Endometriosis and Stem Cell Trafficking

Evaluation of Safety and Efficacy of Amniotic Mesenchymal Stem Cells for POI in Animals

The efficacy of human amniotic mesenchymal stem cell (hAMSC) ovarian injection in improving ovarian function in primary ovarian insufficiency (POI) patients has been shown in some reports. However, the safety and efficacy of hAMSC vein injection remains unclear. In this study, we evaluated the safety and efficacy of hAMSC intravenous injection in cynomolgus macaques and SD rats and provided evidence for clinical trials. The hAMSCs were transplanted three times in SD rats at low, medium, and high doses. The animal behavior and biochemical and biophysical parameters were routinely monitored on a 2-month period posttransplantation, and histopathologic examinations were also performed. Experiments on the acute toxicity, allergy test, and hemolysis test showed that hAMSCs possess good biocompatibility. Our results showed that the maximum tolerated dose of hAMSCs in SD rats was 4.0 × 107 cells/kg. The maximum safe dose with three injections of hAMSCs in SD rats was 5.0 × 106 cells/kg. In addition, the results demonstrated that hAMSCs may restore POI rat ovarian function after two injections of 2.5 × 106 cells/kg or 5.0 × 106 cells/kg, which improved the disturbed estrous cycle, hormone levels, and ovarian lesions induced by pZP3. In conclusion, the preclinical results suggested that the transplantation of hAMSCs may be safe and efficacious for SD rats at doses of 5.0 × 106 cells/kg and lower.

Digestive system deep infiltrating endometriosis: What do we know

Digestive system infiltrating endometriosis (DSIE) is an uncommon form of endometriosis in the digestive system. DSIE often occurs in the intestines (especially the sigmoid rectum), liver, gallbladder and pancreas. Clinically, DSIE presents with the same symptoms as endometriosis, including cyclic pain, bleeding and infertility, in addition to specific biliary/intestinal obstruction and gastrointestinal bleeding. Compared to general endometriosis, DSIE has unique biological behaviour and pathophysiological mechanisms. Most DSIEs are deep invasive endometrioses, characterized by metastasis to the lymph nodes and lymphatic vessels, angiogenesis, peripheral nerve recruitment, fibrosis and invasion of surrounding tissues. DSIE-related peripheral angiogenesis is divided into three patterns: angiogenesis, vasculogenesis and inosculation. These patterns are regulated by interactions between multiple hypoxia-hormone cytokines. The nerve growth factors regulate the extensive neurofibril recruitment in DSIE lesions, which accounts for severe symptoms of deep pain. They are also associated with fibrosis and the aggressiveness of DSIE. Cyclic changes in DSIE lesions, recurrent inflammation and oxidative stress promote repeated tissue injury and repair (ReTIAR) mechanisms in the lesions, accelerating fibril formation and cancer-related mutations. Similar to malignant tumours, DSIE can also exhibit aggressiveness derived from collective cell migration mediated by E-cadherin and N-cadherin. This often makes DSIE misdiagnosed as a malignant tumour of the digestive system in clinical practice. In addition to surgery, novel treatments are urgently required to effectively eradicate this lesion.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.

Endometriosis in the era of precision medicine and impact on sexual and reproductive health across the lifespan and in diverse populations

Endometriosis is a common estrogen-dependent disorder wherein uterine lining tissue (endometrium) is found mainly in the pelvis where it causes inflammation, chronic pelvic pain, pain with intercourse and menses, and infertility. Recent evidence also supports a systemic inflammatory component that underlies associated co-morbidities, e.g., migraines and cardiovascular and autoimmune diseases. Genetics and environment contribute significantly to disease risk, and with the explosion of omics technologies, underlying mechanisms of symptoms are increasingly being elucidated, although novel and effective therapeutics for pain and infertility have lagged behind these advances. Moreover, there are stark disparities in diagnosis, access to care, and treatment among persons of color and transgender/nonbinary identity, socioeconomically disadvantaged populations, and adolescents, and a disturbing low awareness among health care providers, policymakers, and the lay public about endometriosis, which, if left undiagnosed and under-treated can lead to significant fibrosis, infertility, depression, and markedly diminished quality of life. This review summarizes endometriosis epidemiology, compelling evidence for its pathogenesis, mechanisms underlying its pathophysiology in the age of precision medicine, recent biomarker discovery, novel therapeutic approaches, and issues around reproductive justice for marginalized populations with this disorder spanning the past 100 years. As we enter the next revolution in health care and biomedical research, with rich molecular and clinical datasets, single-cell omics, and population-level data, endometriosis is well positioned to benefit from data-driven research leveraging computational and artificial intelligence approaches integrating data and predicting disease risk, diagnosis, response to medical and surgical therapies, and prognosis for recurrence.

Therapeutic restoration of female reproductive and endocrine dysfunction using stem cells

Millions of women worldwide suffer from infertility associated with gynecologic disorders such as premature ovarian insufficiency, polycystic ovary syndrome, Asherman syndrome, endometriosis, preeclampsia, and fallopian tube obstruction. These disorders can lead to infertility and thereby affect the quality of life of the infertile couple because of their psychological impact and significant costs. In recent years, stem cell therapy has emerged as a therapeutic approach to repair or replace damaged tissues or organs. This review describes the recent development as well as the underlying mechanisms of stem cell therapy for a variety of female reproductive diseases, offering us new therapeutic options for the treatment of female reproductive and endocrine dysfunction.

Myometrial-derived CXCL12 promotes lipopolysaccharide induced preterm labour by regulating macrophage migration, polarization and function in mice

Preterm birth is a major contributor to neonatal mortality and morbidity. Infection results in elevation of inflammation-related cytokines followed by infiltration of immune cells into gestational tissue. CXCL12 levels are elevated in preterm birth indicating it may have a role in preterm labour (PTL); however, the pathophysiological correlations between CXCL12/CXCR4 signalling and premature labour are poorly understood. In this study, PTL was induced using lipopolysaccharide (LPS) in a murine model. LPS induced CXCL12 RNA and protein levels significantly and specifically in myometrium compared with controls (3-fold and 3.5-fold respectively). Highest levels were found just before the start of labour. LPS also enhanced the infiltration of neutrophils, macrophages and T cells, and induced macrophage M1 polarization. In vitro studies showed that condition medium from LPS-treated primary smooth muscle cells (SMC) induced macrophage migration, M1 polarization and upregulated inflammation-related cytokines such as interleukin (IL)-1, IL-6 and tumor necrosis factor alpha (TNF-α). AMD3100 treatment in pregnant mice led to a significant decrease in the rate of PTL (70%), prolonged pregnancy duration and suppressed macrophage infiltration into gestation tissue by 2.5-fold. Further, in-vitro treatment of SMC by AMD3100 suppressed the macrophage migration, decreased polarization and downregulated IL-1, IL-6 and TNF-α expression. LPS treatment in pregnant mice induced PTL by increasing myometrial CXCL12, which recruits immune cells that in turn produce inflammation-related cytokines. These effects stimulated by LPS were completely reversed by AMD3100 through blocking of CXCL12/CXCR4 signalling. Thus, the CXCL12/CXCR4 axis presents an excellent target for preventing infection and inflammation-related PTL.

[Mystery of endometriosis - catamenial pneumothorax]

The review is devoted to clinical picture, main theories of pathogenesis, traditional and innovative methods of diagnosis and surgical treatment of catamenial pneumothorax. Currently, clinicians prefer magnetic resonance imaging and thoracoscopy for diagnosis of this disease. Various researchers are actively searching for laboratory diagnostic methods that can confirm endometrioid nature of pneumothorax. Treatment and prevention of catamenial pneumothorax are a controversial issue depending both clinical picture and preferences of the attending physician. Currently, the majority of authors believe that hormonal therapy combined with diaphragm resection ensures optimal anti-relapse effect in patients with thoracic endometriosis.

Genomic Evidence Supports the Recognition of Endometriosis as an Inflammatory Systemic Disease and Reveals Disease-Specific Therapeutic Potentials of Targeting Neutrophil Degranulation

Background

Endometriosis, classically viewed as a localized disease, is increasingly recognized as a systemic disease with multi-organ effects. This disease is highlighted by systemic inflammation in affected organs and by high comorbidity with immune-mediated diseases.

Results

We provide genomic evidence to support the recognition of endometriosis as an inflammatory systemic disease. This was achieved through our genomics-led target prioritization, called ‘END’, that leverages the value of multi-layered genomic datasets (including genome-wide associations in disease, regulatory genomics, and protein interactome). Our prioritization recovered existing proof-of-concept therapeutic targeting in endometriosis and outperformed competing prioritization approaches (Open Targets and Naïve prioritization). Target genes at the leading prioritization revealed molecular hallmarks (and possibly the cellular basis as well) that are consistent with systemic disease manifestations. Pathway crosstalk-based attack analysis identified the critical gene AKT1. In the context of this gene, we further identified genes that are already targeted by licensed medications in other diseases, such as ESR1. Such analysis was supported by current interests targeting the PI3K/AKT/mTOR pathway in endometriosis and by the fact that therapeutic agents targeting ESR1 are now under active clinical trials in disease. The construction of cross-disease prioritization map enabled the identification of shared and distinct targets between endometriosis and immune-mediated diseases. Shared target genes identified opportunities for repurposing existing immunomodulators, particularly disease-modifying anti-rheumatic drugs (such as TNF, IL6 and IL6R blockades, and JAK inhibitors). Genes highly prioritized only in endometriosis revealed disease-specific therapeutic potentials of targeting neutrophil degranulation – the exocytosis that can facilitate metastasis-like spread to distant organs causing inflammatory-like microenvironments.

Conclusion

Improved target prioritization, along with an atlas of in silico predicted targets and repurposed drugs (available at https://23verse.github.io/end), provides genomic insights into endometriosis, reveals disease-specific therapeutic potentials, and expands the existing theories on the origin of disease.

Ribosome Biogenesis Serves as a Therapeutic Target for Treating Endometriosis and the Associated Complications

Ribosome biogenesis is a cellular process critical for protein homeostasis during cell growth and multiplication. Our previous study confirmed up-regulation of ribosome biogenesis during endometriosis progression and malignant transition, thus anti-ribosome biogenesis may be effective for treating endometriosis and the associated complications. A mouse model with human endometriosis features was established and treated with three different drugs that can block ribosome biogenesis, including inhibitors against mTOR/PI3K (GSK2126458) and RNA polymerase I (CX5461 and BMH21). The average lesion numbers and disease frequencies were significantly reduced in treated mice as compared to controls treated with vehicle. Flow cytometry analyses confirmed the reduction of small peritoneal macrophage and neutrophil populations with increased large versus small macrophage ratios, suggesting inflammation suppression by drug treatments. Lesions in treated mice also showed lower nerve fiber density which can support the finding of pain-relief by behavioral studies. Our study therefore suggested ribosome biogenesis as a potential therapeutic target for treating endometriosis.

Expression levels of MCP-1, HGF, and IGF-1 in endometriotic patients compared with non-endometriotic controls

BACKGROUND

To study the concentrations of monocyte chemoattractant protein-1 (MCP-1), hepatocyte growth factor (HGF), and insulin-like growth factor-1 (IGF-1) in peritoneal fluid (PF) and serum, and to evaluate their expressions by PF and peripheral blood mononuclear cells (PFMCs and PBMCs, respectively), and ectopic and eutopic endometrial stromal cells of patients with endometriosis (EESCs and EuESCs, respectively) compared with controls.

METHODS

The concentrations of mentioned cytokines in serum and PF, as well as their expression in PBMCs, PFMCs, EuESCs and EESCs from endometriosis patients and controls were assessed.

RESULTS

The levels of MCP-1, HGF, and IGF-1 in serum and PF in women with endometriosis were significantly higher than the controls (P < 0.05-P < 0.001). Gene expression of MCP-1 and IGF-1 in the PFMCs, PBMCs and EESCs also showed an increased level compared to controls (P < 0.05-P < 0.01). The protein expression of MCP-1 and IGF-1 by PFMCs was statistically higher in endometriotic women (P < 0.05 and P < 0.01, respectively). The gene and protein expression of HGF in PFMCs and its gene expression by EESCs were significantly higher in endometriotic women compared to controls (P < 0.05-P < 0.01).

CONCLUSIONS

The higher concentrations of mentioned cytokines in serum and PF and their higher expression by PFMCs and EESCs in endometriosis patients may contribute to the development of endometriosis.

Can TSH level and premenstrual spotting constitute a non-invasive marker for the diagnosis of endometriosis?

Background

To date, there is no reliable non-invasive marker for the early detection and diagnosis of endometriosis available possibly resulting in a delayed diagnosis and consequently an unnecessary long ordeal for the individual woman. Therefore, the primary objective of the current study was to evaluate whether the combination of a thyroid-stimulating hormone (TSH) level > 2.5 µlU/ml and premenstrual spotting could serve as non-invasive markers of endometriosis. A secondary objective was to determine whether typical symptoms of endometriosis like dysmenorrhea and/or dyspareunia could increase the diagnostic reliability.

Methods

We conducted a retrospective, case–control study with 167 female patients at the Department of OB/GYN and REI (UniKiD) of the medical center of the University of Düsseldorf, between January 2015 and December 2016. 107 women with surgically confirmed endometriosis were compared to 60 without endometriosis (controls). To evaluate the diagnostic accuracy, we considered sensitivity, specificity and predictive values. In order to assess the association between the non-invasive markers and endometriosis an odds ratio (OR) with a 95% confidence interval was calculated.

Results

In our cohort, diagnosis of endometriosis with non-invasive markers according to their sensitivity yielded the following ranking: increased TSH level, premenstrual spotting, combination of both previous parameters, addition of dysmenorrhea, addition of dyspareunia and combination of all parameters.

Conclusion

The existence of endometriosis should be taken into consideration when a patient suffers from thyroid dysfunction and premenstrual spotting. Apart from an increased TSH level, the presence of premenstrual spotting underlines the possible diagnosis of endometriosis with non-invasive markers and therefore, the patient´s history needs to be taken into account carefully.

Trial registration The retrospective study was approved by the Ethics Committee of the medical faculty of the Heinrich-Heine University, Düsseldorf, Germany, Registration number Düsseldorf: 5371R (approved: April 04th, 2016). Since the design of the study was retrospective no written informed consent was necessary.

Endometriosis stem cell sources and potential therapeutic targets: literature review and bioinformatics analysis

The stem cell origin theory of endometriosis (EMS) is a significant area of new research but the sources of this have yet to be adequately summarized. Existing treatments for EMS are commonly associated with a high recurrence rate; consequently, there is an urgent need to develop new therapeutic measures for the future treatment of this disease from the view of stem cells and gene therapy. Recently, we described the evidence for the potential sources of EMS stem cells and other key molecules participating in the establishment of lesions, and predict the miRNAs that target these key genes via bioinformatics analysis for further research. This review highlights the origin of EMS stem cells and potential therapy targets.

Characterization of Bone Marrow Progenitor Cell Uterine Engraftment and Transdifferentiation

Regeneration of uterine tissue is an important physiological process that allows for maintenance of fertility after menstruation or pregnancy. Stem cells, especially bone marrow-derived progenitors, play a crucial role in this regeneration. Here, we describe the conversion of DsRed-labeled bone marrow-derived stem cells (BMDSCs) into specific uterine cell types with both differentiated and stem cell properties in a murine model. Irradiated recipient mice underwent bone marrow transplant with DsRed-expressing BMDSCs and were analyzed for engraftment and differentiation of BMDSCs in the uterus after 2, 6, and 16 weeks. Microarray and qRT-PCR analysis of bone marrow-derived cells obtained from the uterus identified upregulation of markers indicating a contribution to the population of stromal, epithelial, endothelial, and muscle cells, followed by a late expansion of epithelial cells. Other engrafted BMDSCs in the uterus were characterized by the continued expression of specific stem cell markers such as Sca1, CD44, CD146, and CD133, indicating the some BMDSCs remain as progenitor cells. BMDSCs established in recipient mice by the 16th week were sorted by flow cytometry using DsRed and progenitor cell surface markers. In vitro cell culture studies showed that single sorted cells had clonogenic properties. These results suggest that engrafted BMDSCs in the uterus had both a stem cell component and were able to differentiate into several differentiated cell types. The pool of progenitor cells likely continues to supply differentiated uterine cells in the process of uterine repair and remodeling.

Endometrial stem/progenitor cells and their roles in immunity, clinical application, and endometriosis

Endometrial stem/progenitor cells have been proved to exist in periodically regenerated female endometrium and can be divided into three categories: endometrial epithelial stem/progenitor cells, CD140b+CD146+ or SUSD2+ endometrial mesenchymal stem cells (eMSCs), and side population cells (SPs). Endometrial stem/progenitor cells in the menstruation blood are defined as menstrual stem cells (MenSCs). Due to their abundant sources, excellent proliferation, and autotransplantation capabilities, MenSCs are ideal candidates for cell-based therapy in regenerative medicine, inflammation, and immune-related diseases. Endometrial stem/progenitor cells also participate in the occurrence and development of endometriosis by entering the pelvic cavity from retrograde menstruation and becoming overreactive under certain conditions to form new glands and stroma through clonal expansion. Additionally, the limited bone marrow mesenchymal stem cells (BMDSCs) in blood circulation can be recruited and infiltrated into the lesion sites, leading to the establishment of deep invasive endometriosis. On the other hand, cell derived from endometriosis may also enter the blood circulation to form circulating endometrial cells (CECs) with stem cell-like properties, and to migrate and implant into distant tissues. In this manuscript, by reviewing the available literature, we outlined the characteristics of endometrial stem/progenitor cells and summarized their roles in immunoregulation, regenerative medicine, and endometriosis, through which to provide some novel therapeutic strategies for reproductive and cancerous diseases.

Niclosamide suppresses macrophage-induced inflammation in endometriosis†

Endometriosis is a common gynecological disease, which causes chronic pelvic pain and infertility in women of reproductive age. Due to limited efficacy of current treatment options, a critical need exists to develop new and effective treatments for endometriosis. Niclosamide is an efficacious and FDA-approved drug for the treatment of helminthosis in humans that has been used for decades. We have reported that niclosamide reduces growth and progression of endometriosis-like lesions via targeting STAT3 and NFĸB signaling in a mouse model of endometriosis. To examine the effects of niclosamide on macrophage-induced inflammation in endometriosis, a total of 29 stage III-IV endometrioma samples were used to isolate human endometriotic stromal cells (hESCs). M1 or M2 macrophages were isolated and differentiated from fresh human peripheral blood samples. Then, hESCs were cultured in conditioned media (CM) from macrophages with/without niclosamide. Niclosamide dose dependently reduced cell viability and the activity of STAT3 and NFκB signaling in hESCs. While macrophage CM stimulated cell viability in hESCs, niclosamide inhibited this stimulation. Macrophage CM stimulated the secretion of proinflammatory cytokines and chemokines from hESCs. Most of these secreted factors were inhibited by niclosamide. These results indicate that niclosamide is able to reduce macrophage-induced cell viability and cytokine/chemokine secretion in hESCs by inhibiting inflammatory mechanisms via STAT3 and/or NFκB signaling.

Circulating miRNAs Related to Epithelial-Mesenchymal Transitions (EMT) as the New Molecular Markers in Endometriosis

Endometriosis is a chronic gynecological disease defined by the presence of endometrial-like tissue found outside the uterus, most commonly in the peritoneal cavity. Endometriosis lesions are heterogenous but usually contain endometrial stromal cells and epithelial glands, immune cell infiltrates and are vascularized and innervated by nerves. The complex etiopathogenesis and heterogenity of the clinical symptoms, as well as the lack of a specific non-invasive diagnostic biomarkers, underline the need for more advanced diagnostic tools. Unfortunately, the contribution of environmental, hormonal and immunological factors in the disease etiology is insufficient, and the contribution of genetic/epigenetic factors is still fragmentary. Therefore, there is a need for more focused study on the molecular mechanisms of endometriosis and non-invasive diagnostic monitoring systems. MicroRNAs (miRNAs) demonstrate high stability and tissue specificity and play a significant role in modulating a range of molecular pathways, and hence may be suitable diagnostic biomarkers for the origin and development of endometriosis. Of these, the most frequently studied are those related to endometriosis, including those involved in epithelial–mesenchymal transition (EMT), whose expression is altered in plasma or endometriotic lesion biopsies; however, the results are ambiguous. Specific miRNAs expressed in endometriosis may serve as diagnostics markers with prognostic value, and they have been proposed as molecular targets for treatment. The aim of this review is to present selected miRNAs associated with EMT known to have experimentally confirmed significance, and discuss their utility as biomarkers in endometriosis.

Malignant transformation of hepatic endometriosis: a case report and literature review

Background

Extrapelvic endometriosis is defined as the presence of ectopic endometrial tissue in structures outside the pelvis. Although extra-pelvic endometriosis is generally considered benign conditions, malignant potential within endometriotic foci occurs even after definitive surgery. Malignant transformation of hepatic endometriosis is extremely rare. Preoperative diagnosis of this cancer is difficult, and no guidelines on the optimal management currently exist. Here, we present a case report of malignant transformation of hepatic endometriosis and a brief literature review to highlight the current knowledge of the prevalence, clinical features, diagnosis, and management of this condition.

Case presentation

A 50-year-old woman with a 2-year duration of progressive right upper quadrant abdominal pain was admitted to the hospital. She underwent hysterectomy and bilateral salpingo-oophorectomy for benign conditions 4 years prior. Tumor markers demonstrated elevated carbohydrate antigen (CA)-199 112U/mL (normal range: 0–35U/mL) only. Radiological imaging suggested the presence of a 10.7 × 7.7-cm mass in the right lobe of the liver extending to the diaphragm. The intraoperative frozen sections suggested malignant tumor. Right hepatectomy with infiltrating diaphragm resection was performed. The final pathology with immunohistochemistry staining confirmed endometrioid adenocarcinoma in the liver originating from preexisting hepatic endometriosis. After the multidisciplinary team meeting, the consensus was surgery followed by adjuvant chemotherapy. To our knowledge, this is the first case of Chinese woman of a malignant liver tumor originating from endometriosis ever reported by reviewing the current English medical literature.

Conclusion

Though rare, extrapelvic endometriosis-associated cancers should be considered as differentiated diagnosis even after hysterectomy and bilateral salpingo-oophorectomy. This case highlights the importance of collaborative efforts across multiple disciplines for accurate diagnosis and appropriate treatment of malignant transformation of hepatic endometriosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-021-01366-6.

The Effects of Endometriosis on Ovarian Functions

Infertility is a main manifestation of endometriosis, though the exact pathogenesis of endometriosis-associated infertility remains unclear. Compromised ovarian functions may be one of the causes of endometriosis related infertility. The ovarian function can be classified into three basic elements, (1) production of ovarian hormones, (2) maintenance of follicular development until ovulation, and (3) reservoir of dormant oocytes (ovarian reserve). The effects of endometriosis on ovarian hormone production and follicular development are inconclusive. Ovarian endometrioma is common phonotype of endometriosis. Development of endometrioma per se may affect ovarian reserve. Surgery for endometriomas further diminish ovarian reserve, especially women with bilateral involvement. Early intervention with surgery and/or medical treatment may be beneficial, though firm evidence is lacking. When surgery is chosen in women at reproductive age, specific techniques that spare ovarian function should be considered.

Endometriosis Cell Proliferation Induced by Bone Marrow Mesenchymal Stem Cells

Endometriosis is an estrogen-dependent gynecological disorder that affects 10% of reproductive-aged women and causes pelvic pain and infertility. Bone marrow-derived stem cells (BMDCs) are known to engraft endometriosis in association with lesion growth; however, they do not undergo significant clonal expansion. The indirect effects of BMDCs on endometriosis growth and cell proliferation are not well characterized. Here, we demonstrate that BMDCs' co-culture increased endometrial stromal cell proliferation. In vitro studies using endometrial cells showed that BMDCs increased cell proliferation and activation of CDK1 in both an endometriosis cell line and primary endometrial stromal cells from women with endometriosis, however not in normal endometrial cells. In vivo studies using a mouse model of endometriosis showed increased CDK1+ expression associated with engrafted GFP + BMDCs. These results suggest that endometrial cell proliferation is induced by stem cell-derived trophic factors leading to the growth of endometriotic lesions. Targeting the specific signaling molecules secreted by BMDC may lead to novel therapeutic strategies for controlling cell proliferation in endometriosis.

Endometriosis stromal cells induce bone marrow mesenchymal stem cell differentiation and PD-1 expression through paracrine signaling

Endometriosis is an estrogen-dependent, inflammatory gynecological disorder characterized by the growth of endometrial cells in lesions outside the uterus. Bone marrow-derived cells (BMDCs) engraft lesions and increase lesion size. Do endometriosis cells regulate differentiation of engrafted BMDCs in the pathogenesis and growth of endometriosis? Here, we report endometriosis derived stromal cells promote the differentiation of BMDCs to stromal, epithelial and leukocyte cell fates through paracrine signaling. In-vitro studies demonstrated that both mRNA and protein levels of vimentin, cytokeratin and PD-1 were significantly increased in BMDCs cocultured with stromal cells from endometriosis (ENDO) patients compared to stromal cells from normal endometrium (CNTL). Increased expression of PD-1 has been reported in malignancy where it promotes T cell quiescence and immune tolerance. Increased PD-1 was also confirmed in-vivo where we showed that PD-1 expression was induced in BMDCs engrafted into endometriotic lesions in a murine model of endometriosis. AMD3100, an antagonist for CXCR4 receptor inhibited PD-1 expression in BMDCs suggesting that PD-1 induction requires CXCL12. These results suggest that endometriosis stimulated BMDC differentiation through paracrine signaling and increased T cell PD-1 expression. Increased PD-1 expression may be one mechanism by which endometriosis avoids immune surveillance.

Pathogenesis of bowel endometriosis

The pathogenesis of bowel endometriosis is multifactorial. There is a predilection for disease of the rectum/sigmoid colon because refluxed endometrium is more likely to settle in the pouch of Douglas and its movement is delimited by the sigmoid colon, in addition to the close proximity of the rectum/sigmoid to posterior extrinsic uterine adenomyosis and to ovarian endometriomas. Once situated, deep bowel endometriosis has features of invasion, angiogenesis, and fibrosis (repeated tissue injury and repair), with emerging research on oxidative stress and the microbiome. Furthermore, deep bowel endometriosis is associated with neurogenesis and/or the recruitment of local nerve fibers and is capable of invading existing nerves, which in turn may also promote fibrosis. Recently, somatic cancer driver mutations (e.g., in KRAS) were identified in deep bowel endometriosis, which may play a role in the genetic/epigenetic theory of endometriosis. In the future, it is possible that bowel endometriosis could be classified based on molecular features.

Endometriotic inflammatory microenvironment induced by macrophages can be targeted by niclosamide†

Endometriosis causes severe chronic pelvic pain and infertility. We have recently reported that niclosamide treatment reduces growth and progression of endometriosis-like lesions and inflammatory signaling (NF${\rm \small K}$B and STAT3) in a mouse model. In the present study, we examined further inhibitory mechanisms by which niclosamide affects endometriotic lesions using an endometriotic epithelial cell line, 12Z, and macrophages differentiated from a monocytic THP-1 cell line. Niclosamide dose dependently reduced 12Z viability, reduced STAT3 and NF${\rm \small K}$B activity, and increased both cleaved caspase-3 and cleaved PARP. To model the inflammatory microenvironment in endometriotic lesions, we exposed 12Z cells to macrophage conditioned media (CM). Macrophages were differentiated from THP-1 cells using 12-O-tetradecanoylphorbol-13-acetate as M0, and then M0 macrophages were polarized into M1 or M2 using LPS/IFNγ or IL4/IL13, respectively. Conditioned media from M0, M1, or M2 cultures increased 12Z viability. This effect was blocked by niclosamide, and cell viability returned to that of CM from cells treated with niclosamide alone. To assess proteins targeted by niclosamide in 12Z cells, CM from 12Z cells cultured with M0, M1, or M2 with/without niclosamide were analyzed by cytokine/chemokine protein array kits. Conditioned media from M0, M1, and/or M2 stimulated the secretion of cytokines/chemokines from 12Z cells. Production of most of these secreted cytokines/chemokines in 12Z cells was inhibited by niclosamide. Knockdown of each gene in 12Z cells using siRNA resulted in reduced cell viability. These results indicate that niclosamide can inhibit the inflammatory factors in endometriotic epithelial cells stimulated by macrophages by targeting STAT3 and/or NF${\rm \small K}$B signaling.

Biomarkers for the Noninvasive Diagnosis of Endometriosis: State of the Art and Future Perspectives

BACKGROUND

Early and accurate diagnosis of endometriosis is crucial for the management of this benign, yet debilitating pathology. Despite the advances of modern medicine, there is no common ground regarding the pathophysiology of this disease as it continues to affect the quality of life of millions of women of reproductive age. The lack of specific symptoms often determines a belated diagnosis. The gold standard remains invasive, surgery followed by a histopathological exam. A biomarker or a panel of biomarkers is easy to measure, usually noninvasive, and could benefit the clinician in both diagnosing and monitoring the treatment response. Several studies have advanced the idea of biomarkers for endometriosis, thereby circumventing unnecessary invasive techniques. Our paper aims at harmonizing the results of these studies in the search of promising perspectives on early diagnosis.

METHODS

We selected the papers from Google Academic, PubMed, and CrossRef and reviewed recent articles from the literature, aiming to evaluate the effectiveness of various putative serum and urinary biomarkers for endometriosis.

RESULTS

The majority of studies focused on a panel of biomarkers, rather than a single biomarker and were unable to identify a single biomolecule or a panel of biomarkers with sufficient specificity and sensitivity in endometriosis.

CONCLUSION

Noninvasive biomarkers, proteomics, genomics, and miRNA microarray may aid the diagnosis, but further research on larger datasets along with a better understanding of the pathophysiologic mechanisms are needed.

CXCR4 or CXCR7 antagonists treat endometriosis by reducing bone marrow cell trafficking

Adult stem cells have a major role in endometrial physiology, including remodelling and repair. However, they also have a critical role in the development and progression of endometriosis. Bone marrow-derived stem cells engraft eutopic endometrium and endometriotic lesions, differentiating to both stromal and epithelial cell fates. Using a mouse bone marrow transplantation model, we show that bone marrow-derived cells engrafting endometriosis express CXCR4 and CXCR7. Targeting either receptor by the administration of small molecule receptor antagonists AMD3100 or CCX771, respectively, reduced BM-derived stem cell recruitment into endometriosis implants. Endometriosis lesion size was decreased compared to vehicle controls after treatment with each antagonist in both an early growth and established lesion treatment model. Endometriosis lesion size was not effected when the local effects of CXCL12 were abrogated using uterine-specific CXCL12 null mice, suggesting an effect primarily on bone marrow cell migration rather than a direct endometrial effect. Antagonist treatment also decreased hallmarks of endometriosis physiopathology such as pro-inflammatory cytokine production and vascularization. CXCR4 and CXCR7 antagonists are potential novel, non-hormonal therapies for endometriosis.

Expression of ALDH1A Isozymes in Human Endometrium with and without Endometriosis and in Ovarian Endometrioma

Human endometrium is a highly regenerative and dynamic tissue that undergoes cyclic changes during menstrual cycle. It has been reported that endometrial epithelium contains a population of progenitor/stem cells. Increasing amount of evidence indicates that progenitor/stem cells are involved in the pathogenesis of endometriosis. Proteins belonging to the aldehyde dehydrogenase 1 (ALDH1A) family have been reported to be markers of normal tissue stem cells and cancer stem cells. In this study, by using immunohistochemistry, we examined the expression of ALDH1A isozymes in human endometrial tissue, including that affected by endometriosis, and in ovarian endometrioma. Positive staining for ALDH1A isozymes was observed in the stroma of the endometrium and in endometriotic ovarian tissue. In the glands, expression patterns were distinct for different ALDH1A isozymes. ALDH1A1 and ALDH1A3 were highly expressed in the epithelium of stratum basalis of the endometrium and in the epithelium of ovarian endometrioma irrespective of the menstrual cycle, whereas ALDH1A2 was highly expressed only in the epithelium of endometrioma. Furthermore, ALDH1A1 co-localized with N-cadherin, which is a marker of endometrial epithelial progenitor cells, in the glands of stratum basalis. These findings support and reinforce the notion about the presence of progenitor/stem cells in endometrial glands in stratum basalis and in endometriotic glands, suggesting that these cells are involved in the physiology of the endometrium and in the pathology of endometriosis.

Different mutation profiles between epithelium and stroma in endometriosis and normal endometrium

STUDY QUESTION

Are there common mutation profiles between epithelial and stromal cells in ovarian endometriotic tissue and the normal endometrium?

SUMMARY ANSWER

Our study revealed no common mutations between epithelial and stromal cells in ovarian endometriotic tissue and the normal endometrium.

WHAT IS KNOWN ALREADY

Epithelial cells in both ovarian endometriotic tissue and the normal endometrium harbor somatic mutations in cancer-associated genes such as phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and KRAS proto-oncogene, GTPase (KRAS).

STUDY DESIGN, SIZE, DURATION

We performed a retrospective study to identify the mutation profiles of stromal cells in endometriotic tissue and the normal endometrium. We collected 11 endometriotic stroma samples and 10 normal endometrial stroma samples between 2013 and 2017 at a tertiary care center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The laser microdissection method was used to obtain stromal cells in ovarian endometriotic and normal endometrial tissues from patients with ovarian endometriosis and/or other non-invasive gynecological diseases. Target gene sequencing was performed to assess and compare the mutation profiles of stromal cells with those of epithelial cells obtained in our previous study. For target gene sequencing, 76 genes were selected based on previous genomic analyses for ovarian endometriosis, normal endometrium, endometriosis-related ovarian cancer and endometrial cancer.

MAIN RESULTS AND THE ROLE OF CHANCE

Stromal samples in ovarian endometrioma and normal endometrium harbor somatic mutations (18 mutations in 11 endometriosis samples and 16 mutations in 10 normal endometrial samples) but did not share any mutations with paired epithelial samples. The mutant allele frequency of stromal samples was significantly lower than that of epithelial samples in ovarian endometrioma (P = 6.0 × 10-11) and normal endometrium (P = 1.4 × 10-7).

LIMITATIONS, REASONS FOR CAUTION

The number of genes evaluated in the mutational analysis was limited. Additionally, the functional roles of somatic mutations in stromal cells remain unclear.

WIDER IMPLICATIONS OF THE FINDINGS

Different mutation profiles between paired epithelial and stromal cells in both ovarian endometrioma and normal endometrium suggest that origins of epithelial and stromal cells would be independent of each other in both normal endometrium and ovarian endometrioma; however, the theory of epithelial-mesenchymal transition is proposed in ovarian endometrioma.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by the Japan Society for the Promotion of Science KAKENHI grant number JP15H02373 (Grant-in-Aid for Scientific Research A for I.I.), JP16H06267 (Grant-in-Aid for Young Scientists A for K.Y.), JP17K08688 (Grant-in-Aid for Scientific Research C for H.N.) and JP16H06279 (Grant-in-Aid for Scientific Research on Innovative Areas—Platforms for Advanced Technologies and Research Resources for H.N. and K.Y). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Endometrial Stromal Cells Circulate in the Bloodstream of Women with Endometriosis: A Pilot Study

Endometriosis is characterized by the presence of endometrial tissue outside the uterus. While endometriotic tissue is commonly localized in the pelvic cavity, it can also be found in distant sites, including the brain. The origin and pathophysiology of tissue migration is poorly understood; retrograde menstruation is thought to be the cause, although the presence of endometrium at distant sites is not explained by this hypothesis. To determine whether dissemination occurs via the bloodstream in women with endometriosis, we analyzed circulating blood for the presence of endometrial cells. Circulating endometrial stromal cells were identified only in women with endometriosis but not in controls, while endometrial epithelial cells were not identified in the circulation of either group. Our results support the hypothesis that endometrial stromal cells may migrate through circulation and promote the pathophysiology of endometriosis. The detection of these cells in circulation creates avenues for the development of less invasive diagnostic tools for the disease, and opens possibilities for further study of the origin of endometriosis.

Adipocyte alterations in endometriosis: reduced numbers of stem cells and microRNA induced alterations in adipocyte metabolic gene expression

BACKGROUND

Endometriosis is an estrogen dependent, inflammatory disorder occurring in 5-10% of reproductive-aged women. Women with endometriosis have a lower body mass index (BMI) and decreased body fat compared to those without the disease, yet few studies have focused on the metabolic abnormalities in adipose tissue in women with endometriosis. Previously, we identified microRNAs that are differentially expressed in endometriosis and altered in the serum of women with the disease. Here we explore the effect of endometriosis on fat tissue and identified a role for endometriosis-related microRNAs in fat metabolism and a reduction in adipocyte stem cell number.

METHODS

Primary adipocyte cells cultured from 20 patients with and without endometriosis were transfected with mimics and inhibitors of microRNAs 342-3p or Let 7b-5p to model the status of these microRNAs in endometriosis. RNA was extracted for gene expression analysis by qRT-PCR. PCNA expression was used as a marker of adipocyte proliferation. Endometriosis was induced experimentally in 9-week old female C57BL/6 mice and after 10 months fat tissue was harvested from both the subcutaneous (inguinal) and visceral (mesenteric) tissue. Adipose-derived mesenchymal stem cells in fat tissue were characterized in both endometriosis and non-endometriosis mice by FACS analysis.

RESULTS

Gene expression analysis showed that endometriosis altered the expression of Cebpa, Cebpb, Ppar-γ, leptin, adiponectin, IL-6, and HSL, which are involved in driving brown adipocyte differentiation, appetite, insulin sensitivity and fat metabolism. Each gene was regulated by an alteration in microRNA expression known to occur in endometriosis. Analysis of the stem cell content of adipose tissue in a mouse model of endometriosis demonstrated a reduced number of adipocyte stem cells.

CONCLUSIONS

We demonstrate that microRNAs Let-7b and miR-342-3p affected metabolic gene expression significantly in adipocytes of women with endometriosis. Similarly, there is a reduction in the adipose stem cell population in a mouse model of endometriosis. Taken together these data suggest that endometriosis alters BMI in part through an effect on adipocytes and fat metabolism.

Micrometastasis of endometriosis to distant organs in a murine model

Endometriosis is an inflammatory gynecological disorder among reproductive-aged women caused by the engraftment and proliferation of endometrial cells outside the uterus, most commonly in the pelvis. It is thought that the disease arises primarily from retrograde menstruation where cells from the endometrium travel through the fallopian tubes to the peritoneal cavity. However, migration of endometriosis-derived cells to distant organs outside of the peritoneal cavity have not been explored. In the present study, we developed and validated a mouse model of disseminated endometriosis using syngeneic DsRed endometrial tissue introduced into the peritoneum of immunocompetent mice. Flow cytometry and immunofluorescence analysis, demonstrated the presence of endometriosis-derived cells in multiple organs (including lung, spleen, liver and brain) in the murine endometriosis model. Immunostaining revealed the presence of DsRed+/CD45- cells in brain, liver and lung. Engraftment occurred in all experimental animals examined. Cells from endometriotic lesions are capable of migration to and engraftment of multiple organs outside of the peritoneal cavity. Micrometastasis of endometriosis is a novel and frequent phenomenon. These data suggest that widespread dissemination of endometriosis may be common, clinically unrecognized and contribute to the diffuse clinical manifestations of this disease.

TGR5 agonist INT-777 mitigates inflammatory response in human endometriotic stromal cells: A therapeutic implication for endometriosis

Endometriosis is a condition characterized by the presence of endometrial tissues outside the uterus. Endometriotic stromal cells (ESCs) are known to undergo regeneration and are linked to the causation of endometriosis. Activation of stromal cells by local inflammatory cytokines is proposed to be one of the mechanisms of endometriosis development. Takeda-G-protein-receptor-5 (TGR5) is a G protein-coupled bile acid receptor that plays multiple roles in various cells and tissues. In this study, we show that activation of TGR5 by its specific agonist, INT-777, protects ESCs from inflammation and oxidative stress induced by tumor necrosis factor-α (TNF-α). TGR5 is fairly expressed in cultured ESCs, and TNF-α treatment suppresses TGR5 expression. Activation of TGR5 by its synthetic agonist, INT-777, dramatically reduces the production of pro-inflammatory cytokines and adhesion molecules by TNF-α, including interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Moreover, INT-777 suppresses TNF-α-induced NADPH oxidase 4 (NOX4) expression and ameliorates cellular oxidative stress. Mechanistically, our findings demonstrate that INT-777 suppresses TNF-α-induced c-Jun N-terminal kinase (JNK) activation via suppression of p-JNK. INT-777 inhibits TNF-α-induced activation of the activator protein-1 (AP-1) pathway owing to its suppression of c-Jun and c-fos as well as transfected AP-1 promoter. INT-777 also inhibits nuclear factor-κB (NF-κB) activation as revealed by its suppression of TNF-α-induced nuclear p65 accumulation and NF-κB promoter. Collectively, our data indicate that activation of TGR5 by its agonist has protective effects against inflammation and reactive oxygen species (ROS) in cytokine-induced activation of ESCs. Therefore, INT-777 may have an implication in the clinical treatment of endometriosis.

Impact of a Chinese Medicinal Formula, Xiao Liu Fang, on the "3A" Ability of Endometrial Stromal Cells in Patients with Endometriosis

The pathogenesis of endometriosis (EMS) is complicated, and treatment results are unsatisfactory. It has become the focus of gynecological research. Analysis targeting the pathogenesis of EMS is the key to providing more effective treatments. In recent years, the superiority of traditional Chinese medicine in treating EMS has been highlighted, so we investigated the impact of a Chinese medicinal formula (Xiao Liu Fang) on the “3A” ability, in situ, of ectopic endometrial stromal cells in patients with EMS. Primary endometrial stromal cells were isolated using a modified net filtration method, cultured, and identified in different groups. Endometrial cell attachment was measured using the methyl thiazolyl tetrazolium (MTT) colorimetric assay, cell aggression was detected by the transwell cell-invasion assay, and angiogenesis was defined by evaluating the mRNA concentrations of intercellular cell adhesion molecule 1 (ICAM-1), cyclooxygenase 2 (COX-2), matrix metallo peptidase 9 (MMP-9), and vascular endothelial growth factor (VEGF). Attachment, aggression, and angiogenesis (AAA) plays an important role in EMS, and a high dose of the Xiao Liu Fang extract can be used for the treatment of EMS owing to its inhibition of the AAA of endometrial stromal cells. Therefore, in-depth studies targeting the effective mechanisms and targets of traditional Chinese medicine (TCM) are of great significance for the prevention and treatment of EMS.

Pathogenomics of Endometriosis Development

For over 100 years, endometriosis, as a chronic, estrogen-dependent, inflammatory, heritable disease affecting approximately 5–10% of women in reproductive age has been the focus of clinicians and scientists. In spite of numerous environmental, genetic, epigenetic, endocrine, and immunological studies, our knowledge of endometriosis is still fragmentary, and its precise pathophysiology and pathogenomics remain a mystery. The implementation of new technologies has provided tremendous progress in understanding the many intrinsic molecular mechanisms in the development of endometriosis, with progenitor and stem cells (SCs) of the eutopic endometrium as the starting players and endometriotic lesions as the final pathomorphological trait. Novel data on the molecular, genetic, and epigenetic mechanisms of the disease are briefly outlined. We hypothesize the existence of an endometriosis development genetic program (EMDP) that governs the origin of endometrium stem cells programmed for endometriosis (1), their transition (metaplasia) into mesenchymal SCs (2), and their invasion of the peritoneum and progression to endometriotic lesions (3). The pros and cons of the recent unifying theory of endometriosis are also discussed. Complex genomic and epigenetic interactions at different stages of the endometriosis process result in different forms of the disease, with specific features and clinical manifestations. The significance of the EMDP in elaborating a new strategy for endometriosis prediction, prevention, and treatment is discussed.

Independent development of endometrial epithelium and stroma within the same endometriosis

The pathogenesis of endometriosis, a common benign but debilitating disease in women, remains elusive. The currently held stem cell theory posits that circulating progenitor/stem cells are deposited outside the uterus, where they differentiate into endometrial stroma and glandular tissue to establish endometriosis. Fundamental to testing this hypothesis is to elucidate the evolution of both tissue types. Here, we applied droplet digital PCR to analyze synonymous and missense somatic passenger mutations, which are neutral with respect to clonal selection, among six non-superficial endometriotic lesions. We found that among 19 mutations sequenced, all were significantly enriched in epithelial but not in stromal components of every lesion examined. Our data indicate that the evolution of non-superficial endometriosis is complex, in that epithelium is clonal and its development is independent of stroma, providing new insight into the genesis of endometriosis. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

G-Protein-Coupled Receptor CXCR7 Is Overexpressed in Human and Murine Endometriosis

Endometriosis is a chronic inflammatory disease. Dysfunctional regulation of chemokines and chemokine receptors is a crucial aspect of endometriosis pathogenesis. Chemokine G-protein-coupled receptors (GPCRs) are important drug targets that regulate inflammation and immunity. Recently, CXCR7, a C-X-C motif containing GPCR, has been identified as a receptor for chemokine ligand CXCL12, one of the best characterized chemokines for cell trafficking, angiogenesis, and cell proliferation in cancer and inflammation. Here, we investigated the expression and localization of CXCR7 in human endometriosis and a murine model of the disease. Normal endometrial epithelium and stroma showed undetectable or very low expression of CXCR7, without any significant changes across phases of the menstrual cycle in humans. CXCR7 is significantly upregulated in endometriosis, showing higher staining in glands and in associated vessels. The mouse model recapitulated the human findings. In conclusion, overexpression of CXCR7 in different cellular populations of endometriosis microenvironment may play a role in the pathogenesis and represent a novel target for treatment.

Oestrogen, progesterone and stem cells: the discordant trio in endometriosis?

Oestrogen–progesterone signalling is highly versatile and critical for the maintenance of healthy endometrium in humans. The genomic and nongenomic signalling cascades initiated by these hormones in differentiated cells of endometrium have been the primary focus of research since 1920s. However, last decade of research has shown a significant role of stem cells in the maintenance of a healthy endometrium and the modulatory effects of hormones on these cells. Endometriosis, the growth of endometrium outside the uterus, is very common in infertile patients and the elusiveness in understanding of disease pathology causes hindrance in selection of treatment approaches to enhance fertility. In endometriosis, the stem cells are dysfunctional as it can confer progesterone resistance to their progenies resulting in disharmony of hormonal orchestration of endometrial homeostasis. The bidirectional communication between stem cell signalling pathways and oestrogen–progesterone signalling is found to be disrupted in endometriosis though it is not clear which precedes the other. In this paper, we review the intricate connection between hormones, stem cells and the cross-talks in their signalling cascades in normal endometrium and discuss how this is deregulated in endometriosis. Re-examination of the oestrogen–progesterone dependency of endometrium with a focus on stem cells is imperative to delineate infertility associated with endometriosis and thereby aid in designing better treatment modalities.

Pathogenesis of endometriosis: Interaction between Endocrine and inflammatory pathways

Despite an estimated prevalence of 11% in women and plausible historical descriptions dating back to the 17th century, the etiology of endometriosis remains poorly understood. Classical theories of the histological origins of endometriosis are reviewed below. Clinical presentations are variable, and signs and symptoms do not correlate well with the extent of disease. In this summary, we have attempted to synthesize the growing evidence that hormonal and immune factors conspire to activate a local inflammatory microenvironment that encourages endometriosis to persist and elaborate mediators of its two cardinal symptoms: pain and infertility. Surprisingly, in the search for novel therapeutics for medical treatment of endometriosis, some compounds appear to have dual pharmacological functions, simultaneously modifying the endocrine and immune system facets of this complex gynecologic syndrome. We predict that these lead drugs will provide more therapeutic choices for patients in the future.

Bone Marrow Stem Cells Do Not Contribute to Endometrial Cell Lineages in Chimeric Mouse Models

Studies from five independent laboratories conclude that bone marrow stem cells transdifferentiate into endometrial stroma, epithelium, and endothelium. We investigated the nature of bone marrow-derived cells in the mouse endometrium by reconstituting irradiated wild type recipients with bone marrow containing transgenic mTert-green fluorescent protein (GFP) or chicken β-actin (Ch β-actin)-GFP reporters. mTert-GFP is a telomerase marker identifying hematopoietic stem cells and subpopulations of epithelial, endothelial, and immune cells in the endometrium. Ch β-actin-GFP is a ubiquitous reporter previously used to identify bone marrow-derived cells in the endometrium. Confocal fluorescence microscopy for GFP and markers of endometrial and immune cells were used to characterize bone marrow-derived cells in the endometrium of transplant recipients. No evidence of GFP⁺ bone marrow-derived stroma, epithelium, or endothelium was observed in the endometrium of mTert-GFP or Ch β-actin-GFP recipients. All GFP⁺ cells detected in the endometrium were immune cells expressing the pan leukocyte marker CD45, including CD3⁺ T cells and F4/80⁺ macrophages. Further examination of the Ch β-actin-GFP transplant model revealed that bone marrow-derived F4/80⁺ macrophages immunostained weakly for CD45. These macrophages were abundant in the stroma, infiltrated the epithelial and vascular compartments, and could easily be mistaken for bone marrow-derived endometrial cells. We conclude that it is unlikely that bone marrow cells are able to transdifferentiate into endometrial stroma, epithelium, and endothelium. This result has important therapeutic implications, as the expectation that bone marrow stem cells contribute directly to endometrial regeneration is shaping strategies designed to regenerate endometrium in Asherman's syndrome and to control aberrant endometrial growth in endometriosis. Stem Cells 2018;36:91-102.

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.

p38 Mitogen-Activated Protein Kinase is Involved in the Pathogenesis of Endometriosis by Modulating Inflammation, but not Cell Survival

BACKGROUND

Local pro-inflammatory environment and enhanced cell survival contribute to the endometriosis development. A serine/threonine kinase p38 mitogen-activated protein kinase (MAPK) mediates intracellular signaling of cytokine production, cell proliferation, and apoptosis in different cell types. The current study compares p38 MAPK activity in normal endometrium and endometriosis, and assesses role(s) of p38 MAPK on cytokine production and cell survival in endometriosis.

METHODS

Immunohistochemical levels of total and phosphorylated (active) p38 MAPK as well as its correlation with interleukin 8 (IL-8) expression, and cell proliferation and apoptosis were compared in normal human endometrium and endometriosis. The action of p38 MAPK on pro-inflammatory cytokine-induced IL-8 and monocyte chemotactic protein (MCP)-1 expression in endometriotic cells were assessed by enzyme-linked immunosorbent assay. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell survival, 5-bromo-2'-deoxyuridine incorporation, and Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assays were used to determine the function of p38 MAPK in cultured human endometriotic stromal cell proliferation and apoptosis.

RESULTS

p38 MAPK activity was significantly higher in both eutopic and ectopic endometria compared to normal endometria during late proliferative and early secretory phases ( P < .05). Increased p38 MAPK activity in endometriotic cells correlated with IL-8 expression (Pearson correlation coefficient r = 0.83, P < .01), but not with apoptosis in vivo. The pro-inflammatory cytokines IL-1β and tumor necrosis factor (TNF)-α induced activation of p38 MAPK. Inhibition of p38 MAPK activity blocked IL-1β and TNF-α-induced IL-8 and MCP-1 secretion in cultured endometriotic stromal cells ( P < .05), but did not impact on endometriotic cell survival.

CONCLUSIONS

These results suggest that rather than modulating cell survival, increased p38 MAPK activity in endometriotic cells contributes to the pathogenesis of endometriosis by promoting the local inflammatory milieu.

Adult Stem Cells in the Pathogenesis and Treatment of Endometriosis

The human endometrium is a dynamic tissue that undergoes approximately 400 cyclical episodes of proliferation, differentiation, shedding, and regeneration in a woman's reproductive lifespan. The regenerative capacity of human endometrium is likely mediated by adult stem cells. At the cellular level, endometrial mesenchymal stem/stromal cells, located in both the functionalis and basalis layers, support regeneration of the stromal vascular compartment and epithelial progenitor cells, postulated to reside in the basalis epithelium, likely regenerate the glands. Bone marrow adult stem cells, including endothelial progenitor cells, may also participate. Endometriosis can be considered an endometrial proliferative disorder due to dysregulation of the cellular and molecular regenerative processes.

Endometriosis is primarily thought to occur via retrograde menstruation of endometrial debris. It is postulated that endometrial stem/progenitor cells, which have been identified in menstrual blood, are shed into the peritoneal cavity where they adhere to pelvic organs and initiate endometriotic lesions. The homing of bone-marrow-derived adult stem cells to endometriotic lesions is thought to drive progression of the disease.

New drug therapies are urgently required for the treatment of endometriosis due to frequent disease recurrence with current surgical or medical treatments. Medications directly targeting endometrial stem/progenitor cells during menstruation, or following surgery, or targeting bone marrow cell trafficking, are potential targets for future therapies to manage disease initiation and progression.

In this review, we will summarize the current literature on adult stem cell contributions to the development of endometriosis and will then examine the current potential therapies that may target endometrial stem/progenitor cells.