|Year : 2015 | Volume
| Issue : 3 | Page : 73-77
Endometriosis, oocytes, and in vitro fertilization
Gautam Nandkishore Allahbadia
Rotunda-The Center for Human Reproduction, Bandra, Mumbai, India
|Date of Web Publication||8-Dec-2015|
Gautam Nandkishore Allahbadia
Rotunda-The Center For Human Reproduction, 36 Turner Road, #101 1st Floor, B Wing, Bandra(West), Mumbai - 400 050
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Allahbadia GN. Endometriosis, oocytes, and in vitro fertilization. IVF Lite 2015;2:73-7
| Introduction|| |
Endometriosis, a pathological condition in which the endometrium grows outside the uterus, is one of the most common causes of female infertility; it is diagnosed in 25–40% of infertile women. The mechanism by which endometriosis affects the fertility of females remains largely unknown. In 2002, a meta-analysis was published by Barnhart et al. on the effect of endometriosis on in vitro fertilization (IVF). Twenty-two published studies were included in the overall analysis. The chance of achieving pregnancy was significantly lower for endometriosis patients (odds ratio, 0.56; 95% confidence interval [CI]: 0.44–0.70) when compared with tubal factor controls. Multivariate analysis also demonstrated a decrease in fertilization and implantation rates, and a significant decrease in the number of oocytes retrieved for endometriosis patients. Pregnancy rates for women with severe endometriosis were significantly lower than for women with mild disease (odds ratio, 0.60; 95% CI: 0.42–0.87). Patients with endometriosis-associated infertility undergoing IVF respond with significantly decreased levels of all markers of the reproductive process, resulting in a pregnancy rate that is almost one half that of the women with other indications for IVF. These data suggested that the effect of endometriosis is exclusive not only on the receptivity of the endometrium but also on the development of the oocyte and embryo. Endometriosis is suggested to represent an autoimmune disorder; but over the last 20 years, we still do not know sure whether the autoantibodies to antigens are relevant to reproduction. Almost a decade ago, the humoral immune response to the women with endometriosis (Stage I–II: 261 women; Stage III–IV: 62 women) in serum and in peritoneal fluid was investigated compared with 101 healthy women. Enzyme-linked immunosorbent assay (ELISA) was used in all the women for the detection of seven antiphospholipid antibodies (aPLs against cardiolipin, L-phosphatidyl [ph]-serine, ph-glycerol, ph-inositol, ph-ethanolamine, phosphatidic [ph]-acid; and against beta 2-glycoprotein I) of class IgG, IgA, and IgM. A passive hem-agglutination method and ELISA (BioGen) was used for assessment of antizona pellucida antibodies (aZP), tray agglutination test (TAT), and indirect mixed anti-imunoglobulin reaction test for the determination of sperm antibody levels. Endometriosis Stages I–II were associated with higher serum and peritoneal fluid levels of aPLs against inositol, cardiolipin, ethanolamine, and beta 2-glycoprotein I. Forty percent of patients were positive for aZPA. The researchers concluded that patients with lesions of endometriosis Stage I–II had more autoantibodies than those with Stage III–IV and may be immunologically more active. This result may be significant for future treatments such as IVF and embryo transfer.
The IVI Group from Valencia  first compared the IVF outcomes in women with tubal infertility and endometriosis. The results indicated that patients with endometriosis had a poorer IVF outcome in terms of reduced pregnancy rate per cycle per transfer, and reduced implantation rate per embryo replaced. They then evaluated embryo development in vitro in women with and without Endometriosis who underwent IVF and embryo replacement 72 h after oocyte retrieval. They observed that, compared to controls, patients with endometriosis had a significantly reduced number of blastomeres per embryo as well as an increased incidence of arrested embryos in vitro. In subsequent studies, they compared fertility parameters in patients receiving donor oocytes. They noted that, when donor oocytes came from patients without known endometriosis, embryo development and implantation rates were similar in patients with and without endometriosis. However, when the results of oocyte donation were classified according to the nature of the oocytes donated, patients who received embryos derived from oocytes from women with endometriotic ovaries showed a significantly reduced implantation rate compared to the controls. Taken together, these observations suggest that IVF in patients with endometriosis may be related to alterations within the oocyte, which in turn result in embryos of lower quality with a reduced ability to implant.,
| Discussion|| |
Endometriosis and infertility are known to be associated, but it is unclear whether endometriosis causes infertility. Lyons et al. used contrast analog enhancement to study the effect of peritoneal fluid from women with early stage endometriosis on the ciliary beat frequency of human fallopian tube epithelium. They obtained peritoneal fluid from six women with early stage endometriosis and from six fertile women with no evidence of endometriosis to use as controls. Fallopian tubes from hysterectomy specimens were collected from 17 women. The difference in ciliary beat frequency between fallopian tubes exposed to peritoneal fluids of women with and without endometriosis increased with the duration of incubation (mean difference at 24 h 1.35 Hz, 95% CI: 0.94–1.75, P = 0.01). At 24 h, ciliary beat frequency was significantly lower in the incubations with peritoneal fluid from women with endometriosis than controls (4.29 [0.15] vs. 5.64 Hz [0.15], respectively, P = 0.001). Impairment of ciliary action in women with endometriosis might reduce fertility.
Benaglia et al. set up a retrospective study to evaluate whether accidental contamination of follicular fluid (FF) with endometrioma content during oocytes retrieval affects IVF outcome. Cases were 19 women with ovarian endometriomas who had an accidental aspiration of the endometrioma content during oocyte retrieval. Controls (n = 38) were the two subsequent age-matched women with endometriomas who underwent an uncomplicated oocyte retrieval. The main outcome was to evaluate the clinical pregnancy (CP) rate in cases and controls. Accidental aspiration of endometrioma content occurred in 19 out of 314 women (6.1%, 95% CI: 3.8–9.1%). The number of embryos and top quality embryos was significantly higher in exposed women (3.1 ± 2.0 vs. 1.7 ± 1.2 and 1.9 ± 1.5 vs. 1.1 ± 1.1, respectively) but the chances of pregnancy were lower. They concluded that this situation may affect IVF outcome but does not justify systematic surgical removal before the cycle.
Cohen et al. assessed the impact of peritoneal endometriosis on oocyte and embryo quality in a mouse model. Peritoneal endometriosis was surgically induced in 33 B6CBA/F1 female mice (endometriosis group, n = 17) and sham-operated were used as control (sham group, n = 16). Mice were superovulated 4 weeks after surgery and mated or not, to collect E 0.5-embryos or metaphase II (MII)-oocytes. Evaluation of oocyte and zygote quality was done by immunofluorescence under spinning disk confocal microscopy. Endometriosis-like lesions were observed in all mice of endometriosis group. In both groups, a similar mean number of MII oocytes per mouse was observed in nonmated mice (30.2 vs. 32.6), with a lower proportion of normal oocytes in the endometriosis group (61 vs. 83%, P < 0.0001). Abnormalities were incomplete extrusion or division of the first polar body and spindle abnormalities. The mean number of zygotes per mouse was lower in the endometriosis group (21 vs. 35.5, P = 0.02) without difference in embryo quality. Their results support that induced peritoneal endometriosis in a mouse model is associated with a decrease in oocyte quality and embryo number.
The aim of a recent Korean study was to compare intrafollicular biomarkers of the thiol-redox system and chronic inflammation in infertile patients with and without endometriosis, and examine correlations between biomarkers and IVF outcomes. The study included 65 patients receiving IVF: 31 patients with endometriosis versus 34 patients without endometriosis. FF was obtained from a single-dominant follicle during oocyte retrieval and stored at −70°C. Malondialdehyde, superoxide dismutase, glutathione (GSH), glutathione peroxidase 3 (GPX3), thioredoxin (TRX), TRX-binding protein 2 (TBP2), and peroxiredoxin-4 levels were measured in the FF samples by ELISAs as biomarkers of oxidative stress (OS). The inflammatory cytokines interleukin 1 beta (IL1 β), IL6, IL8, and tumor-necrosis factor alpha (TNFα) were also measured by ELISAs. GSH levels were significantly lower in the endometriosis group compared with the controls. TBP2 levels were significantly higher in the endometriosis group. IL6, IL8, and TNFα levels were significantly higher in the endometriosis group. The levels of all of the inflammatory cytokines positively correlated with the levels of TRX. GSH levels positively correlated with the number of high-quality embryos. GPX3 and TRX levels negatively correlated with the percentage of mature oocytes. TNFα levels negatively correlated with the cumulative embryo score per embryo.
Logistic regression analysis revealed that the number of high-quality embryos was an independent factor predicting CP. The study concluded that there may be an imbalance in the thiol-redox system and increased levels of inflammatory cytokines in the intrafollicular microenvironment of infertile patients with endometriosis, which may affect the qualities of the oocyte and embryo.
Some studies have demonstrated alterations in the composition of FF from infertile women with endometriosis (X-Y). Da Broi et al. performed an experimental study to evaluate the effect of FF from infertile women with mild endometriosis (ME) on the genesis of meiotic oocyte anomalies. Samples of FF were obtained from 22 infertile women, 11 with ME, and 11 with tubal or male factors of infertility (control group) who underwent ovarian stimulation for intracytoplasmic sperm injection (ICSI) at their university IVF Unit. FF free of blood and containing a mature oocyte was obtained from 22 infertile women during oocyte retrieval for ICSI. Immature bovine oocytes underwent in vitro maturation (IVM) in the absence of FF (No-FF) and in the presence of four concentrations (1, 5, 10, and 15%) of FF from infertile women without endometriosis (C-FF) and with ME (ME-FF). Eleven replicates were performed, each one using FF from a control patient and a patient with ME. Each FF sample was used in only one experiment. After 22–24 h of IVM, oocytes were denuded, fixed, and immunostained for morphological visualization of microtubules and chromatin by confocal microscopy. A total of 1324 cumulus-oocyte complexes were matured in vitro. Of these, 1128 were fixed and 1048 were analyzed by confocal microscopy. The percentage of meiotically normal oocytes was significantly higher for oocytes that underwent IVM in the absence of FF (No-FF; 76.5%) and in the presence of 1% (80.9%), 5% (76.6%), 10% (75%), and 15% (76.2%) C-FF than in oocytes that underwent IVM in the presence of 1% (44.4%), 5% (36.7%), 10% (45.5%), and 15% (51.2%) ME-FF (P < 0.01). No differences were observed for FF concentrations within each group. When the four concentrations from each group were pooled, the number of oocytes in metaphase I stage was significantly higher in the ME-FF (50 oocytes) than in the C-FF (29 oocytes) group; and the percentage of meiotic abnormalities was significantly higher when oocytes were matured with ME-FF (55.8%) than with C-FF (23.1%), P < 0.01. Data obtained from studies using animal models may not necessarily be extrapolated to humans and studies evaluating in vivo matured oocytes from infertile women with ME are important to confirm their results. However, these results open new insights into the pathogenic mechanisms of infertility related to ME suggesting that FF from infertile women with ME may be involved in the worsening of oocyte quality of these women.
Aromatase plays a fundamental role in the establishment of oocyte quality, which might be compromised in infertile women with endometriosis. The expression of the CYP19A1 gene (that encodes aromatase) was compared in cumulus cells (CCs) and estradiol concentrations in the FF of infertile women with and without endometriosis submitted to ovarian stimulation for ICSI. CCs were isolated and the expression of the CYP19A1 was quantitated by real-time polymerase chain reaction. Estradiol concentrations in FF were measured by chemiluminescence immunoassay. A lower expression of the CYP19A1 in the CCs of infertile women with endometriosis was observed compared with controls (0.17 ± 0.13 and 0.56 ± 0.12, respectively), and no significant difference in the FF estradiol concentrations was observed between groups. These results show reduced expression of the CYP19A1 in CCs of infertile women with endometriosis, which may play a role in the pathogenesis of endometriosis-related infertility.
Retinol (ROL) and its biologically active metabolite, all-trans retinoic acid (ATRA), are essential for a number of reproductive processes. However, there is a paucity of information regarding their roles in ovarian folliculogenesis, oocyte maturation, and early embryogenesis. The objectives of Pauli et al.'s study were to quantify and compare peripheral plasma (PP) and FF retinoid levels, including ATRA in women undergoing IVF and to investigate the relationship between retinoid levels and embryo quality. Retinoid levels were evaluated in PP and FF from 79 women undergoing IVF at the time of oocyte retrieval and corresponding embryo quality assessed on a daily basis after retrieval for 3 days until uterine transfer. The analysis compared the retinoid levels with day 3 embryo grades and between endometriosis versus control patients. Results demonstrated distinctive levels of retinoid metabolites and isomers in FF versus PP. There was a significantly larger percentage of high-quality Grade I embryos derived from the largest versus smallest follicles. An increase in follicle size also correlated with a >50% increase in FF ROL and ATRA concentrations. Independent of follicle size, FF yielding Grade I versus non-Grade I embryos showed higher mean levels of ATRA but not ROL. In a nested case-control analysis, control participants had 50% higher mean levels of ATRA in their FF and PP than women with endometriosis. These findings strongly support the proposition that ATRA plays a fundamental role in oocyte development and quality, and that reduced ATRA synthesis may contribute to decreased fecundity of participants with endometriosis.
Giorgi et al. evaluated the potential protective effect of the antioxidants, L-carnitine (LC), and N-acetyl-cysteine (NAC) in preventing meiotic oocyte damage induced by FF from infertile women with ME. They performed an experimental study. The FF samples were obtained from 22 infertile women undergoing stimulated cycles for ICSI (11 with ME and 11 without endometriosis). Immature bovine oocytes were submitted to IVM divided into nine groups: No-FF (No-FF); with FF from control (CFF) or ME (EFF) groups; and with LC (C + LC and E + LC), NAC (C + NAC and E + NAC), or both antioxidants (C + 2Ao and E + 2Ao). After IVM, oocytes were immunostained for visualization of microtubules and chromatin by confocal microscopy. The percentage of meiotically normal MII oocytes was significantly lower in the EFF group (51.35%) compared to No-FF (86.36%) and CFF (83.52%) groups. The E + NAC (62.22%), E + LC (80.61%), and E + 2Ao (61.40%) groups showed the higher percentage of normal MII than EFF group. The E + LC group showed a higher percentage of normal MII than E + NAC and E + 2Ao groups and a similar percentage to No-FF and CFF groups. Therefore, FF from infertile women with ME causes meiotic abnormalities in bovine oocytes, and for the first time, these authors demonstrated that the use of NAC and LC prevents these damages. These findings elucidate part of the pathogenic mechanisms involved in infertility associated with ME and open perspectives for further studies investigating whether the use of LC could improve the natural fertility and/or the results of IVF of women with ME.
There is increasing evidence that autoimmune phenomena, including auto-antibody production, may affect fertility in women with endometriosis. The aims of the recent study were to evaluate anti-laminin-1 antibody (aLN-1) present in sera and FFs of women with endometriosis undergoing IVF and its impact on oocyte maturation and IVF outcome. Their results highlighted that aLN-1 are increased in women with endometriosis and their presence in FF may affect oocyte maturation leading to reduced fertility.
Hsu et al. set up a prospective cohort study to determine whether endometriosis is associated with mitochondrial dysfunction in cumulus (granulosa [GC]) cells of subjects undergoing IVF-ICSI. CC adenosine triphosphate (ATP) content was 65% lower in subjects with surgically proven endometriosis. There was no significant difference in mtDNA: GDNA ratio. The study summarized that surgically confirmed endometriosis may be associated with CC mitochondrial dysfunction in subjects undergoing IVF-ICSI for infertility as reflected by decreased ATP production.
Xu et al. examined the ultrastructure of oocytes from patients with minimal or ME and control females undergoing IVF treatment by transmission electron microscopy (TEM) to investigate the physiological significance of oocyte quality for patients with minimal or ME. The TEM results revealed that the oocytes from women with minimal or ME exhibited abnormal mitochondrial structure and decreased mitochondria mass. Quantitative real-time PCR analysis revealed that the mitochondrial DNA copy number was significantly reduced in the oocytes from women with minimal or ME compared with those of the control subjects. Their results suggest that decreased oocyte quality because of impaired mitochondrial structure and functions probably an important factor affecting the fertility of endometriosis patients.
| Recent Advances|| |
It is questioned whether worsening of oocyte quality, and OS are involved in the pathogenesis of infertility related to endometriosis and in compromised ICSI outcomes. CCs protect oocytes from entering apoptosis induced by OS. Donabela et al. carried out a case-control study comparing expression of superoxide dismutase 1 (SOD1), SOD2, and GPX4 (genes encoding for the main antioxidant enzymes) in CCs from mature oocytes of 26 infertile patients with minimal/ME, 14 patients with moderate/severe endometriosis, and 41 controls undergoing controlled ovarian stimulation for ICSI using real-time polymerase chain reaction. As a secondary objective, they investigated the interaction between the expression of these genes and CP by a statistical model. Only infertile women with moderate/severe endometriosis showed increased expression of the SOD1 in CCs compared to women with minimal/ME and controls, with a positive interaction between increased expression and the occurrence of CP suggesting that SOD1 might be a potential biomarker of CP following ICSI.
| Conclusions|| |
The endometriosis-related immune events may have a negative impact on almost all components of the reproductive function including fallopian tube function, oocyte quality, sperm function, fertilization, embryo quality, endometrial receptivity, implantation, and placentation. Most cases of infertility or miscarriage seen in women with endometriosis may be due to some immunological alterations associated with endometriosis. In spite of a great deal of effort over many decades, the mechanisms that lead to infertility in women with endometriosis remain unknown. Moreover, controversial results in the literature add even more difficulties in the understanding of this issue. Depending on the research group, there are conflicting data on the results of IVF in patients with endometriosis. Contemporary understanding now veers toward the knowledge that minimal or ME is specifically linked to the occurrence of impaired mitochondrial structure and reduced mtDNA copy numbers because of disorders of cytoplasmic maturation.,, Mitochondria are hypothesized to be derived exclusively from oocytes and their activities appear to be essential for oocyte maturation, chromosome segregation, and the capacity of a high level of development. Several studies have indicated that mitochondrial abnormalities and/or dysfunction could have an adverse influence on human embryonic developmental and might affect competence for the fertilization of human oocytes.,,, In addition, endometriosis lesions or its secretory products could result in mitochondria of poorer quality in oocytes that would affect fertilization and implantation.
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| Authors|| |
About the Author
Gautam N Allahbadia, MD is the Editor-in-Chief of the Journal of Obstetrics and Gynecology of India as well as the IVF Lite (Journal of Minimal Stimulation IVF). He is the Medical Director of Rotunda - The Center for Human Reproduction, the world-renowned infertility clinic at Bandra, and Rotunda-Blue Fertility Clinic and Keyhole Surgery Center, Mumbai, India. He is a noted world authority on ultrasound-guided embryo transfers and one of the pioneers in Third Party Reproduction in Southeast Asia. Dr. Allahbadia was responsible for India's first trans-ethnic surrogate pregnancy involving a Chinese couple's baby delivered by an unrelated Indian surrogate mother. He cherishes over 125 peer-reviewed publications, 134 book chapters and 22 textbooks, the latest being a comprehensive text, entitled “Minimal Stimulation IVF”, and is on the Editorial Board of several International Journals. He just completed a two year tenure as Medical Director at the New Hope IVF Clinic, Sharjah, UAE where he introduced IVF Lite to the country. Dr. Allahbadia has recently been elected as the Vice President of the World Association of Reproductive Medicine (WARM), headquartered in Rome, and “Mumbai's Top Doc” for 2012 by a peer nomination process. You can read more about his work at www.gautamallahbadia.com.