Differentially-Expressed miRNAs in Ectopic Stromal Cells Contribute to Endometriosis Development: The Plausible Role of miR-139-5p and miR-375

Spatial transcriptomic analysis identifies epithelium-macrophage crosstalk in endometriotic lesions

The mechanisms underlying the pathophysiology of endometriosis, characterized by the presence of endometrium-like tissue outside the uterus, remain poorly understood. This study aimed to identify cell type-specific gene expression changes in superficial peritoneal endometriotic lesions and elucidate the crosstalk among the stroma, epithelium, and macrophages compared to patient-matched eutopic endometrium. Surprisingly, comparison between lesions and eutopic endometrium revealed transcriptional similarities, indicating minimal alterations in the sub-epithelial stroma and epithelium of lesions. Spatial transcriptomics highlighted increased signaling between the lesion epithelium and macrophages, emphasizing the role of the epithelium in driving lesion inflammation. We propose that the superficial endometriotic lesion epithelium orchestrates inflammatory signaling and promotes a pro-repair phenotype in macrophages, providing a new role for complement 3 in lesion pathobiology. This study underscores the significance of considering spatial context and cellular interactions in uncovering mechanisms governing disease in endometriotic lesions.

miR-375-3p predicts the severity of endometriosis and regulates cellular progression by targeting NOX4

BACKGROUND

Due to the complex pathogenesis of endometriosis, its early screening and development prediction are still challenging problems in the clinic.

OBJECTIVES

This study evaluated the significance of miR-375-3p in endometriosis onset, progression, and recurrence, aiming to identify a novel biomarker for disease diagnosis and prognosis.

MATERIALS AND METHODS

The study enrolled 100 patients with endometriosis and 80 healthy females. The serum miR-375-3p levels were compared between the two groups, and its diagnostic significance and predictive value were assessed by ROC and Cox regression analyses. The effect of miR-375-3p on endometriosis cell growth and motility was evaluated by CCK8 and Transwell assays.

RESULTS

Endometriosis patients showed a lower serum miR-375-3p level relative to healthy females, and more severe the disease condition, lower the miR-375-3p in endometrial tissues is. Reducing serum miR-375-3p could discriminate endometriosis patients sensitively and specifically. Additionally, miR-375-3p was identified as a predictor for the recurrence of endometriosis together with stage, lesion size, and the levels of related hormones. In endometriosis cells, miR-375-3p was demonstrated to target NOX4 and negatively regulated its expression. Overexpressing miR-375-3p significantly suppressed cell proliferation, migration, and invasion, which was reversed by NOX4.

CONCLUSION

Decreasing miR-375-3p served as a biomarker for endometriosis onset, development, and recurrence. miR-375-3p regulated endometriosis cell growth and motility via negatively modulating NOX4.

Serum-derived small extracellular vesicles as biomarkers for predicting pregnancy and delivery on assisted reproductive technology in patients with endometriosis

Introduction

Endometriosis can cause of infertility, and evaluation methods for predicting clinical pregnancy outcomes are desired. Extracellular vesicles (EVs) exist in blood and it contains small non-coding RNAs (ncRNAs) that may reflect disease severity. In this study, we investigated small ncRNAs in serum EVs to identify specific biomarkers for predicting clinical pregnancy.

Methods

Serum samples were collected from 48 patients who underwent assisted reproductive technology (ART). EVs were successfully isolated from serum samples and characterized using nanoparticle tracking assays, electron microscopy, and western blotting of EV's markers. We performed small RNA sequencing and analyzed microRNA (miRNA) profiles in the infertility patients with and without endometriosis to detect pregnancy-predicting biomarkers.

Results

Candidate miRNAs in serum EVs were selected by comparing patients without endometriosis who became pregnant (n = 13) with those who did not (n = 21). A total of 241 miRNAs were detected; however, no trends separated the two groups. Next, EVs from patients with endometriosis were analyzed and divided into pregnant (n = 4) and non-pregnant (n = 10) cases. Among the 224 candidate miRNAs, miRNA profiles of pregnant women with endometriosis were separated from those of non-pregnant women by receiver-operating characteristics (ROC) curve analysis (area under the curve [AUC] > 0.8). In patients with endometriosis, serum EVs may be useful for predicting possible pregnancy before infertility treatment. Finally, we used small RNA sequencing of the tissue to demonstrate that pregnancy-predicting miRNAs in serum EVs were produced from endometriosis lesions. Although no predictors were found from miRNAs in serum EVs without endometriosis, miRNAs in serum EVs of patients with endometriosis could provide novel noninvasive biomarkers to predict pregnancy and have potential clinical applicability in ART.

Discussion

Further studies are required to examine the functional importance of these miRNAs to elucidate the pathological mechanisms of endometriosis and pregnancy.

Spatial Transcriptomic Analysis Identifies Epithelium-Macrophage Crosstalk in Endometriotic Lesions

The mechanisms underlying the pathophysiology of endometriosis, characterized by the presence of endometrium-like tissue outside the uterus, remain poorly understood. This study aimed to identify cell type-specific gene expression changes in superficial peritoneal endometriotic lesions and elucidate the crosstalk among the stroma, epithelium, and macrophages compared to patient-matched eutopic endometrium. Surprisingly, comparison between lesions and eutopic endometrium revealed transcriptional similarities, indicating minimal alterations in the sub-epithelial stroma and epithelium of lesions. Spatial transcriptomics highlighted increased signaling between the lesion epithelium and macrophages, emphasizing the role of the epithelium in driving lesion inflammation. We propose that the superficial endometriotic lesion epithelium orchestrates inflammatory signaling and promotes a pro-repair phenotype in macrophages, providing a new role for Complement 3 in lesion pathobiology. This study underscores the significance of considering spatial context and cellular interactions in uncovering mechanisms governing disease in endometriotic lesions.

MiRNAs related in signaling pathways of women's reproductive diseases: an overview

BACKGROUND

One of the main health issues that can affect women's health is reproductive diseases, such as polycystic ovary syndrome (PCOS), endometriosis (EMs), uterine leiomyomas (ULs), and ovarian cancer (OC). Although these diseases are very common, we do not have a complete understanding of their underlying cellular and molecular mechanisms. It is important to mention that the majority of patients are diagnosed with these diseases at later stages because of the absence of early diagnostic techniques and dependable molecular indicators. Hence, it is crucial to discover novel and non-invasive biomarkers that have prognostic, diagnostic and therapeutic capabilities. MiRNAs, also known as microRNAs, are small non-coding RNAs that play a crucial role in regulating gene expression at the post-transcriptional level. They are short in length, typically consisting of around 22 nucleotides, and are highly conserved across species. Numerous studies have shown that miRNAs are expressed differently in various diseases and can act as either oncogenes or tumor suppressors.

METHODS

The author conducted a comprehensive review of all the pertinent papers available in web of science, PubMed, Google Scholar, and Scopus databases.

RESULTS

We achieved three goals: providing readers with better information, enhancing search results, and making peer review easier.

CONCLUSIONS

This review focuses on the investigation of miRNAs and their involvement in various reproductive disorders in women, including their molecular targets. Additionally, it explores the role of miRNAs in the development and progression of these disorders.

The Pathological Role of miRNAs in Endometriosis

Association studies investigating miRNA in relation to diseases have consistently shown significant alterations in miRNA expression, particularly within inflammatory pathways, where they regulate inflammatory cytokines, transcription factors (such as NF-κB, STAT3, HIF1α), and inflammatory proteins (including COX-2 and iNOS). Given that endometriosis (EMS) is characterized as an inflammatory disease, albeit one influenced by estrogen levels, it is natural to speculate about the connection between EMS and miRNA. Recent research has indeed confirmed alterations in the expression levels of numerous microRNAs (miRNAs) in both endometriotic lesions and the eutopic endometrium of women with EMS, when compared to healthy controls. The undeniable association of miRNAs with EMS hints at the emergence of a new era in the study of miRNA in the context of EMS. This article reviews the advancements made in understanding the pathological role of miRNA in EMS and its association with EMS-associated infertility. These findings contribute to the ongoing pursuit of developing miRNA-based therapeutics and diagnostic markers for EMS.

hsa_circ_0005991 promotes epithelial-mesenchymal transition by regulating miR-30b-3p/Cdc42EP1 axis in ovary endometriosis

Endometriosis is a common gynecological disease with an enigmatic pathogenesis. This work explored the function of hsa_circ_0005991 in ovarian endometriosis. High-throughput RNA-Seq was conducted in five matched ectopic (EC) and eutopic (EU) samples. Further, several types of cell function experiments were conducted. According to bioinformatics analysis, a competing endogenous RNA network was established. It included 5 circRNAs, 13 miRNAs, and 551 mRNAs. The expression levels of hsa_circ_0005991 and Cdc42EP1 were significantly elevated, while miR-30b-3p was reduced in the EC group. Upregulation of hsa_circ_0005991 raised Cdc42EP1 levels, induced EMT, and boosted Ishikawa cell proliferation, migration, and invasion. hsa_circ_0005991 knockdown indicated the opposite effects. When co-transfected with miR-30b-3p mimics or inhibitors, these effects could be reversed, respectively. Western blot assays showed alterations of EMT markers in EC samples. hsa_circ_0005991/miR-30b-3p/Cdc42EP1 axis promotes the EMT process in endometriosis, which may offer a theoretical foundation for the mechanism exploration and therapy of this disease.

Expression of HOXA10 Gene in Women with Endometriosis: A Systematic Review

The homeobox A10 (HOXA10) gene is known to be related to endometriosis; however, due to a lack of knowledge/evidence in the pathogenesis of endometriosis, the mechanisms that link HOXA10 to endometriosis still need to be clarified. This review addresses the difference in the expression of the HOXA10 gene in endometriotic women versus non-endometriotic women across populations by country and discusses its influences on women's fertility. An organized search of electronic databases was conducted in Scopus, ScienceDirect, PubMed, and Web of Science. The keywords used were (HOXA10 OR "homeobox A10" OR PL OR HOX1 OR HOX1H OR HOX1.8) AND ("gene expression") AND (endometriosis). The initial search resulted in 623 articles, 10 of which were included in this review. All ten papers included in this study were rated fair in terms of the quality of the studies conducted. The expression of the HOXA10 gene was found to be downregulated in most studies. However, one study provided evidence of the downregulation and upregulation of HOXA10 gene expression due to the localization of endometriotic lesions. Measuring the expression of the HOXA10 gene in women is clinically essential to predicting endometriosis, endometrial receptivity, and the development of pinopodes in the endometrium during the luteal phase.

Downregulation of DROSHA: Could It Affect miRNA Biogenesis in Endometriotic Menstrual Blood Mesenchymal Stem Cells?

Menstrual blood mesenchymal stem cells (MenSCs) have gained prominence in the endometriosis scientific community, given their multifunctional roles in regenerative medicine as a noninvasive source for future clinical applications. In addition, changes in post-transcriptional regulation via miRNAs have been explored in endometriotic MenSCs with a role in modulating proliferation, angiogenesis, differentiation, stemness, self-renewal, and the mesenchymal-epithelial transition process. In this sense, homeostasis of the miRNA biosynthesis pathway is essential for several cellular processes and is related to the self-renewal and differentiation of progenitor cells. However, no studies have investigated the miRNA biogenesis pathway in endometriotic MenSCs. In this study, we profiled the expression of eight central genes for the miRNA biosynthesis pathway under experimental conditions involving a two-dimensional culture of MenSCs obtained from healthy women (n = 10) and women with endometriosis (n = 10) using RT-qPCR and reported a two-fold decrease in DROSHA expression in the disease. In addition, miR-128-3p, miR-27a-3p, miR-27b-3p, miR-181a-5p, miR-181b-5p, miR-452-3p, miR-216a-5p, miR-216b-5p, and miR-93-5p, which have been associated with endometriosis, were identified through in silico analyses as negative regulators of DROSHA. Because DROSHA is essential for miRNA maturation, our findings may justify the identification of different profiles of miRNAs with DROSHA-dependent biogenesis in endometriosis.

Exosomal miR-202 derived from leukorrhea as a potential biomarker for endometriosis

OBJECTIVE

Endometriosis (EMS) is a chronic gynecological disorder with an urgent need of a reliable non-invasive diagnostic strategy. Recently, there has been increasing interest in using the contents of exosomes, especially exosomal microRNAs (miRNAs), as potential biomarkers for various types of diseases. In this study, we assessed the differentially expressed miRNAs in exosomes derived from primary normal and ectopic endometrial cells.

METHODS

We used miRNA microarray analysis to identify differentially expressed exosomal miRNAs. Among the selected exosomal miRNAs, we focused on hsa-miR-202-3p and hsa-miR-202-5p and validated their expression levels using quantitative reverse transcription polymerase chain reaction analysis. We then further examined their expression in exosomes derived from vaginal discharge (leukorrhea) from patients with EMS and the negative control group.

RESULTS

The data show that hsa-miR-202-3p and hsa-miR-202-5p were expressed significantly higher in leukorrhea-derived exosomes from EMS patients compared with the negative controls.

CONCLUSION

Taken together, our results suggest that leukorrhea-derived exosomal hsa-miR-202 could serve as a potential useful biomarker for diagnosing EMS.

Roles of microRNAs in Regulating Apoptosis in the Pathogenesis of Endometriosis

Endometriosis is a gynecologic disorder characterized by the presence of endometrial tissues outside the uterine cavity affecting reproductive-aged women. Previous studies have shown that microRNAs and their target mRNAs are expressed differently in endometriosis, suggesting that this molecule may play a role in the development and persistence of endometriotic lesions. microRNA (miRNA), a small non-coding RNA fragment, regulates cellular functions such as cell proliferation, differentiation, and apoptosis by the post-transcriptional modulation of gene expression. In this review, we focused on the dysregulated miRNAs in women with endometriosis and their roles in the regulation of apoptosis. The dysregulated miRNAs and their target genes in this pathophysiology were highlighted. Circulating miRNAs as potential biomarkers for the diagnosis of endometriosis have also been identified. As shown by various studies, miRNAs were reported to be a potent regulator of gene expression in endometriosis; thus, identifying the dysregulated miRNAs and their target genes could help discover new therapeutic targets for treating this disease. The goal of this review is to draw attention to the functions that miRNAs play in the pathophysiology of endometriosis, particularly those that govern cell death.

Long non-coding RNA DHRS4 antisense RNA 1 inhibits ectopic endometrial cell proliferation, migration, and invasion in endometriosis by regulating microRNA-139-5p expression

Endometriosis is an estrogen-dependent chronic gynecological syndrome. Recent studies have shown that long non-coding RNAs participate in the pathogenesis and development of endometriosis. This study aimed to explore the mechanisms of DHRS4 antisense RNA 1 (DHRS4-AS1) in endometriosis. Dual-luciferase reporter assays were conducted to determine the relationship between DHRS4-AS1, microRNA (miR)-139-5p, and arrestin domain-containing 3 (ARRDC3). Furthermore, the expression of DHRS4-AS1 and miR-139-5p in ectopic endometrial stromal cells (EC-ESCs) and endometriosis tissues was examined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Additionally, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry, and Transwell assays were performed to evaluate the proliferation, apoptosis, and migration and invasion of EC-ESCs, respectively. Western blotting and RT-qPCR were further utilized to determine cleaved-Caspase 3, Caspase 3, and matrix metalloproteinase 9 (MMP-9) expression levels. Compared with the EN group, DHRS4-AS1 levels were lower and miR-139-5p levels were higher in EC-ESCs and tissues obtained from patients with endometriosis. Functional assays validated that DHRS4-AS1 targets miR-139-5p, with ARRDC3 being a downstream target of miR-139-5p. Rescue experiments demonstrated that DHRS4-AS1 inhibited EC-ESC proliferation, migration, and invasion, but promoted apoptosis, by targeting miR-139-5p in endometriosis. cleaved-Caspase3 expression level and the cleaved-Caspase 3/Caspase 3 ratio increased, while the expression levels of MMP-9 decreased, after transfection with DHRS4-AS1 overexpression plasmids; however, the effects induced by DHRS4-AS1 overexpression could be partially reversed by co-transfection with the miR-139-5p mimic. The current study demonstrates that the DHRS4-AS1/miR-139-5p/ARRDC3 axis participates in the regulation of EC-ESC function.

MicroRNAs and Progesterone Receptor Signaling in Endometriosis Pathophysiology

Endometriosis is a significant disease characterized by infertility and pelvic pain in which endometrial stromal and glandular tissue grow in ectopic locations. Altered responsiveness to progesterone is a contributing factor to endometriosis pathophysiology, but the precise mechanisms are poorly understood. Progesterone resistance influences both the eutopic and ectopic (endometriotic lesion) endometrium. An inability of the eutopic endometrium to properly respond to progesterone is believed to contribute to the infertility associated with the disease, while an altered responsiveness of endometriotic lesion tissue may contribute to the survival of the ectopic tissue and associated symptoms. Women with endometriosis express altered levels of several endometrial progesterone target genes which may be due to the abnormal expression and/or function of progesterone receptors and/or chaperone proteins, as well as inflammation, genetics, and epigenetics. MiRNAs are a class of epigenetic modulators proposed to play a role in endometriosis pathophysiology, including the modulation of progesterone signaling. In this paper, we summarize the role of progesterone receptors and progesterone signaling in endometriosis pathophysiology, review miRNAs, which are over-expressed in endometriosis tissues and fluids, and follow this with a discussion on the potential regulation of key progesterone signaling components by these miRNAs, concluding with suggestions for future research endeavors in this area.

hsa-miR-340-5p inhibits epithelial–mesenchymal transition in endometriosis by targeting MAP3K2 and inactivating MAPK/ERK signaling

Increasing evidence has verified the indispensable effect of microRNAs (miRNAs) in the biological processes of human diseases, including endometriosis. hsa-miR-340-5p was reported to display a low level in patients with endometriosis, but the detailed function of miR-340-5p in endometriosis is unclarified. RT-qPCR was used for the assessment of RNA levels of miR-340-5p and its downstream target genes in endometrial stromal cells (ESCs). Western blotting and Transwell assays revealed that upregulation of miR-340-5p suppressed the migration, invasiveness, and epithelial–mesenchymal transition (EMT) in ESCs. Bioinformatics tools were used to predict miR-340-5p downstream genes. Luciferase reporter assay displayed that miR-340-5p could bind to messenger RNA mitogen-activated protein kinase kinase kinase 2 (MAP3K2). MAP3K2 was targeted by miR-349-5p and could reverse the influence of miR-340-5p. miR-340-5p exerted its impact on the invasive characters of ESCs by inactivating the MAP3K2-mediated MAPK/ERK signaling. In conclusion, miR-340-5p restrains cell migration, invasiveness, and EMT in ESCs by targeting MAP3K2 and inactivating MAPK/ERK signaling.

Impairment of Decidualization of Endometrial Stromal Cells by hsa-miR-375 Through NOX4 Targeting

Decidualization of the endometrial stromal cells (ESCs) is essential for successful embryo implantation. It involves the transformation of fibroblastic cells into epithelial-like cells that secrete cytokines, growth factors, and proteins necessary for implantation. Previous studies have revealed altered expression of miR-375 in the endometrium of patients with recurrent implantation failure and the ectopic stromal cells of patients with endometriosis. However, the exact molecular mechanisms, particularly the role of microRNAs (miRNAs) in the regulation of decidualization, remain elusive. In this study, we investigated whether decidualization is affected by miR-375 and its potential target(s). The findings demonstrated the downregulation of the expression of miR-375 in the secretory phase compared to its expression in the proliferative phase of the endometrium in normal donors. In contrast, it was upregulated in the secretory phase of the endometrium in infertility patients. Furthermore, during decidualization of ESCs in vitro, overexpression of miR-375 significantly reduced the transcript-level expression of forkhead box protein O1 (FOXO1), prolactin (PRL), and insulin-like growth factor binding protein-1 (IGFBP1), the well-known decidual cell markers. Overexpression of miR-375 also resulted in reduced decidualization-derived intracellular and mitochondrial reactive oxygen species (ROS) levels. Using the luciferase assay, we confirmed that NADPH oxidase 4 (NOX4) is a direct target of miR-375. Collectively, the study showed that the miR-375-mediated NOX4 downregulation reduced ROS production and attenuated the decidualization of ESCs. It provides evidence that miR-375 is a negative regulator of decidualization and could serve as a potential target for combating infertility.

Controlling Semi-Invasive Activity of Human Endometrial Stromal Cells by Inhibiting NF-kB Signaling Pathway Using Aloe-emodin and Aspirin

Background:

Inflammation and its master regulator, Nuclear Factor-kB (NF-kB), have been implicated in the development of endometriosis. Inhibition of NF-kB pathway using small molecules ameliorated disease progression and reduced the lesion size; nevertheless, the underlying mechanism is not fully understood. Therefore, this study, is an attempt to assess whether inhibiting NF-kB signaling by aloe-emodin (AE) or aspirin (Asp), as anti-inflammatory compounds, can suppresses the invasive activity of human endometrial stromal cells at stage IV endometriosis.

Methods:

The eutopic and healthy endometrial biopsies from a total of 8 infertile women with confirmed endometriosis and 8 women without endometriosis were digested and the single cells were cultured. Gene and protein markers of proliferation, migration, adhesion, and invasion of eutopic endometrial stromal cells (EuESCs) with and without treatment with AE or Asp, as well as control endometrial stromal cells (CESCs) was analyzed using q-PCR and immunofluorescence staining, respectively. Comparison between groups was performed using one-way ANOVA and the Bonferroni post hoc and p≤0.5 was considered statistically significant.

Results:

There was an association between NF-kB overexpression and higher proliferation/adhesion capacity in EuESCs. EuESCs (at stage IV endometriosis) displayed no invasive and migratory behaviors. Pre-treatment of EuESCs with AE or Asp significantly attenuated NF-kB expression and reduced proliferative, adhesive, invasive, and migratory activity of endometrial cells (p≤0.5).

Conclusion:

Eutopic endometrial stromal cells seem to have a semi-invasive activity which is largely suppressed by AE or Asp. It can be suggested that both Asp and AE (as potent NF-kB inhibitors) can be used as a supplement in conventional endometriosis treatments.

Knockdown hsa_circ_0063526 inhibits endometriosis progression via regulating the miR-141-5p / EMT axis and downregulating estrogen receptors

Endometriosis can cause severe social burdens. Abnormal circular RNA levels have been found to lead to changes of related gene expression, thereby mediating the occurrence and development of a series of diseases, including endometriosis. The role of circRNA in endometriosis is still in its infancy. This study will explore the role of circRNA hsa_circ_0063526 with microRNA-141-5p in the development of endometriosis. The expression levels of genes were detected by RT-qPCR. Transwell, wound-healing, and EdU assays were performed on the End1 / E6E7 cell line from the endometriosis patient. PCR and immunohistochemistry were used to detect the expression of candidate regulatory genes in ectopic lesions in an endometriosis mice model. The expression level of hsa_circ_0063526 in ectopic tissue of endometriosis patients was significantly higher than control (P<0.05), The expression levels of hsa_circ_0063526 and miRNA-141-5P in ectopic tissue of endometriosis were negatively correlated (P<0.05). Knockdown of hsa_circ_0063526 inhibited the invasion, migration, and proliferation ability of End1 / E6E7 cell; the inhibition of microRNA-141-5p rescued this inhibition (P <0.05). In vivo experiments showed that miR-141-5p and si-hsa_circ_0063526 treatment reduced lesion size and regulated endometriosis genes. Our data suggest that hsa_circ_0063526 and miR-141-5p are possible biomarkers and therapeutic targets for endometriosis.

Homing Peptide-Based Targeting of Tenascin-C and Fibronectin in Endometriosis

The current diagnostic and therapeutic strategies for endometriosis are limited. Although endometriosis is a benign condition, some of its traits, such as increased cell invasion, migration, tissue inflammation, and angiogenesis are similar to cancer. Here we explored the application of homing peptides for precision delivery of diagnostic and therapeutic compounds to endometriotic lesions. First, we audited a panel of peptide phages for the binding to the cultured immortalized endometriotic epithelial 12Z and eutopic stromal HESC cell lines. The bacteriophages displaying PL1 peptide that engages with angiogenic extracellular matrix overexpressed in solid tumors showed the strongest binding to both cell lines. The receptors of PL1 peptide, tenascin C domain C (TNC-C) and fibronectin Extra Domain-B (Fn-EDB), were expressed in both cells. Silver nanoparticles functionalized with synthetic PL1 peptide showed specific internalization in 12Z and HESC cells. Treatment with PL1-nanoparticles loaded with the potent antimitotic drug monomethyl auristatin E decreased the viability of endometriotic cells in 2D and 3D cultures. Finally, PL1-nanoparticless bound to the cryosections of clinical peritoneal endometriotic lesions in the areas positive for TNC-C and Fn-EDB immunoreactivities and not to sections of normal endometrium. Our findings suggest potential applications for PL1-guided nanoparticles in precision diagnosis and therapy of endometriosis.

Endometriosis: Epidemiology, Classification, Pathogenesis, Treatment and Genetics (Review of Literature)

Endometriosis is a “mysterious” disease and its exact cause has not yet been established. Among the etiological factors, congenital, environmental, epigenetic, autoimmune and allergic factors are listed. It is believed that the primary mechanism of the formation of endometriosis foci is retrograde menstruation, i.e., the passage of menstrual blood through the fallopian tubes into the peritoneal cavity and implantation of exfoliated endometrial cells. However, since this mechanism is also observed in healthy women, other factors must also be involved in the formation of endometriosis foci. Endometriosis is in many women the cause of infertility, chronic pain and the deterioration of the quality of life. It also represents a significant financial burden on health systems. The article presents a review of the literature on endometriosis—a disease affecting women throughout the world.

Role of miR-139-5p in ectopic endometrial stromal cells and the underlying molecular mechanism

Endometriosis is an estrogen-dependent disease. Studies have shown that miR-139-5p is significantly upregulated in endometriosis lesions, but its specific role and molecule mechanism in endometriosis has not yet been reported. The malignant biological behavior of ectopic endometrial stromal cells (ESCs) is similar to that of malignant cancer cells. BBC3 (BCL2 binding component 3) is a known apoptosis inducer and it serves key roles in the regulation of cell behavior. However, the role of BBC3 in ectopic ESCs remains unknown. The present study aimed to investigate the role of miR-139-5p in the progression of endometriosis and to determine its underlying molecular mechanism of action. Ectopic, non-ectopic and normal endometrial stromal cells (ESCs) were extracted from endometrial samples, and reverse transcription-quantitative PCR was performed to determine microRNA (miR)-139-5p and Bcl-2 binding component 3 (BBC3) mRNA expression levels in endometrial tissue samples and ESCs. The target gene of miR-139-5p was predicted using TargetScan software and verified using a dual luciferase reporter assay. Western blotting was performed to determine BBC3 protein expression levels. Flow cytometry analysis, and MTT and Transwell assays were performed to assess cell apoptosis, viability, and migration and invasion of the cells transfected with inhibitor control, miR-139-5p inhibitor, miR-139-5p inhibitor + control-small interfering (si)RNA or miR-139-5p inhibitor + BBC3-siRNA, respectively. The results demonstrated that miR-139-5p expression levels were upregulated in ectopic endometrial samples and ESCs compared with the respective control groups. Furthermore, it was verified that BBC3 was a direct target of miR-139-5p, and both BBC3 mRNA and protein expression levels were downregulated in ectopic endometrial samples and ESCs. Both transfection with the miR-139-5p inhibitor and BBC3-small interfering (si)RNA markedly downregulated miR-139-5p and BBC3 expression levels in ectopic ESCs, respectively. miR-139-5p inhibitor-induced upregulated BBC3 expression was reversed following transfection with BBC3-siRNA. Furthermore, the miR-139-5p inhibitor significantly decreased viability, migration and invasion, while inducing apoptosis in ectopic ESCs compared with the inhibitor control group. Notably, the aforementioned effects were reversed by knocking down BBC3 expression. In conclusion, the results of the present study suggested that miR-139-5p may play a key role in the progression of endometriosis by regulating the viability of ESCs and directly targeting BBC3.

Role of miRNAs in Normal Endometrium and in Endometrial Disorders: Comprehensive Review

The molecular responses to hormonal stimuli in the endometrium are modulated at the transcriptional and post-transcriptional stages. Any imbalance in cellular and molecular endometrial homeostasis may lead to gynecological disorders. MicroRNAs (miRNAs) are involved in a wide variety of physiological mechanisms and their expression patterns in the endometrium are currently attracting a lot of interest. miRNA regulation could be hormone dependent. Conversely, miRNAs could regulate the action of sexual hormones. Modifications to miRNA expression in pathological situations could either be a cause or a result of the existing pathology. The complexity of miRNA actions and the diversity of signaling pathways controlled by numerous miRNAs require rigorous analysis and findings need to be interpreted with caution. Alteration of miRNA expression in women with endometriosis has been reported. Thus, a potential diagnostic test supported by a specific miRNA signature could contribute to early diagnosis and a change in the therapeutic paradigm. Similarly, specific miRNA profile signatures are expected for RIF and endometrial cancer, with direct implications for associated therapies for RIF and adjuvant therapies for endometrial cancer. Advances in targeted therapies based on the regulation of miRNA expression are under evaluation.

MiR-370-3p inhibits the development of human endometriosis by downregulating EDN1 expression in endometrial stromal cells

MiR-370-3p has been demonstrated to be downregulated in patients with endometriosis (EM). However, its role and molecular mechanisms in the progression of EM remain unclear. Real-time polymerase chain reaction was used to measure the expression of miR-370-3p and endothelin-1 (EDN1) in patients with or without EM. After miR-370-3p overexpression or knockdown in ectopic endometrial hEM15A cells, the changes in the proliferation, apoptosis, and migration and invasion capacities were detected by using cell counting kit-8, flow cytometry, and transwell methods. The interplay between miR-370-3p and EDN1 was confirmed by a luciferase reporter assay. Patients with EM showed adverse expression of EDN1 and miR-370-3p, especially in eutopic endometrium and ectopic endometrium. MiR-370-3p inhibited the proliferation, metastasis, and invasion capacities of hEM15A cells and promoted apoptosis. Investigation of its molecular mechanism revealed that miR-370-3p targeted EDN1 to influence the biological functions of hEM15A cells. MiR-370-3p represented as a therapeutic target for EM treatment.

miR-202-3p overexpression attenuates endometriosis-like lesions by modulating YAP-dependent transcription of S100A6 in murine models

AIM

Recent evidence has suggested the important implications of microRNAs (miRNAs) in the processes of proliferation and tissue remodeling in endometriosis (EMS). We therefore aim to determine the role of miR-202-3p in the pathophysiology of EMS and its underlying mechanisms.

METHODS

Experimental endometriosis was induced in ovariectomized mice implanted with a slow-release 17-β estradiol capsule. Eutopic endometrial stromal cells (euESCs) were isolated and assayed for proliferative, invasive and apoptotic properties by EdU staining, Transwell assays, and flow cytometry. The invasive and apoptotic features in the endometrium of mice with EMS in vivo were evaluated by using immunohistochemical staining and TUNEL assays.

RESULTS

miR-202-3p was observed to be downregulated in the endometrial tissues of EMS patients. MiR-202-3p was also found to target YAP1 which resulted in reduced euESC proliferation and invasion and increased apoptosis. YAP1 was able to phosphorylated STAT3 which consequently upregulated S100A6 to promote the proliferative and invasive abilities of euESCs. MiR-202-3p was thereby proposed to act as an inhibitor of proliferation and tissue damage in the in vivo setting of EMS, its effects however, were able to be counteracted byS100A6, which reversed the effects of miR-202-3p on tissue injury and cell proliferation.

CONCLUSION

Our data together evidenced that miR-202-3p targeted YAP1 to reduce STAT3-mediated S100A6 whereby preventing the progression of EMS.

The Genetic Background of Endometriosis: Can ESR2 and CYP19A1 Genes Be a Potential Risk Factor for Its Development?

Endometriosis is defined as the presence of endometrial foci, localized beyond their primary site, i.e., the uterine cavity. The etiology of this disease is rather complex. Its development is supported by hormonal, immunological, and environmental factors. During recent years, particular attention has been focused on the genetic mechanisms that may be of particular significance for the increased incidence rates of endometriosis. According to most recent studies, ESR2 and CYP19A1 genes may account for the potential risk factors of infertility associated with endometriosis. The paper presents a thorough review of the latest reports and data concerning the genetic background of the risk for endometriosis development.

Endometriosis Associated Infertility: A Critical Review and Analysis on Etiopathogenesis and Therapeutic Approaches

Endometriosis represents a frequently diagnosed gynecological affliction in the reproductive timespan of women, defined by symptoms ranging from pelvic pain to infertility. A complex interplay between the genetic profile, hormonal activity, menstrual cyclicity, inflammation status, and immunological factors define the phenotypic presentation of endometriosis. To date, imaging techniques represent the gold standard in diagnosing endometriosis, of which transvaginal ultrasonography and magnetic resonance imaging bring the most value to the diagnostic step. Current medical treatment options for endometriosis-associated infertility focus on either stimulating the follicular development and ovulation or on inhibiting the growth and development of endometriotic lesions. Techniques of assisted reproduction consisting of superovulation with in vitro fertilization or intrauterine insemination represent effective treatment alternatives that improve fertility in patients suffering from endometriosis. Emerging therapies such as the usage of antioxidant molecules and stem cells still need future research to prove the therapeutic efficacy in this pathology.

Plasma miRNAs as biomarkers for endometriosis

STUDY QUESTION

Can plasma miRNAs be used for the non-invasive diagnosis of endometriosis in infertile women?

SUMMARY ANSWER

miRNA-based diagnostic models for endometriosis failed the test of independent validation.

WHAT IS KNOWN ALREADY

Circulating miRNAs have been described to be differentially expressed in patients with endometriosis compared with women without endometriosis, suggesting that they could be used for the non-invasive diagnosis of endometriosis. However, these studies have shown limited consistency or conflicting results, and no miRNA-based diagnostic test has been validated in an independent patient cohort.

STUDY DESIGN, SIZE, DURATION

We performed genome-wide miRNA expression profiling by small RNA sequencing to identify a set of plasma miRNAs with discriminative potential between patients with and without endometriosis. Expression of this set of miRNAs was confirmed by RT-qPCR. Diagnostic models were built using multivariate logistic regression with stepwise feature selection. In a final step, the models were tested for validation in an independent patient cohort.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Plasma of all patients was available in the biobank of the Leuven Endometriosis Centre of Excellence. Biomarker discovery and model development were performed in a discovery cohort of 120 patients (controls = 38, endometriosis = 82), and models were tested for validation in an independent cohort of 90 patients (controls = 30, endometriosis = 60). RNA was extracted with the miRNeasy Plasma Kit. Genome-wide miRNA expression analysis was done by small RNA sequencing using the NEBNext small RNA library prep kit and the NextSeq 500 System. cDNA synthesis and qPCR were performed using the Qiagen miScript technology.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified a set of 42 miRNAs with discriminative power between patients with and without endometriosis based on genome-wide miRNA expression profiling. Expression of 41 miRNAs was confirmed by RT-qPCR, and 3 diagnostic models were built. Only the model for minimal-mild endometriosis (Model 2: hsa-miR-125b-5p, hsa-miR-28-5p and hsa-miR-29a-3p) had diagnostic power above chance performance in the independent validation (AUC = 60%) with an acceptable sensitivity (78%) but poor specificity (37%).

LIMITATIONS, REASONS FOR CAUTION

The diagnostic models were built and tested for validation in two patient cohorts from a single tertiary endometriosis centre. Further validation tests in large cohorts with patients from multiple endometriosis centres are needed.

WIDER IMPLICATION OF THE FINDINGS

Our study supports a possible biological link between certain miRNAs and endometriosis, but the potential of these miRNAs as clinically useful biomarkers is questionable in women with infertility. Large studies in well-described patient cohorts, with rigorous methodology for miRNA expression analysis, sufficient statistical power and an independent validation step, are necessary to answer the question of whether miRNAs can be used as diagnostics markers for endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

The project was funded by a grant from the Research Foundation - Flanders (FWO). A.V., D.F.O. and D.P. are PhD fellows from the FWO. T.D. is vice president and Head of Global Medical Affairs Fertility, Research and Development, Merck KGaA, Darmstadt, Germany. He is also a professor in Reproductive Medicine and Biology at the Department of Development and Regeneration, Group Biomedical Sciences, KU Leuven (University of Leuven), Belgium and an adjunct professor at the Department of Obstetrics and Gynecology in the University of Yale, New Haven, USA. Neither his corporate role nor his academic roles represent a conflict of interest with respect to the work done by him for this study. The other co-authors have no conflict of interest.

TRIAL REGISTRATION NUMBER

Not applicable.

Role of Non-coding RNAs in the Pathogenesis of Endometriosis

Endometriosis is a disorder characterized by the presence of endometrial glands and stroma like lesions outside of the uterus. Although several hypothesis have tried to explain the underlying cause of endometriosis, yet the main cause remained obscure. Recent studies have shown contribution of non-coding RNAs in the pathogenesis of endometriosis. Two classes of these transcripts namely long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have mostly attracted attention of researchers. Several studies have reported aberrant expression of these transcripts in affected tissues from patients as well as animal models. Modulation of important signaling pathways such as PI3K/AKT, P38-MAPK, ERK1/2-MAPK and Wnt-β catenin by miRNAs and lncRNAs have potentiated these molecules as biomarkers or therapeutic agents in endometriosis. Single nucleotide polymorphisms with miR-126, miR-143 and miR-146b have been associated with risk of endometriosis. Moreover, miRNAs and lncRNAs control inflammatory responses, cell proliferation, angiogenesis and tissue remodeling, thus understanding the role of these transcripts in endometriosis is a possible way to develop novel diagnostic tests and therapeutic targets for this disorder.

CircATRNL1 promotes epithelial-mesenchymal transition in endometriosis by upregulating Yes-associated protein 1 in vitro

Endometriosis is a common and benign gynecological disorder but exhibits malignant features. However, the underlying pathogenesis and pathophysiology of endometriosis remain unclear. Circular RNAs have been demonstrated to participate in the occurrence and progression of multiple diseases. This study was aimed to explore the roles of circATRNL1 in endometriosis in vitro. Based on the results of reverse transcription-quantitative polymerase chain reaction analysis, we found significant upregulation of circATRNL1 and Yes-associated protein 1 (YAP1), while downregulation of miR-141-3p and miR-200a-3p in ectopic tissues compared to eutopic tissues. The immunohistochemistry and western blot analysis showed differentially expressed epithelial-mesenchymal transition (EMT) markers between EuEM and EcEM tissues. The in vitro assays indicated that overexpression of circATRNL1 could promote the proliferation, migration, and invasion of Ishikawa cells, and induce EMT process, while circATRNL1 silencing showed the opposite effect. The mechanical investigation indicated that circATRNL1 upregulated YAP1 by sponging miR-141-3p and miR-200a-3p. Gain-of-function assays validated the inhibitory function of miR-141-3p and miR-200a-3p in endometriosis. The results of rescue assays confirmed the function of circATRNL1-miR-141-3p/miR-200a-3p-YAP1 axis on Ishikawa cells. Our findings demonstrate that abnormal upregulation of circATRNL1 regulates cell proliferation and motility and promotes EMT process via the miR-141-3p/miR-200a-3p-YAP1 axis in vitro, which could contribute to the progression of endometriosis.

The differential expression of miRNAs between ovarian endometrioma and endometriosis-associated ovarian cancer

Background

MicroRNAs (miRNAs) have been implicated to play a vital role in development, differentiation, cell proliferation and apoptosis. However, which miRNAs are actually associated with endometriosis-associated ovarian cancer remains controversial.

Methods

Serum and ascites samples were obtained from all patients. Serum samples from 5 cases of ovarian endometrioma and endometriosis-associated ovarian cancer each were submitted for comprehensive miRNA microarray profiling. We investigated the differential expression of miRNAs between the two groups to confirm the pivotal role of miRNAs. Quantitative reverse transcription-polymerase chain reaction validation of five selected miRNAs [miR-92a-3p, miR-486-5p, miR-4484, miR-6821-5p, and miR-7108-5p] was performed, and miR-486-5p expression analysis was followed by proliferation and wound healing assays, depending on the expression of miR-486-5p.

Result

miR-486-5p expression in serum and ascites samples from endometriosis-associated ovarian cancer patients was significantly higher than that from ovarian endometrioma patients. Moreover, the miR-486-5p level in serum and ascites samples was significantly correlated with the severity of the endometriosis. The upregulation of miR-486-5p in immortalized ovarian endometrioma cells significantly increased proliferation and migration. In contrast, the downregulation of miR-486-5p in these cells significantly decreased proliferation and migration.

Conclusion

miR-486-5p might function as an oncogenic miRNA in endometriosis-associated ovarian cancer and could be a noninvasive biomarker to prospect the severity of ovarian endometrioma.

Comprehensive characterization of endometrial competing endogenous RNA network in infertile women of childbearing age

Endometriosis is widely associated with infertility in women of childbearing age, for which there have been no effective treatments. Recent studies suggest that the dysregulation of RNAs contributes to the pathogenesis of endometriosis, so we conduct the case-control genetic analysis to characterize the expression and interaction of different subtypes of RNAs in infertile women with endometriosis. The ectopic and eutopic endometrium of patients undergoing infertility treatment were collected and subjected to high throughput sequencing, and bioinformatics analysis was conducted to construct the competing endogenous RNA (ceRNA) network. As a result, the RNA interactive network was constructed in endometriosis, and a set of mRNAs such as cyclin-dependent kinase 1 (CDK1) and proliferating cell nuclear antigen (PCNA) along with their corresponding miRNAs and lncRNAs were found to promote the growth and death of endometrial stromal cells, which was essential for the pathogenesis of endometriosis. These data suggest that RNA crosstalk is a crucial segment in the development of endometriosis, where CDK1 and PCNA may serve as emerging targets for the treatment of endometriosis-related infertility in women of childbearing age.

LINC01018 and SMIM25 sponged miR-182-5p in endometriosis revealed by the ceRNA network construction

The current study intended to explore the interaction of the long non-coding RNA (lncRNA), microRNA (miRNA), and messenger RNA (mRNA) under the background of competitive endogenous RNA (ceRNA) network in endometriosis (EMs). The differentially expressed miRNAs (DEmiRs), differentially expressed lncRNA (DELs), and differentially expressed genes (DEGs) between EMs ectopic (EC) and eutopic (EU) endometrium based on three RNA-sequencing datasets (GSE105765, GSE121406, and GSE105764) were identified, which were used for the construction of ceRNA network. Then, DEGs in the ceRNA network were performed with Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and protein-protein interaction (PPI) analysis. Besides, the DEmiRs in the ceRNA network were validated in GSE124010. And the target DELs and DEGs of verified DEmiRs were validated in GSE86534. The correlation of verified DEmiRs, DEGs, and DELs was explored. Moreover, gene set enrichment analysis (GSEA) was applied to investigate the function of verified DEmiRs, DEGs, and DELs. Overall, 1352 DEGs and 595 DELs from GSE105764, along with 27 overlapped DEmiRs between GSE105765 and GSE121406, were obtained. Subsequently, a ceRNA network, including 11 upregulated and 16 downregulated DEmiRs, 7 upregulated and 13 downregulated DELs, 48 upregulated and 46 downregulated DEGs, was constructed. The GO and KEGG pathway analysis showed that this ceRNA network probably was associated with inflammation-related pathways. Furthermore, hsa-miR-182-5p and its target DELs (LINC01018 and SMIM25) and DEGs (BNC2, CHL1, HMCN1, PRDM16) were successfully verified in the validation analysis. Besides, hsa-miR-182-5p was significantly negatively correlated with these target DELs and DEGs. The GSEA analysis implied that high expression of LINC01018, SMIM25, and CHL1, and low expression of hsa-miR-182-5p would activate inflammation-related pathways in endometriosis EU samples.LINC01018 and SMIM25 might sponge hsa-miR-182-5p to upregulate downstream genes such as CHL1 to promote the development 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.

Endometriosis Pathoetiology and Pathophysiology: Roles of Vitamin A, Estrogen, Immunity, Adipocytes, Gut Microbiome and Melatonergic Pathway on Mitochondria Regulation

Endometriosis is a common, often painful, condition that has significant implications for a woman’s fertility. Classically, endometriosis has been conceptualized as a local estrogen-mediated uterine condition driven by retrograde menstruation. However, recent work suggests that endometriosis may be a systemic condition modulated, if not driven, by prenatal processes. Although a diverse array of factors have been associated with endometriosis pathophysiology, recent data indicate that the low body mass index and decreased adipogenesis may be indicative of an early developmental etiology with alterations in metabolic function crucial to endometriosis pathoetiology.

The present article reviews the data on the pathoetiology and pathophysiology of endometriosis, suggesting key roles for alterations in mitochondria functioning across a number of cell types and body systems, including the immune system and gut microbiome. These changes are importantly regulated by decreases in vitamin A and its retinoic acid metabolites as well as increases in mitochondria estrogen receptor-beta and the N-acetylserotonin/melatonin ratio across development. This has treatment and future research implications for this still poorly managed condition, as well as for the association of endometriosis with a number of cancers.