Endometriosis--a disease because it is characterized by bleeding

Biomarkers of endometriosis

Endometriosis represents a diverse disease characterized by three distinct phenotypes: superficial peritoneal lesions, ovarian endometriomas, and deep infiltrating endometriosis. The most widely accepted pathophysiological hypothesis for endometriosis is rooted in retrograde menstruation, a phenomenon observed in most patients. Endometriosis is closely linked to infertility, but having endometriosis does not necessarily imply infertility. The disease can impact fertility through various mechanisms affecting the pelvic cavity, ovaries, and the uterus itself. MicroRNAs (miRNAs) indeed represent a fascinating and essential component of the regulatory machinery within cells. Discovered in the early 1990s, miRNAs have since been identified as critical players in gene expression control. Unfortunately, ovarian endometrioma is a common gynecologic disorder for which specific serum markers are currently lacking. Some have examined urocortin for its ability to differentiate endometriomas from other benign ovarian cysts. Another potential marker, Cancer Antigen 125 (CA-125) is a well-established indicator for epithelial cell ovarian cancer and its levels can be elevated in conditions such as endometriosis. CA-125 is derived from coelomic epithelia, including the endometrium, fallopian tube, ovary, and peritoneum. In this review we examine the pathophysiologic basis for endometriosis and highlight potential markers to more fully characterize the underlying biochemical processes linked to this multifaceted disease state.

Impact of deep or ovarian endometriosis on pelvic pain and quality of life: prospective cross-sectional ultrasound study

OBJECTIVE

To assess whether premenopausal women diagnosed with deep or ovarian endometriosis on transvaginal sonography (TVS) were more likely to suffer from dyspareunia and pelvic pain symptoms, and have a lower quality of life, compared to women without sonographically diagnosed deep or ovarian endometriosis.

METHODS

This was a prospective, cross-sectional study carried out between February 2019 and October 2020 at the general gynecology clinic at University College London Hospital, London, UK. All premenopausal women aged 18-50 years, who were examined consecutively by a single experienced examiner and underwent a detailed TVS scan, were eligible for inclusion. Pregnant women and those who had received a previous diagnosis of endometriosis or who had experienced a hysterectomy or unilateral/bilateral oophorectomy were excluded. Sonographic findings consistent with deep or ovarian endometriosis were noted. All women completed the British Society of Gynaecological Endoscopy pelvic pain questionnaire. The primary outcome was to determine whether women with sonographic evidence of endometriosis were more likely to experience moderate-to-severe levels of dyspareunia (score of ≥ 4 on an 11-point numerical rating scale (NRS)). Secondary outcomes included assessing moderate-to-severe levels of other pelvic pain symptoms (NRS score of ≥ 4), bowel symptoms (score of ≥ 2 on a 5-point Likert scale) and quality of life, which was measured using the EuroQol-5D-3L (EQ-5D) questionnaire. The number of women with pain scores ≥ 4 and bowel scores ≥ 2, as well as the mean EQ-5D scores, were compared between the group with and that without sonographic evidence of endometriosis using logistic regression analysis, and multivariable analysis was used to adjust for demographic and clinical variables.

RESULTS

A total of 514 women were included in the final study population, of whom 146 (28.4%) were diagnosed with deep or ovarian endometriosis on TVS. On multivariable analysis, the presence of moderate-to-severe dyspareunia was not found to be associated with endometriosis. Moderate-to-severe dyspareunia was significantly associated with lower age (odds ratio (OR), 0.70 (95% CI, 0.56-0.89); P = 0.003) and a history of migraine (OR, 3.52 (95% CI, 1.42-8.77); P = 0.007), and it occurred significantly less frequently in women with non-endometriotic ovarian cysts (OR, 0.47 (95% CI, 0.28-0.78); P = 0.003). There was also a trend towards a positive association between anxiety/depression and moderate-to-severe dyspareunia (OR, 1.94 (95% CI, 0.93-4.03); P = 0.08). Following multivariable analysis, the only symptoms that were significantly more common in women with endometriosis compared to those without were menstrual dyschezia (OR, 2.44 (95% CI, 1.59-3.78); P < 0.001) and difficulty emptying the bladder (OR, 2.56 (95% CI, 1.52-4.31); P < 0.001). Although not reaching statistical significance on multivariable analysis, dysmenorrhea (OR, 1.72 (95% CI, 0.92-3.20); P = 0.09) and lower EQ-5D score (mean ± SD, 0.67 ± 0.33 vs 0.72 ± 0.28; P = 0.06) also occurred more frequently in women with sonographic evidence of endometriosis.

CONCLUSIONS

The majority of pelvic pain symptoms did not differ significantly between women with and those without sonographic evidence of endometriosis, indicating that endometriosis may not always be the source of pelvic pain, even if present. This highlights the need to rule out other causes of pain in symptomatic endometriosis patients before considering surgical procedures, and to provide appropriate patient counseling. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A Fibronectin (FN)-Silk 3D Cell Culture Model as a Screening Tool for Repurposed Antifibrotic Drug Candidates for Endometriosis

This study advances sustainable pharmaceutical research for endometriosis by developing in vitro 3D cell culture models of endometriotic pathophysiology that allow antifibrotic drug candidates to be tested. Fibrosis is a key aspect of endometriosis, yet current cell models to study it remain limited. This work aims to bridge the translational gap between in vitro fibrosis research and preclinical testing of non-hormonal drug candidates. When grown in a 3D matrix of sustainably produced silk protein functionalized with a fibronectin-derived cell adhesion motif (FN-silk), endometrial stromal and epithelial cells respond to transforming growth factor beta-1 (TGF-β1) in a physiological manner as probed at the messenger RNA (mRNA) level. For stromal cells, this response to TGF-β1 is not observed in spheroids, while epithelial cell spheroids behave similarly to epithelial cell FN-silk networks. Pirfenidone, an antifibrotic drug approved for the treatment of idiopathic pulmonary fibrosis, reverses TGF-β1-induced upregulation of mRNA transcripts involved in fibroblast-to-myofibroblast transdifferentiation of endometrial stromal cells in FN-silk networks, supporting pirfenidone's potential as a repurposed non-hormonal endometriosis therapy. Overall, endometrial stromal cells cultured in FN-silk networks-which are composed of a sustainably produced, fully defined FN-silk protein-recapitulate fibrotic cellular behavior with high fidelity and enable antifibrotic drug testing.

Single-cell and spatial transcriptomic profiling revealed niche interactions sustaining growth of endometriotic lesions

Endometriosis is a chronic condition with limited therapeutic options. The molecular aberrations promoting ectopic attachment and interactions with the local microenvironment sustaining lesion growth have been unclear, prohibiting development of targeted therapies. Here, we performed single-cell and spatial transcriptomic profiling of ectopic lesions and eutopic endometrium in endometriosis. We found that ectopic endometrial stromal (EnS) cells retained cyclical gene expression patterns of their eutopic counterparts while exhibiting unique gene expression that contributes to the pathogenesis of endometriosis. We identified two distinct ovarian stromal cells (OSCs) localized at different zones of the lesion, showing differential gene expression profiles associated with fibrosis and inflammation, respectively. We also identified WNT5A upregulation and aberrant activation of non-canonical WNT signaling in endometrial stromal cells that may contribute to the lesion establishment, offering novel targets for therapeutic intervention. These data will enhance our understanding of the molecular mechanisms underlying endometriosis and paves the way for developing non-hormonal treatments.

Proposal for targeted, neo-evolutionary-oriented secondary prevention of early-onset endometriosis and adenomyosis. Part II: medical interventions

According to consistent epidemiological data, the slope of the incidence curve of endometriosis rises rapidly and sharply around the age of 25 years. The delay in diagnosis is generally reported to be between 5 and 8 years in adult women, but it appears to be over 10 years in adolescents. If this is true, the actual onset of endometriosis in many young women would be chronologically placed in the early postmenarchal years. Ovulation and menstruation are inflammatory events that, when occurring repeatedly for years, may theoretically favour the early development of endometriosis and adenomyosis. Moreover, repeated acute dysmenorrhoea episodes after menarche may not only be an indicator of ensuing endometriosis or adenomyosis, but may also promote the transition from acute to chronic pelvic pain through central sensitization mechanisms, as well as the onset of chronic overlapping pain conditions. Therefore, secondary prevention aimed at reducing suffering, limiting lesion progression, and preserving future reproductive potential should be focused on the age group that could benefit most from the intervention, i.e. severely symptomatic adolescents. Early-onset endometriosis and adenomyosis should be promptly suspected even when physical and ultrasound findings are negative, and long-term ovulatory suppression may be established until conception seeking. As nowadays this could mean using hormonal therapies for several years, drug safety evaluation is crucial. In adolescents without recognized major contraindications to oestrogens, the use of very low-dose combined oral contraceptives is associated with a marginal increase in the individual absolute risk of thromboembolic events. Oral contraceptives containing oestradiol instead of ethinyl oestradiol may further limit such risk. Oral, subcutaneous, and intramuscular progestogens do not increase the thromboembolic risk, but may interfere with attainment of peak bone mass in young women. Levonorgestrel-releasing intra-uterine devices may be a safe alternative for adolescents, as amenorrhoea is frequently induced without suppression of the ovarian activity. With regard to oncological risk, the net effect of long-term oestrogen-progestogen combinations use is a small reduction in overall cancer risk. Whether surgery should be considered the first-line approach in young women with chronic pelvic pain symptoms seems questionable. Especially when large endometriomas or infiltrating lesions are not detected at pelvic imaging, laparoscopy should be reserved to adolescents who refuse hormonal treatments or in whom first-line medications are not effective, not tolerated, or contraindicated. Diagnostic and therapeutic algorithms, including self-reported outcome measures, for young individuals with a clinical suspicion of early-onset endometriosis or adenomyosis are proposed.

A protocol for creating endometriosis in rhesus macaques (Macaca mulatta)

BACKGROUND

Endometriosis is the presence of endometrium-like tissue outside the uterine cavity. An experimental model of endometriosis has been created in the baboon by the transcervical collection and laparoscopic inoculation of menstrual endometrium. Macaques are the preferred model for pharmaceutical development, but the complex anatomy of the macaque cervix makes the baboon method impractical. In this work, we sought to validate a surgical approach for creating endometriosis in macaques.

METHODS

Menstrual endometrium was collected via laparoscopic intrauterine puncture and transferred to the peritoneal cavity. We repeated this procedure during three menstruations. Endometriotic tissue was identified during laparoscopy, collected, and characterized by immunohistochemistry.

RESULTS

Sham surgery-treated animals (n = 3) failed to develop endometriosis. We identified red, powder burnt, and white lesions in 13/14 of the treated animals; the stroma of the red lesions stained positive for ovarian steroid receptors.

CONCLUSION

This surgical technique can reliably create hormone-responsive endometriosis in macaques for therapeutic studies.

A novel mechanism regulating pyroptosis-induced fibrosis in endometriosis via lnc-MALAT1/miR-141-3p/NLRP3 pathway†

Endometriosis is a chronic inflammatory disease distinguished by ectopic endometrium and fibrosis. NLRP3 inflammasome and pyroptosis are present in endometriosis. Aberrant increase of Long noncoding (Lnc)-metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) plays a vital role in endometriosis. However, the relationship between lnc-MALAT1, pyroptosis, and fibrosis is not completely known. In the present study, we found that the pyroptosis levels in ectopic endometrium of patients with endometriosis were significantly increased, consistent with fibrosis levels. Lipopolysaccharide (LPS) + ATP could induce pyroptosis of primary endometrial stromal cells (ESCs), thereby releasing interleukin (IL)-1β and stimulating transforming growth factor (TGF)-β1-mediated fibrosis. NLRP3 inhibitor MCC950 had the same effect as TGF-β1 inhibitor SB-431542 in suppressing the fibrosis-inducing effect of LPS + ATP in vivo and in vitro. The abnormal increase of lnc-MALAT1 in ectopic endometrium was connected with NLRP3-mediated pyroptosis and fibrosis. Leveraging bioinformatic prediction and luciferase assays combined with western blotting and quantitative reverse transcriptase-polymerase chain reaction, we validated that lnc-MALAT1 sponges miR-141-3p to promote NLRP3 expression. Silencing lnc-MALAT1 in HESCs ameliorated NLRP3-mediated pyroptosis and IL-1β release, thereby relieving TGF-β1-mediated fibrosis. Consequently, our findings suggest that lnc-MALAT1 is critical for NLRP3-induced pyroptosis and fibrosis in endometriosis through sponging miR-141-3p, which may indicate a new therapeutic target of endometriosis treatment.

In the thicket of fears, doubts, and murky facts: some reflections on treatment modalities for endometriosis-associated pain

Endometriosis-associated pain can be managed by either surgery or hormonal therapy. The final decision as to which treatment modality to take is based on efficacy and possible complications of different treatment modalities, risk of recurrence, and the patient's wishes and preferences. But in the thicket of fears, doubts, and murky facts, the choice may ultimately be the trade-off between irrational fears and ignorance versus scientific evidence. We elaborate some pros and cons of the two treatment modalities and highlight some notable downsides of hormonal therapy, in particular the possible yet unquantified risk of long-term hormonal therapy for malignant transformation, perhaps with the only exception of combined oral contraceptives. Thus, when discussing with patients, we advocate the approach of discussing the advantages and disadvantages of all treatment options in detail, accounting for the known pros and cons with a full understanding of the predictive irrationality of human beings. For endometriosis-associated pain, surgery is definitely not a failure of medicine but, rather, a viable option, especially given the recently surfaced undercurrent of wariness and dissatisfaction with the current hormonal drugs among patients with endometriosis. Above all, there is a pressing need to fill the knowledge gap of perioperative interventions intended to reduce the risk of recurrence and to fulfill the demand for the development of safe and efficacious non-hormonal therapeutics.

An Appraisal of the Tissue Injury and Repair (TIAR) Theory on the Pathogenesis of Endometriosis and Adenomyosis

As understanding their pathogenesis remains elusive, both endometriosis and adenomyosis are often referred to as "enigmatic diseases". The uncertainty and heightened interest are reflected in the range of expressed views and opinions. There is a sense of urgency because of the entailed patient suffering. The plethora of opinions calls for a critical analysis of proposed theories, both old and new. A series of papers published since 2009 proposed that both endometriosis and adenomyosis originate from the same aberrations occurring within the uterus. This came to be recognized as the tissue injury and repair theory, and the newly coined term "archimetrosis" posits that the two diseases share the same origin. While the theory opens an interesting channel for exploration, its claim as a unifying theory necessitates a critical appraisal. We, thus, undertook this review of the theory and analyzed its underpinnings based on a comprehensive review of the literature. Our appraisal indicates that the theory is open to a range of criticisms. Chief among these is the need for confirmatory evidence of features of abnormal uterine contractility and the lack of data addressing the question of causality. In addition, the theory has, as yet, no supporting epidemiological evidence, which is a major weakness. The theory suffers as it is not open to the test of falsifiability, and it lacks the ability to make useful predictions. It has not addressed the questions, such as why only a small percentage of women develop adenomyosis or endometriosis, given the ubiquity of uterine peristalsis. On the other hand, the triggers and prevention of hyper- or dys-peristalsis become critical to a theory of causation. We conclude that additional supportive evidence is required for the theory to be accepted.

The Role of Platelets in the Pathogenesis and Pathophysiology of Adenomyosis

Widely viewed as an enigmatic disease, adenomyosis is a common gynecological disease with bewildering pathogenesis and pathophysiology. One defining hallmark of adenomyotic lesions is cyclic bleeding as in eutopic endometrium, yet bleeding is a quintessential trademark of tissue injury, which is invariably followed by tissue repair. Consequently, adenomyotic lesions resemble wounds. Following each bleeding episode, adenomyotic lesions undergo tissue repair, and, as such, platelets are the first responder that heralds the subsequent tissue repair. This repeated tissue injury and repair (ReTIAR) would elicit several key molecular events crucial for lesional progression, eventually leading to lesional fibrosis. Platelets interact with adenomyotic cells and actively participate in these events, promoting the lesional progression and fibrogenesis. Lesional fibrosis may also be propagated into their neighboring endometrial-myometrial interface and then to eutopic endometrium, impairing endometrial repair and causing heavy menstrual bleeding. Moreover, lesional progression may result in hyperinnervation and an enlarged uterus. In this review, the role of platelets in the pathogenesis, progression, and pathophysiology is reviewed, along with the therapeutic implication. In addition, I shall demonstrate how the notion of ReTIAR provides a much needed framework to tether to and piece together many seemingly unrelated findings and how it helps to make useful predictions.

Endometriosis Stem Cells as a Possible Main Target for Carcinogenesis of Endometriosis-Associated Ovarian Cancer (EAOC)

Endometriosis is a serious recurrent disease impairing the quality of life and fertility, and being a risk for some histologic types of ovarian cancer defined as endometriosis-associated ovarian cancers (EAOC). The presence of stem cells in the endometriotic foci could account for the proliferative, migrative and angiogenic activity of the lesions. Their phenotype and sources have been described. The similarly disturbed expression of several genes, miRNAs, galectins and chaperones has been observed both in endometriotic lesions and in ovarian or endometrial cancer. The importance of stem cells for nascence and sustain of malignant tumors is commonly appreciated. Although the proposed mechanisms promoting carcinogenesis leading from endometriosis into the EAOC are not completely known, they have been discussed in several articles. However, the role of endometriosis stem cells (ESCs) has not been discussed in this context. Here, we postulate that ESCs may be a main target for the carcinogenesis of EAOC and present the possible sequence of events resulting finally in the development of EAOC.

Cracking the enigma of adenomyosis: an update on its pathogenesis and pathophysiology

In brief

Traditionally viewed as enigmatic and elusive, adenomyosis is a fairly common gynecological disease but is under-recognized and under-researched. This review summarizes the latest development on the pathogenesis and pathophysiology of adenomyosis, which have important implications for imaging diagnosis of the disease and for the development of non-hormonal therapeutics.

Abstract

Traditionally considered as an enigmatic disease, adenomyosis is a uterine disease that affects many women of reproductive age and is a contributing factor for pelvic pain, heavy menstrual bleeding (HMB), and subfertility. In this review, the new development in the pathogenesis and pathophysiology of adenomyosis has been summarized, along with their clinical implications. After reviewing the progress in our understanding of the pathogenesis and describing the prevailing theories, in conjunction with their deficiencies, a new hypothesis, called endometrial-myometrial interface disruption (EMID), which is backed by extensive epidemiologic data and demonstrated by a mouse model, is reviewed, along with recent data implicating the role of Schwann cells in the EMI area in the genesis of adenomyosis. Additionally, the natural history of adenomyotic lesions is elaborated and underscores that, in essence, adenomyotic lesions are fundamentally wounds undergoing repeated tissue injury and repair (ReTIAR), which progress to fibrosis through epithelial-mesenchymal transition, fibroblast-to-myofibroblast transdifferentiation, and smooth muscle metaplasia. Increasing lesional fibrosis propagates into the neighboring EMI and endometrium. The increased endometrial fibrosis, with ensuing greater tissue stiffness, results in attenuated prostaglandin E2, hypoxia signaling and glycolysis, impairing endometrial repair and causing HMB. Compared with adenomyosis-associated HMB, the mechanisms underlying adenomyosis-associated pain are less understood but presumably involve increased uterine contractility, hyperinnervation, increased lesional production of pain mediators, and central sensitization. Viewed through the prism of ReTIAR, a new imaging technique can be used to diagnose adenomyosis more accurately and informatively and possibly help to choose the best treatment modality.

Utility of the Levonorgestrel-Releasing Intrauterine System in the Treatment of Abnormal Uterine Bleeding and Dysmenorrhea: A Narrative Review

INTRODUCTION

We undertook a literature review of the use of levonorgestrel-releasing intrauterine devices when utilized for heavy menstrual bleeding and/or dysmenorrhea.

METHODS

A narrative review of articles in the Scopus and Medline databases was conducted.

RESULTS

A number of options exist for the management of both abnormal uterine bleeding (AUB) and dysmenorrhea, and evidence is accumulating that the insertion of a levonorgestrel-releasing intrauterine system (LNG-IUS) represents a useful option for their long-term treatment. The idea of using a progestogen released in utero was initially conceived to achieve long-term contraception, but it was quickly found that these systems could be utilized for a number of therapeutic applications. The first device to be made commercially available, Progestasert, was withdrawn from the market because, in the event of contraceptive failure, it caused a disproportionate percentage of extrauterine pregnancies. On the other hand, the LNG-IUS continues to be successfully utilized in its various variants, releasing 20, 13, or 8 μg/day. These devices have a respective duration of action of 7 (possibly 8), 5, and 3 years, and there exist versions of frameless systems affixed to the myometrium of the uterine fundus. In the present review, following a brief description of the major causes of AUB and dysmenorrhea, the molecular bases for the use of the LNG-IUS are summarized. This is followed by a compendium of its use in AUB and dysmenorrhea, concluding that the insertion of the system improves the quality of life, reduces menstrual blood loss better than other medical therapies, and decreases the extent of dysmenorrhea and pelvic pain. In addition, there is no evidence of a significant difference in these outcomes when the use of the LNG-IUS was compared with improvements offered by endometrial ablation or hysterectomy. Possibly, the most important mechanism of action of the system consists of its ability to induce amenorrhea, which effectively eliminates heavy bleeding and dysmenorrhea. However, no method is ideal for every woman, and, in the case of the LNG-IUS, younger age and severe dysmenorrhea seem to be associated with a higher risk of discontinuation.

CONCLUSION

The higher-dose LNG-IUS is a useful tool for HMB and dysmenorrhea in women of all ages. The low cost and ease of use make the LNG-IUS an attractive option, especially when contraception is also desired.

Unveiling the Pathogenesis of Adenomyosis through Animal Models

Background: Adenomyosis is a common gynecological disorder traditionally viewed as “elusive”. Several excellent review papers have been published fairly recently on its pathogenesis, and several theories have been proposed. However, the falsifiability, explanatory power, and predictivity of these theories are often overlooked. Since adenomyosis can occur spontaneously in rodents and many other species, the animal models may help us unveil the pathogenesis of adenomyosis. This review critically tallies experimentally induced models published so far, with a particular focus on their relevance to epidemiological findings, their possible mechanisms of action, and their explanatory and predictive power. Methods: PubMed was exhaustively searched using the phrase “adenomyosis and animal model”, “adenomyosis and experimental model”, “adenomyosis and mouse”, and “adenomyosis and rat”, and the resultant papers were retrieved, carefully read, and the resultant information distilled. All the retrieved papers were then reviewed in a narrative manner. Results: Among all published animal models of adenomyosis, the mouse model of adenomyosis induced by endometrial–myometrial interface disruption (EMID) seems to satisfy the requirements of falsifiability and has the predictive capability and also Hill’s causality criteria. Other theories only partially satisfy Hill’s criteria of causality. In particular, animal models of adenomyosis induced by hyperestrogenism, hyperprolactinemia, or long-term exposure to progestogens without much epidemiological documentation and adenomyosis is usually not the exclusive uterine pathology consequent to those induction procedures. Regardless, uterine disruption appears to be a necessary but not sufficient condition for causing adenomyosis. Conclusions: EMID is, however, unlikely the sole cause for adenomyosis. Future studies, including animal studies, are warranted to understand how and why in utero and/or prenatal exposure to elevated levels of estrogen or estrogenic compounds increases the risk of developing adenomyosis in adulthood, to elucidate whether prolactin plays any role in its pathogenesis, and to identify sufficient condition(s) that cause adenomyosis.

Tetramethylpyrazine Retards the Progression and Fibrogenesis of Endometriosis

The development of more efficacious, non-hormonal therapeutics for endometriosis is still an unmet medical need begging to be fulfilled. Growing evidence indicates that endometriotic lesions are wounds undergoing repeated tissue injury and repair, and, as such, platelets play an important role in lesional progression. Tetramethylpyrazine (TMP), a compound derived from a herb that has been used for thousands of years to combat “blood stasis” in traditional Chinese medicine, is a prescription drug in China for the treatment of cerebrovascular disorders. We tested the hypothesis that TMP can decelerate lesional progression through arresting epithelial-mesenchymal transition (EMT), fibroblast-to-myofibroblast transdifferentiation (FMT), and fibrogenesis. We found in our in vitro experiments that TMP treatment suppresses platelet-induced EMT, FMT, cellular contractility, and collagen production in a concentration-dependent manner. We also showed that in a mouse model of endometriosis, treatment with TMP significantly reduced lesion weight and the extent of lesional fibrosis and improved hyperalgesia, mostly likely through the reduction of lesional aggregation of platelets and the lesional expression of markers of EMT, FMT, and fibrogenesis. In light of our results and in view of its excellent safety profiles, TMP appears to be a promising drug candidate for treating endometriosis.

How does the extent of fibrosis in adenomyosis lesions contribute to heavy menstrual bleeding?

Purpose

To investigate how the extent of fibrosis in adenomyosis lesions contributes to heavy menstrual bleeding (HMB).

Methods

We recruited 57 women with histologically confirmed adenomyosis, 29 of whom reported moderate/heavy bleeding (MHB) (menstrual blood loss (MBL) ≥20 but <100 mL) and the remaining 28, excessive MBL (EXB; ≥100 mL). Lesional stiffness was measured by transvaginal elastosonography. Full-thickness uterine tissue columns containing the lesion and its neighboring endometrial-myometrial interface (EMI) and endometrial tissues were evaluated for tissue fibrosis and immunohistochemical analysis of HIF-1α, COX-2, EP2, and EP4.

Results

The lesional stiffness in the EXB group was significantly higher than that of MHB, and consistently, the extent of lesional fibrosis and the extent of tissue fibrosis in both EMI and eutopic endometrium were also significantly higher. In adenomyotic lesions and their neighboring EMI and eutopic endometrial tissues, the immunostaining of HIF-1α, COX-2, EP2, and EP4 was significantly reduced. The extent of fibrosis and the immunostaining levels of HIF-1α, COX-2, EP2, and EP4 were negatively correlated in all tissues.

Conclusions

Lesional fibrosis begets stiffening matrix, propagating fibrosis to neighboring EMI and eutopic endometrium, resulting in reduced PGE2 and HIF-1α signaling, and thus likely reduced hypoxia necessary for endometrial repair, leading to HMB.

Comparing endometriotic lesions with eutopic endometrium: time to shift focus?

Endometriosis is a heterogeneous disease in terms of patient symptoms, treatment responsiveness and the presentation of endometriotic lesions. This article explores the histological features of endometriotic lesions, highlighting their sometimes underappreciated heterogeneity. We note the variability in evidence for and against the menstrual cycle responsiveness of lesions and consider the utility of drawing parallels between endometriotic lesions and eutopic endometrium. We ask whether histopathologic features beyond just the presence/absence of endometrial-like glands and/or stroma could help improve disease stratification. At the same time, we acknowledge the desire of many clinicians and patients to avoid invasive surgery thereby limiting the ability to histologically phenotype lesions. The ability to derive clinically useful histological information from endometriotic lesions, in association with patient data, would be invaluable to clinicians to help improve treatment options in such a diverse group of patients. However, in suggesting that a shift in focus may enable the development of a better patient stratification system, we recognise that our wish for a single comprehensive stratification system may be beyond reach for a disease of such diverse presentation.

Ectopic Endometrium: The Pathologist's Perspective

Endometriosis and adenomyosis are two frequent diseases closely linked, characterized by ectopic endometrium. Despite their benign nature, endometriosis and adenomyosis impair women's quality of life by causing pain and infertility and an increase in the incidence of gynecological malignancies has been reported. Since the first description of ectopic endometrium in 1860, different attempts have been made to describe, classify and understand the origin of these diseases. Several theories have been proposed to describe the pathogenic mechanism leading to the development of adenomyosis or endometriosis. However, all the hypotheses show some limitations in explaining all the different aspects and manifestations of these diseases. Despite the remarkable progress made over recent years, the pathogeneses of endometriosis and adenomyosis remain unclear. Moreover, because of the lack of standardized protocols and diagnostic criteria in pathology practice it is difficult to study and to classify these disorders. The goal of this review is to summarize the pathological aspects of adenomyosis and endometriosis, spanning a historical perspective to newly reported data.

Identifying Common Pathogenic Features in Deep Endometriotic Nodules and Uterine Adenomyosis

Increasing imaging data point to a link between deep endometriotic nodules (DENs) and uterine adenomyosis (AD). The study aimed to investigate this link at the histological level and detect potential features shared by the two diseases. We collected formalin-fixed paraffin-embedded tissue (endometrium and lesions) from women with DENs of the rectovaginal septum (n = 13), AD (n = 14), and control subjects (n = 14). Immunohistochemical analyses of CD41 and CD68 were conducted to explore the roles of platelets and macrophages, respectively. Picrosirius red staining was carried out to gather evidence of fibrosis. Vascular endothelial growth factor (VEGF) was assessed, and total numbers of CD31-positive vessels were calculated to investigate the mechanism governing angiogenesis. Double immunohistochemistry for CD31 and alpha smooth muscle actin (αSMA) was performed to discern stable vessels. Platelet aggregation was significantly decreased in both types of lesions compared to their corresponding eutopic endometrium and healthy controls. Macrophage numbers were higher in both lesions than in their corresponding endometrium and healthy subjects. Significantly higher rates of collagen accumulation were detected in DENs and AD lesions compared to their corresponding eutopic and healthy endometrium. VEGF expression was downregulated in the stromal compartment of AD lesions compared to the healthy endometrium. The total number of vessels per area was significantly higher in DENs and AD lesions than in the healthy endometrium. Rates of αSMA-surrounded vessels were decreased in DENs and AD lesions compared to their corresponding eutopic and healthy endometrium. We report common pathogenic mechanisms between DENs and AD, namely excessive macrophage accumulation, fibrosis, and irregular angiogenesis. Our results further support the notion of DENs and AD being linked at the histological level.

Use of dopamine agonists to target angiogenesis in women with endometriosis

Endometriosis requires medical management during a woman's reproductive years. Most treatments aim to create a hypoestrogenic milieu, but for patients wishing to conceive, drugs that allow normal ovarian function are needed. Targeting angiogenesis, a hallmark of the disease, using dopamine agonists (DAs) is a promising strategy for endometriosis treatment. Herein, we review experimental and clinical data that investigate this concept. In experimental models of endometriosis, DAs (bromocriptine, cabergoline, quinagolide) downregulate proangiogenic and upregulate antiangiogenic pathways in inflammatory, endothelial and endometrial cells, blocking cellular proliferation and reducing lesion size. Impaired secretion of vascular endothelial growth factor (VEGF) and inactivation of its receptor type-2 are key events. VEGF inhibition also reduces nerve fiber density in lesions. In humans, quinagolide shows similar effects on lesions, and DAs reduce pain and endometrioma size. Moreover, a 20-fold downregulation of Serpin-1, the gene that encodes for plasminogen activator inhibitor 1 (PAI-1), has been observed after DAs treatment. Pentoxifylline, a PAI-1, increases pregnancy rates in women with endometriosis. Thus, the data support the use of DAs in the medical management of endometriosis to reduce lesion size and pain while maintaining ovulation. A combined approach of DAs and pentoxifylline is perhaps a smart way of targeting the disease from a completely different angle than current medical treatments.

Superficial peritoneal endometriotic lesions are histologically diverse and rarely demonstrate menstrual cycle synchronicity with matched eutopic endometrium

STUDY QUESTION

Do menstrual cycle-dependent changes occur in the histological appearance of superficial peritoneal endometriotic lesions, and are they equivalent to those observed in the eutopic endometrium?

SUMMARY ANSWER

Only a small subset of superficial peritoneal endometriotic lesions exhibits some histological features in phase with menstrual cycle-related changes observed in eutopic endometrium.

WHAT IS KNOWN ALREADY

Endometriotic lesions are frequently described as implants that follow menstrual cycle-related changes in morphology, as per the eutopic endometrium. This concept has been widely accepted despite the lack of conclusive published evidence.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study of 42 patients, from across the menstrual cycle, with surgically and histologically confirmed endometriosis. Patients were a subset selected from a larger endometriosis study being conducted at the Royal Women's Hospital, Melbourne since 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Histological features of epithelium, stroma and gland morphology were examined in haematoxylin and eosin stained sections of superficial peritoneal endometriotic lesions and matched eutopic endometrium (menstrual: n = 4, proliferative: n = 11, secretory: n = 17, hormone-treated: n = 10). At least two biopsies (average = 4, range = 2-8 biopsies) and a matched endometrial sample were analysed for each patient and results were presented per endometriotic gland profile (n = 1051). Data were analysed using mixed effects logistic regression to account for multiple patients and multiple endometriotic biopsies, each with multiple endometriotic gland profiles. This model also enabled analysis of endometriotic lesions versus eutopic endometrium.

MAIN RESULTS AND THE ROLE OF CHANCE

There was considerable inter- and intra-patient variability in the morphology of superficial peritoneal endometriotic lesions. Menstrual cycle-associated changes were only observed for some features in a subset of endometriotic gland profiles. The proportion of endometriotic gland profiles with epithelial mitoses significantly increased in the proliferative phase (18% of gland profiles) relative to the menstrual phase (0% of endometriotic gland profiles) (odds ratios (OR) 9.30; 95% confidence intervals (CI) = 3.71-23.32; P < 0.001). Fewer blood-filled gland lumens were observed in the secretory phase (45% of endometriotic gland profiles) compared to the menstrual phase (67% of endometriotic gland profiles) (OR, 0.30; 95% CI = 0.11-0.79; P = 0.015). The features of the eutopic endometrium analysed in this study did not reflect the results in matched endometriotic lesions (P > 0.05).

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

This study focused on features observed in sections of superficial peritoneal lesions and these may differ from features of deep infiltrating endometriosis or ovarian endometriomas. Cycle phases were limited to menstrual, proliferative and secretory phases to allow appropriate statistical modelling.

WIDER IMPLICATIONS OF THE FINDINGS

This study highlights heterogeneity in the histological characteristics of superficial peritoneal lesions. It challenges the assumption that lesion morphology consistently reflects menstrual cycle-associated changes.

STUDY FUNDING/COMPETING INTEREST(S)

Research reported in this publication was supported in part by National Health and Medical Research Council (NHMRC) project grants GNT1012245, GNT1105321 and GNT1026033 (P.A.W.R., J.E.G. and S.J.H.-C.). There are no competing interests.

Endometriosis in adolescent and young women

Endometriosis in adolescence represents a specific variant of the disease with its own characteristics and, in some cases, even a possibly different pathogenesis. It has its own clinical presentation, diagnostic and therapeutic modalities. The condition is not rare as once thought and certainly deserves attention in view of increasing evidence of its likely progressive nature. Numerous theories for Its pathogenesis have been formulated and they have been divided into two main categories: the 'in-situ' and the 'transplantation' hypotheses. Clinical manifestations include as the prevailing symptom a persistent chronic pelvic pain, despite medical treatment, manifested under various forms: dysmenorrhea, acyclic chronic pain, acute abdominal pain and migraines. These symptoms can substantially affect the quality of life on an adolescent. At histopathology, adolescent endometriosis is characterized by a high proportion of subtle, clear, red or vesicular implants and by the rarity of deep nodules. Frequently, the picture includes ovarian endometriomas. In some adolescent girls, lesions may regress or even disappear, probably through immune suppression; in others, chronic stress, unhealthy diet or lifestyle such as high-fat diet, may accelerate lesional progression and cause symptoms. Classically, management of adolescent endometriosis has been centered on attempts to treat dysmenorrhea; today both medical and surgical modalities have the potential to improve quality of life, alleviate symptoms, prevent the development of more severe disease and minimize risks for future fertility in adolescents. Nonetheless, at present, medical treatments are considered the first line of interventions in treating young women.

Nanomedicines for Endometriosis: Lessons Learned from Cancer Research

Endometriosis is an incurable gynecological disease characterized by the abnormal growth of endometrium-like tissue, characteristic of the uterine lining, outside of the uterine cavity. Millions of people with endometriosis suffer from pelvic pain and infertility. This review aims to discuss whether nanomedicines that are promising therapeutic approaches for various diseases have the potential to create a paradigm shift in endometriosis management. For the first time, the available reports and achievements in the field of endometriosis nanomedicine are critically evaluated, and a summary of how nanoparticle-based systems can improve endometriosis treatment and diagnosis is provided. Parallels between cancer and endometriosis are also drawn to understand whether some fundamental principles of the well-established cancer nanomedicine field can be adopted for the development of novel nanoparticle-based strategies for endometriosis. This review provides the state of the art of endometriosis nanomedicine and perspective for researchers aiming to realize and exploit the full potential of nanoparticles for treatment and imaging of the disorder.

Risk factors for the development of tubo-ovarian abscesses in women with ovarian endometriosis: a retrospective matched case-control study

BACKGROUND

The purpose of this study was to assess the risk factors associated with the development of tubo-ovarian abscesses in women with ovarian endometriosis cysts.

METHODS

This retrospective single-center study included 176 women: 44 with tubo-ovarian abscesses associated with ovarian endometriosis and 132 age-matched (1:3) patients with ovarian endometriosis but without tubo-ovarian abscesses. Diagnoses were made via surgical exploration and pathological examination. The potential risk factors of tubo-ovarian abscesses associated with ovarian endometriosis were evaluated using univariate analysis. The results (p ≤ 0.05) of these parameters were analyzed using a multivariate model.

RESULTS

Five factors were included in the multivariate conditional logistic regression model, including in vitro fertilization, presence of an intrauterine device, lower genital tract infection, spontaneous rupture of ovarian endometriosis cysts, and diabetes mellitus. The presence of a lower genital tract infection (odds ratio 5.462, 95% CI 1.772-16.839) and spontaneous rupture of ovarian endometriosis cysts (odds ratio 2.572, 95% CI 1.071-6.174) were found to be statistically significant risk factors for tubo-ovarian abscesses associated with ovarian endometriosis.

CONCLUSIONS

Among the factors investigated, genital tract infections and spontaneous rupture of ovarian endometriosis cysts were found to be involved in the occurrence of tubo-ovarian abscesses associated with ovarian endometriosis. Our findings indicate that tubo-ovarian abscesses associated with ovarian endometriosis may not be linked to in vitro fertilization as previously thought.

Cancer-associated mutations in endometriosis: shedding light on the pathogenesis and pathophysiology

BACKGROUND

Endometriosis is a benign gynaecological disease. Thus, it came as a complete surprise when it was reported recently that the majority of deep endometriosis lesions harbour somatic mutations and a sizeable portion of them contain known cancer-associated mutations (CAMs). Four more studies have since been published, all demonstrating the existence of CAMs in different subtypes of endometriosis. While the field is still evolving, the confirmation of CAMs has raised many questions that were previously overlooked.

OBJECTIVE AND RATIONALE

A comprehensive overview of CAMs in endometriosis has been produced. In addition, with the recently emerged understanding of the natural history of endometriotic lesions as well as CAMs in normal and apparently healthy tissues, this review attempts to address the following questions: Why has there been such a wild discrepancy in reported mutation frequencies? Why does ectopic endometrium have a higher mutation rate than that of eutopic endometrium? Would the presence of CAMs in endometriotic lesions increase the risk of cancer to the bearers? Why do endometriotic epithelial cells have much higher mutation frequencies than their stromal counterpart? What clinical implications, if any, do the CAMs have for the bearers? Do these CAMs tell us anything about the pathogenesis and/or pathophysiology of endometriosis?

SEARCH METHODS

The PubMed database was searched, from its inception to September 2019, for all papers in English using the term 'endometriosis and CAM', 'endometriosis and cancer-driver mutation', 'somatic mutations', 'fibrosis', 'fibrosis and epigenetic', 'CAMs and tumorigenesis', 'somatic mutation and normal tissues', 'oestrogen receptor and fibrosis', 'oxidative stress and fibrosis', 'ARID1A mutation', and 'Kirsten rat sarcoma mutation and therapeutics'. All retrieved papers were read and, when relevant, incorporated into the review results.

OUTCOMES

Seven papers that identified CAMs in endometriosis using various sequencing methods were retrieved, and their results were somewhat different. Yet, it is apparent that those using microdissection techniques and more accurate sequencing methods found more CAMs, echoing recent discoveries that apparently healthy tissues also harbour CAMs as a result of the replicative aging process. Hence endometriotic lesions, irrespective of subtype, if left intact, would generate CAMs as part of replicative aging, oxidative stress and perhaps other factors yet to be identified and, in some rare cases, develop cancer. The published data still are unable to paint a clear picture on pathogenesis of endometriosis. However, since endometriotic epithelial cells have a higher turnover than their stromal counterpart due to cyclic bleeding, and since the endometriotic stromal component can be formed by refresh influx of mesenchymal cells through epithelial-mesenchymal transition, endothelial-mesenchymal transition, mesothelial-mesenchymal transition and other processes as well as recruitment of bone-marrow-derived stem cells and outflow due to smooth muscle metaplasia, endometriotic epithelial cells have much higher mutation frequencies than their stromal counterpart. The epithelial and stromal cellular components develop in a dependent and co-evolving manner. Genes involved in CAMs are likely to be active players in lesional fibrogenesis, and hyperestrogenism and oxidative stress are likely drivers of both CAMs and fibrogenesis. Finally, endometriotic lesions harbouring CAMs would conceivably be more refractory to medical treatment, due, in no small part, to their high fibrotic content and reduced vascularity and cellularity.

WIDER IMPLICATIONS

The accumulating data on CAMs in endometriosis have shed new light on the pathogenesis and pathophysiology of endometriosis. They also suggest new challenges in management. The distinct yet co-evolving developmental trajectories of endometriotic stroma and epithelium underscore the importance of the lesional microenvironment and ever-changing cellular identity. Mutational profiling of normal endometrium from women of different ages and reproductive history is needed in order to gain a deeper understanding of the pathogenesis. Moreover, one area that has conspicuously received scant attention is the epigenetic landscape of ectopic, eutopic and normal endometrium.

Mesothelial Cells Participate in Endometriosis Fibrogenesis Through Platelet-Induced Mesothelial-Mesenchymal Transition

CONTEXT

While fibrosis in endometriosis has recently loomed prominently, the sources of myofibroblasts, the principal effector cell in fibrotic diseases, remain largely obscure. Mesothelial cells (MCs) can be converted into myofibroblasts through mesothelial-mesenchymal transition (MMT) in many fibrotic diseases and adhesion.

OBJECTIVE

To evaluate whether MCs contribute to the progression and fibrogenesis in endometriosis through MMT.

SETTING, DESIGN, PATIENTS, INTERVENTION, AND MAIN OUTCOME MEASURES

Dual immunofluorescence staining and immunohistochemistry using antibodies against calretinin, Wilms' tumor-1 (WT-1), and α-smooth muscle actin (α-SMA) were performed on lesion samples from 30 patients each with ovarian endometrioma (OE) and deep endometriosis (DE), and 30 normal endometrial (NE) tissue samples. Human pleural and peritoneal MCs were co-cultured with activated platelets or control medium with and without neutralization of transforming growth factor β1 (TGF-β1) and/or platelet-derived growth factor receptor (PDGFR) and their morphology, proliferation, and expression levels of genes and proteins known to be involved in MMT were evaluated, along with their migratory and invasive propensity, contractility, and collagen production.

RESULTS

The number of calretinin/WT-1 and α-SMA dual-positive fibroblasts in OE/DE lesions was significantly higher than NE samples. The extent of lesional fibrosis correlated positively with the lesional α-SMA staining levels. Human MCs co-cultured with activated platelets acquire a morphology suggestive of MMT, concomitant with increased proliferation, loss of calretinin expression, and marked increase in expression of mesenchymal markers. These changes coincided with functional differentiation as reflected by increased migratory and invasive capacity, contractility, and collagen production. Neutralization of TGF-β1 and PDGFR signaling abolished platelet-induced MMT in MCs.

CONCLUSIONS

MCs contribute to lesional progression and fibrosis through platelet-induced MMT.

Pain in Endometriosis

Endometriosis is a chronic and debilitating condition affecting ∼10% of women. Endometriosis is characterized by infertility and chronic pelvic pain, yet treatment options remain limited. In many respects this is related to an underlying lack of knowledge of the etiology and mechanisms contributing to endometriosis-induced pain. Whilst many studies focus on retrograde menstruation, and the formation and development of lesions in the pathogenesis of endometriosis, the mechanisms underlying the associated pain remain poorly described. Here we review the recent clinical and experimental evidence of the mechanisms contributing to chronic pain in endometriosis. This includes the roles of inflammation, neurogenic inflammation, neuroangiogenesis, peripheral sensitization and central sensitization. As endometriosis patients are also known to have co-morbidities such as irritable bowel syndrome and overactive bladder syndrome, we highlight how common nerve pathways innervating the colon, bladder and female reproductive tract can contribute to co-morbidity via cross-organ sensitization.

Fertility Outcome after CO2 Laser Vaporization versus Cystectomy in Women with Ovarian Endometrioma: A Comparative Study

STUDY OBJECTIVE

To assess the postoperative likelihood of conception in patients with endometriomas managed by either CO₂ laser vaporization or cystectomy.

DESIGN

A retrospective study with prospective recording of data.

SETTING

University hospital.

PATIENTS

One hundred and forty-two patients with symptomatic endometriomas.

INTERVENTIONS

Patients underwent a standardized laparoscopic stripping technique (Group 1) or cyst vaporization with CO₂ fiber laser (Group 2). Patients wishing to become pregnant were allowed to attempt a spontaneous conception after surgery. If spontaneous conception failed, patients were referred for in vitro fertilization (IVF).

MEASUREMENTS AND MAIN RESULTS

The primary objective was to compare pregnancy rates between the 2 groups. The secondary objective was the identification of independent predictors of pregnancy. Thirty-nine women in Group 1 (53.4%) and 39 women in Group 2 (56.5%) desired to conceive after surgery. Three patients (7.7%) in Group 1 became pregnant following donor-IVF and were excluded. Pregnancies were recorded in 72.2% of patients treated with cystectomy and in 74.3% of those managed with CO₂ fiber laser (p = .83). Twenty patients (55.6%) in Group 1 and 14 patients (35.9%) in Group 2 conceived spontaneously (p = .08). Among patients who failed spontaneous conception, 21 patients (28%) achieved pregnancy through IVF (Group 1: n = 6, 16.7%; Group 2: n = 15, 38.5%; p = .08). Twenty patients (26.7%) never became pregnant. Age at the time of surgery (odds ratio (OR) = 0.86; 95% Confidence intervals (CI): 0.78-0.96, p = .002) and duration of infertility (OR=0.80; 95% CI: 0.69-0.92, p = .006) were identified as independent indicators for pregnancy.

CONCLUSION

CO₂ laser-treated endometrioma is associated with pregnancy rates equal to those observed after cystectomy and favorable IVF outcomes. The one step CO₂ fiber laser technique may represent a viable alternative to cystectomy.

Evidence in Support for the Progressive Nature of Ovarian Endometriomas

CONTEXT

Whether endometriosis is a progressive disease is a highly contentious issue. While progression is reported to be unlikely in asymptomatic deep endometriosis, progression in symptomatic deep endometriosis has recently been reported, especially in menstruating women. However, pathophysiological reasons for these differences are unclear.

OBJECTIVE

This study was designed to investigate whether ovarian endometrioma (OE) is progressive or not.

SETTING, DESIGN, PATIENTS, INTERVENTION AND MAIN OUTCOME MEASURES

Thirty adolescent patients, aged 15 to 19 years, and 32 adult patients, aged 35 to 39 years, all laparoscopically and histologically diagnosed with OE, were recruited into this study after informed consent. Their demographic and clinical information were collected. Their OE tissue samples were collected and subjected to immunohistochemical analysis for E-cadherin, α-smooth muscle actin (α-SMA), desmin, and adrenergic receptor β2 (ADRB2), as well as quantification of lesional fibrosis by Masson trichrome staining.

RESULTS

OE lesions from the adolescent and adult patients are markedly different, with the latter exhibiting more extensive and thorough progression and more extensive fibrosis, suggesting that lesions in adults progressed to a more advanced stage. Adult lesions and higher staining level of α-SMA and ADRB2 are positively associated with the extent of lesional fibrosis, while the lesion size and the E-cadherin staining are negatively associated.

CONCLUSIONS

Our data provide a more definitive piece of evidence suggesting that OE is a progressive disease, since the adult lesions have had a longer time to progress. In addition, the pace of progression depends on lesional age as well as the severity of endometriosis-associated dysmenorrhea, if any.

The establishment of a mouse model of deep endometriosis

STUDY QUESTION

Is it possible to establish a mouse model of deep endometriosis (DE)?

SUMMARY ANSWER

A mouse DE model that is macroscopically and microscopically similar to nodular lesions in humans can be constructed in as short as 3 weeks by intraperitoneal injection of uterine fragments along with the infusion of substance P (SP) and/or calcitonin gene-related peptide (CGRP).

WHAT IS KNOWN ALREADY

Although a baboon DE model was reported 5 years ago, its prohibitive cost and demand for facilities and expertise associated with the use of non-human primates put its use out of reach for most laboratories.

STUDY DESIGN, SIZE, DURATION

A total of 48 female Balb/C mice were used for this study. Among them, 16 were randomly selected as donors that contributed uterine fragments, and the remaining 32 were recipient mice. The mice with induced endometriosis were followed up for 3-4 weeks.

PARTICIPANTS/MATERIALS, SETTING, METHODS

One day before the induction of endometriosis by intraperitoneal injection of uterine fragments, osmotic pumps were inserted into equal groups of recipient mice to infuse either sterile saline, SP, CGRP, or both SP and CGRP. The hotplate test was administrated to all mice at the baseline and before and after induction of endometriosis. Four (3 for the SP+CGRP group) weeks after induction, all mice were sacrificed. Their endometriotic lesions were excised, weighed and processed for histopathologic examination, and histochemistry, immunohistochemistry and immunofluorescence analyses of markers of proliferation, angiogenesis, epithelial-mesenchymal transition (EMT), fibroblast-to-myofibroblast transdifferentiation (FMT), smooth muscle metaplasia (SMM), mesothelial-mesenchymal transition (MMT) and endothelial-mesenchymal transition (EndoMT) were done. The extent of lesional fibrosis was evaluated by Masson trichrome staining. To further evaluate surrounding organ/tissue invasion, the peritoneal areas adhesive to the lesions were excised for immunohistochemical analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Endometriotic lesions in mice treated with SP and/or CGRP satisfied all requirements for DE, i.e. presence of endometrial epithelial and stromal cells, abundance of fibromuscular content, and encapsulation in surrounding tissues or organs. The lesion weight in the CGRP, SP and SP+CGRP groups was 1.62, 2.14 and 2.18-fold, respectively, heavier than that of control group. Concomitantly, the SP, CGRP and SP+CGRP groups had significantly shorter hotplate latency than that of control group. Lesions in mice treated with SP and/or CGRP, especially with SP+CGRP, exhibited characteristics consistent with EMT, FMT, SMM and extensive fibrosis, along with signs of MMT and EndoMT. Lesional invasion into surrounding tissues/organs was found to be 25.0, 75.0 and 87.5% in mice treated with CGRP, SP and SP+CGRP, but none in control mice.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study is limited by the use of histologic and immunohistochemistry analyses only and lacks molecular data.

WIDER IMPLICATIONS OF THE FINDINGS

The establishment of a mouse DE model supports the idea that endometriotic lesions are wounds undergoing repeated tissue injury and repair and underscores the importance of microenvironments in shaping the lesions' destiny. In addition, signs consistent with MMT and EndoMT indicate that there may be more culpable factors that still remain unidentified and should be pursued in the future. Moreover, the close correlation between the extent of lesional fibrosis and markers of EMT, MMT, EndoMT, FMT and SMM as shown here should facilitate our understanding of the molecular mechanisms underlying the DE pathophysiology. Since this DE model is based on a biologically plausible and evidence-backed theory, it should shed much needed insight into the molecular mechanisms underlying the pathophysiology of DE.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by Grants 81471434 (S.W.G.), 81530040 (S.W.G.), 81771553 (S.W.G.), 81671436 (X.S.L.) and 81871144 (X.S.L.) from the National Natural Science Foundation of China. None of the authors has any conflict of interest to disclose.

Early maternal separation accelerates the progression of endometriosis in adult mice

BACKGROUND

A large body of research highlights the importance of early-life environmental impact on the health outcome in adulthood. However, whether early-life adversity (ELA) has any impact on the development of endometriosis is completely unclear. In this study, we tested the hypothesis that ELA, as manifested by neonatal separation, can accelerate the progression of endometriosis in mouse through activation of the adrenergic receptor β2 (ADRB2) signaling pathway, leading to increased angiogenesis and progression of endometriotic lesions.

METHODS

Eight female Balb/C mice, in late pregnancy, were used used for this study, which later gave birth to 22 female newborn pubs. Eleven additional female Balb/C mice were also used as donors of uterine tissues. The 22 newborn pubs were randomly divided into 2 equal-sized groups, maternal separation (MS) and no separation (NS). Pubs in the MS group were separated from their dams for 3 h/day from postnatal day (PND) 1 to 21, while those in the NS control remained in the home cage with their dams. In adulthood (8-week old), 3 mice in each group were randomly selected to undergo a battery of behavior tests. The remaining 8 mice in each group were induced with endometriosis by intraperitoneal injection of uterine fragments from donor mice. Four weeks after the induction, all mice were sacrificed and their endometriotic lesions were excised for quantification and then prepared for immunohistochemistry analysis.

RESULTS

We confirmed that MS during infancy resulted in anxiety and depression-like behaviors as previously reported. We also found that in MS mice the lesion weight was increased by over 2 folds and generalized hyperalgesia was also significantly increased as compared with NS mice. Immunostaining analysis demonstrated that MS accelerated the development of endometriosis likely through decreased dopamine receptor D2 (DRD2) expression and activation of the ADRB2/cAMP-response element binding protein (CREB) signaling pathway, leading to increased angiogenesis and progression of endometriotic lesions.

CONCLUSIONS

Exposure of female mouse pups to ELA such as MS during their infancy period accelerates the progression of endometriosis, possibly through altered neuronal wiring and hyperactivity of the hypothalamic-pituitary-adrenal axis.

Platelets induce endothelial-mesenchymal transition and subsequent fibrogenesis in endometriosis

RESEARCH QUESTION

Do endometriotic lesions undergo endothelial-mesenchymal transition (EndoMT)?

DESIGN

Lesion samples from 30 patients with ovarian endometriomas and deep endometriosis, and control endometrial tissue samples from 30 women without endometriosis, were analysed. In-vitro experimentation using the human umbilical vein endothelial cell (HUVEC) line were conducted. Immunofluorescence staining and immunohistochemistry analysis using antibodies against endothelial cell and mesenchymal cell markers were conducted. The HUVEC cells were co-cultured with activated platelets or control medium with and without neutralization of TGF-β1 PDGFR, or both. Their morphology, proliferation and expression levels of genes and proteins known to be involved in EndoMT were evaluated, along with their migratory and invasive propensity, contractility and collagen production capability.

RESULTS

The proportion of CD31 and FSP-1 dual-positive cells in FSP-1+ fibroblasts was 74.7% (±5.4%) in ovarian endometrioma lesions, significantly higher than that in deep endometriosis lesions (26.8% ± 26.0%; P = 5.7 × 10^-5), and was zero in normal endometrium. The extent of lesional fibrosis correlated positively with staining levels of the lesional mesenchymal markers FSP-1 and α-SMA (r = 0.91; P < 2.2 × 10^-16, r = 0.81; P = 5.8 × 10^-15, respectively). Human endothelial cells co-cultured with activated platelets acquire a morphology suggestive of EndoMT, concomitant with increased proliferation, loss of CD31 but marked increase in expression of mesenchymal markers. Morphological and gene and protein expression changes are accompanied by functional differentiation reflected by increased migratory and invasive capacity, contractility and collagen production. Neutralization of TGF-β1 and PDGFR signalling abolished platelet-induced EndoMT in human endothelial cells.

CONCLUSIONS

Multiple sources of myofibroblasts exist in endometriotic lesions, and implicates platelets, EndoMT, or both, as potential therapeutic targets for treating endometriosis.

Nanoparticle-Based Platform for Activatable Fluorescence Imaging and Photothermal Ablation of Endometriosis

Endometriosis is a painful disorder where endometrium-like tissue forms lesions outside of the uterine cavity. Intraoperative identification and removal of these lesions are difficult. This study presents a nanoplatform that concurrently delineates and ablates endometriosis tissues using real-time near-infrared (NIR) fluorescence and photothermal therapy (PTT). The nanoplatform consists of a dye, silicon naphthalocyanine (SiNc), capable of both NIR fluorescence imaging and PTT, and a polymeric nanoparticle as a SiNc carrier to endometriosis tissue following systemic administration. To achieve high contrast during fluorescence imaging of endometriotic lesions, nanoparticles are constructed to be non-fluorescent prior to internalization by endometriosis cells. In vitro studies confirm that these nanoparticles activate the fluorescence signal following internalization in macaque endometrial stromal cells and ablate them by increasing cellular temperature to 53 ^° C upon interaction with NIR light. To demonstrate in vivo efficiency of the nanoparticles, biopsies of endometrium and endometriosis from rhesus macaques are transplanted into immunodeficient mice. Imaging with the intraoperative Fluobeam 800 system reveals that 24 h following intravenous injection, nanoparticles efficiently accumulate in, and demarcate, endometriotic grafts with fluorescence. Finally, the nanoparticles increase the temperature of endometriotic grafts up to 47 °C upon exposure to NIR light, completely eradicating them after a single treatment.

Platelets induce increased estrogen production through NF-κB and TGF-β1 signaling pathways in endometriotic stromal cells

Endometriosis is estrogen-dependent disorder. Two theories provide the explanations for the increased estrogen production. One is the feed-forward loop model linking inflammation and estrogen production. The more recent model evokes the tissue hypoxia resulting from endometrial debris detached and then regurgitated to the peritoneal cavity. Both models tacitly assume that everything occurs within the endometriotic stromal cells, seemingly without the need for exogenous factors. This study was undertaken to investigate as whether platelets may be responsible for local estrogen overproduction. We employed in vitro experimentation that evaluated the 17β-estradiol (E₂) levels in endometriotic stromal cells treated with activated platelets, and the genes and protein expression levels of StAR, HSD3B2, aromatase, and HSD17B1, as well as their upstream genes/proteins such as NF-κB, TGF-β1, HIF-1α, SF-1 and phosphorylated CREB. In addition, we conducted 2 animal experimentations using platelet depletion/infusion and also neutralization of NF-κB and TGF-β1, followed by immunohistochemistry analysis of involved in StAR, HSD3B2, aromatase, and HSD17B1, as well as SF-1 and p-CREB. We found that treatment of endometriotic stromal cells by activated platelets increase the E₂ production by 4.5 fold, and concomitant with increased gene and protein expression of StAR, HSD3B2, aromatase, and HSD17B1, the four genes/enzymes important to estrogen synthesis, along with their upstream genes HIF-1α, SF-1 and phosphorylated CREB. Moreover, platelets activate these genes through the activation of NF-κB and/or TGF-β1, and antagonism of either signaling pathway can abolish the induction of the 4 genes and thus increased estrogen production. The two animal experimentations confirmed these changes. Thus, platelets increase the E₂ production in endometriotic stromal cells through upregulation of StAR, HSD3B2, aromatase, and HSD17B1 via the activation of NF-κB and/or TGF-β1. These findings provide a yet another compelling piece of evidence that endometriotic lesions are indeed wounds undergoing repeated tissue injury and repair. They strongly indicate that non-hormonal therapeutics for endometriosis is theoretically viable, with anti-platelet therapy being one promising avenue.

Endometriosis-Associated Pain - Do Preclinical Rodent Models Provide a Good Platform for Translation?

Pelvic pain is a common symptom of endometriosis. Our understanding of its etiology remains incomplete and medical management is limited by poor translation from preclinical models to clinical trials. In this review, we briefly consider the evidence, or lack thereof, that different subtypes of lesion, extra-uterine bleeding, and neuropathic pathways add to the complex and heterogeneous pain experience of women with the condition. We summarize the studies in rodent models of endometriosis that have used behavioral endpoints (evoked and non-evoked) to explore mechanisms of endometriosis-associated pain. Lesion innervation, activation of nerves by pronociceptive molecules released by immune cells, and a role for estrogen in modulating hyperalgesia are key endometriosis-associated pain mechanisms replicated in preclinical rodent models. The presence of ectopic (full thickness uterus or endometrial) tissue may be associated with changes in the spinal cord and brain, which appear to model changes reported in patients. While preclinical models using rats and mice have yielded insights that appear relevant to mechanisms responsible for the development of endometriosis-associated pain, they are limited in scope. Specifically, most studies are based on models that only resulted in the formation of superficial lesions and use induced (evoked) behavioral 'pain' tests. We suggest that translation for patient benefit will be improved by new approaches including models of ovarian and deep infiltrating disease and measurement of spontaneous pain behaviors. Future studies must also capitalize on new advances in the wider field of pain medicine to identify more effective treatments for endometriosis-associated pain.

Rethinking mechanisms, diagnosis and management of endometriosis

Endometriosis is a chronic inflammatory disease defined as the presence of endometrial tissue outside the uterus, which causes pelvic pain and infertility. This disease should be viewed as a public health problem with a major effect on the quality of life of women as well as being a substantial economic burden. In light of the considerable progress with diagnostic imaging (for example, transvaginal ultrasound and MRI), exploratory laparoscopy should no longer be used to diagnose endometriotic lesions. Instead, diagnosis of endometriosis should be based on a structured process involving the combination of patient interviews, clinical examination and imaging. Notably, a diagnosis of endometriosis often leads to immediate surgery. Therefore, rethinking the diagnosis and management of endometriosis is warranted. Instead of assessing endometriosis on the day of the diagnosis, gynaecologists should consider the patient's 'endometriosis life'. Medical treatment is the first-line therapeutic option for patients with pelvic pain and no desire for immediate pregnancy. In women with infertility, careful consideration should be made regarding whether to provide assisted reproductive technologies prior to performing endometriosis surgery. Modern endometriosis management should be individualized with a patient-centred, multi-modal and interdisciplinary integrated approach.

Anti-inflammatory cytokines in endometriosis

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

Neuropeptides Substance P and Calcitonin Gene Related Peptide Accelerate the Development and Fibrogenesis of Endometriosis

Endometriotic lesions are known to be hyperinnervated, especially in lesions of deep endometriosis (DE), which are frequently in close proximity to various nerve plexuses. DE lesions typically have higher fibromuscular content than that of ovarian endometriomas (OE) lesions, but the underlying reason remains elusive. Aside from their traditional role of pain transduction, however, whether or not sensory nerves play any role in the development of endometriosis is unclear. Here, we show that, thorough their respective receptors neurokinin receptor 1 (NK1R), calcitonin receptor like receptor (CRLR), and receptor activity modifying protein 1 (RAMP-1), neuropeptides substance P (SP) and calcitonin gene related peptide (CGRP) induce epithelial-mesenchymal transition (EMT), fibroblast-to-myofibroblast transdifferentiation (FMT) and further turn stromal cells into smooth muscle cells (SMCs) in endometriotic lesions, resulting ultimately in fibrosis. We show that SP and CGRP, or the rat dorsal root ganglia (DRG) supernatant, through the induction of NK1R and CGRP/CRLR/RAMP-1 signaling pathways, promoted EMT, FMT and SMM in endometriosis, resulting in increased migratory and invasive propensity, cell contractility, production of collagen, and eventually to fibrosis. Neutralization of NK1R and/or CGRP/CRLR/RAMP-1 abrogated these processes. Extended exposure of endometriotic stromal cells to SP and/or CGRP or the DRG supernatant induced increased expression of α-SMA, desmin, oxytocin receptor, and smooth muscle myosin heavy-chain. Finally, we show that DE lesions had significantly higher nerve fiber density, increased staining levels of α-SMA, NK1R, CRLR, and RAMP-1, concomitant with higher lesional fibrotic content than that of OE lesions. The extent of lesional fibrosis correlated positively with the staining levels of NK1R, CRLR, and RAMP-1, as well as the nerve fiber density in lesions. Thus, this study provides another piece of evidence that sensory nerves play an important role in promoting the development and fibrogenesis of endometriosis. It explains as why DE frequently have higher fibromuscular content than that of OE, highlights the importance of lesional microenvironment in shaping the lesional fate, gives more credence to the idea that ectopic endometrium is fundamentally wounds that go through repeated tissue injury and repair, and should shed much needed light into the pathophysiology of endometriosis.

Scutellarin Suppresses Platelet Aggregation and Stalls Lesional Progression in Mouse With Induced Endometriosis

Platelets play an important role in the development of endometriosis. Scutellarin is a flavonoid isolated from a medicinal herb traditionally used as a potent antiplatelet agent. In this study, we sought to evaluate its potential therapeutic effect, if any, in mice with induced endometriosis. Endometriosis was induced in 27 female Balb/c mice by intraperitoneal injection of uterine fragments. Two weeks after the induction, the 27 mice were randomly divided in equal sizes into 3 groups: untreated, which received only vehicle, and low-dose and high-dose groups, which received low- and high dose of scutellarin treatment. Hotplate test was administrated to all mice before endometriosis induction, and before and after the scutellarin treatment. Two weeks after the treatment, a blood sample was drawn before sacrifice and all lesions were harvested. The peripheral platelet activation rate and total lesion weight were assessed, and immunohistochemistry and histochemistry analyses were performed to evaluate the extent of proliferation, angiogenesis, fibroblast-to-myofibroblast transdifferentiation (FMT), and fibrosis in lesions. Compared with untreated mice, mice in both low-dose and high-dose groups had significantly reduced lesion weight and improved hyperalgesia. Scutellarin also reduced the peripheral-activated platelets rate and resulted in significantly reduced platelet aggregation, cellular proliferation, angiogenesis, the extent of FMT, and the extent of fibrosis in lesions. Thus, we conclude that scutellarin is efficacious in treating endometriosis in vivo by suppressing platelet aggregation, inhibiting proliferation, angiogenesis, and fibrogenesis, resulting in reduced lesion size and improved pain behavior. As such, scutellarin may be a potentially promising therapeutics for the treatment of endometriosis.

Cancer driver mutations in endometriosis: Variations on the major theme of fibrogenesis

BACKGROUND

One recent study reports cancer driver mutations in deep endometriosis, but its biological/clinical significance remains unclear. Since the natural history of endometriosis is essentially gradual progression toward fibrosis, it is thus hypothesized that the six driver genes reported to be mutated in endometriosis (the RP set) may play important roles in fibrogenesis but not necessarily malignant transformation.

METHODS

Extensive PubMed search to see whether RP and another set of driver genes not yet reported (NR) to be mutated in endometriosis have any roles in fibrogenesis. All studies reporting on the role of fibrogenesis of the genes in both RP and NR sets were retrieved and evaluated in this review.

RESULTS

All six RP genes were involved in various aspects of fibrogenesis as compared with only three NR genes. These nine genes can be anchored in networks linking with their upstream and downstream genes that are known to be aberrantly expressed in endometriosis, piecing together seemingly unrelated findings.

CONCLUSIONS

Given that somatic driver mutations can and do occur frequently in physiologically normal tissues, it is argued that these mutations in endometriosis are not necessarily synonymous with malignancy or premalignancy, but the result of enormous pressure for fibrogenesis.

The M2a macrophage subset may be critically involved in the fibrogenesis of endometriosis in mice

RESEARCH QUESTION

Recent research has shown that endometriotic lesions are essentially wounds that undergo repeated tissue injury and repair, which results in epithelial-mesenchymal transition, fibroblast-to-myofibroblast transdifferentiation, smooth muscle metaplasia and ultimately fibrosis. Macrophages are a key regulator of tissue repair and fibrogenesis. But do macrophages also play a role in fibrogenesis of endometriosis, and, if yes, which subset of macrophages?

DESIGN

To elucidate the role of macrophages in fibrogenesis of endometriosis, we conducted three experiments in mice. In experiment 1, endometriotic tissue samples from female Balb/C mice with induced endometriosis were serially harvested to evaluate the role of macrophages in fibrogenesis. In experiments 2 and 3, female transgenic mice (C57BL/6J background) expressing the human diphtheria toxin receptor under the control of the CD11b promoter had macrophage depletion by diphtheria toxin injection after induction of endometriosis. Additionally, in experiment 3, adoptive transfer of different subsets of macrophage was carried out after macrophage depletion.

RESULTS

Lesional infiltration of M2 macrophages increased progressively as lesions progressed undisturbed, concomitant with progressive epithelial-mesenchymal transition, fibroblast-to-myofibroblast transdifferentiation and fibrosis. Macrophage depletion after induction of endometriosis significantly reduced lesional infiltration of total macrophages, significantly reduced lesional infiltration of M2 macrophages and significantly reduced lesional fibrotic content and lesion weight (P < 0.05). Finally, adoptive transfer of M2a, but not M1 or M2c macrophages, systemically after macrophage depletion significantly increased the extent of fibrosis in lesions (P = 1.6 × 10^-10).

CONCLUSIONS

The identification of a particular macrophage subset in fibrogenesis of endometriosis should further help to shed new light on the pathophysiology of endometriosis.