HOX gene expression is altered in the endometrium of women with endometriosis

In Vitro Gene Expression Profiling of Quantum Molecular Resonance Effects on Human Endometrium Models: A Preliminary Study

OBJECTIVES

The identification of methods to improve the endometrial receptivity (ER) is increasingly of interest. The effect of the electromagnetic field associated with Quantum Molecular Resonance (QMR) on ER was investigated here.

METHODS

Ishikawa cells were used to evaluate the effects of QMR both on the expression of a group of genes involved in ER, i.e., HOXA10, HOXA11, LIF, ITGB3, and ITGAV, and on cell toxicity. Endometrial samples were obtained from six patients during routine diagnostic procedures, four of which were subsequently used to assess the transcriptional response to QMR through microarray.

RESULTS

Compared to unexposed controls, a single exposure of Ishikawa cells to QMR for 20 min was associated with a significant and power-dependent up-regulation of all the selected ER-related genes up to 8 power units (PU). Repeated exposure to QMR, up to three consecutive days, showed a significant up-regulation of all the selected genes at power values of 4 PU, from day two onwards. Negligible cytotoxicity was observed. Gene set enrichment analysis, on microarray data of endometrial biopsies stimulated for three consecutive days at 4 PU, showed a significant enrichment of specific gene sets, related to the proteasome system, the cell adhesion, the glucocorticoid receptor, and cell cycle pathways.

CONCLUSIONS

Our results suggest a possible favorable impact of QMR on ER.

Endometrial Receptivity-Lessons from "Omics"

The window of implantation (WOI) is a critical phase of the menstrual cycle during which the endometrial lining becomes receptive and facilitates embryo implantation. Drawing on findings from various branches of "omics", including genomics, epigenomics, transcriptomics, proteomics, lipidomics, metabolomics, and microbiomics, this narrative review aims to (1) discuss mechanistic insights on endometrial receptivity and its implication in infertility; (2) highlight advances in investigations for endometrial receptivity; and (3) discuss novel diagnostic and therapeutic strategies that may improve reproductive outcomes.

Dual inhibition of AKT and ERK1/2 pathways restores the expression of progesterone Receptor-B in endometriotic lesions through epigenetic mechanisms

Endometriosis is an estrogen-dependent and progesterone-resistant gynecological inflammatory disease of reproductive-age women. Progesterone resistance, loss of progesterone receptor -B (PR-B) in the stromal cells of the endometrium, is one of the hallmarks of endometriosis and a major contributing factor for infertility in endometriosis patients. Loss of PR-B in the stromal cells of the endometriotic lesions poses resistance to the success of progesterone-based therapy. The working hypothesis is that PR-B is hypermethylated and epigenetically silenced, and inhibition of AKT and ERK1/2 pathways will decrease the hypermethylation, reverse the epigenetic silencing, and restore the expression of PR-B via DNA methylation and histone modification mechanisms in the endometriotic lesions. The objectives are to (i) determine the effects of dual inhibition of AKT and ERK1/2 pathways on the expression of PR-B and DNA methylation and histone modification protein machinery in the endometriotic lesions and (ii) identify the underlying epigenetic mechanisms of PR-B restoration in the endometriotic lesions. The results indicate that dual inhibition of AKT and ERK1/2 pathways decreases the hypermethylation, reverses the epigenetic silencing, and restores the expression of PR-B via DNA methylation and H3K9 and H3K27 methylation mechanisms in the endometriotic lesions or endometriotic stromal cells of human origin. These results support the novel concept that restored expression of PR-B in the endometriotic lesions and endometrium may improve the clinical outcome of progesterone therapy in endometriosis patients.

Effect of environmental air pollutants on placental function and pregnancy outcomes: a molecular insight

Air pollution has become a major health concern, particularly for vulnerable populations such as the elderly, children, and pregnant women. Studies have reported a strong association between prenatal exposure to air pollutants and adverse pregnancy outcomes, including lower birth weight, reduced fetal growth, and an increased frequency of preterm births. This review summarizes the harmful effects of air pollutants, such as particulate matter, on pregnancy and outlines the mechanistic details associated with these adverse outcomes. Particulate pollutant matter may be able to cross the placenta barrier, and alterations in placental functions are central to the detrimental effects of these pollutants. In addition to associations with preeclampsia and gestational hypertension, air pollutants also induce oxidative stress, inflammation, and epigenetic alteration in the placenta. These pollutants can also affect placental homeostasis and endocrine function, contributing to pregnancy complications and possible transgenerational effects. Prenatal air pollution exposure has been linked to reduced cognitive and motor function in infants and newborns, increasing the predisposition to autism spectrum disorders and other neuropsychiatric disorders. This review also summarizes the use of various animal models to study the harmful effects of air pollution on pregnancy and postnatal outcomes. These findings provide valuable insight into the molecular events associated with the process and can aid in risk mitigation and adopting safety measures. Implementing effective environmental protocols and taking appropriate steps may reduce the global disease burden, particularly for developing nations with poor regulatory compliance and large populations of pregnant women.

Affinity-tagged SMAD1 and SMAD5 mouse lines reveal transcriptional reprogramming mechanisms during early pregnancy

Endometrial decidualization, a prerequisite for successful pregnancies, relies on transcriptional reprogramming driven by progesterone receptor (PR) and bone morphogenetic protein (BMP)-SMAD1/SMAD5 signaling pathways. Despite their critical roles in early pregnancy, how these pathways intersect in reprogramming the endometrium into a receptive state remains unclear. To define how SMAD1 and/or SMAD5 integrate BMP signaling in the uterus during early pregnancy, we generated two novel transgenic mouse lines with affinity tags inserted into the endogenous SMAD1 and SMAD5 loci (Smad1HA/HA and Smad5PA/PA). By profiling the genome-wide distribution of SMAD1, SMAD5, and PR in the mouse uterus, we demonstrated the unique and shared roles of SMAD1 and SMAD5 during the window of implantation. We also showed the presence of a conserved SMAD1, SMAD5, and PR genomic binding signature in the uterus during early pregnancy. To functionally characterize the translational aspects of our findings, we demonstrated that SMAD1/5 knockdown in human endometrial stromal cells suppressed expressions of canonical decidual markers (IGFBP1, PRL, FOXO1) and PR-responsive genes (RORB, KLF15). Here, our studies provide novel tools to study BMP signaling pathways and highlight the fundamental roles of SMAD1/5 in mediating both BMP signaling pathways and the transcriptional response to progesterone (P4) during early pregnancy.

Affinity-tagged SMAD1 and SMAD5 mouse lines reveal transcriptional reprogramming mechanisms during early pregnancy

Endometrial decidualization, a prerequisite for successful pregnancies, relies on transcriptional reprogramming driven by progesterone receptor (PR) and bone morphogenetic protein (BMP)-SMAD1/SMAD5 signaling pathways. Despite their critical roles in early pregnancy, how these pathways intersect in reprogramming the endometrium into a receptive state remains unclear. To define how SMAD1 and/or SMAD5 integrate BMP signaling in the uterus during early pregnancy, we generated two novel transgenic mouse lines with affinity tags inserted into the endogenous SMAD1 and SMAD5 loci (Smad1HA/HA and Smad5PA/PA). By profiling the genome-wide distribution of SMAD1, SMAD5, and PR in the mouse uterus, we demonstrated the unique and shared roles of SMAD1 and SMAD5 during the window of implantation. We also showed the presence of a conserved SMAD1, SMAD5, and PR genomic binding signature in the uterus during early pregnancy. To functionally characterize the translational aspects of our findings, we demonstrated that SMAD1/5 knockdown in human endometrial stromal cells suppressed expressions of canonical decidual markers (IGFBP1, PRL, FOXO1) and PR-responsive genes (RORB, KLF15). Here, our studies provide novel tools to study BMP signaling pathways and highlight the fundamental roles of SMAD1/5 in mediating both BMP signaling pathways and the transcriptional response to progesterone (P4) during early pregnancy.

Downregulation of homeobox A1 in human granulosa cells is involved in diminished ovarian reserve through promoting cell apoptosis and mitochondrial dysfunction

Granulosa cell apoptosis contributes to the occurrence of diminished ovarian reserve (DOR). HOXA1, belonging to the HOX gene family, is involved in regulating cancer cell apoptosis. However, whether HOXA1 participates in the granulosa cell apoptosis in DOR patients remains to be elucidated. In the current study, we demonstrated the differential transcriptomic landscape of granulosa cells in DOR patients compared to that in the controls and identified decreased expression of the HOXA1 gene. Meanwhile, we found that HOXA1 was a gonadotropin-response gene, in which FSH could promote its expression, whereas LH inhibited HOXA1 expression in human granulosa cells. CCK-8 assay, flow cytometry and TUNEL staining results showed that inhibition of endogenous HOXA1 expression promoted human granulosa cell apoptosis. Moreover, knockdown of HOXA1 increased Bax while reducing Bcl2 protein expression. Furthermore, we found a total of 947 differentially expressed genes (DEGs), including 426 upregulated genes and 521 downregulated genes using transcriptome sequencing technology. Enrichment analysis results showed that the DEGs were involved in apoptosis and mitochondrial function-related signaling pathways. Knockdown of HOXA1 impaired mitochondrial functions, exhibiting increased reactive oxygen species (ROS) and cytoplasmic Ca2+ levels, decreased mitochondrial membrane potential, ATP production and mitochondrial DNA (mtDNA) copy number, and abnormal mitochondrial cristae. Our findings demonstrated that aberrantly reduced HOXA1 expression induced granulosa cell apoptosis in DOR patients and impaired mitochondrial function, which highlighted the potential role of HOXA1 in the occurrence of DOR and provided new insight for the treatment of DOR.

A Systematic Review of Epigenetics of Endometriosis

Objective

To assess the current literature evaluating the epigenetics of endometriosis in humans.

Evidence Review

A systematic review was conducted in accordance with the PRISMA guidelines within PubMed, EBSCOhost, Cochrane Library, Embase, Scopus, and Web of Science Core Collection. A comprehensive search strategy was developed by a data informationist. Observational and interventional studies assessing epigenetics in humans published in English up to January 15th, 2023, were included. Two reviewers independently screened studies evaluating the role of epigenetics in endometriosis. The risk of bias was assessed using Cochrane RoB 2.0 tool and the Newcastle-Ottawa scale. Extracted data were analyzed descriptively.

Results

We identified 18.639 studies, of which 57 were included, comprising 1.623 patients with endometriosis and 1.243 controls. Among the 57 studies included, 50 (88%) were case-control studies, and 7 (12%) were cross-sectional. Fifty-nine percent of the studies were Asian, 25% were from America, 14% were European, and 2% were from Africa. Acetylation and methylation were the two main key histone modifications that were centered in this review. Accordingly, we classified the studies as those focusing on genome-wide methylation and those on histone acetylation. Several studies identified an association between endometriosis and hypermethylated genes, including the PGR-B, SF-1, and RASSF1A. The genes HOXA10, COX-2, IL-12B, and GATA6 were found to be hypomethylated in endometriotic tissue by several studies. In regards to histone modification, multiple studies reported that the acetylation levels of histones H3 and H4 affect multiple genes associated with endometriosis. In addition, HDAC2 was found to be elevated in endometriosis patients in two studies.

Conclusion

Several studies reported a significant difference between specific genes' methylation levels in endometrial biopsies and normal tissue, which suggests that DNA methylation may play an important role in the modulation of the genotype in endometriotic tissue. Acetylation and methylation are the two key histone modifications leading to differential gene expression in endometriotic tissues. The alterations in gene expression reported by the 57 studies can have direct implications on cell cycle growth, cell cycle arrest, and apoptosis and, therefore, might play a key role in the pathogenesis of endometriosis. This review offers insight that histone modifications need further research to evaluate their role as potential biomarkers and treatment targets for endometriosis. Although several key similarities were reported, there were some disagreements among the results, which might be attributable to the heterogeneity between studies. Further research with a more robust standardization is needed to validate the epigenetic changes in endometriosis.

Fertility Preservation in Women with Endometriosis

Several mechanisms have been implicated in the pathogenesis of endometriosis-related infertility. For patients considering surgery, the risk of iatrogenic injury is among the most important factors in the context of fertility preservation, along with age and individual reproductive goals. In the case of endometrioma excision, evidence overwhelmingly demonstrates the negative impact of surgery on ovarian reserve, with significant reductions in antimullerian hormone (up to 30% in unilateral versus up to 44% in bilateral endometriomas). The surgical endometriosis patient should be thoroughly counseled regarding fertility preservation and discussion should include tissue, embryo, and oocyte cryopreservation options. For the latter, data support cryopreservation of 10-15 oocytes in women ≤35 years and over 20 for those >35 years for a realistic chance to achieve one or more live births. When performing surgical interventions for endometriosis, reproductive surgeons should employ fertility-conserving surgical methods to reduce the likelihood of postoperative iatrogenic diminished ovarian reserve.

New concepts on the etiology of endometriosis

Endometriosis is a serious, chronic disorder where endometrial tissue grows outside the uterus, causing severe pelvic pain and infertility. It affects 11% of women. Endometriosis is a multifactorial disorder of unclear etiology, although retrograde menstruation plays a major role. It has a genetic component with over 40 genetic risk factors mapped, although their mechanism of action is still emerging. New evidence suggests a role for retrograde menstruation of endometrial stem/progenitor cells, now that identifying markers of these cells are available. Recent lineage tracing and tissue clearing microscopy and 3D reconstruction has provided new understanding of endometrial glandular structure, particularly the horizontal orientation and interconnection of basalis glands. New sequencing technologies, particularly whole genome DNA sequencing are revealing somatic mutations, including in cancer driver genes, in normal and eutopic endometrium of patients with endometriosis, as well as ectopic endometriotic lesions. Methylome sequencing is offering insight into the regulation of genes and the role of the environmental factors. Single cell RNA sequencing reveals the transcriptome of individual endometrial cells, shedding new light on the diversity and range of cellular subpopulations of the major cell types present in the endometrium and in endometriotic lesions. New endometrial epithelial organoid cultures replicating glandular epithelium are providing tractable models for studying endometriosis. Organoids derived from menstrual fluid offer a non-invasive source of endometrial tissue and a new avenue for testing drugs and developing personalized medicine for treating endometriosis. These new approaches are rapidly advancing our understanding of endometriosis etiology.

Aberrant epigenetic regulation of estrogen and progesterone signaling at the level of endometrial/endometriotic tissue in the pathomechanism of endometriosis

Endometriosis is a term referring to a condition whereby the endometrial tissue is found outside the uterine cavity. This progressive and debilitating condition affects up to 15% of women of reproductive age. Due to the fact that endometriosis cells may express estrogen receptors (ERα, Erβ, GPER) and progesterone (P4) receptors (PR-A, PR-B), their growth, cyclic proliferation, and breakdown are similar to the processes occurring in the endometrium. The underlying etiology and pathogenesis of endometriosis are still not fully explained. The retrograde transport of viable menstrual endometrial cells with the retained ability to attach within the pelvic cavity, proliferate, differentiate and invade into the surrounding tissue explains the most widely accepted implantation theory. Endometrial stromal cells (EnSCs) with clonogenic potential constitute the most abundant population of cells within endometrium that resemble the properties of mesenchymal stem cells (MSCs). Accordingly, formation of the endometriotic foci in endometriosis may be due to a kind of EnSCs dysfunction. Increasing evidence indicates the underestimated role of epigenetic mechanisms in the pathogenesis of endometriosis. Hormone-mediated epigenetic modifications of the genome in EnSCs or even MSCs were attributed an important role in the etiopathogenesis of endometriosis. The roles of excess estrogen exposure and P4 resistance were also found to be crucial in the development of epigenetic homeostasis failure. Therefore, the aim of this review was to consolidate the current knowledge regarding the epigenetic background of EnSCs and MSCs and the changed properties due to estrogen/P4 imbalances in the context of the etiopathogenesis of endometriosis.

Decreased Glycolysis at Menstruation is Associated with Increased Menstrual Blood Loss

Heavy menstrual bleeding (HMB) is common and severely affects the quality of life of the afflicted women. While HMB is known to be caused by impaired endometrial repair after menstruation, its more proximate cause remains unknown. To investigate whether glycolysis plays any role in endometrial repair and thus HMB, we conducted two mouse experiments using a mouse model of simulated menstruation. We performed immunohistochemistry analyses of proteins involved in glycolysis as well as pro- and anti-inflammatory cytokines in endometrium from decidualized and non-decidualized uterine horns. We also assessed the extent of endometrial repair by staging endometrial morphology from decidualization to full repair using histological scoring of uterine sections and quantitated the amount of menstrual blood loss (MBL). In addition, we employed the scratch assay and the CCK-8 assay to evaluate the effect of glycolysis suppression on cellular migration and proliferation, respectively. Finally, we performed an immunohistochemistry analysis of HK2 in endometrium from women with adenomyosis who experienced either moderate/heavy or excessive MBL. We found that endometrial repair coincided with increased glycolysis in endometrium and glycolysis suppression delayed endometrial repair, resulting in increased MBL. Additionally, glycolysis suppression significantly inhibited the proliferative and migratory capability of endometrial cells, and disrupted normal endometrial repair even when hypoxia was maintained. Women with adenomyosis who experienced excessive MBL had significantly lower HK2 staining than those who experienced moderate/heavy MBL. Thus, our study highlights the importance of glycolysis as well as inflammation in optimal endometrial repair, and provides clues for the cause of HMB in women with adenomyosis.

From Retrograde Menstruation to Endometrial Determinism and a Brave New World of "Root Treatment" of Endometriosis: Destiny or a Fanciful Utopia?

Practically unknown outside of China, the "endometrial determinism" theory was proposed to account for the apparent gap between the relatively low prevalence of endometriosis and nearly universal retrograde menstruation. Attracting uncritical advocacy, the theory culminates in a recent consensus by elite Chinese gynecologists in favor of "root treatment", intended to nip endometriosis in the bud. Correcting endometrial "defects" can gain further momentum by the presence of cancer-driver mutations such as KRAS mutations in the endometrium of women with endometriosis and the recent introduction of therapeutics aiming to rectify the effect of these mutations for cancer treatment. We provide a critical appraisal of evidence for endometrial aberrations in endometriosis and relevant experimental evidence. All available evidence of endometrial "defect" is invariably post hoc and may well be secondary to induced endometriosis. We propose that the theory of "endometrial determinism" needs to demonstrate a clear causal and a phylogenetic relationship between endometrial aberrations and endometriosis. We argue that while it is highly likely that endometriosis is a consequence of retrograde menstruation, the case that molecular aberrations as a sole or a necessary determinant remains to be proven. "Root treatment" is a worthy ambition but as of now it is close to a fanciful Utopia.

Uterine administration of C-X-C motif chemokine ligand 12 increases the pregnancy rates in mice with induced endometriosis

OBJECTIVE

To study the effect of intrauterine injection of C-X-C motif chemokine ligand 12 (CXCL12), also known as a stem cell chemoattractant (stromal cell-derived factor 1), on fertility and endometrial receptivity in mice with endometriosis.

DESIGN

Laboratory study.

SETTING

Academic Medical Center.

ANIMAL(S)

Fifty-six mice underwent chemotherapy and bone marrow transplantation. Thirty-six of these mice underwent either surgery to induce endometriosis (n = 20) or sham surgery (n = 16).

INTERVENTION(S)

Injection of CXCL12 as a potential therapeutic agent to improve fertility in endometriosis.

MAIN OUTCOME MEASURE(S)

Pregnancy rate, bone marrow-derived cell (BMDC) recruitment and endometrial receptivity markers.

RESULT(S)

The mice with or without endometriosis received a single uterine injection of either CXCL12 or placebo. Uterine injection of CXCL12 increased the pregnancy rates in a mouse model of endometriosis. Mice were euthanized after delivery, and implantation markers homeobox A11, alpha-v beta-3 integrin, and progesterone receptor were analyzed by immunohistochemistry, whereas green fluorescent protein positive BMDC recruitment was quantified by immunohistochemistry and immunofluorescence. The sham surgery groups without endometriosis had the highest cumulative pregnancy rate (100%) regardless of CXCL12 treatment. The endometriosis group treated with placebo had the lowest pregnancy rate. An increased pregnancy rate was noted in the endometriosis group after treatment with CXCL12. There was also an increase in BMDC recruitment and endometrial expression of progesterone receptor and alpha-v beta-3 integrin in the endometriosis group that received CXCL12 compared with that in the endometriosis group that received placebo.

CONCLUSION(S)

Uterine injection of CXCL12 increased the pregnancy rates in a mouse model of endometriosis. These results suggest that CXCL12 has a potential role as a therapeutic agent in women with infertility related to endometriosis and potentially other endometrial receptivity defects.

Maternal exposure to di(2-ethylhexyl) phthalate (DEHP) causes multigenerational adverse effects on the uterus of F1 and F2 offspring rats

Phthalates are one of the ubiquitous chemicals found in day-to-day products like food packaging, children's toys, and other consumer commodities. There is rising concern that repeated exposure to phthalates during pregnancy and lactation could have long-term effects on maternal and fetal health. We hypothesize that exposure to DEHP during the developmental windows might affect the expression of molecules that regulate uterine function and that this effect would be passed on to further generations. Rat dams were treated with olive oil (vehicle) or DEHP (100 mg/kg b.wt./day) orally from gestational day 9 (GD 9) to the end of lactation (PND 21). F₀ maternal DEHP exposure resulted in multigenerational (F₁ and F₂) reproductive toxicity, as evidenced by an extended estrous cycle, decreased mating, fertility, and fecundity indices. Serum progesterone and estradiol levels were decreased and their cognate receptors (PR and ERα) in the uterus were decreased in the DEHP-exposed offspring rats. Further analysis of the expression of estrogen and progesterone regulatory genes such as Hox a11, VEGF A, Ihh, LIFR, EP4, PTCH, NR2F2, BMP2, and Wnt4 were reduced in the uteri of adult F₁ and F₂ generation rats born from DEHP-exposed F₀ dams. Decreased expression of these crucial proteins due to DEHP exposure may lead to defects in epithelial proliferation and secretion, uterine receptivity, and decidualization in the uteri of successive generations. This study showed that maternal DEHP exposure impairs the expression of molecules that regulate uterine function and this multigenerational effect is transmitted via maternal lineage.

Altered Molecular Pathways and Biomarkers of Endometrial Receptivity in Infertile Women with Polycystic Ovary Syndrome

Anovulation is the most prominent cause of infertility in polycystic ovary syndrome (PCOS) patients. Although ovulation can be corrected pharmacologically, the number of pregnancies remains low. Even if excellent embryos are transferred by IVF, it does not change the high miscarriage rate of PCOS patients. These facts collectively indicate that there is a disorder of endometrial development and receptivity to the embryo in PCOS patients, including the decrease of receptive ability, inhibition of embryo adhesion, undersupply of energy, poor blood perfusion, and pro-inflammatory status in the endometrium. However, it has never received the same attention as ovulatory dysfunction. Here we list some alternations of endometrial receptivity in women with PCOS, discuss the underlying intricate mechanisms, and try to find out the possible therapeutic targets, which may bring new perspectives to those who are able to provide high-quality embryos.

Endometriosis-associated infertility: From pathophysiology to tailored treatment

Despite the clinically recognized association between endometriosis and infertility, the mechanisms implicated in endometriosis-associated infertility are not fully understood. Endometriosis is a multifactorial and systemic disease that has pleiotropic direct and indirect effects on reproduction. A complex interaction between endometriosis subtype, pain, inflammation, altered pelvic anatomy, adhesions, disrupted ovarian reserve/function, and compromised endometrial receptivity as well as systemic effects of the disease define endometriosis-associated infertility. The population of infertile women with endometriosis is heterogeneous, and diverse patients' phenotypes can be observed in the clinical setting, thus making difficult to establish a precise diagnosis and a single mechanism of endometriosis related infertility. Moreover, clinical management of infertility associated with endometriosis can be challenging due to this heterogeneity. Innovative non-invasive diagnostic tools are on the horizon that may allow us to target the specific dysfunctional alteration in the reproduction process. Currently the treatment should be individualized according to the clinical situation and to the suspected level of impairment. Here we review the etiology of endometriosis related infertility as well as current treatment options, including the roles of surgery and assisted reproductive technologies.

Hsa-mir-135a Shows Potential as A Putative Diagnostic Biomarker in Saliva and Plasma for Endometriosis

Endometriosis is a chronic disease characterized by the implantation and proliferation of endometrial tissue outside of the uterine cavity. The nonspecific nature of the symptoms and the lack of sensitive, noninvasive diagnostic methods often lead to a significant delay in diagnosis, highlighting the need for diagnostic biomarkers. The correlation of circulating miRNAs with altered inflammatory signals seen in patients with endometriosis has raised the possibility that miRNAs can serve as biomarkers for the disease. In our study, we analyzed miRNA expression in saliva of women with and without endometriosis using a FireFly custom multiplex circulating miRNA assay. This focused panel included 28 human miRNAs, 25 of which have been previously found to be differentially expressed either in plasma, serum, and/or blood of women with endometriosis, compared to controls. We found that hsa-mir-135a was expressed significantly higher in the saliva of women with endometriosis, independent of disease stage and menstrual cycle phase. We confirmed that hsa-mir-135a also showed significantly elevated expression in the plasma of endometriosis patients. This indicates that hsa-mir-135a is a putative noninvasive biomarker of endometriosis in both saliva and plasma, but further validation studies are required to assess its clinical value as a biomarker.

MicroRNAs and Progesterone Receptor Signaling in Endometriosis Pathophysiology

Endometriosis is a significant disease characterized by infertility and pelvic pain in which endometrial stromal and glandular tissue grow in ectopic locations. Altered responsiveness to progesterone is a contributing factor to endometriosis pathophysiology, but the precise mechanisms are poorly understood. Progesterone resistance influences both the eutopic and ectopic (endometriotic lesion) endometrium. An inability of the eutopic endometrium to properly respond to progesterone is believed to contribute to the infertility associated with the disease, while an altered responsiveness of endometriotic lesion tissue may contribute to the survival of the ectopic tissue and associated symptoms. Women with endometriosis express altered levels of several endometrial progesterone target genes which may be due to the abnormal expression and/or function of progesterone receptors and/or chaperone proteins, as well as inflammation, genetics, and epigenetics. MiRNAs are a class of epigenetic modulators proposed to play a role in endometriosis pathophysiology, including the modulation of progesterone signaling. In this paper, we summarize the role of progesterone receptors and progesterone signaling in endometriosis pathophysiology, review miRNAs, which are over-expressed in endometriosis tissues and fluids, and follow this with a discussion on the potential regulation of key progesterone signaling components by these miRNAs, concluding with suggestions for future research endeavors in this area.

Metformin Alleviates Endometriosis and Potentiates Endometrial Receptivity via Decreasing VEGF and MMP9 and Increasing Leukemia Inhibitor Factor and HOXA10

Background: Endometriosis affects endometrial receptivity, a key factor for successful embryo implantation. Metformin treatment is associated with alleviating the symptoms of endometriosis; however the mechanism of metformin action is unclear. Neoangiogenesis plays an important role in the development and recurrence of endometriosis. In addition, the leukemia inhibitor factor (LIF) and HOXA10 genes are also distinguishing markers of endometriosis (decrease) and endometrial receptivity (increase). This study investigated the therapeutic potentials of metformin and the underlying mechanism using an in vivo rat endometriosis model. Methods: Female Wistar albino mature rats with experimentally induced endometriosis were used in this study. Metformin was administered at doses of 100 mg/kg/d and 200 mg/kg/d. The volume of endometriotic implants was assessed. The protein and mRNA expression of the vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), the endometrial receptivity markers, LIF and HOXA10, were measured in the endometrium of rats with endometriosis. Results: Metformin treatment significantly suppressed the growth of endometriotic implants. Further, the expression of VEGF and MMP-9 protein and mRNA in endometriotic implants were significantly reduced. Metformin also significantly upregulated LIF and HOXA10 expression in endometrium from rats with endometriosis. The inhibitory effect of metformin on the growth of endometriotic implants, VEGF and MMP-9, and upregulating effect on LIF and HOXA10, was optimal at a dose of 100 mg/kg/d. Conclusion: Our in vivo data demonstrates that metformin treatment alleviates endometriosis and potentiates endometrial receptivity. The underlying mechanisms are associated with decreased expression of VEGF and MMP-9 genes and upregulation of the LIF and HOXA10 genes. The effect of metformin was optimal at 100 mg/kg/d. These findings provide a potential alternative for women with endometriosis with the potential to increase fertility. Metformin is an approved drug by FDA for diabetes and this study may add another potential clinical use for metformin.

Progesterone Actions and Resistance in Gynecological Disorders

Estrogen and progesterone and their signaling mechanisms are tightly regulated to maintain a normal menstrual cycle and to support a successful pregnancy. The imbalance of estrogen and progesterone disrupts their complex regulatory mechanisms, leading to estrogen dominance and progesterone resistance. Gynecological diseases are heavily associated with dysregulated steroid hormones and can induce chronic pelvic pain, dysmenorrhea, dyspareunia, heavy bleeding, and infertility, which substantially impact the quality of women's lives. Because the menstrual cycle repeatably occurs during reproductive ages with dynamic changes and remodeling of reproductive-related tissues, these alterations can accumulate and induce chronic and recurrent conditions. This review focuses on faulty progesterone signaling mechanisms and cellular responses to progesterone in endometriosis, adenomyosis, leiomyoma (uterine fibroids), polycystic ovary syndrome (PCOS), and endometrial hyperplasia. We also summarize the association with gene mutations and steroid hormone regulation in disease progression as well as current hormonal therapies and the clinical consequences of progesterone resistance.

Effects of dual inhibition of AKT and ERK1/2 pathways on endometrial pro-inflammatory, hormonal, and epigenetic microenvironment in endometriosis

Endometriosis is an estrogen-dependent and progesterone-resistant gynecological inflammatory disease of reproductive-age women. The prevalence of endometriosis is ~5-10% in reproductive-age women, increasing to 20-30% in women with subfertility. The current anti-estrogen therapies can be prescribed only for a short time because of the undesirable side effects on menstruation, pregnancy, bone health, and failure to prevent a recurrence. The causes of endometriosis-associated infertility are multifactorial and poorly understood. The objective of the present study was to determine the inhibitory effects of AKT and/or ERK1/2 pathways on the microenvironment of the endometrium in a xenograft mouse model of endometriosis of human origin. Results indicate that dual inhibition of AKT and ERK1/2 pathways, but not inhibition of either AKT or ERK1/2 pathway, suppresses the growth of the endometriotic lesions in vivo. Dual inhibition of AKT and ERK1/2 pathways suppresses the production of proinflammatory cytokines, decreases E₂ biosynthesis and signaling, and restores progesterone receptor-B signaling components in the epithelial and stromal cells of the endometrium in a cell-specific manner. These results together suggest that dual inhibition of AKT and ERK1/2 pathways suppresses the estrogen-dominant state and concomitantly increases the progesterone-responsive state of the endometrium. Therefore, dual inhibition of AKT and ERK1/2 pathways could emerge as long-term nonsteroidal therapy for endometriosis.

Increased METTL3-mediated m6A methylation inhibits embryo implantation by repressing HOXA10 expression in recurrent implantation failure

BACKGROUND

Recurrent implantation failure (RIF) is a major limitation of assisted reproductive technology, which is associated with impaired endometrial receptivity. Although N⁶-methyladenosine (m⁶A) has been demonstrated to be involved in various biological processes, its potential role in the endometrium of women with RIF has been poorly studied.

METHODS

Global m⁶A levels and major m⁶A methyltransferases/demethylases mRNA levels in mid-secretory endometrium from normal and RIF women were examined by colorimetric m⁶A quantification strategy and quantitative real-time PCR, respectively. The effects of METTL3-mediated m⁶A modification on embryo attachment were evaluated by an vitro model of a confluent monolayer of Ishikawa cells co-cultured with BeWo spheroids, and the expression levels of homeo box A10 (HOXA10, a well-characterized marker of endometrial receptivity) and its downstream targets were evaluated by quantitative real-time PCR and Western blotting in METTL3-overexpressing Ishikawa cells. The molecular mechanism for METTL3 regulating HOXA10 expression was determined by methylated RNA immunoprecipitation assay and transcription inhibition assay.

RESULTS

Global m⁶A methylation and METTL3 expression were significantly increased in the endometrial tissues from women with RIF compared with the controls. Overexpression of METTL3 in Ishikawa cells significantly decreased the ration of BeWo spheroid attachment, and inhibited HOXA10 expression with downstream decreased β3-integrin and increased empty spiracles homeobox 2 expression. METTL3 catalyzed the m⁶A methylation of HOXA10 mRNA and contributed to its decay with shortened half-life. Enforced expression of HOXA10 in Ishikawa cells effectively rescued the impairment of METTL3 on the embryo attachment in vitro.

CONCLUSION

Increased METTL3-mediated m⁶A modification represents an adverse impact on embryo implantation by inhibiting HOXA10 expression, contributing to the pathogenesis of RIF.

Combined expression of HOXA11 and CD10 identifies endometriosis versus normal tissue and tumors

The gold standard for diagnosing endometriosis is by laparoscopic visual demonstration of ectopic endometrial lesions outside the uterus, preferably verified by biopsy and microscopical examination. Molecular markers to facilitate the microscopical diagnosis of endometriosis and for distinguishing endometriosis from other benign and malignant lesions are lacking. Our aim was to test and validate an immunohistochemical antibody panel for improved diagnostic accuracy of endometriosis. Both CD10 and HOXA11 have been implicated in regulation of endometrial homeostasis. Here we have analyzed the expression pattern of these two proteins using immunohistochemistry on human tissues in a tissue microarray format. CD10 and HOXA11 expression in endometriosis lesions were compared to expression patterns in a range of normal tissues and in primary- and metastatic lesions of endometrial-, cervical- and ovarian cancer. HOXA11 and CD10 were expressed in 98% and 91% of endometriosis lesions and the combined double-positive expression profile of both HOXA11 and CD10 was highly sensitive for ectopic endometrial tissue (90%). The specificity and sensitivity for this double-positive signature in endometriosis was significantly different from all investigated tissues, cancers and metastases except normal, eutopic endometrial- and cervical mucosa. The combination of HOXA11 and CD10 expression profiles provides a useful tool to identify ectopic endometrial tissue and for distinguishing endometriosis from various types of gynecological malignancies and metastases.

Estrogen- and Progesterone (P4)-Mediated Epigenetic Modifications of Endometrial Stromal Cells (EnSCs) and/or Mesenchymal Stem/Stromal Cells (MSCs) in the Etiopathogenesis of Endometriosis

Endometriosis is a common chronic inflammatory condition in which endometrial tissue appears outside the uterine cavity. Because ectopic endometriosis cells express both estrogen and progesterone (P4) receptors, they grow and undergo cyclic proliferation and breakdown similar to the endometrium. This debilitating gynecological disease affects up to 15% of reproductive aged women. Despite many years of research, the etiopathogenesis of endometrial lesions remains unclear. Retrograde transport of the viable menstrual endometrial cells with retained ability for attachment within the pelvic cavity, proliferation, differentiation and subsequent invasion into the surrounding tissue constitutes the rationale for widely accepted implantation theory. Accordingly, the most abundant cells in the endometrium are endometrial stromal cells (EnSCs). These cells constitute a particular population with clonogenic activity that resembles properties of mesenchymal stem/stromal cells (MSCs). Thus, a significant role of stem cell-based dysfunction in formation of the initial endometrial lesions is suspected. There is increasing evidence that the role of epigenetic mechanisms and processes in endometriosis have been underestimated. The importance of excess estrogen exposure and P4 resistance in epigenetic homeostasis failure in the endometrial/endometriotic tissue are crucial. Epigenetic alterations regarding transcription factors of estrogen and P4 signaling pathways in MSCs are robust in endometriotic tissue. Thus, perspectives for the future may include MSCs and EnSCs as the targets of epigenetic therapies in the prevention and treatment of endometriosis. Here, we reviewed the current known changes in the epigenetic background of EnSCs and MSCs due to estrogen/P4 imbalances in the context of etiopathogenesis of endometriosis. Graphical Abstract.

Endometrial stem cells: origin, biological function, and therapeutic applications for reproductive disorders

PURPOSE OF REVIEW

Endometrial stem cells (ESCs) are multipotent cells that are thought to originate locally in the endometrium as well as in the bone marrow (BM). They have remarkable plasticity and hold promise as an autologous source for regenerative medicine. This review focuses on recent studies that have advanced our understanding of the biology and function of ESCs and BM-derived stem cells (BMDSCs) as related to physiological reproductive processes and pathologies. Moreover, it reviews recent data on potential therapeutic applications of stem cells to endometrial disorders that lead to reproductive failure.

RECENT FINDINGS

Growing evidence from basic and preclinical studies suggests that ESCs participate in endometrial tissue regeneration and repair. Recent evidence also suggests that ESCs and BMDSCs play important roles in physiological reproductive functions including decidualization, implantation, pregnancy maintenance, and postpartum uterine remodeling. Initial preclinical and clinical studies with ESCs and BMDSCs suggest they have the potential to provide new therapies for various endometrial disorders associated with reproductive failure.

SUMMARY

Uterine ESCs and BMDSCs appear to play an important biological role in reproductive success and failure, and have the potential to become treatment targets for reproductive diseases including recurrent implantation failure, thin endometrium, Asherman, and recurrent pregnancy loss.

Mesenchymal Stem Cells in Preclinical Infertility Cytotherapy: A Retrospective Review

Infertility is a global reproductive disorder which is caused by a variety of complex diseases. Infertility affects the individual, family, and community through physical, psychological, social and economic consequences. The results from recent preclinical studies regarding stem cell-based therapies are promising. Stem cell-based therapies cast a new hope for infertility treatment as a replacement or regeneration strategy. The main features and application prospects of mesenchymal stem cells in the future of infertility should be understood by clinicians. Mesenchymal stem cells (MSCs) are multipotent stem cells with abundant source, active proliferation, and multidirectional differentiation potential. MSCs play a role through cell homing, secretion of active factors, and participation in immune regulation. Another advantage is that, compared with embryonic stem cells, there are fewer ethical factors involved in the application of MSCs. However, a number of questions remain to be answered prior to safe and effective clinical application. In this review, we summarized the recent status of MSCs in the application of the diseases related to or may cause to infertility and suggest a possible direction for future cytotherapy to infertility.

Metformin and insulin-resistant related diseases: Emphasis on the role of microRNAs

Metformin is one of the most prescribed drugs in type II diabetes (T2DM) which has recently found new applications in the prevention and treatment of various illnesses, from metabolic disorders to cardiovascular and age-related diseases. Metformin improves insulin resistance (IR) by modulating metabolic mechanisms and mitochondrial biogenesis. Alternation of microRNAs (miRs) in the treatment of IR-related illnesses has been observed by metformin therapy. MiRs are small non-coding RNAs that play important roles in RNA silencing, targeting the 3'untranslated region (3'UTR) of most mRNAs and inhibiting the translation of related proteins. As a result, their dysregulation is associated with many diseases. Metformin may alter miRs levels in the treatment of various diseases by AMPK-dependent or AMPK-independent mechanisms. Here, we summarized the therapeutic role of metformin by modifying the aberrant expression of miRs as potential biomarkers or therapeutic targets in diseases in which IR plays a key role.

Genetic impacts on thermostability of onco-lncRNA HOTAIR during the development and progression of endometriosis

HOTAIR is a well-known long non-coding RNA (lncRNA) involved in various cellular signaling, whereas its functional impacts on endometriosis development are still largely unknown. To this end, six potential functional single nucleotide polymorphisms (SNPs) in HOTAIR, with minor allele frequencies more than 10% in Han population and altered net energy of RNA structures larger than 0.5 kcal/mol, were selected for genotyping study. The study included 207 endometriosis patients and 200 healthy women. Genetic substitutions at rs1838169 and rs17720428 were frequently found in endometriosis patients, and rs1838169 showed statistical significance (p = 0.0174). The G-G (rs1838169-rs17720428) haplotype showed the most significant association with endometriosis (p < 0.0001) with enhanced HOTAIR stability, and patients who harbor such haplotype tended to show higher CA125. Data mining further revealed higher mRNA HOTAIR levels in the endometria of patients with severe endometriosis which consistently showed reduced HOXD10 and HOXA5 levels. HOTAIR knockdown with specific shRNAs down-regulated cell proliferation and migration with the induction of HOXD10 and HOXA5 expression in human ovarian clear cancer cells. Our study therefore provided evidence to indicate a prominent role of HOTAIR in promoting endometriosis, which could be used as a potential target for clinical applications.

Differential expression of protein disulfide isomerase (PDI) in regulating endometrial receptivity in humans

Estrogen and progesterone regulate the expression of endometrial proteins that determine endometrial receptivity for embryo implantation. The protein disulfide isomerase (PDI) family of proteins play a diverse role in regulating protein modification and redox function. Although the role of PDIs in cancer progression has been widely studied, their role in endometrial receptivity is largely unknown. We have focused on the expressions of PDIA1, PDIA2, PDIA3, PDIA4, PDIA5, and PDIA6 isoforms in endometrial epithelium under the influence of estrogen and progesterone and investigated their functional role in regulating endometrial receptivity. We found PDIA1-6 transcripts were expressed in endometrial epithelial Ishikawa, RL95-2, AN3CA, and HEC1-B cell lines. The expression of PDIA1 was low and PDIA5 was high in HEC1-B cells, whereas PDIA2 was high in both AN3CA and HEC1-B cells. In Ishikawa cells, estrogen (10 and 100 nM) upregulated PDIA1 and PDIA6, whereas estrogen (100 nM) downregulated PDIA4 and PDIA5; and progesterone (0.1 and 1 μM) downregulated transcript expressions of PDIA1-6. In human endometrial samples, significantly lowered transcript expressions of PDIA2 and PDIA5 were observed in the secretory phase compared with the proliferative phase, whereas no change was observed in the other studied transcripts throughout the cycle. Inhibition of PDI by PDI antibody (5 and 10 μg/mL) and PDI inhibitor bacitracin (1 and 5 mM) significantly increased the attachment of Jeg-3 spheroids onto AN3CA cells. Taken together, our study suggests a role of PDI in regulating endometrial receptivity and the possibility of using PDI inhibitors to enhance endometrial receptivity.

Early Pregnancy Outcomes in Fresh Versus Deferred Embryo Transfer Cycles for Endometriosis-Associated Infertility: A Retrospective Cohort Study

Given the estrogen-dependence associated with endometriosis, hyper-stimulation associated with assisted reproduction treatment may exacerbate the disease process and adversely affect endometrial receptivity and subsequent implantation. In this way, a freeze-all deferred embryo transfer (ET) approach may benefit patients with endometriosis, although controversy exists regarding the mechanism of endometriosis-associated infertility and benefits of deferred ET on endometrial receptivity. Hence, the purpose of this study was to compare in vitro fertilization (IVF) outcomes in women with endometriosis, diagnosed by histology, undergoing fresh versus deferred-ET after elective cryopreservation. Of the 728 women included, no significant differences were observed in baseline patient characteristics and response to gonadotrophin stimulation between fresh and deferred ET groups. Furthermore, no significant differences in implantation rate (49.7 vs. 49.9%, p = 0.73), clinical pregnancy rate (40.9 vs. 39.9%, p = 0.49), and miscarriage rate (9.4 vs. 9.9%, p = 0.63) were observed between fresh and deferred ET groups, respectively. Hence, contrary to previous studies, our results suggest that a deferred ET “freeze-all” IVF strategy does not improve early pregnancy outcomes among women with endometriosis. However, prospective studies are required to validate these findings and further insight into the etiology and pathogenesis of endometriosis-associated infertility are necessary to optimize IVF protocols in this population.

Day-5 fresh embryo transfer is associated with superior clinical outcomes in oocyte donation cycles compared with day-3 embryo transfer

OBJECTIVE

Τo compare clinical outcomes between day-5 (D5ET) and day-3 (D3ET) fresh embryo transfer in oocyte donation cycles.

STUDY DESIGN

A retrospective analysis of prospectively collected cohort data was performed enrolling all participants in an oocyte donation program performed either D5ET or D3ET regarding the period from June 2006 to June 2018. Cycles were compared by the day of embryo transfer. Primary outcomes were the clinical pregnancy rate and live birth rate. Secondary outcomes were implantation rate, biochemical pregnancy rate, early miscarriage rate, and twin pregnancy rate. Outcomes were adjusted for covariates within study groups.

RESULTS

A total of 8023 cycles meeting our inclusion criteria were analyzed. D5ET consisted of 4865 cycles and D3ET of 3158 cycles. The D5ET group had a significantly higher clinical pregnancy rate (p < .001), live birth rate (p = .004), implantation rate (p < .001), and twin pregnancy rate (p = .02) than the D3ET group. Accordingly, biochemical pregnancy rate (7.4% vs. 5.1%, p < .001) and early miscarriage rate (4.1% vs. 3.2%, p = .04) were significantly higher in D3ET compared to the D5ET group.

CONCLUSION

Οocyte donation cycles with fresh D5ET resulted in fewer embryos transferred, higher clinical pregnancy rates, and higher live birth rates compared to D3ET. Our findings are strongly favoring day-5 embryo transfer in oocyte donation cycles.

Genome-wide expression analysis of endometrium before and after endometrioma surgery

OBJECTIVE

This study was planned to investigate possible alteration in the number of differentially expressed genes (DEGs) in eutopic endometrium before and after laparoscopic removal of the ovarian endometrioma.

STUDY DESIGN

Six infertile women with ovarian endometrioma who underwent laparoscopic endometrioma cystectomy and six fertile control subjects who underwent tubal sterilization were included the study. Endometrial samples were collected before and 3 months after surgery throughout the mid-luteal phase. Genome-wide expression profiling was performed with Illumina Human HT-12V4 microchip, a high density silica bead-based microarray which utilizing more than 47.000 probs. Illumina microsequence system was used to assess detection of p value for each probe in every sample. Probes revealing significant assessment (p < .05) were selected for comparative analysis.

RESULTS

We have detected 1478 DEGs in the comparison between endometrium of women with endometrioma and fertile controls. 118 out of 1478 genes (7.9 %) were significantly increased or decreased more than 1.5-fold in their expression. When the preoperative values of the control and patient groups are compared the number of DEGs was 243 (7.5 %). In 9 out of 243 genes, the fold change was found to be 1.5 and more (3.7 %). Comparison of the number of DEGs after endometrioma surgery and tubal ligation revealed that expression patterns of 1036 genes (33.7 %) were changed in endometrioma group. In 105 out of 1036 genes, the fold change was found to be 1.5 and above (10 %). A comparison using 2706 probes revealed changes in the expression patterns of 106 different genes (3.9 %) after endometrioma resection. In 4 out of 106 genes, the fold change was found to be 1.5 and above (3.7 %). The comparison using 6035 probes revealed changes in the expression patterns of 93 genes (1.5 %) after tubal ligation. None of the 93 genes had a fold change of 1.5 or higher. The number of DEGs in endometrioma groups after surgery was approximately 3-fold higher than control group.

CONCLUSIONS

Endometrium of women with endometrioma displayed abnormal expression of genes associated with implantation, immunological, endocrine and neuracrine functions. Positive alteration of the expression pattern of DEGs and signal transduction pathways following endometrioma surgery can improve the receptive capacity and implantation rates of eutopic endometrium.

90 YEARS OF PROGESTERONE: Selective progesterone receptor modulators in gynaecological therapies

Abnormal uterine bleeding (AUB) is a chronic, debilitating and common condition affecting one in four women of reproductive age. Current treatments (conservative, medical and surgical) may be unsuitable, poorly tolerated or may result in loss of fertility. Selective progesterone receptor modulators (SPRMs) influence progesterone-regulated pathways, a hormone critical to female reproductive health and disease; therefore, SPRMs hold great potential in fulfilling an unmet need in managing gynaecological disorders. SPRMs in current clinical use include RU486 (mifepristone), which is licensed for pregnancy interruption, and CDB-2914 (ulipristal acetate), licensed for managing AUB in women with leiomyomas and in a higher dose as an emergency contraceptive. In this article, we explore the clinical journey of SPRMs and the need for further interrogation of this class of drugs with the ultimate goal of improving women's quality of life.

Fertility-related considerations in endometriosis

Endometriosis and infertility often present together but the exact cause-effect mechanism of this association is unknown. Though there are several proposed mechanisms regarding the pathophysiology of endometriosis-related infertility, no one theory is universally accepted. Surgical exploration is gold standard for diagnosis but imaging modalities especially specialized ultrasonography and magnetic resonance imaging can highlight disease burden and aid in planning for surgical excision. Overall, medical therapy is ineffective for endometriosis-related infertility; however, surgery may be fertility enhancing in women with minimal stage disease and in women with large endometriomas. Assisted reproductive technology may be required with endometriosis-related infertility. Medically induced superovulation with intrauterine insemination is typically the first line; however, women with advanced disease may need a more aggressive form of treatment with in vitro fertilization.

Reproductive, obstetric, and perinatal outcomes of women with adenomyosis and endometriosis: a systematic review and meta-analysis

BACKGROUND

The reproductive impact of adenomyosis and endometriosis is widely researched but the extent of these impacts remains elusive. It has been demonstrated that endometriosis, in particular, is known to result in subfertility but endometriosis and adenomyosis are increasingly linked to late pregnancy complications such as those caused by placental insufficiency. At the molecular level, the presence of ectopic endometrium perturbs the endometrial hormonal, cellular, and immunological milieu, negatively influencing decidualization, placentation, and developmental programming of the embryo. It is unclear if and how such early aberrant reproductive development relates to pregnancy outcomes in endometriosis and adenomyosis.

OBJECTIVE AND RATIONALE

The aims of this systematic review and meta-analysis were to (i) investigate the association of adenomyosis and endometriosis with fertility, obstetric, and neonatal outcomes of women through both assisted reproduction and natural conception and (ii) determine whether endometriosis disease subtypes have specific impacts on different stages of the reproductive process.

SEARCH METHODS

A systematic literature review of NHS evidence electronic databases and the Cochrane database identified all comparative and observational studies between 1980 and December 2018 in any language on adenomyosis and endometriosis with fertility, obstetric, and neonatal outcomes (23 search terms used). A total of 104 papers were selected for data extraction and meta-analysis, with use of Downs and Black standardized checklist to evaluate quality and bias.

OUTCOMES

We found that endometriosis consistently leads to reduced oocyte yield and a reduced fertilization rate (FR), in line with current evidence. Milder forms of endometriosis were most likely to affect the fertilization (FR OR 0.77, CI 0.63-0.93) and earlier implantation processes (implantation rate OR 0.76, CI 0.62-0.93). The more severe disease by American Society for Reproductive Medicine staging (ASRM III and IV) influenced all stages of reproduction. Ovarian endometriosis negatively affects the oocyte yield (MD -1.22, CI -1.96, -0.49) and number of mature oocytes (MD -2.24, CI -3.4, -1.09). We found an increased risk of miscarriage in both adenomyosis and endometriosis (OR 3.40, CI 1.41-8.65 and OR 1.30, CI 1.25-1.35, respectively), and endometriosis can be associated with a range of obstetric and fetal complications including preterm delivery (OR 1.38, CI 1.01-1.89), caesarean section delivery (OR 1.98 CI 1.64-2.38), and neonatal unit admission following delivery (OR 1.29, CI 1.07-1.55).

WIDER IMPLICATIONS

Adenomyosis and the subtypes of endometriosis may have specific complication profiles though further evidence is needed to be able to draw conclusions. Several known pregnancy complications are likely to be associated with these conditions. The complications are possibly caused by dysfunctional uterine changes leading to implantation and placentation issues and therefore could potentially have far-reaching consequences as suggested by Barker's hypothesis. Our findings would suggest that women with these conditions should ideally receive pre-natal counselling and should be considered higher risk in pregnancy and at delivery, until evidence to the contrary is available. In order to expand our knowledge of these conditions and better advise on future management of these patients in reproductive and maternal medicine, a more unified approach to studying fertility and reproductive outcomes with longer term follow-up of the offspring and attention to the subtype of disease is necessary.

Alleviation of Symptoms and Improvement of Endometrial Receptivity Following Laparoscopic Adenomyoma Excision and Secondary Therapy with the Levonorgestrel-releasing Intrauterine System

To assess the treatment efficacy of adenomyoma and improvement in implantation receptivity associated with the levonorgestrel-releasing intrauterine system (LNG-IUS) combined with adenomyoma resection. Fifty subjects (control group) underwent laparoscopic adenomyoma excision and received gonadotropin-releasing hormone (GnRH) agonists, and 201 subjects (experimental group) underwent laparoscopic adenomyoma resection and received GnRH agonists combined with the LNG-IUS. Pipelle endometrial biopsies were obtained in the mid-luteal phase, before the operation, and 19 months after the operation. Menstrual blood loss was measured using a pictorial blood loss assessment chart. Pain intensity during menstruation was evaluated on a 10-point visual analog scale (VAS). The volume of uterus was measured through ultrasound. Quantification of HOXA10 promoter methylation was performed through bisulfite sequencing polymerase chain reaction (BSP). Real-time polymerase chain reaction analyzed the expression levels of endometrial HOXA10-mRNA and leukemia inhibitory factor (LIF)-mRNA. After surgery, the scores for dysmenorrhea and menorrhagia were significantly improved, and the volume of the uterus was obviously reduced (all p < 0.01). The mean number of methylated CpG sites, level of endometrial HOXA10-mRNA, and level of endometrial LIF-mRNA were 5.6 ± 1.7 versus 3.9 ± 1.3, 0.8 ± 0.2 versus 0.9 ± 0.3, and 0.8 ± 0.2 versus 1.0 ± 0.2, respectively, in the control group versus the experimental group at 19 months after surgery, and significant improvements were observed in the experimental group (p < 0.001, p = 0.034, p < 0.001). Laparoscopic adenomyoma excision and GnRH agonists can alleviate the symptoms, reduce the number of methylated CpG sites in HOXA10, and improve endometrial HOXA10-mRNA and endometrial LIF-mRNA levels. When combined with subsequent use of the LNG-IUS, better efficacy can be achieved.

Is the profile of transcripts altered in the eutopic endometrium of infertile women with endometriosis during the implantation window?

STUDY QUESTION

Compared to healthy women, is the profile of transcripts altered in the eutopic endometrium of infertile women with endometriosis during the implantation window (IW)?

SUMMARY ANSWER

The eutopic endometrium of infertile women with endometriosis seems to be transcriptionally similar to the endometrium of infertile and fertile controls (FC) during the IW.

WHAT IS KNOWN ALREADY

Endometriosis is a disease related to infertility; nevertheless, little is known regarding the ethiopathogenic mechanisms underlying this association. Some studies evaluating the eutopic endometrium of endometriosis patients suggest there is an endometrial factor involved in the disease-related infertility. However, no study to date has evaluated the endometrial transcriptome (mRNA and miRNA) by next generation sequencing (NGS), comparing patients with endometriosis as the exclusive infertility factor (END) to infertile controls (IC; male and/or tubal factor) and FC.

STUDY DESIGN, SIZE, DURATION

From November 2011 to November 2015 we performed a case-control study, where 17 endometrial samples (six END, six IC, five FC) were collected during the IW.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All endometrial samples had the RNA extracted. Two libraries were prepared for each one (mRNA and miRNA), which were sequenced, respectively, at HISEQ 2500 (RNA-Seq) and MiSeq System (miRNA-Seq), Illumina. The normalization and differential expression were conducted in statistical R environment using DESeq2 package. qPCR was used for data validation, which were analyzed by Kruskal–Wallis test and Dunn posttest (P &lt; 0.05).

MAIN RESULTS AND THE ROLE OF CHANCE

RNA-Seq revealed no differentially expressed genes (DEG) among END, IC and FC groups. miRNA-Seq revealed three differentially expressed miRNAs (has-27a-5p, has-miR-150-5p, has-miR-504-5p) in END group compared to FC group. However, none of the miRNAs identified in the sequencing was validated by qPCR.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study was the small sample size evaluated as a result of the restrictive eligibility criteria adopted, limiting the generalization of the results obtained here. On the other hand, strict eligibility criteria, which eliminated factors potentially related to impaired endometrial receptivity, were required to increase the study’s internal validity.

WIDER IMPLICATIONS OF THE FINDINGS

This study brings new perspectives on the mechanisms involved in endometriosis-related infertility. The present findings suggest the eutopic endometrium of infertile women with endometriosis, without considering the disease’s stage, is transcriptionally similar to controls during the IW, possibly not affecting receptivity. Further studies are needed to evaluate endometrial alterations related to endometriosis’ stages.

STUDY FUNDING/COMPETING INTEREST(S)

This study received financial support from the Sao Paulo Research Foundation (FAPESP—Fundação de Amparo à Pesquisa do Estado de São Paulo; fellowship 2011/17614–6, MGB) and from the National Council for Scientific and Technological Development (CNPq—Conselho Nacional de Desenvolvimento Científico e Tecnológico; INCT—National Institutes of Hormones and Woman’s Health, grant 471 943/2012-6, 309 397/2016-2, PAN; fellowship 140 137/2015-7, MGB). The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Epigenetic control of embryo-uterine crosstalk at peri-implantation

Embryo implantation is one of the pivotal steps during mammalian pregnancy, since the quality of embryo implantation determines the outcome of ongoing pregnancy and fetal development. A large number of factors, including transcription factors, signalling transduction components, and lipids, have been shown to be indispensable for embryo implantation. Increasing evidence also suggests the important roles of epigenetic factors in this critical event. This review focuses on recent findings about the involvement of epigenetic regulators during embryo implantation.

Adult bone marrow progenitors become decidual cells and contribute to embryo implantation and pregnancy

Decidua is a transient uterine tissue shared by mammals with hemochorial placenta and is essential for pregnancy. The decidua is infiltrated by many immune cells promoting pregnancy. Adult bone marrow (BM)-derived cells (BMDCs) differentiate into rare populations of nonhematopoietic endometrial cells in the uterus. However, whether adult BMDCs become nonhematopoietic decidual cells and contribute functionally to pregnancy is unknown. Here, we show that pregnancy mobilizes mesenchymal stem cells (MSCs) to the circulation and that pregnancy induces considerable adult BMDCs recruitment to decidua, where some differentiate into nonhematopoietic prolactin-expressing decidual cells. To explore the functional importance of nonhematopoietic BMDCs to pregnancy, we used Homeobox a11 (Hoxa11)-deficient mice, having endometrial stromal-specific defects precluding decidualization and successful pregnancy. Hoxa11 expression in BM is restricted to nonhematopoietic cells. BM transplant (BMT) from wild-type (WT) to Hoxa11-/- mice results in stromal expansion, gland formation, and marked decidualization otherwise absent in Hoxa11-/- mice. Moreover, in Hoxa11+/- mice, which have increased pregnancy losses, BMT from WT donors leads to normalized uterine expression of numerous decidualization-related genes and rescue of pregnancy loss. Collectively, these findings reveal that adult BMDCs have a previously unrecognized nonhematopoietic physiologic contribution to decidual stroma, thereby playing important roles in decidualization and pregnancy.

Evaluation of Endometrial Receptivity by Measuring HOXA-10, HOXA-11, and Leukemia Inhibitory Factor Expression in Patients with Polycystic Ovary Syndrome

Context:

Polycystic ovary syndrome (PCOS) is an important cause of infertility. In women with PCOS have increased rate of spontaneous abortion and reduced rate of conception. HOXA–10 and HOXA–11 are proteinous products of homeobox gene group and play an important role during implantation.

Aims:

The aim of this study was to evaluate endometrial receptivity by measuring HOXA–10, HOXA–11, and leukemia inhibitory factor (LIF) gene expressions in women with PCOS.

Settings and Design:

A tertiary referral center.

Materials and Methods:

This study was conducted on reproductive age women with abnormal uterine bleeding without sonographically proven anatomical reason. Endometrial sampling procedures were done in proliferative phase using low-pressure endometrial suction device to exclude endometrial pathology. HOXA–10, HOXA–11, and LIF gene expressions were measured from endometrial sampling material. Blood sample was taken to measure serum estradiol level on the day of endometrial sampling.

Statistical Analysis Used:

Statistical analysis was performed using SPSS software version 17 (SPSS Inc., Chicago, IL, USA). Mann–Whitney U-test was used to compare the variables.

Results:

A total of 53 patients were included in this study. Study group consisted of 33 patients with PCOS. Gene expressions of HOXA–10, HOXA–11, and LIF were significantly lower in patients with PCOS (P < 0.05).

Conclusions:

This study results showed that in patients with PCOS have decreased gene expression of HOXA-10, HOXA-11, and LIF which might contribute PCOS-related infertility.

Progesterone and Estrogen Signaling in the Endometrium: What Goes Wrong in Endometriosis?

In the healthy endometrium, progesterone and estrogen signaling coordinate in a tightly regulated, dynamic interplay to drive a normal menstrual cycle and promote an embryo-receptive state to allow implantation during the window of receptivity. It is well-established that progesterone and estrogen act primarily through their cognate receptors to set off cascades of signaling pathways and enact large-scale gene expression programs. In endometriosis, when endometrial tissue grows outside the uterine cavity, progesterone and estrogen signaling are disrupted, commonly resulting in progesterone resistance and estrogen dominance. This hormone imbalance leads to heightened inflammation and may also increase the pelvic pain of the disease and decrease endometrial receptivity to embryo implantation. This review focuses on the molecular mechanisms governing progesterone and estrogen signaling supporting endometrial function and how they become dysregulated in endometriosis. Understanding how these mechanisms contribute to the pelvic pain and infertility associated with endometriosis will open new avenues of targeted medical therapies to give relief to the millions of women suffering its effects.

Clinical approach to recurrent implantation failure: evidence-based evaluation of the endometrium

The endometrium is a dynamic, repetitively cycling tissue that mediates the implantation of the blastocyst. Evaluation of this complex tissue necessitates sophisticated methods that can assess its functional potential. Beginning in the 1950s with simple histological endometrial "dating," these methods have crossed into the molecular era with the use of arrays aimed at dating, functional tests that assess for proliferation and differentiation, and tests that screen for inflammatory markers. In addition to these specialized tests, histologic evaluation for pathologic conditions-such as growth disorders (i.e. polyps and hyperplasia), inflammatory lesions, and retained products of conception-are critical for a complete assessment of the patient with recurrent implantation failure. Whatever the means of testing, the goal is to reveal actionable findings that can assist in offering the best options to patients who have failed multiple transfers with high quality embryos.

Progesterone Receptor B (PGR-B) Is Partially Methylated in Eutopic Endometrium From Infertile Women With Endometriosis

Endometriosis is frequently related to infertility and little is known about the mechanisms underlying this association. Some studies point to an endometrial factor involved in this condition, which could compromise embryo implantation. Progesterone plays crucial role in endometrial receptivity by acting through progesterone receptor (PGR) isoforms PR-A and PR-B whose expression is epigenetically regulated by DNA methylation, in a specific promoter region for each isoform. Epigenetic changes in PGR-A and PGR-B may be related to progesterone resistance of endometriosis-related infertility. In order to better understand the mechanisms involved in endometrial receptivity, this case-control study aimed to compare the methylation pattern of PGR-A and PGR-B in eutopic endometrium from infertile women with and without endometriosis during the secretory phase. Endometrial biopsies from 19 patients (10 infertile women with endometriosis and 9 infertile controls) with regular cycles were performed during the secretory phase and were dated according to Noyes' criteria. The percentage of DNA methylation at PGR-A and PGR-B was carried out by high-resolution melting assay. The PGR-A gene showed 0% of DNA methylation (unmethylated) in both control and endometriosis groups. However, PGR-B gene showed a partially methylated pattern in majority of the patients (n = 7), with methylation percentage corresponding to 50%, while in the control group the percentage of methylation was 20% (hypomethylated; P = .04). The increased percentage of methylation at PGR-B may be related to reduced gene expression, which could compromise the endometrial receptivity in patients with endometriosis.

Regulation of Inflammation Pathways and Inflammasome by Sex Steroid Hormones in Endometriosis

Endometriosis is a gynecological disorder characterized by the growth of endometrial tissue (glands and stroma) outside the uterus, mainly in the peritoneal cavity, ovaries, and intestines. This condition shows estrogen dependency and progesterone resistance, and it has been associated with chronic inflammation, severe pain, and infertility, which negatively affect the quality of life in reproductive women. The molecular mechanisms involved in the pathogenesis of endometriosis are not completely understood; however, inflammation plays a key role in the pathophysiology of the disease, mainly by altering the function of immune cells (macrophages, natural killer, and T cells) and increasing levels of pro-inflammatory mediators in the peritoneal cavity, endometrium, and blood. These immune alterations inhibit apoptotic pathways and promote adhesion and proliferation of endometriotic cells, as well as angiogenesis and neurogenesis in endometriotic lesions. It has been demonstrated that hormonal alterations in endometriosis are related to the inflammatory unbalance in this disease. Particularly, steroid hormones (mainly estradiol) promote the expression and release of pro-inflammatory factors. Excessive inflammation in endometriosis contributes to changes of hormonal regulation by modulating sex steroid receptors expression and increasing aromatase activity. In addition, dysregulation of the inflammasome pathway, mediated by an alteration of cellular responses to steroid hormones, participates in disease progression through preventing cell death, promoting adhesion, invasion, and cell proliferation. Furthermore, inflammation is involved in endometriosis-associated infertility, which alters endometrium receptivity by impairing biochemical responses and decidualization. The purpose of this review is to present current research about the role of inflammasome in the pathogenesis of endometriosis as well as the molecular role of sex hormones in the inflammatory responses in endometriosis.

DNA Methylation Inhibitor 5-Aza-2'-Deoxycytidine Modulates Endometrial Receptivity Through Upregulating HOXA10 Expression

Endometrial receptivity is a critical factor for embryo implantation. A decrease in endometrial homeobox A10 (HOXA10) expression is associated with hypermethylation of its promoter and lower endometrial receptivity in animals and humans. 5-Aza-2'-deoxycytidine (AZA) is a DNA methyltransferase inhibitor. However, whether demethylation of the HOXA10 gene could increase the receptivity of the human endometrium remains unknown. Homeobox A10 promoter methylation was analyzed using bisulfite genomic sequencing polymerase chain reaction. Quantitative real time polymerase chain reaction and Western blotting were used to analyze the expression of HOXA10 and its downstream target genes (integrin subunit β 3 [ITGB3] and insulin growth factor binding protein 1 [IGFBP1]) in Ishikawa cells treated with or without AZA for 24 hours. Their protein expression was analyzed with or without HOXA10 siRNA treatment. The effect of AZA on embryo implantation was examined using a Jeg-3 spheroid-endometrial cell attachment assay. The percentage of methylated CpG islands in the HOXA10 promoter was 72.0% without AZA treatment. However, it was 38% and 35% in the 1 and 10 μM AZA treatment groups, respectively. 5-Aza-2'-deoxycytidine strongly induced the expression of HOXA10, ITGB3, and IGFBP1 messenger RNA and their protein expression. Homeobox A10 knockdown led to decreased expression of HOXA10, ITGB3, and IGFBP1, with or without AZA treatment. The attachment rate of Jeg-3 spheroids increased significantly from 82% (control) to 95% (AZA 1 μM) and 96% (AZA 10 μM) after AZA treatment. 5-Aza-2'-deoxycytidine could upregulate the expression of ITGB3 and IGFBP1 via HOXA10 upregulation, and upregulation of ITGB3 and IGFBP1 plays an important role in endometrial receptivity during implantation. 5-Aza-2'-deoxycytidine may improve endometrial receptivity by upregulating the expression of HOXA10.

Differentially-Expressed miRNAs in Ectopic Stromal Cells Contribute to Endometriosis Development: The Plausible Role of miR-139-5p and miR-375

microRNA (miRNA) expression level alterations between endometrial tissue and endometriotic lesions indicate their involvement in endometriosis pathogenesis. However, as both endometrium and endometriotic lesions consist of different cell types in various proportions, it is not clear which cells contribute to variability in miRNA levels and the overall knowledge about cell-type specific miRNA expression in ectopic cells is scarce. Therefore, we utilized fluorescence-activated cell sorting to isolate endometrial stromal cells from paired endometrial and endometrioma biopsies and combined it with high-throughput sequencing to determine miRNA alterations in endometriotic stroma. The analysis revealed 149 abnormally expressed miRNAs in endometriotic lesions, including extensive upregulation of miR-139-5p and downregulation of miR-375 compared to eutopic cells. miRNA transfection experiments in the endometrial stromal cell line ST-T1b showed that the overexpression of miR-139-5p resulted in the downregulation of homeobox A9 (HOXA9) and HOXA10 expression, whereas the endothelin 1 (EDN1) gene was regulated by miR-375. The results of this study provide further insights into the complex molecular mechanisms involved in endometriosis pathogenesis and demonstrate the necessity for cell-type-specific analysis of ectopic tissues to understand the interactions between different cell populations in disease onset and progression.