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

Host response during unresolved urinary tract infection alters female mammary tissue homeostasis through collagen deposition and TIMP1

Exposure to pathogens throughout a lifetime influences immunity and organ function. Here, we explore how the systemic host-response to bacterial urinary tract infection (UTI) induces tissue-specific alterations to the mammary gland. Utilizing a combination of histological tissue analysis, single cell transcriptomics, and flow cytometry, we identify that mammary tissue from UTI-bearing mice displays collagen deposition, enlarged ductal structures, ductal hyperplasia with atypical epithelial transcriptomes and altered immune composition. Bacterial cells are absent in the mammary tissue and blood of UTI-bearing mice, therefore, alterations to the distal mammary tissue are mediated by the systemic host response to local infection. Furthermore, broad spectrum antibiotic treatment resolves the infection and restores mammary cellular and tissue homeostasis. Systemically, unresolved UTI correlates with increased plasma levels of the metalloproteinase inhibitor, TIMP1, which controls extracellular matrix remodeling and neutrophil function. Treatment of nulliparous and post-lactation UTI-bearing female mice with a TIMP1 neutralizing antibody, restores mammary tissue normal homeostasis, thus providing evidence for a link between the systemic host response during UTI and mammary gland alterations.

Diminished Ovarian Reserve in Endometriosis: Insights from In Vitro, In Vivo, and Human Studies-A Systematic Review

Endometriosis, a prevalent disorder in women of reproductive age, is often associated with undesired infertility. Ovarian reserve, an essential measure of ovarian function that is crucial for maintaining fecundity, is frequently diminished in women with endometriosis. Though the causative relationship between endometriosis and reduced ovarian reserve is not fully understood due to the lack of standardized and precise measurements of ovarian reserve, there is ongoing discussion regarding the impact of interventions for endometriosis on ovarian reserve. Therefore, in this review, we investigate articles that have related keywords and which were also published in recent years. Thereafter, we provide a comprehensive summary of evidence from in vitro, in vivo, and human studies, thereby shedding light on the decreased ovarian reserve in endometriosis. This research consolidates evidence from in vitro, in vivo, and human studies on the diminished ovarian reserve associated with endometriosis, as well as enhances our understanding of whether and how endometriosis, as well as its interventions, contribute to reductions in ovarian reserve. Furthermore, we explore potential strategies to modify existing therapy options that could help prevent diminished ovarian reserve in patients with endometriosis.

Single-cell analysis of menstrual endometrial tissues defines phenotypes associated with endometriosis

BACKGROUND

Endometriosis is a common, complex disorder which is underrecognized and subject to prolonged delays in diagnosis. It is accompanied by significant changes in the eutopic endometrial lining.

METHODS

We have undertaken the first single-cell RNA-sequencing (scRNA-Seq) comparison of endometrial tissues in freshly collected menstrual effluent (ME) from 33 subjects, including confirmed endometriosis patients (cases) and controls as well as symptomatic subjects (who have chronic symptoms suggestive of endometriosis but have not been diagnosed).

RESULTS

We identify a unique subcluster of proliferating uterine natural killer (uNK) cells in ME-tissues from controls that is almost absent from endometriosis cases, along with a striking reduction of total uNK cells in the ME of cases (p < 10^-16). In addition, an IGFBP1+ decidualized subset of endometrial stromal cells are abundant in the shed endometrium of controls when compared to cases (p < 10^-16) confirming findings of compromised decidualization of cultured stromal cells from cases. By contrast, endometrial stromal cells from cases are enriched in cells expressing pro-inflammatory and senescent phenotypes. An enrichment of B cells in the cases (p = 5.8 × 10^-6) raises the possibility that some may have chronic endometritis, a disorder which predisposes to endometriosis.

CONCLUSIONS

We propose that characterization of endometrial tissues in ME will provide an effective screening tool for identifying endometriosis in patients with chronic symptoms suggestive of this disorder. This constitutes a major advance, since delayed diagnosis for many years is a major clinical problem in the evaluation of these patients. Comprehensive analysis of ME is expected to lead to new diagnostic and therapeutic approaches to endometriosis and other associated reproductive disorders such as female infertility.

The effect of endometriosis on fertility in an animal model

The present experimental model aimed to investigate the possible effect of endometriosis on ovarian function by altering follicular maturation and development. This single-blind, randomized study included twenty-four female Sprague Dawley mice, 2.5 months old, weighing 160-200 grams. The animals were randomly separated into four groups on the day of the surgery. Each group consisted of 6 mice. The first group (A) consisted of healthy female mice (control group). The second group (B) consisted of mice subjected to surgical insertion of ovarian endometrioma. The third group (C) consisted of mice subjected to surgically induced diffuse intraperitoneal endometriosis, and the fourth group (D) consisted of mice subjected to surgically induced extraperitoneal endometriosis. According to our experimental model, endometriosis may affect ovarian function by increasing the number of luteinized unruptured follicles (follicles that have undergone luteinization without prior rupture).

TIMP1 may affect goat prolificacy by regulating biological function of granulosa cells

Tissue inhibitor of metalloproteinase 1 (TIMP1) is associated with animal reproductive processes, such as follicular growth, ovulation, luteinization, and embryo development in mammals. The purposes of this study were to explore the expression and localization of TIMP1 in the ovarian tissues and determine the effect of TIMP1 on the function of granulosa cells and the association of TIMP1 with lambing-related genes of the goats. Immunohistochemical analysis showed that TIMP1 protein was strongly expressed by granulosa cells. Enzyme-linked immunosorbent assay (ELISA) results showed that TIMP1 overexpression promoted the secretion of estradiol of granulosa cells after 12, 24, and 48 h of transfection. Moreover, in vitro experiments indicated that TIMP1 had the ability to promote the cell proliferation and elevate the transcriptional levels of four genes associated with goat prolificacy, including BMPR-1B, BMP15, GDF9, and FSHB, in granulosa cells. In conclusion, TIMP1 could be an important molecule in regulating reproductive performance of the goats by affecting estrogen secretion and cell proliferation, as well as the expression of lambing-related genes of granulosa cells in the goats.

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 Ethanol Extract of Avocado (Persea americana Mill. (Lauraceae)) Seeds Successfully Induces Implant Regression and Restores Ovarian Dynamic in a Rat Model of Endometriosis

Endometriosis is an estrogen-dependent disease with conventional therapies which do not have desirable effectiveness and possess many side effects. Scientific evidences suggest that medicinal plants with antioxidant, anti-inflammatory, and/or antiproliferative properties are potential alternatives for the treatment of endometriosis. The ethanol extract of Persea americana Mill. (Lauraceae) seeds was found exhibiting antiproliferative properties in vitro and in vivo. This study therefore is aimed at investigating the effects of such an extract on an experimental model of endometriosis. Endometriosis was induced by grafting uterine fragments onto the peritoneum of female Wistar rats. After checking the success of the transplantation surgery, animals with endometriosis were orally treated with the ethanol extract of P. americana seeds at the doses of 12.5, 25, and 50 mg/kg. The positive control was treated with letrozole (10 mg/kg) while the negative control received the vehicle. Treatments lasted 7 days and animals were sacrificed thereafter. Endometrial implant volume was determined. Estradiol and progesterone levels were measured in serum samples and endometriosis lesions. The oxidative status of endometriosis lesions was evaluated. Histological analysis of endometriosis lesions, uterus, and ovaries was also performed. Results showed that the ethanol extract of P. americana seeds decreased endometrial implant volume (p < 0.001) and serum levels of estradiol and progesterone (p < 0.01). The levels of estradiol also decreased in endometriosis lesions at doses of 12.5 and 50 mg/kg (p < 0.001). Both malondialdehyde and glutathione levels increased in endometriosis lesions (p < 0.001). The ectopic endometrium height decreased and the number of antral follicles and corpora lutea (p < 0.05) increased while that of luteinized unruptured follicles decreased (p < 0.001). In conclusion, the ethanol extract of P. americana seeds displayed an antiendometriosis effect suggesting that it could be a potential alternative for the treatment of endometriosis.

Identifying Mechanisms of Endometriosis-Associated Reduced Fecundity in a Rat Model: Novel Insights toward Understanding Human Infertility

The existence of endometriosis has been known since at least the nineteenth century, yet the lack of understanding of causes of infertility and therefore inadequate treatment approaches in endometriosis creates a significant challenge in reproductive medicine. Women worldwide suffer not only pain and infertility but also economical, societal, and physiological burdens. Studies of reproductive events in women are difficult to conduct due to a host of confounding personal and environmental factors and ethically limited due to the very nature of working with reproductive tissues and cells, especially embryos. Animal models are a viable adjunct to study mechanisms causing human reproductive anomalies and infertility in endometriosis. This chapter discusses reproductive anomalies causing infertility in endometriosis and well-established animal models which help decipher the problems and lead to heretofore unknown nonsurgical, nonhormonal methods to manage endometriosis in women. In addition, studies of effects of developmental exposure to endometriosis are revealing for the first time, in both female and male offspring, transgenerational subfertility in a rat model providing insights into the familial nature of endometriosis and possible epigenetic involvement.

Soy Intake Since the Prepubertal Age May Contribute to the Pathogenesis of Endometriosis in Adulthood

High prevalence of endometriosis was reported in Asian women as a result of their traditionally high intake of soy foods during infancy. Soy is widely used in infant feeding after weaning from breast milk or cow milk. This study thus aimed to determine to what extent soy intake before puberty may contribute to the development of endometriosis. For this purpose, immature (6-week old) female rats were fed with various soy formulas (0%, 10%, 20%, 30%, 40%, 50%, and 60%). Normal control animals were fed with a soy-free diet. At 13 weeks of age, animals (except the normal control) underwent a transplantation surgery to establish endometriosis. Estradiol valerate and oxytocin were used to induce pelvic pain. Endometrial implant levels of glutathione (GSH) and malondialdehyde (MDA) allowed estimating tissue oxidative status. Physiological ovarian function was assessed by histological analysis of ovaries. Results showed that soy-fed animals grew faster than animals receiving a soy-free diet (P < .001). In animals supplemented with more than 10% of soy, the intensity of pelvic pain increased (P < .001) as well as the volume of ectopic foci. In addition, tissue levels of MDA and GSH increased (P < .001). The ovarian function was altered and the number of luteinized unruptured follicles increased. In conclusion, although animals supplemented with soy at the prepubertal stage displayed a good growth performance, regular soy consumption may promote the development and progress of endometriosis in adulthood, especially when soy content in food is more than 10%.

Doxycycline reduces MMP-2 activity and inhibits invasion of 12Z epithelial endometriotic cells as well as MMP-2 and -9 activity in primary endometriotic stromal cells in vitro

BACKGROUND

Matrix metalloproteinases (MMPs), especially the gelatinases MMP-2 and MMP-9, play a crucial role in the pathogenesis of endometriosis by enabling invasion. Doxycycline is a well-tolerated antibiotic and a potent MMP-inhibitor in subantimicrobial doses.

METHODS

Gelatin zymography and activity assays were used to detect latent and active MMP-2 and -9 in cell culture supernatants of immortalized epithelial (12Z) and two isolates of primary endometriotic stromal cells treated with doxycycline. The invasiveness of 12Z endometriotic cells treated with doxycycline was assessed in matrigel-coated invasion chambers. The effect on latent and active MMP-2 expression of the combination of progesterone and doxycycline was tested in 12Z.

RESULTS

Doxycycline significantly reduced the MMP-2 activity and pro-MMP-2 expression in 12Z and the MMP-2 and -9 activity as well as expression of pro-MMP-2 and -9 in primary endometriotic stromal cells. The percentage of 12Z cells invading through a matrigel-coated membrane was reduced to 65 and 22% of the control after treatment with doxycycline at doses of 1 μg/ml and 10 μg/ml, respectively. Furthermore, a combination of progesterone and doxycycline showed an additive effect in low doses on the reduction of MMP-2 activity and pro-MMP2 expression in 12Z endometriotic cells.

CONCLUSIONS

In conclusion, the MMP-inhibiting features of subantimicrobial-dose doxycycline may be further evaluated as a well-tolerable additional therapeutic approach, e.g. in combination with progestins such as dienogest, in patients with infiltrative endometriosis with insufficient response to current medical treatment options.

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 Root Aqueous Extract of Entada africana Guill. et Perr. (Mimosaceae) Inhibits Implant Growth, Alleviates Dysmenorrhea, and Restores Ovarian Dynamic in a Rat Model of Endometriosis

Entada africana (Mimosaceae) was reported to have analgesic and antioxidant properties. The present study is aimed at investigating the effects of the root aqueous extract of Entada africana (EA) on an experimental model of endometriosis. The study was performed in rats orally treated with EA at doses of 127.5, 255, and 510 mg/kg. Microgynon® 30 served as the reference substance. Estradiol valerate and oxytocin were used to induce dysmenorrhea. Endometrial implant levels of catalase and malondialdehyde (MDA) allowed estimating tissue oxidative status. Ovarian dynamic and rat sexual behavior were assessed through histological analysis of ovaries, uterus, and vagina. EA decreased dysmenorrhea at tested doses following a 7-day treatment (p < 0.001). Endometrial implant volume decreased following the three treatment periods (p < 0.05). Catalase activity (p < 0.001) and MDA level (p < 0.01) increased only following a 3-day treatment. EA also increased antral follicles, reduced luteinized unruptured follicle number (p < 0.001), and induced animals to be in the estrus phase. In conclusion, EA prevented the progress of endometriosis, reduced dysmenorrhea, promoted ovarian follicle growth, prevented anovulation, and stimulated the special period of rat sexual desire. These results suggest that Entada africana could be a promising alternative option for the treatment of endometriosis.

Relevant human tissue resources and laboratory models for use in endometriosis research

Endometriosis is characterized by the growth of endometrium‐like tissue outside the uterus, most commonly on the pelvic peritoneum and ovaries. Although it may be asymptomatic in some women, in others it can cause debilitating pain, infertility or other symptoms including fatigue. Current research is directed both at understanding the complex etiology and pathophysiology of the disorder and at the development of new nonsurgical approaches to therapy that lack the unwanted side effects of current medical management. Tools for endometriosis research fall into two broad categories; patient‐derived tissues, and fluids (and cells isolated from these sources) or models based on the use of cells or animals. In this review, we discuss the literature that has reported data from the use of these tools in endometriosis research and we highlight the strengths and weaknesses of each. Although many different models are reported in the literature, hypothesis‐driven research will only be facilitated with careful experimental design and selection of the most appropriate human tissue from patients with and without endometriosis and combinations of physiologically relevant in vitro and in vivo laboratory models.

Cervical mucus proteome in endometriosis

Background

Endometriosis is a chronic gynecological inflammatory disease characterized by the presence of functional endometrial glands and stroma outside of the uterine cavity. It affects 7–10% of women of reproductive age and up to 50% of women with infertility. The current gold standard for the diagnosis combines laparoscopic evaluation and biopsy of the visualized lesions. However, laparoscopy requires general anesthesia and developed surgical skills and it has a high procedural cost. In addition, it is associated with the risk, although rare, of potential intraoperative or postoperative complications. To date, several noninvasive biomarkers have been proposed; however, no definite diagnostic biomarker is yet available. The aim of this study was to characterize the CM proteome in patients with endometriosis using high resolution mass spectrometry—based proteomics, implemented by bioinformatic tools for quantitative analysis, in order to investigate the pathophysiological mechanisms of endometriosis.

Methods

Cervical mucus samples were collected from patients affected by endometriosis and fertile controls. An aliquot of the soluble acidic fraction of each cervical mucus sample, corresponding to 0.5 mg of total protein, was left to digest with sequencing grade modified porcine trypsin. The peptides were analyzed by LC–MS/MS on a high resolution Orbitrap Elite mass spectrometer and data were evaluated using bioinformatic tools.

Results

We aimed at the first total profiling of the cervical mucus proteome in endometriosis. From the list of identified proteins, we detected a number of differentially expressed proteins, including some functionally significant proteins. Six proteins were quantitatively increased in endometriosis, almost all being involved in the inflammatory pattern. Nine proteins were quantitatively reduced in endometriosis, including some proteins related with local innate immunity (CRISP-3 and Pglyrp1) and protection against oxidative stress (HSPB1). Fifteen proteins were not detected in endometriosis samples including certain proteins involved in antimicrobial activity (SLURP1 and KLK13) and related to seminal plasma liquefaction and male fertility (KLK13).

Conclusions

This is the first application of high resolution mass spectrometry—based proteomics aimed in detecting an array of proteins in CM to be proposed for the noninvasive diagnosis of endometriosis. This chronic disease presents in CM an inflammatory protein pattern.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-017-9142-4) contains supplementary material, which is available to authorized users.

Expression pattern of matrix metalloproteinases changes during folliculogenesis in the cat ovary

Matrix metalloproteinase (MMP) has been implicated as having roles in ovarian folliculogenesis. Here, we determined the expression pattern of six MMPs (MMP1, MMP2, MMP3, MMP7, MMP9 and MMP13) and their endogenous tissue inhibitor, TIMP1, during cat follicle growth. Different developmental stage follicles were mechanically isolated and gene expression analysed by real-time qPCR while MMP1, 2, 9 and 13 localization was determined by immunohistochemistry. With the exception of MMP13, the amount of MMP mRNA was lowest in primordial follicles and increased thereafter. Peak levels were detected in early antral follicles for MMP1 (72.2-fold increase above primordial follicle amount), MMP2 (10-fold), MMP3 (57-fold) and MMP9 (2.8-fold). MMP7 transcripts increased 2-fold by the primary follicle stage and then plateaued. MMP13 mRNA peaked in primary follicles (2.5-fold) and was lower in more advanced counterparts. TIMP1 sharply increased (6-fold) in secondary follicles and gradually declined in the later stages. MMP1 and MMP9 expression were expressed in the granulosa cells of all follicle stages. MMP2 was immunoreactive in early and antral follicles, especially at granulosa cells adjacent to the antral cavity. By contrast, the MMP13 was weakly detected in primary follicles onward. In summary, there are distinctive and consistent changes in MMPs and TIMP1 expression during follicle development, suggesting that these enzymes play one or more roles in cat folliculogenesis. In particular, high mRNA and protein expression levels of MMP1 and MMP2, especially at the antral stage, indicate that these enzymes likely are involved in antrum formation and expansion.

Reduced Proteolytic Shedding of Receptor Tyrosine Kinases Is a Post-Translational Mechanism of Kinase Inhibitor Resistance

Kinase inhibitor resistance often involves upregulation of poorly understood "bypass" signaling pathways. Here, we show that extracellular proteomic adaptation is one path to bypass signaling and drug resistance. Proteolytic shedding of surface receptors, which can provide negative feedback on signaling activity, is blocked by kinase inhibitor treatment and enhances bypass signaling. In particular, MEK inhibition broadly decreases shedding of multiple receptor tyrosine kinases (RTK), including HER4, MET, and most prominently AXL, an ADAM10 and ADAM17 substrate, thus increasing surface RTK levels and mitogenic signaling. Progression-free survival of patients with melanoma treated with clinical BRAF/MEK inhibitors inversely correlates with RTK shedding reduction following treatment, as measured noninvasively in blood plasma. Disrupting protease inhibition by neutralizing TIMP1 improves MAPK inhibitor efficacy, and combined MAPK/AXL inhibition synergistically reduces tumor growth and metastasis in xenograft models. Altogether, extracellular proteomic rewiring through reduced RTK shedding represents a surprising mechanism for bypass signaling in cancer drug resistance.

SIGNIFICANCE

Genetic, epigenetic, and gene expression alterations often fail to explain adaptive drug resistance in cancer. This work presents a novel post-translational mechanism of such resistance: Kinase inhibitors, particularly targeting MAPK signaling, increase tumor cell surface receptor levels due to widely reduced proteolysis, allowing tumor signaling to circumvent intended drug action.

Developmental exposure of fetal ovaries and fetal germ cells to endometriosis in an endometriosis model causes differential gene expression in the preimplantation embryos of the first-generation and second-generation embryos

OBJECTIVE

To characterize multigenerational gene expression anomalies in eight-cell stage embryos associated with developmental exposure to endometriosis.

DESIGN

Using an endometriosis model in rats (F0 founder generation) to evaluate gene expression in F1 (fetal exposure) and F2 (fetal germ cell exposure) generation eight-cell stage embryos.

SETTING

Laboratory.

ANIMAL(S)

Endometriosis model in rats (Endo) and controls (Sham).

INTERVENTION(S)

F0 Endo and Sham rats were bred; half the pregnant rats were killed on gestational day 3 to collect F1 eight-cell stage embryos and the others gestated to term (F1 females). Adult F1 females bred; F2 eight-cell embryos collected.

MAIN OUTCOME MEASURE(S)

Maintenance of differential gene expression in F1 and F2 generation eight-cell embryos in endometriosis.

RESULT(S)

Developmental exposure to endometriosis altered the gene signaling pathways, with changes found in apoptosis, the cell cycle process, the response to oxidative stress, negative regulation of molecular function, and RNA processing. The apoptotic genes Diablo, Casp3, Parp1, Cad, and Dnaja3 were increased and the Nfkbia transcripts were decreased in F1 Endo versus F1 Sham embryos. In F2 Endo versus Sham embryos, Casp3 and Cad were statistically significantly increased, and Parp1 and Nfkbia tended to be elevated.

CONCLUSION(S)

Fetal and germ cell exposure to endometriosis alters apoptotic gene expression in first- and second-generation eight-cell stage embryos, supporting the hypothesis of multigenerational inheritance resulting from exposure to endometriosis in utero.

Cellular and molecular basis for endometriosis-associated infertility

Endometriosis is a gynecological disease characterized by the presence of endometrial glandular epithelial and stromal cells growing in the extra-uterine environment. The disease afflicts 10%–15% of menstruating women causing debilitating pain and infertility. Endometriosis appears to affect every part of a woman’s reproductive system including ovarian function, oocyte quality, embryo development and implantation, uterine function and the endocrine system choreographing the reproductive process and results in infertility or spontaneous pregnancy loss. Current treatments are laden with menopausal-like side effects and many cause cessation or chemical alteration of the reproductive cycle, neither of which is conducive to achieving a pregnancy. However, despite the prevalence, physical and psychological tolls and health care costs, a cure for endometriosis has not yet been found. We hypothesize that endometriosis causes infertility via multifaceted mechanisms that are intricately interwoven thereby contributing to our lack of understanding of this disease process. Identifying and understanding the cellular and molecular mechanisms responsible for endometriosis-associated infertility might help unravel the confounding multiplicities of infertility and provide insights into novel therapeutic approaches and potentially curative treatments for endometriosis.

Elevated peritoneal fluid TNF-α incites ovarian early growth response factor 1 expression and downstream protease mediators: a correlation with ovulatory dysfunction in endometriosis

Endometriosis-associated infertility manifests itself via multiple, poorly understood mechanisms. Our goal was to characterize signaling pathways, between peritoneal endometriotic lesions and the ovary, leading to failed ovulation. Genome-wide microarray analysis comparing ovarian tissue from an in vivo endometriosis model in the rat (Endo) with controls (Sham) identified 22 differentially expressed genes, including transiently expressed early growth response factor 1 (Egr1). The Egr1 regulates gene requisites for ovulation. The Egr1 promoter is responsive to tumor necrosis factor-alpha (TNF-α) signaling. We hypothesized that altered expression of ovarian EGR1 is induced by elevated peritoneal fluid TNF-α which is upregulated by the presence of peritoneal endometriosis. Endo rats, compared to controls, had more peritoneal fluid TNF-α and quantitative, spatial differences in Egr1 mRNA and EGR1 protein localization in follicular compartments. Interactions between elevated peritoneal fluid TNF-α and overexpression of follicular Egr1/EGR1 expression may affect downstream protease pathways impeding ovulation in endometriosis. Preliminary studies identified similar patterns of EGR1 protein localization in human ovaries from women with endometriosis and compared to those without endometriosis.

Inflammation, NK cells and implantation: friend and foe (the good, the bad and the ugly?): replacing placental viviparity in an evolutionary perspective

This review summarises an invited talk presented at the 2012 ESRI/ASRI meeting in Hamburg, concerning current views of inflammation in pregnancy, which is timely given that the effects of a local injury in the uterus acts to favour implantation. Recalling that inflammation can be good (it is useful and necessary for implantation), bad (in implantation failure, RSA) and ugly (at the extreme, endometriosis is associated with pain and infertility) leads to consideration of its status in pregnancy. Its role in implantation and the fact that pregnancy maintains some aspects of inflammation throughout, leads to revision of not only concepts of immunosuppression and the Th1/Th2 paradigm, but also the feto-maternal relationship as seen since Medawar's hypotheses were advanced. This is examined from an evolutionary perspective, which should lead to further review of our perception of uterine NK cells, and the emergence of Treg cells to control some aspects of adaptive immunity, which appeared long after placentation.

Expression profile of extracellular matrix and adhesion molecules in the development of endometriosis in a mouse model

Ectopic endometrial tissue induces various reactions in surrounding tissues, such as the surface of the ovary and peritoneal cavity, leading to endometriosis. The aim of this study is to investigate the expression profile of extracellular matrix (ECM) and adhesion molecules in the early steps of development of experimental mouse endometriosis, specifically in peritoneum adjacent to endometrium transplants attached via autotransplantation. The endometriosis model was induced by autotransplantation of endometrium to peritoneal tissue. Peritoneal tissues adjacent to the transplant were obtained at 1, 4, and 7 days posttransplantation. The results showed that messenger RNA expression levels of most of the integrins, collagens, and other ECM reached a peak at 7 days posttransplantation. Uniquely, Lamc2 was significantly increased to its maximum level within 24 hours posttransplantation and may be strongly associated with initiation of the development of endometriosis. These data will be helpful in further investigations of the treatment of endometriosis.

Role of estrogen receptor signaling required for endometriosis-like lesion establishment in a mouse model

Endometriosis results from ectopic invasion of endometrial tissue within the peritoneal cavity. Aberrant levels of the estrogen receptor (ER), ERα and ERβ, and higher incidence of autoimmune disorders are observed in women with endometriosis. An immunocompetent mouse model of endometriosis was used in which minced uterine tissue from a donor was dispersed into the peritoneal cavity of a recipient. Wild-type (WT), ERα-knockout (αERKO), and βERKO mice were donors or recipients to investigate the roles of ERα, ERβ, and estradiol-mediated signaling on endometriosis-like disease. Mice were treated with vehicle or estradiol, and resulting location, number, and size of endometriosis-like lesions were assessed. In comparison with WT lesions in WT hosts, αERKO lesions in WT hosts were smaller and fewer in number. The effect of ER status and estradiol treatment on nuclear receptor status, proliferation, organization, and inflammation within lesions were examined. αERKO lesions in WT hosts did not form distal to the incision site, respond to estradiol, or proliferate but did have increased inflammation. WT lesions in αERKO hosts did respond to estradiol, proliferate, and show decreased inflammation with treatment, but surprisingly, progesterone receptor expression and localization remained unchanged. Only minor differences were observed between WT lesions in βERKO hosts and βERKO lesions in WT hosts, demonstrating the estradiol-mediated signaling responses are predominately through ERα. In sum, these results suggest ER in both endometriosis-like lesions and their environment influence lesion characteristics, and understanding these interactions may play a critical role in elucidating this enigmatic disease.

TIMP1 contributes to ovarian anomalies in both an MMP-dependent and -independent manner in a rat model

Ovulatory dysfunction occurs in women with endometriosis, yet the mechanisms are unknown. We have shown that endometriotic lesions synthesize and secrete tissue inhibitor of metalloproteinase (TIMP) 1 into the peritoneal cavity in humans and a rat model of endometriosis, where excess TIMP1 localizes in the ovarian theca in endometriosis and modulating peritoneal TIMP1 alters ovarian dynamics. Here, we evaluated whether mechanisms whereby excessive peritoneal fluid TIMP1 negatively impacts ovarian function are matrix metalloproteinase (MMP)-dependent and/or MMP-independent actions. Rats were treated with a mutated TIMP1 without MMP inhibitory function (Ala-TIMP1), wild-type TIMP1 (rTIMP1), or PBS. Rats treated with Ala-TIMP1 or rTIMP1 had fewer antral follicles, fewer new corpora lutea, and the presence of luteinized unruptured follicle syndrome compared with PBS rats. Ala-TIMP1 and rTIMP1 differentially caused downstream changes in gene expression and protein localization related to ovulation, as measured by whole-genome microarray with quantitative real-time PCR validation and immunohistochemistry. More vascular endothelial growth factor and FN were expressed and localized in ovaries of Ala-TIMP1-treated rats compared to rTIMP1- and PBS-treated rats inferring MMP-independent functions. Less caspase 3 localized in ovaries of rTIMP1 compared with the other two groups, and was thus dependent on MMP action. Furthermore, after coimmunoprecipitation, more CD63 was bound to TIMP1 in ovaries of rats treated with Ala-TIMP1 than in rTIMP1-treated rats, providing evidence for another MMP-independent mechanism of ovulatory dysfunction. We predict that MMP-dependent and MMP-independent events are involved in improper fortification of the follicular wall through multiple mechanisms, such as apoptosis inhibition, extracellular matrix components and angiogenesis. Collectively, excessive peritoneal TIMP1 causes changes in ovarian dynamics, both dependently and independently of MMP inhibition.