Assessing brain-derived neurotrophic factor as a novel clinical marker of endometriosis

Pilot Study of IL-1 Antagonist Anakinra for Treatment of Endometriosis

Purpose

To evaluate the impact of an interleukin-1 (IL-1) antagonist anakinra (Kineret®) on endometriosis-related quality of life (QoL), pain, and inflammatory biomarkers.

Methods

This was a single-site, randomized, double-blinded, placebo-controlled, cross-over pilot clinical study of patients recruited at an academic specialty clinic. Eligible participants were females aged 18-45 years with menstrual cycles every 24-32 days. Subjects had moderate to severe dysmenorrhea and either a surgical diagnosis of endometriosis or an endometrioma on imaging. Subjects were randomly assigned in a double-blind fashion to receive either the study drug or placebo administered as daily injections during the first 3 periods and then the alternate intervention for the next 3 periods.

Results

Fifteen subjects completed the 6 menstrual cycle study. After each period, they completed the Endometriosis Health Profile-30 (EHP-30) QoL questionnaire and an assessment of dysmenorrhea using a 0-100 Visual Analogue Scale (VAS). All domains of the EHP-30 showed a trend towards improvement, with significant improvements in powerlessness (54.5 vs 63.3, p = 0.04) and self-image (58.1 vs 66.7, p = 0.03) on the study drug compared to placebo. The mean dysmenorrhea VAS also trended toward improvement with a score of 37.5 during active treatment and 42.6 with placebo (p = 0.26). No difference in menstrual cycle length was detected (29.3 days vs 27.7 days, p = 0.56). There were significant differences in multiple inflammatory biomarkers between the study drug and placebo, including BDNF, IL-1, and IL-6 among certain groups.

Conclusion

With all EHP-30 domains and the dysmenorrhea VAS showing either a statistical improvement or trend towards improvement, there is justification for a larger study. As no impact on menstrual cycles was detected, anakinra may be a particularly impactful option for women desiring fertility. Additional evaluation is needed on the role of anakinra on inflammatory markers given significant reductions were identified in multiple biomarkers.

Crimson clues: advancing endometriosis detection and management with novel blood biomarkers

Endometriosis is an inflammatory condition affecting approximately 10% of the female-born population. Despite its prevalence, the lack of noninvasive biomarkers has contributed to an established global diagnostic delay. The intricate pathophysiology of this enigmatic disease may leave signatures in the blood, which, when detected, can be used as noninvasive biomarkers. This review provides an update on how investigators are utilizing the established disease pathways and innovative methodologies, including genome-wide association studies, next-generation sequencing, and machine learning, to unravel the clues left in the blood to develop blood biomarkers. Many blood biomarkers show promise in the discovery phase, but because of a lack of standardized and robust methodologies, they rarely progress to the development stages. However, we are now seeing biomarkers being validated with high diagnostic accuracy and improvements in standardization protocols, providing promise for the future of endometriosis blood biomarkers.

Brain-derived neurotrophic factor (BDNF) as a potential marker of endometriosis: a systematic review and meta-analysis

BACKGROUND

The existing literature on the association between BDNF protein levels and endometriosis presents inconsistent findings. This systematic review and meta-analysis aim to synthesize the available evidence and evaluate the possible relationship between BDNF protein levels and endometriosis.

METHODS

Electronic databases (PubMed, Embase, Scopus, PsycINFO, and Web of Science) were used to conduct a comprehensive literature search from inception to June 2023. The search strategy included relevant keywords and medical subject headings (MeSH) terms related to BDNF, endometriosis, and protein levels. A random-effects model was used for the meta-analysis, and to explore heterogeneity subgroup analyses were performed. funnel plots and statistical tests were used for assessing the publication bias.

RESULTS

A total of 12 studies were included. The pooled standardized mean difference (SMD) of BDNF levels between women with endometriosis and controls was 0.87 (95% confidence interval [CI] 0.34 to 1.39, p = 0.001; I2 = 93%). The results showed that blood levels of BDNF are significantly higher in endometriosis patients (SMD: 1.13 95% CI 0.54 to 1.73, p = 0.0002; I2 = 93%). No significant publication bias was observed based on the results of Egger's regression test ((p = 0.15).

CONCLUSION

This study revealed a significant difference between patients diagnosed with endometriosis and healthy control in the level of BDNF. The results indicate that women with endometriosis have higher levels of BDNF. Further studies are needed to be undertaken to investigate the role of BDNF in endometriosis pathophysiology and the diagnostic value of BDNF in endometriosis.

Brain-derived neurotrophic factor and nerve growth factor expression in endometriosis: A systematic review and meta-analysis

Endometriosis is diagnosed by laparoscopic surgery. The availability of biomarkers can help understand the pathophysiology and aid in the diagnosis of the condition. In this context, this review aimed to examine levels of expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are increased amongst patients with endometriosis and if they can serve as a potential biomarker. PubMed, CENTRAL, Scopus, Web of Science, and Embase databases were searched for studies comparing BDNF or NGF levels amongst endometriosis patients and controls. Data were pooled for serum and tissue levels of BDNF and NGF. Ten fulfilled the inclusion criteria. On comparing BDNF levels, it was noted that endometrial tissue had significantly higher expression of BDNF levels as compared to controls (SMD: 1.73 95% CI: 0.64, 2.82 I2 = 89%). Similarly, the meta-analysis found significantly higher serum levels of BDNF in endometriosis patients as compared to controls (SMD: 1.66 95% CI: 0.73, 2.59 I2 = 95%). Pooled analysis showed significantly increased levels of NGF in endometrial tissue as compared to controls (SMD: 4.15 95% CI: 0.11, 8.18 I2 = 98%) but with unstable results on sensitivity analysis. Only one study showed higher levels of NGF in serum amongst endometriosis patients. Limited data shows higher expression of BDNF in endometrial lesions and increased serum levels of BDNF in endometriosis patients. Similar results were noted for NGF but with very scarce data. Further research is needed to establish BDNF and NGF as suitable biomarkers for the disease.

Development and Validation of an Endometriosis Diagnostic Method Based on Serum Biomarkers and Clinical Variables

Endometriosis affects more than 10% of women of reproductive age, significantly impacting their quality of life. Diagnosis typically takes 4 to 11 years from symptom onset. The gold standard for diagnosing this disease, laparoscopy, is invasive, contributing to this delay in diagnosis. Two studies were conducted to develop a diagnostic test based on the combination of serum biomarkers and clinical variables. Study 1, the development study, aimed to: (i) confirm the ability of CA125, BDNF and clinical variables to differentiate between cases and controls, and (ii) develop a diagnostic algorithm based on these results. Study 2 validated the clinical performance of the developed in vitro diagnostic (IVD) test in diagnosing endometriosis. Serum samples and clinical variables extracted from psychometric questionnaires were obtained from the Oxford Endometriosis CaRe Centre biobank (UK). Case/control classification was performed based on laparoscopy and histological verification of the excised lesions. Studies 1 and 2 included n = 204 and n = 79 patients, respectively. Study 1 found a statistically significant difference between cases and controls for levels of both biomarkers. Of the assessed clinical variables from the patients' medical histories, six were found to be significantly different between endometriosis cases and controls. CA125, BDNF and these six clinical variables were combined into a multivariable prediction model. In Study 2, the IVD test demonstrated sensitivity and specificity values of 46.2% (25.5-66.8%) and 100% (86.7-100%), respectively. Due to its high specificity, this IVD test is a simple and accurate rule-in test for early disease identification, even in the presence of non-specific symptoms.

Circulating CD200 is increased in the secretory phase of women with endometriosis as is endometrial mRNA, and endometrial stromal cell CD200R1 is increased in spite of reduced mRNA

PROBLEM

Estrogen-dependent extrauterine implantation and growth of menstrual endometrial tissue affects roughly 10% of reproductive age women and depends on suppression of local innate immune defenses to prevent ectopic tissue rejection. Immunohistochemistry has shown the immune check-point inhibitor CD200 which can suppress rejection is expressed in eutopic endometrium and in ectopic deposits. Soluble CD200 accumulated in venules draining eutopic and ectopic endometrium of endometriosis cases in the secretory phase but not proliferative phase of the menstrual cycle, and should be increased in the circulation.

METHOD OF STUDY

Sera from endometriosis and non-endometriosis controls were tested by ELISA for CD200. Endometrial CD200, CD200R1 and CD200R2 mRNA in eutopic was quantified by RT-PCR and localized by in situ hybridization. CD200R1 protein was quantified by immunohistochemistry.

RESULTS

Secretory phase serum CD200 was elevated in women with endometriosis compared to controls. Serum CD200 correlated with matched endometrial CD200 mRNA levels. Expression of mRNA for CD200R1 which signals immune suppression was decreased whereas mRNA for the CD200R2 activating receptor was increased. In situ staining of CD200R1 and CD200R2 mRNA showed both receptors were expressed and the fraction of CD200R that is CD200R1 was reduced in secretory and menstrual phase endometriosis endometrium consistent with the RT-PCR result. By contrast, CD200R1 protein and CD200R1 fraction of total CD200R protein were increased in endometriosis.

CONCLUSIONS

Failure to suppress circulating CD200 levels in the secretory phase had an 87% specificity and 90% sensitivity for endometriosis. CD200 and increased CD200R1 expression may facilitate development of ectopic deposits by suppressing rejection mechanisms.

BDNF and TrKB expression levels in patients with endometriosis and their associations with dysmenorrhoea

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a known regulator of the development and maintenance of chronic pain in various chronic disorders. Together with its high-affinity tyrosine kinase type B (TrKB) receptor, BDNF is extensively expressed in the mammalian female reproductive system. However, BDNF and TrKB expression in different stages of endometriosis and the relationship between the expression of each in ectopic lesions and endometriosis pain remain unclear.

METHODS

Sixty-two women who underwent laparoscopic surgery were enrolled in this study: forty-six diagnosed with ovarian endometrioma (study group) and sixteen diagnosed with ovarian benign tumours (control group). Samples from eutopic endometrium and ovarian endometriotic lesions were obtained at laparoscopic surgery. BDNF and TrKB messenger RNA (mRNA) and proteins levels in the eutopic and ectopic endometrium of both groups were measured by real-time PCR and immunohistochemical staining, respectively. Before the surgery the visual analogue scale (VAS) was used to measure dysmenorrhoea.

RESULTS

BDNF and TrKB expression levels were higher in ovarian endometriotic lesions than in eutopic endometrium and normal endometrium (P < 0.05), and there was no cyclical change. Furthermore, their expression levels were higher in eutopic endometrium than in normal endometrium (P < 0.05), and BDNF and TrKB levels were higher in stage IV ovarian endometriotic lesions than in stage II and III lesions (P < 0.05), with their expression being non-significantly higher in stage III than in stage II (P > 0.05). Additionally, correlation coefficients for the association analysis between the mRNA expression of BDNF or TrKB in eutopic endometrium and the dysmenorrhoea VAS score were r = 0.52 and r = 0.56 for BDNF and TrKB, respectively (P < 0.05). The correlation coefficients for the associations between BDNF and TrKB in both the eutopic and ectopic endometrium were r = 0.82 and r = 0.66, respectively (P < 0.05).

CONCLUSIONS

BDNF and TrKB are closely related to dysmenorrhoea caused by endometriosis and may be important in the pathobiology or pathophysiology of endometriosis.

The Anti-Endometriotic Effect of Cyperi Rhizoma Extract, Inhibiting Cell Adhesion and the Expression of Pain-Related Factors through Akt and NF-kB Pathways

Rhizomes of Cyperus rotundus have been widely used as a traditional medicine in Asia for the treatment of gynecological diseases. However, there is no scientific evidence demonstrating the effect of C. rotundus rhizomes on endometriosis, which is characterized by the adhesion of endometrial tissues outside the uterus, resulting in chronic and severe pelvic pain. The aim of this study was to investigate the effects of Cyperi rhizoma extract (CRE) on cell adhesion and the expression of pain-related factors (neurotrophins) in endometriotic cells, and to elucidate the underlying molecular mechanisms. CRE inhibited the adhesion of human endometriotic 12Z cells to peritoneal mesothelial Met5A cells using by adhesion assays. The mRNA expression of adhesion molecules [P-cadherin and matrix metalloproteinase (MMP)-2] was downregulated by CRE treatment. In addition, CRE significantly inhibited the mRNA expression of neurotrophins (BDNF, NGF, NT-3 and NT-4/5) in 12Z cells. Moreover, Akt overexpression markedly neutralized the inhibition of cell adhesion by CRE and expression of neurotrophins in 12Z cells. Furthermore, it was found that CRE suppressed NF-kB activation through the Akt pathway. These data suggest that CRE exerts anti-endometriotic activities by the inhibition of cell adhesion and neurotrophin expression, through the negative regulation of the Akt and NF-kB pathways in endometriotic cells.

Association between endometriosis and lower urinary tract symptoms

OBJECTIVE

To determine if women with endometriosis experience lower urinary tract symptoms (LUTSs) more often than those without.

DESIGN

Cross-sectional analysis at enrollment in a longitudinal cohort.

SETTING

Enrollment at 2 academic hospitals and from the local community.

PATIENT(S)

This analysis included 1,161 women with (n = 520) and without (n = 641) surgically confirmed endometriosis who were enrolled in the Women's Health Study: from Adolescence to Adulthood between 2012 and 2018.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Prevalence of LUTSs, including stress incontinence, urgency and frequency, straining with urination, incomplete bladder emptying, hematuria, dysuria, and bladder pain using standardized questionnaires.

RESULT(S)

The primary outcomes were that women with endometriosis reported the following more often than those without: difficulty passing urine (7.9% vs. 2%; crude odds ratio [OR], 4.14 [95% confidence interval {CI}, 2.19-7.80]; adjusted OR [aOR], 4.31 [95% CI, 2.07-8.95]); still feeling full after urination (18.8% vs. 4.7%; crude OR, 4.73 [95% CI, 3.08-7.25]; aOR, 4.67 [95% CI, 2.88-7.56]); having to urinate again within minutes of urinating (33.1% vs. 17.0%; crude OR, 2.41 [95% CI, 1.83-3.18]; aOR, 2.49 [95% CI, 1.81-3.43]), dysuria (11.7% vs. 4.9%; crude OR, 2.55 [95% CI, 1.62-4.01]; aOR, 2.38 [95% CI, 1.40-4.02]); and pain when the bladder is full (23.0% vs. 4.9%; crude OR, 5.79 [95% CI, 3.82-8.78]; aOR, 6.04 [95% CI, 3.74-9.76]). For the secondary outcomes, among female participants with endometriosis, we observed that the odds of LUTS did not differ by the revised American Society for Reproductive Medicine stage (I/II vs. III/IV) or duration of endometriosis-associated symptoms.

CONCLUSION(S)

Women with surgically confirmed endometriosis were more likely to report LUTS than those without.

Gut Microbiota Exceeds Cervical Microbiota for Early Diagnosis of Endometriosis

The diagnosis of endometriosis is typically delayed by years for the unexclusive symptom and the traumatic diagnostic method. Several studies have demonstrated that gut microbiota and cervical mucus potentially can be used as auxiliary diagnostic biomarkers. However, none of the previous studies has compared the robustness of endometriosis classifiers based on microbiota of different body sites or demonstrated the correlation among microbiota of gut, cervical mucus, and peritoneal fluid of endometriosis, searching for alternative diagnostic approaches. Herein, we enrolled 41 women (control, n = 20; endometriosis, n = 21) and collected 122 well-matched samples, derived from feces, cervical mucus, and peritoneal fluid, to explore the nature of microbiome of endometriosis patients. Our results indicated that microbial composition is remarkably distinguished between three body sites, with 19 overlapped taxa. Moreover, endometriosis patients harbor distinct microbial communities versus control group especially in feces and peritoneal fluid, with increased abundance of pathogens in peritoneal fluid and depletion of protective microbes in feces. Particularly, genera of Ruminococcus and Pseudomonas were identified as potential biomarkers in gut and peritoneal fluid, respectively. Furthermore, novel endometriosis classifiers were constructed based on taxa selected by a robust machine learning method. These results demonstrated that gut microbiota exceeds cervical microbiota in diagnosing endometriosis. Collectively, this study reveals important insights into the microbial profiling in different body sites of endometriosis, which warrant future exploration into the role of microbiota in endometriosis and highlighted values on gut microbiota in early diagnosis of endometriosis.

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.

Niclosamide suppresses macrophage-induced inflammation in endometriosis†

Endometriosis is a common gynecological disease, which causes chronic pelvic pain and infertility in women of reproductive age. Due to limited efficacy of current treatment options, a critical need exists to develop new and effective treatments for endometriosis. Niclosamide is an efficacious and FDA-approved drug for the treatment of helminthosis in humans that has been used for decades. We have reported that niclosamide reduces growth and progression of endometriosis-like lesions via targeting STAT3 and NFĸB signaling in a mouse model of endometriosis. To examine the effects of niclosamide on macrophage-induced inflammation in endometriosis, a total of 29 stage III-IV endometrioma samples were used to isolate human endometriotic stromal cells (hESCs). M1 or M2 macrophages were isolated and differentiated from fresh human peripheral blood samples. Then, hESCs were cultured in conditioned media (CM) from macrophages with/without niclosamide. Niclosamide dose dependently reduced cell viability and the activity of STAT3 and NFκB signaling in hESCs. While macrophage CM stimulated cell viability in hESCs, niclosamide inhibited this stimulation. Macrophage CM stimulated the secretion of proinflammatory cytokines and chemokines from hESCs. Most of these secreted factors were inhibited by niclosamide. These results indicate that niclosamide is able to reduce macrophage-induced cell viability and cytokine/chemokine secretion in hESCs by inhibiting inflammatory mechanisms via STAT3 and/or NFκB signaling.

Current biomarkers for the detection of endometriosis

A clinically reliable non-invasive test for endometriosis is expected to reduce the diagnostic delay. Although varieties of biomarkers have been investigated for decades, and cancer antigen-125, cancer antigen-199, interleukin-6, and urocortin were the most studied ones among hundreds of biomarkers, no clinically reliable biomarkers have been confirmed so far. Some emerging technologies including “omics” technologies, molecular imaging techniques, and microRNAs are promising in solving these challenges, but their utility to detect endometriosis has yet to be verified. New combinations of researched indicators or other non-invasive methods and further exploration of the emerging technologies may be new targets and future research hotspots for non-invasive diagnosis of endometriosis. In conclusion, researches of biomarkers for the detection of endometriosis are still ongoing and may benefit from novel molecular biology, bioinformatics methods and a combination of more diverse monitoring methods. Though it will be a daunting task, the identification of a specific set of diagnostic biomarkers will undoubtedly improve the status of endometriosis.

Macrophage-derived netrin-1 contributes to endometriosis-associated pain

Background

Endometriosis-associated pain can be considered a type of neuropathic pain. Netrin-1 is an axon guidance cue that regulates axonal attraction or rejection in neural injury and regeneration. However, whether netrin-1 plays a role in endometriosis-associated pain remains unclear. This study aimed to determine the role of netrin-1 in endometriosis-related pain.

Methods

Peripheral blood, peritoneal fluid, and endometrial tissues were sampled from women with (n=37) and without endometriosis (n=23). Lipopolysaccharide (LPS) and interferon gamma (IFN-γ) were used to stimulate human monocytic cell lines (THP-1) and rat alveolar macrophage-derived cell lines (NR8383) to induce M1 phenotype macrophages. Serum netrin-1 concentrations, endometrial expression levels of netrin-1, and its receptors including deleted in colorectal cancer (DCC), A2B adenosine receptor (A2BAR), uncoordinated B receptor (UNC5B), uncoordinated C receptor (UNC5C) and Down’s syndrome cell adhesion molecule (DSCAM) were assessed. The polarization phenotypes of the peritoneal macrophages were identified by detecting the marker expression of M1/M2 macrophages via flow cytometry. The expression levels of M1 markers and netrin-1 in THP-1/NR8383 cells were determined.

Results

The expression levels of netrin-1 in serum and endometriotic lesions were significantly higher in women with endometriosis, and were positively correlated with the severity of endometriosis-associated pain. Netrin-1 was co-expressed with CD68 (a macrophage marker) in endometriotic lesions and was synthesized and secreted by THP-1 and NR8383 cells in the process of M1 polarization. In women with endometriosis, peritoneal macrophages were polarized towards the M1 phenotype. In addition, increased expression of DCC and A2BAR, and decreased expression of UNC5B, UNC5C and DSCAM were found in endometriotic lesions.

Conclusions

These results suggest that netrin-1 production by macrophages in endometriotic lesions may play an important role in endometriosis-associated pain.

Brain-derived neurotrophic factor (BDNF) expression and function in the mammalian reproductive Tract

BACKGROUND

Neurotrophins of the nerve growth factor family are soluble polypeptides that are best known for their role in nerve growth, survival and differentiation in the central nervous system. A growing body of literature shows that neurotrophins and their receptors are also expressed throughout the reproductive tract.

OBJECTIVE AND RATIONALE

Neurotrophins are key regulatory proteins in reproductive physiology during development and throughout adult life. Of the neurotrophins, the literature describing the expression and function of brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, neurotrophin receptor kinase-2 (NTRK2), has been expanding rapidly. We therefore conducted a systematic inductive qualitative review of the literature to better define the role of the BDNF in the reproductive tract. We postulate that BDNF and NTRK2 are central regulatory proteins throughout the reproductive system.

SEARCH METHODS

An electronic search of Medline (PubMed) and Web of Science for articles relating to BDNF and the reproductive system was carried out between January 2018 and February 2019.

OUTCOMES

In the ovary, BDNF expression and levels have been linked with follicle organisation during ovarian development, follicle recruitment and growth and oocyte maturation. In the endometrium, BDNF is involved in cell proliferation and neurogenesis. In contrast, literature describing the role of BDNF in other reproductive tissues is sparse and BDNF-NTRK2 signalling in the male reproductive tract has been largely overlooked. Whilst estradiol appears to be the primary regulator of BDNF expression, we also identified reports describing binding sites for glucocorticoid and myocyte enhancer factor-2, a calcium-response element through activation of an N-methyl-D-aspartate (NMDA) receptor, and aryl hydrocarbon receptor nuclear transporter protein-4 (ARNT) response elements in promoter regions of the BDNF gene. Expression is also regulated by multiple microRNAs and post-translational processing of precursor proteins and intracellular shuttling. BDNF-NTRK2 signalling is modulated through tissue specific receptor expression of either the full-length or truncated NTRK2 receptor; however, the functional importance remains to be elucidated. Dysregulation of BDNF expression and circulating concentrations have been implicated in several reproductive disorders including premature ovarian failure, endometriosis, pre-eclampsia, intra-uterine growth restriction (IUGR) and several reproductive cancers.

WIDER IMPLICATIONS

We conclude that BDNF and its receptors are key regulatory proteins central to gonadal development, ovarian regulation and uterine physiology, as well as embryo and placenta development. Furthermore, dysregulation of BDNF-NTRK2 in reproductive diseases suggests their potential role as candidate clinical markers of disease and potential therapeutic targets.

Factors affecting stability of plasma brain-derived neurotrophic factor

Circulating concentrations of brain-derived neurotrophic factor (BDNF) have been linked to cancer, neuropsychiatric, diabetes, and gynecological disorders. However, factors influencing plasma storage and subsequent BDNF quantification are incompletely understood. Therefore, the anticoagulant used in plasma separator tubes, storage-time, storage-temperature, and repeated freeze–thaw cycles on circulating BDNF concentrations was evaluated. Peripheral blood samples were collected from healthy women (n = 14) and men (n = 10) recruited prospectively from McMaster University (August 2014). Blood was collected from the cubital vein into plasma separator tubes containing five different anticoagulant systems [K2EDTA, Li-Hep, Li-Hep (gel), Na-Hep, Na-Hep (glass)], and placed on ice for transport to the lab for centrifugation. Plasma samples (n = 16) collected in K2EDTA tubes from women recruited to a previous study (April 2011 to December 2012) were used to determine the effect of multiple freeze–thaw cycles. Plasma BDNF was quantified using a commercially available ELISA kit. Plasma concentrations of BDNF were significantly affected by the type of plasma separator tube, storage-time, and number of freeze–thaw cycles. Storage temperature (− 20 vs. − 80 °C) did not significantly affect the quantity of BDNF measured as mean BDNF concentrations generally fell within our calculated acceptable change limit up to 6 months in the freezer. Our results suggest that for quantification of circulating BDNF blood collected in K2EDTA tubes and plasma stored up to 6 months at either − 20 or − 80 °C produces reproducible results that fall within an acceptable range. However, plasma samples stored beyond 6 months and repeated freeze–thaw cycles should be avoided.

Effects of Temperamental Characteristics on Depression-Anxiety Levels and the Quality of Life in Infertile Women

Objective

It is known that the risk of anxiety disorders and depression in infertile women increases and their quality of life deteriorates. Temperamental characteristics are considered as predictors of mood disorders. The aim of this study was to investigate temperamental characteristics in infertile women and their effects on depression and anxiety levels, and the quality of life, and to reveal the differences and level of relationship compared to healthy women.

Method

Fourty-four female patients with primary infertility and 30 healthy female controls were included in this study. Temperamental characteristics of the participants were assessed with Temperament Evaluation of Memphis, Pisa, Paris and San Diego-Autoquestionnaire version (TEMPS-A). Depression and anxiety severity were evaluated with Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). To evaluate the quality of life, Short Form 36 (SF-36) health survey questionnaire was also applied.

Results

Hyperthymic temperament scores were higher in infertile women than the control group (p=0.001). BDI scores were positively correlated with depressive and cyclothymic temperament scores, and BAI scores were positively correlated with depressive and anxious temperament scores. A negative correlation was found between hyperthymic temperament and BAI and BDI scores. Hyperthymic temperament scores were positively correlated with both physical and mental subdimension scores of the quality of life scale.

Conclusion

In this study, hyperthymic temperament in infertile women was shown to be protective against anxiety and depression and it also improves the quality of life. Additional studies are needed to clarify the relationship between hyperthymic temperament and ovarian hormones or other biological parameters.

Melatonin activity and receptor expression in endometrial tissue and endometriosis

STUDY QUESTION

Are melatonin receptors (melatonin receptor 1A (MR1A) and melatonin receptor 1B (MR1B)) expressed in human endometrium and endometriotic tissue, and does melatonin affect endometrial cell proliferation?

SUMMARY ANSWER

Melatonin receptors are expressed in human eutopic endometrium, endometriomas and peritoneal lesions, although to different extents, and melatonin treatment attenuated estradiol-induced endometrial epithelial cell proliferation in culture.

WHAT IS KNOWN ALREADY

Melatonin decreased endometriotic lesion volume in a rat model of endometriosis. Melatonin treatment reduced pain scores in and analgesic use by women with endometriosis.

STUDY DESIGN, SIZE, DURATION

Basic science study using human endometrial tissue and an endometrial epithelial cell line.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Measurement of melatonin receptor expression (mRNA and protein) in women with surgically confirmed endometriosis (endometrioma (n = 20) or peritoneal lesion (n = 11) alone) and women without surgical evidence of endometriosis (control, n = 15). Collection of endometrial and endometriotic tissue samples, gynecologic history and demographic information. Quantification of estradiol (1.0 nM) and melatonin (0.1 nM-1.0 μM) ± estradiol-induced endometrial epithelial cell proliferation in cultures of endometrial epithelial cells (CRL-1671) following 24 and 48 hours of culture.

MAIN RESULTS AND THE ROLE OF CHANCE

MR1A and MR1B were localized by immunohistochemistry in glandular epithelial cells of endometrial biopsies from women with and without endometriosis. Both receptors were expressed in eutopic and ectopic endometrial tissue. mRNA expression of MR1A and MR1B was significantly greater in peritoneal lesions than in either endometriomas or eutopic endometrium. However, protein expression of MR1A was decreased in peritoneal lesions compared to control eutopic endometrium, whereas MR1B expression did not differ between the groups. Melatonin (0.1 nM-1.0 μM) treatment inhibited estradiol (1.0 nM)-induced endometrial epithelial cell proliferation at 48 hours but not 24 hours of culture.

LIMITATIONS, REASONS FOR CAUTION

Beneficial effects of melatonin seen in culture have yet to be comprehensively evaluated in women with endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest that melatonin may be useful as an adjunct to current endometriosis treatments.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Canadian Institutes of Health Research (grant MOP142230 to W.G.F.). A.A.M. is supported by a resident research grant through the Physicians Services Incorporated Foundation. The authors have no conflicts of interest.

Dysregulated cytokine profile associated with biochemical premature ovarian insufficiency

Problem

Premature ovarian insufficiency (POI) imposes great challenge on female reproduction. Whether immune disturbance in ovarian environment was implicated in POI remains unclear. We aimed to characterize the cytokine profile in follicular fluid (FF) and paired serum in patients with biochemical POI (bPOI).

Method of study

Multiplex immunoassay containing 45 cytokines was performed for individual FF and paired serum samples from 35 bPOI patients and 37 matched controls. Cytokine profiles were compared between the two groups and cytokines correlated to ovarian reserve, and the rates of day‐3 good‐quality embryos were further analyzed.

Results

In FF, significantly elevated level of chemokines MIP‐1α (P = .043), CXCL8 (P = .024), IP‐10 (P = .041), and eotaxin‐1 (P = .015) as well as growth factors VEGF‐D (P = .047), BDNF (P = .043), LIF (P = .002), and bFGF (P = .046) was found in bPOI patients compared to controls. Yet RANTES manifested an opposite trend with reduced levels among bPOI patients (P = .006). All these chemokines and growth factors in FF were significantly correlated with ovarian reserve (P < .05). In paired serum, cytokine signature was not likely accordant with that in FF between two groups, except for increased IP‐10 (P = .032) in bPOI patients and its significant correlation to FSH and AFC (P < .05). Among all differentially expressed cytokines, RANTES in FF was correlated with the rate of day‐3 good‐quality embryos (P = .035).

Conclusion

Altered cytokine profile characterized by increased chemokines and growth factors was associated with early stage of POI, which may fuel the progression of the disease or even play a crucial role in the development of ovarian insufficiency.

Neurotrophins and glial cell line-derived neurotrophic factor in the ovary: physiological and pathophysiological implications

BACKGROUND

Neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4)] and glial cell line-derived neurotrophic factor (GDNF) are soluble polypeptide growth factors that are widely recognized for their roles in promoting cell growth, survival and differentiation in several classes of neurons. Outside the nervous system, neurotrophin (NT) and GDNF signaling events have substantial roles in various non-neural tissues, including the ovary.

OBJECTIVE AND RATIONALE

The molecular mechanisms that promote and regulate follicular development and oocyte maturation have been extensively investigated. However, most information has been obtained from animal models. Even though the fundamental process is highly similar across species, the paracrine regulation of ovarian function in humans remains poorly characterized. Therefore, this review aims to summarize the expression and functional roles of NTs and GDNF in human ovarian biology and disorders, and to describe and propose the development of novel strategies for diagnosing, treating and preventing related abnormalities.

SEARCH METHODS

Relevant literature in the English language from 1990 to 2018 describing the role of NTs and GDNF in mammalian ovarian biology and phenotypes was comprehensively selected using PubMed, MEDLINE and Google Scholar.

OUTCOMES

Studies have shown that the neurotrophins NGF, BDNF, NT-3 and NT-4 as well as GDNF and their functional receptors are expressed in the human ovary. Recently, gathered experimental data suggest putative roles for NT and GDNF signaling in the direct control of ovarian function, including follicle assembly, activation of the primordial follicles, follicular growth and development, oocyte maturation, steroidogenesis, ovulation and corpus luteum formation. Additionally, crosstalk occurs between these ovarian regulators and the endocrine signaling system. Dysregulation of the NT system may negatively affect ovarian function, leading to reproductive pathology (decreased ovarian reserve, polycystic ovary syndrome and endometriosis), female infertility and even epithelial ovarian cancers.

WIDER IMPLICATIONS

A comprehensive understanding of the expression, actions and underlying molecular mechanisms of the NT/GDNF system in the human ovary is essential for novel approaches to therapeutic and diagnostic interventions in ovarian diseases and to develop more safe, effective methods of inducing ovulation in ART in the treatment of female infertility.

Endometriotic inflammatory microenvironment induced by macrophages can be targeted by niclosamide†

Endometriosis causes severe chronic pelvic pain and infertility. We have recently reported that niclosamide treatment reduces growth and progression of endometriosis-like lesions and inflammatory signaling (NF${\rm \small K}$B and STAT3) in a mouse model. In the present study, we examined further inhibitory mechanisms by which niclosamide affects endometriotic lesions using an endometriotic epithelial cell line, 12Z, and macrophages differentiated from a monocytic THP-1 cell line. Niclosamide dose dependently reduced 12Z viability, reduced STAT3 and NF${\rm \small K}$B activity, and increased both cleaved caspase-3 and cleaved PARP. To model the inflammatory microenvironment in endometriotic lesions, we exposed 12Z cells to macrophage conditioned media (CM). Macrophages were differentiated from THP-1 cells using 12-O-tetradecanoylphorbol-13-acetate as M0, and then M0 macrophages were polarized into M1 or M2 using LPS/IFNγ or IL4/IL13, respectively. Conditioned media from M0, M1, or M2 cultures increased 12Z viability. This effect was blocked by niclosamide, and cell viability returned to that of CM from cells treated with niclosamide alone. To assess proteins targeted by niclosamide in 12Z cells, CM from 12Z cells cultured with M0, M1, or M2 with/without niclosamide were analyzed by cytokine/chemokine protein array kits. Conditioned media from M0, M1, and/or M2 stimulated the secretion of cytokines/chemokines from 12Z cells. Production of most of these secreted cytokines/chemokines in 12Z cells was inhibited by niclosamide. Knockdown of each gene in 12Z cells using siRNA resulted in reduced cell viability. These results indicate that niclosamide can inhibit the inflammatory factors in endometriotic epithelial cells stimulated by macrophages by targeting STAT3 and/or NF${\rm \small K}$B signaling.

Autonomic nervous system and inflammation interaction in endometriosis-associated pain

Endometriosis is a chronic inflammatory disease. Pain is the most common symptom in endometriosis. Endometriosis-associated pain is caused by inflammation, and is related to aberrant innervation. Although the specific mechanism between endometriosis-associated pain and the interaction of aberrant innervation and inflammation remains unclear, many studies have confirmed certain correlations between them. In addition, we found that some chronic inflammatory autoimmune diseases (AIDs) such as inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) share similar characteristics: the changes in dysregulation of inflammatory factors as well as the function and innervation of the autonomic nervous system (ANS). The mechanisms underlying the interaction between the ANS and inflammation have provided new advances among these disorders. Therefore, the purpose of this review is to compare the changes in inflammation and ANS in endometriosis, IBD, and RA; and to explore the role and possible mechanism of sympathetic and parasympathetic nerves in endometriosis-associated inflammation by referring to IBD and RA studies to provide some reference for further endometriosis research and treatment.

Challenges in uncovering non-invasive biomarkers of endometriosis

Endometriosis affects up to 10% of women of childbearing age, causing symptoms that can include chronic pelvic pain and reduced fertility. The symptoms are not specific to the disease and can be confused with other gynecological conditions or normal menstruation. Currently, the disease can be only definitively diagnosed by laparoscopy, as no clinically accepted biomarker exists. Biomarker discovery can either follow a hypothesis-driven approach selecting targets to be tested based on current knowledge of the disease, or take an unbiased high-throughput screening “omics” approach, such as transcriptomics or proteomics, to identify markers that are unique or elevated in accessible bodily fluids of patients with the disease. Numerous studies have been conducted using these approaches to try and identify endometriosis biomarkers, but variabilities in study design, cohort selection, and analysis, together with the fact that most studies were small-scale, have made independent validation of biomarker candidates difficult. Therefore, efforts are underway to standardize cohort selection, patient data, and sample collection to allow better cross-study comparisons. Large scale multi-center studies using this standardized approach are necessary to validate existing endometriosis biomarker candidates and uncover potential new markers. Given the complexity and heterogeneity of the disease, it is likely that a panel of biomarkers will be necessary to diagnose and categorize endometriosis.

Cross-disorder analysis of endometriosis and its comorbid diseases reveals shared genes and molecular pathways and proposes putative biomarkers of endometriosis

RESEARCH QUESTION

Women with endometriosis are considered to be at higher risk of several chronic diseases, such as autoimmune disorders, gynaecological cancers, asthma/atopic diseases and cardiovascular and inflammatory bowel diseases. Could the study of endometriosis-associated comorbidities help to identify potential biomarkers and target pathways of endometriosis?

DESIGN

A systematic review was performed to identify all possible endometriosis-associated comorbid conditions. Next, this list of disorders was coded into MeSH terms, and the gene expression profiles were downloaded from the Phenopedia database and subsequently analysed following a systems biology approach.

RESULTS

The results identified a group of 127 candidate genes that were recurrently expressed in endometriosis and its closest comorbidities and that were defined as 'endometriosis sibling disorders' (ESD). The enrichment analysis showed that these candidate genes are principally involved in immune and drug responses, hormone metabolism and cell proliferation, which are well-known hallmarks of endometriosis. The expression of ESD genes was then validated on independent sample cohorts (n = 207 samples), in which the involvement of 16 genes (AGTR1, BDNF, C3, CCL2, CD40, CYP17A1, ESR1, IGF1, IGF2, IL10, MMP1, MMP7, MMP9, PGR, SERPINE1 and TIMP2) in endometriosis was confirmed. Several of these genes harbour polymorphisms that associate to either endometriosis or its comorbid conditions.

CONCLUSIONS

The study results highlight the molecular processes underlying the aetiopathogenesis of endometriosis and its comorbid conditions, and identify putative endometriosis biomarkers.

Decreased Level of Neurotrophic Factor Neuritin 1 in Women with Ovarian Endometriosis after Receiving Gonadotropin-Releasing Hormone Agonist Treatment

This study aimed to investigate the effect of gonadotropin-releasing hormone agonist (GnRHa) treatment on the expression of neuritin 1 (NRN1) in women with ovarian endometriosis. We collected tissues and serum from women with endometriosis treated with (n = 45) or without (n = 37) GnRHa. NRN1 mRNA and protein levels were measured using qPCR and Western blot. Immunolocalization of NRN1 in endometriotic tissues was examined using immunohistochemistry. In addition, a follow-up study was carried out to monitor the serum level of NRN1 in patients before and after GnRHa treatment. Both mRNA (p = 0.046) and protein (p = 0.0155) levels of NRN1 were significantly lower in endometriotic tissues from patients receiving GnRHa treatment compared to the untreated group. Both epithelial and stromal cells of endometriotic tissues from untreated women with endometriosis exhibited stronger staining of NRN1 but not in those who were treated with GnRHa. The follow-up study showed that the serum level of the NRN1 concentration decreased significantly from 1149 ± 192.3 to 379.2 ± 80.16 pg/mL after GnRHa treatment (p = 0.0098). The expression of NRN1 was significantly lower in women with ovarian endometriosis treated with GnRHa. These results suggest that NRN1 may be a biomarker response to the effect of GnRHa treatment for patients with ovarian endometriosis.

Endometriosis Pathoetiology and Pathophysiology: Roles of Vitamin A, Estrogen, Immunity, Adipocytes, Gut Microbiome and Melatonergic Pathway on Mitochondria Regulation

Endometriosis is a common, often painful, condition that has significant implications for a woman’s fertility. Classically, endometriosis has been conceptualized as a local estrogen-mediated uterine condition driven by retrograde menstruation. However, recent work suggests that endometriosis may be a systemic condition modulated, if not driven, by prenatal processes. Although a diverse array of factors have been associated with endometriosis pathophysiology, recent data indicate that the low body mass index and decreased adipogenesis may be indicative of an early developmental etiology with alterations in metabolic function crucial to endometriosis pathoetiology.

The present article reviews the data on the pathoetiology and pathophysiology of endometriosis, suggesting key roles for alterations in mitochondria functioning across a number of cell types and body systems, including the immune system and gut microbiome. These changes are importantly regulated by decreases in vitamin A and its retinoic acid metabolites as well as increases in mitochondria estrogen receptor-beta and the N-acetylserotonin/melatonin ratio across development. This has treatment and future research implications for this still poorly managed condition, as well as for the association of endometriosis with a number of cancers.

Partners in Crime: NGF and BDNF in Visceral Dysfunction

Neurotrophins (NTs), particularly Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF), have attracted increasing attention in the context of visceral function for some years. Here, we examined the current literature and presented a thorough review of the subject. After initial studies linking of NGF to cystitis, it is now well-established that this neurotrophin (NT) is a key modulator of bladder pathologies, including Bladder Pain Syndrome/Interstitial Cystitis (BPS/IC) and Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS. NGF is upregulated in bladder tissue and its blockade results in major improvements on urodynamic parameters and pain. Further studies expanded showed that NGF is also an intervenient in other visceral dysfunctions such as endometriosis and Irritable Bowel Syndrome (IBS). More recently, BDNF was also shown to play an important role in the same visceral dysfunctions, suggesting that both NTs are determinant factors in visceral pathophysiological mechanisms. Manipulation of NGF and BDNF improves visceral function and reduce pain, suggesting that clinical modulation of these NTs may be important; however, much is still to be investigated before this step is taken. Another active area of research is centered on urinary NGF and BDNF. Several studies show that both NTs can be found in the urine of patients with visceral dysfunction in much higher concentration than in healthy individuals, suggesting that they could be used as potential biomarkers. However, there are still technical difficulties to be overcome, including the lack of a large multicentre placebo-controlled studies to prove the relevance of urinary NTs as clinical biomarkers.

The nervous system and genomics in endometriosis

Endometriosis is a gynaecological disease that occurs in approximately 10% to 15% of women of reproductive age and up to 47% of infertile women. The presence of implants of endometrial-like glands and stroma outside the uterus, characteristic of this disease, induce a wide variety of symptoms, mainly pelvic pain and infertility. Women suffering from this condition experience great distress, which significantly affects their quality of life. Numerous studies attempting to decipher the pathogenic mechanisms of endometriosis have been conducted around the world, yet its aetiology still remains unknown. It is widely believed that in women with endometriosis, the endometrium has characteristic features that allow the formation of implants once fragments have entered the peritoneal cavity through retrograde menstruation. Furthermore, a strong genetic tendency to develop the disease has been reported among patients and first-degree relatives. Thanks to the recent technological advances achieved in genomics and bioinformatics, a number of studies have had the potential to analyse several aspects of the pathogenesis of endometriosis from a genetic perspective. Due to the recent identification of nerve fibres in the endometrium of women with endometriosis, research on the neurogenesis of the disease has increased in the past few years. However, the genetic aspects of nerve growth in endometriosis have not been analysed in depth and further research providing important insights into the mechanisms that mediate pain in affected patients has the potential to contribute substantially to the future management of the condition.

Perineural invasion in endometriotic lesions contributes to endometriosis-associated pain

Purpose

Recent studies have shown that abnormal distribution of pelvic nerves contributes to endometriosis-associated pain. However, the relationship between neurogenesis and pain severity in endometriosis still remains uncertain, which makes it an enigma for both gynecologists as well as neuropathologists. In this study, we tried to explore a special phenomenon, perineural invasion (PNI), in deep infiltrating endometriosis (DIE) and investigated the correlation between PNI- and DIE-associated pain.

Patients and methods

The study was conducted in the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Sun Yat-sen University from June 2012 to January 2015. In total, 64 patients with DIE were enrolled. They received laparoscopically surgical resection of endometriotic lesions. The Kruskal–Wallis and Mann–Whitney tests were used for comparisons of enumeration data. Spearman rank correlation was used for linear analysis.

Results

Immunohistochemical analysis demonstrated that PNI was commonly found in DIE lesions. Patients were divided into PNI (+) group and PNI (−) group. The visual analog scale scores of dysmenorrhea, dyspareunia, and chronic pelvic pain were higher in PNI (+) group than in PNI (−) group. Also, we found significantly increased density of newly formed nerve fibers as well as microvessels in lesions of PNI (+) group. Further, double immunofluorescence showed a closely spatial nerve–vessel network in the endometriotic lesion of PNI (+) group. More importantly, correlation analysis revealed positive relation between the density of newly formed nerve fibers in the lesion and the density of microvessels in lesions of PNI (+) group.

Conclusion

This study suggests that PNI in endometriotic lesions plays an important role in endometriosis-associated pain, mainly through a mechanism named “neuroangiogenesis”.

The Expression and Cellular Localisation of Neurotrophin and Neural Guidance Molecules in Peritoneal Ectopic Lesions

Endometriosis is a gynaecological disorder characterised by the presence of endometrial-like tissue outside the uterus. It affects 10-15% of women during their reproductive age. The existence of close and complex relationship between chronic pelvic pain and endometriosis are widely recognised. However, the mechanisms of pain generation in women with endometriosis remain poorly understood. Immunohistochemistry was used to assess the density of nerve fibres stained with protein gene product 9.5 (PGP9.5) and the expression of various neurotrophins including glial cell derived neurotrophic factor (GDNF), persephin, neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) and neuronal guidance molecules semaphorin 3E and Slit-2 and their receptors Plexin-D1 and Robo4 in peritoneal ectopic lesions from women with endometriosis and uninvolved peritoneum samples. Neurotrophins and neuronal guidance molecules and their receptors are synthesised in situ within peritoneal ectopic lesion which suggest their role in facilitating and maintaining the growth of nerve fibres. These molecules were found to be overall most highly expressed in the glands of endometriotic peritoneal lesions. In addition, the presence of ectopic lesions within the peritoneal cavity may affect the environment; in turn, the peritoneum altered appeared to play a role in the growth of nerve fibres and their development and maintenance in peritoneal lesions. Through exploring different neuronally active factors in and around ectopic lesions which may be contributing to pain generation, this study provides an insight and better understanding of the pain mechanisms associated with peritoneal endometriosis.

IL-1β Stimulates Brain-Derived Neurotrophic Factor Production in Eutopic Endometriosis Stromal Cell Cultures: A Model for Cytokine Regulation of Neuroangiogenesis

Endometriosis implants are comprised of glandular and stromal elements, macrophages, nerves, and blood vessels and are commonly accompanied by pelvic pain. We propose that activated macrophages are recruited to and infiltrate nascent lesions, where they secrete proinflammatory cytokines, promoting the production of chemokines, neurotrophins, and angiogenic growth factors that sustain an inflammatory microenvironment. Immunohistochemical evaluation of endometriosis lesions reveals in situ colocalization of concentrated macrophages, brain-derived neurotrophic factor (BDNF), and nerve fibers. These observations were coupled with biochemical analyses of primary eutopic endometriosis stromal cell (EESC) cultures, which allowed defining potential pathways leading to the neuroangiogenic phenotype of these lesions. Our findings indicate that IL-1β potently (EC₅₀ = 7 ± 2 ng/mL) stimulates production of EESC BDNF at the mRNA and protein levels in an IL-1 receptor-dependent fashion. Selective kinase inhibitors demonstrate that this IL-1β effect is mediated by c-Jun N-terminal kinase (JNK), NF-κB, and mechanistic target of rapamycin signal transduction pathways. IL-1β regulation of regulated on activation normal T cell expressed and secreted (RANTES), a prominent EESC chemokine, also relies on JNK and NF-κB. An important clinical implication of the study is that interference with BDNF and RANTES production, by selectively targeting the JNK and NF-κB cascades, may offer a tractable therapeutic strategy to mitigate the pain and inflammation associated with endometriosis.

Evaluation of Circulating Endometrial Cells as a Biomarker for Endometriosis

BACKGROUND

Circulating endometrial cells (CECs) have been reported to be present in the peripheral blood of women with endometriosis (EM), providing clear and specific evidence of the presence of ectopic lesions. In this study, we established a method with a high detection rate of CECs, assessed the diagnostic value of CECs for EM and compared with serum CA125, and proposed a hypothesis for the pathogenesis of EM from the new perspective of CECs.

METHODS

The participants were enrolled prospectively from October 2015 to July 2016. The peripheral blood samples were collected from 59 participants, and the blood cells were isolated for immunofluorescence staining via microfluidic chips. The cells that were positive for vimentin/cytokeratin and estrogen/progesterone receptor and negative for CD45 were identified as CECs. The serum CA125 level was tested with electrochemiluminescence immunoassay.

RESULTS

The detection rate of CECs reached 89.5% (17/19) in the EM group, which was significantly higher than that of the control group (15.0% [6/40], P < 0.001) and was independent of menstrual cycle phases. Furthermore, a positive CEC assay detected 4/5 cases of Stage I-II EM. In contrast, a positive CA125 test had limited value in detecting EM (13/19, 68.4%) and detected only one case of Stage I-II EM.

CONCLUSION

CECs are promising biomarkers for EM with great potential for a noninvasive diagnostic assay.

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.

Increased serum levels of mBDNF in women with minimal and mild endometriosis have no predictive power for the disease

The objective of our pilot clinical, prospective study was to determine the serum levels of mature brain-derived neurotrophic factor, in of women with endometriosis and controls and explore whether mature brain-derived neurotrophic factor is a potential biomarker for the disease. The patients were selected from the Endometriosis Marker Austria prospective cohort study conducted at the tertiary referral certified Endometriosis Center of the Medical University of Vienna. All women underwent laparoscopic surgery because there was a suspicion of endometriosis, or the women had pelvic pain, adnexal cysts, unexplained infertility, or uterine fibroids. Our main outcome parameter was total levels of mature brain-derived neurotrophic factor in serum, measured using ELISA. Our results show that serum levels of mature brain-derived neurotrophic factor are significantly higher in women with endometriosis compared to women without endometriosis. The mean serum protein levels are significantly higher in women with rAFS stage I and II endometriosis, whereas no difference was found in women with stage III and IV endometriosis and controls. Postoperative follow-up at 6-10 weeks revealed that surgical intervention leads to equilibration of the levels of secreted mature brain-derived neurotrophic factor between women with and without endometriosis. The difference between serum mature brain-derived neurotrophic factor levels of women with endometriosis compared to women without endometriosis is independent of menstrual cycle phase and overall self-reported pelvic pain. ROC-curve analysis showed that, the mature brain-derived neurotrophic factor is not a useful biomarker for endometriosis. In conclusion, although women with stage I and II endometriosis have increased levels of mature brain-derived neurotrophic factor in serum compared to controls, the difference is not predictive for the disease. Impact statement Endometriosis is a disease that can have a significant impact on the quality of life of affected women. The gold standard for diagnosis to this day remains visualization through laparoscopic surgery with histological verification. Current studies are attempting to find a biomarker with high sensitivity and specificity, which would bypass the surgery-associated risks and would significantly reduce costs. In an attempt to elucidate whether mature serum BDNF can serve as diagnostic marker for the disease, we compared the levels of the protein in women with endometriosis to endometriosis-free controls. While our results showed that serum concentrations of the mature protein were significantly higher in women with endometriosis, we did not find this marker to have the sensitivity or specificity needed in order to allow a reliable diagnosis.

Redox regulation of microRNAs in endometriosis-associated pain

Endometriosis is a chronic, painful condition with unknown etiology. A differential expression of microRNAs in the endometriotic tissues from women with endometriosis with pain compared to those without suggested a plausible role for miRNA or epigenetic mechanisms in the etiology of endometriotic pain. The peritoneal milieu is involved in maintenance of endometriotic lesion and nociception. We recently showed the mechanistic role for oxidized-lipoproteins (ox-LDLs) present in peritoneal fluid (PF) in endometriosis and pain. We explored the possibility of ox-LDLs modulating the expression of miRNAs in a manner similar to PF from women with endometriosis. Expression levels of miRNAs and their predicted nociceptive and inflammatory targets were determined in PF and ox-LDL treated human endometrial cell-lines. Samples from IRB-approved and consented patients with and without endometriosis or pain were used. These were compared to endometrial cell-lines treated with various forms of oxidized-lipoproteins. RNA (including miRNAs) were isolated from treated endometrial cells and expression levels were determined using commercial miRNome arrays. Cell lysates were used in immunoblotting for inflammatory proteins using a protein array. Twenty miRNAs including isoforms of miR-29, miR-181 and let-7 were mutually differentially expressed in cells treated with PF from endometriosis patients with pain and those treated with ox-LDL components. The ox-LDLs and endo-PF treatment also produced significant overexpression of microRNA predicted target genes nerve growth factor, interleukin-6 and prostaglandin E synthase and overexpression of their downstream protein targets Mip1α and MCP1. This study showed similarities between miRNA regulation in PF from endometriotic women and ox-LDLs present in abundance in the PF of these women. Key miRNAs responsible for targeting nociceptive and inflammatory molecules were downregulated in the presence of ox-LDLs and endo-PF, thus playing a role in the etiology of endometriotic pain. These redox-sensitive miRNAs can be of potential use as targets in the treatment of endometriosis-associated pain.

Macrophage and nerve interaction in endometriosis

Dysregulation of the immune system in endometriotic milieus has been considered to play a pivotal role in the pathogenesis of endometriosis. Macrophage recruitment and nerve fiber infiltration are the two major characteristics of this aberrant immune environment. First, the recruitment of macrophages and their polarization phenotype within the endometriotic lesion have been demonstrated to facilitate the development and maintenance of endometriosis. M1 phenotype of macrophages has the capacity to secrete multiple cytokines for inflammatory response, while M2 macrophage possesses an opposite property that can mediate the process of immunosuppression and neuroangiogenesis. Upon secretion of multiple abnormal signal molecules by the endometriotic lesion, macrophages could alter their location and phenotype. These changes facilitate the accommodation of the aberrant microenvironment and the exacerbation of disease progression. Second, the infiltration of nerve fibers and their abnormal distribution are proved to be involved in the generation of endometriosis-associated pain and inflammatory response. An imbalance in sensory and sympathetic innervation and the abnormal secretion of different cytokines could mediate neurogenesis and subsequent peripheral neuroinflammation in endometriosis. Although endometriosis creates an inflammatory milieu promoting macrophage infiltration and an imbalanced innervation, interaction between macrophages and nerve fibers in this process remains unknown. The aim of this review is to highlight the role of macrophage and nerve interaction in endometriosis, where macrophage recruitment and neurogenesis can be the underlying mechanism of neuroinflammation and pathogenesis of endometriosis.

Plasma brain-derived neurotrophic factor in women with pelvic pain: a potential biomarker for endometriosis?

AIM

To test whether plasma BDNF levels are useful to predict the presence of endometriosis in women with pelvic pain.

PATIENTS & METHODS

Prospective cross-sectional study including 67 consecutive women aged 24-49 years, scheduled for laparoscopy due to chronic pelvic pain. Preoperative plasma samples were assayed for BDNF using a commercial enzyme immunoassay.

RESULTS

Women with ovarian endometrioma had higher preoperative plasma BDNF (1063 ± 157 pg/ml) compared with women with other benign ovarian tumors (537 ± 131 pg/ml, F = 2.53; p = 0.02). However, plasma BDNF levels were not helpful to indicate the presence of peritoneal or deep infiltrating endometriosis. Plasma BDNF levels were positively correlated with the severity of pelvic pain (r = 0.489; p < 0.0001).

CONCLUSION

Plasma BDNF might be a biomarker of ovarian endometrioma but not a useful diagnostic marker to detect other forms of endometriosis in women with painful symptoms.

Biomarkers in endometriosis: challenges and opportunities

Endometriosis is a debilitating gynecologic disease affecting millions of women across the world, with symptoms including dysmenorrhea, chronic pelvic pain, and infertility. Theorized to stem from the phenomenon of retrograde menstruation, the diagnosis of endometriosis is typically delayed by 8-10 years owing to misinterpretation of symptoms as common menstrual cramps in adolescent girls and young women. With increased incidence of endometriosis in young girls correlated with earlier menarche, the development of diagnostic biomarkers is imperative for diagnosing and treating women afflicted with endometriosis as early as we can. In the past few years, multiple reviews highlighted the list of potential diagnostic candidates in peritoneal fluid, blood, urine, and endometrial biopsies from endometriosis patients in different stages of disease and menstrual cycle. In this review, we explore the opportunities and challenges facing the field of diagnostic biomarkers for endometriosis. We highlight the importance of eutopic endometrium as a source of potential diagnostic biomarkers by looking at the expression levels of noncoding RNA in tissue as well as in blood. Finally, we discuss some of the challenges that hinder our efforts in validating candidate diagnostic biomarkers for endometriosis.

Endometriosis-Derived Thromboxane A2 Induces Neurite Outgrowth

Hyperinnervation in endometriosis is now well documented, but so far only a few neurotrophins have been identified. Since endometriotic stromal cells secrete thromboxane A2 (TXA₂), we sought to determine whether TXA₂, derived from endometriotic stromal cells, induces neurite outgrowth. Using primary sensory neurons derived from rat dorsal root ganglia (DRG) and ectopic endometrial stromal cells (EESCs) derived from human ovarian endometrioma tissues, we treated the primary neurons with different concentrations of U-46619, a stable TXA₂ mimetic, and performed a neuronal growth assay. The primary neurons were also cocultured with a vehicle, nerve growth factor (NGF, serving as a positive control), the supernatant of EESC culture medium, or the supernatant of EESCs pretreated with ozagrel, a thromboxane synthase inhibitor, and a neuronal growth assay was performed. The total neurite length was evaluated through immunofluorescence microscopy. We found that U-46619 significantly increased the neurite outgrowth in DRG neurons in a concentration-dependent fashion ( P < .001). It also increased the number of neurite ends in a concentration-dependent fashion. Ozagrel treatment alone had no effect on the neurite growth ( P > .05), and the treatment with the supernatant of EESCs induced neurite outgrowth just as potently as that treated with NGF (positive control; P > .05). Remarkably, treatment with the EESC supernatant increased the neurite outgrowth by nearly 3-fold as compared with the control ( P < .01), but the pretreatment with ozagrel abolished the stimulatory effect of the EESC by 31.3% ( P < .05). These findings indicate that EESCs potently induce neurite outgrowth, and endometriosis-derived TXA₂ is responsible, at least in part, for this neurotrophic effect.

Localization of TrkB and p75 receptors in peritoneal and deep infiltrating endometriosis: an immunohistochemical study

BACKGROUND

The roles of the neurotrophins NGF (Neurotrophic growth factor) and BDNF (brain-derived neurotrophic factor) in neuronal growth and development are already known. Meanwhile, the neurotrophin receptors TrkA (tropomyosin related kinase A), TrkB, and p75 are important for determining the fate of cells. In endometriosis, this complex system has not been fully elucidated yet. The aim of this study was to evaluate the expression and location of these neurotrophins and their receptors in peritoneal (PE) and deep infiltrating endometriotic (DIE) tissues and to measure and compare the density of nerve fibers in the disease subtypes.

METHODS

PE lesions (n = 20) and DIE lesions (n = 22) were immunostained and analyzed on serial slides with anti-BDNF, -NGF, -TrkA, -TrkB, -p75,-protein gene product 9.5 (PGP9.5, intact nerve fibers) and -tyrosine hydroxylase (TH, sympathetic nerve fibers) antibodies.

RESULT

There was an equally high percentage (greater than 75 %) of BDNF-positive immunostaining cells in both PE and DIE. TrkB (major BDNF receptor) and p75 showed a higher percentage of immunostaining cells in DIE compared to in PE in stroma only (p < 0.014, p < 0.027, respectively). Both gland and stroma of DIE lesions had a lower percentage of NGF-positive immunostaining cells compared to those in PE lesions (p < 0.01 and p < 0.01, respectively), but there was no significant reduction in immunostaining of TrkA in DIE lesions. There was no difference in the mean density of nerve fibers stained with PGP9.5 between PE (26.27 ± 17.32) and DIE (28.19 ± 33.15, p = 0.8). When we performed sub-group analysis, the density of nerves was significantly higher in the bowel DIE (mean 57.33 ± 43.9) than in PE (mean 26.27 ± 17.32, p < 0.01) and non-bowel DIE (mean 14.6. ± 8.6 p < 0.002).

CONCLUSIONS

While the neurotrophin BDNF is equally present in PE and DIE, its receptors TrkB and p75 are more highly expressed in DIE and may have a potential role in the pathophysiology of DIE, especially in promotion of cell growth. BDNF has a stronger binding affinity than NGF to the p75 receptor, likely inducing sympathetic nerve axonal pruning in DIE, resulting in the lower nerve fiber density seen.

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

Endometriosis is a common, complex gynecologic disorder characterized by the presence of endometrial-like tissues at extrauterine sites. Elevation in protein and lipid mediators of inflammation including oxylipins and cytokines within the peritoneum characterize the inflamed pelvic region and may contribute to the survival and growth of displaced endometrial tissues. The presence of a clinically silent but molecularly detectable systemic inflammation in endometriosis has been proposed. Thus, we examined serum oxylipin and immunomodulatory protein levels in 103 women undergoing laparoscopy to evaluate systematically any involvement in systemic pathophysiological inflammation in endometriosis. Oxylipin levels were similar between women with and without endometriosis. Stratification by menstrual phase or severity did not offer any difference. Women with ovarian endometriosis had significantly lower 12-HETE relative to peritoneal endometriosis (−50.7%). Serum oxylipin levels were not associated with pre-operative pain symptoms. Changes to immunomodulatory proteins were minimal, with IL-12(p70), IL-13 and VEGF significantly lower in mild endometriotic women compared to non-endometriotic women (−39%, −54% and −76% respectively). Verification using C-reactive protein as a non-specific marker of inflammation further showed similar levels between groups. The implications of our work suggest pro-inflammatory mediators in the classes studied may have potentially limited value as circulating biomarkers for endometriosis, suggesting of potentially tenuous systemic inflammation in endometriosis.