Nuclear receptor, coregulator signaling, and chromatin remodeling pathways suggest involvement of the epigenome in the steroid hormone response of endometrium and abnormalities in endometriosis

MiR-135a-5p regulates window of implantation by suppressing pinopodes development and decidualization of endometrial stromal cells

PURPOSE

The window of implantation (WOI) is a brief period during which the endometrium is receptive to embryo implantation. This study investigated the relationship between miR-135a-5p and endometrial receptivity.

METHODS

Peripheral blood was collected on the day of ovulation and the 5th day after ovulation for high-throughput sequencing from women who achieved clinical pregnancy through natural cycle frozen embryo transfer. RT-qPCR assessed miR-135a-5p expression in the endometrium tissue or cells during the mouse implantation window or decidualization. Scanning electron microscopy was utilized to observe pinopode morphology and quantity in mice overexpressing miR-135a-5p during the WOI. Human endometrial stromal cells (HESC) and artificial induction of mouse uterine decidualization were used to explore whether miR-135a-5p overexpression inhibits decidualization by regulating HOXA10 and BMPR2. Furthermore, the impact of miR-135a-5p on HESC proliferation and HTR8/SVneo invasion was explored.

RESULTS

A total of 54 women were enrolled in the study. bioinformatics analysis and animal models demonstrated that miR-135a-5p was significantly downregulated during the WOI, and its high expression can lead to abnormal pregnancy outcomes. Overexpression of miR-135a-5p resulted in the absence of pinopode in mouse endometrial tissue during the WOI. High miR-135a-5p levels were found to potentially inhibit endometrial tissue decidualization by downregulating HOXA10 and BMPR2 expression. Finally, CEBPD was identified as a potential regulator of miR-135a-5p, which would explain the decreased miR-135a-5p expression during the WOI.

CONCLUSION

MiR-135a-5p expression is significantly downregulated during the WOI. High miR-135a-5p levels suppress pinopode development and endometrial tissue decidualization through HOXA10 and BMPR2, contributing to inadequate endometrial receptivity.

[Resolution of the national interdisciplinary council of experts "High-dose vitamin D (Devilam) in the practice of an obstetrician-gynecologist"]

On March 28, 2024, the Council of Experts "High-dose vitamin D (Devilam) in the practice of obstetrician-gynecologist, gynecologist and endocrinologist" was held in Moscow with the participation of leading experts gynecologists, endocrinologists and obstetricians-gynecologists, during which new possibilities for the use of high-dose vitamin D in patients of various ages who need correction of existing vitamin D deficiency or insufficiency.

Vitamins in Gynecologic Malignancies

The combination of vitamin A and D derivatives with classical chemotherapeutic treatments results in more satisfactory outcomes. The use of drug combinations, such as 9cUAB130 with carboplatin and cisplatin with TAC-101, shows enhanced cytotoxic effects and reductions in ovarian tumor volume compared to single-drug treatments. Combining cisplatin with calcitriol and progesterone increases VDR expression, potentially enhancing the effectiveness of anticancer therapy in ovarian cancer. The effectiveness of vitamin derivatives in anticancer treatment may vary depending on the characteristics of the tumor and the cell line from which it originated. An increase in thiamine intake of one unit is associated with an 18% decrease in HPV infection. Higher intake of vitamin C by 50 mg/day is linked to a lower risk of cervical neoplasia. Beta-carotene, vitamin C, and vitamin E are associated with risk reductions of 12%, 15%, and 9% in endometrial cancer, respectively. A balanced daily intake of vitamins is important, as both deficiency and excess can influence cancer development. It has been observed that there is a U-shaped relationship between group B vitamins and metabolic markers and clinical outcomes.

The roles of chromatin regulatory factors in endometriosis

PURPOSE

Endometriosis is an estrogen-dependent inflammatory disease and one of the most common gynecological diseases in women of reproductive age. The aim of the review was to explore the relationship between the chromatin regulatory factors and endometriosis.

METHODS

By searching for literature on chromatin regulators and endometriosis in PuMed. Finally, 98 documents were selected.

RESULTS

Chromatin regulators (CRs) are essential epigenetic regulatory factors that can regulate chromatin structure changes and are usually divided into three categories: DNA methylation compounds, histone modification compounds, and chromatin remodeling complexes. Noncoding RNAs are also chromatin regulators and can form heterochromatin by binding to protein complexes. Chromatin regulators cause abnormal gene expression by regulating chromatin structure, thereby affecting the occurrence and development of endometriosis.

CONCLUSION

This review summarizes the participation of chromatin regulators in the mechanisms of endometriosis, and these changes in related chromatin regulators provide a comprehensive reference for diagnosis and treatment of endometriosis.

Roles of bone morphogenetic proteins in endometrial remodeling during the human menstrual cycle and pregnancy

BACKGROUND

During the human menstrual cycle and pregnancy, the endometrium undergoes a series of dynamic remodeling processes to adapt to physiological changes. Insufficient endometrial remodeling, characterized by inadequate endometrial proliferation, decidualization and spiral artery remodeling, is associated with infertility, endometriosis, dysfunctional uterine bleeding, and pregnancy-related complications such as preeclampsia and miscarriage. Bone morphogenetic proteins (BMPs), a subset of the transforming growth factor-β (TGF-β) superfamily, are multifunctional cytokines that regulate diverse cellular activities, such as differentiation, proliferation, apoptosis, and extracellular matrix synthesis, are now understood as integral to multiple reproductive processes in women. Investigations using human biological samples have shown that BMPs are essential for regulating human endometrial remodeling processes, including endometrial proliferation and decidualization.

OBJECTIVE AND RATIONALE

This review summarizes our current knowledge on the known pathophysiological roles of BMPs and their underlying molecular mechanisms in regulating human endometrial proliferation and decidualization, with the goal of promoting the development of innovative strategies for diagnosing, treating and preventing infertility and adverse pregnancy complications associated with dysregulated human endometrial remodeling.

SEARCH METHODS

A literature search for original articles published up to June 2023 was conducted in the PubMed, MEDLINE, and Google Scholar databases, identifying studies on the roles of BMPs in endometrial remodeling during the human menstrual cycle and pregnancy. Articles identified were restricted to English language full-text papers.

OUTCOMES

BMP ligands and receptors and their transduction molecules are expressed in the endometrium and at the maternal-fetal interface. Along with emerging technologies such as tissue microarrays, 3D organoid cultures and advanced single-cell transcriptomics, and given the clinical availability of recombinant human proteins and ongoing pharmaceutical development, it is now clear that BMPs exert multiple roles in regulating human endometrial remodeling and that these biomolecules (and their receptors) can be targeted for diagnostic and therapeutic purposes. Moreover, dysregulation of these ligands, their receptors, or signaling determinants can impact endometrial remodeling, contributing to infertility or pregnancy-related complications (e.g. preeclampsia and miscarriage).

WIDER IMPLICATIONS

Although further clinical trials are needed, recent advancements in the development of recombinant BMP ligands, synthetic BMP inhibitors, receptor antagonists, BMP ligand sequestration tools, and gene therapies have underscored the BMPs as candidate diagnostic biomarkers and positioned the BMP signaling pathway as a promising therapeutic target for addressing infertility and pregnancy complications related to dysregulated human endometrial remodeling.

Exosomes as Theranostic Agents in Reproduction System

Exosomes (Exos), belonging to extracellular vesicles, are cell-derived nano-sized vesicles with the potential to carry different kinds of biological molecules. Many studies have proved the impacts of exosomal cargo on several biological processes in female and male reproductive systems. It is also hypothesized that changes in exosomal cargo are integral to the promotion of certain pathological conditions, thus Exos can be used as valid biomarkers for the diagnosis of infertility and other abnormal conditions. Here, efforts are made to collect some recent data related to the physiological significance of Exos in the reproductive system, and their potential therapeutic effects. It is anticipated that the current review article will lay the groundwork for elucidating the source and mechanisms by which Exos control the reproductive system additionally supplying fresh methods and concepts for the detection and treatment of disorders associated with fertility for future studies.

Association of endometriosis with Sjögren's syndrome: Genetic insights (Review)

Patients with a history of endometriosis have an increased risk of developing various autoimmune diseases such as rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, multiple sclerosis and celiac disease. There is a potential association between endometriosis and an increased susceptibility for Sjögren's syndrome (SS). SS is a common chronic, inflammatory, systemic, autoimmune, multifactorial disease of complex pathology, with genetic, epigenetic and environmental factors contributing to the development of this condition. It occurs in 0.5‑1% of the population, is characterized by the presence of ocular dryness, lymphocytic infiltrations and contributes to neurological, gastrointestinal, vascular and dermatological manifestations. Endometriosis is an inflammatory, estrogen‑dependent, multifactorial, heterogeneous gynecological disease, affecting ≤10% of reproductive‑age women. It is characterized by the occurrence of endometrial tissue outside the uterine cavity, mainly in the pelvic cavity, and is associated with pelvic pain, dysmenorrhea, deep dyspareunia and either subfertility or infertility. It is still unclear whether SS appears as a secondary response to endometriosis, or it is developed due to any potential shared mechanisms of these conditions. The aim of the present review was to explore further the biological basis only of the co‑occurrence of these disorders but not their association at clinical basis, focusing on the analysis of the partially shared genetic background between endometriosis and SS, and the clarification of the possible similarities in the underlying pathogenetic mechanisms and the relevant molecular pathways.

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.

Increased Expression of TGF-β1 Contributes to the Downregulation of Progesterone Receptor Expression in the Eutopic Endometrium of Infertile Women with Minimal/Mild Endometriosis

Endometriosis is a hormone-dependent disease associated with impaired immunoregulation. In our recent study, we have characterized the trascriptomic transformation of eutopic endometrium from patients with minimal/mild endometriosis and controls across the menstrual cycle. However, the regulatory mechanism of altered immune microenvironment in eutopic endometrial stromal cells (ESCs) remains unclear. Here, we want to explore the regulation of immune cell to progesterone resistance and endometrial receptivity in the eutopic ESCs by cytokine (TGF-β1), and to understand the effect of TGF-β1 on the decidualization of the eutopic ESCs. Primary culture of eutopic ESCs was performed to explore the effects of TGF-β1 on the expression of Smad and progesterone receptor (PR) and the in vitro decidualization. Additionally, co-immunoprecipitation (Co-IP) was used to explore the direct interaction between Smad and PR. We found an attenuate expression of PRB protein (p=0.026) after using TGF-β1 in eutopic ESCs, although the difference of PRA before and after treatment was not significant (p=0.678). Similarly, the results of qRT-PCR showed that the mRNA level of PR (p<0.001), PRB (p=0.003) and HOXA10 (p<0.001) decreased significantly after TGF-β1 treatment, but that increased (p<0.023, for all) after SB431542 treatment in the eutopic ESCs. Moreover, TGF-β1 has a negative effect on the in vitro decidualization of eutopic ESCs (p=0.003). And the group with treatment of both TGF-β1 and SB435142 in eutopic ESCs showed significant decidual-like changes with increased prolactin level (p=0.01). We did not observe any physical interaction between the PR and p-Smad3/Smad3 proteins by using Co-IP. By activating TGF-β/Smad signaling in eutopic ESCs, elevated TGF-β1 from CD45+ immune cells could attenuate expression of PR, and further decrease endometrial receptivity.

Vitamin D and Mitosis Evaluation in Endometriosis: A Step toward Discovering the Connection?

(1) Background: The effects of serum vitamin D levels, the vitamin D receptor (VDR), and phosphohistone H3 (PHH3) in endometriosis were investigated in two cohorts of women with this pathology: those receiving hormonal treatment and those without treatment. (2) Methods: In 60 cases of women with endometriosis (26 with progestin treatment and 34 without), paraffin-embedded endometriosis tissue samples retrieved after surgery were immunohistochemically (IHC) analyzed to determine the expression statuses of VDR and PHH3. In addition, serum levels of 25(OH) vitamin D were assessed for each patient. (3) Results: The serum 25(OH) vitamin D evaluations revealed higher levels of 25(OH) vitamin D in women with treatment compared with those without. The positive IHC indexes of VDR and PHH3 in these two groups were compared. Vitamin D receptor levels were positively correlated with PHH3 levels, both being increased in patients without treatment. (4) Conclusions: Serum 25(OH) vitamin D levels and IHC analysis of VDR and PHH3 can be used as additional tools for risk stratification and prognostic assessment in patients with endometriosis.

miR-297 inhibits expression of progesterone receptor and decidualization in eutopic endometria of endometriosis

AIM

Progesterone resistance is an epigenetic factor that reduces endometrial receptivity and causes implantation failure in women with endometriosis. In addition, dysregulated miRNAs contribute to the underlying pathogenic mechanisms of endometriosis. This study aimed to determine the effect of miR-297 on the progesterone receptor (PR) expression and on insufficient decidualization of endometrial stromal cells (ESCs) within the eutopic endometria of infertile women with minimal or mild endometriosis.

METHODS

ESCs were isolated from infertile endometriosis and normal patients and were transfected with miR-297 mimic or miR-297 inhibitor or respective control. qRT-PCR and western blot were conducted to quantify the expression of miR-297 and PR. The effect of miR-297 on ESCs decidualization was investigated by induced decidualization in vitro.

RESULTS

We observed an increase in miR-297 expression and a decrease in the expression of PR in the ESCs from endometriosis patients. Moreover, the expression of PR, most notably PRB, was found to be downregulated following transfection with miR-297 mimic and upregulated following treatment with miR-297 inhibitor. In addition, overexpressed miR-297 inhibited the decidualization of ESCs in vitro. We further determined that miR-297 exerts direct regulatory effects on PR expression.

CONCLUSIONS

We demonstrated that miR-297 interferes with fertility by repressing the expression of PR and preventing efficient decidualization in eutopic endometria. Further, miR-297 directly contributes to progesterone resistance in minimal or mild cases of endometriosis. Thus, regulation of miR-297 may prove to be a promising therapeutic strategy for endometriosis.

Effect of nonsteroidal anti-inflammatory drugs on the inflammatory response of bovine endometrial epithelial cells in vitro

Chronic postpartum uterine infection detrimentally affects subsequent fertility. Nonsteroidal anti-inflammatory drugs (NSAID) are used to alleviate pain and treat inflammatory conditions in transition dairy cows with varying success. To screen the efficacy of NSAID in the absence of animal experiments, we have established an in vitro model to study uterine inflammation. Inflammation was induced in cultured bovine endometrial epithelial cells by challenging cells with an inflammation cocktail: lipopolysaccharide and proinflammatory cytokines, interleukin-1β (IL1β) and tumor necrosis factor α (TNFα). Release of the inflammation markers, serum amyloid A (SAA) and α-1-acid glycoprotein (αAGP), was measured by ELISA. Concentration of these markers was used to indicate the effectiveness in dampening inflammation of 5 NSAID: meloxicam, flunixin meglumine, aspirin, ketoprofen, and tolfenamic acid. Three NSAID, meloxicam, flunixin meglumine, and tolfenamic acid, were successful at dampening the release of SAA and αAGP into cell-culture supernatant, and the corresponding treated cells were selected for down-stream mRNA expression analysis. Expression of 192 genes involved in regulation of inflammatory pathways were investigated using Nanostring. Of the genes investigated, 81 were above the mRNA expression-analysis threshold criteria and were included in expression analysis. All SAA genes investigated (SAA2, SAA3, M-SAA3.2) were upregulated in response to the inflammation cocktail, relative to mRNA expression in control cells; however, AGP mRNA expression was below the expression analysis threshold and was, therefore, excluded from analysis. Treatment with NSAID downregulated genes involved in regulating chemokine signaling (e.g., CXCL2, CXCR4, CXCL5, and CXCL16) and genes that regulate the eicosanoid pathway (e.g., LTA4H, PTGS2, PLA2G4A, and PTGDS). Of the 5 NSAID investigated, meloxicam, flunixin meglumine, and tolfenamic acid are recommended for further investigation into treatment of postpartum uterine inflammation. The results from this study confirm the immunomodulatory properties of the endometrial epithelium in response to inflammatory stimuli and suggest that NSAID may be beneficial in alleviating uterine inflammation.

Sex differences in musculoskeletal injury and disease risks across the lifespan: Are there unique subsets of females at higher risk than males for these conditions at distinct stages of the life cycle?

Sex differences have been reported for diseases of the musculoskeletal system (MSK) as well as the risk for injuries to tissues of the MSK system. For females, some of these occur prior to the onset of puberty, following the onset of puberty, and following the onset of menopause. Therefore, they can occur across the lifespan. While some conditions are related to immune dysfunction, others are associated with specific tissues of the MSK more directly. Based on this life spectrum of sex differences in both risk for injury and onset of diseases, a role for sex hormones in the initiation and progression of this risk is somewhat variable. Sex hormone receptor expression and functioning can also vary with life events such as the menstrual cycle in females, with different tissues being affected. Furthermore, some sex hormone receptors can affect gene expression independent of sex hormones and some transitional events such as puberty are accompanied by epigenetic alterations that can further lead to sex differences in MSK gene regulation. Some of the sex differences in injury risk and the post-menopausal disease risk may be "imprinted" in the genomes of females and males during development and sex hormones and their consequences only modulators of such risks later in life as the sex hormone milieu changes. The purpose of this review is to discuss some of the relevant conditions associated with sex differences in risks for loss of MSK tissue integrity across the lifespan, and further discuss several of the implications of their variable relationship with sex hormones, their receptors and life events.

Decidualization of human endometrial stromal cells requires steroid receptor coactivator-3

Steroid receptor coactivator-3 (SRC-3; also known as NCOA3 or AIB1) is a member of the multifunctional p160/SRC family of coactivators, which also includes SRC-1 and SRC-2. Clinical and cell-based studies as well as investigations on mice have demonstrated pivotal roles for each SRC in numerous physiological and pathophysiological contexts, underscoring their functional pleiotropy. We previously demonstrated the critical involvement of SRC-2 in murine embryo implantation as well as in human endometrial stromal cell (HESC) decidualization, a cellular transformation process required for trophoblast invasion and ultimately placentation. We show here that, like SRC-2, SRC-3 is expressed in the epithelial and stromal cellular compartments of the human endometrium during the proliferative and secretory phase of the menstrual cycle as well as in cultured HESCs. We also found that SRC-3 depletion in cultured HESCs results in a significant attenuation in the induction of a wide-range of established biomarkers of decidualization, despite exposure of these cells to a deciduogenic stimulus and normal progesterone receptor expression. These molecular findings are supported at the cellular level by the inability of HESCs to morphologically transform from a stromal fibroblastoid cell to an epithelioid decidual cell when endogenous SRC-3 levels are markedly reduced. To identify genes, signaling pathways and networks that are controlled by SRC-3 and potentially important for hormone-dependent decidualization, we performed RNA-sequencing on HESCs in which SRC-3 levels were significantly reduced at the time of administering the deciduogenic stimulus. Comparing HESC controls with HESCs deficient in SRC-3, gene enrichment analysis of the differentially expressed gene set revealed an overrepresentation of genes involved in chromatin remodeling, cell proliferation/motility, and programmed cell death. These predictive bioanalytic results were confirmed by the demonstration that SRC-3 is required for the expansion, migratory and invasive activities of the HESC population, cellular properties that are required in vivo in the formation or functioning of the decidua. Collectively, our results support SRC-3 as an important coregulator in HESC decidualization. Since perturbation of normal homeostatic levels of SRC-3 is linked with common gynecological disorders diagnosed in reproductive age women, this endometrial coregulator-along with its new molecular targets described here-may open novel clinical avenues in the diagnosis and/or treatment of a non-receptive endometrium, particularly in patients presenting non-aneuploid early pregnancy loss.

A New Perspective on Thyroid Hormones: Crosstalk with Reproductive Hormones in Females

Accumulating evidence has shown that thyroid hormones (THs) are vital for female reproductive system homeostasis. THs regulate the reproductive functions through thyroid hormone receptors (THRs)-mediated genomic- and integrin-receptor-associated nongenomic mechanisms, depending on TH ligand status and DNA level, as well as transcription and extra-nuclear signaling transduction activities. These processes involve the binding of THs to intracellular THRs and steroid hormone receptors or membrane receptors and the recruitment of hormone-response elements. In addition, THs and other reproductive hormones can activate common signaling pathways due to their structural similarity and shared DNA consensus sequences among thyroid, peptide, and protein hormones and their receptors, thus constituting a complex and reciprocal interaction network. Moreover, THs not only indirectly affect the synthesis, secretion, and action of reproductive hormones, but are also regulated by these hormones at the same time. This crosstalk may be one of the pivotal factors regulating female reproductive behavior and hormone-related diseases, including tumors. Elucidating the interaction mechanism among the aforementioned hormones will contribute to apprehending the etiology of female reproductive diseases, shedding new light on the treatment of gynecological disorders.

Tracing the cis-regulatory changes underlying the endometrial control of placental invasion

Among eutherian (placental) mammals, placental embedding into the maternal endometrium exhibits great differences, from being deeply invasive (e.g., humans) to noninvasive (e.g., cattle). The degree of invasion of placental trophoblasts is positively correlated with the rate of cancer malignancy. Previously, we have shown that fibroblasts from different species offer different levels of resistance to the invading trophoblasts as well as to cancer cell invasion. Here we present a comparative genomic investigation revealing cis-regulatory elements underlying these interspecies differences in invasibility. We identify transcription factors that regulate proinvasibility and antiinvasibility genes in stromal cells. Using an in vitro invasibility assay combined with CRISPR-Cas9 gene knockout, we found that the transcription factors GATA2 and TFDP1 strongly influence the invasibility of endometrial and skin fibroblasts. This work identifies genomic mechanisms explaining species differences in stromal invasibility, paving the way to therapies targeting stromal characteristics to regulate placental invasion, wound healing, and cancer dissemination.

Pathogenesis of Endometriosis: The Origin of Pain and Subfertility

Endometriosis (EM) and adenomyosis (AM) are common conditions with pain and infertility as the principal symptoms. The pathophysiology of pain in EM and AM comprises sensory and somatoform pain mechanisms. Over time, these may aggravate and lead to individual complex disease patterns if not diagnosed and treated. Despite the known facts, several years often pass between the onset of symptoms and diagnosis. Chronic pain disorders with changes on a neuronal level frequently arise and are linked to depressive disorders, with the process becoming a vicious cycle. Additionally, women with EM and AM suffer from sub- and infertility. Low fecundity rates are caused by anatomical changes in combination with behavioral changes in the sexual activity of women with chronic pain as well as local proinflammatory factors that not only decrease implantation rates but also promote early abortions.

Exosomes as Biomarkers for Female Reproductive Diseases Diagnosis and Therapy

Cell-cell communication is an essential mechanism for the maintenance and development of various organs, including the female reproductive system. Today, it is well-known that the function of the female reproductive system and successful pregnancy are related to appropriate follicular growth, oogenesis, implantation, embryo development, and proper fertilization, dependent on the main regulators of cellular crosstalk, exosomes. During exosome synthesis, selective packaging of different factors into these vesicles happens within the originating cells. Therefore, exosomes contain both genetic and proteomic data that could be applied as biomarkers or therapeutic targets in pregnancy-associated disorders or placental functions. In this context, the present review aims to compile information about the potential exosomes with key molecular cargos that are dysregulated in female reproductive diseases which lead to infertility, including polycystic ovary syndrome (PCOS), premature ovarian failure (POF), Asherman syndrome, endometriosis, endometrial cancer, cervical cancer, ovarian cancer, and preeclampsia, as well as signaling pathways related to the regulation of the reproductive system and pregnancy outcome during these pathological conditions. This review might help us realize the etiology of reproductive dysfunction and improve the early diagnosis and treatment of the related complications.

Vitamin D significance in pathogenesis of endometriosis

Genital endometriosis (GE) is a widespread multifactorial disease thus making it necessary to carry on studying its pathogeny in order to work out target therapy techniques. Studying vitamin D role in GE pathogeny is a new promising research trend.

PATIENTS AND TECHNIQUE

25(ОН)D level was determined in peripheral blood (PB) of 440 patients with GE and in peritoneal fluid (PF) - in 49 GE patients; the same test in PB was performed in 30 patients of the control group with the ovulatory menstrual cycle and no gynecologic pathology. 129 patients with GE, as well as 82 women of the control, underwent examination of vitamin D receptor (VDR) polymorphism gene in BsmI, FokI, and TaqI polymorphic locus. We examined vitamin D receptor expression in the eutopic and ectopic endometrium in 32 women with GE and in the endometrium of 20 women from the control group. We also compared the efficacy of combined therapy involving colecalciferol to the standard hormone modulating therapy.

RESULTS

It was established that the prevalent GE forms are characterized by lower 25(ОН)D levels both in PB and in PF. It was also found that G/G genotype of VDR BsmI gene polymorphic variant 1.9 times increases GE occurrence risk. VDR expression was authentically lower in the ectopic endometrium compared to the eutopic endometrium. Patients with GE show no VDR expression cyclic variations in the endometrium which is contrary to the control. Therapy in combination with colecalciferol promotes a more expressed decrease of endometriosis-associated pain syndrome and psycho-emotional stabilization of GE patients compared to the standard hormone modulating therapy.

CONCLUSION

Vitamin D deficiency plays a significant role in the pathogenesis of GE and Vit D may be applied as its targeted therapy.

Vitamin D deficiency as a risk factor for endometriosis in Iranian women

PURPOSE

Vitamin D (Vit D), as an immunomodulator, has been hypothesized to play a critical role in the pathogenesis of endometriosis. Thus, in this study, we evaluated whether there is an association between 25-hydroxyvitamin D [25(OH)D] and susceptibility to endometriosis in Iranian women.

METHODS

Women at reproductive age, including 56 healthy women and 54 patients with endometriosis, were enrolled in the study. Serum levels of 25(OH)D, calcium, parathyroid hormone (PTH), and peritoneal fluid (PF) levels of 25(OH)D were assessed.

RESULTS

The serum and PF levels of 25(OH)D in the patients with endometriosis were significantly lower than the control group (P = 0.001 and P = 0.03, respectively). Subjects with serum levels of 25(OH)D lower than 20 ng/mL had a 2.7 times higher risk of endometriosis than people with 25(OH)D serum levels higher than 20 ng/mL (non-deficient) (OR = 2.7, 95 % confidence interval: 1.24-5.80, P = 0.01). The serum levels of calcium and PTH were significantly lower and higher in patients with endometriosis compared with controls, respectively (P < 0.001, P = 0.02, respectively). Also, the serum levels of 25(OH)D were lower in stages I-II endometriosis than stage III-IV; however, no significant difference was observed.

CONCLUSION

Our findings showed that people with Vit D deficiency are at higher risk of endometriosis.

Circular RNA as a potential diagnostic and/or therapeutic target for endometriosis

Endometriosis is a pathology form of endometrium that behaves in a similar way to malignancies, such as invasion and resistance to apoptosis. Circular RNAs (CircRNAs) are a class of noncoding RNAs that have several biological functions including, miRNA sponging, sequestering of proteins, enhancing parental gene expression and translation resulting in polypeptides. In this review, we highlighted the roles of circRNAs as potential diagnostic and therapeutic biomarkers in endometriosis. Moreover, we summarized the roles of circRNAs in the pathogenesis of endometriosis via different signaling pathways, such as the miRNA network and apoptosis.

Epigenetic modifications working in the decidualization and endometrial receptivity

Decidualization is a critical event for the blastocyst implantation, placental development and fetal growth and the normal term. In mice, the embryo implantation to the uterine epithelial would trigger the endometrial stromal cells to differentiate into decidual stromal cells. However, decidualization in women takes place from the secretory phase of each menstrual cycle and continues to early pregnancy if there is conceptus. Deficient decidualization is often associated with pregnancy specific complications and reproductive disorders. Dramatic changes occur in the gene expression profiles during decidualization, which is coordinately regulated by steroid hormones, growth factors, and molecular and epigenetic mechanisms. Recently, emerging evidences showed that epigenetic modifications, mainly including DNA methylation, histone modification, and non-coding RNAs, play an important role in the decidualization process via affecting the target genes' expression. In this review, we will focus on the epigenetic modifications in decidualization and open novel avenues to predict and treat the pregnancy complications caused by abnormal decidualization.

Vitamin D Effects on the Immune System from Periconception through Pregnancy

Vitamin D is a well-known secosteroid and guardian of bone health and calcium homeostasis. Studies on its role in immunomodulatory functions have expanded its field in recent years. In addition to its impact on human physiology, vitamin D influences the differentiation and proliferation of immune system modulators, interleukin expression and antimicrobial responses. Furthermore, it has been shown that vitamin D is synthesized in female reproductive tissues and, by modulating the immune system, affects the periconception period and reproductive outcomes. B cells, T cells, macrophages and dendritic cells can all synthesize active vitamin D and are involved in processes which occur from fertilization, implantation and maintenance of pregnancy. Components of vitamin D synthesis are expressed in the ovary, decidua, endometrium and placenta. An inadequate vitamin D level has been associated with recurrent implantation failure and pregnancy loss and is associated with pregnancy-related disorders like preeclampsia. This paper reviews the most important data on immunomodulatory vitamin D effects in relation to the immune system from periconception to pregnancy and provides an insight into the possible consequences of vitamin D deficiency before and during pregnancy.

Characterization of VDR and CYP27B1 expression in the endometrium during the menstrual cycle before embryo transfer: implications for endometrial receptivity

BACKGROUND

Molecular analyses of vitamin D in a typical cycling endometrium has received minimal research attention in the reproductive field. This study was designed to assess how expression of the endometrial vitamin D receptor (VDR) and CYP27B1, a vitamin D metabolizing enzyme, change during the menstrual cycle in women of reproductive age. In addition, this study explores the association between expression of vitamin D-VDR system and endometrial receptivity during the implantation window.

METHODS

Sixteen patients underwent standardized in vitro fertilization (IVF) treatment and freeze-all techniques. Before embryo transfer, total serum 25(OH) D levels were determined through blood samples and VDR, CYP27B1, HOXA10, and CYP19 expression were determined through endometrial samples. Endometrial receptivity was also assessed using an electron microscope.

RESULTS

We found that VDR protein expression was significantly lower throughout the endometrial secretory phase compared to the proliferative phase, while CYP27B1 expression remained constant during the menstrual cycle. During the implantation window, ultrastructural evaluation showed that higher serum vitamin D levels were associated with more mature pinopodes; VDR and HOXA10 protein expression were substantially elevated in pregnant women compared to non-pregnant women; and VDR protein levels were positively correlated with HOXA10 levels. In addition, serum vitamin D levels were positively correlated with VDR and HOXA10 protein levels in the endometrium.

CONCLUSIONS

Women with increased VDR expression in the endometrium, especially during the implantation window of the menstrual cycle, were significantly more likely to be pregnant than women with decreased expression. Our results support the hypothesis that the Vitamin D-VDR system performs a role during the development of endometrial receptivity.

Endometriosis research in the -omics era

Endometriosis is a pathological condition extensively studied, but its pathogenesis is not completely understood, since its pathophysiology stems from a broad spectrum of environmental influences and genetic factors. Moreover, the nature of this condition is heterogeneous and includes different anatomical entities. Scientists actively pursue discovery of novel biomarkers in the hope of better identifying susceptible individuals in early stages of the disease. High-throughput technologies have substantially revolutionized medical research and, as a first step, the advent of genotyping arrays led to large-scale genome-wide association studies (GWAS) and enabled the assessment of global transcript levels, thus giving rise to integrative genetics. In this framework, comprehensive studies have been conducted at multiple biological levels by using the "omics" platforms, thus allowing to re-examine endometriosis at a greater degree of molecular resolution. -Omics technologies can detect and analyze hundreds of markers in the same experiment and their increasing use in the field of gynecology comes from an urgent need to find new diagnostic and therapeutic tools that improve the diagnosis of endometriosis and the efficacy of assisted reproductive techniques. Proteomics and metabolomics have been introduced recently into the every day methodology of researchers collaborating with gynecologists and, importantly, multi-omics approach is advantageous to gain insight of the total information that underlies endometriosis, compared to studies of any single -omics type. In this review, we expect to present multiple studies based on the high-throughput-omics technologies and to shed light in all considerable advantages that they may confer to a proper management of endometriosis.

Could DNA hydroxymethylation be crucial in influencing steroid hormone signaling in endometrial biology and endometriosis?

Endometriosis affects 10% of reproductive-aged women. It is characterized by the growth of the endometrium, outside the uterus and is associated with infertility and chronic abdominal pain. Lack of noninvasive diagnostic tools and early screening tests results in delayed treatment and subsequently increased disease severity. Endometriosis is a disease associated with a deregulated hormonal response, therefore, understanding the molecular mechanisms that govern this hormonal interplay is of paramount importance. DNA methylation is an epigenetic mark that regulates gene expression and is often associated with genes that code for steroid receptors and enzymes associated with estrogen synthesis and metabolism in endometriosis. DNA hydroxymethylation, which is structurally similar to methylation but functionally different, is a biologically critical mechanism that is also known to regulate gene expression. Ten Eleven Translocation (TET) proteins mediate hydroxymethylation. However, the role of DNA hydroxymethylation or TETs in the endometrium remains relatively unexplored. Currently, the "gold standard" technique used to study methylation patterns is bisulfite genomic sequencing. This technique also detects hydroxymethylation but fails to distinguish between the two, thereby limiting our understanding of these two processes. The presence of TETs in the male and female reproductive tract and its contribution to endometrial cancer makes it an important factor to study in endometriosis. This review summarizes the role of DNA methylation in aberrant steroid hormone signaling and hypothesizes that hydroxymethylation could be a factor influencing hormonal instability seen in endometriosis.

Pathogenesis of endometriosis: the genetic/epigenetic theory

OBJECTIVE

To study the pathophysiology of endometriosis.

DESIGN

Overview of observations on endometriosis.

SETTING

Not applicable.

PATIENT(S)

None.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

The hypothesis is compatible with all observations.

RESULT(S)

Endometriosis, endometrium-like tissue outside the uterus, has a variable macroscopic appearance and a poorly understood natural history. It is a hereditary and heterogeneous disease with many biochemical changes in the lesions, which are clonal in origin. It is associated with pain, infertility, adenomyosis, and changes in the junctional zone, placentation, immunology, plasma, peritoneal fluid, and chronic inflammation of the peritoneal cavity. The Sampson hypothesis of implanted endometrial cells following retrograde menstruation, angiogenic spread, lymphogenic spread, or the metaplasia theory cannot explain all observations if metaplasia is defined as cells with reversible changes and an abnormal behavior/morphology due to the abnormal environment. We propose a polygenetic/polyepigenetic mechanism. The set of genetic and epigenetic incidents transmitted at birth could explain the hereditary aspects, the predisposition, and the endometriosis-associated changes in the endometrium, immunology, and placentation. To develop typical, cystic ovarian or deep endometriosis lesions, a variable series of additional transmissible genetic and epigenetic incidents are required to occur in a cell which may vary from endometrial to stem cells. Subtle lesions are viewed as endometrium in a different environment until additional incidents occur. Typical cystic ovarian or deep endometriosis lesions are heterogeneous and represent three different diseases.

CONCLUSION(S)

The genetic epigenetic theory is compatible with all observations on endometriosis. Implications for treatment and prevention are discussed.

Reciprocal changes of H3K27ac and H3K27me3 at the promoter regions of the critical genes for endometrial decidualization

AIM

Decidualization is essential for embryo implantation and placental development. We aimed to obtain transcriptome and epigenome profiles for primary endometrial stromal cells (ESCs) and in vitro decidualized cells.

MATERIALS & METHODS

ESCs isolated from human endometrial tissues remained untreated (D0), or decidualized for 4 days (D4) and 8 days (D8) in the presence of 8-bromo-cAMP and progesterone.

RESULTS

Among the epigenetic modifications examined (DNA methylation, H3K27ac, H3K9me3 and H3K27me3), the H3K27ac patterns changed most dramatically, with a moderate correlation with gene expression changes, upon decidualization. Subsets of up- and down-regulated genes upon decidualization were associated with reciprocal changes of H3K27ac and H3K27me3 modifications at their promoter region, and were enriched with genes essential for decidualization such as WNT4, ZBTB16, PROK1 and GREB1.

CONCLUSION

Our dataset is useful to further elucidate the molecular mechanisms underlying decidualization.

Vitamin D and Endometrium: A Systematic Review of a Neglected Area of Research

Growing evidence supports a role of vitamin D (VD) in reproductive health. Vitamin D receptor (VDR) is expressed in the ovary, endometrium, and myometrium. The biological actions of VD in fertility and reproductive tissues have been investigated but mainly using animal models. Conversely, the molecular data addressing the mechanisms underlying VD action in the physiologic endometrium and in endometrial pathologies are still scant. Levels of VDR expression according to the menstrual cycle are yet to be definitively clarified, possibly being lower in the proliferative compared to the secretory phase and in mid-secretory compared to early secretory phase. Endometrial tissue also expresses the enzymes involved in the metabolism of VD. The potential anti-proliferative and anti-inflammatory effects of VD for the treatment of endometriosis have been investigated in recent years. Treatment of ectopic endometrial cells with 1,25(OH)₂D₃ could significantly reduce cytokine-mediated inflammatory responses. An alteration of VD metabolism in terms of increased 24-hydroxylase mRNA and protein expression has been demonstrated in endometrial cancer, albeit not consistently. The effect of the active form of the vitamin as an anti-proliferative, pro-apoptotic, anti-inflammatory, and differentiation-inducing agent has been demonstrated in various endometrial cancer cell lines.

SULFATION PATHWAYS: Contribution of intracrine oestrogens to the aetiology of endometriosis

Endometriosis is an incurable hormone-dependent inflammatory disease that causes chronic pelvic pain and infertility characterized by implantation and growth of endometrial tissue outside the uterine cavity. Symptoms have a major impact on the quality of life of patients resulting in socioeconomic, physical and psychological burdens. Although the immune system and environmental factors may play a role in the aetiology of endometriosis, oestrogen dependency is still considered a hallmark of the disorder. The impact of oestrogens such as oestrone and particularly, oestradiol, on the endometrium or endometriotic lesions may be mediated by steroids originating from ovarian steroidogenesis or local intra-tissue production (intracrinology) dependent upon the expression and activity of enzymes that regulate oestrogen biosynthesis and metabolism. Two key pathways have been implicated: while there is contradictory data on the participation of the aromatase enzyme (encoded by CYP19A1), there is increasing evidence that the steroid sulphatase pathway plays a role in both the aetiology and pathology of endometriosis. In this review, we consider the evidence related to the pathways leading to oestrogen accumulation in endometriotic lesions and how this might inform the development of new therapeutic strategies to treat endometriosis without causing the undesirable side effects of current regimes that suppress ovarian hormone production.

Progesterone Resistance in Endometriosis: an Acquired Property?

Endometriosis is the growth of endometrial tissue outside the uterus and is characterized by progesterone resistance and changes in global and progesterone target gene expression. However, the mechanism behind this and whether it is innate, acquired, or present in both the eutopic and ectopic tissue in not always clear. We find large-scale gene expression studies in eutopic tissue, indicative of progesterone resistance, are often contradictory, potentially due to the dynamic nature of this tissue, whereas suppressed progesterone receptor expression is supported in ectopic but not eutopic tissue. This suggests more studies are required in eutopic tissue particularly, and that potentially the suppressed progesterone receptor (PR) expression is a consequence of the pathogenic process and exposure to the peritoneal environment.

Molecular and Cellular Pathogenesis of Endometriosis

BACKGROUND

A substantial body of studies supports the view that molecular and cellular features of endometriotic lesions differ from those of eutopic endometrium. Apart from that, evidence exists that the eutopic endometrium from pa-tients with endometriosis differs from that of females without endometriosis.

OBJECTIVE

Aberrant expression profiles include a number of non-steroid signaling pathways that exert their putative influ-ence on the pathogenesis of endometriosis at least in part via crosstalk(s) with estrogen-mediated mechanisms. A rational to focus research on non-steroid signal pathways is that they might be remunerative targets for the development and selection of novel therapeutics to treat endometriosis possibly without affecting estrogen levels.

RESULTS AND CONCLUSION

In this article, we describe molecular and cellular features of endometriotic lesions and focus on the canonical WNT/β-signaling pathway, a key regulatory system in biology (including stem cell homeostasis) and often in pathophysiological conditions such as endometriosis. Recently emerged novel biological concepts in signal transduction and gene regulation like exosomes and microRNAs are discussed in their putative role in the pathogenesis of endometriosis.

Endometrial stromal cell attachment and matrix homeostasis in abdominal wall endometriomas

STUDY QUESTION

How does progesterone alter matrix remodeling in abdominal wall endometriomas compared with normal endometrium?

SUMMARY ANSWER

Progesterone may prevent attachment of endometrial cells to the abdominal wall, but does not ameliorate abnormal stromal cell responses of abdominal wall endometriomas.

WHAT IS KNOWN ALREADY

Menstruation is a tightly orchestrated physiologic event in which steroid hormones and inflammatory cells cooperatively initiate shedding of the endometrium. Abdominal wall endometriomas represent a unique form of endometriosis in which endometrial cells inoculate fascia or dermis at the time of obstetrical or gynecologic surgery. Invasion of endometrium into ectopic sites requires matrix metalloproteinases (MMPs) for tissue remodeling but endometrium is not shed externally.

STUDY DESIGN SIZE, DURATION

Observational study in 14 cases and 19 controls.

PARTICIPANTS /MATERIALS, SETTING, METHODS

Tissues and stromal cells isolated from 14 abdominal wall endometriomas were compared with 19 normal cycling endometrium using immunohistochemistry, quantitative PCR, gelatin zymography and cell attachment assays. P values < 0.05 were considered significant and experiments were repeated in at least three different cell preps to provide scientific rigor to the conclusions.

MAIN RESULTS AND THE ROLE OF CHANCE

The results indicate that MMP2 and MMP9 are not increased by TGFβ1 in endometrioma stromal cells. Although progesterone prevents attachment of endometrioma cells to matrix components of the abdominal wall, it does not ameliorate these abnormal stromal cell responses to TGFβ1.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

Endometriomas were collected from women identified pre-operatively. Not all endometriomas were collected. Stromal cells from normal endometrium were from different patients, not women undergoing endometrioma resection.

WIDER IMPLICATIONS OF THE FINDINGS

This work provides insight into the mechanisms by which progesterone may prevent abdominal wall endometriomas but, once established, are refractory to progesterone treatment.

STUDY FUNDING/COMPETING INTEREST(S)

Tissue acquisition was supported by NIH P01HD087150. Authors have no competing interests.

Abnormal Pathways in Endometriosis in Relation to Progesterone Resistance: A Review

Introduction

Endometriosis is an estrogen-dependent disorder, and recent studies suggest that progesterone resistance may contribute to the development and pathophysiology of the disorder. Based on this, identification of genetic and molecular perturbations in the endometrium of women with endometriosis is an important step towards understanding the pathogenesis of the disease, and the development of novel treatment and diagnostic strategies.

Methods

A systematic literature search in PubMed and Embase was performed, and 118 articles were identified for further screening. Two reviewers performed article screening independently using Covidence, and 16 studies fulfilled the inclusion criteria. The Newcastle-Ottawa Scale was used to assess the quality of these studies.

Results

This review presents data from eutopic endometrial biopsies from women with and without endometriosis. Several biomarkers related to a downregulated progesterone response were identified and discussed in detail.

Conclusions

Our review demonstrates significant results concerning the biomarkers investigated, which may substantiate the theory of progesterone resistance in women with endometriosis. However, further research is necessary to determine their specific role and relevance.

miR-196a overexpression activates the MEK/ERK signal and represses the progesterone receptor and decidualization in eutopic endometrium from women with endometriosis

STUDY QUESTION

Do microRNAs (miRNAs) contribute to aberrant progesterone receptor (PGR) expression in the eutopic endometrium of women with endometriosis? SUMMARY ANSWER: miR-196a upregulates MEK/ERK signalling, mediating a downregulation of PGR expression in the eutopic endometrium of women with minimal or mild endometriosis.

WHAT IS KNOWN ALREADY

Implantation failure is strongly suggested as an underlying cause for the observed infertility in minimal or mild endometriosis. Progesterone resistance, which is mainly caused by aberrantly expressed progesterone receptor in the eutopic endometrium, is considered as a key factor of decreased endometrial receptivity; thus far, epigenetics, but not miRNA, has been shown to affect PGR expression in the endometrium.

STUDY DESIGN SIZE, DURATION

Microarray analysis was used to analyse the eutopic endometrium. The differential expression of miR-196a was validated. Bioinformatics analysis predicted that miR-196a targets the 3'-untranslated region (UTR) of the PGR. The relationship between the miR-196a level and PGR expression was studied and the role of the MEK/ERK signal pathway was investigated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Total RNA was extracted from eutopic endometrium samples in three infertile women with mild/minimal endometriosis and three disease-free control subjects. The miRNA and mRNA expression levels were analysed by microarray analysis. The miR-196a expression was validated by qRT-PCR [endometriosis (n = 22) and control (n = 20)], while functional analysis utilised in vitro transfection of endometrial stromal cells (ESCs), induction of decidualization of ESCs, and luciferase reporter assays in 293 T cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 66 dysregulated miRNAs and 357 dysregulated mRNAs were screened by microarray analysis. miR-196a and P-MEK/P-ERK were both found to be significantly upregulated in the eutopic endometrium in patients with mild/minimal endometriosis. PGR and PGR-B mRNA were inhibited by miR-196a overexpression and upregulated by miR-196a inhibition. Luciferase reporter failed to confirm the target regulation of miR-196a on PGR. Transfection of ESCs with a miR-196a mimic led to an increase in the P-MEK/P-ERK protein levels, decrease in the PGR protein levels, and atypical decidualization. Following miR-196a inhibition, the P-MEK/P-ERK protein was downregulated and the PGR protein was upregulated. Inhibition of P-MEK/P-ERK also increased PGR expression.

LARGE SCALE DATA

Data are presented in Supplementary Tables SI and SII.

LIMITATIONS REASONS FOR CAUTION

This study focused on the role of miR-196a, and therefore does not involve other miRNAs; hence, it is possible that other miRNAs may also be responsible for progestin resistance in endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our data revealed altered miRNA expression and activated MEK/ERK signalling in the eutopic endometrium in minimal or mild endometriosis. We showed that the miR-196a level is associated with reduced expression of PGR isoforms through MEK/ERK, suggesting that miR-196a and MEK/ERK are both potential biomarkers of endometriosis. These results provide a novel approach to target the mechanisms behind progesterone resistance in endometriosis.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by the National Natural Science Foundation of China (No. 81370693). The authors have no conflicts of interest.

High-Fat Diet Promotion of Endometriosis in an Immunocompetent Mouse Model is Associated With Altered Peripheral and Ectopic Lesion Redox and Inflammatory Status

Endometriosis is a benign gynecological condition that causes considerable morbidity due to associated infertility, debilitating pelvic pain and inflammatory dysfunctions. Diet is a highly modifiable risk factor for many chronic diseases, but its contribution to endometriosis has not been extensively investigated, due partly to the paradoxical inverse association between obesity and disease incidence. Nevertheless, chronic exposure to dietary high-fat intake has been linked to greater systemic inflammation and oxidative stress, both features of women with endometriosis. Here, we evaluated the effects of a high-fat diet (HFD) (45% fat kcal) on endometriosis progression using an immunocompetent mouse model where ectopic lesion incidence was induced in wild-type recipients by ip administration of endometrial fragments from transcription factor Krüppel-like factor 9-null donor mice. We show that HFD significantly increased ectopic lesion numbers in recipient mice with no significant weight gain and modifications in systemic ovarian steroid hormone and insulin levels, relative to control diet-fed (17% fat kcal) mice. HFD promotion of lesion establishment was associated with reductions in stromal estrogen receptor 1 isoform and progesterone receptor expression, increased F4/80-positive macrophage infiltration, higher stromal but not glandular epithelial proliferation, and enhanced expression of proinflammatory and prooxidative stress pathway genes. Lesion-bearing HFD-fed mice also displayed higher peritoneal fluid TNFα and elevated local and systemic redox status than control diet-fed counterparts. Our results suggest that HFD intake exacerbates endometriosis outcome in the absence of ovarian dysfunction and insulin resistance in mice and warrants further consideration with respect to clinical management of endometriosis progression and recurrence in nonobese patients.

Barriers to a cure for HIV in women

Introduction

Distinct biological factors exist that affect the natural history of HIV and the host immune response between women and men. These differences must be addressed to permit the optimal design of effective HIV eradication strategies for much of the HIV-positive population.

Methods and results

Here, we review the literature on sex-based differences in HIV pathogenesis and natural history in tissues and anatomic compartments, HIV latency and transcriptional activity, and host immunity including the role of sex hormones. We then outline the potential effects of these differences on HIV persistence, and on the safety and efficacy of HIV eradication and curative interventions. Finally, we discuss the next steps necessary to elucidate these factors to achieve a cure for HIV, taking in account the complex ethical issues and the regulatory landscape in the hopes of stimulating further research and awareness in these areas.

Conclusions

Targeted enrolment of women in clinical trials and careful sex-based analysis will be crucial to gain further insights into sex-based differences in HIV persistence and to design sex-specific approaches to HIV eradication, if required.

Arginine methyltransferases mediate an epigenetic ovarian response to endometriosis

Endometriosis is associated with infertility and debilitating chronic pain. Abnormal epigenetic modifications in the human endometrium have recently been implicated in the pathogenesis of this condition. However, whether an altered epigenetic landscape contributes to pathological changes in the ovary is unknown. Using an established baboon endometriosis model, early-, and late-stage epigenetic changes in the ovary were investigated. Transcript profiling of key chromatin-modifying enzymes using pathway-focused PCR arrays on ovarian tissue from healthy control animals and at 3 and 15 months of endometriosis revealed dramatic changes in gene expression in a disease duration-dependent manner. Ingenuity Pathway Analysis indicated that transcripts for chromatin-remodeling enzymes associated with reproductive system disease and cancer development were abnormally regulated, most prominently the arginine methyltransferases CARM1, PRMT2, and PRMT8. Downregulation of CARM1 protein expression was also detected in the ovary, fully-grown oocytes and eutopic endometrium following 15 months of endometriosis. Sodium bisulfite sequencing revealed DNA hypermethylation within the PRMT8 promoter, suggesting that deregulated CpG methylation may play a role in transcriptional repression of this gene. These results demonstrate that endometriosis is associated with changes of epigenetic profiles in the primate ovary and suggest that arginine methyltransferases play a prominent role in mediating the ovarian response to endometriosis. Owing to the critical role of CARM1 in nuclear receptor-mediated transcription and maintenance of pluripotency in the cleavage stage embryo, our results suggest that epigenetic alterations in the ovary may have functional consequences for oocyte quality and the etiology of infertility associated with endometriosis.

Cyclic decidualization of the human endometrium in reproductive health and failure

Decidualization denotes the transformation of endometrial stromal fibroblasts into specialized secretory decidual cells that provide a nutritive and immunoprivileged matrix essential for embryo implantation and placental development. In contrast to most mammals, decidualization of the human endometrium does not require embryo implantation. Instead, this process is driven by the postovulatory rise in progesterone levels and increasing local cAMP production. In response to falling progesterone levels, spontaneous decidualization causes menstrual shedding and cyclic regeneration of the endometrium. A growing body of evidence indicates that the shift from embryonic to maternal control of the decidual process represents a pivotal evolutionary adaptation to the challenge posed by invasive and chromosomally diverse human embryos. This concept is predicated on the ability of decidualizing stromal cells to respond to individual embryos in a manner that either promotes implantation and further development or facilitates early rejection. Furthermore, menstruation and cyclic regeneration involves stem cell recruitment and renders the endometrium intrinsically capable of adapting its decidual response to maximize reproductive success. Here we review the endocrine, paracrine, and autocrine cues that tightly govern this differentiation process. In response to activation of various signaling pathways and genome-wide chromatin remodeling, evolutionarily conserved transcriptional factors gain access to the decidua-specific regulatory circuitry. Once initiated, the decidual process is poised to transit through distinct phenotypic phases that underpin endometrial receptivity, embryo selection, and, ultimately, resolution of pregnancy. We discuss how disorders that subvert the programming, initiation, or progression of decidualization compromise reproductive health and predispose for pregnancy failure.

Human endometrial DNA methylome is cycle-dependent and is associated with gene expression regulation

Human endometrium undergoes major gene expression changes, resulting in altered cellular functions in response to cyclic variations in circulating estradiol and progesterone, largely mediated by transcription factors and nuclear receptors. In addition to classic modulators, epigenetic mechanisms regulate gene expression during development in response to environmental factors and in some diseases and have roles in steroid hormone action. Herein, we tested the hypothesis that DNA methylation plays a role in gene expression regulation in human endometrium in different hormonal milieux. High throughput, genome-wide DNA methylation profiling of endometrial samples in proliferative, early secretory, and midsecretory phases revealed dynamic DNA methylation patterns with segregation of proliferative from secretory phase samples by unsupervised cluster analysis of differentially methylated genes. Changes involved different frequencies of gain and loss of methylation within or outside CpG islands. Comparison of changes in transcriptomes and corresponding DNA methylomes from the same samples revealed association of DNA methylation and gene expression in a number of loci, some important in endometrial biology. Human endometrial stromal fibroblasts treated in vitro with estradiol and progesterone exhibited DNA methylation changes in several genes observed in proliferative and secretory phase tissues, respectively. Taken together, the data support the observation that epigenetic mechanisms are involved in gene expression regulation in human endometrium in different hormonal milieux, adding endometrium to a small number of normal adult tissues exhibiting dynamic DNA methylation. The data also raise the possibility that the interplay between steroid hormone and methylome dynamics regulates normal endometrial functions and, if abnormal, may result in endometrial dysfunction and associated disorders.

The dynamics of nuclear receptors and nuclear receptor coregulators in the pathogenesis of endometriosis

BACKGROUND

Endometriosis is defined as the colonization and growth of endometrial tissue at anatomic sites outside the uterine cavity. Up to 15% of reproductive-aged women in the USA suffer from painful symptoms of endometriosis, such as infertility, pelvic pain, menstrual cycle abnormalities and increased risk of certain cancers. However, many of the current clinical treatments for endometriosis are not sufficiently effective and yield unacceptable side effects. There is clearly an urgent need to identify new molecular mechanisms that critically underpin the initiation and progression of endometriosis in order to develop more specific and effective therapeutics which lack the side effects of current therapies. The aim of this review is to discuss how nuclear receptors (NRs) and their coregulators promote the progression of endometriosis. Understanding the pathogenic molecular mechanisms for the genesis and maintenance of endometriosis as modulated by NRs and coregulators can reveal new therapeutic targets for alternative endometriosis treatments.

METHODS

This review was prepared using published gene expression microarray data sets obtained from patients with endometriosis and published literature on NRs and their coregulators that deal with endometriosis progression. Using the above observations, our current understanding of how NRs and NR coregulators are involved in the progression of endometriosis is summarized.

RESULTS

Aberrant levels of NRs and NR coregulators in ectopic endometriosis lesions are associated with the progression of endometriosis. As an example, endometriotic cell-specific alterations in gene expression are correlated with a differential methylation status of the genome compared with the normal endometrium. These differential epigenetic regulations can generate favorable cell-specific NR and coregulator milieus for endometriosis progression. Genetic alterations, such as single nucleotide polymorphisms and insertion/deletion polymorphisms of NR and coregulator genes, are frequently detected in ectopic lesions compared with the normal endometrium. These genetic variations impart new molecular properties to NRs and coregulators to increase their capacity to stimulate progression of endometriosis. Finally, post-translational modifications of NR coregulators, such as proteolytic processing, generate endometriosis-specific isoforms. Compared with the unmodified coregulators, these coregulator isoforms have unique functions that enhance the pathogenesis of endometriosis.

CONCLUSIONS

Epigenetic/genetic variations and posttranslational modifications of NRs and coregulators alter their original function so that they become potent 'drivers' of endometriosis progression.

DNA methylation patterns of steroid receptor genes ESR1, ESR2 and PGR in deep endometriosis compromising the rectum

Endometriosis is characterized by the presence of endometrial-like tissue located outside the uterine cavity. Recent evidence suggests that endometriosis may be an epigenetic disease, as well as an estrogen-dependent disease. Based on the unique steroid hormone receptor expression profile observed in endometriotic lesions as compared to eutopic endometrium, the present study aimed to gain further insight into the DNA methylation patterns of alternative promoters of the steroid receptor genes ESR1, ESR2 and PGR in intestinal deep endometriosis, one of the most aggressive forms of endometriosis. The DNA methylation patterns were evaluated by methylation-specific polymerase chain reaction (MS-PCR) after bisulfite modification in 44 endometriotic tissues as well as in 7 matched eutopic endometrium. No differences in the DNA methylation were observed for the ESR1 and ESR2 genes. Methylation of the PGR gene was observed in 39% (17 out of 44) and 19% (7 out of 37) of the cases in the promoter regions B (PGRB) and A (PGRA), respectively. Both PGR promoter regions were methylated in 3 cases. PGRB methylated alleles were detected exclusively in the endometriotic lesions when compared to the eutopic endometrium obtained from the same patient. The effect of DNA methylation in inhibiting the PGR gene expression was corroborated by immuno-staining for PgR protein in a subset of tissue samples. The present study demonstrated that epigenetic changes occur in both promoter regions of the PGR gene in intestinal endometriosis. Since eutopic and ectopic tissues do not respond sufficiently to progesterone in women with endometriosis, further study is necessary to evaluate the effect of epigenetic alterations in progesterone-resistance in this enigmatic disease.

Guidelines for the design, analysis and interpretation of 'omics' data: focus on human endometrium

BACKGROUND

'Omics' high-throughput analyses, including genomics, epigenomics, transcriptomics, proteomics and metabolomics, are widely applied in human endometrial studies. Analysis of endometrial transcriptome patterns in physiological and pathophysiological conditions has been to date the most commonly applied 'omics' technique in human endometrium. As the technologies improve, proteomics holds the next big promise for this field. The 'omics' technologies have undoubtedly advanced our knowledge of human endometrium in relation to fertility and different diseases. Nevertheless, the challenges arising from the vast amount of data generated and the broad variation of 'omics' profiling according to different environments and stimuli make it difficult to assess the validity, reproducibility and interpretation of such 'omics' data. With the expansion of 'omics' analyses in the study of the endometrium, there is a growing need to develop guidelines for the design of studies, and the analysis and interpretation of 'omics' data.

METHODS

Systematic review of the literature in PubMed, and references from relevant articles were investigated up to March 2013.

RESULTS

The current review aims to provide guidelines for future 'omics' studies on human endometrium, together with a summary of the status and trends, promise and shortcomings in the high-throughput technologies. In addition, the approaches presented here can be adapted to other areas of high-throughput 'omics' studies.

CONCLUSION

A highly rigorous approach to future studies, based on the guidelines provided here, is a prerequisite for obtaining data on biological systems which can be shared among researchers worldwide and will ultimately be of clinical benefit.

Vitamin D in endometriosis: a causative or confounding factor?

OBJECTIVE

The aim of this paper is to review the evidence from studies that evaluated the relationship between vitamin D and endometriosis.

DESIGN

Comprehensive review.

MATERIALS AND METHODS

Systematic literature search in Medline for relevant publications from 1946 until June 2013.

RESULTS

Endometriosis risk may be influenced by dietary vitamin D intake and plasma hydroxyvitamin D concentration. Vitamin D receptor and vitamin D metabolizing enzymes, 24-hydroxylase and 1-α hydroxylase, are found in the normal cycling endometrium and also in the eutopic and ectopic endometrium of women with endometriosis. The endometrium is a target of 1, 25 dihydroxyvitamin D actions through regulation of specific genes and via immunomodulation. The endometrium in endometriosis expresses dysregulation of some vitamin D enzymes and receptors. If vitamin D and its metabolites are implicated in endometriosis-associated infertility, it is likely through interference with HOXA10 gene expression. The Gc2 phenotype of vitamin D binding protein is prevalent in women with endometriosis and may be implicated in its pathogenesis. In a mouse model, Elocalcitol, a VDR-agonist was shown to reduce the development of endometriotic lesions and recurrence.

CONCLUSION

A biological plausibility for a role of vitamin D, as an immunomodulator and anti-inflammatory agent, in the pathogenesis and treatment of endometriosis is suggested in this article, but is difficult to illustrate due to sparse evidence from human studies limited primarily to case-control studies. A significant knowledge gap precludes the establishment of a clear cause-effect relationship. The intriguing leads presented herein need to be investigated further with placebo-controlled supplementation trials.