Differential regulation of matrix metalloproteinase-3 gene expression in endometriotic lesions compared with endometrium

Melatonin in Endometriosis: Mechanistic Understanding and Clinical Insight

Endometriosis is defined as the development of endometrial glands and stroma outside the uterine cavity. Pathophysiology of this disease includes abnormal hormone profiles, cell survival, migration, invasion, angiogenesis, oxidative stress, immunology, and inflammation. Melatonin is a neuroendocrine hormone that is synthesized and released primarily at night from the mammalian pineal gland. Increasing evidence has revealed that melatonin can be synthesized and secreted from multiple extra-pineal tissues where it regulates immune response, inflammation, and angiogenesis locally. Melatonin receptors are expressed in the uterus, and the therapeutic effects of melatonin on endometriosis and other reproductive disorders have been reported. In this review, key information related to the metabolism of melatonin and its biological effects is summarized. Furthermore, the latest in vitro and in vivo findings are highlighted to evaluate the pleiotropic functions of melatonin, as well as to summarize its physiological and pathological effects and treatment potential in endometriosis. Moreover, the pharmacological and therapeutic benefits derived from the administration of exogenous melatonin on reproductive system-related disease are discussed to support the potential of melatonin supplements toward the development of endometriosis. More clinical trials are needed to confirm its therapeutic effects and safety.

Proteomic analysis of peritoneal fluid identified COMP and TGFBI as new candidate biomarkers for endometriosis

Endometriosis is a common non-malignant gynecological disease that significantly compromises fertility and quality of life of the majority of patients. The gold standard for diagnosis is visual inspection of the pelvic organs by surgical laparoscopy and there are no biomarkers that would allow non-invasive diagnosis. The pathogenesis of endometriosis is not completely understood, thus analysis of peritoneal fluid might contribute in this respect. Our prospective case-control study included 58 patients undergoing laparoscopy due to infertility, 32 patients with peritoneal endometriosis (cases) and 26 patients with unexplained primary infertility (controls). Discovery proteomics using antibody microarrays that covered 1360 proteins identified 16 proteins with different levels in cases versus the control patients. The validation using an ELISA approach confirmed significant differences in the levels of cartilage oligomeric matrix protein (COMP) and transforming growth factor-β-induced protein ig-h3 (TGFBI) and nonsignificant differences in angiotensinogen (AGT). A classification model based on a linear support vector machine revealed AUC of > 0.83, sensitivity of 0.81 and specificity of 1.00. Differentially expressed proteins represent candidates for diagnostic and prognostic biomarkers or drug targets. Our findings have brought new knowledge that will be helpful in the understanding of the pathophysiology of endometriosis and warrant further studies in blood samples.

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.

The Effect of Imbalanced Progesterone Receptor-A/-B Ratio on Gelatinase Expressions in Endometriosis

Background

Gelatinases degrade extracellular matrix (ECM) components to allow for physiological remodeling and contribute to pathological tissue destruction in endometriosis. It is known that the function of gelatinases is resistant to suppression by progesterone in endometriosis. The ability of progesterone to impact gene expression depends on the progesterone receptor-A/-B(PR-A/PR-B) ratio. An imbalanced PR-A/PR-B ratio in endometriotic tissue may be the result of the differential expression of MMP-2 and MMP-9, which could be important in the etiology and pathogenesis of the disease. Hence, we decided to study the association of PR-A/PR-B ratio and gelatinases expression in endometriosis.

Materials and Methods

In this prospective case-control study, we enrolled 40 women, 20 in the case group who were diagnosed with stage III/IV endometriosis and 20 normal subjects without endometriosis (controls) who referred to Royan Institute, Tehran, Iran during 2013-2014. We obtained 60 tissue samples [ectopic (n=20), eutopic (n=20), and normal endometrium (n=20)]. RNA was extracted from the tissue samples in order to analyze PR-A, PR-B, MMP-2, and MMP-9 mRNA levels through real-time polymerase chain reaction (PCR).

Results

There was significantly lower expression of the PR-B isoform in ectopic tissues compared to the control (P=0.002) and eutopic endometrium (P=0.006) tissues. PR-A expression was higher, but not significantly so, in the same ectopic and eutopic endometrium tissues compared to the control tissues (P=0.643). There was significant overexpression of MMP-9 in ectopic samples compared to control (P=0.014) and eutopic endometrium (P=0.012) samples. The PR-A/PR-B ratio was not significantly higher in either eutopic or ectopic samples compared to the control samples (P=0.305).

Conclusion

Our findings support an altered PR-B expression in endometriosis, which may be associated with MMP-9 overexpression. This finding can be important for disease pathogenesis.

The bimodal role of matrix metalloproteinases and their inhibitors in etiology and pathogenesis of endometriosis (Review)

Aberrant regulation of matrix metalloproteinases (MMPs) may be the primary cause of endometrial lesion formation in a group of predisposed women. Prospect for the genuine origin of endometriosis is ongoing, since retrograde menstruation leads to presence of endometrial debris in peritoneal cavity of many women, which do not experience endometriosis. Tissue remodeling is regulated precisely by a balance of MMPs and their inhibitors. Interplay between factors enhancing and suppressing matrix turnover is crucial for cyclic preparation of endometrium for embryo implantation, and endometrial shedding and renewal in physiology of primates. Disorders of the regulation of matrix remodeling leads to augmentation of implantation and invasive growth of ectopic endometrial tissue. Moreover, endometriosis-induced changes in the matrix balance leads to adhesion formation, ovulatory dysfunction and fertility impairment. The review summarizes the current knowledge regarding the regulation of extracellular matrix turnover in the physiology of the endometrial cycle and in the development of endometriosis, as well as the pathophysiology of ovulatory dysfunction in endometriotic women. Therapeutic modalities utilizing modulation of tissue remodeling were discussed.

The DNA methylation status of genes encoding Matrix metalloproteinases and tissue inhibitors of Matrix metalloproteinases in endometriosis

Endometriosis is a benign disease, with malignant properties. A necessary step in the progression of endometriosis is tissue remodeling, which is coordinated by the activities of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs). This study evaluated the regulation of abnormal MMP and TIMP gene expression during endometriosis. Among the two genes families, promoter regions of MMP2, MMP3, MMP7, TIMP3, and TIMP4 were significantly altered in proliferative-phase endometriotic lesions compared to menstrual cycle-matched eutopic tissue from endometriosis-free women. In addition, a negative correlation was found between the DNA methylation status of the promoter region and transcript abundance of MMP2. Our findings suggest that changes in DNA methylation at the promoter region of MMP2 could underlie the changes in its expression in the ectopic endometria from patients with endometriosis.

Endometrial biomarkers for the non-invasive diagnosis of endometriosis

BACKGROUND

About 10% of reproductive-aged women suffer from endometriosis, which is a costly, chronic disease that causes pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but it is expensive and carries surgical risks. Currently, there are no non-invasive tests available in clinical practice that accurately diagnose endometriosis. This is the first diagnostic test accuracy review of endometrial biomarkers for endometriosis that utilises Cochrane methodologies, providing an update on the rapidly expanding literature in this field.

OBJECTIVES

To determine the diagnostic accuracy of the endometrial biomarkers for pelvic endometriosis, using a surgical diagnosis as the reference standard. We evaluated the tests as replacement tests for diagnostic surgery and as triage tests to inform decisions to undertake surgery for endometriosis.

SEARCH METHODS

We did not restrict the searches to particular study designs, language or publication dates. To identify trials, we searched the following databases: CENTRAL (2015, July), MEDLINE (inception to May 2015), EMBASE (inception to May 2015), CINAHL (inception to April 2015), PsycINFO (inception to April 2015), Web of Science (inception to April 2015), LILACS (inception to April 2015), OAIster (inception to April 2015), TRIP (inception to April 2015) and ClinicalTrials.gov (inception to April 2015). We searched DARE and PubMed databases up to April 2015 to identify reviews and guidelines as sources of references to potentially relevant studies. We also performed searches for papers recently published and not yet indexed in the major databases. The search strategies incorporated words in the title, abstract, text words across the record and the medical subject headings (MeSH).

SELECTION CRITERIA

We considered published peer-reviewed, randomised controlled or cross-sectional studies of any size that included prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE).

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from each study and performed a quality assessment. For each endometrial diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis and calculated the estimates of sensitivity and specificity. We considered two or more tests evaluated in the same cohort as separate data sets. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient data were available. The predetermined criteria for a clinically useful test to replace diagnostic surgery was one with a sensitivity of 94% and a specificity of 79%. The criteria for triage tests were set at sensitivity at or above 95% and specificity at or above 50%, which in case of negative results rules out the diagnosis (SnOUT test) or sensitivity at or above 50% with specificity at or above 95%, which in case of positive result rules in the diagnosis (SpIN test).

MAIN RESULTS

We included 54 studies involving 2729 participants, most of which were of poor methodological quality. The studies evaluated endometrial biomarkers either in specific phases of the menstrual cycle or outside of it, and the studies tested the biomarkers either in menstrual fluid, in whole endometrial tissue or in separate endometrial components. Twenty-seven studies evaluated the diagnostic performance of 22 endometrial biomarkers for endometriosis. These were angiogenesis and growth factors (PROK-1), cell-adhesion molecules (integrins α3β1, α4β1, β1 and α6), DNA-repair molecules (hTERT), endometrial and mitochondrial proteome, hormonal markers (CYP19, 17βHSD2, ER-α, ER-β), inflammatory markers (IL-1R2), myogenic markers (caldesmon, CALD-1), neural markers (PGP 9.5, VIP, CGRP, SP, NPY, NF) and tumour markers (CA-125). Most of these biomarkers were assessed in single studies, whilst only data for PGP 9.5 and CYP19 were available for meta-analysis. These two biomarkers demonstrated significant diversity for the diagnostic estimates between the studies; however, the data were too limited to reliably determine the sources of heterogeneity. The mean sensitivities and specificities of PGP 9.5 (7 studies, 361 women) were 0.96 (95% confidence interval (CI) 0.91 to 1.00) and 0.86 (95% CI 0.70 to 1.00), after excluding one outlier study, and for CYP19 (8 studies, 444 women), they were were 0.77 (95% CI 0.70 to 0.85) and 0.74 (95% CI 0.65 to 84), respectively. We could not statistically evaluate other biomarkers in a meaningful way. An additional 31 studies evaluated 77 biomarkers that showed no evidence of differences in expression levels between the groups of women with and without endometriosis.

AUTHORS' CONCLUSIONS

We could not statistically evaluate most of the biomarkers assessed in this review in a meaningful way. In view of the low quality of most of the included studies, the findings of this review should be interpreted with caution. Although PGP 9.5 met the criteria for a replacement test, it demonstrated considerable inter study heterogeneity in diagnostic estimates, the source of which could not be determined. Several endometrial biomarkers, such as endometrial proteome, 17βHSD2, IL-1R2, caldesmon and other neural markers (VIP, CGRP, SP, NPY and combination of VIP, PGP 9.5 and SP) showed promising evidence of diagnostic accuracy, but there was insufficient or poor quality evidence for any clinical recommendations. Laparoscopy remains the gold standard for the diagnosis of endometriosis, and using any non-invasive tests should only be undertaken in a research setting. We have also identified a number of biomarkers that demonstrated no diagnostic value for endometriosis. We recommend that researchers direct future studies towards biomarkers with high diagnostic potential in good quality diagnostic studies.

Intracellular Wnt/Beta-Catenin Signaling Underlying 17beta-Estradiol-Induced Matrix Metalloproteinase 9 Expression in Human Endometriosis

Extracellular matrix remodeling is necessary for ectopic endometrium implantation. Many studies have shown an increased expression of matrix metalloproteinase 9 (MMP9) in the ectopic endometrium of endometriosis. However, the signaling pathways and cellular effects related to this process remain incompletely elucidated. The objective of our study was to investigate the association between MMP9 and the Wnt signaling pathway under the regulation of 17beta-estradiol (E2) in endometrial stromal cells. We found that MMP9 was elevated in tissues from women with endometriosis compared with normal women. Furthermore, MMP9 and beta-catenin increased concurrently in a time- and dose-dependent manner after E2 treatment. To clarify the relationship between MMP9 and beta-catenin, we performed luciferase promoter reporter and chromatin immunoprecipitation assays. A beta-catenin/TCF3/LEF1 complex bound to a specific site on the MMP9 promoter that promoted MMP9 gene and protein expression. The promotion of MMP9 by the Wnt signaling pathway under the regulation of E2 may contribute to the pathophysiology of this disease.

rhTNFR: Fc Suppresses the Development of Endometriosis in a Mouse Model by Downregulating Cell Proliferation and Invasiveness

Tumor necrosis factor α (TNF-α), a proinflammatory cytokine, may play an important role in the pathogenesis of endometriosis; therefore, TNF-α inhibitors potentially have an effect on endometriosis. To investigate the effect of anti-TNF-α treatment on endometriosis, 2 TNF-α inhibitors: recombinant human TNF receptor: Fc fusion protein (rhTNFR: Fc) and TNF-α monoclonal antibody (TNF-α mAb) were used to treat human eutopic endometrial stromal cells (hESCs), and the effects on cell survival, cell cycle, and invasiveness were compared. It was found that rhTNFR: Fc suppressed the TNF-α-induced hESC survival and invasiveness but not TNF-α mAb. Recombinant human TNF receptor: Fc fusion protein decreased the S phase of hESC compared with the TNF-α-treated group. Then, we used a surgically induced mouse model of endometriosis to study the effect of rhTNFR: Fc treatment in vivo. The fluorescence intensity and the size of implanted endometriotic lesions in the mouse model were decreased by rhTNFR: Fc. In conclusion, rhTNFR: Fc suppresses hESC survival and invasiveness and decreases the fluorescence intensity and implant size in the mouse model of endometriosis.

Targeting oxidative stress to treat endometriosis

INTRODUCTION

Endometriosis affects 10% of women of reproductive age. It is defined as the presence of implanted active endometrial tissue outside the uterine cavity. The exact pathophysiology of endometriosis is still uncertain, although several optional etiological theories have been suggested. Being so common, a novel treatment for endometriosis is widely quested. Recent studies addressing the pathological characteristics of endometriosis have revealed a vicious cycle in which oxidative stress (OS) is generated, which in turn facilitates the implantation of the ectopic endometrium. At the same time, the generation of high amounts of reactive oxygen species further triggers a state of OS.

AREAS COVERED

The author examined the evidence associating OS and endometriosis. After establishing an association, a search for antioxidant agents that were investigated specifically on endometriosis patients are described including Vitamins C and E, melatonin, resveratrol, xanthohumol and epigallocatechin-3-gallate. A significant effect of all the reviewed antioxidants on endometriosis is reported.

EXPERT OPINION

Aiming for the reduction of OS as the treatment goal for endometriosis looks promising. However, since most of the studies are either in vitro or are animal based, further studies on human subjects are deemed necessary to elucidate the impact of OS reduction on patients with endometriosis.

The endometriotic tissue lining the internal surface of endometrioma: hormonal, genetic, epigenetic status, and gene expression profile

Ovarian endometriomas are found in a consistent proportion of patients with endometriosis and are associated with a more severe form of the disease. The endometriotic tissue lining the inside of the endometrioma has been extensively studied over the years mostly for the need to compare the molecular and cellular characteristics of eutopic and ectopic endometria. Several aspects of hormonal regulation, response to local inflammation, carcinogenesis, and modifications of the local environment have been investigated in order to characterize also the processes associated with peritoneal endometriosis. In this review, we have summarized the current knowledge of pathophysiology of endometrioma, with a particular focus on the cellular components lining the internal surface of the cyst in order to provide a comprehensive overview of the hormonal, genetic, epigenetic, and gene expression profiles of this essential part of the cyst.

Towards an understanding of the molecular mechanism of endometriosis: unbalancing epithelial-stromal genetic conflict

OBJECTIVES

Despite the high incidence of endometriosis, the etiology is poorly understood. Much work has been carried out to elucidate the genetic basis of endometriosis owing to the advent of genomic analysis and new network-based analysis methods.

METHODS

This article reviews the English literature for (epi)genome-wide profiling and association studies on the pathogenesis and pathophysiology of endometriosis.

RESULTS

The characteristic 82 up- and 45 down-regulated unique genes in endometriosis included genes encoding cell cycle, growth factors, signal transduction, transcription factors, hormones, cytokines, chemokines and (pro)inflammation, proteases, cell adhesion and motility, stress response and detoxification, immune response, metabolism and others. There appear to be at least two types of genes: some genes (n = 50) may evolve mainly for the benefit of the endometrial growth, and the other genes (n = 55) evolve as a protective mechanism for the endometrial decidualization. The present review has shed new light on the overlapping genetic signatures between endometriosis development and decidualization process.

CONCLUSION

In conclusion, insufficient decidualization due to unbalancing epithelial-stromal genetic conflict may result in future endometriosis.

The distinguishing cellular and molecular features of the endometriotic ovarian cyst: from pathophysiology to the potential endometrioma-mediated damage to the ovary

BACKGROUND

Clinical data suggest that the presence of an ovarian endometrioma may cause per se damage to the surrounding otherwise healthy ovarian tissue. However, the basic research has so far done a limited job in trying to understand the potential detrimental effect of an endometrioma presence in the context of the ovarian physiology. We have reviewed the literature with the aim of characterizing the pathophysiology of the endometrioma focusing mostly on factors and mechanisms potentially affecting the surrounding, otherwise normal, ovarian tissue.

METHODS

Comprehensive searches of PUBMED were conducted to identify human studies published from 1991 to 2013 in the English language on the cellular and molecular characterization of the various endometrioma components.

RESULTS

An endometrioma contains free iron, reactive oxygen species (ROS), proteolytic enzymes and inflammatory molecules in concentrations from tens to hundreds of times higher than those present in peripheral blood or in other types of benign cysts. The cyst fluid causes substantial changes in the endometriotic cells that it baths from gene expression modifications to genetic mutations The physical barrier between the cyst contents and the normal ovarian tissue is a thin wall composed of the ovarian cortex itself or fibroreactive tissue. ROS potentially permeating the surrounding tissues and proteolytic substances degrading the adjacent areas are likely to cause the substitution of normal ovarian cortical tissue with fibrous tissue in which the cortex-specific stroma is reduced. The fibrosis is associated with smooth muscle metaplasia and followed by follicular loss and intraovarian vascular injury. Follicular density in tissue surrounding the endometriotic cyst was consistently shown to be significantly lower than in healthy ovaries but this pathological change does not appear to be caused by the stretching of surrounding tissues owing to the presence of a cyst.

CONCLUSIONS

There is sufficient molecular, histological and morphological evidence, in part deriving from knowledge of the pathophysiology, to support a deleterious effect of the endometrioma on the adjacent ovarian cortical tissue, independent of the mere mechanical stretching owing to its size.

Melatonin treatment results in regression of endometriotic lesions in an ooferectomized rat endometriosis model

OBJECTIVE

We aimed to determine the effects of melatonin treatment on endometrial implants in an oopherectomized rat endometriosis model.

MATERIAL AND METHODS

This study is a prospective, randomised, controlled experimental study. It was carried out at the Experimental Research Center of Yeditepe University (YUDETAM). Twenty-two, female, non-pregnant, nulligravid Spraque-Dawley albino rats were included in our study. Endometriosis was surgically induced in oopherectomized rats. Rats were randomised into two groups: control group and melatonin group. In the melatonin group, rats were treated with melatonin (20 mg/kg/day) for two weeks. After the operations were performed to assess the regression of the endometriotic lesions, melatonin treatment was stopped. At the end of the sixth week necropsies were performed to assess the rate of recurrence. The volume and histopathological scores of endometriotic foci were examined.

RESULTS

Volumes of the endometriotic lesions significantly decreased in the melatonin group. Also, when the melatonin group was analysed within itself, endometriotic lesion volumes decreased and histopathological scores increased significantly.

CONCLUSION

Melatonin causes regression of the endometriotic lesions in rats and improvement in their histopathological scores.

Molecular and functional aspects of menstruation in the macaque

Much of our understanding of the molecular control of menstruation arises from laboratory models that experimentally recapitulate some, but not all, aspects of uterine bleeding observed in women. These models include: in vitro culture of endometrial explants or isolated endometrial cells, transplantation of human endometrial tissue into immunodeficient mice and the induction of endometrial breakdown in appropriately pretreated mice. Each of these models has contributed to our understanding of molecular and cellular mechanisms of menstruation, but nonhuman primates, especially macaques, are the animal model of choice for evaluating therapies for menstrual disorders. In this chapter we review some basic aspects of menstruation, with special emphasis on the macaque model and its relevance to the clinical issues of irregular and heavy menstrual bleeding (HMB).

Growth mechanisms of endometriotic cells in implanted places: a review

Endometriosis is a common gynecological disease defined by extrauterine growth of endometrial glands and stroma. A variety of theories have been proposed to account for the pathogenesis of this disease, including retrograde transplantation theory, metaplasia of coelomic epithelium, hematogenic and lymphogenic spread, and remnants of the Mŭllerian duct. However, the etiopathology of endometriosis is still obscure. In this article, we aim to summarize recent researches concerning the growth mechanisms of endometriotic cells in implanted sites systematically, including the adhesion, invasion, angiogenesis, proliferation, apoptosis of endometriotic cells, variations of the immune molecules and endometriotic cells themselves, which may provide clues for future researches in the pathogenesis of endometriosis.

Endometriosis gene expression heterogeneity and biosignature: a phylogenetic analysis

Endometriosis is a multifactorial disease with poorly understood etiology, and reflecting an evolutionary nature where genetic alterations accumulate throughout pathogenesis. Our objective was to characterize the heterogeneous pathological process using parsimony phylogenetics. Gene expression microarray data of ovarian endometriosis obtained from NCBI database were polarized and coded into derived (abnormal) and ancestral (normal) states. Such alterations are referred to as synapomorphies in a phylogenetic sense (or biomarkers). Subsequent gene linkage was modeled by Genomatix BiblioSphere Pathway software. A list of clonally shared derived (abnormal) expressions revealed the pattern of heterogeneity among specimens. In addition, it has identified disruptions within the major regulatory pathways including those involved in cell proliferation, steroidogenesis, angiogenesis, cytoskeletal organization and integrity, and tumorigenesis, as well as cell adhesion and migration. Furthermore, the analysis supported the potential central involvement of ESR2 in the initiation of endometriosis. The pathogenesis mapping showed that eutopic and ectopic lesions have different molecular biosignatures.

Melatonin protects against endometriosis via regulation of matrix metalloproteinase-3 and an apoptotic pathway

The role of matrix metalloproteinases (MMPs) in endometriosis, a gynecological disease of women, is unclear. The study investigated the activity of MMP-3 and its interplay with MMP-9 during the onset of endometriosis. Additionally, the importance of MMP-3 on the apoptotic pathway in endometriosis and effect of melatonin thereon were investigated. A Significant increase in the activity of MMP-3 with the severity of endometriosis in human was observed which was found similar in mice also. During the early phase of endometriosis, MMP-3 but not MMP-9 was increased and associated with the expression of transcription factor, c-Fos. Moreover, urokinase plasminogen activator and tissue inhibitor of metalloproteinase (TIMP)-3 were involved in MMP-3 regulation during endometriosis. Furthermore, MMP-3 activity that was parallel to c-Fos expression in endometriosis was reduced by melatonin pretreatment as characterized by diminished activator protein (AP)-1 DNA-binding activity. Because decreased apoptosis is an explanation for the perpetuation of endometriosis, we tested the role of melatonin on apoptotic pathway in preventing endometriosis. Significant regression of glandular epithelium was observed in melatonin-treated when compared to untreated mice. Melatonin treatment increased apoptotic cells in endometriotic zones. This was related to reduced Bcl-2 expression along with increased Bax expression and caspase-9 activation. In summary, early induction of MMP-3 was distinct from MMP-9 during endometriosis, which was regulated by c-Fos and TIMP-3. Melatonin suppressed MMP-3 activity and amplified apoptosis while regressing endometriosis through a caspase-3 mediated pathway. Thus, melatonin may be a therapeutic agent for resolving endometriosis.

Theoretical targets for TCDD: a bioinformatics approach

Dioxins are a group of highly toxic molecules that exert their toxicity through the activation of the aryl hydrocarbon receptor (AhR). The most important agonist of the AhR, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic compound. Although most of the effects related to TCDD exposure have been linked to the activation of AhR, the objective of this work was to use a bioinformatics approach to identify possible new targets for TCDD. The Target Fishing Docking (TarFisDock) Server was used to find target proteins for TCDD. This virtual screening allowed the identification of binding sites with high affinity for TCDD in diverse proteins, such as metallopeptidases 8 and 3, oxidosqualene cyclase, and myeloperoxidase. Some of these proteins are well known for their biochemical role in some pathological effects of dioxin exposure, including endometriosis, diabetes, inflammation and liver damage. These results suggest that TCDD could also be interacting with cellular targets though AhR-independent pathways.

Reciprocal communication between endometrial stromal cells and macrophages

This study tested the hypothesis that reciprocal communication occurs between macrophages and cultured human endometrial stromal cells and that this communication may contribute to the pathology of endometriosis. An endometrial stromal cell line (telomerase-immortalized human endometrial stromal cell [T-HESC]) was treated with macrophage-conditioned medium (CM) +/- estradiol + progesterone. Macrophages were treated without or with T-HESC CM. DNA microarray identified 716 differentially expressed genes in T-HESCs in response to factors secreted by macrophages. Upregulated genes in T-HESC included interleukin 8 (IL-8)/chemokine (C-X-C motif) ligand 8 (CXCL8), matrix metalloproteinase 3 (MMP3), phospholamban, cysteine-rich angiogenic inducer 61 (CYR61), connective tissue growth factor (CTGF), tenascin C, and nicotinamide N-methyltransferase (NNMT), whereas integrin alpha-6 was downregulated. In contrast, 15 named genes were differentially expressed in macrophages in response to factors secreted by endometrial stromal cells. The data document reciprocal communication between macrophages and endometrial stromal cells and suggest that interaction with macrophages stimulates the expression of genes in endometrial stromal cells that may support the establishment of endometriosis.

Endometriotic epithelial cells induce MMPs expression in endometrial stromal cells via an NFkappaB-dependent pathway

OBJECTIVE

To explore the stroma-epithelium interactions in endometriosis and to identify the possible signalling pathways involved in this cross-talk.

DESIGN

Laboratory study via primary cultured endometrial stromal and epithelial cells.

SETTING

University Hospital.

PATIENTS

Fifteen patients with endometriosis confirmed by histopathology were recruited in the study, and 12 women free of endometriosis were used as control group.

INTERVENTION(S)

Specific NFkappaB inhibitor 1-Pyrrolidinecarbodithioic acid ammonium salt (PDTC) was used in cell cultures.

MAIN OUTCOME MEASURE(S)

The expression and secretion of MMP-2, MMP-9, TIMP-1, TIMP-2 and the DNA-binding activity of NFkappaB in normal endometrial stromal cells or in co-cultures with normal or endometriotic epithelial cells from patients with endometriosis.

RESULT(S)

Endometrial epithelial cells induced MMP-9 and MMP-2 expression in normal stromal cells in vitro. In co-cultures with endometriotic epithelial cells, normal endometrial stromal cells expressed and secreted higher MMP-2 (p < 0.05) and MMP-9 (p < 0.05). Specific inhibition of NFkappaB pathway in stromal cells abolished this induction effect by epithelial cells.

CONCLUSION(S)

Endometriotic epithelial cells induce MMPs expression and secretion in normal endometrial stromal cells via an NFkappaB-dependent pathway in vitro. This cross-talk between epithelial cells and stromal cells may facilitate the implantation and extension of the ectopic foci and favour the development of the disease.

Neutralizing TIMP1 restores fecundity in a rat model of endometriosis and treating control rats with TIMP1 causes anomalies in ovarian function and embryo development

Human and rat endometriotic lesions synthesize and secrete tissue inhibitor of metalloproteinase 1 (TIMP1). More TIMP1 localizes in the ovarian theca in an established rat model for endometriosis (Endo) when compared to surgical controls (Sham). We hypothesized that endometriotic TIMP1 secreted into peritoneal fluid (PF) negatively affects ovarian function and embryogenesis by altering the balance of matrix metalloproteinases (MMPs) and TIMPs. Three experiments were performed modulating TIMP1 in vitro and in vivo to investigate ovarian and embryonic anomalies. The first experiment demonstrated control embryos treated in vitro with endometriotic PF concentrations of TIMP1 developed abnormally. In the second experiment where TIMP1 was modulated in vivo, TIMP1-treated Sham rats had fewer zygotes, ovarian follicles, and corpora lutea (CLs) and poorer embryo quality and development, which is analogous to the findings in Endo rats. Importantly, Endo rats treated with a TIMP1 function-blocking antibody had zygote, follicle, and CL numbers and embryo quality similar to Sham rats. In addition, more TIMP1 inhibitory activity was found in ovaries from Endo and TIMP1-treated Sham rats than in ovaries from Sham or TIMP1 antibody-treated Endo rats. In experiment three, control rats (no surgery) treated with Endo PF had fewer follicles and CLs and increased TIMP1 localization in the ovarian theca whereas treatment with Endo PF stripped of TIMP1 or with Sham PF had no effect, providing further evidence that endometriotic TIMP1 sequesters in the ovary and inhibits MMPs necessary for ovulation. Collectively, these results showed that excessive TIMP1 was deleterious to ovulation and embryo development. Thus, novel TIMP1-modulating therapies may be developed to alleviate infertility in women with endometriosis.

Abnormal regulation of chemokine TECK and its receptor CCR9 in the endometriotic milieu is involved in pathogenesis of endometriosis by way of enhancing invasiveness of endometrial stromal cells

The chemokine thymus-expressed chemokine (TECK), which regulates T-cell development and tissue-specific homing, has been identified as a potential contributor to the pathogenesis and progression of endometriosis. Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD), an air pollutant, and estrogen also appear to be involved in endometriosis. Both endometrial stromal cells (ESCs) and the combination of 17beta-estradiol and TCDD increase the secretion of TECK in the endometriosis-associated cells and promote the invasiveness of ESCs by increasing expression of matrix metalloproteinase (MMP)-2 and MMP-9. Anti-TECK neutralizing antibodies can effectively inhibit the invasiveness of ESCs and the expression of MMP-2 and MMP-9 in the cells. Interestingly, the expression of chemokine C receptor 9 (CCR9) and its ligand TECK increases significantly in the endometriotic milieu of patients with endometriosis. Therefore, the over-expressed TECK interacts with CCR9 on the ESCs in the endometriotic milieu, which may contribute to the onset and progression of endometriosis.

Doxycycline causes regression of endometriotic implants: a rat model

BACKGROUND

Doxycycline (Dox) has a number of non-antibiotic properties. One of them is the inhibition of matrix metalloproteinase (MMP) activity. The aim of this study was to assess the effects of Dox in a rat endometriosis model.

METHODS

Endometriosis was surgically induced in 40 rats by transplanting of endometrial tissue. After 3 weeks, repeat laparotomies were performed to check the implants and the animals were randomized into four groups: Group I, low-dose Dox (5 mg/kg/day); Group II, high-dose Dox (40 mg/kg/day); Group III, leuprolide acetate 1 mg/kg single dose, s.c.; and Group VI (controls), no medication. The treatment, initiated on the day of surgery and continuing for 3 weeks, was administered to the study groups. Three weeks later, the rats were euthanized and the implants were evaluated morphologically and histologically for immunoreactivity of MMP-2 and -9, and interleukin-6 (IL-6) concentration in the peritoneal fluid was assayed.

RESULTS

Treatment with leuprolide acetate, or high-dose or low-dose Dox caused significant decreases in the implant areas compared with the controls (P = 0.03, P = 0.006, and P = 0.001, respectively). IL-6 levels in peritoneal fluid decreased in Group I (P = 0.02) and Group III (P < 0.05). MMP H scores were significantly lower in the group that received low-dose Dox in both epithelial and stromal MMP-2 and -9 immunostaining when compared with the control group [P = 0.048, P = 0.002, P = 0.007 and P = 0.002, respectively, MMP-2 (epithelia), MMP-2 (stroma), MMP-9 (epithelia) and MMP-9 (stroma)].

CONCLUSIONS

Low-dose Dox caused regression of endometriosis in this experimental rat model.

The role of matrix metalloproteinases in the pathogenesis of endometriosis

Endometriosis is a benign, estrogen-dependent disease with an obscure etiology. Even the most widely accepted theory of retrograde menstruation cannot satisfactorily explain the development of endometriosis due to the many gaps in our understanding of its pathophysiology. Although most women have retrograde menstruation; only some develop endometriosis. Apart from simply being present in the peritoneal cavity, the endometrial cells are able to attach to, invade the peritoneum, and proliferate to create and maintain an endometriotic lesion. Matrix metalloproteinases (MMPs) are a group of enzymes that degrade the extracellular matrix. These enzymes participate in the histologic changes of the endometrium during the menstrual cycle with generally a higher expression during the menstrual and proliferative phase of the endometrium and a decreased expression during the secretory phase. As noted above, not only do these enzymes play a crucial factor in the cycling endometrium but the degradation of extracellular matrix is essential for the endometrial cells to invade the peritoneum and to develop an endometriotic lesion as well. The aim of this review is to describe the altered expression of MMPs in the development of endometriosis.

Serial analysis of gene expression reveals differential expression between endometriosis and normal endometrium. Possible roles for AXL and SHC1 in the pathogenesis of endometriosis

BACKGROUND

Endometriosis is a clinical condition that affects up to 10% of the women of reproductive age. Endometriosis is characterized by the presence of endometrial tissues outside the uterine cavity and can lead to chronic pelvic pain, infertility and, in some cases, to ovarian cancer.

METHODS

In order to better understand the pathogenesis of endometriosis, we have used Serial Analysis of Gene Expression (SAGE) to identify genes differentially in this disease by studying three endometriotic tissues and a normal endometrium sample. Promising candidates (AXL, SHC1, ACTN4, PI3KCA, p-AKT, p-mTOR, and p-ERK) were independently validated by immunohistochemistry in additional normal and endometriotic tissues.

RESULTS

We identified several genes differentially expressed between endometriosis and normal endometrium. IGF2, ACTN4, AXL, and SHC1 were among the most upregulated genes. Comparison of the endometriosis gene expression profiles with the gene expression patterns observed in normal human tissues allowed the identification of endometriosis-specific genes, which included several members of the MMP family (MMP1,2,3,10,11,14). Immunohistochemical analysis of several candidates confirmed the SAGE findings, and suggested the involvement of the PI3K-Akt and MAPK signaling pathways in endometriosis.

CONCLUSION

In human endometriosis, the PI3K-Akt and MAPK signaling pathways may be activated via overexpression of AXL and SHC1, respectively. These genes, as well as others identified as differentially expressed in this study, may be useful for the development of novel strategies for the detection and/or therapy of endometriosis.

Reduced fecundity in female rats with surgically induced endometriosis and in their daughters: a potential role for tissue inhibitors of metalloproteinase 1

The cause of reduced fecundity in women with endometriosis is unknown. Expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) by both ectopic and eutopic endometrium reportedly has a role in the pathogenesis of endometriosis. We hypothesize that anomalous endometriotic TIMP protein synthesis, secretion, and localization also cause reproductive pathologies resulting in reduced fecundity. An established rat model for endometriosis (Endo) compared with nonendometriotic controls (Shams) was used to investigate reduced fecundity in endometriosis. Comparing Endo and Sham rats, Endo rats had altered ovarian dynamics, including fewer ovarian follicles and corpora lutea with luteinized unruptured follicles. Furthermore, in vivo anomalies in postovulatory oocyte structure and preimplantation embryo development, including misaligned chromosomes, nuclear and cytoplasmic fragmentation, and delayed or arrested cleavage, as well as spontaneous abortions, were found only in Endo rats. A causative role for TIMP1 in these phenomena is supported by our findings that Endo rats have more TIMP1 in their peritoneal fluid as detected by ELISA and more TIMP1 immunolocalization in the theca of antral follicles as measured by computer-assisted morphometric analysis. These data suggest that in endometriosis the accumulation of TIMP1 disrupts the normal MMP/TIMP enzymatic milieu in the peritoneal cavity and negatively affects ovarian dynamics, oocyte quality, and preimplantation embryo development, thereby decreasing fecundity. Most intriguingly, daughters of Endo rats that had no experimental interventions exhibited these same reproductive abnormalities. We predict that developmental exposure to endometriosis leads to permanent epigenetic changes in subsequent generations.

Role of melatonin in regulating matrix metalloproteinase-9 via tissue inhibitors of metalloproteinase-1 during protection against endometriosis

Endometriosis is a gynecological disease of women and plausibly regulated by matrix metalloproteinases (MMPs). However, mechanisms of alterations in MMPs during endometriosis remain unclear. Human endometriotic tissues possessing varying degrees of severity were examined for expression of MMPs and tissue inhibitors of metalloproteinase (TIMP)-1. In addition, endometriosis was generated in mice and endometriotic tissues were tested for MMP-9 activity. Results show significant upregulation of secreted and synthesized proMMP-9 activity with duration and severity of endometriosis. Along with upregulation of activity, the expression of proMMP-9 was found increased while TIMP-1 expression followed an inverse trend. The effect of melatonin, a major secretory product of the pineal gland, on endometriosis was examined in preventive and therapeutic models in mice. The results show that melatonin arrested lipid peroxidation and protein oxidation and downregulated proMMP-9 activity and expression in a time and dose-dependent manner while protecting and regressing peritoneal endometriosis. Moreover, the attenuated activity and expression of proMMP-9 were associated with subsequent elevation in the expression of TIMP-1. Our study reveals for the first time the role of melatonin in arresting peritoneal endometriosis in mice and a novel marker, expression ratio of proMMP-9 versus TIMP-1, was identified for assessing severity and progression of endometriosis.

Endometriosis and Genetic Polymorphisms

Endometriosis is a benign gynecological disease with an unclear pathophysiology characterized by ectopic endometrium causing endometrium-like inflammatory lesions outside the uterine cavity. Recently, a number of studies have investigated genetic polymorphisms as a possible factor contributing to the development of endometriosis. In this review, we have summarized current data regarding genes with nucleotide polymorphisms investigated with regard to endometriosis. We searched PubMed for publications on endometriosis and polymorphism and found 108 publications between January 1979 and September 2005. These were classified according to the type of genetic polymorphism investigated and whether the result favored or did not favor association with endometriosis. We found a strikingly large amount of conflicting results. About 50% of the reviewed studies demonstrated positive correlations between different polymorphisms and endometriosis. This relation is most clearly seen in groups 1 (cytokines and inflammation), 2 (steroid-synthesizing enzymes and detoxifying enzymes and receptors), 4 (estradiol metabolism), 5 (other enzymes and metabolic systems), and 7 (adhesion molecules and matrix enzymes). Group 8 (apoptosis, cellcycle regulation, and oncogenes) seemed to be negatively correlated with the disease, whereas group 3 (hormone receptors), 6 (growth factor systems), and especially 9 (human leukocyte antigen system components) showed a relatively strong correlation. The review indicates that polymorphisms may have a limited value in assessing possible development of endometriosis.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the complexity of attempting to link endometriosis to single nucleotide polymorphisms (SNPs), explain that the literature is varied on results and recommendations and is population specific, and state that there are some SNP relationships that are clinically stronger than others.

Expression of angiogenic factors in endometriosis: relationship to fibrinolytic and metalloproteinase systems

BACKGROUND

Endometriosis is a highly prevalent, benign disease in which the angiogenic, fibrinolytic and metalloproteinase (MMP) systems may be implicated. The objective of this study is to analyse mRNA expression and protein levels of several angiogenic factors and to correlate them with several components of the fibrinolytic and MMP systems in samples from 71 women with endometriosis and 50 controls.

METHODS AND RESULTS

Eutopic endometrium showed higher mRNA expression of vascular endothelial growth factor (VEGF) in patients than in controls. However, ovarian endometrioma had lower VEGF mRNA levels than did the eutopic endometrium of patients. Similar results were obtained for VEGF protein levels. On the other hand, a significant increase in thrombospondin-1 (TSP-1) levels was observed in ovarian endometrioma than in eutopic endometrium. The peritoneal fluid from women with endometriosis showed a significant increase in VEGF, urokinase-type plasminogen activator (uPA) and MMP-3 levels than that of controls. A significant correlation was observed between the levels of VEGF and uPA in endometrium and in peritoneal fluid.

CONCLUSIONS

Endometrium and peritoneal fluid from women with endometriosis have increased levels of VEGF, uPA and MMP-3 levels. Therefore, the development of endometriotic implants at ectopic sites may be facilitated, promoting the progress of the endometriosis.

Endometriosis is characterized by an impaired localization of laminin-5 and alpha3beta1 integrin receptor

Endometriosis is an estrogen-correlated benign disease characterized by a marked ability of endometrial-like cells to invade and proliferate outside uterine cavity, resembling for some invasive aspect the cancer growth. The molecular mechanisms regulating endometrial cell invasiveness are mostly unknown, although interactions between extracellular matrix (ECM) proteins and their transmembrane receptors, integrins, are likely to play a central role. In particular, laminin (Ln)-5 could be closely involved, as it is in cancer. We have investigated the expression of Ln-1, Ln-5, and collagen IV (Coll IV) ECM proteins and their receptors, alpha3beta1 and alpha6beta4 integrins, in atrophic, proliferative, and secretive endometrium and in endometriosis. The results show that Ln-5, but not Ln-I and Coll IV, is altered in secretive endometrium as well as in endometriosis tissues. No alterations are observed in atrophic or proliferative endometrium. Consistently, the polarization of both integrin subunits alpha3 and beta1, but not alpha6 and beta4, is altered in secretive endometrium and endometriosis tissues, but not in atrophic and proliferative endometrium. These results seem to suggest that Ln-5 and alpha3beta1 could be involved in the invasive mechanism of endometriosis. The altered expression of Ln-5, by upregulating matrix metalloproteases activity, suggest an invading process similar to that of many cancer processes.

Serum and endometrial markers

Endometriosis is a benign but aggressive disease. It occurs when shed endometrium from the female reproductive tract grows at a site outside the uterus. The physiological changes in endometriosis-abnormal tissue growth, invasion, and adhesion phenomena-are similar to those seen in tumorous tissues. Although the etiology of endometriosis is not well understood, the disease is widely accepted to result from the ectopic implantation of refluxed menstrual tissues. In addition, immunologic changes, genetic factors, and environmental factors might also affect a woman's susceptibility to develop endometriosis. Thus far, laparoscopic examination is required to confirm the presence of endometriosis; there is no reliable marker for its diagnosis. Many studies are therefore focusing on identifying markers for the diagnosis and follow-up of endometriosis. This chapter provides a systematic review of these studies, including recent findings from our group on the identification of molecules, in serum and/or endometrium, which are associated with the development of endometriosis at different stages. From this research, we hope to be able to suggest how to approach the potential markers. The identification of highly sensitive and specific markers of endometriosis should facilitate the development of accurate and non-invasive techniques for diagnosis and prognosis.

Nuclear factor-kappab (NF-kappaB): an unsuspected major culprit in the pathogenesis of endometriosis that is still at large?

Endometriosis, defined as the ectopic presence of endometrial glandular and stromal cells outside the uterine cavity, is a common benign gynecological disorder with an enigmatic pathogenesis. Many genes and gene products have been reported to be altered in endometriosis, yet some of them may not be major culprits but merely unwitting accomplices or even innocent bystanders. Therefore, the identification and apprehension of major culprits in the pathogenesis of endometriosis are crucial to the understanding of the pathogenesis and would help to develop better therapeutics for endometriosis. Although so far NF-kappaB only has left few traces of incriminating fingerprints, several lines of investigation suggest that NF-kappaB, a pivotal pro-inflammatory transcription factor, could promote and maintain endometriosis. Various inflammatory agents, growth factors, and oxidative stress activate NF-kappaB. NF-kappaB proteins themselves and proteins regulated by them have been linked to cellular transformation, proliferation, apoptosis, angiogenesis, and invasion. Interestingly, all existing and nearly all investigational medications for endometriosis appear to act through suppression of NF-kappaB activation. In endometriotic cells, NF-kappaB appears to be constitutively activated, and suppression of NF-kappaB activity by NF-kappaB inhibitors or proteasome inhibitors suppresses proliferation in vitro. Viewing NF-kappaB as a major culprit, an autoregulatory loop model can be postulated, which is consistent with existing data and, more importantly, can explain several puzzling phenomena that are otherwise difficult to interpret based on prevailing theories. This view has immediate and important implications for novel ways to treat endometriosis. Further research is warranted to precisely delineate the roles of NF-kappaB in the pathogenesis of endometriosis and to indict and convict its aiders and abettors.

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.

Increased expression of matrix metalloproteinase-9 in the eutopic endometrial tissue of women with endometriosis

BACKGROUND

Endometriosis is a disease where endometrial tissue implants in ectopic locations. Remodelling of the extracellular matrix (ECM) is a prerequisite for the implantation of this tissue to be possible.

METHODS

In this study, we detected immunoreactive matrix metalloproteinase-9 (MMP-9) throughout endometrial tissue and identified von Willebrand factor (vWF)-positive endothelial cells, CD45-positive leukocytes, CD3-positive T lymphocytes and CD68-positive macrophages as cells expressing MMP-9 in the stroma.

RESULTS

We found an increased expression of MMP-9 in the uterine endometrial tissue of women with endometriosis, as assessed by zymography and enzyme-linked immunosorbent assay (ELISA) (P < 0.05). However, RT-PCR did not show a statistically significant increase in MMP-9 mRNA expression in these tissues (P = 0.14). There was no significant difference between women with and without endometriosis in the expression of tissue inhibitor of MMPs (TIMP)-1, a known natural inhibitor of the pro- and active forms of MMP-9, whether tested by ELISA or by RT-PCR (P = 0.46 and 0.37, respectively). Interestingly, the ratio of MMP-9/TIMP-1 expression was significantly higher in women with endometriosis than in normal women both at the protein and the mRNA levels (P < 0.05).

CONCLUSION

These findings make plausible the involvement of MMP-9/TIMP-1 imbalance in the invasiveness of the endometrial tissue of patients with endometriosis and the ectopic development of the disease.

Polymorphisms in the promoter regions of the matrix metalloproteinases-7, -9 and the risk of endometriosis and adenomyosis in China

Matrix metalloproteinases (MMPs) may contribute to the development of endometriosis. The aim of this study was to assess the effects of the polymorphisms in the promoters of MMP-7 (181A/G) and MMP-9 (1562C/T) on the risk of occurrence of endometriosis and adenomyosis. We genotyped 219 patients (143 women with endometriosis, 76 women with adenomyosis) and 160 control women in North China. There was a significant difference in frequency of the MMP-7 genotype between endometriosis and controls (P = 0.01) and also between adenomyosis and controls (P = 0.01). The frequency of the G allele in two groups of patients (7.3 and 7.9%) was significantly higher than in the controls (2.8%) (P = 0.01 and 0.01, respectively). Compared to the A/A genotype, the genotype with the -181G allele showed a significantly increased susceptibility to both diseases, with adjusted odds ratio of 2.62 [95% confidence interval (CI) = 1.17-5.87] for endometriosis and 3.14 (95% CI = 1.26-7.81) for adenomyosis. However, the overall genotype and allelotype distribution of the MMP-9 in the two case groups were not different from that of controls. We conclude that MMP-7-181A/G polymorphism has a potential to be a susceptibility factor for endometriosis and adenomyosis while MMP-9-1562C/T polymorphism may not provide a useful marker to predict susceptibility to endometriosis and adenomyosis, at least in women from North China.

Estrogen receptor beta and matrix metalloproteinase 1 are coexpressed in uterine endometrium and endometriotic lesions of patients with endometriosis

OBJECTIVE

To evaluate the local matrix metalloproteinase 1 (MMP-1), estrogen receptor (ER) alpha, and ERbeta protein expression in eutopic and dystopic tissue from patients with endometriosis and to compare the endometrial expression pattern in women with and without endometriosis.

DESIGN

Immunohistochemical analysis of MMP-1, ERalpha, and ERbeta in paired samples of uterine and endometriotic endometrium from cycling women with endometriosis and in endometrial tissue from 37 healthy women.

SETTING

Research laboratory at a medical school.

PATIENT(S)

Thirty-seven matched samples from endometriotic and corresponding endometrial biopsies obtained during the proliferative and secretory phase. Thirty-seven endometrial biopsies obtained from healthy women during comparable cycle phases.

INTERVENTION(S)

Sampling of endometrial and endometriotic tissue.

MAIN OUTCOME MEASURE(S)

Matrix metalloproteinase 1, ERalpha, and ERbeta protein expression in paraffin-embedded tissue biopsies was measured by IHC.

RESULT(S)

In patients with endometriosis, epithelial and stromal cells from endometriotic lesions both express significantly higher levels of MMP-1 and lower levels of ERalpha than corresponding cells in uterine endometrium. Endometriotic epithelium also expresses higher levels of ERbeta than of ERalpha. In both endometrial glands and corresponding endometriotic epithelium, the distribution of MMP-1 is correlated with ERbeta. No significant differences in endometrial ERalpha, ERbeta, or MMP-1 expression could, however, be detected when patients with endometriosis and healthy controls were compared.

CONCLUSION(S)

We have shown that MMP-1 and ERbeta are coexpressed and up-regulated in endometriotic lesions, whereas local ERalpha expression is down-regulated. The altered ERbeta/ERalpha ratio in endometriotic glands suggests that estrogenic effects on MMP-1 are primarily mediated via ERbeta, and the local control of MMP-1 in eutopic endometrium is not different from that observed in healthy cycling women.

Concentrations of interleukin (IL)-1alpha, IL-1 soluble receptor type II (IL-1 sRII) and IL-1 receptor antagonist (IL-1 Ra) in the peritoneal fluid and serum of infertile women with endometriosis

OBJECTIVE

Endometriosis is an immune system-related gynaecological disease, characterised by an increase in number and activation of peritoneal macrophages. One of macrophage-derived factors is interleukin (IL)-1. The effects of IL-1 are inhibited by IL-1 receptor type II (IL-1 RII), soluble forms of IL-1 RII (IL-1 sRII) and IL-1 receptor antagonist (IL-1 Ra). The aim of our work was to study the IL-1alpha, IL-1 sRII and IL-1 Ra levels in the peritoneal fluid (PF) and serum of women with endometriosis in relation to stage of disease.

STUDY DESIGN

Concentrations of IL-1alpha, IL-1 sRII and IL-1 Ra were measured by ELISA assay in the PF and serum of 58 women; 43 with and 15 without endometriosis (control group).

RESULTS

Elevated PF and serum IL-1alpha and IL-1 Ra levels in the women with endometriosis in comparison with the control group were observed. IL-1 sRII levels in PF and serum were higher in the controls than in the women with endometriosis. Concentrations of IL-1alpha and IL-1 sRII were higher in advanced endometriosis, but higher IL-1 Ra was observed in the early stage of the disease.

CONCLUSION

Impairment of regulation IL-1 activity in the peritoneal fluid and serum of women with endometriosis may play an important role in the pathogenesis and development of the disease.

The function of the SNP in the MMP1 and MMP3 promoter in susceptibility to endometriosis in China

Matrix metalloproteinases (MMPs) may contribute to the development of endometriosis. Genetic variations in several MMP promoters may influence the transcription and expression of MMPs. The purpose of the present study was to assess how gene polymorphisms in the MMP1 and MMP3 promoters affect the risk of development of endometriosis. We genotyped 100 women with endometriosis and 150 control subjects in North China. There was a significant difference in frequency of the MMP1 genotype between cases and controls (P=0.03). The 2G homozygote in endometriosis and controls was significantly different (P=0.02). The frequency of the 2G allele among affected women (79%) was significantly higher than among the healthy controls (66.9%; P=0.003). However, the overall genotype and allelotype distribution of the MMP3 single nucleotide polymorphism (SNP) in patients was not different from that of controls (P> or =0.05). MMP1 and MMP3 polymorphisms were in linkage disequilibrium in cases and controls (D'=0.47; P=0.00). The haplotype frequency distribution derived from these two polymorphisms was significantly different between cases and controls (P=0.00). The haplotype analysis suggested an implication of both MMP1 and MMP3 polymorphisms in the susceptibility to endometriosis. We conclude that the MMP1 promoter SNP and MMP 2G/6A haplotype may modify susceptibility to endometriosis, but that the MMP3 promoter SNP is unlikely to be associated with endometriosis in the population of North China.

Matrix remodeling and endometriosis

The physiological changes in endometriosis involving multiple steps of matrix remodeling include abnormal tissue growth, invasion, and adhesion formation. Endometriosis-associated abnormal matrix remodeling is affected by several molecular factors including proteolytic enzymes and their inhibitors, which mediate tissue turnover throughout the reproductive tract to maintain the integrity of the endometrium, and ovarian steroids, which normally regulate reconstruction and breakdown of endometrium in the menstrual cycle. In addition, various growth factors, such as platelet-derived growth factor, transform growth factor β, and epidermal growth factor, direct modulation of growth, activation, and chemotaxis which may facilitate endometrial cell adhesion onto the peritoneal mesothelium during the development of endometriosis. Furthermore, cell adhesion molecules are believed to be critically involved in most cellular-level processes including cellular differentiation, motility, and attachment with the extracellular matrix. The present review focuses on the abnormal matrix remodeling process and its possible regulatory mechanism in association with endometriosis development. As a greater understanding of the cause of endometriosis is achieved, better treatment of the disease and its prevention become possible. (Reprod Med Biol 2005; 4: 93-99).

Interleukin 1α and tissue-lytic matrix metalloproteinase-1 are elevated in ectopic endometrium of patients with endometriosis

BACKGROUND

Matrix metalloproteinases (MMP) play an essential role in tissue remodelling and menstruation and appear to be regulated by cytokines such as interleukin-1alpha (IL-1alpha). In order to investigate their role in the pathogenesis of endometriosis, the aim of the present study was to compare the protein localization of matrix metalloproteinase-1 (MMP-1) and of its main stimulatory cytokine IL-1alpha in eutopic and dystopic endometrium of patients with endometriosis.

METHODS

MMP-1 and IL-1alpha protein localization was analysed retrospectively in paired paraffin-embedded tissue biopsies obtained simultaneously from the endometrial cavity and from endometrial lesions of 37 patients with peritoneal or ovarian endometriosis and in cycling endometria from 37 women without endometriosis. Protein localization was demonstrated by immunohistochemistry; antibody specificity was confirmed by western blot analysis.

RESULTS

MMP-1 and IL-1alpha protein staining in women suffering from endometriosis was significantly more pronounced in endometriotic lesions than in eutopic endometrium. This held true for both epithelial MMP-1 and IL-1alpha staining (P < 0.006 and P < 0.001), and for stromal MMP-1 and IL-1alpha staining (P < 0.001 and P < 0.001). Furthermore, stromal MMP-1 and IL-1alpha were significantly co-expressed in dystopic endometriotic tissue (P = 0.045). Endometrial MMP-1 and IL-1alpha protein expression pattern in eutopic endometrium from women suffering from endometriosis, however, did not differ significantly from the pattern seen in healthy women.

CONCLUSIONS

The increased expression of both matrix-degrading MMP-1 and its major stimulatory cytokine IL-1alpha in endometriotic lesions and the selective co-expression in the stroma of endometriotic foci clearly suggests their involvement in the pathogenic mechanisms leading to local invasion and tissue destruction.