Attenuated oocyte fertilization and embryo development associated with altered growth factor/signal transduction induced by endometriotic peritoneal fluid

[Research Progress in the Role of Mitochondrial Dysfunction in Endometriosis-Associated Infertility]

Endometriosis (EMT), a common benign gynecological disease, is a leading cause of infertility in women. EMT affects female fertility in various aspects. However, the underlying mechanisms have not been fully elucidated. Mitochondria are known as the "powerhouse" of a cell. They play pivotal roles in the physiological processes of cellular energy metabolism, calcium homeostasis, oxidative stress, autophagy, the regulation of cell cycle, and cell death, and are involved in the pathophysiology of many diseases. Cellular mitochondria are highly dynamic, continuously undergoing cyclic fission and fusion to meet the demands of cellular activities. Balanced mitochondrial dynamics are critical for maintaining normal reproductive function in women. In addition, mitochondria are the major source of reactive oxygen species (ROS). Cell damage, cell death, and fibrosis mediated by the imbalance in the oxidative-antioxidant system in EMT patients lead to decreased oocyte quality and ovarian reserve. Currently, the treatment of EMT-associated infertility remains a challenging and controversial topic. We herein reviewed the latest findings on the role of mitochondrial dysfunction in EMT-associated infertility and the potential therapeutic targets.

Ovarian reserve markers of women with superficial endometriosis

OBJECTIVE

Endometriosis affects up to 10% of reproductive age women and is associated with pelvic pain and subfertility. While previous studies have shown an association between deep and ovarian endometriosis to reduced ovarian reserve, there is no data on the effect of superficial endometriosis on ovarian reserve markers. Hence, we aimed to compare ovarian reserve markers of women with superficial endometriosis to that of women without endometriosis.

METHODS

This was a case control study in a tertiary medical center. The study group included women aged 18-40 with surgically and histopathology-proven superficial endometriosis with no deep lesions or ovarian involvement. The control group included women with no known or suspected endometriosis and was matched to the study group by age, BMI and parity. We excluded women with other known risk factors for ovarian failure and with other gynecological disorders. Participants completed a questionnaire with demographic, medical and gynecological data. Each patient underwent anti-Mullerian hormone (AMH) testing and an ultrasound to assess their antral follicular count (AFC). AMH and AFC were then compared between groups.

RESULTS

A total of 124 women participated in the study. Of these, 50% (n = 62) had surgically proven superficial endometriosis and 50% (n = 62) were without known or suspected endometriosis. Mean AMH levels of women with and without superficial endometriosis was 3.0 ± 2.8 ng/mL and 2.8 ± 1.9 ng/mL, respectively (P = 0.71). AFC also did not differ between groups (women with superficial endometriosis: 12.0 ± 6.6; women without endometriosis: 10.2 ± 5.0, P = 0.15).

CONCLUSIONS

In our cohort, superficial endometriosis was not associated with diminished ovarian reserve. While further studies are needed, to date, it does not appear to be justified to assess ovarian reserve for patients with superficial 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.

Oviductal extracellular vesicles from women with endometriosis impair embryo development

Objective

To investigate the influence of oviductal extracellular vesicles from patients with endometriosis on early embryo development.

Design

In vitro experimental study.

Setting

University-affiliated hospital.

Patients

Women with and without endometriosis who underwent hysterectomy (n = 27 in total).

Interventions

None.

Main outcome measures

Oviductal extracellular vesicles from patients with endometriosis (oEV-EMT) or without endometriosis (oEV-ctrl) were isolated and co-cultured with two-cell murine embryos for 75 hours. Blastocyst rates were recorded. RNA sequencing was used to identify the differentially expressed genes in blastocysts cultured either with oEV-EMT or with oEV-ctrl. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed to identify potential biological processes in embryos that oEV-EMT affects. The functions of oEV on early embryo development were determined by reactive oxygen species (ROS) levels, mitochondrial membrane potentials (MMP), total cell numbers, and apoptotic cell proportions.

Results

Extracellular vesicles were successfully isolated from human Fallopian tubal fluid, and their characterizations were described. The blastocyst rates were significantly decreased in the oEV-EMT group. RNA sequencing revealed that oxidative phosphorylation was down-regulated in blastocysts cultured with oEV-EMT. Analysis of oxidative stress and apoptosis at the blastocysts stage showed that embryos cultured with oEV-EMT had increased ROS levels, decreased MMP, and increased apoptotic index. Total cell numbers were not influenced.

Conclusion

Oviductal extracellular vesicles from patients with endometriosis negatively influence early embryo development by down-regulating oxidative phosphorylation.

Identification and Analysis of Potential Immune-Related Biomarkers in Endometriosis

Background

Endometriosis is an inflammatory gynecological disease leading to deep pelvic pain, dyspareunia, and infertility. The pathophysiology of endometriosis is complex and depends on a variety of biological processes and pathways. Therefore, there is an urgent need to identify reliable biomarkers for early detection and accurate diagnosis to predict clinical outcomes and aid in the early intervention of endometriosis. We screened transcription factor- (TF-) immune-related gene (IRG) regulatory networks as potential biomarkers to reveal new molecular subgroups for the early diagnosis of endometriosis.

Methods

To explore potential therapeutic targets for endometriosis, the Gene Expression Omnibus (GEO), Immunology Database and Analysis Portal (ImmPort), and TF databases were used to obtain data related to the recognition of differentially expressed genes (DEGs), differentially expressed IRGs (DEIRGs), and differentially expressed TFs (DETFs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the DETFs and DEIRGs. Then, DETFs and DEIRGs were further validated in the external datasets of GSE51981 and GSE1230103. Then, we used quantitative real-time polymerase chain reaction (qRT-PCR) to verify the hub genes. Simultaneously, the Pearson correlation analysis and protein-protein interaction (PPI) analyses were used to indicate the potential mechanisms of TF-IRGs at the molecular level and obtain hub IRGs. Finally, the receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic value of the hub IRGs.

Results

We screened a total of 94 DETFs and 121 DEIRGs in endometriosis. Most downregulated DETFs showed decreased expression in the endometria of moderate/severe endometriosis patients. The top-ranked upregulated DEIRGs were upregulated in the endometra of infertile women. Functional analysis showed that DETFs and DEIRGs may be involved in the biological behaviors and pathways of endometriosis. The TF-IRG PPI network was successfully constructed. Compared with the control group, high C3, VCAM1, ITGB2, and C3AR1 expression had statistical significance in endometriosis among the hub DEIRGs. They also showed higher sensitivity and specificity by ROC analysis for the diagnosis of endometriosis. Finally, compared with controls, C3 and VCAM1 were highly expressed in endometriosis tissue samples. In addition, they also showed high specificity and sensitivity for diagnosing endometriosis.

Conclusion

Overall, we discovered the TF-IRG regulatory network and analyzed 4 hub IRGs that were closely related to endometriosis, which contributes to the diagnosis of endometriosis. Additionally, we verified that DETFs or DEIRGs were associated with the clinicopathological features of endometriosis, and external datasets also confirmed the hub IRGs. Finally, C3 and VCAM1 were highly expressed in endometriosis tissue samples compared with controls and may be potential biomarkers of endometriosis, which are helpful for the early diagnosis of endometriosis.

Endometriosis and Infertility: A Long-Life Approach to Preserve Reproductive Integrity

Laparoscopic surgery was originally considered the gold standard in the treatment of endometriosis-related infertility. Assisted reproductive technology (ART) was indicated as second-line treatment or in the case of male factor. The combined approach of surgery followed by ART proved to offer higher chances of pregnancy in infertile women with endometriosis. However, it was highlighted how pelvic surgery for endometriosis, especially in cases of ovarian endometriomas, could cause iatrogenic damage due to ovarian reserve loss, adhesion formation (scarring), and ischemic damage. Furthermore, in the last few years, the trend to delay the first childbirth, recent technological advances in ultrasound diagnosis, and technological progress in clinical and laboratory aspects of ART have certainly influenced the approach to infertility and endometriosis with, ART assuming a more relevant role. Management of endometriosis should take into account that the disease is chronic and involves the reproductive system. Consequently, treatment and counselling should aim to preserve the chances of pregnancy for the patient, even if it is not associated with infertility. This review will analyse the evolution of the management of infertility associated with endometriosis and propose an algorithm for treatment decision-making based on the most recent acquisitions.

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.

Proteomic analysis of peritoneal fluid identified COMP and TGFBI as new candidate biomarkers for endometriosis

Endometriosis is a common non-malignant gynecological disease that significantly compromises fertility and quality of life of the majority of patients. The gold standard for diagnosis is visual inspection of the pelvic organs by surgical laparoscopy and there are no biomarkers that would allow non-invasive diagnosis. The pathogenesis of endometriosis is not completely understood, thus analysis of peritoneal fluid might contribute in this respect. Our prospective case-control study included 58 patients undergoing laparoscopy due to infertility, 32 patients with peritoneal endometriosis (cases) and 26 patients with unexplained primary infertility (controls). Discovery proteomics using antibody microarrays that covered 1360 proteins identified 16 proteins with different levels in cases versus the control patients. The validation using an ELISA approach confirmed significant differences in the levels of cartilage oligomeric matrix protein (COMP) and transforming growth factor-β-induced protein ig-h3 (TGFBI) and nonsignificant differences in angiotensinogen (AGT). A classification model based on a linear support vector machine revealed AUC of > 0.83, sensitivity of 0.81 and specificity of 1.00. Differentially expressed proteins represent candidates for diagnostic and prognostic biomarkers or drug targets. Our findings have brought new knowledge that will be helpful in the understanding of the pathophysiology of endometriosis and warrant further studies in blood samples.

Iron overload compromises preimplantation mouse embryo development

We and others have previously shown that abnormal pelvic environment plays an important role in the unexplained infertility of endometriosis. However, whether iron overload caused by ectopic periodic bleeding found in patients with endometriosis participates in endometriosis-associated reproductive failure is unknown. This study aimed to investigate effects of iron at level relevant to pelvic iron overload on the development of preimplantation mouse embryo. Two-cell embryos were collected, and cultured to blastocysts in G1/G2 medium supplemented with iron alone or in combination with iron chelator. The development rates, ATP level, mitochondrial membrane potential (MMP), reactive oxygen species level (ROS), and apoptotic and ferroptotic indices were compared between control and iron treatments across each specific developmental stage. Prolonged exposure to iron remarkably impaired early embryo development in vitro by hampering blastocyst formation (P < 0.001), which could be partly restored by iron chelator (P < 0.001). The arrest of embryo development was linked with iron-initiated mitochondrial dysfunction with reduction of ATP generation and MMP (P < 0.05 and P < 0.001, respectively). Impaired mitochondria altered ROS accumulation post-iron exposure at morula stage and blastocyst stage (P < 0.05). Moreover, Iron-exposed blastocyst stage embryos showed higher apoptotic and ferroptotic rates (P < 0.001 and P < 0.05, respectively). Our results highlight that pathologically relevant level of iron compromises preimplantation mouse embryo development by disrupting mitochondrial function and triggering both apoptosis and ferroptosis, which implicates that excess iron found in peritoneal fluid of women with endometriosis likely participates in endometriosis-associated reproductive failure.

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.

Are women with small endometriomas who undergo intracytoplasmic sperm injection at an elevated risk for adverse pregnancy, obstetric, and neonatal outcomes?

Objective

The aim of the study was to investigate pregnancy, obstetric, and neonatal outcomes in women with small (<4 cm) unilateral endometriomas.

Methods

This retrospective study included 177 patients: 91 patients with small endometriomas and 86 controls with unexplained or tubal factor infertility who were treated at the Süleymaniye Gynecology and Maternity Training and Research Hospital Infertility Unit between January 2010 and July 2015. The groups were matched with regards to demographic characteristics such as age, body mass index, and infertility duration. All of the women in this study conceived via intracytoplasmic sperm injection. We compared pregnancy, obstetric, and neonatal outcomes between these groups.

Results

Women with endometriomas had a higher biochemical pregnancy rate, but lower clinical pregnancy and live birth rates than women with unexplained and tubal factor infertility (p<0.05 for all). However no significant differences were found in terms of obstetric and neonatal complications between the two groups (p>0.05 for all).

Conclusion

In this study, we found that women with endometriomas less than 4 cm were more prone to early pregnancy complications. We also showed that this group did not have any increased risks of late pregnancy, obstetric, and neonatal complications.

Hysteroscopy and female infertility: a fresh look to a busy corner

Hysteroscopy has evolved from the traditional art of examining the uterine cavity for diagnostic purposes to an invaluable modality to concomitantly diagnose and (see and) treat a multitude of intrauterine pathologies, especially in the field and clinics specialising in female reproduction. This article reviews the literature on the most common cervical, endometrial, uterine and tubal pathologies such as chronic endometritis, endometrial polyps, adenomyosis, endometriosis, endometrial atrophy, adhesions, endometrial hyperplasia, cancer, and uterine malformations. The aim is to determine the efficiency of hysteroscopy compared with other available techniques as a diagnostic and treatment tool and its association with the success of in vitro fertilisation procedures. Although hysteroscopy requires an experienced operator for optimal results and is still an invasive procedure, it has the unique advantage of combining great diagnostic and treatment opportunities before and after ART procedures. In conclusion, hysteroscopy should be recommended as a first-line procedure in all cases with female infertility, and a special effort should be made for its implementation in the development of new high-tech procedures for identification and treatment infertility-associated conditions.

Transferrin and antioxidants partly prevented mouse oocyte oxidative damage induced by exposure of cumulus-oocyte complexes to endometrioma fluid

Background

Exposure of oocytes to the endometrioma fluid has an adverse effect on embryonic quality. To determine whether adding transferrin and antioxidants to culture medium could counteract detrimental effects on mouse cumulus-oocyte complexes (COCs) induced by exposure to endometrioma fluid or not, we conducted an in vitro cross-sectional study using human and mouse COCs.

Methods

Eighteen women who had their oocytes exposed to endometrioma fluid during oocyte retrieval were enrolled. COCs from superovulated ICR female mice were collected. They were first exposed to human endometrioma fluid and then treated by transferrin and/or antioxidants (cysteamine + cystine). Subsequently, COCs function was assessed by molecular methods.

Results

This study observed that human COCs inadvertently exposed to endometrioma fluid in the in vitro fertilization (IVF) group led to a lower good quality embryo rate compared to intracytoplasmic sperm injection (ICSI) group. Exposure of mouse COCs to endometrioma fluid accelerated oocyte oxidative damage, evidenced by significantly reduced CCs viability, defective mitochondrial function, decreased GSH content and increased ROS level, associated with the significantly higher pro-portion of abnormal spindles and lower blastocyst formation (p < 0.05, respectively). This damage could be recovered partly by treating COCs with transferrin and antioxidants (cysteamine + cystine).

Conclusions

Transferrin and antioxidants could reduce the oxidative damage caused by COCs exposure to endometrioma fluid. This finding provides a promising new possibility for intervention in the human oocyte oxidative damage process induced by endometrioma fluid during oocyte pick-up.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-020-00738-0.

Expressed proteins and activated pathways in conditioned embryo culture media from IVF patients are diverse according to infertility factors

OBJECTIVE

Given that the embryo culture medium secretome reflects the embryo development, we hypothesize that protein profiles are affected according to infertility factors, which can be responsible for detrimental embryonic developmental competence. The aim of this study was to screen the protein profile of conditioned embryo culture media in patients presenting deep infiltrating endometriosis (ENDO) and polycystic ovarian syndrome (PCOS) undergoing IVF, by proteomics approaches. The control group was constituted by tubal factor patients.

METHODS

Patients underwent in vitro fertilization (IVF) treatment as routine and oocytes were fertilized by ICSI. The embryos were group cultured until day 3 of development, and after transfer the culture media were collected. For the proteomics analysis, two pools of samples were prepared for groups CONTROL and PCOS, and 4 pools of samples for group DIE. Samples were prepared to deplete high abundant proteins and followed evaluated by high throughput proteomics approach.

RESULTS

The embryonic organ and tissue development were physiological functions activated, based on proteins identified in the 3 study groups of samples. The samples coming from DIE patients presented a high calcium activity and on the other hand, embryos coming from PCOS patients showed a decreased calcium action. Other pathways as grow factors through the EGF signaling pathway overexpressed in ENDO culture medium and protein kinase A in PCOS were also observed.

CONCLUSIONS

Proteomic embryonic secretome will advance our knowledge of early embryogenesis and additionally could lead to improved selection of embryos for transfer warrants further investigation.

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.

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.

Dexamethasone attenuates the embryotoxic effect of endometriotic peritoneal fluid in a murine model

PURPOSE

The in vitro fertilization (IVF) pregnancy rate of women with advanced stage endometriosis is nearly half that of the general population, suggesting incomplete targeting of the pathophysiology underlying endometriosis-associated infertility. Compelling evidence highlights inflammation as the etiologic link between endometriosis and infertility and a potential target for adjunctive treatment. The objective of this study was to examine the effect of dexamethasone on murine embryos exposed to human endometriotic peritoneal fluid (PF) using the established murine embryo assay model.

METHODS

PF was obtained from women with and without severe endometriosis. Murine embryos were harvested and randomly allocated to five groups of culture media conditions: (1) human tubal fluid (HTF), (2) HTF and 10 % PF from women without endometriosis, (3) HTF and 10 % PF from women with endometriosis (PF-E), (4) HTF with PF-E and 0.01 mcg/mL dexamethasone, and (5) HTF with PF-E and 0.1 mcg/mL dexamethasone. Embryos were cultured in standard conditions and evaluated for blastocyst development.

RESULTS

A total of 266 mouse embryos were cultured. Baseline blastulation rates were 63.6 %. The addition of peritoneal fluid from women with endometriosis decreased the blastocyst development rate to 38.9 % (P = 0.008). The addition of 0.1 mcg/mL of dexamethasone to the culture media restored the blastulation rate to near baseline levels (61.2 %; P = 0.019).

CONCLUSIONS

The results of our in vitro study demonstrate the capacity of dexamethasone to mitigate the deleterious impact of endometriotic PF on embryo development. If confirmed in vivo, dexamethasone may prove a useful adjunct for the treatment of endometriosis-associated infertility.

Tubal transport of gametes and embryos: a review of physiology and pathophysiology

With the advent of assisted reproductive technology in the past three decades, the clinical importance of fallopian tubes has been relatively overlooked. However, successful spontaneous conception requires normal function of the tube to provide not only a conduit for the gametes to convene and embryo to reach the uterine cavity, but also a physiologically optimized environment for fertilization and early embryonic development. In this review, after a brief description of normal human tubal anatomy and histology, we will discuss tubal transport and its principal effectors, including ciliary motion, muscular contractility and tubal fluid. Furthermore, we will discuss the ciliary ultrastructure and regulation of ciliary beat frequency by ovarian steroids, follicular fluid, angiotensin system, autonomic nervous system and other factors such as adrenomedullin and prostaglandins. In the last section, we describe the adverse impact of various pathological conditions, such as endometriosis, infection and smoking on tubal function and ciliary motility.

The effect of peritoneal fluid from patients with endometriosis on mitochondrial function and development of early mouse embryos

Background

Peritoneal fluid (PF) from patients with endometriosis can inhibit early embryo development via probable functional changes of embryo mitochondria in the early stage of embryo development. The purpose of this study was to determine the effect of PF from patients with endometriosis on mitochondrial function and development of early mouse embryos.

Methodology/Principal Findings

PF was collected from patients with infertility and endometriosis, infertility due to tubal factors, and normal control subjects, and the level of NO was measured. Early murine embryos were then cultured with PF from normal control subjects, those with endometriosis, and with human tubal fluid (HTF), respectively. Cleavage and blastulation rates, mitochondrial DNA (mtDNA) copy numbers, adenosine triphosphate (ATP) level, and mitochondrial membrane potential (ΔΨm) of the different groups were compared. The NO level in the PF of patients with endometriosis was significantly greater than in those without endometriosis and control patients. The embryos cultures with PF from patients with endometriosis had a lower cleavage rate and blastulation rate, and higher ATP and ΔΨm level at the 2- and 4-cell stages. No significant difference was found in mtDNA copies among the 3 groups.

Conclusions/Significance

PF from patients with endometriosis can inhibit early embryo development via probable functional changes of embryo mitochondria in the early stage of embryo development. Understanding the effects of PF on embryo development may assist in developing new methods of treatment for infertility.

Cellular and molecular basis for endometriosis-associated infertility

Endometriosis is a gynecological disease characterized by the presence of endometrial glandular epithelial and stromal cells growing in the extra-uterine environment. The disease afflicts 10%–15% of menstruating women causing debilitating pain and infertility. Endometriosis appears to affect every part of a woman’s reproductive system including ovarian function, oocyte quality, embryo development and implantation, uterine function and the endocrine system choreographing the reproductive process and results in infertility or spontaneous pregnancy loss. Current treatments are laden with menopausal-like side effects and many cause cessation or chemical alteration of the reproductive cycle, neither of which is conducive to achieving a pregnancy. However, despite the prevalence, physical and psychological tolls and health care costs, a cure for endometriosis has not yet been found. We hypothesize that endometriosis causes infertility via multifaceted mechanisms that are intricately interwoven thereby contributing to our lack of understanding of this disease process. Identifying and understanding the cellular and molecular mechanisms responsible for endometriosis-associated infertility might help unravel the confounding multiplicities of infertility and provide insights into novel therapeutic approaches and potentially curative treatments for endometriosis.

Inflammation, NK cells and implantation: friend and foe (the good, the bad and the ugly?): replacing placental viviparity in an evolutionary perspective

This review summarises an invited talk presented at the 2012 ESRI/ASRI meeting in Hamburg, concerning current views of inflammation in pregnancy, which is timely given that the effects of a local injury in the uterus acts to favour implantation. Recalling that inflammation can be good (it is useful and necessary for implantation), bad (in implantation failure, RSA) and ugly (at the extreme, endometriosis is associated with pain and infertility) leads to consideration of its status in pregnancy. Its role in implantation and the fact that pregnancy maintains some aspects of inflammation throughout, leads to revision of not only concepts of immunosuppression and the Th1/Th2 paradigm, but also the feto-maternal relationship as seen since Medawar's hypotheses were advanced. This is examined from an evolutionary perspective, which should lead to further review of our perception of uterine NK cells, and the emergence of Treg cells to control some aspects of adaptive immunity, which appeared long after placentation.

Conventional IVF versus ICSI in sibling oocytes from couples with endometriosis and normozoospermic semen

PURPOSE

This study compares the fertilization rate and embryonic development of oocytes randomly inseminated by conventional IVF or ICSI in patients with endometriosis and normozoospermic semen during IVF cycles.

METHODS

Sibling oocytes were randomized to be inseminated either by ICSI or IVF. Rates of fertilization, cleavage, blastulation and embryonic morphology were assessed.

RESULTS

A total of 786 sibling cumulus-oocyte complexes (COC) were randomized between insemination by conventional IVF (387 COC) or ICSI (399 COC). A significantly higher fertilization rate was found in the ICSI group (ICSI versus IVF, 73.3±23 % versus 54.7±31.9 % respectively; P=0.003), yielding a higher mean number of day 2 embryos (5.2±3.4 versus 3.6±2.9 respectively; P=0.002). Triploid fertilization rate (3PN/COC) was significantly higher in the IVF group compared to the ICSI group (3.9±8.7 % versus 0.9±3.1 % respectively; P=0.02). The morphology score and rate of development of day 2 and 3 embryos were not different between the two groups. Comparison of embryo transfer cycles in which either IVF or ICSI only embryos were transferred did not reveal any statistically significant differences in pregnancy or implantation rates.

CONCLUSION

ICSI appears to be a better treatment option than conventional IVF in endometriosis-associated infertility, since it offers the advantages of higher fertilization rate and mean number of embryos and lower rate of total fertilization failure and triploid fertilization.

Impact of endometriosis on in vitro fertilization and embryo transfer cycles in young women: a stage-dependent interference

OBJECTIVE

Endometriosis is a frequent indication for in vitro fertilization and embryo transfer (IVF-ET). Its influence on IVF-ET cycles remains controversial. We evaluated the impact of the severity of endometriosis on IVF-ET cycles in young women.

DESIGN

Retrospective cohort study.

SETTING

Academic tertiary referral centre.

SAMPLE AND METHODS

In a retrospective cohort analysis, 164 IVF-ET cycles in 148 women with endometriosis-associated infertility were analyzed. Eighty cycles performed during the same period on 72 consecutive women with tubal infertility were considered as controls. All patients were younger than 35 years old.

MAIN OUTCOME MEASURES

Response to controlled ovarian hyperstimulation (COH), number of oocytes retrieved, fertilization, implantation and pregnancy rate (PR).

RESULTS

Clinical PR was lower in the group with endometriosis (all stages) in comparison with the tubal factor group. Higher total gonadotropin requirements, lower response to COH and lower oocyte yield were also found in the endometriosis group. Stage-stratified analysis showed a lower fertilization rate in stage I-II (52.6% stage I-II, 70.5% stage III-IV and 71.9% tubal factor). In stage III-IV endometriosis there was a higher cycle cancellation rate, a reduced response to COH and a lower PR compared with both the stage I-II and the tubal infertility groups (PR 9.7, 25 and 26.1%, respectively).

CONCLUSIONS

Stage III-IV was strongly associated with poor IVF outcome. A decreased fertilization rate in stage I-II might be a cause of subfertility in these women, owing to a hostile environment caused by the disease.

Ovarian surgery for bilateral endometriomas influences age at menopause

BACKGROUND

Questions remain as to whether surgical excision of ovarian endometriomas might cause damage to ovarian function. To test the hypothesis that ovarian surgery for endometrioma compromises ovarian function and accelerates ovarian failure.

METHODS

In a tertiary university Clinic, longitudinal prospective cohort study. Patients who underwent laparoscopy for endometriosis between March 1993 and November 2007 were assessed for inclusion in the study. A prospective follow-up at 3, 6 and 12 months then yearly was conducted. Evolution of menstrual pattern, symptoms and reproductive outcomes were investigated.

RESULTS

From over the 14-year period, 302 patients were included in the study. The mean age (±SD) of patients was 32.6 ± 5.6 years; the median duration of follow-up was 8.5 years (range 2-17 years). Menopause was documented in 43 women (14.3%) at a mean age of 45.3 ± 4.3 years (range 32-52 years). Women previously submitted to bilateral cystectomy were younger at menopause than those with monolateral endometrioma (42.1 ± 5.1 years versus 47.1 ± 3.5 years, P = 0.003). Premature ovarian failure (POF) was observed in 7 of 43 (16.3%) menopausal patients; the majority (4, 57.1%) after bilateral cystectomy. The relationship between the preoperative ovarian endometriomas total diameter and menopausal age was significant in case of surgery for bilateral endometriomas (R(2) = 0.754, P = 0.002).

CONCLUSIONS

Patients who had been operated on for bilateral endometriomas have an increased risk of POF. Ovarian parenchyma loss at the time of surgery seems related to cyst diameter. In the case of unilateral ovarian endometrioma, the contralateral intact ovary might adequately compensate.

Downregulative effects of nitric oxide on oocyte fertilization and embryo development: possible roles of nitric oxide in the pathogenesis of endometriosis-associated infertility

AIMS

To investigate the effects of elevated nitric oxide (NO) levels in peritoneal fluids (PF) on oocyte fertilization and pre-implantation embryo development, and the relation of those effects to endometriosis-associated infertility.

METHODS

PF from women undergoing laparoscopy for infertility of minor endometriosis, tubal blockage and operation for tubal ligation was aspired at the pouch of the cul-de-sac during surgery. Oocytes and embryos of adult ICR mice were cultured in vitro with or without endometriotic PF. The fertilization rate of oocyte and the cleavage rate of 2-cell embryos were examined. Also, the clinical indexes of IVF-ET of women with minor endometriosis and tubal infertility were analyzed.

RESULTS

Oocyte fertilization rate of endometriotic women with IVF-ET treatment was significantly lower than that of tubal block women. The dose-related adverse effects of endometriotic PF and SNP (NO donor) in culture medium on oocyte fertilization and embryos development were confirmed.

CONCLUSION

Increased NO levels in PF play an important role in mediating the effects of endometriotic PF on oocyte fertilization and embryo development. IVF might serve as an alternative treatment for endometriosis-associated infertility.