Effect of induced peritoneal endometriosis on oocyte and embryo quality in a mouse model

Metformin reverses infertility in a mouse model of endometriosis: unveiling disease pathways and implications for future clinical approaches

RESEARCH QUESTION

Does metformin reverse endometriosis-associated infertility?

DESIGN

Endometriosis was induced by transplanting uterus fragments from B6CBAF1 mice into recipients of the same strain. The mice were divided into groups: endometriosis (End, n = 24), sham-operated (Sham, n = 12), endometriosis with metformin (0.5mg/ml) orally administered for 3 months (EndMet, n = 21) and sham-operated metformin-treated (ShamMet, n = 16). Implant growth was monitored using ultrasonography. Fibrosis was computer-assisted quantified in Masson's trichrome-stained sections of eutopic (EuEnd) and ectopic (EcEnd) endometrium. PCNA, CYP17a1, F4/80 and galectin-3 were analysed by immunofluorescence and western blotting, and NFkB, GPX-1 and HO-1 only by western blotting. Statistical significance was set at P <0.05.

RESULTS

The endometriosis model was successfully established. The End groups showed lower fertility rates than sham-operated mice (P = 0.0034), whereas metformin treatment increased the number of fetuses per pregnant mouse (P = 0.0295), restoring fertility to control levels; it also slowed implant growth and vascularization. Metformin also restored PCNA expression and fibrosis levels to those of non-treated EuSham mice. PCNA expression decreased in pregnant mice (P <0.0178). Metformin diminished CYP17a1 expression in EcEnd versus EuEnd non-treated tissues and conversely up-regulated F4/80 in EuEnd tissue (P <0.0170), and galectin-3, NFkB and the antioxidant enzymes HO-1 and GPX-1 in EcEnd tissue (P <0.0293), in non-mated mice.

CONCLUSIONS

These results indicate that application of metformin can alleviate oxidative stress and mitigate fibrosis in endometriosis lesions in a murine model of endometriosis, which highlights metformin's potential as a pharmacological intervention for improving infertility in endometriosis.

Single-cell dual-omics reveals translational and transcriptional landscapes and regulations in oocytes from ovarian endometriosis patients

Introduction

A significant proportion of women in their reproductive years are afflicted by endometriosis. And one of the major contributing factors to infertility linked to ovarian endometriosis is thought to be oocyte quality. The precise molecular mechanisms are still unknown. Furthermore, because of transcriptional silence, translatome is better able to explain molecular behavior in oocytes than transcriptome sequencing, which has been used widely in recent years.

Methods

We conducted single-cell transcriptome and translatome sequencing on oocytes obtained from patients with ovarian endometriosis, as well as from control subjects with infertility due to tubal or male factors.

Results

For the first time, we characterized the translational and transcriptional profiles of mRNA in GV-stage oocytes from patients with ovarian endometriosis and control subjects. Our translational analysis identified 2,480 differentially expressed genes in oocytes from ovarian endometriosis patients. Furthermore, we demonstrated that global translational activity in human oocytes is significantly altered by ovarian endometriosis. Key pathways such as "oxidative stress," "oocyte meiosis," and "spliceosome" were identified as critical factors influencing oocyte quality in ovarian endometriosis patients.

Discussion

This study elucidated the molecular characteristics and potential mechanisms underlying poor oocyte quality in patients with ovarian endometriosis. Our findings provided new insights into the pathogenesis of endometriosis-associated infertility and highlighted potential therapeutic targets for improving oocyte quality and reproductive outcomes.

Does endometriosis inflict harm on embryos? A systematic review of embryo morphokinetics analysed by time lapse monitoring in women with endometriosis

Endometriosis has been shown to be associated with unfavorable development and maturation of oocytes, as well as aberrancies in embryonal development, including arrest after fertilization, following in vitro fertilization (IVF). Time-lapse monitoring (TLM) enables continuous and non-invasive monitoring of embryo morphokinetics during the IVF process and might be useful in the assessment of embryos from women with endometriosis. In this review, five eligible studies were evaluated to determine if embryo morphokinetics assessed under TLM differ in patients with endometriosis and subsequently predict blastocyst quality, implantation and success of pregnancy. The studies showed overall inferior morphokinetic parameters of embryos from endometriosis patients when compared to controls, independent of the severity of endometriosis. Embryos with optimal early morphokinetic parameters (t2, s2, t5, tSB, tEB) and late developmental events (compaction, morulation, and blastulation) had better implantation rates than those who had suboptimal ranges. However, due to few studies available with mostly retrospective data, the validity of these findings and their generalizability for clinical practice needs to be further assessed. Prospective studies with larger sample sizes are needed to determine whether using TLM for embryo selection in endometriosis improves pregnancy and live birth outcomes.

Patient experiences of being advised by a healthcare professional to get pregnant to manage or treat endometriosis: a cross-sectional study

BACKGROUND

There is a lack of evidence that pregnancy reduces endometriotic lesions or symptoms, however studies indicate that people with endometriosis are commonly advised to get pregnant to manage or treat endometriosis. This study sought to examine the impact of this advice on patients with endometriosis when the advice was provided by healthcare professionals.

METHODS

The Endometriosis Patient Experience Survey was a self-reported, community-based, cross-sectional online survey of people who had been medically diagnosed with endometriosis. Descriptive statistics were used to analyse the quantitative survey data and thematic analysis was undertaken for the qualitative survey data.

RESULTS

1892 participants had received the advice to get pregnant or have a baby to manage or treat their endometriosis, with 89.4% of participants receiving this advice from healthcare professionals. In exploring the qualitative data, seven themes were contextualised relating to the impact of this advice in terms of health literacy, accepting the advice, rejecting the advice, major life decisions, healthcare interactions, mental health and relationships.

CONCLUSIONS

This study demonstrates profound and often negative patient impacts of the advice from healthcare professionals to get pregnant to manage or treat endometriosis. Impacts ranged from planning for pregnancy, hastening the making of major life decisions, eroding trust with healthcare professionals, worsening mental health and straining relationships. Providing evidence-based information on the treatment and management of endometriosis is essential. Pregnancy or having a baby should not be suggested as a treatment for endometriosis and the provision of this advice by healthcare professionals can have negative impacts on those who receive it.

Surgical management of endometriosis to optimize fertility

PURPOSE OF REVIEW

Surgery is an integral element of treatment for infertility caused by endometriosis. This review summarizes the purported mechanisms of infertility in endometriosis, as well as the impacts of surgery for endometriosis on fertility, including pregnancy achieved spontaneously and with assisted reproductive technology (ART).

RECENT FINDINGS

Endometriosis' effect on fertility is multifactorial. The sequela of increased inflammation resulting from endometriosis causes alterations in ovarian, tubal, and uterine function. Removing or destroying these lesions reduces inflammation. Surgical treatment of both early-stage endometriosis and deeply infiltrating endometriosis improves spontaneous pregnancy rates and ART pregnancy rates. Conventional or robotic laparoscopy is the preferred surgical approach.

SUMMARY

Endometriosis has detrimental effects on fertility, including negative impacts on oocyte, tubal, and endometrial function. Laparoscopic surgery for endometriosis elevates both spontaneous and ART pregnancy rates above those achieved with expectant management alone. The resection or destruction of endometriosis implants reduces inflammation, which likely improves the multifactorial infertility related to endometriosis. This topic is complex and controversial; more research in the form of high-quality randomized control trials is needed.

Does Endometriosis Impact the Composition of Follicular Fluid in IL6 and AMH? A Case-Control Study

OBJECTIVE

The aim of this study was to compare follicular liquid levels of IL6 and AMH in women with and without endometriosis and to evaluate their potential impact on ICSI outcomes.

MATERIALS AND METHODS

It is a prospective case-control study conducted on 25 women with proven endometriosis and 50 patients diagnosed with other causes of infertility. All these patients were candidates for ICSI cycles. Their follicular fluid was collected at the time of oocyte retrieval and used to evaluate IL-6 and AMH titers by electro-chemiluminescent immunoassay (Cobas e411-Roche).

RESULTS

The IL-6 levels in follicular fluid were higher in the endometriosis group than in the control group (152.3 vs. 19.9 pg/mL; p = 0.02). The median level for AMH was 2.2 ± 1.88 ng/mL with no statistical difference between the two groups (2.2 vs. 2.7 ng/mL, p = 0.41). No significant correlation between the follicular IL6 and AMH levels was observed.

CONCLUSIONS

The oocyte quality seems to be preserved in patients with endometriosis with the adequate response to ovarian stimulation. High levels of follicular IL6 are in accordance with the inflammatory phenomenon of the disease; however, this increase has no impact on ICSI outcomes.

Anti-oxidant effect of metformin through AMPK/SIRT1/PGC-1α/SIRT3- independent GPx1 expression in the heart of mice with endometriosis

OBJECTIVES

Endometriosis is a gynecological disease associated with an imbalance between oxidative species production and anti-oxidative defenses. In women, endometriosis has been reported to associate with increased incidence of cardiovascular events. As such, this study aimed to analyze the oxidation-responsive AMPK/SIRT1/PGC-1α/SIRT3 pathway in the heart of a mouse model of endometriosis. The effect of metformin, an insulin-sensitizing and anti-oxidative drug with already shown positive results in endometriotic tissue was studied.

METHODS

Thirty-six female B6CBA/F1 mice were divided into 4 groups (Control-C, Surgery-induced Endometriosis and Metformin-EM (50 mg/kg/day orally administrated for 3 months), Endometriosis-E and Metformin-M). Immunofluorescent labelling of SIRT1 and SIRT3 was performed in the heart tissue. Assessment of expression of AMPKα, SIRT1, PGC-1α, SIRT3, SOD2, and GPx1 was performed by Western Blotting. The quantification of microRNA(miR)-34a, miR-195, miR-217, miR-155 and miR-421, involved in the regulation of expression of SIRT1 and SIRT3, was performed by Real-Time PCR.

RESULTS

Data showed an increase in phospho-AMPKα and in GPx1 expression in the EM group when compared to the C group, but not in the total AMPK, SIRT1, PGC-1α, SIRT3 and SOD2, suggesting a GPx1 expression increase independently of the AMPK/SIRT1/PGC-1α/SIRT3 pathway. MicroRNAs, excepting miR-217, showed a consistent trend of increase in the M group.

CONCLUSIONS

Our study showed that endometriosis does not significantly affect the expression of the components of the AMPK/SIRT1/PGC-1α/SIRT3 pathway in the heart. However, it indicates that an oxidative condition underlying endometriosis is required for metformin to evidence an increment in the expression of the anti-oxidative enzyme GPx1.

Metformin Prevents Endothelial Dysfunction in Endometriosis through Downregulation of ET-1 and Upregulation of eNOS

This study aimed to evaluate if the treatment with metformin affects the morphologic structure, endothelial function, angiogenesis, inflammation and oxidation-responsive pathways in the heart of mice with surgically induced endometriosis. B6CBA/F1 mice (n = 37) were divided into four groups; Sham (S), Metformin (M), Endometriosis (E) and Metformin/Endometriosis (ME). The cross-sectional area of cardiomyocytes was assessed after Hematoxylin-Eosin staining and fibrosis after Picrosirius-Red staining. ET-1, nitric oxide synthases-iNOS and eNOS, and VEGF and VEGFR-2 were detected by immunofluorescence. Semi-quantification of ET-1, eNOS, VEGF, NF-kB, Ikβα and KEAP-1 was performed by Western blotting. MIR199a, MIR16-1, MIR18a, MIR20a, MIR155, MIR200a, MIR342, MIR24-1 and MIR320a were quantified by Real-Time qPCR. The interaction of endometriosis and metformin effects was assessed by a two-way ANOVA test. Compared with the other groups, M-treated mice presented a higher cross-sectional area of cardiomyocytes. Heart fibrosis increased with endometriosis. Treatment of endometriosis with metformin in the ME group downregulates ET-1 and upregulates eNOS expression comparatively with the E group. However, metformin failed to mitigate NF-kB expression significantly incremented by endometriosis. The expression of MIR199a, MIR16-1 and MIR18a decreased with endometriosis, whereas MIR20a showed an equivalent trend, altogether reducing cardioprotection. In summary, metformin diminished endometriosis-associated endothelial dysfunction but did not mitigate the increase in NF-kB expression and cardiac fibrosis in mice with endometriosis.

Infertility workup: identifying endometriosis

Endometriosis was classically diagnosed during diagnostic laparoscopies, which used to be routinely performed up until a decade ago or so. This practice fitted with the long-held belief that surgery was the gold standard for diagnosing endometriosis. Today, the abandon of routine diagnostic laparoscopies-in favor of assisted reproductive technology-first therapeutic approaches-has created a void for diagnosing endometriosis. Modern-day imaging techniques-ultrasound and magnetic resonance imaging-when used with a systematic approach have offered a reliable replacement option for diagnosing endometriosis. In infertility, endometriosis should be identified or excluded on the basis of past history or confirmation or exclusion suspicion on the basis of history and/or physical examination.

Endometriosis in the Mouse: Challenges and Progress Toward a ‘Best Fit’ Murine Model

Endometriosis is a prevalent gynecologic condition associated with pelvic pain and infertility characterized by the implantation and growth of endometrial tissue displaced into the pelvis via retrograde menstruation. The mouse is a molecularly well-annotated and cost-efficient species for modeling human disease in the therapeutic discovery pipeline. However, as a non-menstrual species with a closed tubo-ovarian junction, the mouse poses inherent challenges as a preclinical model for endometriosis research. Over the past three decades, numerous murine models of endometriosis have been described with varying degrees of fidelity in recapitulating the essential pathophysiologic features of the human disease. We conducted a search of the peer-reviewed literature to identify publications describing preclinical research using a murine model of endometriosis. Each model was reviewed according to a panel of ideal model parameters founded on the current understanding of endometriosis pathophysiology. Evaluated parameters included method of transplantation, cycle phase and type of tissue transplanted, recipient immune/ovarian status, iterative schedule of transplantation, and option for longitudinal lesion assessment. Though challenges remain, more recent models have incorporated innovative technical approaches such as in vivo fluorescence imaging and novel hormonal preparations to overcome the unique challenges posed by murine anatomy and physiology. These models offer significant advantages in lesion development and readout toward a high-fidelity mouse model for translational research in endometriosis.

The effectiveness of antioxidant therapy (vitamin C) in an experimentally induced mouse model of ovarian endometriosis

Objectives:

This study investigates the therapeutic effect of vitamin C on the development of endometrial lesions and fecundity disorders in the ovarian induction model of mouse endometriosis.

Methods:

Ovarian endometriosis was surgically induced in 14 NMRI female mice (treatment group, N = 7) and (control group, N = 7). Three days after the second surgery (to assess endometriotic implant), the mice were randomized into two intervention groups: control (placebo) and treatment (50 mg/kg vitamin C every two days orally for four weeks) groups. In the oestrus phase, the mice were sacrificed. In macroscopic assessment, endometriotic implants were evaluated in size, volume, weight, growth score and adhesion score. The microscopic assessment examined the ovarian tissue (the number of antral follicles, corpus luteum and atretic follicles) and endometriotic lesion (histologic and trichrome fibrosis scores).

Results:

Post-treatment implant volume, growth score, adhesion extent score and adhesion severity score were significantly lower in the treatment group (vitamin C) in comparison with the control group (placebo) (p < 0.0001). The difference between the median weight of endometriotic implants, epithelialization of implant tissue, trichrome fibrosis scores and follicle number in the two groups (treatment and control) was statistically significant (p < 0.05). Atretic follicles were significantly decreased after vitamin C therapy (p < 0.05). Although the numbers of corpus luteum seemed to be more preserved in specimens from the control group, there was no statistical significance between the two groups’ histological scores.

Conclusion:

As a result, we may imply that vitamin C has a significant effect on reducing the induction and growth of endometrial implants, improving the fecundity function of ovaries, and consequently prevention of endometriosis-associated cancers. Further research is needed to improve targeted interventions resulting in the prevention and treatment of human endometriosis.

Iron overload in endometriosis peritoneal fluid induces early embryo ferroptosis mediated by HMOX1

Endometriosis is one of the most common disorders that causes infertility in women. Iron is overloaded in endometriosis peritoneal fluid (PF), with harmful effects on early embryo development. However, the mechanism by which endometriosis peritoneal fluid affects embryonic development remains unclear. Hence, this study investigated the effect of iron overload on mouse embryos and elucidated the molecular mechanism. Iron overload in endometriosis PF disrupted blastocyst formation, decreased GPX4 expression and induced lipid peroxidation, suggesting that iron overload causes embryotoxicity and induces ferroptosis. Moreover, mitochondrial damage occurs in iron overload-treated embryos, presenting as decreased ATP levels, increased ROS levels and MMP hyperpolarization. The cytotoxicity of iron overload is attenuated by the ferroptosis inhibitor Fer-1. Furthermore, Smart-seq analysis revealed that HMOX1 is upregulated in embryo ferroptosis and that HMOX1 suppresses ferroptosis by maintaining mitochondrial function. This study provides new insight into the mechanism of endometriosis infertility and a potential target for future endometriosis infertility treatment efforts.

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.

Getting to Know Endometriosis-Related Infertility Better: A Review on How Endometriosis Affects Oocyte Quality and Embryo Development

Endometriosis-related infertility describes a case of deteriorated fecundity when endometriosis is diagnosed. Numerous mechanisms have been proposed in an effort to delineate the multifaceted pathophysiology that induces impairment of reproductive dynamics in patients with endometriosis. In this critical analysis, authors present the plethora of molecular events that are entailed and elaborate on how they potentially impair the oocyte's and embryo's competence in patients with endometriosis. Reactive oxygen species, dysregulation of the immune system and cellular architectural disruption constitute the crucial mechanisms that detrimentally affect oocyte and embryo developmental potential. The molecular level impairment of the reproductive tissue is discussed, since differentiation, proliferation and apoptosis constitute focal regulatory cellular functions that appear severely compromised in cases of endometriosis. Mapping the precise molecular mechanisms entailed in endometriosis-related infertility may help delineate the complex nature of the disorder and bring us a step closer to a more personalized approach in understanding, diagnosing and managing endometriosis-related infertility.

The Graduated Embryo Score of Embryos from Infertile Women with and without Peritoneal Endometriosis

OBJECTIVE

 To determine embryo quality (mean graduated embryo score [GES]) in infertile patients with endometriosis undergoing in vitro fertilization with embryo transfer (IVF-ET) compared with infertile patients without endometriosis.

METHODS

 A case-control study was performed comparing 706 embryos (162 patients) divided into 2 groups: 472 embryos derived from patients without endometriosis (n = 109, infertile patients with tubal infertility) and 234 embryos from patients in the study group (n = 53, infertile patients with peritoneal endometriosis). All patients were subjected to IVF using an oestradiol-antagonist-recombinant follicle-stimulating hormone (FSH) protocol for ovarian stimulation. The mean GES was performed to evaluate all embryos at 3 points in time: 16 to 18 hours, 25 to 27 hours, and 64 to 67 hours. Embryo evaluation was performed according to the following parameters: fragmentation, nucleolar alignment, polar body apposition, blastomere number/morphology, and symmetry. The primary outcome measure was the mean GES score. We also compared fertilization, implantation, and pregnancy rates.

RESULTS

 Although the number of embryos transferred was greater in patients with endometriosis than in the control group (2.38 ± 0.66 versus 2.15 ± 0.54; p = 0.001), the mean GES was similar in both groups (71 ± 19.8 versus 71.9 ± 23.5; p = 0.881). Likewise, the fertilization rate was similar in all groups, being 61% in patients with endometriosis and 59% in the control group (p = 0.511). No significant differences were observed in the implantation (21% versus 22%; [p = 0.989]) and pregnancy rates (26.4% versus 28.4%; p = 0.989).

CONCLUSION

 Embryo quality measured by the mean GES was not influenced by peritoneal endometriosis. Likewise, the evaluated reproductive outcomes were similar between infertile patients with and without endometriosis.

The Significance of Planned Fertility Preservation for Women With Endometrioma Before an Expected Ovarian Cystectomy

Endometrioma is known to reduce the ovarian reserve and the extent of the decrease is more severe when ovarian surgery is performed. Therefore, to prevent this decline in fertility, patients with endometrioma are considered candidates for preoperative fertility preservation (FP). In this study, we evaluate the efficacy of FP in women with endometrioma before planned ovarian surgery. A total of 95 cycles in 62 patients with endometrioma, undergoing controlled ovarian stimulation (COS) for FP using a gonadotropin-releasing hormone (GnRH) antagonist protocol before an expected ovarian surgery, were enrolled retrospectively. COS outcomes were compared according to endometrioma laterality. Additionally, first COS cycle outcomes in patients with endometrioma were compared with those in infertile patients, or in patients with a benign ovarian cyst using propensity score matching. When multiple COS cycles were performed, the results of cumulative cycles were analyzed. Embryo quality was worse in the bilateral endometrioma group. Compared with the infertile patient group, the patients with endometrioma had significantly lower Anti-Müllerian Hormone (AMH) and fewer numbers of oocytes retrieved (median, 3.3 vs. 1.2, p<0.001; 7.0 vs. 4.0, p=0.009, respectively). Compared with mature oocytes in infertile patients or patients with a benign cyst, mature oocytes were fewer in patients with endometrioma, but this was not statistically significant (median, 4.0 vs. 3.0, p=0.085; 5.5 vs. 3.0, p=0.052, respectively). The median value of the cumulative number of cryopreserved oocytes or embryos was 14.5 up to the fourth cycle compared to 3 up to the first cycle, with cumulative effect. Women with endometrioma should be counseled for FP before planned ovarian cystectomy. The number of cryopreserved oocytes or embryos can be increased by repeated cycles.

Endometriosis shows no impact on the euploid blastocyst rate per cohort of inseminated metaphase-II oocytes: A case-control study

OBJECTIVE

To evaluate the true impact of endometriosis on oocytes' competence defined as blastulation, euploidy and implantation rates.

DESIGN

Retrospective multicenter case-control study involving infertile couples undergoing ICSI with qPCR and trophectoderm biopsy-based PGT-A. Patients affected from endometriosis (n = 210) were diagnosed through transvaginal sonography or surgical history with histological confirmation. Each case was matched to two controls (n = 420) according to IVF clinic, maternal age at retrieval (38.6 ± 2.7 yr), number of previous failed IVF treatments (0.5 ± 0.8) and number of metaphase-II oocytes retrieved (6.1 ± 3.7 per patient). The primary outcome was the mean euploid blastocyst rate per cohort of inseminated metaphase-II oocytes. Other embryological, clinical, obstetric and neonatal outcomes were also evaluated.

RESULTS

The mean euploid blastocyst rate per cohort of inseminated metaphase-II oocytes was identical in the two groups (18 %±22 %) independently of maternal age. No difference was shown for all embryological outcomes investigated. The live birth rates per vitrified-warmed single euploid blastocyst transfer were also similar (67/158, 42 % in patients affected from endometriosis versus 132/327, 40 % in matched-controls). No difference was reported in the gestational and neonatal outcomes. The cumulative live birth delivery rates among completed cycles were also identical (61/201, 30 % versus 117/391, 30 % in endometriosis and matched-control groups, respectively) independently of maternal age.

CONCLUSIONS

Endometriosis might not impair oocyte developmental and reproductive competence, although its potential impact on the number of metaphase-II oocytes retrieved cannot be ignored. This information is critical for clinicians during counseling to outline an effective strategy to treat infertile patients affected from this condition. Future prospective studies are needed to evaluate the impact of endometriosis stage on euploidy rates.

Endometriosis and Reproduction: What We Have Learned

Endometriosis, despite only affecting 10-15% of women of fertile age, is still an enigmatic disease. Recent developments in assisted reproductive technology have contributed to a better understanding of where and how endometriosis could compromise fertility. In this mini-review we will show how the main point of damage in endometriosis is quantitative impairment of the ovaries, if the "less is more" mantra should be applied when considering ovarian surgery, and when fertility preservation prior to ovarian surgery could be considered. Endometrial receptivity, however, does not seem to be affected.

Endometriosis Lowers the Cumulative Live Birth Rates in IVF by Decreasing the Number of Embryos but Not Their Quality

Endometriosis and infertility are closely linked, but the underlying mechanisms are still poorly understood. This study aimed to evaluate the impact of endometriosis on in vitro fertilization (IVF) parameters, especially on embryo quality and IVF outcomes. A total of 1124 cycles with intracytoplasmic sperm injection were retrospectively evaluated, including 155 cycles with endometriosis and 969 cycles without endometriosis. Women with endometriosis had significantly lower ovarian reserve markers (AMH and AFC), regardless of previous ovarian surgery. Despite receiving significantly higher doses of exogenous gonadotropins, they had significantly fewer oocytes, mature oocytes, embryos, and top-quality embryos than women in the control group. Multivariate analysis did not reveal any association between endometriosis and the proportion of top-quality embryo (OR = 0.87; 95% CI [0.66-1.12]; p = 0.3). The implantation rate and the live birth rate per cycle were comparable between the two groups (p = 0.05), but the cumulative live births rate was significantly lower in in the endometriosis group (32.1% versus 50.7%, p = 0.001), as a consequence of the lower number of frozen embryos. In conclusion, endometriosis lowers the cumulative live birth rates by decreasing the number of embryos available to transfer, but not their quality.

Elevated peritoneal fluid ceramides in human endometriosis-associated infertility and their effects on mouse oocyte maturation

OBJECTIVE

To characterize the peritoneal fluid (PF) sphingolipid profile in endometriosis-associated infertility (EAI), and to assess the plausible functional role(s) of ceramides in oocyte maturation potential.

DESIGN

Retrospective case-control study and in vitro mouse oocyte study.

SETTING

University-affiliated hospital and university laboratory.

SUBJECTS

Twenty-seven infertile patients diagnosed with endometriosis and 20 infertile patients who did not have endometriosis; BALB/c female mice.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

PF sphingolipid concentrations. Number of metaphase II (MII) mouse oocytes.

RESULT(S)

Liquid chromatography-tandem mass spectrometry revealed 11 significantly elevated PF sphingolipids in infertile women with severe endometriosis compared with infertile women without endometriosis (change >50%, false discovery rate ≤10%). Logistic regression analysis identified three very-long-chain ceramides potentially associated with EAI. Functional studies revealed that very-long-chain ceramides may compromise or induce murine MII oocyte maturation. The oocyte maturation effects induced by the very long-chain ceramides were triggered by alterations in mitochondrial superoxide production in a concentration-dependent manner. Scavenging of mitochondrial superoxide reversed the maturation effects of C_24:0 ceramide.

CONCLUSION(S)

EAI is associated with accumulation of PF very-long-chain ceramides. Mouse studies demonstrated how ceramides affect MII oocyte maturation, mediating through mitochondrial superoxide. These results provide an opportunity for direct functional readout of pathophysiology in EAI, and future therapies targeted at this sphingolipid metabolism may be harnessed for improved oocyte maturation.

Detrimental effects of endometriosis on oocyte morphology in intracytoplasmic sperm injection cycles: a retrospective cohort study

While an association can be addressed among endometriosis and subfertility, the causal relationship has not been elucidated yet. Impaired oocyte quality in endometriosis patients has been accused for the unsuccessful outcomes of assisted reproductive techniques. There are limited studies in literature evaluated association between endometriosis and oocyte morphology. We conducted this retrospective study to evaluate whether morphological abnormalities of oocytes are more common in women with endometriosis than women with diagnosis of male factor infertility as a source of healthy oocytes. Totally 1568 oocytes, 775 (49.4%) in endometriosis groups and 793 (50.6%) in control group were evaluated for morphological parameters before ICSI cycles. Abnormal oocyte morphology was detected in 352 (22.4%) of 1568 oocytes. Of the abnormal oocytes, 208 (59.1%) were in endometriosis group and 144 (40.9%) in control group (p < .001). The following dysmorphisms were significantly higher in oocytes retrieved from endometriosis group: dark cytoplasm; dark, large or thin zona pellucida; and flat or fragmented polar body (p <  .05 for all). When morphological parameters for oocytes of endometriosis patients evaluated, the oocyte defects has increased significantly in endometriosis patients. These findings are thought to be useful to clarify the subfertility in endometriosis patient, which needs to be confirmed with further studies.

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.

Pregnancy outcomes after controlled ovarian hyperstimulation in women with endometriosis-associated infertility: GnRH-agonist versus GnRH-antagonist

BACKGROUND OR OBJECTIVE

Endometriosis is common in women referred for infertility. In vitro fertilization provides good results but the choice of the best-controlled ovarian hyperstimulation protocol remains a subject of debate. The objective of this retrospective study was to compare pregnancy outcomes in women with endometriosis-associated infertility after COH with a long agonist protocol or a six-week oral contraception-antagonist protocol.

MATERIAL AND METHODS

Retrospective analysis of a prospective database identified 284 COH cycles - 165 with GnRH-agonist protocol (GnRH-agonist group) and 119 with GnRH-antagonist protocol (GnRH-antagonist group) - in 218 women, with endometriosis from January 2013 to October 2015.

RESULTS

No difference in the epidemiological characteristics was found between the groups. Per started cycle, pregnancy and live-birth rates after fresh embryo transfer were higher with the GnRH-agonist protocol (25% vs. 13%, P=0.02 and 18% vs. 8%, P=0.04, respectively). Considering analysis per cycle with embryo transfer, the pregnancy rate was similar in both groups while the live-birth rate was higher in the GnRH-agonist group (29% vs. 17%, P=0.053 and 22% vs. 10%, P=0.02, respectively). No difference was observed between the groups with freeze-thaw embryo transfer. Subgroup analysis (endometrioma alone, deep infiltrating endometriosis with and without endometrioma, endometriosis with and without adenomyosis) revealed no difference between the groups for either pregnancy or live-birth rates.

CONCLUSION

A GnRH-agonist protocol appears to result in higher pregnancy and live-birth rates after fresh embryo transfer in women with endometriosis-associated infertility, suggesting that a GnRH-antagonist protocol might negatively impact endometrial receptivity.

The Role of Oocyte Organelles in Determining Developmental Competence

The ability of an oocyte to undergo successful cytoplasmic and nuclear maturation, fertilization and embryo development is referred to as the oocyte’s quality or developmental competence. Quality is dependent on the accumulation of organelles, metabolites and maternal RNAs during the growth and maturation of the oocyte. Various models of good and poor oocyte quality have been used to understand the essential contributors to developmental success. This review covers the current knowledge of how oocyte organelle quantity, distribution and morphology differ between good and poor quality oocytes. The models of oocyte quality are also described and their usefulness for studying the intrinsic quality of an oocyte discussed. Understanding the key critical features of cytoplasmic organelles and metabolites driving oocyte quality will lead to methods for identifying high quality oocytes and improving oocyte competence, both in vitro and in vivo.

Relevant human tissue resources and laboratory models for use in endometriosis research

Endometriosis is characterized by the growth of endometrium‐like tissue outside the uterus, most commonly on the pelvic peritoneum and ovaries. Although it may be asymptomatic in some women, in others it can cause debilitating pain, infertility or other symptoms including fatigue. Current research is directed both at understanding the complex etiology and pathophysiology of the disorder and at the development of new nonsurgical approaches to therapy that lack the unwanted side effects of current medical management. Tools for endometriosis research fall into two broad categories; patient‐derived tissues, and fluids (and cells isolated from these sources) or models based on the use of cells or animals. In this review, we discuss the literature that has reported data from the use of these tools in endometriosis research and we highlight the strengths and weaknesses of each. Although many different models are reported in the literature, hypothesis‐driven research will only be facilitated with careful experimental design and selection of the most appropriate human tissue from patients with and without endometriosis and combinations of physiologically relevant in vitro and in vivo laboratory models.

[Deep infiltrative endometriosis without digestive involvement, what is the impact of surgery on in vitro fertilization outcomes? A retrospective study]

OBJECTIVES

To evaluate the impact of complete removal of endometriosis in case of deep infiltrative endometriosis without digestive involvement, on in vitro fertilization outcomes.

METHODS

Retrospective monocentric study. We included infertile women with deep infiltrative endometriosis without colorectal involvement that underwent IVF. Women were divided in two groups, following their history: "surgery" when they underwent complete endometriosis resection before IVF and "without surgery" when they underwent IVF without endometriosis removal. We analysed IVF outcomes considering pregnancy rates per cycle and cumulative pregnancy rates per patient.

RESULTS

We included 72 patients: 35 in the "surgery" group and 37 in the "without surgery" group. Women in the two groups were comparable in terms of baseline characteristics (age, body mass index, anti-Müllerian hormone, antral follicular count), endometriosis localizations and in vitro fertilization parameters. Cumulative pregnancy rates per patient were similar in both groups (40 % in the "surgery" group and 41 % in the "without surgery" group; P=1). Clinical pregnancy rate per cycle were also comparable groups (24 % in the "surgery" group and 28 % in the "without surgery" group; P=0.67). Surgery performed was comparable in women that became pregnant and in women that did not. Age was lower in women that became pregnant (P=0.01) and there were more pregnancy obtained in women under 35 years.

CONCLUSION

In women with deep infiltrative endometriosis without digestive involvement, in vitro fertilization outcomes were not impacted by surgery. Therapeutic choice between IVF or surgery as first-line treatment remains thus questionable and shall be guided by other influencing factors, such as pain symptomatology, age, tubal permeability, ovarian reserve, partner's sperm characteristics and woman's choice.

Dienogest treatment after ovarian endometrioma removal in infertile women prior to IVF

BACKGROUND

Severe forms of genital endometriosis are known to be associated with infertility and its subsequent treatment failure. Both gonadotropin-releasing hormone analogs (a-GnRH) and dienogest have been suggested as additional hormone therapy for patients with endometriomas. However, the result of hormonal suppression before an in vitro fertilization (IVF) cycle remains undetermined.

MATERIALS AND METHODS

A prospective cohort study of 144 infertile women planning IVF after laparoscopic surgery of ovarian endometriomas was conducted at our department in 2012-2015. Patients were divided into three groups: group I (N = 38) with dienogest course, group II (N = 70) with a-GnRH group III (N = 70) without any hormonal therapy within 6 months preceding IVF.

RESULTS

The study groups did not differ by removed endometriomas size and ovarian reserve indicators. The gonadotropin dose per Cycle was higher, while the number of retrieved oocytes was lower in group III patients (p < .001). In women with dienogest pretreatment, clinical pregnancy rate was 2.5 times (44.7% versus 16.7%, p = .012) and delivery rate - three times higher (36.8% versus 11.1%, p = .013) as compared with those from group III.

CONCLUSIONS

The present study confirms the necessity of pre-cycle medical interventions in women with ovarian forms of endometriosis undergoing IVF. We suggest dienogest to be possibly more efficient treatment option for this kind of patients.

Oocyte competence in in vitro fertilization and intracytoplasmic sperm injection patients suffering from endometriosis and its possible association with subsequent treatment outcome: a matched case-control study

INTRODUCTION

Endometriosis affects up to 15% of women of reproductive age. There is an obvious lack of studies dealing with morphological parameters of oocyte morphology in endometriosis patients in assisted reproduction. One aim of the study is to describe oocyte morphology in patients undergoing intracytoplasmic sperm injection suffering from endometriosis. In addition, the impact of endometriosis on in vitro fertilization results is analyzed. Both in vitro fertilization and intracytoplasmic sperm injection patients are then matched with an endometriosis-free control group for highlighting the possible association of endometriosis with pregnancy outcome.

MATERIAL AND METHODS

Oocyte morphology of endometriosis patients was assessed in two groups. Both study group and control group consisted of 129 in vitro fertilization/intracytoplasmic sperm injection cycles each. Patients were matched according to anti-Müllerian hormone, female age, previous treatment cycles, and method of fertilization. Endometriosis was graded according to the revised American Society for Reproductive Medicine guidelines of 1997.

RESULTS

Patients with endometriosis had a significantly lower rate of mature oocytes (p < 0.03) and morphologically normal oocytes (p < 0.001). In particular, brownish oocytes (p < 0.009; stage I-IV) and the presence of refractile bodies (p < 0.001; stage IV) were found to be increased. Endometriosis stage IV was associated with significantly worse-quality oocytes than stages I-III (p < 0.01). Fertilization was significantly reduced in conventional in vitro fertilization but not in intracytoplasmic sperm injection (p < 0.03). This was due to lower fertilization rates in stage III-IV endometriosis compared with stage I-II (p < 0.04). No difference was observed with respect to rates of implantation, clinical pregnancy, miscarriage, live birth, and malformation.

CONCLUSIONS

Endometriosis patients, in particular those with severe endometriosis, present lower-quality oocytes. Once fertilized, no impairment of further preimplantation embryo development and pregnancy outcome right up to healthy live birth rate has to be expected.

Modern Management of Endometrioma-Associated Infertility: in Favor of ART

Introduction

Endometrioma is present in 17% to 40% of women with endometriosis. Since it has been traditionally believed that the presence of an endometrioma adversely affects the outcome of assisted reproductive technology (ART), surgery has been suggested by many practitioners before advancing to ART, in the hope of improving results.

Scientific Evidence

In the present article, we outline the impact of an endometrioma on the ovarian reserve and describe how surgical resection of an endometriotic cyst affects ovarian reserve, ovarian response after stimulation and ART outcome. Several studies suggest that the sole presence of an endometrioma may have a negative impact on ovarian reserve of the affected ovary, and surgery (particularly cystectomy) has been the choice of treatment in ovarian endometriosis for many years. However, detrimental effects of laparoscopic surgical removal on ovarian reserve and responsiveness to hyperstimulation has made that ART practices are shifting towards a more conservative approach: experimental and clinical data supporting this shift are thoroughly reviewed here.

Clinical Implications

Opposed to the conventional criteria of performing cystectomy when ovarian endometrioma is observed, careful consideration of patient symptoms as well as her age and ovarian reserve will help to select the patients that require surgery prior to ART, whereas the majority will not need surgery prior to ART; even more, surgery may compromise ovarian reserve in most cases even if performed by careful surgeons.

Conclusions

Individualization of the treatment is imperative. Each case should be thoroughly assessed, looking at both the advantages and complications of cyst removal prior to ART. Surgery should be approached with caution in women with endometriomas, especially if the woman has had previous ovarian surgery. In the presence of infertility, we recommend generally sparing surgical treatment and proceeding directly to ART. This reduces the time to achieve a pregnancy, avoids potential surgical risks and limits patient costs.

The Impact of Myeloperoxidase and Activated Macrophages on Metaphase II Mouse Oocyte Quality

Myeloperoxidase (MPO), an abundant heme-containing enzyme present in neutrophils, monocytes, and macrophages, is produced in high levels during inflammation, and associated with poor reproductive outcomes. MPO is known to generate hypochlorous acid (HOCl), a damaging reactive oxygen species (ROS) utilizing hydrogen peroxide (H₂O₂) and chloride (Cl^-). Here we investigate the effect of activated immune cells and MPO on oocyte quality. Mouse metaphase II oocytes were divided into the following groups: 1) Incubation with a catalytic amount of MPO (40 nM) for different incubation periods in the presence of 100 mM Cl^- with and without H₂O₂ and with and without melatonin (100 μM), at 37°C (n = 648/648 total number of oocytes in each group for oocytes with and without cumulus cells); 2) Co-cultured with activated mouse peritoneal macrophage and neutrophils cells (1.0 x 10⁶ cells/ml) in the absence and presence of melatonin (200 μM), an MPO inhibitor/ROS scavenger, for different incubation periods in HTF media, at 37°C (n = 200/200); 3) Untreated oocytes incubated for 4 hrs as controls (n = 73/64). Oocytes were then fixed, stained and scored based on the microtubule morphology and chromosomal alignment. All treatments were found to negatively affect oocyte quality in a time dependent fashion as compared to controls. In all cases the presence of cumulus cells offered no protection; however significant protection was offered by melatonin. Similar results were obtained with oocytes treated with neutrophils. This work provides a direct link between MPO and decreased oocyte quality. Therefore, strategies to decrease MPO mediated inflammation may influence reproductive outcomes.