Limited value of pro-inflammatory oxylipins and cytokines as circulating biomarkers in endometriosis - a targeted 'omics study

Follicular Fluid and Blood Monitorization of Infertility Biomarkers in Women with Endometriosis

Infertility is recognized globally as a social disease and a growing medical condition, posing a significant challenge to modern reproductive health. Endometriosis, the third-most frequent gynecologic disorder, is one of the most common and intricate conditions that can lead to female infertility. Despite extensive research, the etiology, malignant transformation, and biological therapy of endometriosis remain unknown. Blood and follicular fluid are two matrices that have been carefully studied and can provide insights into women's health. These matrices are clinically significant because they contain metabolites closely associated with women's illness stage and reproductive outcomes. Nowadays, the application of metabolomic analysis in biological matrices may be able to predict the outcome of assisted reproductive technologies with greater precision. From a molecular viewpoint on reproductive health, we evaluate and compare the utilization of human follicular fluid and blood as matrices in analysis for diagnostic and assisted reproductive technology (ART) predictors of success for endometriosis patients. In the follicular fluid (FF), plasma, and serum of endometriosis-affected women, researchers identified dysregulations of oxidative stress, upregulation of several immune factors, and aberrations in energy metabolic pathways. The altered signatures negatively correlate with the overall oocyte and embryo quality and fertilization rate.

Cytokine and chemokine profiles in women with endometriosis, polycystic ovary syndrome, and unexplained infertility

Numerous factors (including immunological, congenital, hormonal, and morphological disorders) can lead to infertility. In this regard, 3 specific diseases associated with infertility are discussed in this review study (i.e., polycystic ovary syndrome [PCOS], endometriosis [EMS], and unexplained infertility [UI]). PCOS is a common endocrine disorder characterized by chronic low-grade inflammation, and EMS is a benign disease characterized by the presence of ectopic endometrial tissue. UI refers to couples who are unable to conceive for no known reason. Conception and pregnancy are significantly affected by the immune system; in this regard, chemokines and cytokines play important roles in the regulation of immune responses. Patients with PCOS, EMS, and UI have altered cytokine and chemokine profiles, suggesting that dysregulation of these molecules may contribute to infertility in these conditions. Accordingly, the issue of infertility is addressed in this review study, a condition that affects approximately 16% of couples worldwide.

An integrated multi-tissue approach for endometriosis candidate biomarkers: a systematic review

Biomarker identification could help in deciphering endometriosis pathophysiology in addition to their use in the development of non invasive diagnostic and prognostic approaches, that are essential to greatly improve patient care. Despite extensive efforts, no single potential biomarker or combination has been clinically validated for endometriosis.Many studies have investigated endometriosis-associated biological markers in specific tissues, but an integrative approach across tissues is lacking. The aim of this review is to propose a comprehensive overview of identified biomarkers based on tissue or biological compartment, while taking into account endometriosis phenotypes (superficial, ovarian or deep, or rASRM stages), menstrual cycle phases, treatments and symptoms.We searched PubMed and Embase databases for articles matching the following criteria: 'endometriosis' present in the title and the associated term 'biomarkers' found as Medical Subject Headings (MeSH) terms or in all fields. We restricted to publications in English and on human populations. Relevant articles published between 01 January 2005 (when endometriosis phenotypes start to be described in papers) and 01 September 2022 were critically analysed and discussed.Four hundred forty seven articles on endometriosis biomarkers that included a control group without endometriosis and provided specific information on endometriosis phenotypes are included in this review. Presence of information or adjustment controlling for menstrual cycle phase, symptoms and treatments is highlighted, and the results are further summarized by biological compartment. The 9 biological compartments studied for endometriosis biomarker research are in order of frequency: peripheral blood, eutopic endometrium, peritoneal fluid, ovaries, urine, menstrual blood, saliva, feces and cervical mucus. Adjustments of results on disease phenotypes, cycle phases, treatments and symptoms are present in 70%, 29%, 3% and 6% of selected articles, respectively. A total of 1107 biomarkers were identified in these biological compartments. Of these, 74 were found in several biological compartments by at least two independent research teams and only 4 (TNF-a, MMP-9, TIMP-1 and miR-451) are detected in at least 3 tissues with cohorts of 30 women or more.Integrative analysis is a crucial step to highlight potential pitfalls behind the lack of success in the search for clinically relevant endometriosis biomarkers, and to illuminate the physiopathology of this disease.

Effects of dysregulated glucose metabolism on the occurrence and ART outcome of endometriosis

BACKGROUND

Endometriosis is associated with systemic metabolic indicators, including body mass index (BMI), glucose metabolism and lipid metabolism, while the association between metabolic indexes and the occurrence and assisted reproductive technology (ART) outcome of endometriosis is unclear. We aimed to evaluate the characteristics of systemic metabolic indexes of endometriosis patients with infertility and their effects on pregnancy outcome after ART treatment.

METHODS

A retrospective cohort study involve 412 endometriosis patients and 1551 controls was conducted. Primary outcome was metabolic indexes, and secondary measures consisted of the influence of metabolic indexes on the number of retrieved oocytes and ART outcomes.

RESULTS

Endometriosis patients had higher insulin (INS) [6.90(5.10-9.50) vs 6.50(4.80-8.90) μU/mL, P = 0.005]. A prediction model for endometriosis combining the number of previous pregnancies, CA125, fasting blood glucose (Glu) and INS, had a sensitivity of 73.9%, specificity of 67.8% and area under curve (AUC) of 0.77. There were no significant differences in ART outcomes and complications during pregnancy. The serum levels of Glu before pregnancy were associated with GDM both in endometriosis group (aOR 12.95, 95% CI 1.69-99.42, P = 0.014) and in control group (aOR 4.15, 95% CI 1.50-11.53, P = 0.006).

CONCLUSIONS

We found serum Glu is related to the number of retrieved oocytes in control group, serum INS is related to the number of retrieved oocytes in endometriosis group, while serum Glu and INS before pregnancy are related to the occurrence of GDM in two groups. A prediction model based on metabolic indexes was established, representing a promising non-invasive method to predict endometriosis patients with known pregnancy history.

Dehydroepiandrosterone supplementation and the impact of follicular fluid metabolome and cytokinome profiles in poor ovarian responders

BACKGROUND

Poor ovarian responders (POR) are women undergoing in-vitro fertilization who respond poorly to ovarian stimulation, resulting in the retrieval of lower number of oocytes, and subsequently lower pregnancy rates. The follicular fluid (FF) provides a crucial microenvironment for the proper development of follicles and oocytes through tightly controlled metabolism and cell signaling. Androgens such as dehydroepiandrosterone (DHEA) have been proposed to alter the POR follicular microenvironment, but the impact DHEA imposes on the FF metabolome and cytokine profiles is unknown. Therefore, the objective of this study is to profile and identify metabolomic changes in the FF with DHEA supplementation in POR patients.

METHODS

FF samples collected from 52 POR patients who underwent IVF with DHEA supplementation (DHEA +) and without (DHEA-; controls) were analyzed using untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics and a large-scale multiplex suspension immunoassay covering 65 cytokines, chemokines and growth factors. Multivariate statistical modelling by partial least squares-discriminant regression (PLSR) analysis was performed for revealing metabolome-scale differences. Further, differential metabolite analysis between the two groups was performed by PLSR β-coefficient regression analysis and Student's t-test.

RESULTS

Untargeted metabolomics identified 118 FF metabolites of diverse chemistries and concentrations which spanned three orders of magnitude. They include metabolic products highly associated with ovarian function - amino acids for regulating pH and osmolarity, lipids such fatty acids and cholesterols for oocyte maturation, and glucocorticoids for ovarian steroidogenesis. Four metabolites, namely, glycerophosphocholine, linoleic acid, progesterone, and valine were significantly lower in DHEA + relative to DHEA- (p < 0.05-0.005). The area under the curves of progesterone glycerophosphocholine, linoleic acid and valine are 0.711, 0.730, 0.785 and 0.818 (p < 0.05-0.01). In DHEA + patients, progesterone positively correlated with IGF-1 (Pearson r: 0.6757, p < 0.01); glycerophosphocholine negatively correlated with AMH (Pearson r: -0.5815; p < 0.05); linoleic acid correlated with estradiol and IGF-1 (Pearson r: 0.7016 and 0.8203, respectively; p < 0.01 for both). In DHEA- patients, valine negatively correlated with serum-free testosterone (Pearson r: -0.8774; p < 0.0001). Using the large-scale immunoassay of 45 cytokines, we observed significantly lower MCP1, IFNγ, LIF and VEGF-D levels in DHEA + relative to DHEA.

CONCLUSIONS

In POR patients, DHEA supplementation altered the FF metabolome and cytokine profile. The identified four FF metabolites that significantly changed with DHEA may provide information for titrating and monitoring individual DHEA supplementation.

Gas Chromatography-Mass Spectrometry (GC-MS) Metabolites Analysis in Endometriosis Patients: A Prospective Observational Translational Study

BACKGROUND

Endometriosis affects women of reproductive age, and its pathogenesis is still unclear. Typically, it overlaps other similar medical and surgical conditions, determining a delay in early diagnosis. Metabolomics allows studying metabolic changes in different physiological or pathological states to discover new potential biomarkers. We used the gas chromatography-mass spectrometer (GC-MS) to explore metabolic alterations in endometriosis to better understand its pathophysiology and find new biomarkers.

METHODS

Twenty-two serum samples of patients with symptomatic endometriosis and ten without it were collected and subjected to GC-MS analysis. Multivariate and univariate statistical analyses were performed, followed by pathway analysis.

RESULTS

Partial least squares discriminant analysis was performed to determine the differences between the two groups (p = 0.003). Threonic acid, 3-hydroxybutyric acid, and proline increased significantly in endometriosis patients, while alanine and valine decreased. ROC curves were built to test the diagnostic power of metabolites. The pathway analysis identified the synthesis and degradation of ketone bodies and the biosynthesis of phenylalanine, tyrosine, and tryptophan as the most altered pathways.

CONCLUSIONS

The metabolomic approach identifies metabolic alterations in women with endometriosis. These findings may improve our understanding of the pathophysiological mechanisms of disease and the discovery of new biomarkers.

Non-invasive diagnosis of endometriosis: Immunologic and genetic markers

Endometriosis, a benign gynecologic and chronic inflammatory disease, is defined by the presence of endometrial tissue outside the uterus characterized mainly by pelvic pain and infertility. Because endometriosis affects approximately 10% of females, it represents a significant socioeconomic burden worldwide having tremendous impact on daily quality of life. Accurate and prompt diagnosis is crucial for the management of this debilitating disorder. Unfortunately, diagnosis is typically delayed to lack of specific symptoms and readily accessible biomarkers. Although histopathologic examination remains the current gold standard, this approach is highly invasive and not applicable for early screening. Recent work has focused on the identification of reliable biomarkers including immunologic, ie, immune cells, antibodies and cytokines, as well as genetic and biochemical markers, ie, microRNAs, lncRNAs, circulating and mitochondrial nucleic acids, along with some hormones, glycoproteins and signaling molecules. Confirmatory research studies are, however, needed to more fully establish these markers in the diagnosis, progression and staging of these endometrial lesions.

Decreased Innate Migration of Pro-Inflammatory M1 Macrophages through the Mesothelial Membrane Is Affected by Ceramide Kinase and Ceramide 1-P

The retrograde flow of endometrial tissues deposited into the peritoneal cavity occurs in women during menstruation. Classically (M1) or alternatively (M2) activated macrophages partake in the removal of regurgitated menstrual tissue. The failure of macrophage egress from the peritoneal cavity through the mesothelium leads to chronic inflammation in endometriosis. To study the migration differences of macrophage phenotypes across mesothelial cells, an in vitro model of macrophage egress across a peritoneal mesothelial cell monolayer membrane was developed. M1 macrophages were more sessile, emigrating 2.9-fold less than M2 macrophages. The M1 macrophages displayed a pro-inflammatory cytokine signature, including IL-1α, IL-1β, TNF-α, TNF-β, and IL-12p70. Mass spectrometry sphingolipidomics revealed decreased levels of ceramide-1-phosphate (C1P), an inducer of migration in M1 macrophages, which correlated with its poor migration behavior. C1P is generated by ceramide kinase (CERK) from ceramide, and blocking C1P synthesis via the action of NVP231, a specific CERK chemical inhibitor, prohibited the emigration of M1 and M2 macrophages up to 6.7-fold. Incubation with exogenously added C1P rescued this effect. These results suggest that M1 macrophages are less mobile and have higher retention in the peritoneum due to lower C1P levels, which contributes to an altered peritoneal environment in endometriosis by generating a predominant pro-inflammatory cytokine environment.

The role of the Immune System in the Development of Endometriosis

Endometriosis is a chronic disease that affects about 10% of women of reproductive age. It can contribute to pelvic pain, infertility or other conditions such as asthma, cardiovascular disease, breast or ovarian cancer. Research has shown that one of the conditions for the development of endometrial lesions is the dysfunction of the immune system. It appears that immune cells, such as neutrophils, macrophages, NK cells and dendritic cells, may play a specific role in the angiogenesis, growth and invasion of endometriosis cells. Immune cells secrete cytokines and defensins that also affect the endometriosis environment. This review discusses the various components of the immune system that are involved in the formation of endometrial lesions in women.

Is there a role for small molecule metabolite biomarkers in the development of a diagnostic test for endometriosis?

Endometriosis is a disease defined by the presence of benign lesions of endometrial-like glands and stroma outside the endometrial cavity. Affecting an estimated 11.4% of Australian women, symptoms include chronic pelvic pain, dysmenorrhea and infertility. The current gold standard of diagnosis requires an expensive and invasive laparoscopic surgery, resulting in delayed time to treatment. The identification of a non-invasive endometriosis biomarker - a measurable factor correlating with disease presence or activity - has therefore become a priority in endometriosis research, although no biomarker has yet been validated. As small molecule metabolites and lipids have emerged as a potential focus, this review with systematic approach, aims to summarize studies examining metabolomic biomarkers of endometriosis in order to guide future research. EMBASE, PubMed and Web of Science were searched using keywords: lipidomics OR metabolomics OR metabolome AND diagnostic tests OR biomarkers AND endometriosis, and only studies written in English from August 2000 to August 2020 were included. Twenty-nine studies met inclusion and exclusion criteria and were included. These studies identified potential biomarkers in serum, ectopic tissue, eutopic endometrium, peritoneal fluid, follicular fluid, urine, cervical swabs and endometrial fluid. Glycerophospholipids were identified as potential biomarkers in all specimens, except urine and cervical swab specimens. However, no individual molecule or metabolite combination has reached clinical diagnostic utility. Further research using large study populations with robust patient phenotype and specimen characterisation is required if we are to make progress in identifying and validating a non-invasive diagnostic test for endometriosis.

Dysregulated sphingolipid metabolism and autophagy in granulosa cells of women with endometriosis

We evaluated metabolic profiles between cumulus cells (CCs) and mural granulosa cells (MGCs) derived from women with endometriosis to identify their correlations with oocyte quality. CCs and MGCs were collected from women with and without endometriosis undergoing in vitro fertilization/intracytoplasmic sperm injection treatment. The metabolomics of CCs and MGCs were measured by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) followed by a quantitative polymerase chain reaction to further confirm the genes involved in the metabolic results. LC-MS/MS analysis revealed differences in 24 metabolites of CCs and 71 metabolites of MGCs between groups. Among them, five metabolites were upregulated and 19 metabolites were downregulated in CCs with endometriosis, whereas three metabolites were upregulated and 68 metabolites were downregulated in MGCs with endometriosis. Metabolites related to sphingolipid metabolism, which included palmitic acid (PA) and docosahexaenoic acid, increased significantly only in CCs with endometriosis, whereas sphingosine and PA were significantly downregulated in MGCs with endometriosis compared with CCs and MGCs without endometriosis. Gene expression involved in ceramide synthesis (CERS1, SPTL1, and SMPD1) and autophagy (BECN1, LAMP, and PC3) were significantly higher in CCs with endometriosis according to FASN, BECN1, and LAMP protein expressions. However, gene expression involved in ceramide synthesis (SPHK1, ASAH1, and SGPP1) and autophagy (BECN1, LAMP, and PC3) were significantly lower in MGCs with endometriosis, whereas CERS1 and UGCG expression increased. There are differences in sphingolipid metabolites in CCs and MGCs with endometriosis compared with women without endometriosis. These differences seem to be involved in the regulation of autophagic cell death in preovulatory follicles.

Endometriosis: Epidemiology, Classification, Pathogenesis, Treatment and Genetics (Review of Literature)

Endometriosis is a “mysterious” disease and its exact cause has not yet been established. Among the etiological factors, congenital, environmental, epigenetic, autoimmune and allergic factors are listed. It is believed that the primary mechanism of the formation of endometriosis foci is retrograde menstruation, i.e., the passage of menstrual blood through the fallopian tubes into the peritoneal cavity and implantation of exfoliated endometrial cells. However, since this mechanism is also observed in healthy women, other factors must also be involved in the formation of endometriosis foci. Endometriosis is in many women the cause of infertility, chronic pain and the deterioration of the quality of life. It also represents a significant financial burden on health systems. The article presents a review of the literature on endometriosis—a disease affecting women throughout the world.

Discovery and validation of peritoneal endometriosis biomarkers in peritoneal fluid and serum

RESEARCH QUESTION

What are the potential biomarkers for peritoneal endometriosis in peritoneal fluid and serum?

DESIGN

Case-control studies composed of independent discovery and validation sets were conducted. In the discovery set, untargeted liquid chromatography-mass spectrometry (LC-MS/MS) metabolomics, multivariable and univariable analyses were conducted to generate global metabolomic profiles of peritoneal fluid for endometriosis and to identify potential metabolites that could distinguish peritoneal endometriosis (n = 10) from controls (n = 31). The identified metabolites from the discovery set were validated in independent peritoneal fluid (n =19 peritoneal endometriosis and n = 20 controls) and serum samples (n = 16 peritoneal endometriosis and n = 19 controls) using targeted metabolomics. The area under the receiver-operating characteristics curve (AUC) analysis was used to evaluate the diagnostic performance of peritoneal endometriosis metabolites.

RESULTS

In the discovery set, peritoneal fluid phosphatidylcholine (34:3) and phenylalanyl-isoleucine were significantly increased in peritoneal endometriosis groups compared with control groups, with AUC 0.77 (95% CI 0.61 to 0.92; P = 0.018) and AUC 0.98 (95% CI 0.95 to 1.02; P < 0.001), respectively. In the validation set, phenylalanyl-isoleucine retained discriminatory performance to distinguish peritoneal endometriosis from controls in both peritoneal fluid (AUC 0.77, 95% CI 0.61 to 0.92; P = 0.006) and serum samples (AUC 0.81, 95% CI 0.64 to 0.99; P = 0.004), with notably stronger discrimination between peritoneal endometriosis and controls in proliferative phase.

CONCLUSION

Our preliminary results propose phenylalanyl-isoleucine as a potential biomarker of peritoneal endometriosis, which may be used as a minimally invasive diagnostic biomarker of peritoneal endometriosis.

Metabolic Profile of Patients with Severe Endometriosis: a Prospective Experimental Study

Endometriosis is a common disease affecting women in reproductive age. There are several hypotheses on the pathogenesis of this disease. Often, its lesions and symptoms overlap with those of many other medical and surgical conditions, causing a delay in diagnosis. Metabolomics represents a useful diagnostic tool for the study of metabolic changes during a different physiological or pathological status. We used 1H-NMR to explore metabolic alteration in a cohort of patients with endometriosis in order to contribute to a better understanding of the pathophysiology of the disease and to suggest new useful biomarkers. Thirty-seven patients were recruited for the metabolomic analysis: 22 patients affected by symptomatic endometriosis and 15 not affected by it. Their serum samples were collected and analyzed with 1H-NMR. Multivariate statistical analysis was conducted, followed by univariate and pathway analyses. Partial Least Square Discriminant Analysis (PLS-DA) was performed to determine the presence of any differences between the non-endometriosis and endometriosis samples (R2X = 0.596, R2Y = 0.713, Q2 = 0.635, and p < 0.0001). β-hydroxybutyric acid and glutamine were significantly increased, whereas tryptophan was significantly decreased in the endometriosis patients. ROC curves were built to test the diagnostic power of the metabolites (β-hydroxybutyric acid: AUC = 0.85 CI = 0.71-0.99; glutamine: AUC = 0.83 CI = 0.68-0.98; tryptophan: AUC = 0.75 CI = 0.54-0.95; β-hydroxybutyric acid + glutamine + tryptophan AUC = 0.92 CI = 0.81-1). The metabolomic approach enabled the identification of several metabolic alterations occurring in women with endometriosis. These findings may provide new bases for a better understanding of the pathophysiological mechanisms of the disease and for the discovery of new biomarkers. Trial registration number NCT02337816.

The Role of Arachidonic and Linoleic Acid Derivatives in Pathological Pregnancies and the Human Reproduction Process

The aim of the available literature review was to focus on the role of the proinflammatory mediators of AA and LA derivatives in pathological conditions related to reproduction and pregnancy. Arachidonic (AA) and linoleic acid (LA) derivatives play important roles in human fertility and the course of pathological pregnancies. Recent studies have demonstrated that uncontrolled inflammation has a significant impact on reproduction, spermatogenesis, endometriosis, polycystic ovary syndrome (PCOS) genesis, implantation, pregnancy and labor. In addition, cyclooxygenase-mediated prostaglandins and AA metabolite levels are higher in women’s ovarian tissue when suffering from PCOS. It has been demonstrated that abnormal cyclooxygenase-2 (COX-2) levels are associated with ovulation failure, infertility, and implantation disorders and the increase in 9-HODE/13-HODE was a feature recognized in PCOS patients. Maintaining inflammation without neutrophil participation allows pregnant women to tolerate the fetus, while excessive inflammatory activation may lead to miscarriages and other pathological complications in pregnancies. Additionally AA and LA derivatives play an important role in pregnancy pathologies, e.g., gestational diabetes mellitus, preeclampsia (PE), and fetal growth, among others. The pathogenesis of PE and other pathological states in pregnancy involving eicosanoids have not been fully identified. A significant expression of 15-LOX-1,2 was found in women with PE, leading to an increase in the synthesis of AA and LA derivatives, such as hydroxyeicozatetraenoic acids (HETE) and hydroxyoctadecadiene acids (HODE). Synthesis of the metabolites 5-, 8-, 12-, and 15-HETE increased in the placenta, while 20-HETE increased only in umbilical cord blood in women with preeclampsia compared to normal pregnancies. In obese women with gestational diabetes mellitus (GDM) an increase in epoxygenase products in the cytochrome P450 (CYP) and the level of 20-HETE associated with the occurrence of insulin resistance (IR) were found. In addition, 12- and 20-HETE levels were associated with arterial vasoconstriction and epoxyeicosatrienoic acids (EETs) with arterial vasodilatation and uterine relaxation. Furthermore, higher levels of 5- and 15-HETE were associated with premature labor. By analyzing the influence of free fatty acids (FFA) and their derivatives on male reproduction, it was found that an increase in the AA in semen reduces its amount and the ratio of omega-6 to omega-3 fatty acids showed higher values in infertile men compared to the fertile control group. There are several studies on the role of HETE/HODE in relation to male fertility. 15-Hydroperoxyeicosatetraenoic acid may affect the integrity of the membrane and sperm function. Moreover, the incubation of sperm with physiologically low levels of prostaglandins (PGE2/PGF2α) improves the functionality of human sperm. Undoubtedly, these problems are still insufficiently understood and require further research. However, HETE and HODE could serve as predictive and diagnostic biomarkers for pregnancy pathologies (especially in women with risk factors for overweight and obesity). Such knowledge may be helpful in finding new treatment strategies for infertility and the course of high-risk pregnancies.

Peritoneal Fluid Cytokines Reveal New Insights of Endometriosis Subphenotypes

Endometriosis is a common inflammatory gynecological disorder which causes pelvic scarring, pain, and infertility, characterized by the implantation of endometrial-like lesions outside the uterus. The peritoneum, ovaries, and deep soft tissues are the commonly involved sites, and endometriotic lesions can be classified into three subphenotypes: superficial peritoneal endometriosis (PE), ovarian endometrioma (OE), and deep infiltrating endometriosis (DIE). In 132 women diagnosed laparoscopically with and without endometriosis (n = 73, 59 respectively), and stratified into PE, OE, and DIE, peritoneal fluids (PF) were characterized for 48 cytokines by using multiplex immunoassays. Partial-least-squares-regression analysis revealed distinct subphenotype cytokine signatures—a six-cytokine signature distinguishing PE from OE, a seven-cytokine signature distinguishing OE from DIE, and a six-cytokine-signature distinguishing PE from DIE—each associated with different patterns of biological processes, signaling events, and immunology. These signatures describe endometriosis better than disease stages (p < 0.0001). Pathway analysis revealed the association of ERK1 and 2, AKT, MAPK, and STAT4 linked to angiogenesis, cell proliferation, migration, and inflammation in the subphenotypes. These data shed new insights on the pathophysiology of endometriosis subphenotypes, with the potential to exploit the cytokine signatures to stratify endometriosis patients for targeted therapies and biomarker discovery.

Gamma-Synuclein Levels Are Elevated in Peritoneal Fluid of Patients with Endometriosis

Background

The role of gamma-synuclein (SNCG) has been widely examined in malignant conditions due to its possible role in disease progression, but very little information is available on its theoretical function on endometriosis formation.

Material/Methods

Between January 2016 and December 2016, we collected peritoneal fluid and plasma samples from 45 consecutive female patients, of which 15 were without endometriosis, 15 had minimal to mild endometriosis, and 15 had moderate to severe endometriosis. The statistical power was 0.98. We evaluated SNCG levels in the peritoneal fluid and plasma of patients diagnosed with endometriosis, and we compared them with the levels obtained from disease-free control subjects by using enzyme-linked immunosorbent assay.

Results

SNCG levels were statistically significantly (1.2-fold) higher in the peritoneal fluid of patients with endometriosis compared to controls (p=0.04). We did not find a significant difference between SNCG levels in the plasma of our endometriosis patients and the control group (p=0.086). However, despite previous data showing very limited expression of SNCG in healthy tissues, we found SNCG in the peritoneal fluid of all of the patients in our healthy control group.

Conclusions

Levels of SNCG were statistically significantly higher in the peritoneal fluid of patients with endometriosis compared to disease-free controls, which may indicate its possible role the formation and progression of the disease. Moreover, its biological function should be further investigated due to the conflicting results concerning its expression in healthy tissues.

Endometriosis research in the -omics era

Endometriosis is a pathological condition extensively studied, but its pathogenesis is not completely understood, since its pathophysiology stems from a broad spectrum of environmental influences and genetic factors. Moreover, the nature of this condition is heterogeneous and includes different anatomical entities. Scientists actively pursue discovery of novel biomarkers in the hope of better identifying susceptible individuals in early stages of the disease. High-throughput technologies have substantially revolutionized medical research and, as a first step, the advent of genotyping arrays led to large-scale genome-wide association studies (GWAS) and enabled the assessment of global transcript levels, thus giving rise to integrative genetics. In this framework, comprehensive studies have been conducted at multiple biological levels by using the "omics" platforms, thus allowing to re-examine endometriosis at a greater degree of molecular resolution. -Omics technologies can detect and analyze hundreds of markers in the same experiment and their increasing use in the field of gynecology comes from an urgent need to find new diagnostic and therapeutic tools that improve the diagnosis of endometriosis and the efficacy of assisted reproductive techniques. Proteomics and metabolomics have been introduced recently into the every day methodology of researchers collaborating with gynecologists and, importantly, multi-omics approach is advantageous to gain insight of the total information that underlies endometriosis, compared to studies of any single -omics type. In this review, we expect to present multiple studies based on the high-throughput-omics technologies and to shed light in all considerable advantages that they may confer to a proper management of endometriosis.

Multiplex analysis of 40 cytokines do not allow separation between endometriosis patients and controls

Endometriosis is a common gynaecological condition characterized by severe pelvic pain and/or infertility. The combination of nonspecific symptoms and invasive laparoscopic diagnostics have prompted researchers to evaluate potential biomarkers that would enable a non-invasive diagnosis of endometriosis. Endometriosis is an inflammatory disease thus different cytokines represent potential diagnostic biomarkers. As panels of biomarkers are expected to enable better separation between patients and controls we evaluated 40 different cytokines in plasma samples of 210 patients (116 patients with endometriosis; 94 controls) from two medical centres (Slovenian, Austrian). Results of the univariate statistical analysis showed no differences in concentrations of the measured cytokines between patients and controls, confirmed by principal component analysis showing no clear separation amongst these two groups. In order to validate the hypothesis of a more profound (non-linear) differentiating dependency between features, machine learning methods were used. We trained four common machine learning algorithms (decision tree, linear model, k-nearest neighbour, random forest) on data from plasma levels of proteins and patients’ clinical data. The constructed models, however, did not separate patients with endometriosis from the controls with sufficient sensitivity and specificity. This study thus indicates that plasma levels of the selected cytokines have limited potential for diagnosis of endometriosis.

Anti-inflammatory cytokines in endometriosis

Although the pathogenesis of endometriosis is not fully understood, it is often considered to be an inflammatory disease. An increasing number of studies suggest that differential expression of anti-inflammatory cytokines (e.g., interleukin-4 and -10, and transforming growth factor-β1) occurs in women with endometriosis, including in serum, peritoneal fluid and ectopic lesions. These anti-inflammatory cytokines also have indispensable roles in the progression of endometriosis, including by promoting survival, growth, invasion, differentiation, angiogenesis, and immune escape of the endometriotic lesions. In this review, we provide an overview of the expression, origin, function and regulation of anti-inflammatory cytokines in endometriosis, with brief discussion and perspectives on their future clinical implications in the diagnosis and therapy of the disease.

Modern Methods of Sample Preparation for the Analysis of Oxylipins in Biological Samples

Oxylipins are potent lipid mediators derived from polyunsaturated fatty acids, which play important roles in various biological processes. Being important regulators and/or markers of a wide range of normal and pathological processes, oxylipins are becoming a popular subject of research; however, the low stability and often very low concentration of oxylipins in samples are a significant challenge for authors and continuous improvement is required in both the extraction and analysis techniques. In recent years, the study of oxylipins has been directly related to the development of new technological platforms based on mass spectrometry (LC–MS/MS and gas chromatography–mass spectrometry (GC–MS)/MS), as well as the improvement in methods for the extraction of oxylipins from biological samples. In this review, we systematize and compare information on sample preparation procedures, including solid-phase extraction, liquid–liquid extraction from different biological tissues.

Aberrant methylation of the IL-12B promotor region contributes to the risk of developing ovarian endometriosis

Studies have shown that aberrant expression of IL-12p40, which is encoded by the interleukin-12B (IL-12B) gene, may be involved in the development of endometriosis. In this study, we investigated the role of aberrant methylation of the IL-12B promoter region and its associated expression in the development of ovarian endometriosis. By using pyrosequencing, we analyzed the methylation level of the IL-12B promoter region in eutopic and ectopic endometrium of patients with ovarian endometriosis and normal endometrium of control women. The expression of IL-12B mRNA was detected by quantitative real-time PCR. The results showed that the methylation level of the IL-12B promoter region in ectopic and eutopic endometrium of patients with ovarian endometriosis was significantly lower than that in endometrium of women without endometriosis ( p < 0.001 and p = 0.041, respectively). In contrast, mRNA levels were significantly increased in ectopic and eutopic endometrium of patients with ovarian endometriosis compared to those in endometrium of women without endometriosis ( p < 0.001 and p = 0.042, respectively). Correlation analysis showed that the methylation level of the IL-12B promoter region was negatively correlated with mRNA levels of IL-12B ( p < 0.001). Our data suggested that aberrant methylation of the IL-12B promoter region may be responsible for aberrant IL-12B mRNA expression in endometrium tissue of women, which may be associated with the development of ovarian endometriosis in northern Chinese women.

Elevated peritoneal fluid ceramides in human endometriosis-associated infertility and their effects on mouse oocyte maturation

OBJECTIVE

To characterize the peritoneal fluid (PF) sphingolipid profile in endometriosis-associated infertility (EAI), and to assess the plausible functional role(s) of ceramides in oocyte maturation potential.

DESIGN

Retrospective case-control study and in vitro mouse oocyte study.

SETTING

University-affiliated hospital and university laboratory.

SUBJECTS

Twenty-seven infertile patients diagnosed with endometriosis and 20 infertile patients who did not have endometriosis; BALB/c female mice.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

PF sphingolipid concentrations. Number of metaphase II (MII) mouse oocytes.

RESULT(S)

Liquid chromatography-tandem mass spectrometry revealed 11 significantly elevated PF sphingolipids in infertile women with severe endometriosis compared with infertile women without endometriosis (change >50%, false discovery rate ≤10%). Logistic regression analysis identified three very-long-chain ceramides potentially associated with EAI. Functional studies revealed that very-long-chain ceramides may compromise or induce murine MII oocyte maturation. The oocyte maturation effects induced by the very long-chain ceramides were triggered by alterations in mitochondrial superoxide production in a concentration-dependent manner. Scavenging of mitochondrial superoxide reversed the maturation effects of C_24:0 ceramide.

CONCLUSION(S)

EAI is associated with accumulation of PF very-long-chain ceramides. Mouse studies demonstrated how ceramides affect MII oocyte maturation, mediating through mitochondrial superoxide. These results provide an opportunity for direct functional readout of pathophysiology in EAI, and future therapies targeted at this sphingolipid metabolism may be harnessed for improved oocyte maturation.

Differential responses of endothelial integrity upon the intake of microencapsulated garlic, tomato extract or a mixture: a single-intake, randomized, double-blind, placebo-controlled crossover trial

This study investigated the effect of microencapsulated garlic and/or tomato on endothelial dysfunction induced by the PhenFlex test (PFT) in healthy male smokers. In a randomized, double-blind, placebo-controlled crossover trial, 41 healthy male smokers were randomly assigned to one of four groups to receive the test groups (in microencapsulated garlic powder, tomato extract and a mixture thereof) or the placebo group. Proteomic biomarkers related to endothelial integrity were measured in plasma. Microencapsulated garlic, tomato extract and the mixture affected endothelial integrity biomarkers differently. Garlic consumption increased prothrombin time and decreased SAA and IL-12. Tomato extract intake increased activated partial thrombin time and decreased d-dimer, SAA, sVCAM-1, IL-13 and MCP-3 levels. Consumption of the mixture increased sE-selectin and lowered D-dimer, SAA, IL-13 and IL-10 responses after PFT challenge for 6 h. The different responses became clearer under high compliance in the dietary restriction groups. This single-intake clinical trial addressed the different responses of biomarkers related to endothelial integrity.

An overview of the biologic effects of omega-6 oxylipins in humans

Oxylipins are lipid mediators produced from polyunsaturated fatty acid (PUFA) metabolism, and are thought to be a molecular explanation for the diverse biological effects of PUFAs. Like PUFAs, oxylipins are distinguished by their omega-6 (n6) or omega-3 (n3) chemistry. We review the use of n6 oxylipins as biomarkers of disease and their use in diagnosis and risk assessment. We show cases where oxylipins derived from linoleate (LA) or arachidonate (AA) produced by the activities of lipoxygenase, cyclooxygenase, epoxygenase, ω/ω-1 hydroxylase, and autooxidation are useful as biomarkers or risk markers. HODEs, KODEs, EpOMEs, DiHOMEs, and other metabolites of LA as well as prostanoids, HETEs, KETEs, EpETrEs, and DiHETrEs, and other metabolites of AA were useful for understanding the different signaling environments in conditions from traumatic brain injury, to major coronary events, dyslipidemia, sepsis, and more. We next evaluate interventions that alter the concentrations of n6 oxylipins in plasma. We note the utility and response of each plasma fraction, and the generally increasing utility from the non-esterified, to the esterified, to the lipoprotein fractions. Finally, we review the effects which are specifically related to n6 oxylipins and most likely to be beneficial. Both n6 and n3 oxylipins work together in an exceedingly complex matrix to produce physiological effects. This overview should provide future investigators with important perspectives for the emerging utility of n6 oxylipins as products of n6 PUFAs in human health.

Metabolomics reveals perturbations in endometrium and serum of minimal and mild endometriosis

Endometriosis is a common benign gynecological disease, characterized by growth and proliferation of endometrial glands and stroma outside the uterus. With studies showing metabolic changes in various biofluids of endometriosis women, we have set upon to investigate whether endometrial tissue show differences in their metabolic profiles. ¹H NMR analysis was performed on eutopic endometrial tissue of women with endometriosis and controls. Analysis was performed on spectral data and on relative concentrations of metabolites obtained from spectra using multivariate and univariate data analysis. Analysis shows that various energy, ketogenic and glucogenic metabolites have significant altered concentrations in various stages of endometriosis. In addition, altered tissue metabolites in minimal and mild stages of endometriosis were explored in serum of these patients to assess their role in disease diagnosis. For Stage I diagnosis alanine was found to have 90% sensitivity (true positives) and 58% specificity (true negatives). For Stage II diagnosis alanine, leucine, lysine, proline and phenylalanine showed significant altered levels in serum. While sensitivity of these serum metabolites varied between 69.2–100% the specificity values ranged between 58.3–91.7%. Further, a regression model generated with this panel of serum markers showed an improved sensitivity and specificity of 100% and 83%, respectively for Stage II diagnosis.

Noninvasive diagnosis of endometriosis: Review of current peripheral blood and endometrial biomarkers

A noninvasive biomarker-based test could help shorten the diagnostic delay for endometriosis. The most investigated biomarker sources are peripheral blood and endometrium. Discovery of endometriosis biomarkers is often hypothesis-driven, i.e. when one or a few biomarkers are investigated based on their role in the disease pathogenesis. Alternatively, a hypothesis-generating approach has been followed using the "omics" technologies. A variety of biomarkers for endometriosis have been investigated, but no biomarker has been validated for clinical use. Many challenges lie ahead in the endometriosis biomarker field. In the future, harmonized collection and reporting methods should allow large-scale international collaboration for highly powered studies.

Omega-6-derived oxylipin changes in serum of patients with hepatitis B virus-related liver diseases

INTRODUCTION

Chronic hepatitis B virus (HBV) infection is the main etiologic risk factor for hepatocellular carcinoma (HCC). Early studies indicated that the increase of omega-6-derived oxylipins may be involved in the pathogenesis of HBV-related HCC, yet their changes during the distinct clinical phases of chronic HBV infection remain unclear. To fill this gap, in this study we investigated the omega-6-derived oxylipin profiles in patients with three major clinical stages of chronic HBV infection (chronic hepatitis B, liver cirrhosis, and HCC).

METHODS

Eighteen omega-6-derived oxylipins were quantified in serum samples of 34 patients with chronic hepatitis B, 46 patients with HBV-related liver cirrhosis, 38 patients with HBV-related HCC, and 50 healthy controls using liquid chromatography tandem mass spectrometry.

RESULTS

Seven oxylipins were found to be altered in patients with HBV-related liver diseases, including 9,10-dihydroxyoctadecenoic acid (9,10-DiHOME), 12,13-DiHOME, 14,15-dihydroxyeicosatrienoic acid (14,15-DiHETrE), 13-hydroxyoctadecadienoic acid (13-HODE), 12-hydroxyeicosatetraenoic acid (12-HETE), 11-HETE, and thromboxane B₂ (TXB₂). Of these, three oxylipins derived from the cytochrome P450 (CYP450) pathways including 9,10-DiHOME, 12,13-DiHOME, and 14,15-DiHETrE were found to be associated with the levels of α-fetoprotein (AFP), a tumor marker. In combination with AFP, age, and gender, a combination of these seven differential oxylipins could significantly enhance the prediction of HBV-related liver diseases, particularly for liver cirrhosis (p < 0.05).

CONCLUSION

This study for the first time shows the correlations between CYP450-derived oxylipins and the progression of chronic HBV infection, and sheds a new light on the surveillance of HBV-related live diseases using oxylipins.

Endocrinology Meets Metabolomics: Achievements, Pitfalls, and Challenges

The metabolome, although very dynamic, is sufficiently stable to provide specific quantitative traits related to health and disease. Metabolomics requires balanced use of state-of-the-art study design, chemical analytics, biostatistics, and bioinformatics to deliver meaningful answers to contemporary questions in human disease research. The technology is now frequently employed for biomarker discovery and for elucidating the mechanisms underlying endocrine-related diseases. Metabolomics has also enriched genome-wide association studies (GWAS) in this area by providing functional data. The contributions of rare genetic variants to metabolome variance and to the human phenotype have been underestimated until now.

Endometriosis foci differentiation by rapid lipid profiling using tissue spray ionization and high resolution mass spectrometry

Obtaining fast screening information on molecular composition of a tissue sample is of great importance for a disease biomarkers search and for online surgery control. In this study, high resolution mass spectrometry analysis of eutopic and ectopic endometrium tissues (90 samples) is done using direct tissue spray mass spectrometry in both positive and negative ion modes. The most abundant peaks in the both ion modes are those corresponding to lipids. Species of three lipid classes are observed, phosphatidylcholines (PC), sphingomyelins (SM) and phosphoethanolamines (PE). Direct tissue analysis gives mainly information on PC and SM lipids (29 species) in positive ion mode and PC, SM and PE lipids (50 species) in negative ion mode which gives complementary data for endometriosis foci differentiation. The biggest differences were found for phospholipids with polyunsaturated acyls and alkils. Although, tissue spray shows itself as appropriate tool for tissue investigation, caution should be paid to the interpretation of mass spectra because of their higher complexity with more possible adducts formation and multiple interferences must be taken into account. The present work extends the application of direct tissue analysis for the rapid differentiation between endometriotic tissues of different foci.