Immunology of endometriosis

Immune Checkpoints in Endometriosis-A New Insight in the Pathogenesis

Endometriosis (EMS) is an oestrogen-dependent, chronic disease affecting women of a reproductive age. One of the important factors involved in the development of this disease is the complex disorders associated with the functioning of the immune system. Recent evidence has shown that EMS development is associated with changes in systemic and local immunity, including functional disturbances of effector and antigen-presenting cells. One of the reasons for immune imbalance can be the improper expression of immune checkpoints (ICPs). ICPs and their ligands are responsible for maintaining self-tolerance and the modulation of the initiation, duration, and magnitude of the immune response of effector cells in normal tissues to avoid tissue damage. Considering the complex nature of co-stimulatory or co-inhibitory ICPs and the signalling between effector cells and APCs, we hypothesise that changes in cells' activity caused by ICPs may lead to serious immune system disturbances in patients with endometriosis. Moreover, both upregulation and downregulation in the expression of ICPs may be implicated in this process, including the reduced activity of effector cells against endometrial implants and disturbances in the antigen-presenting process. In this narrative review, we discuss, for the first time, key findings from the emerging literature, describing the associations between ICPs and their possible implication in the pathogenesis of endometriosis.

Immune pathway through endometriosis to ovarian cancer

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

Causal effects of endometriosis on SLE, RA and SS risk: evidence from meta-analysis and Mendelian randomization

BACKGROUND

Endometriosis is an underdiagnosed disorder that affects an estimated 6-10% of women of reproductive age. Endometriosis has been reported in epidemiological studies to be associated with autoimmune diseases. However, the relationship remains controversial.

METHODS

A meta-analysis of observational studies was undertaken to evaluate the risk of autoimmune diseases in patients with endometriosis. The relevant studies were retrieved via the databases Medline, Embase and Web of Science until July 20, 2023. Mendelian randomization (MR) was subsequently utilized to scrutinize the causal influence of genetic predisposition toward endometriosis on three autoimmune diseases.

RESULTS

The meta-analysis findings revealed a relationship between endometriosis and the onset of SLE (cohort studies: RR = 1.77, 95% confidence interval (CI): 1.47-2.13, I2 = 0%; Case-control and cross-sectional studies: OR = 5.23, 95% CI: 0.74-36.98, I2 = 98%), RA (cohort studies: RR = 2.18, 95% CI: 1.85-2.55, I2 = 92%; Case-control and cross-sectional studies: OR = 1.40, 95% CI: 1.19-1.64, I2 = 0%) and SS (cohort studies: RR = 1.49, 95% CI: 1.34-1.66, I2 = 0%). Similarly, in our MR study, the results of the inverse-variance-weighted (IVW) model suggested that genetic predisposition to endometriosis was causally associated with an increased risk for SLE (OR = 1.915, 95% CI: 1.204-3.045, p = 0.006) and RA (OR = 1.005, 95% CI: 1.001-1.009, p = 0.014).

CONCLUSIONS

Both our meta-analysis and MR study indicate that endometriosis increases the risk of autoimmune diseases. These findings not only broaden our understanding of the genetic mechanisms underlying the comorbidity of endometriosis and autoimmune diseases, but also offer a new strategy for autoimmune disease prevention.

The Extracellular Vesicle-Macrophage Regulatory Axis: A Novel Pathogenesis for Endometriosis

Endometriosis (EMs) is a common disease among women whose pathogenesis is still unclear, although there are various hypotheses. Recent studies have considered macrophages the key part of the immune system in developing EMs, inducing inflammation, the growth and invasion of the ectopic endometrium, and angiogenesis. Extracellular vesicles (EVs) as novel intercellular vesicle traffic, can be secreted by many kinds of cells, including macrophages. By carrying long non-coding RNA (lncRNA), microRNA (miRNA), or other molecules, EVs can regulate the biological functions of macrophages in an autocrine and paracrine manner, including ectopic lesion growth, immune dysfunction, angiogenesis, and can further accelerate the progression of EMs. In this review, the interactions between macrophages and EVs for the pathogenesis of EMs are summarized. Notably, the regulatory pathways and molecular mechanisms of EVs secreted by macrophages during EMs are reviewed.

The landscape of non-coding RNAs in the immunopathogenesis of Endometriosis

Endometriosis is a complex disorder that is characterized by the abnormal growth of endometrial-like tissue outside the uterus. It is associated with chronic inflammation, severe pelvic pain, infertility, and significantly reduced quality of life. Although the exact mechanism of endometriosis remains unknown, inflammation and altered immunity are considered key factors in the immunopathogenesis of the disorder. Disturbances of immune responses result in reduced clearance of regurgitated endometrial cells, which elicits oxidative stress and progression of inflammation. Proinflammatory mediators could affect immune cells' recruitment, fate, and function. Reciprocally, the activation of immune cells can promote inflammation. Aberrant expression of non-coding RNA (ncRNA) in patient and animal lesions could be suggestive of their role in endometriosis establishment. The engagement of these RNAs in regulating diverse biological processes, including inflammatory responses and activation of inflammasomes, altered immunity, cell proliferation, migration, invasion, and angiogenesis are widespread and far-reaching. Therefore, ncRNAs can be identified as a determining candidate regulating the inflammatory responses and immune system. This review aims in addition to predict the role of ncRNAs in the immunopathogenesis of endometriosis through regulating inflammation and altered immunity based on previous studies, it presents a comprehensive view of inflammation role in the pathogenesis of endometriosis.

Regulation of progesterone receptor expression in endometriosis, endometrial cancer, and breast cancer by estrogen, polymorphisms, transcription factors, epigenetic alterations, and ubiquitin-proteasome system

The uterus and breasts are hormone-responsive tissues. Progesterone and estradiol regulate gonadotropin secretion, prepare the endometrium for implantation, maintain pregnancy, and regulate the differentiation of breast tissue. Dysregulation of these hormones causes endometriosis, endometrial cancer, and breast cancer, damaging the physical and mental health of women. Emerging evidence has shown that progesterone resistance or elevated progesterone activity is the primary hormonal substrate of these diseases. Since progesterone acts through its specific nuclear receptor, the abnormal expression of the progesterone receptor (PR) dysregulates progesterone function. This review discusses the regulatory mechanisms of PR expression in patients with endometriosis, and endometrial or breast cancer, including estrogen, polymorphisms, transcription factors, epigenetics, and the ubiquitin-proteasome system. (1) Estrogen promotes the expression of PRA (a PR isoform) mRNA and protein through the interaction of estrogen receptors (ERs) and Sp1 with half-ERE/Sp1 binding sites. ERs also affect the binding of Sp1 and Sp1 sites to promote the expression of PRB (another PR isoform)(2) PR polymorphisms, mainly PROGINS and + 331 G/A polymorphism, regulate PR expression by affecting DNA methylation and transcription factor binding. (3) The influence of epigenetic alterations on PR expression occurs through DNA methylation, histone modification, and microRNA. (4) As one of the main protein degradation pathways in vivo, the ubiquitin-proteasome system (UPS) regulates PR expression by participating in protein degradation. These mechanisms may provide new molecular targets for diagnosing and treating endometriosis, endometrial, and breast cancer.

Huayu Sanjie Enema Liquid Relieves Pain in Endometriosis Model Rats by Inhibiting Inflammation, Peripheral Sensitization, and Pelvic Adhesion

The objective of this study is to observe the effect of relieving pain of Huayu Sanjie enema liquid (HYSJ-EL) on endometriosis model rats and to explore its mechanism of action. Of 24 female Sprague Dawley rats, six were randomly selected as the sham operation group (normal control group). The remaining rats were used to establish rat models of endometriosis through autologous endometrial transplantation combined with estrogen injection. Successfully modeled rats were randomly divided into the model, indomethacin (Western medicine group), and HYSJ-EL (Chinese herbs group) treatment groups. The thermal pain threshold of rats was measured, and hematoxylin and eosin staining was used to observe pathological changes after sampling. Serum levels of prostaglandin E2 (PGE2), interleukin-6 (IL-6), macrophage inflammatory protein-2 (MIP-2), plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor-β (TGF-β) were measured using an enzyme-linked immunosorbent assay (ELISA). Furthermore, the protein and mRNA expression levels of transient receptor potential vanilloid-1 (TRPV1) and tumor necrosis factor-α (TNF-α) in the endometrium and endometriotic lesions were measured using Western blotting and quantitative real-time PCR assays, respectively. Compared to the model group, the heat pain threshold of rats in the HYSJ-EL group was significantly increased (P < 0.01), and the serum levels of PGE2, IL-6, MIP-2, PAI-1, and TGF-β were significantly decreased (P < 0.01), as well as the expression of TRPV1 and TNF-α protein and mRNA in the tissue of the ectopic lesion was significantly decreased (P < 0.05). These results indicate that the Huayu Sanjie enema liquid exerts analgesic effects on endometriosis by inhibiting inflammation, peripheral nerve sensitization, and pelvic adhesion.

The role of the Immune System in the Development of Endometriosis

Endometriosis is a chronic disease that affects about 10% of women of reproductive age. It can contribute to pelvic pain, infertility or other conditions such as asthma, cardiovascular disease, breast or ovarian cancer. Research has shown that one of the conditions for the development of endometrial lesions is the dysfunction of the immune system. It appears that immune cells, such as neutrophils, macrophages, NK cells and dendritic cells, may play a specific role in the angiogenesis, growth and invasion of endometriosis cells. Immune cells secrete cytokines and defensins that also affect the endometriosis environment. This review discusses the various components of the immune system that are involved in the formation of endometrial lesions in women.

Immunopathogenesis of endometriosis: An overview of the role of innate and adaptive immune cells and their mediators

BACKGROUND

Endometriosis is a chronic inflammatory disease associated with the growth and proliferation of endometrial-like tissues outside the uterus. Although the exact etiology and mechanism of the pathogenesis of the disease have not been fully elucidated, the immune system cells and the mediators produced by them can be named as effective factors in the onset and progression of the disease.

AIMS

We aim to attempt to review studies on the role of the immune system in endometriosis to better understand the pathogenesis of endometriosis.

CONTENT

Abundant production of inflammatory mediators by neutrophils and macrophages and reduced cytotoxicity of defined cells promote endometriosis at the early stages of the disease. Following an increase in the inflammation of the environment, the body takes compensatory mechanisms to reduce inflammation and establish homeostasis. For this purpose, the body produces remodeling and anti-inflammatory factors leading to slow conversion of the inflammatory environment into a non-inflammatory environment with proliferative and immunosuppressive properties. Environmental conditions induce M2 macrophages, TH2 cells, and Tregs differentiation, promoting disease progression by producing angiogenic and immunosuppressive factors. However, the exact molecular mechanism involved in changing inflammatory to non-inflammatory conditions is not yet fully understood.

IMPLICATIONS

Due to the common characteristics of endometriotic cells and cancer cells, most potential treatment options for endometriosis have been suggested due to the results of these methods in the treatment of cancer. In this pathway, immune system cells and soluble mediators can be used as targets.

The extracellular vesicular pseudogene LGMNP1 induces M2-like macrophage polarization by upregulating LGMN and serves as a novel promising predictive biomarker for ovarian endometriosis recurrence

STUDY QUESTION

How does ectopic endometrial stromal cell (Ecto-ESC)-derived extracellular vesicular Legumain pseudogene 1 (EV-LGMNP1), a newly identified pseudogene of Legumain (LGMN), contribute to M2-phenotype macrophage polarization, and does it predict recurrence in patients with ovarian endometriosis (EMs)?

SUMMARY ANSWER

EV-LGMNP1, which is abundant in Ecto-ESCs and serum from ovarian EMs, can direct macrophages towards an M2 phenotype by upregulating LGMN expression and is a promising biomarker for predicting ovarian EMs recurrence.

WHAT IS KNOWN ALREADY

Extracellular vesicles (EVs) can mediate cell-to-cell crosstalk to promote disease progression via cargo molecule transport. Recently, LGMNP1, a newly identified pseudogene of LGMN, has been reported to promote cancer progression by upregulating LGMN. LGMN is a well-studied protein that can induce M2-like polarization.

STUDY DESIGN, SIZE, DURATION

An in vitro study was conducted with Ecto-ESCs isolated from ectopic endometrial samples, collected from two patients with ovarian EMs (diagnosed by laparoscopy and histological analysis). A clinical retrospective cohort study of 52 ovarian EMs patients and 21 controls with available preoperative serum samples was carried out (2013-2017). The follow-up period ended either at the time of recurrence or on 31 December 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ecto-ESC-derived EVs (EV/Ecto-ESCs) were characterized by nanoparticle tracking analysis, transmission electron microscopy and western blotting. EV internalization by THP-1 cells, which are the most widely used primary human macrophages model, was detected by fluorescence labelling. After EV treatment, THP-1 cell polarization was detected by quantitative real-time PCR (qRT-PCR) and western blot analyses of CD86 (M1-related marker) and CD206 (M2-related marker). LGMNP1 mRNA expression level in EVs from both primary ectopic endometrioc stromal cells and serum was examined using qRT-PCR. Additionally, the expression of LGMN, the downstream target gene of LGMNP1, in THP-1 cells was evaluated using qRT-PCR and western blotting. Kaplan-Meier and multivariate Cox regression analyses were applied to evaluate the independent predictive factors of EMs recurrence-free survival. A novel nomogram model based on serum EV-LGMNP1 was then formulated to predict EMs recurrence.

MAIN RESULTS AND THE ROLE OF CHANCE

In vitro assays demonstrated that EV/Ecto-ESCs drove macrophages towards an M2-like phenotype. Moreover, LGMNP1 contributed to EV/Ecto-ESC-induced M2 macrophage polarization by upregulating LGMN mRNA expression levels. Clinically, serum EV-LGMNP1 was more highly expressed in recurrent EMs patients than in controls and EMs patients without recurrence. Survival analysis and our novel nomogram reconfirmed that serum EV-LGMNP1 was a novel promising and meaningful non-invasive biomarker for predicting EMs recurrence.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

In vitro experiments were only performed on samples from two patients with ovarian endometriosis, and a larger sample size is needed. ESCs isolated from the eutopic endometrium of EMs and non-EMs patients should be studied in the future. Additionally, in vitro experiments should be performed using endometrial epithelium cells and further in vivo experiments, such as using mice endometriotic models to investigate whether EV/Ecto could induce M2 macrophage polarization, should be conducted. Moreover, multicentre, large-sample data are needed to validate our predictive nomogram model.

WIDER IMPLICATIONS OF THE FINDINGS

Our study provides novel insights into the mechanism of M2 polarization involved in ovarian EMs progression mediated by an 'EV-shuttled pseudogene LGMNP1' mode. In addition, serum EV-LGMNP1 may serve as a novel non-invasive biomarker for predicting recurrence, providing a new therapeutic target for ovarian EMs.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by funding from the National Natural Science Foundation of China (81971361), the Natural Science Foundation of Shanghai Science and Technology (19ZR1406900), the Shanghai 'Rising Stars of Medical Talent' Youth Development Program (AB83030002019004), the Clinical Research Plan of SHDC (SHDC2020CR4087), the Shanghai Municipal Health Commission (202040498), the Research and Innovation Project of the Shanghai Municipal Education Commission (2019-01-07-00-07-E00050) and the Clinical Research Plan of SHDC (SHDC2020CR1045B). There are no competing interests to declare.

The role of dendritic cells in endometriosis: A systematic review

Endometriosis (EDT), a common estrogen-dependent inflammatory disorder, is characterized by endometrial-like tissue outside the uterus. While its pathogenesis is poorly understood, it is supposed that the immune system plays a role in its pathophysiology, and increased number of immune cells and changes in both cell-mediated and humoral immunity have been described. Dendritic cells (DCs) are antigen-presenting cells (APC) of the immune system that recognize, capture, and process complex antigens and present them to T cells, conferring them a unique ability as mediators between the innate and adaptive immune systems. This systematic review aims to enlighten possible disturbances (systemically and locally) of DCs in the development and progression of endometriosis. A search using the strategy: ("dendritic cells" AND "immunology" AND "endometriosis") in databases resulted in 490 citations; after applying inclusion and exclusion criteria, a total of 13 studies were assessed. The evaluated studies demonstrated that DCs are susceptible to pro-endometriotic changes which could inhibit immature DCs (imDCs) from their maturation and induce imDCs into a macrophage phenotype. In addition, the growth and vascularization of endometriosis requires the presence of endogenous DC, which infiltrate endometriotic lesions and enhance endothelial cell migration by secreting proangiogenic factors. Whereas DC maturation suppresses this response, imDC actively promote angiogenesis and growth, leading to a switch in their immunologic role from presenting antigens to support angiogenesis and EDT progression.

Multi-omics analysis reveals the interaction between the complement system and the coagulation cascade in the development of endometriosis

Endometriosis (EMS) is a disease that shows immune dysfunction and chronic inflammation characteristics, suggesting a role of complement system in its pathophysiology. To find out the hub genes and pathways involved in the pathogenesis of EMs, three raw microarray datasets were recruited from the Gene Expression Omnibus database (GEO). Then, a series of bioinformatics technologies including gene ontology (GO), Hallmark pathway enrichment, protein-protein interaction (PPI) network and gene co-expression correlation analysis were performed to identify hub genes. The hub genes were further verified by the Real-time quantitative polymerase chain reaction (RT-PCR) and Western Blot (WB). We identified 129 differentially expressed genes (DEGs) in EMs, of which 78 were up-regulated and 51 were down-regulated. Through GO functional enrichment analysis, we found that the DEGs are mainly enriched in cell adhesion, extracellular matrix remodeling, chemokine regulation, angiogenesis regulation, epithelial cell proliferation, et al. In Hallmark pathway enrichment analysis, coagulation pathway showed great significance and the terms in which included the central complement factors. Moreover, the genes were dominating in PPI network. Combined co-expression analysis with experimental verification, we found that the up-regulated expression of complement (C1S, C1QA, C1R, and C3) was positively related to tissue factor (TF) in EMs. In this study, we discovered the over expression complement and the positive correlation between complement and TF in EMs, which suggested that interaction of complement and coagulation system may play a role within the pathophysiology of EMS.

Diagnostic Significance of Selected Serum Inflammatory Markers in Women with Advanced Endometriosis

Endometriosis is a gynecological disease, the pathogenesis of which seems to be directly associated with inflammatory processes. Serum concentrations of IL-1β, IL-6, hs-CRP, IgG, YKL 40 and PRL, in comparison to the well-known CA 125 levels, were studied with the aim of identifying an additional noninvasive inflammatory marker or set of markers characteristic for endometriosis. The study group included 43 women with endometriosis (E), 35 women with benign gynecological disorders but without endometriosis (NE, non-endometriosis) as a comparative group, and a control group consisting of 18 healthy subjects (C). The serum concentrations of IL-1β, IL-6, hs-CRP, YKL-40, PRL and CA 125 were significantly higher in the E group (median values: 0.41 pg/mL, 2.42 pg/mL, 2.33 mg/L, 79.30 ng/mL, 21.88 ng/mL and 68.00 U/mL, respectively) than in the control group (median values: 0.21 pg/mL, 0.98 pg/mL, 0.52 mg/L, 49.77 ng/mL, 12.08 ng/mL and 12.20 U/mL respectively), with the significance of p = 0.011, p < 0.001, p = 0.028, p = 0.005, p < 0.001 and p < 0.001, respectively. The IgG concentrations were significantly lower in the endometriosis group (median value: 1061.21 mg/dL) as compared to healthy women (median value: 1210.50 mg/dL; p = 0.025). Significant differences in concentrations of IL-6 (p = 0.040), hs-CRP (p = 0.007) and CA 125 (p < 0.001) were observed in stage III vs. stage IV of endometriosis. Significantly higher concentrations of IL-6 (p = 0.010), hs-CRP (p = 0.037) and PRL (p < 0.001) were observed in the NE group vs. the control group. Only CA 125 concentrations were significantly higher in endometriosis patients as compared to the non-endometriosis group (p < 0.001). The proposed panel of inflammatory markers, especially IL-6, PRL and CA 125, may become a useful tool to identify women with advanced endometriosis who could qualify for treatment.

Expression of monocyte chemotactic protein 2 and tumor necrosis factor alpha in human normal endometrium and endometriotic tissues

Endometriosis is a gynocological disease characterized by the presence of the endometrial glands and stroma outside the uterine cavity. This disease affects % 6-10 of women with reproductive age and it causes serious problems such as pelvic pain, dysmenorrhea and infertility. Although endometriosis is one of the most investigated disease of gynecology, its pathogenesis is not clear completely. In recent years, many studies revealed the inflammatory nature of endometriosis. Many of the immune cells and their secretory products cytokines and chemokines has been detected in body fluids of women with endometriosis. Cytokines are protein or glycoprotein in structures and hormon-like molecules that act generally in a paracrine fashion to regulate immun responses. They involved in chemotaxis, cell proliferation, cell activation, motility, adhesion and morphogenesis. Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine secreted by the macrophages, monocytes, neutrophiles, T cells and natural killer cells. It stimulates increase in the level of the chemokines in body fluids. Monocyte chemotactic protein 2 (MCP-2) is a chemokine act to recruit and activate monocytes into sites of inflammation area. The aim of this study to investigate the ultrastructural properties and whether the expression and localization of TNF-α and MCP-2 in the eutopic endometrium (normal endometrium of women with endometriosis) and endometritic tissues of women with endometriosis. Eutopic endometrial and endometriotic tissue samples were obtained from women with endometriosis between 20-41 y and normal endometrial tissues were collected from 5 women without endometriosis as a control group. Tissues were processed for light and electron microscopy and examined. The epithelial cells of endometriotic tissues were revealed strongly cytoplasmic TNF-α and MCP-2 immunreactivities. Eutopic endometrial tissues were also stained prominently for both TNF-α and MCP-2. Furthermore, a significant increase in stromal macrophages were observed in endometriotic tissues. Moreover, the ultrastructural observations on the normal and endometriotic tissues were exhibited microvilli-rich cells and ciliated cells. These findings suggest that TNF-α and MCP-2 may be involved in normal endometrial biology and in the pathogenesis of endometriosis.

Extracellular Vesicles: Recent Developments in Aging and Reproductive Diseases

Extracellular vesicles (EVs), present in cell culture media and several body fluids, play a prominent role in intercellular communication under physiological and pathological conditions. We performed a systematic literature search to review evidence regarding the existence, composition, and release of different EVs, as well as the biomarkers, cargos, and separation methods. We also reviewed the potential of EVs to transport cargos and alter the function and phenotype of recipient cells associated with aging and reproductive diseases, including polycystic ovary syndrome and endometriosis. In aging, EVs promote inflammatory reactions and offsetting the occurrence of aging. In the polycystic ovary syndrome and endometriosis, EVs and their cargos are involved in the occurrence of diseases, therapeutic strategies, and perform as non-invasive biomarkers. As the study of EVs is still in the early stages, it is not surprising that most of the current literature only describes their possible roles.

Association of TNF-α gene T-1031C polymorphism with endometriosis: A meta-analysis

The single nucleotide polymorphism T-1031C has shown to have an important role in the regulation and transcription efficiency of TNF-α gene. Yet, the relationship between TNF-α T-1031C gene polymorphism and the development of endometriosis (EM) still remains unclear. The aim of this meta-analysis was to summarize the effects of TNF-α T-1031C gene polymorphism and clarify their possible association with EM. A comprehensive literature search was performed using PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials (up to August 10, 2019). A fixed- or random-effects model was employed according to the heterogeneity among studies. The log odds ratios and 95% confidence intervals (CIs) were estimated in the models of allele comparison (T vs C), homozygote comparison (TT vs CC) and (TC vs CC), dominant (TT vs TC + CC), hyperdominant (TT + CC vs TC), and recessive (TT + TC vs CC) to estimate the strength of the associations. A total of 7 case-control studies were included in this meta-analysis. Overall, significant associations between TNF-α T-1031C and EM were identified from (T vs C: log OR [95% CI] = 0.31 [-0.09, 0.71]; TT + CC vs TC: 0.27 [0.04, 0.50]; TC + CC vs TT: -0.83 [-1.19, -0.47]). On the other hand, no significant correlation was found in other gene models (TT vs TC: log OR [95% CI] = 0.89 [0.64, 1.13]; TT vs CC: 0.3 [-0.74, 1.36]; TT + TC vs CC: 0.17 [-0.81, 1.15]). In subgroup analyses by ethnicity or HWE P-value, there was a statistically significant association between TNF-α T-1031C polymorphisms and EM in the dominant model (TT vs TC + CC: log OR [95%] = -0.84 [-1.60, -0.09]) for the European population, and in hyperdominant model (TT + CC vs TC: log OR [95%] = 0.24 [0.001, 0.49]) for Asian population. To sum up, this meta-analysis showed that TNF-α T-1031C polymorphism was associated with EM susceptibility and has a protective effect in Asian and European populations.

Macrophages alternatively activated by endometriosis-exosomes contribute to the development of lesions in mice

STUDY QUESTION

Do exosomes play a role in the pathogenesis of endometriosis in a murine model?

SUMMARY ANSWER

Exosomes from endometriosis (EMS) can alternatively activate macrophages and thus contribute to the development of lesions in mice.

WHAT IS KNOWN ALREADY

The pathogenesis of endometriosis, an inflammatory disease, possibly involves peritoneal macrophages. Exosomes are recognized as a new communicator among cells and a key modulator in several inflammatory diseases.

STUDY DESIGN, SIZE, DURATION

We performed in vitr and in vivo experiments to demonstrate the role of exosomes in modulating macrophages. RAW264.7 cells (macrophages) were used to examine the effects of exosomes on macrophages in vitro. An experiment was also conducted in vivo, as follows. Fifty C57BL/6 female mice were randomly allocated to five control and five experimental groups (n = 5/group). The experimental group was injected i.p. with EMS-exosomes derived from eutopic stromal cells, starting on Day-7 then every day for 1 week. The control group received CON-exosomes from mice without endometriosis. Peritoneal macrophages were assessed over the next 6 days. On Day 0, all mice were injected i.p. with endometrium to establish the endometriosis model. On Day 14, all mice were sacrificed, ectopic lesions were counted and measured.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Exosomes were isolated from endometrial stromal cells (ESCs) by ultracentrifugation and characterized through transmission electron microscopy, nanoparticle tracking analysis and western blot. After treatment with exosomes, the polarization and phagocytic ability of the macrophages were detected by flow cytometry analysis, immunofluorescent staining and RT-PCR. C57BL/6 mice were utilized to establish an endometriosis model by i.p. injection of endometrial segments.

MAIN RESULTS AND THE ROLE OF CHANCE

After treatment with EMS-exosomes, the macrophages were polarized into an M2-like phenotype and their phagocytic ability decreased (P < 0.05 versus treatment with CON-exosomes). The total weight and volume of the lesions in mice treated with EMS-exosomes significantly increased compared with those in mice treated with CON-exosomes (P < 0.05). The infiltration of M2-like macrophages was enhanced in the EMS-exosome group (P < 0.001 versus treatment with CON-exosomes).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Detection of endometriosis following exosome treatment was only performed in a murine endometriosis model. Clinical data and additional mechanism studies must be conducted to understand the role of exosomes in the pathogenesis of endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

This study emphasizes the importance of EMS-exosomes in the pathogenesis of endometriosis. Further investigations on the exosome signaling pathways may contribute to the development of effective treatments for endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by grants (Nos. 81571417 and 81771552) from the National Science Foundation of China. The authors report no conflict of interest.

Endometriosis, endocrine disrupters, and epigenetics: an investigation into the complex interplay in women with polybrominated biphenyl exposure and endometriosis

PURPOSE

Endocrine disrupting compounds (EDCs) have been shown to affect multiple biologic processes especially steroid-hormone processes. We sought to determine differences in DNA methylation exists between women with and without endometriosis following exposure to polybrominated biphenyl (PBB).

METHODS

Cross-sectional study of 305 females in the Michigan PBB Registry. DNA was extracted, and DNA methylation was interrogated using the MethylationEPIC BeadChip (Illumina, San Diego, California). Demographic data was analyzed using Chi-squared and T tests. Linear regressions were performed for each cytosine-guanine dinucleotide (CpG) site, modeling the logit transformation of the β value as a linear function of the presence of endometriosis. Sensitivity analyses were conducted controlling for estradiol levels and menopausal status. Replication study performed evaluating for any association between CpGs reported in the literature and our findings.

RESULTS

In total, 39,877 CpGs nominally associated with endometriosis (p < 0.05) after adjusting for age and cellular heterogeneity, although none remained significant after correction for multiple comparisons (FDR < 0.05). Pathway analysis of these CpGs showed enrichment in 68 biologic pathways involved in various endocrine, immunologic, oncologic, and cell regulation processes as well as embryologic reproductive tract development and function (FoxO, Wnt, and Hedgehog signaling). We identified 42,261 CpG sites in the literature reported to be associated with endometriosis; 2012 of these CpG sites were also significant in our cohort.

CONCLUSION

We found 39,877 CpG sites that nominally associated with endometriosis (p < 0.05) after adjusting for age and cellular heterogeneity; however, none remained significant after correction for multiple comparisons (FDR < 0.05).

Evaluation of the brain functional activities in rats various location-endometriosis pain model

Background

Endometriosis (EM) is a common gynecological disease in women of reproductive age. These patients in approximately 80% suffer the various degree pain. This study will investigate synergistically the mechanism of the higher-position central sensitization and offer a pre-clinical experiment evidence for treatment of various location-EM patients with pain.

Methods

Twenty Sprague-Dawley rats were induced three types EM including abdominal EM (n=5), gastrocnemius EM (n=5) and ovary EM group (n=5) and one sham control group (n=5). All groups were measured the pain sensitization by hotplate test, then scanned by the functional magnetic resonance imaging (fMRI). The resting-state fMRI (rs-fMRI) date was analyzed using regional homogeneity (ReHo) approach to find out the abnormal functional activity brain regions. Nissl staining method observed the state of neurons in aberrant ReHo signal brain regions.

Results

Rats with EM pain sensitization were increased in abdominal EM and gastrocnemius EM than ovary EM group and sham control. The ReHo value is decreased in gastrocnemius EM in right thalamus and left olfactory tubercle compared with other three groups. The number of neurons was decreased; cavitation around nucleus, and pyknotic homogenous nuclei. Nissl bodies were stained deeply, and the shape was irregular in gastrocnemius EM by Nissl staining in right thalamus. In left olfactory tubercle, there was no significant difference in 4 groups.

Conclusions

The thalamus may be the potential key brain region for the central sensitization mechanism of various location-EM pain. The oxidative activation may be weakened in thalamus in gastrocnemius EM group with more severe pain. This finding could lend support for future research on the imageology and pathology of various location-EM pain.

Role of thyroid dysimmunity and thyroid hormones in endometriosis

Endometriosis is characterized by the presence of ectopic endometrial cells outside the uterine cavity. Thyroid autoimmunity has been associated with endometriosis. This work investigated the potential pathophysiological link between endometriosis and thyroid disorders. Transcripts and proteins involved in thyroid metabolism are dysregulated in eutopic and ectopic endometrium of endometriotic patients, leading to resistance of ectopic endometrium to triiodothyronine (T3) action and local accumulation of thyroxine (T4). Thyroid-stimulating hormone (TSH) acts as a proliferative and prooxidative hormone on all endometria of endometriosis patients and controls, whereas T3 and T4 act to specifically increase ectopic endometrial cell proliferation and reactive oxygen species (ROS) production. Mouse studies confirmed the data gained in vitro since endometriotic implants were found to be bigger when thyroid hormones increased. A retrospective analysis of endometriosis patients with or without a thyroid disorder revealed an increased chronic pelvic pain and disease score in endometriotic patients with a thyroid disorder.

Endometriotic lesions

Endometriosis is a complex gynaecological condition affecting women of reproductive age. It is characterised by the presence of lesions containing endometrial glands and stroma outside the uterus. The disease is typically associated with pelvic pain (including dysmenorrhoea and dyspareunia), infertility and bowel-related symptoms. Endometriotic lesions have a highly variable presentation and most commonly occur in the abdominal cavity. These lesions are broadly classified into peritoneal, ovarian and deep infiltrating endometriosis. There have been observations of increased density of nerve fibres and neurological molecules in the endometriotic lesions compared to the uninvolved peritoneum of women without endometriosis and the presence of unmyelinated nerve fibres were higher near the glands. The lesion sites are characterised by a range of immunological alterations, and specific immune cell populations have also been known to synthesise and secrete neurogenic factors. Endometriotic lesions are capable of producing prostaglandins which are direct generators of pain and are capable of inducing inflammation. Diagnosing the disease involves direct visualisation of the lesions through a laparoscopic or laparotomy, which is followed by histopathological examination of biopsied or excised lesions. The staging of endometriosis due to its complexity is highly variable as presentation and gaps in knowledge pose a great challenge in the classification of the disease. The medical management of endometriosis aims at providing adequate analgesia and suppression of the activity of the lesion. A better understanding of endometriotic lesion relationships between innervations and specific clinical characteristics may elucidate aspects of pain mechanisms and infertility in endometriosis and facilitate the development of novel therapeutic approaches.

Anti-inflammatory cytokines in endometriosis

Although the pathogenesis of endometriosis is not fully understood, it is often considered to be an inflammatory disease. An increasing number of studies suggest that differential expression of anti-inflammatory cytokines (e.g., interleukin-4 and -10, and transforming growth factor-β1) occurs in women with endometriosis, including in serum, peritoneal fluid and ectopic lesions. These anti-inflammatory cytokines also have indispensable roles in the progression of endometriosis, including by promoting survival, growth, invasion, differentiation, angiogenesis, and immune escape of the endometriotic lesions. In this review, we provide an overview of the expression, origin, function and regulation of anti-inflammatory cytokines in endometriosis, with brief discussion and perspectives on their future clinical implications in the diagnosis and therapy of the disease.

Research on central sensitization of endometriosis-associated pain: a systematic review of the literature

Endometriosis-associated pain afflicts an enormous number of women who suffer from endometriosis. There is an urgent need to explore the pathogenesis of endometriosis-associated pain to identify targets for treatment of hyperalgesia. A search was conducted in PubMed, Web of Science, Embase, and the Cochrane Library using the search terms "endometriosis" AND ("pain" OR "hyperalgesia" OR "nociception" OR "allodynia") AND "central sensitization". The search was limited to articles published in English from 01/01/2008 to the present. Among the search results, 15 articles were eligible for systematic review, including 6 reviews, 6 human studies (one in the form of a conference abstract only), and 3 animal studies. The articles were classified into 4 lists to describe the mechanism of endometriosis-associated pain and synthesize different aspects of research on it. In conclusion, there is a need to explore the mechanism of endometriosis-associated pain in terms of innervation, vascularization, local inflammation, cross-correlated visceral sensitization, and central sensitization to identify the target molecules and signaling pathways of key genes and relevant biomarkers through new techniques, all with the goal of developing a more comprehensive treatment strategy for endometriosis than is currently available.

Effect of type II collagen extract on immunosuppression induced by methotrexate in rats

This study investigated the effect of type II collagen extract on SD rats with deteriorated immunity caused by methotrexate. The test samples were dosed once a day for 28 days by gastric gavage at dosage 250 mg/kg and 500 mg/kg after methotrexate treatment, and the changes on body weight, total blood leukocyte numbers, the percentages of B-cells, CD4+ T-cells and CD8+ T-cells in the blood and spleen were observed. The changes on body weight, the total blood leukocyte numbers, the total lymphocyte numbers in the spleen, the ratio of CD4+ and CD8+ T-cells in the blood and spleen were increased significantly in type II collagen extract groups as compared with the control group. According to the above results, type II collagen extract has an effect of increasing immune responses on rats with deteriorated immunity caused by methotrexate.

Absence of formyl peptide receptor 1 causes endometriotic lesion regression in a mouse model of surgically-induced endometriosis

Endometriosis is a female disease in which endometrial tissues grows outside the uterus. Patients showed alterations in endocrine and immune systems. Endometriotic lesions are characterized by deregulated interaction between immune cells and tissue cells. The formyl peptide receptor 1 (Fpr1) is expressed by both immune and stromal cells including epithelial cells. We investigated the development of the physiopathology of the surgically-induced endometriosis in Fpr1 KO mice compared to WT animals. Operated Fpr1 KO mice showed lower duration of uterine pain behaviors, lower size of developed cysts and reduced mast cell numbers. Immunohistochemical analyses indicated changes in NGF, VEGF and ICAM-1 expression associated with the pathology, which were reduced in absence of the Fpr1 gene. Molecular analyses indicated that in absence of Fpr1 there was reduced neutrophils accumulation and nitrosative stress formation, NF-κB translocation into the nucleus as well as NRLP3 inflammasome signalling. Fpr1 gene deletion caused reduction of resistance to the apoptosis, assessed by TUNEL assay. We underline the pathogenic role of Fpr1 in experimental endometriosis, which is the result of modulation of immune cell recruitment, suggesting it as a new target to control the pathologic features of endometriotic lesions.

The Characteristic Expression of CD3+ T Cells, CD8+ T Cells and CD57+ NK Cells in Distinct Zones of Peritoneal Endometriotic Lesions

Background: Endometriosis is a benign gynecological condition, associated with a dysfunctional immune response that facilitates progression of peritoneal lesions. Specific immune cells are hypothesized to be recruited to peritoneal endometriotic lesions; though little is known about the significance of specific T and NK cell expression and the microanatomical zoning of lesions. This study aimed to characterize the zoning of T and NK cell populations in endometriotic peritoneal lesions compared to histologically normal peritoneum.

Methods and Results: Immunohistochemical analysis of CD3+ and CD8+ T cells and CD57+ NK cells in 18 peritoneal endometrial lesions and 20 normal peritoneal biopsies revealed greatly increased expression of these immune cells in women with confirmed endometriosis. Alpha-smooth muscle actin (α-SMA) antibody was used to detect the reactive a-SMA zone surrounding the core glands and stroma. CD57+ NK cells and CD3+ and CD8+ T cells were significantly over-expressed (p<0.01) throughout the peritoneal endometriotic lesions compared to normal peritoneum (in women without endometriosis) and these cells were highly expressed in the core lesion zone compared to expression in the adjacent α-SMA zone and surrounding peritoneum.

Conclusions: Our observations support the concept that immune cell populations are recruited into developing endometriotic lesions. We have for the first time shown that NK and T immune cells are distributed differentially across various microanatomical zones of peritoneal lesions. Such understanding of zone specific immune-cell expression is crucial for better defining the roles these immune cells play in endometriotic lesion establishment and progression.

Efficacies of vitamin D and omega-3 polyunsaturated fatty acids on experimental endometriosis

OBJECTIVE

The aim of this study was to investigate the effects of 1,25-dihydroxyvitamin-D3 (vitamin D) and omega-3 polyunsaturated fatty acids (omega-3 PUFA) on experimentally induced endometriosis in a rat model.

MATERIALS AND METHODS

A prospective, single-blind, randomized, controlled experimental study was performed on 30 Wistar female rats. Endometriosis was surgically induced by implanting endometrial tissue on the abdominal peritoneum. Four weeks later, a second laparotomy was performed to assess pre-treatment implant volumes and cytokine levels. The rats were randomized into three groups: vitamin D group (42 μg/kg/day), omega-3 PUFA group (450 mg/kg/day), and control group (saline 0.1 mL/rat/day). These treatments were administered for 4 weeks. At the end of treatment, a third laparotomy was performed for the assessment of cytokine levels, implant volumes (post-treatment) and implants were totally excised for histopathologic examination. Pre- and post-treatment volumes, cytokine levels within the groups, as well as stromal and glandular tissues between the groups were compared.

RESULTS

The mean post-treatment volume was statistically significantly reduced in the omega-3 PUFA group (p=0.02) and the level of the interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), vascular endothelial growth factor (VEGF) in the peritoneal fluid were significantly decreased at the end of treatment in the omega-3 PUFA group (p=0.02, p=0.03, and p=0.03, respectively). In the vitamin D group, only IL-6 levels were significantly decreased. In the histopathologic examination, the glandular tissue and stromal tissue scores of the implants were significant lower in the omega-3 PUFA group (p=0.03 and p=0.02).

CONCLUSION

Omega-3 PUFA caused significant regression of endometriotic implants. Vitamin D has not been as effective as omega-3 PUFA on endometriosis.

Increased expression of resistin in ectopic endometrial tissue of women with endometriosis

PROBLEM

Inflammation is a key process in the establishment and progression of endometriosis. Resistin, an adipocytokine, has biological properties linked to immunologic functions, but its role in endometriosis is unclear.

METHOD OF STUDY

Resistin gene expression was examined in eutopic and ectopic endometrial tissues from women with (n=25) or without (n=25) endometriosis. Resistin mRNA and protein levels were determined in endometrial tissue using quantitative real-time reverse transcription PCR and Western blotting, following adipokine profiling arrays.

RESULTS

Resistin protein was detected in human endometrial tissues using an adipokine array test. Resistin mRNA and protein levels were significantly higher in ectopic endometrial tissue of patients with endometriosis than in normal eutopic endometrial tissue.

CONCLUSION

Our results indicate that resistin is differentially expressed in endometrial tissues from women with endometriosis and imply a role for resistin in endometriosis-associated pelvic inflammation.

Vitamin C is effective for the prevention and regression of endometriotic implants in an experimentally induced rat model of endometriosis

OBJECTIVE

Endometriosis is a chronic inflammatory disease pathologically defined as the presence of endometrial-like tissue outside the uterine cavity. It is one of the most important diseases affecting women of reproductive age. The process of endometriotic implant growth is mediated by many complex interactions of immunologic, hormonal, genetic, and environmental mediators. Vitamin C (ascorbic acid), besides playing a role in preventing invasion and metastasis, is an antioxidant having anti-inflammatory and -angiogenic effects. In this study, we aimed to investigate the effect of vitamin C on the prevention and regression of endometriotic implants in a rat model of endometriosis.

MATERIALS AND METHODS

This was a prospective, comparative, experimental animal study. After endometriotic implants were induced simultaneously, rats were divided into three groups. Group A was given 500 mg/kg of intravenous vitamin C every 2 days, starting immediately after implantation (n = 11). All rats had a second operation 21 days after the initial one and had the lesion volumes measured. Group B was given 500 mg/kg of intravenous vitamin C every 2 days, starting 21 days after this operation (n = 11). All rats were sacrificed 21 days after the third operation. Implant volume, weight measurements, and histopathological evaluation of the lesions were carried out. Group A received vitamin C throughout the study, while Group C (n = 11) was not given any medication. The findings in the three groups were compared.

RESULTS

At the second laparotomy after the induction, Group A had the smallest implant volume with a statistically significant difference compared to Group B (p = 0.012). The end-of-study volumes of endometriotic implants of group B were significantly smaller than the first volumes (p < 0.05).

CONCLUSION

Intravenous vitamin C treatment might have a suppressive effect on the prevention of endometriotic implant induction and regression of endometriotic implant volumes.

Biomarkers in endometriosis: challenges and opportunities

Endometriosis is a debilitating gynecologic disease affecting millions of women across the world, with symptoms including dysmenorrhea, chronic pelvic pain, and infertility. Theorized to stem from the phenomenon of retrograde menstruation, the diagnosis of endometriosis is typically delayed by 8-10 years owing to misinterpretation of symptoms as common menstrual cramps in adolescent girls and young women. With increased incidence of endometriosis in young girls correlated with earlier menarche, the development of diagnostic biomarkers is imperative for diagnosing and treating women afflicted with endometriosis as early as we can. In the past few years, multiple reviews highlighted the list of potential diagnostic candidates in peritoneal fluid, blood, urine, and endometrial biopsies from endometriosis patients in different stages of disease and menstrual cycle. In this review, we explore the opportunities and challenges facing the field of diagnostic biomarkers for endometriosis. We highlight the importance of eutopic endometrium as a source of potential diagnostic biomarkers by looking at the expression levels of noncoding RNA in tissue as well as in blood. Finally, we discuss some of the challenges that hinder our efforts in validating candidate diagnostic biomarkers for endometriosis.

Co-micronized Palmitoylethanolamide/Polydatin Treatment Causes Endometriotic Lesion Regression in a Rodent Model of Surgically Induced Endometriosis

Endometriosis is a chronic, painful disease characterized by the presence of endometrial glands and stroma outside the uterine cavity. Palmitoylethanolamide (PEA), an endogenous fatty acid amide, has anti-inflammatory and neuroprotective effects. PEA lacks free radical scavenging activity, unlike polydatin (PLD), a natural precursor of resveratrol. The aim of this study was to investigate the effect of orally administered co-micronized PEA/polydatin [m(PEA/PLD)] in an autologous rat model of surgically induced endometriosis. Endometriosis was induced in female Wistar albino rats by auto-transplantation of uterine squares (implants) into the intestinal mesentery and peritoneal cavity. Rats were distributed into one control group and one treatment group (10 animals each): m(PEA/PLD) 10 mg/kg/day. At 28 days after surgery the relative volume of the endometrioma was determined. Endometrial-like tissue was confirmed by histology: Masson trichrome and toluidine blue were used to detect fibrosis and mast cells, respectively. The treated group displayed a smaller cyst diameter, with improved fibrosis score and mast cell number decrease. m(PEA/PLD) administration decreased angiogenesis (vascular endothelial growth factor), nerve growth factor, intercellular adhesion molecule, matrix metalloproteinase 9 expression, and lymphocyte accumulation. m(PEA/PLD) treatment also reduced peroxynitrite formation, (poly-ADP)ribose polymerase activation, IkBα phosphorylation and nuclear facor-kB traslocation in the nucleus. Our results suggested that m(PEA/PLD) may be of use to inhibit development of endometriotic lesions in rats.

STAT4 single nucleotide gene polymorphisms and susceptibility to endometriosis-related infertility

INTRODUCTION

Endometriosis is a multifactorial benign gynecologic disorder, characterized by the ectopic growth of misplaced endometrial cells with complex genetic inheritance and changing of some immune based factors and also shares some autoimmune characteristics. However, it is not clear yet that how and when these immunological factors affect the initiation or progression of the disease. It has been shown that STAT4 is a predisposing gene in the development of some autoimmune diseases.

METHOD

The study group comprised 114 patients with endometriosis and 92 sex-, age-, and ethnicity-matched healthy controls of Iranian ancestry. Four SNPs (rs7574865, rs7601754, rs7582694 and rs11889341) were genotyped using the MGB TaqMan.

RESULTS

A significant association in rs7582694 between C allele (P=0.002, OR=1.986, 95% CI: 1.262-3.126) and endometriosis was found in our study, while the G allele (P=0.002, OR=0.0503, 95% CI: 0.319-0.792) was significantly decreased in the patients population. The GC genotype (P=0.004, OR=2.234, 95% CI: 1.301-4.150) was also significantly overrepresented in the patients with endometriosis, while the frequency of GG genotype was significantly lower in the patient group, compared to the controls (P=0.007, OR=0.457, 95% CI: 0.256-0.813).

CONCLUSIONS

Our results for the first time showed a significant association between rs7582694 alleles and genotypes and susceptibility to endometriosis in a population.

Evaluation of Risk Factors Associated with Endometriosis in Infertile Women

BACKGROUND

Endometriosis affects women's physical and mental wellbeing. Symptoms include dyspareunia, dysmenorrhea, pelvic pain, and infertility. The purpose of this study is to assess the correlation between some relevant factors and symptoms and risk of an endometriosis diagnosis in infertile women.

MATERIALS AND METHODS

A retrospective study of 1282 surgical patients in an infertility Institute, Iran between 2011 and 2013 were evaluated by laparoscopy. Of these, there were 341 infertile women with endometriosis (cases) and 332 infertile women with a normal pelvis (comparison group). Chi-square and t tests were used to compare these two groups. Logistic regression was done to build a prediction model for an endometriosis diagnosis.

RESULTS

Gravidity [odds ratio (OR): 0.8, confidence interval (CI): 0.6-0.9, P=0.01], parity (OR: 0.7, CI: 0.6-0.9, P=0.01), family history of endometriosis (OR: 4.9, CI: 2.1-11.3, P<0.001), history of galactorrhea (OR: 2.3, CI: 1.5-3.5, P=0.01), history of pelvic surgery (OR: 1.9, CI: 1.3-2.7, P<0.001), and shorter menstrual cycle length (OR: 0.9, CI: 0.9-0.9, P=0.04) were associated with endometriosis. Duration of natural menstruation and age of menarche were not correlated with subsequent risk of endometriosis (P>0.05). Fatigue, diarrhea, constipation, dysmenorrhea, dyspareunia, pelvic pain and premenstrual spotting were more significant among late-stage endometriosis patients than in those with early-stage endometriosis and more prevalent among patients with endometriosis than that of the comparison group. In the logistic regression model, gravidity, family history of endometriosis, history of galactorrhea, history of pelvic surgery, dysmenorrhoea, pelvic pain, dysparaunia, premenstrual spotting, fatigue, and diarrhea were significantly associated with endometriosis. However, the number of pregnancies was negatively related to endometriosis.

CONCLUSION

Endometriosis is a considerable public health issue because it affects many women and is associated with the significant morbidity. In this study, we built a prediction model which can be used to predict the risk of endometriosis in infertile women.

Syndecan-4 expression is upregulated in endometriosis and contributes to an invasive phenotype

OBJECTIVE

To study the expression and function of syndecan-4 in endometriosis.

DESIGN

Histopathological investigation of eutopic endometrium and experimental laboratory study on a cell line derived from epithelial endometriotic cells (12Z).

SETTING

University hospital laboratory.

PATIENT(S)

One hundred six women (62 controls/44 endometriosis) from the IVF center of Münster University Hospital aged 23-44 undergoing Pipelle biopsy and diagnostic exploratory laparoscopy.

INTERVENTION(S)

Eutopic endometrial tissue was investigated by immunohistochemistry for the expression of syndecan-4. The human endometriotic cell line 12Z was transiently transfected with syndecan-4 small interfering RNA and investigated for changes in cell behavior.

MAIN OUTCOME MEASURE(S)

Syndecan-4 expression in eutopic endometrium was evaluated immunohistochemically in endometrial glands and stroma. Scoring results were correlated with the stages of the menstrual cycle and presence or absence of endometriosis. Quantitative polymerase chain reaction was used to measure syndecan-4-dependent expression changes of MMP2, MMP3, MMP9, Rac1, and ATF2. Altered cell behavior was monitored by matrigel invasion assays and cell viability assays.

RESULT(S)

Syndecan-4 expression was significantly higher in the glands and stroma of patients with endometriosis compared with controls, whereas no menstrual cycle-dependent expression was observed. In 12Z cells, syndecan-4 depletion did not affect cell viability but resulted in a significantly reduced matrigel invasiveness and reduced expression of the small GTPase Rac1, the transcription factor ATF-2, and MMP3.

CONCLUSION(S)

The upregulation of syndecan-4 in the eutopic endometrium of endometriosis patients may facilitate the pathogenetic process by promoting invasive cell growth via Rac1, MMP3, and ATF-2.

Endometriosis: alternative methods of medical treatment

Endometriosis is an inflammatory estrogen-dependent disease defined by the presence of endometrial glands and stroma at extrauterine sites. The main purpose of endometriosis management is alleviating pain associated to the disease. This can be achieved surgically or medically, although in most women a combination of both treatments is required. Long-term medical treatment is usually needed in most women. Unfortunately, in most cases, pain symptoms recur between 6 months and 12 months once treatment is stopped. The authors conducted a literature search for English original articles, related to new medical treatments of endometriosis in humans, including articles published in PubMed, Medline, and the Cochrane Library. Keywords included "endometriosis" matched with "medical treatment", "new treatment", "GnRH antagonists", "Aromatase inhibitors", "selective progesterone receptor modulators", "anti-TNF α", and "anti-angiogenic factors". Hormonal treatments currently available are effective in the relief of pain associated to endometriosis. Among new hormonal drugs, association to aromatase inhibitors could be effective in the treatment of women who do not respond to conventional therapies. GnRH antagonists are expected to be as effective as GnRH agonists, but with easier administration (oral). There is a need to find effective treatments that do not block the ovarian function. For this purpose, antiangiogenic factors could be important components of endometriosis therapy in the future. Upcoming researches and controlled clinical trials should focus on these drugs.

Pro-inflammatory cytokines for evaluation of inflammatory status in endometriosis

THE AIM OF THE STUDY

The aim of the study was to investigate the serum pro-inflammatory cytokine profile in patients with diagnosed endometriosis.

MATERIAL AND METHODS

The study included 160 women, who were divided in two study groups (Group I - endometriosis; Group 2 - healthy). We evaluated the serum levels of interleukin (IL)-1β, IL-5, IL-6, IL-7, and IL-12, and of tumour necrosis factor α (TNF-α) with the use of Human Multiplex Cytokine Panels.

RESULTS

The serum level of IL-1β, IL-6, and TNF-α is significantly higher in women with endometriosis compared to women free of disease, from the control group (mean 10.777, 183.027, and 131.326, respectively, compared to 3.039, 70.043, and 75.285, respectively; p = 0.002, p < 0.001, and p = 0.015, respectively). No significant differences in the serum levels of IL-5 and IL-12 were observed between the studied groups, and IL-7 had a very low detection rate.

CONCLUSIONS

Women with endometriosis have elevated levels of key pro-inflammatory cytokines, i.e. IL-1β, IL-6, and TNF-α. At the same time, IL-1β and IL-6 could be used as predictors for endometriosis.

KIR2DS5 in the presence of HLA-C C2 protects against endometriosis

Endometriosis is defined as the presence of functional endometrial tissue outside the uterine cavity. Several hypotheses have attempted to explain the etiology and pathogenesis of endometriosis. Recently, it has been suggested that a defect of the natural killer (NK) activity in the recognition and lysis of endometrial cells is one of the crucial points in the development of this disease. Natural killer cells can express killer immunoglobulin-like receptors (KIR), which recognize class I human leukocyte antigens on target cells. We asked whether polymorphisms in KIR, HLA-C, and HLA-B genes are risk factors for endometriosis. We tested 153 women with endometriosis diagnosed on the basis of laparoscopic and histological examination, and 213 control healthy women, who gave birth to at least one child. The frequency of KIR genes in patients was similar to that in controls except for KIR2DS5, which exerted a protective effect only in HLA-C C2-positive individuals. Moreover, KIR2DS5-positive women with endometriosis had 13 times lower chance that the disease would occupy the peritoneum than KIR2DS5- and KIR2DS4del-negative ones (OR = 0.077, P = 0.0061). Similarly, KIR2DS4del-positive endometriotic persons had 11 times lower chance for peritoneal disease (OR = 0.094, P < 0.001). Negative linkage disequilibrium between KIR2DS5 and KIR2DS4del indicates that these genes are mutually exclusive. Our data suggest that KIR2DS5 may be associated with protection from endometriosis, whereas KIR2DS4del seems to be associated with higher disease stages, possibly by exclusion of protective KIR2DS5.

A potential novel treatment strategy: inhibition of angiogenesis and inflammation by resveratrol for regression of endometriosis in an experimental rat model

The aim of our study was to evaluate the effectiveness of resveratrol in experimentally induced endometrial implants in rats through inhibiting angiogenesis and inflammation. Endometrial implants were surgically induced in 24 female Wistar-Albino rats in the first surgery. After confirmation of endometriotic foci in the second surgery, the rats were divided into resveratrol (seven rats), leuprolide acetate (eight rats), and control (seven rats) groups and medicated for 21 d. In the third surgery, the measurements of mean areas and histopathological analysis of endometriotic lesions, VEGF, and MCP-1 measurements in blood and peritoneal fluid samples, and immunohistochemical staining were evaluated. After treatment, significant reductions in mean areas of implants (p < 0.01) and decreased mean histopathological scores of the implants (p < 0.05), mean VEGF-staining scores of endometriotic implants (p = 0.01), and peritoneal fluid levels of VEGF and MCP-1 (p < 0.01, for VEGF and p < 0.01, for MCP-1) were found in the resveratrol and leuprolide acetate groups. Serum VEGF (p = 0.05) and MCP-1 (p = 0.01) levels after treatment were also significantly lower in the resveratrol and leuprolide acetate groups. Resveratrol appears to be a potential novel therapeutic agent in the treatment of endometriosis through inhibiting angiogenesis and inflammation. Further studies are needed to determine the optimum effective dose in humans and to evaluate other effects on reproductive physiology.

Identification of local angiogenic and inflammatory markers in the menstrual blood of women with endometriosis

The aim of this study was to evaluate the presence of myeloperoxidase (MPO), N-acetyl-β-D-glucosaminidase (NAG), tumor necrosis factor alpha (TNF-α) and vascular endothelial growth factor (VEGF) in peripheral and menstrual blood in women with (n=10) and without (n=7) endometriosis. NAG and MPO activities were evaluated by enzymatic methods, whereas TNF-α and VEGF by immunoassay. No significant differences were found for these markers, neither in menstrual nor in peripheral blood between groups. Menstrual blood NAG (P=0.039) and MPO (P=0.0117) activities in the endometriosis group were significantly higher than in peripheral blood. NAG and MPO presented positive linear correlation in peripheral (P=0.07; r=0.641) and menstrual blood (P=0.01; r=0.603). These findings point to the existence of an increased local inflammatory activity in women with endometriosis.

Peripheral and endometrial dendritic cell populations during the normal cycle and in the presence of endometriosis

Background

Dysfunctional immune response may be implicated in endometriosis pathogenesis, and dendritic cells (DC) may play greater roles in this response than previously recognized. This study set out to evaluate peripheral blood and endometrial DC population changes in the presence and absence of endometriosis pathology.

Methods

Endometrial (n = 83) and peripheral blood samples (n = 30) were subjected to immunohistochemical techniques and flow cytometry, respectively, to assess DC populations in women with and without endometriosis. Three circulating DC subsets (MDC1, MDC2 and PDC, expressing CD1c, CD303 and CD141), and late-stage mature endometrial DCs (using DC-LAMP antibody) were investigated.

Results

A highly significant reduction in CD1c intensity on MDC1 populations in peripheral blood was observed between normal cycle proliferative and menstrual phases (p = 0.025), but not in women with endometriosis, in whom CD1c intensity was markedly increased at the time of menstruation (p = 0.05). A significant reduction in peripheral blood MDC2 (p = 0.016) and apparent reduction in endometrial DC-LAMP+ DC (trend, p = 0.062) were observed in women with endometriosis compared with controls, consistent with our preliminary DC data.

Conclusions

Cyclical variation in endometrial and circulating DC populations appears to be crucial during normal menstrual cycles and in the establishment of pregnancy. In endometriosis, circulating and endometrial DC populations are significantly dysregulated at a number of levels, and are likely to contribute to inefficient immunological targeting of endometrial fragments shed at menstruation, facilitating their survival and establishment of endometriosis.

Serum YKL-40 levels are altered in endometriosis

Endometriosis is traditionally defined as the presence of endometrial glands and stroma in ectopic locations, especially the pelvic peritoneum, ovaries and rectovaginal septum. YKL-40, a new biomarker of inflammation, is secreted by activated macrophages and neutrophils in different tissues with inflammation. Serum concentrations of YKL-40 are elevated in patients with diseases characterized by inflammation. We aimed to investigate the possible association between serum YKL-40 levels and endometriosis. A total number of 88 women were recruited for this case-control study. About 53 patients with surgically proven endometriosis were included, while 35 patients without endometriosis comprised the control group. Patients were classified as having minimal, mild, moderate and severe disease in accordance with the severity. Two new groups were formed by combining patients with minimal and mild disease (Stage 1-2) and with moderate and severe disease (Stage 3-4). Serum YKL-40 levels were statistically higher in the endometriotic group compared to control group (p:0.001). YKL-40 levels were significantly higher in Stage 3-4 group compared to Stage 1-2 group (p values 0.001) as well. Correlation analysis revealed a positive correlation between serum YKL-40 levels and the stage of the disease. YKL-40 may be utilized as a marker for determining the severity of endometriosis.

Altered genome-wide methylation in endometriosis

Endometriosis has been associated with aberrant methylation in the eutopic endometrium. Using a genome-wide methylation array, we identified differentially methylated genes in the endometrium from women with or without endometriosis. One hundred and twenty genes were significantly altered by >1.5-fold. In all, 59 genes were significantly hypermethylated and 61 genes were significantly hypomethylated. Changes in gene expression associated with the altered methylation status were validated using quantitative real-time polymerase chain reaction. A limited number of candidate genes are selectively methylated in the endometrium of women with endometriosis. Several genes not previously associated with endometriosis are aberrantly methylated and expressed. These include O-6-methylguanine-DNA methyltransferase, dual specificity phosphatase 22, cell division cycle associated 2, inhibitor of DNA binding 2, retinoblastoma binding protein 7, bone morphogenetic protein receptor, type 1B, tumor necrosis factor receptor 1B, zinc finger protein receptor 681, immunoglobulin superfamily, member 21, and tumor protein 73. Aberrant DNA methylation and gene expression of these genes may contribute to abnormal regulation of endometrial cell proliferation and function in women.

Role of iron overload-induced macrophage apoptosis in the pathogenesis of peritoneal endometriosis

This article presents an overview of the involvement of iron overload-induced nitric oxide (NO) overproduction in apoptosis of peritoneal macrophages of women with endometriosis. We have postulated that the peritoneal iron overload originated from retrograde menstruation or bleeding lesions in the ectopic endometrium, which may contribute to the development of endometriosis by a wide range of mechanisms, including oxidative damage and chronic inflammation. Excessive NO production may also be associated with impaired clearance of endometrial cells by macrophages, which promotes cell growth in the peritoneal cavity. Therefore, further research of the mechanisms and consequences of macrophage apoptosis in endometriosis helps discover novel therapeutic strategies that are designed to prevent progression of endometriosis.