Systems genetics view of endometriosis: a common complex disorder

Deep Infiltrating Endometriosis in Adolescence: Early Diagnosis and Possible Prevention of Disease Progression

Endometriosis has a prevalence of 10% worldwide in premenopausal women. Probably, endometriosis begins early in the life of young girls, and it is commonly diagnosed later in life. The prevalence of deep infiltrating endometriosis (DIE) in adolescence is currently unknown due to diagnostic limits and underestimation of clinical symptoms. Dysmenorrhea is a common symptom in adolescents affected by DIE, often accompanied by dyspareunia and chronic acyclic pelvic pain. Ultrasonography-either performed transabdominal, transvaginal or transrectal-should be considered the first-line imaging technique despite the potential for missed diagnosis due to early-stage disease. Magnetic resonance imaging should be preferred in the case of virgo patients or when ultrasonographic exam is not accepted. Diagnostic laparoscopy is deemed acceptable in the case of suspected DIE not responding to conventional hormonal therapy. An early medical and/or surgical treatment may reduce disease progression with an immediate improvement in quality of life and fertility, but at the same time, painful symptoms may persist or even recur due to the surgery itself. The aim of this narrative review is to report the prevalence of DIE in adolescents, describe the pathogenetic theories and discuss the management in adolescent women, including the challenging road to diagnosis and the treatment alternatives.

Identification and Immune Characteristics Study of Pyroptosis‑Related Genes in Endometriosis

Endometriosis (EMT) is a prevalent gynecological disorder characterized by pain and infertility associated with the menstrual cycle. Pyroptosis, an emerging cell death mechanism, has been implicated in the pathogenesis of diverse diseases, highlighting its pivotal role in disease progression. Therefore, our study aimed to investigate the impact of pyroptosis in EMT using a comprehensive bioinformatics approach. We initially obtained two datasets from the Gene Expression Omnibus database and performed differential expression analysis to identify pyroptosis-related genes (PRGs) that were differentially expressed between EMT and non-EMT samples. Subsequently, several machine learning algorithms, namely least absolute shrinkage selection operator regression, support vector machine-recursive feature elimination, and random forest algorithms were used to identify a hub gene to construct an effective diagnostic model for EMT. Receiver operating characteristic curve analysis, nomogram, calibration curve, and decision curve analysis were applied to validate the performance of the model. Based on the selected hub gene, differential expression analysis between high- and low-expression groups was conducted to explore the functions and signaling pathways related to it. Additionally, the correlation between the hub gene and immune cells was investigated to gain insights into the immune microenvironment of EMT. Finally, a pyroptosis-related competing endogenous RNA network was constructed to elucidate the regulatory interactions of the hub gene. Our study revealed the potential contribution of a specific PRG to the pathogenesis of EMT, providing a novel perspective for clinical diagnosis and treatment of EMT.

Genital tract infection and pelvic surgery contribute to the development of endometriosis

Endometriosis is a multifactorial disease, and inflammation is considered a core pathology. Inflammation related to genital tract infection (GTI) and surgical injury may cause endometriosis. Therefore, we investigated the incidence of endometriosis in women with a recent history of GTI, pelvic surgery, or both. Using the Korean National Health Insurance Service-National Sample Cohort, 20- to 49-year-old women diagnosed with GTI or who underwent pelvic surgeries between 2002 and 2008 were collected and followed up for five years. After excluding women who had already been diagnosed with endometriosis or diseases that may affect endometriosis, a total of 30,336 women were diagnosed with GTI (Study 1), 2894 women who underwent pelvic surgery (Study 2), and 788 women who underwent GTI and pelvic surgery, both (Study 3) were enrolled for each study. The comparison groups in which sociodemographic factors matched for each group were collected. The incidence of endometriosis per 1000 person-year was 5.37, 5.17, and 20.81 in each case group and was significantly higher than each comparison group. A recent history of GTI increased an adjusted hazard ratio (aHR) of 2.29 (1.99-2.63, 95% confidence interval) for the development of endometriosis. The aHRs of pelvic surgery history and the history of both GTI and pelvic surgery were 2.10 and 7.82, respectively. In conclusion, the pelvic inflammation resulting from genital infection and pelvic surgical injury may play a role in developing endometriosis. Active treatment of genital infections and careful surgical procedures to minimize tissue injury may reduce the incidence of pelvic endometriosis.

Molecular Basis of Endometriosis and Endometrial Cancer: Current Knowledge and Future Perspectives

The human endometrium is a unique tissue undergoing important changes through the menstrual cycle. Under the exposure of different risk factors in a woman's lifetime, normal endometrial tissue can give rise to multiple pathologic conditions, including endometriosis and endometrial cancer. Etiology and pathophysiologic changes behind such conditions remain largely unclear. This review summarizes the current knowledge of the pathophysiology of endometriosis and its potential role in the development of endometrial cancer from a molecular perspective. A better understanding of the molecular basis of endometriosis and its role in the development of endometrial pathology will improve the approach to clinical management.

MiR-182 inhibits proliferation, migration, invasion and inflammation of endometrial stromal cells through deactivation of NF-κB signaling pathway in endometriosis

Endometriosis affects about 10-15% women for reproductive age, but it is not currently curable and the underlying etiology for this disease is still not clear. In the present study, functions and mechanisms of miR-182 and RELA in endometriosis were investigated. BAY 11-7082 was used to block NF-κB pathway. qRT-PCR, ELISA and western blot assays were employed to evaluate the expressions of miR-182 and RELA, inflammatory factors and epithelial-mesenchymal transition (EMT)-related markers, and activation of NF-κB pathway. MTT, wound healing or Transwell assays were used to evaluate the cell proliferation, migration and invasion capacities. Bioinformatic and dual-luciferase reporter assays were carried out to analyze the interaction between miR-182 and RELA. MiR-182 expression was decreased, while RELA was increased as developed from normal to eutopic and ectopic status, which was accompanied by upregulated inflammatory factors and EMT-related proteins. RELA was directly targeted by miR-182 in human endometrial stromal cells. Overexpression of RELA increased inflammation-associated and EMT-related markers expression, while miR-182 upregulation decreased the expression of these genes in a dose-dependent manner, which finally attenuated the proliferation, migration and invasion capacities of endometrial stromal cells through deactivation of NF-κB signaling pathway. Moreover, co-overexpression of RELA reversed the above effects induced by miR-182. In a word, miR-182 directly targeted RELA and inhibited proliferation, migration, invasion, EMT and inflammation of endometrial stromal cells through deactivation of NF-κB signaling pathway in endometriosis. These results provide new insights into the interaction between miR-182 and NF-κB pathway and their potential as therapeutic targets for treatment of endometriosis.

The Chronic Use of Magnesium Decreases VEGF Levels in the Uterine Tissue in Rats

Vascular endothelial growth factor (VEGF) is the most important regulator of angiogenesis which serves to provide sufficient blood supply, and can trigger both physiological and pathological angiogenesis. Recent studies have shown that VEGF increases in gynecological diseases (such as endometriosis, ovarian, and endometrial cancers) and is a prognostic factor in these pathologies. Therefore, VEGF should be maintained at appropriate levels. Magnesium is used in many gynecological practices (such as eclampsia, preeclampsia, dysmenorrhea, and climacteric symptoms) and the mechanisms of action are still under investigation. Redox status, which can be regulated by magnesium, was shown to affect VEGF expression. The aim of this study was to evaluate the effects of chronic magnesium use on VEGF and oxidative status in the uterus. Magnesium sulfate was administered to rats at doses of 30 mg/kg (intramuscular) for 2 weeks. VEGF, Superoxide dismutase (SOD), Glutathione peroxidase (GPx), and Malondialdehyde (MDA) levels were measured using ELISA; vascular and cellular alterations were determined by histology in the uterine tissue at the metoestrus phase. In the uterine tissue of Mg-treated subjects, magnesium levels increased while VEGF, SOD, GPx, and MDA levels decreased without histological changes. There was a negative correlation between uterine tissue magnesium levels and VEGF, SOD, GPx, and MDA levels. Consequently, the results of this study demonstrated that regular magnesium use decreased VEGF levels in uterus. Decreased VEGF levels were associated with decreased uterine oxidative stress. Chronic magnesium usage may protect the uterine tissue from certain diseases in which angiogenesis is critical.

Learning endometriosis phenotypes from patient-generated data

Endometriosis is a systemic and chronic condition in women of childbearing age, yet a highly enigmatic disease with unresolved questions: there are no known biomarkers, nor established clinical stages. We here investigate the use of patient-generated health data and data-driven phenotyping to characterize endometriosis patient subtypes, based on their reported signs and symptoms. We aim at unsupervised learning of endometriosis phenotypes using self-tracking data from personal smartphones. We leverage data from an observational research study of over 4000 women with endometriosis that track their condition over more than 2 years. We extend a classical mixed-membership model to accommodate the idiosyncrasies of the data at hand, i.e., the multimodality and uncertainty of the self-tracked variables. The proposed method, by jointly modeling a wide range of observations (i.e., participant symptoms, quality of life, treatments), identifies clinically relevant endometriosis subtypes. Experiments show that our method is robust to different hyperparameter choices and the biases of self-tracking data (e.g., the wide variations in tracking frequency among participants). With this work, we show the promise of unsupervised learning of endometriosis subtypes from self-tracked data, as learned phenotypes align well with what is already known about the disease, but also suggest new clinically actionable findings. More generally, we argue that a continued research effort on unsupervised phenotyping methods with patient-generated health data via new mobile and digital technologies will have significant impact on the study of enigmatic diseases in particular, and health in general.

Analysis of exosomal lncRNA, miRNA and mRNA expression profiles and ceRNA network construction in endometriosis

Aim: To investigate exosomal RNAs (long noncoding RNAs (lncRNAs), microRNAs (miRNAs) and messenger RNAs (mRNAs)) profiling and their related networks in endometriosis (EMs). Materials & methods: RNA sequence was performed in exosomes from ovarian endometriomas (EC), eutopic endometria (EU) and normal endometria (Control) stromal cells. The bioinformatics algorithms evaluated competing endogenous RNA (ceRNA) networks. The top-ranked ceRNA networks were confirmed by RT-PCR. Results: Overlapped differentially expressed 938 lncRNAs, 39 miRNAs and 1449 mRNAs were identified. 13 co-expression modules and 61 ceRNA networks were constructed. Conclusion: This study for the first time shows exosomal RNA biomarkers and lncRNA-related networks in EMs, which reveals a novel molecular mechanism of EMs and provides new resources for EM diagnosis and treatment.

Phytochemical profiling and ameliorative effects of Achillea cretica L. on rat model of endometriosis

ETHNOPHARMACOLOGICAL RELEVANCE

Achillea cretica (AC) is a medicinal plant emphasized for treatment of gynecological disorders and pathological symptoms similar to endometriosis in traditional Persian medicine. Since information about its chemical constituents is limited, the aim of this study is to investigate phenolic composition of AC extract as well as its effect on experimental model of endometriosis.

MATERIALS AND METHODS

RP-HPLC-PDA-ESI-MS/MS analysis was used for the determination of polyphenolic compounds. Endometriosis was induced in rats by suturing of uterus segments to abdominal wall of same rat, after eight weeks when the model was induced, it was followed by 28 days of treatment with 100, 200, and 400 mg/kg/day of hydroethanolic extract of the plant. Blood samples and implanted tissues were collected in the final day, and area of foci, tumor necrosis factor-α, vascular endothelial growth factor, interleukin-6, and serum total thiol molecules were measured and compared with positive group (0.2 mg/kg/day letrozole) and control group (solvent of extract: normal saline). Implanted tissue sections of the sacrificed rats were also assessed histopathologically.

RESULTS

Nine polyphenolic compounds were identified in AC extract including 7 flavonoids and 2 phenolic acids. Plant extract decreased area of foci and cytokine levels in serum and local tissue. Histopathological assessments confirmed the effectiveness of treatments by decreasing the thickness of epithelial layer and increasing the infiltration of leukocytes into this layer. Doses of 100 mg/kg and 400 mg/kg of extract showed better effects in comparison with the dose of 200 mg/kg in reduction of cytokine levels and size of implanted tissue. Extract and letrozole did not demonstrate significant effect on thiol level.

CONCLUSION

AC aerial extract may be a favorable medicine for management of endometriosis by modulating inflammatory cytokines; however, further studies are needed for more conclusive and reliable decision about its efficacy and safety.

Bioinformatic analysis reveals the importance of epithelial-mesenchymal transition in the development of endometriosis

Background: Endometriosis is a frequently occurring disease in women, which seriously affects their quality of life. However, its etiology and pathogenesis are still unclear. Methods: To identify key genes/pathways involved in the pathogenesis of endometriosis, we recruited 3 raw microarray datasets (GSE11691, GSE7305, and GSE12768) from Gene Expression Omnibus database (GEO), which contain endometriosis tissues and normal endometrial tissues. We then performed in-depth bioinformatic analysis to determine differentially expressed genes (DEGs), followed by gene ontology (GO), Hallmark pathway enrichment and protein-protein interaction (PPI) network analysis. The findings were further validated by immunohistochemistry (IHC) staining in endometrial tissues from endometriosis or control patients. Results: We identified 186 DEGs, of which 118 were up-regulated and 68 were down-regulated. The most enriched DEGs in GO functional analysis were mainly associated with cell adhesion, inflammatory response, and extracellular exosome. We found that epithelial-mesenchymal transition (EMT) ranked first in the Hallmark pathway enrichment. EMT may potentially be induced by inflammatory cytokines such as CXCL12. IHC confirmed the down-regulation of E-cadherin (CDH1) and up-regulation of CXCL12 in endometriosis tissues. Conclusions: Utilizing bioinformatics and patient samples, we provide evidence of EMT in endometriosis. Elucidating the role of EMT will improve the understanding of the molecular mechanisms involved in the development of endometriosis.

Expression levels of circulatory mir-185-5p, vascular endothelial growth factor, and platelet-derived growth factor target genes in endometriosis

BACKGROUND

Using blood-based biomarkers such as microRNAs (miRNAs) may allow particularly effective and minimally invasive diagnosis and treatment of endometriosis. Objective: We evaluated the differential expression of circulating miRNA-185-5p (miR-185-5p), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) target genes between endometriosis and healthy women.

MATERIALS AND METHODS

25 women with a history of endometriosis (grad III-IV) diagnosed by laparoscopy as the case group and 25 women without endometriosis underwent laparoscopy for ovarian cysts or pelvic pain as the control group were enrolled in this case-control study. Blood samples were obtained, and total RNA was used for high-throughput small RNA sequencing, and this was confirmed by means of quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

miRNA expression profiling using non-coding RNA sequencing revealed that one miRNA including miR-185-5p was significantly down-regulated in the case group compared with the controls. The qRT-PCR results showed significant downregulation of the expression level of miR-185-5p (p < 0.01) in the plasma of the case group. Receiver operating characteristic (ROC) curve analysis showed the area of miR-185-5p under the ROC curve for endometriosis diagnosis was 0.919 (p < 0.001). The RT-PCR results demonstrated that there was no significant difference in the expression of VEGF and PDGF mRNA of blood samples in the cases compared to the control group (PDGF, p = 0.09 and VEGF, p = 0.36).

CONCLUSION

The low expression of miR-185-5p in the plasma of women with endometriosis could be employed as an important non-invasive biomarker for early detection and screening of endometriosis by blood samples.

Endometriosis Knowledgebase: a gene-based resource on endometriosis

Endometriosis is a complex, benign, estrogen-dependent gynecological disorder with an incidence of ~10% women in reproductive age. The implantation and growth of endometrial cells outside the uterus leads to the development of endometriosis. Endometriosis is also associated with comorbid conditions like cardiovascular and autoimmune diseases. The absence of non-invasive diagnostic markers, delayed diagnosis, high risk of recurrence of the disease on surgical removal of the tissue and absence of a definitive cure for endometriosis makes it imperative to gain insights into the complex etiology of endometriosis. A plethora of genes identified from blood and endometrial biopsies, involved in different pathways like steroid metabolism, angiogenesis, inflammation, etc. have been associated with endometriosis. However, the exact mechanism and genetic etiology of endometriosis still remain unclear. The polygenic nature of the disease, incongruent phenotypic manifestations in different ethnic populations and information scattered in literature makes it difficult to delineate the sub-network of genes that will aid in disease diagnosis and effective treatment. Endometriosis Knowledgebase is a manually curated database with information on genes associated with endometriosis. It holds information on 831 genes, their associated polymorphisms, gene ontologys, pathways and diseases. Genes in the database are enriched in pathways important for cell signaling, immune regulation and reproduction. A genetic overlap is seen between endometriosis and cancers, endocrine/reproductive, nervous system, immune and metabolic diseases. Network analysis of genes in the Endometriosis Knowledgebase helped predict 13 new candidate genes for endometriosis. These genes were found to be enriched in biological processes associated with endometriosis. The Endometriosis Knowledgebase and incorporated tools for gene and sequence-based analysis will benefit both researchers and clinicians working in the realm of reproductive biology.

Cross-disorder analysis of endometriosis and its comorbid diseases reveals shared genes and molecular pathways and proposes putative biomarkers of endometriosis

RESEARCH QUESTION

Women with endometriosis are considered to be at higher risk of several chronic diseases, such as autoimmune disorders, gynaecological cancers, asthma/atopic diseases and cardiovascular and inflammatory bowel diseases. Could the study of endometriosis-associated comorbidities help to identify potential biomarkers and target pathways of endometriosis?

DESIGN

A systematic review was performed to identify all possible endometriosis-associated comorbid conditions. Next, this list of disorders was coded into MeSH terms, and the gene expression profiles were downloaded from the Phenopedia database and subsequently analysed following a systems biology approach.

RESULTS

The results identified a group of 127 candidate genes that were recurrently expressed in endometriosis and its closest comorbidities and that were defined as 'endometriosis sibling disorders' (ESD). The enrichment analysis showed that these candidate genes are principally involved in immune and drug responses, hormone metabolism and cell proliferation, which are well-known hallmarks of endometriosis. The expression of ESD genes was then validated on independent sample cohorts (n = 207 samples), in which the involvement of 16 genes (AGTR1, BDNF, C3, CCL2, CD40, CYP17A1, ESR1, IGF1, IGF2, IL10, MMP1, MMP7, MMP9, PGR, SERPINE1 and TIMP2) in endometriosis was confirmed. Several of these genes harbour polymorphisms that associate to either endometriosis or its comorbid conditions.

CONCLUSIONS

The study results highlight the molecular processes underlying the aetiopathogenesis of endometriosis and its comorbid conditions, and identify putative endometriosis biomarkers.

The Origin and Pathogenesis of Endometriosis

Recent molecular genetic findings on endometriosis and normal endometrium suggest a modified model in which circulating epithelial progenitor or stem cells intended to regenerate uterine endometrium after menstruation may become overreactive and trapped outside the uterus. These trapped epithelium-committed progenitor cells form nascent glands through clonal expansion and recruit polyclonal stromal cells, leading to the establishment of deep infiltrating endometriosis. Once formed, the ectopic tissue becomes subject to immune surveillance, resulting in chronic inflammation. The inflammatory response orchestrated by nuclear factor-κB signaling is exacerbated by aberrations in the estrogen receptor-β and progesterone receptor pathways, which are also affected by local inflammation, forming a dysregulated inflammation-hormonal loop. Glandular epithelium within endometriotic tissue harbors cancer-associated mutations that are frequently detected in endometriosis-related ovarian cancers. In this review, we summarize recent advances that have illuminated the origin and pathogenesis of endometriosis and have provided new avenues for research that promise to improve the early diagnosis and management of endometriosis.

[Endometrial cell apoptosis impairment associated with hormonal imbalance as a key factor in the development of endometriosis]

The review describes the effect of certain hormones and their imbalance on apoptosis of retrogradely refluxed endometrial cells in the abdominal cavity and the effects of estrogen, progesterone, anti-Mullerian hormone, and gonadotropin-releasing hormone on the internal and external apoptotic pathways of various cell populations in endometriotic foci. The nuclear estrogen receptor β (ER-β) is shown to inhibit TNF receptors that trigger the external apoptotic pathway, but the effects of estrogens do not play a key role in the pathogenesis of endometriosis. The role of progesterone and changes in the receptor status towards prevalence of PR-A with a decreased response of endometrial tissue to progesterone and inhibition of apoptosis are described. We discuss the role of the anti-Müllerian hormone and gonadotropin-releasing hormone II (GnRH II) as activators of apoptosis in normal endometrial tissue and in endometriosis. Investigation of endocrine effects on apoptosis of parenchymal and stromal cells of endometriotic foci may provide a theoretical basis for searching for new therapeutic targets in this hormone-dependent pathology.

Genome-wide DNA methylation profiling in ectopic and eutopic of endometrial tissues

PURPOSE

Endometriosis is a gynecological disease that causes the uterine lining to appear in other organs outside the uterus. As DNA methylation has an important role in this disorder, its profiling can reveal new information to improve the diagnosis and treatment of endometriosis patients.

METHODS

We conducted a genome-wide methylation profiling of ectopic and eutopic endometrial tissues from women with and without endometriosis using Infinium Human Methylation 450K BeadChip arrays. DNA methylation samples were collected from nine ectopic and nine eutopic endometrial tissues of endometriosis and six endometrial tissues of healthy controls.

RESULTS

Correlation heatmaps and the principal component analysis divided the samples into two clusters, one consisting of all ectopic samples and the other consisting of both eutopic and control samples unexpectedly without segregation between them. The assay identified a group of methylated genes that were overrepresented in biological processes, including abnormality in signaling, development, and adhesion of cells. Pathway analysis revealed disruption in HTLV infection pathways, PI3K-Akt, oxytocin, and relaxin signaling. Moreover, we found eutopic lesions are strongly associated with autoimmune disease.

CONCLUSIONS

Our results confirmed the role of DNA methylation alternations in endometriosis development and pathogenesis. Our finding suggests aberrant DNA methylation can activate several signaling pathways including PI3k-AKT signaling, relaxin, and oxytocin which are associated with the pathogenesis of endometriosis.

High-Diversity Mouse Populations for Complex Traits

Contemporary mouse genetic reference populations are a powerful platform to discover complex disease mechanisms. Advanced high-diversity mouse populations include the Collaborative Cross (CC) strains, Diversity Outbred (DO) stock, and their isogenic founder strains. When used in systems genetics and integrative genomics analyses, these populations efficiently harnesses known genetic variation for precise and contextualized identification of complex disease mechanisms. Extensive genetic, genomic, and phenotypic data are already available for these high-diversity mouse populations and a growing suite of data analysis tools have been developed to support research on diverse mice. This integrated resource can be used to discover and evaluate disease mechanisms relevant across species.

Human epidemiological evidence about the associations between exposure to organochlorine chemicals and endometriosis: Systematic review and meta-analysis

BACKGROUND

Endometriosis is a gynaecological disease characterized by the presence of ectopic endometrial tissue that affects women during their reproductive years, having a strong impact on their lives, fertility and healthcare costs. The aetiology remains largely unknown, but current evidence suggests that it is multi-causal and oestrogen-dependent. Many epidemiologic studies have explored associations between organochlorine chemicals (OCCs) and endometriosis, but the findings are inconsistent.

OBJECTIVES

A systematic review (SR) and meta-analysis were conducted to gather and synthesize all the available evidence from human epidemiological studies about the associations between OCCs and endometriosis.

DATA SOURCES

The searches were conducted in PubMed and Web of Science in June 2016 with a final follow-up in August 2018.

STUDY ELIGIBILITY CRITERIA

Only human epidemiological studies were considered, independent of participant age, body mass index or life-stage. Studies reporting individual measures of exposure to OCCs were included, considering but not limited to polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), or organochlorine pesticides (OCPs). The primary health outcome was presence of endometriosis, including all sub-types. Eligibility criteria excluded articles not written in English, conference papers, reviews and studies with overlapping information.

STUDY APPRAISAL AND SYNTHESIS METHODS

A SR protocol pre-registered at PROSPERO was applied in duplicate to gather and extract all eligible original papers from PUBMED and Web of Science databases. Odds ratios were pooled using the inverse variance method for random effects meta-analysis for each group of OCCs. Risk of bias was assessed using the National Toxicology Program/Office of Health Assessment and Translation (NTP/OHAT) Risk of Bias Rating Tool for Human and Animal Studies adapted to the review question. The confidence in the body of evidence and related level of evidence was measured by using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) based NTP/OHAT framework. The results were structured and presented in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Of the 51 studies retained for the full-text screening, 17 provided effect sizes and metrics sufficient for pooling estimates through meta-analysis. The overall odds ratios and 95% confidence intervals were 1.65 (1.14; 2.39) for dioxins (n = 10), 1.70 (1.20; 2.39) for PCBs (n = 9), and 1.23 (1.13; 1.36) for OCPs (n = 5). Despite being statistically significant, these estimates should be considered with caution given the notable heterogeneity and small estimated effect size. Misclassification of exposure, due to varying laboratory detection rate capabilities, and disease status, due to varying definitions of endometriosis, were identified as major sources of uncertainty.

LIMITATIONS, CONCLUSIONS, AND IMPLICATIONS OF KEY FINDINGS

The level of evidence was considered to be "moderate" with "serious" risk of bias according the NTP/OHAT criteria, supporting the need for further well-designed epidemiological research to fill lingering data gaps. Given the complexity of endometriosis and lack of known biomarkers suitable for population-based research, carefully designed observational studies play an important role in better understanding the aetiology of endometriosis, as will evolving mixture modeling approaches capable of handling various environmental chemical exposures. Attention to critical windows of exposure will shed further light on the possible developmental origin of endometriosis. Considering the high economic and societal cost associated with endometriosis, further research on this field is urged.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42018080956.

Pathogenesis of endometriosis: the genetic/epigenetic theory

OBJECTIVE

To study the pathophysiology of endometriosis.

DESIGN

Overview of observations on endometriosis.

SETTING

Not applicable.

PATIENT(S)

None.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

The hypothesis is compatible with all observations.

RESULT(S)

Endometriosis, endometrium-like tissue outside the uterus, has a variable macroscopic appearance and a poorly understood natural history. It is a hereditary and heterogeneous disease with many biochemical changes in the lesions, which are clonal in origin. It is associated with pain, infertility, adenomyosis, and changes in the junctional zone, placentation, immunology, plasma, peritoneal fluid, and chronic inflammation of the peritoneal cavity. The Sampson hypothesis of implanted endometrial cells following retrograde menstruation, angiogenic spread, lymphogenic spread, or the metaplasia theory cannot explain all observations if metaplasia is defined as cells with reversible changes and an abnormal behavior/morphology due to the abnormal environment. We propose a polygenetic/polyepigenetic mechanism. The set of genetic and epigenetic incidents transmitted at birth could explain the hereditary aspects, the predisposition, and the endometriosis-associated changes in the endometrium, immunology, and placentation. To develop typical, cystic ovarian or deep endometriosis lesions, a variable series of additional transmissible genetic and epigenetic incidents are required to occur in a cell which may vary from endometrial to stem cells. Subtle lesions are viewed as endometrium in a different environment until additional incidents occur. Typical cystic ovarian or deep endometriosis lesions are heterogeneous and represent three different diseases.

CONCLUSION(S)

The genetic epigenetic theory is compatible with all observations on endometriosis. Implications for treatment and prevention are discussed.

Anti-angiogenic treatment of endometriosis via anti-VEGFA siRNA delivery by means of peptide-based carrier in a rat subcutaneous model

Development of gene therapy for endometriosis requires inhibition of vascularization in endometrial lesions. We have previously developed CXCR4 receptor-targeted siRNA carrier L1 and observed efficient RNAi-mediated down-regulation of VEGFA gene expression in endothelial cells followed by decrease in VEGFA protein production and inhibition of cell migration. In this study we evaluated L1 carrier as non-viral vector for anti-VEGFA siRNA delivery into endometrial implants in rat subcutaneous endometriosis model created by subcutaneous auto-transplantation of uterus horn's fragments. Therapeutic anti-angiogenic efficiency of anti-VEGFA siRNA/L1 polyplexes was evaluated by lesion size measurement, histopathologic examination, immunohistochemical staining and real-time reverse transcriptase-PCR analysis. After in vivo administration of anti-VEGFA siRNA we observed a 55-60% inhibition of endometriotic lesions growth and approximately two-fold decrease in VEGFA gene expression in comparison with untreated implants. Results of immunohistochemical examination of endometriotic lesions confirmed anti-angiogenic effects of anti-VEGFA siRNA/L1 polyplexes. Ultimately, our results demonstrate the efficiency of anti-angiogenic treatment of EM by means of anti-VEGFA siRNA delivery with L1 peptide-based carrier.

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.

A Review of the Epigenetic Contributions to Endometriosis

Epigenetic influences have been postulated to affect the course of endometriosis. DNA methyltransferases, estrogen and progesterone receptors, micro-RNAs, and histone deacetylators, have shown differential expression in endometriosis compared with normal endometrium. Others such as aromatase, Steroid Factor-1, COX-2, and Homeobox A10 also have epigenetic modifications in endometriosis. Limitations in this area of research include heterogeneity in study design, patient populations, and methods of analysis. Larger, controlled studies are needed. Future targeted uses of this work may include using methylomes to noninvasively diagnose endometriosis, or targeting histone-deacetylase inhibitors for treatment.

Non-neuronal cell outgrowth in C. elegans

Cell outgrowth is a hallmark of some non-migratory developing cells during morphogenesis. Understanding the mechanisms that control cell outgrowth not only increases our knowledge of tissue and organ development, but can also shed light on disease pathologies that exhibit outgrowth-like behavior. C. elegans is a highly useful model for the analysis of genes and the function of their respective proteins. In addition, C. elegans also has several cells and tissues that undergo outgrowth during development. Here we discuss the outgrowth mechanisms of nine different C. elegans cells and tissues. We specifically focus on how these cells and tissues grow outward and the interactions they make with their environment. Through our own identification, and a meta-analysis, we also identify gene families involved in multiple cell outgrowth processes, which defined potential C. elegans core components of cell outgrowth, as well as identify a potential stepwise cell behavioral cascade used by cells undergoing outgrowth.

[Pathogenesis, genetics and diagnosis of endometriosis]

Endometriosis is a multifactorial pathology. Trans-tubal reflux theory remains valid. Genetic and epigenetic factors associated with immunological perturbations are involved. The role of endocrine disruptors is discussed although epidemiological studies are contradictory. Therapeutics are primarily based on hormonal treatments but better understanding of pathophysiology should allow targeted non-hormonal therapy. The clinical examination is sometimes negative, which should not eliminate the diagnosis and imposes complementary examinations as best as possible by referents.

Metabolomic profiling and biochemical evaluation of the follicular fluid of endometriosis patients

Integration of the metabolic profile, the inflammatory state and the cell damage in the follicular fluid of women with endometriosis.

The gut microbiota: a puppet master in the pathogenesis of endometriosis?

Endometriosis is a frequent gynecologic disease with a complex, multifactorial cause. It is characterized by the cyclic estrogen-driven proliferation and bleeding of endometriotic lesions (ie, ectopic endometrial glands and stroma) outside the uterus. These lesions induce a chronic activation of the innate immune system within the peritoneal cavity that is associated with the release of various inflammatory cytokines and angiogenic growth factors into the peritoneal fluid. This stimulates angiogenesis and the further spread of the lesions and triggers the typical pain that is symptomatic of the disease. Moreover, circulating stem and progenitor cells are recruited into the ectopic endometrial tissue and contribute to its growth and vascularization. In recent years, an increasing number of studies have indicated that the gut microbiota is not only essential for a physiologic gastrointestinal function but acts as a central regulator of a variety of inflammatory and proliferative conditions. Besides, the gut flora affects estrogen metabolism and stem-cell homeostasis. Based on these findings, we hypothesize that the gut microbiota may be involved crucially in the onset and progression of endometriosis. In the future, this novel view of the pathogenesis of endometriosis may be verified by analysis of the development of endometriotic lesions in animal models with a defined composition of the gut microbiota and by investigation of the microbiota of patients with endometriosis with modern next-generation sequencing tools. This could open the door for completely new preventive, diagnostic, and therapeutic approaches for endometriosis.

Epigenetics: A key paradigm in reproductive health

It is well established that there is a heritable element of susceptibility to chronic human ailments, yet there is compelling evidence that some components of such heritability are transmitted through non-genetic factors. Due to the complexity of reproductive processes, identifying the inheritance patterns of these factors is not easy. But little doubt exists that besides the genomic backbone, a range of epigenetic cues affect our genetic programme. The inter-generational transmission of epigenetic marks is believed to operate via four principal means that dramatically differ in their information content: DNA methylation, histone modifications, microRNAs and nucleosome positioning. These epigenetic signatures influence the cellular machinery through positive and negative feedback mechanisms either alone or interactively. Understanding how these mechanisms work to activate or deactivate parts of our genetic programme not only on a day-to-day basis but also over generations is an important area of reproductive health research.

DNA methylation in endometriosis (Review)

Endometriosis is defined by the presence and growth of functional endometrial tissue, outside the uterine cavity, primarily in the ovaries, pelvic peritoneum and rectovaginal septum. Although it is a benign disease, it presents with malignant characteristics, such as invasion to surrounding tissues, metastasis to distant locations and recurrence following treatment. Accumulating evidence suggests that various epigenetic aberrations may play an essential role in the pathogenesis of endometriosis. Aberrant DNA methylation represents a possible mechanism repsonsible for this disease, linking gene expression alterations observed in endometriosis with hormonal and environmental factors. Several lines of evidence indicate that endometriosis may partially be due to selective epigenetic deregulations influenced by extrinsic factors. Previous studies have shed light into the epigenetic component of endometriosis, reporting variations in the epigenetic patterns of genes known to be involved in the aberrant hormonal, immunologic and inflammatory status of endometriosis. Although recent studies, utilizing advanced molecular techniques, have allowed us to further elucidate the possible association of DNA methylation with altered gene expression, whether these molecular changes represent the cause or merely the consequence of the disease is a question which remains to be answered. This review provides an overview of the current literature on the role of DNA methylation in the pathophysiology and malignant evolution of endometriosis. We also provide insight into the mechanisms through which DNA methylation-modifying agents may be the next step in the research of the pharmaceutical treatment of endometriosis.

Comparative systems genetics view of endometriosis and uterine leiomyoma: Two sides of the same coin?

Endometriosis (EM) and uterine leiomyoma (UL) are two most frequent benign tumors of monoclonal origin affecting about 30% of all women in their reproductive age. Modern molecular technologies have made a tremendous impact in understanding both disorders. Here is the first comparative analysis of molecular mechanisms underlying development of EM and UL as it looks from the platform of systems genetics. Similarities and differences of EM and UL at their incipient stages are enlightened with special emphasis on their gene networks, gene expression, and epigenetic regulation, of pathologic development. The analysis substantiates a new hypothesis postulating tumors as outgrowths of the stem cells with mesenchymal commitment lineage (mSC) which migrate from the endometrium/myometrium junctional zone of the uterus. Comparative analysis has revealed basic similarities of molecular pathogenesis of EM and UL suggesting molecular syntropy of both disorders. Peculiarities of the epigenetic landscape determining development of mSC may explain the existence of different clinical forms of EM and UL as well as their unique clinical manifestation. Some perspectives for practical and scientific application in EM and UL studies of this new hypothesis are outlined.

Survivin and VEGF as Novel Biomarkers in Diagnosis of Endometriosis

Background

The aim of this study was to investigate the role of peripheral blood markers as additional diagnostic tools to transvaginal ultrasound (TVU) findings in the diagnosis of endometriosis.

Methods

This study included 40 patients undergoing laparoscopy for suspected endometriosis from January to December 2012. Preoperative levels of serum CA125, CA19-9, CEA and mRNA expression levels for survivin and VEGF were obtained. Real-time PCR was used to determine relative gene expression. A new diagnostic score was obtained by deploying the peripheral blood markers to the TVU findings. Statistical methods used were Chi-square, Fisher’s, Student’s t-test or the Mann – Whitney test.

Results

There was a statistically significant difference in serum CA125, survivin and VEGF levels in patients with endometriosis and those without endometriosis (p<0.001, p=0.025 and p=0.009, respectively). False negative TVU findings were noted in 3/13 patients (23.1%) with peritoneal endometriosis without ovaries involvement. High sensitivity (93.3%), specificity (90.0%), PPV (96.6%), NPV (81.8%) and accuracy (92.5%) were obtained for a diagnostic score based on TVU and significant peripheral blood markers (CA125, survivin and VEGF).

Conclusions

Determination of serum CA125, mRNA expression levels for survivin and VEGF along with TVU can contribute to higher accuracy of the noninvasive diagnostic tools for endometriosis.

Increased dose single-agent gemcitabine in platinum-taxane resistant metastatic ovarian cancer

CONCLUSION

In platinum–taxane resistant epithelial ovarian cancer (EOC), we aimed to determine the effectiveness.

PATIENTS AND METHODS

Between 2004 and 2013, patients afflicted with platinum–taxane resistant EOC and who were administered a 30-minute i.v. infusion of single-agent gemcitabine at a dose of 1,250 mg/m2 on the 1st, 8th and 15th days, every 28 days, were examined retrospectively.

RESULTS

Twenty-six patients with platinum–taxane resistant EOC were included in the study. The overall survival (OS) was 48 months. The median survival after becoming platinum–taxane resistant was 16 months for the study population. Median time to progression (TTP) and median survival after becoming platinum–taxane resistant for patients who received second-line treatment were 3.3 months and 16 months, respectively; for patients who received third-line treatment with gemcitabine, these were 3.7 months and 19 months, respectively. Administration of gemcitabine as second- and third-line chemotherapy in platinum–taxane resistant EOC, provides similar TTP and OS outcomes (p = 0.4, p = 0.9) with a similar response and toxicity rate.

CONCLUSIONS

Second- and third-line gemcitabine at a dose of 1,250 mg/m2 on days 1, 8 and 15 every 28 days as a 30-minute i.v. infusion in platinum–taxane resistant EOC is an effective treatment option with a tolerable and manageable toxicity.