The effect of various doses of mifepristone on endometrial leukaemia inhibitory factor expression in the midluteal phase--an immunohistochemical study

Alterations in Epithelial Cell Polarity During Endometrial Receptivity: A Systematic Review

BACKGROUND

Abnormal endometrial receptivity is one of the major causes of embryo implantation failure and infertility. The plasma membrane transformation (PMT) describes the collective morphological and molecular alterations occurring to the endometrial luminal epithelium across the mid-secretory phase of the menstrual cycle to facilitate implantation. Dysregulation of this process directly affects endometrial receptivity and implantation. Multiple parallels between these alterations to confer endometrial receptivity in women have been drawn to those seen during the epithelial-mesenchymal transition (EMT) in tumorigenesis. Understanding these similarities and differences will improve our knowledge of implantation biology, and may provide novel therapeutic targets to manage implantation failure.

METHODS

A systematic review was performed using the Medline (Ovid), Embase, and Web of Science databases without additional limits. The search terms used were "(plasma membrane* or cell membrane*) and transformation*" and "endometrium or endometrial." Research studies on the PMT or its regulation in women, discussing either the endometrial epithelium, decidualized stroma, or both, were eligible for inclusion.

RESULTS

A total of 198 articles were identified. Data were extracted from 15 studies that matched the inclusion criteria. Collectively, these included studies confirmed the alterations occurring to the endometrial luminal epithelium during the PMT are similar to those seen during the EMT. Such similarities included alterations to the actin cytoskeleton remodeling of adherens junctions, integrin expression and epithelial-stromal communication. These were also some differences between these processes, such as the regulation of tight junctions and mucins, which need to be further researched.

CONCLUSIONS

This review raised the prospect of shared and distinct mechanisms existing in PMT and EMT. Further investigation into similarities between the PMT in the endometrium and the EMT in tumorigenesis may provide new mechanistic insights into PMT and new targets for the management of implantation failure and infertility.

Effects of low doses of mifepristone on human embryo implantation process in a three-dimensional human endometrial in vitro co-culture system

OBJECTIVES

We wanted to explore the effects of two different low doses (0.5μM and 0.05μM) of mifepristone, exposed during the receptive period, on the human embryo implantation process, using a well-established three-dimensional in vitro cell culture model, specifically developed to study this process.

METHODS

An in vitro three-dimensional cell culture model was constructed using human endometrial cells isolated from the endometrium of proven fertile women, collected on cycle day LH+4. After 5 days of culture, supernumerary human embryos were added and cultured for another 5 days with mifepristone 0.5μM (n=8) or 0.05μM (n=10) or vehicle as control (n=10). The cultures were checked for embryo attachment and terminated. We studied the expression of 16 reported endometrial receptivity markers in the endometrial constructs using real-time polymerase chain reaction.

RESULTS

None of the embryos in 0.5μM of mifepristone attached to the endometrial constructs (p=.004), whereas 4 out of 10 in 0.05μM (p=.3698) and 7 out of 10 embryos in the control group attached to the cultures. We found that most of the studied receptivity markers were significantly altered with mifepristone exposure in a similar direction in both treatment groups. Only IL6 was significantly differentially expressed between the treatment groups (p=.017).

CONCLUSION

We report for the first time that exposure to a low concentration (0.5μM) of mifepristone during the receptive period successfully inhibits human embryo implantation process in vitro. Further, we observed a dose-dependent effect of mifepristone on endometrial receptivity at the functional level.

IMPLICATION

This study contributes new knowledge that low dose of mifepristone during the short period of receptive phase can inhibit endometrial receptivity, which further promotes mifepristone as a contraceptive agent. This could give women a treatment choice to avoid unwanted pregnancy with high efficacy and minimal side effects.

Paeonia lactiflora Enhances the Adhesion of Trophoblast to the Endometrium via Induction of Leukemia Inhibitory Factor Expression

In the present study, we investigated the role of Paeonia lactiflora Pall. extract on embryo implantation in vitro and in vivo. A polysaccharides depleted-water extract of P. lactiflora (PL-PP) increased LIF expression in human endometrial Ishikawa cells at non-cytotoxic doses. PL-PP significantly increased the adhesion of the human trophectoderm-derived JAr spheroids to endometrial Ishikawa cells. PL-PP-induced LIF expression was decreased in the presence of a p38 kinase inhibitor SB203580 and an MEK/ERK inhibitor U0126. Furthermore, endometrial LIF knockdown by shRNA reduced the expression of integrins β3 and β5 and adhesion of JAr spheroids to Ishikawa cells. In vivo administration of PL-PP restored the implantation of mouse blastocysts in a mifepristone-induced implantation failure mice model. Our results demonstrate that PL-PP increases LIF expression via the p38 and MEK/ERK pathways and favors trophoblast adhesion to endometrial cells.

Changes in the transcriptome of the human endometrial Ishikawa cancer cell line induced by estrogen, progesterone, tamoxifen, and mifepristone (RU486) as detected by RNA-sequencing

Background

Estrogen (E2) and progesterone (P4) are key players in the maturation of the human endometrium. The corresponding steroid hormone modulators, tamoxifen (TAM) and mifepristone (RU486) are widely used in breast cancer therapy and for contraception purposes, respectively.

Methodology/Principal findings

Gene expression profiling of the human endometrial Ishikawa cancer cell line treated with E2 and P4 for 3 h and 12 h, and TAM and RU486 for 12 h, was performed using RNA-sequencing. High levels of mRNA were detected for genes, including PSAP, ATP5G2, ATP5H, and GNB2L1 following E2 or P4 treatment. A total of 82 biomarkers for endometrial biology were identified among E2 induced genes, and 93 among P4 responsive genes. Identified biomarkers included: EZH2, MDK, MUC1, SLIT2, and IL6ST, which are genes previously associated with endometrial receptivity. Moreover, 98.8% and 98.6% of E2 and P4 responsive genes in Ishikawa cells, respectively, were also detected in two human mid-secretory endometrial biopsy samples. TAM treatment exhibited both antagonistic and agonistic effects of E2, and also regulated a subset of genes independently. The cell cycle regulator cyclin D1 (CCND1) showed significant up-regulation following treatment with TAM. RU486 did not appear to act as a pure antagonist of P4 and a functional analysis of RU486 response identified genes related to adhesion and apoptosis, including down-regulated genes associated with cell-cell contacts and adhesion as CTNND1, JUP, CDH2, IQGAP1, and COL2A1.

Conclusions

Significant changes in gene expression by the Ishikawa cell line were detected after treatments with E2, P4, TAM, and RU486. These transcriptome data provide valuable insight into potential biomarkers related to endometrial receptivity, and also facilitate an understanding of the molecular changes that take place in the endometrium in the early stages of breast cancer treatment and contraception usage.

Oviductal, endometrial and embryonic gene expression patterns as molecular clues for pregnancy establishment

In higher animals, the beginning of new life and transfer of genetic material to the next generation occurs in the oviduct when two distinct gametes cells unite resulting in the formation of a zygote. The zygote then undergoes serial developmental processes in the oviduct and enters into the uterus where it faces challenges and scrutiny from the endometrial ecosystem. Thus, embryos that are able to establish an appropriate embryo-maternal dialogue are capable of developing to term whereas the incompetent ones can perish any time during the gestation period. Although several lines of evidences indicated that pregnancy loss is a multi-factorial phenomenon, the biochemical composition of the embryo and maternal environment are the main players to determine pregnancy outcome. Indeed, expression patterns of the genes are the driving forces that induce biochemical composition changes in embryo, oviduct and uterine environment. Thus, examining the molecular signals that are associated with oviductal or endometrial receptivity and embryo implantation is essential for establishing strategies to improve pregnancy success. Therefore, this review focuses on the contribution of oviduct and its transcriptome profile on early stage embryo development and the impact of endometrium and its transcriptome changes on peri and post embryo implantation. In addition, this paper integrates established facts about hormonal and molecular signatures associated with endometrial receptivity. Finally, the blastocyst and pre-conception endometrial gene expression profiles have been discussed in relation to the pregnancy outcome to highlight the potentials of blastocyst and pre-transfer endometrial transcriptome profile approach for selecting appropriate recipient and developmentally competent embryo.

The role of sex steroid hormones, cytokines and the endocannabinoid system in female fertility

BACKGROUND

Marijuana, the most used recreational drug, has been shown to have adverse effects on human reproduction. Endogenous cannabinoids (also called endocannabinoids) bind to the same receptors as those of Δ(9)-tetrahydrocannabinol (THC), the psychoactive component of Cannabis sativa. The most extensively studied endocannabinoids are anandamide (N-arachidonoylethanolamine, AEA) and 2-arachidonoylglycerol. The endocannabinoids, their congeners and the cannabinoid receptors, together with the metabolic enzymes and putative transporters form the endocannabinoid system (ECS). In this review, we summarize current knowledge about the relationships of ECS, sex steroid hormones and cytokines in female fertility, and underline the importance of this endocannabinoid-hormone-cytokine network.

METHODS

Pubmed and the Web of Science databases were searched for studies published since 1985, looking into the ECS, sex hormones, type-1/2 T-helper (Th1/Th2) cytokines, leukaemia inhibitory factor, leptin and reproduction.

RESULTS

The ECS plays a pivotal role in human reproduction. The enzymes involved in the synthesis and degradation of endocannabinoids normalize levels of AEA for successful implantation. The AEA degrading enzyme (fatty acid amide hydrolase) activity as well as AEA content in blood may potentially be used for the monitoring of early pregnancies. Progesterone and oestrogen are involved in the maintenance of endocannabinoid levels. The ECS plays an important role in the immune regulation of human fertility.

CONCLUSIONS

The available studies suggest that tight control of the endocannabinoid-hormone-cytokine network is required for successful implantation and early pregnancy maintenance. This hormone-cytokine network is a key element at the maternal-foetal interface, and any defect in such a network may result in foetal loss.

Knockdown of IGF-binding protein 7 inhibits transformation of the endometrial gland in an in vitro model

Uterine endometrial glands and their secretory products are critical for the implantation and survival of the peri-implantation embryo, and for the establishment of uterine receptivity. We previously reported that insulin-like growth factor binding protein 7 (IGFBP7) is abundantly expressed in uterine glandular epithelial cells during the secretory phase of the menstrual cycle. In the present study, we used a cultured glandular epithelial cell line of human (EM1) to investigate the significance of IGFBP7 in the function of endometrial glands. EM1 cells formed a mesh-like structure on Matrigel, which was accompanied by elevated levels of intracellular cyclic AMP. However, these morphological changes were blocked by treatment with protein kinase A (PKA) inhibitor (H89). IGFBP7 knockdown using specific short interference RNA (siRNA) inhibited the formation of the mesh-like structure on Matrigel. Cyclic AMP analogs, dibutyryl-cAMP, and N(6)-phenyl-cAMP induced the expression of leukemia inhibitory factor (LIF) which is essential for the onset of implantation. Enhanced LIF expression was suppressed by IGFBP7 siRNA treatment. Western blot analysis revealed that IGFBP7 knockdown results in the aberrant, constitutive expression of the MAPK signaling pathway. These results suggest that IGFBP7 regulates morphological changes of glandular cells by interfering with the normal PKA and MAPK signaling pathways that are associated with the transformation and/or differentiation of endometrial glands.

Leukemia inhibitory factor and interleukin-11: critical regulators in the establishment of pregnancy

Blastocyst implantation into a receptive endometrium is critical to the establishment of pregnancy and is tightly regulated by factors within the blastocyst-endometrial micro-environment. Leukemia inhibitory factor (LIF) and interleukin-11 (IL11) have key roles during implantation. Female mice with a null mutation in the LIF or IL11RA gene are infertile due to a complete failure of implantation or a defective differentiation/decidualization response to the implanting blastocyst, respectively. LIF and IL11 deficiency during pregnancy is associated with infertility and miscarriage in women. Numerous cell populations at the maternal-fetal interface are regulated by LIF/IL11 including the endometrial epithelium, decidualizing stroma, placental trophoblasts and leukocytes. This review focuses on the roles of LIF/IL11 during early pregnancy and highlights their potential as contraceptive targets and therapeutic agents for infertility.

Endometrial effects of a single early luteal dose of the selective progesterone receptor modulator CDB-2914

OBJECTIVE

To test potential contraceptive mechanisms of the selective P receptor modulator CDB-2914 in the early luteal phase.

DESIGN

Prospective randomized clinical trial.

SETTING

Clinical research center.

PATIENT(S)

Fifty-six women with regular cycles.

INTERVENTION(S)

Women received a single dose of CDB-2914 (10, 50, or 100 mg) or placebo given after ovulation and within 2 days of the LH surge. Four to 6 days later, a transvaginal ultrasound scan measured endometrial thickness, and an endometrial biopsy specimen was obtained.

MAIN OUTCOME MEASURE(S)

The endometrium was evaluated by thickness and by immunohistochemical analysis for P-dependent markers; safety laboratory tests were performed, and E(2) and P levels were obtained.

RESULT(S)

CDB-2914 caused a significant dose-dependent decrease in endometrial thickness, an increase in glandular P receptors, and a decrease in peripheral node addressins. Estradiol and P levels and menstrual cycle timing were not altered. No adverse effects were observed.

CONCLUSION(S)

The alteration in endometrial thickness and P-dependent markers of implantation in the absence of changes in hormone levels and cycle length suggests that CDB-2914 may have contraceptive properties.

Emergency contraception in Cuba with 10 mg of mifepristone

BACKGROUND

Mifepristone in a dose of 10 mg is an effective emergency contraceptive when administered up to 120 hours after unprotected coitus.

METHODS

Between May 2003 and February 2005, we conducted in Cuba a single-arm trial to evaluate the effectiveness of 10 mg mifepristone for emergency contraception up to 6 days after unprotected coitus. A total of 635 women who requested emergency contraception after a single act of unprotected intercourse were included in the study.

RESULTS

After treatment there were 7/635 (1.1%) pregnancies (95% CI 0.4-2.3%). Pregnancy that might have occurred was prevented in 88.0% of the cases (95% CI 77.1-95.1%). The most common side effects reported by participants were fatigue (10.7%), dizziness (6.1%) and nausea (4.9%); vomiting was only reported by 0.6%. In 38/635 (6.0%) women menstruation was delayed more than 7 days.

CONCLUSIONS

Mifepristone 10 mg administered is an effective emergency contraceptive with an acceptable profile of side effects up to five days, but greater studies are necessary to verify its efficacy up to 6 days after unprotected intercourse.

Leukaemia inhibitory factor receptor and gp130 in the human Fallopian tube and endometrium before and after mifepristone treatment and in the human preimplantation embryo

Leukaemia inhibitory factor (LIF) is a cytokine, which is associated with reproductive processes such as embryo development and implantation. The objectives of this study were to detect the presence of LIF receptor (LIFR) and glycoprotein 130 (gp 130) in the human Fallopian tube, endometrium and preimplantation embryo and to study the effect of mifepristone on the expression of LIFR and gp130 in the Fallopian tube. Twenty-two healthy fertile women received a single dose of 200 mg mifepristone or placebo immediately after ovulation (LH + 2). Biopsies were obtained from the Fallopian tubes during laparoscopic sterilization once between days LH + 4 and LH + 6 and from endometrium once between days LH + 6 and LH + 8. Preimplantation embryos were received from couples undergoing in vitro fertilization treatment. Immunohistochemistry was used to detect the presence of LIFR and gp130 in the Fallopian tube, endometrium and preimplantation embryo. Real-time PCR was used to study LIFR and gp130 expression in the Fallopian tube and endometrium. LIFR and gp130 were localized in the Fallopian tube, preimplantation embryo and endometrium. LIFR was more abundant in the Fallopian tube than in the endometrium. In the blastocyst, the staining of gp130 was mainly localized in the inner cell mass, whereas LIFR was expressed in all cells. The presence of LIFR and gp130 in the Fallopian tube and preimplantation embryo indicates a role for LIF in communication between the embryo and the Fallopian tube. Mifepristone did not affect the expression of LIFR and gp130 in the Fallopian tube, nor in the endometrium suggesting that progesterone might not be directly involved in the regulation of LIFR or gp130.

Monoclonal anti-leukemia inhibitory factor antibody inhibits blastocyst implantation in the rhesus monkey

INTRODUCTION

Leukemia inhibitory factor (LIF) appears important in the process of blastocyst implantation in primates. In the present study, we investigated the effect on pregnancy outcome of the administration of a monoclonal antibody (mAb) to recombinant human (rh) LIF (anti-LIF mAb) into the uterine cavity of mated female rhesus monkeys during the peri-implantation period.

METHODS

Two milligrams of either mouse mAb to rhLIF or isotype-matched immunoglobulin (Ig) was administered into the uterine cavity on estimated Day 5 or Day 8 after ovulation either through the vagina (n=33) or through the oviduct (n=29) of successfully mated females.

RESULTS

There was a significant (p<.04) decline in pregnancy outcome in groups treated with anti-LIF mAb (8 pregnancies from 32 animals) compared with control animals (24 pregnancies from 30 animals). There was, however, no significant difference in pregnancy inhibition between a group of animals subjected to vaginal route treatment and a group of animals subjected to oviductal route treatment, as well as between a group subjected to anti-LIF mAb on Day 5 after ovulation and a group subjected to anti-LIF mAb on Day 8 after ovulation. No significant change was seen in the number of viable pregnancy in animals treated with 6 mg of anti-LIF mAb (5 pregnancies from 16 animals) compared with animals treated with 2 mg of anti-LIF mAb (8 pregnancies from 32 animals). Serum profiles of estradiol, progesterone, monkey chorionic gonadotropin and mouse IgG did not show any difference among different treatment subgroups during the luteal phase. However, among animals treated with anti-LIF mAb, the mean area under the curve for serum mouse IgG in pregnant animals (234+/-55 microg/mL day) was significantly (p<.01) less than that of nonpregnant animals (1325+/-97 microg/mL day).

CONCLUSION

The results of the present study put forward the proof of concept that LIF plays a critical role in the process of blastocyst implantation in the rhesus monkey.

Endometrial receptivity markers, the journey to successful embryo implantation

Human embryo implantation is a three-stage process (apposition, adhesion and invasion) involving synchronized crosstalk between a receptive endometrium and a functional blastocyst. This ovarian steroid-dependent phenomenon can only take place during the window of implantation, a self-limited period of endometrial receptivity spanning between days 20 and 24 of the menstrual cycle. Implantation involves a complex sequence of signalling events, consisting in the acquisition of adhesion ligands together with the loss of inhibitory components, which are crucial to the establishment of pregnancy. Histological evaluation, now considered to add little clinically significant information, should be replaced by functional assessment of endometrial receptivity. A large number of molecular mediators have been identified to date, including adhesion molecules, cytokines, growth factors, lipids and others. Thus, endometrial biopsy samples can be used to identify molecules associated with uterine receptivity to obtain a better insight into human implantation. In addition, development of functional in vitro systems to study embryo-uterine interactions will lead to better definition of the interactions existing between the molecules involved in this process. The purpose of this review was not only to describe the different players of the implantation process but also to try to portray the relationship between these factors and their timing in the process of uterine receptivity.

Expression of leukemia inhibitory factor and its receptors is increased during differentiation of human embryonic stem cells

OBJECTIVE

To investigate gene expression profiles during the early spontaneous differentiation of human embryonic stem cells (hESCs), with particular emphasis on leukemia inhibitory factor (LIF)-induced pathways and the ultrastructural surface morphology of the undifferentiated and spontaneously differentiated hESCs.

DESIGN

Prospective experimental study.

SETTING

University laboratory.

PATIENT(S)

Four hESC cell lines.

INTERVENTION(S)

The effect of LIF on receptor expression level was studied in cultures.

MAIN OUTCOME MEASURE(S)

Gene expression in the hESC line HS237 was analyzed using microarrays. Real-time reverse-transcription polymerase chain reaction was used to validate the microarray results in four hESC lines (HS181, HS235, HS237, HS293). Immunohistochemistry was used to assay LIF, LIF receptor, and gp130 protein expression. Cell surface morphology was studied using scanning electron microscopy.

RESULT(S)

The expression of LIF, LIF receptor, and gp130 messenger RNA and protein was increased in spontaneously differentiated HS237 cells compared with undifferentiated cells, with high expression of an inhibitor of LIF-mediated signaling, suppressor of cytokine signaling-1, in undifferentiated hESCs. Genes, those expressed specifically and those shared in undifferentiated hESCs, differentiated cells, and in fibroblasts, were identified. Supplementation with LIF did not affect the LIF receptor expression.

CONCLUSION(S)

The expression of LIF and its receptors is low in undifferentiated hESCs but increases during differentiation. Added LIF does not prevent spontaneous differentiation. Suppressor of cytokine signaling-1 may prevent LIF signaling in hESCs.

The science behind 25 years of ovarian stimulation for in vitro fertilization

To allow selection of embryos for transfer after in vitro fertilization, ovarian stimulation is usually carried out with exogenous gonadotropins. To compensate for changes induced by stimulation, GnRH analog cotreatment, oral contraceptive pretreatment, late follicular phase human chorionic gonadotropin, and luteal phase progesterone supplementation are usually added. These approaches render ovarian stimulation complex and costly. The stimulation of multiple follicular development disrupts the physiology of follicular development, with consequences for the oocyte, embryo, and endometrium. In recent years, recombinant gonadotropin preparations have become available, and novel stimulation protocols with less detrimental effects have been developed. In this article, the scientific background to current approaches to ovarian stimulation for in vitro fertilization is reviewed. After a brief discussion of the relevant aspect of ovarian physiology, the development, application, and consequences of ovarian stimulation strategies are reviewed in detail.

Cytokines, chemokines and growth factors in endometrium related to implantation

The complexity of the events of embryo implantation and placentation is exemplified by the number and range of cytokines with demonstrated roles in these processes. Disturbance of the normal expression or action of these cytokines results in complete or partial failure of implantation and abnormal placental formation in mice or humans. Of known importance are members of the gp130 family such as interleukin-11 (IL-11) and leukaemia inhibitory factor (LIF), the transforming growth factor beta (TGFbeta) superfamily including the activins, the colony-stimulating factors (CSF), the IL-1 system and IL-15 system. New data are also emerging for roles for a number of chemokines (chemoattractive cytokines) both in recruiting specific cohorts of leukocytes to implantation sites and in trophoblast differentiation and trafficking. This review focuses on those cytokines and chemokines whose expression pattern in the human endometrium is consistent with a potential role in implantation and placentation and for which some relevant actions are known. It examines what is known of their regulation and action along with alterations in clinically relevant situations.

Leukemia inhibitory factor and human embryo implantation

The success of embryonic implantation relies on an ideal cross-talk between the embryo and the receptive endometrium. This article focuses on the role of leukemia inhibitory factor (LIF) and its receptors in human embryo implantation. LIF is a secreted glycoprotein first described as a factor that induced the differentiation of mouse myeloid leukemic M1 cells into macrophages and later proposed as a marker of the embryo implantation process. An important role for LIF in implantation was shown on LIF knockout mice, when embryo implantation did not occur. In endometrium of healthy women, LIF and LIF mRNA are expressed throughout the menstrual cycle with a striking increase in the midsecretory phase, coinciding with a supposed window of implantation. Correlation in the expression of LIF and some other markers of implantation has been reported. LIF acts on cells by binding to the LIF receptor (LIFR) and gp130. Human blastocysts express mRNAs for LIFR and gp130, participating actively in establishing contact with the endometrium. In the endometrium, LIFR and gp130 are expressed in the endometrial epithelium throughout the cycle with strong increase in the midsecretory phase. Endometrium of infertile women produces significantly less LIF during the period of receptivity. The role of LIF gene mutations in unexplained infertility and implantation failures in IVF patients is not clear yet. Infertile patients showed reduced secretion of LIFR and gp130 compared with fertile controls during the implantation window. Recombinant human LIF might help to improve the implantation rate in women with unexplained infertility.

The antiprogesterone Org 31710 inhibits human blastocyst-endometrial interactions in vitro

OBJECTIVE

To investigate the effect of the anti-P Org 31710 on human blastocyst attachment to cultured endometrial epithelial cells.

DESIGN

Experimental in vitro study.

SETTING

University hospital.

PATIENT(S)

Eleven fertile endometrial donors.

INTERVENTION(S)

Timed endometrial biopsy for cell cultures.

MAIN OUTCOME MEASURE(S)

Blastocyst attachment rate on endometrial cell cultures; secretion of glycodelin and leukemia inhibitory factor into the culture medium measured by RIA and ELISA techniques; and expression of progesterone receptors, interleukin-1 receptor type-1, and integrin subunit beta(3) on endometrial epithelial cells examined by immunohistochemistry. Endometrial pinopodes visualized by scanning electron microscopy.

RESULT(S)

Eleven of 16 human blastocysts attached to control cultures, whereas none of 10 blastocysts attached when Org 31710 was added to the culture medium (P=.0007). Immunohistochemical studies demonstrated no significant differences between groups. Biochemical analyses displayed a trend toward higher glycodelin secretions and, by scanning electron microscopy, a tendency toward less pinopode formation in the Org 31710 group, but the results did not reach statistical significance. The presence of swollen microvilli, precursors of endometrial pinopodes, was significantly reduced on cultures with Org 31710 (P=.03).

CONCLUSION(S)

The study presents a model for human blastocyst-endometrial interactions responding to an anti-P drug. The exact mechanism for the anti-attachment properties of Org 31710 on the cultured endometrial cells and the blastocysts needs further evaluations.

The potential of mifepristone (RU-486) as an emergency contraceptive drug

The potential of mifepristone to be an emergency contraceptive is reviewed. Mifepristone prevents 92-100% of pregnancies with an acceptable side-effect profile on oral intake of a 10-600-mg dose within 72 h of unprotected intercourse. A single dose of 10 mg mifepristone resulted in a pregnancy rate of 1.5%, similar to a 1.5-mg single dose or two doses of 0.75 mg levonorgestrel 12 h apart, administered within 120 h (current standard) of unprotected sexual intercourse. Mifepristone and levonorgestrel do not differ in efficacy as emergency contraceptives. The mode of action of emergency contraception (EC) with mifepristone or levonorgestrel is primarily associated with inhibition of ovulation rather than prevention of implantation. Different doses of mifepristone appear to have similar effects. However, delay in the onset of subsequent menstruation caused by mifepristone is dose dependent and is reduced with a lower dose without affecting its efficacy. Patient acceptability of mifepristone as EC is high. However, the optimum standard dose of mifepristone is yet to be established for its application as an effective and acceptable emergency contraceptive drug for ordinary clinical use or practice.

Hormonal regulation of implantation

Implantation is a complex process that requires synchronization between the embryo and a receptive endometrium. Hormones, such as the female sex steroids, prostaglandins, and peptide hormones, regulate the cellular and molecular mediators of endometrial receptivity, which include pinopodes, cell adhesion molecules, cytokines, homeobox genes, and growth factors. These mediators can be altered, despite the presence of normal hormone levels and endometrial histology; this limits the usefulness of the luteal phase endometrial biopsy. Therefore, analysis of markers of endometrial receptivity may predict successful implantation better. Elevated androgen and estrogen levels, as seen with polycystic ovary syndrome and controlled ovarian hyperstimulation, respectively, also can have detrimental effects on the endometrium, and therefore, implantation.

Mifepristone for luteal phase contraception

The concept of luteal phase contraception and the use of mifepristone in clinical trials, which allows for testing of its validity, as well as clinical pharmacological research designed to understand its mode of action, are reviewed. Early luteal phase administration has a variety of morphological, physiological and biochemical effects on the endometrium that are likely to interfere with embryonic-endometrial interactions. In fact, specifically designed pilot clinical trials as well as data derived from emergency contraception studies indicate that early luteal phase administration of mifepristone is highly effective in preventing pregnancy, with minimal disturbance of hormonal parameters or menstrual cyclicity. Mid and late luteal phase administration of mifepristone at doses above 25 mg are highly effective in inducing endometrial bleeding in nonconceptional cycles. However, administration of mifepristone within the period between implantation and expected menses fails to induce bleeding in a significant proportion of cases, and furthermore the bleeding induced does not insure the termination of pregnancy. While the data suggest there is potential for a once-a-month contraceptive pill, it is likely that no molecule endowed with partial agonistic properties, like mifepristone, will completely and reliably suppress the essential functions of progesterone in order to achieve contraceptive efficacy comparable to that of modern contraceptive methods.

Reproductive biology and IVF: ovarian stimulation and endometrial receptivity

The influence of ovarian stimulation on endometrium receptivity has been inadequately addressed in medical literature. Hormonal effects of ovarian stimulation on endometrial changes as compared with the natural cycle should be elucidated and correlated with the potential of the embryo to implant. It is important to distinguish between the endometrial effect of induction of ovulation in anovulatory women and those of ovarian (super)ovulation in ovulatory women. Induction of ovulation leads to in vivo conception whereas ovarian stimulation results in in vitro fertilization. The available data in the field indicate that endometrial changes have an impressive negative influence on the potential of embryonic implantation. The aim of this review is to analyse the effects of gonadotropin, GnRH-agonist and GnRH-antagonist administration on endometrial behaviour, to highlight the gaps in current knowledge and to propose areas in which research is needed.

Summary of evidence and research needs on the use of mifepristone in fertility regulation: consensus from the conference

The conference on the use of mifepristone to reduce unwanted pregnancy, sponsored by the World Health Organization, Concept Foundation and the Rockefeller Foundation, took place in Bellagio, Italy, between 24 and 28 September 2001. The objective of the conference was to review the scientific information and to evaluate the use of mifepristone for emergency contraception, luteal contraception and menstrual induction. Mifepristone is highly effective for emergency contraception but its advantages and disadvantages in comparison with levonorgestrel need to be further studied. Data indicate that mifepristone alone or in combination with misoprostol has potential for occasional use for women seeking help following repeated unprotected intercourse and/or when the interval between intercourse and treatment is more then 120 h. Administration of mifepristone immediately after ovulation seems to be an effective contraceptive method. However, before it can be used commonly, there is a need for a simple and inexpensive method to identify the right time in the cycle. Once-a-month treatment with mifepristone and misoprostol at the expected time of menstruation is not a practical method due to bleeding irregularities and timing of treatment. Menstrual induction with mifepristone and a suitable prostaglandin analogue is highly effective. A randomized comparison with manual vacuum aspiration is, however, needed before it can be recommended for routine use.

A multiparametric study of the action of mifepristone used in emergency contraception using the Rhesus monkey as a primate model

Mifepristone is a potent agent used in emergency contraception (EC). In the present study, we examined the contraceptive efficacy of mifepristone used in EC and then, using the model of mifepristone-based EC, we investigated its mechanism of action in the rhesus monkey. Sexually mature females were allowed to cohabitate with male animals from 1600 to 900 h of any one day of days 8-17 of cycle without (Group I; n = 6) and with a single dose of mifepristone (Group II, n = 31, 25 mg per animal, subcutaneous) 72 h postcoitus. Blood samples from all animals of Groups I and II were used to determine the concentrations of estradiol (E), progesterone (P) and chorionic gonadotrophin in peripheral circulation for retrospective analysis of the days of ovulation and blastocyst implantation. Four out of six animals (66.6%) in Group I became pregnant, while all 31 monkeys in Group II failed to establish pregnancy along with marginal changes in serum concentrations of E and P. In the second part of the study, animals were subjected to the same experimental protocol followed by collection of endometrial tissue samples on cycle day 22 from animals of both Group I (n = 6) and Group II (n = 24). Endometrial samples were subjected to morphological analysis including mitotic index, immunohistochemistry for vascular endothelial growth factor (VEGF), leukemia inhibitory factor (LIF), transforming growth factor beta1, estradiol receptor (ER), progesterone receptor (PR), proliferating cell nuclear antigen, placental protein 14 (PP 14) and detection of apoptosis by terminal nick end labeling method followed by histometric analysis. The results were retrospectively analyzed between the two groups on the basis of the day of treatment after ovulation: early luteal phase (days 0-3 postovulation) and mid-luteal phase (days 4-7 after ovulation). Mifepristone used in EC in the present study resulted in general loss of functional integrity of epithelial compartment characterized by loss of secretory maturation, increased apoptosis and higher degree of degeneration along with decreased expression of VEGF, LIF, PP14 and ER, while PR level increased as compared to control samples. The vascular compartment appeared to be compromised along with affected morphological features and decreased expression of VEGF, LIF, ER and PR following the administration of mifepristone. It appears that mifepristone used in EC alters the physiological homeostasis in epithelial and vascular compartments of implantation stage endometrium rendering it hostile to blastocyst implantation. Furthermore, the degree to which the endometrial function is affected largely depends on the day of mifepristone treatment in a parameter-specific manner resulting in a higher degree of degenerative changes in samples obtained from animals who received mifepristone during mid-luteal phase of cycles.

Mechanisms of action of mifepristone when used for emergency contraception

An emergency contraceptive method is used after coitus but before pregnancy occurs. The use of emergency contraception is largely underutilized worldwide. Recently, treatment with 10 mg mifepristone as a single dose has emerged as one of the most effective hormonal methods for emergency contraception, with very low side effects. However, the mechanism of action of mifepristone in humans when used for contraceptive purposes and especially for emergency contraception remains largely unknown. The objective of this review is to summarize available data on the effect of mifepristone on female reproductive functions relevant to emergency use of the compound. Taken together, available data from studies in humans indicate that the contraceptive effect of mifepristone used as a single low dose for emergency contraception is mainly due to impairment of ovarian function, either by blocking or postponing the luteinizing hormone surge, rather than to inhibiting of implantation.

Effects of mifepristone on endometrial receptivity

At the development of receptivity the endometrium undergoes specific changes. Several factors have been suggested as markers of endometrial receptivity. A common feature for most of these factors is that they are directly, or indirectly, regulated by progesterone. The effect of various doses and regimens of mifepristone on endometrial development and markers of receptivity has been studied. Timed endometrial biopsies were assessed by immunhistochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and electron microscopy. In addition the contraceptive efficacy of these regimens was investigated. Administration of 200 mg of mifepristone immediately post ovulation has a pronounced effect on endometrial development and on suggested markers of receptivity. This regimen has been shown to be an effective contraceptive method. When 10 mg is given pre or post ovulation, only minor effects on the endometrium are observed. Our studies show that mifepristone, when administered in low doses that do not affect ovulation, significantly affects some of the studied markers of endometrial receptivity and reduces pregnancy rates; however, these activities are more pronounced with the higher dose, which is more effective. Our findings provide insight into the regulation of progesterone receptors of various suggested markers of endometrial receptivity and the possibility of using mifepristone for endometrial contraception.

Progesterone receptor isoform B in the human fallopian tube and endometrium following mifepristone

The distribution of progesterone receptor isoform B may have important clinical significance. The aim of this study was to compare the expression, localization and regulation of progesterone receptor isoform B in the human Fallopian tube and endometrium following mifepristone in a dose effective for contraception. Fertile women were treated with a single dose of 200 mg mifepristone on day luteinizing hormone (LH)+2. Biopsies were obtained from the Fallopian tube on day LH+4 to LH+6 and from the endometrium on day LH+6 to LH+8. Progesterone receptor isoform B expression was analyzed by immunohistochemistry and reverse transcriptase polymerase chain reaction. Treatment with mifepristone increased progesterone receptor isoform B concentration in epithelial and stromal cells in the Fallopian tube and also increased progesterone receptor isoform B concentration in the glandular cells of the endometrium. These results further support the hypothesis that the contraceptive effect of mifepristone when given postovulatory is primarily due to alteration of the peri-implantation milieu influencing endometrial receptivity.

Coexpression of pinopodes and leukemia inhibitory factor, as well as its receptor, in human endometrium

OBJECTIVE

To determine cell-type-specific expression of leukemia inhibitory factor (LIF) and LIF receptor (LIFR) proteins relative to formation of pinopodes in human endometrial samples.

DESIGN

Prospective clinical study.

SETTING

Hospital-based unit for reproductive health and university-affiliated reproductive research laboratories.

PATIENT(S)

Twenty-six healthy fertile women with normal menstrual cycles.

MAIN OUTCOME MEASURE(S)

Routine blood and urine samples were obtained, and vaginal ultrasonography and endometrial biopsy were performed. Pinopode formation and expression of LIF and LIFR were examined in endometrial samples.

RESULT(S)

Samples obtained during LH days 6 through 9 had pinopodes at different developmental stages. Both surface and glandular epithelial cells expressed maximal levels of LIF and LIFR protein, in biopsy samples showed fully developed pinopodes. Immunostaining of LIF was more intense in the glandular epithelium, whereas immunostaining of LIFR was most intense in the surface epithelium. Before and after the appearance of pinopodes, LIF and LIFR immunostaining was less intense or faint. Stromal endometrial cells showed faint LIF accumulation.

CONCLUSION(S)

The simultaneous positive spatial and temporal expression of pinopodes and LIF and LIFR proteins in endometrial samples from healthy women suggests that both molecular and structural cell changes are important in the initiation of human blastocyst implantation.

Implantation defects in infertile women with endometriosis

The endometrium undergoes characteristic histologic changes during the menstrual cycle as it prepares for embryo implantation. Historic and current data suggest the presence of a defined period of maximal uterine receptivity during the mid-secretory phase occurring between days 7 and 10 postovulation. In recent years, we and others have sought to define biochemical markers of receptivity that might be used to better understand this time of endometrial differentiation. Based on the work with cell adhesion molecules, we have discovered three different integrins that are only coexpressed during this time in the cycle when embryos will successfully implant. By studying the regulation of one of these, the alpha(v)beta3 integrin, and its extracellular matrix ligand, osteopontin (OPN), we have defined two separate regulatory pathways that may regulate endometrial receptivity. While alpha(v)beta3 expression appears to be stimulated by EGF or heparin-binding EGF, osteopontin is stimulated by progesterone. We now believe the former pathway is a paracrine-mediated signal, while the latter is a direct effect of progesterone on the estrogen-primed endometrial epithelium. In women with endometriosis, it appears that alpha(v)beta3 expression is reduced, while OPN expression is unaffected. Interestingly, binding of OPN to the surface epithelium appears quite limited when alpha(v)beta3 expression is lacking. Such evidence continues to reinforce the notion that endometrium from some women with endometriosis is dysfunctional and may account for the reduction in cycle fecundity noted in this group of patients.

Modulation of the action of chorionic gonadotropin in the baboon (Papio anubis) uterus by a progesterone receptor antagonist (ZK 137. 316)

Signals from the developing mammalian blastocyst rescue the corpus luteum (CL) and modulate the uterine environment in preparation for implantation and early pregnancy. Our previous studies demonstrated that both short- and long-term administration of chorionic gonadotropin (CG) markedly alters the morphology and the biochemical activity of the receptive endometrium. Because the effects of CG were superimposed on a progesterone-primed endometrium, this study was undertaken to determine if the inhibition of progesterone action by progesterone receptor antagonists (PRa) in intact and ovariectomized baboons would alter the action of CG on the endometrium at the time of uterine receptivity. In the short-term hCG-treated baboons, the PRa reduced the epithelial plaque reaction, completely inhibited alpha-smooth muscle actin (alphaSMA) expression in stromal fibroblasts, and induced the reappearance of the progesterone (PR) and estrogen (ERalpha) receptors in epithelial cells. However, this treatment protocol had no effect on the expression of glycodelin in the glandular epithelium. In contrast, glycodelin expression in addition to alphaSMA was suppressed in the ovariectomized animals. In the long-term hCG-treated baboons, the PRa had a similar effect on both alphaSMA, PR, and ER. In addition, this treatment also resulted in an inhibition of glycodelin expression in the glandular epithelium. These results indicate that blocking the action of progesterone on the endometrium even for a short period of time has a profound effect on the hCG-induced response in stromal fibroblasts. In contrast, for the diminution of glandular epithelial function in the presence of an ovary requires prolonged inhibition of progesterone action, suggesting a potential paracrine effect on the endometrium from the CL in response to hCG.

Local effects of mifepristone on the nonhuman primate endometrium

OBJECTIVE

To determine the effects of a low-dose mifepristone regimen on endometrium in the rhesus monkey by endometrial staging and analysis of molecular markers of endometrial receptivity.

DESIGN

A prospective, randomized comparative study.

SETTING

Academic research environment.

ANIMAL(S)

Normally cycling rhesus (Macaca mulatta) monkeys.

INTERVENTION(S)

Monkeys (5 per control or treatment group) received 0.03 mg of mifepristone in vehicle (sesame oil) per kilogram of body weight or vehicle daily from day 2 of the menstrual cycle to 7 days after the midcycle E2 surge.

MAIN OUTCOME MEASURE(S)

Serum estradiol (E2) and progesterone (P) levels; endometrial staging and immunoreactivity of leukemia inhibitory factor and interleukin-6 performed on fixed endometrial tissues; and relative abundance of endometrial estrogen and P receptor mRNA evaluated with semiquantitative reverse transcriptase polymerase chain reaction in which cyclophilin mRNA, a housekeeping gene product, was coamplified as the reference standard.

RESULT(S)

Mifepristone at 0.03 mg/kg/d induced a delay in the endometrial cycle with a shift from the late to midsecretory phase. This treatment regimen did not suppress the midcycle gonadotropin surge or, presumably, ovulation because P levels were normal during the midluteal phase. The staining intensity of leukemia inhibitory factor and interleukin-6 was dependent upon the endometrial stage and was decreased in treated monkeys. E and P receptor mRNAs increased significantly with mifepristone treatment compared with controls, another indication of delayed uterine staging.

CONCLUSION(S)

Mifepristone at 0.03 mg/kg/d had no antiovulatory effect but delayed development of the endometrium from the late to midsecretory phase. This study provides further evidence that endometrial maturation can be altered without affecting ovarian cyclicity.

Leukemia-inhibitory factor-neuroimmune modulator of endocrine function

Leukemia-inhibitory factor (LIF) is a pleiotropic cytokine expressed by multiple tissue types. The LIF receptor shares a common gp130 receptor subunit with the IL-6 cytokine superfamily. LIF signaling is mediated mainly by JAK-STAT (janus-kinase-signal transducer and activator of transcription) pathways and is abrogated by the SOCS (suppressor-of cytokine signaling) and PIAS (protein inhibitors of activated STAT) proteins. In addition to classic hematopoietic and neuronal actions, LIF plays a critical role in several endocrine functions including the utero-placental unit, the hypothalamo-pituitary-adrenal axis, bone cell metabolism, energy homeostasis, and hormonally responsive tumors. This paper reviews recent advances in our understanding of molecular mechanisms regulating LIF expression and action and also provides a systemic overview of LIF-mediated endocrine regulation. Local and systemic LIF serve to integrate multiple developmental and functional cell signals, culminating in maintaining appropriate hormonal and metabolic homeostasis. LIF thus functions as a critical molecular interface between the neuroimmune and endocrine systems.

Contraceptive efficacy of daily administration of 0.5 mg mifepristone

The antiprogestin mifepristone has shown potential to be used as a contraceptive. If 200 mg mifepristone is administered immediately after ovulation, the endometrium shows sufficient impairment of secretory development to prevent implantation. Low daily doses of mifepristone have been shown to reduce several of the local factors regarded as crucial for implantation in human endometrium. To find out if this regimen is sufficient to prevent pregnancy, 32 women were recruited for a study where 0.5 mg mifepristone was administered daily. A total of 141 cycles were studied. Five pregnancies occurred, which was significantly less than if no contraceptive method had been used. However, the dose chosen did not seem sufficient to act as a contraceptive although it is probably not possible to increase the dose without disturbing ovulation and bleeding pattern.

Contraceptive use of antiprogestin

OBJECTIVES

To study the effect of antiprogestin on ovarian function and endometrial development during the menstrual cycle and the possibility of using these compounds for contraceptive purposes.

METHODS

Administration of different doses of the antiprogestin mifepristone during the menstrual cycle; intermittent measurements of luteinizing hormone, progestin and estrogen in blood and/or urine; endometrial morphology and concentration of markers for endometrial receptivity; efficacy trials of the contraceptive effect of mifepristone.

RESULTS

A high dose of mifepristone administered in the follicular phase will inhibit follicular development. If mifepristone is given immediately after ovulation, the secretory development of the endometrium and the expression of, for instance, leukemia inhibitory factor and integrins will be inhibited. Similar effects on the endometrium are obtained with small weekly doses (2.5 or 5.0 mg) or small daily doses (0.5 mg) of mifepristone, which do not inhibit ovulation. Once-monthly administration of 200 mg mifepristone on the day after ovulation, and emergency postcoital treatment, are highly effective methods for preventing pregnancy. Even 5 mg once weekly has a significant contraceptive effect.

CONCLUSIONS

The antiprogestin mifepristone has a number of effects during the menstrual cycle which makes the compound suitable for contraceptive use. Treatment after a single act of unprotected intercourse, and once-a-month treatment immediately after ovulation, have shown high contraceptive efficacy. A low-dose regimen which does not influence ovulation also has a contraceptive effect, but the efficacy needs to be improved before routine clinical use.

Contraceptive efficacy of low doses of mifepristone

OBJECTIVE

To determine whether a 5-mg dose of mifepristone is sufficient to prevent pregnancy.

DESIGN

Clinical study.

SETTING

Academic research center.

SUBJECT(S)

Healthy, fertile, sexually active female volunteers.

INTERVENTION

Volunteers received a 5-mg dose of mifepristone once weekly, starting on cycle day 2, for up to 6 months. This was their only contraceptive method.

MAIN OUTCOME MEASURE(S)

Number of pregnancies.

RESULT(S)

The treatment resulted in a significant decrease in pregnancy rate without affecting the menstrual cycle or causing disturbing side effects.

CONCLUSION(S)

A low dose of mifepristone, which does not inhibit ovulation, reduces fertility significantly by affecting the endometrium. However, the contraceptive effect needs to be improved for the drug to compete with other contraceptive methods.

Cloning of leukemia inhibitory factor (LIF) and its expression in the uterus during embryonic diapause and implantation in the mink (Mustela vison)

Leukemia inhibitory factor (LIF) is essential for embryo implantation in mice. Whether LIF plays a role in termination of embryonic diapause and initiation of implantation in carnivores, especially in species with obligate delayed implantation such as the mink, is not known. The objectives of this study were to clone the LIF coding sequence in the mink and determine its mRNA abundance in the uterus through embryonic diapause, implantation, and early postimplantation. We show that the mink LIF cDNA contains 609 nt encoding a deduced protein of 203 amino acids. The homologies are 80.6, 90, 88.2, 87.6, and 86.8% in coding sequence and 79.2, 90.1, 91, 90.1 and 85.4% in amino acid sequence with mouse, human, pig, cow, and sheep respectively. Glycosylation sites and disulfide bonds present in other species are generally conserved in the mink LIF sequence. Quantitation by polymerase chain reaction amplification indicates that LIF mRNA is expressed in mink uterus just prior to implantation and during the first two days after implantation, but not during diapause or later after implantation pregnancy. The abundance of LIF mRNA was significantly higher in the uterus at the embryo expansion stage (P < 0.05) than at days 1-2 of postimplantation. By immunohistochemical localization it was shown that LIF is expressed in the uterine epithelial glands at time of embryonic expansion and in early postimplantation. The coincidence of LIF expression with implantation in this species suggests that LIF is involved in the implantation process, and may be a maternal signal which terminates obligate embryonic diapause.

Leukemia inhibitory factor in human reproduction

PROBLEM

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of the interleukin-6 family and has different biological actions in various tissue systems. Although named for its ability to inhibit proliferation of a myeloid leukemic cell line by inducing differentiation, it also regulates the growth and differentiation of embryonic stem cells, primordial germ cells, peripheral neurons, osteoblasts, adipocytes, and endothelial cells. LIF is crucial for successful implantation of the embryo in mice. Currently, there is an accumulation of data about the role of LIF in human reproduction.

METHOD OF STUDY

This review of the literature and of our studies focuses on the expression, regulation, and effects of LIF in the human endometrium, fallopian tube, and ovarian follicle.

RESULTS

Human endometrium expresses LIF in a menstrual cycle-dependent manner. Maximal expression is observed between days 19 and 25 of the menstrual cycle, coinciding with the time of implantation. Various cytokines and growth factors induce endometrial LIF expression in vitro. LIF receptor is expressed in endometrial tissue throughout the menstrual cycle and on human blastocysts in a stage-dependent manner. Affecting the trophoblast differentiation pathway toward the adhesive phenotype, LIF plays a role in implantation. LIF is also expressed and secreted by the epithelial cells of the fallopian tube. Its increased expression in the tubal stromal cell cultures by the inflammatory cytokines suggests a link between salpingitis and ectopic implantation in the tube. The rising follicular fluid LIF level around the time of ovulation indicates that LIF may play a role in ovulatory events, early embryonic development, and implantation.

CONCLUSIONS

There is growing evidence that LIF may be one of the entities that plays a role in human reproduction.