Serum adiponectin concentrations are decreased in women with endometriosis

The mysterious association between adiponectin and endometriosis

Adiponectin is a pleiotropic cytokine predominantly derived from adipose tissue. In addition to its role in regulating energy metabolism, adiponectin may also be related to estrogen-dependent diseases, and many studies have confirmed its involvement in mediating diverse biological processes, including apoptosis, autophagy, inflammation, angiogenesis, and fibrosis, all of which are related to the pathogenesis of endometriosis. Although many researchers have reported low levels of adiponectin in patients with endometriosis and suggested that it may serve as a protective factor against the development of the disease. Therefore, the purpose of this review was to provide an up-to-date summary of the roles of adiponectin and its downstream cytokines and signaling pathways in the aforementioned biological processes. Further systematic studies on the molecular and cellular mechanisms of action of adiponectin may provide novel insights into the pathophysiology of endometriosis as well as potential therapeutic targets.

Evaluation of adipokines concentrations in plasma, peritoneal, and endometrioma fluids in women operated on for ovarian endometriosis

Introduction

Some studies indicate the role of selected adipokines in the development of endometriosis. However, a comprehensive assessment of plasma, peritoneal, and endometrioma fluids adipokines concentrations in women with ovarian endometriosis has not yet been performed. Therefore, this study aimed to analyze plasma, peritoneal, and endometrioma fluids selected adipokines concentrations in women operated on for ovarian endometriosis.

Materials and methods

A cross-sectional cohort study involved 56 women operated on for ovarian endometriosis. Body mass, height, and waist circumference were measured, and BMI was calculated. Plasma, peritoneal, and endometrioma fluids adiponectin, leptin, omentin resistin, RBP4, and visfatin/NAMPT were determined by ELISA.

Results

The highest plasma levels of adiponectin, leptin, omentin, and RBP4 than in the endometrioma and peritoneal fluids were found, while levels of resistin and visfatin/NAMPT were significantly higher in endometrioma fluid than in plasma and peritoneal fluid. In addition, levels of visfatin/NAMPT were significantly higher in peritoneal fluid than in plasma. There were also positive correlations between leptin, RBP4, and adiponectin levels in endometrioma and peritoneal fluids (ρ = 0.28; p < 0.05; ρ = 0.31; p < 0.05; ρ= 0.32; p < 0.05, respectively). There were no associations between adipokines levels in plasma, endometrioma, and peritoneal fluids and endometriosis stage.

Conclusion

Our results show that visfatin/NAMPT and resistin may be locally secreted in endometrioma related to inflammation regardless of the stage of endometriosis.

A monoclonal antibody activating AdipoR for type 2 diabetes and nonalcoholic steatohepatitis

Adiponectin receptors, AdipoR1 and AdipoR2 are promising targets for the prevention and treatment of metabolic diseases. In this study, we aimed to establish agonistic antibodies against AdipoR1 and AdipoR2 with a long enough half-life to provide a means of improving poor medication adherence associated with preclinical small-molecule AdipoR agonists or existing antidiabetic drugs. Monoclonal antibodies were obtained by immunizing AdipoR knockout mice with human AdipoR-expressing cells. Of the antibodies shown to bind to both, an agonist antibody was obtained, which exhibited adenosine 5'-monophosphate-activated protein kinase-activating properties such as adiponectin and was named AdipoR-activating monoclonal antibody (AdipoRaMab). AdipoRaMab ameliorated glucose intolerance in high-fat diet-fed mice, which was not observed in AdipoR1·AdipoR2 double knockout mice. AdipoRaMab exhibited anti-inflammatory and antifibrotic effects in the nonalcoholic steatohepatitis (NASH) model, indicating its therapeutic potential in diabetes and in NASH. In addition, the results of this study indicated that AdipoRaMab may exert therapeutic effects even in a once-monthly dosing regimen through its humanization.

Association between endometriosis and risk of type 2 diabetes: Results from the prospective E3N cohort

OBJECTIVE

Several studies suggest an association between endometriosis and the risk of cardio-metabolic diseases. This study aimed to prospectively evaluate the association between history of endometriosis and incident type 2 diabetes.

STUDY DESIGN

E3N is a prospective cohort of 98,995 French women aged 40-65 years at inclusion. Multivariable Cox regression models were used to estimate hazard ratios and 95 % confidence intervals for the association between endometriosis and incident type 2 diabetes. We evaluated effect modification by age, body mass index, infertility treatment, adherence to the Mediterranean diet, and menopausal status.

RESULTS

Age at inclusion was 51 ± 6 years and there were 2672 incident cases of type 2 diabetes. A total of 4606 women reported surgically-confirmed endometriosis among 83,582 women with no history of diabetes at inclusion. Endometriosis was not associated with type 2 diabetes risk in a model adjusted for age, BMI, physical activity, smoking, education, age at menarche and oral contraceptive use (hazard ratio [HR] = 1.09; 95 % confidence interval [CI] = 0.92-1.29), neither after further adjustment for family history of diabetes, hypertension and menopausal status (HR = 0.97;95%CI = 0.80-1.16). The relationship did not differ by age at inclusion, BMI, infertility treatment, diet or menopausal status (p > 0.05).

CONCLUSIONS

Surgically-confirmed endometriosis was not associated with the risk of type 2 diabetes in this large cohort, confirming that endometriosis is not a risk marker for type 2 diabetes.

The Complex Roles of Adipokines in Polycystic Ovary Syndrome and Endometriosis

Polycystic ovary syndrome (PCOS) and endometriosis are frequent diseases of the female reproductive tract causing high morbidity as they can significantly affect fertility and quality of life. Adipokines are pleiotropic signaling molecules secreted by white or brown adipose tissues with a central role in energy metabolism. More recently, their involvement in PCOS and endometriosis has been demonstrated. In this review article, we provide an update on the role of adipokines in both diseases and summarize previous findings. We also address the results of multi-omics approaches in adipokine research to examine the role of single nucleotide polymorphisms (SNPs) in genes coding for adipokines and their receptors, the secretome of adipocytes and to identify epigenetic alterations of adipokine genes that might be conferred from mother to child. Finally, we address novel data on the role of brown adipose tissue (BAT), which seems to have notable effects on PCOS. For this review, original research articles on adipokine actions in PCOS and endometriosis are considered, which are listed in the PubMed database.

Metformin as a Potential Treatment Option for Endometriosis

Endometriosis is a common disease in women of reproductive age, and its pathogenesis seems to be largely affected by hormone imbalance, inflammation, oxidative stress, and autophagy dysregulation. These pathophysiological disturbances interact with one another through mechanisms that are still awaiting elucidation. The aim of this article is to present current knowledge regarding the possibilities of using metformin in the pharmacological treatment of endometriosis. Metformin is an insulin sensitizer widely used for the treatment of type 2 diabetes mellitus. The pleiotropic effects of metformin are mainly exerted through the activation of AMP-activated protein kinase, which is the key cellular energy homeostasis regulator that inhibits mTOR, a major autophagy suppressor. Metformin regresses endometriotic implants by increasing the activity of superoxide dismutase. It is also an inhibitor of metalloproteinase-2, decreasing the levels of the vascular endothelial growth factor and matrix metalloproteinase-9 in animal studies. In endometriosis, metformin might modify the stroma-epithelium communication via Wnt2/β-catenin. With its unique therapeutic mechanisms and no serious side effects, metformin seems to be a helpful anti-inflammatory and anti-proliferative agent in the treatment of endometriosis. It could be a missing link for the successful treatment of this chronic disease.

Association of leptin and adiponectin levels with endometriosis: a systematic review and meta-analysis

BACKGROUND

We aimed to summarize the available data regarding the levels of leptin and adiponectin and the key modulators of endometriosis compared to the controls.

METHODS

The electronic databases such as MEDLINE, Embase, Scopus, Cochrane Library, and Web of Science were searched up to October 2020. The circulating and peritoneal levels of leptin and circulating levels of adiponectin were included. We used the Cochrane's Q test and the I² statistic in this study. These tests' weighted mean difference (WMD) and 95% CIs were considered as the summary effect size. They were then pooled using a random-effects model with the DerSimonian-Laird method.

RESULTS

Twenty eligible articles (or 25 studies) with 2645 participants (1362 women with endometriosis and 1283 controls) were included. Pooled results showed that women with endometriosis had significantly higher leptin levels (WMD = 4.45 mg/ml, 95%CI = 2.42-6.49, p < .01) and leptin/BMI ratio (WMD = 0.32 mg/ml, 95%CI = 0.23-0.42, p < .001) than the controls, whereas adiponectin levels (WMD = -0.24 mg/ml, 95%CI = -4.27 to -0.01, p = .038) were significantly lower. The pooled results also indicated significantly lower leptin levels in women with advanced-stage endometriosis (WMD = -8.07 mg/ml, 95%CI = -14.22 to -1.92, p = .01) than in the early stage. It was found, however, that there were no significant differences in adiponectin levels of women with advanced-stage endometriosis (WMD = -0.16 mg/ml, 95%CI = -0.64 to 0.32, p = .512) and the early-stage ones.

CONCLUSION

We showed that leptin levels and leptin/BMI ratio were significantly higher in women with endometriosis than the controls. Nonetheless, patients with endometriosis had significantly lower levels of adiponectin than the controls.

The Formidable yet Unresolved Interplay between Endometriosis and Obesity

Obesity and endometriosis are two very common entities, yet there is uncertainty on their exact relationship. Observational studies have repeatedly shown an inverse correlation between endometriosis and a low body mass index (BMI). However, obesity does not protect against endometriosis and on the contrary an increased BMI may lead to more severe forms of the disease. Besides, BMI is not accurate in all cases of obesity. Consequently, other anthropometric and phenomic traits have been studied, including body adiposity content, as well as the effect of BMI early in life on the manifestation of endometriosis in adulthood. Some studies have shown that the phenotypic inverse correlation between the two entities has a genetic background; however, others have indicated that certain polymorphisms are linked with endometriosis in females with increased BMI. The advent of metabolic bariatric surgery and pertinent research have led to the emergence of biomolecules that may be pivotal in understanding the pathophysiological interaction of the two entities, especially in the context of angiogenesis and inflammation. Future research should focus on three objectives: detection and interpretation of obesity-related biomarkers in experimental models with endometriosis; integration of endometriosis-related queries into bariatric registries; and multidisciplinary approach and collaboration among specialists.

A prospective study of endometriosis and risk of type 2 diabetes

AIMS/HYPOTHESIS

The objective of this study was to investigate the association between laparoscopically confirmed endometriosis and risk of type 2 diabetes.

METHODS

We used data from the Nurses' Health Study II, a prospective cohort of female nurses followed for >25 years (N = 112,037). We used Cox proportional hazards models to estimate the HRs and 95% CIs of incident, confirmed type 2 diabetes (n = 8496 participants) adjusted a priori for confounding factors. We additionally investigated differences in the relationship between endometriosis and type 2 diabetes by age (<50 or ≥50 years), BMI (<30 or ≥30 kg/m²), infertility history, menopausal status and history of gestational diabetes mellitus (GDM; restricted to parous women).

RESULTS

We saw no association between laparoscopically confirmed endometriosis and risk of type 2 diabetes in multivariable confounder-adjusted models (HR 1.06 [95% CI 0.98, 1.13]) or models accounting for potential mediating factors (HR 0.94 [95% CI 0.87, 1.00]). However, we observed modest differences in the association between endometriosis and type 2 diabetes by BMI group, history of infertility and history of GDM. Among non-obese women (HR 1.17 [95% CI 1.02, 1.35]), women who never experienced infertility (HR 1.14 [95% CI 1.04, 1.25]) and women who never experienced GDM (HR 1.11 [95% CI 1.01, 1.22]), endometriosis was associated with greater risk of type 2 diabetes.

CONCLUSIONS/INTERPRETATION

Overall, women with endometriosis were not at increased risk of type 2 diabetes. However, among subgroups at low risk for type 2 diabetes (i.e. non-obese women and women with no prior history of infertility or GDM), endometriosis was associated with a modest increased risk of type 2 diabetes.

The influence of gestational hypertension on cord blood adiponectin levels: a case-controlled study

INTRODUCTION

Gestational hypertension is one of the most common complications of pregnancy and childbirth worldwide and may be associated with metabolic disorders. Adiponectin is an adipocyte-specific plasma protein with insulin-sensitizing, vascular-protective, anti-inflammatory properties, and its role in metabolic disorders in prenatal and postnatal development in neonates remains unclear. The primary purpose of this study was to determine whether gestational hypertension is a condition lowering cord blood adiponectin level. Next, we have evaluated whether cord blood adiponectin level correlates with selected anthropometric parameters in neonates.

MATERIAL AND METHODS

The case-control study included 89 newborns divided into two groups: 30 neonates in the study group whose mothers were diagnosed with gestational hypertension and 59 healthy neonates born from normotensive pregnancies. Adiponectin determinations were performed in both groups, and neonatal anthropometric measurements and perinatal data were collected.

RESULTS

There was no statistically significant difference (p = 0.27) between adiponectin concentration in cord blood of newborns from the study group [median (Q1-Q3) 9.86 μg/ml (8.16-13.26 μg/ml)] compared with the control group [median (Q1-Q3) 10.65 μg/ml (8.69-14.29 μg/ml)]. No statistically significant correlations were observed between adiponectin level and gestational age, body weight, body length, and chest circumference. A significant correlation was observed between adiponectin level and head circumference among newborns in the control group and among the entire population of newborns included in the study.

CONCLUSION

No significant influence of gestational hypertension on cord blood adiponectin levels or their correlation with neonatal anthropometric measurements was observed.

Role of Adiponectin in Cervical Cancer

BACKGROUND

Cervical Cancer (CC) is the most common leading cancer in women globally. This is considered to be the type of cancer that is restricted to women. Any women in the reproductive age range can develop CC. However, women between the ages of 25 and 39 are at a higher risk.

OBJECTIVE

In comparison with developed countries, the screening and awareness of CC in developing countries are significantly low. Infection with Human papillomavirus (HPV) is the main cause of CC, especially HPV-16 and HPV-18. Other than HPV, there are other factors that can contribute to CC, such as Human simplex virus (HSV) infection and immunocompromised patients with HIV.

CONCLUSION

Cervical cancer can be detected by molecular techniques such as (1) PCR, (2) visual acetic acid method, (3) DNA Hybrid II test, (4) liquid-based cytology, (5) Pap-Smear techniques, and (6) colposcopy techniques. Early detection of CC is very much needed; cryotherapy or LEEP (Loop electro surgical excision procedure) can be conducted during the pre-invasive stage of CC. Some metabolic changes in the human body such as fluctuating levels of insulin and triglycerides and increased activity of adiponectin may lead to CC. These contributing factors, such as adipokines, can be used as biomarkers for CC detection.

Modulation of adiponectin system expression in the porcine uterus during early pregnancy by prostaglandin E2 and F2α

Studies have demonstrated that adiponectin could be a link between reproductive functions and energy metabolism in animals. The aim of the present study was to investigate the effects of prostaglandin (PG) E₂ and PGF_2α (10, 50, 100, 250 and 500ngmL^-1) on the expression and secretion of adiponectin and its receptor genes and proteins by cultured in vitro porcine endometrial and myometrial tissues on Days 10-28 of pregnancy and Days 10-11 of the oestrous cycle. The gene expression was analysed using the real-time PCR method. Adiponectin protein secretion was determined by ELISA, whereas the receptors proteins content was defined using Western Blot analysis. Both PGE₂ and PGF_2α modulated the expression of adiponectin system genes and proteins in the uterus during early pregnancy. PGE₂ and PGF_2α had similar effects on the adiponectin system, which differed between the stages of gestation and between pregnancy and the oestrous cycle. On Days 10-11 of gestation, PGE₂ and PGF_2α generally increased adiponectin secretion by endometrial and myometrial tissues. Both PGs decreased levels of endometrial adiponectin receptor type 1 (AdipoR1), whereas only PGF_2α decreased myometrial levels of AdipoR1. Both PGs increased myometrial adiponectin receptor type 2 (AdipoR2) levels. On Days 12-13 of gestation, PGE₂ decreased AdipoR1 concentrations in both tissues and AdipoR2 levels in the endometrium. PGF_2α decreased myometrial concentrations of both receptors. On Days 15-16 of gestation, both PGE₂ and PGF_2α increased concentrations of AdipoR1 and AdipoR2 in the endometrium and myometrium. PGE₂ stimulated the secretion of adiponectin in the endometrium, but not in the myometrium. On Days 27-28 of pregnancy, both PGE₂ and PGF_2α inhibited the expression of AdipoR1 and AdipoR2 in endometrial and myometrial tissues and decreased the secretion of endometrial adiponectin. Both PGE₂ and PGF_2α had tissue-specific and dose-dependent effects on the adiponectin system.

Expression and Role of Peptides, Proteins and Growth Factors in the Pathogenesis of Endometriosis

Growing evidence is demonstrating that several peptides (corticotrophin-releasing factor, urocortins, ghrelin), proteins (leptin, adiponectin) and growth factors (vascular endothelial growth factor; epidermal growth factor family of growth factors and receptors, fibroblast growth factor, insulin like growth factor and insulin like growth factor-binding proteins, transforming growth factor-β and, activin A and related proteins) are expressed in endometriotic implants, and locally play a relevant role in affecting the biological mechanisms leading to endometriosis. They establish a complex network of interactions by which they are therefore able to stimulate angiogenesis, inflammatory cell recruitment and reaction, the growth of endometriotic tissue and its survival through the modulation of the narrow immune system. This review will evaluate the role played by several regulatory peptides, proteins and growth factors in affecting endometrial physiology and the putative mechanisms advocated to explain endometriosis (angiogenesis, cellular and humoral immunity, inflammatory response, endometrial cell proliferation, activation, motility, adhesion and invasion).

Adiponectin: A New Regulator of Female Reproductive System

Adiponectin is the hormone that belongs to the group of adipokines, chemical agents mainly derived from the white adipose tissue. The hormone plays pleiotropic roles in the organism, but the most important function of adiponectin is the control of energy metabolism. The presence of adiponectin and its receptors in the structures responsible for the regulation of female reproductive functions, such as hypothalamic-pituitary-gonadal (HPG) axis, indicates that adiponectin may be involved in the female fertility regulation. The growing body of evidence suggests also that adiponectin action is dependent on the actual and hormonal status of the animal. Present study presents the current knowledge about the presence and role of adiponectin system (adiponectin and its receptors: AdipoR1 and AdipoR2) in the ovaries, oviduct, and uterus, as well as in the hypothalamus and pituitary, the higher branches of HPG axis, involved in the female fertility regulation.

A critical role for adiponectin-mediated development of endometrial luminal epithelial cells during the peri-implantation period of pregnancy

Adiponectin is one of the adipokines in the collagen superfamily. It is secreted primarily by white adipocytes and influences reproductive processes including ovarian and uterine functions. Adiponectin regulates energy homeostasis, insulin sensitivity, and is anti-inflammatory in various tissues. Its receptors (ADIPOR1 and ADIPOR2) are widely expressed in mammalian tissues, including porcine conceptuses and endometrial during the estrous cycle and peri-implantation period of pregnancy. However, regulatory effects of adiponectin on endometrial epithelial cells are unknown. Therefore, we investigated the effects of parity on expression of ADIPOR1 and ADIPOR2 and the effects of adiponectin in the porcine endometrium during early pregnancy. Results of this study revealed robust expression of ADIPOR1 and ADIPOR2 in uterine luminal (LE) and glandular (GE) epithelia during early pregnancy and expression decreased as with increasing parity. For porcine luminal epithelial (pLE) cells, adiponectin enhanced proliferation, and increased phosphorylation of AKT, P70S6K, S6, ERK1/2, JNK, P38, and P90RSK in a time-dependent manner. Moreover, the abundance of adiponectin-activated signaling molecules were suppressed by pharmacological inhibitors including wortmannin, U0126, SP600125, and SB203580, respectively, in pLE cells. Furthermore, inhibition of each targeted signal transduction molecule influenced proliferation of adiponectin-stimulated pLE cells. In addition, adiponectin inhibited tunicamycin-induced endoplasmic reticulum (ER)-stress through effects on ER stress regulated proteins in pLE cells. Collectively, these results suggest that adiponectin affects development of porcine uterine epithelia and reproductive performance through modulation of PI3K/AKT and MAPK cell signaling pathways.

Adiponectin, orexin A and orexin B concentrations in the serum and uterine luminal fluid during early pregnancy of pigs

Adiponectin is the most abundant adipose-released protein that circulates in human plasma at high concentrations. The neuropeptides orexin A (OXA, hypocretin-1) and orexin B (OXB, hypocretin-2) are derived from a common precursor peptide, prepro-orexin and are produced mainly by neurons located in the lateral hypothalamus. It has been demonstrated that the peptides such as adiponectin and orexins have an important role in the regulation of energy metabolism and neuroendocrine functions. These hormones appear to be implicated in both normal and disturbed pregnancy. The objectives of this study were to determine adiponectin and orexin concentrations in the plasma and uterine luminal fluid (ULF) of pigs during early gestation and to explore the relationships between hormone concentrations and stages of pregnancy. The greatest plasma concentrations of adiponectin were observed on days 15-16 and 27-28 of pregnancy, and the least concentrations were on days 30-32 of gestation and on days 10-11 of the oestrous cycle. In ULF, adiponectin concentrations were greater on days 15-16 of pregnancy and on days 10-11 of the oestrous cycle than on days 10-11 and days 12-13 of pregnancy. The greatest OXA concentrations in the blood plasma were noted on days 10-16 of gestation, and the least OXA concentrations were on days 27-32 of pregnancy and on days 10-11 of the oestrous cycle. Orexin A concentrations in ULF were greater on days 10-11 of the cycle than throughout pregnancy. Serum OXB concentrations were greatest on days 10-11 and 30-32 of pregnancy, and least on days 12-28 of gestation. The greatest OXB concentrations in ULF were on days 10-13 of gestation, and the least OXB concentrations were on days 15-16 of pregnancy. This is first study to demonstrate the presence of adiponectin and orexins in the serum and ULF during early pregnancy of pigs as well as the relationships between adiponectin and orexin concentrations and the stage of pregnancy. The fluctuations in adiponectin and orexin concentrations in the plasma and ULF suggest that the hormones present in ULF are mostly of local origin and that these hormones participate in the processes that accompany early pregnancy.

The roles of leptin and adiponectin at the fetal-maternal interface in humans

Infertility now affects one in seven couples, and the prevalence of this condition continues to increase. Ovulatory defects and unknown causes account for more than half of the cases of infertility. It has been postulated that a significant proportion of these cases are directly or indirectly related to obesity, since the presence of excess adipose tissue has a variety of effects on reproductive function. Here, we review on the effects of the two major adipokines (leptin and adiponectin) on fertility, with a focus on the first steps in embryo implantation and the key components of fetal-maternal interface (the placenta and the endometrium). These adipokines are reportedly involved in the regulation of cell proliferation and differentiation, and as such affect local angiogenesis, immune tolerance and inflammatory processes in placental and endometrial tissues. In placental cells, leptin and adiponectin also modulate trophoblast invasiveness and the nutrient supply. These observations strongly suggest by interfering with the placenta and endometrium, adipokines can create a favorable environment for embryo implantation and have a key role in fetal-maternal metabolism, fetal-maternal communication, and gestation. Given that reproductive functions are tightly coupled to the energy balance, metabolic abnormalities may lead to the development of complications of pregnancy and changes in fetal growth. In this context, we suggest that the leptin/adiponectin ratio may be a clinically valuable marker for detecting a number of pathologies in pregnancy.

Blood biomarkers for the non-invasive diagnosis of endometriosis

BACKGROUND

About 10% of reproductive-aged women suffer from endometriosis, a costly chronic disease causing pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but is expensive and carries surgical risks. Currently, there are no non-invasive or minimally invasive tests available in clinical practice to accurately diagnose endometriosis. Although other reviews have assessed the ability of blood tests to diagnose endometriosis, this is the first review to use Cochrane methods, providing an update on the rapidly expanding literature in this field.

OBJECTIVES

To evaluate blood biomarkers as replacement tests for diagnostic surgery and as triage tests to inform decisions on surgery for endometriosis. Specific objectives include:1. To provide summary estimates of the diagnostic accuracy of blood biomarkers for the diagnosis of peritoneal, ovarian and deep infiltrating pelvic endometriosis, compared to surgical diagnosis as a reference standard.2. To assess the diagnostic utility of biomarkers that could differentiate ovarian endometrioma from other ovarian masses.

SEARCH METHODS

We did not restrict the searches to particular study designs, language or publication dates. We searched CENTRAL to July 2015, MEDLINE and EMBASE to May 2015, as well as these databases to 20 April 2015: CINAHL, PsycINFO, Web of Science, LILACS, OAIster, TRIP, ClinicalTrials.gov, DARE and PubMed.

SELECTION CRITERIA

We considered published, peer-reviewed, randomised controlled or cross-sectional studies of any size, including prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE). We included studies comparing the diagnostic test accuracy of one or more blood biomarkers with the findings of surgical visualisation of endometriotic lesions.

DATA COLLECTION AND ANALYSIS

Two authors independently collected and performed a quality assessment of data from each study. For each diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis, and we calculated sensitivity and specificity estimates. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient datasets were available. The predetermined criteria for a clinically useful blood test to replace diagnostic surgery were a sensitivity of 0.94 and a specificity of 0.79 to detect endometriosis. We set the criteria for triage tests at a sensitivity of ≥ 0.95 and a specificity of ≥ 0.50, which 'rules out' the diagnosis with high accuracy if there is a negative test result (SnOUT test), or a sensitivity of ≥ 0.50 and a specificity of ≥ 0.95, which 'rules in' the diagnosis with high accuracy if there is a positive result (SpIN test).

MAIN RESULTS

We included 141 studies that involved 15,141 participants and evaluated 122 blood biomarkers. All the studies were of poor methodological quality. Studies evaluated the blood biomarkers either in a specific phase of the menstrual cycle or irrespective of the cycle phase, and they tested for them in serum, plasma or whole blood. Included women were a selected population with a high frequency of endometriosis (10% to 85%), in which surgery was indicated for endometriosis, infertility work-up or ovarian mass. Seventy studies evaluated the diagnostic performance of 47 blood biomarkers for endometriosis (44 single-marker tests and 30 combined tests of two to six blood biomarkers). These were angiogenesis/growth factors, apoptosis markers, cell adhesion molecules, high-throughput markers, hormonal markers, immune system/inflammatory markers, oxidative stress markers, microRNAs, tumour markers and other proteins. Most of these biomarkers were assessed in small individual studies, often using different cut-off thresholds, and we could only perform meta-analyses on the data sets for anti-endometrial antibodies, interleukin-6 (IL-6), cancer antigen-19.9 (CA-19.9) and CA-125. Diagnostic estimates varied significantly between studies for each of these biomarkers, and CA-125 was the only marker with sufficient data to reliably assess sources of heterogeneity.The mean sensitivities and specificities of anti-endometrial antibodies (4 studies, 759 women) were 0.81 (95% confidence interval (CI) 0.76 to 0.87) and 0.75 (95% CI 0.46 to 1.00). For IL-6, with a cut-off value of > 1.90 to 2.00 pg/ml (3 studies, 309 women), sensitivity was 0.63 (95% CI 0.52 to 0.75) and specificity was 0.69 (95% CI 0.57 to 0.82). For CA-19.9, with a cut-off value of > 37.0 IU/ml (3 studies, 330 women), sensitivity was 0.36 (95% CI 0.26 to 0.45) and specificity was 0.87 (95% CI 0.75 to 0.99).Studies assessed CA-125 at different thresholds, demonstrating the following mean sensitivities and specificities: for cut-off > 10.0 to 14.7 U/ml: 0.70 (95% CI 0.63 to 0.77) and 0.64 (95% CI 0.47 to 0.82); for cut-off > 16.0 to 17.6 U/ml: 0.56 (95% CI 0.24, 0.88) and 0.91 (95% CI 0.75, 1.00); for cut-off > 20.0 U/ml: 0.67 (95% CI 0.50 to 0.85) and 0.69 (95% CI 0.58 to 0.80); for cut-off > 25.0 to 26.0 U/ml: 0.73 (95% CI 0.67 to 0.79) and 0.70 (95% CI 0.63 to 0.77); for cut-off > 30.0 to 33.0 U/ml: 0.62 (95% CI 0.45 to 0.79) and 0.76 (95% CI 0.53 to 1.00); and for cut-off > 35.0 to 36.0 U/ml: 0.40 (95% CI 0.32 to 0.49) and 0.91 (95% CI 0.88 to 0.94).We could not statistically evaluate other biomarkers meaningfully, including biomarkers that were assessed for their ability to differentiate endometrioma from other benign ovarian cysts.Eighty-two studies evaluated 97 biomarkers that did not differentiate women with endometriosis from disease-free controls. Of these, 22 biomarkers demonstrated conflicting results, with some studies showing differential expression and others no evidence of a difference between the endometriosis and control groups.

AUTHORS' CONCLUSIONS

Of the biomarkers that were subjected to meta-analysis, none consistently met the criteria for a replacement or triage diagnostic test. A subset of blood biomarkers could prove useful either for detecting pelvic endometriosis or for differentiating ovarian endometrioma from other benign ovarian masses, but there was insufficient evidence to draw meaningful conclusions. Overall, none of the biomarkers displayed enough accuracy to be used clinically outside a research setting. We also identified blood biomarkers that demonstrated no diagnostic value in endometriosis and recommend focusing research resources on evaluating other more clinically useful biomarkers.

The role of adiponectin in obesity-associated female-specific carcinogenesis

Adipose tissue is a highly vascularized endocrine organ, and its secretion profiles may vary with obesity. Adiponectin is secreted by adipocytes that make up adipose tissue. Worldwide, obesity has been designated a serious health problem among women and is associated with a variety of metabolic disorders and an increased risk of developing cancer of the cervix, ovaries, uterus (uterine/endometrial), and breast. In this review, the potential link between obesity and female-specific malignancies is comprehensively presented by discussing significant features of the intriguing and complex molecule, adiponectin, with a focus on recent findings highlighting its molecular mechanism of action in female-specific carcinogenesis.

in vitro Anti-Proliferative Effect of Adiponectin on Human Endometriotic Stromal Cells through AdipoR1 and AdipoR2 Gene Receptor Expression

BACKGROUND

Endometriosis is a complex disorder in reproductive age women which consist of stromal and epithelial cells implantation outside the uterine cavity. Adiponectin is a member of cytokine family with various metabolic roles and proliferation inhibition of many cancer cells. The aim of the present research was to determine adiponectin effect on human endometriotic stromal cells (ESCs) proliferation and their expression of adiponectin receptors.

METHODS

In this experimental study, endometrial biopsies (n=7) were taken. ESCs isolation was done by enzymatic digestion and cell filtrations. ESCs of each biopsy were divided into four groups: 0 (control), 10, 100, and 200 ng/ml adiponectin concentrations in three different times (24, 48 or 72 h). The effect of adiponectin on ESC viability and expression of mRNA Adipo receptor1 (R1) and Adipo receptor2 (R2) was determined by Trypan blue staining and semi-quantitative RT-PCR, respectively. Data were analyzed by one-way ANOVA and unpaired student's t-test, and P<0.05 was considered statistically significant.

RESULTS

Adiponectin inhibited human endometriotic stromal cell proliferation in time- and dose-dependent manners significantly (P=0.001). Expression of AdipoR1 and AdipoR2 gene receptors was increased in human ESCs significantly (P<0.05).

CONCLUSIONS

Adiponectin can suppress endometriosis by inhibiting ESC proliferation and increased AdipoR1 and AdipoR2 expression.

Metformin Suppresses Prostaglandin E2-Induced Cytochrome P450 Aromatase Gene Expression and Activity via Stimulation of AMP-Activated Protein Kinase in Human Endometriotic Stromal Cells

BACKGROUND

Cytochrome P450 aromatase (encoded by the CYP19A1/aromatase gene) plays a critical physiologic role in endometriosis. Metformin is known to suppress prostaglandin E2 (PGE2)-induced CYP19A1 messenger RNA (mRNA) expression in human endometriotic stromal cells (ESCs). However, the possible mechanism behind this suppression remains to be determined.

METHODS

In this study, ESCs were cultured with metformin, PGE2, and adenosine monophosphate (AMP)-activated protein kinase (AMPK) inhibitors. Expression of CYP19A1 mRNA and aromatase activity were measured by quantitative polymerase chain reaction and aromatase activity assay, respectively. The binding of the cyclic AMP response element-binding (CREB) protein to CYP19A1 promoter II (PII) was assessed by chromatin immunoprecipitation assay.

RESULTS

We demonstrated that metformin downregulated the expression of aromatase mRNA (32%) and activity (25%) stimulated by PGE2 (4.18-fold and 2.14-fold) in ESCs via stimulation of AMPK. Following PGE2 treatment, there was a marked increase in CREB binding to aromatase PII, while metformin attenuated the above-mentioned stimulation by 67%.

CONCLUSION

Metformin could inhibit PGE2-induced CYP19A1 mRNA expression and aromatase activity via AMPK activation and inhibition of CREB to CYP19A1 PII in human ESCs. The results of the present study suggest that metformin may have unique therapeutic potential as an antiendometriotic drug in the future.

Expression of adiponectin and adiponectin receptors 1 and 2 in the porcine uterus, conceptus, and trophoblast during early pregnancy

Adiponectin, one of the several adipocytokines secreted mainly by the adipose tissue, plays an important role in regulating energy homeostasis and controls female fertility. Female reproductive functions are closely associated with nutritional status, and adiponectin seems to be an important factor linking the regulation of metabolic homeostasis with reproductive processes. The biological activity of adiponectin is mediated by two distinct receptors, adiponectin receptor 1 (AdipoR1) and adiponectin receptor 2 (AdipoR2). The objective of this study was to determine the presence of and changes in the gene and protein expression pattern of adiponectin and its receptors in the porcine uterus during early pregnancy and on Days 10 to 11 of the estrous cycle and in the conceptus and trophoblast. The highest level of adiponectin transcript was observed on Days 15 to 16 of gestation, Days 10 to 11 of the cycle in the endometrium, and Days 15 to 16 of gestation in the myometrium. The highest expression of AdipoR1 and AdipoR2 genes was detected on Days 10 to 11 of gestation in the endometrium, and Days 12 to 13 in the myometrium. The highest content of adiponectin protein was noted on Days 12 to 13 and 30 to 32 of gestation in the endometrium and Days 10 to 11 of the cycle in the myometrium. The expression of adiponectin protein was higher on Days 27 to 28 and 30 to 32 in the conceptuses. AdipoR1 protein content in the myometrium was highest on Days 12 to 13 and 30 to 32. In contrast, in the endometrium, it was more constant. The highest content of AdipoR2 protein was detected on Days 15 to 16 and 30 to 32 of gestation, Days 10 to 11 of the cycle in the endometrium, and Days 10 to 11 of gestation in the myometrium. In the conceptuses, the highest AdipoR1 protein content was observed on Days 15 to 16, and the highest AdipoR2 protein expression was determined on Days 15 to 16 and 27 to 28. In the trophoblasts, AdipoR1 protein content was higher on Days 27 to 28 than on Days 30 to 32, whereas the expression of AdipoR2 was higher on Days 30 to 32. This study demonstrated the presence of adiponectin and its receptors in the uteri, conceptuses, and trophoblasts of pregnant pigs and that the local adiponectin system is dependent on the stage of pregnancy.

Insulin and leptin levels in obese patients with and without breast cancer

BACKGROUND

Leptin has been associated with progression and poor survival in BC. Moreover, it is still controversial as to whether the effect of leptin depends only on its correlation with body mass index (BMI), or could be a direct role of adipokine in the development of BC. The aim of this study was to identify if there was a difference between serum leptin levels and insulin in obese patients with and without BC.

PATIENTS AND METHODS

A cross-sectional study was made in 156 women, a group of 78 with obesity and BC and 78 with obesity without BC. When subjects agreed to participate, written informed consent was obtained from all subjects. Biochemical variables such as glucose, triglycerides, high-density and low-density lipoprotein, cholesterol, insulin, and leptin were measured and homeostasis model assessment (HOMA-IR) was calculated.

RESULTS

The age, number of parities, glucose, HOMA-IR, and leptin were significantly different at P < .05.

CONCLUSION

Serum leptin levels and leptin/BMI ratio were statistically significantly increased in patients with BC.

Expression of adiponectin, leptin, and their receptors in ovarian endometrioma

OBJECTIVE

To evaluate the expression of leptin, leptin receptor (ObR), adiponectin, and adiponectin receptor (AdipoR) in ovarian endometriomas compared with normal endometrium, and to analyze relationships among adipokines and their receptors.

DESIGN

Experimental study.

SETTING

A clinic for the treatment of endometriosis and basic research laboratories.

PATIENT(S)

Forty-four women with endometriosis and 42 age-matched women with no laparoscopic evidence of endometriosis as control subjects.

INTERVENTION(S)

Endometrial tissue samples were obtained during laparoscopic surgery.

MAIN OUTCOME MEASURE(S)

Immunohistochemical staining for leptin, ObR, adiponectin, and AdipoR was performed with the use of tissue microarray. Clinical characteristics were reviewed from the patient's medical records. The effect of leptin on the expression of adiponectin was evaluated in endometriotic cell line using real-time reverse-transcription polymerase chain reaction.

RESULT(S)

Positive expression rates of leptin and ObR were significantly higher in ovarian endometrioma compared with normal endometrium, but those of adiponectin and AdipoR were similar (ovarian endometrioma vs. normal endometrium, respectively: leptin 100% vs. 59.5%; ObR 72.7% vs. 33.3%; adiponectin 31.8% vs. 42.9%; AdipoR 88.6% vs. 73.8%). Expression of adipokines and their receptors did not show any correlation with disease stage. A positive correlation was found between expression of ObR and adiponectin (correlation coefficient 0.488; P=.001). Leptin treatment in endometriotic cells induced mRNA expression of adiponectin.

CONCLUSION(S)

These data suggest that leptin and its receptor are induced in ovarian endometriomas, and that the leptin/ObR system regulates adiponectin gene expression in endometriotic cells.

Plasma adipokines and endometriosis risk: a prospective nested case-control investigation from the Nurses' Health Study II

STUDY QUESTION

Do higher leptin levels and lower adiponectin levels predict subsequent development of endometriosis?

SUMMARY ANSWER

Plasma leptin and adiponectin levels were not associated with laparoscopically confirmed endometriosis when collected prior to disease diagnosis.

WHAT IS KNOWN ALREADY

Case-control studies have identified altered levels of the inflammatory adipokines leptin and adiponectin in women with endometriosis, but it remains unclear whether inflammation results in endometriosis or whether the presence of endometriosis creates an inflammatory state.

STUDY DESIGN, SIZE, DURATION

Nested, matched, case-control study within the prospective Nurses' Health Study II (NHS II) cohort. Blood samples were collected between 1996 and 1999 from 29 611 female nurses within the cohort. Women who reported endometriosis before blood collection were excluded.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Plasma leptin and adiponectin levels were assayed by ELISA. Three hundred and fifty cases of laparoscopically confirmed endometriosis were matched 1:2 with 694 controls of comparable race, age, infertility history, menopausal status and time of blood draw. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression models adjusting for matching factors and BMI.

MAIN RESULTS AND THE ROLE OF CHANCE

After adjusting for BMI, there were no statistically significant associations between endometriosis and leptin [RR = 1.2; 95% CI = 0.7-2.0; P-value, test for linear trend (P(trend)) = 0.72], adiponectin (RR = 0.8; 95% CI = 0.5-1.2; P(trend) = 0.48) or the leptin to adiponectin ratio (RR = 0.8; 95% CI = 0.4-1.4; P(trend) = 0.14) when comparing the upper with the lower quartile. Results were unaltered when analyses were stratified by BMI or restricted to cases diagnosed ≥ 4 years after blood draw. To evaluate statistical significance and limit the role of chance to the gold standard of 5%, we present 95% CIs about the RRs, and for P-values calculated for linear tests of trend and tests of heterogeneity, we have set the α-level to be 0.05 (i.e. <0.05 is considered to be statistically significant).

LIMITATIONS AND REASONS FOR CAUTION

A limitation of this study is the inability to differentiate the time of endometriosis 'diagnosis' from the time of disease 'onset' due to the impossibility in identifying a precise time point at which the disease process was first initiated at a molecular or cellular level. Additional limitations include lack of information regarding stage of endometriosis and the possibility of asymptomatic disease in the control population.

WIDER IMPLICATIONS OF THE FINDINGS

The mean age at diagnosis of endometriosis in the study population is 41.7, ≈ 10 years older than the mean age of diagnosis in the general population. While this may limit the generalizability of the results, there is no reason to suspect that the association between adipokines and endometriosis risk should differ at a younger age of diagnosis in an adult population.

Adiponectin and its receptors in preimplantation embryo development

Adiponectin can play an important role in regulating the female reproductive function and embryo development and can affect the embryo at very early stages of pregnancy--during the preimplantation period. Disturbances in the maternal adiponectin system are associated with several diseases, including diabetes type 2, obesity, and some female reproductive disorders. Adiponectin receptors are expressed in oocytes and preimplantation embryos and can be activated by adiponectin produced by maternal adipose tissue or organs of the female reproductive tract. Adiponectin can affect proliferation and survival of cells in preimplantation embryos, and these effects are isoform dependent. Experimental results suggest involvement of various protein kinases, including mitogen-activated protein kinases, in the regulation of these processes by adiponectin. Actions of adiponectin on lipid and glucose metabolism can increase the energy supply to the embryo, and final targets of adiponectin signaling are metabolic enzymes, glucose transporters, and fatty acid transporters. The involvement of several signaling molecules, such as AMPK/PRKA, PI3K, or AKT/PKB, in the regulation of metabolic processes by adiponectin has been demonstrated in preimplantation embryos. In summary, adiponectin produced in an endocrine/paracrine/autocrine manner can significantly influence preimplantation embryo development, uterine receptivity, and embryo implantation.

Adiponectin and adiponectin receptors in the mouse preimplantation embryo and uterus

BACKGROUND

Adiponectin (Adipoq), a protein secreted by adipocytes in inverse proportion to the adipose mass present, modulates energy homeostasis and increases insulin sensitivity. Tissue Adipoq signaling decreases in settings of maternal diabetes, polycystic ovary syndrome (PCOS) and endometriosis, conditions which are associated with reproductive difficulty. Our objective was to define the expression and hormonal regulation of Adipoq and its receptors in the mouse preimplantation embryo and uterus.

METHODS AND RESULTS

By real-time quantitative PCR, mRNA transcripts for Adipoq, AdipoR1, AdipoR2, Ppara, Ppard, FATP1 (SLC27A1) and acyl CoA oxidase (Acox1) were identified in mouse 2-cell and 8-cell embryos, while blastocyst stage embryos and trophoblast stem (TS) cells expressed mRNA for all genes except Adipoq. Protein expression of Adipoq, AdipoR1, AdipoR2, the insulin sensitive transporters GLUT8 (Slc2A8), GLUT12 (Slc2A12) and p-PRKAA1 was identified by immunofluorescence staining in all stages of preimplantation embryos including the blastocyst. In situ hybridization demonstrated the presence of Adipoq, AdipoR1 and AdipoR2 mRNA in the mouse decidual cells of the implantation site and in artificially decidualized cells, and the expression of these proteins was confirmed by western blotting. Flow cytometry confirmed cell surface expression of AdipoR1 and AdipoR2 in TS cells and decidual cells.

CONCLUSIONS

These results suggest for the first time that Adipoq signaling may play an important role in preimplantation embryo development and uterine receptivity by autocrine and paracrine methods in the mouse. Implantation failures and pregnancy loss, specifically those experienced in women with maternal metabolic conditions such as diabetes, obesity and PCOS, may be the result of aberrant Adipoq and AdipoR1 and AdipoR2 expression and suboptimal decidualization in the uterus.

Peripheral biomarkers of endometriosis: a systematic review

BACKGROUND

Endometriosis is estimated to affect 1 in 10 women during the reproductive years. There is often delay in making the diagnosis, mainly due to the non-specific nature of the associated symptoms and the need to verify the disease surgically. A biomarker that is simple to measure could help clinicians to diagnose (or at least exclude) endometriosis; it might also allow the effects of treatment to be monitored. If effective, such a marker or panel of markers could prevent unnecessary diagnostic procedures and/or recognize treatment failure at an early stage.

METHODS

We used QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria to perform a systematic review of the literature over the last 25 years to assess critically the clinical value of all proposed biomarkers for endometriosis in serum, plasma and urine.

RESULTS

We identified over 100 putative biomarkers in publications that met the selection criteria. We were unable to identify a single biomarker or panel of biomarkers that have unequivocally been shown to be clinically useful.

CONCLUSIONS

Peripheral biomarkers show promise as diagnostic aids, but further research is necessary before they can be recommended in routine clinical care. Panels of markers may allow increased sensitivity and specificity of any diagnostic test.

Peritoneal fluid leptin levels are increased but adiponectin levels are not changed in infertile patients with pelvic endometriosis

OBJECTIVE

Endometriosis is a leading cause of infertility, and recent studies suggest that leptin and adiponectin may have a role in its causation and progression. This study assessed levels of leptin and adiponectin in serum and peritoneal fluid (PF) in patients with endometriosis and infertility.

DESIGN AND SETTING

This cross-sectional study included women undergoing diagnostic and/or therapeutic laparoscopy for endometriosis with chief complaint of infertility. Following laparoscopy, patients diagnosed with endometriosis served as cases while patients with no endometriosis served as controls. Patients with polycystic ovarian syndrome, diabetes, thyroiditis and patients on prior therapy with danazol or leuprolide were excluded from the study. Leptin and adiponectin levels were analysed in blood and PF using commercially available ELISA kits.

RESULTS

Of the 50 patients (aged 22-41 years), 15 had endometriosis (cases) while 35 had no endometriosis (controls). The median PF leptin level was significantly higher in cases as compared to controls (27.7 vs. 15.6 ng/ml, p = 0.019), and this remained significant even when PF leptin was BMI-normalised (p = 0.004). However, median serum leptin and adiponectin levels remained comparable between the two groups.

CONCLUSIONS

This study confirmed the role of PF leptin in causation and progression of endometriosis. However, this would have been definitive if healthy fertile females were included in this study.

The role of adiponectin in reproduction: from polycystic ovary syndrome to assisted reproduction

OBJECTIVE

To summarize the effects of the adipokine adiponectin on the reproductive endocrine system, from the hypothalamic-pituitary axis to the gonads and target tissues of the reproductive system.

DESIGN

A Medline computer search was performed to identify relevant articles.

SETTING

Research institution.

INTERVENTION(S)

None.

RESULT(S)

Adiponectin is a hormone secreted by adipose tissue that acts to reduce insulin resistance and atherogenic damage, but it also exerts actions in other tissues. Adiponectin mediates its actions in the periphery mainly via two receptors, AdipoR1 and AdipoR2. Adiponectin receptors are present in many reproductive tissues, including the central nervous system, ovaries, oviduct, endometrium, and testes. Adiponectin influences gonadotropin release, normal pregnancy, and assisted reproduction outcomes.

CONCLUSION(S)

Adiponectin, a beneficial adipokine, represents a major link between obesity and reproduction. Higher levels of adiponectin are associated with improved menstrual function and better outcomes in assisted reproductive cycles.

Expression of adiponectin receptors and effects of adiponectin isoforms in mouse preimplantation embryos

BACKGROUND

Adiponectin, a pleiotropic hormone secreted from adipose tissue, can mediate some negative effects of obesity on female health, and can participate in the impaired reproductive performance of obese women. Using a mouse model, we investigated expression of adiponectin receptors in ovulated oocytes and in vivo derived preimplantation embryos, and tested effects of different adiponectin isoforms on development of preimplantation embryos in vitro.

METHODS AND RESULTS

Using RT-PCR and immunohistochemistry, we found expression of adiponectin receptors AdipoR1 and AdipoR2, at the mRNA and protein level, in mouse ovulated oocytes and preimplantation embryos. Quantitative real-time RT-PCR analysis showed a decrease in the amount of AdipoR1 and AdipoR2 mRNA after fertilization, which was followed by an increase in mRNA at the morula and blastocyst stage; mRNA for adiponectin was detected only at the blastocyst stage. Administration of full-length adiponectin significantly changed the distribution in numbers of cells of cultured preimplantation embryos, increasing the proportion of embryos with high cell numbers (>128 cells) and decreasing the proportion of embryos with lower cell numbers (<65 cells). Blastocysts possessed significantly higher cell numbers after full-length adiponectin treatment. Mutated trimeric adiponectin had the opposite effect, a significant decrease in the proportion of embryos with higher cell numbers (>96 cells) and increase in the proportion of embryos with lower cell numbers (<65 cells). Trimeric adiponectin also significantly decreased the cell number and increased cell death in blastocysts. Truncated globular adiponectin had no significant effect on development of mouse preimplantation embryos.

CONCLUSIONS

Our results indicate that adiponectin can directly influence the development of the preimplantation embryo, and the effects are isoform dependent.

Adipokine concentrations in nonobese women: a study of reproductive aging, body mass index, and menstrual cycle effects

OBJECTIVE

To explore the influence of reproductive aging, body mass index (BMI), and the menstrual cycle on adiponectin (AD) and leptin concentrations.

DESIGN

Cross-sectional comparison in age- and BMI-matched nonobese volunteers with regular cycles (CO, n = 19) or in early postmenopause (EPM, n = 19), aged 40-52 years, and a young cycling group (CY, n = 21), aged 20-30 years.

MEASURES

Sex steroids, fasting AD, leptin, insulin, glucose, AD/leptin (A/L) ratio, and insulin resistance (IR) by homeostasis model assessment (HOMA-IR). In ovulatory women, AD, estradiol (E(2)), and progesterone were assessed weekly across the same menstrual cycle.

RESULTS

Insulin, glucose, HOMA-IR, A/L ratio, and leptin values were similar across the three study groups. AD differed, with the highest concentrations in the EPM group (CY: 13.0 +/- 0.9 microg/ml vs. CO: 14.0 +/- 1.1 microg/ml vs. EPM: 17.7 +/- 1.5 microg/ml; p = .05). Values among cycling women were similar. When the cycling groups were combined into a premenopausal (PRE) group and compared to EPM women by BMI (> or

CONCLUSION

Nonobese, midlife women experience minimal adverse effects from reproductive aging on insulin sensitivity and adipokine secretion. The menstrual cycle is not a key mediator of AD. Early menopause has differential, BMI-dependent effects on adipokine secretion.

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Key Words

• menopause
• menstrual cycle
• adipokines

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MESH Headings

• Adipokines/blood
• Adult
• Aging/blood
• Body Mass Index
• Female
• Humans
• Insulin Resistance
• Middle Aged
• Reproduction

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Grants

• P30 NR010677-03 NINR NIH HHS
• R01 AG015083-04 NIA NIH HHS
• P30 NR010677 NINR NIH HHS
• P30NR010677 NINR NIH HHS
• R01-AG15083-04 NIA NIH HHS
• 5-M01-00042 PHS HHS

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Affiliation(s)

Patricia A. Rouen McAuley School of Nursing, University of Detroit Mercy, 4001 W. McNichols Road., Detroit, MI 48221, , Phone: (313) 993-1739 Fax: (313) 993-1271
Jane L. Lukacs School of Nursing, University of Michigan, Ann Arbor, MI
Nancy E. Reame School of Nursing, Columbia University, New York, NY

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Current concepts of the pathogenesis of endometriosis

Endometriosis is a disease that causes the health of women of reproductive age to deteriorate. The implantation theory is the most widely accepted pathogenesis of the disease, although many points remain poorly understood concerning this theory. According to this theory, regurgitated endometrial debris has to go through various sequential events for the disease to develop. Recent studies have elucidated several aspects of these events. A remarkably reduced gene expression of GnRH II and an increase in uterine contraction-induced IL-8 secretion are suggested to be pathogenic changes in the eutopic endometrium of women with endometriosis. An increased level of osteoprotegerin in the peritoneal fluid of women with endometriosis is suggested to impede tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis of endometriotic cells. An increase in the concentration of hepatocyte growth factor and a decrease in the concentration of interferon gamma-inducible protein-10 in the peritoneal fluid of women with endometriosis may stimulate the angiogenesis and development of endometriosis. Midkine, the concentration of which is very high in the follicular fluid of the ovary, may stimulate the growth of endometriosis at the time of ovulation. Immune cells, such as macrophages, lymphocytes, mast cells, and neutrophils, in endometriotic lesions are suggested to play important roles in the progression of the disease. For example, IL-4 from Th2 cells, IL-17 from Th17 cells, tryptase from mast cells, and some serine proteases from neutrophils have been shown to stimulate endometriotic stromal cells, suggesting their specific roles in endometriosis. Interestingly, adiponectin, a key factor in metabolism, also appears to be involved in the pathogenesis of endometriosis. These novel findings sustain the current understanding of the pathogenesis of endometriosis.

Angiogenesis and antiangiogenic therapy in endometriosis

Endometriosis, the presence of endometrium-like tissue outside of the uterine cavity, is a common disease among women of reproductive age. Typical symptoms include abdominal pain and painful menstruation. In addition, endometriosis is associated with reduced fertility. Current treatment modalities, the surgical removal of endometriotic lesions and the hormonal suppression of estrogen are associated with significant morbidity, side-effects and recurrence rates. Despite uncertainties about the pathophysiology of the disease it has recently become apparent that angiogenesis plays a pivotal role in endometriosis. This review focuses on a multitude of factors involved in the angiogenic phenotype of endometriosis demonstrating that many biological systems such as the immune system and steroid hormones are closely connected to angiogenic pathways in this disease. In addition, experimental and clinical data are discussed that concentrate on the inhibition of angiogenesis as a novel therapeutic approach for endometriosis.

Metformin suppresses interleukin (IL)-1beta-induced IL-8 production, aromatase activation, and proliferation of endometriotic stromal cells

CONTEXT

Metformin, a widely used treatment for diabetes that improves insulin sensitivity, also has both antiinflammatory properties and a modulatory effect on ovarian steroid production, two actions that have been suggested to be efficacious in therapy for endometriosis.

OBJECTIVE

To determine whether metformin may be effective for the treatment of endometriosis, we evaluated the effects of this agent on inflammatory response, estradiol production, and proliferation of endometriotic stromal cells (ESCs).

DESIGN

ESCs derived from ovarian endometriomas were cultured with various concentrations of metformin.

MAIN OUTCOME MEASURES

IL-8 production, mRNA expression and aromatase activity, and 5-bromo-2'-deoxyuridine incorporation in ESCs were measured.

RESULTS

Metformin dose-dependently suppressed IL-1beta-induced IL-8 production, cAMP-induced mRNA expression and aromatase activity, and 5-bromo-2'-deoxyuridine incorporation in ESCs.

CONCLUSION

These results suggest that further investigation into the unique therapeutic potential of metformin as an antiendometriotic drug is warranted.

Development of multimarker panel for early detection of endometrial cancer. High diagnostic power of prolactin

OBJECTIVE

Endometrial carcinoma is the most common gynecologic cancer. Although the prognosis for endometrial cancer is generally good, cancers identified at late stages are associated with high levels of morbidity and mortality. Therefore, prevention and early detection may further reduce the burden of this challenging disease.

METHODS

A panel of 64 serum biomarkers was analyzed in sera of patients with stages I-III endometrial cancer and age-matched healthy women, utilizing a multiplex xMAP bead-based immunoassay. For multivariate analysis, four different statistical classification methods were used: logistic regression (LR), separating hyperplane (SHP), k nearest neighbors (KNN), and classification tree (CART). For each of these classifiers, a diagnostic model was created based on the cross-validation set consisting of sera from 115 patients with endometrial cancer and 135 healthy women.

RESULTS

Our data have demonstrated that patients with endometrial cancer have significantly different expression patterns of several serum biomarkers as compared to healthy controls. Prolactin was the strongest discriminative biomarker for endometrial cancer providing 98.3% sensitivity and 98.0% specificity alone. Our results have revealed that serum concentration of cancer antigens, including CA 125, CA 15-3, and CEA are higher in patients with Stage III endometrial cancer as compared to those with Stage I. In addition, we have shown that the expression of CA 125, AFP, and ACTH is elevated in women with tumor grade 3 vs. grade 1. Furthermore, five-biomarker panel (prolactin, GH, Eotaxin, E-selectin, and TSH) identified in this study was able to discriminate endometrial cancer from ovarian and breast cancers with high sensitivity and specificity.

CONCLUSIONS

The ability of prolactin to accurately discriminate between cancer and control groups indicates that this biomarker could potentially be used for development of blood-based test for the early detection of endometrial cancer in high-risk populations. Combining the information on multiple serum markers using flexible statistical methods allows for achieving high cancer selectivity.

Selective increase in high molecular weight adiponectin concentration in serum of women with preeclampsia

Total adiponectin concentrations have been shown to increase in serum of preeclamptic women. However, variance of concentrations of different isoforms has not been studied, despite the emerging notion that high, medium and low molecular weight adiponectin exert different functions. We have determined serum concentrations of each adiponectin isoform using a newly developed enzyme immunosorbent assay. High molecular weight (HMW) adiponectin concentrations were significantly higher in women with preeclampsia (n=14; median, 11.2 microg/ml; interquartile range, 9.2-15.8) compared to normal pregnant women (n=14; 6.8 microg/ml, 5.4-10.7; P=0.04). In contrast, medium molecular weight and low molecular weight adiponectin concentrations were substantially equal between the groups. The ratio of HMW adiponectin to total adiponectin was also markedly higher in preeclamptic women (52.3%, 49.5-58.7) than control women (43.0%; 39.8-48.0; P=0.004). Taken together with other reports our findings imply a physiological feedback response to minimize endothelial damage in preeclamptic women.

Expression of adiponectin receptors and its possible implication in the human endometrium

Adiponectin, a pleiotropic cytokine, exerts its effects via the specific receptors AdipoR1 and AdipoR2. Whereas circulating adiponectin concentrations decrease in women with endometriosis and endometrial cancer, possible effects of adiponectin and the presence of the receptors in the endometrium have not been determined. In this study, we examined the expression of adiponectin receptors AdipoR1 and AdipoR2 in the human endometrium and assessed effects of adiponectin in endometrial cells. Expression of AdipoR1 and AdipoR2 in endometrial tissues was evaluated by real-time quantitative PCR, in situ hybridization, and Western blotting. The effects of adiponectin on phosphorylation of AMP-activated protein kinase, a regulator of energy homeostasis, in cultured endometrial stromal cells (ESCs) and epithelial cells (EECs) were studied by Western blotting. The effects of adiponectin on IL-1beta-induced secretion of IL-6, IL-8, and monocyte chemoattractant protein 1 from cultured ESCs were determined using specific ELISAs. The expression of AdipoR1 and AdipoR2 was detected in the endometrium. The expression of both genes was increased in the midluteal phase, the period of embryo implantation. In situ hybridization revealed that both AdipoR1 and AdipoR2 appeared to be equally expressed in the epithelial cells and in the stromal cells. Adiponectin increased phosphorylation of AMP-activated protein kinase in ESCs and EECs. Adiponectin decreased IL-1beta-induced secretion of IL-6, IL-8, and monocyte chemoattractant protein 1 from ESCs. These findings suggest that adiponectin exerts energy-homeostatic and antiinflammatory effects in the endometrium, and these effects might be relevant to pathological and physiological endometrium-related events such as implantation and endometriosis.