Microarray evaluation of endometrial receptivity in Chinese women with polycystic ovary syndrome

LIFR-Mediated ERBB2 Signaling Is Essential for Successful Embryo Implantation in Mice

In eutherian mammals, embryo implantation is a critical process for a successful pregnancy. In mice, the activation of the leukemia inhibitory factor (LIF) receptor-STAT3 signaling axis induces embryo adhesion and decidualization. The LIF receptor is believed to function as a heterodimer composed of LIFR (encoded by Lifr) and GP130 (encoded by Il6st); however, their distinct expression patterns in the uterine epithelium immediately prior to implantation suggest divergent functional roles. In this study, we generated uterine epithelium-specific Lifr knockout (Lifr eKO) mice and conducted a comprehensive gene expression analysis of the endometrium before implantation. We compared these results with those from uterine epithelium-specific Gp130 knockout (Gp130 eKO) mice. Similarly to Gp130 eKO mice, Lifr eKO mice were completely infertile. We identified 299 genes with expression changes greater than twofold following gene deletion; among these, 31 genes were downregulated and 57 genes were upregulated in both eKO models. Many of the downregulated genes were previously implicated in uterine function. Hub gene analysis identified Erbb2 and c-Fos as key regulators in both models. Further experiments using an ERBB2 inhibitor suggested that LIFR-ERBB2-mediated signaling plays a crucial role in embryo implantation.

Cell type and region-specific transcriptional changes in the endometrium of women with RIF identify potential treatment targets

Recurrent implantation failure (RIF) is a devastating condition that leaves many undergoing fertility treatment childless. The human endometrium is receptive to a blastocyst for a brief period, the window of implantation. Critical knowledge underpinning biological processes leading to RIF, essential for effective treatment, is lacking. We employed spatial transcriptomics to define region- and cell-type-specific differences in endometrial gene expression in luteinizing hormone timed biopsies between women with RIF (n = 8) and fertile controls (FC) (n = 8). Differentially expressed genes (DEGs) were identified when comparing endometrial regions between FC and RIF (685 luminal epithelium, 293 glandular epithelium, 419 subluminal stroma, 264 functionalis stroma, 1,125 subluminal stromal CD45+ leukocytes, and 1,049 functionalis stromal CD56+ leukocytes). Only 57 DEGs were common to all subregions and cell types, which highlights that multiple DEGs are lost when the endometrium is examined as a single entity. When RIF-specific DEGs were leveraged against knowledge from mouse genetic models, genes associated with aberrant embryo implantation phenotypes were observed, mostly in immune cell populations. Dysregulated pathways in specific endometrial regions included the "WNT signaling pathway," altered in the functionalis and subluminal stroma. "Response to estradiol" and "ovulation cycle" pathways were dysregulated in the subluminal stroma. In silico drug screening identified potential compounds that can reverse the RIF gene expression profile (e.g., raloxifene, bisoprolol). Our findings, in a well-characterized cohort, highly endorse consideration of each endometrial region and cell type as separate entities. Ignoring individual regions and composite cell populations will overlook important aberrations, forego potential treatment targets, and lead to research waste pursuing clinically irrelevant treatment options.

Endometrial transcriptome profiling of patients with recurrent implantation failure during hormone replacement therapy cycles

Background

The molecular mechanisms underlying window of implantation (WOI) displacement in patients with recurrent implantation failure (RIF) remain unclear. This study aims to explore the transcriptomic signatures of endometrium with normal and displaced WOIs and to identify the causes of endometrial receptivity (ER) abnormalities and WOI displacement in RIF patients.

Methods

In this study, 40 RIF patients were recruited and underwent personalized embryo transfer (pET) guided by the predicted results of endometrial receptivity diagnosis (ERD) model. Transcriptome analysis of endometrium from patients with clinical pregnancies after pET was performed to identify differentially expressed genes (DEGs) associated with WOI displacement. Gene expression data from HRT and natural cycle endometrium were compared to identify specific gene expression patterns of ER-related genes during WOI.

Results

The ERD results indicated that 67.5% of RIF patients (27/40) were non-receptive in the conventional WOI (P+5) of the HRT cycle. The clinical pregnancy rate in RIF patients improved to 65% (26/40) after ERD-guided pET, indicating the effectiveness of transcriptome-based WOI prediction. Among the 26 patients with clinical pregnancy, the gene expression profiles of P+5 endometrium from advanced (n=6), normal (n=10) and delayed (n=10) WOI groups were significantly different from each other. Furthermore, 10 DEGs identified among P+5 endometrium of 3 groups were involved in immunomodulation, transmembrane transport and tissue regeneration, which could accurately classify the endometrium with different WOIs. Additionally, a large number of ER-related genes showed significant correlation and similar gene expression patterns in P+3, P+5, and P+7 endometrium from HRT cycles and LH+5, LH+7, and LH+9 endometrium from natural cycles.

Conclusion

Our study shows that ER-related genes share similar gene expression patterns during WOI in both natural and HRT cycles, and their aberrant expression is associated with WOI displacements. The improvement of pregnancy outcomes in RIF patients by adjusting ET timing according to ERD results demonstrates the importance of transcriptome-based endometrial receptivity assessment and the clinical efficiency of ERD model.

Expression profile analysis of LncRNAs and mRNAs in pre-receptive endometrium of women with polycystic ovary syndrome undergoing in vitro fertilization-embryo transfer

BACKGROUND

To compare the expression levels of long non-coding RNA (lncRNA) and messenger RNA (mRNA) in pre-receptive endometrium between patients with Polycystic Ovary Syndrome (PCOS)and normal ovulation undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHODS

Endometrial tissues were collected with endometrial vacuum curette in pre-receptive phase (3 days after oocytes retrieval) from PCOS and control groups. LncRNAs and mRNAs of endometrium were identified via RNA sequencing and alignments. A subset of 9 differentially expressed lncRNAs and 11 mRNAs were validated by quantitative reverse transcription polymerase chain reaction(qRT-PCR)in 22 PCOS patients and 18 ovulation patients. The function of mRNAs with differential expression patterns were explored using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG).

RESULTS

We found out 687 up-regulated and 680 down-regulated mRNAs, as well as 345 up-regulated and 63 down-regulated lncRNAs in the PCOS patients in contrast to normal ovulation patients. qRT-PCR was used to detect the expression of 11 mRNAs, and validated that the expression of these 6 mRNAs CXCR4, RABL6, OPN3, SYBU, IDH1, NOP10 were significantly elevated among PCOS patients, and the expression of ZEB1 was significantly decreased. qRT-PCR was performed to detect the expression of 9 lncRNAs, and validated that the expression of these 7 lncRNAs IDH1-AS1, PCAT14, FTX, DANCR, PRKCQ-AS1, SNHG8, TPT1-AS1 were significantly enhanced among PCOS patients. Bioinformatics analysis showed that differentially expressed genes (DEGs) involved KEGG pathway were tyrosine metabolism, PI3K-Akt pathway, metabolic pathway, Jak-STAT pathway, pyruvate metabolism, protein processing in endoplasmic reticulum, oxidative phosphorylation and proteasome. The up-regulation of GO classification was involved in ATP metabolic process, oxidative phosphorylation, RNA catabolic process, and down-regulation of GO classification was response to corticosteroid, steroid hormone, and T cell activation.

CONCLUSION

Our results determined the characteristics and expression profile of endometrial lncRNAs and mRNAs in PCOS patients in pre-receptive phase, which is the day 3 after oocytes retrival. The possible pathways and related genes of endometrial receptivity disorders were found, and those lncRNAs may be developed as a predictive biomarker of endometrium in pre-receptive phase.

Which transfer day results in the highest live birth rate for PCOS patients undergoing in vitro fertilization?

BACKGROUND

Polycystic ovary syndrome (PCOS) has unusual levels of hormones. The hormone receptors in the endometrium have a hostile effect and make the microenvironment unfavorable for embryo implantation. The use of gonadotropin stimulation during in vitro fertilization (IVF) may have an impact on embryo implantation and live birth rate. According to recent data, the clinical results of day 4 embryo transfer (D4 transfer) were on par with those of day 5 embryo transfer (D5 transfer) in IVF-ET. There are few studies comparing the outcomes of transplants with various etiologies and days. The purpose of this study was to determine which transfer day had the best result for PCOS patients undergoing IVF.

METHODS

This retrospective cohort study was conducted in the Xingtai Infertility Specialist Hospital between January 2017 and November 2021. A total of 1,664 fresh ART cycles met inclusion criteria, including 242 PCOS transfers and 1422 tubal factor infertility transfers.

CONCLUSIONS

PCOS individuals had the highest live birth rate on D4 transferred. It was not need to culture embryos to blastocysts to optimize embryo transfer for PCOS women. This could be a novel approach to transplantation for PCOS.

The Effect of Metformin and Carbohydrate-Controlled Diet on DNA Methylation and Gene Expression in the Endometrium of Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is an endocrine disease associated with infertility and metabolic disorders in reproductive-aged women. In this study, we evaluated the expression of eight genes related to endometrial function and their DNA methylation levels in the endometrium of PCOS patients and women without the disease (control group). In addition, eight of the PCOS patients underwent intervention with metformin (1500 mg/day) and a carbohydrate-controlled diet (type and quantity) for three months. Clinical and metabolic parameters were determined, and RT-qPCR and MeDIP-qPCR were used to evaluate gene expression and DNA methylation levels, respectively. Decreased expression levels of HOXA10, GAB1, and SLC2A4 genes and increased DNA methylation levels of the HOXA10 promoter were found in the endometrium of PCOS patients compared to controls. After metformin and nutritional intervention, some metabolic and clinical variables improved in PCOS patients. This intervention was associated with increased expression of HOXA10, ESR1, GAB1, and SLC2A4 genes and reduced DNA methylation levels of the HOXA10 promoter in the endometrium of PCOS women. Our preliminary findings suggest that metformin and a carbohydrate-controlled diet improve endometrial function in PCOS patients, partly by modulating DNA methylation of the HOXA10 gene promoter and the expression of genes implicated in endometrial receptivity and insulin signaling.

Updates in diagnosing polycystic ovary syndrome-related infertility

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a condition that affects approximately 13% of reproductive age women and is characterized by androgen excess, menstrual irregularity and altered ovarian morphology. PCOS presents a complex etiology and pathophysiology, which still requires a detailed investigation of biochemical signatures to identify the molecules and mechanisms that govern it.

AREAS COVERED

This narrative review summarizes the main molecular alterations found in the ovarian follicular fluid, endometrium and placenta of women with PCOS, and the genotypes potentially associated with the outcome of infertility treatments in PCOS.

EXPERT OPINION

PCOS is associated with multiple alterations in growth factors, sex steroid hormones, reactive oxygen species, proinflammatory cytokines and adipokines, which contribute to follicle arrest/ anovulation or suboptimal corpus luteum function, and ultimately to menstrual irregularity and hyperandrogenic symptoms. A panel of PCOS biomarkers should include, besides ovarian products, markers of adipose tissue function, insulin resistance, vascular health, and low-grade chronic inflammation. The effects of ovarian stimulation drugs on infertile women with PCOS are likely to be modified by genetic factors, but the available evidence is heterogeneous; therefore, future studies should evaluate standard treatments and pre-specified outcomes of interest to provide more conclusive answers.

Hormonal and Metabolic Factors Influence the Action of Progesterone on the Endometrium of Women with Polycystic Ovary Syndrome

Hormonal and metabolic factors may influence endometrial quality and interfere with the action of progesterone. Therefore, the aim of our study was to address this issue. Participants were recruited from an outpatient reproductive endocrinology clinic at an academic tertiary medical care centre. All subjects underwent endometrial biopsy (EB) in the follicular phase of the cycle prior to treatment. Thereafter, they were treated with micronized progesterone (400 mg/day × 10 days intravaginally) from days 14-28 of the next cycle. A second EB was performed between days 21-24 of the cycle (the second phase). The metabolic and hormonal serum levels were evaluated during the implantation window. EB samples were analysed using light microscopy for histomorphometric analysis. The endometrium of women with Polycystic Ovarian Syndrome (PCOS) in the second phase demonstrated a uniform surface epithelium with less leukocyte infiltration and an absence of apoptotic figures compared to the control group. (p < 0.021). The thickness of the surface epithelium in the second phase of the PCOS group correlated positively with free and bioavailable testosterone values. The number of stromal cells increases with increasing insulin levels. Our results suggest that histomorphometric abnormalities of the endometrium persist and are linked to androgen and insulin levels despite progesterone supplementation in PCOS.

Dysregulation in Multiple Transcriptomic Endometrial Pathways Is Associated with Recurrent Implantation Failure and Recurrent Early Pregnancy Loss

Overlapping disease aetiologies associated with multiple altered biological processes have been identified that change the endometrial function leading to recurrent implantation failure (RIF) and recurrent early pregnancy loss (REPL). We aimed to provide a detailed insight into the nature of the biological malfunction and related pathways of differentially expressed genes in RIF and REPL. Endometrial biopsies were obtained from 9 women experiencing RIF, REPL and control groups. Affymetrix microarray analysis was performed to measure the gene expression level of the endometrial biopsies. Unsupervised clustering of endometrial samples shows scattered distribution of gene expression between the RIF, REPL and control groups. 2556 and 1174 genes (p value < 0.05, Fold change > 1.2) were significantly altered in the endometria of RIF and REPL patients’ group, respectively compared to the control group. Downregulation in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the differentially expressed genes (DEGs) in RIF and REPL including ribosome and oxidative phosphorylation pathways. Gene Ontology (GO) analysis revealed ribosomes and mitochondria inner membrane as the most significantly downregulated cellular component (CC) affected in RIF and REPL. Determination of the dysregulated genes and related biological pathways in RIF and REPL will be key in understanding their molecular pathology and of major importance in addressing diagnosis, prognosis, and treatment issues

The Endometrial Transcriptome of Metabolic and Inflammatory Pathways During the Window of Implantation Is Deranged in Infertile Obese Polycystic Ovarian Syndrome Women

Introduction and Aim: Obese women with polycystic ovarian syndrome (PCOS) have a reduced rate of spontaneous conception even when their cycles are ovulatory. Endometrial receptivity is an important factor for poor implantation and increased miscarriage rates. Mechanisms in which both pathologies modify the endometrium are not fully clarified. The aim of our study was to compare the endometrial transcriptomic profiles between infertile obese PCOS (O-PCOS) women and infertile normal weight subjects during the window of implantation in ovulatory menstrual cycles. Methods: We conducted a prospective transcriptomic analysis of the endometrium using RNA sequencing. In this way, potential endometrial mechanisms leading to the poor reproductive outcome in O-PCOS patients could be characterized. Endometrial samples during days 21-23 of the menstrual cycle were collected from infertile O-PCOS women (n = 11) and normal weight controls (n = 10). Subgroups were defined according to the ovulatory/anovulatory status in the natural cycles, and O-PCOS women were grouped into the O-PCOS ovulatory (O-PCOS-ovul) subgroup. RNA isolation, sequencing with library reparation, and subsequent RNAseq data analysis were performed. Results: Infertile O-PCOS patients had 610 differentially expressed genes (DEGs), after adjustment for multiple comparisons with normal weight infertile controls, related to obesity (MXRA5 and ECM1), PCOS (ADAMTS19 and SLC18A2), and metabolism (VNN1 and PC). In the ovulatory subgroup, no DEGs were found, but significant differences in canonical pathways and the upstream regulator were revealed. According to functional and upstream analyses of ovulatory subgroup comparisons, the most important biological processes were related to inflammation (TNFR1 signaling), insulin signaling (insulin receptor signaling and PI3/AKT), fatty acid metabolism (stearate biosynthesis I and palmitate biosynthesis I), and lipotoxicity (unfolded protein response pathway). Conclusions: We demonstrated that endometrial transcription in ovulatory O-PCOS patients is deranged in comparison with the control ovulatory endometrium. The most important pathways of differentiation include metabolism and inflammation. These processes could also represent potential mechanisms for poor embryo implantation, which prevent the development of a successful pregnancy. ClinicalTrials.gov ID: NCT03353948.

Molecular signature of immunological mechanism behind impaired endometrial receptivity in polycystic ovarian syndrome

Objective

Despite the treatment of anovulation, infertility is still one of the main complications in PCOS women during reproductive age, which appears to be mainly due to impaired uterine receptivity. This study investigated the transcriptome profiles of endometrium in PCOS patients and healthy fertile individuals as the control group.

Methods

Total mRNA was extracted from endometrial tissues of PCOS patients (n = 12) and healthy fertile individuals (n = 10) during the luteal phase. After cDNA synthesis, PCR array was performed using Human Female Infertility RT2 Profiler PCR Array kit (Qiagen, Cat.No: PAHS-164Z) for evaluating expression of 84 genes contributing to the female infertility.

Results

PCR Array data analysis identified significantly greater expression of CSF, IL11, IL15, IL1r1, IL1b, TNF, LIF, TNFRSF10B, TGFβ, C3, ITGA4 (Cd49d), SPP1, and Calca in PCOS women than in controls (P < 0.05). However, the expression of LIFR, C2, CD55, CFD, CALCA, LAM1, LAMC2, MMP2, MMP7, MMP9, ESR, SELL, ITGB3, and VCAM1 was significantly lower in PCOS group than in controls (P < 0.05). The results revealed dysregulation of immune-inflammatory molecules, complement activation and downregulation of IGF-I as well as adhesion molecules in PCOS group.

Conclusion

The findings of this study indicated some potential causes of reduced receptivity of endometrium thus compromising the fertility in PCOS patients.

Basic aspects of endometrial receptivity in PCOS patients

Polycystic Ovarian Syndrome (PCOS) is an endocrine disorder commonly affecting the reproductive capacity of women leading to infertility. PCOS-related infertility is majorly due to anovulation; however, it is not the only cause. The defective endometrium causing recurrent miscarriage and implantation failure can also be accountable for infertility in PCOS women. The unusual levels of hormones and their receptors in the PCOS endometrium have a hostile effect during WOI, making the microenvironment unfavorable for embryo implantation. To date, many studies have been performed to determine the role of candidate genes in endometrial receptivity but very limited data is available using whole genome approach. This review aims at summarizing the existing studies on the basic aspects of endometrial receptivity in PCOS. The review focuses on aberrant levels of hormones and their receptors in the endometrium, affecting the receptivity. Additionally, it explores the novel approach reviewing the effect on treatment options administered for ovulation induction in PCOS on their endometrial receptivity. Overall, this review will help us to understand the molecular milieu in PCOS endometrium and its effect on the receptivity potential. However, to have a thorough understanding of the mechanistic approach of hormonal imbalance in PCOS on endometrial receptivity, there is a need to give more weightage to genome-wide studies in the future. The current review will further guide us to formulate future studies using whole genome technologies for the assessment of endometrial receptivity in different cohorts of PCOS women, which may have future diagnostic implementations.

A Systematic Review and Integrated Bioinformatic Analysis of Candidate Genes and Pathways in the Endometrium of Patients With Polycystic Ovary Syndrome During the Implantation Window

Polycystic ovary syndrome (PCOS) is a common disorder with wide-ranging clinical heterogeneity that causes infertility. However, the comprehensive molecular mechanisms of PCOS in causing infertility is remaining unclear. Hence, a comprehensive literature search was conducted using PubMed, Scopus, EBSCOhost, and Science Direct. Medical Subject Heading (MeSH) terms like PCOS, gene expression, implantation window and endometrium were used as the keywords. From 138 studies retrieved, original articles with RNA profiling on human endometrial tissues in PCOS women during the implantation window were included. Study design, sample size, sample type, method, and differentially expressed genes (DEGs) were identified from all publications. The DEGs were analyzed using the software packages DAVID, STRING, and Cytoscape. Three studies that met inclusion criteria were included, and 368 DEGs were identified. Twelve significant clusters from the protein-protein interaction network (PPI) complex were found, and cluster 1 showed very high intermolecular interactions. Five candidate genes (AURKA, CDC25C, KIF23, KIF2C, and NDC80) were identified from the systematic review and integrated bioinformatics analysis. It is concluded that cell cycle is the fundamental biological processes that were dysregulated in the endometrium of PCOS women, affecting decidualization progression in the endometrium during the implantation window.

An Update on the Progress of Endometrial Receptivity in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a significant public health issue with diverse presentations, including reproductive, metabolic, and psychological disorders. Although problems with ovulation, metabolism, and hormonal imbalance can be pharmacologically improved, even the excellent quality of transferred embryos does not necessarily increase the pregnancy rate. Poor endometrial receptivity in women with PCOS perturbs endometrial decidualization and blastocyst implantation, increasing adverse pregnancy outcomes, such as miscarriage and poor embryonic development. The etiological and pathophysiological mechanisms involved in defective endometrial receptivity in women with PCOS have not been fully elucidated to date. Various contributing factors have been reported as primary causes of defective endometrial receptivity in women with PCOS, including metabolic alterations, inflammatory events, and some abnormally expressed endometrial molecular markers. However, few studies to date have investigated in depth the complex mechanisms underlying the compromised endometrial receptivity in women with PCOS. This article reviews recent reports mainly on metabolic alterations and some new endometrial molecular markers in order to collate the existing data and improve our understanding in this field. The aim was to discuss current novel insights on defective endometrial receptivity in women with PCOS in order to provide a theoretical basis for reducing adverse pregnancy outcomes and improving the live birth rate in PCOS.

The Disorders of Endometrial Receptivity in PCOS and Its Mechanisms

Polycystic ovary syndrome (PCOS) is a mysterious and complicated endocrine disease with the combination of metabolic, reproductive, psychological dysfunctions. Impaired endometrial receptivity and ovulation disorders/anovulation are both important causes of PCOS-related infertility. However, change in endometrium has never received the same attention as ovulatory dysfunction. Besides, putting emphasis on endometrial function may be more realistic for PCOS-related infertility, given the wide use of assisted reproductive technology. The present review focuses on the disorders of endometrial receptivity of patients with PCOS, summarizes the changes of the indicators of endometrial receptivity including leukemia inhibitory factor, homeobox genes A, pinopodes, αvβ3-integrin, and intercellular junctions and also analyzes the possible mechanisms of decreased endometrial receptivity and its relationship with the main endocrine and metabolic disorders of PCOS such as hyperandrogenism, inflammation, insulin resistance, and obesity. Despite several biomarkers have been found to be associated with decreased endometrial receptivity in PCOS, the clinical relevance of these findings still awaits future clarification.

The Complicated Effects of Extracellular Vesicles and Their Cargos on Embryo Implantation

As a rate-limiting step in pregnancy, embryo implantation is highly dependent on intercellular communication. Extracellular vesicles (EVs) are newly identified to be important in the course of intercellular communication. EVs have been isolated from a wide variety of biofluids and tissues, including plasma, liver, uterine, semen, embryo, etc. The present and future use of EVs not only as biomarkers, but also as targeting drug delivery system, is promisingly pave the way for advanced comprehension of implantation failure in reproductive diseases. However, as the precise mechanisms of EVs in embryo implantation has not been elucidated yet. Herein, we summarize the current knowledge on the diverse effects of EVs from various sources and their cargos such as microRNA, long non-coding RNA, protein, etc. on embryo implantation, and the potential mechanisms of EVs in reproductive diseases such as recurrent implantation failure, polycystic ovary syndrome and endometriosis. It is essential to note that many of the biologically plausible functions of EVs in embryo implantation discussed in present literatures still need further research in vivo.

Endometrial function in women with polycystic ovary syndrome: a comprehensive review

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. An endometrial component has been suggested to contribute to subfertility and poor reproductive outcomes in affected women.

OBJECTIVE AND RATIONALE

The aim of this review was to determine whether there is sufficient evidence to support that endometrial function is altered in women with PCOS, whether clinical features of PCOS affect the endometrium, and whether there are evidence-based interventions to improve endometrial dysfunction in PCOS women.

SEARCH METHODS

An extensive literature search was performed from 1970 up to July 2020 using PubMed and Web of Science without language restriction. The search included all titles and abstracts assessing a relationship between PCOS and endometrial function, the role played by clinical and biochemical/hormonal factors related to PCOS and endometrial function, and the potential interventions aimed to improve endometrial function in women with PCOS. All published papers were included if considered relevant. Studies having a specific topic/hypothesis regarding endometrial cancer/hyperplasia in women with PCOS were excluded from the analysis.

OUTCOMES

Experimental and clinical data suggest that the endometrium differs in women with PCOS when compared to healthy controls. Clinical characteristics related to the syndrome, alone and/or in combination, may contribute to dysregulation of endometrial expression of sex hormone receptors and co-receptors, increase endometrial insulin-resistance with impaired glucose transport and utilization, and result in chronic low-grade inflammation, immune dysfunction, altered uterine vascularity, abnormal endometrial gene expression and cellular abnormalities in women with PCOS. Among several interventions to improve endometrial function in women with PCOS, to date, only lifestyle modification, metformin and bariatric surgery have the highest scientific evidence for clinical benefit.

WIDER IMPLICATIONS

Endometrial dysfunction and abnormal trophoblast invasion and placentation in PCOS women can predispose to miscarriage and pregnancy complications. Thus, patients and their health care providers should advise about these risks. Although currently no intervention can be universally recommended to reverse endometrial dysfunction in PCOS women, lifestyle modifications and metformin may improve underlying endometrial dysfunction and pregnancy outcomes in obese and/or insulin resistant patients. Bariatric surgery has shown its efficacy in severely obese PCOS patients, but a careful evaluation of the benefit/risk ratio is warranted. Large scale randomized controlled clinical trials should address these possibilities.

Proteome analysis of endometrial tissue from patients with PCOS reveals proteins predicted to impact the disease

Polycystic ovary syndrome (PCOS) is a complex disease that causes an ovulatory infertility in approximately 10% of reproductive-age women. We searched for candidate proteins that might contribute to endometrial receptivity defects in PCOS patients, and result in adverse reproductive outcomes. Shotgun proteomics approach was used to investigate the proteome profile of the endometrium at the luteal phase in PCOS patients compared to healthy fertile individuals. Biological process and pathway analyses were conducted to categorize the proteins with differential expressions. Confirmation was performed for a number of proteins via immunoblotting in new samples. 150 proteins with higher abundance, and 46 proteins with lower abundance were identified in the endometrial tissue from PCOS patients compared to healthy fertile individuals. The proteins with higher abundance were enriched in protein degradation, cell cycle, and signaling cascades. Proteins with lower abundance in PCOS patients were enriched in extracellular matrix (ECM) composition and function, as well as the salvage pathway of purine biosynthesis. Metabolism was the most affected biological process with over 100 up-regulated, and approximately 30 down-regulated proteins. Our results indicate significant imbalances in metabolism, proteasome, cell cycle, ECM related proteins, and signaling cascades in endometrial tissue of PCOS, which may contribute to poor reproductive outcomes in these patients. We postulate that the endometria in PCOS patients may not be well-differentiated and synchronized for implantation. Possible roles of the above-mentioned pathways that underlie implantation failure in PCOS will be discussed. Our findings need to be confirmed in larger populations.

Establishment and Analysis of a Combined Diagnostic Model of Polycystic Ovary Syndrome with Random Forest and Artificial Neural Network

Polycystic ovary syndrome (PCOS) is one of the most common metabolic and reproductive endocrinopathies. However, few studies have tried to develop a diagnostic model based on gene biomarkers. In this study, we applied a computational method by combining two machine learning algorithms, including random forest (RF) and artificial neural network (ANN), to identify gene biomarkers and construct diagnostic model. We collected gene expression data from Gene Expression Omnibus (GEO) database containing 76 PCOS samples and 57 normal samples; five datasets were utilized, including one dataset for screening differentially expressed genes (DEGs), two training datasets, and two validation datasets. Firstly, based on RF, 12 key genes in 264 DEGs were identified to be vital for classification of PCOS and normal samples. Moreover, the weights of these key genes were calculated using ANN with microarray and RNA-seq training dataset, respectively. Furthermore, the diagnostic models for two types of datasets were developed and named neuralPCOS. Finally, two validation datasets were used to test and compare the performance of neuralPCOS with other two set of marker genes by area under curve (AUC). Our model achieved an AUC of 0.7273 in microarray dataset, and 0.6488 in RNA-seq dataset. To conclude, we uncovered gene biomarkers and developed a novel diagnostic model of PCOS, which would be helpful for diagnosis.

Uterine Fluid Proteins for Minimally Invasive Assessment of Endometrial Receptivity

CONTEXT

Clinically used endometrial (EM) receptivity assays are based on transcriptomic patterning of biopsies at midsecretory endometrium (MSE) to identify the possible displacement or disruption of window of implantation (WOI) in patients with recurrent implantation failure (RIF). However, biopsies are invasive and cannot be performed in the same cycle with in vitro fertilization embryo transfer, while uterine fluid (UF) analysis is considered minimally invasive and can immediately precede embryo transfer.

OBJECTIVE

To determine whether UF proteome can be used for WOI monitoring and whether it would highlight the etiology of RIF.

PATIENTS

Paired early secretory endometrial (ESE) and MSE UF samples from six fertile control women for discovery, and an additional 11 paired ESE/MSE samples from controls and 29 MSE samples from RIF patients for validation.

RESULTS

Using discovery mass spectrometry (MS) proteomics we detected 3158 proteins from secretory phase UF of which 367 undergo significant (q < 0.05) proteomic changes while transitioning from ESE to MSE. Forty-five proteins were further validated with targeted MS, and 21 were found to display similar levels between control ESE and RIF MSE, indicating displacement of the WOI. A panel of PGR, NNMT, SLC26A2 and LCN2 demonstrated specificity and sensitivity of 91.7% for distinguishing MSE from ESE samples. The same panel distinguished control MSE samples from RIF MSE with a 91.7% specificity and 96.6% sensitivity.

CONCLUSION

UF proteins can be used for estimating uterine receptivity with minimal invasiveness. Women with RIF appear to have altered MSE UF profiles that may contribute to their low IVF success rate.

Hyperandrogenism and insulin resistance induce gravid uterine defects in association with mitochondrial dysfunction and aberrant reactive oxygen species production

Women with polycystic ovary syndrome (PCOS) are at increased risk of miscarriage, which often accompanies the hyperandrogenism and insulin resistance seen in these patients. However, neither the combinatorial interaction between these two PCOS-related etiological factors nor the mechanisms of their actions in the uterus during pregnancy are well understood. We hypothesized that hyperandrogensim and insulin resistance exert a causative role in miscarriage by inducing defects in uterine function that are accompanied by mitochondrial-mediated oxidative stress, inflammation, and perturbed gene expression. Here, we tested this hypothesis by studying the metabolic, endocrine, and uterine abnormalities in pregnant rats after exposure to daily injection of 5α-dihydrotestosterone (DHT; 1.66 mg·kg body wt^-1·day^-1) and/or insulin (6.0 IU/day) from gestational day 7.5 to 13.5. We showed that whereas DHT-exposed and insulin-exposed pregnant rats presented impaired insulin sensitivity, DHT + insulin-exposed pregnant rats exhibited hyperandrogenism and peripheral insulin resistance, which mirrors pregnant PCOS patients. Compared with controls, hyperandrogenism and insulin resistance in the dam were associated with alterations in uterine morphology and aberrant expression of genes responsible for decidualization (Prl8a2, Fxyd2, and Mt1g), placentation (Fcgr3 and Tpbpa), angiogenesis (Flt1, Angpt1, Angpt2, Ho1, Ccl2, Ccl5, Cxcl9, and Cxcl10) and insulin signaling (Akt, Gsk3, and Gluts). Moreover, we observed changes in uterine mitochondrial function and homeostasis (i.e., mitochondrial DNA copy number and the expression of genes responsible for mitochondrial fusion, fission, biogenesis, and mitophagy) and suppression of both oxidative and antioxidative defenses (i.e., reactive oxygen species, Nrf2 signaling, and interactive networks of antioxidative stress responses) in response to the hyperandrogenism and insulin resistance. These findings demonstrate that hyperandrogenism and insulin resistance induce mitochondria-mediated damage and a resulting imbalance between oxidative and antioxidative stress responses in the gravid uterus.

Identification of mRNAs related to endometrium function regulated by lncRNA CD36-005 in rat endometrial stromal cells

BACKGROUND

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder in women of reproductive age and is commonly complicated by adverse endometrial outcomes. Long non-coding RNAs (lncRNAs) are a class of non-protein-coding transcripts that are more than 200 nucleotides in length. Accumulating evidence indicates that lncRNAs are involved in the development of various human diseases. Among these lncRNAs, lncRNA CD36-005 (CD36-005) is indicated to be associated with the pathogenesis of PCOS. However, the mechanisms of action of CD36-005 have not yet been elucidated.

METHODS

This study determined the CD36-005 expression level in the uteri of PCOS rat model and its effect on the proliferation activity of rat primary endometrial stromal cells. RNA sequencing (RNA-seq) and bioinformatics analysis were performed to detect the mRNA expression profiles and the biological pathways in which these differentially expressed mRNAs involved, after CD36-005 overexpression in the primary endometrial stromal cells. The differential expression of Hmgn5, Nr5a2, Dll4, Entpd1, Fam50a, and Brms1 were further validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

CD36-005 is highly expressed in the uteri of PCOS rat model and promotes the proliferation of rat primary endometrial stromal cells. A total of fifty-five mRNAs differentially expressed were identified in CD36-005 overexpressed stromal cells. Further analyses identified that these differentially expressed mRNAs participate in many biological processes and are associated with various human diseases. The results of qRT-PCR validation were consistent with the RNA-seq data.

CONCLUSIONS

These data provide a list of potential target mRNA genes of CD36-005 in endometrial stromal cells and laid a foundation for further studies on the molecular function and mechanism of CD36-005 in the endometrium.

Distinct changes in the proteome profile of endometrial tissues in polycystic ovary syndrome compared with healthy fertile women

RESEARCH QUESTION

What is the molecular basis of infertility related to uterine dysfunction in women with polycystic ovary syndrome (PCOS)?

DESIGN

In this study, differences in protein expression between PCOS and normal endometrium were identified using a proteomic approach based on two-dimensional electrophoresis (2-DE) coupled with mass spectrometry (MS). The proteome of endometrium were analysed during the proliferative (on day 2 or 3 before ovulation, n = 6) and luteal phases (on day 3-5 after ovulation, n = 6) from healthy women and PCOS patients (12-14 days after spontaneous bleeding, n = 12). The differentially expressed proteins were categorized based on the biological process using the DAVID bioinformatics resources.

RESULTS

Over 803 reproducible protein spots were detected on gels, and 150 protein spots showed different intensities between PCOS and normal women during the proliferative and luteal phases. MS analysis detected 70 proteins out of 150 spots. For four of the 70 proteins, 14-3-3 protein, annexin A5, SERPINA1 and cathepsin D, 2-DE results were validated and localized by Western blot and immunohistochemistry, respectively, and their gene expression profiles were confirmed by real-time quantitative PCR. The obtained results corresponded to the proteomic analysis. The differentially expressed proteins identified are known to be involved in apoptosis, oxidative stress, inflammation and the cytoskeleton.

CONCLUSIONS

The processes related to the differentially expressed proteins play important roles in fecundity and fecundability. The present study may reveal the cause of various endometrial aberrations as a limiting factor for achieving pregnancy in PCOS women.

A comparison of transcriptomic profiles in endometrium during window of implantation between women with unexplained recurrent implantation failure and recurrent miscarriage

The endometrium becomes receptive to the embryo only in the mid-luteal phase, but not in the other stages of the menstrual cycle. Endometrial factors play an important role in implantation. Women with recurrent miscarriage and recurrent implantation failure have both been reported to have altered expression of receptivity markers during the window of implantation. We aimed to compare the gene expression profiles of the endometrium in the window of implantation among women with unexplained recurrent implantation failures (RIF) and unexplained recurrent miscarriages (RM) by RNA sequencing (RNA-Seq). In total 20 patients (9 RIF and 11 RM) were recruited. In addition 4 fertile subjects were included as reference. Endometrium samples were precisely timed on the 7th day after luteal hormone surge (LH + 7). All the 24 endometrium samples were extracted for total RNA. The transcriptome was determined by RNA-Seq in the first 14 RNA samples (5 RIF, 6 RM and 3 fertile). Differentially expressed genes between RM and RIF were validated by quantitative real-time PCR (qPCR) in all 24 RNA samples (9 RIF, 11 RM and 4 fertile). Transcriptomic profiles of RM and RIF, but not control samples, were separated from each other by principle component analysis (PCA) and support vector machine (SVM). Complementary and coagulation cascades pathway was significantly up-regulated in RIF while down-regulated in RM. Differentially expressed genes C3, C4, C4BP, DAF, DF and SERPING1 in complement and coagulation cascade pathway between RM and RIF were further validated by qPCR. This study compared endometrial transcriptome among patients with RIF and RM in the window of implantation; it identified differential molecular pathways in endometrium between RIF and RM, which potentially affect the implantation process.

Downregulation of autophagy gene expression in endometria from women with polycystic ovary syndrome

Autophagy, a process of controlled cellular self-digestion, could be involved in cyclic remodeling of the human endometrium. We investigated endometrial mRNA expression of 23 autophagy-related (ATG) genes and transcription factors in healthy controls (n = 12) and anovulatory polycystic ovary syndrome (PCOS) patients (n = 24), as well as in their subgroup (n = 12) before and after metformin treatment. The mRNA levels of transcription factor forkhead box protein O1 (FOXO1) and several molecules involved in autophagosome formation (ATG13, RB1-inducible coiled-coil 1), autophagosome nucleation (ATG14, beclin 1, SH3-domain GRB2-like endophilin B1), autophagosome elongation (ATG3, ATG5, γ-aminobutyric acid receptor-associated protein - GABARAP), and delivery of ubiquitinated proteins to autophagosomes (sequestosome 1), were significantly reduced in anovulatory PCOS compared to healthy endometrium. Free androgen index, but not free estrogen index, insulin levels, or body mass index, negatively correlated with the endometrial expression of ATG3, ATG14, and GABARAP in PCOS patients. Treatment of PCOS patients with metformin (2 g/day for 3 months) significantly increased the endometrial mRNA levels of FOXO1, ATG3, and UV radiation resistance-associated gene. These data suggest that increased androgen availability in PCOS is associated with metformin-sensitive transcriptional downregulation of endometrial autophagy.

Altered expression of miRNAs in the uterus from a letrozole-induced rat PCOS model

Polycystic ovary syndrome (PCOS) causes female subfertility with ovarian disorders and may be associated with increased rate of early-pregnancy failure. Rat PCOS models were established using letrozole to understand the uterine pathogenesis of PCOS. The differential expression of microRNAs (miRNAs) was observed in rat uterus with PCOS. After estrous cycles were disrupted, significantly abnormal ovarian morphology and hormone level were observed in rats with PCOS. A total of 148 miRNAs differentially expressed were identified in the uterus from the letrozole-induced rat model compared with the control. These miRNAs included 111 upregulated miRNAs and 37 downregulated miRNAs. The differential expression of miR-484, miR-375-3p, miR-324-5p, and miR-223-3p was further confirmed by quantitative reverse transcription polymerase chain reaction. Bioinformatic analysis showed that these four miRNAs were predicted to regulate a large number of genes with different functions. Pathway analysis supported that target genes of miRNAs were involved in insulin secretion and signaling pathways, such as wnt, AMPK, PI3K-Akt, and Ras. These data indicated that miRNAs differentially expressed in rat uterus with PCOS may be associated with PCOS pathogenesis in the uterus. Our findings can help clarify the mechanism of uterine defects in PCOS.

MiR-125b regulates endometrial receptivity by targeting MMP26 in women undergoing IVF-ET with elevated progesterone on HCG priming day

On the women undergoing IVF-ET with elevated progesterone on human chorionic gonadotrophin priming, the assisted reproductive technology outcome is poor. But, due to the unknown mechanism of this process, no effective method has been found to overcome this difficulty. Here, we investigated the roles of miR-125b and its target gene, MMP26, in endometrial receptivity (ER) in these women. The expression of miR-125b was significantly up-regulated in EECs in women with elevated progesterone during the window of implantation, and it showed a progesterone-dependent effect in vitro. Similarly, the expression of miR-125b was significantly up-regulated in the preimplantation period, and was down-regulated in the implantation period and the post-implantation period in mouse EECs. In addition, miR-125b showed a greater decrease at implantation sites than it did at interimplantation sites. The luciferase report assay demonstrated that MMP26 is a target gene of miR-125b. And the expression profile of MMP26 showed an inverse relationship with miR-125b in vivo and in vitro. Overexpression of miR-125b in human EECs inhibited cell migration and invasion. Gain-of-function of miR-125b induced a significant decrease in the number of implantation sites. In conclusion, these data shed new light on how miR-125b triggers ER decline through the regulation of MMP26 function.

Apolipoprotein A1 as a novel anti-implantation biomarker in polycystic ovary syndrome: A case-control study

Background:

Women with polycystic ovary syndrome have lower pregnancy rates, possibly due to the decreased uterine receptivity. Successful implantation depends on protein networks that are essential for cross-talk between the embryo and endometrium. Apolipoprotein A1 has been proposed as a putative anti-implantation factor. In this study, we evaluated apolipoprotein A1 expression in human endometrial tissues.

Materials and Methods:

Endometrial apolipoprotein A1 messenger RNA (mRNA) and protein expression were investigated using quantitative real-time polymerase chain reaction (PCR) and Western blot. The distribution of apolipoprotein A1 was also detected by immunostaining. Samples were obtained from 10 patients with polycystic ovary syndrome and 15 healthy fertile women in the proliferative (on day 2 or day 3 before ovulation, n = 7) and secretory (on days 3-5 after ovulation, n = 8) phases.

Results:

Endometrial apolipoprotein A1 expression was upregulated in patients with polycystic ovary syndrome compared to normal subjects. However, apolipoprotein A1 expression in the proliferative phase was significantly higher than in the luteal phase (P value < 0.05).

Conclusion:

It seems that differentially expressed apolipoprotein A1 negatively affects endometrial receptivity in patients with polycystic ovary syndrome. The results showed that apolipoprotein A1 level significantly changes in the human endometrium during the menstrual cycle with minimum expression in the secretory phase, coincident with the receptive phase (window of implantation). Further studies are required to clarify the clinical application of this protein.

Efficacy of the Levonorgestrel-Releasing Intrauterine System on IVF-ET Outcomes in PCOS With Simple Endometrial Hyperplasia

OBJECTIVE

This study investigated the in vitro fertilization (IVF) outcome of levonorgestrel-releasing intrauterine system (LNG-IUS) pretreatment for simple endometrial hyperplasia (EH) in patients with polycystic ovary syndrome (PCOS) undergoing IVF embryo transfer (IVF-ET).

METHODS

One hundred ninety patients with PCOS and simple EH without cytologic atypia were allocated randomly to 2 independent arms, that is, the LNG-IUS group (90 patients) and the non-LNG-IUS group (100 patients). Four hundred fourteen patients with PCOS without endometrial disease comprised the control group. Each patient was reevaluated by transvaginal ultrasonography (TVS) and endometrial biopsy after 6 months. For each patient, IVF outcome measures, such as number of recombinant follicle-stimulating hormone, endometrial thickness on human chorionic gonadotropin (HCG) day, hormone levels (progesterone, luetinizing hormone, and serum estradiol) on HCG day, number of oocytes, fertilization rate, clinical pregnancy rate, and miscarriage rate were compared among the 3 groups.

RESULTS

In general, the 3 groups did not differ with respect to the main clinical and biochemical data. After 6 months, patients in LNG-IUS group had an EH resolution rate of 87.77%. In the non-LNG-IUS group, the resolution rate was 15.00%, and 3% of these patients showed progression of EH. The clinical pregnancy rates in the non-LNG-IUS group were significantly lower (28.04%) than that in the LNG-IUS group (46.06%) and the control group (44.65%). The miscarriage rate was highest in the non-LNG-IUS group, but no significant difference in miscarriage rate existed among the 3 groups.

CONCLUSION

The study illustrates that the LNG-IUS can be safely used for 6 months as a treatment for patients with PCOS and simple EH. Additionally, use of the LNG-IUS can increase the clinical pregnancy rates and implantation rates of patients with PCOS and simple EH who undergo gonadotropin-releasing hormone agonist IVF-ET protocols.

Letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in women with polycystic ovarian syndrome: a pilot study

OBJECTIVE

To study the efficiency of letrozole, an aromatase inhibitor, in endometrial preparation for cryopreserved-thawed embryo transfer (FET) in women with polycystic ovarian syndrome (PCOS).

DESIGN

Retrospective observational study.

PATIENTS

One hundred and twenty patients with PCOS who met the inclusion criteria for the study.

MEASUREMENTS

We assessed in vitro fertilization outcomes in one hundred and twenty patients with PCOS (148 cycles) who were prepared for and underwent FET between June 2011 and December 2012. Patients were prepared for FET using artificial hormone cycles induced with oestrogen and progesterone supplementation (n = 76), letrozole stimulation (n = 40) or hMG stimulation (n = 32).

RESULTS

There were no differences in demographic characteristics between the groups, except that the letrozole group had a higher incidence of embryo transfer failure in the past. The letrozole stimulation group had a significantly higher maximal endometrial thickness and significantly higher rates of clinical pregnancy per transfer, ongoing pregnancy per transfer and implantation, compared with the artificial and hMG stimulation groups. Differences in these parameters between the artificial and hMG stimulation groups were not significant.

CONCLUSION

Using letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in patients with PCOS may be associated with better outcomes than using hormonal manipulation or hMG stimulation.

Genetic investigation into ethnic disparity in polycystic ovarian syndrome

Polycystic ovarian syndrome is universally the most common endocrinopathy in women of reproductive age. It is characterized by composite clinical phenotypes reflecting the reproductive impact of ovarian dysfunction (androgen excess, oligo-/anovulation, polycystic ovary) and metabolic abnormalities (insulin resistance, obesity) with widely varying symptoms among the affected. Studies have shown a clear pattern of disparity in clinical manifestations of its component phenotypes across ethnic populations. Recent genetic association studies suggested differential genetic background that could contribute to the observed ethnic disparity. We summarize the current status in genetic studies of the disorder in different populations with a focus on ethnicity. Especially, we highlight and discuss the applications of recent developments in DNA sequencing, global transcriptional and epigenetic profiling that could help to unravel the molecular basis of the interethnic difference in the pathogenesis of the syndrome. It is hoped that identification and characterization of population-specific structural genetic and functional genomic patterns could help to not only deepen our understanding of the aetiology but also develop more efficient strategies for treatment and prevention of polycystic ovarian syndrome.

Endometrium in women with polycystic ovary syndrome during the window of implantation

The human endometrium undergoes to a complex series of proliferative and secretory changes in each menstrual cycle and displays only a short period of receptivity, known as the "window of implantation", necessary for the implantation of the blastocyst in the uterus. The implantation process occurs in a sequential manner, leading to the establishment of pregnancy. Morphofunctional changes during this period may prevent or hinder the implantation. For this reason, the study of the endometrium at this stage is important for the improvement of therapies that may interfere with the mechanisms involved in maternal-embryonic interaction. Several gynecological disorders, including polycystic ovary syndrome (PCOS), are associated with decreased fertility and uterine receptivity. In spite of recent advances in assisted reproduction techniques, allowing the selection of high quality embryos, the implantation rate remains low and has not increased enough in recent decades. This article aims at reviewing the endometrial aspects of the "window of implantation" in women with polycystic ovary syndrome, focusing mainly on adhesion molecules. For that purpose, we analyzed 105 articles published in journals indexed in PubMed in the last 50 years (up to May 2011). In conclusion, the endometrial receptivity seems to be the major limiting factor for the establishment of pregnancy in a large number of gynecological diseases, including PCOS, and treatment to improve implantation rates is likely to be taken towards this direction.

The role of androgens and the androgen receptor in cycling endometrium

Androgens and the androgen receptor (AR) are not only required for male reproductive function, they are also essential for female reproductive physiology. Widely expressed in female reproductive tissues, AR levels fluctuate in a regulated manner in the cycling endometrium. Female androgen production depends on the adrenal glands and expression of key enzymes in the endometrium that facilitate local androgen biosynthesis and conversion. Moreover, levels of circulating androgens, in women of reproductive age, fluctuate in a cycle-dependent manner and a mid-cycle peak is associated with conception. AR and androgen signalling have a decisive role in the differentiation of human endometrial stromal cells into decidual cells. Compelling evidence for androgen signalling in the regulation of endometrial function pertaining to implantation and pregnancy is provided by epidemiological studies demonstrating a strong association between polycystic ovary syndrome, premature ovarian failure or advanced maternal age and adverse pregnancy outcome. Thus, androgen signalling is an essential component of normal endometrial physiology and its perturbation is associated with reproductive failure.

Endometrial abnormality in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy associated with infertility and metabolic disorder in women of reproductive age. Although the clinical and biochemical features are heterogeneous with individuals, the most widely accepted clinical characteristics of PCOS are oligo- or anovulation combined with hyperandrogenism. With the higher rate of implantation failure after induction of ovulation or higher risk of spontaneous miscarriage after pregnancy, the reduced fertility is apparently attributed not only to anovulation but also to endometrial dysfunction in patients with PCOS. Here we review the features of the endometrial abnormalities in women with PCOS. The ability to improve the endometrial functions is of potential therapeutic targets to increase reproductive outcome of women with PCOS.

Global alteration in gene expression profiles of deciduas from women with idiopathic recurrent pregnancy loss

Recurrent pregnancy loss (RPL) occurs in ∼5% of women. However, the etiology is still poorly understood. Defects in decidualization of the endometrium during early pregnancy contribute to several pregnancy complications, such as pre-eclampsia and intrauterine growth restriction (IUGR), and are believed to be important in the pathogenesis of idiopathic RPL. We performed microarray analysis to identify gene expression alterations in the deciduas of idiopathic RPL patients. Control patients had one antecedent term delivery, but were undergoing dilation and curettage for current aneuploid miscarriage. Gene expression differences were evaluated using both pathway and gene ontology (GO) analysis. Selected genes were validated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). A total of 155 genes were found to be significantly dysregulated in the deciduas of RPL patients (>2-fold change, P < 0.05), with 22 genes up-regulated and 133 genes down-regulated. GO analysis linked a large percentage of genes to discrete biological functions, including immune response (23%), cell signaling (18%) and cell invasion (17.1%), and pathway analysis revealed consistent changes in both the interleukin 1 (IL-1) and IL-8 pathways. All genes in the IL-8 pathway were up-regulated while genes in the IL-1 pathway were down-regulated. Although both pathways can promote inflammation, IL-1 pathway activity is important for normal implantation. Additionally, genes known to be critical for degradation of the extracellular matrix, including matrix metalloproteinase 26 and serine peptidase inhibitor Kazal-type 1, were also highly up-regulated. In this first microarray approach to decidual gene expression in RPL patients, our data suggest that dysregulation of genes associated with cell invasion and immunity may contribute significantly to idiopathic recurrent miscarriage.

Does metformin influence the insulin-, IGF I- and IGF II-receptor gene expression and Akt phosphorylation in human decidualized endometrial stromal cells?

OBJECTIVE

To assess the effects of metformin on insulin-, IGF I-, and IGF II-receptor gene expression and Akt phosphorylation in decidualized human endometrial stromal cells (ESC) after stimulation with insulin, IGF I and II.

STUDY DESIGN

ESC were isolated from healthy, regularly cycling women and after two passages decidualized with estrogen/progesterone±metformin. Cells were incubated with insulin, IGF I or IGF II for 1, 5, and 10 min to assess Akt phosphorylation by Western blot. To investigate the insulin-, IGF I- and IGF II-receptor gene expression ESC were incubated with insulin, IGF I or IGF II for 6 and 24h.

RESULTS

Insulin- and IGF I-receptor gene expression in ESC changed significantly after incubation with insulin, IGF I or IGF II. This was further augmented in metformin pretreated cells, while IGF II-receptor gene expression changed particularly after pretreatment with metformin. Akt phosphorylation peaked after 5 min insulin, IGF I and IGF II stimulation in ESC in both control (control 0.08 ± 0.03 vs. insulin 0.74 ± 0.19, IGF I 0.68 ± 0.22, IGF II 0.53 ± 0.13, p<0.05) and metformin pretreated cells (control 0.03 ± 0.01 vs. insulin 0.75 ± 0.11, IGF I 0.74 ± 0.15, IGF II 0.67 ± 0.09, p<0.005). However, there was no significant difference between the control and metformin pretreated group.

CONCLUSION

Insulin, IGF I and IGF II lead to changes in their receptor gene expression and induced Akt phosphorylation in ESC. These effects were further highlighted in the presence of metformin.

Progesterone resistance in PCOS endometrium: a microarray analysis in clomiphene citrate-treated and artificial menstrual cycles

CONTEXT

Polycystic ovary syndrome (PCOS), the most common endocrinopathy of reproductive-aged women, is characterized by ovulatory dysfunction and hyperandrogenism.

OBJECTIVE

The aim was to compare gene expression between endometrial samples of normal fertile controls and women with PCOS.

DESIGN AND SETTING

We conducted a case control study at university teaching hospitals.

PATIENTS

Normal fertile controls and women with PCOS participated in the study.

INTERVENTIONS

Endometrial samples were obtained from normal fertile controls and from women with PCOS, either induced to ovulate with clomiphene citrate or from a modeled secretory phase using daily administration of progesterone.

MAIN OUTCOME MEASURE

Total RNA was isolated from samples and processed for array hybridization with Affymetrix HG U133 Plus 2 arrays. Data were analyzed using GeneSpring GX11 and Ingenuity Pathways Analysis. Selected gene expression differences were validated using RT-PCR and/or immunohistochemistry in separately obtained PCOS and normal endometrium.

RESULTS

ANOVA analysis revealed 5160 significantly different genes among the three conditions. Of these, 466 were differentially regulated between fertile controls and PCOS. Progesterone-regulated genes, including mitogen-inducible gene 6 (MIG6), leukemia inhibitory factor (LIF), GRB2-associated binding protein 1 (GAB1), S100P, and claudin-4 were significantly lower in PCOS endometrium; whereas cell proliferation genes, such as Anillin and cyclin B1, were up-regulated.

CONCLUSIONS

Differences in gene expression provide evidence of progesterone resistance in midsecretory PCOS endometrium, independent of clomiphene citrate and corresponding to the observed phenotypes of hyperplasia, cancer, and poor reproductive outcomes in this group of women.

Variation in hyaluronan-binding protein 2 (HABP2) promoter region is associated with unexplained female infertility

We set up to analyze polymorphisms in hyaluronan-binding protein 2 (HABP2) gene in healthy fertile women (n = 158) and in women with unexplained infertility (n = 116) and to investigate the potential role of HABP2 in receptive endometrium. Minor rs1157916 A and the major rs2240879 A alleles together with AA genotypes were significantly less frequent in infertile women than in controls. Immunohistochemistry analysis of endometrial HABP2 expression at the time of implantation identified significantly lower HABP2 protein level in infertile women in stroma and vessels than in fertile women. Migration assay analysis of cultured trophoblast and endothelial cells toward HABP2 protein referred to the function of HABP2 in endometrial endothelial cells. In conclusion, our results indicate that polymorphisms in the regulatory region of HABP2 gene could influence gene expression levels in the receptive endometrium and could thereby be one reason for infertility complications in women with unexplained infertility. Additionally, HABP2 protein involvement in endometrial angiogenesis is proposed.

Altered spatiotemporal expression of collagen types I, III, IV, and VI in Lpar3-deficient peri-implantation mouse uterus

Lpar3 is upregulated in the preimplantation uterus, and deletion of Lpar3 leads to delayed uterine receptivity in mice. Microarray analysis revealed that there was higher expression of Col3a1 and Col6a3 in the Preimplantation Day 3.5 Lpar3(-/-) uterus compared to Day 3.5 wild-type (WT) uterus. Since extracellular matrix (ECM) remodeling is indispensable during embryo implantation, and dynamic spatiotemporal alteration of specific collagen types is part of this process, this study aimed to characterize the expression of four main uterine collagen types: fibril-forming collagen (COL) I and COL III, basement membrane COL IV, and microfibrillar COL VI in the peri-implantation WT and Lpar3(-/-) uterus. An observed delay of COL III and COL VI clearance in the Lpar3(-/-) uterus may be associated with higher preimplantation expression of Col3a1 and Col6a3. There was also delayed clearance of COL I and delayed deposition of COL IV in the decidual zone in the Lpar3(-/-) uterus. These changes were different from the effects of 17beta-estradiol and progesterone on uterine collagen expression in ovariectomized WT uterus, indicating that the altered collagen expression in Lpar3(-/-) uterus is unlikely to be a result of alterations in ovarian hormones. Decreased expression of several genes encoding matrix-degrading metallo- and serine proteinases was observed in the Lpar3(-/-) uterus. These results demonstrate that pathways downstream of LPA3 are involved in the dynamic remodeling of ECM in the peri-implantation uterus.

Endometrial gene expression analysis at the time of embryo implantation in women with unexplained infertility

Successful embryo implantation depends on the quality of the embryo, as well as on the receptivity of the endometrium. The aim of this study was to investigate the endometrial gene expression profile in women with unexplained infertility in comparison with fertile controls at the time of embryo implantation in order to find potential predictive markers of uterine receptivity and to identify the molecular mechanisms of infertility. High-density oligonucleotide gene arrays, comprising 44 000 gene targets, were used to define the endometrial gene expression profile in infertile (n = 4) and fertile (n = 5) women during the mid-secretory phase (day LH + 7). Microarray results were validated using real-time PCR. Analyses of expression data were carried out using non-parametric methods. Hierarchical clustering and principal component analysis showed a clear distinction in endometrial gene expression between infertile and fertile women. In total we identified 145 significantly (>3-fold change) up-regulated and 115 down-regulated genes in infertile women versus controls. Via Database for Annotation, Visualization and Integrated Discovery functional analysis we detected a substantial number of dysregulated genes in the endometria of infertile women, involved in cellular localization (21.1%) and transport (18.8%) and transporter activity (13.1%) and with major localization in extracellular regions (19.2%). Ingenuity Pathways Analysis of the gene list showed dysregulation of gene pathways involved in leukocyte extravasation signalling, lipid metabolism and detoxification in the endometria of infertile women. In conclusion, endometrial gene expression in women with unexplained infertility at the time of embryo implantation is markedly different from that in fertile women. These results provide new information on genes and pathways that may have functional significance as regards to endometrial receptivity and subsequent embryo implantation.