Increased concentration of 8-hydroxy-2'-deoxyguanosine in follicular fluid of infertile women with endometriosis

Methyl 3,4-dihydroxybenzoate alleviates oxidative damage in granulosa cells by activating Nrf2 antioxidant pathway

Oxidative damage induced granulosa cells (GCs) apoptosis was considered as a significant cause of compromised follicle quality, antioxidants therapy has emerged as a potential method for improving endometriosis pregnancy outcomes. Here, we found that GCs from endometriosis patients show increased oxidative stress level. Methyl 3,4-dihydroxybenzoate (MDHB), a small molecule compound that is extracted from natural plants, reversed tert-butyl hydroperoxide (TBHP) induced GCs oxidative damage. Therefore, the aim of this study was to assess the protective effect of MDHB for GCs and its potential mechanisms. TUNEL staining and immunoblotting of cleaved caspase-3/7/9 showed MDHB attenuated TBHP induced GCs apoptosis. Mechanistically, MDHB treatment decreased cellular and mitochondria ROS production, improved the mitochondrial function by rescuing the mitochondrial membrane potential (MMP) and ATP production. Meanwhile, MDHB protein upregulated the expression of vital antioxidant transcriptional factor Nrf2 and antioxidant enzymes SOD1, NQO1 and GCLC to inhibited oxidative stress state, further beneficial to oocytes and embryos quality. Therefore, MDHB may represent a potential drug candidate in protecting granulosa cells in endometriosis, which can improve pregnancy outcomes for endometriosis-associated infertility.

Metabolic profile of follicular fluid in patients with ovarian endometriosis undergoing IVF: a pilot study

RESEARCH QUESTION

What are the metabolic characteristics of follicular fluid in patients with ovarian endometriosis undergoing IVF?

DESIGN

This was an exploratory cohort study on endometriosis. In total, 19 infertile patients with ovarian endometriosis diagnosed by laparoscopy, and 23 controls matched in terms of age and body mass index (women with infertility due to male or tubal factors) were enrolled in this study. All patients underwent IVF treatment with a gonadotrophin-releasing hormone antagonist protocol, and follicular fluid was collected at oocyte retrieval. The metabolomics of follicular fluid samples was analysed using an ultra-high-performance liquid chromatography Orbitrap Exploris mass spectrometer (UHPLC-OE-MS). The best combination of biomarkers was selected by performing stepwise logistic regression analysis with backward elimination.

RESULTS

Fifteen metabolites were identified as biomarkers associated with endometriosis. A final model containing 8-hydroxy-2-deoxyguanosine, biotin, n-acetyl-L-methionine and n-methylnicotinamide was constructed. Receiver operating characteristic analysis confirmed the value of these parameters in diagnosing endometriosis, with sensitivity of 94.7% and specificity of 95.7%. Enrichment analysis via the Kyoto Encyclopedia of Genes and Genome showed that 15 metabolites were enriched in eight metabolic pathways.

CONCLUSION

Metabolomics based on UHPLC-OE-MS effectively characterized the metabolomics analysis of follicular fluid in patients with ovarian endometriosis. These findings may provide a new basis for better understanding of how diseases progress, and for the discovery of new biomarkers.

How Can Selected Dietary Ingredients Influence the Development and Progression of Endometriosis?

Endometriosis is a chronic, hormone-dependent disease characterized by the presence of endometrial tissue in ectopic locations. Since the treatment options for this disease are still limited, and the cure rate is unsatisfactory, the search for ways to treat symptoms and modify the course of the disease is of key importance in improving the quality of life of patients with endometriosis. So far, the literature has shown that nutrition can influence endometriosis through hormonal modification and altering the inflammatory or oxidative response. Since the importance of nutrition in this disease is still a subject of scientific research, we aimed to summarize the current knowledge on the role of dietary modifications in endometriosis. Our review showed that nutrients with anti-inflammatory and antioxidant properties, including most vitamins and several trace elements, may influence the pathogenesis of endometriosis and can be considered as the nutrients preventing the development of endometriosis. However, despite the many discoveries described in this review, further interdisciplinary research on this topic seems to be extremely important, as in the future, it may result in the development of personalized therapies supporting the treatment of endometriosis.

A cohort study on IVF outcomes in infertile endometriosis patients: the effects of rapamycin treatment

RESEARCH QUESTION

Can rapamycin, used as an anti-senescence drug before IVF cycles, improve the IVF outcomes of women with endometriosis by reducing oxidative stress and senescence?

DESIGN

This retrospective analysis involved 168 endometriosis patients undergoing two successive IVF cycles. The treatment group (n = 80) received 3 months of rapamycin before the second IVF cycle, while the non-treatment group (n = 88) had no adjuvant treatment. The first and second IVF cycles were compared between and within groups. Follicular fluid from both IVF cycles (treatment group n = 28, non-treatment group n = 32) were tested for senescence-associated and oxidative stress-related markers.

RESULTS

Comparing the follicular fluid from the second cycles, the rapamycin treatment group showed decreased markers of oxidative stress (8-hydroxydesoxyguanosine, malondialdehyde) and increased antioxidant markers (superoxidase dismutase, glutathione peroxidase) (all P < 0.001); the expression of senescence-related markers p16 and p21 was also significantly lower in the treatment group than in the non-treatment group (P < 0.001). Comparing the second IVF cycles, the treatment group needed fewer days of ovarian stimulation, with increased numbers of oocytes obtained and mature oocytes compared with the non-treatment group (all P < 0.001). Furthermore, rates of fertilization, implantation and clinical pregnancy were significantly higher in the treatment group (P = 0.008, 0.034 and 0.038 respectively), as was the live birth rate (P = 0.003). No structural abnormalities were seen in fetuses born to women treated with rapamycin.

CONCLUSIONS

This study suggested an association between short-term rapamycin treatment and improved pregnancy outcomes via IVF. This result needs to be further investigated in prospective randomized controlled clinical trials.

The Pathological Role of miRNAs in Endometriosis

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

Do the oxidative stress biomarkers predict COVID-19 outcome? An in-hospital cohort study

In SARSCoV-2 infections, excessive activation of the immune system dramatically elevates reactive oxygen species levels, harms cell structures, and directly increases disease severity and mortality. We aimed to evaluate whether plasma oxidative stress biomarker levels could predict mortality in adults admitted with Coronavirus Disease 2019 (COVID-19), considering potential confounders. We conducted a cohort study of 115 adults (62.1 ± 17.6 years, 65 males) admitted to a Brazilian public hospital for severely symptomatic COVID-19. Serum levels of α-tocopherol, glutathione, superoxide dismutase, 8-hydroxy-2'-deoxyguanosine, malondialdehyde, and advanced oxidation protein products were quantified at COVID-19 diagnosis using real-time polymerase chain reaction. Serum levels of α-tocopherol, glutathione, superoxide dismutase, and advanced oxidation protein products differed significantly between survivors and non-survivors. Serum glutathione levels below 327.2 μmol/mL were associated with a significant risk of death in COVID-19 patients, even after accounting for other factors (adjusted hazard ratio = 3.12 [95% CI: 1.83-5.33]).

Oxidatively generated DNA damage mediates the associations of exposure to phthalates with uterine fibroids and endometriosis: Findings from TREE cohort

BACKGROUND

Epidemiological studies on phthalate exposures in associations with uterine fibroids (UF) and endometriosis (EMT) are inconsistent. The underlying mechanisms are poorly understood.

OBJECTIVES

To investigate the relationships of urinary phthalate metabolites with UF and EMT risks, and further to examine the mediating role of oxidative stress.

METHODS

This study included 83 and 47 women separately diagnosed with UF and EMT, as well as 226 controls from the Tongji Reproductive and Environmental (TREE) cohort. Two spot urine samples from each woman were analyzed for two oxidative stress indicators and eight urinary phthalate metabolites. Unconditional logistic regression models or multivariate regression models were fitted to evaluate the associations among phthalate exposures, oxidative stress indicators, and the risks of UF and EMT. The potential mediating role of oxidative stress was estimated by the mediation analyses.

RESULTS

We observed that each ln-unit increase in urinary mono-benzyl phthalate (MBzP) concentrations was associated with increased UF risk [adjusted OR (aOR): 1.56, 95% CI: 1.20, 2.02], and that each ln-unit increase in urinary MBzP (aOR: 1.48, 95% CI: 1.09, 1.99), mono-isobutyl phthalate (MiBP) (aOR: 1.83, 95% CI: 1.19, 2.82), and mono-2-ethylhexyl phthalate (MEHP) (aOR: 1.66, 95% CI: 1.19, 2.31) concentrations were associated with increased EMT risk (all FDR-adjusted P < 0.05). Moreover, we observed that all tested urinary phthalate metabolites were positively associated with two oxidative stress indicators [4-hydroxy-2-nonenal-mercapturic acid (4-HNE-MA) and 8-hydroxy-2-deoxyguanosine (8-OHdG)], in which 8-OHdG was associated with increased risks of UF and EMT (all FDR-adjusted P < 0.05). The mediation analyses showed that 8-OHdG mediated the positive relationships of MBzP with UF risk, and of MiBP, MBzP, and MEHP with EMT risk, with the estimated intermediary proportion ranging from 32.7% to 48.1%.

CONCLUSIONS

Oxidatively generated DNA damage may mediate the positive associations of certain phthalate exposures with the risks of UF and EMT. However, further investigation is warranted to confirm these findings.

Decreased oocyte quality in patients with endometriosis is closely related to abnormal granulosa cells

Infertility and menstrual abnormalities in endometriosis patients are frequently caused by aberrant follicular growth or a reduced ovarian reserve. Endometriosis typically does not directly harm the oocyte, but rather inhibits the function of granulosa cells, resulting in a decrease in oocyte quality. Granulosa cells, as oocyte nanny cells, can regulate meiosis, provide the most basic resources required for oocyte development, and influence ovulation. Endometriosis affects oocyte development and quality by causing granulosa cells apoptosis, inflammation, oxidative stress, steroid synthesis obstacle, and aberrant mitochondrial energy metabolism. These aberrant states frequently interact with one another, however there is currently relatively little research in this field to understand the mechanism of linkage between abnormal states.

Nontargeted metabolomics analysis of follicular fluid in patients with endometriosis provides a new direction for the study of oocyte quality

Endometriosis is a common, estrogen-dependent chronic gynecological disease that endangers the reproductive system and systemic metabolism of patients. We aimed to investigate the differences in metabolic profiles in the follicular fluid between infertile patients with endometriosis and controls. A total of 25 infertile patients with endometriosis and 25 infertile controls who were similar in age, BMI, fertilization method and ovulation induction treatment were recruited in this study. Metabolomics analysis of follicular fluid was performed by two methods of high-performance liquid chromatography tandem mass spectrometry. There were 36 upregulated and 17 downregulated metabolites in the follicular fluid of patients in the endometriosis group. KEGG pathway analysis revealed that these metabolites were enriched in phenylalanine, tyrosine and tryptophan biosynthesis, aminoacyl-tRNA biosynthesis, phenylalanine metabolism and pyrimidine metabolism pathways. A biomarker panel consisting of 20 metabolites was constructed by random forest, with an accuracy of 0.946 and an AUC of 0.988. This study characterizes differences in follicular fluid metabolites and associated pathway profiles in infertile patients with endometriosis. These findings can provide a better comprehensive understanding of the disease and a new direction for the study of oocyte quality, as well as potential metabolic markers for the prognosis of endometriosis.

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.

Progesterone and Androstenedione Are Important Follicular Fluid Factors Regulating Porcine Oocyte Maturation Quality

Oocytes matured in vitro are useful for assisted human and farm animal reproduction. However, the quality of in vitro matured oocytes is usually lower than that of in vivo matured oocytes, possibly due to the absence of some important signal regulators in vitro. In this study, untargeted metabolomics was used to detect the changes in the metabolites in the follicular fluid (FF) during in vivo pig oocyte maturation and in the culture medium during in vitro maturation. Our results showed that the total metabolite changing profile of the in vivo FF was different from that of the in vitro maturation medium, but the levels of 23 differentially expressed metabolites (DEMs) changed by following the same trend during both in vivo and in vitro pig oocyte maturation. These 23 metabolites may be important regulators of porcine oocyte maturation. We found that progesterone and androstenedione, two factors in the ovarian steroidogenesis pathway enriched from the DEMs, were upregulated in the FF during in vivo pig oocyte maturation. The levels of these two factors were 31 and 20 fold, respectively, and they were higher in the FF than in the culture medium at the oocyte mature stage. The supplementation of progesterone and androstenedione during in vitro maturation significantly improved the pig oocyte maturation rate and subsequent embryo developmental competence. Our finding suggests that a metabolic abnormality during in vitro pig oocyte maturation affects the quality of the matured oocytes. This study identified some important metabolites that regulate oocyte maturation and their developmental potential, which will be helpful to improve assisted animal and human reproduction.

Clotrimazole is effective, safe and tolerable for the treatment of endometriosis and functions by downregulating inducible nitric oxide synthase and modulating oxidative stress biomarkers

This study investigated the mechanism of action of clotrimazole (CTZ) and its adverse effects in a model of endometriosis. After autologous endometrial implantation, 18 rats were randomized into two treatment groups: 200 mg/kg CTZ or vehicle for 15 consecutive days. The lesion growth, implant size, glandular atrophy, nitric oxide (NO) serum levels, number of macrophage cells and inducible nitric oxide synthase (iNOS) immunoreactivity were significantly reduced in the CTZ group compared with the control. CTZ (p < 0.05) reduced the lipid peroxidation and protein carbonylation levels in the liver but did not alter the superoxide dismutase (SOD), glutathione (GSH) or glutathione S-transferase (GST) levels in the brain; however, the drug significantly reduced SOD activity and enhanced GST activity in the liver. These results suggest that CTZ interferes with reactive nitrogen species production by downregulating iNOS expression and thus enhances the antioxidant system to promote atrophy and regression of endometriotic lesions, without adverse effects on the brain and/or liver.

Emerging hallmarks of endometriosis metabolism: A promising target for the treatment of endometriosis

Endometriosis, characterized by ectopic endometrium growth in the extrauterine environment, is one of the most notable diseases of the female reproductive system. Worldwide, endometriosis affects nearly 10 % of women in their reproductive years and causes a significant decline in quality of life. Despite extensive investigations of endometriosis over the past years, the mechanisms of endometriosis pathogenesis remain unclear. In recent years, metabolic factors have increasingly been considered factors in endometriosis. There is compelling evidence regarding the progress of endometriosis in the context of severe metabolic dysfunction. Hence, the curative strategies and ongoing attempts to conquer endometriosis might start with metabolic pathways. This review focuses on metabolic mechanisms and summarizes current research progress. These findings provide valuable information for the non-intrusive diagnosis of the disease and may contribute to the understanding of the pathogenesis of endometriosis.

Oxidatively Damaged Nucleic Acid: Linking Diabetes and Cancer

Significance: Our current knowledge of the mechanism between diabetes and cancer is limited. Oxidatively damaged nucleic acid is considered a critical factor to explore the connections between these two diseases. Recent Advances: The link between diabetes mellitus and cancer has attracted increasing attention in recent years. Emerging evidence supports that oxidatively damaged nucleic acid caused by an imbalance between reactive oxygen species generation and elimination is a bridge connecting diabetes and cancer. 8-Oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine assume important roles as biomarkers in assessing the relationship between oxidatively damaged nucleic acid and cancer. Critical Issues: The consequences of diabetes are extensive and may lead to the occurrence of cancer by influencing a combination of factors. At present, there is no direct evidence that diabetes causes cancer by affecting a single factor. Furthermore, the difficulty in controlling variables and differences in detection methods lead to poor reliability and repeatability of results, and there are no clear cutoff values for biomarkers to indicate cancer risk. Future Directions: A better understanding of connections as well as mechanisms between diabetes and cancer is still needed. Both diabetes and cancer are currently intractable diseases. Further exploration of the specific mechanism of oxidatively damaged nucleic acid in the connection between diabetes and cancer is urgently needed. In the future, it is necessary to further take oxidatively damaged nucleic acid as an entry point to provide new ideas for the diagnosis and treatment of diabetes and cancer. Experimental drugs targeting the repair process of oxidatively generated damage require an extensive preclinical evaluation and could ultimately provide new treatment strategies for these diseases. Antioxid. Redox Signal. 37, 1153-1167.

Endometriosis-associated infertility: From pathophysiology to tailored treatment

Despite the clinically recognized association between endometriosis and infertility, the mechanisms implicated in endometriosis-associated infertility are not fully understood. Endometriosis is a multifactorial and systemic disease that has pleiotropic direct and indirect effects on reproduction. A complex interaction between endometriosis subtype, pain, inflammation, altered pelvic anatomy, adhesions, disrupted ovarian reserve/function, and compromised endometrial receptivity as well as systemic effects of the disease define endometriosis-associated infertility. The population of infertile women with endometriosis is heterogeneous, and diverse patients' phenotypes can be observed in the clinical setting, thus making difficult to establish a precise diagnosis and a single mechanism of endometriosis related infertility. Moreover, clinical management of infertility associated with endometriosis can be challenging due to this heterogeneity. Innovative non-invasive diagnostic tools are on the horizon that may allow us to target the specific dysfunctional alteration in the reproduction process. Currently the treatment should be individualized according to the clinical situation and to the suspected level of impairment. Here we review the etiology of endometriosis related infertility as well as current treatment options, including the roles of surgery and assisted reproductive technologies.

The Impact of Controlled Ovarian Stimulation on Serum Oxidative Stress Markers in Infertile Women with Endometriosis Undergoing ICSI

Endometriosis-related infertility is associated with oxidative stress (OS). The present study aims to compare serum OS markers of infertile women with endometriosis and controls during the follicular phase of the natural cycle (D1), after pituitary downregulation using a GnRH agonist (D2), after controlled ovarian stimulation (COS) on the day of human chorionic gonadotropin administration (D3), and on the day of oocyte retrieval (D4). One hundred and eight serum samples (58 controls and 35 early and 18 advanced endometriosis cases) were collected at these four timepoints. OS markers were compared among the groups and timepoints using a linear regression model with mixed effects and a post-test using orthogonal contrasts. The significance was set at 5%. We observed altered OS markers in the endometriosis patients during the D1, D2, D3, and D4 timepoints compared to the controls. The evidence of systemic OS in infertile patients with endometriosis during COS suggests the mobilization of potent antioxidants in an attempt to protect the oocyte from oxidative damage, especially on the day of oocyte retrieval.

Transcriptomic analysis of cumulus cells shows altered pathways in patients with minimal and mild endometriosis

Endometriosis is a chronic inflammatory disorder that is highly associated with infertility. This association seems to be related to oocyte impairment, mainly in the initial stages of endometriosis (minimal and mild), where no distortions or adhesions are present. Nonetheless, invasive oocyte analyses are not routinely feasible; thus, indirect assessment of oocyte quality is highly desirable, and, in this context, cumulus cells (CCs) may be more suitable targets of analysis. CCs are crucial in oocyte development and could be used as an index of oocyte quality. Therefore, this prospective case–control study aimed to shed light on the infertility mechanisms of endometriosis I/II by analyzing the CCs’ mRNA transcription profile (women with endometriosis I/II, n = 9) compared to controls (women with tubal abnormalities or male factor, n = 9). The transcriptomic analyses of CCs from patients with minimal and mild endometriosis revealed 26 differentially expressed genes compared to the controls. The enrichment analysis evidenced some altered molecular processes: Cytokine-cytokine receptor interactions, Chemokine signaling, TNF signaling, NOD-like receptor signaling, NF-kappa B signaling, and inflammatory response. With the exception of CXCL12, all enriched genes were downregulated in CCs from patients with endometriosis. These findings provide a significant achievement in the field of reproductive biology, directing future studies to discover biomarkers of oocyte quality in endometriosis.

Oxidative stress and DNA damage status in couples undergoing in vitro fertilization treatment

This study examined the status of oxidative stress in 599 couples undertaking in vitro fertilization (IVF) treatment and its association with reproductive hormones, smoking, and outcomes. Oxidative stress biomarkers such as malondialdehyde, 8-hydroxy-2-deoxyguanosine, hydrogen peroxide (H₂O₂), catalase (CAT), and total antioxidant capacity (TAC) were determined in follicular fluid and seminal plasma. Tail moment (TM) was used to evaluate DNA damage in the sperm and granulosa cells. Reproductive hormones in serum and cotinine (COT) in urine, follicular fluid, and seminal plasma samples were determined. Separate multivariate linear regression was used to assess associations between levels of each oxidative stress biomarker and each hormone and smoking parameter (modeled as natural log-transformed). The findings indicate that some oxidative stress and DNA damage biomarkers played a role in disrupting certain reproductive hormones in women and their male partners either by overproducing reactive oxygen species or reducing antioxidant defense capacity. Although women were nonsmokers, COT levels > 50 and 10 µg/L in urine and follicular were observed in 5.7 and 1.7%, respectively. Levels of follicular fluid COT were positively associated with H₂O₂ and TM. We used log-binomial multivariate regression to estimate relative risks for the association between oxidative stress/DNA damage and IVF binary outcomes (fertilization rate > 50%, biochemical pregnancy, clinical pregnancy, and live birth). An increase in the CAT levels of follicular fluid was associated with a 48 and 41% decrease in the risk of poor fertilization rate (≤50%) and unsuccessful live birth, respectively. After the models were adjusted for hormonal factors, the associations remained the same, except that the elevated TAC in follicular fluid became significantly associated with a decrease of 42% in the risk of poor fertilization rate (≤50%). The higher antioxidant activity (CAT and TAC) in follicular fluid might positively impact specific IVF outcomes.

Molecular Signatures Correlated With Poor IVF Outcomes: Insights From the mRNA and lncRNA Expression of Endometriotic Granulosa Cells

The outcomes of in vitro fertilization (IVF) for endometriotic women are significantly worse than for patients without ovarian endometriosis (OEM), as shown by fewer retrieved oocytes. However, the exact pathophysiological mechanism is still unknown. Thus, we conducted a prospective study that analyzed mRNA and lncRNA transcriptome between granulosa cells (GCs) from patients with fewer retrieved oocytes due to OEM and GCs from controls with male factor (MF) infertility using an RNA sequencing approach. We found a group of significantly differentially expressed genes (DEGs), including NR5A2, MAP3K5, PGRMC2, PRKAR2A, DEPTOR, ITGAV, KPNB1, GPC6, EIF3A, and SMC5, which were validated to be upregulated and negatively correlated with retrieved oocyte numbers in GCs of patients with OEM, while DUSP1 demonstrated the opposite. The molecular functions of these DEGs were mainly enriched in pathways involving mitogen-activated protein kinase (MAPK) signaling, Wnt signaling, steroid hormone response, apoptosis, and cell junction. Furthermore, we performed lncRNA analysis and identified a group of differentially expressed known/novel lncRNAs that were co-expressed with the validated DEGs and correlated with retrieved oocyte numbers. Co-expression networks were constructed between the DEGs and known/novel lncRNAs. These distinctive molecular signatures uncovered in this study are involved in the pathological regulation of ovarian reserve dysfunction in OEM patients.

Effects of bone marrow mesenchymal stem cell transplantation on tumor necrosis factor-alpha receptor 1 expression, granulosa cell apoptosis, and folliculogenesis repair in endometriosis mouse models

BACKGROUND AND AIM

Endometriosis affects the ovaries and causes a decrease in the oocyte quality during endometrial receptivity. During the development of ovarian follicles, paracrine communication occurs between granulosa cells and oocytes. This study was conducted to determine the effects of bone marrow mesenchymal stem cell transplantation on tumor necrosis factor-alpha (TNF-α) receptor 1 (TNFR1) expression, granulosa cell apoptosis, and folliculogenesis in endometriosis mouse models.

MATERIALS AND METHODS

This study involved 42 female mice, which were divided into three groups: Healthy mice (T0), endometriosis mice without transplantation (T1), and endometriosis mice with bone marrow mesenchymal stem cell transplantation (T2). The mice were injected intraperitoneally with endometrial fragments (200 μL) to become endometriosis models. On day 15, the endometriosis models received mesenchymal stem cells. Sample collection was performed on day 29. Granulosa cell apoptosis and TNFR1 expression were examined using immunohistochemical staining, and folliculogenesis was assessed using hematoxylin and eosin staining of ovary samples. The data obtained from both examinations were statistically analyzed using Statistical Package for the Social Sciences.

RESULTS

The results showed that TNFR1 expression is significantly decreased in T2 (p<0.004). The apoptosis of granulosa cells was lower in T2 (p<0.000). The primary, secondary, and graafian follicle counts in T2 were significantly increased.

CONCLUSION

Bone marrow mesenchymal stem cell transplantation in endometriosis mouse models can reduce TNFR1 expression and granulosa cell apoptosis and improve folliculogenesis.

Effects of multicycle gonadotropin-releasing hormone antagonist protocols on oxidative stress of follicular fluid and ovarian granulosa cells

The effect of repeated multicycle gonadotropin-releasing hormone antagonist (GnRH-ant) protocols on oxidative stress (OS) in follicular fluid (FF) and ovarian granulosa cells (GCs) remains unclear. This study investigated the effects of repeated multicycle GnRH-ant protocols on OS markers of FF and ovarian GCs. A total of 145 patients were enrolled and divided into four groups: 1 cycle group (n = 42), 2 cycles group (n = 37), 3 cycles group (n = 45), and 4-5 cycles group (n = 21). The FF and ovarian GCs of the patients were collected on the day of last oocyte retrieval and the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were tested by ELISA. The results showed that the serum estradiol levels on hCG injection day in the 3 and 4-5 cycles were significantly (P < 0.05) lower than in the 1 and 2 cycles. The number of retrieved oocytes (12.1 ± 3.3 in cycle 1, 11.7 ± 3.1 in cycle 2, 10.4 ± 2.4 in cycle 3, and 9.4 ± 2.4 in cycles 4-5), embryos with two pronuclei (7.6 ± 3.0 in cycle 1, 7.0 ± 2.5 in cycle 2, 6.2 ± 2.6 in cycle 3, and 5.5 ± 2.1 in cycles 4-5), and the rates of high-quality embryos (52.2% in cycle 1, 47.9% in cycle 2, 38.6% in cycle 3, and 36.5% in cycles 4-5), implantation (35.4% in cycle 1, 32.4% in cycle 2, 23.8% in cycle 3, and 22.9% in cycles 4-5) and clinical pregnancy (50.0% in cycle 1, 43.2% in cycle 2, 33.3% in cycle 3, and 23.8% in cycles 4-5) in cycles 3 and 4-5 were significantly (P < 0.05) lower than those in cycles 1 and 2. Compared with 1 and 2 cycles, the 8-OHdG and SOD were significantly increased in the 3-5 cycles, while the CAT and GSH-Px levels were significantly decreased. Together, this study reveals repeated COS with the use of GnRH-ant protocols results in OS and changes the follicle microenvironment of FF and GCs, possibly leading to poor IVF outcomes in patients with 3-5 cycles of COS.

Novel therapeutic targets to improve IVF outcomes in endometriosis patients: a review and future prospects

BACKGROUND

Patients with endometriosis often experience infertility and have poor IVF outcomes, with low fertilization and pregnancy rates. Although many theories have tried to explain the mechanisms underlying infertility in these patients, none of them is conclusive.

OBJECTIVE AND RATIONALE

In this review, we discuss the pathologic mechanisms through which endometriosis likely leads to infertility along with the therapeutic options used to date to treat endometriosis-related infertility and, thereby, to improve IVF outcomes in patients with endometriosis.

SEARCH METHODS

We performed a comprehensive literature search of clinical outcomes in endometriosis and the molecular mechanisms contributing to oocyte quality using the PubMed database to identify human and animal studies published from 1992 until September 2020. In total, 123 manuscripts were included.

OUTCOMES

While some theories propose that endometriosis patients may have fertility problems as a result of decreased endometrial receptivity, others reinforce the idea that infertility could be associated with oocyte alterations and lower implantation rates. Single-cell RNA sequencing of oocytes from patients with endometriosis has identified dysregulated mechanisms involved in steroid metabolism and biosynthesis, response to oxidative stress and cell cycle regulation. Dysregulation of these mechanisms could result in the poor IVF outcomes observed in patients with endometriosis. Further, impaired steroidogenesis may directly affect oocyte and embryo quality. Increased oxidative stress in patients with endometriosis also has a detrimental effect on the follicular microenvironment, inducing cell cycle dysregulation in oocytes, poor oocyte quality, and infertility. Moreover, granulosa cells in the context of endometriosis undergo increased apoptosis and have an altered cell cycle that could adversely affect folliculogenesis, oocyte and embryo quality, and IVF outcomes. Endometriosis is also associated with inflammatory damage and impaired angiogenesis, which could be directly correlated with poor IVF outcomes. While therapeutic options using GnRH analogues, progestins and aromatase inhibitors do not improve endometriosis-related infertility, anti-inflammatory agents and antioxidant supplementation could improve oocyte quality as well as implantation and clinical pregnancy rates in patients with endometriosis.

WIDER IMPLICATIONS

Endometriosis is a heterogeneous disease whose pathogenesis is complex and could affect fertility by altering a collection of molecular mechanisms in oocytes. Thus, a single model is not sufficient to describe endometriosis-related infertility. Dysregulation of steroidogenesis, oxidative stress, cell cycle progression, inflammation and angiogenesis in the follicular environment and oocytes in individuals with endometriosis are all possible contributors to endometriosis-related infertility. Therefore, treatments targeting these mechanisms could be therapeutic alternatives to improve IVF outcomes for these patients.

Susceptibility of Oocytes from Gilts and Sows to Beauvericin and Deoxynivalenol and Its Relationship with Oxidative Stress

Beauvericin (BEA) and deoxynivalenol are toxins produced by Fusarium species that can contaminate food and feed. The aim of this study was to assess the effects of these mycotoxins on the maturation of oocytes from gilts and sows. Furthermore, the antioxidant profiles in the oocytes' environment were assessed. Cumulus-oocyte-complexes (COCs) from gilts and sows were exposed to beauvericin (BEA) or deoxynivalenol (DON) and matured in vitro. As an extra control, these COCs were also exposed to reactive oxygen species (ROS). The maturation was mostly impaired when oocytes from gilts were exposed to 0.02 μmol/L DON. Oocytes from sows were able to mature even in the presence of 5 μmol/L BEA. However, the maturation rate of gilt oocytes was already impaired by 0.5 μmol/L BEA. It was observed that superoxide dismutase (SOD) and glutathione (GSH) levels in the follicular fluid (FF) of gilt oocytes was higher than that from sows. However, the expression of SOD1 and glutathione synthetase (GSS) was higher in the oocytes from sows than in those from gilts. Although DON and BEA impair cell development by diverse mechanisms, this redox imbalance may partially explain the vulnerability of gilt oocytes to these mycotoxins.

Polystyrene microplastics lead to pyroptosis and apoptosis of ovarian granulosa cells via NLRP3/Caspase-1 signaling pathway in rats

Microplastics (MPs) considered as a new persistent environmental pollutant could enter into the circulatory system and result in decrease of sperm quantity and quality in mice. However, the effects of Polystyrene MPs (PS MPs) on the ovary and its mechanism in rats remained unclear. In this present study, thirty-two healthy female Wistar rats were exposed to different concentrations of 0.5 µm PS MPs dispersed in deionized water for 90 days. Using hematoxylin-eosin (HE) staining, the number of growing follicles was decreased compared to the control group. In addition, the activity of glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) were decreased while the expression level of malondialdehyde (MDA) was increased in ovary tissue. Confirmed by immunohistochemistry, the integrated optical density of NLRP3 and Cleaved-Caspase-1 had been elevated by 13.9 and 14 in granulosa cells in the 1.5 mg/kg/d group. Furthermore, compared to the control group, the level of AMH had been decreased by 23.3 pg/ml while IL-1β and IL-18 had been increased by 32 and 18.5 pg/ml in the 1.5 mg/kg/d group using the enzyme-linked immune sorbent assay (ELISA). Besides, the apoptosis of granulosa cells was elevated measured by terminal deoxyribonucleotide transferase-mediated nick end labeling (TUNEL) staining and flow cytometry. Moreover, western blot assays showed that the expressions of NLRP3/Caspase-1 signaling pathway related factors and Cleaved-Caspase-3 were increased. These results demonstrated that PS MPs could induce pyroptosis and apoptosis of ovarian granulosa cells via the NLRP3/Caspase-1 signaling pathway maybe triggered by oxidative stress. The present study suggested that exposure to microplastics had adverse effects on ovary and could be a potential risk factor for female infertility, which provided new insights into the toxicity of MPs on female reproduction.

Altered transcriptome in cumulus cells of infertile women with advanced endometriosis with and without endometrioma

RESEARCH QUESTION

Is the transcriptome of cumulus cells of infertile women with advanced endometriosis (EIII/IV), with and without endometrioma, altered?

DESIGN

In this prospective case-control study, next-generation RNA sequencing was used to compare the transcript profile of cumulus cells among infertile patients undergoing ovarian stimulation for intracytoplasmic sperm injection with EIII/IV, with (n = 9) and without endometrioma (n = 9), and controls (n = 9). An in-silico enrichment analysis was conducted to establish the possibly altered pathways in cumulus cells of patients with endometriosis.

RESULTS

Most of the differentially expressed genes (DEG) were found when cumulus cells from women with EIII/IV with endometrioma were compared with controls (DEG, n = 461). In women with EIII/IV without endometrioma, only 66 DEG were verified compared with controls. The enrichment analysis showed that some DEG in cumulus cells of endometriosis are involved in important pathways for the oocyte competence acquisition, such as oxidative phosphorylation, metabolism, mitochondrial function, acetylation and steroid biosynthesis. No DEG were found when cumulus cells from women with EIII/IV with and without endometrioma were compared.

CONCLUSION

RNA sequencing results suggest that cumulus cells of infertile women with EIII/IV have an altered transcriptome, regardless of endometrioma. The present findings offer a better understanding of the genes and molecular mechanisms that may be involved in endometriosis-related infertility, mostly in the oocyte competence acquisition process.

Cell-free DNA discoveries in human reproductive medicine: providing a new tool for biomarker and genetic assays in ART

Cell-free DNAs (cfDNAs) are fragmented forms of DNA that are released into extracellular environments. Analyzing them, regarding either concentration or genetic/epigenetic status can provide helpful information about disorders, response to treatments, estimation of success rates, etc. Moreover, since they are presented in body fluids, evaluation of the aforementioned items would be achieved by less/non-invasive methods. In human reproduction field, it is required to have biomarkers for prediction of assisted reproduction techniques (ART) outcome, as well as some non-invasive procedures for genetic/epigenetic assessments. cfDNA is an appropriate candidate for providing the both approaches in ART. Recently, scientists attempted to investigate its application in distinct fields of reproductive medicine that resulted in discovering its applicability for biomarker and genetic/epigenetic analyses. However, due to some limitations, it has not reached to clinical administration yet. In this article, we have reviewed the current reported data with respect to advantages and limitations of cfDNA utilization in three fields of ART, reproduction of male and female, as well as in vitro developed embryos.

Biomarkers of nucleic acid oxidation - A summary state-of-the-art

Oxidatively generated damage to DNA has been implicated in the pathogenesis of a wide variety of diseases. Increasingly, interest is also focusing upon the effects of damage to the other nucleic acids, RNA and the (2′-deoxy-)ribonucleotide pools, and evidence is growing that these too may have an important role in disease. LC-MS/MS has the ability to provide absolute quantification of specific biomarkers, such as 8-oxo-7,8-dihydro-2′-deoxyGuo (8-oxodG), in both nuclear and mitochondrial DNA, and 8-oxoGuo in RNA. However, significant quantities of tissue are needed, limiting its use in human biomonitoring studies. In contrast, the comet assay requires much less material, and as little as 5 μL of blood may be used, offering a minimally invasive means of assessing oxidative stress in vivo, but this is restricted to nuclear DNA damage only. Urine is an ideal matrix in which to non-invasively study nucleic acid-derived biomarkers of oxidative stress, and considerable progress has been made towards robustly validating these measurements, not least through the efforts of the European Standards Committee on Urinary (DNA) Lesion Analysis. For urine, LC-MS/MS is considered the gold standard approach, and although there have been improvements to the ELISA methodology, this is largely limited to 8-oxodG. Emerging DNA adductomics approaches, which either comprehensively assess the totality of adducts in DNA, or map DNA damage across the nuclear and mitochondrial genomes, offer the potential to considerably advance our understanding of the mechanistic role of oxidatively damaged nucleic acids in disease.

•

Oxidatively damaged nucleic acids are implicated in the pathogenesis of disease.

•

LC-MS/MS, comet assay and ELISA are often used to study oxidatively damaged DNA.

•

Urinary oxidatively damaged nucleic acids non-invasively reflect oxidative stress.

•

DNA adductomics will aid understanding the role of ROS damaged DNA in disease.

Activation of endoplasmic reticulum stress mediates oxidative stress-induced apoptosis of granulosa cells in ovaries affected by endometrioma

Endometriosis exerts detrimental effects on ovarian physiology and compromises follicular health. Granulosa cells from patients with endometriosis are characterized by increased apoptosis, as well as high oxidative stress. Endoplasmic reticulum (ER) stress, a local factor closely associated with oxidative stress, has emerged as a critical regulator of ovarian function. We hypothesized that ER stress is activated by high oxidative stress in granulosa cells in ovaries with endometrioma and that this mediates oxidative stress-induced apoptosis. Human granulosa-lutein cells (GLCs) from patients with endometrioma expressed high levels of mRNAs associated with the unfolded protein response (UPR). In addition, the levels of phosphorylated ER stress sensor proteins, inositol-requiring enzyme 1 (IRE1) and double-stranded RNA-activated protein kinase-like ER kinase (PERK), were elevated in granulosa cells from patients with endometrioma. Given that ER stress results in phosphorylation of ER stress sensor proteins and induces UPR factors, these findings indicate that these cells were under ER stress. H2O2, an inducer of oxidative stress, increased expression of UPR-associated mRNAs in cultured human GLCs, and this effect was abrogated by pretreatment with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor in clinical use. Treatment with H2O2 increased apoptosis and the activity of the pro-apoptotic factors caspase-8 and caspase-3, both of which were attenuated by TUDCA. Our findings suggest that activated ER stress induced by high oxidative stress in granulosa cells in ovaries with endometrioma mediates apoptosis of these cells, leading to ovarian dysfunction in patients with endometriosis.

Cancer-associated mutations in endometriosis: shedding light on the pathogenesis and pathophysiology

BACKGROUND

Endometriosis is a benign gynaecological disease. Thus, it came as a complete surprise when it was reported recently that the majority of deep endometriosis lesions harbour somatic mutations and a sizeable portion of them contain known cancer-associated mutations (CAMs). Four more studies have since been published, all demonstrating the existence of CAMs in different subtypes of endometriosis. While the field is still evolving, the confirmation of CAMs has raised many questions that were previously overlooked.

OBJECTIVE AND RATIONALE

A comprehensive overview of CAMs in endometriosis has been produced. In addition, with the recently emerged understanding of the natural history of endometriotic lesions as well as CAMs in normal and apparently healthy tissues, this review attempts to address the following questions: Why has there been such a wild discrepancy in reported mutation frequencies? Why does ectopic endometrium have a higher mutation rate than that of eutopic endometrium? Would the presence of CAMs in endometriotic lesions increase the risk of cancer to the bearers? Why do endometriotic epithelial cells have much higher mutation frequencies than their stromal counterpart? What clinical implications, if any, do the CAMs have for the bearers? Do these CAMs tell us anything about the pathogenesis and/or pathophysiology of endometriosis?

SEARCH METHODS

The PubMed database was searched, from its inception to September 2019, for all papers in English using the term 'endometriosis and CAM', 'endometriosis and cancer-driver mutation', 'somatic mutations', 'fibrosis', 'fibrosis and epigenetic', 'CAMs and tumorigenesis', 'somatic mutation and normal tissues', 'oestrogen receptor and fibrosis', 'oxidative stress and fibrosis', 'ARID1A mutation', and 'Kirsten rat sarcoma mutation and therapeutics'. All retrieved papers were read and, when relevant, incorporated into the review results.

OUTCOMES

Seven papers that identified CAMs in endometriosis using various sequencing methods were retrieved, and their results were somewhat different. Yet, it is apparent that those using microdissection techniques and more accurate sequencing methods found more CAMs, echoing recent discoveries that apparently healthy tissues also harbour CAMs as a result of the replicative aging process. Hence endometriotic lesions, irrespective of subtype, if left intact, would generate CAMs as part of replicative aging, oxidative stress and perhaps other factors yet to be identified and, in some rare cases, develop cancer. The published data still are unable to paint a clear picture on pathogenesis of endometriosis. However, since endometriotic epithelial cells have a higher turnover than their stromal counterpart due to cyclic bleeding, and since the endometriotic stromal component can be formed by refresh influx of mesenchymal cells through epithelial-mesenchymal transition, endothelial-mesenchymal transition, mesothelial-mesenchymal transition and other processes as well as recruitment of bone-marrow-derived stem cells and outflow due to smooth muscle metaplasia, endometriotic epithelial cells have much higher mutation frequencies than their stromal counterpart. The epithelial and stromal cellular components develop in a dependent and co-evolving manner. Genes involved in CAMs are likely to be active players in lesional fibrogenesis, and hyperestrogenism and oxidative stress are likely drivers of both CAMs and fibrogenesis. Finally, endometriotic lesions harbouring CAMs would conceivably be more refractory to medical treatment, due, in no small part, to their high fibrotic content and reduced vascularity and cellularity.

WIDER IMPLICATIONS

The accumulating data on CAMs in endometriosis have shed new light on the pathogenesis and pathophysiology of endometriosis. They also suggest new challenges in management. The distinct yet co-evolving developmental trajectories of endometriotic stroma and epithelium underscore the importance of the lesional microenvironment and ever-changing cellular identity. Mutational profiling of normal endometrium from women of different ages and reproductive history is needed in order to gain a deeper understanding of the pathogenesis. Moreover, one area that has conspicuously received scant attention is the epigenetic landscape of ectopic, eutopic and normal endometrium.

miR-532-3p: a possible altered miRNA in cumulus cells of infertile women with advanced endometriosis

RESEARCH QUESTION

Is the profile of microRNA (miRNA) altered in cumulus cells of infertile women with early (EI/II) and advanced (EIII/IV) endometriosis?

DESIGN

In this prospective case-control study, a miRNA profile including 754 targets was evaluated in samples of cumulus cells from infertile women with endometriosis (5 EI/II, 5 EIII/IV) and infertile controls (5, male and/or tubal factor) undergoing ovarian stimulation for intracytoplasmic sperm injection, using TaqMan® Array Human MicroRNA Cards A and B. The groups were compared with Kruskal-Wallis test, followed by Benjamini-Hochberg correction and Dunn's post hoc test. An in silico enrichment analysis was performed to list the possibly altered pathways in which the altered miRNA target genes are involved.

RESULTS

Only the miRNA miR-532-3p showed significant differences among the analysed groups, being down-regulated in the EIII/IV group compared with the infertile control group, as well as compared with the EI/II group. The enrichment analysis showed that some genes regulated by this miRNA are involved in important pathways for the acquisition of oocyte competence, such as the oxytocin, calcium, Wnt, FoxO, ErbB and Ras signalling pathways, as well as the oocyte meiosis pathway.

CONCLUSION

The present findings bring new perspectives to understanding the follicular microenvironment of infertile women with different stages of endometriosis. It is suggested that the dysregulation of miR-532-3p may be a potential mechanism involved in the aetiopathogenesis of endometriosis-related infertility. Further studies are needed to evaluate these pathways in cumulus cells of infertile women with the disease, as well as their impact on the acquisition of oocyte competence.

Phthalate metabolites and biomarkers of oxidative stress in the follicular fluid of women undergoing in vitro fertilization

Epidemiological studies have suggested that phthalate exposures were associated with adverse reproductive outcomes, such as low oocyte yield and reduced embryo quality, but the underlying mechanisms remained largely unknown. Oxidative stress may be a potential contributor to phthalate-induced adverse reproductive outcomes. To explore the associations between phthalate exposure and levels of oxidative stress among women seeking in vitro fertilization (IVF), we measured the concentrations of eight phthalate metabolites and biomarkers of oxidative stress, including 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA), and total antioxidant capacity (TAC), in follicular fluid (FF) samples collected from 332 women. Multivariable linear regression models were used to assess the associations between phthalate metabolites and biomarkers of oxidative stress in FF samples. The concentrations of most tested phthalate metabolites were positively associated with the 8-OHdG levels. The metabolites of di-(2-ethylhexyl) phthalate (DEHP) were inversely associated with the TAC levels. The concentrations of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) were positively associated with the MDA levels. Our results revealed a positive association between phthalate metabolites and oxidative stress levels in FF, while more toxicological and epidemiological studies are required to confirm our findings.

Decreased Expression of Peroxiredoxin in Patients with Ovarian Endometriosis Cysts

BACKGROUND

Endometriosis (EMT) is a common occurrence in women of reproductive age. Since oxidative stress has been associated with the development and/or progression of the disease, the present study was conducted to detect the expression of peroxiredoxin (PRX) isoforms, including PRX1, PRX2, and PRX3.

METHODS

Fifty-two patients with ovarian endometriosis cysts and 47 controls were included in the study. Serum levels of PRXs were detected by enzyme-linked immunosorbent assay, and the expression of PRX in the endometrium was examined by immunohistochemistry.

RESULTS

Serum PRX1, PRX2, and PRX3 were significantly lower in EMT patients than in controls. The expression of the three isoforms was significantly decreased in ectopic endometrium compared to that in eutopic or control endometrium. There was no difference in PRX expression between eutopic endometrium of EMT patients and control endometrium, and no association was found between serum PRX levels and immunostaining scores.

CONCLUSION

Our results are the first report that PRXs are downregulated in EMT patients, which suggests that PRXs are involved in the oxidative state of the disease.

Malignant Transformation and Associated Biomarkers of Ovarian Endometriosis: A Narrative Review

This review focuses on pathogenesis of endometriosis, its possible biomarkers and role in endometriosis-associated ovarian cancer. We analyzed various databases to obtain new insights, theories, and biomarkers associated with endometriosis. There are several theories of endometriosis development and biomarker changes including atypical forms. A number of studies have attempted to establish specific, reliable biomarkers to help diagnose endometriosis and endometriosis-associated diseases on the basis of different pathogenetic pathways. Nevertheless, despite intensive research extending even to the molecular level, the origin, natural history, malignant transformation, and laboratory management of endometriosis and related diseases are not yet clearly defined. Therefore, early laboratory diagnoses of endometriosis, its atypical form, and endometriosis-associated ovarian tumors are important problems that require further study in the context of advanced therapeutic strategies to provide maximal health benefits to patients.

Excessive oxidative stress in cumulus granulosa cells induced cell senescence contributes to endometriosis-associated infertility

Endometriosis an important cause of female infertility and seriously impact physical and psychological health of patients. Endometriosis is now considered to be a public health problem that deserves in-depth investigation, especially the etiopathogenesis of endometriosis-associated infertility. We aimed to illuminate the etiopathogenesis of endometriosis-associated infertility that involve excessive oxidative stress (OS) induced pathological changes of ovary cumulus granulosa cell (GCs). Senescence-associated β-galactosidase (SA β-gal) activity in GCs from endometriosis patients, soluble isoform of advanced glycation end products receptor (sRAGE) expression in follicular fluid from endometriosis patients and differentially expressed senescence-associated secretory phenotype factors (IL-1β, MMP-9, KGF and FGF basic protein) are all useful indexes to evaluate oocyte retrieval number and mature oocyte number. RNA-sequencing and bioinformatics analysis indicated senescent phenotype of endometriosis GCs and aggravated endoplasmic reticulum (ER) stress in endometriosis GCs. Targeting ER stress significantly alleviated OS-induced GCs senescence as well as mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) reduction in GCs. Moreover, melatonin administration rescued OS-enhanced ER stress, cellular senescence, and MMP and ATP abnormities of endometriosis GCs in vitro and in vivo. In conclusion, our results indicated excessive reactive oxygen species induces senescence of endometriosis GCs via arouse ER stress, which finally contributes to endometriosis-associated infertility, and melatonin may represent a novel adjuvant therapy strategy for endometriosis-associated infertility.

•

Endometriosis patients ovary cumulus granulosa cells (GCs) show senescence phenotype.

•

Excessive oxidative stress in GCs drives cellular senescence via activating ER stress.

•

Melatonin alleviates ER stress and GCs senescence in vitro and in vivo.

Cell-free DNA content in follicular fluid: A marker for the developmental ability of porcine oocytes

PURPOSE

The present study examined the relationships among the amount of cell-free-DNA (cfDNA) in porcine follicular fluid (FF), the developmental ability of enclosed oocytes, and characteristics of granulosa cells and examined the effect of cfDNA content in maturation medium on the developmental ability of the oocytes.

METHODS

Oocytes and FF were collected from individual gilts, and the gilts were rated based on the ability of their oocytes to develop to the blastocyst stage and the amount of cfDNA in the FF. The copy numbers of mitochondrial DNA (Mt-DNA) and nuclear DNA (N-DNA) were measured by real-time PCR and the DNA sequence. FF or cfDNA was added to the maturation medium, and the developmental ability of the oocytes was examined.

RESULTS

The amount of cfDNA was associated with apoptosis of the granulosa cells, and high-cfDNA content in FF was associated with low developmental ability of oocytes. Supplementation of the maturation medium with FF containing high cf-Mt-DNA or with DNA extracted from the FF did not affect oocyte developmental competence.

CONCLUSIONS

Cell-free DNA content in FF is a marker for oocyte competence, but cfDNA in the oocyte maturation environment did not affect oocyte developmental ability.

The Role of Fertility Preservation in Women with Endometriosis: A Systematic Review

OBJECTIVE

To summarize the available evidence concerning fertility preservation techniques in the context of women with endometriosis.

DATA SOURCES

We searched for studies published between 1984 and 2019 on endometriosis and Assisted Reproductive Technology outcomes. We searched MEDLINE and PubMed and performed a manual search of reference lists within identified studies.

METHODS OF STUDY SELECTION

A total of 426 articles were identified, and 7 studies were eligible to be included for the systematic review. We included all published studies, excluding reviews, case reports, and animal studies.

TABULATION, INTEGRATION, AND RESULTS

Despite a significant increase in the number of studies addressing fertility preservation over the study period, we found a relative lack of evidence addressing the use of fertility preservation techniques in women with endometriosis. The studies identified included 2 case reports, 1 histological science study, and 4 retrospective cohort studies.

CONCLUSION

Women with endometriosis may benefit from fertility preservation techniques. However, there currently is a paucity of data in this population, especially when compared with other indications for fertility preservation. Although much knowledge can be translated from the oncofertility discipline, we have identified and discussed endometriosis-related changes to ovarian reserve and oocyte health that justify further well-designed research to confirm that fertility preservation outcomes are similar for women with endometriosis.

Ethiopathogenic mechanisms of endometriosis-related infertility

Endometriosis is a highly prevalent disease among women of reproductive age and is frequently associated to infertility. However, the mechanisms underlying endometriosis-related infertility are still not completely known. Several studies have been conducted in order to elucidate this question. Besides anatomical changes that may impair gametes and embryo transport along the tubes; a smaller ovarian reserve due to advanced endometriosis and endometriomas; and a dysregulated hypothalamic-pituitary-ovarian axis, there are pieces of evidence suggesting that the peritoneal ectopic endometrial foci may induce a local inflammatory response, with the recruitment of macrophages, cytokine release, and reactive oxygen species generation, leading to a pro-oxidant peritoneal microenvironment. These alterations may be systemically reflected and also affect the follicular microenvironment. A harmful follicular fluid may disrupt cumulus cells functions and, consequently, compromise oocyte competence. There is also evidence suggesting that the peritoneal fluid of women with endometriosis may alter sperm function. Reduced endometrial receptivity is also pointed as a possible mechanism involved in endometriosis-related infertility, which needs further investigation.

Systemic oxidative stress as a possible mechanism underlying the pathogenesis of mild endometriosis-related infertility

RESEARCH QUESTION

Does systemic oxidative stress occur during the early follicular phase of the menstrual cycle in infertile women with minimal (stage I) or mild (stage II) endometriosis? Are serum oxidative stress markers during the early follicular phase of the menstrual cycle good predictors of successful gestation in these women who undergo ovarian stimulation for intracytoplasmic sperm injection (ICSI)?

MATERIALS AND METHODS

A pilot study (prospective case-control study) was conducted in a University Hospital. Serum samples were obtained during the early follicular phase of the natural cycle preceding ovarian stimulation for ICSI of infertile women (with and without stage I and II endometriosis, the latter having male factor infertility). Total hydroperoxides (FOX1), malondialdehyde, advanced oxidation protein products, reduced glutathione, superoxide dismutase, total antioxidant capacity (TAC), 8-hydroxy-2'-deoxyguanosine (8OHdG) and vitamin E were analysed in serum from 35 women with stage I or II endometriosis and 60 control women. The accuracy of oxidative stress markers for predicting clinical pregnancy and live births was determined by receiver operator characteristic curves.

RESULTS

Women with stage I and II endometriosis showed lower serum 8OHdG concentrations (16.02 ng/ml) compared with the control group (22.08 ng/ml). The best predictor for clinical pregnancy and live births was TAC, whereas FOX1 was the best predictor of clinical pregnancy in the control group.

CONCLUSIONS

Infertile women with stage I and II endometriosis present systemic oxidative stress during the early follicular phase of the menstrual cycle. Some oxidative stress markers were good predictors of clinical pregnancy and live births after ICSI. Serum TAC was predictive of clinical pregnancy and live births after ICSI in women with stage I or II endometriosis.

Cell-free DNA in medium is associated with the maturation ability of in vitro cultured oocytes

Follicular fluid contains cell-free DNA (cfDNA), which may serve as a useful biomarker of oocyte ability. The present study evaluates whether nuclear and mitochondrial cfDNAs in conditioned oocyte growth medium determine the quality of oocytes cultured in vitro. Oocyte and granulosa cell complexes (OGCs) derived from early antral follicles of gilt ovaries were cultured for 14 days and the amount of cfDNA and lactate concentration in the conditioned culture medium were measured and compared to evaluate oocyte maturation ability. The amount of nuclear cfDNA, but not mitochondrial cfDNA, strongly correlated with the number of dead cells in OGCs. Furthermore, low mitochondrial cfDNA content and high lactate concentration in the medium was associated with high maturation ability of oocytes cultured in vitro. In conclusion, the amounts of nuclear and mitochondrial cfDNAs differentially reflect the conditions of OGCs, and low mitochondrial cfDNA, low glucose content, and high lactate concentration in the medium are associated with the proper maturation of oocytes.

Influence of follicular fluid and cumulus cells on oocyte quality: clinical implications

An equilibrium needs to be established by the cellular and acellular components of the ovarian follicle if developmental competence is to be acquired by the oocyte. Both cumulus cells (CCs) and follicular fluid (FF) are critical determinants for oocyte quality. Understanding how CCs and FF influence oocyte quality in the presence of deleterious systemic or pelvic conditions may impact clinical decisions in the course of managing infertility. Given that the functional integrities of FF and CCs are susceptible to concurrent pathological conditions, it is important to understand how pathophysiological factors influence natural fertility and the outcomes of pregnancy arising from the use of assisted reproduction technologies (ARTs). Accordingly, this review discusses the roles of CCs and FF in ensuring oocyte competence and present new insights on pathological conditions that may interfere with oocyte quality by altering the intrafollicular environment.

The Role of Oxidative Stress and Membrane Transport Systems during Endometriosis: A Fresh Look at a Busy Corner

Endometriosis is a condition characterized by the presence of endometrial tissue outside the uterine cavity, leading to a chronic inflammatory reaction. It is one of the most widespread gynecological diseases with a 10-15% prevalence in the general female population, rising up to 30-45% in patients with infertility. Although it was first described in 1860, its etiology and pathogenesis are still unclear. It is now accepted that inflammation plays a central role in the development and progression of endometriosis. In particular, it is marked by an inflammatory process associated with the overproduction of an array of inflammatory mediators such as prostaglandins, metalloproteinases, cytokines, and chemokines. In addition, the growth and adhesion of endometrial cells in the peritoneal cavity due to reactive oxygen species (ROS) and free radicals lead to disease onset, its ensuing symptoms-among which pain and infertility. The aim of our review is to evaluate the role of oxidative stress and ROS in the pathogenesis of endometriosis and the efficacy of antioxidant therapy in the treatment and mitigation of its symptoms.

Implications of immune dysfunction on endometriosis associated infertility

Endometriosis is a complex, inflammatory disease that affects 6-10% of reproductive-aged women. Almost half of the women with endometriosis experience infertility. Despite the excessive prevalence, the pathogenesis of endometriosis and its associated infertility is unknown and a cure is not available. While many theories have been suggested to link endometriosis and infertility, a consensus among investigators has not emerged. In this extensive review of the literature as well as research from our laboratory, we provide potential insights into the role of immune dysfunction in endometriosis associated infertility. We discuss the implication of the peritoneal inflammatory microenvironment on various factors that contribute to infertility such as hormonal imbalance, oxidative stress and how these could further lead to poor oocyte, sperm and embryo quality, impaired receptivity of the endometrium and implantation failure.

A Biochemical Approach to Detect Oxidative Stress in Infertile Women Undergoing Assisted Reproductive Technology Procedures

Oxidative stress plays a major role in critical biological processes in human reproduction. However, a reliable and biologically accurate indicator of this condition does not yet exist. On these bases, the aim of this study was to assess and compare the blood and follicular fluid (FF) redox status of 45 infertile subjects (and 45 age-matched controls) undergoing in vitro fertilization (IVF), and explore possible relationships between the assessed redox parameters and IVF outcomes. Reactive Oxygen Species (ROS) production, assessed by flow cytometry analysis in blood leukocytes and granulosa cells, significantly increased (p < 0.05) in infertile patients. Also, oxidative stress markers—ThioBarbituric Acid-Reactive Substances (TBARS) as an index of lipid peroxidation, and Oxygen Radical Absorbance Capacity (ORAC) to account for total antioxidant capacity, both assayed by fluorometric procedures—in blood and FF were significantly (p < 0.001) modified in infertile patients compared to the control group. Moreover, a significant correlation between blood redox markers and FF redox markers was evident. An ORAC/TBARS ratio, defined as the redox index (RI), was obtained in the plasma and FF of the patients and controls. In the patients, the plasma RI was about 3.4-fold (p < 0.0001) lower than the control, and the FF RI was about six-fold (p < 0.0001) lower than the control. Interestingly, both the plasma RI and FF RI results were significantly correlated (p < 0.05) to the considered outcome parameters (metaphase II, fertilization rate, and ongoing pregnancies). Given the reported findings, a strict monitoring of redox parameters in assisted reproductive techniques and infertility management is recommended.

Advanced oxidation protein products from the follicular microenvironment and their role in infertile women with endometriosis

Endometriosis (EM) is associated with oxidative stress. Advanced oxidation protein products (AOPPs) are novel markers of oxidative stress, which serve an important role as an inflammatory mediator in various chronic diseases. In order to examine the role of AOPPs in infertile women with EM, the present study analyzed the levels of AOPPs, estradiol (E₂) and progesterone (P₄) in the follicular fluid (FF) of 89 women with or without EM undergoing in vitro fertilization (IVF). The AOPP concentration in the FF of the EM group was significantly higher when compared with that of the control group (51.5±22.4 vs. 41.8±18.3 µmol/l; P<0.05). However, the FF P₄ levels and blastocyst rate were significantly lower in the EM group compared with the control group (P₄:1,249.6±465.4 vs. 1,752.7±565.4 ng/ml, P<0.05; blastocyst rate: 0.511±0.322 vs. 0.662±0.278; P<0.05). The AOPP concentration and P₄ level in the FF presented a significant negative correlation in the EM and control groups, as well as in the total cohort of patients (EM group: r=-0.406, P=0.006; control group: r=-0.315, P=0.035; total: r=-0.421, P<0.001). In addition, there was a significant negative correlation between the FF AOPP concentrations and blastocyst rate in the EM group and in the total cohort (EM group: r=-0.376, P=0.012; total: r=-0.367, P<0.001). In conclusion, these results suggested that AOPPs may be a potentially effective marker for predicting the oocyte quality and outcomes of IVF in infertile women with EM.

Oxidative Stress in Granulosa-Lutein Cells From In Vitro Fertilization Patients

Ovarian aging is associated with gradual follicular loss by atresia/apoptosis. Increased production of toxic metabolites such as reactive oxygen species (ROS) and reactive nitrogen species as well as external oxidant agents plays an important role in the process of ovarian senescence and in the pathogenesis of ovarian pathologies such as endometriosis and polycystic ovary syndrome (PCOS). This review provides a synthesis of available studies of oxidative stress (OS) in the ovary, focusing on the most recent evidence obtained in mural granulosa-lutein (GL) cells of in vitro fertilization patients. Synthesis of antioxidant enzymes such as peroxiredoxin 4, superoxide dismutase, and catalase and OS damage response proteins such as aldehyde dehydrogenase 3, member A2 decreases with aging in human GL cells, favoring an unbalance in ROS/antioxidants that mediates molecular damage and altered cellular function. The increase in OS in the granulosa cell correlates with diminished expression of follicle-stimulating hormone receptor (FSHR) and a dysregulation of the FSHR signaling pathway and may be implicated in disrupted steroidogenic function and poor response to FSH in women with aging. Women with endometriosis and PCOS have lower antioxidant production capacity that may contribute to abnormal follicular development and infertility. Further investigation of the signaling pathways involved in cellular response to OS could shed light into molecular characterization of these diseases and development of new treatment strategies to improve reproductive potential in these women.

Iron overload and altered iron metabolism in ovarian cancer

Iron is an essential element required for many processes within the cell. Dysregulation in iron homeostasis due to iron overload is detrimental. This nutrient is postulated to contribute to the initiation of cancer; however, the mechanisms by which this occurs remain unclear. Defining how iron promotes the development of ovarian cancers from precursor lesions is essential for developing novel therapeutic strategies. In this review, we discuss (1) how iron overload conditions may initiate ovarian cancer development, (2) dysregulated iron metabolism in cancers, (3) the interplay between bacteria, iron, and cancer, and (4) chemotherapeutic strategies targeting iron metabolism in cancer patients.

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).

Follicular Fluid redox involvement for ovarian follicle growth

As the human ovarian follicle enlarges in the course of a regular cycle or following controlled ovarian stimulation, the changes in its structure reveal the oocyte environment composed of cumulus oophorus cells and the follicular fluid (FF).

In contrast to the dynamic nature of cells, the fluid compartment appears as a reservoir rich in biomolecules. In some aspects, it is similar to the plasma, but it also exhibits differences that likely relate to its specific localization around the oocyte. The chemical composition indicates that the follicular fluid is able to detect and buffer excessive amounts of reactive oxygen species, employing a variety of antioxidants, some of them components of the intracellular milieu.

An important part is played by albumin through specific cysteine residues. But the fluid contains other molecules whose cysteine residues may be involved in sensing and buffering the local oxidative conditions. How these molecules are recruited and regulated to intervene such process is unknown but it is a critical issue in reproduction.

In fact, important proteins in the FF, that regulate follicle growth and oocyte quality, exhibit cysteine residues at specific points, whose untoward oxidation would result in functional loss. Therefore, preservation of controlled oxidative conditions in the FF is a requirement for the fine-tuned oocyte maturation process. In contrast, its disturbance enhances the susceptibility to the establishment of reproductive disorders that would require the intervention of reproductive medicine technology.