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

Immune pathway through endometriosis to ovarian cancer

Endometriosis is an estrogen-dependent inflammatory disease, defined by the presence of functional endometrial tissue outside of the uterine cavity. This disease is one of the main gynecological diseases, affecting around 10%-15% women and girls of reproductive age, being a common gynecologic disorder. Although endometriosis is a benign disease, it shares several characteristics with invasive cancer. Studies support that it has been linked with an increased chance of developing endometrial ovarian cancer, representing an earlier stage of neoplastic processes. This is particularly true for women with clear cell carcinoma, low-grade serous carcinoma and endometrioid. However, the carcinogenic pathways between both pathologies remain poorly understood. Current studies suggest a connection between endometriosis and endometriosis-associated ovarian cancers (EAOCs) via pathways associated with oxidative stress, inflammation, and hyperestrogenism. This article aims to review current data on the molecular events linked to the development of EAOCs from endometriosis, specifically focusing on the complex relationship between the immune response to endometriosis and cancer, including the molecular mechanisms and their ramifications. Examining recent developments in immunotherapy and their potential to boost the effectiveness of future treatments.

The Expression of Kisspeptins and Matrix Metalloproteinases in Extragenital Endometriosis

Endometriosis is characterized by a condition where endometrial tissue grows outside the uterine cavity. The mechanisms of endometrium growth during endometriosis might be similar to the development of a tumor. The kisspeptin (KISS1) gene was initially discovered as a suppressor of metastasis. Matrix metalloproteinases (MMPs) and their inhibitors are described as factors in the early stages of endometriosis and tumor growth progression. We applied the quantitative polymerase chain reaction and the immunofluorescence method to investigate KISS1, its receptor (KISS1R), MMP-2, and MMP-9 in the eutopic and ectopic endometrium in women with and without endometriosis. We presume that the dysregulation of KISS1 and MMPs might contribute to endometriosis pathogenesis. Samples for the immunofluorescence study were collected from patients with a confirmed diagnosis of endometriosis in stages I-IV, aged 23 to 38 years old (n = 40). The cell line was derived from the endometrium of patients with extragenital endometriosis (n = 7). KISS1 and KISS1R expression are present in the ectopic endometrium of patients with extragenital endometriosis, as opposed to the control group where these proteins were not expressed. There is a decrease in KISS1 and KISS1R values at all stages of endometriosis. MMP-2 and MMP-9 genes express statistically significant increases in stages II, III, and IV of extragenital endometriosis. MMP synthesis increased in the last stages of endometriosis. We suppose that the KISS1/KISS1R system can be used in the future as a suppressive complex to reduce MMP-2 and MMP-9 expression and prevent endometrial cells from invading.

Serum kisspeptin levels in deep-infiltrating, ovarian, and superficial endometriosis: A prospective observational study

The diagnosis of endometriosis may delay for many years due to non-deterministic symptoms and avoiding surgical interventions. Kisspeptins are hormones that interact with endometrial tissue to limit invasions during placentation and various cancers and are suggested to be also associated with endometriosis. This study evaluated if serum kisspeptin levels are associated with the invasion depth in endometriosis. Forty patients between 18 and 45 years of age and admitted to a tertiary-care Obstetrics and Gynecology Department between 2020 and 2021 with a diagnosis of endometriosis, and 40 patients without endometrioma were included in the study. Demographic, obstetric, clinical, and biochemical characteristics were evaluated in patients with superficial (SE) and deep infiltrating (DIE) endometriosis and healthy controls. Twenty patients (50%) had SE, 14 (35%) had DIE, and 22 (55%) had endometrioma in the patient group. Fertility rates were higher among controls, but similar between patients with SE and DIE. CA125 levels were significantly higher in the DIE group. SE and DIE groups had similar kisspeptin values, significantly higher than controls. CA125 and kisspeptin levels were not correlated in study groups. Serum kisspeptin levels were significantly different between endometriosis patients and healthy controls. However, kisspeptin levels were unable to differentiate endometriosis severity. Our results suggest that kisspeptins might play a role in the pathogenesis of endometriosis, which needs further assessment in more comprehensive studies.

KRAS Mutation in Endometriosis-Associated Ovarian Borderline and Malignant Epithelial Tumors

Background: Endometriosis is a common disease among women with the capacity to transform into ovarian neoplasms. KRAS mutation is a keystone in tumor-genesis of many malignant neoplasms. Objectives: In the current study, we investigated KRAS mutations in endometriosis-associated ovarian borderline and malignant epithelial tumors. Methods: The specimens of 42 consecutive patients undergoing a surgical procedure whose final diagnosis comprised endometriosis-associated borderline and malignant epithelial ovarian tumors including 12 borderline epithelial tumors and 30 ovarian epithelial carcinomas were histopathologically reviewed. All cases were evaluated regarding the type of tumor, differentiation and simultaneous presence of endometriosis or atypical endometriosis. DNA extraction from the selected paraffin block was done and mutation of codons 12 and 13 was assessed. Results: Due to the quality of genomic DNA for PCR study was not acceptable in 6 out of 42 cases, among remaining 36 cases, KRAS mutation was observed in 6 cases including 2 cases with mutations in 2nd base of 12th codon (G→T), 3 cases with substitution of G→A in the 2nd base of 12th codon, and one with substitution of G→T in the 1st base of 12th codon. Conclusions: We evaluated the KRAS mutation in the spectrum of ovarian epithelial tumors associated with endometriosis for treatment approaches including targeted therapies. Our results suggested a possible link between KRAS mutation and endometriosis-associated ovarian borderline and malignant tumors but there was no convincing evidence to prove a definite linkage.

Epithelial Cells of Deep Infiltrating Endometriosis Harbor Mutations in Cancer Driver Genes

Endometriosis is an inflammatory condition manifested by the presence of endometrial-like tissue outside of the uterine cavity. The most common clinical presentations of endometriosis are dysmenorrhea, infertility, and severe pelvic pain. Few hypotheses attempt to explain the pathogenesis of endometriosis; however, none of the theories have been fully confirmed or considered universal. We examined somatic mutations in eutopic endometrium samples, deep endometriotic nodules and peripheral blood from 13 women with deep endometriosis of the rectovaginal space. Somatic variants were identified in laser microdissected samples using next-generation sequencing. A custom panel of 1296 cancer-related genes was employed, and selected genes representing cancer drivers and non-drivers for endometrial and ovarian cancer were thoroughly investigated. All 59 detected somatic variants were of low mutated allele frequency (<10%). In deep ectopic lesions, detected variants were significantly more often located in cancer driver genes, whereas in eutopic endometrium, there was no such distribution. Our results converge with other reports, where cancer-related mutations were found in endometriosis without cancer, particularly recurrent KRAS mutations. Genetic alterations located in ectopic endometriotic nodules could contribute to their formation; nevertheless, to better understand the pathogenesis of this disease, more research in this area must be performed.

Premetastasis

Sterile inflammation within primary tumor tissues can spread to distant organs that are devoid of tumor cells. This happens in a manner dependent on tumor-led secretome, before the actual metastasis occurs. The premetastatic microenvironment is established in this way and is at least partly regulated by hijacking the host innate immune system. The biological manifestation of premetastasis include increased vascular permeability, cell mobilization via the blood stream, degradation of the extracellular matrix, immunosuppression, and host antineoplastic activities.

Suppression of PRDX4 inhibits cell proliferation and invasion of ectopic endometrial stromal cells in endometriosis

Oxidative stress (OS) has been proposed to play a role in the development of EMs. Peroxiredoxins are a family of antioxidant proteins that exhibit peroxidase activity in a thioredoxin-dependent manner, protecting cells against OS. The Western blotting results showed that the relative expression of PRDX4 was significantly increased in ectopic endometria compared with the normal endometria of EMs-free (p < .05). The H₂O₂ concentration was also significantly higher in the ectopic endometrium. PRDX4 siRNA was transfected into primary ectopic endometrial stromal cells (EESCs). The viability of the transfected EESCs was measured by CCK-8 assay, and the results showed significantly decreased cell viability. Furthermore, the apoptosis rate and ROS generation in flow cytometry assays were significantly increased after the knockdown of PRDX4 expression (p < .05). Scratch assays and transwell assays revealed that decreased expression of PRDX4 mediated by siRNA inhibited EESC migration and invasion. In conclusion, these findings indicate the potential role of PRDX4 in the development of EMs and PRDX4 as a possible therapeutic target for EMs treatment.

Phytotherapy in endometriosis: an up-to-date review

Endometriosis is a benign gynecological disease which symptoms can provide a severe impact on patient's quality of life with subsequent impact on psychological well-being. Different therapeutic strategies are available to treat this disease, such as surgery, hormonal therapies, and nonsteroidal anti-inflammatory drugs. Nevertheless, the efficacy of conventional medical treatments is limited or intermittent in most of the patients due to the associated side effects. Therefore, a woman with endometriosis often search for additional and alternative options, and phytotherapy might be a promising alternative and complementary strategy. Different medicinal plants, multicomponent herbal preparations, and phytochemicals were investigated for pharmacological proprieties in endometriosis therapy. In most of the cases, the effect on endometriosis was related to phenolic compounds, such as flavonoids and phenolic acids reporting anti-inflammatory, proapoptotic, antioxidant, and immunomodulatory functions. Moreover, some phytochemicals have been related to a strong phytoestrogenic effect modulating the estrogen activity. Although promising, available evidence is based on in vitro and animal models of endometriosis with a limited number of well-performed clinical studies. There are almost none randomized control trials in this area. Therefore, properly constructed clinical trials are mandatory to achieve more conclusive results about the promising role of phytotherapy in the management of endometriosis.

Protein expression pattern of tissue inhibitor of metalloproteinase-3 (TIMP3) in endometriosis and normal endometrium

Given the involvement of different extracellular matrix (ECM) metalloproteinases (MMPs) in endometriosis, the protein expression pattern of tissue inhibitor of metalloproteinase-3 (TIMP3) was analyzed in this study in endometriosis and normal endometrium. Tissue samples were collected prospectively from 64 premenopausal patients undergoing operative laparoscopy. Protein expression of TIMP3 was analyzed immunohistochemically in endometriotic lesions (n = 30) and normal eutopic endometrium from patients with (n = 35) and without (n = 29) endometriosis. Comparison between the three different groups of tissue samples showed that TIMP3 was differentially expressed between the three groups (p = .04). Pair-wise comparisons showed that TIMP3 expression was lower in endometriotic lesions as compared with normal eutopic endometrium from controls (p = .006); the same non-significant trend was found, in the comparison between endometriosis lesions and matched eutopic endometrium. There were no differences in TIMP3 expression in the normal eutopic endometrium between patients with and without endometriosis. In conclusion, TIMP3 seems to be involved in the pathogenesis, pathophysiology, and maintenance of endometriosis and it might be useful as a diagnostic and prognostic marker of endometriosis. Future studies should further investigate this issue, as well as the interplay between TIMPs and different extracellular MMPs in endometriosis.

The Pathogenesis of Endometriosis: Molecular and Cell Biology Insights

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

Complete remission of cerebral endometriosis with dienogest: a case report

The most recent evidences suggest the use of progesterone mimicking drugs for the treatment of endometriosis. Particularly, dienogest has been largely tested. However, the standard treatment of extra-pelvic endometriosis is debated. Particularly, cerebral localization of endometriosis is a very rare clinical condition. The surgical approach for such a particular disorder would consist in difficult procedures, thus leading to prefer the medical treatment. We hereby report the clinical case of a cerebral localization of endometriosis treated with dienogest who experienced a complete remission of the disease.

Expression and shedding of CD44 in the endometrium of women with endometriosis and modulating effects of vitamin D: A randomized exploratory trial

Endometriosis is an estrogen-dependent disease. The impaired estrogen and progesterone signaling over-activates the Wnt/β-catenin pathway in endometriosis patients, which can explain the increased invasion potency of endometrial cells derived from the endometrium of women with endometriosis. The regulatory effects of vitamin D on Wnt/β-catenin pathway were demonstrated by previous studies. According to gene prioritization method, among Wnt target genes, CD44 was in high ranking in relation to endometriosis. The aim of this study is to investigate the expression of CD44 in the endometrium of women with endometriosis and to study the effects of vitamin D on its expression. This prospective study was performed, during a 12 months period from December 2015 to November 2016, on healthy women as the control group (n = 14) and endometriosis patients (n = 34). The endometriosis patients randomly divided into two groups: One group treated according to the routine protocol and the other group, alongside the routine protocol, took 50,000 IU vitamin D weekly for 12-14 weeks. Blood, endometrial fluid, and endometrial tissue samples were obtained from the control group and endometriosis groups before and after the intervention. We used in silico gene prioritization to study the relevance of CD44. The expression of CD44 was evaluated using the techniques of Western blot, real-time polymerase chain reaction, and ELISA. The eutopic endometrium of women with endometriosis in mid-secretory phase expressed significantly higher levels of CD44s, CD44V, and CD44v6. The concentration of soluble CD44 in the serum and endometrial fluid of endometriosis patients was higher than of healthy women. The expression level of CD44s, CD44V, and CD44v6 in the eutopic endometrium as well as the concentration of soluble CD44 in the endometrial fluid was decreased after modification of the circulating levels of 25(OH)D. It seems that the increased expression and extensive shedding of CD44 in eutopic endometrium play a role in the pathogenesis of endometriosis. Vitamin D can control and modify this process at least in part. We suggest more in vivo investigations on the therapeutic potency of vitamin D in endometriosis.

Kisspeptin/Kisspeptin Receptor System in the Ovary

Kisspeptins are a family of neuropeptides that are critical for initiating puberty and regulating ovulation in sexually mature females via the central control of the hypothalamic-pituitary-gonadal axis. Recent studies have shown that kisspeptin and its receptor kisspeptin receptor (KISS1R) are expressed in the mammalian ovary. Convincing evidence indicates that kisspeptins can activate a wide variety of signals via its binding to KISS1R. Experimental data gathered recently suggest a putative role of kisspeptin signaling in the direct control of ovarian function, including follicular development, oocyte maturation, steroidogenesis, and ovulation. Dysregulation or naturally occurring mutations of the kisspeptin/KISS1R system may negatively affect the ovarian function, leading to reproductive pathology or female infertility. A comprehensive understanding of the expression, actions, and underlying molecular mechanisms of this system in the human ovary is essential for novel approaches to therapeutic and diagnostic interventions in reproductive diseases and infertility.

Immunohistochemical expression pattern of metastasis suppressors KAI1 and KISS1 in endometriosis and normal endometrium

OBJECTIVE

To analyze the expression pattern of metastasis suppressors KAI1 and KISS1 in the endometrium of patients with and without endometriosis.

STUDY DESIGN

In this pilot study, tissue samples were prospectively collected from 38 patients with endometriosis and 29 without endometriosis, undergoing operative laparoscopy in the proliferative phase of the menstrual cycle; diagnosis or absence of endometriosis was confirmed histologically. Protein expression of KAI1 and KISS1 were analyzed immunohistochemically in endometriotic lesions and the eutopic endometrium of patients with endometriosis and without endometriosis.

RESULTS

KAI1 expression was significantly decreased in the glandular eutopic endometrium of endometriosis patients as compared with that of patients without endometriosis (p=0.008). On the other hand, in endometriosis patients, KAI1 expression was significantly increased in the ectopic as compared with the eutopic endometrial stroma (p=0.021). There were no other significant differences in KAI1 expression between different groups. KISS1 expression in the ectopic glandular endometrium was significantly increased as compared with the eutopic glandular endometrium from patients with (p=0.004) and without endometriosis (p=0.008). There was no significant difference in KISS1 protein expression in the stromal endometrium between the three groups.

CONCLUSIONS

KAI1 and KISS1 are implicated in the pathogenesis and maintenance of endometriosis. Future studies should investigate whether KAI1 and KISS1 could be used as markers for early and minimally invasive detection of endometriosis based on their differential protein expression pattern in the eutopic endometrium of patients with and without endometriosis.

microRNA miR-200b affects proliferation, invasiveness and stemness of endometriotic cells by targeting ZEB1, ZEB2 and KLF4

Endometriosis is characterized by growth of endometrial tissue at ectopic locations. Down-regulation of microRNA miR-200b is observed in endometriosis and malignant disease, driving tumour cells towards an invasive state by enhancing epithelial-to-mesenchymal transition (EMT). miR-200b up-regulation may inhibit EMT and invasive growth in endometriosis. To study its functional impact on the immortalized endometriotic cell line 12Z, the stromal cell line ST-T1b, and primary endometriotic stroma cells, a transient transfection approach with microRNA precursors was employed. Expression of bioinformatically predicted targets of miR-200b was analysed by qPCR. The cellular phenotype was monitored by Matrigel invasion assays, digital-holographic video microscopy and flow cytometry. qPCR revealed significant down-regulation of ZEB1 (P < 0.05) and ZEB2 (P < 0.01) and an increase in E-cadherin (P < 0.01). miR-200b overexpression decreased invasiveness (P < 0.0001) and cell motility (P < 0.05). In contrast, cell proliferation (P < 0.0001) and the stemness-associated side population phenotype (P < 0.01) were enhanced following miR-200b transfection. These properties were possibly due to up-regulation of the pluripotency-associated transcription factor KLF4 (P < 0.05) and require attention when considering therapeutic strategies. In conclusion, up-regulation of miR-200b reverts EMT, emerging as a potential therapeutic approach to inhibit endometriotic cell motility and invasiveness.

The plasma and peritoneal fluid concentrations of matrix metalloproteinase-9 are elevated in patients with endometriosis

Background

Enzyme matrix metalloproteinase-9 is a member of the matrix metalloproteinase family, which is critical to normal tissue remodelling during embryogenesis and wound healing. In patients with endometriosis, increased expression and activity of matrix metalloproteinase-9 have been observed in ectopic endometrium, but the plasma and peritoneal fluid concentrations of matrix metalloproteinase-9 in patients with endometriosis and their relation to disease severity have not been clear. The aim of the study was to investigate the concentrations of matrix metalloproteinase-9 in plasma and peritoneal fluid of patients with endometriosis.

Methods

A prospective case–control study was conducted in Jinan Military General Hospital between January 2010 and December 2013. Fifty patients with proven endometriosis and 26 endometriosis-free controls were enrolled in this study. Patients with endometriosis were evaluated and divided into moderate/severe endometriosis group (stage I–II, n = 26) and minimal/mild endometriosis group (stage III–IV, n = 24) according to the revised criteria of the American Society for Reproductive Medicine. Blood samples and peritoneal fluid were obtained from both patients and controls. Matrix metalloproteinase-9 was measured using enzyme-linked immunosorbent assay in plasma and peritoneal fluid. The concentration of matrix metalloproteinase-9 between different groups was compared and its correlation to disease severity was analysed.

Results

Plasma and peritoneal fluid concentrations of matrix metalloproteinase-9 in patients with endometriosis were higher than that in controls. In addition, those patients with moderate/severe endometriosis had significantly higher plasma and peritoneal fluid concentrations of matrix metalloproteinase-9 compared to those with minimal/mild endometriosis. Matrix metalloproteinase-9 concentrations in plasma and peritoneal fluid were both positively correlated with severity of endometriosis and plasma matrix metalloproteinase-9 concentrations had a positive correlation with peritoneal fluid matrix metalloproteinase-9 concentrations in patients with endometriosis.

Conclusions

Increased concentrations of plasma and peritoneal fluid concentrations of matrix metalloproteinase-9 appear to be associated with disease severity of endometriosis and may serve as an alternative biomarker to determine disease severity of endometriosis.

Replication and meta-analysis of previous genome-wide association studies confirm vezatin as the locus with the strongest evidence for association with endometriosis

STUDY QUESTION

Is it possible to replicate the genetic association of single nucleotide polymorphisms (SNPs) rs13394619, rs4141819, rs7739264, rs17694933 and rs10859871 in five genetic loci previously identified as associated with endometriosis in an Italian Caucasian population?

SUMMARY ANSWER

SNP rs10859871 near the vezatin (VEZT) gene was found to be significantly associated with endometriosis in general while SNPs rs17694933 and rs4141819 were associated with Stage III/IV and ovarian disease, respectively.

WHAT IS KNOWN ALREADY

Endometriosis represents a complex disease in which the phenotypic manifestations are influenced by both genetic and environmental factors. Recent genome-wide association studies (GWASs) have allowed to identify some SNPs associated with the predisposition to the disease. A meta-analysis published in 2014 combined results from GWAS and replication studies showing that of the nine loci found to be associated with the disease in at least one of the studies, six (rs7521902, rs1270667, rs13394619, rs7739264, rs1537377 and rs10859871) remained genome-wide significant while two others (rs1250248 and rs4141819) showed borderline genome-wide significant association with more severe disease.

STUDY DESIGN, SIZE, DURATION

Allele frequencies of selected SNPs (rs13394619, rs4141819, rs7739264, rs17694933 and rs10859871) were investigated in 305 women with laparoscopically proven endometriosis, 285 laparoscopic controls and 2425 healthy, blood donor controls from the general population. A meta-analysis with previous data was also conducted.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 590 women who underwent endoscopic surgery were enrolled in the study and a blood sample was collected. After DNA extraction, genotype was obtained using Taq-Man pre-designed assay. Genotype data from healthy blood donor women were obtained from an existing genotype bank.

MAIN RESULTS AND THE ROLE OF CHANCE

A statistically significant association with endometriosis was found for SNP rs10859871, close to the VEZT gene, compared with both general population [odds ratio (OR) = 1.43, 95% confidence interval (CI): 1.20-1.71, P = 6.9 × 10(-5)] and laparoscopic controls (OR = 1.58, 95% CI: 1.24-2.02, P = 2.1 × 10(-4)). Meta-analysis with previous data confirmed the rs10859871 SNP as that with the strongest evidence for association with endometriosis (OR = 1.19, 95% CI: 1.15-1.24, P = 7.9 × 10(-20)). A further meta-analysis conducted using data from Stage III-IV endometriosis resulted in stronger genome-wide significant effect sizes for four out of the five SNPs tested.

LIMITATIONS, REASONS FOR CAUTION

The inability to confirm all previous demonstrated associations considering all stages of endometriosis may be due to a lack of statistical power and differences in the definition of cases included.

WIDER IMPLICATIONS OF THE FINDINGS

The associations with the SNPs identified so far have been obtained with a relatively small sample size supporting a limited heterogeneity across the various datasets. This represents an important advance in the identification of genetic markers of this disease.

STUDY FINDING/COMPETING INTERESTS

No funding to declare. The authors have no competing financial interests in relation to the content of this research paper.

Genetic variation of the E-cadherin gene is associated with primary infertility in patients with ovarian endometriosis

OBJECTIVE

To explore the association between the genetic variant of E-cadherin gene and endometriosis-related infertility.

DESIGN

Case-control study.

SETTING

University hospital.

PATIENT(S)

Five hundred eighty-nine women with ovarian endometriosis including 127 patients with primary infertility and 589 female controls in northern China.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Single nucleotide polymorphisms (SNPs) in the promoter region, exons, and the 3' untranslated region of the E-cadherin gene were identified by direct sequencing in patients with ovarian endometriosis and with polymerase chain reaction (PCR). Six candidate SNPs (rs16260, rs28372783, rs1801552, rs1801026, rs8049282, and rs13689) were genotyped by PCR and ligase detection reaction.

RESULT(S)

The results revealed a significant association of rs8049282 SNP on E-cadherin gene with endometriosis-related infertility. When compared with control women or endometriosis patients who had a history of successful fertility, the CC genotype of rs8049282 may significantly increase the risk of primary infertility in patients with ovarian endometriosis (adjusted odds ratio [OR] = 2.70, 95% confidence interval [CI] 1.45-5.00; OR = 2.54, 95% CI 1.45-4.44, respectively).

CONCLUSION(S)

Our results suggested that genetic variants on the E-cadherin gene may be involved in endometriosis-related infertility. The rs8049282 SNP of the E-cadherin gene may be a potential molecular marker for the development of primary infertility in northern Chinese women with ovarian endometriosis.

Peripheral blood telomere content is greater in patients with endometriosis than in controls

The etiology of endometriosis remains poorly understood but circulating stem cells may contribute. Telomeres shorten with cell divisions and age. Stem cells attempt to compensate for telomere attrition through the action of telomerase. Since circulating stem cells may contribute to endometriosis, we compared telomere content in lymphocytes of patients with and without endometriosis.

METHODS

Observational study comparing peripheral lymphocytes telomere content, measured by quantitative polymerase chain reaction, in patients with (n = 86) and without endometriosis (n = 21).

FINDINGS

Patients with endometriosis had longer telomeres than that of matched, endometriosis-free controls (telomere to single copy gene ratio [T/S ratio] of 1.62 vs 1.34, respectively, P = .00002). Patients with endometriosis were 8.1-fold more likely to have long telomeres. (odds ratio = 8.1, 95% confidence interval: 1.28-51.57, P = .0264).

INTERPRETATION

Longer telomeres could be consistent with a stem cell origin of endometriosis.

Extrapelvic endometriosis: a rare entity or an under diagnosed condition?

Endometriosis is a clinical entity characterized by the presence of normal endometrial mucosa abnormally implanted in locations other than the uterine cavity. Endometriosis can be either endopelvic or extrapelvicdepending on the location of endometrial tissue implantation. Despite the rarity of extrapelvic endometriosis, several cases of endometriosis of the gastrointestinal tract, the urinarytract, the upper and lower respiratory system, the diaphragm, the pleura and the pericardium, as well as abdominal scars loci have been reported in the literature. There are several theories about the pathogenesis and the pathophysiology of endometriosis. Depending on the place of endometrial tissue implantation, endometriosis can be expressed with a wide variety of symptoms. The diagnosis of this entity is neither easy nor routine. Many diagnostic methods clinical and laboratory have been used, but none of them is the golden standard. The multipotent localization of endometriosis in combination with the wide range of its clinical expression should raise the clinical suspicion in every woman with periodic symptoms of extrapelvic organs. Finally, the therapeutic approach of this clinical entity is also correlated with the bulk of endometriosis and the locum that it is found. It varies from simple observation, to surgical treatment and treatment with medication as well as a combination of those.

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

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

Cellular exchange in an endometriosis-adhesion model using GFP transgenic mice

BACKGROUND

Endometriosis is a debilitating disease that affects women of reproductive age and may lead to impaired fertility. Cell attachment, invasion of the underlying tissue, and vascular ingrowth are important processes in endometrial lesion development. However, the degree of cellular exchange between host peritoneum and endometrial tissue is unclear.

METHODS

An experimental endometriosis model was employed whereby uterine horn fragments from wild-type mice were implanted into genetically identical eGFP (enhanced green fluorescent protein) host mice and vice versa. Hormone sensitivity of the ectopic lesions was assessed and cellular exchange determined histologically.

RESULTS

White cyst-like lesions developed from implanted fibrin-rich fragments by day 7. Lesions consisted of a well-developed stroma with glandular and luminal epithelium. Both ovariectomy and treatment with a GnRH agonist, leuprorelin, resulted in the suppression of ectopic lesion growth, whereas estradiol treatment increased the size of the ectopic lesion (4 mice per group on day 14). Ingrowth and outgrowth of blood vessels was apparent as well as the exchange of cells between host peritoneum and lesion.

CONCLUSION

These findings support the proposal that there is a close cellular interplay between host peritoneum and ectopic tissue and the suitability of this mouse model to study these interactions.

A cross-study gene set enrichment analysis identifies critical pathways in endometriosis

BACKGROUND

Endometriosis is an enigmatic disease. Gene expression profiling of endometriosis has been used in several studies, but few studies went further to classify subtypes of endometriosis based on expression patterns and to identify possible pathways involved in endometriosis. Some of the observed pathways are more inconsistent between the studies, and these candidate pathways presumably only represent a fraction of the pathways involved in endometriosis.

METHODS

We applied a standardised microarray preprocessing and gene set enrichment analysis to six independent studies, and demonstrated increased concordance between these gene datasets.

RESULTS

We find 16 up-regulated and 19 down-regulated pathways common in ovarian endometriosis data sets, 22 up-regulated and one down-regulated pathway common in peritoneal endometriosis data sets. Among them, 12 up-regulated and 1 down-regulated were found consistent between ovarian and peritoneal endometriosis. The main canonical pathways identified are related to immunological and inflammatory disease. Early secretory phase has the most over-represented pathways in the three uterine cycle phases. There are no overlapping significant pathways between the dataset from human endometrial endothelial cells and the datasets from ovarian endometriosis which used whole tissues.

CONCLUSION

The study of complex diseases through pathway analysis is able to highlight genes weakly connected to the phenotype which may be difficult to detect by using classical univariate statistics. By standardised microarray preprocessing and GSEA, we have increased the concordance in identifying many biological mechanisms involved in endometriosis. The identified gene pathways will shed light on the understanding of endometriosis and promote the development of novel therapies.

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.

Activin A increases invasiveness of endometrial cells in an in vitro model of human peritoneum

The aim of this study was to investigate whether activin A has an effect on the attachment and/or invasion of endometrial cells in a modeled peritoneum in vitro. Cultured endometrial stromal cells (ESCs) and endometrial epithelial cells (EECs) were treated with activin A (6.25-50 ng/ml) and with activin A (25 ng/ml) with and without inhibin A or follistatin. Fluorescent labeled cells were added to confluent peritoneal mesothelial cells (PMCs) and to a monolayer of confluent PMCs grown in a Matrigel invasion assay. The rate of endometrial cell attachment and invasion through PMCs was assessed. The expression of cell adhesion proteins N- and E-cadherin was evaluated with real-time RT-PCR. Activin A (25 ng/ml) promoted invasion of the endometrial cells through the modeled peritoneum (>2-fold versus control) and this effect was partially reversed by inhibin A and follistatin. Activin A had no effect on the rate of attachment of the endometrial cells to the PMCs or in the rate of proliferation. In addition, activin A induced a decreased mRNA expression of E-cadherin in cultured EECs. In conclusion, activin A increases invasion of EECs and ESCs into modeled peritoneum. In EECs, this effect may be related to down-regulation of E-cadherin expression. Further studies are warranted to evaluate the role of activin-A in the genesis of the endometriotic lesion.

Soluble HLA-G in the peritoneal fluid of women with endometriosis

The aim of this study was to determine the level of soluble HLA-G molecules in the peritoneal fluid of endometriosis patients. The findings demonstrate that a soluble HLA-G level in the peritoneal fluid of women with endometriosis is similar to that of the control group.

Expression of heparanase and angiopoietin-2 in patients with endometriosis

OBJECTIVE

The objective was to investigate the expression of heparanase (Hpa) and angiopoietin-2 (Ang-2) in endometriosis.

STUDY DESIGN

In ectopic and eutopic endometrium of patients undergoing laparoscopy for endometriosis (n=86) and in normal endometrium of patients undergoing laparoscopic tubal ligation or hysteroscopic resection because of uterus septus (n=30), we determined Hpa and Ang-2 gene expression by RT-PCR. To support the mRNA data, the expression of Hpa and Ang-2 protein was measured by Western blot analysis. Finally, Hpa and Ang-2 in these tissues was localized by immunohistochemical staining.

RESULT(S)

The positive rate of Hpa and Ang-2 mRNA in ectopic and eutopic endometrium in the study group was significantly higher than that in normal endometrium in the control group. In the study group, ectopic and eutopic endometrium expressed a higher positive rate of Hpa and Ang-2 protein, whereas in the control group, normal endometrium expressed a lower positive rate of Hpa and Ang-2 protein. In eutopic and ectopic endometrium, there was balanced expression between Hpa and Ang-2. Both Hpa and Ang-2 showed a balanced expression between eutopic and ectopic endometrium. In ectopic endometrium, strong staining for Hpa and Ang-2 was observed both in epithelial cells and in stromal cells, but in eutopic endometrium, Hpa and Ang-2 were mainly expressed in epithelial cells.

CONCLUSION

The higher expression of Hpa and Ang-2 in ectopic and eutopic endometrium may play an important role in the pathogenesis and development of endometriosis.

Association of three single nucleotide polymorphisms of the E-cadherin gene with endometriosis in a Chinese population

Endometriosis, one of the most frequent diseases in gynecology, is a benign but invasive and metastatic disease. The altered expression of E-cadherin may play an important role in developing endometriosis. In this paper, we discuss the association of three single nucleotide polymorphisms (SNPs) on the E-cadherin gene and risk of endometriosis. We examined the genotype frequency of three polymorphisms in 152 endometriosis patients and 189 control women. There was a significant difference in the frequency of the E-cadherin 3'-UTR C --> T genotypes between endometriosis and controls (P = 0.01). The frequency of the C allele in patients (71.1%) was significantly higher than in the controls (63.8%; P = 0.04). When compared with the T/T + T/C genotypes, the C/C genotype had a significantly increased susceptibility to endometriosis, with an adjusted odds ratio of 1.79 (95% confidence interval = 1.17-2.76). No significant difference was found between endometriosis and control women on two polymorphisms (-160 C --> A, -347 G --> GA) at the gene promoter region of E-cadherin. The -160 C --> A and -347 G --> GA polymorphisms displayed linkage disequilibrium (D' = 0.999). The -160 A/-347 GA haplotype was only detected in endometriosis patients (2%). These data show a relation between the E-cadherin 3'-UTR C --> T polymorphism, the -160 A/-347 GA haplotype of two promoter polymorphisms and risk of endometriosis, suggesting a potential role in endometriosis development, at least in North Chinese women.

An ileal endometrioma: of carcinoids and cadherin

A 38-year-old woman with history of prior adrenalectomy for Cushing's syndrome presented with intermittent right lower quadrant (RLQ) abdominal pain, nausea, bloating, and non-bloody diarrhea for 2 months. Symptoms were not related to her menstrual periods. Examination revealed only an ill-defined mass in the RLQ. Investigations for infectious causes, inflammatory bowel disease, and carcinoid tumor were negative. Computed tomography (CT) demonstrated a terminal ileal mass with mesenteric stranding and dilatation of the proximal bowel. At laparotomy, a fibrotic, terminal ileal mass with matted adhesions involving the mesentery and retroperitoneum was resected. Histopathological examination identified multiple foci of endometriosis extending from the serosal surface into the mucosa of the terminal ileum. Immunostaining revealed E- and P-cadherin, but not N-cadherin immuno-positivity. Mucosal involvement without cyclical menstrual symptoms and intestinal obstruction is an unusual presentation of intestinal endometriosis. Although the mechanism of endometriosis is not clear, the role of cell adhesion molecules such as cadherins has received attention. Increased expression of E- and P-cadherin and decreased N-cadherin expression in our patient demonstrates differential expression of these cadherins in endometriotic tissue. Future studies may investigate patterns of differential expression of these cadherins in a series of cases to elucidate the mechanisms of migration of endometriotic tissue.

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.

Oxidative damage and mitochondrial DNA mutations with endometriosis

Endometriosis, a frequently encountered disease in gynecology, is a considerable threat to the physical, psychological, and social integrity of women. Moreover, up to 50% of infertile patients have this disease. The etiology and pathogenesis of this important disease are poorly understood; it is defined as an ectopic location for endometrium-like glandular epithelium and stroma outside of the uterine cavity. It still remains an open question as to what extent the peritoneal environment influences the establishment and/or progression of endometriosis. As a result of such stress, a sterile, inflammatory reaction with the secretion of growth factors, cytokines, and chemokines is generated, which is especially deleterious to successful reproduction. Significantly higher amounts of oxidative damage were detected in endometriotic lesions than in controlled normal endometrium, including mitochondrial DNA (mtDNA) rearrangement, 8-OH-deoxyguanosine (8-OH-dG), and lipoperoxide contents. There were approximately sixfold increases in 8-OH-dG and lipoperoxides in chocolate cysts compared with normal endometrial tissues. A novel 5,335-bp deletion of mtDNA was identified in endometriotic tissue. According to these results, we propose that oxidative stress and mtDNA mutations might be anticipated in the initiation or progression of endometriosis. Only by understanding the mechanisms involved in the pathogenesis of endometriosis can we develop a basis for new diagnostic and therapeutic approaches.

Future Directions in Endometriosis Research

Endometriosis is an important gynecological disease, pathologically defined by the ectopic presence of both endometrial glands and stroma, and clinically associated with pelvic pain and infertility. Our current knowledge of the pathogenesis, pathophysiology of related infertility, and spontaneous evolution is still limited, although endometriosis has been described for many years. Future research in endometriosis needs to focus on pathogenesis studies in the baboon model and on the early interactions between endometrial and peritoneal cells in the pelvic cavity at the time of menstruation. Proteomic and genomic approaches are needed to detect potential differences between eutopic endometrium and myometrium in women with and without endometriosis. Immunomodulatory drugs inhibiting endometriosis-associated pelvic inflammation may offer new medical treatment for endometriosis in the future.

Endometriosis and the neoplastic process

Endometriosis is a frequent disorder that commonly presents with infertility and pelvic pain. Although the precise aetiology of endometriosis is unclear, it is generally considered to involve multiple genetic, environmental, immunological, angiogenic and endocrine processes. Genetic factors have been implicated in endometriosis but the susceptibility genes remain largely unknown. Although endometriosis is a benign disorder, recent studies of endometriosis suggest endometriosis could be viewed as a neoplastic process. Evidence to support this hypothesis includes the increased susceptibility to develop ovarian clear-cell and endometrioid cancers in the presence of endometriosis, and molecular similarities between endometriosis and cancer. In this article we discuss (i) the evidence suggesting that endometriosis might be viewed as a neoplastic process, and (ii) the implications of this hypothesis for elucidating the pathogenesis of endometriosis and developing novel methods of diagnostic classification and individualised treatments.

Activity of eosinophils and immunoglobulin E concentration in the peritoneal fluid of women with endometriosis

Autoinflammatory phenomena, including autoantibody production and atopy, have been regarded as associated with endometriosis. The present study investigates the activity of eosinophils and the distribution of immunoglobulin E concentrations in the peritoneal fluid of women with early endometriosis. The study group consisted of 30 patients with laparoscopically diagnosed early endometriosis. The healthy control group consisted of 18 females with no evident changes in the abdominal cavity and no endometrial foci. Concentrations of immunoglobulin E in serum and peritoneal blood were determined by enzyme immunoassay. The activity of eosinophils was estimated according to the expression of the early activation molecule CD69 by the flow cytometry method. The concentrations of immunoglobulin E in the peripheral blood and peritoneal fluid were similar in both groups. However, the count of CD69+ eosinophils was higher in the peritoneal fluid of women with endometriosis. The results indicate that activated eosinophils accumulate in the peritoneal fluid in early endometriosis and can play a significant role in the pathogenesis of the disease.

Pathogenesis of endometriosis: natural immunity dysfunction or autoimmune disease?

Endometriosis is a chronic inflammatory disease, characterized by implantation and growth of endometrial tissue outside the uterine cavity. This disabling condition is considered one of the most frequent diseases in gynecology, affecting 15-20% of women in their reproductive life. Pelvic endometriosis, the most common form of the disease, is associated with increased secretion of pro-inflammatory cytokines, neo-angiogenesis, intrinsic anomalies of the refluxed endometrium and impaired function of cell-mediated natural immunity. Recently, endometriosis has also been considered to be an autoimmune disease, owing to the presence of autoantibodies, the association with other autoimmune diseases and recurrent immune-mediated abortion. These findings are in apparent contradiction with the reduced cell-mediated natural immunity observed during the disease. In this review, we focus on the multiple processes underlying the complex pathogenesis of endometriosis, with particular emphasis on the role played by the immune system with the induction of autoimmunity.

Endometriosis: current concepts and therapy

Endometriosis is the growth of endometrial tissue in ectopic locations. The clinical picture is extremely pleiomorphic, which can make the diagnosis difficult. Despite 70 years of theories and experimentation, the cause is not clear, and it is likely that more than one mechanism is at work in most patients. Both medical and surgical treatments are available. In each case, the woman and her physician should formulate a comprehensive treatment plan that addresses the primary complaint as well as the patient's reproductive desires.

Expression of matrix metalloproteinases in ovarian endometriomas: immunohistochemical study and enzyme immunoassay

Like carcinoma, endometriosis has the unique characteristics, of invasion and metastasis, though pathologically, it is a benign tumor. However, the mechanism of destruction of the surrounding tissue in endometriosis is still unclear. In this study, the expression and localization of matrix metalloproteinases (MMP)-1, -2, -3, -7, -9 and tissue inhibitors of metalloproteinases-1 (TIMP-1) were evaluated by immunohistochemistry for 20 cases and the amounts of MMP-1, TIMP-1 and MMP-1/TIMP-1 complex in the fluid of endometrioma, were analyzed by ELISA and western blotting for 20 cases, which were analyzed by immunohistochemical study. MMP-1, -2 and -9 were detected strongly in both stromal and epithelial cells and MMP-7 in the epithelial cells in the menstrual period. MMP-3 was mainly expressed in macrophage containing hemosiderin but the change of expression was not clear. TIMP-1 was intensively detected in both stromal and epithelial cells in the menstrual period but the expression decreased in other stages of the menstrual cycle. ELISA for MMP-1 also showed results similar to immunohistochemistry, suggesting that it was released to the cyst in the menstrual period when it was released to the extracellular space from the cytoplasm. The expression of TIMP-1 was not clearly changed during the menstrual cycle. From these results, it was suggested that the destruction of the surrounding matrix by endometriosis might be caused by various MMPs, which are mainly produced in stromal cells.