Endometriosis and infertility: the role of exogenous lipid peroxides in the peritoneal fluid

Pelvic pain symptoms and endometriosis characteristics in relation to oxidative stress among adolescents and adults with and without surgically-confirmed endometriosis

Background: While the majority of reproductive-aged females will experience pelvic pain during their lives, biological mechanisms underlying pelvic pain are not well understood. We investigated associations between pelvic pain symptoms and oxidative stress among people with and without surgically-confirmed endometriosis. Methods: Using an enzyme-linked immunosorbent assay, we measured 8-Hydroxy-2'-deoxyguanosine (8-OHdG) in urine samples and corrected for creatinine levels in 434 surgically-confirmed endometriosis participants compared to 605 participants never diagnosed with endometriosis. At enrollment, participants reported details of their pelvic pain symptoms. Linear regression was used to compute geometric mean (GM) creatinine-corrected 8-OHdG levels with 95% confidence intervals (CI) among all participants and those with and without endometriosis separately, adjusting for potential confounders. Interactions by surgically-confirmed endometriosis status were tested by Wald statistics. Results: No trends in 8-OHdG were observed among those with or without endometriosis for severity or frequency of dysmenorrhea, acyclic pelvic pain, dyspareunia or pain with bowel movements. Among endometriosis participants, lower 8-OHdG levels were observed for participants with any white, blue/black, or brown lesions (GM=76.7 versus 82.9 ng/mg; p=0.10), which was primarily driven by lower levels of 8-OHdG for any blue/black lesions (GM=72.8 versus 81.6 ng/mg; p=0.05). Conclusion: While no associations were observed between 8-OHdG and pelvic pain symptoms, future research is needed to assess how other pathways of oxidative damage, e.g. through proteins or lipids, may affect endometriosis-associated symptoms. Additionally, further research is needed to understand differences in oxidative stress among endometriosis lesion sub-phenotypes.

Systemic Oxidative Stress in Women with Ovarian and Pelvic Endometriosis: Role of Hormonal Therapy

This study was performed to evaluate the systemic oxidative stress balance in women with either ovarian or deep infiltrating endometriosis (DIE) and any alterations of the same during hormone therapy. Free oxygen radicals (FORT) and free oxidant radical defense (FORD) were measured in the capillary blood of 24 women without endometriosis, 26 women with endometrioma, and 26 women with DIE with or without endometrioma. Endometriosis was diagnosed by clinical and ultrasound assessment. Dietary factors, lifestyle habits, and intake of any substances interfering with the oxidative status were recorded. Women were prescribed contraceptive hormones, and the baseline assessments were repeated at the 3rd month of use, revealing a higher oxidative stress balance (FORT/FORD) in women with endometriosis than in controls (4.75 ± 4.4 vs. 2.79 ± 2.2; p = 0.05). The highest values were found in women with DIE (5.34 ± 4.6; p = 0.028 vs. controls). Regression analysis revealed an independent link between FORT/FORD and endometrioma (b 2.874, 95% CI 0.345, 5.403; p = 0.027) and DIE (b 4.419, 95% CI 1.775, 7.064; p = 0.001) but a negative correlation with HDL-cholesterol (b -0.063, 95% CI -0.125, -0.002; p = 0.043). In controls, the hormone therapy increased FORT (p = 0.003), but also FORD (p = 0.012), with the FORT/FORD balance remaining stable (2.72 ± 2.2 vs. 2.73 ± 1.8; p = 0.810). In women with endometriosis, FORT remained unchanged, but FORD increased (p = 0.004), and the FORT/FORD ratio significantly decreased (4.75 ± 4.4 vs. 2.57 ± 1.76; p = 0.002) to values similar to the control levels. These data indicate that systemic oxidative stress balance increased in women with endometriosis, particularly in those with DIE. The hormonal therapy did not change the oxidative stress balance in control women but significantly improved it in women with endometriosis, particularly those suffering from DIE.

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.

Evaluation of Oxidative Stress and Severity of Endometriosis

Aims

The aim was to evaluate the association between oxidative stress with the severity of endometriosis in blood and peritoneal fluid.

Settings and Design

This study was a prospective observational study conducted in the department of obstetrics and gynecology in a tertiary center over 2 years in patients with endometriosis requiring laparoscopy.

Methodology

Patients diagnosed with endometriosis and undergoing laparoscopy for infertility and/or chronic pelvic pain were included in the study. Out of the 64 patients recruited, only 55 patients formed the part of our study. Blood and peritoneal fluid was evaluated for oxidative stress parameters such as glutathione peroxidase, superoxide dismutase (SOD), and lipid peroxides.

Results

The severity of endometriosis was assessed intraoperatively by the revised American Society for Reproductive Medicine scoring in all 55 patients who underwent laparoscopy into minimal (n = 3), mild (n = 7), moderate (n = 32), and severe (n = 17). Median activity of SOD and glutathione peroxidase was lowest in the severe stage of endometriosis, whereas the median activity of lipid peroxide was highest in the severe stage of endometriosis in both blood and peritoneal fluid samples. There was a statistically significant increase in oxidative stress with the severity of endometriosis.

Conclusions

Oxidative stress might play a role in the disease process of endometriosis. Control of oxidative stress can be used as the latest treatment option for the management of endometriosis.

1H NMR based targeted metabolite profiling for understanding the complex relationship connecting oxidative stress with endometriosis

Accumulating evidence indicates the active role of oxidative stress in the development of endometriosis; however, the mechanism of reactive oxygen species generation is poorly understood. Metabonomics/metabolomics is a scientific discipline that can be used to study changes in metabolite ensembles associated with disease pathophysiology. The present study focuses on the use of proton nuclear magnetic resonance spectroscopy based targeted metabolite profiling approach to explore dysregulation in metabolites expression in women with endometriosis. Further, association of oxidative stress with the metabolite ensembles, if any, is investigated. Using multivariate statistics, partial least square discriminant analysis model was generated which could classify endometriosis patients with sensitivity and specificity of 92.83% and 100%, respectively, and with a classification rate of 96.4%. In conjunction with increased glucose metabolism, citrate and succinate were found to be elevated in endometriosis patients. Higher levels of reactive oxygen species, lipid peroxidation, and advanced oxidation protein products and lower levels of total antioxidant capacity, superoxide dismutase, catalase, and glutathione were also observed. Increased glucose metabolism and defects in the mitochondrial respiratory system are suggested to be the possible sources of excessive reactive oxygen species generation in endometriosis.

Low-density lipoproteins oxidation and endometriosis

The etiopathogenesis of endometriosis still remains unknown. Recent data provide new valuable information concerning the role of oxidative stress in the pathophysiology of the disease. It has been proved that levels of different lipid peroxidation end products are increased in both peritoneal fluid (PF) and serum of endometriotic patients. We assessed the concentration of oxidized low-density lipoproteins (oxLDL) in PF of 110 women with different stages of endometriosis and 119 women with serous (n = 78) or dermoid (n = 41) ovarian cysts, as the reference groups. PF oxLDL levels were evaluated by ELISA. We found that concentrations of oxLDL in PF of endometriotic women were significantly higher compared to women with serous but not dermoid ovarian cysts. Interestingly, by analyzing concentrations of oxLDL in women with different stages of the disease, it was noted that they are significantly higher only in the subgroup of patients with stage IV endometriosis as compared to women with ovarian serous cysts. In case of minimal, mild, and moderate disease, PF oxLDL levels were similar to those noted in reference groups. Our results indicate that disrupted oxidative status in the peritoneal cavity of women with endometriosis may play a role in the pathogenesis of advanced stages of the disease.

New trends for the medical treatment of endometriosis

INTRODUCTION

Endometriosis is a benign sex hormone-dependent gynecological disease, characterized by the presence and growth of endometrial tissue outside the uterus; it affects 10% of women of reproductive age and is associated with infertility and pain. Treatment of endometriosis involves conservative or radical surgery, or medical therapies. The goals for endometriosis treatment may be the relief of pain and/or a successful pregnancy achievement in infertile patients. Treatment must be individualized with a multidisciplinary approach. The classical treatments carry adverse side effects and in some cases a negative impact on quality of life. New agents promise a distinct perspective in endometriosis treatment.

AREAS COVERED

The aim of this paper is to systematically review the literature evidence of new medical treatments for endometriosis, defined as pharmacological treatments not yet commonly available and currently under investigation.

EXPERT OPINION

These new medical therapies would be used associated with surgical treatment and, in the future, will render possible the association of hormone therapy with non-hormonal treatment for endometriosis.

Effect of follicular fluid oxidative stress parameters on intracytoplasmic sperm injection outcome

OBJECTIVE

The purpose of this study was to evaluate the association between the follicular fluid (FF) reactive oxygen species (ROS) levels, total antioxidant capacity (TAC) and ROS-TAC score and pregnancy after intracytoplasmic sperm injection (ICSI).

METHODS

A total of 138 consecutive women who had ICSI were included in this study. FF ROS and TAC were measured by enhanced chemiluminescence and colorimetric assay, respectively, and then the ROS-TAC score was calculated.

RESULTS

Out of the 138 included patients, 42 (30%) achieved pregnancy after ICSI. Log ROS, TAC, and the ROS-TAC score were not significantly different across diagnoses. Pregnant cycles were associated with significantly lower ROS (P < 0.001), higher TAC (P < 0.001) and higher ROS-TAC scores (P < 0.001). After adjusting for age, there was a significant positive correlation between log ROS and the number of follicles on the day of HCG administration (correlation 0.20, 95% CI: 0.02, 0.39) as well as the number of oocytes retrieved (correlation 0.18, 0.001, 0.36) but not with TAC. Interestingly, in women with endometriosis, higher TAC levels and higher ROS-TAC scores were associated with a higher likelihood of finding normal oocytes (P = 0.005 and P = 0.002, respectively).

CONCLUSION

Higher FF TAC, higher FF ROS-TAC scores and lower FF ROS levels are associated with pregnancy after ICSI. Oxidative stress parameters may be markers of metabolic activity within the follicle.

Reactive oxygen species controls endometriosis progression

Endometriosis is associated with chronic inflammation, and reactive oxygen species (ROS) are proinflammatory mediators that modulate cell proliferation. We have investigated whether the dysregulation of ROS production in endometriotic cells correlates with a pro-proliferative phenotype and can explain the spreading of this disease. Stromal and epithelial cells were purified from ovarian endometrioma and eutopic endometrium from 14 patients with endometriosis to produce four primary cell lines from each patient. ROS production, detoxification pathways, cell proliferation, and mitogen-activated protein kinase pathway activation were studied and compared with epithelial and stromal cell lines from 14 patients without endometriosis. Modulation of the proliferation of endometriosis by N-acetyl-cysteine, danazol, and mifepristone was tested in vitro and in 28 nude mice implanted with endometriotic tissue of human origin. Endometriotic cells displayed higher endogenous oxidative stress with an increase in ROS production, alterations in ROS detoxification pathways, and a drop in catalase levels, as observed for tumor cells. This increase in endogenous ROS correlated with increased cellular proliferation and activation of ERK1/2. These phenomena were abrogated by the antioxidant molecule N-acetyl-cysteine both in vitro and in a mouse model of endometriosis. Human endometriotic cells display activated pERK, enhanced ROS production, and proliferative capability. Our murine model shows that antioxidant molecules could be used as safe and efficient treatments for endometriosis.

The role of the oxidative-stress in the endometriosis-related infertility

Endometriosis is a common gynecological disorder of the reproductive age characterised by pelvic pain, dysmenorrhea and infertility. Classic theories have failed to propose a precise pathogenetic mechanism. Recent studies have investigated the role of the immune system and oxidative stress in the development of endometriosis as well as the identification of biomarkers for a non-invasive diagnosis of the disease. At endometriotic sites, inflammatory cells including eosinophils, neutrophils and macrophages generate reactive oxygen species that contribute to the development of oxidative stress in the peritoneal cavity. Oxidative stress further augments immune response in affected sites. The oxidants exacerbate the development of endometriosis by inducing chemoattractants and endometrial cell growth-promoting activity. The oxidative proinflammatory state of the peritoneal fluid is an important mediator of endometriosis. Many studies investigate the correlation of endometriosis and oxidative stress but the results are discrepant. Furthermore, oxidative stress has been implicated in unexplained infertility and has been associated with some of its causative factors. Oxidative stress influences women's reproductive capacity. The association between endometriosis and infertility is described in several studies and still remains debated.

Oxidative stress and antioxidants: exposure and impact on female fertility

BACKGROUND

Reproductive failure is a significant public health concern. Although relatively little is known about factors affecting fertility and early pregnancy loss, a growing body of literature suggests that environmental and lifestyle factors play an important role. There is sufficient evidence to hypothesize that diet, particularly its constituent antioxidants, and oxidative stress (OS) may influence the timing and maintenance of a viable pregnancy. We hypothesize that conditions leading to OS in the female affect time-to-pregnancy and early pregnancy loss.

METHODS

We review the epidemiology of female infertility related to antioxidant defenses and oxidation and examine potential sources of OS from the ovarian germ cell through the stages of human pregnancy and pregnancy complications related to infertility. Articles were identified through a search of the PubMed database.

RESULTS

Female OS is a likely mediator of conception and threshold levels for OS exist, dependent on anatomic location and stage of preconception.

CONCLUSIONS

Prospective pregnancy studies with dietary assessment and collection of biological samples prior to conception with endpoints of time-to-pregnancy and early pregnancy loss are needed.

Oxidative stress and tumor necrosis factor–α–induced alterations in metaphase II mouse oocyte spindle structure

OBJECTIVE(S)

To examine the effect of exogenous exposure to hydrogen peroxide (H(2)O(2)) and tumor necrosis factor (TNF)-alpha on mouse metaphase II (MII) oocyte spindle structure and to examine the potential benefits of supplementing the culture media with vitamin C.

DESIGN

Prospective study.

SETTING

Research laboratory in a tertiary hospital.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Microtubule changes and alterations in chromosomal alignment.

RESULT(S)

Both concentration- and time-dependent alterations were seen in spindle structure after exposure to H(2)O(2). An H(2)O(2) concentration as low as 12.5 microM increased the odds of an oocyte with altered microtubule and chromosome alignment (score >or=3) by 93%. Significantly increased damage was seen with increasing period of incubation. Higher scores were seen after exposure to both TNF-alpha alone and in combination with H(2)O(2) compared with controls. Changes in chromosomal alignment were comparable among the three groups. Oocytes coincubated with H(2)O(2) and vitamin C at 200 microM demonstrated less damage compared with those with H(2)O(2) alone.

CONCLUSION(S)

Oxidative stress results in concentration and time-dependent alterations in the spindle structure and augments the effects induced by TNF-alpha. Proper oocyte handling in vitro may help reduce oxidative insult, thus improving the oocyte quality. Antioxidants may have a protective effect and need to be further evaluated.

Comparative proteomic analysis of human adenomyosis using two-dimensional gel electrophoresis and mass spectrometry

OBJECTIVE

To identify the differently expressed proteins in adenomyotic tissue compared with normal uterine muscle.

DESIGN

Retrospective, case-controlled study.

SETTING

University-based Department of Obstetrics and Gynecology and Proteomic Research Center.

PATIENT(S)

Ten patients who underwent transabdominal hysterectomy were included in this study. Five of them were histologically diagnosed with adenomyosis and the other five age-matched patients had cervical carcinoma in situ.

INTERVENTION(S)

Postoperative adenomyotic tissue and normal uterine muscle samples were collected.

MAIN OUTCOME MEASURE(S)

The protein extracts from paired sample tissue were separated using two-dimensional gel electrophoresis. The differently expressed protein spots were detected by gel comparison using image analysis software and identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry.

RESULT(S)

Compared with protein profiling of normal uterine muscle, there were 12 protein spots dysregulated in adenomyotic tissue. Among them, 10 protein spots were successfully identified by mass spectrometry.

CONCLUSION(S)

Comparative proteomic analysis is a useful approach for the discovery of protein biomarkers for adenomyosis and understanding the pathophysiology of the disease.

Decreased lactoferrin levels in peritoneal fluid of women with minimal endometriosis

OBJECTIVE

The aim of the study was to evaluate for the presence of lactoferrin (LTF) in peritoneal fluid (PF) of women with and without endometriosis.

PATIENTS

Seventy-eight women were studied, including 49 women with endometriosis and, as a reference group, 29 patients with functional follicle ovarian cysts.

RESULTS

Lactoferrin levels were detectable in all peritoneal fluid samples. Women with minimal endometriosis had lower PF lactoferrin concentrations compared to both patients with high revised American Fertility Society classification scores and women with follicle ovarian cysts. No significant difference in the peritoneal LTF levels was found between patients with stage II endometriosis, stage III or IV endometriotic disease and women with functional cysts of ovaries.

CONCLUSIONS

Owing to its antibacterial properties lactoferrin is probably an important defense factor in the peritoneal cavity, however its role in the pathogenesis of endometriosis remains enigmatic.

Nuclear factor-kappab (NF-kappaB): an unsuspected major culprit in the pathogenesis of endometriosis that is still at large?

Endometriosis, defined as the ectopic presence of endometrial glandular and stromal cells outside the uterine cavity, is a common benign gynecological disorder with an enigmatic pathogenesis. Many genes and gene products have been reported to be altered in endometriosis, yet some of them may not be major culprits but merely unwitting accomplices or even innocent bystanders. Therefore, the identification and apprehension of major culprits in the pathogenesis of endometriosis are crucial to the understanding of the pathogenesis and would help to develop better therapeutics for endometriosis. Although so far NF-kappaB only has left few traces of incriminating fingerprints, several lines of investigation suggest that NF-kappaB, a pivotal pro-inflammatory transcription factor, could promote and maintain endometriosis. Various inflammatory agents, growth factors, and oxidative stress activate NF-kappaB. NF-kappaB proteins themselves and proteins regulated by them have been linked to cellular transformation, proliferation, apoptosis, angiogenesis, and invasion. Interestingly, all existing and nearly all investigational medications for endometriosis appear to act through suppression of NF-kappaB activation. In endometriotic cells, NF-kappaB appears to be constitutively activated, and suppression of NF-kappaB activity by NF-kappaB inhibitors or proteasome inhibitors suppresses proliferation in vitro. Viewing NF-kappaB as a major culprit, an autoregulatory loop model can be postulated, which is consistent with existing data and, more importantly, can explain several puzzling phenomena that are otherwise difficult to interpret based on prevailing theories. This view has immediate and important implications for novel ways to treat endometriosis. Further research is warranted to precisely delineate the roles of NF-kappaB in the pathogenesis of endometriosis and to indict and convict its aiders and abettors.

The presence of antibodies to oxidative modified proteins in serum from polycystic ovary syndrome patients

Polycystic ovary syndrome (PCOS) affects 5-10% of women of reproductive age. Free radicals, as a product of oxidative stress, impair cells and tissue properties related to human fertility. These free radicals, together with the oxidized molecules, may have a cytotoxic or deleterious effects on sperm and oocytes, on early embryo development or on the endometrium. Aldehyde-modified proteins are highly immunogenic and circulating autoantibodies to new epitopes, such as malondialdehyde (MDA), may affect the reproductive system. Autoantibodies or elevated reactive oxygen species (ROS) in serum are often associated with inflammatory response. The purpose of this work is to investigate whether PCOS women show increased levels of oxidized proteins (protein-MDA) and anti-endometrial antibodies (AEA) in their sera, compared with control patients, and to determine whether AEA specificity is related to oxidized protein derivatives. Sera from 31 women [10 patients with PCOS (PCOS group) and 21 women with male factor of infertility (control group)] were chosen from patients attending for infertility. Anti-endometrial antibodies were determined by enzyme-linked immunosorbent assay (ELISA) with an endometrial cell line (RL-95). Antibodies against MDA modified human serum albumin (HSA-MDA) were also determined by ELISA. Oxidized proteins (protein-MDA) in serum were determined by a colorimetric assay. Patients with PCOS have significantly higher levels of AEA and anti-HSA-MDA, as well as oxidized proteins (protein-MDA) in serum than control patients. For the first time, we describe an autoimmune response in PCOS patients, in terms of AEA. The evidence of protein-MDA in the serum of these patients, together with the increased antibody reactivity to MDA-modified proteins (HSA-MDA) in vitro, supports the conclusion that oxidative stress may be one of the important causes for abnormal endometrial environment with poor embryo receptivity in PCOS patients.

Role of oxidative stress in endometriosis

Endometriosis is a chronic pleomorphic disorder with pelvic or systemic manifestations, and is characterized by the presence of endometrial glands and stroma. In the United States, the prevalence of the disease is estimated to range from 2 to 50% in women of reproductive age. No single theory can explain the histogenesis and the pleomorphic manifestations of endometriosis. Endometriosis is being reported in younger age women and manifesting with increasing severity, hence the need to understand the role of oxidative stress (OS) in endometriosis. The presence of elevated concentrations of free radicals and lowered antioxidant potential leads to OS. The development of OS in the local peritoneal environment may be one of the links in the chain of events leading to endometriosis. Redox levels may modulate the severity and the dynamics of endometriosis and progression of the disease. OS has been implicated in infertility associated with endometriosis. Recent literature reviewed investigates the role of molecular mechanisms and genetic pathways that may modulate cellular response to OS. Antioxidant supplementation, immunomodulators, and selective progesterone receptor modulators with antioxidant effects have been investigated as possible treatments for endometriosis, but compelling evidence on the benefits of the various modalities is lacking. Results of the limited number of animal and human trials need to be corroborated by larger randomized controlled trials.

Role of oxidative stress in female reproduction

In a healthy body, ROS (reactive oxygen species) and antioxidants remain in balance. When the balance is disrupted towards an overabundance of ROS, oxidative stress (OS) occurs. OS influences the entire reproductive lifespan of a woman and even thereafter (i.e. menopause). OS results from an imbalance between prooxidants (free radical species) and the body's scavenging ability (antioxidants). ROS are a double-edged sword - they serve as key signal molecules in physiological processes but also have a role in pathological processes involving the female reproductive tract. ROS affect multiple physiological processes from oocyte maturation to fertilization, embryo development and pregnancy. It has been suggested that OS modulates the age-related decline in fertility. It plays a role during pregnancy and normal parturition and in initiation of preterm labor. Most ovarian cancers appear in the surface epithelium, and repetitive ovulation has been thought to be a causative factor. Ovulation-induced oxidative base damage and damage to DNA of the ovarian epithelium can be prevented by antioxidants. There is growing literature on the effects of OS in female reproduction with involvement in the pathophysiology of preeclampsia, hydatidiform mole, free radical-induced birth defects and other situations such as abortions. Numerous studies have shown that OS plays a role in the pathophysiology of infertility and assisted fertility. There is some evidence of its role in endometriosis, tubal and peritoneal factor infertility and unexplained infertility. This article reviews the role OS plays in normal cycling ovaries, follicular development and cyclical endometrial changes. It also discusses OS-related female infertility and how it influences the outcomes of assisted reproductive techniques. The review comprehensively explores the literature for evidence of the role of oxidative stress in conditions such as abortions, preeclampsia, hydatidiform mole, fetal embryopathies, preterm labour and preeclampsia and gestational diabetes. The review also addresses the growing literature on the role of nitric oxide species in female reproduction. The involvement of nitric oxide species in regulation of endometrial and ovarian function, etiopathogenesis of endometriosis, and maintenance of uterine quiescence, initiation of labour and ripening of cervix at parturition is discussed. Complex interplay between cytokines and oxidative stress in the etiology of female reproductive disorders is discussed. Oxidant status of the cell modulates angiogenesis, which is critical for follicular growth, corpus luteum formation endometrial differentiation and embryonic growth is also highlighted in the review. Strategies to overcome oxidative stress and enhance fertility, both natural and assisted are delineated. Early interventions being investigated for prevention of preeclampsia are enumerated. Trials investigating combination intervention strategy of vitamin E and vitamin C supplementation in preventing preeclampsia are highlighted. Antioxidants are powerful and there are few trials investigating antioxidant supplementation in female reproduction. However, before clinicians recommend antioxidants, randomized controlled trials with sufficient power are necessary to prove the efficacy of antioxidant supplementation in disorders of female reproduction. Serial measurement of oxidative stress biomarkers in longitudinal studies may help delineate the etiology of some of the diosorders in female reproduction such as preeclampsia.

Oxidative stress and endometriosis

BACKGROUND

Little is known about the aetiology of endometriosis; however, in the presence of oxidative stress, reactive oxygen species might increase growth and adhesion of endometrial cells in the peritoneal cavity, leading to endometriosis and infertility. Within a study investigating persistent organic compounds and endometriosis, the authors evaluated the association between oxidative stress and endometriosis.

METHODS

Women aged 18-40 years who were undergoing laparoscopy were contacted to participate in the study (n = 100); 84 were eligible and agreed to be interviewed; 78 provided blood specimens. Four markers of oxidative stress and antioxidant status were measured in serum for 61 women. Multiple imputation of missing data was used to generate values for the missing oxidative stress data.

RESULTS

Thirty-two women had visually confirmed endometriosis at laparoscopy while 52 did not, including 22 undergoing tubal ligation and 30 with idiopathic infertility. There was a weak association between thiobarbituric acid-reactive substances (nmol/ml) and endometriosis, after adjusting for age, body mass index, current smoking, hormone use in the past 12 months, gravidity, serum vitamin E, serum estradiol, and total serum lipids (beta = 1.18; 95% CI-0.04, 2.39).

CONCLUSIONS

These results suggest that oxidative stress might play a role in the development and progression of endometriosis, which should be evaluated in larger studies.

Lipid peroxidation in the peritoneal fluid of infertile women with peritoneal endometriosis

OBJECTIVE

To assess the level of lipid peroxidation in the peritoneal fluid of infertile women with peritoneal endometriosis and of fertile disease-free controls.

STUDY DESIGN

Level of lipid peroxidation (malondialdeyde, malondialdeyde with copper addition, and cholest-3,5-dien-7-one) was measured in the peritoneal fluid obtained from 21 women with endometriosis-related infertility and from 21 fertile women having tubal ligation.

RESULTS

: The level of lipid peroxidation did not differ significantly (P > 0.05) according to the stage of endometriosis. The level of lipid peroxidation (malondialdeyde, malondialdeyde with the addition of copper, and cholest-3,5-dien-7-one) did not differ significantly (P > 0.05) between patients with endometriosis-related infertility (0.07 nmol/ml, 0.34 nmol/ml, 0.24 microg/ml, respectively) and disease-free controls (0.04 nmol/ml, 0.21 nmol/ml, 0.25 microg/ml, respectively).

CONCLUSION

The level of lipid peroxidation did not differ between women with endometriosis-related infertility and fertile disease-free controls, suggesting that increased reactive oxygen species may not be one of the factors responsible for compromised fertility in patients with endometriosis.

Role of reactive oxygen species in gynecologic diseases

Free radicals derived from molecular oxygen and nitrogen are highly reactive metabolites called reactive oxygen species (ROS). Cells continuously produce free radicals and ROS as part of the metabolic process. They are involved in the various functions of the reproductive system. Antioxidants are enzymes or compounds that scavenge and reduce the presence of free radicals. Normally, a balance exists between concentrations of reactive oxygen species and antioxidant scavenging systems. The disruption of the delicate balance between pro- and antioxidants results in oxidative stress. Oxidative stress has been implicated in embryo fragmentation, DNA damage, apoptosis and poor pregnancy outcome. It has also been implicated in a large number of gynecologic diseases, such as endometriosis, pre-eclampsia and maternal diabetes. The use of antioxidants may be beneficial in combating the harmful effects of oxidative stress in many of these diseases. The present review outlines the importance of these species in the pathology of various gynecologic diseases. (Reprod Med Biol 2004; 3: 177 - 199).

Investigation of glutathione concentrations in peritoneal fluid from women with and without endometriosis

Changes in the peritoneal fluid (PF) environment have been implicated in the pathogenesis of endometriosis as well as in the decrease of fertility.

OBJECTIVE

To evaluate the concentration of glutathione in PF of women with endometriosis.

PATIENTS

Twenty-one patients with endometriosis (I or II rAFS stage, n=11; III or IV rAFS stage, n=10), and 29 patients with follicular or dermoid ovarian cysts (n=17 and n=12, respectively).

RESULTS

Mean (+/-S.D.) PF glutathione concentration was 0.22+/-0.01 micromol/ml in patients with minimal or mild endometriosis, 0.21+/-0.05 micromol/ml in women with III or IV stage of the disease, 0.24 +/- 0.03 micromol/ml in women with follicle ovarian cysts, and 0.23+/-0.05 micromol/ml in patients with dermoid tumors of ovaries. No significant difference in the peritoneal glutathione level was found between the groups.

CONCLUSION

These results suggest that PF glutathione is not involved in the progression of endometriosis.

Oxidative stress may be a piece in the endometriosis puzzle

OBJECTIVE

To assess the total antioxidant potential of women with endometriosis-associated infertility, women with idiopathic infertility, and fertile controls.

DESIGN

Retrospective study.

SETTING

University medical hospital.

PATIENT(S)

Sixty-five women admitted for diagnostic laparoscopy.

MAIN OUTCOME MEASURES

Peritoneal fluid samples were analyzed for superoxide dismutase activity and total antioxidant status on spectrophotometry, glutathione peroxidase activity on enzyme-linked immunosorbent assay, and lipid peroxides levels on colorimetry.

RESULT(S)

Mean activity of superoxide dismutase, glutathione peroxidase, and total antioxidant status was lowest and lipid peroxide level was highest among infertile patients with endometriosis. Women with idiopathic infertility, in contrast, had the highest superoxide dismutase, glutathione peroxidase, and total antioxidant status activity and the lowest lipid peroxide level.

CONCLUSION(S)

High antioxidant potential is not a contributing factor in women with idiopathic infertility. Low total antioxidant status and low activity of antioxidant enzymes in the peritoneal fluid of infertile women with endometriosis probably do not influence fertility in these women, but these factors may play a role in the development of the disease.

Oxidative stress and peritoneal endometriosis

OBJECTIVE

To review the literature associating pelvic endometriosis with oxidative stress and to discuss the potential causes and consequences of a pro-oxidant environment in the peritoneal cavity.

DESIGN

Literature survey.

RESULT(S)

Several studies suggest that oxidative stress is a component of the inflammatory reaction associated with endometriosis. Evidence includes the prevention of endometriosis induction in rabbits by the addition of antioxidants, an increase in reactive oxygen species release by macrophages, increased peritoneal levels of oxidized low-density lipoproteins and their by-products, altered expression of endometrial pro-oxidant and antioxidant enzymes, and consumption of peritoneal fluid vitamin E. Retrograde menstruation is likely to carry highly pro-oxidant factors, such as heme and iron, into the peritoneal cavity, as well as apoptotic endometrial cells, which are well-known inducers of oxidative stress. Reactive oxygen species may be involved in endometriosis-associated infertility and may play a role in the regulation of the expression of genes encoding immunoregulators, cytokines and cell adhesion molecules implicated in the pathogenesis of endometriosis.

CONCLUSION(S)

Better understanding of the mechanisms of reactive oxygen species production and detoxification and further investigation of their effect on the peritoneal environment are essential to obtain new insight into this disease and eventually develop new diagnostic and therapeutic strategies.

Macrophages, oxidation, and endometriosis

Retrograde menstruation has been suggested to be the cause for the presence of endometrial cells in the peritoneal cavity. However, little is known about the events that lead to the adhesion and growth of these cells that ultimately result in endometriosis, considering the fact that the disease occurs only in certain women despite the common occurrence of retrograde menstruation in most women. We postulate that, in normal women, the endometrial cells and tissue that arrive in the peritoneal cavity during menstruation are effectively removed by macrophages that are chemoattracted and become resident tissue macrophages in the peritoneal cavity. In contrast, the peritoneal macrophages in women with endometriosis are nonadherent and ineffectively scavenged, resulting in the sustained presence and growth of the endometrial cells. We also postulate that the peritoneal fluid is not a passive reservoir of the factors secreted by cells of the peritoneum, but actively promotes endometriosis. The peritoneal fluid is rich in lipoproteins, particularly low-density lipoprotein, which generates oxidized lipid components in a macrophage-rich inflammatory milieu. The oxidants exacerbate the growth of endometriosis by inducing chemoattractants such as MCP-1 and endometrial cell growth-promoting activity. We provide evidence for the presence of oxidative milieu in the peritoneal cavity of women with endometriosis, the nonscavenging properties of macrophages that are nonadherent, and the synergistic interaction between macrophages, oxidative stress, and the endometrial cells. For example, the peritoneal fluid lipoproteins of subjects with endometriosis have increased the propensity to undergo oxidation as compared with plasma lipoproteins, and the subjects also have increased titer of autoantibodies to oxidatively modified proteins. If the oxidative proinflammatory nature of the peritoneal fluid is an important mediator of endometriosis growth, anti-inflammatory agents and antioxidants might afford protection against endometriosis.

Total antioxidant status of peritoneal fluid in infertile women

OBJECTIVE

To determine whether impairment of the antioxidant systems of peritoneal fluid might be a factor responsible for infertility.

STUDY DESIGN

Total antioxidant status was measured in peritoneal fluid obtained from 18 infertile women suffering from minimal or mild endometriosis, 23 patients with unexplained infertility, 12 women with tubal infertility and 13 fertile women.

RESULTS

Total antioxidant status was significantly lower in peritoneal fluid from women with unexplained infertility (0.49+/-0.21 mmol/l) compared to both fertile patients (0.67+/-0.24 mmol/l, P=0.02) and women with tubal infertility (0.76+/-0.26 mmol/l, P=0.001). Peritoneal fluid total antioxidant status did not differ significantly between patients with endometriosis (0.61+/-0.2 mmol/l), tubal infertility and the fertile group (P>0.05).

CONCLUSIONS

Our results suggest that low antioxidant status in peritoneal fluid may play a role in the pathogenesis of infertility.

Levels of lipid peroxides and superoxide dismutase in peritoneal fluid of patients with endometriosis

In order to evaluate the changes of lipid perioxides (LPO) and superoxide dismutase (SOD) levels in peritoneal fluid in patients with endometriosis, the levels of LPO and SOD in peritoneal fluids from infertile women with endometriosis and with normal pelvis were measured. The result showed that the levels of LPO but SOD was elevated significantly in peritoneal fluid from women with endometriosis than in women with normal pelvis (P < 0.01). It is suggested that free oxygen radicals may be involved in the pathogenesis of endometriosis associated infertility.