Oxidative cell injury as a predictor of endometriosis progression

Bibliometric and visual analysis on oxidative stress in gynecological and reproductive diseases: A systematic review

BACKGROUND

The imbalance between the generation and elimination of reactive oxygen species (ROS) is defined as oxidative stress (OS). Elevated levels of OS are implicated in various diseases, especially in gynecological and reproductive disorders. The abundance of recent literature makes it challenging to assimilate all available information. This bibliometric analysis seeks to depict the research landscape of OS in gynecological and reproductive diseases and to identify future hotspots and trends.

METHODS

The Web of Science Core Collection served as the source for articles related to OS in gynecological and reproductive diseases. CtieSpace and VOSviewer software were utilized to analyzed countries/regions, institutions, journals, authors, and keywords of all eligible articles.

RESULTS

A total of 1423 articles were included. There was a gradual increase in the number of publications in this field. The USA maintained the highest number of publications, with 372 articles. Cleveland Clinic was the leading institution in terms of publication volume, contributing 67 articles. In total, 6925 authors were identified. Agarwal A as the most frequently co-cited author, received 812 citations across 43 publications. The predominant clusters included "placenta," "polycystic ovary syndrome," "male infertility," and "oocyte quality." Notably, "oocyte quality'" was identified as a current key research topic.

CONCLUSION

There was an uptrend in the number of articles addressing OS in gynecological and reproductive diseases. However, international collaboration and exchange were limited. The topic of male infertility had remained a consistent area of interest, and research on oocyte quality is poised to become a potential focal point in the future.

Current Understanding of and Future Directions for Endometriosis-Related Infertility Research with a Focus on Ferroptosis

BACKGROUND

To date, the development of therapy for endometriosis and disease-related infertility remains a major challenge. Iron overload caused by periodic bleeding is a hallmark of endometriosis. Ferroptosis is an iron- and lipid-reactive oxygen species-dependent type of programmed cell death that is distinct from apoptosis, necrosis, and autophagy. This review summarizes the current understanding of and future directions for the research and treatment of endometriosis and disease-related infertility, with the main focus on the molecular basis of ferroptosis in endometriotic and granulosa cells.

METHODS

Papers published between 2000 and 2022 in the PubMed and Google Scholar databases were included in this review.

RESULTS

Emerging evidence suggests that ferroptosis is closely linked to the pathophysiology of endometriosis. Endometriotic cells are characterized by ferroptosis resistance, whereas granulosa cells remain highly susceptible to ferroptosis, suggesting that the regulation of ferroptosis is utilized as an interventional target for research into the treatment of endometriosis and disease-related infertility. New therapeutic strategies are urgently needed to efficiently kill endometriotic cells while protecting granulosa cells.

CONCLUSIONS

An analysis of the ferroptosis pathway in in vitro, in vivo, and animal research enhances our understanding of the pathogenesis of this disease. Here, we discuss the role of ferroptosis modulators as a research approach and potential novel treatment for endometriosis and disease-related infertility.

Endometriosis Stem Cells as a Possible Main Target for Carcinogenesis of Endometriosis-Associated Ovarian Cancer (EAOC)

Endometriosis is a serious recurrent disease impairing the quality of life and fertility, and being a risk for some histologic types of ovarian cancer defined as endometriosis-associated ovarian cancers (EAOC). The presence of stem cells in the endometriotic foci could account for the proliferative, migrative and angiogenic activity of the lesions. Their phenotype and sources have been described. The similarly disturbed expression of several genes, miRNAs, galectins and chaperones has been observed both in endometriotic lesions and in ovarian or endometrial cancer. The importance of stem cells for nascence and sustain of malignant tumors is commonly appreciated. Although the proposed mechanisms promoting carcinogenesis leading from endometriosis into the EAOC are not completely known, they have been discussed in several articles. However, the role of endometriosis stem cells (ESCs) has not been discussed in this context. Here, we postulate that ESCs may be a main target for the carcinogenesis of EAOC and present the possible sequence of events resulting finally in the development of EAOC.

Endometrial DNA damage response is modulated in endometriosis

STUDY QUESTION

Is the DNA damage response (DDR) dysregulated in the eutopic endometrium of women with endometriosis?

SUMMARY ANSWER

Endometrial expression of genes involved in DDR is modulated in women with endometriosis, compared to those without the disease.

WHAT IS KNOWN ALREADY

Ectopic endometriotic lesions are reported to harbour somatic mutations, thereby hinting at dysregulation of DDR and DNA repair pathways. However, it remains inconclusive whether the eutopic endometrium also manifests dysregulated DDR in endometriosis.

STUDY DESIGN, SIZE, DURATION

For this case-control study conducted between 2015 and 2019, eutopic endometrial (E) samples (EE- from women with endometriosis, CE- from women without endometriosis) were collected in either mid-proliferative (EE-MP, n = 23; CE-MP, n = 17) or mid-secretory (EE-MS, n = 17; CE-MS, n = 9) phases of the menstrual cycle. This study compares: (i) DNA damage marker localization, (ii) expression of DDR genes and (iii) expression of DNA repair genes in eutopic endometrial samples from women with and without endometriosis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included (i) 40 women (aged 31.9 ± 0.81 years) with endometriosis and (ii) 26 control women (aged 31.4 ± 1.02 years) without endometriosis. Eutopic endometrial samples from the two groups were divided into different parts for histological analysis, immunohistochemistry, RNA extraction, protein extraction and comet assays. Eighty-four genes of relevance in the DNA damage signalling pathway were evaluated for their expression in eutopic endometrial samples, using RT2 Profiler PCR arrays. Validations of the expression of two GADD (Growth Arrest DNA Damage Inducible) proteins - GADD45A and GADD45G were carried out by immunoblotting. DNA damage was assessed by immunohistochemical localization of γ-H2AFX (a phosphorylated variant of histone H2AX) and 8-OHdG (8-hydroxy-2'-deoxyguanosine). RNA sequencing data from mid-proliferative (EE-MP, n = 4; CE-MP, n = 3) and mid-secretory phase (EE-MS and CE-MS, n = 4 each) endometrial samples were scanned to compare the expression status of all the genes implicated in human DNA repair. PCNA (Proliferating Cell Nuclear Antigen) expression was determined to assess endometrial proliferation. Residual DNA damage in primary endometrial cells was checked by comet assays. Public datasets were also scanned for the expression of DDR and DNA repair genes as our RNASeq data were limited by small sample size. All the comparisons were made between phase-matched endometrial samples from women with and without endometriosis.

MAIN RESULTS AND THE ROLE OF CHANCE

Endometrial expression of DDR genes and intensity of immunolocalized γ-H2AFX were significantly (P < 0.05) higher in EE, compared to CE samples. DDR proteins, especially those belonging to the GADD family, were found to be differentially abundant in EE, as compared to CE. These patterns were evident in both mid-proliferative and mid-secretory phases. Intriguingly, higher DDR was associated with increased cell proliferation in EE-MP, compared to CE-MP. Furthermore, among the differentially expressed transcripts (DETs) encoded by DNA repair genes, the majority showed up-regulation in EE-MP, compared to CE-MP. Interestingly, CE-MP and EE-MP had a comparable percentage (P > 0.05) of cells with residual DNA damage. However, unlike the mid-proliferative phase data, many DETs encoded by DNA repair genes were down-regulated in EE-MS, compared to CE-MS. An analysis of the phase-matched control and endometriosis samples included in the GSE51981 dataset available in the Gene Expression Omnibus database also revealed significant (P < 0.05) alterations in the expression of DDR and DNA repair genes in EE, compared to CE.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The study was conducted on a limited number of endometrial samples. Also, the study does not reveal the causes underlying dysregulated DDR in the eutopic endometrium of women with endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Alterations in the expression of DDR and DNA repair genes indirectly suggest that eutopic endometrium, as compared to its healthy counterpart, encounters DNA damage-inducing stimuli, either of higher strength or for longer duration in endometriosis. It will be worthwhile to identify the nature of such stimuli and also explore the role of higher genomic insults and dysregulated DDR/DNA repair in the origin and/or progression of endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the Department of Biotechnology and Indian Council of Medical Research, Government of India. No conflict of interest is declared.

A delicate redox balance between iron and heme oxygenase-1 as an essential biological feature of endometriosis

BACKGROUND

Recent studies have focused on the role of oxidative stress, which may be implicated in the development, progression, and pathophysiology of endometriosis.

AIM OF THE STUDY

The aim of this study is to investigate the redox balance of endometriosis by simultaneously measuring iron-related compounds (total iron, heme iron, free iron, oxyhemoglobin [oxyHb], methemoglobin [metHb] and 8-hydroxy-2-deoxy guanosine [8-OHdG]) and antioxidants (bilirubin, heme oxygenase-1 [HO-1] and total antioxidant capacity [TAC]).

METHODS

This study includes 236 histopathologically confirmed cases (178 cases of endometriosis and 58 cases of non-endometriosis). Cyst fluid samples were collected from patients admitted to the Department of Gynecology, Nara Medical University, Kashihara, Japan, for surgery.

RESULTS

Age at diagnosis (p <0.001), the maximum diameter of the cyst (p <0.001) and CA125 levels (p <0.001) differed significantly between the two groups. Total iron, heme iron, free iron, metHb, and oxyHb were markedly higher in endometriosis compared to non-endometriosis. Bilirubin, HO-1 and TAC were significantly higher in endometriosis patients compared with those from non-endometriosis patients. In endometriosis, total iron showed a positive correlation with HO-1 (r, 0.518, p = 0.001), but there were no antioxidants that correlated with iron in non-endometriosis. Iron and HO-1 did not correlate with age or tumor size.

CONCLUSIONS

HO-1 may regulate the delicate balance of iron-induced oxidative stress in endometriotic cyst fluid.

Eutopic endometrium from women with endometriosis and chlamydial endometritis share immunological cell types and DNA repair imbalance: A transcriptome meta-analytical perspective

The aim of this study was to identify the key similarities between the eutopic endometrium of women with endometriosis and chlamydia-induced endometritis taking into account tissue microenvironment heterogeneity, transcript gene profile, and enriched pathways. A meta-analysis of whole transcriptome microarrays was performed using publicly available data, including samples containing both glandular and stromal endometrial components. Control samples were obtained from women without any reported pathological condition. Only samples obtained during the proliferative menstrual phase were included. Cellular tissue heterogeneity was predicted using a method that integrates gene set enrichment and deconvolution approaches. The batch effect was estimated by principal variant component analysis and removed using an empirical Bayes method. Differentially expressed genes were identified using an adjusted p-value < 0.05 and fold change = 1.5. The protein-protein interaction network was built using the STRING database and interaction score over 400. The Molecular Signatures Database was used to analyse the functional enrichment analysis. Both conditions showed similarities in cell types in the microenvironment, particularly CD4⁺ and CD8⁺ Tem cells, NKT cells, Th2 cells, basophils, and eosinophils. With regards to the regulation of cellular senescence and DNA integrity/damage checkpoint, which are commonly enriched pathways, 21 genes were down-regulated and directly related to DNA repair. Compared to the endometriosis samples, some chlamydial endometritis samples presented a lack of enriched immune pathways. Our results suggest that both conditions show similar distributions of microenvironment cell types, the downregulation of genes involved in DNA repair and cell cycle control, and pathways involved in immune response evasion.

Analysis of IVF/ICSI Outcomes in Endometriosis Patients With Recurrent Implantation Failure: Influence on Cumulative Live Birth Rate

OBJECTIVE

To study the influence of endometriosis activity on the pregnancy outcomes of patients with recurrent implantation failure (RIF) in in-vitro fertilization/intra-cytoplasmic sperm injection (IVF/ICSI) cycles. The pregnancy outcomes were compared between RIF patients with endometriosis who received treatment at different occasions to explore the appropriate treatment plan for these patients and to optimize the pregnancy-support strategies.

DESIGN

Ambispective cohort study.

METHODS

A total of 330 patients with endometriosis were enrolled from 2008 to 2018 and included 1043 IVF/ICSI cycles. All patients were diagnosed with RIF after IVF/ICSI. Patients were assigned to three subtypes according to different control states of endometriosis, including the untreated, early-treatment, and late-treatment groups. The clinical pregnancy rate, live birth rate, and cumulative live birth rate of endometriosis patients with RIF were the main outcomes; additionally, the fertilization rate, available embryonic rate, and high-quality embryonic rate were also compared.

RESULTS

The early-treatment and late-treatment groups showed higher cumulative live birth rate than the untreated group (early-treated 43.6% vs. late-treated 46.3% vs. untreated 27.7%, P<0.001), though patients in the two treatment groups had higher rates of adenomyosis and ovarian surgery. The two treatment group showed a better laboratory result than the untreated and especially, the early-treatment group. The untreated group (46.24%) had a lower IVF fertilization rate than the treated group (early-treated [64.40%] and late-treated [60.27%] (P<0.001). In addition, the rates of available embryos and high-quality embryos in the early-treated group were much higher those that in the untreated group (90.30% vs. 85.20%, 76.50% vs. 64.47%). Kaplan-Meier curve showed that patients in the untreated group needed a mean of 23.126 months to achieve one live birth; whereas those in the treated group needed a comparatively shorter duration (early-treated: 18.479 ± 0.882 months and late-treated: 14.183 ± 1.102 months, respectively).

CONCLUSION

Endometriosis has a negative influence on IVF/ICSI outcome. The control of endometriosis activity can result in a higher cumulative live birth rate in patients. It is necessary for endometriosis patients to receive medical treatment to achieve a better prognosis especially for those with RIF.

Genetic variants in the nucleotide excision repair genes are associated with the risk of developing endometriosis

Endometriosis is a major health issue among women of reproductive age. However, its etiology has not yet been completely understood. We investigated 10 single nucleotide polymorphisms from six novel nucleotide excision repair genes and the susceptibility to endometriosis. A total of 153 patients with endometriosis were recruited during 2000-2010 from central Taiwan. Pathological confirmation was necessary for all patients, and exclusion criteria included the presence of leiomyoma, adenomyosis, or cancer of the uterine, cervix, or ovary and a prescription of hormone therapy. Furthermore, a total of 636 age-matched individuals without endometriosis were recruited during the same time period from central Taiwan. The polymerase chain reaction coupled with restriction fragment length polymorphism methodology was applied for genotyping. The multivariate logistic regression analysis showed that subjects carrying the ERCC1 rs11615 TT (OR = 2.04, 95% CI = 1.36-3.41), ERCC2 rs1799793 AA (OR = 1.86, 95% CI = 1.14-3.11), and ERCC6 rs2228528 AA genotypes (OR = 1.79, 95% CI = 1.13-2.83) exhibited significantly increased risks of developing endometriosis compared with their counterparts carrying the wild-type genotypes. This study suggests that certain single nucleotide polymorphisms of nucleotide excision repair genes excision repair cross-complementation group 1 (ERCC1, ERCC2, and ERCC6) predispose women to the development of endometriosis.

Amine oxidase 3 is a novel pro-inflammatory marker of oxidative stress in peritoneal endometriosis lesions

Endometriosis is a common gynaecological disease of women in reproductive age, and is thought to arise from retrograde menstruation and implantation of endometrial tissue, mostly into the peritoneal cavity. The condition is characterized by a chronic, unresolved inflammatory process thereby contributing to pain as cardinal symptom in endometriosis. Elevated reactive oxygen species (ROS) and oxidative stress have been postulated as factors in endometriosis pathogenesis. We here set out for a systematic study to identify novel mechanisms and pathways relating to oxidative stress in ectopic peritoneal lesions. Using combined proteomic and transcriptomic approaches, we identified novel targets including upregulated pro-oxidative enzymes, such as amine oxidase 3/vascular adhesion protein 1 (AOC3/VAP1) as well as downregulated protective factors, in particular alkenal reductase PTGR1 and methionine sulfoxide reductase. Consistent with an altered ROS landscape, we observed hemoglobin / iron overload, ROS production and lipid peroxidation in ectopic lesions. ROS-derived 4-hydroxy-2-nonenal induced interleukin IL-8 release from monocytes. Notably, AOC3 inhibitors provoked analgesic effects in inflammatory pain models in vivo, suggesting potential translational applicability.

Vibrational characterization of granulosa cells from patients affected by unilateral ovarian endometriosis: New insights from infrared and Raman microspectroscopy

Endometriosis is a chronic gynaecological disease characterised by the presence of endometrial cells in extra-uterine regions. One of the main factors impacting on the fertility of women affected by endometriosis is the poor oocyte quality. Granulosa Cells (GCs) regulate oocyte development and maintain the appropriate microenvironment for the acquisition of its competence; hence, the dysregulation of these functions in GCs can lead to severe cellular damages also in oocytes. In this study, luteinized GCs samples were separately collected from both ovaries of women affected by Unilateral Ovarian Endometriosis and analysed by infrared and Raman microspectroscopy. The spectral data were compared with those of GCs from women with diagnosis of tubal, idiopathic or male infertility (taken as control group). The coupling of these two spectroscopic techniques sheds new light on the alteration induced by this pathology on GCs metabolism and biochemical composition. In fact, the study revealed similar biochemical modifications in GCs from both ovaries of women affected by unilateral ovarian endometriosis, such as the alteration of the protein pattern, the induction of oxidative stress mechanisms, and the deregulation of lipid and carbohydrate metabolisms. These evidences suggest that unilateral endometriosis impairs the overall ovarian functions, causing alterations not only in the ovary with endometriotic lesions but also in the contralateral "healthy" one.

MiR-210-3p protects endometriotic cells from oxidative stress-induced cell cycle arrest by targeting BARD1

Endometriosis is associated with benign but adversely developed cysts in the extrauterine environment. The oxidative imbalanced environment induces DNA damage and affects cell cycle progression of endometrial stromal cells (ESCs) and endometrial epithelial cells, but how endometriotic cells maintain proliferation in the presence of oxidative stress is not clear. Growing evidence has indicated that the ectopic hypoxic microenvironment and oxidative stress can stimulate the growth of endometriotic cells, which is mainly due to the increase of HIF-1α. We found that the master hypoxia-associated miRNA miR-210-3p was increased in stromal and glandular cells of ectopic lesions compared with that of eutopic and normal endometria and was consistent with the expression of HIF-1α and the local oxidative stress-induced DNA damage predictor 8-OHdG. Moreover, miR-210-3p was upregulated in ESCs and Ishikawa cells under hypoxic conditions but not in normoxic culture. Knockdown of miR-210-3p induced a G2/M arrest of ESCs and Ishikawa cells under hypoxia, while no effect was found under normoxia. BARD1 was identified as a target of miR-210-3p. BARD1 expression was decreased in endometriotic tissues compared with eutopic and normal endometria and negatively correlated with the expression of miR-210-3p. Multivariate regression analysis showed that BARD1 downregulation could serve as an indicator for endometriotic severity. Our results suggest that miR-210-3p attenuates the G2/M cell cycle checkpoint by inactivating BRCA1 complex function in response to DNA damage under hypoxia via targeting the 3′ untranslated region of BARD1 mRNA. Endometriotic mouse model experiments showed that intraperitoneal injection of the miR-210-3p inhibitor or vitamin C suppressed the growth of endometriotic lesions. Together, our results demonstrate that endometriotic cells inhibit BARD1/BRCA1 function by upregulating miR-210-3p, which might be the underlying mechanism for endometriotic cell maintenance of growth in oxidative stress. Furthermore, inhibition of miR-210-3p and administration of vitamin C are promising approaches for the treatment of endometriosis.

Three-dimensionally-printed models in reproductive surgery: systematic review and clinical applications

INTRODUCTION

3D printing has wide application in medicine while it provides customizability and precision for anatomical model development. Our aims were to perform a systematic review and to explore the use of 3D printing applications on human reproduction and reproductive surgery.

EVIDENCE ACQUISITION

We have performed a systematic review in PubMed database to assess previous publications within 3D printing in human reproduction and gynecology. We have developed 3D models according to patients' magnetic resonance images (MRI). MRI were transformed into DICOM images that originated our 3D virtual models and PolyJet technology was applied for the printing process. We included two infertile patients in reproductive age with surgical indication for hysteroscopy septoplasty and myomectomy.

EVIDENCE SYNTHESIS

Of 1965 studies searched, we excluded 1934 publications based on their titles. Abstracts of 31 remained studies were read, and 24 studies were selected for full-text analysis. We included 11 studies for the systematic review, based on our eligibility criteria. We have designed four 3D models (uterus, ovaries, uterine cervix and uterus with fibroids) that provided enriched information to improve pre-surgical planning, medical training, fertility-sparing surgery, patient comprehension of surgical procedures and assisted reproduction applications.

CONCLUSIONS

3D models for human reproduction are feasible. They might improve assisted reproductive techniques, help in pre-surgical planning for reproductive surgeries, and provide accurate measures of ovarian reserve. Besides, we see future applications in endometrioma research and in the fabrication of devices, such as embryo transfer catheter and a 3D printed embryo.

Cancer driver mutations in endometriosis: Variations on the major theme of fibrogenesis

BACKGROUND

One recent study reports cancer driver mutations in deep endometriosis, but its biological/clinical significance remains unclear. Since the natural history of endometriosis is essentially gradual progression toward fibrosis, it is thus hypothesized that the six driver genes reported to be mutated in endometriosis (the RP set) may play important roles in fibrogenesis but not necessarily malignant transformation.

METHODS

Extensive PubMed search to see whether RP and another set of driver genes not yet reported (NR) to be mutated in endometriosis have any roles in fibrogenesis. All studies reporting on the role of fibrogenesis of the genes in both RP and NR sets were retrieved and evaluated in this review.

RESULTS

All six RP genes were involved in various aspects of fibrogenesis as compared with only three NR genes. These nine genes can be anchored in networks linking with their upstream and downstream genes that are known to be aberrantly expressed in endometriosis, piecing together seemingly unrelated findings.

CONCLUSIONS

Given that somatic driver mutations can and do occur frequently in physiologically normal tissues, it is argued that these mutations in endometriosis are not necessarily synonymous with malignancy or premalignancy, but the result of enormous pressure for fibrogenesis.

Comparison of redox parameters in ovarian endometrioma and its malignant transformation

The present study aimed to evaluate the levels of oxidative stress and antioxidant markers in benign endometrioma (OE) and its malignant transformation [endometriosis-associated ovarian cancer (EAOC)] by measuring 8-hydroxy-2-deoxyguanosine (8-OHdG), heme oxygenase-1 (HO-1) and total antioxidant capacity (TAC/Heme-iron) alterations associated with disease progression. Cyst fluid samples from 44 patients with OE and 14 patients with EAOC were studied using an enzyme-linked immunosorbent assay. A χ² test, t-test and Pearson correlation test were performed using SPSS version 22.0. The cut-off point, sensitivity and specificity of each marker for EAOC diagnosis were evaluated by receiver operating characteristic curve analysis. Cyst fluid 8-OHdG and HO-1 levels in the EAOC group were significantly decreased compared with the OE subjects (P=0.013 and P<0.001, respectively). The levels of TAC/Heme-iron in patients with EAOC were significantly higher compared with those in the OE subjects (P<0.001). The present study demonstrated a positive correlation between 8-OHdG and HO-1 levels (P=0.012). HO-1 exhibited the highest discriminant value for EAOC (Area Under the Curve=0.901). The optimal cut-off point of HO-1 for the diagnosis of EAOC was 2.314 ng/ml, with a sensitivity and specifity of 95.2 and 85.7%, respectively. The present study revealed a clear separation between the overall redox state in OE and EAOC. It was concluded that characteristic alterations in important factors in redox may be helpful for understanding the pathogenesis of the malignant transformation of endometriosis.

Endometriosis Is a Cause of Infertility. Does Reactive Oxygen Damage to Gametes and Embryos Play a Key Role in the Pathogenesis of Infertility Caused by Endometriosis?

Approximately, 10-15% of women of reproductive age are affected by endometriosis, which often leads to infertility. Endometriosis often has an inherited component, and several causative predisposing factors are hypothesized to underlie the pathogenesis of endometriosis. One working hypothesis is the theory of retrograde menstruation. According to the theory of retrograde menstruation, components of refluxed blood, including apoptotic endometrial tissue, desquamated menstrual cells, lysed erythrocytes, and released iron, induce inflammation in the peritoneal cavity. This in turn activates macrophage release of reactive oxygen species (ROS), leading to oxidative stress via the respiratory burst. Refluxed blood promotes the Fenton reaction, terminating in the production of hydroxyl radical, the most potently destructive ROS. In this article, we review the papers that demonstrate decreased quantity and quality of oocytes and embryos retrieved from IVF/ICSI patients with endometriosis. We discuss literature data demonstrating that ROS are generated in endometriotic tissues that have physical proximity to gametes and embryos, and demonstrating adverse impacts on oocyte, sperm and embryo microtubule apparatus, chromosomes, and DNA. Data that addresses the notions that endometriosis causes oocyte and fetal aneuploidy and that these events are mediated by ROS species are also discussed. Literature data are also discussed that employ use of anti-oxidant molecules to evaluate the importance of ROS-mediated oxidative damage in the pathogenesis of endometriosis. Studies are discussed that have employed anti-oxidants compounds as therapeutics to improve oocyte and embryo quality in infertile subjects, and improve fertility in patients with endometriosis.

Increased serum levels of mBDNF in women with minimal and mild endometriosis have no predictive power for the disease

The objective of our pilot clinical, prospective study was to determine the serum levels of mature brain-derived neurotrophic factor, in of women with endometriosis and controls and explore whether mature brain-derived neurotrophic factor is a potential biomarker for the disease. The patients were selected from the Endometriosis Marker Austria prospective cohort study conducted at the tertiary referral certified Endometriosis Center of the Medical University of Vienna. All women underwent laparoscopic surgery because there was a suspicion of endometriosis, or the women had pelvic pain, adnexal cysts, unexplained infertility, or uterine fibroids. Our main outcome parameter was total levels of mature brain-derived neurotrophic factor in serum, measured using ELISA. Our results show that serum levels of mature brain-derived neurotrophic factor are significantly higher in women with endometriosis compared to women without endometriosis. The mean serum protein levels are significantly higher in women with rAFS stage I and II endometriosis, whereas no difference was found in women with stage III and IV endometriosis and controls. Postoperative follow-up at 6-10 weeks revealed that surgical intervention leads to equilibration of the levels of secreted mature brain-derived neurotrophic factor between women with and without endometriosis. The difference between serum mature brain-derived neurotrophic factor levels of women with endometriosis compared to women without endometriosis is independent of menstrual cycle phase and overall self-reported pelvic pain. ROC-curve analysis showed that, the mature brain-derived neurotrophic factor is not a useful biomarker for endometriosis. In conclusion, although women with stage I and II endometriosis have increased levels of mature brain-derived neurotrophic factor in serum compared to controls, the difference is not predictive for the disease. Impact statement Endometriosis is a disease that can have a significant impact on the quality of life of affected women. The gold standard for diagnosis to this day remains visualization through laparoscopic surgery with histological verification. Current studies are attempting to find a biomarker with high sensitivity and specificity, which would bypass the surgery-associated risks and would significantly reduce costs. In an attempt to elucidate whether mature serum BDNF can serve as diagnostic marker for the disease, we compared the levels of the protein in women with endometriosis to endometriosis-free controls. While our results showed that serum concentrations of the mature protein were significantly higher in women with endometriosis, we did not find this marker to have the sensitivity or specificity needed in order to allow a reliable diagnosis.

Is the oocyte quality affected by endometriosis? A review of the literature

Endometriosis is an estrogen-dependent chronic inflammatory condition that affects women in their reproductive period causing infertility and pelvic pain. The disease, especially at the ovarian site has been shown to have a detrimental impact on ovarian physiology. Indeed, sonographic and histologic data tend to support the idea that ovarian follicles of endometriosis patients are decreased in number and more atretic. Moreover, the local intrafollicular environment of patients affected is characterized by alterations of the granulosa cell compartment including reduced P450 aromatase expression and increased intracellular reactive oxygen species generation. However, no comprehensive evaluation of the literature addressing the effect of endometriosis on oocyte quality from both a clinical and a biological perspective has so far been conducted. Based on this systematic review of the literature, oocytes retrieved from women affected by endometriosis are more likely to fail in vitro maturation and to show altered morphology and lower cytoplasmic mitochondrial content compared to women with other causes of infertility. Results from meta-analyses addressing IVF outcomes in women affected would indicate that a reduction in the number of mature oocytes retrieved is associated with endometriosis while a reduction in fertilization rates is more likely to be associated with minimal/mild rather than with moderate/severe disease. However, evidence in this field is still far to be conclusive, especially with regards to the effects of different stages of the disease and to the impact of patients’ previous medical/surgical treatment(s).

High-Fat Diet Promotion of Endometriosis in an Immunocompetent Mouse Model is Associated With Altered Peripheral and Ectopic Lesion Redox and Inflammatory Status

Endometriosis is a benign gynecological condition that causes considerable morbidity due to associated infertility, debilitating pelvic pain and inflammatory dysfunctions. Diet is a highly modifiable risk factor for many chronic diseases, but its contribution to endometriosis has not been extensively investigated, due partly to the paradoxical inverse association between obesity and disease incidence. Nevertheless, chronic exposure to dietary high-fat intake has been linked to greater systemic inflammation and oxidative stress, both features of women with endometriosis. Here, we evaluated the effects of a high-fat diet (HFD) (45% fat kcal) on endometriosis progression using an immunocompetent mouse model where ectopic lesion incidence was induced in wild-type recipients by ip administration of endometrial fragments from transcription factor Krüppel-like factor 9-null donor mice. We show that HFD significantly increased ectopic lesion numbers in recipient mice with no significant weight gain and modifications in systemic ovarian steroid hormone and insulin levels, relative to control diet-fed (17% fat kcal) mice. HFD promotion of lesion establishment was associated with reductions in stromal estrogen receptor 1 isoform and progesterone receptor expression, increased F4/80-positive macrophage infiltration, higher stromal but not glandular epithelial proliferation, and enhanced expression of proinflammatory and prooxidative stress pathway genes. Lesion-bearing HFD-fed mice also displayed higher peritoneal fluid TNFα and elevated local and systemic redox status than control diet-fed counterparts. Our results suggest that HFD intake exacerbates endometriosis outcome in the absence of ovarian dysfunction and insulin resistance in mice and warrants further consideration with respect to clinical management of endometriosis progression and recurrence in nonobese patients.

Altered levels of acylcarnitines, phosphatidylcholines, and sphingomyelins in peritoneal fluid from ovarian endometriosis patients

Endometriosis is a complex, polygenic, and estrogen-dependent disease that affects 6% to 10% of women of reproductive age, and 30% to 50% of women with infertility and/or pelvic pain. Surgical diagnosis of endometriosis is still the gold standard, as there are currently no diagnostic biomarkers available. Due to the invasive diagnostics, it can take up to 11 years before affected women are diagnosed and receive the appropriate treatment. We performed a targeted metabolomics study to search for potential semi-invasive biomarkers in peritoneal fluid from endometriosis patients. Our case-control study comprised 29 ovarian endometriosis patients and 36 healthy control women. The 148 metabolites included acylcarnitines, glycerophospholipids, and sphingolipids, which were quantified by electrospray ionization tandem mass spectrometry. The strength of association between the metabolites and the metabolite ratios and disease was assessed using crude and adjusted odds ratios. The best combination of biomarkers was then selected by performing step-wise logistic regression. Our analysis reveals significantly decreased concentrations of 10 metabolites, of carnitine and acylcarnitines (C0, C8:1, C6C4:1 DC, C10:1), phosphatidylcholines (PC aa C38:3, PC aa C38:4, PC aa C40:4, PC aa C40:5), and sphingomyelins (SM C16:1, SM C18:1), and 125 significantly altered metabolite ratios in patients versus control women. The best model includes two ratios: a carnitine to a phosphatidylcholine (C0/PC ae C36:0); and between two phosphatidylcholines (PC aa C30:0/PC ae C32:2). When adjusted for age, this provides sensitivity of 82.8% and specificity of 94.4%, with AUC of 0.944. Our study supports the importance of carnitine, phosphatidylcholine, and sphingomyelin metabolites in the pathophysiology of endometriosis, and confirms the potential for the combination of individual metabolite ratios to provide biomarkers for semi-invasive diagnostics.

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.

Characteristics of follicular fluid in ovaries with endometriomas

The study of follicular fluid (FF) content nearby endometriomas may assist in elucidating pathophysiology, possible biomarkers related to this disease and the effect of endometriomas on ovarian physiology. As the question "how endometrioma may intrude the physiology of ovarian tissue?" is still open, we aimed to summarize the molecular evidence supporting the idea that endometriomas can negatively influence the content of the surrounding ovarian follicles. An alteration of the iron metabolism and an increased ROS (reactive oxygen species) generation characterize the intrafollicular environment adjacent to endometriomas. Other potentially negative effects include decreased testosterone and anti-Mullerian hormone FF levels although these have been only partially clarified. Alterations in lipid and proteomic patterns have been also observed in FF samples nearby endometriomas. The possibility that endometriomas per se may influence IVF clinical results as a consequence of the detrimental impact on the local intrafollicular environment is also discussed.

Diagnostic potential of peritoneal fluid biomarkers of endometriosis

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterus, in different parts of the peritoneal cavity. It affects up to 10% of reproductive-age women and up to 50% of women with infertility. Surgical diagnosis of endometriosis is still the gold standard, with no diagnostic biomarkers available. Medical therapies target the symptoms and not the disease itself, and surgical treatment cannot prevent recurrence. As peritoneal fluid reflects the altered peritoneal microenvironment of endometriosis patients, it can provide a wealth of information on pathophysiological processes and potential biomarkers. This report reviews the molecular biomarkers identified in peritoneal fluid over the last 5 years and discusses their potential applications for diagnosis, prognosis and drug therapy.

Oxidative stress in pregnancy and fertility pathologies

Oxidative stress designates the state of imbalance between reactive oxygen species (ROS) production and antioxidant levels. In a healthy placenta, there is an increase in ROS production, due to formation of new tissues and inherent metabolism, but this is balanced by higher levels of antioxidants. However, this balance is lost in some situations, with a consequent increase in oxidative stress levels. Oxidative stress has been implicated in several placental disorders and pregnancy pathologies. The present review intends to summarize what is known about the relationship between oxidative stress and well-known pregnancy disorders.

Peritoneal fluid reduces angiogenesis-related microRNA expression in cell cultures of endometrial and endometriotic tissues from women with endometriosis

Endometriosis, defined as the presence of endometrium outside the uterus, is one of the most frequent gynecological diseases. It has been suggested that modifications of both endometrial and peritoneal factors could be implicated in this disease. Endometriosis is a multifactorial disease in which angiogenesis and proteolysis are dysregulated. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the protein expression and may be the main regulators of angiogenesis. Our hypothesis is that peritoneal fluid from women with endometriosis could modify the expression of several miRNAs that regulate angiogenesis and proteolysis in the endometriosis development. The objective of this study has been to evaluate the influence of endometriotic peritoneal fluid on the expression of six miRNAs related to angiogenesis, as well as several angiogenic and proteolytic factors in endometrial and endometriotic cell cultures from women with endometriosis compared with women without endometriosis.