Coelomic metaplasia theory of endometriosis: evidence from in vivo studies and an in vitro experimental model

The role of innate and adaptive immunity in endometriosis

The innate and adaptive immune systems are the two key branches that determine host protection at all mucosal surfaces in human body, including the female reproductive tract. The pattern recognition receptors within the host that recognize pathogen-associated molecular patterns are expressed on the cells of the innate immune system. Rapidly reactive, theinnate immune system, responds immediately to the presence of infectious or other non-self agents, thereby launching an inflammatory response to protect the host until the activation of slower adaptive immune system. Macrophages, dendritic cells, and toll-like receptors are integral components of the innate immune system. In contrast, T-helper (Th1/Th2/Th17) cells and regulatory T (Treg) cells are the primary components of adaptive immune system. Studies showed that the growth and progression of endometriosis continue even in unilateral ovariectomized animal suggesting that besides ovarian steroid hormones, the growth of endometriosis could be regulated by innate/adaptive immune systems in pelvic environment. Recent reports demonstrated a potential role of Th1/Th2/Th17/Treg cells either individually or collectively in the initiation, maintenance, and progression of endometriosis. Herewe review the fundamental knowledge of innate and adaptive immunity and elaborate the role of innate and adaptive immunity in endometriosis based on both human and experimental data.

Mood disorders influencing endometriosis and adenomyosis: Mendelian randomisation study

BACKGROUND

Many studies have found an association between mood-disorder-related traits and endometriosis and adenomyosis. However, the cause-effect relationship remains unclear.

AIMS

We conducted Mendelian randomisation analyses to evaluate any causal relationship between mood disorders and endometriosis as well as different sites of endometriosis.

METHOD

Summary-level statistics for mood-disorder-related traits and endometriosis (8288 cases, 68 969 controls) in European populations were derived from large-scale data-sets of genome-wide association studies. A two-sample Mendelian randomisation was performed using the inverse-variance weighted and weight median methods. Further sensitivity analyses, including heterogeneity, pleiotropy and leave-one-out analyses, were conducted to test the consistency of the results.

RESULTS

Genetically determined mood swings (odds ratio = 2.557, 95% CI: 1.192-5.483, P = 0.016) and major depression (odds ratio = 1.233, 95% CI: 1.019-1.493, P = 0.031) were causally associated with an increased risk of endometriosis. Mood swings (odds ratio = 4.238, 95% CI: 1.194-15.048, P = 0.025) and major depression (odds ratio = 1.512, 95% CI: 1.052-2.173, P = 0.025) were also causally associated with the risk of adenomyosis. Sensitivity analyses confirmed the reliability of the results.

CONCLUSIONS

Our results suggest that mood-disorder-related traits increase the risk of endometriosis and adenomyosis. This study provides new insights into the potential pathogenesis of endometriosis and adenomyosis, and highlights the importance of preventing endometriosis and adenomyosis in patients with mood-disorder-related traits.

Identification of potential diagnostic biomarkers and therapeutic targets for endometriosis based on bioinformatics and machine learning analysis

PURPOSE

Endometriosis (EMs) is a major gynecological condition in women. Due to the absence of definitive symptoms, its early detection is very challenging; thus, it is crucial to find biomarkers to ease its diagnosis and therapy. Here, we aimed to identify potential diagnostic and therapeutic targets for EMs by constructing a regulatory network and using machine learning approaches.

METHODS

Three Gene Expression Omnibus (GEO) datasets were merged, and differentially expressed genes (DEGS) were identified after preprocessing steps. Using the DEGs, a transcription factor (TF)-mRNA-miRNA regulatory network was constructed, and hub genes were detected based on four different algorithms in CytoHubba. The hub genes were used to build a GaussianNB diagnostic model and also in docking analysis that were performed using Discovery Studio and AutoDock Vina software.

RESULTS

A total of 119 DEGs were identified between EMs and non-EMs samples. A regulatory network consisting of 52 mRNAs, 249 miRNAs, and 37 TFs was then constructed. The diagnostic model was introduced using the hub genes selected from the network (GATA6, HMOX1, HS3ST1, NFASC, and PTGIS) that its area under the curve (AUC) was 0.98 and 0.92 in the training and validation cohorts, respectively. Based on docking analysis, two chemical compounds, rofecoxib and retinoic acid, had potential therapeutic effects on EMs.

CONCLUSION

In conclusion, this study identified potential diagnostic and therapeutic targets for EMs which demand more experimental confirmations.

Circulating CD200 is increased in the secretory phase of women with endometriosis as is endometrial mRNA, and endometrial stromal cell CD200R1 is increased in spite of reduced mRNA

PROBLEM

Estrogen-dependent extrauterine implantation and growth of menstrual endometrial tissue affects roughly 10% of reproductive age women and depends on suppression of local innate immune defenses to prevent ectopic tissue rejection. Immunohistochemistry has shown the immune check-point inhibitor CD200 which can suppress rejection is expressed in eutopic endometrium and in ectopic deposits. Soluble CD200 accumulated in venules draining eutopic and ectopic endometrium of endometriosis cases in the secretory phase but not proliferative phase of the menstrual cycle, and should be increased in the circulation.

METHOD OF STUDY

Sera from endometriosis and non-endometriosis controls were tested by ELISA for CD200. Endometrial CD200, CD200R1 and CD200R2 mRNA in eutopic was quantified by RT-PCR and localized by in situ hybridization. CD200R1 protein was quantified by immunohistochemistry.

RESULTS

Secretory phase serum CD200 was elevated in women with endometriosis compared to controls. Serum CD200 correlated with matched endometrial CD200 mRNA levels. Expression of mRNA for CD200R1 which signals immune suppression was decreased whereas mRNA for the CD200R2 activating receptor was increased. In situ staining of CD200R1 and CD200R2 mRNA showed both receptors were expressed and the fraction of CD200R that is CD200R1 was reduced in secretory and menstrual phase endometriosis endometrium consistent with the RT-PCR result. By contrast, CD200R1 protein and CD200R1 fraction of total CD200R protein were increased in endometriosis.

CONCLUSIONS

Failure to suppress circulating CD200 levels in the secretory phase had an 87% specificity and 90% sensitivity for endometriosis. CD200 and increased CD200R1 expression may facilitate development of ectopic deposits by suppressing rejection mechanisms.

A Review of Urinary Tract Endometriosis

PURPOSE OF REVIEW

To describe the presenting signs and symptoms of patients with urinary tract endometriosis (UTE), appropriate workup, and to review medical and surgical therapies for symptom palliation and definitive management.

RECENT FINDINGS

UTE is a condition that clinicians should maintain a high index of suspicion for, as symptoms can be easily misdiagnosed from other causes. Surgical resection of implants appears to offer safe and durable symptom relief. Urinary tract endometriosis may present with symptoms overlapping with interstitial cystitis, nephrolithiasis, bladder overactivity, or recurrent urinary tract infections, and may or may not be cyclical in nature. Cyclical gross hematuria is considered pathognomonic, though final diagnosis must be made after a pathologic review. Without proper diagnosis and treatment, consequences such as silent renal loss from asymptomatic obstruction may result. After the diagnosis is made, initial therapy can be undertaken with hormonal treatment to palliate symptoms (most commonly in the form of combined oral contraceptives), followed by surgical resection for a definitive treatment option.

Genomic Evidence Supports the Recognition of Endometriosis as an Inflammatory Systemic Disease and Reveals Disease-Specific Therapeutic Potentials of Targeting Neutrophil Degranulation

Background

Endometriosis, classically viewed as a localized disease, is increasingly recognized as a systemic disease with multi-organ effects. This disease is highlighted by systemic inflammation in affected organs and by high comorbidity with immune-mediated diseases.

Results

We provide genomic evidence to support the recognition of endometriosis as an inflammatory systemic disease. This was achieved through our genomics-led target prioritization, called ‘END’, that leverages the value of multi-layered genomic datasets (including genome-wide associations in disease, regulatory genomics, and protein interactome). Our prioritization recovered existing proof-of-concept therapeutic targeting in endometriosis and outperformed competing prioritization approaches (Open Targets and Naïve prioritization). Target genes at the leading prioritization revealed molecular hallmarks (and possibly the cellular basis as well) that are consistent with systemic disease manifestations. Pathway crosstalk-based attack analysis identified the critical gene AKT1. In the context of this gene, we further identified genes that are already targeted by licensed medications in other diseases, such as ESR1. Such analysis was supported by current interests targeting the PI3K/AKT/mTOR pathway in endometriosis and by the fact that therapeutic agents targeting ESR1 are now under active clinical trials in disease. The construction of cross-disease prioritization map enabled the identification of shared and distinct targets between endometriosis and immune-mediated diseases. Shared target genes identified opportunities for repurposing existing immunomodulators, particularly disease-modifying anti-rheumatic drugs (such as TNF, IL6 and IL6R blockades, and JAK inhibitors). Genes highly prioritized only in endometriosis revealed disease-specific therapeutic potentials of targeting neutrophil degranulation – the exocytosis that can facilitate metastasis-like spread to distant organs causing inflammatory-like microenvironments.

Conclusion

Improved target prioritization, along with an atlas of in silico predicted targets and repurposed drugs (available at https://23verse.github.io/end), provides genomic insights into endometriosis, reveals disease-specific therapeutic potentials, and expands the existing theories on the origin of disease.

Thoracic Endometriosis: A Presentation of an Uncommon Disease in a Black African Woman

Introduction. Endometriosis is defined as a chronic gynecologic disease which is characterized by the presence of endometrial glands and stroma in anatomical sites and organs outside the uterine cavity. The exact prevalence of endometriosis is difficult to determine because many women remain asymptomatic. However, endometriosis affects about 10% to 15% of women. Thoracic endometriosis (TES) is the most common endometriosis outside the abdominopelvic cavity. It refers to endometriosis within the thoracic cavity including the lung parenchyma, diaphragm, and pleural surfaces. It can manifest as catamenial chest pain, pneumothorax, hemoptysis, hemothorax, catamenial haemoptysis, and pulmonary nodules. Case Summary. A 39-years-old married female presented with recurrent right-sided chest pain of 22 years duration, recurrent cough of more than 20 years and progressive breathlessness of a month duration. The chest pain is pleuritic, and it often starts few days to the onset of her menses and lasts throughout menstrual flow only to abate after the stoppage of menstrual bleeding. Cough was unproductive, paroxysmal often worse with worsening chest pain. It disappears after the end of menstrual bleed. Breathlessness was initially on mild to moderate exertion before progressing to occasional breathlessness at rest. No history of orthopnea, paroxysmal nocturnal dyspnea, and pedal swelling was found. Over the years, she had presented to several clinics where she was said to have menstrual pain referred to the chest. Conclusion. Diagnosis of extrapelvic endometriosis can be challenging and delayed because it presents in a myriad of ways and in some cases, it may be difficult to link symptoms and the menstrual cycle.

Current Knowledge on Endometriosis Etiology: A Systematic Review of Literature

Objective

To review the mechanisms of endometriosis development, including those related to epigenetic mutations, cellular dysregulation, inflammatory processes, and oxidative stress.

Methods

A systematic literature review regarding current aspects of endometriosis etiology, genesis and development was performed using the PubMed, Google Scholar, and eLibrary databases. Keywords included endometriosis, etiology, development, genesis, associations and mechanisms. A multilingual search was performed.

Results

Several mechanisms underline the pathophysiological pathways for endometriosis development. Epigenetic mutations, external and internal influences, and chronic conditions have a significant impact on endometriosis development, survival and regulation. Several historically valid theories on endometriosis development were discussed, as well as updated findings.

Conclusion

Despite recent advances, fundamental problems in understanding endometriosis remain unresolved. The identification of unknown circulating epithelial progenitors or stem cells that are responsible for epithelial growth in both the endometrium and endometriotic foci seems to be the next step in solving these questions.

How Does Endometriosis Lead to Ovarian Cancer? The Molecular Mechanism of Endometriosis-Associated Ovarian Cancer Development

Numerous epidemiological and histopathological studies support the notion that clear cell and endometrioid carcinomas derive from ovarian endometriosis. Accordingly, these histologic types are referred to as "endometriosis-associated ovarian cancer" (EAOC). Although the uterine endometrium is also considered an origin of endometriosis, the molecular mechanism involved in transformation of the uterine endometrium to EAOC via ovarian endometriosis has not yet been clarified. Recent studies based on high-throughput sequencing technology have revealed that cancer-associated gene mutations frequently identified in EAOC may exist in the normal uterine endometrial epithelium and ovarian endometriotic epithelium. The continuum of genomic alterations from the uterine endometrium to endometriosis and EAOC has been described, though the significance of cancer-associated gene mutations in the uterine endometrium or endometriosis remains unclear. In this review, we summarize current knowledge regarding the molecular characteristics of the uterine endometrium, endometriosis, and EAOC and discuss the molecular mechanism of cancer development from the normal endometrium through endometriosis in an effort to prevent EAOC.

Endometriotic lung cyst causing catamenial hemoptysis; a case report and review of literature

We report a rare case of an endometriotic lung cyst in a 47-year woman with recurrent catamenial hemoptysis. Chest computed tomography (CT) obtained outside the menstruation in October 2019 revealed a cystic lesion (2.5 cm) located in the right inferior lobe near the distal esophagus and the inferior pulmonary vein. Compared to CT abdomen in May 2019, this lesion had increased with a larger volume and a thicker wall. An endometrial lung cyst was suspected as episodes of hemoptysis no longer occurred after initiating hormonal treatment with nomegestrol acetate. Exploratory video-assisted thoracoscopic surgery with wedge resection of the cyst was performed. Histopathologic examination confirmed the diagnosis of an endometriotic cystic lesion. Postoperative course was uneventful with no further symptoms since then.

Endometriosis is a chronic systemic disease: clinical challenges and novel innovations

Endometriosis is a common disease affecting 5-10% of women of reproductive age globally. However, despite its prevalence, diagnosis is typically delayed by years, misdiagnosis is common, and delivery of effective therapy is prolonged. Identification and prompt treatment of endometriosis are essential and facilitated by accurate clinical diagnosis. Endometriosis is classically defined as a chronic, gynaecological disease characterised by endometrial-like tissue present outside of the uterus and is thought to arise by retrograde menstruation. However, this description is outdated and no longer reflects the true scope and manifestations of the disease. The clinical presentation is varied, the presence of pelvic lesions is heterogeneous, and the manifestations of the disease outside of the female reproductive tract remain poorly understood. Endometriosis is now considered a systemic disease rather than a disease predominantly affecting the pelvis. Endometriosis affects metabolism in liver and adipose tissue, leads to systemic inflammation, and alters gene expression in the brain that causes pain sensitisation and mood disorders. The full effect of the disease is not fully recognised and goes far beyond the pelvis. Recognition of the full scope of the disease will facilitate clinical diagnosis and allow for more comprehensive treatment than currently available. Progestins and low-dose oral contraceptives are unsuccessful in a third of symptomatic women globally, probably as a result of progesterone resistance. Oral gonadotropin-releasing hormone (GnRH) antagonists constitute an effective and tolerable therapeutic alternative when first-line medications do not work. The development of GnRH antagonists has resulted in oral drugs that have fewer side-effects than other therapies and has allowed for rapid movement between treatments to optimise and personalise endometriosis care. In this Review, we discuss the latest understanding of endometriosis as a systemic disease with multiple manifestations outside the parameters of classic gynaecological disease.

Changes in the Expression of TBP-2 in Response to Histone Deacetylase Inhibitor Treatment in Human Endometrial Cells

Histone deacetylase inhibitors (HDACi) induce apoptosis preferentially in cancer cells by caspase pathway activation and reactive oxygen species (ROS) accumulation. Suberoylanilide hydroxamic acid (SAHA), a HDACi, increases apoptosis via altering intracellular oxidative stress through thioredoxin (TRX) and TRX binding protein-2 (TBP-2). Because ROS accumulation, as well as the redox status determined by TBP-2 and TRX, are suggested as possible mechanisms for endometriosis, we queried whether SAHA induces apoptosis of human endometrial cells via the TRX–TBP-2 system in endometriosis. Eutopic endometrium from participants without endometriosis, and ectopic endometrium from patients with endometriosis, was obtained surgically. Human endometrial stromal cells (HESCs) and Ishikawa cells were treated with SAHA and cell proliferation was assessed using the CCK-8 assay. Real-time PCR and Western blotting were used to quantify TRX and TBP-2 mRNA and protein expression. After inducing oxidative stress, SAHA was applied. Short-interfering TRX (SiTRX) transfection was performed to see the changes after TRX inhibition. The mRNA and protein expression of TBP-2 was increased with SAHA concentrations in HESCs significantly. The mRNA TBP-2 expression was decreased after oxidative stress, upregulated by adding 2.5 μM of SAHA. The TRX/TBP-2 ratio decreased, apoptosis increased significantly, and SiTRX transfection decreased with SAHA. In conclusion, SAHA induces apoptosis by modulating the TRX/TBP-2 system, suggesting its potential as a therapeutic agent for endometriosis.

Endometriosis and ovarian cancer risk, an epigenetic connection

Endometriosis is a gynecological disorder that affects 176 million women worldwide and 1 in 10 females in the United States. Endometriosis most often affects women of child-bearing age, with most going undiagnosed. Endometriosis also shares many characteristics common to invasive cancer and has been known to be associated with epithelial ovarian cancer. Ovarian cancer is the 11^th most common cancer among women and over 22,000 new cases will be diagnosed within the next year. Women most commonly diagnosed with this cancer are between the ages of 55–64 years, outside the range of the age of women affected with endometriosis. While no known cause of either disease has been established, epigenetic regulation is thought to play a major role in both. This review focuses on epigenetic changes that occur within each individual disease as well as those that are similar in both, suggesting a possible etiological link between the two diseases.

Thoracic Endometriosis Syndrome: A Review of Diagnosis and Management

Background:

Endometriosis is characterized by the presence of endometrial-like glands and stroma outside the uterine cavity and is believed to affect 6%–10% of reproductive-age women. Endometriosis within the lung parenchyma or on the diaphragm and pleural surfaces produces a range of clinical and radiological manifestations. This includes catamenial pneumothorax, hemothorax, hemoptysis, and pulmonary nodules, resulting in an entity known as thoracic endometriosis syndrome (TES).

Database:

Computerized searches of MEDLINE and PubMed were conducted using the key words “thoracic endometriosis,” “catamenial pneumothorax,” “catamenial hemothorax,” and “catamenial hemoptysis.” References from identified sources were manually searched to allow for a thorough review.

Conclusion:

TES can produce incapacitating symptoms for some patients. Symptoms of TES are nonspecific, so a high degree of clinical suspicion is warranted. Medical management represents the first-line treatment approach. When this fails or is contraindicated, definitive surgical treatment for cases of suspected TES uses a combined video laparoscopy performed by a gynecologic surgeon and video-assisted thoracoscopic surgery performed by a thoracic surgeon. Postoperative hormonal suppression may further reduce disease recurrence.

Catamenial Pneumothorax, a Commonly Misdiagnosed Thoracic Condition: Multicentre Experience and Audit of a Small Case Series With Review of the Literature

BACKGROUND

Catamenial pneumothorax (CP) is an unusual condition affecting premenopausal women and commonly misdiagnosed as simple pneumothorax. It is characterised by its recurrence between the day before and within 72 hours after the onset of menstruation. It has been associated with thoracic endometriosis but the aetiology is not well understood and there is no unified agreement for its optimal management. The aim of this study is to determine the incidence of CP in surgical patients and the results of their treatment.

METHODS

Females between the ages of 30 to 50 years with a diagnosis of pneumothorax, admitted for surgery over a 10-year period in four different hospitals were retrospectively reviewed for evidence of CP. An audit of surgical and medical management of the patients with CP and their short to midterm outcomes was performed in addition to a systemic review of the literature on CP.

RESULT

A total of 120 premenopausal female patients with a diagnosis of pneumothorax were admitted for Video Assisted Thoracoscopic (VAT) surgery and five women (4.1%) with a mean age of 42.6 years were diagnosed to have CP through surgical and histological findings. The first case was diagnosed 5 years ago and the last three within recent 12 months after the changes in surgical practices of inspecting diaphragmatic surface in suspected cases of CP. Four patients underwent diaphragmatic plication and one patient had a pleural biopsy. All patients underwent talc pleurodesis and hormone therapy in the postoperative period. Short to midterm (mean follow-up period of 25.2 months) results of the patients with CP were encouraging.

CONCLUSIONS

It is possible that many of the cohort of premenopausal female patients presenting with recurrent pneumothorax are misdiagnosed as spontaneous pneumothorax (SP) because routine inspection of the diaphragmatic surface is not often performed. A thorough menstrual history and its temporal relation to pneumothorax onset should be assessed on every woman presenting with recurrent pneumothorax and intraoperative exploration of diaphragmatic surface should be performed in the patients with high suspicion of CP as the patients diagnosed with CP have a good outcome with surgery and hormone therapy.

Appendectomy Scar Endometriosis: A Case Report

Scar endometriosis is one of the rare cases of surgery, which specifically occurs in gynecological surgeries. It is important to do a correct diagnosis in such rare cases to have an efficient treatment. The disease is commonly observed in child-bearing women with clinical manifestations such as acute abdomen or chronic and cyclic pelvic pain. Herein we reported a case of appendectomy scar endometriosis.

Molecular and Cellular Pathogenesis of Endometriosis

BACKGROUND

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

OBJECTIVE

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

RESULTS AND CONCLUSION

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

Endometrial Stromal and Epithelial Cells Exhibit Unique Aberrant Molecular Defects in Patients With Endometriosis

CONTEXT

Endometriosis is a chronic inflammatory disease that causes pain and infertility in women of reproductive age.

OBJECTIVE

To investigate the pathologic pathways in endometrial stromal and epithelial cells that contribute to the manifestation of endometriosis.

DESIGN

In vitro cellular and molecular analyses of isolated eutopic endometrial stromal and epithelial cells.

METHODS

Eutopic stromal and epithelial cells from endometriotic and normal patients were isolated by fluorescence-activated cell sorting for paired sibling RNA sequencing and microRNA microarray. Aberrant pathways were identified using ingenuity pathway analysis networks and confirmed with in vitro modulation of the affected pathways in stromal and epithelial cell cultures.

RESULTS

Both stromal versus epithelial cell types and paired endometriotic versus normal samples exhibited distinct hierarchical clustering. Compared to normal samples, there were 151 and 215 differentially expressed genes in the endometriotic stromal and epithelial populations, respectively, and concomitantly 9 and 16 differentially expressed microRNAs. Overall, endometriotic stromal and epithelial cells revealed distinct defects. In endometriotic stromal cells, key decidualization genes Zinc finger E-box Binding protein 1 (ZEB1), Heart And Neural crest Derivatives expressed 2 (HAND2), WNT4, and Interleukin 15 (IL-15) were found to be downregulated and Periostin (POSTN) and Matrix Metallopeptidase 7 (MMP7) were upregulated. Specifically, ZEB1 was downregulated in stromal cells by aberrant elevation in miR-200b. In contrast, ZEB1 was found to be upregulated in endometriotic epithelial cells through associated upregulation of transforming growth factor β1 (TGFβ1), inducer of the TGFβ1-Bone Morphogenetic Protein 2 (BMP2)-MMP2-Prostaglandin-endoperoxide Synthase 2 (COX2)-ZEB1 pathway, which activates epithelial-mesenchymal transition.

CONCLUSION

Manifestation of endometriosis involves dysregulation of unique molecular pathways within the diseased endometrial stromal and epithelial cells in the endometrium. Targeting the cell type-specific defects may offer a novel approach to treating endometriosis.

Integrative Analysis Reveals Regulatory Programs in Endometriosis

Endometriosis is a common gynecological disease found in approximately 10% of reproductive-age women. Gene expression analysis has been performed to explore alterations in gene expression associated with endometriosis; however, the underlying transcription factors (TFs) governing such expression changes have not been investigated in a systematic way. In this study, we propose a method to integrate gene expression with TF binding data and protein-protein interactions to construct an integrated regulatory network (IRN) for endometriosis. The IRN has shown that the most regulated gene in endometriosis is RUNX1, which is targeted by 14 of 26 TFs also involved in endometriosis. Using 2 published cohorts, GSE7305 (Hover, n = 20) and GSE7307 (Roth, n = 36) from the Gene Expression Omnibus database, we identified a network of TFs, which bind to target genes that are differentially expressed in endometriosis. Enrichment analysis based on the hypergeometric distribution allowed us to predict the TFs involved in endometriosis (n = 40). This included known TFs such as androgen receptor (AR) and critical factors in the pathology of endometriosis, estrogen receptor α, and estrogen receptor β. We also identified several new ones from which we selected FOXA2 and TFAP2C, and their regulation was confirmed by quantitative real-time polymerase chain reaction and immunohistochemistry (IHC). Further, our analysis revealed that the function of AR and p53 in endometriosis is regulated by posttranscriptional changes and not by differential gene expression. Our integrative analysis provides new insights into the regulatory programs involved in endometriosis.

A rare case of endometrioma in a bitch

Background

Endometriosis is ectopic development of endometrial glands and stroma in extra-uterine sites and if the lesions occur as a well-defined mass is referred to as endometrioma. In the literature, endometrioma has been reported in only women and there are no reports of endometrioma in animals, including non-human primates.

Case presentation

A rare case of endometrioma is reported in an 11-year-old female German Shepherd with clinical signs of dehydration, anemia and prostration. Necropsy revealed ascites, generalized pallor, and a well-demarcated reddish mass adjacent to the left ovary and uterus and adherent to the retroperitoneum. The mass measured 25.0 × 20.0 cm with intermingled soft and firm areas. Upon incision, the mass was found to be solid with variable sized cystic cavities filled with coagulated blood. Microscopically, the mass was composed of cuboidal or prismatic epithelial cells arranged in tubules or acini. The epithelium of the mass had similar characteristics to the normal endometrium with PAS-positive secretions. The stroma was prominent and formed by loose connective tissue and smooth muscle fibers as confirmed by Masson trichrome. Extensive multifocal areas of hemorrhage were also observed in the stroma of the mass and in the interior of some epithelium-lined, cystic structures. Most of the epithelial cells had strong and diffuse cytokeratin expression, and some had vimentin expression. Epithelial and stromal cells also showed ERβ, AR, VEGF and COX2 expression. The stroma showed areas with strong and diffuse vimentin expression. Factor VIII expression was observed only in the endothelium of blood vessels in the stroma.

Conclusions

The macroscopic, microscopic and immunohistochemical findings are consistent with an endometrioma.

Endometriosis of the appendix

Purpose

Endometriosis is defined as functioning endometrial tissue outside of the uterus. Endometriosis of the appendix is uncommon. Its clinical presentation varies from asymptomatic to acute abdominal pain. The aims of this study were to describe our experience of managing patients with appendiceal endometriosis and to review the clinical characteristics of this medical condition.

Methods

Five cases of appendiceal endometriosis diagnosed between January 2007 and December 2012 were retrospectively reviewed. Patients treated for intra-abdominal endometriosis were excluded.

Results

The mean age at diagnosis was 33.8 years old. One patient was in the second trimester of pregnancy. Two patients were asymptomatic. Three patients had clinical symptoms including two with acute pain in the right lower quadrant and one with abdominal discomfort. Four patients showed appendiceal abnormalities in imaging studies including two cases of suspected mucocele and two cases of appendiceal infection. There were no suspicions of endometriosis of the appendix based on preoperative imaging studies. Three patients underwent appendectomy due to clinical symptoms, and two underwent incidental appendectomy combined with another operation. None of the patients received adjuvant therapy.

Conclusion

Appendiceal endometriosis should be included in the differential diagnosis for acute abdominal pain, especially when women of childbearing age present with clinical symptoms of acute appendicitis.

Concurrent appendiceal and umbilical endometriosis: a case report and review of the literature

INTRODUCTION

Endometriosis affects 3 to 10 percent of women of reproductive age. Most of the time it involves the pelvis; however, sites of endometriosis have been reported almost anywhere in the body. Appendiceal and primary umbilical endometriosis are considered rare loci, making accurate diagnosis elusive. Here we present the case of a 46-year-old woman with concurrent appendiceal and umbilical endometriosis.

CASE PRESENTATION

A 46-year-old Greek woman presented with a large mass in the lower abdomen adhering to the surrounding organs. She reported recurrent lower abdominal and pelvic pain and the presence of a dark-blue hard nodule at the umbilicus. She had no previous medical, surgical or gynecological history. Her physical examination and laboratory test results were without any significant findings. The laparotomy revealed a fibromatose uterus adhering to the rectum and a urinary cyst and a palpable mass in the vermiform appendix. A hysterectomy and an appendectomy were performed. The umbilical mass was also excised. Pathology revealed endometriosis of the umbilicus and the appendix. The postoperative period was uneventful and she was discharged.

CONCLUSIONS

Endometriosis, although rare, should always be considered in women of reproductive age, presenting with cyclic pain. The diagnosis is, most of the time, difficult and requires a high degree of clinical suspicion. The clinical doctor should be aware that endometriosis can sometimes be multifocal, thus a thorough investigation is required in all cases.

Molecular aspects of development and regulation of endometriosis

Endometriosis is a common and painful condition affecting women of reproductive age. While the underlying pathophysiology is still largely unknown, much advancement has been made in understanding the progression of the disease. In recent years, a great deal of research has focused on non-invasive diagnostic tools, such as biomarkers, as well as identification of potential therapeutic targets. In this article, we will review the etiology and cellular mechanisms associated with endometriosis as well as the current diagnostic tools and therapies. We will then discuss the more recent genomic and proteomic studies and how these data may guide development of novel diagnostics and therapeutics. The current diagnostic tools are invasive and current therapies primarily treat the symptoms of endometriosis. Optimally, the advancement of "-omic" data will facilitate the development of non-invasive diagnostic biomarkers as well as therapeutics that target the pathophysiology of the disease and halt, or even reverse, progression. However, the amount of data generated by these types of studies is vast and bioinformatics analysis, such as we present here, will be critical to identification of appropriate targets for further study.

Endometrioma contained within the broad ligament

We present a rare case of an endometrioma present within and firmly adherent to the broad ligament in a patient who experienced an episode of acute abdominal pain. The endometrioma was excised laparoscopically and the broad ligament repaired.

Transcriptional profiling of endometriosis tissues identifies genes related to organogenesis defects

Endometriosis is a common benign pathology, characterised by the presence of endometrial tissue outside the endometrial cavity with a prevalence of 10-15% in reproductive-aged women. The pathogenesis is not completely understood, and several theories have been proposed to explain the aetiology. Our group has recently described the presence of ectopic endometrium in a consistent number of human female foetuses analysed by autopsy, reinforcing the hypothesis that endometriosis may be generated by defects during the organogenesis of the female reproductive trait. Herein, in order to identify, at molecular level, changes involved in the disease, we compared the transcriptional profiling of ectopic endometrium with the corresponding eutopic one. Statistical analyses lead us to identify some genes specifically deregulated in the ectopic endometrium, that are involved in gonad developmental process or in wound healing process. Among them, we identified BMP4 and GREM1. BMP4 was never associated before to endometriosis and is involved in the mesoderm-Müllerian duct differentiation. GREM1 is needed for the initial step of the ureter growth and perhaps could possibly be involved in Müller ducts differentiation. These molecules might be related to the endometriosis aetiology since we showed that their expression is not related to the menstrual cycle phase both at RNA and at protein levels. These data support the theory that embryological defects could be responsible of the endometriosis generation.

Expression of Th1 and Th2 cytokine-associated transcription factors, T-bet and GATA-3, in the eutopic endometrium of women with endometriosis

The objective of the present study was to evaluate the expression of T-box expressed in T cells (T-bet) and GATA binding protein 3 (GATA-3) in the eutopic endometrium from women with endometriosis. Endometrial tissues were collected from 20 women with laparoscopically confirmed endometriosis and 20 women without endometriosis. T-bet and GATA-3 expression was measured by quantitative real-time PCR (qPCR), immunohistochemistry and Western blot analysis. Eutopic endometrial tissues from patients with endometriosis expressed lower levels of T-bet mRNA and high levels of GATA-3 mRNA, leading to a significant lower T-bet/GATA-3 mRNA ratio (P<0.05). Western blot analysis showed that the T-bet/GATA-3 protein ratio in endometriosis group was also statistically lower than that in the control group (P<0.05). These results suggested that T-bet and GATA-3 may act as cytokine regulatory genes, and the Th2-specific transcription factor, GATA-3, probably plays an essential role in the immune response and the development of endometriosis.

Umbilical laparoscopic scar endometriosis

Umbilical endometriosis is rare and challenging in both diagnosis and treatment. We report a case of an umbilical scar endometriotic nodule in a 39-year-old lady following laparoscopy-assisted vaginal hysterectomy. The wide local excision of the nodule and histopathological examination confirmed the diagnosis. We discuss the pathogenesis, diagnosis, differential diagnosis, and treatment options for the patient.

MiR-199a attenuates endometrial stromal cell invasiveness through suppression of the IKKβ/NF-κB pathway and reduced interleukin-8 expression

MicroRNAs have recently been identified as regulators that modulate target gene expression and are suggested to be involved in the development and progression of endometriosis. This study was undertaken to analyze the expression level of microRNA-199a (miR-199a) in paired ovarian endometrioma and eutopic endometrium from women with endometriosis, and to investigate the contribution of miR-199a to the invasive capability of endometrial stromal cells (ESCs). Cell adhesion, migration and Matrigel invasion assays were carried out to measure the invasiveness of ESCs. Bioinformatics prediction, reporter gene assay, PCR, western blotting and ELISA were performed to identify miR-199a targets and related signaling pathways. The results showed that the expression level of miR-199a was lower in the eutopic endometrium from women with endometriosis, and even lower in the paired ovarian endometrioma, compared with the expression in normal controls. Moreover, ectopic expression of miR-199a attenuated ESC adhesion, migration and invasiveness. MiR-199a targeted and inhibited IkappaB kinase beta (IKKβ) in ESCs. Accompanied by IKKβ reduction, miR-199a suppressed nuclear factor-kappa B (NF-κB) pathway activation and interleukin-8 (IL-8) production in ESCs. All these findings suggest that miR-199a, down-regulated in endometriosis, attenuates the invasive capability of ESCs in vitro partly through IKK/NF-κB pathway suppression and reduced IL-8 expression. In conclusion, miR-199a could be involved in the pathogenesis of endometriosis.

Endometriosis for the colorectal surgeon

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity. Although the exact pathophysiology is unclear, endometriosis is a well-known cause of pelvic pain and infertility in reproductive-aged women. Endometriosis can have extrapelvic manifestations relevant for colorectal surgeons to appreciate, such as cyclic constipation, diarrhea, hematochezia, and dyschezia. The treatment of endometriosis involves a combination of medical and surgical interventions where close collaboration between the gynecologist and colorectal surgeon can help achieve prolonged periods of symptom remission.

Acute appendicitis caused by endometriosis: a case report

Introduction

Endometriosis is a well-recognized gynecological condition in the reproductive age group. Surgical texts present the gynecological aspects of the disease in detail, but the published literature on unexpected manifestations, such as appendiceal disease, is inadequate. The presentation to general surgeons may be atypical and pose diagnostic difficulty. Thus, a definitive diagnosis is likely to be established only by the histological examination of a specimen.

Case presentation

We report a case of endometriosis of the appendix in a 25-year-old Caucasian woman who presented with symptoms of acute appendicitis and was treated by appendectomy, which resulted in a good outcome.

Conclusions

We discuss special aspects of acute appendicitis caused by endometriosis to elucidate the pathologic entity of this variant of acute appendicitis.

Colonization of Intestinal Endometriosis by Benign Colonic Mucosa: A Pattern Potentially Misdiagnosed as Invasive Mucinous Carcinoma

Endometriosis is well known for creating diagnostic pitfalls for pathologists. It may produce masses mimicking neoplasms or cause diagnostic quandaries, particularly when the patient age, location, and/or epithelial appearance are atypical. This study reports a patient with endometriosis causing rectal bleeding and involving the cecum. It produced a mass clinically considered appendiceal. The endometriosis was focally lined by intestinal epithelium including Paneth cells. In the deep endometriotic glands embedded within intestinal wall, direct fusion of the intestinal and the endometrial epithelium—the benign intestinal epithelium apparently colonizing the endometriotic foci—was found. The mass effect, plus deep-seated intestinal epithelium, closely mimicked invasive well-differentiated mucinous carcinoma. This is yet another peculiar presentation of endometriosis with potential for misinterpretation as a more serious condition, specifically well-differentiated mucinous carcinoma of the cecum or appendix.

Endometriosis and infertility: pathophysiology and management

Endometriosis and infertility are associated clinically. Medical and surgical treatments for endometriosis have different effects on a woman's chances of conception, either spontaneously or via assisted reproductive technologies (ART). Medical treatments for endometriosis are contraceptive. Data, mostly uncontrolled, indicate that surgery at any stage of endometriosis enhances the chances of natural conception. Criteria for non-removal of endometriomas are: bilateral cysts, history of past surgery, and altered ovarian reserve. Fears that surgery can alter ovarian function that is already compromised sparked a rule of no surgery before ART. Exceptions to this guidance are pain, hydrosalpinges, and very large endometriomas. Medical treatment-eg, 3-6 months of gonadotropin-releasing hormone analogues-improves the outcome of ART. When age, ovarian reserve, and male and tubal status permit, surgery should be considered immediately so that time is dedicated to attempts to conceive naturally. In other cases, the preference is for administration of gonadotropin-releasing hormone analogues before ART, and no surgery beforehand. The strategy of early surgery, however, seems counterintuitive because of beliefs that milder non-surgical options should be offered first and surgery last (only if initial treatment attempts fail). Weighing up the relative advantages of surgery, medical treatment and ART are the foundations for a global approach to infertility associated with endometriosis.

Ultrastructure of ectopic peritoneal lesions from women with endometriosis, including observations on the contribution of coelomic mesothelium

Following a study in a baboon model of endometriosis, we here describe the morphology of ectopic peritoneal lesions in the human to examine the effects of an ectopic site on glandular structure and function. Ectopic biopsies from 17 women with endometriosis were fixed and processed for electron microscopy. Certain biopsies were also probed for intermediate filaments using immunohistochemistry. Ultrastructurally, lesions showed many different glandular morphologies with indications of delayed maturation compared to normal endometrium. Mesothelium covered some lesions and there was evidence of mesothelial invasion into the stroma. Ectopic endometriotic lesions from women with endometriosis showed ultrastructural differences from eutopic endometrium, with indications that mesothelial invasion may contribute to gland development in some lesions.

Immunohistochemical study of osteopontin and l-selectin in a rat endometriosis model and in human endometriosis

OBJECTIVE

To investigate the localization of the proteins osteopontin (OPN) and L-selectin (SELL).

DESIGN

Retrospective nonrandomized immunohistochemical study in a surgically induced rat model of peritoneal endometriosis and in samples of human endometriotic lesions of ovaries.

SETTING

Department of gynecology in a university hospital.

PATIENT(S)

A rat endometriosis model was induced in 10 8-week-old SLC-Sprague-Dawley rats by surgical autotransplantation of uterus. Fourteen premenopausal women with histologically diagnosed endometriosis were selected (mean age, 39 y; range, 25-53 y). Twenty endometriotic specimens were obtained from 14 patients who underwent laparoscopic surgery for enlarged endometriotic cysts.

INTERVENTION(S)

Histopathological examination of endometriotic ovarian specimens for OPN and SELL expression by immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Demonstration of the immunoreactive staining of OPN and SELL expressions in tissues of a rat endometriosis model and of human endometriosis.

RESULT(S)

In both tissues from a rat endometriosis model and from human endometriosis, OPN was stained more prominently in glandular epithelium than in interstitial space, whereas SELL stained more prominently in interstitial space (macrophages and lymphocytes) than in epithelium. The staining pattern of OPN in ectopic endometriotic lesions was very similar to that in eutopic normal human endometrium in the secretory phase.

CONCLUSION(S)

These results suggested important roles for OPN and SELL in the pathogenesis of endometriosis.

Local application of danazol-loaded hyaluronic acid hydrogel to endometriosis in a rat model

OBJECTIVE

To evaluate the efficacy of a drug delivery system composed of danazol-loaded hyaluronic acid for local application to endometriosis.

DESIGN

Prospective, randomized study.

SETTING

Academic research unit of the department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Adult female Sprague-Dawley rats.

INTERVENTION(S)

Danazol-loaded hyaluronic acid hydrogel (DZ-HA gel) was injected into the rat endometriosis model.

MAIN OUTCOME MEASURE(S)

Size and histological changes in experimental endometriosis, the concentration of danazol in the cyst wall and plasma, and estrous cycles were examined.

RESULT(S)

Histologically, DZ-HA gel-treated cysts displayed marked atrophy of the endometrial epithelium. Increased numbers of apoptotic cells and decreased numbers of proliferative cells were noted with 10 mg/mL DZ-HA gel. Size of treated cysts decreased to approximately 60% at 9 weeks after injection. The estrous cycles were not disturbed during DZ-HA gel treatment.

CONCLUSION(S)

Local injection of DZ-HA gel achieved endometrial atrophy of an experimental model of endometriosis without disturbing the sexual cycle. These results suggest that local application of DZ using this drug delivery system may prove useful for treating endometriosis.

Initial endometriosis showing direct morphologic evidence of metaplasia in the pathogenesis of ovarian endometriosis

It is believed that ovarian endometriosis may be generated by a celomic metaplastic process from existing epithelium in the ovary. However, no morphologic evidence of metaplastic process has been described. In this study, we intended to identify the earliest morphologic changes of endometriosis within the ovary to examine if evidence of metaplasia exists. Included in this study were 110 ovarian endometriosis cases and 30 benign ovaries without endometriosis but with ovarian epithelial inclusions (OEIs). Among the 110 well-established ovarian endometriosis cases, 34 cases showed areas of initial endometriosis (IE), which is defined as lesions showing direct transitions from normal-looking ovarian tissue to areas of minimal formation of endometriosis and/or to areas of full-blown endometriosis. We further divided IE into two types: type I IE was present on the ovarian surface, which was associated with ovarian surface epithelia; type II was located within the ovarian cortex, which was associated with OEIs. Sections containing IE, OEIs, and well-formed endometriosis were subject to CD10 and aromatase immunostaining. In IE lesions, the number of CD10-positive cells were significantly higher than the number of that in OEIs, but lower than that of well-formed endometriosis areas (p < 0.05). Aromatase expression was detected in both epithelial and stromal components of the IE lesions, indicating that estrogen local production may be involved in this initial process of endometriosis. Microvessel density was higher in IE lesions than in areas of OEI (p < 0.05). Based on the morphologic characteristics of IE, we believe that IE represent a spectrum of the earliest morphologic changes of endometriosis identifiable by routine microscopy. The morphologic transitions from ovarian surface epithelium or OEI to IE lesions provide direct metaplastic evidence for the pathogenesis of ovarian endometriosis. This metaplastic process may not only involve the ovarian epithelial cells, but also stromal components. Local production of estrogen, probably in high-levels, may be related to the initial process of endometriosis, although detailed mechanisms remain to be clarified.

Recent Advances in Endometriosis With Emphasis on Pathogenesis, Molecular Pathology, and Neoplastic Transformation

This article reviews recent advances in our understanding of endometriosis with special reference to its pathogenesis, recent molecular studies, and relationship to neoplasia. Pathogenetic factors include familial predisposition, immunological factors, cell adhesion factors, angiogenic factors, and hormonal factors. Recent molecular findings in endometriosis include the monoclonality of endometriotic cysts and loss of heterozygosity in the majority of cases associated with adenocarcinoma. Women with a long-standing history of endometriosis have an increased risk of ovarian cancer, most commonly endometrioid and clear cell adenocarcinomas. In these cases, there is a high frequency of atypia in the endometriosis, and the endometriosis and the associated ovarian carcinoma may show identical PTEN mutations.

Catamenial pneumothorax revisited: Clinical approach and systematic review of the literature

BACKGROUND

Catamenial pneumothorax is a rare entity of spontaneous, recurring pneumothorax in women. It has been associated with thoracic endometriosis, yet varying clinical courses and the lack of consistent intraoperative findings have led to conflicting etiologic theories.

METHODS

We discuss etiology, clinical course, and surgical treatment of 3 women with catamenial pneumothorax. In addition, the world literature since the first description is reviewed.

RESULTS

Three women (31, 32, and 39 years old) had recurrent, menses-associated, right-sided spontaneous pneumothoraces. They had undergone video-assisted thoracoscopic surgery previously, with various unsuccessful procedures. Finally, with video-assisted thoracoscopic surgery multiple small perforations in the tendinous part of the right diaphragm with adjacent endometrial implants were detected. After plication of the involved area, 2 patients have been free of recurrence for 22 and 13 months, respectively. Laparoscopic evaluation in 1 woman with a further recurrence revealed asymptomatic pelvic endometriosis. This patient has been free of recurrence since initiation of luteinizing hormone-releasing hormone analog therapy for 17 months. In a review of 229 cases of catamenial pneumothorax in the literature, adequate information was given for 195 patients (85.2%). One hundred fifty-four (79%) were treated surgically, with detailed findings reported for 140 (91%). Thoracic endometriosis was diagnosed in 73 patients (52.1%), and 54 (38.8%) showed diaphragmatic lesions. Pleurodesis, with or without diaphragmatic repair or wedge resection, was performed in 81.7% of the cases.

CONCLUSIONS

Catamenial pneumothorax may be suspected in ovulating women with spontaneous pneumothorax, even in the absence of symptoms associated with pelvic endometriosis. During video-assisted thoracoscopic surgery, inspection of the diaphragmatic surface is paramount. Plication of the involved area alone can be successful. In complicated cases, hormonal suppression therapy is a helpful adjunct.

What we have learned from isolated cells from human ovary?

In the ovary, morphodynamics of follicles with cyclic maturation, ovulation and repair occur under the control of various tropic factors. The ovarian functions have been mostly studied by using subhuman primates and non-primate animals because of the limited availability of closely staged human specimens. We have recently established the in vitro culture systems of ovarian surface epithelium (OSE) and granulosa cells of humans, and subsequently developed the immortalization of each cell. The immortalized cell lines may supply us advanced studies on ovarian disorders as well as its physiological functions. On the embryologically putative müllerian potential of coelomic epithelium, endometriosis can be explained by coelomic metaplasia from the peritoneal mesothelium, including OSE. We can microscopically observe a continuity from flat epithelial cells on the ovarian surface or within the cortical inclusion cysts to endometriotic gland cells. The primary human OSE cells exhibited a glandular-stromal structure similar to endometriosis when they were co-cultured with endometrial stromal cells in an estrogen-rich environment. Primary and immortalized OSE cells converted the estrone to estradiol, and expressed the genes for steroidogenic factor-1 (SF-1), p450arom and 17beta-HSDs. This character of OSE was, in part, similar to the granulosa cells. One of the immortalized OSE clone produces disseminated tumors mimicking undifferentiated carcinomas in nude mice. Ovarian granulosa cells play a key role in the functional maturation of the entire follicle. The molecular pathways in granulosa cells responsible for the growth, differentiation, and nursing the oocyte are still largely unknown. Our immortalized human granulosa cell line, GC1a, obtained from developing follicles, showed no steroid hormone biosynthesis, and no detectable expression of the genes for StAR or cytochrome p450 enzymes due to the lack of SF-1. Transfected SF-1 elicited estradiol secretion in GC1a cells with concomitant expression of the genes encoding the proteins for gonadal steroidogenesis. The enzymatic activity of 17beta-HSD was also achieved by SF-1 transgene. These results indicate that SF-1 controls the gene expression required for steroidogenesis in the human developing follicle. Clinically, immortalized GC1a cells from human origin, with steroidogenic capacity, may serve as a feeder layer for in vitro oocyte maturation. Further investigations of our immortalized OSE and granulosa cells of humans will allow us to clarify whether they have a single progenitor cell.

Pathogenesis of endometriosis

Endometriosis is a common gynecologic disorder characterized by the presence of endometrial tissue outside the uterine cavity. Various theories have been put forth to explain the mechanisms for the development of this disease. Although no single theory can explain all cases of endometriosis, the retrograde menstruation theory has gained the widest acceptance. This theory proposes that viable endometrial tissue is refluxed through the fallopian tubes during menstruation and implants on peritoneal surface or pelvic organs. Retrograde menstruation occurs in 76% to 90% of women. The much lower prevalence of endometriosis suggests that additional factors determine susceptibility to endometriosis. Once in the peritoneal cavity, the survival and implantation of endometrial cells seem to be mediated by abnormal MMP and TIMP expression, altered immune milieu, aberrant local aromatase activity, and genetic and environmental factors.

New considerations for the pathogenesis of endometriosis

OBJECTIVES

To review the available evidence regarding the immunological, epidemiological and other factors involved in the pathogenesis of endometriosis.

METHODS

Literature review.

RESULTS

Endometriosis remains a poorly-understood disease of unknown etiology and pathogenesis.

CONCLUSIONS

There is evidence to suggest that alterations in the immune response, whether genetically transmitted or environmentally induced, predispose women to the ectopic implantation of endometrial cells transported into the peritoneal cavity by way of retrograde menstruation. This predisposition may exist because of an impaired peritoneal clearing of endometrial cells and fragments or because of pathological angiogenesis.

Identification of an invasive, N-cadherin-expressing epithelial cell type in endometriosis using a new cell culture model

Studies of molecular, cellular, and pathophysiological parameters in endometriosis are primarily hampered by a lack of in vitro model systems, such as endometriotic cell lines. To overcome this we successfully established cell lines from peritoneal endometriotic biopsies and characterized them at the molecular and cellular level. Two types of cells could be transformed: one exhibiting stromal cell features (cytokeratin/E-cadherin-negative), the other epithelial-like (cytokeratin-positive/E-cadherin-negative, invasive in vitro). Using a Matrigel assay the epithelial-like cell lines proved as invasive as metastatic carcinoma cells, possibly through the influence of N-cadherin implicated as a path-finding cadherin allowing cellular invasion and migration in both normal and pathophysiological processes. Our results support the idea that endometriosis, although not neoplastic, shares features with malignant cells and that metastasis in endometriosis may include mechanisms proposed for micrometastasis in cancer. Thus our cell lines will not only be useful tools for analyzing molecular and cellular events relating to endometriosis, but may also represent a paradigm for invasion and metastasis in general.