Short-term culture of peritoneum explants confirms attachment of endometrium to intact peritoneal mesothelium

Rectus Abdominis Muscle Endometriosis: A Unique Case Report with a Literature Review

Introduction and importance: Extrapelvic endometriosis, confined exclusively to the body of the rectus abdominis muscle, is a rare form of abdominal wall endometriosis. While its etiopathology remains unclear, it is often diagnosed in healthy women who present with atypical symptoms and localization unrelated to any incision site, or in the absence of a history of endometriosis or previous surgery. Presentation of the case: Here, we describe a unique case of intramuscular endometriosis of the rectus abdominis muscle in a healthy 39-year-old Caucasian woman. The condition was located away from any prior incisional scars and presented without typical symptoms or concurrent pelvic disease, making diagnostic imaging unclear. After partial surgical resection of the endometriotic foci, the diagnosis was confirmed histologically. Progestogen-based supportive medication was initiated to prevent the need for additional surgeries and to reduce the risk of recurrence. After 6 years of follow-up and continued progestogen treatment, the patient remains symptom-free and has shown no recurrence of the disease. Clinical discussion: Endometriosis of the rectus abdominis muscle exhibits specific characteristics in terms of localization, etiopathology, symptomatology, and diagnostic imaging, suggesting that it should be considered a distinct clinical entity. Conclusions: Although rare, primary endometriosis of the rectus abdominis muscle should be included in the differential diagnosis for women of childbearing age. Early diagnosis is essential to avoid delayed recognition, tissue damage, and to minimize the risk of recurrence or malignant transformation. Given the increasing frequency of gynecologic and laparoscopic surgeries worldwide, it is crucial to establish standardized reporting protocols, follow-up timelines, and imaging assessments during specific phases of the menstrual cycle. Standardization will help raise awareness of this disease, and further our understanding of its pathogenesis, risk factors, recurrence patterns, and potential for malignant transformation-factors that are still not fully understood.

Receptive window might be shorter in patients with endometriosis and lesions cyclically prepare for implantation

OBJECTIVE

To investigate whether endometrial receptivity is affected in patients with endometriosis using podocalyxin (PCX) as a functional biomarker and to study how endometriotic lesions display PCX and the potential pathological implications.

DESIGN

We have previously reported that PCX, an anti-adhesion glycoprotein and barrier protector, is dynamically regulated in the endometrium and acts as a key negative regulator of epithelial receptivity. Early in the cycle both luminal epithelium (LE, lining the endometrial surface) and glandular epithelium (GE, residing within the tissue) strongly express PCX, but in the receptive window, PCX is selectively downregulated in LE, switching the endometrial surface to an adhesive state for embryo attachment/implantation; meanwhile, PCX expression is maintained in GE until postreceptivity. Here, we immuno-stained PCX in endometrial tissues and ectopic lesions biopsied across the menstrual cycle from patients with endometriosis (EOS, n = 41), and compared with endometrium of non-endometriosis controls (non-EOS, n = 55). We further investigated how PCX changes observed in ectopic lesions may influence their adhesive capacity.

SETTING

RMIT University, Australia.

PATIENTS

Women without and with endometriosis.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURES

The window of endometrial receptivity might be shorter in patients with endometriosis; ectopic sites in addition downregulate PCX cyclically, mirroring the eutopic endometrial cells in preparing for receptivity to increase their adhesion potential.

RESULTS

Endometrial PCX levels were comparable between non-EOS and EOS early in the cycle, and in both groups, PCX is downregulated in LE during the expected window of receptivity; however, in EOS endometrium, PCX is reduced earlier in GE as if the receptive window were shorter. In endometriotic lesions, PCX was detected in endometrial LE- and GE-like cells plus mesothelial cells enveloping peritoneal organs, but PCX was cyclically lost specifically in LE-like cells and reduced in GE-like cells as seen in the eutopic endometrium, which however may increase their adhesion potential to nearby organs (overlaid by mesothelial cells). This speculation was further corroborated in an in vitro model showing endometrial epithelial cells with lower PCX were indeed more adhesive to mesothelial cells.

CONCLUSION

Endometrial receptivity is subtly affected in patients with endometriosis with a shorter window. Cyclic downregulation of PCX in ectopic sites may have pathological consequences.

Long-Term Maintenance of Viable Human Endometrial Epithelial Cells to Analyze Estrogen and Progestin Effects

There are fewer investigations conducted on human primary endometrial epithelial cells (HPEECs) compared to human primary endometrial stromal cells (HPESCs). One of the main reasons is the scarcity of protocols enabling prolonged epithelial cell culture. Even though it is possible to culture HPEECs in 3D over a longer period of time, it is technically demanding. In this study, we successfully established a highly pure, stable, and long-term viable human conditionally reprogrammed endometrial epithelial cell line, designated as eCRC560. These cells stained positive for epithelial markers, estrogen and progesterone receptors, and epithelial cell-cell contacts but negative for stromal and endothelial cell markers. Estradiol (ES) reduced the abundance of ZO-1 in a time- and dose-dependent manner, in contrast to the dose-dependent increase with the progestin dienogest (DNG) when co-cultured with HPESCs. Moreover, ES significantly increased cell viability, cell migration, and invasion of the eCRC560 cells; all these effects were inhibited by pretreatment with DNG. DNG withdrawal led to a significantly disrupted monolayer of eCRC560 cells in co-culture with HPESCs, yet it markedly increased the adhesion of eCRC560 to the human mesothelial MeT-5A cells. The long-term viable eCRC560 cells are suitable for in vitro analysis of HPEECs to study the epithelial compartment of the human endometrium and endometrial pathologies.

Research advances in drug therapy of endometriosis

Endometriosis is one of the most common benign gynecological disorders in reproductive-aged women. The major symptoms are chronic pelvic pain and infertility. Despite its profound impact on women's health and quality of life, its pathogenesis has not been fully elucidated, it cannot be cured and the long-term use of drugs yields severe side effects and hinders fertility. This review aims to present the advances in pathogenesis and the newly reported lead compounds and drugs managing endometriosis. This paper investigated Genetic changes, estrogen-dependent inflammation induction, progesterone resistance, imbalance in proliferation and apoptosis, angiogenesis, lymphangiogenesis and neurogenesis, and tissue remodeling in its pathogenesis; and explored the pharmacological mechanisms, constitutive relationships, and application prospects of each compound in the text. To date, Resveratrol, Bay1316957, and bardoxifene were effective against lesions and pain in controlled animal studies. In clinical trials, Quinagolide showed no statistical difference with the placebo group; the results of phase II clinical trial of the IL-33 antibody have not been announced yet; clinical trial stage III of vilaprisan was suspended due to drug toxicity. Elagolix was approved for the treatment of endometriosis-related pain, but clinical studies of Elagolix for the pretreatment of patients with endometriosis to before In vitro fertilization treatment have not been fulfilled. The results of a clinical study of Linzagolix in patients with moderate to severe endometriosis-related pain have not been disclosed yet. Letrozole improved the fertility of patients with mild endometriosis. For endometriosis patients with infertility, oral GnRH antagonists and aromatase inhibitors are promising drugs, especially Elagolix and Letrozole.

Establishment of the SIS scaffold-based 3D model of human peritoneum for studying the dissemination of ovarian cancer

Ovarian cancer is the second most common gynecological malignancy in women. More than 70% of the cases are diagnosed at the advanced stage, presenting as primary peritoneal metastasis, which results in a poor 5-year survival rate of around 40%. Mechanisms of peritoneal metastasis, including adhesion, migration, and invasion, are still not completely understood and therapeutic options are extremely limited. Therefore, there is a strong requirement for a 3D model mimicking the in vivo situation. In this study, we describe the establishment of a 3D tissue model of the human peritoneum based on decellularized porcine small intestinal submucosa (SIS) scaffold. The SIS scaffold was populated with human dermal fibroblasts, with LP-9 cells on the apical side representing the peritoneal mesothelium, while HUVEC cells on the basal side of the scaffold served to mimic the endothelial cell layer. Functional analyses of the transepithelial electrical resistance (TEER) and the FITC-dextran assay indicated the high barrier integrity of our model. The histological, immunohistochemical, and ultrastructural analyses showed the main characteristics of the site of adhesion. Initial experiments using the SKOV-3 cell line as representative for ovarian carcinoma demonstrated the usefulness of our models for studying tumor cell adhesion, as well as the effect of tumor cells on endothelial cell-to-cell contacts. Taken together, our data show that the novel peritoneal 3D tissue model is a promising tool for studying the peritoneal dissemination of ovarian cancer.

Potential use of ellagic acid for endometriosis treatment: its effect on a human endometrial cell cycle, adhesion and migration

EA treatment decreases cell adhesion and migration of endometrial cells and alters the progression of an endometrial stromal cell line cycle.

Endometriosis

Pelvic endometriosis is a complex syndrome characterized by an estrogen-dependent chronic inflammatory process that affects primarily pelvic tissues, including the ovaries. It is caused when shed endometrial tissue travels retrograde into the lower abdominal cavity. Endometriosis is the most common cause of chronic pelvic pain in women and is associated with infertility. The underlying pathologic mechanisms in the intracavitary endometrium and extrauterine endometriotic tissue involve defectively programmed endometrial mesenchymal progenitor/stem cells. Although endometriotic stromal cells, which compose the bulk of endometriotic lesions, do not carry somatic mutations, they demonstrate specific epigenetic abnormalities that alter expression of key transcription factors. For example, GATA-binding factor-6 overexpression transforms an endometrial stromal cell to an endometriotic phenotype, and steroidogenic factor-1 overexpression causes excessive production of estrogen, which drives inflammation via pathologically high levels of estrogen receptor-β. Progesterone receptor deficiency causes progesterone resistance. Populations of endometrial and endometriotic epithelial cells also harbor multiple cancer driver mutations, such as KRAS, which may be associated with the establishment of pelvic endometriosis or ovarian cancer. It is not known how interactions between epigenomically defective stromal cells and the mutated genes in epithelial cells contribute to the pathogenesis of endometriosis. Endometriosis-associated pelvic pain is managed by suppression of ovulatory menses and estrogen production, cyclooxygenase inhibitors, and surgical removal of pelvic lesions, and in vitro fertilization is frequently used to overcome infertility. Although novel targeted treatments are becoming available, as endometriosis pathophysiology is better understood, preventive approaches such as long-term ovulation suppression may play a critical role in the future.

Arrangement of myofibroblastic and smooth muscle-like cells in superficial peritoneal endometriosis and a possible role of transforming growth factor beta 1 (TGFβ1) in myofibroblastic metaplasia

PURPOSE

Superficial peritoneal endometriotic (pEM) lesions are composed of endometrial glands and stroma, in addition to a third component-myofibroblasts and smooth muscles (SM)-like cells. The latter develops secondary to a metaplasia. In this study, we characterised the third component cells in pEM according to differentiation markers in different micro-compartments. Furthermore, a possible effect of TGFβ1 on myofibroblastic metaplasia in endometriotic epithelial cells was studied.

METHODS

Seventy-six premenopausal patients were included. Peritoneal biopsies were excised from EM patients (n = 23), unaffected peritoneum (peritoneum from EM patients but without EM components, n = 5/23) and non-EM patients (n = 10). All peritoneal biopsies were immunolabeled for ASMA, calponin, collagen I, desmin, TGFß receptor 1 (R1), R2 and R3 in addition to ultrastructure examination by transmission electron microscopy (TEM) (n = 1). TGFß1 level was measured in peritoneal fluid (PF) (EM, n = 19 and non-EM, n = 13) collected during laparoscopy. Furthermore, TGFß1 effect on myofibroblastic metaplasia was studied in vitro.

RESULTS

At the centre of pEM lesions, calponin immunolabeling outweighs the collagen I while in the periphery the reverse occurs. SM-like cells expressing desmin predominate at the periphery, while ASMA immunolabeling was detectable in all micro-compartments. Both indicate an abundance of myofibroblasts at the centre of pEM lesions and SM-like cells in the periphery. Although activated TGFß1 in PF did not differ between EM and non-EM, it inhibited the cell proliferation of the endometriotic epithelial cells and induced an upregulation in ASMA and collagen IA2 expression as well.

CONCLUSION

The abundance of the myofibroblasts and SM-like cells points to a myofibroblastic metaplasia in pEM. Both cells are differentially arranged in the different micro-compartments of pEM lesions, with increasing cell maturity towards the periphery of the lesion. Furthermore, TGFß1 may play a role in the myofibroblastic metaplasia of the endometriotic epithelial cells. These findings provide a better insight in the micro-milieu in EM lesions, where most of the disease dynamics occur.

Endometriosis

Endometriosis is a common inflammatory disease characterized by the presence of tissue outside the uterus that resembles endometrium, mainly on pelvic organs and tissues. It affects ~5-10% of women in their reproductive years - translating to 176 million women worldwide - and is associated with pelvic pain and infertility. Diagnosis is reliably established only through surgical visualization with histological verification, although ovarian endometrioma and deep nodular forms of disease can be detected through ultrasonography and MRI. Retrograde menstruation is regarded as an important origin of the endometrial deposits, but other factors are involved, including a favourable endocrine and metabolic environment, epithelial-mesenchymal transition and altered immunity and inflammatory responses in genetically susceptible women. Current treatments are dictated by the primary indication (infertility or pelvic pain) and are limited to surgery and hormonal treatments and analgesics with many adverse effects that rarely provide long-term relief. Endometriosis substantially affects the quality of life of women and their families and imposes costs on society similar to those of other chronic conditions such as type 2 diabetes mellitus, Crohn's disease and rheumatoid arthritis. Future research must focus on understanding the pathogenesis, identifying disease subtypes, developing non-invasive diagnostic methods and targeting non-hormonal treatments that are acceptable to women who wish to conceive.

Transforming growth factor β1 enhances adhesion of endometrial cells to mesothelium by regulating integrin expression

Endometriosis is the abnormal growth of endometrial cells outside the uterus, causing pelvic pain and infertility. Furthermore, adhesion of endometrial tissue fragments to pelvic mesothelium is required for the initial step of endometriosis formation outside uterus. TGF-β1 and adhesion molecules importantly function for adhesion of endometrial tissue fragments to mesothelium outside uterus. However, the function of TGF-β1 on the regulation of adhesion molecule expression for adhesion of endometrial tissue fragments to mesothelium has not been fully elucidated. Interestingly, transforming growth factor β1 (TGF-β1) expression was higher in endome-triotic epithelial cells than in normal endometrial cells. The adhesion efficiency of endometriotic epithelial cells to meso-thelial cells was also higher than that of normal endometrial cells. Moreover, TGF-β1 directly induced the adhesion of endometrial cells to mesothelial cells through the regulation of integrin of αV, α6, β1, and β4 via the activation of the TGF-β1/TGF-βRI/Smad2 signaling pathway. Conversely, the adhesion of TGF-β1-stimulated endometrial cells to mesothelial cells was clearly reduced following treatment with neutralizing antibodies against specific TGF-β1-mediated integrins αV, β1, and β4 on the endometrial cell membrane. Taken together, these results suggest that TGF-β1 may act to promote the initiation of endometriosis by enhancing integrin-mediated cell-cell adhesion.

Polychlorinated biphenyl 104 promotes migration of endometrial stromal cells in endometriosis

Polychlorinated biphenyls (PCBs), as part of environmental contaminants, have been proved to be related to endometriosis. This study is to investigate the effect of PCB 104 on cell migration, invasion and resultant gene expression in endometrial stromal cells (ESCs). Fifty-three specimens of eutopic endometrial tissues were collected from twenty-four women with endometriosis (EU-EMS) and twenty-nine women without endometriosis (EU-NON). Both EU-EMS and EU-NON were divided into the PCB 104 exposure group and the control group according to whether they were exposed to PCB 104. Primary cultured ESCs were exposed to PCB 104 at the micro molar doses (2 × 10^-3, 0.2 and 1 μmol/L) and concentrations of 2, 5 and 10 μmol/L in six-well plates. Cell mobility and proliferation assay were used to evaluate the effects of PCB 104 on the migration, invasion and proliferation of ESCs, and the effect of PCB 104 on actin cytoskeleton was also examined by immunofluorescence. Subsequently, the mRNA levels of related genes including matrix metalloproteinase (MMP) -2, -3, -9, -10, E-cadherin, Snail, Slug and tissue inhibitor of metalloproteinase (TIMP) -2 in ESCs were examined by using real-time PCR, as well as protein levels of MMP-3 and MMP-10 were detected by enzyme-linked immunosorbent assay (ELISA). We explored the role of epidermal growth factor receptor (EGFR) in the expression of MMP-3 and MMP-10 induced by PCB 104. Exposure to PCB 104 significantly increased the migration and invasion of ESCs. The mRNA and protein levels of MMP-3 and MMP-10 in ESCs treated with PCB 104 were higher than that in the control, with a dose- and time-dependent manner in mRNA level, while the expression of MMP-2, MMP-9, TIMP-2, E-cadherin, Snail and Slug did not change significantly. Taken together, PCB 104 promotes migration and invasion of ESCs by inducing the expression of MMP-3 and MMP-10, which may involved the EGFR signalling pathway.

Back to the Original Question in Endometriosis: Implantation or Metaplasia?

The pathogenesis of some forms of endometriosis is still controversial. Different research approaches have been used to clarify this issue and an intense debate has derived over the years among scientists. This paper presents and discusses aged and modern ideas derived from various observations in different research areas on this specific topic. More specifically, data derived from histological results, animal studies, anatomical findings and basic research activity are presented.

Although an increasing body of evidence tends to support the implantation theory, which currently represents the most recognized pathogenic model for endometriosis, some aspects of this disease remain obscure and the scientific and medical communities have still not made significant progress in terms of completely elucidating the histogenesis of some forms of the disease.

Endometriosis: Aetiopathogenetic Basis

Endometriosis, defined by the presence of endometrial tissue outside the uterine cavity, is a common condition affecting 10% of women in the reproductive age. Menstrual factors reported to increase risk include dysmenorrhea, early menarche, and shorter cycle lengths. The theory of retrograde menstruation with implantation of endometrial fragments, in conjunction with peritoneal factors to stimulate cell growth is the most widely accepted.

There is a growing body of evidence that immunological factors and angiogenesis play a key role in the pathogenesis of endometriosis. In women with endometriosis, there appears to be an alteration in the function of peritoneal macrophages, natural killer cells and lymphocytes, with production of growth factors and inflammatory mediators in the peritoneal fluid. Survival, adhesion, proliferation, invasion and vascularization of endometrial tissue in abdominal cavity may be the consequence of retrograde menstruation and referred to as implantation theory.

Progress in the diagnosis and management of adolescent endometriosis: an opinion

Increasing evidence indicates that early onset endometriosis (EOE), starting around menarche or early adolescence, may have an origin different from the adult variant, originating from neonatal uterine bleeding (NUB). This implies seeding of naïve endometrial progenitor cells into the pelvic cavity with NUB; these can then activate around thelarche. It has its own pathophysiology, symptomatology and risk factors, warranting critical management re-evaluation. It can also be progressive, endangering future reproductive capacity. This variant seems to be characterized by the presence of ovarian endometrioma. Today, the diagnosis of endometriosis in young patients is often delayed for years; if rapidly progressive, it can severely affect pelvic organs, even in the absence of serious symptoms. Given the predicament, great attention must be paid to symptomatology that is often non-specific, justifying a search for new, simple, non-invasive markers of increased risk. Better use of modern imaging techniques will aid considerably in screening for the presence of EOE. Traditional laparoscopy should be limited to cases in which imaging gives rise to suspicion of severity and a stepwise, minimally invasive approach should be used, followed by medical treatment to prevent recurrence. In conclusion, EOE represents a condition necessitating early diagnosis and stepwise management, including medical treatment.

Macrophages promote the growth and invasion of endometrial stromal cells by downregulating IL-24 in endometriosis

Macrophages play an important role in the origin and development of endometriosis. Estrogen promoted the growth of decidual stromal cells (DSCs) by downregulating the level of interleukin (IL)-24. The aim of this study was to clarify the role and mechanism of IL-24 and its receptors in the regulation of biological functions of endometrial stromal cells (ESCs) during endometriosis. The level of IL-24 and its receptors in endometrium was measured by immunohistochemistry.In vitroanalysis was used to measure the level of IL-24 and receptors and the biological behaviors of ESCs. Here, we found that the expression of IL-24 and its receptors (IL-20R1 and IL-20R2) in control endometrium was significantly higher than that in eutopic and ectopic endometrium of women with endometriosis. Recombinant human IL-24 (rhIL-24) significantly inhibited the viability of ESCs in a dosage-dependent manner. Conversely, blocking IL-24 with anti-IL-24 neutralizing antibody promoted ESCs viability. In addition, rhIL-24 could downregulate the invasiveness of ESCsin vitro. After co-culture, macrophages markedly reduced the expression of IL-24 and IL-20R1 in ESCs, but not IL-22R1. Moreover, macrophages significantly restricted the inhibitory effect of IL-24 on the viability, invasion, the proliferation relative gene Ki-67, proliferating cell nuclear antigen (PCNA) and cyclooxygenase2 (COX-2), and the stimulatory effect on the tumor metastasis suppressor gene CD82 in ESCs. These results indicate that the abnormally low level of IL-24 in ESCs possibly induced by macrophages may lead to the enhancement of ESCs’ proliferation and invasiveness and contribute to the development of endometriosis.

Bone Marrow Stem Cell Chemotactic Activity Is Induced by Elevated CXCl12 in Endometriosis

Endometriosis is an inflammatory gynecological disorder caused by the growth of endometrial tissue outside the uterus. Endometriosis produces chemokines, including CXCL12, that attract bone marrow cells to the lesions. In this study, we describe the expression, localization, and chemotactic activity of CXCL12 in endometriotic lesions. Biopsies were collected both from women with endometriosis undergoing laparoscopy and control endometrium from women without endometriosis. Expression of CXCl12 and CXCR4 messenger RNA was increased approximately 4- and 6-fold, respectively, in endometriosis compared to eutopic endometrium. Immunohistochemistry of lesions revealed that CXCR4 was expressed in the stroma and epithelium in both endometriosis and control eutopic endometrium. The level of CXCR4 protein expression was significantly higher in all cellular compartments of the endometriotic lesions compared to control endometrium. CXCL12 protein expression was also higher in endometriotic lesions and was greatest in the epithelial compartment. CXCL12 was increased more in the condition media of cultured endometriosis than in controls as measured by enzyme-linked immunosorbent assay. Transwell chamber migration was used to demonstrate 2-fold increased chemoattraction of mouse bone marrow stem cells toward CXCL12 in the endometriotic-conditioned medium compared with eutopic endometrium. Our results indicate that a preferential recruitment of stem cells to endometriosis can explain how endometriosis outcompetes eutopic endometrium in recruiting the limited supply of circulating stem cells. The CXCL12/CXCR4 signaling axis is a potential target for the treatment of endometriosis and its associated disorders.

The Presence of Endometrial Cells in Peritoneal Fluid of Women With and Without Endometriosis

To reinforce Sampson's theory of retrograde menstruation in the pathogenesis of endometriosis, proof should be provided that during menstruation endometrial cells are present in peritoneal fluid (PF). We hypothesize that the prevalence of PF samples containing endometrial cells is higher in patients with endometriosis than in controls without endometriosis during menstruation. We selected from our biobank PF samples of 17 reproductive-age women with (n = 9) or without (n = 8) endometriosis who had received a diagnostic laparoscopy for investigation of pain/infertility. Peritoneal fluid had been collected during laparoscopy in the menstrual phase of the cycle, centrifuged, and the resulting pellet was stored at -80°C. About 5-μm sections of frozen PF pellets were stained using the Dako Envision Flex system with primary antibodies against epithelial cell adhesion molecule (Ep-CAM; endometrial epithelial cells), CD10 (endometrial stromal cells), prekeratin (epithelial/mesothelial cells), vimentin (endometrial/mesothelial/immune cells), calretinin (mesothelial cells), and CD68 (macrophages). The PF cells positive for Ep-CAM were detected in 5 of 9 patients with endometriosis and 6 of 8 controls ( P = .62). CD10 stained positively in 6 of the 9 patients with endometriosis and 3 of the 8 controls ( P = .35). Calretinin and prekeratin staining showed the presence of mesothelial cells in all pellets. Vimentin stained approximately 100% of the PF cells. CD68+ macrophages represented >50% of cells in all pellets. The prevalence of PF samples containing endometrial epithelial and stromal cells was not higher in patients with endometriosis than in controls without endometriosis during menstruation. Our findings question the relevance of endometrial cells in PF for the pathogenesis of endometriosis and support the importance of other mechanisms such as immune dysfunction and/or endometrial stem cells.

The involvement of osteopontin and matrix metalloproteinase- 9 in the migration of endometrial epithelial cells in patients with endometriosis

BACKGROUND

Endometriosis, which shares certain characteristics with cancers, may cause abnormal expression of proteins involved in cell migration. Endometrial epithelial cells (EECs) are believed to play an important role in endometriotic migration. The aim of this study was to investigate the relationship between the expression of osteopontin (OPN) and matrix metalloproteinase-9 (MMP-9) in endometriotic migration.

METHODS

We performed primary culture of EECs and investigated the expression of OPN and MMP-9 in EECs regulated by 17beta-estradiol (E2). OPN-specific siRNA interference was used to down-regulate OPN and to explore the corresponding change in MMP-9 expression. Real-time RT-PCR, western blot analysis and flow cytometry were used to determine the expression levels of OPN and MMP-9. Gelatin zymography was performed to observe the enzymatic activity of MMP-9 in conditioned media. Transwell and wound scratch assays were performed to investigate the migration ability of EECs.

RESULTS

The expression levels of OPN and MMP-9 in normal EECs (NEECs) were inferior to those in EECs from patients with endometriosis (EEECs). The expression levels of OPN and MMP-9 from stage III/IV EEECs and secretory-phase EECs were higher than those of stage I/II EEECs or proliferative-phase EECs. The expression levels of OPN and MMP-9 in EEECs were increased by E2 treatment and remarkably decreased by siRNA interference. Active MMP-9 expression increased with E2 treatment and decreased with siRNA treatment in EEECs compared with the same treatments in NEECs. The migratory abilities of EEECs were enhanced after cells were treated with E2; in contrast, these abilities were reduced by siRNA interference. In NEECs, active MMP-9 and cellular migration abilities were only minimally influenced by E2 and siRNA treatment.

CONCLUSIONS

The present study suggests that the up-regulation of MMP-9 via activation of OPN induced by estrogen may correlate with the migration of endometrial epithelial cells in patients with endometriosis.

Increased levels of biglycan in endometriomas and peritoneal fluid samples from ovarian endometriosis patients

In our previous low-density-array gene-expression analysis we found an increased expression of biglycan gene in ovarian endometriosis patients. In the present study we evaluated biglycan expression at the protein level in tissue, serum and peritoneal fluid (PF) from ovarian endometriosis patients, patients with benign ovarian cysts and healthy women. Twenty samples of endometriomas and 27 of control tissues (benign ovarian cysts and eutopic endometrium of healthy women) were obtained laparoscopically or by curettage. Serum and PF samples were collected from 56 ovarian endometriosis patients and 40 controls (patients with benign cysts and healthy women). Tissue biglycan levels and serum and PF biglycan concentrations were determined by Western blotting and ELISA, respectively. Biglycan was detected in endometriomas and in benign cysts tissues but differed in glycosylation levels. The PF biglycan concentrations were significantly increased in ovarian endometriosis patients (mean ± SD=220.3 ± 190.5 pg/mg protein) compared to the whole control group (101.9 ± 94.7 pg/mg protein, p<0.001), while serum concentrations did not differ significantly. Biglycan appears to be involved in ovarian pathologies and probably has different roles in benign cysts as compared to ovarian endometriomas.

Selective inhibition of prostaglandin E2 receptors EP2 and EP4 inhibits adhesion of human endometriotic epithelial and stromal cells through suppression of integrin-mediated mechanisms

Endometriosis is a chronic gynecological disease of reproductive age women characterized by the presence of functional endometrial tissues outside the uterine cavity. Interactions between the endometriotic cells and the peritoneal extracellular matrix proteins (ECM) are crucial mechanisms that allow adhesion of the endometriotic cells into peritoneal mesothelia. Prostaglandin E2 (PGE2) plays an important role in the pathogenesis of endometriosis. In previous studies, we have reported that selective inhibition of PGE2 receptors PTGER2 and PTGER4 decreases survival and invasion of human endometriotic epithelial and stromal cells through multiple mechanisms. Results of the present study indicates that selective inhibition of PTGER2- and PTGER4-mediated PGE2 signaling 1) decreases the expression and/or activity of specific integrin receptor subunits Itgb1 (beta1) and Itgb3 (beta3) but not Itgb5 (beta5), Itga1 (alpha1), Itga2 (alpha2), Itga5 (alpha5), and Itgav (alphav); 2) decreases integrin-signaling components focal adhesion kinase or protein kinase 2 (PTK2) and talin proteins; 3) inhibits interactions between Itgb1/Itgb3 subunits, PTK2, and talin and PTGER2/PTGER4 proteins through beta-arrestin-1 and Src kinase protein complex in human endometriotic epithelial cells 12Z and stromal cells 22B; and 4) decreases adhesion of 12Z and 22B cells to ECM collagen I, collagen IV, fibronectin, and vitronectin in a substrate-specific manner. These novel findings provide an important molecular framework for further evaluation of selective inhibition of PTGER2 and PTGER4 as potential nonsteroidal therapy to expand the spectrum of currently available treatment options for endometriosis in child-bearing age women.

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

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

Inhibition of IDO1 suppresses cyclooxygenase-2 and matrix metalloproteinase-9 expression and decreases proliferation, adhesion and invasion of endometrial stromal cells

Indoleamine 2,3-dioxygenase-1 (IDO1) is an intracellular enzyme that catalyses essential amino acid tryptophan along the kynurenine pathway. The aim of this study was to determine the impact of IDO1 expression on the biological characteristic of the endometrial stromal cells (ESCs). IDO1, cyclooxygenase-2 (COX-2) and matrix metalloproteinases (MMPs) in endometriotic ectopic stromal cells, endometriosis-derived eutopic stromal cells and normal ESCs (control) were detected by the in-cell Western analysis. After being treated with lipopolysaccharide, levo-1-methyl-tryptophan (L-1-MT) alone or a combination, a comparative analysis of the above protein expression was evaluated. The effects of IDO1 on ESCs proliferation, adhesion and invasion were detected through ELISA, adhesion assay and Matrigel invasion assay, respectively. The results showed that, contrary to healthy ESCs from control women, the expression of IDO1 was significantly higher in eutopic and ectopic ESCs obtained from women with endometriosis. Inhibition of IDO1 by L-1-MT suppressed the expression of COX-2 and MMP-9 in ESCs. It could also decrease the ESCs proliferation, adhesion and invasion, while stimulating ESCs decidualization. Thus, IDO1 is possibly involved in endometriosis pathogenesis via promoting COX-2 and MMP-9 expression and regulation of ESCs biological characteristics. The information may be useful for developing a new therapeutic strategy for endometriosis.

CD82 gene suppression in endometrial stromal cells leads to increase of the cell invasiveness in the endometriotic milieu

Tetraspanin CD82 is a wide-spectrum tumor metastasis suppressor that inhibits motility and invasiveness of cancer cells. Endometriosis is a benign gynecological disorder, but appears malignant behaviors including invasion, ectopic implantation and recurrence. This study is to elucidate the role of CD82 expression regulation in the pathogenesis of endometriosis. The short interfering RNA silence was established to analyze the roles of CD82, chemokine CCL2, and its receptor CCR2 in the invasiveness of endometrial stromal cells (ESCs). We have found that the mRNA and protein levels of CD82 in the primary normal ESCs from endometrium without endometriosis are significantly higher than that of the primary ESCs from eutopic endometrium and ectopic tissue. CD82 inhibits the invasiveness of ESCs by downregulating CCL2 secretion and CCR2 expression via mitogen-activated protein kinase (MAPK) and integrinβ1 signal pathway, and in turn upregulating the expression of TIMP1 and TIMP2 in an autocrine manner. The combination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with 17β-estradiol can promote the invasion of ESCs via suppressing CD82 expression and stimulating CCL2 secretion and CCR2 expression, and the enhanced interaction of CCL2-CCR2 recruits more macrophages into the ectopic milieu in a paracrine manner, which further downregulates CD82 expression in the ectopic ESCs. Our study has demonstrated for the first time that the abnormal lower CD82 expression in ESCs induced by TCDD and estrogen may be an important molecular basis of endometriosis pathogenesis through enhancing the CCL2 secretion and CCR2 expression and the invasion of ESCs via MAPK and integrinβ1 signal pathway.

Colony-stimulating factor-1 exerts direct effects on the proliferation and invasiveness of endometrial epithelial cells

Although macrophage colony-stimulating factor (CSF-1) has been suggested to play a role in maintaining the chronic inflammatory response in endometriosis, our data suggest that CSF-1 may also play a role in early endometriosis lesion formation. We have shown that CSF-1, in an autocrine fashion, has a direct effect on endometrial epithelial cell proliferation and attachment to peritoneal mesothelial cells, early steps in endometriosis lesion formation on the peritoneum.

Inhibition of CD44 N- and O-linked glycosylation decreases endometrial cell lines attachment to peritoneal mesothelial cells

The attachment of endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs) to peritoneal mesothelial cells (PMCs) with and without inhibition of N- and O-linked glycosylation, the viability of EECs and ESCs, and the expression of CD44 surface density were evaluated. Inhibition of CD44 N- and O-linked glycosylation by using tunicamycin and/or B-GalNAc statistically significantly inhibited endometrial cell attachment to peritoneal mesothelial cells, suggesting a role in establishment of early endometriotic lesions.

Basal and steroid hormone-regulated expression of CXCR4 in human endometrium and endometriosis

Endometriosis is associated with activation of local and systemic inflammatory mechanisms, including increased levels of chemokines and other proinflammatory cytokines. We have previously reported increased gene expression of chemokine receptor 4 (CXCR4), the receptor for CXCL12, in lesions of the rat model of endometriosis. The CXCR4-CXCL12 axis has been shown to have both immune (HIV infection, lymphocyte chemotaxis) and nonimmune functions, including roles in tissue repair, angiogenesis, invasion, and migration. There is evidence indicating that these mechanisms are also at play in endometriosis; therefore, we hypothesized that activation of the CXCR4-CXCL12 axis could be responsible, at least in part, for the survival and establishment of endometrial cells ectopically. Immunohistochemistry (IHC) showed that CXCR4 protein levels were significantly higher in endometriotic lesions compared to the endometrium of controls. Next, we determined basal gene and protein expression of CXCR4 and CXCL12 and regulation by estradiol (E2) and/or progesterone (P4) in endometrial cell lines using quantitative polymerase chain reaction (qPCR), and Western blots. Basal CXCR4 gene expression levels were higher in epithelial versus stromal cells; conversely, CXCL12 was expressed at higher levels in stromal vs epithelial cells. CXCR4 gene expression was significantly downregulated by ovarian steroid hormones in endometrial epithelial. These data suggest that steroid modulation of CXCR4 is defective in endometriosis, although the specific mechanism involved remains to be elucidated. These findings have implications for future therapeutic strategies specifically targeting the inflammatory component in endometriosis.

Peroxisome-proliferator activator receptor-gamma activation decreases attachment of endometrial cells to peritoneal mesothelial cells in an in vitro model of the early endometriotic lesion

The aim of this study was to investigate whether peroxisome proliferator-activated receptor (PPAR)-gamma activation has an effect on the attachment of endometrial cells to peritoneal mesothelial cells in a well-established in vitro model of the early endometriotic lesion. The endometrial epithelial cell line EM42 and mesothelial cell line LP9 were used for this study. EM42 cells, LP9 cells or both were treated with the PPAR-gamma agonist ciglitazone (CTZ) at varying concentrations (10, 20 and 40 microM) x 48 h with subsequent co-culture of EM42 and LP9 cells. The rate of EM42 attachment and invasion through LP9 cells was then assessed and compared with control (EM42 and LP9 cells co-cultured without prior treatment with CTZ). Next, attachment of CTZ-treated and untreated EM42 cells to hyaluronic acid (HA), a cell adhesion molecule (CAM) on peritoneal mesothelial cells, were assessed. Although there was no difference in EM42 attachment when LP9 cells alone were treated with CTZ, treatment of EM42 cells with 40 microM CTZ decreased EM42 attachment to LP9 cells by 27% (P < 0.01). Treatment of both EM42 and LP9 cells with 40 microM CTZ decreased EM42 attachment to LP9 by 37% (P < 0.01). Treatment of EM42 cells with 40 microM CTZ decreased attachment to HA by 66% (P = 0.056). CTZ did not decrease invasion of EM42 cells through the LP9 monolayer. CTZ may inhibit EM42 cell proliferation. In conclusion, CTZ significantly decreased EM42 attachment to LP9 cells and HA in an in vitro model of the early endometriotic lesion.

Reviews: in vitro models to study the pathogenesis of endometriosis

Several in vitro models that attempt to replicate the intraperitoneal environment have been developed to study the pathogenesis of endometriosis. The chicken chorioallantotic membrane has been used, but it has not been well characterized and may introduce some species specific variables. In vitro models using human tissues include amniotic membrane, human peritoneal explants, and cell culture monolayers. These models have been used to qualitatively, quantitatively, and temporally assess attachment of endometrial cells to peritoneal mesothelial and subsequent transmesothelial invasion. These models have also been used to assess the role of cytokines in the development of the early endometriotic lesion. Two- and three dimensional invasion chamber models have been utilized to assess endometrial cell interactions with peritoneal mesothelial cells and the extracellular matrix. Invasion models are also useful to evaluate novel therapeutic approaches. This review will focus on the above models to assist reproductive scientists interested in the pathogenesis of endometriosis.

MMP-2 functions as an early response protein in ovarian cancer metastasis

The most common site (80%) of ovarian cancer metastasis is the omentum, a large (15 x 10 x 2 cm) peritoneal fold covering the small bowel. Because of the absence of model systems that accurately reproduce the microenvironment of the human omentum, the biological mechanism of early ovarian cancer metastasis is poorly understood. Using a new organotypic 3D culture of the omentum, we show that when cancer cells adhere, matrix-metalloproteinase (MMP)-2 is upregulated and proteolytically activated in these cells. The activated MMP-2 cleaves the matrix proteins fibronectin, vitronectin and collagen I into smaller fragments. The cleaved extra-cellular matrix (ECM) fragments then facilitate and accelerate cancer cell adhesion and invasion by binding to their cognate integrin receptors. In vivo inhibition of MMP-2 before adhesion by using a siRNA or a blocking antibody significantly reduced the number of metastasis and tumor weight in a xenograft mouse model. After metastasis had been established, blocking MMP-2 produced less of an effect. Our data identify tumor-derived proteolytically active MMP-2 as an early regulator of ovarian cancer metastasis.

Endometrial stromal cells from women with endometriosis reveal peculiar migratory behavior in response to ovarian steroids

OBJECTIVE

To evaluate differences in endometrial stromal cell (ESC) migration between patients with and without endometriosis.

DESIGN

Differences in ESC migration, cellular morphology, and cytoskeletal-actin dynamics were evaluated in response to platelet-derived growth factor-BB (PDGF-BB) and steroid hormones (17beta-estradiol and progesterone).

SETTING

Medical school research laboratory.

PATIENT(S)

Endometrial biopsy samples obtained from 43 women: 23 as controls (endometriosis excluded by laparoscopy), 20 with severe or moderate endometriosis (diagnosed by laparoscopy).

INTERVENTION(S)

ESCs were treated with and without PDGF-BB, 17beta-estradiol, and progesterone.

MAIN OUTCOME MEASURE(S)

Cellular migration was evaluated by means of chemotaxis experiments in a Boyden chamber. Cellular morphology and cytoskeletal-actin dynamics were evaluated by immunofluorescence.

RESULT(S)

Progesterone stimulated the migratory behavior of ESCs derived from women with endometriosis, while 17beta-estradiol could stimulate motility of ESCs derived from both controls and women with endometriosis, with a greater effect observed in the latter group. No difference in ESC migratory behavior after PDGF-BB treatment was observed between women with and without the disease. Also, PDGF-BB and steroid hormones could modify the organization of actin cytoskeletal structures.

CONCLUSION(S)

Ovarian steroids differently affect the migration of ESCs derived from women with and without endometriosis. This effect is likely to involve cytoskeletal reorganization. Nongenomic signaling pathways induced by steroid hormones might have a role in this phenomenon.

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.

[Pathogenesis of endometriosis]

Endometriosis, defined by the development of endometrial tissue outside the uterus, is a benign disease responsible for infertility and pelvic pain. The diagnosis based on a detailed gynecological history and a careful clinical examination should be done as early as possible in order to treat patients correctly. Medical treatment is not appropriate in all cases and surgical treatment should be proposed but morbidity is related to the severity of the lesion. Ectopic implantation of endometrial cells needs complex interactions between host tissue and epithelial endometrial cells. The conditions for the development of endometriosis are estrogeno-dependent growth of endometrial cells, induction of angiogenesis and lymphangiogenesis. Principal cellular and molecular factors of angiogenesis, lymphangiogenesis and fibrosis should be identified in order to develop new therapeutic strategies of endometriosis.

The relationship between microvessel density, proliferative activity and expression of vascular endothelial growth factor-A and its receptors in eutopic endometrium and endometriotic lesions

Studies were performed to elucidate the possible relationship between microvessel density, proliferative activity and angiogenesis in eutopic endometrium from women with and without endometriosis and peritoneal endometriotic lesions. The question whether changes in these parameters in endometriotic lesions were reflected by the level of vascular endothelial growth factor-A (VEGF-A) in serum and peritoneal fluid was also studied. Biopsy specimens of both eutopic endometrium and peritoneal endometriotic lesions from women with endometriosis (n = 25) as well as eutopic endometrium from women without endometriosis (n = 14) were analysed immunohistochemically regarding microvessel density, proliferative activity, and expression of VEGF-A and its receptors vascular endothelial growth factor receptors 1 and 2 (VEGFR-1 and VEGFR-2) in stroma, glands and blood vessels. The VEGF-A concentration was measured in peritoneal fluid and serum. Secretory phase eutopic endometrium from women with endometriosis had significantly higher microvessel density, expression of VEGF-A in glandular epithelium and VEGFR-2 in endometrial blood vessels than those from women without endometriosis. Endometriotic lesions with high proliferative activity had a higher microvessel density and showed higher vascular expression of VEGFR-2 as well as being accompanied by higher levels of VEGF-A in peritoneal fluid and serum, compared with lesions with low proliferative activity. In conclusion, there seems to be a dysregulation of angiogenic activity in the eutopic endometrium of women with endometriosis and endometriotic lesions with high proliferative activity were accompanied by higher local angiogenic activity and higher levels of VEGF in serum and peritoneal fluid.

Endometriosis: epidemiology and aetiological factors

Estimates of the frequency of endometriosis vary widely. Based on the few reliable data, the prevalence of the condition can reasonably be assumed to be around 10%. Although no consistent information is available on the incidence of the disease, temporal trends suggest an increase among women of reproductive age. This could be explained-at least in part-by changing reproductive habits. Numerous epidemiological studies have indicated that nulliparous women and women reporting short and heavy menstrual cycles are at increased risk of developing endometriosis; data on other risk factors are less consistent. These epidemiological findings strongly support the menstrual reflux hypothesis. Additional evidence in favour of this theory includes the demonstration of viable endometrial cells in the menstrual effluent and peritoneal fluid, experimental implantation and growth of endometrium within the peritoneal cavity, observation of some degree of retrograde menstruation in most women undergoing laparoscopy during menses, and an association between obstructed menstrual outflow and endometriosis.

The role of endometrium in endometriosis

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterus. Several theories have been proposed to explain the pathogenesis of this disease. According to Sampson's retrograde menstruation theory, endometrial cells are refluxed through the fallopian tubes during the menstruation and implant onto peritoneum or pelvic organs. Since retrograde menstruation is a very common phenomenon among women of reproductive age, there must be other factors that may contribute to the pathophysiology and/or pathogenesis of endometriosis. Genetic predisposition, environmental factors, and alterations in immune and endocrine functions are believed to play significant roles in the establishment and maintenance of endometriosis. Although the eutopic endometriums of women with and without endometriosis are histologically similar, studies revealed that there are many fundamental differences between these two tissues. Invasive properties, decreased apoptosis, alterations in expression of specific gene and proteins, and increased steroid and cytokine production have been identified in eutopic endometrium of women with endometriosis. Furthermore, significant biochemical differences exist even between ectopic and autologous eutopic endometrium. These differences can be explained by the direct effects of an inflammatory peritoneal environment.

Vascular endothelial growth factor and matrix metalloproteinase-2 expedite formation of endometriosis in the early stage ICR mouse model

OBJECTIVE

To establish a mouse model for endometriosis and to evaluate roles of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP-2) in the formation of disease.

DESIGN

Experimental laboratory study.

SETTING

A women's hospital in China.

PATIENT(S) AND ANIMAL(S)

Ten women with endometriosis and 10 control women, as well as ICR mice.

INTERVENTION(S)

Endometrial fragments were transplanted in the peritoneal cavities of mice at minilaparotomy. Transplants were observed and then removed for the assessment of morphology and immunohistochemical staining of VEGF and MMP-2.

MAIN OUTCOME MEASURE(S)

Observation of transplants, expression of VEGF and MMP-2.

RESULT(S)

On days 1 and 2, glandular and stromal cells were viable at the margins of transplants. On day 3, the transplants were surrounded by mesothelial cells, and the endometrial glands and stromal cells were clearly viable at the interface. The scores of VEGF and MMP-2 of viable glandular cells of transplants were increased compared with the ones before transplantation. The scores of VEGF and MMP-2 of transplants from women with endometriosis were higher than those of control women.

CONCLUSION(S)

Endometrial transplants from the patients with endometriosis express more VEGF and MMP-2 than endometrium in control women, suggesting that VEGF and MMP-2 may expedite the formation of endometriosis in its early stage.

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.

Effects of combined 17beta-estradiol with TCDD on secretion of chemokine IL-8 and expression of its receptor CXCR1 in endometriotic focus-associated cells in co-culture

BACKGROUND

Chemokines play an important role in the pathogenesis of endometriosis. In the present study, the transcription of 18 chemokine receptors in eutopic endometrium and ectopic tissue with endometriosis was first analysed by RT-PCR. Dioxin, an air pollutant, and estrogen are reported to be associated with endometriosis. The regulatory mechanisms of dioxin and estrogen in the expression of CXCR1/IL-8 in the corresponding cells will help in elucidating roles of the chemokine in the aetiology of endometriosis.

METHODS AND RESULTS

CXCR1, a type of chemokine receptor, was over-expressed in endometriotic tissue. The high translation of the receptor and its ligand, interleukin (IL-8), in endometriotic tissue was then demonstrated by immunochemistry. Estradiol and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alone inhibited expression of CXCR1, whereas the combination of estradiol with TCDD up-regulated the expression. TCDD promoted IL-8 secretion by human pelvic mesothelial cells (HPMC), and 17beta-estradiol magnified the stimulatory effect. Both 17beta-estradiol and TCDD alone inhibited IL-8 secretion of U937 (a cell line of monocyte), but combination of 17beta-estradiol and TCDD had no further inhibitory effect. The co-culture of endometrial stromal cells (ESC) with HPMC produced more IL-8 than respective or total production of either of the cells alone, and estradiol played a synergistic stimulatory role with TCDD in IL-8 secretion of the co-culture. Interaction of HPMC and the monocytes significantly stimulated IL-8 secretion, suggesting a main resource of IL-8 in peritoneal cavity with endometriosis. TCDD promoted IL-8 secretion by HPMC-U937 co-culture, but exerted a contrary effect for IL-8 secretion when combined with estradiol.

CONCLUSION

Estradiol and TCDD in the peritoneal cavity can lead to a persistent and serious inflammation, which gives a new insight into the interactions of estrogen and TCDD in endometriosis.

Elevated levels of fibroblast growth factor-2 in serum from women with endometriosis

OBJECTIVE

The purpose of this study was to determine whether serum and peritoneal fluid levels of fibroblast growth factor-2 (FGF-2) differ between women with and without endometriosis and to examine the relationship between proliferative activity in the endometriotic lesions and the levels of FGF-2 in serum and peritoneal fluid.

STUDY DESIGN

Biopsy specimens of peritoneal endometriotic lesions (n = 25) were analyzed immunohistochemically regarding proliferative activity in stroma, glands, and blood vessels. The FGF-2 concentration was measured in peritoneal fluid and serum from 25 women with endometriosis and 14 healthy controls.

RESULTS

Patients with endometriosis had higher serum concentrations of FGF-2 during both the proliferative and secretory menstrual phases than healthy women. Peritoneal fluid levels of FGF-2 differed significantly between women with high and low proliferative activity in their endometriotic lesions.

CONCLUSION

Women with endometriosis have a higher serum level of FGF-2 than healthy controls.

A novel in vitro model of the early endometriotic lesion demonstrates that attachment of endometrial cells to mesothelial cells is dependent on the source of endometrial cells

OBJECTIVE

To characterize the source of variability in endometrial stromal cell (ESC) binding to peritoneal mesothelial cells (PMC).

DESIGN

In vitro study.

SETTING

University medical center.

PATIENT(S)

Reproductive-age women without endometriosis undergoing surgery for benign conditions.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Binding of ESCs (n = 9) to PMCs collected from the anterior abdominal wall (AAW) (n = 5), a commercially available mesothelial cell line (LP9) (three different passages) and normal ovarian surface epithelium (NOSE) (n = 5).

RESULT(S)

There were no differences in the binding of same-source ESCs to mesothelial cells obtained from the AAW of different women, to different passages of LP9s or to NOSE of different women. There was a trend toward increased binding of ESCs to NOSE compared to AAW PMCs. In contrast, there were significant differences in the ability of ESCs obtained from different women to bind to same-source PMCs.

CONCLUSION(S)

There is significant variability in ESC binding to PMCs. This variation is dependent primarily on the source of the ESCs. The ESC binding to LP9 PMCs was similar to AAW PMCs and NOSE.

Defining endometrial cells: the need for improved identification at ectopic sites and characterization in eutopic sites for developing novel methods of management for endometriosis

Endometriosis is classically defined as ectopic growth of endometrial glands and stroma. Currently, histologic confirmation of laparoscopic findings is paramount for diagnosis of endometriosis and evidence is evolving suggesting that the pathogenesis of endometriosis is related to endometrial anomalies.

Tumour necrosis factor-alpha, interleukin-6 and interleukin-8 do not promote adhesion of human endometrial epithelial cells to mesothelial cells in a quantitative in vitro model

BACKGROUND

A key factor in the pathogenesis of endometriosis is the endometrial-peritoneal adhesion. To study the pathogenesis of endometriosis, a quantitative in vitro assay (QIVA) was developed to measure in vitro adhesion between human endometrial epithelial cells and mesothelial cells using commercially available cell lines. Using the QIVA, the hypothesis was tested that tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8) promote adhesion of endometrial epithelial cells to mesothelial cells.

METHODS

Mesothelial cells were pre-treated with TNF-alpha, IL-6 or IL-8 in various concentrations (ranging from 0 to 1000 IU/ml) for 24 h. Confluent endometrial epithelial cells were labelled with [35S]methionine, added to the confluent mesothelial cells and incubated for 1 h. After incubation, non-adhering cells were removed and adherent cells were solubilized and their [35S]methionine radioactivity was counted to quantify the adherence of endometrial epithelial cells to mesothelial cells.

RESULTS

The in vitro adhesion of human endometrial epithelial cells to human mesothelial cells was inhibited in a dose-dependent manner by TNF-alpha (P=0.0007), IL-6 (P<0.0001) and IL-8 (P=0.0004).

CONCLUSIONS

Using a quantitative in vitro adhesion assay, we were unable to confirm our hypothesis that TNF-alpha, IL-6 and IL-8 promote the in vitro adhesion between endometrial epithelial cells and mesothelial cells.