Secondary müllerian system and endometriosis

Müllerian anomalies and endometriosis as potential explanatory models for the retrograde menstruation/implantation and the embryonic remnants/celomic metaplasia pathogenic theories: a systematic review and meta-analysis

STUDY QUESTION

Does endometriosis prevalence differ in patients with obstructive Müllerian anomalies (OMA) versus those with nonobstructive Müllerian anomalies (NOMA), and in patients with NOMA versus those without Müllerian anomalies?

SUMMARY ANSWER

The quantitative synthesis of published data demonstrates a substantially increased prevalence of endometriosis in patients with OMA compared with those with NOMA, and a similar prevalence in patients with NOMA and those without Müllerian anomalies.

WHAT IS KNOWN ALREADY

The pathogenesis of endometriosis has not been definitively clarified yet. A higher prevalence of endometriosis in patients with OMA than in those with NOMA would support the retrograde menstruation (RM)/implantation theory, whereas a higher prevalence of endometriosis in the NOMA group than in the group without Müllerian anomalies would support the embryonic remnants/celomic metaplasia hypothesis.

STUDY DESIGN, SIZE, DURATION

This systematic review with meta-analysis was restricted to full-length, English-language articles published in peer-reviewed journals between 1980 and 2023. The PubMed and EMBASE databases were searched using the keyword 'endometriosis' in combination with 'Müllerian anomalies', 'obstructive Müllerian anomalies', 'female genital malformations', 'retrograde menstruation', 'infertility', 'pelvic pain', and 'classification'. References from relevant publications were screened, and PubMed's 'similar articles' and 'cited by' functions were used.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Studies were selected if they reported the prevalence of surgically confirmed endometriosis in either individuals with OMA compared to those with NOMA, or patients with NOMA compared to those without Müllerian anomalies. Cohort and case-control studies and case series were deemed eligible for inclusion. Noncomparative studies, studies not reporting both the number of individuals with endometriosis and the total number of those with Müllerian anomalies or with other gynecological conditions, those including exclusively data on patients with absent or uncertain menstrual function (e.g. complete Müllerian agenesis category), or with imperforate hymen were excluded. Two reviewers independently abstracted data. The risk of bias was assessed with the Risk of Bias In Non-randomized Studies of Exposures tool. The overall certainty of the evidence was graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines.

MAIN RESULTS AND THE ROLE OF CHANCE

Seven retrospective studies were included. The overall mean estimate of endometriosis prevalence was 47% (95% CI, 36-58%) in patients with OMA, and 19% (95% CI, 15-24%) in patients with NOMA, with a common odds ratio (OR) of 4.72 (95% CI, 2.54-8.77). The overall mean estimate of endometriosis prevalence in patients with NOMA was 23% (95% CI, 20-27%), and that in patients without Müllerian anomalies was 21% (95% CI, 20-22%), with a common OR of 0.95 (95% CI, 0.57-1.58). The overall certainty of the evidence according to GRADE guidelines was judged as low for both comparisons.

LIMITATIONS, REASON FOR CAUTION

Some NOMA subtypes may create a partial obstacle to menstrual efflux and/or generate dysfunctional myometrial contractions that favor transtubal reflux, thus increasing the risk of endometriosis and limiting the difference between OMA and NOMA. As infertility and pelvic pain are strongly associated with endometriosis, women with these symptoms are inappropriate controls. Confounding by indication could explain the lack of difference in endometriosis prevalence between patients with NOMA and those without Müllerian anomalies.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this meta-analysis support the validity of the RM theory but do not definitively rule out alternative hypotheses. Thus, RM may be considered the initiator for the development of endometriotic lesions, while not excluding the contribution of both inheritable and tissue-specific genetic and epigenetic modifications as disease-promoting factors.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was received for this review. P.Ve. is a member of the Editorial Board of Human Reproduction Open, the Journal of Obstetrics and Gynaecology Canada, and the International Editorial Board of Acta Obstetricia et Gynecologica Scandinavica; has received royalties from Wolters Kluwer for chapters on endometriosis management in the clinical decision support resource UpToDate; and maintains both a public and private gynecological practice. E.S. discloses payments from Ferring for research grants and honoraria from Merck-Serono for lectures. All other authors declare they have no conflict of interest.

REGISTRATION NUMBER

N/A.

Primary Retroperitoneal Carcinomas: New Insights into Pathogenesis and Clinical Management in Comparison with Ovarian Carcinomas and Carcinoma of Unknown Primary

Primary retroperitoneal carcinomas are very rare tumors. Their pathogenesis remains unknown but may be associated with that of ovarian carcinomas, considering the similarity in morphology and gender preference. Although metaplasia of coelomic epithelium is the most widely accepted theory, the pathogenesis of retroperitoneal carcinomas may differ by histologic subtype, like ovarian carcinomas. Mucinous carcinoma, which develops in both women and men, may originate in both primordial germ cells and Walthard cell nests that may be derived from the fallopian tube. Serous carcinomas may be associated with endosalpingiosis, the presence of fallopian tube-like epithelium outside the fallopian tube, and a remnant Müllerian tract. Endometrioid and clear cell carcinomas appear to be associated with extraovarian endometriosis. Additionally, both carcinomas in the retroperitoneal lymph nodes may be metastatic diseases from endometrial and/or renal cell cancer that regress spontaneously (carcinoma of unknown primary). Retroperitoneal carcinomas are difficult to diagnose, as they have no characteristic symptoms and signs. Surgery is the cornerstone of treatment, but the necessity of chemotherapy may depend on histological subtype. Further studies are necessary, in particular studies on endosalpingiosis, as endosalpingiosis is a poorly understood condition, although it is associated with the development of both serous and mucinous carcinomas.

A Decade of Therapeutic Challenges in Synchronous Gynecological Cancers from the Bucharest Oncological Institute

The aim of our study is to present the particularities of a specific subset of gynecological cancer patients in Romania. We present a review of synchronous gynecological neoplasia (SGN) treated in the Bucharest Oncological Institute's surgery departments over a decade. Between 2012 and 2022, 7419 female patients with genital malignancies were treated. We identified 36 patients with invasive synchronous primary gynecological cancers (0.5%) and 12 cases with one primary gynecological and another primary invasive pelvic cancer (rectal/bladder). All recurrent, metastatic, or metachronous tumors detected were excluded. Demographic data, personal history, presenting symptoms, pathologic findings, staging, treatment, and evolution for each case were recorded. Usually, the most common SGN association is between ovarian and endometrial cancer of endometrioid differentiation (low-grade malignancies with very good prognosis). However, we noticed that, given the particularities of the Romanian medical system, the most frequent association is between cervical and endometrial, followed by cervical and ovarian cancers. Moreover, the cancer stage at diagnosis is more advanced. In countries with low HPV vaccination rate and low adherence to screening programs, SGNs can present as extremely advanced cases and require extensive surgery (such as pelvic exenterations) to achieve radicality. This multimodal treatment in advanced cases with high tumor burden determines a reduction in survival, time until progression, and quality of life.

New Insights in Pathogenesis of Endometriosis

Endometriosis is a gynecological disease characterized by the growth of endometrial glands and stroma outside the uterine cavity. The incidence of the disease is very high, there are currently no reliable early diagnostic tests, the therapies are only symptomatic and, consequently, the social impact of endometriosis is very important, also considering the related fertility problems. Despite this, the pathogenesis of endometriosis is still not fully defined. Retrograde menstruation and coelomic metaplasia are currently the most recognized pathogenetic hypotheses. Recent experimental evidences generated by our research group and by others have indicated an alteration of the fine-tuning of the female genital system developmental program during a critical window of time in the fetal life as the pathogenetic event prompting to the development of endometriosis later in life. Goal of this article is to present a revision of the recent literature about the different pathogenetic mechanisms proposed for endometriosis with particular emphasis on the embryologic theory. The possible clinical and pathological implications of these findings will be discussed.

The ischemic time window of ectopic endometrial tissue crucially determines its ability to develop into endometriotic lesions

Endometriosis develop from shed endometrial fragments via retrograde menstruation. This affects the survival, proliferation and vascularization of the tissue and its final ability to form endometriotic lesions. Within this study, uterine tissue samples from donor mice were precultivated for 24 h or 72 h to simulate avascular periods. Their morphology, microvessel density, apoptotic activity and expression of angiogenesis-related proteins were analyzed in vitro. The formation of endometriotic lesions in vivo was assessed after transplantation of precultivated uterine tissue samples to the abdominal wall and dorsal skinfold chambers by means of high-resolution ultrasound, intravital fluorescence microscopy, histology and immunohistochemistry. In vitro, 72-h-precultivated uterine tissue samples exhibit extensive areas of tissue necrosis and high numbers of apoptotic cells as well as a significantly reduced cell and microvessel density. These samples failed to develop into endometriotic lesions. In contrast, the 24-h-precultivated samples showed, that their early vascularization and growth in vivo was improved when compared to controls. This indicates that avascular periods have a strong impact on the survival of ectopic endometrial tissue and the chance for the development of endometriosis.

Endometriosis: Epidemiology, Classification, Pathogenesis, Treatment and Genetics (Review of Literature)

Endometriosis is a “mysterious” disease and its exact cause has not yet been established. Among the etiological factors, congenital, environmental, epigenetic, autoimmune and allergic factors are listed. It is believed that the primary mechanism of the formation of endometriosis foci is retrograde menstruation, i.e., the passage of menstrual blood through the fallopian tubes into the peritoneal cavity and implantation of exfoliated endometrial cells. However, since this mechanism is also observed in healthy women, other factors must also be involved in the formation of endometriosis foci. Endometriosis is in many women the cause of infertility, chronic pain and the deterioration of the quality of life. It also represents a significant financial burden on health systems. The article presents a review of the literature on endometriosis—a disease affecting women throughout the world.

Endometriosis in adolescent and young women

Endometriosis in adolescence represents a specific variant of the disease with its own characteristics and, in some cases, even a possibly different pathogenesis. It has its own clinical presentation, diagnostic and therapeutic modalities. The condition is not rare as once thought and certainly deserves attention in view of increasing evidence of its likely progressive nature. Numerous theories for Its pathogenesis have been formulated and they have been divided into two main categories: the 'in-situ' and the 'transplantation' hypotheses. Clinical manifestations include as the prevailing symptom a persistent chronic pelvic pain, despite medical treatment, manifested under various forms: dysmenorrhea, acyclic chronic pain, acute abdominal pain and migraines. These symptoms can substantially affect the quality of life on an adolescent. At histopathology, adolescent endometriosis is characterized by a high proportion of subtle, clear, red or vesicular implants and by the rarity of deep nodules. Frequently, the picture includes ovarian endometriomas. In some adolescent girls, lesions may regress or even disappear, probably through immune suppression; in others, chronic stress, unhealthy diet or lifestyle such as high-fat diet, may accelerate lesional progression and cause symptoms. Classically, management of adolescent endometriosis has been centered on attempts to treat dysmenorrhea; today both medical and surgical modalities have the potential to improve quality of life, alleviate symptoms, prevent the development of more severe disease and minimize risks for future fertility in adolescents. Nonetheless, at present, medical treatments are considered the first line of interventions in treating young women.

Neonatal Uterine Bleedings: An Ignored Sign but a Possible Cause of Early-Onset Endometriosis - A Systematic Review

OBJECTIVE

Based on the hypothesis that neonatal uterine bleedings (NUB), occurring mostly in the first week after birth, could represent a pathogenetic mechanism for early-onset endometriosis, this systematic review (SR) was undertaken to evaluate the prevalence and screening strategies used to assess and quantify NUB.

DESIGN

Both a SR and a sample literature search in PubMed and Embase were conducted to gather information on NUB prevalence and screening techniques. This was performed by an information specialist. Only full-text articles regarding the assessment of NUB in neonates in the first 2 weeks after birth were included. No limit on language or publication data was used.

MATERIALS AND METHODS

The SR was registered in PROSPERO (CRD42019138121). Data was first assessed for eligibility on title and abstract by 2 blinded review authors. Any disagreements were discussed with a third reviewer if necessary. Subsequently, full-text articles were read and assessed for quality using the Cochrane Collaboration Handbook.

RESULTS

Out of 1,988 articles in the systematic search, 10 relevant articles were selected, of which 8 were identified through the systematic search and 2 were found through other sources. The sample search of 4,445 articles did not bring up relevant articles. Results were not comparable due to the heterogeneity of screening techniques, although data showed consensus. The prevalence of visible bleeding ranged from 3.3 to 53.8% and the prevalence of occult bleeding from 25.4 to 96.7%. The occurrence was the highest between the 3rd and 7th day postpartum (PP) and the bleeding lasted for 3-4 days on average. Various screening techniques for detecting NUB were found in the literature, including the use of hemoglobin detection devices (such as Hemastix) in the vaginal vestibulum, comparison of diapers with stains of known volume, colposcopy, and ultrasonography.

CONCLUSION

The reported prevalence of NUB varies considerably, with a consistent occurrence between the 3rd and the 7th day PP. Literature to assess NUB is dated. The techniques are poorly described and heterogeneous. Future research should focus on prospective cohort studies in order to attempt to correlate NUB cases to (early-onset) endometriosis.

NK Cells as Potential Targets for Immunotherapy in Endometriosis

Endometriosis is a common gynecological disease defined by the presence of endometrial-like tissue outside the uterus, most frequently on the pelvic viscera and ovaries, which is associated with pelvic pains and infertility. It is an inflammatory disorder with some features of autoimmunity. It is accepted that ectopic endometriotic tissue originates from endometrial cells exfoliated during menstruation and disseminating into the peritoneum by retrograde menstrual blood flow. It is assumed that the survival of endometriotic cells in the peritoneal cavity may be partially due to their abrogated elimination by natural killer (NK) cells. The decrease of NK cell cytotoxic activity in endometriosis is associated with an increased expression of some inhibitory NK cell receptors. It may be also related to the expression of human leukocyte antigen G (HLA-G), a ligand for inhibitory leukocyte immunoglobulin-like receptor subfamily B member 1 (LILRB1) receptors. The downregulated cytotoxic activity of NK cells may be due to inhibitory cytokines present in the peritoneal milieu of patients with endometriosis. The role of NK cell receptors and their ligands in endometriosis is also confirmed by genetic association studies. Thus, endometriosis may be a subject of immunotherapy by blocking NK cell negative control checkpoints including inhibitory NK cell receptors. Immunotherapies with genetically modified NK cells also cannot be excluded.

EXTL3-interacting endometriosis-specific serum factors induce colony formation of endometrial stromal cells

Endometriosis is a benign chronic condition characterized by the existence of endometrial-like stroma and glandular tissue in extrauterine locations. The molecular mechanisms of its pathogenesis have not been elucidated. We have studied the role of EXTL3 (exostosin-like 3) in endometriosis and found that it is expressed in endometrial tissue as well as endometriosis lesions. We have found that serum from endometriosis patients contains a factor or factors, which interact with EXTL3 resulting in strongly increased colony formation in regenerating cell culture. We also found increased anti-EXTL3 antibodies in endometriosis patients’ sera. EXTL3 is an N-acetyl glucosamine (GlcNAc) transferase, performing a key step in heparan sulfate (HS) glucosaminoglycan synthesis. Many viruses replicate in regenerating epithelial cells and use HS as a receptor for cell entry. We measured antibody titres to viruses, which use HS as a receptor for cell entry, and found rarely increased titres for these viruses in endometriosis sera, whereas titres to viruses using other receptors were equally distributed in study groups. The data indicate that perturbation of HS metabolism is associated with 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.

Functional müllerian tissue within the conus medullaris generating cyclical neurological morbidity in an otherwise healthy female

PURPOSE

Endometriosis is a common disease; however, ectopic müllerian tissue within the spine is a rare entity with the potential for producing significant neurological compromise. There are several postulated etiologies for this phenomenon, and only a few case reports are available in the world literature. Knowledge of this rare phenomenon is of paramount importance, since early diagnosis can lead to lessened neurological morbidity.

METHODS

In this manuscript, we present a case report, discuss gynecological and neurosurgical perspectives relating to the treatment strategies for managing this entity, and propose an alternative explanation for such an occurrence from a neurogenetic standpoint.

RESULTS

We present a case of spinal müllerianosis within the conus medullaris which was managed symptomatically for several years with an intracystic drain and subcutaneous reservoir. Over the years, it became clear that there was a cyclical presentation to her clinical malady, which at times was severe. Ultimately, she required surgical resection which aided in her diagnosis and subsequent treatment.

CONCLUSION

Intraspinal müllerianosis is a rare location for an otherwise common disease in women and has the potential to create significant neurological morbidity by creating a mass lesion. Although the exact etiology remains unclear, the histogenic theories of embryologic origin appear most plausible. Treatment strategies for this condition may include hormonal therapy, obstetrical surgery, or open spinal surgery. This unusual and poorly understood disease should be considered in the differential diagnosis for intraspinal lesions presenting with hemorrhage in the clinical context of cyclical neurological symptoms.

[Endometriosis: the gynecologist's opinion]

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity. Endometriosis affects 7-10% of women of reproductive age, 60% of women with pelvic pain, and up to 50% of women with infertility. Etiology and pathogenesis of the disease are still unclear, with the theory of retrograde menstruation, and possibly associated cofactors, as the most important. The definitive method to diagnose endometriosis is visualization at surgery, preferably at laparoscopy, with histology confirmation of disease. The revised classification of the American Society for Reproductive Medicine is used to stage the disease and determine the patient's prognosis. The treatment of the disease depends on the patient's age, associated symptoms, and disease stage. Medical or surgical therapy may be used in case of pain associated with endometriosis, whereas surgery is the mainstay of treatment in case of endometriosis-associated infertility.

Western herbal medicine, epigenetics, and endometriosis

Endometriosis is an enigmatic disease characterized by the presence and growth of endometrial-like tissue outside the uterine cavity. The etiology of endometriosis is poorly understood, yet recent evidence suggests that epigenetic aberrations and heritable changes in the genome may be the key to understanding how to approach this disease. Difficulty in long-term management of endometriosis symptoms and unpredictability of treatment outcome necessitate research into other treatment modalities, such as Western herbal medicine. This article reviews commonly used herbs in the treatment of endometriosis, the effects of phytochemical constituents on endometrial cells, and the impact on the epigenome.

Identification of displaced endometrial glands and embryonic duct remnants in female fetal reproductive tract: possible pathogenetic role in endometriotic and pelvic neoplastic processes

BACKGROUND

Recent findings strongly promoted the hypothesis that common pelvic gynecological diseases including endometriosis and ovarian neoplasia may develop de novo from ectopic endometrial-like glands and/or embryonic epithelial remnants. To verify the frequency, the anatomical localization and the phenotype of misplaced endometrial tissue along the fetal female reproductive tract, histological and immunohistochemical analyses of uteri, fallopian tubes, and uterosacral ligaments were performed.

METHODS

Reproductive organs were collected from seven female fetuses at autopsy, five of them from gestational ages between 18 and 26 weeks and two fetuses with gestational ages of 33 and 36 weeks deceased of placental anomalies. Serial sections from areas containing ectopic glands and embryonic duct residues were analyzed by histological and immunohistochemical procedures.

RESULTS

Numerous ectopic endometrial glands and stroma were detected in the myometrium in two fetuses with low levels of expression of estrogen receptor-alpha (ER-α) and progesterone receptors (PR). The embryonic ducts were localized in the uterine broad and ovarian ligaments and under the fallopian tube serosa in six fetuses. Low levels of steroid receptors expression were found in the embryonic residues, whereas the carcino-embryonic antigen (CEA) and the tumor marker Ca 125 were not detected. The embryonic residues stromal component strongly expressed the CD 10 and vimentin proteins.

CONCLUSION

The anatomical and the immunohistochemical features of the ectopic organoid structures identified in fetal female reproductive tract suggest that endometriotic as well as neoplastic disease in adult women may develop on the basis of misplaced endometrial glands and/or embryonic cell remnants.

Stretch magnitude- and frequency-dependent cyclooxygenase 2 and prostaglandin E2 up-regulation in human endometrial stromal cells: Possible implications in endometriosis

Endometriosis, with a prevalence rate ranging from 6% to 10%, is the major contributor to pelvic pain and subfertility, and considerably reduces the quality of life in affected women. However, the pathogenesis of this disease remains largely unknown. The present study aimed to uncover the role of hyperperistalsis in the pathogenesis of endometriosis, by exploring the response of human endometrial stromal cells (ESCs) to the cyclic stretch in vitro. ESCs isolated from 18 different endometrium biopsies undergoing hysterectomy for myoma were subjected to uniaxial cyclic stretches with different magnitude and frequency using the Uniaxial Tension System. Expression of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1) in stretched and unstretched ESCs were assessed by realtime quantitative polymerase chain reaction and Western blot. Production of prostaglandin E2 (PGE2) in the culture medium was measured by enzyme-linked immunosorbent assay. The cyclic stretch mimicking hyperperistalsis in endometriosis (5% elongation at 4 cycles/min) stimulated quick up-regulations of COX-2 and mPGES-1 simultaneously on both transcriptional and translational levels, and delayed PGE2 overproduction was also noted in ESCs. As the stretch magnitude or frequency increased, so did overexpression of COX-2 and PGE2 ( P < 0.05). By contrast, the cyclic stretch mimicking physiological peristalsis (3% elongation at 2 cycles/min) did not induce significant COX-2, mPGES-1 or PGE2production within 12 h. Both COX-2 and mPEGS-1 are PGE2 synthases, and the aberrant COX-2 and PGE2 production play important roles in the pathogenesis of endometriosis. Therefore, the present findings revealed that increased stretch stimuli from the hyperperistalsis of endometriosis were capable of causing the aberrant COX-2 and PGE2 expression in the endometrium by mechanotransduction, in a magnitude and frequency-dependent manner. It implied possible roles of hyperperistalsis in the pathogenesis of endometriosis, particularly in the view of COX-2 and PGE2.

Ovarian cancer stroma: pathophysiology and the roles in cancer development

Ovarian cancer represents one of the cancers with the worst prognostic in adult women. More than half of the patients who present with clinical signs such as abdominal bloating and a feeling of fullness already show advanced stages. The majority of ovarian cancers grow as cystic masses, and cancer cells easily spread into the pelvic cavity once the cysts rupture or leak. When the ovarian cancer cells disseminate into the peritoneal cavity, metastatic nests may grow in the cul-de-sac, and in more advanced stages, the peritoneal surfaces of the upper abdomen become the next largest soil for cancer progression. Ascites is also produced frequently in ovarian cancers, which facilitates distant metastasis. Clinicopathologic, epidemiologic and molecular studies on ovarian cancers have improved our understanding and therapeutic approaches, but still further efforts are required to reduce the risks in the patients who are predisposed to this lethal disease and the mortality of the patients in advanced stages. Among various molecules involved in ovarian carcinogenesis, special genes such as TP53, BRCA1 and BRCA2 have been well investigated. These genes are widely accepted as the predisposing factors that trigger malignant transformation of the epithelial cells of the ovary. In addition, adnexal inflammatory conditions such as chronic salpingitis and ovarian endometriosis have been great research interests in the context of carcinogenic background of ovarian cancers. In this review, I discuss the roles of stromal cells and inflammatory factors in the carcinogenesis and progression of ovarian cancers.

Pathogenesis of endometriosis: the role of genetics, inflammation and oxidative stress

INTRODUCTION

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity.

MATERIALS AND METHODS

The etiology of this multifactorial disease is still unresolved and an increasing number of studies suggest that genetic, hormonal, environmental, immunological and oxidative factors may all play an important role in the pathogenesis of this disorder.

CONCLUSIONS

In this literature review, inflammatory activity, oxidative stress as well as genetic abnormalities and mutations have been studied in an effort to identify factors predisposing to endometriosis.

Paired-box gene 2 is down-regulated in endometriosis and correlates with low epidermal growth factor receptor expression

BACKGROUND

Paired-box 2 (Pax2) is involved in the development of the female genital tract and has been associated with endometrial pathologies. The expression of Pax2 is induced by epidermal growth factor (EGF) and estrogens. In the present study, Pax2 expression and regulation were investigated in endometriosis.

METHODS AND RESULTS

Pax2 protein expression was assessed by immunohistochemistry in the eutopic (i.e. inside the uterus) and ectopic tissue (endometriosis) from 11 patients. Immunoreactivity was high in the endometrium, with strong epithelial and weaker stromal staining. Similar expression patterns of Pax2 were observed in the endometrium of women without endometriosis (n = 12). The mRNA level of Pax2 was assessed by real-time PCR in the eutopic and ectopic endometria of 14 patients and in the endometrium from women without endometriosis (n = 20). Pax2 expression was lower in endometriotic lesions than that in the eutopic endometrium of patients (P< 0.001) and controls (P= 0.007). Three possible mechanisms determining low Pax2 expression were investigated: EGF signalling, CpG DNA methylation of the Pax2 promoter and steroid response. The mRNA level of the EGF receptor (EGFR1) was assessed in the samples used for Pax2 mRNA assessment. A significant correlation between EGFR1 and Pax2 in both eutopic and ectopic tissues was observed (R = 0.58; slope regression line, 0.81; 95% CI: 0.09-1.52 and R = 0.54; slope regression line, 2.51; 95% CI: 0.02-4.99, respectively). CpG DNA methylation was analyzed by methyl-specific PCR in two regions of the Pax2 promoter but they were unmethylated in all samples. Steroid responsiveness was assessed using endometrial explant cultures and Pax2 was not regulated by either 17β-estradiol or progesterone.

CONCLUSIONS

In endometriosis patients, Pax2 is down-regulated in the lesions compared with the eutopic tissue, possibly due to low EGF signalling.

Immune interactions in endometriosis

Endometriosis is a common, complex gynecologic disorder characterized by the presence of endometrial glands and stroma at extrauterine (ectopic) sites. In women who develop this disease, alterations in specific biological processes involving both the endocrine and immune systems have been observed, which may explain the survival and growth of displaced endometrial tissue in affected women. In the past decade, a considerable amount of research has implicated a role for alterations in progesterone action at both eutopic and ectopic sites of endometrial growth which may contribute to the excessive inflammation associated with progression of endometriosis; however, it remains unclear whether these anomalies induce the condition or are simply a consequence of the disease process. In this article, we summarize current knowledge of alterations within the immune system of endometriosis patients and discuss how endometrial cells from women with this disease not only have the capacity to escape immunosurveillance, but also use inflammatory mechanisms to promote their growth within the peritoneal cavity. Finally, we discuss evidence that exposure to an environmental endocrine disruptor, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, can mediate the development of an endometrial phenotype that exhibits both reduced progesterone responsiveness and hypersensitivity to proinflammatory stimuli mimicking the endometriosis phenotype. Future studies in women with endometriosis should consider whether a heightened inflammatory response within the peritoneal microenvironment contributes to the development and persistence of this disease.

A laparoscopic approach to Nuck's duct endometriosis

OBJECTIVE

To report a case of uncommon endometriosis located in the Nuck's duct and its laparoscopic resolution.

DESIGN

Case report.

SETTING

Gynecologic department at 12 de Octubre University Hospital, Madrid.

PATIENT(S)

A 35-year-old woman, gravida 1 para 1, presented with an inguinal right mass. She had a right nephrectomy because of acute pyelonephritis. Computed tomography showed a cystic lesion that was suggestive of a Nuck's duct cyst. Fine-needle aspiration cytology was performed, and endometriosis was determined.

INTERVENTION(S)

Cyst removal and closure of the internal inguinal ring's defect by the laparoscopic approach.

MAIN OUTCOME MEASURE(S)

Disease free.

RESULT(S)

The intervention was successfully performed by laparoscopic approach. The postoperative evolution was good, and the patient was discharged 2 days after surgery.

CONCLUSION(S)

Inguinal or Nuck's duct are both uncommon locations for endometriosis; therefore, it is difficult to suspect in patients without a surgical history. Once identified, the treatment involves removal of the endometrioma and repair of the internal inguinal ring. A laparoscopic approach should be considered when possible.

Identification of cells with colony-forming activity, self-renewal capacity, and multipotency in ovarian endometriosis

Endometriosis, the growth of endometrial tissue outside the uterine cavity, is a common gynecological disorder affecting 10% to 15% of women in their reproductive years. Retrograde menstrual shedding containing endometrial stem/progenitor cells has been postulated to be involved in its pathogenesis. In this study, we identified putative endometriotic stem/progenitor cells by their colony-forming potential, self-renewal capacity, and multipotency. Purified epithelial and stromal cells isolated from ovarian endometriotic cysts formed large and small colony-forming units (CFUs) in clonogenic assay. The colony-forming activity of epithelial and stromal cells was found to differ greatly between autologous endometrium and ovarian endometrioma samples. The large CFUs could propagate more than the small CFUs. The endometriotic epithelial small CFUs expressed epithelial markers (epithelial cell adhesion molecule, cytokeratin, and α6 integrin); only occasional large CFUs expressed α6 integrin. Aside from the expression of fibroblast markers, stromal CFUs also expressed three somatic stem cell markers: sal-like 4, CD133, and Musashi-1. Endometriotic stromal cells derived from large CFUs could differentiate into four mesenchymal lineages when cultured in the respective inducing-media, as determined by histochemical staining and RT-PCR of lineage specific markers. These findings demonstrate that ovarian endometrioma contains a subset of cells displaying somatic stem cell properties.

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.

A novel endometriosis inducing factor in women with endometriosis

AIM

To confirm the hypothesis of the presence of a possible endometriosis inducing factor(s) (EIF) in the blood of women with endometriosis.

PATIENTS AND METHODS

Forty infertile women were studied. The study group compromised of fifteen women of each three different degrees of endometriosis and fifteen women without endometriosis as a control group. Stem cells are characterized by being spindle shaped and proliferate in appropriate culture indefinitely. The women sera were co-cultured with mesenchymal stem cells (MSCs) which were followed up weekly to look for morphological changes and to detect Annexin 1 marker and ß-actin gene by reverse transcriptase polymerase chain reaction.

RESULTS

MSCs cultured with sera of cases with, mild, moderate and severe endometriosis, showed morphological changes to be columnar and cuboidal shaped cells -resembling endometrial cells and glands- by the 4th week in 60%, 60% & 100% respectively. These cells were detected from as early as the first week in women with moderate and severe types (20% for each group). The percentage of the change into endometrial like cells increased among the three groups where it was 30±25.8%, 45±29.9% and 75±37.9% respectively. Moreover, increasing number of endometrial like cells are detected weekly, the more severe the disease is. None of the cultures of serum of the control group had made such changes all over the study. Furthermore, with more differentiation there was a considerable decrease in number of stem cells. These differentiated cells expressed the Annexin-1 marker.

CONCLUSION

It was evident that serum of women with endometriosis posses a factor(s) that enables the MSCs to be transformed into endometrial like cells and glands in vitro. This finding supports a new theory for the etiology of endometriosis. This observation may have a tremendous effect on the therapeutic implications of this debilitating condition.

Ectopic endometrium in human foetuses is a common event and sustains the theory of müllerianosis in the pathogenesis of endometriosis, a disease that predisposes to cancer

BACKGROUND

Endometriosis is a gynecological disease defined by the histological presence of endometrial glands and stroma outside the uterine cavity. Women with endometriosis have an increased risk of different types of malignancies, especially ovarian cancer and non-Hodgkin's lymphoma. Though there are several theories, researchers remain unsure as to the definitive cause of endometriosis. Our objective was to test the validity of the theory of müllerianosis for endometriosis, that is the misplacing of primitive endometrial tissue along the migratory pathway of foetal organogenesis

METHODS

We have collected at autopsy 36 human female foetuses at different gestational age. We have performed a morphological and immunohistochemical study (expression of oestrogen receptor and CA125) on the pelvic organs of the 36 foetuses included en-block and totally analyzed.

RESULTS

In 4 out of 36 foetuses we found presence of misplaced endometrium in five different ectopic sites: in the recto-vaginal septum, in the proximity of the Douglas pouch, in the mesenchimal tissue close to the posterior wall of the uterus, in the rectal tube at the level of muscularis propria, and in the wall of the uterus. All these sites are common location of endometriosis in women.

CONCLUSION

We propose that a cause of endometriosis is the dislocation of primitive endometrial tissue outside the uterine cavity during organogenesis.

Pathogenesis of endometriosis: the role of defective 'immunosurveillance'

OBJECTIVE

To analyse the aetiopathogenesis and the role of defective 'immunosurveillance' in endometriosis.

METHOD

Review of studies on the pathogenesis of endometriosis, focusing particularly on novel molecules which express adhesive or proteolytic properties. Hypotheses addressing the role of oxidative stress in endometriosis were also reviewed.

RESULTS

Endometriosis is a multifactorial disease associated with a general inflammatory response aiming to clear the peritoneal cavity from the ectopic endometriotic cells and tissue. Modern theories suggest that this inflammatory response creates an environment that may promote implantation and proliferation due to defective 'immunosurveillance'.

CONCLUSION

The modern interpretation of the theory of reflux menstruation holds that women destined to develop endometriosis have a deficient immune system, which cannot defend against regurgitated endometrial cells. New findings on genetics, immune modulation, and secreted products of endometriotic lesions of affected women have given insight into the pathogenesis of this disorder and may serve as the background for new treatments of endometriosis-associated pain and infertility.

Endométriose et adolescente

Endometriosis has long been considered as a disease of women over 30 years old. However, recent data from the literature demonstrated its high incidence in teenagers. Endometriosis in teenagers is generally associated with chronic pelvic pains and cyclical signs are less common than in adults. The persistence of the pain despite an estroprogestative contraception associated with non-steroidal anti-inflammatory drugs is a strong argument for the diagnosis and justifies a laparoscopic exploration. During this laparoscopy, the search for atypical lesions, which are much more common than typical ones, is essential. Biopsies of these lesions is mandatory in every patient to rule out false positives and false negatives which are common in atypical lesions. The aim of the treatment is to improve the pain. The first line of medical treatment is based on the estroprogestative contraception and non-steroidal anti-inflammatory drugs. The prescription of GnRH should be the ultimate solution because the bone reserve increases until the age of 18 to 20. The laparoscopic treatment, when required, should be as complete as possible. Early diagnosis and medical management may prevent the development of the disease. However, further studies in the teenager are essential to improve the current empirical management.

Stromal cells from endometriotic lesions and endometrium from women with endometriosis have reduced decidualization capacity

OBJECTIVE

To evaluate the phenotype, proliferative, and differentiation capacities in vitro of stromal cells derived from peritoneal, ovarian, and deeply infiltrating endometriosis.

DESIGN

Experimental study using phase contrast microscopy, immunocytochemistry, and functional bioassays.

SETTING

University-based laboratory.

PATIENT(S)

Women with and without endometriosis undergoing surgery for benign indications.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The stability in vitro of stromal cells derived from peritoneal (n = 18), ovarian (n = 29), and deeply infiltrating (n = 14) endometriotic lesions, as well as endometrium from women with (n = 5) and without endometriosis (n = 5) was evaluated by detection of endometrial markers. The proliferative and differentiation capacity of the cells was assessed by the use of cell doubling estimation and in vitro decidualization assays.

RESULT(S)

The expression of the progesterone receptor and CD10 in stromal cells derived from the three types of endometriotic lesions is retained in culture up to passage 10. The doubling time of stromal cells from deeply infiltrating lesions is lower than that of endometrial stromal cells. Levels of prolactin and insulin-like growth factor binding protein-1 (IGFBP-1) are reduced in supernatants from stromal cells derived from the three types of lesions and from the endometrium of women with endometriosis.

CONCLUSION(S)

The peritoneal, ovarian, and deeply infiltrating endometriotic stromal cell lines we describe retain in vivo tissue markers. Loss of differentiation capacity of the endometriotic cell lines and endometrial cells from women with endometriosis may influence the capacity for proliferation and survival of these cells in the ectopic environment.

Structural changes and cell properties of human ovarian surface epithelium in ovarian pathophysiology

The surface epithelial cells of the ovary, which are modified peritoneal cells, form a single, focally pseudostratified layer. The Müllerian ducts differentiate after invagination of the coelomic mesothelium over the gonadal ridges during the 6th week of embryonic life. On the basis of the embryologically putative Müllerian potential of this epithelium, endometriosis can be explained by coelomic metaplasia from the peritoneum, including ovarian surface epithelium. Some pelvic endometriosis specimens have shown that epithelial cells on the ovary or pelvis are serially changed to endometriotic gland cells. Immunohistochemistry as well as scanning electron microscopy also reinforce the light-microscopical findings. A three-dimensional culture system demonstrated that human ovarian surface epithelial cells exhibited a glandular-stromal structure when they were cocultured with endometrial stromal cells in an estrogen-rich environment. Ovarian carcinomas in the epithelial-stromal category are thought to arise from the surface epithelium and its inclusions. The ovarian surface epithelium is physiologically involved in follicular rupture, oocyte release, and the subsequent repair of follicle wall during reproductive age. Simultaneously, ovulation may cause a loss of integrity of the surface epithelium, followed by accumulation of multiple mutations. The cortical invagination, surface stromal proliferation, and Müllerian differentiation of these cells are likely not to be an early step in the cancer development. However, the inclusion cysts are closely related with carcinogenesis because they are significantly more common in ovaries contralateral to those containing epithelial cancers than in control ovaries. As an in vitro study, ovarian carcinoma cell lines were established from simian virus 40 large T antigen-transformed human surface epithelial cells of the ovary. Further investigations of these cell lines may lead to insights into the preneoplastic and early stages of carcinomas. To clarify the pathogenesis of endometriosis and epithelial ovarian cancer, specifically designed studies of ovarian surface epithelium are required.

Augmented cell survival in eutopic endometrium from women with endometriosis: expression of c-myc, TGF-beta1 and bax genes

BACKGROUND

Endometriosis is a common gynaecological disorder characterized by the presence of endometrial tissue outside of the uterus. The fragments in normal menstruation are composed of necrotic and living cells, which do not survive in ectopic locations because of programmed cell death. The aim of this study was to evaluate if the balance between cell proliferation and apoptosis is changed in eutopic endometrium from women with endometriosis throughout the menstrual cycle by studying bax (pro-apoptotic), c-myc (regulator of cell cycle) and TGF-beta1 (involved in cell differentiation) genes.

METHODS

Eutopic endometrium was obtained from: 30 women with endometriosis (32.8 +/- 5 years) and 34 fertile eumenorrheic women (36 +/- 5.3 years). We analyzed apoptosis (TUNEL: DNA fragmentation); cell proliferation (immunohistochemistry (IHC) for Ki67); c-myc, bax and TGF-beta1 mRNA abundance (RT-PCR) and TGF-beta1 protein (IHC) in endometrial explants.

RESULTS

Cell proliferation strongly decreased from proliferative to late secretory phases in glands, but not in stroma, in both endometria. Positive staining in glands and stroma from proliferative endometrium with endometriosis was 1.9- and 2.2-fold higher than control endometrium, respectively (p < 0.05). Abundance of c-myc mRNA was 65% higher in proliferative endometrium from endometriosis than normal tissue (p < 0.05). TGF-beta1 (mRNA and protein) augmented during mid secretory phase in normal endometrium, effect not observed in endometrium with endometriosis. In normal endometrium, the percentage of apoptotic epithelial and stromal cells increased more than 30-fold during late secretory phase. In contrast, in endometrium from endometriosis, not only this increase was not observed, besides bax mRNA decreased 63% versus normal endometrium (p < 0.05). At once, in early secretory phase, apoptotic stromal cells increased 10-fold with a concomitant augment of bax mRNA abundance (42%) in endometria from endometriosis (p < 0.05).

CONCLUSION

An altered expression of c-myc, TGF-beta1 and bax was observed in eutopic endometrium from endometriosis, suggesting its participation in the regulation of cell survival in this disease. The augmented cell viability in eutopic endometrium from these patients as a consequence of a reduction in cell death by apoptosis, and also an increase in cell proliferation indicates that this condition may facilitate the invasive feature of the endometrium.

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.

Increase of activated mast cells in human endometriosis

PROBLEM

The proliferation of stromal cells in endometriosis promotes extensive adhesion; therefore, the morphological analysis of stromal lesions is important in the investigation of the pathogenesis of endometriosis.

METHOD OF STUDY

In this study, the morphological and numeric comparisons of degranulated mast cells were performed between endometriotic lesions and comparative regions (eutopic endometrium and normal uterine serosa) of patients with and without endometriosis.

RESULTS

In cases of endometriosis, diffuse infiltration of numerous mast cells was observed throughout the stromal lesions. These mast cells exhibited degranulation, and scattered granules were also observed. In the eutopic endometrium and normal uterine serosa of both the endometriosis patients and the controls, mast cells were rarely detected.

CONCLUSIONS

These results suggest that an abnormal immune response, specifically a hypersensitivity reaction, is strongly related to endometriosis; our findings will be helpful in the development of methods for the treatment of endometriosis.

Association between endometriosis and genetic polymorphisms of the estradiol-synthesizing enzyme genes HSD17B1 and CYP19

BACKGROUND

Endometriosis, an estrogen-dependent disease, is believed to be influenced by multiple genetic and environmental factors. Here, we evaluated whether the risk and severity of endometriosis are associated with polymorphisms in estradiol-synthesizing enzyme genes: the Ser312Gly polymorphism in 17-beta-hydroxysteroid dehydrogenase type 1 (HSD17B1) and the Arg264Cys polymorphism in cytochrome P450, subfamily XIX (CYP19).

METHODS

All participants underwent diagnostic laparoscopy, and the stage of endometriosis was determined according to the Revised American Fertility Society classification. Of the 138 women enrolled, 59 had no endometriosis, 21 had stage I, 10 had stage II, 23 had stage III and 25 had stage IV. SNPs were discriminated by allele-specific oligonucleotide hybridization.

RESULTS

Individuals having at least one A-allele (A/G or A/A genotype) of HSD17B1 showed a significantly increased risk of endometriosis (A/G genotype: adjusted OR, 3.06; 95%CI 1.21-7.74; A/A genotype: adjusted OR, 3.02; 95%CI 1.08-8.43). There was a significant trend associating A/G + A/A genotypes with severity of endometriosis (P for trend < 0.01). No statistically significant association was found for the CYP19 polymorphism.

CONCLUSIONS

Evidence for association between the Ser312Gly polymorphism in HSD17B1 and endometriosis was found in a Japanese population. The A-allele of HSD17B1 appears to confer higher risk for endometriosis.

Pathogenesis of endometriosis

Many women harbour spots of peritoneal endometriosis without having any symptoms; this is referred to as the phenomenon endometriosis. Some of these women go on to develop symptomatic endometriosis. Although we know the factors potentially involved in the aetiology and pathogenesis of endometriosis, the exact mechanism by which the phenomenon endometriosis develops into the disease endometriosis, with its associated signs and symptoms, remain obscure. The widely accepted theory is Sampson's transplantation theory. Recent findings indicate that certain properties of the endometrium, and the influence of the local environment, are crucial in the development of endometriosis. Early endometriosis lesion formation is described in detail, as this seems to be a key process in the development of peritoneal endometriosis.

Endometriosis from thelarche to midteens: pathogenesis and prognosis, prevention and pedagogy

John Huffman, a founder of the subspecialty of pediatric and adolescent gynecology in North America, first related the diagnosis of endometriosis to thelarche. Subsequently, endometriosis was diagnosed in early puberty between thelarche and menarche. Based on solid evidence, we suggest that the theory of embryonic mullerian rests be added to currently accepted theories of pathogenesis of endometriosis. This article argues for recognition of embryonic mullerian rests as the pathogenesis of some cases of endometriosis not explained by accepted theories. Along with Huffman, we propose that thelarche be recognized as a developmental benchmark, after which endometriosis is included in the differential diagnosis of chronic pelvic pain. Thus, in an effort to refocus research and patient care to early adolescence, this review is limited to endometriosis occurring in young women from thelarche to their sixteenth birthday. Relating endometriosis to thelarche has fundamental implications for pathogenesis, early diagnosis, prognosis, treatment, education, and long-term care of adolescents.

Steroid and cytokine regulation of matrix metalloproteinase expression in endometriosis and the establishment of experimental endometriosis in nude mice

The cyclic expression of matrix metalloproteinases (MMPs) by human endometrium has been suggested to play a role in the invasive process necessary to establish endometriosis. The ability of progesterone exposure to inhibit endometrial MMP-3 and MMP-7 expression requires the local action of TGF beta and may also be linked to the local production of retinoic acid by stromal cells. A continuous expression of several MMPs in endometriotic lesions has been reported, indicating a failure of progesterone or locally produced factors to suppress these enzymes. To address cell-specific MMP regulation associated with endometriosis, we examined expression of MMP-3 and MMP-7 mRNA in eutopic endometrium and endometriotic lesions acquired during the secretory phase of the menstrual cycle. We examined the in vitro regulation of MMP-3 and MMP-7 protein in similar tissues. We also examined the in vitro regulation of MMP secretion by progesterone, retinoic acid, and TGF beta in endometriosis tissues relative to the establishment of experimental disease. Our studies indicate that either eutopic or ectopic tissue from women with endometriosis exhibit patterns of altered MMP regulation in vivo. A lack of responsiveness to progesterone was demonstrated in vitro, associated with a failure to suppress MMP expression and an enhanced ability of the tissue to establish experimental endometriosis. However, in vitro treatments with retinoic acid and TGF beta restored the ability of progesterone to suppress MMPs in vitro and prevented the establishment of experimental disease.

Pathological evaluation of the rat endometriosis model

OBJECTIVE

To observe in detail the morphology of experimental rat endometriosis, specifically in peritoneum adjacent to uterine transplants attached via autotransplantation.

DESIGN

Light and electron microscopic study.

SETTING

Tochigi Institute of Clinical Pathology, Japan.

ANIMAL(S)

Female-SD rats maintained on a schedule of 12 hours of light and 12 hours of dark for 2 weeks.

INTERVENTION(S)

Uterine transplants were attached to rat peritoneum via the surgical autotransplantation technique. The implanted area of peritoneum, including abdominal muscle, were excised from anesthetized rats at four (n = 10), seven (n = 10), and 14 (n = 10) days after uterine autotransplantation. The mesenteries were autotransplanted as a comparative control.

MAIN OUTCOME MEASURE(S)

We examined the morphologic alterations of uterus-attached peritoneum following the time interval after the implantation.

RESULT(S)

In rat endometriosis models, the stromal tissue of uterus-attached peritoneum showed proliferation and infiltration of mast cells, eosinophils, plasma cells, lymphocytes, and macrophages. These lesions increased with time after implantation; however, ultimately these infiltrating cells disappeared and proliferation declined.

CONCLUSION(S)

Our findings suggest that uterine autotransplantation induces the infiltration of allergic inflammatory-related cells and proliferative lesions in peritoneal stroma attached endometrium. These data should prove useful for investigations of human endometriosis.

Theories of endometriosis

Endometriosis is characterised by the presence of abnormally located tissue resembling the endometrium with glands and stroma. Several hypotheses have attempted to explain the development of such tissue. The oldest theory, that of metaplasia, suggests that under diverse influences coelomic tissue could be transformed into endometrium. The most often cited theory, that of implantation, proposes that the physiological phenomenon of endometrial reflux in the fallopian tubes during menstruation may, in certain conditions, overcome local defense mechanisms, implant, and proliferate. The peritoneal fluid in unaffected women possesses the capacity to prevent endometriotic tissue from becoming established. The reasons for the occurrence of endometriosis and its consequences (pain, sterility, adhesions) are probably numerous and involve the endometrium, the immune system (macrophages, natural killer cells), the peritoneum, and fallopian tubes. The failure to clear the peritoneal cavity of fragments of endometrium could cause a state of local inflammation with hyperactivation of macrophages secreting a variety of different compounds. Some of these compounds may bring about metaplasia of the peritoneum or the development of Mullerian residues.

Transforming growth factor-beta isoforms and receptors in endometriotic cysts of the human ovary

PROBLEM

The present study examined the presence and cellular distribution of transforming growth factor-beta1, 2, and 3 isoforms and their type I and II receptors in endometriotic cysts of the ovary, relative to their presence in normal endometrial tissue.

METHOD OF STUDY

Thirteen control samples of normal endometrium in the proliferative phase and 11 ovarian endometriotic cysts were examined by immunohistochemistry for transforming growth factor-beta1, 2, and 3 isoforms and their type I and II receptors.

RESULTS

Immunoreactivity for all ligands and receptors was detected in both normal endometrium and endometriotic cysts. Isoform-specific differences in immunostaining were not detected. Expression of all ligands and receptors was significantly increased in epithelial cells of endometriotic cysts compared with those of normal endometrium. On the other hand, stromal cells in normal endometrium and endometriotic cysts were only faintly immunostained. Inflammatory cells infiltrating among endometriotic stromal cells contained the highest immunostaining intensity for all ligands and receptors. We identified nearly all inflammatory cells as macrophages using a specific antibody.

CONCLUSIONS

These findings suggest that macrophages in endometriotic tissue are a major source of transforming growth factor-beta, which may be an important regulator of cell proliferation in endometriotic cysts through paracrine and autocrine actions.

The putative role of cell adhesion molecules in endometriosis: can we learn from tumour metastasis?

Endometriosis, one of the most frequent diseases in gynaecology, is a considerable threat to the physical, psychological and social integrity of women. The etiology and pathogenesis of this important disease, defined as the ectopic location of endometrium-like glandular epithelium and stroma outside the uterine cavity, is poorly understood. Clinical observations and in vitro experiments imply that endometriotic cells are invasive and able to metastasize. Analogous to tumour metastasis, it is likely that cell adhesion molecules are central for the invasion and metastasis of endometriotic cells. Investigation of these molecules in endometriosis should increase our understanding of the molecular mechanisms involved in the pathogenesis of this disease.

Laparoscopic surgical management of diaphragmatic endometriosis

OBJECTIVE

To review the clinical presentations of and management options for diaphragmatic endometriosis.

DESIGN

Retrospective review.

SETTING

Referral center.

PATIENT(S)

Twenty-four women with endometriosis of the diaphragm.

INTERVENTION(S)

Surgical management.

MAIN OUTCOME MEASURE(S)

Diagnostic accuracy and therapeutic feasibility of operative laparoscopy.

RESULT(S)

Operative findings in 17 patients included 2-5 spots of endometriosis on the diaphragm measuring <1 cm. Seven women had numerous lesions scattered across the diaphragm. Lesions were bilateral in 8 patients, limited to the right hemidiaphragm in 14 patients, and limited to the left hemidiaphragm in 2 patients. In 7 patients, six endometriosis lesions were directly in the line of the left ventricle and three lesions were adjacent to the phrenic nerve. Endometriosis was infiltrating into the muscular layer of the diaphragm in 7 patients. The symptoms in all 7 symptomatic patients decreased significantly after treatment, with a minimum follow-up period of 12 months. No postoperative complications occurred.

CONCLUSION(S)

The abdominal diaphragm can be involved with endometriosis and can be diagnosed and treated effectively with the use of videolaparoscopy.

Peritoneal endometriosis, ovarian endometriosis, and adenomyotic nodules of the rectovaginal septum are three different entities

OBJECTIVE

To review the histogenesis of peritoneal, ovarian, and rectovaginal endometriotic lesions.

DESIGN

The comparison of morphologic, morphometric, and histochemical data observed in each type of lesion.

SETTING

A university hospital department of gynecology.

PATIENT(S)

Patients complaining of infertility or pelvic pain with laparoscopically proved endometriosis.

INTERVENTION(S)

Laparoscopy was performed, and biopsy specimens from the endometriotic lesions were histologically studied.

RESULT(S)

Three types of endometriotic lesions must be considered: peritoneal, ovarian, and rectovaginal. Morphologic and morphometric data show similarities between eutopic endometrium and red peritoneal lesions, suggesting that these lesions are the first stage of early implantation of endometrial glands and stroma. After partial shedding, the red lesions regrow constantly. The shedding induces an inflammatory reaction, provoking scarification, and the lesions become black. The subsequent fibrosis leads to areas of white opacification that are inactive. The pathogenesis of ovarian endometriomas is a source of controversy. Although there seems to be a consensus concerning the invagination theory, there is still a contradiction between the implantation theory and the metaplasia theory. We recently showed that the mesothelium covering the ovary can invaginate into the ovarian cortex, pushing back the primordial follicles. The presence of mesothelial invagination in continuum with endometriotic tissue suggests that metaplastic histogenesis of ovarian endometriotic lesions occurs. Rectovaginal endometriotic nodules must be considered adenomyomas, consisting of smooth muscle with active glandular epithelium and scanty stroma. Immunocytochemical results show poor differentiation and hormonal independence of these lesions and indicate a close relation with their mesodermal müllerian origin.

CONCLUSION(S)

Peritoneal, ovarian and rectovaginal endometriotic lesions must be considered as three separate entities with different pathogeneses.

Intrapelvic injection of menstrual endometrium causes endometriosis in baboons (Papio cynocephalus and Papio anubis)

OBJECTIVE

The Sampson hypothesis of retrograde menstruation as a cause of endometriosis was tested by determining the effect of intrapelvic injection of menstrual versus luteal endometrium on the incidence, peritoneal involvement, and stage of endometriosis.

STUDY DESIGN

Seventeen baboons were injected retroperitoneally with luteal (n = 6) or menstrual (n = 7) endometrium and intraperitoneally with menstrual endometrium (n = 4). Laparoscopies were performed after 2 months in all animals and after 5 and 12 months in six and five primates injected with luteal and menstrual endometrium, respectively.

RESULTS

The peritoneal endometriosis surface area, number of implants, and incidence of typical and red subtle lesions were significantly higher after retroperitoneal injection of menstrual than of luteal endometrium. By use of menstrual endometrium intraperitoneal seeding was more successful in causing endometriosis than was retroperitoneal injection. No significant changes in number or surface area of endometriotic lesions induced with retroperitoneal injection of luteal endometrium after 5 months were observed in the six baboons. At repeat laparoscopy 12 months after intrapelvic injection of menstrual endometrium progression was recorded in three of four regularly cycling animals, whereas regression was evident in one baboon that had become amenorrheic after induction.

CONCLUSION

Intrapelvic injection of menstrual endometrium can cause peritoneal endometriosis and offers experimental evidence supporting the Sampson hypothesis.

The number of proliferating cell nuclear antigen positive cells in endometriotic lesions differs from that in the endometrium. Analysis of PCNA positive cells during the menstrual cycle and in post-menopause

Immunohistochemical expression of proliferating cell nuclear antigen (PCNA) was studied in the endometrium and in endometriotic lesions during the menstrual cycle and in post-menopausal patients. During the menstrual cycle, in the basal layer of the endometrium, an increase in the number of positive indices (PI) of PCNA was observed in epithelial cells from the menstrual phase. It reached a maximum in the proliferative phase and decreased in the secretory phase. However, no change was observed in the stromal cells of the basal layer. In the functional layer of the endometrium, the PI of the epithelial cells showed a high peak in the late proliferative phase, decreased sharply in the secretory phase and remained unchanged thereafter. The PI of the stromal cells in the functional layer showed two peaks, one in the late proliferative and the other in the mid and late secretory phase. In the endometriotic lesions, except for the proliferative phase, the number of PI was significantly higher than that of the corresponding endometrium and no significant changes were observed during the menstrual cycle. In post-menopausal endometriotic lesions, the number of PI was also higher than that of the corresponding endometrium. Thus the numbers of PI differed between the endometrium and endometriotic lesions in the same patients. These results imply that the endometriotic lesions are constantly more proliferative than the endometrium irrespective of the hormonal milieu during both the menstrual cycle and in a post-menopausal environment.