The Estrogen Early Response Gene FOS Is Altered in a Baboon Model of Endometriosis1

The Known, the Unknown and the Future of the Pathophysiology of Endometriosis

Endometriosis is one of the most common causes of chronic pelvic pain and infertility, affecting 10% of women of reproductive age. A delay of up to 9 years is estimated between the onset of symptoms and the diagnosis of endometriosis. Endometriosis is currently defined as the presence of endometrial epithelial and stromal cells at ectopic sites; however, advances in research on endometriosis have some authors believing that endometriosis should be re-defined as "a fibrotic condition in which endometrial stroma and epithelium can be identified". There are several theories on the etiology of the disease, but the origin of endometriosis remains unclear. This review addresses the role of microRNAs (miRNAs), which are naturally occurring post-transcriptional regulatory molecules, in endometriotic lesion development, the inflammatory environment within the peritoneal cavity, including the role that cytokines play during the development of the disease, and how animal models have helped in our understanding of the pathology of this enigmatic disease.

The Role of Platelets in the Pathogenesis and Pathophysiology of Adenomyosis

Widely viewed as an enigmatic disease, adenomyosis is a common gynecological disease with bewildering pathogenesis and pathophysiology. One defining hallmark of adenomyotic lesions is cyclic bleeding as in eutopic endometrium, yet bleeding is a quintessential trademark of tissue injury, which is invariably followed by tissue repair. Consequently, adenomyotic lesions resemble wounds. Following each bleeding episode, adenomyotic lesions undergo tissue repair, and, as such, platelets are the first responder that heralds the subsequent tissue repair. This repeated tissue injury and repair (ReTIAR) would elicit several key molecular events crucial for lesional progression, eventually leading to lesional fibrosis. Platelets interact with adenomyotic cells and actively participate in these events, promoting the lesional progression and fibrogenesis. Lesional fibrosis may also be propagated into their neighboring endometrial-myometrial interface and then to eutopic endometrium, impairing endometrial repair and causing heavy menstrual bleeding. Moreover, lesional progression may result in hyperinnervation and an enlarged uterus. In this review, the role of platelets in the pathogenesis, progression, and pathophysiology is reviewed, along with the therapeutic implication. In addition, I shall demonstrate how the notion of ReTIAR provides a much needed framework to tether to and piece together many seemingly unrelated findings and how it helps to make useful predictions.

AP-1 Subunit JUNB Promotes Invasive Phenotypes in Endometriosis

Endometriosis is a disease defined by the presence of abnormal endometrium at ectopic sites, causing pain and infertility in 10% of women. Mutations in the chromatin remodeling protein ARID1A (AT-rich interactive domain-containing protein 1A) have been identified in endometriosis, particularly in the more severe deep infiltrating endometriosis and ovarian endometrioma subtypes. ARID1A has been shown to regulate chromatin at binding sites of the Activator Protein 1 (AP-1) transcription factor, and AP-1 expression has been shown in multiple endometriosis models. Here, we describe a role for AP-1 subunit JUNB in promoting invasive phenotypes in endometriosis. Through a series of knockdown experiments in the 12Z endometriosis cell line, we show that JUNB expression in endometriosis promotes the expression of epithelial-to-mesenchymal transition genes co-regulated by ARID1A including transcription factors SNAI1 and SNAI2, cell adhesion molecules ICAM1 and VCAM1, and extracellular matrix remodelers LOX and LOXL2. In highly invasive ARID1A-deficient endometriotic cells, co-knockdown of JUNB is sufficient to suppress invasion. These results suggest that AP-1 plays an important role in the progression of invasive endometriosis, and that therapeutic inhibition of AP-1 could prevent the occurrence of deep infiltrating endometriosis.

RNA-Sequencing based analysis of bovine endometrium during the maternal recognition of pregnancy

BACKGROUND

Maternal recognition is the crucial step for establishing pregnancy in cattle. This study aims to identify endometrial genes and biological pathways involved in the maternal recognition of pregnancy. Caruncular endometrial tissues were collected from Day 15-17 of gestation (pregnant), non-pregnant (absence of conceptus), and cyclic (non-bred) heifers.

RESULTS

Total RNAs were isolated from the caruncular endometrial tissues of pregnant, non-pregnant, and cyclic heifers, and were subjected to high-throughput RNA-sequencing. The genes with at least two-fold change and Benjamini and Hochberg p-value ≤ 0.05 were considered differentially expressed genes and further confirmed with quantitative real-time PCR. A total of 107 genes (pregnant vs cyclic) and 98 genes (pregnant vs non-pregnant) were differentially expressed in the pregnant endometrium. The most highly up-regulated genes in the pregnant endometrium were MRS2, CST6, FOS, VLDLR, ISG15, IFI6, MX2, C15H11ORF34, EIF3M, PRSS22, MS4A8, and TINAGL1. Interferon signaling, immune response, nutrient transporter, synthesis, and secretion of proteins are crucial pathways during the maternal recognition of pregnancy.

CONCLUSIONS

The study demonstrated that the presence of conceptus at Day 15-17 of gestation affects the endometrial gene expression related to endometrial remodeling, immune response, nutrients and ion transporters, and relevant signaling pathways in the caruncular region of bovine endometrium during the maternal recognition of pregnancy.

A mouse model of endometriosis mimicking the natural spread of invasive endometrium

STUDY QUESTION

Is it possible to establish a genetically engineered mouse model (GEMM) of endometriosis that mimics the natural spread of invasive endometrium?

SUMMARY ANSWER

Endometriosis occurs in an ARID1A (AT-rich interactive domain-containing protein 1A) and PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha) mutant GEMM of endometrial dysfunction following salpingectomy.

WHAT IS KNOWN ALREADY

Although mouse models of endometriosis have long been established, most models rely on intraperitoneal injection of uterine fragments, steroid hormone treatments or the use of immune-compromised mice.

STUDY DESIGN, SIZE, DURATION

Mice harboring the lactotransferrin-Cre (LtfCre0/+), Arid1afl, (Gt)R26Pik3ca*H1047R and (Gt)R26mTmG alleles were subject to unilateral salpingectomies at 6 weeks of age. Control (n = 9), LtfCre0/+; (Gt)R26Pik3ca*H1047R; Arid1afl/+ (n = 8) and LtfCre0/+; (Gt)R26Pik3ca*H1047R; Arid1afl/fl (n = 9) were used for the study. The (Gt)R26mTmG allele was used for the purpose of fluorescent lineage tracing of endometrial epithelium. LtfCre0/+; (Gt)R26mTmG (n = 3) and LtfCre0/+; (Gt)R26Pik3ca*H1047R/mTmG; Arid1afl/fl (n = 4) were used for this purpose. Mice were followed until the endpoint of vaginal bleeding at an average time of 17 weeks of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

At 6 weeks of age, mice were subjected to salpingectomy surgery. Mice were followed until the time point of vaginal bleeding (average 17 weeks), or aged for 1 year in the case of control mice. At time of sacrifice, endometriotic lesions, ovaries and uterus were collected for the purpose of histochemical and immunohistochemical analyses. Samples were analyzed for markers of the endometriotic tissue and other relevant biomarkers.

MAIN RESULTS AND THE ROLE OF CHANCE

Following salpingectomy, LtfCre0/+; (Gt)R26Pik3ca*H1047R/mTmG; Arid1afl/fl mice developed endometriotic lesions, including lesions on the ovary, omentum and abdominal wall. Epithelial glands within lesions were negative for ARID1A and positive for phospho-S6 staining, indicating ARID1A-PIK3CA co-mutation status, and expressed EGFP (enhanced green fluorescent protein), indicating endometrial origins.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

LtfCre0/+; (Gt)R26Pik3ca*H1047R; Arid1afl/fl mice develop vaginal bleeding as a result of endometrial dysfunction at an average age of 17 weeks and must be sacrificed. Furthermore, while this model mimics the natural spread of endometriotic tissue directly from the uterus to the peritoneum, the data presented do not reject current hypotheses on endometriosis pathogenesis.

WIDER IMPLICATIONS OF THE FINDINGS

The idea that endometriosis is the result of abnormal endometrial tissue colonizing the peritoneum via retrograde menstruation has gained widespread support over the past century. However, most models of endometriosis take for granted this possibility, relying on the surgical removal of bulk uterine tissue and subsequent transplantation into the peritoneum. Growing evidence suggests that somatic mutations in ARID1A and PIK3CA are present in the endometrial epithelium. The establishment of a GEMM which mimics the natural spread of endometrium and subsequent lesion formation supports the hypothesis that endometriosis is derived from mutant endometrial epithelium with invasive properties.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the American Cancer Society PF-17-163-02-DDC (M.R.W.), the Mary Kay Foundation 026-16 (R.L.C.) and the Ovarian Cancer Research Fund Alliance 457446 (R.L.C.). The authors declare no competing interests.

Nerve fibre infiltration and expression in peritoneal lesions of endometriosis in a nonhuman primate model of endometriosis

Baboon ( Papio anubis) models of endometriosis are thought to mimic the early stages of spontaneous human peritoneal endometriotic disease. The objective of this study was to investigate the presence and course of nerve fibre ingrowth during peritoneal lesion formation in specimens collected at 3 months (early stage of lesion development) and 15 months (late stage of lesion development) after disease initiation compared to pelvic peritoneum (control). Five-micron sections of paraffin-embedded peritoneal lesions were obtained from normally cycling baboons with 3-month (n = 12), 15-month (n = 12) induced endometriosis and pelvic peritoneum (n = 10) from baboons with no endometriosis. Immunohistochemical staining was performed with specific antibodies: protein gene product 9.5 – broad marker of nerve fibres and neurones, neuropeptide Y – sympathetic neurones, substance P – sensory neurones, vasoactive intestinal peptide – parasympathetic neurones, nerve growth factor – development of new neurones and high-affinity receptor for nerve growth factor (tropomyosin receptor kinase A) – neuronal differential. Significantly, more nerve fibres were identified in peritoneal endometriotic lesions collected 15 months after the initiation of experimental protocols compared with 3-month and control samples (p < 0.001). Nerve fibres were immunoreactive for all the tested markers – protein gene product 9.5, neuropeptide Y, substance P, vasoactive intestinal peptide, nerve growth factor and tropomyosin receptor kinase A – indicating the presence of different types of nerve fibres. In conclusion, peritoneal lesions of endometriosis in a nonhuman primate model of endometriosis were found to be progressively and spontaneously innervated by both myelinated and unmyelinated sensory nerve fibres, parasympathetic and sympathetic neurones. These nerve fibres may play an important role in the mechanisms of pain generation in this condition.

Human chorionic gonadotropin promotes cell proliferation through the activation of c-Met in gastric cancer cells

Hormones and their receptors affect the development process of gastric cancer. Previous studies have revealed that human chorionic gonadotropin (hCG) is expressed in gastric cancer tissue. However, the mechanism by which hCG exerts its effects on gastric cancer cells had not been reported. In the present study, the expression of hCG and its receptor was detected in gastric cancer tissues and para-carcinoma tissues of 62 patients with gastric carcinoma. Following the treatment of gastric cancer cells SGC-7901 with hCG, a cell counting kit-8 assay, flow cytometry, a colony formation assay and a xenograft tumor model in nude mice were used to detect the effect of hCG on cell proliferation; and the expression of c-Met was determined by western blot analysis. The expression of hCG and its receptor were significantly higher in gastric cancer tissues compared with that of the matched para-carcinoma tissue (P<0.01). Proliferation of SGC-7901 cells treated with hCG was significant higher and the number of cells at the G₂/M phase of the cell cycle increased compared with the control cells. Hepatocyte growth factor transmembrane protein receptor expression was increased in hCG-treated cells compared with the control cells, which relies on the protein kinase A signaling pathway. The present study revealed the potential function of hCG in the development of gastric cancer, suggesting that hCG may be a molecular marker and potential drug target in gastric cancer.

The Early Genes c-fos and c-jun: Potential Targets to Modulate Estrogen Action in Endometriosis?

Endometriosis is a common estrogen-dependent disorder. C-fos and c-jun are early transcription factors probably related to estradiol-dependent cell proliferation. C-fos gene expression is higher in endometriotic implants compared to normal endometrium and the distribution of c-Fos protein is higher in the stroma of endometriotic tissue. C-Jun expression is also more abundant in ectopic endometrial tissue. These findings point to an increased estrogen signaling in endometriosis and suggest that c-fos and c-jun could be potential targets to emerging treatments designed to affect selectively the endometriotic tissue, such as tissue-specific gene therapy.

Progesterone Resistance in Endometriosis Is Modulated by the Altered Expression of MicroRNA-29c and FKBP4

CONTEXT

Endometriosis results in aberrant gene expression in the eutopic endometrium (EuE) and subsequent progesterone resistance. MicroRNA (miR) microarray data in a baboon model of endometriosis showed an increased expression of miR-29c.

OBJECTIVES

To explore the role of miR-29c in progesterone resistance in a subset of women with endometriosis.

DESIGN

MiR-29c expression was analyzed in the endometrium of baboons and women with or without endometriosis. The role in progesterone resistance and decidualization was analyzed by transfecting human uterine fibroblast cells with miR-29c.

PATIENTS

Subjects diagnosed with deep infiltrative endometriosis (DIE) by transvaginal ultrasound with bowel preparation underwent surgical excision of endometriosis. Eutopic secretory endometrium was collected pre- and postoperatively. Women with normal EuE and without DIE served as controls.

RESULTS

Quantitative reverse transcription polymerase chain reaction demonstrated that miR-29c expression increased, while the transcript levels of its target, FK506-binding protein 4 (FKBP4), decreased in the EuE of baboons following the induction of endometriosis. FKBP4 messenger RNA and decidual markers were statistically significantly decreased in decidualized human uterine fibroblast cells transfected with a miR-29c mimic compared with controls. Human data corroborated our baboon data and demonstrated higher expression of miR-29c in endometriosis EuE compared with normal EuE. MiR-29c was significantly decreased in endometriosis EuE postoperatively compared with preoperative tissues, and FKBP4 showed an inverse trend following radical laparoscopic resection surgery.

CONCLUSIONS

We demonstrate that miR-29c expression is increased in EuE of baboons and women with endometriosis, which might contribute to a compromised progesterone response by diminishing the levels of FKBP4. Resection of DIE is likely to reverse the progesterone resistance associated with endometriosis in women.

Protein Inhibitor of Activated STAT3 (PIAS3) Is Down-Regulated in Eutopic Endometrium of Women with Endometriosis

Endometriosis is a major cause of chronic pelvic pain and infertility. Activation of STAT3 appears central to the inflammatory phenotype of eutopic endometrium in women with endometriosis. However, the molecular mechanism by which this occurs remains unknown. Our objective is to determine how STAT3 activity is regulated in endometriosis. Protein inhibitor of activated STAT3 (PIAS3) is a negative regulator of STAT3 activity. We examined the levels of PIAS3 in endometrium from women with and without endometriosis using Western blot analysis and immunohistochemistry. Levels of PIAS3 are significantly lower, in contrast with phosphorylation of STAT3, in women with endometriosis compared to women without endometriosis. Furthermore, induction of endometriosis in the baboon showed a significant reduction of PIAS3 expression during the progression of the disease. Interferon-γ (INFγ) reduces PIAS3 protein levels and increases phospho-STAT3 levels through CXCL10 in endometrial cells, Ishikawa, and 12Z cells. These results suggest that attenuation of PIAS3 causes aberrant activation of STAT3 in endometriosis, leading to inflammatory changes that may impair fertility or cause pain.

Dysregulation of Lysyl Oxidase Expression in Lesions and Endometrium of Women With Endometriosis

Lysyl oxidases (LOXs) are enzymes involved in collagen deposition, extracellular membrane remodeling, and invasive/metastatic potential. Previous studies reveal an association of LOXs and endometriosis. We aimed to identify the mechanisms activated by upregulation of lysyl oxidases (LOX) in endometriotic cells and tissues. We hypothesized that LOX plays a role in endometriosis by promoting invasiveness and epithelial to mesenchymal transition (EMT).

METHODS

The LOX protein expression levels were measured by immunohistochemistry in lesions and endometrium on a tissue microarray (TMA) and in endometrial biopsies from patients and controls during the window of implantation (WOI). Estradiol regulation of LOX expression was determined by quantitative polymerase chain reaction (qPCR). Proliferation, invasion, and migration assays were performed in epithelial (endometrial epithelial cell), endometrial (human endometrial stromal cell), and endometriotic cell lines (ECL and 12Z). Pathway-focused multiplex qPCR was used to determine transcriptome changes due to LOX overexpression.

RESULTS

LOX protein was differentially expressed in ovarian versus peritoneal lesions. During WOI, LOX levels were higher in luminal epithelium of patients with endometriosis-associated infertility compared to controls. Invasive epithelial cell lines expressed higher levels of LOX than noninvasive ones. Transfection of LOX into noninvasive epithelial cells increased their migration in an LOX inhibitor-sensitive manner. Overexpression of LOX did not fully induce EMT but the expression of genes related to fibrosis and extracellular matrix remodeling were dysregulated.

CONCLUSIONS

This study documents that expression of LOX is differentially regulated in endometriotic lesions and endometrium. A role for LOX in mediating proliferation, migration, and invasion of endometrial and endometriotic cells was observed, which may be implicated in the establishment and progression of endometriotic lesions.

Arginine methyltransferases mediate an epigenetic ovarian response to endometriosis

Endometriosis is associated with infertility and debilitating chronic pain. Abnormal epigenetic modifications in the human endometrium have recently been implicated in the pathogenesis of this condition. However, whether an altered epigenetic landscape contributes to pathological changes in the ovary is unknown. Using an established baboon endometriosis model, early-, and late-stage epigenetic changes in the ovary were investigated. Transcript profiling of key chromatin-modifying enzymes using pathway-focused PCR arrays on ovarian tissue from healthy control animals and at 3 and 15 months of endometriosis revealed dramatic changes in gene expression in a disease duration-dependent manner. Ingenuity Pathway Analysis indicated that transcripts for chromatin-remodeling enzymes associated with reproductive system disease and cancer development were abnormally regulated, most prominently the arginine methyltransferases CARM1, PRMT2, and PRMT8. Downregulation of CARM1 protein expression was also detected in the ovary, fully-grown oocytes and eutopic endometrium following 15 months of endometriosis. Sodium bisulfite sequencing revealed DNA hypermethylation within the PRMT8 promoter, suggesting that deregulated CpG methylation may play a role in transcriptional repression of this gene. These results demonstrate that endometriosis is associated with changes of epigenetic profiles in the primate ovary and suggest that arginine methyltransferases play a prominent role in mediating the ovarian response to endometriosis. Owing to the critical role of CARM1 in nuclear receptor-mediated transcription and maintenance of pluripotency in the cleavage stage embryo, our results suggest that epigenetic alterations in the ovary may have functional consequences for oocyte quality and the etiology of infertility associated with endometriosis.

Molecular classification of endometriosis and disease stage using high-dimensional genomic data

Endometriosis (E), an estrogen-dependent, progesterone-resistant, inflammatory disorder, affects 10% of reproductive-age women. It is diagnosed and staged at surgery, resulting in an 11-year latency from symptom onset to diagnosis, underscoring the need for less invasive, less expensive approaches. Because the uterine lining (endometrium) in women with E has altered molecular profiles, we tested whether molecular classification of this tissue can distinguish and stage disease. We developed classifiers using genomic data from n = 148 archived endometrial samples from women with E or without E (normal controls or with other common uterine/pelvic pathologies) across the menstrual cycle and evaluated their performance on independent sample sets. Classifiers were trained separately on samples in specific hormonal milieu, using margin tree classification, and accuracies were scored on independent validation samples. Classification of samples from women with E or no E involved 2 binary decisions, each based on expression of specific genes. These first distinguished presence or absence of uterine/pelvic pathology and then no E from E, with the latter further classified according to severity (minimal/mild or moderate/severe). Best performing classifiers identified E with 90%-100% accuracy, were cycle phase-specific or independent, and used relatively few genes to determine disease and severity. Differential gene expression and pathway analyses revealed immune activation, altered steroid and thyroid hormone signaling/metabolism, and growth factor signaling in endometrium of women with E. Similar findings were observed with other disorders vs controls. Thus, classifier analysis of genomic data from endometrium can detect and stage pelvic E with high accuracy, dependent or independent of hormonal milieu. We propose that limited classifier candidate genes are of high value in developing diagnostics and identifying therapeutic targets. Discovery of endometrial molecular differences in the presence of E and other uterine/pelvic pathologies raises the broader biological question of their impact on the steroid hormone response and normal functions of this tissue.

Early origins of adult disease: approaches for investigating the programmable epigenome in humans, nonhuman primates, and rodents

According to the developmental origins of health and disease hypothesis, in utero experiences reprogram an individual for immediate adaptation to gestational perturbations, with the sequelae of later-in-life risk of metabolic disease. An altered gestational milieu with resultant adult metabolic disease has been observed in instances of both in utero constraint (e.g., from famine or uteroplacental insufficiency) and overt caloric abundance (e.g., from a maternal high-fat, caloric-dense diet). The commonality of the adult metabolic phenotype begs the question of how diverse in utero experiences (i.e., reprogramming events) converge on common metabolic pathways and how the memory of these events is maintained across the lifespan. We and others have investigated the molecular mechanisms underlying fetal programming and observed that epigenetic modifications to the fetal and placental epigenome accompany these reprogramming events. Based on several lines of emerging data in human and nonhuman primates, it is now felt that modified epigenetic signature--and the histone code in particular--underlies alterations in postnatal gene expression and metabolic pathways central to accurate functioning and maintenance of health. Because of the tissue lineage specificity of many of these modifications, nonhuman primates serve as an apt model system for the capacity to recapitulate human gene expression and regulation during development. This review summarizes recent epigenetic advances using rodent and primate (both human and nonhuman) models during in utero development and contributing to adult diseases later in life.

The role of lipoxin A4 in endometrial biology and endometriosis

Lipoxin A4 (LXA4), an endogenous anti-inflammatory and immunomodulatory mediator studied in many disease states, is recently appreciated as a potentially significant player in the endometrium. This eicosanoid, synthesized from arachidonic acid via the action of lipoxygenase enzymes, is likely regulated in endometrial tissue during the menstrual cycle. Recent studies revealed that LXA4 acts as an estrogen receptor agonist in endometrial epithelial cells, antagonizing some estrogen-mediated activities in a manner similar to the weak estrogen estriol, with which it shares structural similarity. LXA4 may also be an anti-inflammatory molecule in the endometrium, though its precise function in various physiological and pathological scenarios remains to be determined. The expression patterns for LXA4 and its receptor in the female reproductive tract suggest a role in pregnancy. The present review provides an oversight of its known and putative roles in the context of immuno-endocrine crosstalk. Endometriosis, a common inflammatory condition and a major cause of infertility and pain, is currently treated by surgery or anti-hormone therapies that are contraceptive and associated with undesirable side effects. LXA4 may represent a potential therapeutic and further research to elucidate its function in endometrial tissue and the peritoneal cavity will undoubtedly provide valuable insights.

Changes in eutopic endometrial gene expression during the progression of experimental endometriosis in the baboon, Papio anubis

Endometriosis is associated with aberrant gene expression in the eutopic endometrium of women with disease. To determine if the development of endometriotic lesions directly impacts eutopic endometrial gene expression, we sequentially analyzed the eutopic endometrium across the time course of disease progression in a baboon model of induced disease. Endometriosis was induced in baboons (n = 4) by intraperitoneal inoculation of autologous menstrual endometrium. Eutopic endometria were collected during the midsecretory phase (Days 9-11 postovulation) at 1, 3, 6-7, 10-12, and 15-16 mo after disease induction and compared with tissue from disease-free baboons. RNA was hybridized to Human Genome U133 Plus 2.0 Arrays, and data were extracted using Gene-Chip Operating Software. Subsequently, both Gene Set Enrichment Analysis and Ingenuity Pathways Analysis were used to find biological states that have a statistically significant enrichment concomitant with pairwise comparison of human endometriosis arrays. Within 1 mo of induction of the disease, 4331 genes were differentially expressed (P < 0.05). Hierarchical clustering revealed self-segregation into two groups-a) 1, 3, and 10-12 mo and b) 6-7 and 15-16 mo-together with controls. Clustering analysis at each stage of disease validated dysregulation of several signaling pathways, including Nodal-like receptor, EGF, ERK/MAPK, and PI3/AKT. Sequential analysis of the same animals during disease progression demonstrated an early disease insult and a transitory dominance of an estrogenic phenotype; however, as the disease progressed, a progesterone-resistant phenotype became evident. Furthermore, we demonstrate a 38.6% differential gene expression overlap with endometrial samples in the midsecretory phase from women with endometriosis, concomitant with similar dysregulation in human disease candidate genes Fos, Nodal, Suclg2, and Kras, among others. Molecular changes in the eutopic endometrium, associated with endometriosis, are directly impacted by endometriotic lesions, providing strong evidence that it is the disease rather than inherent defective endometrium that results in aberrant gene expression in the eutopic endometrium. Furthermore, this baboon model provides a powerful means whereby the early events associated with the pathology of disease and the resulting infertility may be elucidated.

Factors regulated by interferon gamma and hypoxia-inducible factor 1A contribute to responses that protect mice from Coccidioides immitis infection

Background

Coccidioidomycosis results from airborne infections caused by either Coccidioides immitis or C. posadasii. Both are pathogenic fungi that live in desert soil in the New World and can infect normal hosts, but most infections are self-limited. Disseminated infections occur in approximately 5% of cases and may prove fatal. Mouse models of the disease have identified strains that are resistant (e.g. DBA/2) or susceptible (e.g. C57BL/6) to these pathogens. However, the genetic and immunological basis for this difference has not been fully characterized.

Results

Microarray technology was used to identify genes that were differentially expressed in lung tissue between resistant DBA/2 and sensitive C57BL/6 mice after infection with C. immitis. Differentially expressed genes were mapped onto biological pathways, gene ontologies, and protein interaction networks, which revealed that innate immune responses mediated by Type II interferon (i.e., IFNG) and the signal transducer and activator of transcription 1 (STAT1) contribute to the resistant phenotype. In addition, upregulation of hypoxia inducible factor 1A (HIF1A), possibly as part of a larger inflammatory response mediated by tumor necrosis factor alpha (TNFA), may also contribute to resistance. Microarray gene expression was confirmed by real-time quantitative PCR for a subset of 12 genes, which revealed that IFNG HIF1A and TNFA, among others, were significantly differentially expressed between the two strains at day 14 post-infection.

Conclusion

These results confirm the finding that DBA/2 mice express more Type II interferon and interferon stimulated genes than genetically susceptible strains and suggest that differential expression of HIF1A may also play a role in protection.

Gene expression and DNA-methylation of bovine pretransfer endometrium depending on its receptivity after in vitro-produced embryo transfer

Embryonic implantation to establish a pregnancy is a complex process that requires appropriate communication between the embryo and the maternal endometrium. Inadequate uterine receptivity may contribute to the majority of implantation failures. To provide a comprehensive inventory of genes and functional networks that represent the maternal input of the embryo-maternal cross-talk, a longitudinal, holistic study of the endometrial transcriptome in relation to the days of estrous and to the receptivity of the endometrium was performed in bovine. At day 3 of estrous, genes related to cell communication and mitochondrial energy metabolism were differentially expressed among high- and low-receptive endometria (HR, LR); at day 7, transcripts functioning in immune and inflammatory pathways, oxidative stress, and angiogenesis had different abundances. Additionally, temporal transcriptional changes between days 3 and 7 differed considerably among HR and LR. Further, several transcription factors were predicted as relevant for receptivity because they were either differentially expressed among HR and LR animals or are known to be associated with genes we detected to have differential expression. Finally, global DNA methylation varied according to the interaction of receptivity group and day of estrous, and a divergent trend, which correlated with abundance of DNMT1 transcript, was observed in LR and HR along the estrous cycle days. The study revealed that, even in early estrous, transcripts related to cell communication and response to exogenous stimuli, vascularization, and energy supply show divergent expression and longitudinal temporal regulation in HR and LR. Key components of these molecular pathways are known to be dependent on ovarian hormones that promote uterine receptivity.

Cofilin and slingshot localization in the epithelium of uterine endometrium changes during the menstrual cycle and in endometriosis

Regulation of the actin cytoskeleton is essential for epithelial cell polarity and protein trafficking within human uterine epithelium. The actin-binding protein cofilin is involved in regulation of actin dynamics by promoting actin branching and cytoskeleton reorganization. Dual immunohistochemical staining of cofilin and G-actin (represented by DNAse I staining) revealed cofilin-G-actin colocalization in the apical side of luminal epithelial cells of human uterine endometrium during the proliferative phase of the menstrual cycle. Interestingly, during the secretory phase of the menstrual cycle, cofilin was only present on the basolateral side. To determine whether the disease endometriosis causes a different pattern of actin remodeling, we investigated an established baboon model of induced endometriosis. The cofilin pattern in the secretory phase of baboons with endometriosis was similar to the proliferative phase in normal animals; cofilin was observed in the apical parts of luminal and glandular epithelium. A phosphatase regulating the activity of cofilin, slingshot (SSH1), revealed a similar staining pattern within these tissues. These patterns were confirmed through quantitative image analysis. Quantification of messenger RNA (mRNA) detected upregulated SSH1 and suggested a progesterone resistance-related pattern of nuclear steroid hormone receptors, but no change in membrane progesterone receptors (mPR alpha or mPR beta) was observed in endometriosis. Our data indicate that the severe dyssynchrony during menstrual cycle phases in endometriosis is connected with improper cytoskeleton rearrangements. We suggest that cofilin-mediated actin reorganization in uterine epithelial cells might be important in preparation for blastocyst implantation; dysregulation of this reorganization may lead to decreased fertility in endometriosis.

Endometrial stromal cells and immune cell populations within lymph nodes in a nonhuman primate model of endometriosis

Mounting evidence suggests that immunological responses may be altered in endometriosis. The baboon (Papio anubis) is generally considered the best model of endometriosis pathogenesis. The objective of the current study was to investigate for the first time immunological changes within uterine and peritoneal draining lymph nodes in a nonhuman primate baboon model of endometriosis. Paraffin-embedded femoral lymph nodes were obtained from 22 normally cycling female baboons (induced endometriosis n = 11; control n = 11). Immunohistochemical staining was performed with antibodies for endometrial stromal cells, T cells, immature and mature dendritic cells, and B cells. Lymph nodes were evaluated using an automated cellular imaging system. Endometrial stromal cells were significantly increased in lymph nodes from animals with induced endometriosis, compared to control animals (P = .033). In animals with induced endometriosis, some lymph node immune cell populations including T cells, dendritic cells and B cells were increased, suggesting an efficient early response or peritoneal drainage.

Caries induced cytokine network in the odontoblast layer of human teeth

BACKGROUND

Immunologic responses of the tooth to caries begin with odontoblasts recognizing carious bacteria. Inflammatory propagation eventually leads to tooth pulp necrosis and danger to health. The present study aims to determine cytokine gene expression profiles generated within human teeth in response to dental caries in vivo and to build a mechanistic model of these responses and the downstream signaling network.

RESULTS

We demonstrate profound differential up-regulation of inflammatory genes in the odontoblast layer (ODL) in human teeth with caries in vivo, while the pulp remains largely unchanged. Interleukins, chemokines, and all tested receptors thereof were differentially up-regulated in ODL of carious teeth, well over one hundred-fold for 35 of 84 genes. By interrogating reconstructed protein interaction networks corresponding to the differentially up-regulated genes, we develop the hypothesis that pro-inflammatory cytokines highly expressed in ODL of carious teeth, IL-1β, IL-1α, and TNF-α, carry the converged inflammatory signal. We show that IL1β amplifies antimicrobial peptide production in odontoblasts in vitro 100-fold more than lipopolysaccharide, in a manner matching subsequent in vivo measurements.

CONCLUSIONS

Our data suggest that ODL amplifies bacterial signals dramatically by self-feedback cytokine-chemokine signal-receptor cycling, and signal convergence through IL1R1 and possibly others, to increase defensive capacity including antimicrobial peptide production to protect the tooth and contain the battle against carious bacteria within the dentin.

Immunohistochemical study of the ubiquitin-nuclear factor-kB pathway in the endometrium of the baboon (Papio anubis) with and without endometriosis

The aim of the present study was to conduct a semiquantitative immunohistochemical investigation into the levels of intermediary proteins within the nuclear factor (NF)-kappaB pathway throughout the menstrual cycle in a non-human primate, namely the baboon (Papio anubis), with and without endometriosis. Formalin-fixed eutopic (n = 2-4) and ectopic (n = 6-7) endometrial tissues from baboons at the mid-luteal phase were embedded in paraffin and examined for NF-kappaB pathway components (i.e. IkappaB kinase (IKK) alpha, IKKbeta, phosphorylated (phospho-) IkappaBalpha and phospho-NF-kappaB p65 subunit), ubiquitin, 19S proteasome and the NF-kappaB activator tumour necrosis factor (TNF)-alpha. Similarly, endometrial tissues from baboons at the late follicular, mid-luteal and menses phase (n = 2-4) were investigated to determine the levels of these proteins throughout the menstrual cycle. Cytoplasmic stromal IKKalpha and glandular 19S proteasome immunostaining was elevated in the ectopic endometrium, whereas levels of ubiquitin, phospho-p65, IKKbeta, TNF-alpha and nuclear 19S proteasome were similar in the eutopic and ectopic endometrium. A significant decrease in phospho-IkappaBalpha nuclear immunostaining was observed within glandular cells of the ectopic endometrium. In the eutopic endometrium, IKKalpha, ubiquitin and 19S proteasome immunostaining was elevated in different phases of the menstrual cycle, whereas levels of phospho-p65, IKKbeta, phospho-IkappaBalpha and TNF-alpha remained unchanged. We have demonstrated that, in the baboon endometriosis model, levels of IKKalpha immunostaining are elevated, whereas those of phospho-IkappaBalpha are reduced, consistent with the hypothesis that excessive NF-kappaB activity plays a role in reducing ectopic endometrial apoptosis, which contributes to the pathophysiology of endometriosis. Further studies are required to confirm a causal association between elevated IKKalpha levels and reduced endometrial apoptosis.

Extracellular matrix metalloproteinase inducer expression in the baboon endometrium: menstrual cycle and endometriosis

Extracellular matrix metalloproteinase inducer (EMMPRIN; BSG) regulates tissue remodeling through matrix metalloproteinases (MMPs). In human and non-human primates, endometrial remodeling is important for menstruation and the pathogenesis of endometriosis. We hypothesized that as in humans, BSG and MMPs are expressed in the endometrium of cycling baboons, and their expression is hormonally regulated by ovarian hormones, but endometriosis disrupts this regulation. BSG expression was evaluated in the baboon endometrium by q-PCR and immunohistochemistry. In the endometrium of control cycling animals, BSG mRNA levels were highest in late secretory stage tissue. BSG protein localized to glandular epithelial cells during the proliferative phase; whereas, secretory stage tissues expressed BSG in glandular and luminal epithelia with weak stromal staining. Several MMPs were differentially expressed throughout the menstrual cycle with the highest levels found during menstruation. In ovariectomized animals, BSG endometrial mRNA levels were highest with treatment of both estrogen and progesterone than that with only estrogen. Estrogen alone resulted in BSG protein localization primarily in the endometrial glandular epithelia, while estrogen and progesterone treatment displayed BSG protein localization in both the glandular and stromal cells. Exogenous hormone treatment resulted in differential expression patterns of all MMPs compared with the control cycling animals. In the eutopic endometrium of endometriotic animals, BSG mRNA levels and protein were elevated early but decreased later in disease progression. Endometriosis elevated the expression of all MMPs except MMP7 compared with the control animals. In baboons, BSG and MMP endometrial expression is regulated by both ovarian hormones, and their expression patterns are dysregulated in endometriotic animals.

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.

Human transcriptional coactivator with PDZ-binding motif (TAZ) is downregulated during decidualization

Transcriptional coactivator with PDZ-binding motif (TAZ) is known to bind to a variety of transcription factors to control cell differentiation and organ development. However, its role in uterine physiology has not yet been described. To study its regulation during the unique process of differentiation of fibroblasts into decidual cells (decidualization), we utilized the human uterine fibroblast (HuF) in vitro cell model. Immunocytochemistry data demonstrated that the majority of the TAZ protein is localized in the nucleus. Treatment of HuF cells with the embryonic stimulus cytokine interleukin 1 beta in the presence of steroid hormones (estradiol-17 beta and medroxyprogesterone acetate) for 13 days did not cause any apparent TAZ mRNA changes but resulted in a significant TAZ protein decline (approximately 62%) in total cell lysates. Analysis of cytosolic and nuclear extracts revealed that the decline of total TAZ was caused primarily by a drop of TAZ protein levels in the nucleus. TAZ was localized on the peroxisome proliferator-activated receptor response element site (located at position -1200 bp relative to the transcription start site) of the genomic region of decidualization marker insulin-like growth factor-binding protein 1 (IGFBP1) in HuF cells as detected by chromatin immunoprecipitation. TAZ is also present in human endometrium tissue as confirmed by immunohistochemistry. During the secretory phase of the menstrual cycle, specific TAZ staining particularly diminishes in the stroma, suggesting its participation during the decidualization process, as well as implantation. During early baboon pregnancy, TAZ protein expression remains minimal in the endometrium close to the implantation site. In summary, the presented evidence shows for the first time to date TAZ protein in the human uterine tract, its downregulation during in vitro decidualization, and its localization on the IGFBP1 promoter region, all of which indicate its presence in the uterine differentiation program during pregnancy.

Connexin expression pattern in the endometrium of baboons is influenced by hormonal changes and the presence of endometriotic lesions

Experimentally induced endometriosis in baboons serves as an elegant model to discriminate between endometrial genes which are primarily associated with normal endometrial function and those that are changed by the presence of endometriotic lesions. Since connexin genes are characteristic of the hormonally regulated differentiation of the endometrium, we have examined connexin expression in baboon endometrium to delineate if they are altered in response to the presence of endometriotic lesions. Connexin expression in the endometrium of cycling baboons is similar to that of the human endometrium with Connexin(Cx)43 being primarily seen in the stromal compartment and Cx26 and Cx32 being present predominantly in the epithelium. Although Cx32 is up-regulated during the secretory phase, Cx26 and Cx43 are down-regulated. In the baboon model of induced endometriosis a change in connexin pattern was evident in the presence of endometriotic lesions. In the secretory phase, Cx26 and Cx32 are no longer present in the epithelium but Cx26 is now observed primarily in the stromal cells. Infusion of chorionic gonadotrophin in a manner that mimics blastocyst transit in utero failed to rescue the aberrant stromal expression of Cx26 that is associated with the presence of endometriotic lesions suggesting an impairment of the implantation process. The altered connexin pattern coupled with a loss of the channel protein in the epithelium and a gain of Cx26 in the stromal compartment suggests that the presence of lesions changes the uterine environment and thereby the differentiation programme. This aberrant expression of connexins may be an additional factor that contributes to endometriosis-associated infertility.

The non-human primate model of endometriosis: research and implications for fecundity

The development of an animal model of endometriosis is crucial for the investigation of disease pathogenesis and therapeutic intervention. These models will enhance our ability to evaluate the causes for the subfertility associated with disease and provide a first-line validation of treatment modulators. Currently rodents and non-human primate models have been developed, but each model has their limitations. The aim of this manuscript is to summarize the current findings and theories on the development of endometriosis and disease progression and the effectiveness of therapeutic targets using the experimental induced model of endometriosis in the baboon (Papio anubis).

Nonhuman primate models for translational research in endometriosis

Endometriosis, defined as the ectopic presence of endometrial-like cells, is associated with infertility and pelvic pain in women. Whereas pathogenesis and spontaneous evolution of endometriosis are still poorly understood, recurrences after surgical therapy or after medical treatment are common. Spontaneous endometriosis occurs only in women and in nonhuman primates (NHPs). Inbred rhesus monkeys kept in colonies offer an attractive preclinical model to study the inheritance of spontaneous endometriosis. Baboons with spontaneous or induced endometriosis appear to be the best NHP model to study pathogenesis, pathophysiology, spontaneous evolution and new medical treatment options. In baboons, induction of endometriosis after intrapelvic injection of menstrual endometrium leads to biological changes in peritoneal cavity and in endometrium. This induction process may allows the study of cause-effect relationships which may lead to the discovery of new biomarkers for the development of new non-invasive diagnostic tests and drugs that may prevent or treat endometriosis.

Eutopic endometrium from women with endometriosis shows altered ultrastructure and glycosylation compared to that from healthy controls--a pilot observational study

Endometrial curettings from a cohort of 24 women with endometriosis were compared with matched biopsies from 14 healthy, fertile women and examined for ultrastructural changes and the secretion of glycans bound by the lectin from Dolichos biflorus. Ultrastructural analysis of glandular endometrial tissue from women with stages I to III endometriosis showed heterogeneous responses to the disease, biopsies often showing a mixture of features, combining delays in the maturation sequence with characteristics of later phenotypes particularly in the mid-late secretory phase of the menstrual cycle. Expression of glycans bound by Dolichos biflorus agglutinin was very variable in these cases but generally matched the observed ultrastructure. Biopsies from women with stage IV endometriosis showed immature gland morphology later in the cycle and also failed to express Dolichos biflorus agglutinin-binding glycans, suggesting an association between histological and biochemical function in advanced disease states. These findings may explain in part endometriosis-associated subfertility as blastocyst attachment is intimately associated with appropriate glycosylation and gland morphology.

Increased expression of c-fos protein associated with increased matrix metalloproteinase-9 protein expression in the endometrium of endometriotic patients

OBJECTIVE

To investigate c-fos and matrix metalloproteinase-9 (MMP-9) expression in the endometrium from women with or without endometriosis throughout the menstrual cycle, and to explore the correlation of c-fos expression with MMP-9 expression and 17beta-E(2) levels in serum.

DESIGN

Molecular studies in human tissue.

SETTING

A women's hospital in China.

PATIENT(S)

Fifty-five premenopausal women (25 with endometriosis and 30 without endometriosis) undergoing laparoscopic surgery or hysterectomy.

INTERVENTION(S)

Eutopic and ectopic endometrium tissue were obtained at the time of surgery. Peripheral sera were also collected on the same day.

MAIN OUTCOME MEASURE(S)

Immunohistochemical localization of c-fos in the endometrium, c-fos and MMP-9 protein levels in the endometrium, and 17beta-E(2) levels in the serum.

RESULT(S)

c-fos protein was predominantly located in the nuclei of glandular epithelial cells and stromal cells. c-fos and MMP-9 protein levels in paired eutopic and ectopic endometria from women with endometriosis were significantly higher than those in the endometrium from women without endometriosis. No significant difference in c-fos or MMP-9 protein levels was observed between paired eutopic and ectopic endometria. c-fos protein levels in endometrium positively correlated with endometrial MMP-9 levels and serum 17beta-E(2) levels.

CONCLUSION(S)

Expression of c-fos in the human endometrium may be regulated by 17beta-E(2), and c-fos may be involved in development of endometriosis by promoting MMP-9 gene expression and subsequently the invasive potential of endometrial explants.

TLR3 and TLR4 expression in healthy and diseased human endometrium

BACKGROUND

Toll-like receptors (TLRs) play an essential role in the innate immune system by initiating and directing immune response to pathogens. TLRs are expressed in the human endometrium and their regulation might be crucial for the pathogenesis of endometrial diseases.

METHODS

TLR3 and TLR4 expression was investigated during the menstrual cycle and in postmenopausal endometrium considering peritoneal endometriosis, hyperplasia, and endometrial adenocarcinoma specimens (grade 1 to 3). The expression studies applied quantitative RT-PCR and immunolabelling of both proteins.

RESULTS

TLR3 and TLR4 proteins were mostly localised to the glandular and luminal epithelium. In addition, TLR4 was present on endometrial dendritic cells, monocytes and macrophages. TLR3 and TLR4 mRNA levels did not show significant changes during the menstrual cycle. In patients with peritoneal endometriosis, TLR3 and TLR4 mRNA expression decreased significantly in proliferative diseased endometrium compared to controls. Interestingly, ectopic endometriotic lesions showed a significant increase of TLR3 und TLR4 mRNA expression compared to corresponding eutopic tissues, indicating a local gain of TLR expression. Endometrial hyperplasia and adenocarcinoma revealed significantly reduced receptor levels when compared with postmenopausal controls. The lowest TLR expression levels were determined in poor differentiated carcinoma (grade 3).

CONCLUSION

Our data suggest an involvement of TLR3 and TLR4 in endometrial diseases as demonstrated by altered expression levels in endometriosis and endometrial cancer.

Gene expression profiles and functional characterization of human immortalized endometriotic epithelial and stromal cells

OBJECTIVE

To determine whether immortalized endometriotic cells can be used as potential models to unravel pathophysiology/pathogenesis of endometriosis in humans.

DESIGN

In vitro study. Human immortalized endometriotic epithelial and stromal cells.

SETTING

College of Veterinary Medicine and Biomedical Sciences, Texas A&M University.

PATIENT(S)

Not applicable.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Gene expression pattern and prostaglandin E(2) production and activity of matrix metalloproteinase 2 and matrix metalloproteinase 9.

RESULT(S)

Several genes associated with estrogen and progesterone biosynthesis and signaling, cell cycle regulation, extracellular matrix degradation, angiogenesis, cell growth and survival, cytokine production, and prostaglandin E(2) biosynthesis, transport, and signaling were expressed in human immortalized endometriotic cells. These endometriotic epithelial and stromal cells exhibited migrating and invading potential, produced a high quantity of prostaglandin E(2), and showed higher matrix metalloproteinase 2 and matrix metalloproteinase 9 activity compared to normal endometrial, epithelial, and stromal cells.

CONCLUSION(S)

Human immortalized endometriotic epithelial and stromal cells could be used as ideal models to study the molecular and cellular aspects of endometriosis in humans.

Prolonged stimulation with tumor necrosis factor-alpha induced partial methylation at PR-B promoter in immortalized epithelial-like endometriotic cells

The promoter of P receptor isoform B (PR-B) has recently been shown to be hypermethylated in endometriotic tissues, but one question remains as what causes the aberrant methylation. We show that sustained stimulation of an epithelial-like endometriotic cell line with tumor necrosis factor alpha stimulation for 30 days induced partial methylation in the promoter region of PR-B with concomitant reduction of PR-B expression.

Wild Fulvous Fruit Bats (Rousettus leschenaulti) Exhibit Human-Like Menstrual Cycle1

We investigated the menstrual cycle of wild fulvous fruit bats (Rousettus leschenaulti), focusing on changes in the endometrial and ovarian structure and pituitary and steroid hormones. The menstrual cycle lasts for 33 days in bats studied in their natural habitat and in captivity. Vaginal bleeding was restricted to a single day (Day 1). A preovulatory follicle was found in the ovary on Day 18 when the levels of LH and FSH reached their maxima, accompanied by a thickened endometrium. On Day 24, serum levels of progesterone and estradiol-17 were also maximal, and uterine glands increased in size. After that, the levels of progesterone dropped precipitously, leading to menstrual bleeding. Both the morphologic and hormonal changes observed in fulvous fruit bats during the menstrual cycle resemble similar changes in humans. Fulvous fruit bats may be useful nonprimate laboratory models to study menstruation and menstrual dysfunction.

A system-wide analysis of differentially expressed genes in ectopic and eutopic endometrium

BACKGROUND

Decades of research suggest that endometriosis is a complex disorder, with varying severity, onset and progression. Many genes have been associated with endometriosis through a number of studies and now microarray analyses have added to the list of perturbed or differentially regulated genes. Thus, it is difficult to see 'the big picture' without first integrating these multiple, heterogeneous sources of high-quality information for analysis.

METHODS

The goal of this study was to infer correlative and/or causal trends by combining empirical microarray analysis with a historical knowledge base of genetic relationships in endometriosis via a program called IRIDESCENT.

RESULTS

Importantly, we found a number of genes, which may have a central role in endometriosis, despite the fact that few or no past studies have reported these associations.

CONCLUSIONS

Several genes listed as non-responders on the microarray were found to be regulated post-transcriptionally, illustrating the importance of integrating multiple data sources.

Tyrosine receptor kinase B (TrkB) protein expression in the human endometrium

Tyrosine kinase receptor B (TrkB) gene expression, a neurotrophic factor receptor expressed in the brain and ovary, has recently been identified in deep infiltrating endometriosis by gene array. TrkB is thought to be important in resistance to anchorage independent apoptosis (ANOIKIS) and thus could be important in the pathogenesis of endometriosis. However, TrkB protein expression in the eutopic endometrium of women with and without endometriosis is unknown. Therefore, we examined TrKB protein expression in the endometrium by Western blot (n = 50) and immunohistochemistry (n = 17). Immunoblots of endometrial biopsies were prepared from women with endometriosis (n = 21) vs. healthy controls (n = 29) undergoing benign gynecological surgery at McMaster University Medical Centre. TrkB protein expression was significantly higher in immunoblots from women with endometriosis compared to women without endometriosis. In samples of archived paraffin-embedded endometrial tissue TrkB was localized to the cytoplasm of epithelial cells of the eutopic endometrium from women with endometriosis (n = 7) and without endometriosis (n = 10). We conclude that TrkB protein is expressed in human endometrium. Our results also suggest that TrkB expression may be greater in women with endometriosis compared to women without endometriosis.

Altered expression of HOXA10 in endometriosis: potential role in decidualization

Endometriosis is a poorly understood gynaecologic disorder that is associated with infertility. In this study, we examined the expression of HOXA10 in the eutopic endometrium of baboons with induced endometriosis. A decrease in HOXA10 mRNA was observed after 3, 6, 12 and 16 months of disease, which reached statistical significance at 12 and 16 months. HOXA10 protein levels were decreased in both the epithelial and stromal cells of the endometrium. Furthermore, expression of beta3 integrin (ITGB3), which is upregulated by HOXA10, was decreased, whereas EMX2, a gene that is inhibited by HOXA10, was increased. Next, methylation patterns of the HOXA10 gene were analysed in the diseased and control animals. The F1 region on the promoter was found to be the most significantly methylated in the endometriosis animals and this may account for the decrease in HOXA10 expression. Finally, we demonstrate that stromal cells from the eutopic endometrium of baboons with endometriosis expressed significantly higher levels of insulin-like growth factor binding protein-1 (IGFBP1) mRNA than disease-free animals in response to estradiol, medroxyprogesterone acetate and dibutyryl cAMP (H + dbcAMP). The functional role of HOXA10 in IGFBP1 expression was further explored using human endometrial stromal cells (HSC). Overexpression of HOXA10 in HSC resulted in a decrease of IGFBP1 mRNA, whereas silencing HOXA10 caused an increase of IGFBP1 mRNA, even in the presence of H + dbcAMP. These data demonstrate that HOXA10 negatively influences IGFBP1 expression in decidualizing cells. Thus, the decrease in HOXA10 levels may in part be involved with the altered uterine environment associated with endometriosis.

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.

Morphological and glycosylation changes associated with the endometrium and ectopic lesions in a baboon model of endometriosis

BACKGROUND

Endometriosis is one of the most common causes of infertility and pelvic pain. A baboon model has recently been developed whereby the intrapelvic injection of menstrual endometrium results in the induction of endometriotic lesions. We have used this model to investigate changes in ultrastructure and glycosylation of endometria from normal and diseased baboons.

METHODS

Endometriosis was induced in eight female baboons; endometrial tissue and endometriotic lesions were removed on days 9-11 post ovulation between 3 and 16 months of disease and compared with endometrium from 17 control animals, using electron microscopy and lectin histochemistry.

RESULTS

Ultrastructurally, diseased endometrial glands showed abnormalities in secretory vacuoles and an intracellular accumulation of glycogen; in later stages of the disease, glands resembled those of the late secretory phase endometrium. The abnormalities were mirrored by changes in glycan expression. In early disease, there was an increased binding of lectin from Dolichos biflorus agglutinin (DBA) to fucosylated N-acetylglucosamine residues, whereas in later stages, this binding generally decreased in association with the appearance of a late secretory phenotype.

CONCLUSIONS

Endometriosis is accompanied by progressive changes in the gland architecture and biochemistry resulting in dyssynchrony within the window of uterine receptivity, which may result in the reduced fertility associated with this disease.

A baboon model for endometriosis: implications for fertility

Endometriosis is one of the most common causes of chronic pelvic pain and infertility in women in the reproductive age group. Although the existence of this disease has been known for over 100 years our current knowledge of its pathogenesis and the pathophysiology of its related infertility remains unclear. Several reasons contribute to our lack of knowledge, the most critical being the difficulty in carrying out objective long-term studies in women. Thus, we and others have developed a model of this disease in the non-human primate, the baboon (Papio anubis). Intraperitoneal inoculation of autologous menstrual endometrium results in the development of endometriotic lesions with gross morphological characteristics similar to those seen in the human. Multiple factors have been implicated in endometriosis-associated infertility. We have described aberrant levels of factors involved in multiple pathways important in the establishment of pregnancy, in the endometrium of baboons induced with endometriosis. Specifically, we have observed dysregulation of proteins involved in invasion, angiogenesis, methylation, cell growth, immunomodulation, and steroid hormone action. These data suggest that, in an induced model of endometriosis in the baboon, an increased angiogenic capacity, decreased apoptotic potential, progesterone resistance, estrogen hyper-responsiveness, and an inability to respond appropriately to embryonic signals contribute to the reduced fecundity associated with this disease.