Altered expression of activin, cripto, and follistatin in the endometrium of women with endometrioma

Endometriosis: Cellular and Molecular Mechanisms Leading to Fibrosis

Endometriosis is a chronic inflammatory condition affecting women of reproductive age. A relevant feature of endometriosis is the presence of fibrotic tissue inside and around the lesions, thus contributing to the classic endometriosis-related symptoms, pain, and infertility. The molecular mechanisms responsible for the development of fibrosis in endometriosis are not yet defined. The present review aimed to examine the biological mechanisms and signalling pathways involved in fibrogenesis of endometriotic lesions, highlighting the difference between deep infiltrating and ovarian endometriosis. The main cell types involved in the development of fibrosis are platelets, myofibroblasts, macrophages, and sensory nerve fibers. Members of the transforming growth factor (TGF) -β family, as well as the receptor Notch, or the bioactive sphingolipid sphingosine 1-phosphate (S1P), play a role in the development of tissue fibrosis, resulting in their metabolism and/or their signalling pathways altered in endometriotic lesions. It is relevant the knowledge of the molecular mechanisms that guide and support fibrosis in endometriosis, to identify new drug targets and provide new therapeutic approaches to patients.

Myostatin: a multifunctional role in human female reproduction and fertility - a short review

Myostatin (MSTN) is member of the transforming growth factor β (TGF-β) superfamily and was originally identified in the musculoskeletal system as a negative regulator of skeletal muscle growth. The functional roles of MSTN outside of the musculoskeletal system have aroused researchers' interest in recent years, with an increasing number of studies being conducted in this area. Notably, the expression of MSTN and its potential activities in various reproductive organs, including the ovary, placenta, and uterus, have recently been examined. Numerous studies published in the last few years demonstrate that MSTN plays a critical role in human reproduction and fertility, including the regulation of follicular development, ovarian steroidogenesis, granule-cell proliferation, and oocyte maturation regulation. Furthermore, findings from clinical samples suggest that MSTN may play a key role in the pathogenesis of several reproductive disorders such as uterine myoma, preeclampsia (PE), ovary hyperstimulation syndrome (OHSS), and polycystic ovarian syndrome (PCOS). There is no comprehensive review regarding to MSTN related to the female reproductive system in the literature. This review serves as a summary of the genes in reproductive medicine and their potential influence. We summarized MSTN expression in different compartments of the female reproductive system. Subsequently, we discuss the role of MSTN in both physiological and several pathological conditions related to the female fertility and reproduction-related diseases.

Hormonal treatments for endometriosis: The endocrine background

Endometriosis is a benign uterine disorder characterized by menstrual pain and infertility, deeply affecting women's health. It is a chronic disease and requires a long term management. Hormonal drugs are currently the most used for the medical treatment and are based on the endocrine pathogenetic aspects. Estrogen-dependency and progesterone-resistance are the key events which cause the ectopic implantation of endometrial cells, decreasing apoptosis and increasing oxidative stress, inflammation and neuroangiogenesis. Endometriotic cells express AMH, TGF-related growth factors (inhibin, activin, follistatin) CRH and stress related peptides. Endocrine and inflammatory changes explain pain and infertility, and the systemic comorbidities described in these patients, such as autoimmune (thyroiditis, arthritis, allergies), inflammatory (gastrointestinal/urinary diseases) and mental health disorders.The hormonal treatment of endometriosis aims to block of menstruation through an inhibition of hypothalamus-pituitary-ovary axis or by causing a pseudodecidualization with consequent amenorrhea, impairing the progression of endometriotic implants. GnRH agonists and antagonists are effective on endometriosis by acting on pituitary-ovarian function. Progestins are mostly used for long term treatments (dienogest, NETA, MPA) and act on multiple sites of action. Combined oral contraceptives are also used for reducing endometriosis symptoms by inhibiting ovarian function. Clinical trials are currently going on selective progesterone receptor modulators, selective estrogen receptor modulators and aromatase inhibitors. Nowadays, all these hormonal drugs are considered the first-line treatment for women with endometriosis to improve their symptoms, to postpone surgery or to prevent post-surgical disease recurrence. This review aims to provide a comprehensive state-of-the-art on the current and future hormonal treatments for endometriosis, exploring the endocrine background of the disease.

The Potential of Non-Invasive Biomarkers for Early Diagnosis of Asymptomatic Patients with Endometriosis

Endometriosis is a disease that affects women of reproductive age and has a significantly negative impact on their well-being. The main symptoms are dysmenorrhoea, chronic pelvic pain and infertility. In many patients the diagnostic process is very long and can take up to 8-12 years. Laparoscopy, an invasive method, is still necessary to confirm the diagnosis. Therefore, development of more effective diagnostic markers appears to be of the utmost importance for early diagnosis of endometriosis and provision of appropriate treatment. From a clinical point of view, detection of early-stage endometriosis in asymptomatic patients is an ideal situation since early diagnosis of endometriosis may delay the onset of symptoms as well as prevent progression and complications. In the meantime, Cancer Antigen 125 (CA-125) is still the most frequently studied and used marker. Other glycoproteins, growth factors and immune markers seem to play an important role. However, the search for an ideal endometriosis marker is still underway. Further studies into the pathogenesis of endometriosis will help to identify biomarkers or sets of biomarkers with the potential to improve and speed up the diagnostic process in a non-invasive way.

Sphingosine 1-phosphate receptors are dysregulated in endometriosis: possible implication in transforming growth factor β-induced fibrosis

OBJECTIVE

To study the molecular mechanisms involved in the appearance of the fibrotic trait in endometriosis by investigating whether the signaling pathway of the bioactive sphingolipid sphingosine 1-phosphate (S1P) was altered in endometriotic lesions.

DESIGN

Case-control laboratory study.

SETTING

University research institute and university hospital.

PATIENT(S)

A total of 75 women, with and without endometriosis, were included in the study.

INTERVENTIONS(S)

Endometrial samples were obtained from women affected (n = 15 endometrioma [OMA]; n = 30 deep infiltrating endometriosis [DIE]) and not (n = 30) by endometriosis by means of laparoscopic surgery, followed by clinical and imaging investigation and checking for the expression of fibrosis markers and genes implicated in S1P metabolism and signaling by means of real-time polymerase chain reaction.

MAIN OUTCOME MEASURE(S)

The role of the S1P signaling axis in endometriosis-associated fibrosis was studied in vitro, where RNA interference approaches were used to investigate if S1P synthesis by sphingosine kinases (SKs) and specific S1P receptors (S1PRs) are implicated in the profibrotic effect of the cytokine transforming growth factor (TGF) β1.

RESULT(S)

mRNA expression analysis of S1PR demonstrated a deep dysregulation of S1P signaling in endometriosis, characterized by increased expression of fibrosis markers: S1P₁ was transcriptionally more expressed in OMA, and S1P₃ and S1P₅ mRNA levels were significantly augmented in both OMA and DIE. SK1 and its activating protein calcium- and integrin-binding protein 1 (CIB1) were significantly up-regulated in OMA and DIE. A crucial role for the SK/S1PR axis in the profibrotic effect elicited by TGFβ1 was highlighted in vitro.

CONCLUSION(S)

The S1P signaling axis may represent a useful biomarker or innovative pharmacologic target for endometriosis.

Endometrial biomarkers for the non-invasive diagnosis of endometriosis

BACKGROUND

About 10% of reproductive-aged women suffer from endometriosis, which is a costly, chronic disease that causes pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but it is expensive and carries surgical risks. Currently, there are no non-invasive tests available in clinical practice that accurately diagnose endometriosis. This is the first diagnostic test accuracy review of endometrial biomarkers for endometriosis that utilises Cochrane methodologies, providing an update on the rapidly expanding literature in this field.

OBJECTIVES

To determine the diagnostic accuracy of the endometrial biomarkers for pelvic endometriosis, using a surgical diagnosis as the reference standard. We evaluated the tests as replacement tests for diagnostic surgery and as triage tests to inform decisions to undertake surgery for endometriosis.

SEARCH METHODS

We did not restrict the searches to particular study designs, language or publication dates. To identify trials, we searched the following databases: CENTRAL (2015, July), MEDLINE (inception to May 2015), EMBASE (inception to May 2015), CINAHL (inception to April 2015), PsycINFO (inception to April 2015), Web of Science (inception to April 2015), LILACS (inception to April 2015), OAIster (inception to April 2015), TRIP (inception to April 2015) and ClinicalTrials.gov (inception to April 2015). We searched DARE and PubMed databases up to April 2015 to identify reviews and guidelines as sources of references to potentially relevant studies. We also performed searches for papers recently published and not yet indexed in the major databases. The search strategies incorporated words in the title, abstract, text words across the record and the medical subject headings (MeSH).

SELECTION CRITERIA

We considered published peer-reviewed, randomised controlled or cross-sectional studies of any size that included prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE).

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from each study and performed a quality assessment. For each endometrial diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis and calculated the estimates of sensitivity and specificity. We considered two or more tests evaluated in the same cohort as separate data sets. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient data were available. The predetermined criteria for a clinically useful test to replace diagnostic surgery was one with a sensitivity of 94% and a specificity of 79%. The criteria for triage tests were set at sensitivity at or above 95% and specificity at or above 50%, which in case of negative results rules out the diagnosis (SnOUT test) or sensitivity at or above 50% with specificity at or above 95%, which in case of positive result rules in the diagnosis (SpIN test).

MAIN RESULTS

We included 54 studies involving 2729 participants, most of which were of poor methodological quality. The studies evaluated endometrial biomarkers either in specific phases of the menstrual cycle or outside of it, and the studies tested the biomarkers either in menstrual fluid, in whole endometrial tissue or in separate endometrial components. Twenty-seven studies evaluated the diagnostic performance of 22 endometrial biomarkers for endometriosis. These were angiogenesis and growth factors (PROK-1), cell-adhesion molecules (integrins α3β1, α4β1, β1 and α6), DNA-repair molecules (hTERT), endometrial and mitochondrial proteome, hormonal markers (CYP19, 17βHSD2, ER-α, ER-β), inflammatory markers (IL-1R2), myogenic markers (caldesmon, CALD-1), neural markers (PGP 9.5, VIP, CGRP, SP, NPY, NF) and tumour markers (CA-125). Most of these biomarkers were assessed in single studies, whilst only data for PGP 9.5 and CYP19 were available for meta-analysis. These two biomarkers demonstrated significant diversity for the diagnostic estimates between the studies; however, the data were too limited to reliably determine the sources of heterogeneity. The mean sensitivities and specificities of PGP 9.5 (7 studies, 361 women) were 0.96 (95% confidence interval (CI) 0.91 to 1.00) and 0.86 (95% CI 0.70 to 1.00), after excluding one outlier study, and for CYP19 (8 studies, 444 women), they were were 0.77 (95% CI 0.70 to 0.85) and 0.74 (95% CI 0.65 to 84), respectively. We could not statistically evaluate other biomarkers in a meaningful way. An additional 31 studies evaluated 77 biomarkers that showed no evidence of differences in expression levels between the groups of women with and without endometriosis.

AUTHORS' CONCLUSIONS

We could not statistically evaluate most of the biomarkers assessed in this review in a meaningful way. In view of the low quality of most of the included studies, the findings of this review should be interpreted with caution. Although PGP 9.5 met the criteria for a replacement test, it demonstrated considerable inter study heterogeneity in diagnostic estimates, the source of which could not be determined. Several endometrial biomarkers, such as endometrial proteome, 17βHSD2, IL-1R2, caldesmon and other neural markers (VIP, CGRP, SP, NPY and combination of VIP, PGP 9.5 and SP) showed promising evidence of diagnostic accuracy, but there was insufficient or poor quality evidence for any clinical recommendations. Laparoscopy remains the gold standard for the diagnosis of endometriosis, and using any non-invasive tests should only be undertaken in a research setting. We have also identified a number of biomarkers that demonstrated no diagnostic value for endometriosis. We recommend that researchers direct future studies towards biomarkers with high diagnostic potential in good quality diagnostic studies.

Clinical significance of serum follistatin levels in the diagnosis of ovarian endometrioma and benign ovarian cysts

OBJECTIVE

To determine the clinical significance of serum follistatin levels in women with an ovarian endometrioma.

MATERIALS AND METHODS

This is a prospective study of 89 women, 56 with an ovarian endometrioma (endometrioma group) and 33 with a benign ovarian cyst (control group) who underwent laparoscopic excision. Age, parity, body mass index, serum CA-125, serum CA 19-9, and serum follistatin levels were determined for all participants and evaluated as potential prognostic factors prior to laparoscopic cystectomy.

RESULTS

There were no significant differences in demographic factors between the endometrioma group and the control group. However, serum follistatin levels were significantly higher in the endometrioma group (9350 ± 895 pg/mL vs. control group 725 ± 72 pg/mL, p < 0.05). The optimal diagnostic cut-off values (sensitivity and specificity) of CA-125, CA 19-9, and follistatin for ovarian endometrioma were 23.2 IU/mL (82.14% and 72.73%), 30.14 IU/mL (45.28% and 87.50%), and 2350 pg/mL (53.7% and 60.61%), respectively.

CONCLUSION

Despite the increased serum follistatin levels in patients with ovarian endometrioma, CA-125 was determined to be a more sensitive and specific marker than follistatin for the diagnosis of ovarian endometrioma and endometriosis.

The role of TGFβ superfamily members in the pathophysiology of endometriosis

The transforming growth factor-beta (TGFβ) superfamily comprises over 30 dimeric proteins with conserved structures, which play important roles in the control of cellular proliferation, differentiation and apoptosis. These proteins are expressed and finely regulated in human endometrium during the menstrual cycle, which is consistent with their effects on endometrial cell proliferation and tissue remodeling. This review is focused on summarizing the role of key members of the TGFβ superfamily in the pathophysiology of endometriosis. Evidence suggests that TGFβ, activins, inhibins, nodal, bone morphogenetic proteins, growth differentiation factors, and anti-Müllerian hormone are produced by endometriotic lesions and could be involved in the establishment and progression of the disease. Their receptors and signaling pathways may also be altered in the presence of endometriosis and may be potential targets to the development of therapeutic agents.

BMP-4 increases activin A gene expression during osteogenic differentiation of mouse embryonic stem cells

Activin A is a growth factor released by mature osteoblasts that has a critical effect on bone formation. We investigated the effect of bone morphogenetic protein (BMP)-4 on activin A gene expression during in vitro osteogenic differentiation of mouse embryonic stem (ES) cells. Embryoid bodies were cultured in retinoic acid (RA) for three days and then without RA for two days. Seeded cells received osteogenic medium with β-glycerophosphate, L-ascorbic acid 2-phosphate and dexamethasone during 19 days, with or without BMP-4. Six independent experiments were carried out. Real-time PCR was used to detect gene expression of activin A, Oct-4, Nanog, osteocalcin, RUNX2 and bone alkaline phosphatase. Immunofluorescence was used to co-localize activin A with the undifferentiation marker stage-specific embryonic antigen 1. Cells treated with BMP-4 had an increased gene expression of activin A, osteocalcin and bone alkaline phosphatase (p < 0.05). In conclusion, BMP-4 increases activin A gene expression during mouse ES cell differentiation into bone precursors.

Expression of Nodal, Cripto, SMAD3, phosphorylated SMAD3, and SMAD4 in the proliferative endometrium of women with endometriosis

BACKGROUND

Nodal is a growth factor of the transforming growth factor β superfamily that is expressed in high turnover tissues, such as the human endometrium, and in several malignancies. The effects of Nodal are modulated by the coreceptor Cripto and mediated by SMAD proteins. This study evaluated the gene and protein expression of Nodal, Cripto, total and phosphorylated (p) SMAD3, and SMAD4 in the proliferative endometrium of women with and without endometriosis.

METHOD

Total RNA was isolated and complementary DNA synthesized from eutopic endometrium of women with (n = 15) and without (n = 12) endometriosis, followed by quantitative real-time polymerase chain reaction (PCR) to evaluate the gene expression of Nodal, Cripto, SMAD3, and SMAD4. Western blot was used to evaluate the protein levels of Nodal and Cripto, and immunohistochemistry was performed to localize SMAD3, pSMAD3, and SMAD4.

RESULTS

Although Nodal expression was unchanged in women with endometriosis, real-time PCR indicated lower gene expression of Cripto (fold change 0.27, P < .05) in the endometriosis group. This difference, however, was not maintained at protein expression level as assessed by Western blot. The immunostaining of total SMAD3 was reduced in the endometriosis group (P < .01), but the localization of pSMAD3 and the nuclear staining of SMAD4 were unchanged.

CONCLUSION

These findings suggest that the Nodal signaling pathway has subtle changes in the endometrium of women with endometriosis, but this imbalance may not cause functional damage as it seems not to affect the nuclear expression of SMAD4.

FOXL2 in human endometrium: hyperexpressed in endometriosis

The present study investigated expression and protein localization of FOXL2 messenger RNA (mRNA) in endometrium of healthy women and in patients with endometriosis during endometrial cycle. In endometriotic lesions, FOXL2 mRNA and protein were evaluated and a possible correlation with activin A mRNA expression changes was also studied. Endometrium was collected from healthy women (n = 52) and from women with endometriosis (n = 31) by hysteroscopy; endometriotic tissues were collected by laparoscopy (n = 38). FOXL2 gene expression analysis in endometrium of healthy women showed a significant expression and no significant changes in mRNA levels between proliferative and secretory phases; a similar pattern was observed in endometrium of patients with endometriosis. Immunohistochemical evaluation showed that FOXL2 protein localized in stromal and glandular cells and colocalized with SUMO-1. FOXL2 mRNA expression was 3-fold higher in endometriosis than in healthy endometrium (P < .01) and a positive correlation between FOXL2 and activin A mRNA was found (P < .05) in endometriosis. In conclusion, FOXL2 mRNA expression and its protein localization do not change during endometrial cycle in eutopic endometrium from healthy individuals or patients with endometriosis; the hyperexpression of FOXL2 in endometriotic lesions suggests an involvement of this transcriptional regulator, probably associated with activin A expression and related to the pathogenesis of endometriosis.

Endometrioma: From Pathogenesis to Clinical Management

An endometrioma (OMA) is the localization of endometriosis in ovary, and it most often develops as a cyst. The pathogenesis of OMA is still an open question and controversial; a cystic hemorrhagic corpus luteum may be a prerequisite, occurring as a transition to an endometriotic cyst. Inversion and progressive invagination of the ovarian cortex after the accumulation of menstrual debris derived from bleeding of superficial endometriotic implants, located on the ovarian surface and adherent to the peritoneum, is another hypothesis. Gene studies show that WNT4 and FN1 are predisposing genes for OMA development. A role of environmental toxicants in the development of OMA is also under investigation; dioxins and dioxin-like compounds (DLCs), interacting with steroid receptors, are possible factors. Even if women with endometriosis have a 1.5 times greater lifetime risk to develop an ovarian carcinoma, an OMA is not to be considered a preneoplastic lesion.

The clinical management of OMAs is complex and should be individualized. Ultrasounds and magnetic resonance imaging (MRI) are sensitive but not specific for diagnosis. Treatment is influenced by patient age, desire for pregnancy, pain severity, cyst dimensions and characteristics (unilateral/bilateral), coexistence of deep endometriosis, previous gynecological or obstetrical history and previous surgery. Laparoscopic surgery is considered the treatment of choice in cases of infertile patients with a large OMA or pain, and in patients not responding to medical therapy. It should be performed with proper techniques by trained surgeons to decrease the damage to the remaining ovarian tissue, and to maintain the ovarian reserve after surgery. A medical hormonal and nonhormonal treatment is used for asymptomatic and/or pain-associated OMA (progestins, estroprogestins and antiinflammatory drugs). Considering the relative high recurrence rate after surgery, a medical treatment should be offered.

Activin A stimulates interleukin 8 and vascular endothelial growth factor release from cultured human endometrial stromal cells: possible implications for the pathogenesis of endometriosis

BACKGROUND

Activin A is an endometrial secretory product involved in inflammation and angiogenesis. The present study aimed to evaluate the effect of activin A and its antagonist follistatin on interleukin (IL)-6, IL-8, and vascular endothelial growth factor (VEGF) expression and release from cultured human endometrial stromal cells (HESCs) from women with and without endometriosis.

METHODS

The HESCs were collected from women with endometriosis (n = 6) and controls (n = 6). Primary cultures were treated with activin A at different doses or activin A plus follistatin. The IL-6, IL-8, and VEGF messenger RNA expression was evaluated by real-time polymerase chain reaction and protein release was evaluated by enzyme-linked immunosorbent assay.

RESULTS

Unstimulated HESC from women with endometriosis secreted more IL-6 and IL-8 than controls. The addition of activin A increased IL-8 and VEGF secretion in HESC from controls and decreased IL-6 and IL-8 secretion in HESC from women with endometriosis. These effects were counteracted by follistatin.

CONCLUSION

Activin A regulates the expression and secretion of IL-8 and VEGF in cultured HESC, and this mechanism appears to be disrupted in eutopic endometrial cells from women affected by endometriosis.

Diagnostic value of serum activin A and follistatin levels in women with peritoneal, ovarian and deep infiltrating endometriosis

BACKGROUND

Activin A is a growth factor, produced by the endometrium, whose actions are modulated by the binding protein follistatin. Both proteins are detectable in the peripheral serum and their concentrations may be increased in women with endometriosis. The present study was designed to evaluate whether serum levels of activin A and follistatin are altered, and therefore have a potential diagnostic value, in women with peritoneal, ovarian and deep infiltrating endometriosis.

METHODS

We performed a multicenter controlled study evaluating simultaneously serum activin A and follistatin concentrations in women with and without endometriosis. Women with endometriosis (n = 139) were subdivided into three groups: peritoneal endometriosis (n = 28); ovarian endometrioma (n = 61) and deep infiltrating endometriosis (n = 50). The control group (n = 75) consisted of healthy women with regular menstrual cycles. Blood samples were collected from a peripheral vein and assayed for activin A and follistatin using commercially available enzyme immunoassay kits.

RESULTS

The ovarian endometrioma group had serum activin A levels significantly higher than healthy controls (0.22 ± 0.01 ng/ml versus 0.17 ± 0.01 ng/ml, P < 0.01). None of the endometriosis groups had serum follistatin levels which were significantly altered compared with healthy controls; however, levels found in the endometrioma group (2.34 ± 0.32 ng/ml) were higher than that in the deep endometriosis group (1.50 ± 0.17 ng/ml, P < 0.05). The area under the receiver operating characteristic curve of activin A was 0.700 (95% confidence interval: 0.605-0.794), while that of follistatin was 0.620 (95% confidence interval: 0.510-0.730) for the diagnosis of ovarian endometrioma. The combination of both markers into a duo marker index did not improve significantly their diagnostic accuracy.

CONCLUSIONS

The present study demonstrated that serum activin A and follistatin are not significantly altered in peritoneal or deep infiltrating endometriosis and have limited diagnostic accuracy in the diagnosis of ovarian endometrioma.