Endometriosis: the pathophysiology as an estrogen-dependent disease

Exercise and endometriosis-is there a promising future? A narrative review

BACKGROUND

Endometriosis is the leading cause of chronic pelvic pain in women of reproductive age with debilitating effects on quality of life, yet no cure exists. Exercise yields the potential in providing women with a non-invasive, non-pharmacological method of symptom control.

AIM(S)

Present up-to-date knowledge regarding how exercise may contribute to the management of endometriosis-related symptoms.

OBJECTIVE(S)

Discuss: 1. The pathophysiology surrounding exercise and endometriosis. 2. The role of exercise in endometriosis symptom control.

RATIONALE

Scientific literature has alluded to exercise being a favourable factor in the management of endometriosis-related symptoms. Moreover, current clinical guidelines for endometriosis fail to reflect the aforementioned benefits of exercise.

SEARCH STRATEGY

A search strategy using the terms 'endometriosis', 'endometriomas', 'exercise', and 'physical activity' was devised. Pubmed, Medline, Cochrane reviews, and Embase were reviewed.

INCLUSION CRITERIA

Interventional studies, within-subjects studies, randomised-control trials, systematic reviews, meta-analysis, cohort studies, publication since 2000.

EXCLUSION CRITERIA

Non-English publications, non-human studies.

RESULTS

Numerous studies have suggested positive effects for endometriosis patients who performed exercise exclusively or in conjunction with other therapies. Improvements in pain levels, quality of life, anxiety, and depression were noted.

DISCUSSION

Current research outlines promise regarding the potential benefit of exercise prescribing in patients with endometriosis as well as a synergy between exercise and hormonal therapies for the management of endometriosis-related symptoms. However, the current paucity of high-quality robust studies investigating these aspects of endometriosis management is an apparent obstacle to progression in this area.

CONCLUSION

For clinicians to incorporate exercise in managing endometriosis, clear recommendations regarding advice and benefits are needed.

Macrophage polarization in adenomyosis: A review

Adenomyosis (AM) is a common gynecological disorder characterized by the presence of endometrial glands and stroma within the uterine myometrium. It is associated with abnormal uterine bleeding (AUB), dysmenorrhea, and infertility. Although several mechanisms have been proposed to elucidate AM, the exact cause and development of the condition remain unclear. Recent studies have highlighted the significance of macrophage polarization in the microenvironment, which plays a crucial role in AM initiation and progression. However, a comprehensive review regarding the role and regulatory mechanism of macrophage polarization in AM is currently lacking. Therefore, this review aims to summarize the phenotype and function of macrophage polarization and the phenomenon of the polarization of adenomyosis-associated macrophages (AAMs). It also elaborates on the role and regulatory mechanism of AAM polarization in invasion/migration, fibrosis, angiogenesis, dysmenorrhea, and infertility. Furthermore, this review explores the underlying molecular mechanisms of AAM polarization and suggests future research directions. In conclusion, this review provides a new perspective on understanding the pathogenesis of AM and provides a theoretical foundation for developing targeted drugs through the regulation of AAM polarization.

Microbiota in Irritable Bowel Syndrome and Endometriosis: Birds of a Feather Flock Together-A Review

Endometriosis and irritable bowel syndrome (IBS) are chronic conditions affecting up to 10% of the global population, imposing significant burdens on healthcare systems and patient quality of life. Interestingly, around 20% of endometriosis patients also present with symptoms indicative of IBS. The pathogenesis of both these multifactorial conditions remains to be fully elucidated, but connections to gut microbiota are becoming more apparent. Emerging research underscores significant differences in the gut microbiota composition between healthy individuals and those suffering from either endometriosis or IBS. Intestinal dysbiosis appears pivotal in both conditions, exerting an influence via similar mechanisms. It impacts intestinal permeability, triggers inflammatory reactions, and initiates immune responses. Furthermore, it is entwined in a bidirectional relationship with the brain, as part of the gut-brain axis, whereby dysbiosis influences and is influenced by mental health and pain perception. Recent years have witnessed the development of microbiota-focused therapies, such as low FODMAP diets, prebiotics, probiotics, antibiotics, and fecal microbiota transplantation, designed to tackle dysbiosis and relieve symptoms. While promising, these treatments present inconsistent data, highlighting the need for further research. This review explores the evidence of gut dysbiosis in IBS and endometriosis, underscoring the similar role of microbiota in both conditions. A deeper understanding of this common mechanism may enable enhanced diagnostics and therapeutic advancements.

Vanillin prevents the growth of endometriotic lesions through anti-inflammatory and antioxidant pathways in a mouse model

Endometriosis is an estrogen-dependent chronic inflammatory gynecological disease defined by the presence of endometrial glands and mesenchyme outside the uterine cavity, named ectopic endometrium. Recent studies showed that endometriosis is associated with hormone imbalance, inflammation and oxidative stress. As the main component of vanilla bean extract, vanillin is widely used as a flavoring agent in the food, pharmaceutical, and cosmetic industries. It is known for its anti-inflammatory, antibacterial, and antitumor properties, but its therapeutic efficacy in endometriosis has not been studied. In this study, we evaluated the roles of vanillin in this disease using an induced endometriotic mouse model. The results showed that vanillin significantly inhibited the growth of endometrial lesions. Compared with the control group, the weight and volume of lesions were reduced considerably in the vanillin-treated group, showing its fantastic ability to inhibit cell proliferation and promote apoptosis. In addition, in the treatment group, mRNA expression of the pro-inflammatory cytokines Tnfa, Infg, Il1b, and Il6 was reduced, the number of macrophages and neutrophils was decreased, and the NF-κB signaling pathway was inhibited, indicating that vanillin suppressed the inflammatory response in the ectopic endometrium. Besides, we found that the intensity of tissue reactive oxygen species (ROS) was significantly lower, and mitochondrial complex IV expression was reduced in the vanillin-treated group. Meanwhile, treatment of the immortalized human endometriotic epithelial cell line (11Z) with vanillin resulted in the downregulation of cyclin genes that drive the cell proliferation process, inhibited cell proliferation, promoted apoptosis, and downregulated the expression of LPS-induced inflammatory cytokines. Most importantly, our data showed that the vanillin treatment had only minimal effects on the eutopic endometrium with respect to the pregnancy process, indicating its safety to be used in treating endometriosis in adults. In conclusion, our data suggest that vanillin has potential therapeutic properties for endometriosis as a regulatory molecule of cell proliferation, apoptosis, inflammation, and oxidative stress.

How Do Microorganisms Influence the Development of Endometriosis? Participation of Genital, Intestinal and Oral Microbiota in Metabolic Regulation and Immunopathogenesis of Endometriosis

Microorganisms inhabiting the human body play an extremely key role in its proper functioning, as well as in the development of the immune system, which, by maintaining the immune balance, allows you to enjoy health. Dysbiosis of the intestinal microbiota, or in the oral cavity or reproductive tract, understood as a change in the number and diversity of all microorganisms inhabiting them, may correlate with the development of many diseases, including endometriosis, as researchers have emphasized. Endometriosis is an inflammatory, estrogen-dependent gynecological condition defined by the growth of endometrial cells outside the uterine cavity. Deregulation of immune homeostasis resulting from microbiological disorders may generate chronic inflammation, thus creating an environment conducive to the increased adhesion and angiogenesis involved in the development of endometriosis. In addition, research in recent years has implicated bacterial contamination and immune activation, reduced gastrointestinal function by cytokines, altered estrogen metabolism and signaling, and abnormal progenitor and stem cell homeostasis, in the pathogenesis of endometriosis. The aim of this review was to present the influence of intestinal, oral and genital microbiota dysbiosis in the metabolic regulation and immunopathogenesis of endometriosis.

Potent Dual Inhibitors of Steroid Sulfatase and 17β-Hydroxysteroid Dehydrogenase Type 1 with a Suitable Pharmacokinetic Profile for In Vivo Proof-of-Principle Studies in an Endometriosis Mouse Model

Treating estrogen-dependent diseases like endometriosis with drugs suppressing local estrogen activation may be superior to existing endocrine therapies. Steroid sulfatase (STS) and 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) are key enzymes of local estrogen activation. We describe the rational design, synthesis, and biological profilation of furan-based compounds as a novel class of dual STS/17β-HSD1 inhibitors (DSHIs). In T47D cells, compound 5 showed irreversible inhibition of STS and potent, reversible inhibition of 17β-HSD1. It was selective over 17β-HSD2 and displayed high metabolic stabilities in human and mouse liver S9 fractions. No effect on cell viability was detected up to 31 μM (HEK293) and 23 μM (HepG2), respectively, and there was no activation of the aryl hydrocarbon receptor (AhR) up to 3.16 μM. Single daily application to mice revealed steady-state plasma levels high enough to make this compound eligible for an in vivo proof-of-principle study in a mouse endometriosis model.

CFP1 governs uterine epigenetic landscapes to intervene in progesterone responses for uterine physiology and suppression of endometriosis

Progesterone (P₄) is required for the preparation of the endometrium for a successful pregnancy. P₄ resistance is a leading cause of the pathogenesis of endometrial disorders like endometriosis, often leading to infertility; however, the underlying epigenetic cause remains unclear. Here we demonstrate that CFP1, a regulator of H3K4me3, is required for maintaining epigenetic landscapes of P₄-progesterone receptor (PGR) signaling networks in the mouse uterus. Cfp1^f/f;Pgr-Cre (Cfp1^d/d) mice showed impaired P₄ responses, leading to complete failure of embryo implantation. mRNA and chromatin immunoprecipitation sequencing analyses showed that CFP1 regulates uterine mRNA profiles not only in H3K4me3-dependent but also in H3K4me3-independent manners. CFP1 directly regulates important P₄ response genes, including Gata2, Sox17, and Ihh, which activate smoothened signaling pathway in the uterus. In a mouse model of endometriosis, Cfp1^d/d ectopic lesions showed P₄ resistance, which was rescued by a smoothened agonist. In human endometriosis, CFP1 was significantly downregulated, and expression levels between CFP1 and these P₄ targets are positively related regardless of PGR levels. In brief, our study provides that CFP1 intervenes in the P₄-epigenome-transcriptome networks for uterine receptivity for embryo implantation and the pathogenesis of endometriosis.

Regulation of HAND2 Expression by LncRNA HAND2-AS1 in Ovarian Endometriosis Involving DNA Methylation

HAND2 is a critical mediator of progesterone receptor signaling in endometrium. Silencing of HAND2 expression is associated with female infertility and endometrial cancers. We recently observed that lncRNA HAND2-AS1 and HAND2 are expressed coordinately in human endometrial stromal cells. To investigate involvement of HAND2-AS1 and HAND2 in pathogenesis of endometriosis, we employed immunohistochemistry, in situ hybridization, and quantitative real-time PCR to assess their expression in normal endometrium and the ectopic lesions obtained from patients with ovarian endometriosis. HAND2 promoter methylation was also monitored in these samples. Our results revealed that HAND2 and HAND2-AS1 expression levels were reduced but promoter methylation was enhanced significantly in ectopic endometrium when compared with the normal controls. Fluorescence in situ hybridization showed that HAND-AS1 is predominantly localized in the nuclei of endometrial stromal cells in contrast to the cytoplasmic distribution in epithelial cell compartment. To further investigate regulation of HAND2 expression by HAND2-AS1, HAND2-AS1 was silenced or overexpressed in human endometrial stromal cells. Our studies showed that expression levels of HAND2 and its direct target IL15 were attenuated markedly in HAND2-AS1 silenced cells but enhanced significantly in the overexpressed human endometrial stromal cells. Silencing of HAND2-AS1 also impaired endometrial stromal cell decidualization as indicated by downregulation of decidual biomarkers IGFBP1 and PRL. In addition, HAND2 promoter methylation was also enhanced upon HAND2-AS1 silencing. RNA immunoprecipitation studies further revealed that HAND2-AS1 is capable of binding to DNA methyltransferase DNMT1, indicating that HAND2-AS1 governs HAND2 expression epigenetically involving DNA methylation.

Macrophages and small extracellular vesicle mediated-intracellular communication in the peritoneal microenvironment: Impact on endometriosis development

Endometriosis is an inflammatory disease that is defined as the growth of endometrium-like tissue outside the uterus, commonly on the lining of the pelvic cavity, visceral organs and in the ovaries. It affects around 190 million women of reproductive age worldwide and is associated with chronic pelvic pain and infertility, which greatly impairs health-related life quality. The symptoms of the disease are variable, this combined with a lack of diagnostic biomarkers and necessity of surgical visualisation to confirm disease, the prognosis can take an average timespan of 6–8 years. Accurate non-invasive diagnostic tests and the identification of effective therapeutic targets are essential for disease management. To achieve this, one of the priorities is to define the underlying pathophysiological mechanisms that contribute to endometriosis. Recently, immune dysregulation in the peritoneal cavity has been linked to endometriosis progression. Macrophages account for over 50% of immune cells in the peritoneal fluid and are critical for lesion growth, angiogenesis, innervation and immune regulation. Apart from the secretion of soluble factors like cytokines and chemokines, macrophages can communicate with other cells and prime disease microenvironments, such as the tumour microenvironment, via the secretion of small extracellular vesicles (sEVs). The sEV-mediated intracellular communication pathways between macrophages and other cells within the peritoneal microenvironment in endometriosis remain unclear. Here, we give an overview of peritoneal macrophage (pMΦ) phenotypes in endometriosis and discuss the role of sEVs in the intracellular communication within disease microenvironments and the impact they may have on endometriosis progression.

Molecular Targets for Nonhormonal Treatment Based on a Multistep Process of Adenomyosis Development

Adenomyosis is an estrogen-dependent gynecologic disease characterized by the presence of endometrial tissue within the myometrium. Adenomyosis presents with abnormal uterine bleeding, pelvic pains, and infertility. This review aimed to investigate the major estrogen downstream effectors involved in the process of adenomyosis development and their potential use for nonhormonal treatment. A literature search was performed for preclinical and clinical studies published between January 2010 and November 2021 in the PubMed and Google Scholar databases using a combination of specific terms. Adenomyosis presents with a wide spectrum of clinical manifestations from asymptomatic to severe through a complex process involving a series of molecular changes associated with inflammation, invasion, angiogenesis, and fibrosis. Adenomyosis may develop through a multistep process, including the acquisition of (epi)genetic mutations, tissue injury caused at the endometrial-myometrial interface, inside-to-outside invasion (from the endometrial side into the uterine wall), or outside-to-inside invasion (from the serosal side into the uterine wall), and epithelial-mesenchymal transition, tissue repair or remodeling in the myometrium. These processes can be regulated by increased estrogen biosynthesis and progesterone resistance. The expression of estrogen downstream effectors associated with persistent inflammation, fragile and more permeable vessel formation, and tissue injury and remodeling may be correlated with dysmenorrhea, heavy menstrual bleeding, and infertility, respectively. Key estrogen downstream targets (e.g., WNT/β-catenin, transforming growth factor-β, and nuclear factor-κB) may serve as hub genes. We reviewed the molecular mechanisms underlying the development of adenomyosis and summarized potential nonhormonal therapies.

HRT in Women Undergoing Pelvic Clearance for Endometriosis-A Case Report and a National Survey

The optimal hormone replacement therapy (HRT) in women who have undergone pelvic clearance for endometriosis remains uncertain with insufficient evidence. The purpose of this case report and the national survey was to highlight the potential HRT-related risks and to establish current HRT practice in this group of women. The case was a 45-year-old woman presenting with recurrence of severe chronic pelvic pain while on oestrogen-only HRT (EO-HRT) for five years after subtotal hysterectomy and bilateral oophorectomy for severe endometriosis. MRI revealed multiple peri-cervical endometriomas and severe right hydroureter/hydronephrosis with complete right renal parenchymal loss. The survey was a 21-item questionnaire administered electronically using SurveyMonkey. It was reviewed and approved by British Menopause Society and British Society of Gynaecological endoscopy and was sent to their members as well as NHS Gynaecologists. A total of 216 physicians responded including 120 (55.6%) Gynaecology Consultants and 96 (44.4%) GPs/Nurses in Menopause clinics. Overall, 68.6% of responders prescribe combined HRT (C-HRT), 11.1% tibolone, 13.0% EO-HRT and 7.8% varied HRT. Fifty-one percent prescribe the progestogen component of C-HRT indefinitely, 22% for 3-6 months and 27% for varied durations. In conclusion, this study highlights the real risk of endometriosis recurrence in EO-HRT users after pelvic clearance for endometriosis. The survey revealed that only two thirds of Gynecologists/Menopause practitioners prescribe combined HRT in this group of women.

The bidirectional relationship between endometriosis and microbiome

Endometriosis has been described by many different theories of pathogenesis over the years. It is now also appreciated to be a state of chronic inflammation, and the role of immune dysfunction in its development has been proven. There is increasing evidence to support the role of the microbiome in the formation and progression of endometriosis via inflammatory pathways. The dysbiosis seen in endometriosis is thought to be both causative and a consequence of the pathogenesis. Gut, peritoneal fluid and female reproductive tract microbiota has been studied to understand if there are any microbiome signatures specific to endometriosis. New research on how to manipulate the microbiome for better detection and treatment of endometriosis is emerging.

Clinical Diagnosis and Early Medical Management for Endometriosis: Consensus from Asian Expert Group

This work provides consensus guidance regarding clinical diagnosis and early medical management of endometriosis within Asia. Clinicians with expertise in endometriosis critically evaluated available evidence on clinical diagnosis and early medical management and their applicability to current clinical practices. Clinical diagnosis should focus on symptom recognition, which can be presumed to be endometriosis without laparoscopic confirmation. Transvaginal sonography can be appropriate for diagnosing pelvic endometriosis in select patients. For early empiric treatment, management of women with clinical presentation suggestive of endometriosis should be individualized and consider presentation and therapeutic need. Medical treatment is recommended to reduce endometriosis-associated pelvic pain for patients with no immediate pregnancy desires. Hormonal treatment can be considered for pelvic pain with a clinical endometriosis diagnosis; progestins are a first-line management option for early medical treatment, with oral progestin-based therapies generally a better option compared with combined oral contraceptives because of their safety profile. Dienogest can be used long-term if needed and a larger evidence base supports dienogest use compared with gonadotropin-releasing hormone agonists (GnRHa) as first-line medical therapy. GnRHa may be considered for first-line therapy in some specific situations or as short-term therapy before dienogest and non-steroidal anti-inflammatory drugs as add-on therapy for endometriosis-associated pelvic pain.

The Phytochemical Profile and Biological Activity of Malva neglecta Wallr. in Surgically Induced Endometriosis Model in Rats

Leaves and aerial parts of Malva neglecta Wallr. have been traditionally used in Anatolia for the treatment of pain, inflammation, hemorrhoids, renal stones, constipation, and infertility. This study investigated the effects of M. neglecta leaves in a rat endometriosis model. The dried plant material was extracted with n-hexane, ethyl acetate, and methanol, successively. Experimental endometriosis was surgically induced in six-week-old female, non-pregnant, Wistar albino rats by autotransplant of endometrial tissue to the abdominal wall. After twenty-eight days, rats were evaluated for a second laparotomy. Endometrial foci areas were assessed, and intraabdominal adhesions were scored. Rats were divided into five groups as control, n-hexane, ethyl acetate, methanol, and aqueous extracts, as well as reference. At the end of the treatment, all rats were sacrificed and endometriotic foci areas and intraabdominal adhesions were re-evaluated and compared with the previous findings. Moreover, peritoneal fluid was collected to detect tumor necrosis factor- α (TNF-α), vascular endothelial growth factor (VEGF), and interleukin-6 (IL-6) levels, and cDNA synthesis, and a quantitative real-time polymerase chain reaction (PCR) test was done. The phytochemical content of the most active extract was determined using High-Performance Liquid Chromatography (HPLC). Both endometrial volume and adhesion score decreased significantly in the group treated with methanol extract. In addition, significant decreases were observed in TNF-α, VEGF, and IL-6 levels in animals administered methanol extract. HPLC results showed that the activity caused by the methanol extract of M. neglecta was due to the polyphenols. Taken together, these novel findings indicate that M. neglecta may be a promising alternative for the treatment of endometriosis.

Pathogenic Role of the Sphingosine 1-Phosphate (S1P) Pathway in Common Gynecologic Disorders (GDs): A Possible Novel Therapeutic Target

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid, noteworthy for its involvement both in the modulation of various biological processes and in the development of many diseases. S1P signaling can be either pro or anti-inflammatory, and the sphingosine kinase (SphK)–S1P–S1P receptor (S1PR) axis is a factor in accelerating the growth of several cells, including endometriotic cells and fibrosis. Gynecologic disorders, including endometriosis, adenomyosis, and uterine fibroids are characterized by inflammation and fibrosis. S1P signaling and metabolism have been shown to be dysregulated in those disorders and they are likely implicated in their pathogenesis and pathophysiology. Enzymes responsible for inactivating S1P are the most affected by the dysregulation of S1P balanced levels, thus causing accumulation of sphingolipids within these cells and tissues. The present review highlights the past and latest evidence on the role played by the S1P pathways in common gynecologic disorders (GDs). Furthermore, it discusses potential future approaches in the regulation of this signaling pathway that could represent an innovative and promising therapeutical target, also for ovarian cancer treatment.

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.

Quality of life of patients with bilateral oophorectomy before the age of 45 for the treatment of endometriosis

INTRODUCTION

The study aimed to evaluate the quality of life and associated factors among women who underwent bilateral oophorectomy (BO) before the age of 45 for the treatment of deep infiltrating endometriosis (DIE).

MATERIALS AND METHODS

This cross-sectional study was carried out in 52 women who were treated from January 2014 to December 2019 in 2 public and private DIE surgical centers in Toulouse. All women answered the Menopausal Quality of Life questionnaire (MenQOL). Mean MenQOL scores were compared according to age at BO, smoking, BMI, level of education, delay between BO and the survey and post-BO hormone replacement therapy (HRT) using Mann-Whitney and Anova tests. Spearman's correlation coefficient was used to analyze the correlations between all the MEnQOL domain scores and clinical variables. The variables associated with the outcomes in univariate analyses with p < 0.2 were jointly evaluated using multiple linear regression.

RESULTS

The mean age at the time of the survey was 43.4 ± 3.4 years while the mean age at BO was 40.5 ± 3.4 years. The mean MenQOL score was 3.96 (± 1.45), with the highest scores in the sexual (4.77) and vasomotor (4.01) domains. BMI and smoking were independently and significantly associated with the mean total MenQOL score, all domain scores being significantly higher in overweight/obese women. A trend towards worse MenQOL scores was found in patients who had BO before the age of 41. We did not find any difference according to whether or not they were taking HRT.

CONCLUSION

This is a first study evaluating quality of life in a specific population of oophorectomized women under the age of 45 using MenQOL for DIE. While BO is effective in relieving pain in women with severe DIE, the induced premature menopause is associated with a poor quality of life, which deserves further attention.

Body mass index and endometriosis: Is there a relationship?

Objective:

Previous studies on the relationship between the presence of endometriosis (EM) and body mass index (BMI) have shown inconsistent results. This study aimed to compare the BMI between women with EM and non-endometriotic controls.

Methods:

In the present cross-sectional study, BMI of 65 endometriotic women with 43 non-endometriotic controls undergoing laparoscopy were compared. The comparison of BMI between the two groups and in disease stages was analyzed using t-test.

Results:

BMI was significantly lower in women with EM compared to control women ( p = 0.01). There were no statistically significant differences in BMI between disease stages.

Conclusion:

The present study results showed that women with EM have lower BMI compared to non-endometriotic controls. More studies are suggested to clarify the mechanisms of this association.

Endometriosis-Associated Angiogenesis and Anti-angiogenic Therapy for Endometriosis

Endometriosis is a known estrogen-dependent inflammatory disease affecting reproductive-aged women. Common symptoms include pelvic pain, dysmenorrhea, dyspareunia, heavy menstrual bleeding, and infertility. The exact etiology of endometriosis is largely unknown, and, thus, the diagnosis and treatment of endometriosis are challenging. A complex interplay of many molecular mechanisms is thought to aid in the progression of endometriosis, most notably angiogenesis. This mini-review examines our current knowledge of the molecular etiology of endometriosis-associated angiogenesis and discusses anti-angiogenic therapy, in the blockade of endometriosis-associated angiogenesis, as potential non-hormonal therapy for the treatment of endometriosis.

The Role of mTOR and eIF Signaling in Benign Endometrial Diseases

Adenomyosis, endometriosis, endometritis, and typical endometrial hyperplasia are common non-cancerous diseases of the endometrium that afflict many women with life-impacting consequences. The mammalian target of the rapamycin (mTOR) pathway interacts with estrogen signaling and is known to be dysregulated in endometrial cancer. Based on this knowledge, we attempt to investigate the role of mTOR signaling in benign endometrial diseases while focusing on how the interplay between mTOR and eukaryotic translation initiation factors (eIFs) affects their development. In fact, mTOR overactivity is apparent in adenomyosis, endometriosis, and typical endometrial hyperplasia, where it promotes endometrial cell proliferation and invasiveness. Recent data show aberrant expression of various components of the mTOR pathway in both eutopic and ectopic endometrium of patients with adenomyosis or endometriosis and in hyperplastic endometrium as well. Moreover, studies on endometritis show that derangement of mTOR signaling is linked to the establishment of endometrial dysfunction caused by chronic inflammation. This review shows that inhibition of the mTOR pathway has a promising therapeutic effect in benign endometrial conditions, concluding that mTOR signaling dysregulation plays a critical part in their pathogenesis.

Establishment of Adenomyosis Organoids as a Preclinical Model to Study Infertility

Adenomyosis is related to infertility and miscarriages, but so far there are no robust in vitro models that reproduce its pathological features to study the molecular mechanisms involved in this disease. Endometrial organoids are in vitro 3D models that recapitulate the native microenvironment and reproduce tissue characteristics that would allow the study of adenomyosis pathogenesis and related infertility disorders. In our study, human endometrial biopsies from adenomyosis (n = 6) and healthy women (n = 6) were recruited. Organoids were established and hormonally differentiated to recapitulate midsecretory and gestational endometrial phases. Physiological and pathological characteristics were evaluated by immunohistochemistry, immunofluorescence, qRT-PCR, and ELISA. Secretory and gestational organoids recapitulated in vivo glandular epithelial phenotype (pan-cytokeratin, Muc-1, PAS, Laminin, and Ki67) and secretory and gestational features (α-tubulin, SOX9, SPP1, PAEP, LIF, and 17βHSD2 expression and SPP1 secretion). Adenomyosis organoids showed higher expression of TGF-β2 and SMAD3 and increased gene expression of SPP1, PAEP, LIF, and 17βHSD2 compared with control organoids. Our results demonstrate that organoids derived from endometria of adenomyosis patients and differentiated to secretory and gestational phases recapitulate native endometrial-tissue-specific features and disease-specific traits. Adenomyosis-derived organoids are a promising in vitro preclinical model to study impaired implantation and pregnancy disorders in adenomyosis and enable personalized drug screening.

The protective effects of ritodrine against hypoxia/reoxygenation-induced injury in endometrial stromal cells

Endometriosis (EMS) is often observed in women of childbearing age and significantly impacts patients' quality of life. Ritodrine is a β2 receptor agonist applied for relaxing the uterine smooth muscle. Its inhibitory effects on inflammation have recently been noted. The present study explored the protective impact of Ritodrine on hypoxia/reoxygenation (H/R)- induced injury in endometrial stromal cells (ESCs). Human ESCs (HESCs) were treated with Ritodrine (0.1, 0.5 μM) for 24 h, followed by exposure to H/R for 6 h. Ritodrine ameliorated H/R-induced higher reactive oxygen species (ROS), declined glutathione (GSH) concentration and increased production of tumor necrosis factor-α (TNF-α), interleukin- 6 (IL-6), and monocyte chemotactic protein 1 (MCP-1) in HESCs. Furthermore, Ritodrine ameliorated the H/R-induced higher nuclear level of nuclear factor κ-B (NF-κB) p65 expression and increased luciferase activity of the NF-κB promoter. In addition, we show that Ritodrine mitigated H/R-induced higher estrogen receptor α (ER-α) expression in HESCs. Interestingly, overexpressing ER-α abolished the regulatory effects of Ritodrine on oxidative stress and the NF-κB pathway-mediated inflammation. Collectively, our data reveal that Ritodrine alleviated H/R-induced injury in ESCs by inhibiting the ER-α/NF-κB pathway.

The Effect of Mesenchymal Stromal Cells Derived From Endometriotic Lesions on Natural Killer Cell Function

Endometriosis is an inflammatory disease that presents with ectopic endometriotic lesions. Reduced immunosurveillance of these lesions has been proposed to be playing a role in the pathology of endometriosis. Mesenchymal stromal cells (MSC) are found in ectopic lesions and may decrease immunosurveillance. In the present study, we examined if MSC contribute to reduced immunosurveillance through their immunosuppressive effects on natural killer (NK) cells. Stromal cells from endometriotic ovarian cysts (ESC_cyst) and eutopic endometrium (ESC_endo) of women with endometriosis and their conditioned medium were used in co-cultures with allogeneic peripheral blood NK cells. Following culture, NK cells were examined phenotypically for their expression of activating, inhibitory, maturation, and adhesion receptors and co-receptors, as well as the degranulation (CD107a) marker and the immunostimulatory (interferon-γ) and immunosuppressive (transforming growth factor beta 1 and interleukin-10) cytokines. Moreover, NK cell cytotoxicity was examined using chromium 51 release killing assays. There were no differences between ESC_cyst and ESC_endo regarding their effects on NK cell cytotoxicity in both conditioned medium and direct co-culture experiments. Additionally, there were no differences between ESC_cyst and ESC_endo regarding their impact on NK cells’ phenotype and degranulation in both conditioned medium and direct co-culture experiments. Although there were no differences found for DNAX accessory molecule-1 (DNAM-1) and NKp44, we found that the expression of the NK cell ligand CD155 that binds DNAM-1 and proliferating cell nuclear antigen (PCNA) that binds NKp44 was significantly less on ESC_cyst than on ESC_endo. These findings were not supported by the results that the expression of the known and unknown ligands on ESC_cyst for DNAM-1 and NKp44 using chimeric proteins was not significantly different compared to ESC_endo. In conclusion, the results suggest that ectopic MSC may not contribute to reduced immunosurveillance in endometriosis through their inhibitory effects on NK cells. This suggests that NK cell inhibition in the pelvic cavity of women with endometriosis develops due to other factors.

Association of microbial dynamics with urinary estrogens and estrogen metabolites in patients with endometriosis

Endometriosis is an estrogen dependent gynecological disease associated with altered microbial phenotypes. The association among endogenous estrogen, estrogen metabolites, and microbial dynamics on disease pathogenesis has not been fully investigated. Here, we identified estrogen metabolites as well as microbial phenotypes in non-diseased patients (n = 9) and those with pathologically confirmed endometriosis (P-EOSIS, n = 20), on day of surgery (DOS) and ~1–3 weeks post-surgical intervention (PSI). Then, we examined the effects of surgical intervention with or without hormonal therapy (OCPs) on estrogen and microbial profiles of both study groups. For estrogen metabolism analysis, liquid chromatography/tandem mass spectrometry was used to quantify urinary estrogens. The microbiome data assessment was performed with Next generation sequencing to V4 region of 16S rRNA. Surgical intervention and hormonal therapy altered gastrointestinal (GI), urogenital (UG) microbiomes, urinary estrogen and estrogen metabolite levels in P-EOSIS. At DOS, 17β-estradiol was enhanced in P-EOSIS treated with OCPs. At PSI, 16-keto-17β-estradiol was increased in P-EOSIS not receiving OCPs while 2-hydroxyestradiol and 2-hydroxyestrone were decreased in P-EOSIS receiving OCPs. GI bacterial α-diversity was greater for controls and P-EOSIS that did not receive OCPs. P-EOSIS not utilizing OCPs exhibited a decrease in UG bacterial α-diversity and differences in dominant taxa, while P-EOSIS utilizing OCPs had an increase in UG bacterial α-diversity. P-EOSIS had a strong positive correlation between the GI/UG bacteria species and the concentrations of urinary estrogen and its metabolites. These results indicate an association between microbial dysbiosis and altered urinary estrogens in P-EOSIS, which may impact disease progression.

The role of gut and genital microbiota and the estrobolome in endometriosis, infertility and chronic pelvic pain

BACKGROUND

Endometriosis is a chronic, burdensome condition that is historically understudied. Consequently, there is a lack of understanding of the etiology of the disease and its associated symptoms, including infertility and chronic pelvic pain (CPP). Endometriosis development is influenced by estrogen metabolism and inflammation, which are modulated by several factors including the microbiome and the estrobolome (the collection of genes encoding estrogen-metabolizing enzymes in the gut microbiome). Therefore, there is increasing interest in understanding the role of microbiota in endometriosis etiology.

OBJECTIVE AND RATIONALE

To date, there is no cure for endometriosis and treatment options often are ineffective. This manuscript will review the potential relationship between the microbiome and endometriosis, infertility and CPP and highlight the available data on the microbiome in relation to endometriosis and its related symptoms. The overarching goal of this manuscript is to inform future microbiome research that will lead to a deeper understanding of the etiology of the disease and possible diagnostic modalities and treatments. The potential impact of the microbiome on estrogen regulation modulated by the estrobolome, as well as inflammation and other endometriosis-promoting mechanisms within the genital tract, will be reviewed. The methodological limitations of microbiome-related studies will be critically assessed to provide improved guidelines for future microbiome and clinical studies.

SEARCH METHODS

PubMed databases were searched using the following keywords: endometriosis AND microbiome, infertility AND microbiome, pelvic pain AND microbiome, IVF (in-vitro fertilization) AND microbiome, endometriosis AND infertility. Clinical and preclinical animal trials that were eligible for review, and related to microbiome and endometriosis, infertility or CPP were included. All available manuscripts were published in 2002-2021.

OUTCOMES

In total, 28 clinical and 6 animal studies were included in the review. In both human and animal studies, bacteria were enriched in endometriosis groups, although there was no clear consensus on specific microbiota compositions that were associated with endometriosis, and no studies included infertility or CPP with endometriosis. However, bacterial vaginosis-associated bacteria and Lactobacillus depletion in the cervicovaginal microbiome were associated with endometriosis and infertility in the majority (23/28) of studies. Interpretation of endometrial studies is limited owing to a variety of methodological factors, discussed in this review. In addition, metadata outlining antibiotic usage, age, race/ethnicity, menopausal status and timing of sample collection in relation to diagnosis of endometriosis was not consistently reported. Animal studies (6/6) support a bidirectional relationship between the gut microbiota and endometriosis onset and progression.

WIDER IMPLICATIONS

There is evidence that a dysbiotic gut or genital microbiota is associated with multiple gynecologic conditions, with mounting data supporting an association between the microbiome and endometriosis and infertility. These microbiomes likely play a role in the gut-brain axis, which further supports a putative association with the spectrum of symptoms associated with endometriosis, including infertility and CPP. Collectively, this review highlights the demand for more rigorous and transparent methodology and controls, consistency across the field, and inclusion of key demographic and clinical characteristics of disease and comparison participants. Rigorous study designs will allow for a better understanding of the potential role of the microbiome in endometriosis etiology and the relationship to other disorders of the female reproductive tract.

Effect of urolithins A and B on ectopic endometrial growth in a murine model of endometriosis

Endometriosis is an often painful disease in reproductive-aged women, in which endometrial-like tissue grows outside the uterine cavity. Since the limited current therapeutic alternatives fail in alleviating the symptoms and based on our previous research in in vitro models using the same compounds as the ones used in the present study, we aimed to evaluate the effects of urolithins A (UA) and B (UB) on the growth and survival of endometriotic-like lesions in a murine model of endometriosis. Female BALB/C mice were surgically induced with endometriosis and treated with 2.5 mg kg^-1 day^-1 intraperitoneal UA or UB. The mice were monitored daily and weighed and the estrous stage was determined. After 28 days of treatment, lesions were counted, measured, excised, and fixed. Both urolithins proved not to affect the estrous cycle or body weight of the mice. UA completely prevented endometriotic-like lesions, while UB diminished the implant volume (p < 0.05). Treatment also reduced epithelial and stromal cell proliferation within the implants (p < 0.001 and p < 0.01, respectively) and apoptosis was enhanced (p < 0.05 and p < 0.01, respectively). These results are promising and reveal that urolithins A and B, separately, have a beneficial effect on the overall endometriotic growth without affecting the body weight or estrous cycle.

Effects of Breastfeeding on Endometriosis-Related Pain: A Prospective Observational Study

Endometriosis is a gynecological estrogen-dependent disease whose commonest pain symptoms are dysmenorrhea, dyspareunia, and acyclic chronic pelvic pain (CPP). Hormonal changes occurring during breastfeeding seem to reduce pain and disease recurrence. The aim of this observational prospective study was to assess the effect of breastfeeding on pain and endometriotic lesions in patients with endometriosis and to evaluate a possible correlation between the duration of breastfeeding, postpartum amenorrhea, and pain. Out of 156 pregnant women with endometriosis enrolled, 123 who breastfed were included in the study and were monitored for 2 years after delivery; 96/123 exclusively breastfed for at least 1 month. Mode of delivery, type and duration of breastfeeding, intensity of pain symptoms, and lesion size before pregnancy and during the 24-month follow-up were analyzed. All patients experienced a significant reduction in dysmenorrhea proportional to the duration of breastfeeding. CPP was significantly reduced only in women who exclusively breastfed. No significant improvement in dyspareunia was observed. Ovarian endometriomas were significantly reduced. Therefore, breastfeeding, particularly if exclusive, may cause improvement in dysmenorrhea and CPP proportional to the duration of breastfeeding, as well as a reduction in the size of ovarian endometriomas.

Effects of Ethinyl Estradiol in Combined Oral Contraceptives on Cell Proliferation and Apoptosis in Ectopic Endometrial Tissue: A Randomized Controlled Study

Objective: Since endometriosis is an estrogen-dependent disease; therefore, combined oral contraceptives (COCs) may not be the best choice for the treatment of endometriosis. The objective of the present study was to investigate the effects of ethinyl estradiol (EE) and desogestrel (DSG) in COCs on cell proliferation and apoptosis in ectopic endometrial tissue as compared to DSG alone. Materials and methods: Forty-five women of reproductive age with at least one endometriotic cyst were recruited into this single-blind randomized controlled trial study and randomly divided equally into three groups. EE-DSG and DSG groups received EE (0.03 mg) and DSG (0.15 mg) or DSG alone daily for 28-35 days before surgery. The control group was prescribed nothing. Endometriotic cyst tissues were collected during ovarian cystectomy for immunohistochemistry. Results: Levels of Ki-67 positive cells in the ectopic endometrial tissue of the EE-DSG group were significantly higher than the DSG group (median [IQR]; 1.4[1.2] vs 0.6 [0.7], P <0.016). There were significantly more TUNEL-positive cells in the EE-DSG group compared to the DSG group (median [IQR]; 2.8[0.7] vs 1.8[1.4], P < 0.016, respectively). Moreover, the number of TUNEL-positive cells in the EE-DSG and DSG groups were significantly higher than the control (median [IQR]; 2.8[0.7] vs 0.2[0.2] and 1.8[1.4] vs 0.2[0.2], P <0.016). The levels of cells that positively stained for Bcl2 were not different among all groups. Conclusion: Progestin alone increased cell apoptosis in ectopic endometria. However, concurrent EE in COCs enhanced proliferation and promoted a greater apoptotic effect in ectopic endometria compared to progestin alone.

Effect of combined contraceptive pill on immune cell of ovarian endometriotic tissue

BACKGROUND

Dysregulation of immune response is associated with development of endometriosis. The study aim was to evaluate effect of combined oral contraceptive pills (COCs) consisting of ethinyl estradiol (EE) and desogestrel on the expression of macrophage, natural killer cells, and regulatory T cells of ovarian endometriotic cysts.

METHODS

Endometriotic cyst wall tissues were collected from women with endometriosis who were treated (n = 22) with COCs (one table per day of EE 0.03 mg and desogestrel 0.15 mg administered for 28 to 35 days before surgery) or untreated (n = 22). The tissues were collected from endometriotic cyst wall during laparoscopic or laparotomy ovarian cystectomy. Immunohistochemistry for anti-CD68, anti-CD56, and anti-forkhead-winged helix transcription factor (FoxP3), a marker for macrophages, natural killer cells, and regulatory T cells, respectively, were investigated.

RESULTS

The median (interquartile range [IQR]) number of anti-CD68 positive cells in the COC group was significantly lower than in the untreated group (12.7; 4.9-19.3) versus 45.7 (26.0-70.7), p < 0.001). Tissue infiltration of anti-CD56 positive cells in endometriotic cyst was significantly higher after the treatment when compared with tissue from untreated group (42.9, 27.4-68.9 versus 25.3 (14.1-37.3; p = 0.009). The number of regulatory T cells was also significantly increased in the COC group (6.3, 2.8-15.5) versus 0 (0-1.8; p < 0.001).

CONCLUSIONS

The effects of COC, containing EE 0.30 mg with desogestrel 0.15 mg, on the immune system was demonstrated by a significant decrease in the number of macrophages and an increase in natural killer and regulatory T cells.

Superficial peritoneal endometriotic lesions are histologically diverse and rarely demonstrate menstrual cycle synchronicity with matched eutopic endometrium

STUDY QUESTION

Do menstrual cycle-dependent changes occur in the histological appearance of superficial peritoneal endometriotic lesions, and are they equivalent to those observed in the eutopic endometrium?

SUMMARY ANSWER

Only a small subset of superficial peritoneal endometriotic lesions exhibits some histological features in phase with menstrual cycle-related changes observed in eutopic endometrium.

WHAT IS KNOWN ALREADY

Endometriotic lesions are frequently described as implants that follow menstrual cycle-related changes in morphology, as per the eutopic endometrium. This concept has been widely accepted despite the lack of conclusive published evidence.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study of 42 patients, from across the menstrual cycle, with surgically and histologically confirmed endometriosis. Patients were a subset selected from a larger endometriosis study being conducted at the Royal Women's Hospital, Melbourne since 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Histological features of epithelium, stroma and gland morphology were examined in haematoxylin and eosin stained sections of superficial peritoneal endometriotic lesions and matched eutopic endometrium (menstrual: n = 4, proliferative: n = 11, secretory: n = 17, hormone-treated: n = 10). At least two biopsies (average = 4, range = 2-8 biopsies) and a matched endometrial sample were analysed for each patient and results were presented per endometriotic gland profile (n = 1051). Data were analysed using mixed effects logistic regression to account for multiple patients and multiple endometriotic biopsies, each with multiple endometriotic gland profiles. This model also enabled analysis of endometriotic lesions versus eutopic endometrium.

MAIN RESULTS AND THE ROLE OF CHANCE

There was considerable inter- and intra-patient variability in the morphology of superficial peritoneal endometriotic lesions. Menstrual cycle-associated changes were only observed for some features in a subset of endometriotic gland profiles. The proportion of endometriotic gland profiles with epithelial mitoses significantly increased in the proliferative phase (18% of gland profiles) relative to the menstrual phase (0% of endometriotic gland profiles) (odds ratios (OR) 9.30; 95% confidence intervals (CI) = 3.71-23.32; P < 0.001). Fewer blood-filled gland lumens were observed in the secretory phase (45% of endometriotic gland profiles) compared to the menstrual phase (67% of endometriotic gland profiles) (OR, 0.30; 95% CI = 0.11-0.79; P = 0.015). The features of the eutopic endometrium analysed in this study did not reflect the results in matched endometriotic lesions (P > 0.05).

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

This study focused on features observed in sections of superficial peritoneal lesions and these may differ from features of deep infiltrating endometriosis or ovarian endometriomas. Cycle phases were limited to menstrual, proliferative and secretory phases to allow appropriate statistical modelling.

WIDER IMPLICATIONS OF THE FINDINGS

This study highlights heterogeneity in the histological characteristics of superficial peritoneal lesions. It challenges the assumption that lesion morphology consistently reflects menstrual cycle-associated changes.

STUDY FUNDING/COMPETING INTEREST(S)

Research reported in this publication was supported in part by National Health and Medical Research Council (NHMRC) project grants GNT1012245, GNT1105321 and GNT1026033 (P.A.W.R., J.E.G. and S.J.H.-C.). There are no competing interests.

Gut microbiota imbalance and its correlations with hormone and inflammatory factors in patients with stage 3/4 endometriosis

Endometriosis (EM) in reproductive females has an incidence of 6-10% and greatly affects female fertility, quality of life, and long-term health. The gut microbiota can affect the physiological and pathological processes of humans through various pathways, such as those involving the nervous and endocrine systems and immunity, and it plays important roles in endocrine and inflammatory diseases. Whether the gut microbiota plays a role in EM has gradually attracted researchers' attention. In the present study, fecal and blood samples were collected from 12 patients with stage 3/4 EM and 12 healthy controls. We performed 16S rRNA high-throughput sequencing to compare the gut microbiota between the EM and control groups. Serum levels of hormones and inflammatory cytokines were measured. We found that compared with the control group, the EM group had a lower α diversity of gut microbiota and a higher Firmicutes/Bacteroidetes ratio. The abundances of various taxa (such as Actinobacteria, Tenericutes, Blautia, Bifidobacterium, Dorea, and Streptococcus) were significantly different between the two groups. The taxon with the highest abundance in the EM group was Prevotella_7, and that in the control group was Coprococcus_2. The serum levels of E2 and IL-8 were significantly higher in the EM group than in the control group (E2: EM group 74.7 ± 22.5 pg/L vs CON group 47.9 ± 12.5 pg/L; IL-8: EM group 6.39 ± 1.59 pg/mL vs CON group 4.14 ± 0.73 pg/mL). Additionally, the gut microbiota of the EM group was enriched for the microbial function categories environmental information processing, endocrine system, and immune system. Correlations were detected between each of Blautia and Dorea abundance and estradiol level and between Subdoligranulum abundance and IL-8 level. This study elucidated the associations between the gut microbiota and both serum hormones and inflammatory factors in EM. However, the findings need to be verified in future studies.

S100A7 promotes the development of human endometriosis by activating NF-κB signaling pathway in endometrial stromal cells

Endometriosis (EM) is a chronic inflammatory disease affecting women aged between 23 and 42 years with a prevalence of 6%-10%. S100A7, a member of the S100 protein family, has been implicated in promoting inflammation. However, the role of S100A7 in EM and its underlying mechanism remain to be elucidated. S100A7 was silenced or overexpressed in primary endometrial stromal cells (ESCs). Cell proliferation was determined using a Cell Counting Kit-8. Cell cycle/apoptosis was monitored using a flow cytometer. Cell invasion was studied by a Transwell assay. Quantitative RT-PCR and Western blot analyses were used to evaluate gene expression. S100A7 and NF-κB expression is increased in both endometriotic tissue and ESCs from women with EM. The expression of S100A7 is correlated with the expression of NF-κB. S100A7 knockdown inhibits ESCs proliferation, cell cycle progression, cell invasion, and inflammation, but promotes cell apoptosis in an NF-κB dependent manner. In contrast, S100A7 overexpression demonstrated an inverse effect. S100A7 is increased in both endometriotic tissue and ESCs from women with EM. S100A7 overexpression contributes to EM through increasing ESCs proliferation, cell cycle progression, cell invasion, and inflammation, and inhibiting cell apoptosis in the NF-κB dependent manner. These findings highlight the importance of S100A7/NF-κB signaling in EM and provide new insights into therapeutic strategies for EM.

Endometriosis of the Canal of Nuck: A Systematic Review of the Literature

Endometriosis is a common benign gynecological condition defined as the presence of endometrial tissue in tissues outside the uterine cavity. Apart from the common sites of endometriosis, rare sites other have also been reported including the liver, the thoracic cavity, the muscles, nerves, and more rarely in a patent Nuck canal. We aim to evaluate the clinical presentation, diagnostic features, and management of the Nuck endometriosis. A meticulous search of three electronic databases was performed until May 2020 for articles reporting cases of Nuck endometriosis. A total of 36 patients from 20 studies were analyzed. Median age of patients was 36 years with 33 women being of reproductive age. A right-sided lesion was identified in 30 cases (83.3%), while all patients suffer from a groin mass with cyclic pain in a proportion of 22%. All the patients finally underwent surgery for investigation of the lesion and fixation of the defect. Five cases of malignancy were detected at final pathology. All of them were alive with a median reported overall survival of 37 months. Nuck endometriosis should be included in the differential diagnosis of female patients with groin swelling. An evaluation by a gynecologist is important when endometriosis is suspected.

Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis

Endometriosis is a chronic, inflammatory, hormone-dependent disease characterized by histological lesions produced by the presence of endometrial tissue outside the uterine cavity. Despite the fact that an estimated 176 million women are affected worldwide by this gynecological disorder, risk factors that cause endometriosis have not been properly defined and current treatments are not efficient. Although the interaction between diet and human health has been the focus of many studies, little information about the correlation of foods and their bioactive derivates with endometriosis is available. In this framework, Brassica crops have emerged as potential candidates for ameliorating the chronic inflammatory condition of endometriosis, due to their abundant content of health-promoting compounds such as glucosinolates and their hydrolysis products, isothiocyanates. Several inflammation-related signaling pathways have been included among the known targets of isothiocyanates, but those involving aquaporin water channels have an important role in endometriosis. Therefore, the aim of this review is to highlight the promising effects of the phytochemicals present in Brassica spp. as major candidates for inclusion in a dietary approach aiming to improve the inflammatory condition of women affected with endometriosis. This review points out the potential roles of glucosinolates and isothiocyanates from Brassicas as anti-inflammatory compounds, which might contribute to a reduction in endometriosis symptoms. In view of these promising results, further investigation of the effect of glucosinolates on chronic inflammatory diseases, either as diet coadjuvants or as therapeutic molecules, should be performed. In addition, we highlight the involvement of aquaporins in the maintenance of immune homeostasis. In brief, glucosinolates and the modulation of cellular water by aquaporins could shed light on new approaches to improve the quality of life for women with endometriosis.

Alteration of systemic and uterine endometrial immune populations in patients with endometriosis

PROBLEM

Endometriosis is defined as growth of endometrial tissue in ectopic locations; it is associated with infertility and chronic pain and affects ~12% of reproductive-aged women. Although inflammation is known to play a key role in endometriosis, knowledge related to immune phenotypes associated with this disease is lacking. This study aimed to characterize immune profiles in patients with endometriosis, to assess inflammatory mediators, to and determine if surgical and/or hormonal therapies restore immune homeostasis.

METHODS OF STUDY

Samples from nine controls and 20 histologically confirmed endometriosis patients were collected upon surgery and ~1-3 weeks post-surgical intervention. Subjects were either not utilizing hormonal suppression or were currently on monophasic hormonal therapy. Tolerant regulatory T cells (Tregs = natural [nTregs] +inducible [iTregs]) and inflammatory T helper 17 (Th17) cells were identified in peripheral blood via flow cytometry and within the eutopic/ectopic endometrial tissues via immunohistochemistry and real-time-qPCR. Cytokines were assessed via 10-plex-ELISA.

RESULTS

Patients with endometriosis not utilizing hormonal therapy exhibited lower iTregs (tolerant), greater Th17 (inflammatory), and a reduction in Treg/Th17 ratio (P < .05), indicative of systemic inflammation. Treg and Th17 localizations were enhanced within the ectopic endometrial implant, which promotes lesion development. Hormonal therapy decreased systemic and local inflammation (eutopic/ectopic endometrium) via decreased iTregs and Th17 cells in patients with endometriosis (P < .05). Thus, imbalance within immune populations correlated with increased inflammation in patients with endometriosis, which was mitigated by hormonal therapy.

CONCLUSIONS

Patients with endometriosis exhibited systemic and localized inflammation within ectopic and endometrial tissues. Hormonal therapy dampened inflammation caused by disease.

The Enigmatic Role of Serum & Glucocorticoid Inducible Kinase 1 in the Endometrium

The serum- and glucocorticoid-inducible kinase 1 (SGK1) is subject to genetic up-regulation by diverse stimulators including glucocorticoids, mineralocorticoids, dehydration, ischemia, radiation and hyperosmotic shock. To become active, the expressed kinase requires phosphorylation, which is accomplished by PI3K/PDK1 and mTOR dependent signaling. SGK1 enhances the expression/activity of various transport proteins including Na⁺/K⁺-ATPase as well as ion-, glucose-, and amino acid- carriers in the plasma membrane. SGK1 can further up-regulate diverse ion channels, such as Na⁺-, Ca²⁺-, K⁺- and Cl^– channels. SGK1 regulates expression/activity of a wide variety of transcription factors (such as FKHRL1/Foxo3a, β-catenin, NFκB and p53). SGK1 thus contributes to the regulation of transport, glycolysis, angiogenesis, cell survival, immune regulation, cell migration, tissue fibrosis and tissue calcification. In this review we summarized the current findings that SGK1 plays a crucial function in the regulation of endometrial function. Specifically, it plays a dual role in the regulation of endometrial receptivity necessary for implantation and, subsequently in pregnancy maintenance. Furthermore, fetal programming of blood pressure regulation requires maternal SGK1. Underlying mechanisms are, however, still ill-defined and there is a substantial need for additional information to fully understand the role of SGK1 in the orchestration of embryo implantation, embryo survival and fetal programming.

Alterations of CD4+T Cell Subsets in Blood and Peritoneal Fluid in Different Stages of Endometriosis

Background

Endometriosis is a chronic inflammatory disorder with known immune disturbances. The aim of this study was to compare the frequency of different CD4+ T cells [T helper (Th)1, Th2, Th17 and regulatory T cells (Tregs)] in peripheral blood (PB) and peritoneal fluid (PF) of patients that have early and advanced stages of endome- triosis with a control group.

Materials and Methods

In this case control study, PB and PF samples were collected from women aged 24-40 years who underwent laparoscopy procedures. The frequency of CD4+ T subsets were analysed by flow cytometry and com- pared between three study groups; early endometriosis (stage I, II), advanced endometriosis (stage III, IV) and control (no endometriosis). T cell numbers were compared between the PB and PF in each of the aforementioned groups.

Results

No statistically significant difference was found between the study groups regarding the numbers of Th1, Th2 and Th17 cells in PB. The PF of patients with advanced endometriosis had increased numbers of Th17 cells compared to the control group (P=0.003), with P values of 0.059 and 0.045 in both menstrual phases. Increased numbers of Th2 cells in PF from early compared to advanced stages of endometriosis were detected exclusively in the luteal phase (P=0.035). The control group had increased numbers of Treg and Th2 cells in the PF compared to PB (both, P value=0.046). However, in the early stages of endometriosis there were more Th2, Th17 and Treg cells in the PF compared to PB (P values: 0.005, 0.047 and 0.013, respectively), while the number of Th17 cells was higher in the PF compared with PB in the advanced stages of endometriosis (P= 0.013).

Conclusion

There were increased numbers of Th17 cells in the PF of patients with advanced stages of endometriosis, which could be related to the severity of this disease.

Pain in Endometriosis

Endometriosis is a chronic and debilitating condition affecting ∼10% of women. Endometriosis is characterized by infertility and chronic pelvic pain, yet treatment options remain limited. In many respects this is related to an underlying lack of knowledge of the etiology and mechanisms contributing to endometriosis-induced pain. Whilst many studies focus on retrograde menstruation, and the formation and development of lesions in the pathogenesis of endometriosis, the mechanisms underlying the associated pain remain poorly described. Here we review the recent clinical and experimental evidence of the mechanisms contributing to chronic pain in endometriosis. This includes the roles of inflammation, neurogenic inflammation, neuroangiogenesis, peripheral sensitization and central sensitization. As endometriosis patients are also known to have co-morbidities such as irritable bowel syndrome and overactive bladder syndrome, we highlight how common nerve pathways innervating the colon, bladder and female reproductive tract can contribute to co-morbidity via cross-organ sensitization.

Estradiol promotes EMT in endometriosis via MALAT1/miR200s sponge function

Endometriosis is an estrogen-dependent benign gynecological disease that shares some common features of malignancy. Epithelial-mesenchymal transition (EMT) has been recognized as a core mechanism of endometriosis. MALAT1 is widely known as EMT promoter, while miR200 family members (miR200s) are considered as EMT inhibitors. Previous studies have reported that MALAT1 upregulation and miR200s downregulation are observed in endometriosis. MiR200c has been regarded as the strongest member of miR200s to interact with MALAT1. However, whether MALAT1/miR200c regulates EMT remains largely unclear. In this study, the roles of miR200s and MALAT1 in ectopic endometrium were investigated. Additionally, the effects of E2 on EMT and MALAT1/miR200s were examined in both EECs and Ishikawa cells. Notably, E2 could upregulate MALAT1 and downregulate miR200s expression levels and induce EMT in EECs and Ishikawa cells. PHTPP, an ERβ antagonist, could reverse the effect of E2. Overexpression of miR200c and knockdown of MALAT1 significantly inhibited E2-mediated EMT, suggesting that both miR200c and MALAT1 are involved in the E2-induced EMT process in endometriosis. In addition, a reciprocal inhibition was found between miR200s and MALAT1. Therefore, the role of MALAT1/miR200c in EMT is influenced by the presence of estrogen during endometriosis development.

Putative adverse outcome pathways for female reproductive disorders to improve testing and regulation of chemicals

Modern living challenges female reproductive health. We are witnessing a rise in reproductive disorders and drop in birth rates across the world. The reasons for these manifestations are multifaceted and most likely include continuous exposure to an ever-increasing number of chemicals. The cause–effect relationships between chemical exposure and female reproductive disorders, however, have proven problematic to determine. This has made it difficult to assess the risks chemical exposures pose to a woman’s reproductive development and function. To address this challenge, this review uses the adverse outcome pathway (AOP) concept to summarize current knowledge about how chemical exposure can affect female reproductive health. We have a special focus on effects on the ovaries, since they are essential for lifelong reproductive health in women, being the source of both oocytes and several reproductive hormones, including sex steroids. The AOP framework is widely accepted as a new tool for toxicological safety assessment that enables better use of mechanistic knowledge for regulatory purposes. AOPs equip assessors and regulators with a pragmatic network of linear cause–effect relationships, enabling the use of a wider range of test method data in chemical risk assessment and regulation. Based on current knowledge, we propose ten putative AOPs relevant for female reproductive disorders that can be further elaborated and potentially be included in the AOPwiki. This effort is an important step towards better safeguarding the reproductive health of all girls and women.

Exposure to Phthalate Esters and the Risk of Endometriosis

Endometriosis is a common gynecologic disease, worldwide, whose true prevalence is uncertain because it is a difficult disease to diagnose. Endometriosis is a common cause of chronic pelvic pain, dysmenorrhea, and infertility, and is also associated with ovarian cancer. Although the risk factors for endometriosis are unclear, there is increasing evidence that exposure to environmental contaminants, especially phthalates, could affect the pathogenesis of endometriosis. Phthalates are industrial chemicals, used to make flexible plastics, and are present in numerous common plastic products, including medical devices and materials. Several in vitro studies have suggested a positive association between exposure to phthalate, or phthalate metabolites, and the risk of endometriosis. Since the 2000s, studies based on human plasma and urinary concentrations of various phthalate metabolites have been published, but there are still limitations to our understanding of the pathophysiology of phthalates and endometriosis. This report aims to review the current state of knowledge about a possible role of phthalates in the pathogenesis of endometriosis based on cell culture, animal models, and human data.

Rapid Effects of Oestrogen on Intracellular Ca2+ in the Uterine Junctional Myometrium of Patients With and Without Adenomyosis in Different Phases of the Menstrual Cycle

We investigated the role of oestrogen receptor 1 (ESR1) in regulating the [Ca²⁺]i concentration in the junctional zone (JZ) and its effect on adenomyosis. JZ smooth muscle cells (JZSMCs) were isolated from 17 control and 24 adenomyotic uteri, and membrane proteins were extracted from the cells. In the control group, the levels of membrane ESR1 and [Ca²⁺]i in the proliferative phase were significantly greater than they were in the secretory phase. While no difference was detected between the two phases, ESR1 and [Ca²⁺]i levels in the adenomyosis group were significantly higher in the proliferative and secretory phases than they were in the control groups. Oestradiol induced a rapid increase in [Ca²⁺]i in the JZSMCs of both groups. When pretreated with the ESR1 antagonist ICI 182,780, the increase in [Ca²⁺]i was clearly reduced in both groups compared with the control, but the differences were not significant. Filtered E-6-BSA also induced [Ca²⁺]i, and its actions were similar to those of oestrogen. Removal of extracellular Ca²⁺ did not alter the effect of oestradiol, but the phospholipase C inhibitor U73122 (10 μM) and 2-aminoethoxydiphenyl borate (5 μM) significantly reduced the oestradiol-induced [Ca²⁺]i flux. Oestradiol was unable to induce a [Ca²⁺]i flux in thapsigargin-depleted cells; this result indicated that oestradiol mediates the [Ca²⁺]i flux in JZSMCs through ESR1, which activates the phospholipase C pathway. ESR1 levels were assessed by Western blotting. Changes in the [Ca²⁺]i concentration induced by oestrogen stimulation were analysed by immunofluorescence. The ΔFCa²⁺ was calculated as the difference between baseline and peak fluorescence response to stimulation. We found that the abnormal intracellular [Ca²⁺]i response to oestrogen could account for aberrant JZ peristalsis.

Polymorphisms in the 3'UTR Region of ESR2 and CYP19A1 Genes in Women With Endometriosis

OBJECTIVE

ESR2 and CYP19A1 genes play a major role in the hormonal control of women with endometriosis. The aim of the study was to analyze single nucleotide polymorphisms (SNPs) in the 3'UTR region of ESR2 and CYP19A1 genes. The study aimed at localisation of new polymorphisms, the nucleotide variants of which determine the level of susceptibility to endometriosis.

STUDY DESIGN

The study included n = 200 patients: 100 with endometriosis and 100 healthy controls. The Sanger's sequencing method was applied for polymorphism analysis.

RESULTS

Statistically significant correlations were identified between new, not previously described, two SNPs of ESR2 gene and endometriosis: rs4986938 (G>A) and rs928554 (A>G). In the case of rs4986938 polymorphism, the genotype AA was found to decrease the risk of endometriosis (OR = 0.24 95 % PU 0.05-1.22, p = 0.04). Analysis of the rs928554 polymorphism revealed that the occurrence of the AG genotype reduced the risk of endometriosis (OR = 0.38 95 % PU 0.21-0.71, p = 0.002). There were no differences in the distribution of genotypes of the polymorphisms rs10046 (C>T) and rs4646 (C>A) of CYP19A1 gene between patients and control.

CONCLUSIONS

Further studies are necessary in groups with higher numbers of patients to explain whether the above-mentioned polymorphisms may be the risk factors for endometriosis.

Association between the microbiota and women's cancers - Cause or consequences?

Breast, ovarian and uterine cancers are the most common neoplasms among women. Several mechanisms may be involved in oncogenesis and these include environmental and genetic factors. Bacteria may affect the development of some cancers, with bacterial components, their products and metabolites interacting with susceptible tissues. Commensalism and dysbiosis are important potential mechanisms involved in oncogenesis, and an effective strategy for diagnosis and treatment is required. The purpose of this review was to analyze the complex associations between these cancers in women, and the microbiota, specifically bacterial microbes. However, several cancers have an increased prevalence among individuals with HIV and HPV so the relationship between viral infections and malignancies in women is also referred to. We described how different phylum of bacteria, particularly in the gut, mammary tissue and vaginal microbiome may be involved in carcinogenesis; and we discuss the potential pathways involved: (I), that lead to cell proliferation, (II), immune system perturbation, (III), cell metabolic changes (e.g., hormonal factors), and (IV), DNA damage. Studies investigating the differences between the composition of the bacterial microbiota of healthy women compared to that present in various conditions, and the clinical trials are summarized for the few studies that have addressed the microbiota and related conditions, are also reviewed.

The prevalence of endometrioma and associated malignant transformation in women over 40 years of age

OBJECTIVE

Endometriosis is an estrogen-dependent chronic disease, which is regarded as a disease of reproductive-aged women. Endometriosis is most frequently diagnosed during reproductive period. We aimed to determine the frequency of endometrioma in women over 40 years of age who were operated for adnexial mass.

MATERIALS AND METHODS

A total of 1100 women over 40 years of age underwent surgery for adnexal mass were included in this cohort study between 2006 and 2016. Women who met the criteria were compared regarding the type of adnexial mass, age groups, menopausal status and malignant transformation.

RESULTS

A total of 299 women (27.2 %) with benign ovarian mass were determined to have endometrioma. Women with endometrioma were younger and nulliparous more frequently comparing women without endometrioma. Although 20 % of the patients in the endometrioma group were postmenopausal, 70 % of the patients in the control group were postmenopausal. Endometrioma-associated ovarian tumors were developed in nearly 11 % of women with endometrioma.

CONCLUSIONS

Even though endometriosis is accepted as a disease of reproductive-aged women, it can occur over 40 years of age. Detailed anamnesis and careful gynecological examination provide key information for differential diagnosis. Accurate information about the risk of malignant transformation should be informed.

Comparative immunohistochemical study of deep infiltrating endometriosis, lymph node endometriosis and atypical ovarian endometriosis including description of a perineural invasion

AIM

Endometriosis is an inflammatory condition that shares a number of similarities with malignant diseases, such as an abnormal morphology, migration along the nerve bundles and metastatic spread to lymph nodes and distant organs. Endometriotic lesions are associated with oestrogen and progesterone imbalance which seems to play a key role in the pathogenesis of endometriosis. The aim of this study was to compare the status of both oestrogen and progesterone receptors in tissue of deep infiltrating endometriosis, lymph node endometriosis and atypical ovarian endometriosis using immunohistochemical methods, as well as to investigate the relationship between endometriosis and protein p53.

METHODS

A total of 40 cases with deep infiltrating endometriosis were included in our study. Based on histopathological analysis of resected specimens, the cases were divided into 2 groups: group 1 - lymph node endometriosis (cases with lymph node involvement; n=12) and group 2 - deep infiltrating endometriosis (cases without lymph node involvement; n=28). As a control group, eutopic endometrium of adenomyosis- and endometriosis-free women were used (n=16). Five cases of atypical ovarian endometriosis as well as descriptions of the nerve involvement in endometriosis were also included. Immunohistochemical staining with a total of 4 markers was performed - oestrogen and progesterone receptors (ER, PR), p53 and Ki-67 (proliferation index).

RESULTS

The immunophenotype of the cases in groups 1 and 2 and in the control group was virtually identical in the proliferative phase - strong nuclear ER and PR expression in more than 90% of endometrial glandular and stromal cells. In the early and mid secretory phase, ER expression only slightly decreased (80%) in endometrial glandular cells in group 2 and the control group, whereas in the late secretory phase, significant decrease of ER expression only in the control group was observed (15-50%; P<0.001). In group 2 and the control group, significant decrease of PR expression only in endometrial glandular cells was observed in the mid and late secretory phase (less than 15%; P<0.001). Differences in receptor content were found only in isolated cases in group 2. In group 1, no secretory changes were found. In all three groups, sporadic and weak nuclear p53 expression in less than 3% in both endometrial glandular and stromal cells was detected (regardless of the phase of the menstrual cycle). In atypical ovarian endometriosis, higher and strong p53 expression (on average 26%) and decrease in ER (on average 56%) and PR (less than 1%) expression was observed; compared to the control group and groups 1 and 2, the differences for all 3 markers were highly significant (P<0.001). In all groups, the proliferation index (Ki-67) reached the highest values in the proliferation phase and decreased during the cycle. However, in endometriotic tissue, it was widely variable in the individual phases of the cycle. Perineural spread of endometriosis with significant neural hypertrophy, hyperplasia and involvement of the ganglia of the autonomic nervous system was detected in 5 cases (12.5%). Conlusion. From a histological and immunohistochemical point of view, deep infiltrating endometriosis and lymph node endometriosis appear to represent the same entity. For the first time, a simple immunohistochemical panel with antibodies against ER, PR and p53 useful in diagnosing atypical endometriosis has been described. The marked endometriosis-associated neural changes (endometriotic neuropathy) could be one of the causes of impaired function of the affected organs after debulking surgery with macroscopic negative resection margins as well as pain symptomatology in macroscopic inapparent endometriotic lesions.

Challenges in uncovering non-invasive biomarkers of endometriosis

Endometriosis affects up to 10% of women of childbearing age, causing symptoms that can include chronic pelvic pain and reduced fertility. The symptoms are not specific to the disease and can be confused with other gynecological conditions or normal menstruation. Currently, the disease can be only definitively diagnosed by laparoscopy, as no clinically accepted biomarker exists. Biomarker discovery can either follow a hypothesis-driven approach selecting targets to be tested based on current knowledge of the disease, or take an unbiased high-throughput screening “omics” approach, such as transcriptomics or proteomics, to identify markers that are unique or elevated in accessible bodily fluids of patients with the disease. Numerous studies have been conducted using these approaches to try and identify endometriosis biomarkers, but variabilities in study design, cohort selection, and analysis, together with the fact that most studies were small-scale, have made independent validation of biomarker candidates difficult. Therefore, efforts are underway to standardize cohort selection, patient data, and sample collection to allow better cross-study comparisons. Large scale multi-center studies using this standardized approach are necessary to validate existing endometriosis biomarker candidates and uncover potential new markers. Given the complexity and heterogeneity of the disease, it is likely that a panel of biomarkers will be necessary to diagnose and categorize endometriosis.

The effects of letrozole on women with endometriosis undergoing ovarian stimulation for in vitro fertilization

This study aimed to analyze the effects of a new protocol with letrozole on the outcomes of in vitro fertilization (IVF) cycles in women with endometriosis. This retrospective cohort study was conducted for women diagnosed with endometriosis undergoing IVF from an infertility clinic. A new protocol, combination therapy with letrozole and gonadotropin, was used from August 2016 to January 2018 ('protocol 1', n = 38). From March 2014 to July 2016, conventional IVF with gonadotropin was administered ('protocol 2', n = 26). Age and ovarian reserve were comparable between the two groups. The patients who received protocol 1 resulted in a significantly lower peak estradiol level in IVF compared with those received protocol 2 (722 ± 1076 pg/mL versus 2168 ± 1521 pg/mL, p < .001). The length of stimulation, the total dose of gonadotropin, number of oocytes retrieved, fertilization rates, and number of embryos obtained were similar between the two groups. The mean percentage of mature oocytes was lower (69.9 ± 23.7% versus 80.2 ± 21.0%, p = .029) in patients with protocol 1. While maintaining low estrogen levels, the combination therapy with letrozole and gonadotropin produce similar oocyte and embryo yield to the conventional IVF protocol in women with endometriosis.

Estrogen-regulated CD200 inhibits macrophage phagocytosis in endometriosis

OBJECTIVES

Endometriosis (EMS) is a benign disease that is related to estrogen, immune disorders and inflammation. The purpose of this research was to determine the expression of CD200 in EMS and to clarify its role in the pathogenesis of the disease.

METHODS

The levels of serum CD200 in patients with and without EMS were determined by ELISA. Furthermore, the expression of CD200 in normal eutopic endometrium and ectopic endometrium was detected by immunohistochemistry and western blotting. The CD200 receptor (CD200R) in macrophages in peritoneal fluid (pMØ) obtained from controls and patients with EMS was examined by western blotting. CD200 expression in human endometrial stromal cells (HESCs) stimulated with 17β-estradiol (E₂) was measured by western blotting. Furthermore, macrophages were stimulated with different concentrations of CD200 and the effect on phagocytosis was analyzed.

RESULTS

The plasma CD200 levels of patients with EMS was significantly increased compared with controls (P = 0.0173, 95%CI [18.75, 159.6]). Compared with normal eutopic endometrium, the expression of CD200 was significantly increased in ectopic endometrial tissues. The CD200R expression in pMØ obtained from patients with EMS was increased compared with the controls (P = 0.0244). CD200 expression in HESCs stimulated with E₂ was up-regulated. As the levels of CD200 increased, macrophage phagocytosis in vitro gradually decreased.

CONCLUSIONS

CD200 is an estrogen-induced molecule that impairs macrophage phagocytosis and may contribute to the immune escape of ectopic lesions in EMS.

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.