elevated intracellular cAMP levels that sensitize ES cells to the actions of progestins through down-regulation of cellular PR levels and possibly via modulation of function of an intermediate factor(s) such as SRC-1e.

Interferon-gamma modulates prolactin and tissue factor expression in differentiating human endometrial stromal cells.

Cytokines such as interferon-gamma (IFNgamma) released by resident uterine immune cells are thought to influence the expression of differentiated function in the human endometrium. Decidualization of the stromal cell compartment is confined to the superficial endometrial layer in the nonpregnant uterus. To explore the molecular mechanism underlying the spatial expression of the decidual phenotype, the effect of IFNgamma on the induction of two well characterized markers of endometrial stromal (ES) cell differentiation, PRL and tissue factor (TF), has been investigated. IFNgamma antagonizes cAMP-mediated PRL protein and messenger RNA expression in primary ES cell cultures through inhibition of decidual PRL promoter activity. In parallel, IFNgamma stimulates Stat-1 (signal transducer and activator of transcription-1) expression, phosphorylation, and translocation to the nucleus. Exogenously expressed Stat-1 potently represses decidual PRL promoter activation, indicating the potential for the inhibitory effects of IFNgamma to be mediated by Stat-1. We demonstrate that although the coactivator CREB-binding protein/p300 is essential for decidual PRL transcription, this coactivator does not appear to be the target for IFNgamma-mediated repression. By contrast, IFNgamma has little effect on cAMP-mediated TF expression, but induces TF in ES cells not exposed to a decidualizing stimulus. This suggested that in vivo TF expression may not be restricted to decidualizing cells of the superficial layer and was confirmed by immunohistochemical analysis demonstrating intense TF staining in the basal stromal compartment during the regeneration phase of the cycle. The differential sensitivity of decidualization-associated genes to IFNgamma illustrates its potential role as a selective biological response modifier that influences regional function within the endometrium.

Human endometrial fibroblasts immortalized by simian virus 40 large T antigen differentiate in response to a decidualization stimulus.

Human endometrial fibroblasts have been immortalized by infection with simian virus 40 large T antigen and established as a permanent cell line, St-2. Biochemical differentiation of this cell line has been demonstrated by the ability of a decidualizing stimulus, 8-bromo-cAMP plus medroxyprogesterone acetate (MPA), to induce PRL secretion and increase the enzymatic activity of estrone sulfatase. MPA, alone or in combination with estradiol, was unable to elicit this response, but potentiated the effect of 8-bromo-cAMP on PRL production and estrone sulfatase activity. The increase in PRL protein was accompanied by an increase in PRL messenger RNA and increased expression of the insulin-like growth factor-binding protein-1 messenger RNA. The St-2 cell PRL transcript was larger than the pituitary PRL transcript, suggesting its initiation from the distal, nonpituitary, PRL promoter. This was confirmed by reverse transcription-PCR analysis of PRL transcripts using primers specific for the additional sequences present only in the 5'-untranslated region of RNA initiated from the distal promoter. Transient transfection of a reporter construct containing 3000 bp of DNA 5' to the decidual-specific promoter of the human PRL gene demonstrated that cAMP was capable of activating this distal promoter in St-2 cells. In conclusion, this novel cell line provides an interesting new model in which to pursue aspects of biochemical differentiation of human endometrium in vitro.