Identifying and optimizing human endometrial gene expression signatures for endometrial dating.

STUDY QUESTION: What are the key considerations for developing an enhanced transcriptomic method for secretory endometrial tissue dating? SUMMARY ANSWER: Multiple gene expression signature combinations can serve as biomarkers for endometrial dating, but their predictive performance is variable and depends on the number and identity of the genes included in the prediction model, the dataset characteristics and the technology employed for measuring gene expression. WHAT IS KNOWN ALREADY: Among the new generation of transcriptomic endometrial dating (TED) tools developed in the last decade, there exists variation in the technology used for measuring gene expression, the gene makeup and the prediction model design. A detailed study, comparing prediction performance across signatures for understanding signature behaviour and discrepancies in gene content between them, is lacking. STUDY DESIGN, SIZE, DURATION: A multicentre prospective study was performed between July 2018 and October 2020 at five different centres from the same group of clinics (Spain). This study recruited 281 patients and finally included in the gene expression analysis 225 Caucasian patients who underwent IVF treatment. After preprocessing and batch effect filtering, gene expression measurements from 217 patients were combined with artificial intelligence algorithms (support vector machine, random forest and k-nearest neighbours) allowing evaluation of different prediction models. In addition, secretory-phase endometrial transcriptomes from gene expression omnibus (GEO) datasets were analysed for 137 women, to study the endometrial dating capacity of genes independently and grouped by signatures. This provided data on the consistency of prediction across different gene expression technologies and datasets. PARTICIPANTS/MATERIALS, SETTING, METHODS: Endometrial biopsies were analysed using a targeted TruSeq (Illumina) custom RNA expression panel called the endometrial dating panel (ED panel). This panel included 301 genes previously considered relevant for endometrial dating as well as new genes selected for their anticipated value in detecting the secretory phase. Final samples (n = 217) were divided into a training set for signature discovery and an independent testing set for evaluation of predictive performance of the new signature. In addition, secretory-phase endometrial transcriptomes from GEO were analysed for 137 women to study endometrial dating capacity of genes independently and grouped by signatures. Predictive performance among these signatures was compared according to signature gene set size. MAIN RESULTS AND THE ROLE OF CHANCE: Testing of the ED panel allowed development of a model based on a new signature of 73 genes, which we termed 'TED' and delivers an enhanced tool for the consistent dating of the secretory phase progression, especially during the mid-secretory endometrium (3-8 days after progesterone (P) administration (P + 3-P + 8) in a hormone replacement therapy cycle). This new model showed the best predictive capacity in an independent test set for staging the endometrial tissue in the secretory phase, especially in the expected window of implantation (average of 114.5 ± 7.2 h of progesterone administered; range in our patient population of 82-172 h). Published sets of genes, in current use for endometrial dating and the new TED genes, were evaluated in parallel in whole-transcriptome datasets and in the ED panel dataset. TED signature performance was consistently excellent for all datasets assessed, frequently outperforming previously published sets of genes with a smaller number of genes for dating the endometrium in the secretory phase. Thus, this optimized set exhibited prediction consistency across datasets. LARGE SCALE DATA: The data used in this study is partially available at GEO database. GEO identifiers GSE4888, GSE29981, GSE58144, GSE98386. LIMITATIONS, REASONS FOR CAUTION: Although dating the endometrial biopsy is crucial for investigating endometrial progression and the receptivity process, further studies are needed to confirm whether or not endometrial dating methods in general are clinically useful and to guide the specific use of TED in the clinical setting. WIDER IMPLICATIONS OF THE FINDINGS: Multiple gene signature combinations provide adequate endometrial dating, but their predictive performance depends on the identity of the genes included, the gene expression platform, the algorithms used and dataset characteristics. TED is a next-generation endometrial assessment tool based on gene expression for accurate endometrial progression dating especially during the mid-secretory. STUDY FUNDING/COMPETING INTEREST(S): Research funded by IVI Foundation (1810-FIVI-066-PD). P.D.-G. visiting scientist fellowship at Oxford University (BEFPI/2010/032) and Josefa Maria Sanchez-Reyes' predoctoral fellowship (ACIF/2018/072) were supported by a program from the Generalitat Valenciana funded by the Spanish government. A.D.-P. is supported by the FPU/15/01398 predoctoral fellowship from the Ministry of Science, Innovation and Universities (Spanish Government). D.W. received support from the NIHR Oxford Biomedical Research Centre. The authors do not have any competing interests to declare.

The role of endometrial staining for CD138 as a marker of chronic endometritis in predicting live birth.

PURPOSE: Chronic endometritis (CE) is diagnosed via endometrial biopsy and staining for plasma cells. A threshold plasma cell count that identifies CE and predicts pregnancy outcomes has not been established, and the prevalence of plasma cells in the general infertile population is unknown. The purpose of this study was to determine the prevalence of plasma cells in the general infertile population and whether a threshold exists which predicts live birth. METHODS: Endometrial samples were obtained prospectively from 80 women undergoing IVF, embedded in paraffin, and stained for plasma cells using mouse mono-clonal antibody for CD138. Slides were reviewed at 20× magnification and 10 random images captured. Three reviewers graded each image for plasma cells. Participants underwent single, euploid, and frozen blastocyst transfer. RESULTS: Forty-nine percent of samples had ≥1 plasma cell across 10 HPFs, 11% had ≥5 cells across 10 HPFs, and 4% had ≥10 cells across 10 HPFs. There was no difference in prevalence between those who did and did not achieve live birth. Using thresholds of 1, 5, and 10 plasma cells per 10 HPFs, there were no differences in implantation, clinical pregnancy, clinical pregnancy loss, or live birth rates between patients with and without CE. CONCLUSION: Endometrial plasma cells are present in half the general infertile population and do not predict implantation, clinical pregnancy, clinical pregnancy loss, or live birth rates at low levels.

Varying levels of serum estradiol do not alter the timing of the early endometrial secretory transformation.

STUDY QUESTION: Do supraphysiologic estradiol (E2) levels in the ranges attained during normal and high response superovulation cycles modify the onset of endometrial secretory transformation? SUMMARY ANSWER: Highly supraphysiologic levels of E2 do not alter the ability of physiologic levels of progesterone (P4) to induce secretory transformation. WHAT IS KNOWN ALREADY: Previous studies have demonstrated that premature P4 elevations during IVF cycles are associated with a decrement in clinical pregnancy rates after fresh embryo transfer due to shifts in the window of implantation (WOI). However, alterations in the onset of secretory transformation may not apply uniformly to all patients. High responders with supraphysiologic E2 levels accompanied by similar subtle increases in P4 have not been shown to have decreased sustained implantation rates. This prospective investigation in which whole-genome transcriptomic and methylomic analysis of the endometrium is performed for individual patients under a range of E2 concentrations brings clarity to a long-debated issue. STUDY DESIGN, SIZE, DURATION: A randomized, prospective and paired trial was conducted in which 10 participants were enrolled and randomized to the order in which they completed three distinct uterine stimulation cycles, each at a specific E2 concentration: physiologic (∼180 pg/ml), moderately supraphysiologic (600-800 pg/ml) or supraphysiologic (2000 pg/ml). Target E2 ranges were selected to mimic those seen in natural, controlled ovarian stimulation and IVF cycles. E2 valerate was administered in order to maintain stable E2 levels for 12 days followed by intramuscular P4 in oil 10 mg/day for two doses, after which an endometrial biopsy was performed. A total of 30 endometrial biopsies were included in a whole-genome transcriptomic and methylomic analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Healthy volunteers without a history of infertility were included in this study at a single large infertility center. DNA was isolated from the endometrial biopsy specimens and bisulfite sequencing was performed to construct a methylation array. Differential methylation analysis was conducted based on differences in M-values of individuals across treatment groups for each probe as well as carrying out t-tests. RNA was isolated for RNA-Seq analysis and gene expression values were compared using DESeq2. All analyses were performed in a pairwise fashion to compare among the three stimulation cycles within individuals and secondarily to compare all participants in each of the cycles. MAIN RESULTS AND THE ROLE OF CHANCE: The mean peak E2 and P4 levels were 275 pg/ml and 4.17 ng/ml in the physiologic group, 910 pg/ml and 2.69 ng/ml in the moderate group was, and 2043 pg/ml and 2.64 ng/ml in the supraphysiologic group, respectively. Principal component analysis of 834 913 CpG sites was performed on M-values of individuals within the low, moderate and supraphysiologic conditions in a paired approach. There were no differences in genome-wide methylation within participants across E2 groups. A paired analysis revealed that gene expression profiles did not differ within the same individual at each of the three E2 levels. No significant alterations in gene expression as related to endometrial physiology were identified between the low, moderate and supraphysiologic groups in an inter-participant analysis. LIMITATIONS, REASONS FOR CAUTION: Although each participant completed a physiologic cycle in which E2 levels were maintained in a range that would simulate a natural cycle, our findings are limited by lack of an unmedicated control to assess if there was a potential effect from E2V. Additionally, our results were obtained in fertile individuals, who may have a different endometrial response compared to an infertile population. Despite the whole genomic endometrial assessment and rigorous, paired study design, the sample size was limited. WIDER IMPLICATIONS OF THE FINDINGS: Given that the endometrial response to P4 is unaffected by E2 levels in the supraphysiologic range, diminutions in implantation seen in stimulated cycles may result from embryonic-endometrial dyssynchrony following early P4 elevations or slowly blastulating embryos, which occur independently of the magnitude of the E2 rise. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the Foundation for Embryonic Competence, Basking Ridge, NJ, USA. Dr E.S. reports consultancy work for The Foundation for Embryonic Competence, Basking Ridge, NJ, USA. The other authors declare no conflict of interests related to this topic. TRIAL REGISTRATION NUMBER: NCT02458404.

Diminished ovarian reserve and poor response to stimulation in patients <38 years old: a quantitative but not qualitative reduction in performance.

STUDY QUESTION: Do infertile women aged <38 years with quantitative evidence of diminished ovarian reserve and/or poor response to stimulation also exhibit poor oocyte quality as measured by blastulation rates, aneuploidy rates, and live birth rates? SUMMARY ANSWER: Young women with evidence of accelerated follicular depletion, either by precycle ovarian reserve testing or postcycle evidence of low oocyte yield, exhibit equivalent blastulation rates, aneuploidy rates and live birth rates per euploid embryo transfer as age-matched controls with normal precycle and postcycle parameters. WHAT IS KNOWN ALREADY: Previous studies are conflicted as to whether women with evidence of diminished ovarian reserve and/or poor ovarian response are also at increased risk of exhibiting evidence of poor oocyte quality. Most prior studies have failed to adequately control for the confounding effect of female age on typical markers of oocyte quality in poor responders. The rate of follicular depletion occurs at around 38 years on average; thus, evidence of quantitative depletion before this would indicate a premature diminution of ovarian reserve and allow evaluation of whether markers of oocyte quality are tied to quantitative markers. STUDY DESIGN, SIZE, DURATION: This was a retrospective cohort study at a single center between 2012 and 2016. This time frame was specifically chosen as all embryos were cultured to the blastocyst stage at this center during the study period (no cleavage stage transfers were performed). Two comparisons were made: precycle assessment of ovarian reserve (based on anti-mullerian hormone (AMH) level) and postcycle oocyte yield results. For each comparison, patients in <10th percentile were compared to patients in the interquartile range (IQR) with respect to blastulation rate, aneuploidy rate and live birth rate. A mixed effects model was created to control for female age (in the <38 year old range) and correlation among oocytes from a given cohort. PARTICIPANTS/MATERIALS, SETTING, METHODS: For the precycle blastulation analysis, only patients with AMH data available were included (345 patients with AMH in the <10th percentile versus 1758 patients with AMH in the 25th to 75th percentile (IQR)). To compare aneuploidy rates, the subset of these patients who pursued preimplantation genetic testing for aneuploidy (PGT-A) was then analyzed (124 patients in the <10th percentile versus 782 patients in the IQR). For the postcycle blastulation analysis, all patients who proceeded to retrieval (whether or not they also had AMH data available) were included (535 patients with oocyte yield in the <10th percentile versus 2675 patients in the IQR). To compare aneuploidy rates, the subset of these patients who pursued PGT-A was then analyzed (156 patients in the <10th percentile versus 1100 patients in the IQR). MAIN RESULTS AND THE ROLE OF CHANCE: The adjusted odds of a given fertilized oocyte developing to a blastocyst, being aneuploid or leading to a live birth after euploid transfer were no different if the oocyte was retrieved from a cycle with ovarian reserve parameters or oocyte yield in the <10th percentile compared to an oocyte retrieved in a cycle with those parameters in the 25-75th percentile. An AMH level in the <10th percentile did more commonly result in cycle cancellation prior to retrieval and after retrieval prior to transfer due to global arrest of embryos. LIMITATIONS, REASONS FOR CAUTION: The timing of retrieval in patients with fewer oocytes may be more optimal given the greater ability to discern the overall maturity of the cohort, thus enhancing performance per retrieved oocyte. Analyses included only first cycles. Subsequent adjustment of protocol due to prior performance may mean that some patients in the <10th percentile for oocyte yield are actually better prognosis patients than their first cycle indicates. Data on whether or not patients were on oral contraceptives at time that AMH level drawn was not available. Other unknown biases are also likely to be present given retrospective nature of the study. WIDER IMPLICATIONS OF THE FINDINGS: While young women with evidence of quantitative depletion of ovarian reserve have lower live birth rates per stimulation cycle, this not attributable to poor oocyte quality because the blastulation rate per fertilized oocyte and live birth rate per embryo transfer are equivalent to that in women with normal quantitative markers of ovarian reserve. Thus, the pathophysiology mediating a premature quantitative decline in ovarian reserve appears different than that which mediates markers of oocyte quality, such as aneuploidy. Young poor responders may use this information to help guide embryo accumulation strategies when considering their family building plans. STUDY FUNDING/COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: N/A.

Prediction of pregnancy viability in bovine in vitro-produced embryos and recipient plasma with Fourier transform infrared spectroscopy.

We analyzed embryo culture medium (CM) and recipient blood plasma using Fourier transform infrared (FTIR) metabolomics to predict pregnancy outcome. Individually cultured, in vitro-produced (IVP) blastocysts were transferred to recipients as fresh and vitrified-warmed. Spent CM and plasma samples were evaluated using FTIR. The discrimination capability of the classifiers was assessed for accuracy, sensitivity (pregnancy), specificity (nonpregnancy), and area under the receiver operator characteristic curve (AUC). Within all IVP fresh embryos (birth rate=52%), high AUC were obtained at birth, especially with expanded blastocysts (CM: 0.80±0.053; plasma: 0.89±0.034). The AUC of vitrified IVP embryos (birth rate = 31%) were 0.607±0.038 (CM, expanded blastocysts) and 0.672±0.023 (plasma, all stages). Recipient plasma generally predicted pregnancy outcome better than did embryo CM. Embryos and recipients with improved pregnancy viability were identified, which could increase the economic benefit to the breeding industry.

Impaired Mitochondrial Stress Response due to CLPP Deletion Is Associated with Altered Mitochondrial Dynamics and Increased Apoptosis in Cumulus Cells.

Caseinolytic peptidase P (CLPP) plays a central role in mitochondrial unfolded protein response (mtUPR) and is required for maintaining protein homeostasis in the mitochondria. Global germline Clpp deletion causes female infertility and accelerated follicular depletion. In the current study, we aimed to characterize the role of CLPP in cumulus cell function, gene expression, and mitochondrial ultrastructure. We found that mitochondria in Clpp-deficient cumulus cells have a smaller aspect ratio (length/width) and have a larger coverage area (mitochondrial area/cytoplasmic area) under electron microscopy. These ultrastructural changes were accompanied with diminished expression of mitochondrial dynamics genes. RNA sequencing analysis revealed a significant change in genes related to cellular metabolism in Clpp-deficient cumulus cells compared to wild type. In addition, apoptosis and phagosome pathways were significantly affected. Immunofluorescence assessment confirmed increased apoptotic activity and decreased cell proliferation in cumulus oophorus complexes (COCs) of Clpp-deficient mice. Our findings demonstrate that deletion of CLPP results in significant structural and functional changes in cumulus cells and suggests that mtUPR is required for cumulus cell function.

Interleukin-8 induces proliferation of endometrial stromal cells: a potential autocrine growth factor.

Proliferation of endometrium is dependent on sex steroid hormones, but specific growth factors are likely to play an important role in regulating this process. A number of cytokines and growth factors are synthesized in the endometrium in response to sex steroid hormones and act to regulate endometrial function. Endometrial cells produce interleukin-8 (IL-8) both in vivo and in vitro. We hypothesized that IL-8, a neutrophil chemoattractant/activating factor and a potent angiogenic agent that has been shown to stimulate growth in other cell types, may directly stimulate proliferation of endometrial cells. We first investigated the effect of IL-8 and mouse antihuman-IL-8 neutralizing antibody on endometrial stromal cell proliferation using both a colorimetric assay and thymidine uptake. We then investigated the modulation of endometrial stromal cell IL-8 production and proliferation by antisense oligonucleotides specific for IL-8. There was a concentration-dependent increase of cell proliferation with IL-8 (2-fold at 1 ng/mL; P < 0.01 between control and concentrations above 0.01 ng/mL) and a concentration-dependent inhibition of cell proliferation with anti-IL-8 antibody (to 30% of the control at 1 microg/mL; P < 0.01 between control and concentrations above 0.1 microg/mL). IL-8 antisense oligonucleotide treatment decreased IL-8 production by endometrial stromal cells in culture as well as cell proliferation when it is compared with scrambled (nonsense) oligonucleotide treatment (P < 0.01). Addition of IL-8 (1 ng/mL) reversed the proliferation inhibitory effect of IL-8 antisense oligonucleotides. We propose that IL-8 may act as an autocrine growth factor in the endometrium, and suggest that it may also play a role in the pathogenesis of endometriosis.

Interleukin-8 in the human endometrium.

We have previously shown that interleukin-8 (IL-8), a cytokine with neutrophil chemotactic/activating and T cell chemotactic activity, is produced by human endometrial stromal and glandular cells in culture. The present study investigated the temporal and spatial expression of IL-8 messenger ribonucleic acid (mRNA) and protein in the human endometrium. Endometrial tissue (n = 52) was obtained from human uteri after hysterectomy conducted for reasons other than endometrial disease or from endometrial biopsies. The day of the menstrual cycle was established from women's menstrual history and was confirmed by histology. Half of the tissues (n = 26) were snap-frozen in liquid nitrogen, cellular RNA was extracted, and Northern blots were hybridized with a riboprobe complementary to a specific sequence of IL-8 mRNA. The remaining tissues (n = 26) were processed for frozen sections, and immunohistochemistry was performed using mouse antihuman IL-8 antibody. Comparison of IL-8 mRNA levels throughout the menstrual cycle revealed that late secretory and early to midproliferative phase IL-8 expression was significantly greater than midcycle expression (P < 0.02). Analysis of the IL-8 immunohistochemistry revealed that IL-8 protein is found in the surface epithelium and glands throughout the menstrual cycle. There was no detectable immunoreactive IL-8 in the stromal cells. We conclude that IL-8 is produced in the human endometrium in vivo, and the variations of IL-8 mRNA throughout the menstrual cycle suggest that sex hormones may regulate its gene expression. We speculate that IL-8 may modulate the timely recruitment of neutrophils and lymphocytes into the endometrium.

Estradiol regulates monocyte chemotactic protein-1 in human coronary artery smooth muscle cells: a mechanism for its antiatherogenic effect.

OBJECTIVE: The protective effect of estrogen against early atherosclerosis in animal models is well documented, but the mechanisms responsible for this effect are not well understood. The earliest recognizable event in the pathogenesis of atherosclerosis is an increased recruitment of macrophages into the arterial subendothelium. Macrophages first play a protective role by removing low-density lipoproteins, but when the cholesterol is in excess, macrophages are converted into foam cells and form atheromas. Recent human and animal data indicate that the recruitment of macrophages to the arterial wall is mediated by monocyte chemotactic protein-1 (MCP-1). We hypothesized that one of the mechanisms of estrogen's protective effect against atherosclerosis may be the down-regulation of MCP-1 expression in the arterial wall. DESIGN: Human coronary artery smooth muscle cells were replicated to confluence in smooth muscle cell basal medium supplemented with growth factors and 5% fetal bovine serum. Before each experiment, cells were incubated for 24 h with phenol red-free medium containing 5% charcoal-stripped calf serum, and then they were treated with various concentrations of 17beta-estradiol as well as selective estrogen receptor (ER) modulators, raloxifene and tamoxifen. MCP-1 messenger ribonucleic acid (mRNA) levels were quantified by Northern blots. MCP-1 protein was quantified using an enzyme-linked immunosorbent assay. ER expression was evaluated by reverse transcriptase-polymerase chain reaction. RESULTS: Human coronary artery smooth muscle cells expressed MCP-1 mRNA and produced MCP-1 protein. Estradiol induced up to 40% inhibition in mRNA expression at concentrations 10-9 M and higher. Raloxifene and tamoxifen also resulted in an inhibition, but the inhibition was less than when induced by estradiol. Estradiol also inhibited the MCP-1 protein production in a concentration-dependent manner (p < 0.05). Coronary smooth muscle cells expressed both ERalpha and ERbeta. CONCLUSION: Our findings suggest that one of the mechanisms by which estrogen prevents atherosclerosis is by down-regulating MCP-1 expression, thus decreasing macrophage recruitment to the arterial wall.

Growth-regulated alpha expression in the peritoneal environment with endometriosis.

OBJECTIVE: To investigate the presence and modulation of growth-regulated alpha, a member of the chemokine family with neutrophil chemotactic activity, in the peritoneal fluid of women with or without endometriosis. METHODS: Peritoneal fluid samples were obtained at laparoscopy from 63 women with endometriosis and 19 fertile women without endometriosis. Endometrial tissue was obtained from uteri after hysterectomy for reasons other than endometrial disease or from endometrial biopsies of reproductive-age women. Cellular RNA was extracted and northern blots were hybridized with an oligonucleotide probe complementary to a specific sequence of growth-regulated alpha messenger RNA. Growth-regulated alpha in peritoneal fluid and culture supernatant was quantified using enzyme-linked immunosorbent assay. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney tests. RESULTS: The median (range) concentration of growth-regulated alpha in peritoneal fluid samples from 19 normal fertile women was 27 pg/mL (0-108), from 24 women with moderate endometriosis 34 pg/mL (8-150), and from seven with severe endometriosis was 73 pg/mL (10-221) (P = .04, P = .01, respectively). In the moderate and severe endometriosis groups, the levels of growth-regulated alpha were significantly higher in the peritoneal fluid of women with untreated endometriosis (73 pg/mL [10-221]) than in women with medically treated endometriosis (25 pg/mL [8-47]). In mesothelial and endometrial stromal cells in culture, growth-regulated alpha messenger RNA and protein were detectable constitutively; however, both interleukin-1 alpha and tumor necrosis factor-alpha induced higher levels of growth-regulated alpha messenger RNA and protein in a dose- and time-dependent manner. CONCLUSIONS: Growth-regulated alpha levels are elevated in the peritoneal fluid of women with moderate and severe endometriosis. This chemotactic factor, which acts via the interleukin-8 receptor, may play a role in the pathogenesis of endometriosis.

Basic fibroblast growth factor: peritoneal and follicular fluid levels and its effect on early embryonic development.

OBJECTIVE: To investigate the effect of basic fibroblast growth factor (FGF) on preimplantation embryos and to evaluate the levels of basic FGF in follicular and peritoneal fluid. DESIGN: Prospective study. SETTING: University-based laboratory. PATIENT(S): Follicular fluids (FFs) were obtained from women undergoing ovulation induction (n = 62) and peritoneal fluids were obtained from women with (n = 49) or without (n = 12) endometriosis. INTERVENTION(S): The effect of basic FGF on mouse embryos was assessed. Basic FGF concentrations were measured in pre-hCG and post-hCG FFs and in peritoneal fluids. MAIN OUTCOME MEASURE(S): Two-cell murine embryos were treated with basic FGF and followed for the rate of blastocyst formation and embryo hatching. Follicular and peritoneal fluid basic FGF levels were measured by ELISA. RESULT(S): Basic FGF (10 ng/mL) decreased the rate of blastocyst formation and embryo hatching. The level of basic FGF did not change in the FF around ovulation, and there was no correlation between FF basic FGF levels and reproductive parameters, with the exception of age. The levels of basic FGF in the peritoneal fluid of women with or without endometriosis were not different. CONCLUSION(S): Basic FGF is present in follicular and peritoneal fluids, but its concentration in these fluids does not change during the menstrual cycle or in the presence of endometriosis. Basic FGF inhibits murine preimplantation embryonic development at concentrations 10-100 times higher than the levels detected in follicular and peritoneal fluids.

Expression of aminopeptidase N in human endometrium and regulation of its activity by estrogen.

OBJECTIVES: To determine whether aminopeptidase N (APN) regulates the cycle-dependent bioavailability of interleukin-8 (IL-8) in the endometrium. DESIGN: Prospective study. SETTING: University medical center. PATIENT(S): Women without endometrial pathology from the proliferative (n = 25) or secretory (n = 18) phase of the menstrual cycle. INTERVENTION(S): We first immunolocalized APN in the endometrium using an anti-APN antibody. We then determined the regulation of APN kinetic activity by sex steroids in endometrial stromal cell cultures. MAIN OUTCOME MEASURE(S): Expression of APN in human endometrium throughout the menstrual cycle. Regulation of APN activity by estradiol and progesterone in cultured endometrial stromal cells. RESULT(S): Immunohistochemistry of endometrial sections revealed staining of endometrial stroma throughout the menstrual cycle. There was no detectable staining in glandular cells. The expression of APN as detected by immunohistochemistry was significantly lower in the early proliferative phase. In cultured cells, estradiol inhibited APN activity in a concentration-dependent manner. Progesterone did not have a significant effect. CONCLUSION(S): Stromal localization of APN in endometrium may explain the epithelial rather than stromal presence of IL-8 in vivo. Decreased expression of APN may increase IL-8 bioavailability thus contributing to angiogenesis and polymorphonuclear leukocyte chemotaxis in early proliferative phase.

Perspectives on emerging biomarkers for non-invasive assessment of embryo viability in assisted reproduction.

A key step in assisted reproduction is the assessment of embryo viability in order to identify the embryo(s) most likely to result in pregnancy. Currently used embryo assessment systems are largely based on morphology and cleavage rate. While these systems have been pivotal in improving implantation and pregnancy rates and reducing multiple gestations, their precision is still insufficient. The limitations of strategies based on morphology have led to the investigation of adjunctive technologies for non-invasive assessment of embryo viability in assisted reproduction. These include the measurement of glucose, pyruvate, or amino acid levels in the embryo culture media, assessment of oxygen consumption by the embryo, genomic and proteomic profiling, and most recently, analytical examination of the embryonic metabolome. As the number of ART cycles increases worldwide, improvements in the ability to quickly and non-invasively identify the best embryos for transfer become an increasingly more important goal for reproductive medicine.

Regulation of monocyte chemotactic protein-1 expression in human endometrial stromal cells by integrin-dependent cell adhesion.

Shed menstrual endometrium is viable and has the ability to implant and grow in women, who eventually develop endometriosis. Many of the cell-to-cell or cell-to-extracellular matrix (ECM) connections are mediated by integrins. Monocyte chemotactic protein (MCP)-1, a potent chemotactic factor produced in many cell types, is elevated in the peritoneal fluid of women with endometriosis. In this study, we investigated whether endometrial stromal cell (ESC) adhesion itself induces the expression of MCP-1 and whether this process is integrin mediated. ESC were plated on Petri dishes and 24-well plates coated with fibronectin, laminin, collagen IV, poly-L-lysine, or mouse anti-human integrin beta(1) and beta(2) monoclonal antibodies. Adherence of ESC to various ECM substrates, except for poly-L-lysine, a non-integrin-dependent adhesion matrix, induced the expression of MCP-1 at both mRNA and protein levels. Engagement of beta(1)-containing integrins was associated with ESC adhesion and resulted in up-regulation of MCP-1 gene expression and protein secretion. Disruption of the actin cytoskeleton by treating ESC with cytochalasin D completely blocked the increase of MCP-1 induced in response to integrin activation. These findings indicate a novel mechanism of MCP-1 regulation. Cell adhesion to ECM is an important event that leads to stimulation of MCP-1 expression, and this process is mediated by integrins.

Leukaemia inhibitory factor expression in human follicular fluid and ovarian cells.

Leukaemia inhibitory factor (LIF) is a 43 kDa glycoprotein with a remarkable range of biological actions in different tissue systems. LIF improves the rate of fertilization of mouse oocytes in vitro and up-regulates aromatase enzyme. We postulated that LIF may be an important modulator of ovarian function and may also improve embryo quality in humans. Follicular fluid samples from patients undergoing in-vitro fertilization (IVF) and embryo transfer (n = 123), from women undergoing ovarian stimulation (n = 4) and from women undergoing laparoscopy for tubal ligation during their follicular phase (n = 3) were used. Follicular fluid LIF, oestradiol, and progesterone were measured and embryo quality was assessed. Granulosa-lutein cells were cultured for 3 days in Ham's F-12:Dulbecco's modified Eagle's medium (DMEM). Ovarian stromal cells, isolated by enzymatic dispersion of ovarian tissue, were also cultured in the same medium. Following experimental treatments, LIF mRNA and protein concentrations were quantified. The concentration of LIF was 0.8 +/- 0.3 (mean +/- SEM) pg/ml in pre-human chorionic gonadotrophin (HCG) follicular fluid samples and 13.0 +/- 1.1 pg/ml in post-HCG follicular fluid samples (P < 0.05). LIF levels were undetectable in three follicular fluid samples obtained during unstimulated follicular phase. There was a correlation between follicular fluid LIF and follicular fluid oestradiol concentrations (r = 0.36; P = 0.0001) and the number of grade I embryos (r = 0.62; P = 0.01). LIF mRNA and the protein were expressed constitutively but in low amounts in the ovarian stromal cell cultures. The concentrations of LIF mRNA as well as protein were increased by interleukin (IL)-1alpha and tumour necrosis factor alpha (TNF alpha) in a time- and concentration-dependent manner. Purified granulosa-lutein cells expressed low amounts of LIF mRNA and protein which were not significantly increased by IL-1alpha or TNF alpha. Our findings suggest that HCG stimulates the expression of LIF in follicular fluid. Both granulosa-lutein and ovarian stromal cells express the LIF mRNA and produce the protein. Modulation of LIF in these cells may play an important role in the physiology of ovulation and early embryo development.

Growth-regulated alpha expression in human preovulatory follicles and ovarian cells.

PROBLEM: Around the time of ovulation the number of neutrophils increases in the theca of the leading follicle. We hypothesized that growth-regulated alpha (GRO alpha), a neutrophil chemoat-tractant/activating factor, may be a modulator of periovulatory neutrophil chemotaxis. METHOD: GRO alpha levels were measured in follicular fluids (n = 61). Granulosa-lutein and ovarian stromal cells were also cultured. After experimental paradigms, GRO alpha mRNA was evaluated by Northern analysis, GRO alpha in follicular fluids, and culture supernatants were quantified using ELISA. RESULTS: In follicular fluids the mean pre-human chorionic gonadotropin (hCG) GRO alpha level was 51 +/- 24 (+/- SEM) pg/ml, post-hCG it was 210 +/- 20 pg/ml (P = 0.04). GRO was produced constitutively by ovarian stromal and granulosa-lutein cells. Interleukin-alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) further stimulated GRO alpha production. Treatment of stromal cells with hCG also stimulated GRO alpha production. CONCLUSION: GRO alpha is a constituent of periovulatory follicular fluid. Ovarian stromal and granulosa-lutein cells express the GRO alpha mRNA and produce the protein. The regulation of GRO alpha by cytokines and hCG suggests that GRO alpha may play a role in the process of ovulation.

Regulation of monocyte chemotactic protein-1 expression in human endometrial stromal cells by estrogen and progesterone.

There is a cyclicity in the number of endometrial macrophages that is most likely secondary to changes in steroid hormone levels. One cytokine that controls macrophage migration is monocyte chemotactic protein-1 (MCP-1). In the endometrium, highest levels of MCP-1 are detected perimenstrually, when estrogen levels are low; however, when estrogen levels are high (around the time of ovulation), MCP-1 levels are lowest. We hypothesized that sex steroids may be involved in the regulation of macrophage migration by regulating MCP-1 expression. We investigated the regulation of MCP-1 expression in human endometrial stromal cells by estradiol 17beta (E2) and progestins. We found that MCP-1 mRNA levels decreased in response to E2 (5 x 10(-8) M), with biphasic nadirs at 8 h and 24 h. MCP-1 protein production was also inhibited by E2 in a concentration-dependent manner. Tamoxifen, an anti-estrogen, alone (10(-7) M) did not affect MCP-1 expression, but it reversed the E2-induced inhibition up to 80%. Progesterone (10(-7) M) alone slightly decreased MCP-1 levels, and the combination of E2 and progesterone further decreased them, but that decrease was not different from that observed using E2 treatment alone. In summary, we found that E2 inhibits MCP-1 expression in endometrial stromal cells, and we speculate that E2 may control endometrial macrophage migration by regulating MCP-1 expression.

The peritoneal fluid levels of interleukin-12 in women with endometriosis.

PROBLEM: Interleukin-12 (IL-12) is produced mainly by monocytes/macrophages, and it induces proliferation and cytotoxicity of T-cells and natural killer cells. In women with endometriosis, natural killer cell activity in the peritoneal fluid is significantly decreased. We aimed to measure the peritoneal fluid level of IL-12 in endometriosis. METHOD OF STUDY: We measured IL-12 levels in peritoneal fluid samples from women with or without endometriosis and in supernatants from endometrial stromal, ovarian stromal, and mesothelial cell cultures, using a high-sensitivity enzyme-linked immunosorbent assay. RESULTS: The median concentration of IL-12 in the peritoneal fluid of women with endometriosis was 1.1 pg/ml (range, 0.2-5.5) and was 1.6 pg/ml (range, 0.4-2.8) in women without endometriosis, not a statistically significant difference. IL-12 was not detected in the supernatants of endometrial stromal, ovarian stromal, and mesothelial cell cultures. CONCLUSION: Concentrations of IL-12 in the peritoneal fluid of women with or without endometriosis are low, but they are detectable and are not affected significantly by the presence of endometriosis.

Monocyte chemotactic protein-1 expression in human corpus luteum.

Invasion of the corpus luteum by macrophages is a characteristic of luteal regression. Monocyte chemotactic protein-1 (MCP-1), a chemokine that recruits macrophages, is expressed in the rat corpus luteum where it increases in amount during luteolysis. In this study we examined the temporal and spatial expression of MCP-1 and changes in macrophage concentration in the human corpus luteum. Corpora lutea (n = 39) were grouped according to menstrual cycle phase and were examined by immunohistochemistry for MCP-1 and macrophages, and by Northern blot for MCP-1 mRNA. We found increasing amounts of macrophages with progressing luteolysis (P < 0.001). Staining for MCP-1 was stronger in the regressing corpora lutea compared with the staining in corpora lutea of early luteal phase (P < 0.05). MCP-1 was more prominent in blood vessel walls surrounding the corpus luteum than in vessels located far from it. The mean MCP-1 mRNA expression in regressing corpora lutea was higher than that observed in corpora lutea of the early and mid-luteal phase (P = 0.003). In conclusion, we found that MCP-1 expression and the number of macrophages increase with regression of the corpus luteum. MCP-1 is mostly expressed in blood vessel walls surrounding the corpus luteum and may play a role in the recruitment of macrophages to the corpus luteum during its regression.

Follicular fluid of women with endometriosis stimulates the proliferation of endometrial stromal cells.

The peritoneal environment in endometriosis is known to have growth-promoting effects on endometrial cells. To investigate whether follicular fluid, a contributor to the peritoneal fluid, stimulates endometrial cell proliferation, we incubated endometrial stromal cells in culture with various dilutions of follicular fluid obtained from women with or without endometriosis undergoing oocyte retrieval for in-vitro fertilization. Cell proliferation assays were performed using follicular fluid from 28 women (without endometriosis, n = 13; with endometriosis, n = 15) in eight different endometrial stromal cell culture set-ups. Cell proliferation was assessed by a colorimetric method. Maximum cell proliferation was detected when endometrial cells were incubated with 50% dilution of follicular fluid for 48 h. Follicular fluid from women with endometriosis induced significantly higher cell proliferation than follicular fluid from women without endometriosis (P < 0.05). Our findings indicate that follicular fluid contents may contribute to the growth-promoting factors in the peritoneal fluid of women with endometriosis.