The role of gene polymorphisms in endometriosis

WNT4 (rs7521902 and rs16826658) polymorphism and its association with endometriosis - A systematic review and meta-analysis

IMPORTANCE

This systematic review supports the involvement of the WNT4 gene in the pathophysiology of endometriosis.

OBJECTIVE

To conduct a systematic review and meta-analysis on WNT4 rs7521902 and rs16826658 polymorphism associated with endometriosis based on multi-ethnic case-control studies.

DATA SOURCES

Comprehensive searching was performed using Medline, Embase, and Google Scholar.

STUDY SELECTION AND SYNTHESIS

Keywords used for searching using Boolean operators are endometriosis, WNT4, and polymorphism. This review followed PRISMA guidelines, and meta-analysis was conducted in STATA18.

MAIN OUTCOMES

WNT4 polymorphisms identified in this review were rs7521902, rs16826658, rs2235529, rs3820282, and rs12037376.

RESULTS

A total of 250 studies were identified through databases; 10 were eligible for this review, and eight were included in the meta-analysis. Two WNT4 polymorphisms (rs7521902 and rs16826658) were analysed in the meta-analysis. A lower risk of odds in having endometriosis was apparent in the CC genotype of rs7521092 polymorphism with a pooled OR of 0.86 (0.76, 0.99). Most articles were high-quality case-control studies and were at low risk of bias.

CONCLUSION

This study highlighted the association of WNT4 polymorphisms (rs7521092) and endometriosis across Latin America, Europe, and Asian populations.

RELEVANCE

Following the completion of the Human Genome Project, many genetic aspects of endometriosis were revealed, including the discovery of single nucleotide polymorphisms (SNPs). However, due to a lack of replications and conflicting results between studies, the conclusion of the endometriosis genetic pathway needed to be completed. This finding of WNT4 showed that its association with endometriosis was valid even in varied ethnicities, indicating a general genetic aspect of disease across populations. Nevertheless, further studies are needed to confirm this finding, including functional biological and longitudinal studies.

Crimson clues: advancing endometriosis detection and management with novel blood biomarkers

Endometriosis is an inflammatory condition affecting approximately 10% of the female-born population. Despite its prevalence, the lack of noninvasive biomarkers has contributed to an established global diagnostic delay. The intricate pathophysiology of this enigmatic disease may leave signatures in the blood, which, when detected, can be used as noninvasive biomarkers. This review provides an update on how investigators are utilizing the established disease pathways and innovative methodologies, including genome-wide association studies, next-generation sequencing, and machine learning, to unravel the clues left in the blood to develop blood biomarkers. Many blood biomarkers show promise in the discovery phase, but because of a lack of standardized and robust methodologies, they rarely progress to the development stages. However, we are now seeing biomarkers being validated with high diagnostic accuracy and improvements in standardization protocols, providing promise for the future of endometriosis blood biomarkers.

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.

Recent insights explaining susceptibility to endometriosis-From genetics to environment

Endometriosis is a disease with a heterogeneous pathogenesis, explained by multiple theories, and also with a polymorphic presentation. The purpose of this literature review is to systematize the genetic, inflammatory, and environmental factors related to the pathophysiology of endometriosis. Current evidence suggests that endometriosis is a complex inherited genetic condition, in which the genes that determine susceptibility to the disease interact with the environment to develop different phenotypes. Genetic variants associated with risk of endometriosis have been identified in several genome-wide association studies, in addition to a group of genes related to the pathophysiology of endometriosis, namely the estrogen, progesterone and androgen receptors and the cytochrome P450 gene, as well as the p53 gene. The role of inflammation is controversial; however, it is an essential process, both in the initiation and perpetuation of the disease, in and outside the pelvis. Alterations in reactive oxygen species pathways that consequently determine oxidative stress are typical in the inflammatory environment of endometriosis. The role of environmental factors is a relatively new and broad-spectrum topic, with inconsistent evidence. Multiple factors have been studied such as endocrine-disrupting chemicals, metals, intrauterine exposure to diethylstilbesterol and lifestyle risk factors. In conclusion, endometriosis remains a mysterious condition, with multifactorial factors involved in its pathophysiology. The progress that has been made in the genetic predisposition to endometriosis may allow the establishment of new therapeutic targets. On the other hand, understanding the role of the environment in this disease may allow preventive intervention, minimizing its incidence and/or severity. This article is categorized under: Reproductive System Diseases > Molecular and Cellular Physiology Reproductive System Diseases > Environmental Factors Reproductive System Diseases > Genetics/Genomics/Epigenetics.

Endometrial receptivity defects MUC-1 and COX-2 polymorphisms in endometriosis

The endometrium produces MUCIN-1 (MUC-1) and cyclooxygenase-2 (COX-2), which are essential for implantation. MUC-1 is required for adhesion, while COX-2 is necessary for decidualization. Variations or polymorphisms in MUC-1 and COX-2 can lead to changes in endometrial receptivity. This study investigated the relationship between MUC-1 and COX-2 polymorphisms and endometrial receptivity in endometriosis patients. Blood DNA samples were collected from 35 patients with endometriosis and 32 healthy patients between days 19 to 24 of their menstrual cycle (secretory phase). MUC-1 polymorphism was determined using the Amplification Refractory Mutation System (ARMS), and COX-2 gene polymorphism was assessed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The frequency distribution of gene polymorphisms between the two groups was compared using bivariate analysis. There were seven genotypic combinations of MUC-1 and COX-2: AAGC; AAGG; GACC; GAGC; GAGG; GGGC; GGGG. The AAGC genotype combination test was significant, with an OR=6.43 (95% CI:1.09-7.62) and p=0.01. In conclusion, combining MUC-1 and COX-2 (AAGC) genotypes results in endometrial receptivity defects in endometriosis.

A Common Genetic Factor Underlies Genetic Risk for Gynaecological and Reproductive Disorders and Is Correlated with Risk to Depression

INTRODUCTION

Sex steroid hormone fluctuations may underlie both reproductive disorders and sex differences in lifetime depression prevalence. Previous studies report high comorbidity among reproductive disorders and between reproductive disorders and depression. This study sought to assess the multivariate genetic architecture of reproductive disorders and their loading onto a common genetic factor and investigated whether this latent factor shares a common genetic architecture with female depression, including perinatal depression (PND).

METHOD

Using UK Biobank and FinnGen data, genome-wide association meta-analyses were conducted for nine reproductive disorders, and genetic correlation between disorders was estimated. Genomic Structural Equation Modelling identified a latent genetic factor underlying disorders, accounting for their significant genetic correlations. SNPs significantly associated with both latent factor and depression were identified.

RESULTS

Excellent model fit existed between a latent factor underlying five reproductive disorders (χ2 (5) = 6.4; AIC = 26.4; CFI = 1.00; SRMR = 0.03) with high standardised loadings for menorrhagia (0.96, SE = 0.05); ovarian cysts (0.94, SE = 0.05); endometriosis (0.83, SE = 0.05); menopausal symptoms (0.77, SE = 0.10); and uterine fibroids (0.65, SE = 0.05). This latent factor was genetically correlated with PND (rG = 0.37, SE = 0.15, p = 1.4e-03), depression in females only (rG = 0.48, SE = 0.06, p = 7.2e-11), and depression in both males and females (MD) (rG = 0.35, SE = 0.03, p = 1.8e-30), with its top locus associated with FSHB/ARL14EP (rs11031006; p = 9.1e-33). SNPs intronic to ESR1, significantly associated with the latent factor, were also associated with PND, female depression, and MD.

CONCLUSION

A common genetic factor, correlated with depression, underlies risk of reproductive disorders, with implications for aetiology and treatment. Genetic variation in ESR1 is associated with reproductive disorders and depression, highlighting the importance of oestrogen signalling for both reproductive and mental health.

The presence of clear cell glands around the ovarian endometrioid cyst has an association with clear cell carcinoma

We found some clear cell glands appeared in the endometrioid cysts (ECs) of the ovary (EC-CCG). To explore the clinicopathological features, molecular biological changes, and prognosis in EC-CCG and analyze the association with ovarian clear cell borderline tumors (CCBT) and clear cell carcinoma (CCC). We retrospectively examined 35 cases of EC-CCG, compared them to 13 cases of clear cell cystadenomas, 14 cases of CCBT, and 49 cases of CCC. We analyzed the differences in clinicopathological features and prognosis between the four groups. Data on clinicopathology and survival were gathered. Immunohistochemistry (IHC) was performed in all cases, and we analyzed the molecular changes of 2 cases of EC-CCG and 1 case of CCC by whole-exome sequencing (WES). EC-CCG shared some common clinicopathological features with CCBT: they occurred before menopause, had an elevated serum CA125 level in some cases, had an ovarian cystic mass on B-ultrasound, and had a risk of recurrence. Microscopically, both diseases were based on typical EC, and clear cell glands in the EC cyst wall were seen in varying numbers. Some cases of EC-CCG had IHC results similar to those of CCBT and CCC, with positive expression of HNF1β and NapsinA; decreased expression of ER, PR, and ARID1A; and increased expression of Ki67 (> 5%). WES results revealed that EC-CCG had mutations in TP53BP1, ZNF462, FN1, and FTL (which was also mutated in CCC). In summary, we found that clear cell glands appearing around EC in the ovary have an association with CCC.

Role of macrophages in the immunopathogenesis of adenomyosis

The aim of the research: to study pathophysiological mechanisms of adenomyosis development by determining the role of macrophages in the uterine microenvironment. Materials and methods: a prospective study has been conducted on 35 women. There were 20 (57.1 %) who had adenomyosis of I degree. The control group consisted of 15 (34.3 %) gynecologically healthy women. The patients underwent general clinical, instrumental (ultrasound, hysteroscopy) examinations. Fragments of the uterine wall obtained by hysterorectoscopy were used for morphological study. The method of immunohistochemical determination of CD68+ and CD163+ macrophages was used to analyze the characteristics of phenotypic equivalents of M1 and M2 macrophages in uterine tissue samples. Results: The increase in the number of macrophages in the myometrium of patients with adenomyosis revealed in this study, which is found in large numbers in the areas of infiltration of the stroma of myometrial cells in close association with the perivascular region, can be regarded as the basis of the mechanism for the formation of endometrioid heterotopia. Furthermore, distortion of the CD68/CD163 ratio of macrophages is characterized by proinflammatory shift. Conclusions: The study's main result is an increase in the quantitative indicators of CD68+ macrophages associated with adenomyosis, which indicates an immunopathological process in adenomyosis.

A GWAS in Idiopathic/Unexplained Infertile Men Detects a Genomic Region Determining Follicle-Stimulating Hormone Levels

CONTEXT

Approximately 70% of infertile men are diagnosed with idiopathic (abnormal semen parameters) or unexplained (normozoospermia) infertility, with the common feature of lacking etiologic factors. Follicle-stimulating hormone (FSH) is essential for initiation and maintenance of spermatogenesis. Certain single-nucleotide variations (SNVs; formerly single-nucleotide polymorphisms [SNPs]) (ie, FSHB c.-211G > T, FSHR c.2039A > G) are associated with FSH, testicular volume, and spermatogenesis. It is unknown to what extent other variants are associated with FSH levels and therewith resemble causative factors for infertility.

OBJECTIVE

We aimed to identify further genetic determinants modulating FSH levels in a cohort of men presenting with idiopathic or unexplained infertility.

METHODS

We retrospectively (2010-2018) selected 1900 men with idiopathic/unexplained infertility. In the discovery study (n = 760), a genome-wide association study (GWAS) was performed (Infinium PsychArrays) in association with FSH values (Illumina GenomeStudio, v2.0). Minor allele frequencies (MAFs) were analyzed for the discovery and an independent normozoospermic cohort. In the validation study (n = 1140), TaqMan SNV polymerase chain reaction was conducted for rs11031005 and rs10835638 in association with andrological parameters.

RESULTS

Imputation revealed 9 SNVs in high linkage disequilibrium, with genome-wide significance (P < 4.28e-07) at the FSHB locus 11p.14.1 being associated with FSH. The 9 SNVs accounted for up to a 4.65% variance in FSH level. In the oligozoospermic subgroup, this was increased up to 6.95% and the MAF was enhanced compared to an independent cohort of normozoospermic men. By validation, a significant association for rs11031005/rs10835638 with FSH (P = 4.71e-06/5.55e-07) and FSH/luteinizing hormone ratio (P = 2.08e-12/6.4e-12) was evident.

CONCLUSIONS

This GWAS delineates the polymorphic FSHB genomic region as the main determinant of FSH levels in men with unexplained or idiopathic infertility. Given the essential role of FSH, molecular detection of one of the identified SNVs that causes lowered FSH and therewith decreases spermatogenesis could resolve the idiopathic/unexplained origin by this etiologic factor.

Molecular Mechanisms Underlying the Association between Endometriosis and Ectopic Pregnancy

Endometriosis is a common inflammatory disease characterized by the presence of endometrial cells outside the uterine cavity. It is estimated that it affects 10% of women of reproductive age. Its pathogenesis covers a wide range of abnormalities, including adhesion, proliferation, and cell signaling disturbances. It is associated with a significant deterioration in quality of life as a result of chronic pelvic pain and may also lead to infertility. One of the most serious complications of endometriosis is an ectopic pregnancy (EP). Currently, the exact mechanism explaining this phenomenon is unknown; therefore, there are no effective methods of prevention. It is assumed that the pathogenesis of EP is influenced by abnormalities in the contraction of the fallopian tube muscles, the mobility of the cilia, and in the fallopian microenvironment. Endometriosis can disrupt function on all three levels and thus contribute to the implantation of the embryo beyond the physiological site. This review takes into account aspects of the molecular mechanisms involved in the pathophysiology of endometriosis and EP, with particular emphasis on the similarities between them.

Immunopathogenesis of endometriosis - a novel look at an old problem

This review aims to cast a look at endometriosis as a chronic and progressive gynecological disease.Endometriosis-affected tissues show a variety of pathologic features: alterations in cell growth, apoptosis, activation, angiogenesis, cell adhesion, and cytokine production. Fresh endometriotic lesions are associated with induction of an inflammatory reaction represented by overproduction of prostaglandins (PGE2), metalloproteinases (MMP-2, -3, -9), cytokines (IL-1β, IL-8, IFN-γ, TNF-α, MCP-1 and MIF) and adhesive molecules (ICAM-1, VCAM-1) and activation of synthesis of reactive oxygen and nitrogen species. The inflammatory process may lead to defective folliculogenesis by an altered follicular milieu. An increase in the number and change in function of macrophages, T- and B-lymphocytes and reduction of NK cells have been reported. Treg lymphocytes are known to play an extremely important role in controlling and modulating changes in the aberrant immune response in endometriosis. Dysregulation of the immune system results in both increased progression of endometriosis and its severity. In inflammatory conditions the immune cells provide immune defense at the local level - in peritoneal fluid - and could further cause: 1) a decrease of the number of NK CD16+ cells with expression of KIRs and an increase of NK CD57+; 2) increased numbers of CD8+ cells and CD11b- immature dendritic cells; 3) an increase of FoxP3 expression in the regulatory T cell (Treg) population; 4) an increase of macrophages activating T- and B-lymphocytes leading to elevated synthesis of cytokines and/or autoantibodies. We may conclude that endometriosis resembles an immunodependent disease with the autoimmune background and breakdown of immunosuppressive mechanisms. Further immunological investigations may open a new avenue to discover innovative immunomodulatory treatments of endometriosis.

Sex hormone-related polymorphisms in endometriosis and migraine: A narrative review

Some evidence indicates endometriosis and migraine have a common genetic predisposition in sex-hormone genes, which could have important implications for the treatment of these two heterogenous conditions. To date, the genes responsibility remains unknown. Based on the biological hypothesis that polymorphisms of genes involved in sex-hormone pathways may influence estrogen levels and phenotypes of both disorders, we did a literature search for candidate sex-hormone genes and genes involved in the metabolism of estradiol. The aim was to review the evidence for shared sex-hormone-related polymorphisms between endometriosis and migraine and provide an exhaustive overview of the current literature. We included case-control studies investigating associations between candidate sex-hormone-related genes and the disorders endometriosis and migraine, respectively. Results showed three overlapping sex-hormone-associated polymorphisms in estrogen receptor genes that are associated with both conditions. To confirm possible associations with other sex-hormone genes, larger studies are needed.

Hypoxia activates the unfolded protein response signaling network: An adaptive mechanism for endometriosis

Endometriosis (EMS) is a chronic gynecological disease that affects women of childbearing age. However, the exact cause remains unclear. The uterus is a highly vascularized organ that continuously exposes endometrial cells to high oxygen concentrations. According to the "planting theory" of EMS pathogenesis, when endometrial cells fall from the uterine cavity and retrograde to the peritoneal cavity, they will face severe hypoxic stress. Hypoxic stress remains a key issue even if successfully implanted into the ovaries or peritoneum. In recent years, increasing evidence has confirmed that hypoxia is closely related to the occurrence and development of EMS. Hypoxia-inducible factor-1α (HIF-1α) can play an essential role in the pathological process of EMS by regulating carbohydrate metabolism, angiogenesis, and energy conversion of ectopic endometrial cells. However, HIF-1α alone is insufficient to achieve the complete program of adaptive changes required for cell survival under hypoxic stress, while the unfolded protein response (UPR) responding to endoplasmic reticulum stress plays an essential supplementary role in promoting cell survival. The formation of a complex signal regulation network by hypoxia-driven UPR may be the cytoprotective adaptation mechanism of ectopic endometrial cells in unfavorable microenvironments.

Polygenic Risk Score Prediction for Endometriosis

Endometriosis is a major health care challenge because many young women with endometriosis go undetected for an extended period, which may lead to pain sensitization. Clinical tools to better identify candidates for laparoscopy-guided diagnosis are urgently needed. Since endometriosis has a strong genetic component, there is a growing interest in using genetics as part of the clinical risk assessment. The aim of this work was to investigate the discriminative ability of a polygenic risk score (PRS) for endometriosis using three different cohorts: surgically confirmed cases from the Western Danish endometriosis referral Center (249 cases, 348 controls), cases identified from the Danish Twin Registry (DTR) based on ICD-10 codes from the National Patient Registry (140 cases, 316 controls), and replication analysis in the UK Biobank (2,967 cases, 256,222 controls). Patients with adenomyosis from the DTR (25 cases) and from the UK Biobank (1,883 cases) were included for comparison. The PRS was derived from 14 genetic variants identified in a published genome-wide association study with more than 17,000 cases. The PRS was associated with endometriosis in surgically confirmed cases [odds ratio (OR) = 1.59, p = 2.57× 10⁻⁷] and in cases from the DTR biobank (OR = 1.50, p = 0.0001). Combining the two Danish cohorts, each standard deviation increase in PRS was associated with endometriosis (OR = 1.57, p = 2.5× 10⁻¹¹), as well as the major subtypes of endometriosis; ovarian (OR = 1.72, p = 6.7× 10⁻⁵), infiltrating (OR = 1.66, p = 2.7× 10⁻⁹), and peritoneal (OR = 1.51, p = 2.6 × 10⁻³). These findings were replicated in the UK Biobank with a much larger sample size (OR = 1.28, p < 2.2× 10⁻¹⁶). The PRS was not associated with adenomyosis, suggesting that adenomyosis is not driven by the same genetic risk variants as endometriosis. Our results suggest that a PRS captures an increased risk of all types of endometriosis rather than an increased risk for endometriosis in specific locations. Although the discriminative accuracy is not yet sufficient as a stand-alone clinical utility, our data demonstrate that genetics risk variants in form of a simple PRS may add significant new discriminatory value. We suggest that an endometriosis PRS in combination with classical clinical risk factors and symptoms could be an important step in developing an urgently needed endometriosis risk stratification tool.

The Role of Peritoneal Macrophages in Endometriosis

Endometriosis is an estrogen-dependent gynecological disorder, defined as the growth of endometrial stromal cells and glands at extrauterine sites. Endometriotic lesions are more frequently located into the abdominal cavity, although they can also be implanted in distant places. Among its etiological factors, the presence of immune dysregulation occupies a prominent place, pointing out the beneficial and harmful outcomes of macrophages in the pathogenesis of this disease. Macrophages are tissue-resident cells that connect innate and adaptive immunity, playing a key role in maintaining local homeostasis in healthy conditions and being critical in the development and sustainment of many inflammatory diseases. Macrophages accumulate in the peritoneal cavity of women with endometriosis, but their ability to clear migrated endometrial fragments seems to be inefficient. Hence, the characteristics of the peritoneal immune system in endometriosis must be further studied to facilitate the search for new diagnostic and therapeutic tools. In this review, we summarize recent relevant advances obtained in both mouse, as the main animal model used to study endometriosis, and human, focusing on peritoneal macrophages obtained from endometriotic patients and healthy donors, under the perspective of its future clinical translation to the role that these cells play on this pathology.

Genomics of Endometriosis: From Genome Wide Association Studies to Exome Sequencing

This review aims at better understanding the genetics of endometriosis. Endometriosis is a frequent feminine disease, affecting up to 10% of women, and characterized by pain and infertility. In the most accepted hypothesis, endometriosis is caused by the implantation of uterine tissue at ectopic abdominal places, originating from retrograde menses. Despite the obvious genetic complexity of the disease, analysis of sibs has allowed heritability estimation of endometriosis at ~50%. From 2010, large Genome Wide Association Studies (GWAS), aimed at identifying the genes and loci underlying this genetic determinism. Some of these loci were confirmed in other populations and replication studies, some new loci were also found through meta-analyses using pooled samples. For two loci on chromosomes 1 (near CCD42) and chromosome 9 (near CDKN2A), functional explanations of the SNP (Single Nucleotide Polymorphism) effects have been more thoroughly studied. While a handful of chromosome regions and genes have clearly been identified and statistically demonstrated as at-risk for the disease, only a small part of the heritability is explained (missing heritability). Some attempts of exome sequencing started to identify additional genes from families or populations, but are still scarce. The solution may reside inside a combined effort: increasing the size of the GWAS designs, better categorize the clinical forms of the disease before analyzing genome-wide polymorphisms, and generalizing exome sequencing ventures. We try here to provide a vision of what we have and what we should obtain to completely elucidate the genetics of this complex disease.

WNT4 Balances Development vs Disease in Gynecologic Tissues and Women's Health

The WNT family of proteins is crucial in numerous developmental pathways and tissue homeostasis. WNT4, in particular, is uniquely implicated in the development of the female phenotype in the fetus, and in the maintenance of müllerian and reproductive tissues. WNT4 dysfunction or dysregulation can drive sex-reversal syndromes, highlighting the key role of WNT4 in sex determination. WNT4 is also critical in gynecologic pathologies later in life, including several cancers, uterine fibroids, endometriosis, and infertility. The role of WNT4 in normal decidualization, implantation, and gestation is being increasingly appreciated, while aberrant activation of WNT4 signaling is being linked both to gynecologic and breast cancers. Notably, single-nucleotide polymorphisms (SNPs) at the WNT4 gene locus are strongly associated with these pathologies and may functionally link estrogen and estrogen receptor signaling to upregulation and activation of WNT4 signaling. Importantly, in each of these developmental and disease states, WNT4 gene expression and downstream WNT4 signaling are regulated and executed by myriad tissue-specific pathways. Here, we review the roles of WNT4 in women's health with a focus on sex development, and gynecologic and breast pathologies, and our understanding of how WNT4 signaling is controlled in these contexts. Defining WNT4 functions provides a unique opportunity to link sex-specific signaling pathways to women's health and disease.

Endometriosis and Cancer: Exploring the Role of Macrophages

Endometriosis and cancer have much in common, notably their burgeoning of cells in hypoxic milieus, their invasiveness, and their capacity to trigger remodeling, vascularization, and innervation of other tissues. An important role in these processes is played by permissive microenvironments inhabited by a variety of stromal and immune cells, including macrophages. Remarkable phenotypical plasticity of macrophages makes them a promising therapeutic target; some key issues are the range of macrophage phenotypes characteristic of a particular pathology and the possible manners of its modulation. In both endometriosis and cancer, macrophages guard the lesions from immune surveillance while promoting pathological cell growth, invasion, and metastasis. This review article focuses on a comparative analysis of macrophage behaviors in endometriosis and cancer. We also highlight recent reports on the experimental modulation of macrophage phenotypes in preclinical models of endometriosis and cancer.

Single nucleus multi-omics regulatory landscape of the murine pituitary

To provide a multi-omics resource and investigate transcriptional regulatory mechanisms, we profile the transcriptome, chromatin accessibility, and methylation status of over 70,000 single nuclei (sn) from adult mouse pituitaries. Paired snRNAseq and snATACseq datasets from individual animals highlight a continuum between developmental epigenetically-encoded cell types and transcriptionally-determined transient cell states. Co-accessibility analysis-based identification of a putative Fshb cis-regulatory domain that overlaps the fertility-linked rs11031006 human polymorphism, followed by experimental validation illustrate the use of this resource for hypothesis generation. We also identify transcriptional and chromatin accessibility programs distinguishing each major cell type. Regulons, which are co-regulated gene sets sharing binding sites for a common transcription factor driver, recapitulate cell type clustering. We identify both cell type-specific and sex-specific regulons that are highly correlated with promoter accessibility, but not with methylation state, supporting the centrality of chromatin accessibility in shaping cell-defining transcriptional programs. The sn multi-omics atlas is accessible at snpituitaryatlas.princeton.edu.

Prevalence of Common Gynecological Conditions in the Middle East: Systematic Review and Meta-Analysis

Introduction: High prevalence of gynecological conditions in women of Middle Eastern origin is reported, likely due to regional risk factors and mediators. The objective of this systematic review and meta-analysis is to investigate the prevalence of polycystic ovary syndrome (PCOS), endometriosis, uterine fibroids, and adenomyosis in women of Middle Eastern origin. Methods: MEDLINE, EMBASE, PsycINFO, Global Health, and Google Scholar databases were searched from database inception until 14 February 2021 to identify relevant studies. Peer-reviewed research articles that reported the prevalence of PCOS, endometriosis, uterine fibroids, and adenomyosis in the Middle Eastern population were written in English or Arabic. The primary outcome was the estimated pooled prevalence of PCOS, endometriosis, uterine fibroids, and adenomyosis in the Middle Eastern populations. The secondary outcome was to assess the evidence in the data for the presence of heterogeneity, by conducting subtype-pooled analysis of prevalence estimates of the conditions. Total weighted prevalence was calculated via Freeman-Tukey arcsine transformation and heterogeneity through the I 2 statistic. Quality control was performed using GRADE criteria. Results: A total of 47 studies, 26 on PCOS, 12 on endometriosis, eight on uterine fibroids, and seven on adenomyosis, were included. The pooled prevalence of PCOS diagnosed according to the NIH criteria was 8.9% (95% CI: 6.5-11.7; prevalence range: 4.0-27.6%), with a higher prevalence from the Gulf Arab states (18.8%, 95% CI: 9.5-30.3; range: 12.1-27.6%). According to the Rotterdam criteria, the pooled prevalence of PCOS was 11.9% (95% CI: 7.1-17.7; range: 3.4-19.9%) with studies limited to the Persian and Levant regions. Endometriosis was diagnosed in 12.9% (95% CI: 4.2-25.4; range: 4.2-21.0%) of women undergoing laparoscopy, for any indication. Uterine fibroid and adenomyosis prevalence of women was 30.6% (95% CI: 24.9-36.7; range: 18.5-42.6%) and 30.8% (95% CI: 27.1-34.6, range: 25.6-37.7%), respectively. Heterogeneity was present between studies due to statistical and methodological inconsistencies between studies, and quality of evidence was low due to sample size and unrepresentative participant selection. Conclusion: This is the first review that has reported the prevalence of gynecological diseases in the Middle Eastern population, suggesting that gynecological morbidity is a public health concern. Due to the health disparities in women, further research is required to understand the relative roles of environmental and genetic factors in the region to serve as a benchmark for evaluation and comparative purposes with other populations.

Deciphering biomarkers of endometriosis by proteomic analysis of eutopic endometrium in infertile patients

AIM

Endometriosis is associated with infertility. The aim of this study was to examine the overall proteomic changes of eutopic endometrium in infertile women with endometriosis.

METHODS

Tandem mass tags combined with multidimensional liquid chromatography and mass spectrometry analyses were used to screen the proteomic profiles of eutopic endometrium from infertile patients with endometriosis (N = 4), compared with that from patients without endometriosis (N = 4). Quantitative proteomic analysis, functional categories and significant pathway analysis were investigated subsequently.

RESULTS

In total, 6.698 proteins were identified, among which 5,812 proteins were quantified. Compared with controls, proteomic analysis showed some differentially expressed proteins: 16 up-regulated proteins and 23 down-regulated proteins. Bioinformatics analysis indicated that differentially expressed proteins were involved in humoral immune response pathways, antimicrobial humoral response and regulation of nitric oxide biosynthetic process. Besides, our results showed that alpha-1-acid glycoprotein 2, complement factor B and zinc transporter Zip14 were important resources for investigating potential mechanism of infertility in infertile women with endometriosis.

CONCLUSIONS

This study provided a reference proteome map of eutopic endometrium from infertile women with endometriosis. The long-term benefits of using those markers to stratify clinical treatment warrant further investigation.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

Systematic review of genome-wide association studies on susceptibility to endometriosis

Endometriosis is a complex and heterogeneous disease in which extrinsic and intrinsic factors, such as genetics, provide to the disease development. Genome-wide association (GWA) studies may be essential to recognize genetic variants associated with the endometriosis risk. However, in the current literature there are some conflicting results between these studies. The aim of the present study was to undertake a systematic review about endometriosis GWA studies, to describe the disease-associated genes and single nucleotide polymorphisms (SNPs) to try to understand the endometriosis etiopathogenesis, besides to discuss possible bias of conflicting results among these studies. This study is a systematic review of GWA studies in endometriosis published until December 31^th, 2019 by PubMed database, considering the following descriptors: endometriosis and ("polymorphism" or "SNP" or "genetic polymorphism" or "variants" or "locus") and ("GWA" or "Genome-wide" or "Genome wide" or "Genetic association study"). The included studies were analyzed with methodological rigor (STROBE and PRISMA) to enable better quality of case-control and meta-analysis studies, respectively. Of the 88 articles found, only 15 were eligible. All articles had appropriate quality evaluated by STROBE and PRISMA checklists (77% and 81%, respectively). Overall, 35,022 endometriosis cases and 181,760 controls were analyzed. The number of participants in each study was quite different (171 to 17,045 for the cases and 308 to 150,021 for the controls), with a predominance of European ethnicity. Most endometriosis cases (86%) were diagnosed by surgery, while selection of the control group was different among studies. About 47% performed only one stage (discovery stage) and 53% performed both the discovery and replication analyses. Eleven genes/SNPs were associated with endometriosis risk in more than one article (chromosome 1, 2, 6, 7, 9 and 12; WNT4, GREB1, FN1, IL1A, ETAA1, RND3, ID4, NFE2L3, CDKN2B-AS1 and VEZT). SNPs were localized in intergenic and intronic regions, their risk allele frequencies varied among the studies and their results were conflicting. In summary, WNT4 rs7521902, GREB1 rs13394619, FN1 rs1250248, IL1A rs6542095 and VEZT rs10859871 variants are highlighted due to high frequency and pathways and function that each gene influences in the development of endometriosis. However, the replication and validation of these variants in different populations are necessary for a better understanding of the endometriosis etiopathogenesis, in order to optimize the diagnosis and improve the efficiency of clinical treatment of the disease.

Endometriosis Associated Infertility: A Critical Review and Analysis on Etiopathogenesis and Therapeutic Approaches

Endometriosis represents a frequently diagnosed gynecological affliction in the reproductive timespan of women, defined by symptoms ranging from pelvic pain to infertility. A complex interplay between the genetic profile, hormonal activity, menstrual cyclicity, inflammation status, and immunological factors define the phenotypic presentation of endometriosis. To date, imaging techniques represent the gold standard in diagnosing endometriosis, of which transvaginal ultrasonography and magnetic resonance imaging bring the most value to the diagnostic step. Current medical treatment options for endometriosis-associated infertility focus on either stimulating the follicular development and ovulation or on inhibiting the growth and development of endometriotic lesions. Techniques of assisted reproduction consisting of superovulation with in vitro fertilization or intrauterine insemination represent effective treatment alternatives that improve fertility in patients suffering from endometriosis. Emerging therapies such as the usage of antioxidant molecules and stem cells still need future research to prove the therapeutic efficacy in this pathology.

Polymorphisms and endometriosis: a systematic review and meta-analyses

BACKGROUND

Endometriosis is an estrogen-dependent gynecological disorder that affects at least 10% of women of reproductive age. It may lead to infertility and non-specific symptoms such as chronic pelvic pain. Endometriosis screening and diagnosis are difficult and time-consuming. Late diagnosis (with a delay ranging from 3.3 to 10.7 years) is a major problem and may contribute to disease progression and a worse response to treatment once initiated. Efficient screening tests might reduce this diagnostic delay. As endometriosis is presumed to be a complex disease with several genetic and non-genetic pathogenic factors, many researchers have sought to identify polymorphisms that predispose to this condition.

OBJECTIVE AND RATIONALE

We performed a systematic review and meta-analysis of the most regularly reported polymorphisms in order to identify those that might predispose to endometriosis and might thus be of value in screening.

SEARCH METHODS

The MEDLINE database was searched for English-language publications on DNA polymorphisms in endometriosis, with no date restriction. The PubTator text mining tool was used to extract gene names from the selected publications' abstracts. We only selected polymorphisms reported by at least three studies, having applied strict inclusion and exclusion criteria to their control populations. No stratification based on ethnicity was performed. All steps were carried out according to PRISMA guidelines.

OUTCOMES

The initial selection of 395 publications cited 242 different genes. Sixty-two genes (corresponding to 265 different polymorphisms) were cited at least in three publications. After the application of our other selection criteria (an original case-control study of endometriosis, a reported association between endometriosis and at least one polymorphism, data on women of reproductive age and a diagnosis of endometriosis in the cases established by surgery and/or MRI and confirmed by histology), 28 polymorphisms were eligible for meta-analysis. Only five of the 28 polymorphisms were found to be significantly associated with endometriosis: interferon gamma (IFNG) (CA) repeat, glutathione S-transferase mu 1 (GSTM1) null genotype, glutathione S-transferase pi 1 (GSTP1) rs1695 and wingless-type MMTV integration site family member 4 (WNT4) rs16826658 and rs2235529. Six others showed a significant trend towards an association: progesterone receptor (PGR) PROGINS, interCellular adhesion molecule 1 (ICAM1) rs1799969, aryl-hydrocarbon receptor repressor (AHRR) rs2292596, cytochrome family 17 subfamily A polypeptide 1 (CYP17A1) rs743572, CYP2C19 rs4244285 and peroxisome proliferator-activated receptor gamma (PPARG) rs1801282), and 12 showed a significant trend towards the lack of an association: tumor necrosis factor (TNF) rs1799964, interleukin 6 (IL6) rs1800796, transforming growth factor beta 1 (TGFB1) rs1800469, estrogen receptor 1 (ESR1) rs2234693, PGR rs10895068, FSH receptor (FSHR) rs6166, ICAM1 rs5498, CYP1A1 rs4646903, CYP19A1 rs10046, tumor protein 53 (TP53) rs1042522, X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1) rs25487 and serpin peptidase inhibitor clade E member 1 (SERPINE1) rs1799889; however, for the 18 polymorphisms identified in the latter two groups, further studies of the potential association with the endometriosis risk are needed. The remaining five of the 28 polymorphisms were not associated with endometriosis: glutathione S-transferase theta 1 (GSTT1) null genotype, vascular endothelial growth factor alpha (VEGFA) rs699947, rs833061, rs2010963 and rs3025039.

WIDER IMPLICATIONS

By carefully taking account of how the control populations were defined, we identified polymorphisms that might be candidates for use in endometriosis screening and polymorphisms not associated with endometriosis. This might constitute the first step towards identifying polymorphism combinations that predispose to endometriosis (IFNG (CA) repeat, GSTM1 null genotype, GSTP1 rs1695, WNT4 rs16826658 and WNT4 rs2235529) in a large cohort of patients with well-defined inclusion criteria. In turn, these results might improve the diagnosis of endometriosis in primary care. Lastly, our present findings may enable a better understanding of endometriosis and improve the management of patients with this disease.

Association between mitochondrial DNA D-loop region polymorphisms and endometriosis in a Chinese population

OBJECTIVE

To investigate the correlation between endometriosis and mitochondrial DNA (mtDNA) D-loop single nucleotide polymorphisms (SNPs) and haplotype, as well as the predictive power of certain SNPs in reproductive outcomes in a Chinese Han population.

METHODS

A case-control study was conducted in which 125 endometriosis patients and 124 controls were recruited from an academic fertility center. The entire 1124-bp D-loop region of mtDNA of whole blood samples from all subjects was amplified, sequenced, and compared with the revised Cambridge Reference Sequence (rCRS) to identify SNPs and haplotypes. The association between D-loop SNPs and embryo quality and clinical outcome following in vitro fertilization (IVF) was also assessed.

RESULTS

A total of 321 polymorphisms were identified by sequencing, allowing comparison of the D-loop between endometriosis patients and controls. The frequency of the AC523-524 del, T16172C, and C16290T variants were significantly higher, while the frequency of polymorphisms T195C, 573XCins, 16036Gins, 16049Gins, T16140C, A16183C, T16189C, and 16193Cins were lower, in the endometriosis group compared with the control group (p < 0.05). Within the endometriosis group, the high-quality blastocyst rate in the 16,290T subgroup was significantly lower than that in the 16290C subgroup (p < 0.05). In the control group, 16519C carriers showed a lower rate of high-quality blastocyst development compared with 16519T (p < 0.05). In endometriosis patients clinical pregnancy rate was significantly lower in the 150T subgroup compared with the 150C subgroup (p < 0.05).

DISCUSSION

Data confirms a correlation between D-loop polymorphisms and endometriosis. The polymorphisms AC523-524 del, T16172C, and C16290T are associated with increased risk of endometriosis, while T195C, 573XCins, 16036Gins, 16049Gins, T16140C, A16183C, T16189C, and 16193Cins are associated with decreased risk of endometriosis. In addition, C16290T and T16519C can be associated with poor quality blastocyst development in population with and without endometriosis, respectively and C150T can be a predictor of poor IVF outcome.

The impact of vascular endothelial growth factor single nucleotide polymorphisms in the development and severity of endometriosis: A systematic review of the literature

OBJECTIVE

To review the impact of single nucleotide polymorphisms (SNPs) of the vascular endothelial growth factor (VEGF) gene in the development and severity of endometriosis.

SEARCH STRATEGY

We searched Medline, Scopus, Clinicaltrials.gov, EMBASE, Cochrane Central Register of Controlled Trials CENTRAL and Google Scholar databases for published studies in the field.

SELECTION CRITERIA

We included prospective and retrospective observational studies.

DATA COLLECTION AND ANALYSIS

Data extraction was performed using a modified data form that was based in Cochrane`s data collection form for intervention reviews.

MAIN RESULTS

Twenty studies were included that investigated the frequency of the various alleles of the -460C/T, +405G/C, +936C/T, -2578A/C and -1154G/A SNPs. The Hardy-Weinberg equilibrium revealed that the different genotypes were comparable among patients with endometriosis and control women, as well as among patients with mild and severe forms of the disease. No differences were observed in the expression of the various alleles in the majority of cases. Ethnical variations were observed; however, the results should be regarded as inconclusive due to the small amount of available data.

CONCLUSIONS

The results of our meta-analysis suggest that the investigated single nucleotide polymorphisms are unlikely to significantly contribute to the development and severity of endometriosis.

Genetic, Epigenetic, and Steroidogenic Modulation Mechanisms in Endometriosis

Endometriosis is a chronic gynecological disease, affecting up to 10% of reproductive-age women. The exact cause of the disease is unknown; however, it is a heritable condition affected by multiple genetic, epigenetic, and environmental factors. Previous studies reported variations in the epigenetic patterns of numerous genes known to be involved in the aberrant modulation of cell cycle steroidogenesis, abnormal hormonal, immune and inflammatory status in endometriosis, apoptosis, adhesion, angiogenesis, proliferation, immune and inflammatory processes, response to hypoxia, steroidogenic pathway and hormone signaling are involved in the pathogenesis of endometriosis. Accumulating evidence suggest that various epigenetic aberrations may contribute to the pathogenesis of endometriosis. Among them, DNA methyltransferases, histone deacetylators, and non-coding microRNAs demonstrate differential expression within endometriotic lesions and in the endometrium of patients with endometriosis. It has been indicated that the identification of epigenetic differences within the DNA or histone proteins may contribute to the discovery of a useful prognostic biomarker, which could aid in the future earlier detection, timely diagnosis, and initiation of a new approach to the treatment of endometriosis, as well as inform us about the effectiveness of treatment and the stage of the disease. As the etiology of endometriosis is highly complex and still far from being fully elucidated, the presented review focuses on different approaches to identify the genetic and epigenetic links of endometriosis and its pathogenesis.

TLR4 T399I Polymorphism and Endometriosis in a Cohort of Italian Women

Background: Endometriosis is a widespread multifactorial disease in which environmental, genetic, and epigenetic factors contribute to the phenotype. Single Nucleotide Polymorphisms (SNPs) in genes implicated in pivotal molecular mechanisms have been investigated as susceptible risk factors in distinct populations. Among these, Toll-like receptor 4 (TLR4) represents a good candidate due to its role in the immune/inflammatory response and endometriosis pathogenesis. Methods: The TRL4 gene T399I SNP (C/T transition, rs4986791) was investigated in 236 Italian endometriosis patients and 150 controls by using the PCR-RFLP method. One-tailed Fisher’s exact test was used to compare differences between categorical variables. T399I genotype distribution was evaluated for Hardy–Weinberg equilibrium in both groups using the Chi-squared test for given probabilities. Results: Fisher’s exact test comparing C and T allele frequencies showed a difference in the frequency of T alleles between patients and controls (OR = 1.96, 95% confidence interval 0.91–4.23; p-value = 0.0552). Genotype frequencies did not show any significant difference between patients and controls. The homozygous TT genotype was observed in 2% of endometriosis women and not in controls. Conclusions: Our results show that the TLR4 rs4986791 T variant may be considered a genetic risk factor for endometriosis in Italian women. More extensive studies in other populations are needed to confirm this result.

Genetic Characterization of Endometriosis Patients: Review of the Literature and a Prospective Cohort Study on a Mediterranean Population

The pathogenesis of endometriosis is unknown, but some evidence supports a genetic predisposition. The purpose of this study was to evaluate the recent literature on the genetic characterization of women affected by endometriosis and to evaluate the influence of polymorphisms of the wingless-type mammalian mouse tumour virus integration site family member 4 (WNT4), vezatin (VEZT), and follicle stimulating hormone beta polypeptide (FSHB) genes, already known to be involved in molecular mechanisms associated with the proliferation and development of endometriotic lesions in the Sardinian population. Materials and Methods: In order to provide a comprehensive and systematic tool for those approaching the genetics of endometriosis, the most cited review, observational, cohort and case-control studies that have evaluated the genetics of endometriosis in the last 20 years were collected. Moreover, 72 women were recruited for a molecular biology analysis of whole-blood samples—41 patients affected by symptomatic endometriosis and 31 controls. The molecular typing of three single nucleotide polymorphisms (SNPs) was evaluated in patients and controls: rs7521902, rs10859871 and rs11031006, mapped respectively in the WNT4, VEZT and FSHB genes. In this work, the frequency of alleles, genotypes and haplotypes of these SNPs in Sardinian women is described. Results: From the initial search, a total of 73 articles were chosen. An analysis of the literature showed that in endometriosis pathogenesis, the contribution of genetics has been well supported by many studies. The frequency of genotypes observed in the groups of the study population of 72 women was globally coherent with the law of the Hardy–Weinberg equilibrium. For the SNP rs11031006 (FSHB), the endometriosis group did not show an increase in genotypic or allelic frequency due to this polymorphism compared to the control group (p = 0.9999, odds ratio (OR) = 0.000, 95% confidence interval (CI), 0.000–15.000 and p = 0.731, OR = 1639, 95% CI, 0.39–683, respectively, for the heterozygous genotype and the polymorphic minor allele). For the SNP rs10859871 (VEZT), we found a significant difference in the frequency of the homozygous genotype in the control group compared to the affected women (p = 0.0111, OR = 0.0602, 95% CI, 0.005–0.501). For the SNP rs7521902 (WNT4), no increase in genotypic or allelic frequency between the two groups was shown (p = 0.3088, OR = 0.4133, 95% CI, 0.10–1.8 and p = 0.3297, OR = 2257, 95% CI, 0.55–914, respectively, for the heterozygous genotype and the polymorphic minor allele). Conclusion: An analysis of recent publications on the genetics of endometriosis showed a discrepancy in the results obtained in different populations. In the Sardinian population, the results obtained do not show a significant association between the investigated variants of the genes and a greater risk of developing endometriosis, although several other studies in the literature have shown the opposite. Anyway, the data underline the importance of evaluating genetic variants in different populations. In fact, in different ethnic groups, it is possible that specific risk alleles could act differently in the pathogenesis of the disease.

Tissue specific regulation of transcription in endometrium and association with disease

STUDY QUESTION

Are genetic effects on endometrial gene expression tissue specific and/or associated with reproductive traits and diseases?

SUMMARY ANSWER

Analyses of RNA-sequence data and individual genotype data from the endometrium identified novel and disease associated, genetic mechanisms regulating gene expression in the endometrium and showed evidence that these mechanisms are shared across biologically similar tissues.

WHAT IS KNOWN ALREADY

The endometrium is a complex tissue vital for female reproduction and is a hypothesized source of cells initiating endometriosis. Understanding genetic regulation specific to, and shared between, tissue types can aid the identification of genes involved in complex genetic diseases.

STUDY DESIGN, SIZE, DURATION

RNA-sequence and genotype data from 206 individuals was analysed and results were compared with large publicly available datasets.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA-sequencing and genotype data from 206 endometrial samples was used to identify the influence of genetic variants on gene expression, via expression quantitative trait loci (eQTL) analysis and to compare these endometrial eQTLs with those in other tissues. To investigate the association between endometrial gene expression regulation and reproductive traits and diseases, we conducted a tissue enrichment analysis, transcriptome-wide association study (TWAS) and summary data-based Mendelian randomisation (SMR) analyses. Transcriptomic data was used to test differential gene expression between women with and without endometriosis.

MAIN RESULTS AND THE ROLE OF CHANCE

A tissue enrichment analysis with endometriosis genome-wide association study summary statistics showed that genes surrounding endometriosis risk loci were significantly enriched in reproductive tissues. A total of 444 sentinel cis-eQTLs (P < 2.57 × 10-9) and 30 trans-eQTLs (P < 4.65 × 10-13) were detected, including 327 novel cis-eQTLs in endometrium. A large proportion (85%) of endometrial eQTLs are present in other tissues. Genetic effects on endometrial gene expression were highly correlated with the genetic effects on reproductive (e.g. uterus, ovary) and digestive tissues (e.g. salivary gland, stomach), supporting a shared genetic regulation of gene expression in biologically similar tissues. The TWAS analysis indicated that gene expression at 39 loci is associated with endometriosis, including five known endometriosis risk loci. SMR analyses identified potential target genes pleiotropically or causally associated with reproductive traits and diseases including endometriosis. However, without taking account of genetic variants, a direct comparison between women with and without endometriosis showed no significant difference in endometrial gene expression.

LARGE SCALE DATA

The eQTL dataset generated in this study is available at http://reproductivegenomics.com.au/shiny/endo_eqtl_rna/. Additional datasets supporting the conclusions of this article are included within the article and the supplementary information files, or are available on reasonable request.

LIMITATIONS, REASONS FOR CAUTION

Data are derived from fresh tissue samples and expression levels are an average of expression from different cell types within the endometrium. Subtle cell-specifc expression changes may not be detected and differences in cell composition between samples and across the menstrual cycle will contribute to sample variability. Power to detect tissue specific eQTLs and differences between women with and without endometriosis was limited by the sample size in this study. The statistical approaches used in this study identify the likely gene targets for specific genetic risk factors, but not the functional mechanism by which changes in gene expression may influence disease risk.

WIDER IMPLICATIONS OF THE FINDINGS

Our results identify novel genetic variants that regulate gene expression in endometrium and the majority of these are shared across tissues. This allows analysis with large publicly available datasets to identify targets for female reproductive traits and diseases. Much larger studies will be required to identify genetic regulation of gene expression that will be specific to endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Health and Medical Research Council (NHMRC) under project grants GNT1026033, GNT1049472, GNT1046880, GNT1050208, GNT1105321, GNT1083405 and GNT1107258. G.W.M is supported by a NHMRC Fellowship (GNT1078399). J.Y is supported by an ARC Fellowship (FT180100186). There are no competing interests.

Cross-disorder analysis of endometriosis and its comorbid diseases reveals shared genes and molecular pathways and proposes putative biomarkers of endometriosis

RESEARCH QUESTION

Women with endometriosis are considered to be at higher risk of several chronic diseases, such as autoimmune disorders, gynaecological cancers, asthma/atopic diseases and cardiovascular and inflammatory bowel diseases. Could the study of endometriosis-associated comorbidities help to identify potential biomarkers and target pathways of endometriosis?

DESIGN

A systematic review was performed to identify all possible endometriosis-associated comorbid conditions. Next, this list of disorders was coded into MeSH terms, and the gene expression profiles were downloaded from the Phenopedia database and subsequently analysed following a systems biology approach.

RESULTS

The results identified a group of 127 candidate genes that were recurrently expressed in endometriosis and its closest comorbidities and that were defined as 'endometriosis sibling disorders' (ESD). The enrichment analysis showed that these candidate genes are principally involved in immune and drug responses, hormone metabolism and cell proliferation, which are well-known hallmarks of endometriosis. The expression of ESD genes was then validated on independent sample cohorts (n = 207 samples), in which the involvement of 16 genes (AGTR1, BDNF, C3, CCL2, CD40, CYP17A1, ESR1, IGF1, IGF2, IL10, MMP1, MMP7, MMP9, PGR, SERPINE1 and TIMP2) in endometriosis was confirmed. Several of these genes harbour polymorphisms that associate to either endometriosis or its comorbid conditions.

CONCLUSIONS

The study results highlight the molecular processes underlying the aetiopathogenesis of endometriosis and its comorbid conditions, and identify putative endometriosis biomarkers.

The Pathogenesis of Endometriosis: Molecular and Cell Biology Insights

The etiopathogenesis of endometriosis is a multifactorial process resulting in a heterogeneous disease. Considering that endometriosis etiology and pathogenesis are still far from being fully elucidated, the current review aims to offer a comprehensive summary of the available evidence. We performed a narrative review synthesizing the findings of the English literature retrieved from computerized databases from inception to June 2019, using the Medical Subject Headings (MeSH) unique ID term “Endometriosis” (ID:D004715) with “Etiology” (ID:Q000209), “Immunology” (ID:Q000276), “Genetics” (ID:D005823) and “Epigenesis, Genetic” (ID:D044127). Endometriosis may origin from Müllerian or non-Müllerian stem cells including those from the endometrial basal layer, Müllerian remnants, bone marrow, or the peritoneum. The innate ability of endometrial stem cells to regenerate cyclically seems to play a key role, as well as the dysregulated hormonal pathways. The presence of such cells in the peritoneal cavity and what leads to the development of endometriosis is a complex process with a large number of interconnected factors, potentially both inherited and acquired. Genetic predisposition is complex and related to the combined action of several genes with limited influence. The epigenetic mechanisms control many of the processes involved in the immunologic, immunohistochemical, histological, and biological aberrations that characterize the eutopic and ectopic endometrium in affected patients. However, what triggers such alterations is not clear and may be both genetically and epigenetically inherited, or it may be acquired by the particular combination of several elements such as the persistent peritoneal menstrual reflux as well as exogenous factors. The heterogeneity of endometriosis and the different contexts in which it develops suggest that a single etiopathogenetic model is not sufficient to explain its complex pathobiology.

Role of FN1 and GREB1 gene polymorphisms in endometriosis

Endometriosis is a complex gynecological disorder, affecting up to 10% of women of childbearing age, characterized by the presence of functional endometrial tissue at ectopic positions generally within the peritoneum. It is a heritable condition influenced by multiple genetic, epigenetic and environmental factors, with an overall heritability estimated at approximately 50%. The aim of the present study was to evaluate the association of rs1250248 and rs11674184 single nucleotide polymorphisms (SNPs), mapping to fibronectin 1 (FN1) and growth regulation by estrogen in breast cancer 1 (GREB1) genetic loci, respectively, with the risk of endometriosis. A total of 166 women with endometriosis (stages I–IV) who were hospitalized for the condition, diagnosed by laparoscopic intervention and histologically confirmed, and 168 normal controls were recruited and genotyped. Genotyping of the rs1250248 and rs11674184 SNPs was performed with TaqMan primer/probe sets. A significant association was detected with the A allele, as well as the AA and AG genotypes of rs1250248 (FN1) in patients with endometriosis, as well as in patients with stage I and II of the disease only. The rs11674184 SNP of the GREB1 gene was not found to be associated with an increased susceptibility to endometriosis either for all patients (stages I–IV) or for subgroups of stage I and II or III and IV of the disease only. Our results demonstrated a genetic association between the rs1250248 (FN1) SNP and endometriosis at both the genotypic and allelic level. However, although rs11674184 of GREB1 constitutes one of the most consistently associated SNPs with endometriosis in European ancestry populations, it was not found to be associated with endometriosis in this study.

Expression and role of hScrib in endometrium, endometriosis, and endometrial adenocarcinoma

To explore the role of hScrib in the pathogenesis of endometriosis.This was a retrospective study of 240 women in our hospital between January 2014 and January 2017. The expression of hScrib in endometrium (EM), endometriosis (EMs), and endometrial adenocarcinoma (EC) was investigated, and compared the differences among them. Serum levels, protein expressions, localizations, and correlations of hScrib and E-cadherin were determined.The levels of serum soluble hScrib and E-cadherin were significantly highest in EC, followed by EMs, and healthy women (P < .05). hScrib protein content was opposite result in 3 tissues (P < .05), and was negatively correlated with r-AFS stage in EMs. The location changed from membrane to cytoplasm. Co-localization of hScrib with E-cadherin was found at extensive cell-cell boundaries in EMs.hScrib and E-cadherin may be as new diagnostic markers of endometriosis. Low expression of hScrib leads to the loss of cell polarity and stability. Also, hScrib may induce EMT through regulating E-cadherin, might play an important role in pathogenesis of 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.

Pathogenomics of Endometriosis Development

For over 100 years, endometriosis, as a chronic, estrogen-dependent, inflammatory, heritable disease affecting approximately 5–10% of women in reproductive age has been the focus of clinicians and scientists. In spite of numerous environmental, genetic, epigenetic, endocrine, and immunological studies, our knowledge of endometriosis is still fragmentary, and its precise pathophysiology and pathogenomics remain a mystery. The implementation of new technologies has provided tremendous progress in understanding the many intrinsic molecular mechanisms in the development of endometriosis, with progenitor and stem cells (SCs) of the eutopic endometrium as the starting players and endometriotic lesions as the final pathomorphological trait. Novel data on the molecular, genetic, and epigenetic mechanisms of the disease are briefly outlined. We hypothesize the existence of an endometriosis development genetic program (EMDP) that governs the origin of endometrium stem cells programmed for endometriosis (1), their transition (metaplasia) into mesenchymal SCs (2), and their invasion of the peritoneum and progression to endometriotic lesions (3). The pros and cons of the recent unifying theory of endometriosis are also discussed. Complex genomic and epigenetic interactions at different stages of the endometriosis process result in different forms of the disease, with specific features and clinical manifestations. The significance of the EMDP in elaborating a new strategy for endometriosis prediction, prevention, and treatment is discussed.

A focus on the distinctions and current evidence of endometriosis in adolescents

Endometriosis (EM) occurring in adolescents presents distinct clinical and histologic characteristics compared to the disease in women. Because the symptoms of EM are nonspecific, often overlapping with those experienced in a range of gynecological and gastrointestinal conditions, the process of reaching a diagnosis of EM is often delayed. The diagnosis of EM is suspected depending on the history and the symptoms and signs, is corroborated by physical examination and imaging techniques, and is finally proved by histological examination of specimens collected during laparoscopy. Currently, there is insufficient evidence to make strong recommendations for management in adolescents who may have EM. This short report reviews some peculiarities of EM in adolescents and provides an update of recent knowledge of the diagnosis and treatment of EM. We hope that the present contribution may help to bring more attention to the clinical diagnosis of EM and consequently aid in decreasing diagnostic delay.

The role of IL‑16 gene polymorphisms in endometriosis

Endometriosis is one of the most common gynecological diseases affecting up to 10% of the female population of childbearing age and a major cause of pain and infertility. It is influenced by multiple genetic, epigenetic and environmental factors. Interleukin-16 (IL-16) is a proinflammatory cytokine playing a pivotal role in many inflammatory and autoimmune diseases as well as in the pathogenesis of endometriosis. The aim of the present study was to evaluate the association of two IL-16 gene single nucleotide polymorphisms (SNPs), rs4072111 and rs11556218, with the risk of endometriosis in women from Greece as well as to gain insight about the structural consequences of these two exonic SNPs regarding development of the disease. A total of 159 women with endometriosis (stages I–IV) hospitalized for endometriosis, diagnosed by laparoscopic intervention and histologically confirmed, and 146 normal controls were recruited and genotyped. Subjects were genotyped using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) strategy. A significant association was detected regarding the GG and GT genotype as well as 'G' allele of rs11556218 in patients with endometriosis. The rs4072111 SNP of the IL-16 gene was not found to be associated with an increased susceptibility to endometriosis either for all patients (stages I–IV) or for stage III and IV of the disease only. Our results demonstrated that rs11556218 is associated with endometriosis in Greek women, probably by resulting in the aberrant expression of IL-16, as suggested by the bioinformatics analysis conducted on the SNP-derived protein sequences, which indicated a possible association between mutation and functional modification of Pro-IL-16.