Combination of 17β-estradiol with the environmental pollutant TCDD is involved in pathogenesis of endometriosis via up-regulating the chemokine I-309–CCR8

Melatonin: Current evidence on protective and therapeutic roles in gynecological diseases

Melatonin, a potent antioxidant and free radical scavenger, has been demonstrated to be effective in gynecological conditions and female reproductive cancers. This review consolidates the accumulating evidence on melatonin's multifaceted protective effects in different pathological contexts. In gynecological conditions such as endometriosis, polycystic ovary syndrome (PCOS), and uterine leiomyoma, melatonin has shown promising effects in reducing oxidative stress, inflammation, and hormonal imbalances. It inhibits adhesion molecules' production, and potentially mitigates leukocyte adherence and inflammatory responses. Melatonin's regulatory effects on hormone production and insulin sensitivity in PCOS individuals make it a promising candidate for improving oocyte quality and menstrual irregularities. Moreover, melatonin exhibits significant antitumor effects by modulating various signaling pathways, promoting apoptosis, and suppressing metastasis in breast cancers and gynecological cancers, including ovarian, endometrial, and cervical cancers. Furthermore, melatonin's protective effects are suggested to be mediated by interactions with its receptors, estrogen receptors and other nuclear receptors. The regulation of clock-related genes and circadian clock systems may also contribute to its inhibitory effects on cancer cell growth. However, more comprehensive research is warranted to fully elucidate the underlying molecular mechanisms and establish melatonin as a potential therapeutic agent for these conditions.

Therapeutic effects of melatonin on endometriosis, targeting molecular pathways: Current knowledge and future perspective

Endometriosis, the very serious disease in women creates a huge financial burden worldwide, which is comparable to diabetes mellitus. In addition to the typical pelvic pain, endometriosis is related to low life quality and decreased work efficiency; clinical consequences include mood complaints, metabolic impairments, inflammation, immunologic problems, and elevated malignancy risks. Several risk factors are correlated with endometriosis including elevated oxidative and nitrosative stress, long-lasting inflammation, raised immune tolerance, as well as autoimmunity. Melatonin is a natural molecule present throughout both the plant and animal kingdoms. It has numerous functions as an antioxidant and anti-inflammatory agent. Due to the anti-proliferative, antioxidant, anti-inflammatory, and anti-invasive features of melatonin, it performances as a beneficial agent to limit endometriosis; this involves several pathways including antiestrogenic, antioxidant, anti-inflammatory, and anti-apoptosis effects, as well as reducing the growth of E2-induced endometriotic tissue. Moreover, melatonin can favor sleep quality and decrease the unwanted signs in the patients. However, most of the data on melatonin accured from experimental works and additional clinical trials are needed. This review summarizes what is currently known regarding the influence of melatonin on endometriosis. AVAILABILITY OF DATA AND MATERIAL: Not applicable.

Pharmaceuticals targeting signaling pathways of endometriosis as potential new medical treatment: A review

Endometriosis (EM) is defined as endometrial tissues found outside the uterus. Growth and development of endometriotic cells in ectopic sites can be promoted via multiple pathways, including MAPK/MEK/ERK, PI3K/Akt/mTOR, NF-κB, Rho/ROCK, reactive oxidative stress, tumor necrosis factor, transforming growth factor-β, Wnt/β-catenin, vascular endothelial growth factor, estrogen, and cytokines. The underlying pathophysiological mechanisms include proliferation, apoptosis, autophagy, migration, invasion, fibrosis, angiogenesis, oxidative stress, inflammation, and immune escape. Current medical treatments for EM are mainly hormonal and symptomatic, and thus the development of new, effective, and safe pharmaceuticals targeting specific molecular and signaling pathways is needed. Here, we systematically reviewed the literature focused on pharmaceuticals that specifically target the molecular and signaling pathways involved in the pathophysiology of EM. Potential drug targets, their upstream and downstream molecules with key aberrant signaling, and the regulatory mechanisms promoting the growth and development of endometriotic cells and tissues were discussed. Hormonal pharmaceuticals, including melatonin, exerts proapoptotic via regulating matrix metallopeptidase activity while nonhormonal pharmaceutical sorafenib exerts antiproliferative effect via MAPK/ERK pathway and antiangiogenesis activity via VEGF/VEGFR pathway. N-acetyl cysteine, curcumin, and ginsenoside exert antioxidant and anti-inflammatory effects via radical scavenging activity. Natural products have high efficacy with minimal side effects; for example, resveratrol and epigallocatechin gallate have multiple targets and provide synergistic efficacy to resolve the complexity of the pathophysiology of EM, showing promising efficacy in treating EM. Although new medical treatments are currently being developed, more detailed pharmacological studies and large sample size clinical trials are needed to confirm the efficacy and safety of these treatments in the near future.

Associations between Exposure to Organochlorine Chemicals and Endometriosis: A Systematic Review of Experimental Studies and Integration of Epidemiological Evidence

BACKGROUND

Growing epidemiological evidence suggests that organochlorine chemicals (OCCs), including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), may play a role in the pathogenesis of endometriosis.

OBJECTIVES

We aimed to systematically review the experimental evidence (in vivo and in vitro) on the associations between exposure to OCCs and endometriosis-related end points.

METHODS

A systematic review protocol was developed following the National Toxicology Program /Office of Health Assessment and Translation (NTP/OHAT) framework and managed within a web-based interface. In vivo studies designed to evaluate the impact of OCCs on the onset or progression of endometriosis and proliferation of induced endometriotic lesions were eligible. Eligible in vitro studies included single-cell and co-culture models to evaluate the proliferation, migration, and/or invasion of endometrial cells. We applied the search strings to PubMed, Web of Science, and Scopus®. A final search was performed on 24 June 2020. Assessment of risk of bias and the level of evidence and integration of preevaluated epidemiological evidence was conducted using NTP/OHAT framework Results: Out of 812 total studies, 39 met the predetermined eligibility criteria (15 in vivo, 23 in vitro, and 1 both). Most studies (n=27) tested TCDD and other dioxin-like chemicals. In vivo evidence supported TCDD's promotion of endometriosis onset and lesion growth. In vitro evidence supported TCDD's promotion of cell migration and invasion, but there was insufficient evidence for cell proliferation. In vitro evidence further supported the roles of the aryl hydrocarbon receptor and matrix metalloproteinases in mediating steroidogenic disruption and inflammatory responses. Estrogen interactions were found across studies and end points.

CONCLUSION

Based on the integration of a high level of animal evidence with a moderate level of epidemiological evidence, we concluded that TCDD was a known hazard for endometriosis in humans and the conclusion is supported by mechanistic in vitro evidence. Nonetheless, there is need for further research to fill in our gaps in understanding of the relationship between OCCs and their mixtures and endometriosis, beyond the prototypical TCDD. https://doi.org/10.1289/EHP8421.

Influence of Stress on the Vitamin D-Vitamin D Receptor System, Macrophages, and the Local Inflammatory Milieu in Endometriosis

We previously demonstrated the negative impact of stress in an animal model of endometriosis. Although its role is unclear, altered levels of vitamin D (VitD) have been found in patients with this condition. VitD signaling through the VitD receptor (VDR) has anti-proliferative properties and induces an anti-inflammatory phenotype in macrophages. We hypothesized that stress impacts the vitamin D-VDR system, influencing macrophage behavior and the local inflammatory milieu in endometriosis. Endometriosis was surgically induced in female Sprague-Dawley rats, which were then exposed to uncontrollable, controllable, or no stress for 10 days. Sham controls received sutures only. VitD levels were measured by ELISA; cytokine levels by multiplex assay and PCR; and VDR expression and macrophage numbers assessed by immunohistochemistry and immunofluorescence. VDR expression in patient samples was assessed by immunohistochemical staining of a tissue microarray. Serum VitD levels were higher in endometriosis animals compared with sham (p < 0.01) with no significant effect of stress. Uncontrollable stress increased macrophage infiltration (p < 0.01) and VDR expression in vesicles, which were attenuated by controllable stress. Macrophage infiltration correlated with vesicle area (p < 0.05), and peritoneal vitamin D levels correlated with vesicle VDR expression (r = 0.81, p < 0.01). Decreased expression of chemokine ligand 2 (p < 0.05) and TGFβ was observed in endometriosis with uncontrollable stress, whereas IL12 increased with controllable stress. Differential expression of VDR was observed in patient tissues. Stress exacerbates development of cysts in endometriosis through mechanisms that include macrophage recruitment, cytokine changes, and a potentially perturbed VitD:VDR axis, suggesting an impact on the local inflammatory environment.

Multiplex analysis of 40 cytokines do not allow separation between endometriosis patients and controls

Endometriosis is a common gynaecological condition characterized by severe pelvic pain and/or infertility. The combination of nonspecific symptoms and invasive laparoscopic diagnostics have prompted researchers to evaluate potential biomarkers that would enable a non-invasive diagnosis of endometriosis. Endometriosis is an inflammatory disease thus different cytokines represent potential diagnostic biomarkers. As panels of biomarkers are expected to enable better separation between patients and controls we evaluated 40 different cytokines in plasma samples of 210 patients (116 patients with endometriosis; 94 controls) from two medical centres (Slovenian, Austrian). Results of the univariate statistical analysis showed no differences in concentrations of the measured cytokines between patients and controls, confirmed by principal component analysis showing no clear separation amongst these two groups. In order to validate the hypothesis of a more profound (non-linear) differentiating dependency between features, machine learning methods were used. We trained four common machine learning algorithms (decision tree, linear model, k-nearest neighbour, random forest) on data from plasma levels of proteins and patients’ clinical data. The constructed models, however, did not separate patients with endometriosis from the controls with sufficient sensitivity and specificity. This study thus indicates that plasma levels of the selected cytokines have limited potential for diagnosis of endometriosis.

Elevated serum chemokines are independently associated with both endometriosis and uranium exposure

Endometriosis is a complex disease impacted by the hormonal and immune systems. Cytokines and chemokines are serum biomarkers that maybe useful to develop a noninvasive disease diagnosis. Individuals in the Fernald Community Cohort were exposed to uranium, a heavy metal with radioactive properties and estrogenic potential; therefore, serum samples from women in this cohort with or without uranium and with or without endometriosis were compared for alterations in chemokine, cytokine, and matrix metalloproteinase (MMP) levels. Control women were matched to endometriosis cases by uranium exposure, age, and body mass index. MMP levels were not altered. Five chemokines and one cytokine significantly increased in endometriosis cases versus controls irrespective of uranium exposure. Uranium exposure alone was associated with an increase in inflammatory chemokines. The majority of the elevated chemokines in endometriosis cases play important roles in attracting T helper-2 cells, which may be vital to understanding the immune response in endometriosis.

Synergistic effect of regulatory T cells and proinflammatory cytokines in angiogenesis in the endometriotic milieu

STUDY QUESTION

Do regulatory T cells (Tregs) contribute to angiogenesis in endometriosis?

SUMMARY ANSWER

High levels of CCL17 and CCL22 cause the recruitment of Tregs, upregulate the immunosuppression of Tregs and, in turn, may promote angiogenesis in endometrial cells in synergy with proinflammatory cytokines.

WHAT IS ALREADY KNOWN

The peritoneal fluid of patients with endometriosis has a higher percentage of Tregs than that of normal individuals; however, the regulatory role of Tregs in the disease remains unclear.

STUDY DESIGN, SIZE, DURATION

This study used primary human endometrial stromal cells (ESCs), monocytes (Mo), Tregs and human umbilical vein endothelial cells (HUVECs). All experiments were performed at least three times.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The migration of Tregs was evaluated by the transwell migration assay. The activation of extracellular signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase and p38 signaling pathways was examined using the In-Cell WesternTM (LI-COR®) western blot analysis system, as well as by traditional western blot analysis. Changes in the expression of CCL22, CCL17, transforming growth factor-beta 1 (TGF-β1), Interleukin (IL)-1β, tumor necrosis factor alpha (TNF-α), IL-8 and vascular endothelial growth factor (VEGF) in cell-culture supernatant were detected by ELISA. We analyzed the Tregs by multicolor flow cytometry to directly test the expression of CCR4, CD4, CD25, Foxp3, CTLA-4, CD39 and CD73.

MAIN RESULTS AND THE ROLE OF CHANCE

Our results showed that ESCs-Mo co-culture produced significantly higher levels of CCL22 and CCL17 than ESCs or Mo cultured alone, and that estradiol (E2) or progesterone (P) further promoted this upregulation, demonstrating stronger chemotaxis on Tregs. The co-culture of ESCs with Mo stimulated TGF-β1 secretion by Tregs, which could be inhibited by anti-CCL22 or/and anti-CCL17 neutralizing antibodies (Abs). The expression of CCR4 by Tregs was upregulated in ESCs-Mo co-culture, especially by treatment with E2 and/or P, and this effect could be abolished by anti-CCL22 and/or anti-CCL17-neutralizing Abs. The Treg-ESCs-Mo co-culture treated with E2 (10-8 mol/l) and P (10-8 mol/l) could enhance the immunosuppression of Tregs, as proved by the elevated expression of Foxp3, CTLA-4, CD39 and CD73 on Tregs. ESCs-Mo co-culture could significantly promote the secretion of IL-1β and TNF-α. TGF-β1 from Tregs could activate p38/ERK1/2 signaling pathways in ESCs, and IL-1β and TNF-α produced by ESCs-Mo co-culture had synergistic roles with TGF-β1. TGF-β1 and the proinflammatory cytokines IL-1β or TNF-α could synergistically promote IL-8 and VEGF expression in ESCs via the p38/ERK1/2 signaling pathways. The high levels of IL-8 and VEGF in the supernatant of ESCs stimulated the angiogenesis of HUVECs.

LARGE SCALE DATA

None.

LIMITATIONS, REASONS FOR CAUTION

This study was only performed in vitro using eutopic ESCs, instead of ectopic cells, from endometriosis patients. Therefore, it is necessary to do further experiments to determine whether Tregs promote angiogenesis in the endometriotic milieu in synergy with proinflammatory cytokines in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Co-targeting Tregs and proinflammatory cytokines may be an effective treatment for endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Ministry of Science and Technology of China 2015CB943300 to L.D.-J.; National Natural Science Foundation of China, item number 81200425 to  W.X.-Q.; National Natural Science Foundation of China, item number 81471548 to L.D.-J.; and The Research Fund for the Doctoral Program of Higher Education of China to W.X.-Q. (20110071120093). The authors have no conflicts of interest to declare.

Polychlorinated biphenyls and its potential role in endometriosis

With the progress of global industrialization and environmental deterioration, the relationship between human health and the living environment has become an increasing focus of attention. Polychlorinated biphenyls (PCBs, including dioxin-like polychlorinated biphenyls and non-dioxin-like polychlorinated biphenyls), as part of the organic chlorine contaminants, have been suspected as playing a role in the etiopathogenesis of endometriosis. Several population-based studies have proposed that exposure to PCBs may increase the risk of developing endometriosis, while some epidemiological studies have failed to find any association between PCBs and endometriosis. The purpose of this review is to discuss the potential pathophysiological relationship between endometriosis and PCBs with a focus on both dioxin-like polychlorinated biphenyls and non-dioxin-like polychlorinated biphenyls.

Aberrant expression of epithelial leucine-rich repeat containing G protein-coupled receptor 5-positive cells in the eutopic endometrium in endometriosis and implications in deep-infiltrating endometriosis

OBJECTIVE

To characterize leucine-rich repeat containing G protein-coupled receptor 5-positive (LGR5⁺) cells from the endometrium of women with endometriosis.

DESIGN

Prospective experimental study.

SETTING

University hospital/fertility clinic.

PATIENT(S)

Twenty-seven women with endometriosis who underwent surgery and 12 healthy egg donors, together comprising 39 endometrial samples.

INTERVENTION(S)

Obtaining of uterine aspirates by using a Cornier Pipelle.

MAIN OUTCOMES MEASURE(S)

Immunofluorescence in formalin-fixed paraffin-embedded tissue from mice and healthy and pathologic human endometrium using antibodies against LGR5, E-cadherin, and cytokeratin, and epithelial and stromal LGR5⁺ cells isolated from healthy and pathologic human eutopic endometrium by fluorescence-activated cell sorting and transcriptomic characterization by RNA high sequencing.

RESULT(S)

Immunofluorescence showed that LGR5⁺ cells colocalized with epithelial markers in the stroma of the endometrium only in endometriotic patients. The results from RNA high sequencing of LGR5⁺ cells from epithelium and stroma did not show any statistically significant differences between them. The LGR5⁺ versus LGR5^- cells in pathologic endometrium showed 394 differentially expressed genes. The LGR5⁺ cells in deep-infiltrating endometriosis expressed inflammatory markers not present in the other types of the disease.

CONCLUSION(S)

Our results revealed the presence of aberrantly located LGR5⁺ cells coexpressing epithelial markers in the stromal compartment of women with endometriosis. These cells have a statistically significantly different expression profile in deep-infiltrating endometriosis in comparison with other types of endometriosis, independent of the menstrual cycle phase. Further studies are needed to elucidate their role and influence in reproductive outcomes.

Immunosuppressive macrophages induced by IDO1 promote the growth of endometrial stromal cells in endometriosis

It was previously demonstrated that anomalous expression of indoleamine 2,3-dioxygenase-1 (IDO1) in endometrial stromal cells (ESCs) stimulated an inflammatory response that subsequently initiated the activation of immunosuppressive macrophages in endometriosis. The aim of the present study was to clarify the effect of IDO1‑induced macrophages on the growth of ESCs in endometriosis. Normal ESCs, ectopic ESCs and normal ESCs treated with plasmid pEGFP‑N1‑IDO1 or SD11‑IDO1 short hairpin RNA were co‑cultured with peripheral blood‑derived monocyte (PBMC)‑driven macrophages directly for 48 h. Compared with normal ESCs, the PBMC‑driven macrophages that were co‑cultured with ectopic ESCs displayed a lower phagocytic ability. pEGFP‑N1‑IDO1 transfection of normal ESCs also decreased the phagocytic ability of co‑cultured macrophages. Additionally, pEGFP‑N1‑IDO1‑transfected ESC‑induced macrophages significantly increased the viability and proliferation of ESCs, while ESC apoptosis was decreased, compared with control ESCs. In conclusion, IDO1 educated-macrophages may facilitate the survival of retrograde endometrial tissues, and be involved in the pathogenesis of endometriosis.

Combined 17β-Estradiol with TCDD Promotes M2 Polarization of Macrophages in the Endometriotic Milieu with Aid of the Interaction between Endometrial Stromal Cells and Macrophages

The goal of this study is to elucidate the effects of 17β-estradiol and TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) on macrophage phenotypes in the endometriotic milieu. Co-culture of endometrial stromal cells (ESCs) and U937 cells (macrophage cell line) was performed to simulate the endometriotic milieu and to determine the effects of 17β-estradiol and/or TCDD on IL10, IL12 production and HLA-DR, CD86 expression by U937 macrophages. We found that combining 17β-estradiol with TCDD has a synergistic effect on inducing M2 activation when macrophages are co-cultured with ESCs. Moreover, the combination of 17β-estradiol and TCDD significantly enhanced STAT3 and P38 phosphorylation in macrophages. Differentiation of M2 macrophages induced by 17β-estradiol and TCDD were effectively abrogated by STAT3 and P38MAPK inhibitors, but not by ERK1/2 and JNK inhibitors. In conclusion, 17β-estradiol and TCDD in the ectopic milieu may lead to the development of endometriosis by inducing M2 polarization of macrophages through activation of the STAT3 and P38MAPK pathways.

Shikonin reduces endometriosis by inhibiting RANTES secretion and mononuclear macrophage chemotaxis

Endometriosis is a common disease in females of reproductive age and has the classic characteristic of mononuclear cell infiltration into lesions. Shikonin is an anti-inflammatory phytocompound obtained from Lithospermum erythrorhizon whose potential therapeutic effects in the treatment of endometriosis remain unclear. The working hypothesis of the present study was that shikonin is capable of inhibiting the development of endometriosis by inhibiting the chemotactic effect. In a murine model of endometriosis, shikonin significantly inhibited the growth of human endometrial tissue implanted into severe combined immunodeficiency (SCID) mice (P<0.05) and no adverse effects were observed. Mouse regulated upon activation normal T-cell expressed and secreted (mRANTES) levels in the peritoneal fluid of the animal endometriosis model were higher than those in normal SCID mice (P<0.05) and decreased significantly following shikonin treatment in a dose-dependent manner (P<0.05). Peritoneal fluid from SCID mice treated with shikonin inhibited the chemotaxis of monocytes; this inhibitory effect was eradicated by mRANTES antibody. In vitro, shikonin significantly inhibited RANTES expression in U937 cells that were cultured alone or co-cultured with human mesothelial and endometrial stromal cells. In addition, shikonin inhibited the RANTES-induced chemotaxis of U937 cells (P<0.05). The results indicate that shikonin inhibits the development of endometriosis by various mechanisms, including the inhibition of RANTES expression and the reduction of mononuclear cell migration to lesions. Therefore, shikonin may be a novel, useful and safe agent for treating endometriosis.

Chemokines in the pathogenesis of endometriosis and infertility

Endometriosis is a chronic benign disease that affects women of reproductive age causing abdominal pain and infertility. Its pathogenesis remains obscure despite all the research conducted over the past 100 years. However, there is a consensus among the specialists that the basis of its pathophysiology would be multifactorial. Many publications have demonstrated that chemokines are somehow associated with the development of endometriosis and infertility. In this study, we reviewed all PubMed literature using MeSH terms "chemokines" and "endometriosis" as well as "chemokines" and "female infertility" to establish what we know and what we do not yet know about this relationship.

Environmental Influences on the Development of Endometriosis

Purpose

Several environmental toxicants (ETs), including dioxins and dioxin-like compounds (DLCs), perfluorochemicals, organochlorine pesticides, phthalates, and heavy metals (especially cadmium with its estrogen-like properties in animal models) have been investigated as possibly being related to endometriosis.

Methods

Systematic review of pertinent literature.

Results

DLCs have been the most investigated ETs. DLCs are persistent organic pollutants with highly toxic potential and include three types of compounds: polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) or furans, and polychlorinated biphenyls (PCBs). The most toxic is 2, 3, 7, 8- tetrachlorodibenzo-p-dioxin (TCDD). The connection mechanism between dioxins and endometriosis is still unclear. However, dioxins and DLCs are endocrine-disrupting compounds that can affect the pathobiology of endometriosis at multiple levels. Part of the dioxin and DLCs toxic effects can be accounted for by their interaction with the aryl hydrocarbon receptor (AhR). It has been proposed that dioxin can initiate or promote endometriosis by means of interaction with estrogen receptors or by suppressing the expression of progesterone receptors. Furthermore, TCDD alters the expression of cytokines and growth factors, remodeling enzymes and cytochrome P450 expression and activity.

Conclusions

Studies in rhesus models have revealed a correlation between dioxin exposure and endometriosis. However, evidence from epidemiologic studies is inconclusive.

Growth mechanisms of endometriotic cells in implanted places: a review

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

Pathophysiological roles of chemokines in human reproduction: an overview

Chemokines are a group of small cytokines that have an ability to induce leukocyte migration. Chemokines exert their functions by binding and activating specific G protein-coupled receptors. Studies have unveiled pleiotropic bioactivities of chemokines in various phenomena ranging from immunomodulation, embryogenesis, and homeostasis to pathogenesis. In the mammalian reproductive system, chemokines unexceptionally serve in multimodal events that are closely associated with establishment, maintenance, and deterioration of fecundity. The aim of this review is to update the knowledge on chemokines in male and female genital organs, with a focus on their potential pathophysiological roles in human reproduction.