Role of interleukin-32 in the pathogenesis of endometriosis: in vitro, human and transgenic mouse data

Cancer-Associated Fibroblast-Secreted Exosomes Promote Gastric Cancer Cell Migration and Invasion via the IL-32/ESR1 Axis

Exosomes secreted by cancer-associated fibroblasts (CAFs) play a critical part in cancer progression. This study aimed to explore the effects of CAF-exosomes on gastric cancer (GC) cell metastasis. AGS and HGC-27 cells were treated with exosomes and cell viability, migration, and invasion were evaluated using Cell-Counting Kit-8 and Transwell assays. Exosome-regulated mRNAs were explored using quantitative real-time PCR. The relationship between interleukin (IL)32 and estrogen receptor 1 (ESR1) was evaluated using co-immunoprecipitation and dual-luciferase reporter assays. The results of this study show that CAF-derived exosomes promote GC cell viability, migration, and invasion. Exosome treatment increased the levels of IL32, which interacted with ESR1 and negatively regulated ESR1 levels. Rescue experiments were conducted to demonstrate that CAF-exosomes promoted biological behaviors of GC cells by upregulating IL32 and downregulating ESR1 expression. In conclusion, CAF-derived exosomes promote GC cell viability, migration, and invasion by elevating the IL32/ESR1 axis, suggesting a novel strategy for metastatic GC treatment.

Transgenic mice applications in the study of endometriosis pathogenesis

Endometriosis (EM), characterized by ectopic growth of endometrial tissues and recurrent pelvic pain, is a common disease with severe negative impacts on the life quality of patients. Conventional uterine tissue transplantation-based models have been broadly used to investigate the pathogenic mechanism(s) of EM. Transgenic mice with whole body or uterine/pelvic tissue-specific labelling by the expression of GFP, β-gal or other light-emitting or chromogenic markers enable investigators to analyze the contribution to endometriotic lesions by the donor or recipient side after uterine tissue transplantation. Moreover, when coupled to uterine tissue transplantation, transgenic mice with a specific EM-related gene knocked out or overexpressed make it possible to determine the gene's in vivo role(s) for EM pathogenesis. Furthermore, observations on the rise of de novo endometriotic lesions as well as structural/functional changes in the eutopic endometrium or pelvic tissues after gene manipulation will directly relate the cognate gene to the onset of EM. A major advantage of transgenic EM models is their efficiency for analyzing gene interactions with hormonal, dietetic and/or environmental factors. This review summarizes the features/sources/backgrounds of transgenic mice and their applications to EM studies concerning hormonal regulation, angiogenesis and inflammation. Findings from these studies, the advantages/disadvantages of transgenic EM models, and future expectations are also discussed.

Cytokine and chemokine profiles in women with endometriosis, polycystic ovary syndrome, and unexplained infertility

Numerous factors (including immunological, congenital, hormonal, and morphological disorders) can lead to infertility. In this regard, 3 specific diseases associated with infertility are discussed in this review study (i.e., polycystic ovary syndrome [PCOS], endometriosis [EMS], and unexplained infertility [UI]). PCOS is a common endocrine disorder characterized by chronic low-grade inflammation, and EMS is a benign disease characterized by the presence of ectopic endometrial tissue. UI refers to couples who are unable to conceive for no known reason. Conception and pregnancy are significantly affected by the immune system; in this regard, chemokines and cytokines play important roles in the regulation of immune responses. Patients with PCOS, EMS, and UI have altered cytokine and chemokine profiles, suggesting that dysregulation of these molecules may contribute to infertility in these conditions. Accordingly, the issue of infertility is addressed in this review study, a condition that affects approximately 16% of couples worldwide.

Potential link between the nerve injury-induced protein (Ninjurin) and the pathogenesis of endometriosis

Endometriosis remains a widespread but severe gynecological disease in women of reproductive age, with an unknown etiology and few treatment choices. The menstrual reflux theory is largely accepted as the underlying etiology but does not explain the morbidity or unpleasant pain sensations of endometriosis. The neurological and immune systems are both involved in pain mechanisms of endometriosis, and interlinked through a complex combination of cytokines and neurotransmitters. Numerous pieces of evidence suggest that the nerve injury-inducible protein, Ninjurin, is actively expressed in endometriosis lesions, which contributes to the etiology and development of endometriosis. It may be explored in the future as a novel therapeutic target. The aim of the present review was to elucidate the multifaceted role of Ninjurin. Furthermore, we summarize the association of Ninjurin with the pain mechanism of endometriosis and outline the future research directions. A novel therapeutic pathway can be discovered based on the potential pathogenic variables.

Complex Interplay between Autophagy and Oxidative Stress in the Development of Endometriosis

Endometriosis (Endo) is a chronic gynecological disease. This paper aimed to evaluate the modulation of autophagy, oxidative stress and apoptosis with Açai Berries in a rat model of endometriosis. Endometriosis was induced with an intraperitoneal injection of minced uterus tissue from a donor rat into a recipient one. The abdominal high-frequency ultrasound (hfUS) analysis was performed at 7 and 14 days from the endometriosis induction to evaluate the growth of the lesion during the experiment. Seven days from the induction, once the lesions were implanted, an Açai Berry was administered daily by gavage for the next seven days. At the end of the experiment, the hfUS analysis showed a reduced lesion diameter in animals given the Açai Berry. A macroscopical and histological analysis confirmed this result. From the molecular point of view, Western blot analyses were conducted to evaluate the autophagy induction. Samples collected from the Endo group showed impaired autophagy, while the Açai Berry administration inhibited PI3K and AKT and ERK1/2 phosphorylation and promoted autophagy by inactivating mTOR. Additionally, Açai Berry administration dephosphorylated ATG1, promoting the activity of the ATG1/ULK1 complex that recruited Ambra1/Beclin1 and Atg9 to promote autophagosome nucleation and LC3II expression. Açai Berry administration also restored mitophagy, which increased Parkin cytosolic expression. The Açai Berry increased the expression of NRF2 in the nucleus and the expression of its downstream antioxidant proteins as NQO-1 and HO-1, thereby restoring the oxidative imbalance. It also restored the impaired apoptotic pathway by reducing BCL-2 and increasing BAX expression. This result was also confirmed by the TUNEL assay. Overall, our results displayed that Açai Berry administration was able to modulate autophagy, oxidative stress and apoptosis during endometriosis.

Dienogest May Reduce Estradiol- and Inflammatory Cytokine-Induced Cell Viability and Proliferation and Inhibit the Pathogenesis of Endometriosis: A Cell Culture- and Mouse Model-Based Study

Dienogest (DNG) is a therapeutic medication used in endometriosis treatment. Limited data are available regarding its mechanism of action on endometrial cells. Using in vivo and in vitro models, we investigated whether DNG treatment causes significant biological changes in human endometrial stromal cells (ESCs). The markers related to the pathogenesis of endometriosis in ESCs were evaluated using estradiol, tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), and IL-32, administered alone or in combination with DNG. Implanted endometrial tissues were compared between C57BL/6 mice that did or did not receive DNG treatment by using size measurements and immunohistochemistry. A significant decrease in cell viability, protein kinase B (AKT) phosphorylation, and the expression of p21-activated kinase 4 and vascular endothelial growth factor were observed in ESCs treated with estradiol plus DNG. Cell viability, AKT phosphorylation, and proliferating cell nuclear antigen (PCNA) expression also decreased significantly after TNF-α plus DNG treatment. Treatment with IL-1β or IL-32 plus DNG significantly decreased cell viability or PCNA expression, respectively. The size of the implanted endometrial tissue significantly decreased in mice treated with DNG, accompanied by decreased PCNA expression. Thus, DNG may reduce cell viability and proliferation induced by estradiol, TNF-α, IL-1β, and IL-32, and inhibit the endometriosis pathogenesis by decreasing PCNA expression.

Copaiba Oil Resin Exerts an Additive Effect to Babassu Oil on Behavioral Changes in Human Endometriotic Cell Cultures

Background: Current drugs for the treatment of endometriosis are not able to completely cure the condition, and significant side effects hinder the continuation of treatment. Therefore, it is necessary to search for new drug candidates. In the present paper, the use of plant extracts is highlighted. Babassu oil and Copaiba oil resin have several therapeutic properties. We investigated the in vitro effects of two nanoemulsions containing oil extracted from Babassu (Orbignya speciosa) nuts (called SNEDDS-18) and/or oil resin extracted from Copaiba trunk (Copaifera langsdorffii) (called SNEDDS-18/COPA) on cultured human eutopic endometrium stromal cells from endometrial biopsies of patients without (CESC) and with (EuESC) endometriosis as well as human stromal cells from biopsies of endometriotic lesions (EctESC). Methods: CESC, EuESC, and EctESC were taken and treated with SNEDDS-18 and SNEDDS-18/COPA to evaluate their effects on cytotoxicity, cell morphology, proliferation, and signaling pathways. Results: After 48 h of incubation with SNEDDS-18 and SNEDDS-18/COPA, cell viability and proliferation were inhibited, especially in EctESC. The lowest concentration of both nanoemulsions reduced cell viability and proliferation and broke down the cytoskeleton in EctESCs. After 24 h of treatment a decrease in IL-1, TNF-α, and MCP-1 was observed, as well as an increase in IL-10 production. Conclusions: Both nanoemulsions can affect endometriotic stromal cell behaviors, thus revealing two potential candidates for new phytotherapeutic agents for the management of endometriosis.

A Paradoxical Effect of Interleukin-32 Isoforms on Cancer

IL-32 plays a contradictory role such as tumor proliferation or suppressor in cancer development depending on the cancer type. In most cancers, it was found that the high expression of IL-32 was associated with more proliferative and progression of cancer. However, studying the isoforms of IL-32 cytokine has placed its paradoxical role into a wide range of functions based on its dominant isoform and surrounding environment. IL-32β, for example, was found mostly in different types of cancer and associated with cancer expansion. This observation is legitimate since cancer exhibits some hypoxic environment and IL-32β was known to be induced under hypoxic conditions. However, IL-32θ interacts directly with protein kinase C-δ reducing NF-κB and STAT3 levels to inhibit epithelial-mesenchymal transition (EMT). This effect could explain the different functions of IL-32 isoforms in cancer. However, pro- or antitumor activity which is dependant on obesity, gender, and age as it relates to IL-32 has yet to be studied. Obesity-related IL-32 regulation indicated the role of IL-32 in cancer metabolism and inflammation. IL-32-specific direction in cancer therapy is difficult to conclude. In this review, we address that the paradoxical effect of IL-32 on cancer is attributed to the dominant isoform, cancer type, tumor microenvironment, and genetic background. IL-32 seems to have a contradictory role in cancer. However, investigating multiple IL-32 isoforms could explain this doubt and bring us closer to using them in therapy.

Interleukin-9 produced by helper T cells stimulates interleukin-8 expression in endometriosis

PROBLEM

Inflammation and immune responses play crucial roles in the development of endometriosis. Although interleukin-9 (IL-9) has a pro-inflammatory function in chronic inflammatory diseases, its function in endometriosis remains unknown. Here, we aimed to investigate the significance of IL-9 and IL-9-producing lymphocytes in endometriosis.

METHOD OF STUDY

Specimens were obtained from patients with and without endometriosis. Peritoneal fluid (PF), peripheral blood (PB), and ovarian endometrioma (OE) tissues were analyzed for the proportion of CD4⁺ IL-9⁺ lymphocytes and IL-9 concentration using flow cytometry and enzyme-linked immunosorbent assay. OE, endometrium with endometriosis (EE), and normal endometrium (NE) were analyzed for IL-9 receptor (IL-9R) expression using immunohistochemical staining. IL-9-dependent changes in Interleukin-8 (IL-8) expression in endometrial stromal cells from OE (OESCs) were evaluated using real-time PCR.

RESULTS

The proportion of CD4⁺ IL-9⁺ lymphocytes was higher in the PF, but not the PB, of patients with endometriosis than individuals without endometriosis (p < .05). However, IL-9 levels in the PF did not differ between those with and without endometriosis. We detected CD4+ IL-9+ lymphocytes in OE tissues and IL-9R in OE tissues and OESCs. In OESC culture, IL-9 significantly elevated IL-8 expression in a dose-dependent manner (p < .05), which was nullified by the addition of the anti-IL-9 receptor antibody. Furthermore, IL-9 additively stimulated IL-8 expression in the presence of TNF-α (p < .05).

CONCLUSION

Our findings show that IL-9 produced by helper T cells induces IL-8 expression, suggesting that IL-9 plays an important role in the development of endometriosis by stimulating IL-8 expression.

Integrative Analysis of Differently Expressed Genes Reveals a 17-Gene Prognosis Signature for Endometrial Carcinoma

Endometrial carcinoma (EC) is the fifth widely occurring malignant neoplasm among women all over the world. However, there is still lacking efficacy indicators for EC's prognosis. Here, we analyzed two databases including an RNA-sequencing-based TCGA dataset and a microarray-based GSE106191. After normalizing the raw data, we identified 114 common genes with upregulation and 308 common genes with downregulation in both the TCGA and GSE106191 databases. Bioinformatics analysis showed that the differently expressed genes in EC were related to the IL17 signaling pathway, PI3K-Akt signaling pathway, and cGMP-PKG signaling pathway. Furthermore, we performed the least absolute shrinkage and selection operator (LASSO) Cox regression analysis and generated a signature featuring 17 prognosis-related genes (MAL2, ANKRD22, METTL7B, IL32, ERFE, OAS1, TRPC1, SRPX, RAPGEF4, PSD3, SIMC1, TRPC6, WFS1, PGR, PAMR1, KCNK6, and FAM189A2) and found that it could predict OS in EC patients. The further analysis showed that OAS1, MAL2, ANKRD22, METTL7B, and IL32 were significantly upregulated in EC samples after comparison with normal samples. However, TRPC1, SRPX, RAPGEF4, PSD3, SIMC1, TRPC6, WFS1, PGR, PAMR1, KCNK6, and FAM189A2 were significantly downregulated in EC samples in comparison with normal samples. And correlation analysis showed that our results showed that the expressions of 17 prognosis-related hub genes were significantly correlated based on Pearson correlation. We here offer a newly genetic biomarker for the prediction of EC patients' prognosis.

Interleukin-37b inhibits the growth of murine endometriosis-like lesions by regulating proliferation, invasion, angiogenesis and inflammation

Endometriosis is a gynecological disease with abnormal expression of interleukin (IL)-37 which can suppress inflammation and the immune system. Here we investigated the role of the IL-37b splice variant in endometriosis in vivo and in vitro. In a murine model of endometriosis, in vivo administration of IL-37b significantly inhibited the development of lesions judged by the number (P = 0.0213), size (P = 0.0130) and weight (P = 0.0152) of lesions. IL-37b had no effect on the early stage of lesion formation, however administration in the growth stage of lesions decreased the number (P = 0.0158), size (P = 0.0158) and weight (P = 0.0258) of lesions compared with PBS control, an effect that was not reversed by macrophage depletion. Expressions of inflammatory factors, matrix metalloproteinases and vascular endothelial growth factor-A mRNA/protein were significantly inhibited in ectopic lesions following IL-37b administration, and in uterine segments treated in vitro. In vitro treatment of uterine segments with IL-37b inhibited phosphorylation of Akt and Erk1/2 in uterine segments. Isolated mouse endometrial stromal treated with IL-37b and transfected with pIL-37b plasmid got suppressed cell proliferation, invasion, angiogenesis and the expression of inflammatory factors. In addition, transfection with pIL-37b significantly decreased the phosphorylation of Akt and Erk1/2. IL-37b also inhibited proliferation and the expression of inflammatory and angiogenesis factors in epithelial cell line RL95-2. These findings suggest that IL-37b may inhibit the growth of lesions by regulating proliferation, invasion, angiogenesis and inflammation through Akt and Erk1/2 signaling pathway.

Inflammatory Mediators and Pain in Endometriosis: A Systematic Review

BACKGROUND

pain is one of the main symptoms of endometriosis and it has a deleterious effect on a patients' personal and social life. To date, the clinical management of pain includes prolonged medication use and, in some cases, surgery, both of which are disruptive events for patients. Hence, there is an urgency for the development of a sufficient non-invasive medical treatment. Inflammation is one of the causative factors of pain in endometriosis. It is well established that inflammatory mediators promote angiogenesis and interact with the sensory neurons inducing the pain signal; the threshold of pain varies and it depends on the state and location of the disease. The inhibition of inflammatory mediators' synthesis might offer a novel and effective treatment of the pain that is caused by inflammation in endometriosis.

OBJECTIVES

patients with endometriosis experience chronic pelvic pain, which is moderate to severe in terms of intensity. The objective of this systematic review is to highlight the inflammatory mediators that contribute to the induction of pain in endometriosis and present their biological mechanism of action. In addition, the authors aim to identify new targets for the development of novel treatments for chronic pelvic pain in patients with endometriosis.

DATA SOURCES

three databases (PubMed, Scopus, and Europe PMC) were searched in order to retrieve articles with the keywords 'inflammation, pain, and endometriosis' between the review period of 1 January 2016 to 31 December 2020. This review has been registered with PROSPERO (registry number: CRD42020171018). Eligibility Criteria: only original articles that presented the regulation of inflammatory mediators and related biological molecules in endometriosis and their contribution in the stimulation of pain signal were included.

DATA EXTRACTION

two authors independently extracted data from articles, using predefined criteria.

RESULTS

the database search yielded 1871 articles, which were narrowed down to 56 relevant articles of interest according to the eligibility criteria.

CONCLUSIONS

inflammatory factors that promote angiogenesis and neuroangiogenesis are promising targets for the treatment of inflammatory pain in endometriosis. Specifically, CXC chemokine family, chemokine fractalkine, and PGE2 have an active role in the induction of pain. Additionally, IL-1β appears to be the primary interleukin (IL), which stimulates the majority of the inflammatory factors that contribute to neuroangiogenesis along with IL-6. Finally, the role of Ninj1 and BDNF proteins needs further investigation.

HMGB1 Mediated Inflammation and Autophagy Contribute to Endometriosis

AIM

High mobility group box (HMGB)-1 has been implicated in endometriosis due to the important regulatory roles of inflammation in endometriosis. The aim of the present study was to explore the roles of HMGB-1 in endometriosis and to elucidate the underlying mechanism.

METHODS

Endometrial specimens were collected from women with endometriosis and healthy volunteers. Immunohistochemistry staining was used to determine the expression patterns and localization of HMGB-1 in the normal, eutopic and ectopic endometrial tissues. Western blotting and qRT-PCR were used to determine the mRNA and protein levels of inflammatory cytokines [interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-1β], autophagy-related markers [beclin-1, autophagy-related (atg)13, microtubule-associated protein light chain (LC)3-I, LC-II and p62] and HMGB-1, respectively. Spearman's rank correlation analysis was employed to investigate the correlation between HMGB-1 with inflammatory cytokines and beclin-1. Besides, human endometrial stromal cells (HESCs) were isolated from ectopic endometrium and subsequently transfected with shRNA against HMGB-1. After the transfected cells were subjected to hypoxia, ELISA was used to determine the levels of HMGB-1 and inflammatory cytokines in the cell supernatant. Western blotting was used to determine the expression levels of autophagy-related markers in the cells.

RESULTS

Positive correlations were observed between HMGB-1 and the inflammatory cytokines. In addition, a positive correlation was also identified between HMGB-1 and beclin-1 in the ectopic endometrium. Further results demonstrated that autophagy-related markers beclin-1, atg13 and p62 were significantly upregulated in the ectopic endometrium. In addition, HMGB-1 knockdown suppressed the levels of inflammatory cytokines IL-6, TNF-α and IL-1β and autophagy-related markers beclin-1 and atg13, while upregulated p62 in HESCs under hypoxic condition.

CONCLUSION

Knockdown of HMGB-1 under hypoxic condition regulated inflammatory cytokines and autophagy-related markers. HMGB-1 might contribute to the development of endometriosis in part through regulating inflammatory response and autophagy.

MTA1, a Target of Resveratrol, Promotes Epithelial-Mesenchymal Transition of Endometriosis via ZEB2

Endometriosis is a benign disease that shares some malignant features. Epithelial-mesenchymal transition (EMT) is involved in the pathogenesis of endometriosis. Metastasis-associated protein 1 (MTA1) plays an important role in various cancers by promoting EMT, yet there are no studies on its function in endometriosis. In the present study, we found that MTA1 was highly expressed in the ectopic endometrium of endometriosis patients and that the expression of MTA1 was related to the revised American Fertility Society stage. MTA1 facilitated endometrial stroma cell proliferation, migration, and invasion by inducing EMT, and the promotion function and MTA1 expression were suppressed by resveratrol, a natural polyphenol. Moreover, we revealed that MTA1 induced EMT through interaction with ZEB2. The findings in a mouse endometriosis model further showed that MTA1 and ZEB2 were upregulated in ectopic tissues and that resveratrol inhibited the growth of ectopic lesions and expression of MTA1 and ZEB2. Taken together, we demonstrate that MTA1 is a protein that promotes EMT via interacting with ZEB2 in the pathogenesis of endometriosis, and may be a target of resveratrol.

Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis

Endometriosis is a chronic, inflammatory, hormone-dependent disease characterized by histological lesions produced by the presence of endometrial tissue outside the uterine cavity. Despite the fact that an estimated 176 million women are affected worldwide by this gynecological disorder, risk factors that cause endometriosis have not been properly defined and current treatments are not efficient. Although the interaction between diet and human health has been the focus of many studies, little information about the correlation of foods and their bioactive derivates with endometriosis is available. In this framework, Brassica crops have emerged as potential candidates for ameliorating the chronic inflammatory condition of endometriosis, due to their abundant content of health-promoting compounds such as glucosinolates and their hydrolysis products, isothiocyanates. Several inflammation-related signaling pathways have been included among the known targets of isothiocyanates, but those involving aquaporin water channels have an important role in endometriosis. Therefore, the aim of this review is to highlight the promising effects of the phytochemicals present in Brassica spp. as major candidates for inclusion in a dietary approach aiming to improve the inflammatory condition of women affected with endometriosis. This review points out the potential roles of glucosinolates and isothiocyanates from Brassicas as anti-inflammatory compounds, which might contribute to a reduction in endometriosis symptoms. In view of these promising results, further investigation of the effect of glucosinolates on chronic inflammatory diseases, either as diet coadjuvants or as therapeutic molecules, should be performed. In addition, we highlight the involvement of aquaporins in the maintenance of immune homeostasis. In brief, glucosinolates and the modulation of cellular water by aquaporins could shed light on new approaches to improve the quality of life for women with endometriosis.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

TET1 may contribute to hypoxia-induced epithelial to mesenchymal transition of endometrial epithelial cells in endometriosis

Background

Endometriosis (EMs) is a non-malignant gynecological disease, whose pathogenesis remains to be clarified. Recent studies have found that hypoxia induces epithelial-mesenchymal transition (EMT) as well as epigenetic modification in EMs. However, the relationship between EMT and demethylation modification under hypoxia status in EMs remains unknown.

Methods

The expression of N-cadherin, E-cadherin and TET1 in normal endometria, eutopic endometria and ovarian endometriomas was assessed by immunohistochemistry and immunofluorescence double staining. 5-hmC was detected by fluorescence-based ELISA kit using a specific 5-hmC antibody. Overexpression and inhibition of TET1 or hypoxia-inducible factor 2α (HIF-2α) were performed by plasmid and siRNA transfection. The expression of HIF-2α, TET1 and EMT markers in Ishikawa (ISK) cells (widely used as endometrial epithelial cells) was evaluated by western blotting. The interaction of HIF-2α and TET1 was analyzed by chromatin immunoprecipitation.

Results

Demethylation enzyme TET1 (ten-eleven translocation1) was elevated in glandular epithelium of ovarian endometrioma, along with the activation of EMT (increased expression of N-cadherin, and decreased expression of E-cadherin) and global increase of epigenetic modification marker 5-hmC(5-hydroxymethylcytosine). Besides, endometriosis lesions had more TET1 and N-cadherin co-localized cells. Further study showed that ISK cells exhibited enhanced EMT, and increased expression of TET1 and HIF-2α under hypoxic condition. Hypoxia-induced EMT was partly regulated by TET1 and HIF-2α. HIF-2α inhibition mitigated TET1 expression changes provoked by hypoxia.

Conclusions

Hypoxia induces the expression of TET1 regulated by HIF-2α, thus may promote EMT in endometriosis.

Advanced oxidation protein products change biological behaviors of rat endometrial epithelial cells by activating ERK/P38 signaling pathways

Advanced oxidation protein products (AOPPs) are a family of oxidized protein compounds and could induce oxidative stress and inflammatory lesion in various cells. The accumulation of AOPPs was associated with female reproductive diseases such as polycystic ovary syndrome (PCOS), leiomyoma and endometriosis. However, the relationship between AOPPs and endometrial cells is unclear. To explore the effects of accumulated AOPPs on endometrial cells, we treated normal rat endometrial epithelial cells (rEECs) and endometriosis model rats with AOPPs. Primary rEECs were collected from 8-week-old female Wistar rats. Increasing the amount of AOPPs in the media of rEECs enhanced rEEC proliferation and migration, and inhibited apoptosis. Moreover, AOPPs triggered the production of reactive oxygen species and nitrite along with activated ERK and P38 signal and this, in turn, led to an upregulation of proliferation and migration. With the treatment of antioxidants or the inhibitors of ERK and P38, the above effects of AOPPs on rEECs were attenuated. Additionally, in an endometriosis rat model, a similar phenomenon was observed in that the growth of endometriotic implants were promoted by AOPPs and EECs were significantly increased. This study indicated that the accumulation of AOPPs could promote rEEC proliferation and migration through ERK and P38 signal both in vivo and in vitroThis article has an associated First Person interview with the first author of the paper.

MicroRNA‑16 inhibits endometrial stromal cell migration and invasion through suppression of the inhibitor of nuclear factor‑κB kinase subunit β/nuclear factor‑κB pathway

Accumulating evidence has demonstrated that endometrial stromal cells (ESCs) are responsible for the pathogenesis of endometriosis (Ems), which is characterized by the presence of functional endometrial-like tissues outside the uterine cavity. Abnormal expression of microRNAs (miRNAs) in ESCs may be implicated in the etiology of Ems; however, the exact mechanisms have yet to be fully elucidated. The aim of the present study was to investigate the effects of miRNAs on ESCs and the underlying mechanisms. Using a microarray assay, microRNA-16 (miR-16) was found to be significantly downregulated in the ectopic endometrial tissues in patients with Ems, compared with that in eutopic endometrial tissues. Overexpression of miR-16 significantly suppressed the migration and invasion of ESCs, whereas miR-16 inhibition exerted the opposite effects. Furthermore, dual luciferase reporter assay demonstrated that miR-16 directly targeted the inhibitor of nuclear factor (NF)-κB kinase subunit β (IKKβ) and suppressed its translation. It was observed that the expression of IKKβ was upregulated and inversely correlated with miR-16 levels in the ectopic endometrial tissues in patients with Ems. Additionally, knockdown of IKKβ by si-IKKβ mimicked the effects of miR-16 overexpression on ESCs, while the promoting effects of IKKβ overexpression on the migration and invasion of ESCs were attenuated by miR-16 overexpression. Finally, miR-16 inhibited the activation of the NF-κB pathway by targeting IKKβ. Collectively, these results demonstrated that miR-16 may suppress Ems by inhibiting the IKKβ/NF-κB pathway, suggesting that miR-16 may be a useful target in the treatment of Ems.

Elevated serum interleukin-32 levels in patients with endometriosis: A cross-sectional study

PROBLEM

Recently, interleukin (IL)-32 has been suggested to be involved in the pathogenesis of endometriosis. The aim of this study was to investigate whether serum IL-32 level might be used as a biomarker for diagnosis of endometriosis.

METHOD OF STUDY

We recruited the serum samples of 50 patients with histologically confirmed endometriosis and 35 controls. Enzyme-linked immunosorbent assay was used to analyze the serum IL-32, IL-6, IL-10, tumour necrosis factor (TNF)-α, IL-1β, and CA-125 levels in patients with and without the disease and the diagnostic potentials of the cytokines were assessed using receiver operating characteristic curve and the area under the curve (AUC).

RESULTS

Among evaluated cytokines, only serum IL-32 levels showed significant differences between patients with and without endometriosis (1111.24 ± 149.59 vs 631.10 ± 120.23 ng/mL, P = 0.018, respectively). When the diagnostic power of serum IL-32 was evaluated, the AUC was 0.638 (95% confidence interval (CI): 0.521-0.766, P = 0.031). When serum IL-32 levels were combined with serum CA-125 levels, the AUC was increased to 0.749 (95% CI: 0.640-0.858, P < 0.001) with sensitivity and specificity of 60.0% and 82.9% at cutoff value of 0.640, which led to detect 25 more cases of endometriosis than the use of serum CA 125 with the cutoff value of 35 IU/mL (36/50 vs 11/50, P < 0.001) without sacrificing the specificity of the marker.

CONCLUSION

Serum IL-32 levels are elevated in patients with endometriosis, and with combination of serum CA-125 levels, it may serve as a potential biomarker for endometriosis.

Naringenin ameliorates progression of endometriosis by modulating Nrf2/Keap1/HO1 axis and inducing apoptosis in rats

Endometriosis is mainly characterized by the presence of endometrial tissue exterior to the uterus, however, the exact pathophysiology of this disease still remains uncertain. Moreover, the incidence significantly contributes to infertility among women and hence, a novel treatment for endometriosis is widely investigated. Naringenin is a plant-derived flavonoid having anti-proliferative, anti-inflammatory, and anti-angiogenic properties in chronic and metabolic diseases. The current study was planned with an objective to demonstrate the anti-endometriotic therapeutic potential of naringenin in rats and to examine its impact on various cellular aspects with a view to define the mechanism involved. The endometrial lesion volumes, weight, serum TNF-α level and the histopathologic scores were significantly reduced in the naringenin- treated group as compared to the endometriotic control group. Naringenin ameliorated the expression of prognostic markers (TAK1, PAK1, VEGF and PCNA) involved in development and progression of endometriotic cells. Naringenin caused dose-dependent loss of mitochondrial membrane potential, induced apoptosis and inhibited proliferation in these cells. Further, a significant increase in level of Nrf2 and its downstream molecules (NQO1, HO-1) was found in endometriotic lesion, with a subsequent decrease in its repressor molecule Keap-1. Naringenin significantly modulated the expression of Nrf2 and its effector molecules downstream. It also inhibited the invasion of endometrial cells by reducing the expression of MMP-2 and MMP-9 in in-vitro primary culture. We conclude that naringenin may have a therapeutic potential in the treatment of endometriosis via induction of ROS-mediated apoptosis and its anti-invasive effects.

IL-37 affects the occurrence and development of endometriosis by regulating the biological behavior of endometrial stromal cells through multiple signaling pathways

Endometriosis (EMs) is a chronic inflammatory condition. Interleukin (IL)-37 is a member of the IL-1 family and an anti-inflammatory cytokine. This study aimed to evaluate the possible role of IL-37 in the EMs pathogenesis. We investigated the in vivo effect of IL-37 on EMs by injection with recombinant human IL-37 (rhIL-37) into EMs mice. Furthermore, we evaluated the in vitro effects of IL-37 on proliferation, adhesion, migration and invasiveness of endometrial stromal cells (ESCs), and explored whether Wnt/β-catenin and mitogen-activated protein kinase (MAPK) pathways were involved in this process. In cultured ESCs, IL-37 overexpression significantly suppressed both protein and mRNA expression of the inflammation-associated cytokines, including IL-1β, IL-6, IL-10 and tumor necrosis factor (TNF-α). Furthermore, IL-37 overexpression significantly inhibited ESCs proliferation, adhesion, migration, invasion and the activity of matrix metalloproteinase (MMP)-2 and MMP-9. In contrast, knockdown of IL-37 exerted the opposite effects. Importantly, the IL-37-mediated action in ESCs was through inactivation of Wnt/β-catenin, p38 MAPK, extracellular signal-related kinases MAPK and c-Jun N-terminal kinase MAPK pathways. Moreover, EMs mice treated with rhIL-37 showed the decreased endometriotic-like lesion size and lesion weight, lower expression of IL-1β, IL-6, IL-10, TNF-α, vascular endothelial growth factor (VEGF), soluble intercellular adhesion molecule-I (ICAM-I) and MMP-2/9 activity in peritoneal fluid compared with the wide type (WT) EMs mice. These findings suggest that IL-37 suppresses cell proliferation, adhesion, migration and invasion of human ESCs through multiple signaling pathways, thereby affecting the occurrence and development of EMs.

Overexpression of TGF-β enhances the migration and invasive ability of ectopic endometrial cells via ERK/MAPK signaling pathway

Endometriosis is a common gynecological disease with manifestations of endometrial-like tissue outside the uterus. Transforming growth factor-β (TGF-β) is known to facilitate a series of biological events in many cells, including migration. However, the roles of TGF-β in endometriosis still remain largely unknown. The aim of the present study was to discover the role of TGF-β1 in endometriosis development and progression and its associated mechanisms. It was demonstrated that the expression of TGF-β1 was significantly elevated in endometriosis in comparison with that in normal tissue. Overexpression of TGF-β increased the proliferation and upregulated proliferating cell nuclear antigen and cyclin D1 in endometrial stromal cells (ESCs). Furthermore, TGF-β overexpression also triggered a series of biological events occurring in ESCs, including cell migration and invasion, and activated the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling pathway. The inhibition of the ERK/MAPK pathway reversed the previous effects of TGF-β overexpression. Collectively, the present results indicate that overexpression of TGF-β enhances the migration and invasion of ectopic ESCs via the ERK/MAPK signaling pathway, providing theoretical evidence for the development of new treatment methods targeting the TGF-β-ERK/MAPK signaling pathway for prophylaxis of endometriosis.