Increased expression of c-fos protein associated with increased matrix metalloproteinase-9 protein expression in the endometrium of endometriotic patients

Machine learning-based integrated identification of predictive combined diagnostic biomarkers for endometriosis

Background: Endometriosis (EM) is a common gynecological condition in women of reproductive age, with diverse causes and a not yet fully understood pathogenesis. Traditional diagnostics rely on single diagnostic biomarkers and does not integrate a variety of different biomarkers. This study introduces multiple machine learning techniques, enhancing the accuracy of predictive models. A novel diagnostic approach that combines various biomarkers provides a new clinical perspective for improving the diagnostic efficiency of endometriosis, holding significant potential for clinical application. Methods: In this study, GSE51981 was used as a test set, and 11 machine learning algorithms (Lasso, Stepglm, glmBoost, Support Vector Machine, Ridge, Enet, plsRglm, Random Forest, LDA, XGBoost, and NaiveBayes) were employed to construct 113 predictive models for endometriosis. The optimal model was determined based on the AUC values derived from various algorithms. These genes were then evaluated using nine machine learning algorithms (Random Forest, SVM, Gradient Boosting Machine, LASSO, XGB, NNET, Generalized Linear Model, KNN, and Decision Tree) to assess significance scores and identify diagnostic genes for each algorithm. The diagnostic value of these genes was further validated in external datasets from GSE7305, GSE11691, and GSE120103. Results: Analysis of the GSE51981 dataset revealed 62 DEGs. The Stepglm [Both] and plsRglm algorithms identified 30 genes with the most potential using the AUC evaluation. Subsequently, nine machine learning algorithms were applied to select diagnostic genes, leading to the identification of five key diagnostic genes using the LASSO algorithm. The ADAT1 gene exhibited the best single-gene predictive performance, with an AUC of 0.785. A combination of genes (FOS, EPHX1, DLGAP5, PCSK5, and ADAT1) achieves an AUC of 0.836 in the test dataset. Moreover, these genes consistently exhibited an AUC exceeding 0.78 in all validation datasets, demonstrating superior predictive performance. Furthermore, correlation analysis with immune infiltration strengthened their predictive value by demonstrating the close relationship of the diagnostic genes with immune infiltrating cells. Conclusion: A combination of biomarkers consisting of FOS, EPHX1, DLGAP5, PCSK5, and ADAT1 can serve as a diagnostic tool for endometriosis, enhancing diagnostic efficiency. The association of these genes with immune infiltrating cells reveals their potential role in the pathogenesis of endometriosis, providing new insights for early detection and treatment.

Complex Extract of Polygonatum sibiricum and Nelumbinis semen Improves Menopause Symptoms via Regulation of Estrogen Receptor Beta in an Ovariectomized Rat Model

Menopause is a hormone-deficiency state that causes facial flushing, vaginal dryness, depression, anxiety, insomnia, obesity, osteoporosis, and cardiovascular disease as ovarian function decreases. Hormone-replacement therapy is mainly used to treat menopause; however, its long-term use is accompanied by side effects such as breast cancer and endometriosis. To identify the effect of a complex extract of Polygonatum sibiricum (PS) and Nelumbinis semen (NS) on improving menopause without side effects, an ovariectomized rat model was established to analyze several menopause symptoms. Compared to single extracts, the complex extract restored vaginal epithelial cell thickness and decreased serotonin concentration by increasing the estrogen receptors ERα (ESR1) and ERβ (ESR2), depending on the ratio. Although the complex extract exerted a lower weight-loss effect than the single extracts, improved blood-lipid metabolism was observed after increasing high-density lipoprotein cholesterol levels and decreasing low-density lipoprotein cholesterol and triglyceride levels, and ovariectomy-induced osteoporosis was alleviated by suppressing osteoclast production. Thus, by increasing only ERβ expression without regulating ERα expression in the uterus, the complex extract of PS and NS may be a natural treatment for improving menopause symptoms without side effects, such as endometriosis.

Identification of key modules and candidate genes associated with endometriosis based on transcriptome data via bioinformatics analysis

BACKGROUNDS

Endometriosis is a common disease in women, but the signaling pathways and genes involved remain unclear. This study screened genes that were differentially expressed in ectopic endometrium (EC) and eutopic endometrium (EU) in endometriosis and provided clues for subsequent experimental verification.

METHODS

Endometriosis samples were harvested from inpatients that underwent surgery from 2017 to 2019 with pathological evidence of endometriosis. We assessed the mRNA expression profiles in endometriosis and further conducted gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, Gene Set Enrichment Analysis (GSEA) and weighted gene co-expression network analysis (WGCNA) to identify potential biomarkers in endometriosis. Finally, we further validated hub genes using public databases and immunohistochemistry assays.

RESULTS

The upregulated DEGs of ectopic endometrium from endometriosis patients were mainly involved in cell adhesion, MAPK signaling, PI3K-Akt signaling pathways, cytokine receptor interactions, and epithelial-mesenchymal transformation (EMT)-associated signaling pathways. The downregulated DEGs between ectopic endometrium and eutopic endometrium were related to decidualization-associated genes in endometriosis. The correlated gene modules in eutopic endometrial cells were mainly enriched in cell adhesion, embryo implantation and inflammation. The eutopic and ectopic endometrial lesions in endometriosis were involved in the EMT process. Furthermore, we identified 18 co-expression modules during WGCNA analysis. Hub genes in the pale turquoise module were FOSB, JUNB, ATF3, CXCL2, FOS, etc. Significantly enriched KEGG pathways included the TNF, MAPK, foxO, oxytocin, and p53 signaling pathways. Enrichment pathways were directly related to immune surveillance, stem cell self-renewal, and epithelial-mesenchymal transformation. Several pathways and modules of endometriosis are related to cancer-associated pathways, which substantiates the correlation between endometriosis and various gynecological tumors.

CONCLUSIONS

Endometriosis was tightly correlated with EMT and fibrosis mediated by inflammatory immunity, cytokines, estrogen, kinases and protooncogene through transcriptomics. Overall, our findings lay the groundwork for understanding the pathogenesis of endometriosis and its relationship with malignant transformation.

AP-1 Subunit JUNB Promotes Invasive Phenotypes in Endometriosis

Endometriosis is a disease defined by the presence of abnormal endometrium at ectopic sites, causing pain and infertility in 10% of women. Mutations in the chromatin remodeling protein ARID1A (AT-rich interactive domain-containing protein 1A) have been identified in endometriosis, particularly in the more severe deep infiltrating endometriosis and ovarian endometrioma subtypes. ARID1A has been shown to regulate chromatin at binding sites of the Activator Protein 1 (AP-1) transcription factor, and AP-1 expression has been shown in multiple endometriosis models. Here, we describe a role for AP-1 subunit JUNB in promoting invasive phenotypes in endometriosis. Through a series of knockdown experiments in the 12Z endometriosis cell line, we show that JUNB expression in endometriosis promotes the expression of epithelial-to-mesenchymal transition genes co-regulated by ARID1A including transcription factors SNAI1 and SNAI2, cell adhesion molecules ICAM1 and VCAM1, and extracellular matrix remodelers LOX and LOXL2. In highly invasive ARID1A-deficient endometriotic cells, co-knockdown of JUNB is sufficient to suppress invasion. These results suggest that AP-1 plays an important role in the progression of invasive endometriosis, and that therapeutic inhibition of AP-1 could prevent the occurrence of deep infiltrating endometriosis.

Associations Between Keratoconus and the Level of Sex Hormones: A Cross-Sectional Study

Purpose

To analyze the level of sex hormone in relation to keratoconus (KC).

Methods

Sixty-two eyes of 62 patients (12 females, 50 males) classified as KC and 120 eyes of 120 patients (21 females, 99 males) with mild to moderate myopia and astigmatism were analyzed. Plasma samples were collected and analyzed using a chemiluminescence immunoassay to determine the concentrations of estriol (E₃), estradiol (E₂), progesterone (P), and testosterone (T). Corneal morphological parameters, such as the central corneal thickness (CCT), thinnest corneal thickness (TCT), and maximum simulated keratometry (K_max), were measured using Pentacam and Sirius.

Results

The mean age was 23.73 ± 5.16 years for patients with KC and 23.68 ± 6.10 years for patients treated with laser vision correction (LVC). Among the patients with KC, 12 were female (19.35%) and 50 were male (80.65%). The majority of patients with KC were between 20 and 30 years old. In female patients, the concentration of T in the KC group was significantly lower than that in the LVC group (0.86 ± 0.33 vs. 1.18 ± 0.58 nmol/L; P = 0.044). There were positive correlations between T, CCT (r = 0.395, P = 0.023) and TCT (r = 0.378, P = 0.030) in female patients. In male patients, E₂ was higher in the KC group than the LVC group (143.75 ± 34.82 vs. 124.80 ± 43.56 pmol/L; P = 0.013), while T was significantly lower (11.59 ± 2.85 vs. 13.58 ± 4.77 nmol/L; P = 0.026). A positive correlation was found between E₂ and K_max (r = 0.222, P = 0.007) in male patients.

Conclusions

Conclusively, our results showed that T level was reduced in both female and male KC plasma, while E₂ was increased in male KC plasma. Different levels of sex hormones are correlated with KC, which, may provide the basis of a new technique for screening and diagnosing KC with or without the assistance of current imaging techniques. Moreover, the correlations between sex hormone alterations and KC provide compelling insight into KC etiopathogenesis.

External validation of putative biomarkers in eutopic endometrium of women with endometriosis using NanoString technology

PURPOSE

To combine different independent endometrial markers to classify the presence of endometriosis.

METHODS

Endometrial biopsies were obtained from 109 women with endometriosis as well as 110 control women. Nine candidate biomarkers independent of cycle phase were selected from the literature and NanoString was performed. We compared differentially expressed genes between groups and generated generalized linear models to find a classifier for the disease.

RESULTS

Generalized linear models correctly detected 68% of women with endometriosis (combining deep infiltrating and ovarian endometriosis). However, we were not able to distinguish between individual types of endometriosis compared to controls. From the 9 tested genes, FOS, MMP7, and MMP11 seem to be important for disease classification, and FOS was the most over-expressed gene in endometriosis.

CONCLUSION(S)

Although generalized linear models may allow identification of endometriosis, we did not obtain perfect classification with the selected gene candidates.

Baicalein inhibits FURIN-MT1-MMP-mediated invasion of ectopic endometrial stromal cells in endometriosis possibly by reducing the secretion of TGFB1

PROBLEM

Endometriosis (EMs) is characterized by the presence of endometrial stroma and glands outside the uterus. Our previous study showed that baicalein inhibited proliferation and induced apoptosis in EMs. However, the effects of baicalein on the invasiveness of ectopic endometrial stromal cells (EcESCs) remain unclear. The aim of this study was to assess the potential anti-invasive effect of baicalein and determine the underlying mechanism.

METHODS

The invasive and migratory properties of EcESCs were assessed in vitro using Transwell and wound healing assays. The expression of functional markers of EcESCs, including matrix metalloproteases (MMPs), FURIN, and TGFB1, was analyzed using WB and ELISA. Additionally, a mouse model of EMs was treated with baicalein (10 mg/kg/d and 35 mg/kg/d) for 4 weeks. The weight and number of ectopic lesions were determined, and the expression of markers was assessed using immunohistochemistry.

RESULTS

Baicalein inhibited the invasion of EcESCs and the expression of certain invasion-related proteins, including MMP9, MMP2, and MT1-MMP. Exposure to baicalein reduced the extracellular levels of TGFB1 in EcESCs and the reduced expression of TGFB1, resulting in decreased expression of FURIN in EcESCs, which serves a pivotal role in the transformation of pro-MT1-MMP to activated MT1-MMP. In the mouse model of EMs, intraperitoneal injection of baicalein inhibited the growth of ectopic lesions and reduced MT1-MMP, FURIN, and TGFB1 expression.

CONCLUSIONS

Baicalein reduced the invasion of EMs, potentially by restricting the FURIN-MT1-MMP-mediated cell invasion of EcESCs maybe through reduction of the autocrine of TGFB1.

Determining the Molecular Background of Endometrial Receptivity in Adenomyosis

Background: Adenomyosis is a gynaecological condition with limited evidence of negative impact to endometrial receptivity. It is commonly associated with endometriosis, which has been shown to alter endometrial expression patterns. Therefore, the candidate genes identified in endometriosis could serve as a source to study endometrial function in adenomyosis. Methods: Transcripts/proteins associated with endometrial receptivity in women with adenomyosis or endometriosis and healthy women were obtained from publications and their nomenclature was adopted according to the HUGO Gene Nomenclature Committee (HGNC). Retrieved genes were analysed for enriched pathways using Cytoscape/Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Reactome tools to prioritise candidates for endometrial receptivity. These were used for validation on women with (n = 9) and without (n = 13) adenomyosis. Results: Functional enrichment analysis of 173, 42 and 151 genes associated with endometriosis, adenomyosis and healthy women, respectively, revealed signalling by interleukins and interleukin-4 and interleukin-13 signalling pathways, from which annotated LIF, JUNB, IL6, FOS, IL10 and SOCS3 were prioritised. Selected genes showed downregulated expression levels in adenomyosis compared to the control group, but without statistical significance. Conclusion: This is the first integrative study providing putative candidate genes and pathways characterising endometrial receptivity in women with adenomyosis in comparison to healthy women and women with endometriosis.

Transcriptome meta-analysis reveals differences of immune profile between eutopic endometrium from stage I-II and III-IV endometriosis independently of hormonal milieu

Eutopic endometrium appears to be crucial for endometriosis development. Despite of the evident importance, data regarding the cellular microenvironment remain unclear. Our objective was to explore the tissue microenvironment heterogeneity, transcripts, and pathways that are enriched in all phases of the menstrual cycle by analysing publicly deposited data derived from whole transcriptome microarrays of eutopic endometria of women with and without endometriosis. A meta-analysis of the transcriptome microarrays was performed using raw data available from a public database. Eligibility criteria included eutopic endometrium samples from women with endometriosis and healthy controls without any pathological condition reported the presence of an adequately reported normal menstrual phase, and samples containing both glandular and stromal components. Raw data were processed using a robust multiarray average method to provide background correction, normalisation, and summarisation. The batch effect was estimated by principal variant component analysis and removed using an empirical Bayes method. Cellular tissue heterogeneity was inferred using the xCell package. Differentially expressed genes were identified based on a 5% adjusted p value and a 2.0-fold change. Pathways were identified by functional enrichment based on the Molecular Signatures Database, a p value of < 5%, and an FDR q value of ≤ 25%. Genes that were more frequently found in pathways were identified using leading edge analysis. In a manner independent of cycle phase, the subpopulations of activated dendritic cells, CD4 T effector memory phenotype cells, eosinophils, macrophages M1, and natural killer T cells (NKT) were all higher in stage I-II endometriosis compared to those in healthy controls. The subpopulations of M2 macrophages and natural killer T cells were elevated in eutopic endometriums from women with stage III-IV endometriosis, and smooth muscle cells were always more prevalent in healthy eutopic endometriums. Among the differently expressed genes, FOS, FOSB, JUNB, and EGR1 were the most frequently mapped within the interaction networks, and this was independent of stage and cycle phase. The enriched pathways were directly related to immune surveillance, stem cell self-renewal, and epithelial mesenchymal transition. PI3K AKT mTOR, TGF signalling, and interferon alpha/gamma responses were enriched exclusively in stage III-IV endometriosis. The cellular microenvironments and immune cell profiles were different between eutopic endometriums from women with stage I-II and stage III-IV endometriosis, and these differences were independent of the hormonal milieu. Specifically, a pro-inflammatory profile was predominant in stage I-II endometriosis, and M1-M2 polarization into eutopic endometrium may be crucial for the progression of the disease. The higher prevalence of NKT cells in eutopic endometriums from women with endometriosis that was independent of cycle phase or staging suggested a sustained stress and/or damage to these eutopic endometriums. Based on this, the results of this meta-analysis are important for identifying challenges and opportunities for future research.

Doxycycline reduces MMP-2 activity and inhibits invasion of 12Z epithelial endometriotic cells as well as MMP-2 and -9 activity in primary endometriotic stromal cells in vitro

BACKGROUND

Matrix metalloproteinases (MMPs), especially the gelatinases MMP-2 and MMP-9, play a crucial role in the pathogenesis of endometriosis by enabling invasion. Doxycycline is a well-tolerated antibiotic and a potent MMP-inhibitor in subantimicrobial doses.

METHODS

Gelatin zymography and activity assays were used to detect latent and active MMP-2 and -9 in cell culture supernatants of immortalized epithelial (12Z) and two isolates of primary endometriotic stromal cells treated with doxycycline. The invasiveness of 12Z endometriotic cells treated with doxycycline was assessed in matrigel-coated invasion chambers. The effect on latent and active MMP-2 expression of the combination of progesterone and doxycycline was tested in 12Z.

RESULTS

Doxycycline significantly reduced the MMP-2 activity and pro-MMP-2 expression in 12Z and the MMP-2 and -9 activity as well as expression of pro-MMP-2 and -9 in primary endometriotic stromal cells. The percentage of 12Z cells invading through a matrigel-coated membrane was reduced to 65 and 22% of the control after treatment with doxycycline at doses of 1 μg/ml and 10 μg/ml, respectively. Furthermore, a combination of progesterone and doxycycline showed an additive effect in low doses on the reduction of MMP-2 activity and pro-MMP2 expression in 12Z endometriotic cells.

CONCLUSIONS

In conclusion, the MMP-inhibiting features of subantimicrobial-dose doxycycline may be further evaluated as a well-tolerable additional therapeutic approach, e.g. in combination with progestins such as dienogest, in patients with infiltrative endometriosis with insufficient response to current medical treatment options.

The bimodal role of matrix metalloproteinases and their inhibitors in etiology and pathogenesis of endometriosis (Review)

Aberrant regulation of matrix metalloproteinases (MMPs) may be the primary cause of endometrial lesion formation in a group of predisposed women. Prospect for the genuine origin of endometriosis is ongoing, since retrograde menstruation leads to presence of endometrial debris in peritoneal cavity of many women, which do not experience endometriosis. Tissue remodeling is regulated precisely by a balance of MMPs and their inhibitors. Interplay between factors enhancing and suppressing matrix turnover is crucial for cyclic preparation of endometrium for embryo implantation, and endometrial shedding and renewal in physiology of primates. Disorders of the regulation of matrix remodeling leads to augmentation of implantation and invasive growth of ectopic endometrial tissue. Moreover, endometriosis-induced changes in the matrix balance leads to adhesion formation, ovulatory dysfunction and fertility impairment. The review summarizes the current knowledge regarding the regulation of extracellular matrix turnover in the physiology of the endometrial cycle and in the development of endometriosis, as well as the pathophysiology of ovulatory dysfunction in endometriotic women. Therapeutic modalities utilizing modulation of tissue remodeling were discussed.

Expression and shedding of CD44 in the endometrium of women with endometriosis and modulating effects of vitamin D: A randomized exploratory trial

Endometriosis is an estrogen-dependent disease. The impaired estrogen and progesterone signaling over-activates the Wnt/β-catenin pathway in endometriosis patients, which can explain the increased invasion potency of endometrial cells derived from the endometrium of women with endometriosis. The regulatory effects of vitamin D on Wnt/β-catenin pathway were demonstrated by previous studies. According to gene prioritization method, among Wnt target genes, CD44 was in high ranking in relation to endometriosis. The aim of this study is to investigate the expression of CD44 in the endometrium of women with endometriosis and to study the effects of vitamin D on its expression. This prospective study was performed, during a 12 months period from December 2015 to November 2016, on healthy women as the control group (n = 14) and endometriosis patients (n = 34). The endometriosis patients randomly divided into two groups: One group treated according to the routine protocol and the other group, alongside the routine protocol, took 50,000 IU vitamin D weekly for 12-14 weeks. Blood, endometrial fluid, and endometrial tissue samples were obtained from the control group and endometriosis groups before and after the intervention. We used in silico gene prioritization to study the relevance of CD44. The expression of CD44 was evaluated using the techniques of Western blot, real-time polymerase chain reaction, and ELISA. The eutopic endometrium of women with endometriosis in mid-secretory phase expressed significantly higher levels of CD44s, CD44V, and CD44v6. The concentration of soluble CD44 in the serum and endometrial fluid of endometriosis patients was higher than of healthy women. The expression level of CD44s, CD44V, and CD44v6 in the eutopic endometrium as well as the concentration of soluble CD44 in the endometrial fluid was decreased after modification of the circulating levels of 25(OH)D. It seems that the increased expression and extensive shedding of CD44 in eutopic endometrium play a role in the pathogenesis of endometriosis. Vitamin D can control and modify this process at least in part. We suggest more in vivo investigations on the therapeutic potency of vitamin D in endometriosis.

The Early Genes c-fos and c-jun: Potential Targets to Modulate Estrogen Action in Endometriosis?

Endometriosis is a common estrogen-dependent disorder. C-fos and c-jun are early transcription factors probably related to estradiol-dependent cell proliferation. C-fos gene expression is higher in endometriotic implants compared to normal endometrium and the distribution of c-Fos protein is higher in the stroma of endometriotic tissue. C-Jun expression is also more abundant in ectopic endometrial tissue. These findings point to an increased estrogen signaling in endometriosis and suggest that c-fos and c-jun could be potential targets to emerging treatments designed to affect selectively the endometriotic tissue, such as tissue-specific gene therapy.

CCL19/CCR7 contributes to the pathogenesis of endometriosis via PI3K/Akt pathway by regulating the proliferation and invasion of ESCs

PROBLEM

The level of CCL19 increased in the peritoneal fluid of women with endometriosis, but the precise mechanism of CCL19/CCR7 in the pathogenesis of endometriosis remains unknown.

METHODS

ELISA and immunohistochemistry were performed to analyze CCL19/CCR7 expressions in peritoneal fluid and endometrium from women with endometriosis (n = 38) and controls (n = 32). Cell proliferation and transwell invasion assays were applied to detect proliferation and invasion of human endometrial stromal cells (ESCs). Expressions of Bcl2, MMP2, MMP9, and p-AKT/AKT were analyzed by Western blot.

RESULTS

Peritoneal fluid concentration of CCL19 in patients with endometriosis was higher than that in controls. Those patients with moderate/severe endometriosis had significantly higher peritoneal fluid concentrations of CCL19 compared to those with minimal/mild endometriosis. Higher CCL19 and CCR7 were found in the endometrium with endometriosis compared to control. CCL19 significantly enhanced ESC proliferation and invasion through CCR7 via activating PI3K/Akt signal pathways. CCL19/CCR7 interaction significantly enhanced phosphorylation of Akt, Bcl2, MMP2, and MMP9 in ESCs.

CONCLUSION

These data indicate CCL19/CCR7 contributes to proliferation and invasion of ESCs, which are conducive to the pathogenesis of endometriosis through activating PI3K/Akt pathway.

Identification of global transcriptome abnormalities and potential biomarkers in eutopic endometria of women with endometriosis: A preliminary study

The etiology and pathophysiology of endometriosis remain unclear. The aim of the current study was to identify a candidate pathogenic gene, as well as potential biomarkers of endometriosis using messenger RNA (mRNA) sequencing (mRNA-seq). Twenty-three eutopic endometria from women with endometriosis and 20 endometria from control subjects were investigated. Eight eutopic endometria and five normal endometria were selected for mRNA-seq. Differentially expressed genes (DEGs) were identified and functional analysis was conducted. Validation of certain DEGs was performed in the remaining cases and control subjects by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A total of 72 DEGs (66 upregulated and 6 downregulated) were identified in samples from women with endometriosis and compared with the control subjects. High DEGs included those involved in various functions, such as extracellular matrix (ECM) remodeling, angiogenesis, cell proliferation and differentiation. Enriched by these DEGs, 100 Gene Ontology terms were identified as significantly important, particularly ‘ECM’ and ‘endogenous stimulus’. Validation using RT-qPCR indicated that matrix metallopeptidase 11, dual specificity phosphatase 1, Fos proto-oncogeneand serpin family E member 1 were significantly upregulated and adenosine deaminase 2 was significantly downregulated in the eutopic endometrium of patients with endometriosis. The identified DEGs may be involved in the pathogenesis of endometriosis and may be potential biomarkers in the eutopic endometrium. The current study provides a comprehensive, but preliminary insight for elucidating the mechanisms of endometriosis, which require further in-depth studies for confirmation.

Endometrial biomarkers for the non-invasive diagnosis of endometriosis

BACKGROUND

About 10% of reproductive-aged women suffer from endometriosis, which is a costly, chronic disease that causes pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but it is expensive and carries surgical risks. Currently, there are no non-invasive tests available in clinical practice that accurately diagnose endometriosis. This is the first diagnostic test accuracy review of endometrial biomarkers for endometriosis that utilises Cochrane methodologies, providing an update on the rapidly expanding literature in this field.

OBJECTIVES

To determine the diagnostic accuracy of the endometrial biomarkers for pelvic endometriosis, using a surgical diagnosis as the reference standard. We evaluated the tests as replacement tests for diagnostic surgery and as triage tests to inform decisions to undertake surgery for endometriosis.

SEARCH METHODS

We did not restrict the searches to particular study designs, language or publication dates. To identify trials, we searched the following databases: CENTRAL (2015, July), MEDLINE (inception to May 2015), EMBASE (inception to May 2015), CINAHL (inception to April 2015), PsycINFO (inception to April 2015), Web of Science (inception to April 2015), LILACS (inception to April 2015), OAIster (inception to April 2015), TRIP (inception to April 2015) and ClinicalTrials.gov (inception to April 2015). We searched DARE and PubMed databases up to April 2015 to identify reviews and guidelines as sources of references to potentially relevant studies. We also performed searches for papers recently published and not yet indexed in the major databases. The search strategies incorporated words in the title, abstract, text words across the record and the medical subject headings (MeSH).

SELECTION CRITERIA

We considered published peer-reviewed, randomised controlled or cross-sectional studies of any size that included prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE).

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from each study and performed a quality assessment. For each endometrial diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis and calculated the estimates of sensitivity and specificity. We considered two or more tests evaluated in the same cohort as separate data sets. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient data were available. The predetermined criteria for a clinically useful test to replace diagnostic surgery was one with a sensitivity of 94% and a specificity of 79%. The criteria for triage tests were set at sensitivity at or above 95% and specificity at or above 50%, which in case of negative results rules out the diagnosis (SnOUT test) or sensitivity at or above 50% with specificity at or above 95%, which in case of positive result rules in the diagnosis (SpIN test).

MAIN RESULTS

We included 54 studies involving 2729 participants, most of which were of poor methodological quality. The studies evaluated endometrial biomarkers either in specific phases of the menstrual cycle or outside of it, and the studies tested the biomarkers either in menstrual fluid, in whole endometrial tissue or in separate endometrial components. Twenty-seven studies evaluated the diagnostic performance of 22 endometrial biomarkers for endometriosis. These were angiogenesis and growth factors (PROK-1), cell-adhesion molecules (integrins α3β1, α4β1, β1 and α6), DNA-repair molecules (hTERT), endometrial and mitochondrial proteome, hormonal markers (CYP19, 17βHSD2, ER-α, ER-β), inflammatory markers (IL-1R2), myogenic markers (caldesmon, CALD-1), neural markers (PGP 9.5, VIP, CGRP, SP, NPY, NF) and tumour markers (CA-125). Most of these biomarkers were assessed in single studies, whilst only data for PGP 9.5 and CYP19 were available for meta-analysis. These two biomarkers demonstrated significant diversity for the diagnostic estimates between the studies; however, the data were too limited to reliably determine the sources of heterogeneity. The mean sensitivities and specificities of PGP 9.5 (7 studies, 361 women) were 0.96 (95% confidence interval (CI) 0.91 to 1.00) and 0.86 (95% CI 0.70 to 1.00), after excluding one outlier study, and for CYP19 (8 studies, 444 women), they were were 0.77 (95% CI 0.70 to 0.85) and 0.74 (95% CI 0.65 to 84), respectively. We could not statistically evaluate other biomarkers in a meaningful way. An additional 31 studies evaluated 77 biomarkers that showed no evidence of differences in expression levels between the groups of women with and without endometriosis.

AUTHORS' CONCLUSIONS

We could not statistically evaluate most of the biomarkers assessed in this review in a meaningful way. In view of the low quality of most of the included studies, the findings of this review should be interpreted with caution. Although PGP 9.5 met the criteria for a replacement test, it demonstrated considerable inter study heterogeneity in diagnostic estimates, the source of which could not be determined. Several endometrial biomarkers, such as endometrial proteome, 17βHSD2, IL-1R2, caldesmon and other neural markers (VIP, CGRP, SP, NPY and combination of VIP, PGP 9.5 and SP) showed promising evidence of diagnostic accuracy, but there was insufficient or poor quality evidence for any clinical recommendations. Laparoscopy remains the gold standard for the diagnosis of endometriosis, and using any non-invasive tests should only be undertaken in a research setting. We have also identified a number of biomarkers that demonstrated no diagnostic value for endometriosis. We recommend that researchers direct future studies towards biomarkers with high diagnostic potential in good quality diagnostic studies.

Intracellular Wnt/Beta-Catenin Signaling Underlying 17beta-Estradiol-Induced Matrix Metalloproteinase 9 Expression in Human Endometriosis

Extracellular matrix remodeling is necessary for ectopic endometrium implantation. Many studies have shown an increased expression of matrix metalloproteinase 9 (MMP9) in the ectopic endometrium of endometriosis. However, the signaling pathways and cellular effects related to this process remain incompletely elucidated. The objective of our study was to investigate the association between MMP9 and the Wnt signaling pathway under the regulation of 17beta-estradiol (E2) in endometrial stromal cells. We found that MMP9 was elevated in tissues from women with endometriosis compared with normal women. Furthermore, MMP9 and beta-catenin increased concurrently in a time- and dose-dependent manner after E2 treatment. To clarify the relationship between MMP9 and beta-catenin, we performed luciferase promoter reporter and chromatin immunoprecipitation assays. A beta-catenin/TCF3/LEF1 complex bound to a specific site on the MMP9 promoter that promoted MMP9 gene and protein expression. The promotion of MMP9 by the Wnt signaling pathway under the regulation of E2 may contribute to the pathophysiology of this disease.

Effect of the non-specific matrix metalloproteinase inhibitor Doxycycline on endometriotic implants in an experimental rat model

The aim of this study was to investigate the possible therapeutic effects of Doxycycline (Dox) on endometriotic lesions in an experimental rat model. Thirty-seven female Wistar albino rats with surgically induced endometriosis were randomized and divided into four groups. The rats were administered 5 mg/kg/day oral Dox in Group 1 (low-dose Dox group, n=9), 20 mg/kg/day oral Dox in Group 2 (high-dose Dox group, n=10) and 1 mg/kg single dose, subcutaneous leuprolide acetate in Group 3 (leuprolide acetate group, n=9). The rats in Group 4 (control group, n=9) were given no medication. The rats received medication for three weeks and were then sacrificed to evaluate the morphological and histological features of the implants. Matrix metalloproteinase (MMP)-9 immunoreactivity of the implants was also evaluated. The size of the endometriotic implants decreased in Groups 1-3 but statistically significant differences were not observed among the groups. The mean surface area of the endometriotic implants decreased from 69.3±30.8 to 52.1±27.0 mm² in Group 1 (P>0.05), from 60.2±18.9 to 38.6±28.7 mm² in Group 2 (P>0.05) and from 58.1±33.1 to 26±9.0 mm² in Group 3 (P=0.03). The epithelial MMP-9 immunohistochemical score was significantly higher in Group 1 and lower in Group 3 when compared with the control group (Group 4) (P=0.042 and P=0.014, respectively). When the stromal MMP-9 immunohistochemical and histopathological scores of the endometriotic implants were compared, no statistically significant differences were found among the groups. Although there was no statistically significant difference, Dox reduced the endometriotic implant area in the rat endometriosis model. Further studies are required to investigate the potential efficacy of Dox in endometriosis due to its widespread use and tolerability.

Somatostatin analogs regress endometriotic implants in rats by decreasing implant levels of vascular endothelial growth factor and matrix metaloproteinase 9

OBJECTIVE

To examine the effect of somatostatin analogs on surgically induced endometriosis in rat models.

STUDY DESIGN

Endometrial tissue was implanted onto the abdominal peritoneum of 26 rats that were randomized into 3 groups. The rats in group 1(n = 9) were subcutaneously administered with 0.02 mg/kg/d of octreotide (a short-acting analog)for 28 days . The rats in group 2 (n = 8) were subcutaneously injected with 20 mg/kg of a single dose of a long-acting analogue lanreotide The rats in group 3 were given no medication and served as controls (n = 9).

RESULTS

Mean volume and histologic score of implants in groups 1 (P < .01 and P < .05, respectively) and 2 (P < .01and P < .05, respectively) were significantly lower than that in group 3. There were significant reductions in vascular endothelial growth factor (VEGF) and matrix metalloproteinase 9 (MMP-9) immunoreactivities in group 1 (0.67 ± 0.50 and 1.22 ± 0.44, respectively; both P < .01) and group 2 (0.71 ± 0.48 and 0.86 ± 0.69, respectively; both P < .01) when compared with the control group (1.78 ± 0.83 and 2.11 ± 0.78, respectively).

CONCLUSION

Somatostatin analogs has regressed significantly the size of the endometriotic implants and caused atrophy of these lesions in rats by decreasing explant levels of VEGF and MMP-9.

Selective inhibition of prostaglandin E2 receptors EP2 and EP4 inhibits invasion of human immortalized endometriotic epithelial and stromal cells through suppression of metalloproteinases

Prostaglandin E2 (PGE2) plays an important role in the pathogenesis of endometriosis. We recently reported that inhibition of COX-2 decreased migration as well as invasion of human endometriotic epithelial and stromal cells. Results of the present study indicates that selective inhibition of PGE2 receptors EP2 and EP4 suppresses expression and/or activity of MMP1, MMP2, MMP3, MMP7 and MMP9 proteins and increases expression of TIMP1, TIMP2, TIMP3, and TIMP4 proteins and thereby decreases migration and invasion of human immortalized endometriotic epithelial and stromal cells into matrigel. The interactions between EP2/EP4 and MMPs are mediated through Src and β-arrestin 1 protein complex involving MT1-MMP and EMMPRIN in human endometriotic cells. These novel findings provide an important molecular and cellular framework for further evaluation of selective inhibition of EP2 and EP4 as potential nonsteroidal therapy for endometriosis in childbearing-age women.

Doxycycline causes regression of endometriotic implants: a rat model

BACKGROUND

Doxycycline (Dox) has a number of non-antibiotic properties. One of them is the inhibition of matrix metalloproteinase (MMP) activity. The aim of this study was to assess the effects of Dox in a rat endometriosis model.

METHODS

Endometriosis was surgically induced in 40 rats by transplanting of endometrial tissue. After 3 weeks, repeat laparotomies were performed to check the implants and the animals were randomized into four groups: Group I, low-dose Dox (5 mg/kg/day); Group II, high-dose Dox (40 mg/kg/day); Group III, leuprolide acetate 1 mg/kg single dose, s.c.; and Group VI (controls), no medication. The treatment, initiated on the day of surgery and continuing for 3 weeks, was administered to the study groups. Three weeks later, the rats were euthanized and the implants were evaluated morphologically and histologically for immunoreactivity of MMP-2 and -9, and interleukin-6 (IL-6) concentration in the peritoneal fluid was assayed.

RESULTS

Treatment with leuprolide acetate, or high-dose or low-dose Dox caused significant decreases in the implant areas compared with the controls (P = 0.03, P = 0.006, and P = 0.001, respectively). IL-6 levels in peritoneal fluid decreased in Group I (P = 0.02) and Group III (P < 0.05). MMP H scores were significantly lower in the group that received low-dose Dox in both epithelial and stromal MMP-2 and -9 immunostaining when compared with the control group [P = 0.048, P = 0.002, P = 0.007 and P = 0.002, respectively, MMP-2 (epithelia), MMP-2 (stroma), MMP-9 (epithelia) and MMP-9 (stroma)].

CONCLUSIONS

Low-dose Dox caused regression of endometriosis in this experimental rat model.

The role of matrix metalloproteinases in the pathogenesis of endometriosis

Endometriosis is a benign, estrogen-dependent disease with an obscure etiology. Even the most widely accepted theory of retrograde menstruation cannot satisfactorily explain the development of endometriosis due to the many gaps in our understanding of its pathophysiology. Although most women have retrograde menstruation; only some develop endometriosis. Apart from simply being present in the peritoneal cavity, the endometrial cells are able to attach to, invade the peritoneum, and proliferate to create and maintain an endometriotic lesion. Matrix metalloproteinases (MMPs) are a group of enzymes that degrade the extracellular matrix. These enzymes participate in the histologic changes of the endometrium during the menstrual cycle with generally a higher expression during the menstrual and proliferative phase of the endometrium and a decreased expression during the secretory phase. As noted above, not only do these enzymes play a crucial factor in the cycling endometrium but the degradation of extracellular matrix is essential for the endometrial cells to invade the peritoneum and to develop an endometriotic lesion as well. The aim of this review is to describe the altered expression of MMPs in the development of endometriosis.

High expression levels of cyclin B1 and Polo-like kinase 1 in ectopic endometrial cells associated with abnormal cell cycle regulation of endometriosis

OBJECTIVE

To investigate the possible roles of cyclin B1/cyclin-dependent kinase (cdc2) and Polo-like kinase 1 (Plk1) in the pathogenesis of endometriosis.

DESIGN

A case-control study.

SETTING

University hospital.

PATIENT(S)

Patients with or without endometriosis were diagnosed by pathological examination or laparoscopy. The patients with the following criteria within the past 6 months were excluded: endocrine or inflammatory diseases, pregnancy or lactation, hormonal therapy, and neoplasm in the uterine cavity.

INTERVENTION(S)

Eutopic and ectopic endometria were obtained at the time of surgery. Blood was collected on the same day as surgery.

MAIN OUTCOME MEASURE(S)

The mRNA/protein expression and localization of cyclin B1, cdc2, and Plk1 in endometrium, and serum levels of E(2) and P.

RESULT(S)

The expression levels of cyclin B1 and Plk1, but not cdc2, in ectopic endometria were significantly higher than in eutopic endometria. The immunohistochemical staining of cyclin B1 and Plk1 was detected in the nuclei of ectopic and eutopic endometrial cells. Furthermore, ectopic endometrial expression levels of cyclin B1 or Plk1 were positively correlated with serum E(2) levels.

CONCLUSION(S)

Cyclin B1 and Plk1 may play important roles in the pathogenesis of endometriosis by mediating ectopic endometrial cell proliferation under regulation of ovarian hormones.