The pains of endometriosis

A new concept of endometriosis and adenomyosis: tissue injury and repair (TIAR)

Pelvic endometriosis, deeply infiltrating endometriosis and uterine adenomyosis share a common pathophysiology and may be integrated into the physiological mechanism and new nosological concept of 'tissue injury and repair' (TIAR) and may, in this context, just represent the extreme of a basically physiological, estrogen-related mechanism that is pathologically exaggerated in an extremely estrogen-sensitive reproductive organ. The acronym TIAR describes a fundamental and apparently ubiquitous biological system that becomes operative in mesenchymal tissues following tissue injury and, upon activation, results in the local production of estradiol. Endometriosis and adenomyosis are caused by trauma. In the spontaneously developing disease, chronic uterine peristaltic activity or phases of hyperperistalsis induce, at the endometrial-myometrial interface near the fundo-cornual raphe, microtraumatisations, with activation of the TIAR mechanism. With ongoing traumatisations, such sites of inflammation might accumulate and the increasingly produced estrogens interfere in a paracrine fashion with ovarian control over uterine peristaltic activity, resulting in permanent hyperperistalsis and a self-perpetuation of the disease process. Overt autotraumatisation of the uterus with dislocation of fragments of basal endometrium into the peritoneal cavity and infiltration of basal endometrium into the depth of the myometrial wall ensues. In most cases of endometriosis/adenomyosis a causal event early in the reproductive period of life must be postulated, rapidly leading to archimetral hyperestrogenism and uterine hyperperistalsis. In late premenopausal adenomyosis such an event might not have occurred. However, as indicated by the high prevalence of the disease, it appears to be unavoidable that, with time, chronic normoperistalsis throughout the reproductive period of life accumulates to the same extent of microtraumatisation. With activation of the TIAR mechanism followed by chronic inflammation and infiltrative growth, endometriosis/adenomyosis of the younger woman and premenopausal adenomyosis share in principal the same pathophysiology.

Effect of human umbilical cord mesenchymal stem cells transplantation on nerve fibers of a rat model of endometriosis

Background

Endometriosis is a common, benign, oestrogen-dependent, chronic gynaecological disorder associated with pelvic pain and infertility. Some researchers have identified nerve fibers in endometriotic lesions in women with endometriosis. Mesenchymal stem cells (MSCs) have attracted interest for their possible use for both cell and gene therapies because of their capacity for self-renewal and multipotentiality of differentiation. We investigated how human umbilical cord-MSCs (hUC-MSCs) could affect nerve fibers density in endometriosis.

Materials and Methods

In this experimental study, hUC-MSCs were isolated from fresh human umbilical cord, characterized by flow cytometry, and then transplanted into surgically induced endometriosis in a rat model. Ectopic endometrial implants were collected four weeks later. The specimens were sectioned and stained immunohistochemically with antibodies against neurofilament (NF), nerve growth factor (NGF), NGF receptor p75 (NGFRp75), tyrosine kinase receptor-A (Trk-A), calcitonin gene-related peptide (CGRP) and substance P (SP) to compare the presence of different types of nerve fibers between the treatment group with the transplantation of hUC-MSCs and the control group without the transplantation of hUC-MSCs.

Results

There were significantly less nerve fibers stained with specific markers we used in the treatment group than in the control group (p<0.05).

Conclusion

MSC from human umbilical cord reduced nerve fiber density in the treatment group with the transplantation of hUC-MSCs.

Dual suppression of estrogenic and inflammatory activities for targeting of endometriosis

Estrogenic and inflammatory components play key roles in a broad range of diseases including endometriosis, a common estrogen-dependent gynecological disorder in which endometrial tissue creates inflammatory lesions at extrauterine sites, causing pelvic pain and reduced fertility. Current medical therapies focus primarily on reducing systemic levels of estrogens, but these are of limited effectiveness and have considerable side effects. We developed estrogen receptor (ER) ligands, chloroindazole (CLI) and oxabicycloheptene sulfonate (OBHS), which showed strong ER-dependent anti-inflammatory activity in a preclinical model of endometriosis that recapitulates the estrogen dependence and inflammatory responses of the disease in immunocompetent mice and in primary human endometriotic stromal cells in culture. Estrogen-dependent phenomena, including cell proliferation, cyst formation, vascularization, and lesion growth, were all arrested by CLI or OBHS, which prevented lesion expansion and also elicited regression of established lesions, suppressed inflammation, angiogenesis, and neurogenesis in the lesions, and interrupted crosstalk between lesion cells and infiltrating macrophages. Studies in ERα or ERβ knockout mice indicated that ERα is the major mediator of OBHS effectiveness and ERβ is dominant in CLI actions, implying involvement of both ERs in endometriosis. Neither ligand altered estrous cycling or fertility at doses that were effective for suppression of endometriosis. Hence, CLI and OBHS are able to restrain endometriosis by dual suppression of the estrogen-inflammatory axis. Our findings suggest that these compounds have the desired characteristics of preventive and therapeutic agents for clinical endometriosis and possibly other estrogen-driven and inflammation-promoted disorders.

Urine, peritoneal fluid and omental fat proteomes of reproductive age women: Endometriosis-related changes and associations with endocrine disrupting chemicals

Endometriosis, ectopic growth of the uterine lining (endometrium), which affects 6-11% of reproductive age women, is associated with pelvic pain and infertility. We investigated the peritoneal fluid (PF), urine and omental fat (OF) proteomes of women with endometriosis vs. individuals with no surgically visualized endometriosis. All participants were enrolled in the NICHD-funded ENDO Study. A two-step proteomic study was performed. The first, a broad survey, employed a semi-quantitative gel LC-mass spectrometry (MS) workflow: SDS PAGE fractionation, trypsin digestion and LC-MS/MS. The results showed sample integrity but failed to detect any differences between women with and without endometriosis. The second step was a quantitative analysis of OF samples. We employed another sample set (n=30) from women ± disease and isobaric mass-tag (iTRAQ) chemistry to label peptides and 2D LC-MS/MS for protein identification and quantification. Three proteins-matrix metalloproteinase-9, neutrophil elastase, and FAM49B-were significantly lower in abundance in samples from women with endometriosis. Interestingly, neutrophil elastase and FAM49B levels were associated with higher levels of a subset of endocrine disrupting chemicals (EDCs) that were previously measured in the same samples. The results of these experiments showed the feasibility of associating endometriosis with changes in the OF protein repertoire and EDC levels.

BIOLOGICAL SIGNIFICANCE

Endometriosis, pathological growth of the uterine lining, is associated with significant morbidities, including pain and infertility. However, the causes of this common condition are poorly understood. This study determined whether endometriosis was associated with changes in the protein composition of peritoneal fluid, urine and/or omental fat. A protein of unknown function (FAM49B) and two proteinases (metalloproteinase-9, neutrophil elastase) were down regulated in OF samples from women with versus without endometriosis. These findings suggested proteinase imbalances at sites that were distant from the endometriotic lesions. Additionally, FAM49B and neutrophil elastase levels were associated with higher levels of a subset of environmental chemicals that were quantified in the same samples, suggesting other possible associations. Thus, this work generated hypotheses that will be tested in further studies.

The association between vascular endothelial growth factor (VEGF) +405G>C genetic polymorphism and endometriosis

The vascular endothelial growth factor (VEGF) is one of the most important candidate genes for the development of endometriosis, and VEGF genetic polymorphisms might be potentially associated with endometriosis risk. However, the results still remain controversial. The objective of this study aimed to perform a comprehensive meta-analysis to explore a better understanding of the effects of VEGF +405G>C genetic polymorphism on the risk of endometriosis. A total of eleven eligible studies were eventually identified in this meta-analysis, including 2829 endometriosis cases and 2947 controls. In the overall analysis, no significant association between the VEGF +405G>C genetic polymorphism and the risk of endometriosis was detected in all genetic models (for homozygote comparison [CC versus vs. GG]: OR = 1.21, 95% CI 0.67-2.19, P = 0.537; for heterozygote comparison [CG vs. GG]: OR = 1.16, 95% CI 0.86-1.56, P = 0.348; for dominant comparison CC/CG vs. GG: OR = 1.10, 95% CI 0.93-1.30, P = 0.263; for recessive comparison [CC vs. CG/GG]: OR = 1.03, 95% CI 0.73-1.47, P = 0.857; allele comparison [C vs. G]: OR = 0.99, 95% CI 0.70-1.40, P = 0.962). In the subgroup analysis by ethnicities, there was no significant association between VEGF +405G>C genetic polymorphism and endometriosis risk in Asians and/or Caucasians under all genetic models (all P-values >0.05). No publication bias was observed in this study. This meta-analysis supports that the VEGF +405G>C genetic polymorphism is not significant associated with the risk of endometriosis.

Inflammation and nerve fiber interaction in endometriotic pain

Endometriosis is an extremely prevalent estrogen-dependent condition characterized by the growth of ectopic endometrial tissue outside the uterine cavity, and is often presented with severe pain. Although the relationship between lesion and pain remains unclear, nerve fibers found in close proximity to endometriotic lesions may be related to pain. Also, women with endometriosis pain develop central sensitization. Endometriosis creates an inflammatory environment and recent research is beginning to elucidate the role of inflammation in stimulating peripheral nerve sensitization. In this review, we discuss endometriosis-associated inflammation, peripheral nerve fibers, and assess their potential mechanism of interaction. We propose that an interaction between lesions and nerve fibers, mediated by inflammation, may be important in endometriosis-associated pain.

Stroke in Young Women

In women ages 15-45 years, an additional set of risk factors are important in the pathogenesis of ischemic stroke. Some of these pertain strictly to women, and relate to exogenous hormones and pregnancy. Various other conditions are more common in women, which include migraine with aura, selected vascular disorders and autoimmune conditions. These differences do have implications for management in both the primary and secondary prevention of stroke in this age group.

Molecular classification of endometriosis and disease stage using high-dimensional genomic data

Endometriosis (E), an estrogen-dependent, progesterone-resistant, inflammatory disorder, affects 10% of reproductive-age women. It is diagnosed and staged at surgery, resulting in an 11-year latency from symptom onset to diagnosis, underscoring the need for less invasive, less expensive approaches. Because the uterine lining (endometrium) in women with E has altered molecular profiles, we tested whether molecular classification of this tissue can distinguish and stage disease. We developed classifiers using genomic data from n = 148 archived endometrial samples from women with E or without E (normal controls or with other common uterine/pelvic pathologies) across the menstrual cycle and evaluated their performance on independent sample sets. Classifiers were trained separately on samples in specific hormonal milieu, using margin tree classification, and accuracies were scored on independent validation samples. Classification of samples from women with E or no E involved 2 binary decisions, each based on expression of specific genes. These first distinguished presence or absence of uterine/pelvic pathology and then no E from E, with the latter further classified according to severity (minimal/mild or moderate/severe). Best performing classifiers identified E with 90%-100% accuracy, were cycle phase-specific or independent, and used relatively few genes to determine disease and severity. Differential gene expression and pathway analyses revealed immune activation, altered steroid and thyroid hormone signaling/metabolism, and growth factor signaling in endometrium of women with E. Similar findings were observed with other disorders vs controls. Thus, classifier analysis of genomic data from endometrium can detect and stage pelvic E with high accuracy, dependent or independent of hormonal milieu. We propose that limited classifier candidate genes are of high value in developing diagnostics and identifying therapeutic targets. Discovery of endometrial molecular differences in the presence of E and other uterine/pelvic pathologies raises the broader biological question of their impact on the steroid hormone response and normal functions of this tissue.

Targeting the Wnt/β-catenin pathway in endometriosis: a potentially effective approach for treatment and prevention

Endometriosis is a chronic, estrogen-dependent disease associated with infertility and pelvic pain. Endometriosis is defined by the presence of extra-uterine endometrial tissue. It affects approximately 10% of reproductive-aged women. However, the underlying etiology, pathogenesis and pathophysiology remain to be fully elucidated. Knowledge of these factors is indispensable for the development of targeted therapies for prevention and treatment of endometriosis. Several studies, including those from our laboratory, have suggested that aberrant activation of the Wnt/β-catenin pathway may be involved in the pathophysiology of endometriosis. This is a review of the literature focused on the aberrant activation of the Wnt/β-catenin pathway in patients with endometriosis, and on how targeting the Wnt/targeting pathway may be a potentially effective approach for treating and/or preventing endometriosis.

Targeting the Wnt/β-catenin pathway in endometriosis: a potentially effective approach for treatment and prevention

Endometriosis is a chronic, estrogen-dependent disease associated with infertility and pelvic pain. Endometriosis is defined by the presence of extra-uterine endometrial tissue. It affects approximately 10% of reproductive-aged women. However, the underlying etiology, pathogenesis and pathophysiology remain to be fully elucidated. Knowledge of these factors is indispensable for the development of targeted therapies for prevention and treatment of endometriosis. Several studies, including those from our laboratory, have suggested that aberrant activation of the Wnt/β-catenin pathway may be involved in the pathophysiology of endometriosis. This is a review of the literature focused on the aberrant activation of the Wnt/β-catenin pathway in patients with endometriosis, and on how targeting the Wnt/targeting pathway may be a potentially effective approach for treating and/or preventing endometriosis.

Elevated peritoneal expression and estrogen regulation of nociceptive ion channels in endometriosis

CONTEXT

Ovarian suppression is a common treatment for endometriosis-associated pelvic pain. Its exact mechanism of action is poorly understood, although it is assumed to reflect reduced production/action of estrogens.

OBJECTIVE

The objective of the study was to measure the expression of mRNAs encoded by nociceptive genes in the peritoneum of women with chronic pelvic pain (CPP) with or without endometriosis and to investigate whether estrogens alter nociceptive gene expression in human sensory neurons.

DESIGN

The study was performed using human tissue analysis and cell culture.

SETTING

The study was conducted at a university research institute.

PATIENTS

Peritoneal biopsies were obtained from women with CPP and endometriosis (n = 12), CPP and no endometriosis (n = 10), and no pain or endometriosis (n = 5). Endometriosis lesions were obtained from women with endometriosis (n = 18).

MAIN OUTCOME MEASURES

mRNAs encoding ion channels (P2RX3, SCN9A, SCN11A, TRPA1, TRPV1) and the neurotransmitter TAC1 were measured in human tissue samples and in human embryonic stem cell-derived sensory neurons treated with estrogens.

RESULTS

TRPV1, TRPA1, and SCN11A mRNAs were significantly higher in the peritoneum from women with endometriosis (P < .001, P < .01). TRPV1, SCN9A, and TAC1 were elevated in endometriosis lesions (P < .05). P2RX3 mRNA was increased in the peritoneum of women with CPP, with and without endometriosis (P < .05). Incubation of sensory neurons with 17β-estradiol increased TRPV1 mRNA (P < .01). The estrogen receptor-β-selective agonist 2,3-bis(4-hydroxy-phenyl)-propionitrile increased concentrations of TRPV1, P2RX3, SCN9A, and TAC1 mRNAs.

CONCLUSIONS

Estrogen-dependent expression of TRPV1 in sensory neurons may explain why ovarian suppression can reduce endometriosis-associated pain. Strategies directly targeting ion channels may offer an alternative option for the management of CPP.

Resolvins RvD1 and 17(R)-RvD1 alleviate signs of inflammation in a rat model of endometriosis

OBJECTIVE

To study the effects of two resolvins of D series, RvD1 and 17(R)-RvD1, on inflammatory signs associated with endometriosis (ENDO).

DESIGN

In vivo research study.

SETTING

Research laboratory.

ANIMAL(S)

Female Sprague-Dawley rats.

INTERVENTION(S)

Intravenous or intraperitoneal injections of RvD1 (300 ng/kg) or 17(R)-RvD1 (300 and 900 ng/kg) in rats with surgically induced ENDO.

MAIN OUTCOME MEASURE(S)

Vascular permeability of ectopic endometrial growths was assessed by Evans Blue extravasation; vaginal hyperalgesia was assessed with telemetered visceromotor response.

RESULT(S)

Both resolvins, but not vehicle, significantly decreased vascular permeability in ectopic endometrial tissue. 17(R)-RvD1 also significantly alleviated severity of vaginal hyperalgesia.

CONCLUSION(S)

Our results suggest that RvD1 and 17(R)-RvD1 can be considered for further investigation of their therapeutic potential for treating ENDO.

Neurobiological mechanisms of pelvic pain

Pelvic pain is a common condition which significantly deteriorates health-related quality of life. The most commonly identified causes of pain in the pelvic region are gynaecologic, urologic, gastrointestinal, neurological, and musculoskeletal. However, in up to 33% of patients the source of this symptom is not identified, frustrating both patients and health-care professionals. Pelvic pain may involve both the somatic and visceral systems, making the differential diagnosing challenging. This paper aimed to review the mechanisms involved in pelvic pain perception by analyzing the neural plasticity and molecules which are involved in these complex circuits.

Possible Loss of GABAergic Inhibition in Mice With Induced Adenomyosis and Treatment With Epigallocatechin-3-Gallate Attenuates the Loss With Improved Hyperalgesia

We have previously reported that induction of adenomyosis in mice results in progressive hyperalgesia, uterine hyperactivity, and elevated plasma corticosterone levels and that epigallocatechin-3-gallate (EGCG) treatment dose dependently suppressed myometrial infiltration and improved generalized hyperalgesia. In this study, we examined whether adenomyosis induced in mice results in the loss of GABAergic inhibition as manifested by the diminished glutamate decarboxylase (GAD) 65-expressing neurons in the brainstem nucleus raphe magnus (NRM) that could correlate with heightened hyperalgesia. We also evaluated whether EGCG treatment would reverse these changes and also improve the expression of some proteins known to be involved in adenomyosis. Adenomyosis was induced in 28 female ICR mice and additional 12 were used as blank controls, as reported previously. At the 16th week, all mice with induced adenomyosis received low- or high-dose EGCG treatment or untreated. Mice without adenomyosis received no treatment. After 3 weeks of treatment, their uterine horns and brains were harvested. The right uterine horn was used for immunohistochemistry analysis and for counting the number of macrophages infiltrating into the ectopic endometrium. The brainstem NRM sections were subjected to immunofluorescence staining for GAD65. We found that mice with induced adenomyosis had significantly diminished GAD65-expressing neurons, concomitant with heightened hyperalgesia. Treatment with EGCG increased these neurons in conjunction with improved hyperalgesia, reduced the expression of p-p65, cycloxygenase 2, oxytocin receptor, collagen I and IV, and transient receptor potential vanilloid type 1 in ectopic endometrium or myometrium, reduced the number of macrophages infiltrating into the ectopic endometrium while elevated the expression of progesterone receptor isoform B. Thus, adenomyosis-induced pain resembles neuropathic pain in that there is a remarkable central plasticity.

An Investigation of the Relationship between Pelvic Pain and Density of Nerve Fibers in Peritoneal Lesions of Endometriosis

Purpose

Endometriosis is a gynecological disease often characterized by severe pelvic pain, including perimenstrual and intermenstrual pain and dyspareunia. Sensory nerve fibers within peritoneal lesions have previously been shown to contribute to generation of pain in endometriosis; however, their association with different types of pelvic pain is currently uncertain.

Methods

Peritoneal endometriotic lesions (n = 30) were sectioned and stained immunohistochemically with protein gene product 9.5 (PGP 9.5; pan-neuronal marker), neuropeptide Y (NPY; sympathetic), vasoactive intestinal polypeptide (VIP; parasympathetic), substance P (SP; sensory) and nerve growth factor (NGF) to identify nerve fibers and neurotrophin levels. Densities were assessed within stroma of the lesions and in the adjacent peritoneum. Pelvic pain scores were obtained using a visual analogue scale (VAS), and correlation analysis was performed.

Results

Increased density of nerve fibers was observed within the stroma of lesions. NGF expression was significantly increased in glandular epithelium, compared with stromal regions (p = 0.026) and correlated inversely with menstrual pain scores (p = 0.05). Sympathetic nerve fiber density (NPY) in stroma showed a significant positive correlation with intensity of menstrual pain (p = 0.04). Parasympathetic nerve fiber density (VIP) also showed a strong trend toward a positive correlation with menstrual pain intensity (p = 0.056).

Conclusions

There is increased neurogenesis in the stromal region. Innervation of lesions correlates to intensity of menstrual pain. NGF in glandular epithelium may promote growth of nerve fibers into the core of lesions; however, the inverse correlation between NGF expression in glandular epithelium and menstrual pain indicates that mechanisms of pain generation in endometriosis are complex.

Peripheral changes in endometriosis-associated pain

BACKGROUND

Pain remains the cardinal symptom of endometriosis. However, to date, the underlying mechanisms are still only poorly understood. Increasing evidence points towards a close interaction between peripheral nerves, the peritoneal environment and the central nervous system in pain generation and processing. Recently, studies demonstrating nerve fibres and neurotrophic and angiogenic factors in endometriotic lesions and their vicinity have led to increased interest in peripheral changes in endometriosis-associated pain. This review focuses on the origin and function of these nerves and factors as well as possible peripheral mechanisms that may contribute to the generation and modulation of pain in women with endometriosis.

METHODS

We conducted a systematic search using several databases (PubMed, MEDLINE, EMBASE and CINAHL) of publications from January 1977 to October 2013 to evaluate the possible roles of the peripheral nervous system in endometriosis pathophysiology and how it can contribute to endometriosis-associated pain.

RESULTS

Endometriotic lesions and peritoneal fluid from women with endometriosis had pronounced neuroangiogenic properties with increased expression of new nerve fibres, a shift in the distribution of sensory and autonomic fibres in some locations, and up-regulation of several neurotrophins. In women suffering from deep infiltrating endometriosis and bowel endometriosis, in which the anatomical distribution of lesions is generally more closely related to pelvic pain symptoms, endometriotic lesions and surrounding tissues present higher nerve fibre densities compared with peritoneal lesions and endometriomas. More data are needed to fully confirm a direct correlation between fibre density in these locations and the amount of perceived pain. A better correlation between the presence of nerve fibres and pain symptoms seems to exist for eutopic endometrium. However, this appears not to be exclusive to endometriosis. No correlation between elevated neurotrophin levels and pain severity appears to exist, suggesting the involvement of other mediators in the modulation of pain.

CONCLUSIONS

The increased expression of neurotrophic factors and nerve fibres in endometriotic lesions, eutopic endometrium and the peritoneum imply a role of such peripheral changes in the pathogenesis of endometriosis-associated pain. However, a clear link between these findings and pain in patients with endometriosis has so far not been demonstrated.

Endometriosis: pathogenesis and treatment

Endometriosis is defined as the presence of endometrial-type mucosa outside the uterine cavity. Of the proposed pathogenic theories (retrograde menstruation, coelomic metaplasia and Müllerian remnants), none explain all the different types of endometriosis. According to the most convincing model, the retrograde menstruation hypothesis, endometrial fragments reaching the pelvis via transtubal retrograde flow, implant onto the peritoneum and abdominal organs, proliferate and cause chronic inflammation with formation of adhesions. The number and amount of menstrual flows together with genetic and environmental factors determines the degree of phenotypic expression of the disease. Endometriosis is estrogen-dependent, manifests during reproductive years and is associated with pain and infertility. Dysmenorrhoea, deep dyspareunia, dyschezia and dysuria are the most frequently reported symptoms. Standard diagnosis is carried out by direct visualization and histologic examination of lesions. Pain can be treated by excising peritoneal implants, deep nodules and ovarian cysts, or inducing lesion suppression by abolishing ovulation and menstruation through hormonal manipulation with progestins, oral contraceptives and gonadotropin-releasing hormone agonists. Medical therapy is symptomatic, not cytoreductive; surgery is associated with high recurrence rates. Although lesion eradication is considered a fertility-enhancing procedure, the benefit on reproductive performance is moderate. Assisted reproductive technologies constitute a valid alternative. Endometriosis is associated with a 50% increase in the risk of epithelial ovarian cancer, but preventive interventions are feasible.

Genetic variants underlying risk of endometriosis: insights from meta-analysis of eight genome-wide association and replication datasets

BACKGROUND

Endometriosis is a heritable common gynaecological condition influenced by multiple genetic and environmental factors. Genome-wide association studies (GWASs) have proved successful in identifying common genetic variants of moderate effects for various complex diseases. To date, eight GWAS and replication studies from multiple populations have been published on endometriosis. In this review, we investigate the consistency and heterogeneity of the results across all the studies and their implications for an improved understanding of the aetiology of the condition.

METHODS

Meta-analyses were conducted on four GWASs and four replication studies including a total of 11 506 cases and 32 678 controls, and on the subset of studies that investigated associations for revised American Fertility Society (rAFS) Stage III/IV including 2859 cases. The datasets included 9039 cases and 27 343 controls of European (Australia, Belgium, Italy, UK, USA) and 2467 cases and 5335 controls of Japanese ancestry. Fixed and Han and Elkin random-effects models, and heterogeneity statistics (Cochran's Q test), were used to investigate the evidence of the nine reported genome-wide significant loci across datasets and populations.

RESULTS

Meta-analysis showed that seven out of nine loci had consistent directions of effect across studies and populations, and six out of nine remained genome-wide significant (P < 5 × 10⁻⁸), including rs12700667 on 7p15.2 (P = 1.6 × 10⁻⁹), rs7521902 near WNT4 (P = 1.8 × 10⁻¹⁵), rs10859871 near VEZT (P = 4.7 × 10⁻¹⁵), rs1537377 near CDKN2B-AS1 (P = 1.5 × 10⁻⁸), rs7739264 near ID4 (P = 6.2 × 10⁻¹⁰) and rs13394619 in GREB1 (P = 4.5 × 10⁻⁸). In addition to the six loci, two showed borderline genome-wide significant associations with Stage III/IV endometriosis, including rs1250248 in FN1 (P = 8 × 10⁻⁸) and rs4141819 on 2p14 (P = 9.2 × 10⁻⁸). Two independent inter-genic loci, rs4141819 and rs6734792 on chromosome 2, showed significant evidence of heterogeneity across datasets (P < 0.005). Eight of the nine loci had stronger effect sizes among Stage III/IV cases, implying that they are likely to be implicated in the development of moderate to severe, or ovarian, disease. While three out of nine loci were inter-genic, the remaining were in or near genes with known functions of biological relevance to endometriosis, varying from roles in developmental pathways to cellular growth/carcinogenesis.

CONCLUSIONS

Our meta-analysis shows remarkable consistency in endometriosis GWAS results across studies, with little evidence of population-based heterogeneity. They also show that the phenotypic classifications used in GWAS to date have been limited. Stronger associations with Stage III/IV disease observed for most loci emphasize the importance for future studies to include detailed sub-phenotype information. Functional studies in relevant tissues are needed to understand the effect of the variants on downstream biological pathways.

Role of the CXCL12-CXCR4 axis in the development of deep rectal endometriosis

Immunological and angiogenetic factors enhance the implantation of endometrial cells in the peritoneal cavity. The aim of this work was to determine the role of the CXCL12-CXCR4 axis in the attraction and the peritoneal implantation of endometriotic stromal cells in deep infiltrating endometriosis (DIE). Biopsies of DIE nodules were obtained from 14 patients undergoing surgical treatment for DIE with low rectal involvement and from 12 patients without macroscopic endometriosis undergoing laparoscopy. CXCR4 expression was evaluated by Western blot analysis and flow cytometry in eutopic endometrial cells and DIE stromal cells in primary cultures derived from the biopsies. CXCL12-induced migration of DIE eutopic endometrial stromal cells was evaluated by transwell migration. CXCL12 was assayed in peritoneal fluids by ELISA. CXCR4 expression was higher in eutopic endometrial stromal cells than in control endometrial cells (p<0.05) and in DIE stromal cells (p<0.05). Eutopic endometrial stromal cells were more attracted by CXCL12 than control cells (p<0.01). CXCL12 was higher in DIE peritoneal fluids than in controls (p<0.05). CXCR4 was down-regulated in deep infiltrating endometriotic stromal cells. The CXCL12-CXCR4 axis plays a role in the attraction of eutopic endometrial cells into the peritoneal cavity, and the down-regulation of CXCR4 in resident endometriotic cells could cause their arrest in situ.

Association study of the TNF-α -1031T/C and VEGF +450G/C polymorphisms with susceptibility to endometriosis

Tumor necrosis factor-α (TNF-α), a multifunctional proinflammatory cytokine, and vascular endothelial growth factor (VEGF), a major mediator of angiogenesis and vascular permeability, have been investigated in endometriosis patients of different populations. This study was carried out to investigate whether the two polymorphisms, TNF-α -1031T/C and VEGF +450G/C are associated with susceptibility to endometriosis in an Iranian population. Totally, 135 women with diagnosis of endometriosis and 173 women with no evidence of the disease were included in this study. The -1031T/C and +450G/C polymorphisms were assessed by PCR-RFLP analysis, using the two restriction enzymes BbsI and BsmFI, respectively. The frequencies of the TNF-α -1031TC genotype (p = 0.038) and the -1031 C allele (p = 0.048) were significantly lower in patients than control group. In contrast, no significant differences in the genotype and allele frequencies of the VEGF +450G/C polymorphism were found between the case and control groups. Our results suggest that the TNF-α -1031T/C polymorphism was associated with susceptibility to endometriosis in Iranian population, and the -1301C allele may have a protective role in development of endometriosis; On the contrary, we find no association between the VEGF +450G/C polymorphism and risk of endometriosis.

The relation between endometriosis and ovarian cancer - a review

BACKGROUND

Endometriosis is known to harbor characteristics substantiating its possible role as a precursor of ovarian cancer.

OBJECTIVE

To assess the quality of the literature regarding the association between endometriosis and ovarian cancer and to estimate the extent of this relation.

METHODS

An electronic literature search was conducted in PubMed and 1112 articles dealing with the relation between endometriosis and ovarian cancer were identified. Original articles based on case-control studies, cohort studies and cross-sectional studies were included. Studies consisting of populations with self-reported endometriosis were excluded, as were articles with fewer than 20 cases of ovarian cancer. Twenty-eight studies underwent detailed quality assessments based on the checklists developed by the Scottish Intercollegiate Guidelines Network (SIGN). Meta-analyses were conducted on selected subgroups of ovarian cancer with coexisting endometriosis.

RESULTS

None of the 28 studies was given the highest possible rating using the SIGN checklists. The risk of ovarian cancer in women with endometriosis was reported to be a standardized incidence ratio of 1.43-8.95, a rate ratio of 1.6-2.88, an odds ratio of 1.34, with a prevalence of ovarian cancer in 2.0-17.0% of women with endometriosis. Conversely, the prevalence of endometriosis in women with ovarian cancer ranged from 3.4 to 52.6%. Meta-analysis results were weakened by heterogeneity.

CONCLUSION

There is sufficient evidence to conclude that there is an increased risk of developing clear-cell and endometrioid epithelial ovarian cancer for women with histologically verified endometriosis. Nonetheless, prospective cohort studies assessing the relation between endometriosis and ovarian cancer will increase knowledge in this field.

Serum concentration of lignocaine after pertubation: an observational study

Objective

The objective of this study was to report the serum concentration of lignocaine after pertubation in patients with endometriosis.

Design

Prospective observational study.

Setting

The study was carried out at a gynaecological outpatient unit in Stockholm, Sweden.

Population

Eligible patients had endometriosis with a dysmenorrhoic pain score of >50 mm on a visual analogue scale, and patent fallopian tubes.

Methods

Patients with endometriosis (n = 25) were included in the study. The patients received pre-ovulatory pertubations with lignocaine hydrochloride 10 mg (n = 16) or ringer acetate (placebo, n = 9). The procedure comprised passing the study solution through the uterus and the fallopian tubes via an intra-cervical balloon catheter. Serum samples were collected at 0, 5, 15 and 30 min after pertubation.

Main Outcome Measures

The serum samples were analysed for the concentration of lignocaine with an LCMS-SIM method.

Results

Low levels of lignocaine were detected in the serum samples following pertubation of 10 mg lignocaine hydrochloride. The highest observed concentration was seen after 30 min (mean 0.050 μg/ml), with an individual maximum of 0.124 μg/ml. Maximum concentration (C_max) and time to C_max (T_max) could not be calculated, since the highest values were observed in the 30-min samples, which was the last sample obtained. Lignocaine was not detected after pertubation with placebo.

Conclusions

The serum levels of lignocaine following pertubation of 10 mg lignocaine hydrochloride are detectable but low. Lignocaine pertubated through the fallopian tubes reaches the peritoneal cavity and diffuses through the peritoneum into the blood circulation. Pertubation with lignocaine is safe and has no lignocaine-related adverse events.

Effect of siRNA against β-NGF on nerve fibers of a rat model with endometriosis

OBJECTIVE

This study examines whether silencing specific β-nerve growth factor small interfering RNA (β-NGF siRNA) can affect the growth of ectopic endometriotic implants, generalized hyperalgesia, and nerve fiber density in endometriosis.

METHODS

Four specific β-NGF siRNAs were detected by Western blot analysis, and the most efficient specific siRNA was transferred into rats with surgically induced endometriosis through gene transfer. The length × width × height of each ectopic transplant that survived from 2 groups were measured at pre-and postbombardment after 2 weeks. The transplants were collected 2 weeks after bombardment. Warm-water tail flick test was performed before the rats were sacrificed. The specimens were sectioned and stained immunohistochemically with antibodies against the types of nerve fibers to compare the presence of different nerve fibers in the treatment and control groups. The serums and supernatants of the peritoneal washings in the treatment and control groups were collected for enzyme-linked immunosorbent assay (ELISA) analysis. The extra rats were successfully induced with endometriosis and through gene transfer as described above. The spherical volumes of the transplants and tail flick latency post-bombardment after 4, 6, 8, and 10 weeks were measured.

RESULTS

The spherical volumes in the treatment group were much smaller than those in the control group, and tail flick latency significantly increased in the treatment group postbombardment after 2 weeks. The ELISA analysis showed that the concentrations of β-NGF in the serums and supernatants of the peritoneal fluid decreased in the treatment group unlike in the control group. Less sympathetic and sensory innervation was observed in the treatment group postbombardment after 2 weeks. The outcomes of the spherical volumes of the transplants and tail flick latency postbombardment after 4, 6, 8, and 10 weeks showed that the sizes of the transplants did not return to their previous size and that the treatment had some effects on generalized hyperalgesia.

CONCLUSION

Specific siRNA-mediated silencing of the β-NGF gene expression after gene transfer suppressed the growth of ectopic endometriotic implants resulted in a significant improvement in generalized hyperalgesia as well as reduced sympathetic and sensory nerve fiber density in the treatment group.

Prevalence and associated factors of female sexual dysfunction in women with endometriosis

OBJECTIVE

The issue of female sexual function is often overlooked in women with endometriosis, especially in mainland China. The objectives of this study were to estimate the prevalence and associated factors of female sexual dysfunction in endometriosis in China.

METHODS

This cross-sectional study was conducted at a referral university hospital in Beijing, Peoples Republic of China from July 2011 to April 2012. Women were recruited among inpatients scheduled for laparoscopic surgery based on signs and symptoms suggestive of endometriosis. Before laparoscopy, a semi-structured questionnaire was used to collect demographic data and disease characteristics. The simplified Chinese version of the Female Sexual Function Index was used to assess sexual function.

RESULTS

A total of 111 consecutive women with histologically confirmed endometriosis were enrolled in this study. The prevalence of female sexual dysfunction was 73% for those with endometriosis. Univariable analysis identified three potential predictors of female sexual dysfunction: pelvic pain intensity; deep infiltrating endometriosis status; and revised American Society for Reproductive Medicine stages. Multivariable analysis showed that moderate-to-severe pelvic pain (adjusted odds ratio [OR] 3.4, 95% confidence interval [CI] 1.3-8.8) and revised American Society for Reproductive Medicine stage III or IV (adjusted OR 4.4, 95% CI 1.3-15.5) were associated with increased risk of having female sexual dysfunction.

CONCLUSION

Female sexual dysfunction is common in women with endometriosis, especially for those with severe pelvic pain and advanced stages of endometriosis.

Interplay between Misplaced Müllerian-Derived Stem Cells and Peritoneal Immune Dysregulation in the Pathogenesis of Endometriosis

In the genetic regulation of Müllerian structures development, a key role is played by Hoxa and Wnt clusters, because they lead the transcription of different genes according to the different phases of the organogenesis, addressing correctly cell-to-cell interactions, allowing, finally, the physiologic morphogenesis. Accumulating evidence is suggesting that dysregulation of Wnt and/or Hox genes may affect cell migration during organogenesis and differentiation of Müllerian structures of the female reproductive tract, with possible dislocation and dissemination of primordial endometrial stem cells in ectopic regions, which have high plasticity to differentiation. We hypothesize that during postpubertal age, under the influence of different stimuli, these misplaced and quiescent ectopic endometrial cells could acquire new phenotype, biological functions, and immunogenicity. So, these kinds of cells may differentiate, specializing in epithelium, glands, and stroma to form a functional ectopic endometrial tissue. This may provoke a breakdown in the peritoneal cavity homeostasis, with the consequent processes of immune alteration, documented by peripheral mononuclear cells recruitment and secretion of inflammatory cytokines in early phases and of angiogenic and fibrogenic cytokines in the late stages of the disease.

Chronic pelvic pain in endometriosis: an overview

Chronic pelvic pain (CPP) could be considered nowadays a deep health problem that challenges physicians all over the world. This because its aetiology is still unclear, the course of the disease could vary a lot among different patients and through time in the same patient, and the response to treatments is not every time successful. Among women who underwent laparoscopy for CPP, endometriosis is found in about 1/3 of the cases, while only 25% of women with histological confirmed endometriosis are asymptomatic. A wide range of variables may exert their influence on the resulting pain syndrome in endometriosis; for example, score according to American society for reproductive medicine (rASRM), size of the sub-peritoneal and pelvic wall implants, Douglas obliteration, previous surgery. It is widely accepted nowadays that central nervous system (CNS) and peripheral nervous system (PNS) seems to influence each other and this interconnection play a key role in pain modulation. Moreover, the phenomena induced by endometriosis in the pelvis, including the breakdown of peritoneal homeostasis and the induction of the production of proinflammatory and proangiogenic cytokines, are responsible of altered innervations and modulation of pain pathways in these patients. There are many proposed medical and surgical approach to treat this painful syndrome, although there is necessity of more efforts to create new non-invasive strategies that set a more accurate diagnosis of the causes of endometriotic-related CPP, and therefore facilitate its eradication.

Prevalence of pain syndromes, mood conditions, and asthma in adolescents and young women with endometriosis

STUDY OBJECTIVE

Adult women with endometriosis are often diagnosed with comorbid pain, mood, and autoimmune conditions. This study aims to describe the occurrence of pain syndromes, mood conditions, and asthma in adolescents and young women with endometriosis evaluated at our medical center.

DESIGN

Retrospective review of medical records.

SETTING

Department of Obstetrics and Gynecology at a tertiary referral center.

PARTICIPANTS

138 adolescents/young women who were less than age 24 years at the time of their initial visit at our medical center, and whose surgical diagnosis of endometriosis was made at our institution or by outside institutions by the age of 21.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Prevalence of comorbid pain syndromes (defined as interstitial cystitis, irritable bowel syndrome, chronic headaches, chronic low back pain, vulvodynia, fibromyalgia, temporomandibular joint disease, and chronic fatigue syndrome), mood conditions (defined as depression and anxiety), and asthma.

RESULTS

Comorbid pain syndromes were found in 77 (56%) women, mood conditions in 66 (48%) women, and asthma in 31 (26%) women. Comparing endometriosis patients with and without comorbid pain syndromes, no differences were found in age at time of diagnosis, endometriosis symptoms, and endometriosis stage. Patients with comorbid pain syndromes were more likely to report mood conditions (62% vs 30% respectively, P < .001) and smoking (31% vs 10% respectively, P = .003), underwent more surgeries for endometriosis (median of 2 [range, 1-7] vs 1 [range, 1-5], P < .005), and were more likely to undergo appendectomy or cholecystectomy (30% vs 13%, P = .02).

CONCLUSIONS

Comorbid pain syndromes, mood conditions and asthma are common in adolescents and young women with endometriosis.

Angiogenesis and endometriosis

A comprehensive review was performed to survey the role of angiogenesis in the pathogenesis of endometriosis. This is a multifactorial disease in which the development and maintenance of endometriotic implants depend on their invasive capacity and angiogenic potential. The peritoneal fluid of patients with endometriosis is a complex suspension carrying inflammatory cytokines, growth factors, steroid hormones, proangiogenic factors, macrophages, and endometrial and red blood cells. These cells and their signaling products concur to promote the spreading of new blood vessels at the endometriotic lesions and surroundings, which contributes to the endometriotic implant survival. Experimental studies of several antiangiogenic agents demonstrated the regression of endometriotic lesions by reducing their blood supply. Further studies are necessary before these novel agents can be introduced into clinical practice, in particular the establishment of the safety of anti-angiogenic medications in women who are seeking to become pregnant.

Cellular and molecular basis for endometriosis-associated infertility

Endometriosis is a gynecological disease characterized by the presence of endometrial glandular epithelial and stromal cells growing in the extra-uterine environment. The disease afflicts 10%–15% of menstruating women causing debilitating pain and infertility. Endometriosis appears to affect every part of a woman’s reproductive system including ovarian function, oocyte quality, embryo development and implantation, uterine function and the endocrine system choreographing the reproductive process and results in infertility or spontaneous pregnancy loss. Current treatments are laden with menopausal-like side effects and many cause cessation or chemical alteration of the reproductive cycle, neither of which is conducive to achieving a pregnancy. However, despite the prevalence, physical and psychological tolls and health care costs, a cure for endometriosis has not yet been found. We hypothesize that endometriosis causes infertility via multifaceted mechanisms that are intricately interwoven thereby contributing to our lack of understanding of this disease process. Identifying and understanding the cellular and molecular mechanisms responsible for endometriosis-associated infertility might help unravel the confounding multiplicities of infertility and provide insights into novel therapeutic approaches and potentially curative treatments for endometriosis.

Disturbed balance between phase I and II metabolizing enzymes in ovarian endometriosis: a source of excessive hydroxy-estrogens and ROS?

Oxidative metabolism of estrogens was studied in 31 ovarian endometriosis and 29 normal endometrium samples, by qPCR. Expression was monitored for genes encoding five estrogen hydroxylating, five hydroxy (OH)-estrogen conjugating, and three estrogen quinone detoxifying enzymes. CYP1B1, COMT, NQO1, and GSTP1 protein levels were determined using Western blotting and immunohistochemistry staining. Increased expression of CYP1A1, CYP3A7 and COMT, and higher levels of MB-COMT were seen in endometriosis, as compared to normal endometrium. Expression of CYP1B1, CYP3A5, SULT1A1 and NQO2 was unchanged, with comparable CYP1B1 protein levels. Expression of SULT1E1, SULT2B1, UGT2B7, NQO1, and GSTP1 was decreased. Three NQO1 isoforms were detected; NQO1c appears to be endometriosis-specific. Our data indicate a disturbed balance between phase I and II metabolizing enzymes in endometriosis, potentially leading to excessive OH-estrogen and altered ROS formation, and stimulation of proliferation of ectopic endometrium. This is the first report on disturbed expression of estrogen oxidative metabolism genes in ovarian endometriosis.

Endometriosis, a disease of the macrophage

Endometriosis, a common cause of pelvic pain and female infertility, depends on the growth of vascularized endometrial tissue at ectopic sites. Endometrial fragments reach the peritoneal cavity during the fertile years: local cues decide whether they yield endometriotic lesions. Macrophages are recruited at sites of hypoxia and tissue stress, where they clear cell debris and heme-iron and generate pro-life and pro-angiogenesis signals. Macrophages are abundant in endometriotic lesions, where are recruited and undergo alternative activation. In rodents macrophages are required for lesions to establish and to grow; bone marrow-derived Tie-2 expressing macrophages specifically contribute to lesions neovasculature, possibly because they concur to the recruitment of circulating endothelial progenitors, and sustain their survival and the integrity of the vessel wall. Macrophages sense cues (hypoxia, cell death, iron overload) in the lesions and react delivering signals to restore the local homeostasis: their action represents a necessary, non-redundant step in the natural history of the disease. Endometriosis may be due to a misperception of macrophages about ectopic endometrial tissue. They perceive it as a wound, they activate programs leading to ectopic cell survival and tissue vascularization. Clearing this misperception is a critical area for the development of novel medical treatments of endometriosis, an urgent and unmet medical need.

Raf-1 levels determine the migration rate of primary endometrial stromal cells of patients with endometriosis

Endometriosis is a disease characterized by the localization of endometrial tissue outside the uterine cavity. The differences observed in migration of human endometrial stromal cells (hESC) obtained from patients with endometriosis versus healthy controls were proposed to correlate with the abnormal activation of Raf-1/ROCKII signalling pathway. To evaluate the mechanism by which Raf-1 regulates cytoskeleton reorganization and motility, we used primary eutopic (Eu-, n = 16) and ectopic (Ec-, n = 8; isolated from ovarian cysts) hESC of patients with endometriosis and endometriosis-free controls (Co-hESC, n = 14). Raf-1 siRNA knockdown in Co- and Eu-hESC resulted in contraction and decreased migration versus siRNA controls. This phenotype was reversed following the re-expression of Raf-1 in these cells. Lowest Raf-1 levels in Ec-hESC were associated with hyperactivated ROCKII and ezrin/radixin/moesin (E/R/M), impaired migration and a contracted phenotype similar to Raf-1 knockdown in Co- and Eu-hESC. We further show that the mechanism by which Raf-1 mediates migration in hESC includes direct myosin light chain phosphatase (MYPT1) phosphorylation and regulation of the levels of E/R/M, paxillin, MYPT1 and myosin light chain (MLC) phosphorylation indirectly via the hyperactivation of ROCKII kinase. Furthermore, we suggest that in contrast to Co-and Eu-hESC, where the cellular Raf-1 levels regulate the rate of migration, the low cellular Raf-1 content in Ec-hESC, might ensure their restricted migration by preserving the contracted cellular phenotype. In conclusion, our findings suggest that cellular levels of Raf-1 adjust the threshold of hESC migration in endometriosis.

Possible involvement of nerve growth factor in dysmenorrhea and dyspareunia associated with endometriosis

Nerve growth factor (NGF) has been recently proposed as one of the key factors responsible not only for promotion of nerve fiber growth but also for the onset and maintenance of pain in a variety of diseases. The aim of this study was to investigate the role of NGF in the pelvic pain associated with endometriosis. Tissue and peritoneal fluid samples were collected from 95 women with laparoscopically and histopathologically confirmed endometriosis and 59 control women without endometriosis. Expression levels of NGF mRNA and protein were examined using real-time RT-PCR and immunohistochemistry, respectively. Concentration of NGF in the peritoneal fluid (PF-NGF) was measured using ELISA. The degree of dyspareunia and dysmenorrhea was evaluated using a verbal rating scale. Real-time RT-PCR analysis revealed that NGF mRNA was significantly more abundant in the ovarian endometriomas and peritoneal endometriosis than in the normal control endometrium. Immunohistochemical analyses demonstrated that NGF was prominently expressed and preferentially localized to the glands of the ovarian endometriomas and peritoneal endometriosis, whereas it was only weakly detectable in the normal endometrium. Although PF-NGF was undetectable in some normal subjects and endometriosis patients, elevated PF-NGF in the peritoneal fluid was more frequently observed in endometriosis patients with severe pain than in those with less severe pain. Our results suggest that NGF produced locally in the peritoneal cavity may be involved in the generation of endometriosis-associated pelvic pain.

Intraoperative detection of subtle endometriosis: a novel paradigm for detection and treatment of pelvic pain associated with the loss of peritoneal integrity

Endometriosis is a common disease affecting 40 to 70% of reproductive-aged women with chronic pelvic pain (CPP) and/or infertility. The purpose of this study was to demonstrate the use of a blue dye (methylene blue) to stain peritoneal surfaces during laparoscopy (L/S) to detect the loss of peritoneal integrity in patients with pelvic pain and suspected endometriosis. Forty women with CPP and 5 women without pain were evaluated in this pilot study. During L/S, concentrated dye was sprayed onto peritoneal surfaces, then aspirated and rinsed with Lactated Ringers solution. Areas of localized dye uptake were evaluated for the presence of visible endometriotic lesions. Areas of intense peritoneal staining were resected and some fixed in 2.5% buffered gluteraldehyde and examined by scanning (SEM) electron microscopy. Blue dye uptake was more common in women with endometriosis and chronic pelvic pain than controls (85% vs. 40%). Resection of the blue stained areas revealed endometriosis by SEM and loss of peritoneal cell-cell contact compared to normal, non-staining peritoneum. Affected peritoneum was associated with visible endometriotic implants in most but not all patients. Subjective pain relief was reported in 80% of subjects. Based on scanning electron microscopy, we conclude that endometrial cells extend well beyond visible implants of endometriosis and appear to disrupt the underlying mesothelium. Subtle lesions of endometriosis could therefore cause pelvic pain by disruption of peritoneal integrity, allowing menstrual or ovulatory blood and associated pain factors access to underlying sensory nerves. Complete resection of affected peritoneum may provide a better long-term treatment for endometriosis and CPP. This simple technique appears to improve detection of subtle or near invisible endometriosis in women with CPP and minimal visual findings at L/S and may serve to elevate diagnostic accuracy for endometriosis at laparoscopy.

Pain and endometriosis: Etiology, impact, and therapeutics

The association of pain and endometriosis was recognized with the first definitive published reports of this disorder. Unfortunately, the precise etiologies and pathways leading to nociception and pain symptoms in endometriosis remain poorly understood, and as a result, effective therapeutic interventions are lacking with consequent profound effects on affected women's quality of life. In this opinion paper we summarize selected proceedings presented at the 28th Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Istanbul, Turkey, and review the clinical and translational evidence of chronic pain, neurogenesis, and the pernicious impact of dyspareunia on women with symptomatic endometriosis. The effectiveness of medical treatments is critically assessed and the findings indicate that good therapeutic options are available with extant medications effective in some sub-groups of women with endometriosis, many of which are affordable globally. Nevertheless, new management strategies and drugs need to be developed to increase the options of all afflicted women to minimize and ideally eradicate painful symptoms of endometriosis. However, only by elucidating distinctions among sub-groups with specific symptoms, suggesting different mechanisms, are we likely to derive truly successful therapeutic strategies.

Functional analyses of endometriosis-related polymorphisms in the estrogen synthesis and metabolism-related genes

Endometriosis is determined by genetic factors, and the prevalence of genetic polymorphisms varies greatly depending on the ethnic group studied. The objective of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) of 9 genes involved in estrogen biosynthesis and metabolism and the risks of endometriosis. Three hundred patients with endometriosis and 337 non-endometriotic controls were recruited. Thirty four non-synonymous SNPs, which change amino acid residues, were analyzed using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS). The functions of SNP-resulted amino acid changes were analyzed using multiple web-accessible databases and phosphorylation predicting algorithms. Among the 34 NCBI-listed SNPs, 22 did not exhibit polymorphism in this study of more than 600 Taiwanese Chinese women. However, homozygous and heterozygous mutants of 4 SNPs - rs6165 (genotype GG+GA, 307(Ala/Ala)+307(Ala/Thr)) of FSHR, rs 6166 (genotype GG+GA, 680(Ser/Asn)+680(Ser/Ser)) of FSHR, rs2066479 (genotype AA+AG, 289(Ser/Ser)+289(Ser/Gly)) of HSD17B3 and rs700519 (genotype TT+TC, 264(Cys/Cys)+264(Cys/Arg)) of CYP19, alone or in combination, were significantly associated with decreased risks of endometriosis. Bioinformatics results identified 307(Thr) of FSHR to be a site for O-linked glycosylation, 680(Ser) of FSHR a phosphorylated site by protein kinase B, and 289(Ser) of HSD17B3 a phosphorylated site by protein kinase B or ribosomal protein S6 kinase 1. Results of this study suggest that non-synonymous polymorphisms of FSHR, HSD17B3 and CYP19 genes may modulate the risk of endometriosis in Taiwanese Chinese women. Identification of the endometrosis-preferential non-synonymous SNPs and the conformational changes in those proteins may pave the way for the development of more disease-specific drugs.

Migration of cells from experimental endometriosis to the uterine endometrium

Endometriosis is the estrogen-dependent growth of endometrial tissue outside the uterus. Endometriosis has an effect on the eutopic endometrium; however, the nature of the cellular or molecular signal from the lesion to the uterus is unknown. Here we demonstrate that cells migrate from endometriosis to eutopic endometrium. Experimental endometriosis was established by transplanting endometrial tissue from green fluorescent protein (GFP) mice to the peritoneal cavity of DS-Red mice. Immunofluorescence (IF) identified cells from the ectopic lesions in the uterus. The eutopic endometrial cells were sorted by fluorescence activated cell sorting, and the GFP(+)/DS-Red(-) population was characterized using microarray analysis. The results of cell sorting as well as the array results were confirmed by quantitative PCR and IF. GFP(+)/DS-red(-)/Cd45(-) cells were identified in the eutopic endometrium of mice with experimental endometriois (∼1.8%) and not in controls. Global gene expression profiling of these cells showed absence of leukocyte and increased expression of pan-epithelial markers in the uterine GFP(+) cells. Moreover, GFP(+) cells showed up-regulation of Wnt7A expression and 17 other genes associated with the Wingless pathway. Several genes that are associated with epithelial-to-mesenchymal transition were also highly differentially expressed in GFP(+) cells. IF confirmed the presence of the GFP(+)/CD45(-)/Wnt7a(+)/cytokeritin(+) cells in the endometrium of endometriotic animals, and not in controls. Cells from endometriotic lesions are capable of migrating to the eutopic endometrium. The ectopic expression of Wnt7A suggests a possible mechanism by which ectopic lesions affect the eutopic endometrium and interfere with embryo implantation and fertility.

Pelvic pain in women with ovarian endometrioma is mostly associated with coexisting peritoneal lesions

STUDY QUESTION

Is the occurrence of pelvic pain in women with ovarian endometrioma associated with coexisting peritoneal lesions (PLs)?

SUMMARY ANSWER

Pelvic pain in women with ovarian endometrioma is usually associated with coexisting PLs. An increased tissue inflammatory reaction with elevated prostaglandin (PG) production may be responsible for the generation of pain.

WHAT IS KNOWN ALREADY

Severe pelvic pain in women with ovarian endometrioma is reported to be associated with deeply infiltrating endometriosis. However, information on pelvic pain in women with ovarian endometriosis with and without coexistent peritoneal superficial lesions is limited.

STUDY DESIGN, SIZE AND DURATION

Retrospective clinical study with case-controlled biological research using prospectively collected tissue samples derived from women with and without endometriosis and their retrospective evaluation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We performed a retrospective cohort study conducted in 2988 cases who had laparoscopic surgery for indications of ectopic pregnancy, tubal infertility and other benign gynecologic diseases. We analyzed the occurrence of pelvic pain in the cases with ovarian endometrioma according to the distribution of coexisting PLs and pattern of intrapelvic adhesions. Inflammatory reaction of eutopic and ectopic endometria was measured by immunoreaction to macrophage marker, CD68. The tissue expression of cyclooxygenase (COX) 2 was examined by immunohistochemistry and tissue concentrations of PG F2α were measured by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the 2988 surgical cases, 350 (11.7%) were found to have ovarian endometrioma at laparoscopy. Coexisting PLs were present in 269 of these women and in this group 85.4% of cases experienced pelvic pain and 14.6% had no pain. In contrast, among the 81 women with ovarian endometrioma only, 38.3% cases experienced pelvic pain and 61.7% cases had no pain and the difference between the groups was statistically significant (P < 0.01). The infiltration of CD68-immunoreactive macrophages was significantly higher in the eutopic and ectopic endometria of women with peritoneal endometriosis than in ovarian endometrioma. The tissue expression of COX2 and levels of PGF2α were significantly higher in both the eutopic and ectopic endometria derived from women with peritoneal endometriosis than in similar tissues derived from women with ovarian endometrioma.

LIMITATIONS, REASONS FOR CAUTIONS

Lack of evaluation in the detection of general or disseminated deeply infiltrating endometriosis in the pelvic cavity could be a bias or limitation in this study. Further multicenter prospective studies are needed to strengthen our current findings.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings may provide some new insights to understand the physiopathology of pelvic pain in women with ovarian cystic endometriosis and may hint at proper surgical manipulation to prevent the recurrence of pelvic pain in these women.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Sports, Culture, Science and Technology of Japan. There is no conflict of interest related to this study.

TRIAL REGISTRATION NUMBER

Not applicable.