Increased asymmetric dimethylarginine and enhanced inflammation are associated with impaired vascular reactivity in women with endometriosis

The pathogenesis of endometriosis and adenomyosis: insights from single-cell RNA sequencing†

Endometriosis and adenomyosis are two similar gynecological diseases that are characterized by ectopic implantation and the growth of the endometrial tissue. Previous studies have reported that they share a common pathophysiology in some respects, such as a similar cellular composition and resistance to the progestogen of lesions, but their underlying mechanisms remain elusive. Emerging single-cell ribonucleic acid sequencing (scRNA-seq) technologies allow for the dissection of single-cell transcriptome mapping to reveal the etiology of diseases at the level of the individual cell. In this review, we summarized the published findings in research on scRNA-seq regarding the cellular components and molecular profiles of diverse lesions. They show that epithelial cell clusters may be the vital progenitors of endometriosis and adenomyosis. Subclusters of stromal cells, such as endometrial mesenchymal stem cells and fibroblasts, are also involved in the occurrence of endometriosis and adenomyosis, respectively. Moreover, CD8+ T cells, natural killer cells, and macrophages exhibit a deficiency in clearing the ectopic endometrial cells in the immune microenvironment of endometriosis. It seems that the immune responses are activated in adenomyosis. Understanding the immune characteristics of adenomyosis still needs further exploration. Finally, we discuss the application of findings from scRNA-seq for clinical diagnosis and treatment. This review provides fresh insights into the pathogenesis of endometriosis and adenomyosis as well as the therapeutic targets at the cellular level.

Serum Levels of Interleukins in Endometriosis Patients: A Systematic Review and Meta-analysis

OBJECTIVE

The aims of this systematic review and meta-analysis were to produce a comprehensive survey of the serum levels of interleukins (ILs) in untreated people with endometriosis compared with people without endometriosis.

DATA SOURCES

A systematic literature search of English language studies within Cinahl, Medline Complete, PubMed, and Scopus from inception to May 2023 was performed.

METHODS OF STUDY SELECTION

We included studies that compared IL serum levels in people with endometriosis to those without endometriosis. Meta-analysis was performed on IL-1RA, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17A, IL-18, IL-23, and IL-37.

TABULATION, INTEGRATION, AND RESULTS

The systematic search retrieved 651 studies, of which 77 underwent a full-text review. A total of 30 studies met inclusion criteria for the meta-analysis. IL-1Ra, IL-6, and IL-37 serum levels were 2.56 (95% CI 2.20-2.92, p <.001), 1.38 (95% CI 0.58-2.17, p <.001), and 1.77 (95% CI 1.33-2.20, p <.001) standard deviations higher in the patients with endometriosis compared with patients without endometriosis while IL-23 serum levels 0.40 (95% CI -0.73 to -0.07, p = .02) standard deviations lower, respectively.

CONCLUSION

There is mounting evidence that ILs, especially IL-6, may be good candidates for unique noninvasive diagnostic tools and/or treatment pathways for endometriosis.

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

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

Reduced cardiovascular risks in women with endometriosis or polycystic ovary syndrome carrying a common functional IGF1R variant

STUDY QUESTION

Is the increased future cardiovascular risk seen in women with endometriosis or polycystic ovary syndrome (PCOS) mitigated by functional insulin-like growth factor-1 receptor (IGF1R) single-nucleotide polymorphism (SNP) rs2016347 as previously shown in women with hypertensive disorders of pregnancy?

SUMMARY ANSWER

This cohort study found that women with endometriosis or PCOS who carry a T allele of IGF1R SNP rs2016347 had a reduced future risk of developing cardiovascular disease (CVD) and associated risk factors, with risk reduction dependent on cohort era.

WHAT IS KNOWN ALREADY

Women with endometriosis or PCOS have been shown to have an increased future risk of CVD and associated risk factors with limited predictive ability.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study took place in the Nurses' Health Study 2 (NHS2), which enrolled 116 430 participants in 1989 who were followed through 2015. The study population was analyzed in its entirety, and subdivided into entry (pre-1989) and after entry (post-1989) exposure cohorts. All NHS2 participants were eligible for inclusion in the study, 9599 (8.2%) were excluded for missing covariates.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The NHS2 enrolled female registered nurses from 14 different states who ranged in age from 25 to 42 years at study entry. Data were collected from entry and biennial questionnaires, and analysis conducted from November 2020 to June 2021. Cox proportional hazard models were used to assess risk of CVD, hypertension (HTN), hypercholesterolemia (HC) and type 2 diabetes, both with and without genotyping for rs2016347.

MAIN RESULTS AND THE ROLE OF CHANCE

While women without endometriosis or PCOS, as a whole, demonstrated no impact of genotype on risk in either cohort, women with endometriosis carrying a T allele had a lower risk of CVD (hazard ratio (HR), 0.48; 95% CI, 0.27-0.86, P = 0.02) and HTN (HR, 0.80; 95% CI, 0.66-0.97, P = 0.03) in the pre-1989 cohort, while those in the post-1989 cohort had a decrease in risk for HC (HR, 0.76; 95% CI, 0.62-0.94, P = 0.01). Women with PCOS in the post-1989 cohort showed a significant protective impact of the T allele on HTN (HR, 0.44; 95% CI, 0.27-0.73, P = 0.002) and HC (HR, 0.62; 95% CI, 0.40-0.95, P = 0.03).

LIMITATIONS, REASONS FOR CAUTION

Data on specific endometriosis lesion locations or disease stage, as well as on PCOS phenotypes were lacking. In addition, data on systemic medical treatments beyond the use of oral contraceptives were missing, and these treatments may have confounded the results.

WIDER IMPLICATIONS OF THE FINDINGS

These findings implicate systemic dysregulation of the insulin-like growth factor-1 axis in the development of HTN, HC and clinical CVD in endometriosis and PCOS, suggesting a common underlying pathogenetic mechanism.

STUDY FUNDING/COMPETING INTEREST(S)

The NHS2 infrastructure for questionnaire data collection was supported by National Institute of Health (NIH) grant U01CA176726. This work was also supported in part by NIH and National Cancer Institute grant U24CA210990; as well, research effort and publication costs were supported by the Elizabeth MA Stevens donor funds provided to the Buck Institute for Research on Aging. The authors declare they have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Endometriosis and cardiovascular disease

Endometriosis is a chronic gynaecological disease affecting 1 in 10 reproductive-age women. It is defined as the presence of endometrium-like tissue outside the uterus. Beyond this placid anatomical definition, endometriosis is a complex, hormonal, inflammatory, and systemic condition that poses significant familial, psychological, and economic burden. The interaction between the cardiovascular system and endometriosis has become a field of interest as the underlying mutual mechanisms become better understood. On the basis of accumulating fundamental and clinical evidence, it is likely that there exists a close relationship between endometriosis and the cardiovascular system. Therefore, investigating the endometriosis-cardiovascular interaction is highly clinically significant. In this review, we highlight our current understanding of the pathophysiology of endometriosis with systemic hormonal, pro-inflammatory, pro-angiogenic, immunologic, and genetic processes beyond the peritoneal microenvironment. Additionally, we provide current clinical evidence about how endometriosis interacts with cardiovascular risk factors and cardiovascular disease (CVD). To date, only small associations between endometriosis and CVD have been reported in observational studies, inherently limited by the potential influence of unmeasured confounding. Cardiovascular disease in women with endometriosis remains understudied, under-recognized, and underdiagnosed. More detailed study of the cardiovascular-endometriosis interaction is needed to fully understand its clinical relevance, underlying pathophysiology, possible means of early diagnosis and prevention.

Female Infertility and Cardiovascular Risk - A Hype or an Underestimated Reality?

Infertility may be an early indicator of later-life health risk development, such as cardiovascular disease (CVD), the leading cause of death globally. Various infertility-associated factors such as female age, polycystic ovarian syndrome, endometriosis and metabolic syndrome are also risk factors for CVD. Whether there is a real association between female infertility and CVD, given that common pathways lead to both entities, or since both female infertility and CVD share a common basis, needs to be further investigated. If such an association is confirmed, infertile women might benefit from the initiation of preventive strategies aiming to control CVD risk factors. Thus, female infertility may represent an early indicator of future CVD and concomitantly a unique opportunity to identify women at increased risk for developing CVD. It is therefore imperative that large population- based studies are performed to elucidate this issue further and promote public awareness, if necessary.

Effects of androgenic properties of progestin combined with ethinyl estradiol on vascular endothelial reactivity, plasma lipids and free radical production in women with endometriosis

AIM

Endothelial reactivity is inhibited and oxidative stress is enhanced in women with endometriosis. Testosterone may adversely affect lipids and endothelium. We investigated the effects of androgenic properties of progestins combined with ethinyl estradiol (EE) on endothelial function, lipids and free radical production in such women.

METHODS

Women with endometriosis were treated with 20 μg EE + 3 mg drospirenone (DRSP) or 35 μg EE + 1 mg norethisterone (NET) for 3 months. Plasma concentrations of sex hormone-binding globulin (SHBG), lipids, copper (Cu), derivatives of reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), nitrite/nitrate, endothelin-1 and asymmetrical dimethylarginine (ADMA) were measured before and after treatment. Flow-mediated vasodilation (FMD) of the brachial artery was measured by ultrasonography.

RESULTS

DRSP group, but not NET group, significantly increased FMD and concentrations of nitrite/nitrate and small dense LDL cholesterol, while decreased endothelin-1 concentrations. In both groups, ADMA and LDL cholesterol concentrations were significantly decreased, but triglyceride, SHBG, d-ROMs, Cu and ceruloplasmin concentrations increased, and BAP concentrations did not change. DRSP group significantly increased HDL cholesterol concentrations, whereas NET group decreased its concentrations. Changes in triglyceride correlated positively either with changes in SHBG (r = 0.57, P < 0.001) or with small dense LDL cholesterol (r = 0.45, P = 0.005). Changes in Cu correlated positively with changes in d-ROMs (r = 0.87, P < 0.001).

CONCLUSION

Androgenic properties of progestin may counteract EE's favorable effects on endothelial function and HDL cholesterol, while eliminating its adverse effects on increased triglyceride-induced small dense LDL cholesterol in women with endometriosis.

Atherosclerosis-related biomarkers in women with endometriosis: The effects of dienogest and oral contraceptive therapy

Objective

Chronic inflammation in endometriosis is associated with increased risk of future cardiovascular disease; however, no studies have investigated the cardiovascular risk of women who have undergone hormonal therapy for endometriosis. We investigated atherosclerosis-related biomarkers in women with and without endometriosis and the effects of dienogest (DNG) and oral contraceptive (OC) therapies.

Study design

In this cross-sectional study, 109 women with endometriosis and 42 control women without endometriosis were enrolled. The endometriosis group was divided into the untreated (n = 34), DNG therapy (n = 33), and OC therapy (n = 42) groups. Lipid profile serum levels, inflammatory marker such as high-sensitivity C-reactive protein, oxidative stress markers such as oxidized low-density lipoprotein and diacron-reactive oxygen metabolites, and atherosclerosis indicators (cardio-ankle vascular index [CAVI] and ankle-brachial pressure index [ABI]) were measured.

Results

The median treatment duration was 28 months in the DNG group and 32.5 months in the OC group. Triglyceride levels were higher in the OC group than in the other three groups (P <  0.05). Regarding markers of inflammation and oxidative stress, log high-sensitivity C-reactive protein and diacron-reactive oxygen metabolites levels were higher in the untreated group than in the control group (P <  0.05), and these markers were further increased in the OC group (log high-sensitivity C-reactive protein: P <  0.05; diacron-reactive oxygen metabolites: P <  0.01), but not in the DNG group. There was no difference in the CAVI and ABI among all groups. Spearman correlation revealed a positive correlation between duration of OC therapy and CAVI (ρ = +0.49; P = 0.002), but no correlation between the duration of DNG therapy and CAVI (ρ = –0.04; P = 0.81).

Conclusions

Inflammation and oxidative stress markers are increased in women with untreated endometriosis. Treatment with OC, but not with DNG, further increases these levels. There was a positive association between the duration of OC administration and atherosclerosis risk for women with endometriosis. Our results suggest that DNG could be administered to endometriosis without the increased atherosclerosis risk and short-term OC administration for endometriosis is not harmful, however, atherosclerosis risk should be strictly observed.

Long-term Health Consequences of Endometriosis - Pathways and Mediation by Treatment

Purpose of review

The purpose of this review is to discuss the most up to date research on endometriosis and chronic disease risk, highlighting the role treatments for endometriosis may play in these associations.

Recent findings

Previous studies have shown a consistent association between endometriosis and risk for epithelial ovarian cancer but the association with other cancers is less clear. Current research indicates that endometriosis may in be associated with risk of systemic lupus erythematosus, and potentially other autoimmune diseases. Limited evidence is also present for the association between endometriosis and cardiovascular disease and related conditions (e.g,. hypertension, hypercholesterolemia). A potential explanation for a portion of the increased risk of chronic diseases among women with endometriosis may relate to treatments for endometriosis impacting these outcomes.

Summary

Given the prevalence of endometriosis, understanding the relation between endometriosis and other chronic diseases has the potential to impact the health of many women. However, few high-quality studies with limited biases and adequate follow-up currently exist. Future multi-disciplinary research in prospective cohorts, with ample follow-up time, and detailed information on endometriosis characteristics and treatment is critical to advancing our understanding of this disease and its consequences.

Atherosclerotic cardiovascular disease in women with endometriosis: a systematic review of risk factors and prospects for early surveillance

Endometriosis and atherosclerotic cardiovascular disease (ASCVD) share similar pathogenic mechanisms. Hence, this systematic review evaluates the association between endometriosis and lifetime ASCVD risk including co-prevalence with dyslipidaemia, atherosclerosis and non-invasive markers of endothelial dysfunction. The electronic databases Embase, PubMed, MEDLINE, Cochrane Register of Trials and ClinicalTrials.gov were systematically searched for relevant articles. Two prospective cohort studies demonstrated an increased lifetime ASCVD risk after controlling for demographic and lifestyle confounders in women with endometriosis, as measured by higher incidence of myocardial infarction (relative risk [RR] 1.52), angiography-confirmed angina (RR 1.91), or requiring coronary artery bypass graft surgery (RR 1.35). Among 10 studies that included 407 patients with surgically proven endometriosis and 557 controls, RR of developing hypercholesterolemia and hypertension were 1.25 and 1.14, respectively, while higher serum lipoprotein a and lower paraoxonase 1 levels were found in women with endometriosis that was negatively correlated with stage of disease (r = -0.74, P < 0.0001). Hence, currently available evidence suggests that women with endometriosis are at higher lifetime risk of developing ASCVD than women without endometriosis. However, robust causal evidence is still lacking and future studies are needed to determine whether women with endometriosis represent a high-risk population for lifelong ASCVD risk.

Cardiovascular risk may be increased in women with unexplained infertility

Objective

Growing evidence suggests that increased cardiovascular disease (CVD) risk is associated with female infertility caused by conditions such as polycystic ovarian disease, obesity, thyroid dysfunction, and endometriosis. The aim of this study was to evaluate whether any relationship exists between CVD and unexplained infertility.

Methods

Sixty-five women with unexplained infertility and 65 fertile controls were enrolled in the study. CVD risk markers such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), triglycerides (TG), insulin resistance (defined by the homeostasis model assessment ratio), and high-sensitivity C-reactive protein (hs-CRP) were assessed.

Results

TG, TC, LDL, and hs-CRP levels were higher and HDL levels were lower in patients with unexplained infertility than in fertile controls (p<0.05 for all). Positive associations were found between unexplained infertility and TG, TC, LDL, and hs-CRP levels, and a negative correlation was found for HDL (p<0.05 for all). Multivariate logistic regression analysis showed that TG, HDL, and hs-CRP were independent variables associated with unexplained infertility.

Conclusion

Our study showed that women with unexplained infertility had an atherogenic lipid profile and elevated hs-CRP levels, suggesting a higher risk of developing CVD in the future. Further studies with larger groups are needed to investigate the nature of this link.

Endometriosis: where are we and where are we going?

Endometriosis currently affects ~5.5 million reproductive-aged women in the U.S. with symptoms such as painful periods (dysmenorrhea), chronic pelvic pain, pain with intercourse (dyspareunia), and infertility. It is defined as the presence of endometrial tissue outside the uterine cavity and is found predominately attached to sites within the peritoneal cavity. Diagnosis for endometriosis is solely made through surgery as no consistent biomarkers for disease diagnosis exist. There is no cure for endometriosis and treatments only target symptoms and not the underlying mechanism(s) of disease. The nature of individual predisposing factors or inherent defects in the endometrium, immune system, and/or peritoneal cavity of women with endometriosis remains unclear. The literature over the last 5 years (2010-2015) has advanced our critical knowledge related to hormones, hormone receptors, immune dysregulation, hormonal treatments, and the transformation of endometriosis to ovarian cancer. In this review, we cover the aforementioned topics with the goal of providing the reader an overview and related references for further study to highlight the progress made in endometriosis research, while concluding with critical areas of endometriosis research that are urgently needed.

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.

Endometriosis Located Proximal to or Remote From the Uterus Differentially Affects Uterine Gene Expression

The mechanisms that lead to the altered uterine gene expression in women with endometriosis are poorly understood. Are these changes in gene expression mediated by proximity to endometriotic lesions or is endometriosis a systemic disease where the effect is independent of proximity to the uterus? To answer this question, we created endometriosis in a murine model either in the peritoneal cavity (proximal) or at a subcutaneous remote site (distal). The expression of several genes that are involved in endometrial receptivity (homeobox A10 [Hoxa10], homeobox A11 [Hoxa11], insulin-like growth factor binding protein 1 [Igfbp1], Kruppel-like factor 9 [Klf9], and progesterone receptor [Pgr]) was measured in the eutopic endometrium of mice transplanted with either proximal or distal endometriosis lesions. Decreased expression of Hoxa10, Igfbp1, Klf9, and total Pgr genes was observed in the eutopic endometrium of mice with peritoneal endometriosis. In the mice with distal lesions, overall expression of these genes was not as severely affected, however, Igfbp1 expression was similarly decreased and the effect on Pgr was more pronounced. Endometriosis does have a systemic effect that varies with distance to the end organ. However, even remote disease selectively and profoundly alters the expression of genes such as Pgr. This is the first controlled experiment demonstrating that endometriosis is not simply a local peritoneal disease. Selective alteration of genes critical for endometrial receptivity and endometriosis propagation may be systemic. Similarly, systemic effects of endometriosis on other organs may also be responsible for the widespread manifestations of the disease.

Endometriosis and atherosclerosis: what we already know and what we have yet to discover

The possible association between endometriosis and atherosclerosis represents an emerging topic in the field of women's health. In this Clinical Opinion paper, we analyze this theme focusing on the pathogenetic mechanisms of both diseases, deeply discussing about what is already known about this association and producing starting points about what we consider suitable to research in the near future with regard to cardiovascular involvement in women affected by endometriosis. We have identified 5 reports specifically carried out to investigate the relationship between atherosclerosis and endometriosis; these studies show the presence of subclinical atherosclerosis in women affected by endometriosis, susceptible of regression after surgical removal of endometriosis, with a possible prognostic relevance for variations of cardiovascular risk in these women. However, to date, no studies in literature have been carried out to investigate the real incidence of cardiovascular events in women with endometriosis.

Targeting oxidative stress to treat endometriosis

INTRODUCTION

Endometriosis affects 10% of women of reproductive age. It is defined as the presence of implanted active endometrial tissue outside the uterine cavity. The exact pathophysiology of endometriosis is still uncertain, although several optional etiological theories have been suggested. Being so common, a novel treatment for endometriosis is widely quested. Recent studies addressing the pathological characteristics of endometriosis have revealed a vicious cycle in which oxidative stress (OS) is generated, which in turn facilitates the implantation of the ectopic endometrium. At the same time, the generation of high amounts of reactive oxygen species further triggers a state of OS.

AREAS COVERED

The author examined the evidence associating OS and endometriosis. After establishing an association, a search for antioxidant agents that were investigated specifically on endometriosis patients are described including Vitamins C and E, melatonin, resveratrol, xanthohumol and epigallocatechin-3-gallate. A significant effect of all the reviewed antioxidants on endometriosis is reported.

EXPERT OPINION

Aiming for the reduction of OS as the treatment goal for endometriosis looks promising. However, since most of the studies are either in vitro or are animal based, further studies on human subjects are deemed necessary to elucidate the impact of OS reduction on patients with endometriosis.

Endometriosis: a high-risk population for major chronic diseases?

BACKGROUND

Despite an estimated prevalence of 10% in women, the etiology of endometriosis remains poorly understood. Over recent decades, endometriosis has been associated with risk of several chronic diseases, such as cancer, autoimmune diseases, asthma/atopic diseases and cardiovascular diseases. A deeper understanding of these associations is needed as they may provide new leads into the causes or consequences of endometriosis. This review summarizes the available epidemiological findings on the associations between endometriosis and other chronic diseases and discusses hypotheses for underlying mechanisms, potential sources of bias and methodological complexities.

METHODS

We performed a comprehensive search of the PubMed/Medline and ISI Web of Knowledge databases for all studies reporting on the associations between endometriosis and other diseases published in English through to May 2014, using numerous search terms. We additionally examined the reference lists of all identified papers to capture any additional articles that were not identified through computer searches.

RESULTS

We identified 21 studies on the associations between endometriosis and ovarian cancer, 14 for breast cancer, 8 for endometrial cancer, 4 for cervical cancer, 12 for cutaneous melanoma and 3 for non-Hodgkin's lymphoma, as well as 9 on the links between endometriosis and autoimmune diseases, 6 on the links with asthma and atopic diseases, and 4 on the links with cardiovascular diseases. Endometriosis patients were reported to be at higher risk of ovarian and breast cancers, cutaneous melanoma, asthma, and some autoimmune, cardiovascular and atopic diseases, and at decreased risk of cervical cancer.

CONCLUSIONS

Increasing evidence suggests that endometriosis patients are at higher risk of several chronic diseases. Although the underlying mechanisms are not yet understood, the available data to date suggest that endometriosis is not harmless with respects to women's long-term health. If these relationships are confirmed, these findings may have important implications in screening practices and in the management and care of endometriosis patients.

The Impact of Endometriosis across the Lifespan of Women: Foreseeable Research and Therapeutic Prospects

In addition to estrogen dependence, endometriosis is characterized by chronic pelvic inflammation. The impact of the chronic pelvic inflammatory state on other organ systems and women's health is unclear. Endometriosis associated chronic inflammation and potential adverse health effects across the lifespan render it imperative for renewed research vigor into the identification of novel biomarkers of disease and therapeutic options. Herein we propose a number of opportunities for research and development of new therapeutics to address the unmet needs in the treatment of endometriosis per se and its ancillary risks for other diseases in women across the lifespan.

Disease history and risk of comorbidity in women's life course: a comprehensive analysis of the Japan Nurses' Health Study baseline survey

OBJECTIVE

To classify diseases based on age at peak incidence to identify risk factors for later disease in women's life course.

DESIGN

A cross-sectional baseline survey of participants in the Japan Nurses' Health Study.

SETTING

A nationwide prospective cohort study on the health of Japanese nurses. The baseline survey was conducted between 2001 and 2007 (n=49,927).

MAIN OUTCOME MEASURES

Age at peak incidence for 20 diseases from a survey of Japanese women was estimated using the Kaplan-Meier method with the Kernel smoothing technique. The incidence rate and peak incidence for diseases whose peak incidence occurred before the age of 45 years or before the perimenopausal period were selected as early-onset diseases. The OR and 95% CI were estimated to examine the risk of comorbidity between early-onset and other diseases.

RESULTS

Four early-onset diseases (endometriosis, anaemia, migraine headache and uterine myoma) were significantly correlated with one another. Late-onset diseases significantly associated (OR>2) with early-onset diseases included comorbid endometriosis with ovarian cancer (3.65 (2.16 to 6.19)), endometrial cancer (2.40 (1.14 to 5.04)) and cerebral infarction (2.10 (1.15 to 3.85)); comorbid anaemia with gastric cancer (3.69 (2.68 to 5.08)); comorbid migraine with transient ischaemic attack (3.06 (2.29 to 4.09)), osteoporosis (2.11 (1.71 to 2.62)), cerebral infarction (2.04 (1.26 to 3.30)) and angina pectoris (2.00 (1.49 to 2.67)); and comorbid uterine myoma with colorectal cancer (2.31 (1.48 to 3.61)).

CONCLUSIONS

While there were significant associations between four early-onset diseases, women with a history of one or more of the early-onset diseases had a higher risk of other diseases later in their life course. Understanding the history of early-onset diseases in women may help reduce the subsequent risk of chronic diseases in later life.

Arterial stiffness is increased in young women with endometriosis

Endometriosis is a chronic gynaecological disorder that is accompanied by inflammation and oxidative stress. Atherosclerosis has a long subclinical progression in arteries of children and young adults decades before overt clinical manifestations of the disease. In this study, we determined arterial stiffness by measuring brachial-ankle pulse wave velocity (baPWV) in women with endometriosis to assess the presence of subclinical atherosclerosis. We also measured markers of inflammation and oxidative stress in women with endometriosis. baPWV in women with endometriosis aged over 30 years was significantly higher than that in women without endometriosis aged over 30 years (p < 0.05), but not in women aged less than 30. Serum high-sensitivity C-reactive protein level in women with endometriosis was significantly higher than that in controls (p < 0.05). Young women with endometriosis show significantly increased arterial stiffness, suggesting that women with endometriosis need to be cautious of the future onset of atherosclerosis.

Endothelial dysfunction but not increased carotid intima-media thickness in young European women with endometriosis

BACKGROUND

Atherosclerosis is a chronic and degenerative disease developing typically in the elderly; nonetheless, a condition of accelerated atherosclerosis can be observed precociously in the presence of some diseases. Endometriosis, a chronic benign gynecological disorder, shows some characteristics, such as oxidative stress, systemic inflammation and a pro-atherogenic lipid profile, which could increase the risk of developing accelerated atherosclerosis. The aim of our study was to evaluate markers of subclinical atherosclerosis in young European women with endometriosis.

METHODS

This cross-sectional study included 37 women with endometriosis and 31 control subjects. The presence of subclinical atherosclerosis was investigated by ultrasound evaluation of common carotid intima-media thickness (ccIMT) and flow-mediated dilation (FMD); in addition, serum levels of lipids, inflammatory and coagulation parameters, as well as markers of endothelial inflammation and activation, were determined.

RESULTS

Women with endometriosis showed significantly lower values of FMD compared with controls [mean difference: -4.62, 95% confidence interval (CI): -6.52, -2.73; P < 0.001], whereas no significant differences in ccIMT values were found between the two groups. As regards markers of endothelial inflammation and activation, women with endometriosis had significantly higher values of inter-cellular adhesion molecule 1 (P < 0.001), vascular cell adhesion molecule 1 (P < 0.001), E-selectin (P < 0.001), von Willebrand factor (P = 0.004) and ristocetin cofactor (P = 0.001) compared with controls.

CONCLUSIONS

Our study suggests that women with endometriosis have more subclinical atherosclerosis, resulting in a higher risk of developing cardiovascular disorders. Moreover, our findings demonstrate that endothelial dysfunction can occur in the absence of structural atherosclerotic changes; its evaluation might be helpful in young women with endometriosis.