The peritoneum--an important factor for pathogenesis and pain generation in endometriosis

Endometriosis, an Ongoing Pain—Step-by-Step Treatment

Endometriosis is a disease that is becoming more and more challenging for the medical community. The current therapeutic concepts (surgical therapy and/or hormonal therapies) often do not lead to sufficient pain control, and late diagnosis and high recurrence rates mean that women affected by the disease can suffer for decades before receiving proper treatment. Although the introduction of certified endometriosis centers has created contact points for surgical therapies performed by endometriosis experts, these centers are not sufficient to offer the affected patients the all-encompassing long-term support they need. In recent years, new findings regarding the pathogenesis and correlations of the pain phenomena caused by endometriosis have shown that conventional therapy strategies are not adequate and individual long-term concepts must be developed. Not only can endometriosis cause nociceptive pain, but it can also lead to a nociplastic reaction with central sensitization. Hence, aside from the classic cyclic complaints, patients increasingly suffer from atypical pain. Due to the high number of affected patients who are treated inadequately, it is necessary for gynecologists in private practices to become familiar with multimodal treatment concepts since they are the central point of contact of their patients. The following article will provide an overview of treatment strategies for chronic symptomatic endometriosis.

Near-Infrared Fluorescence Imaging for the Intraoperative Detection of Endometriosis: A Pilot Study

Introduction: Endometriosis surgery is associated with a high risk of reoperation due to an insufficient recognition of endometriotic lesions. Our aim was to explore the role of near-infrared fluorescence (NIRF) imaging for the visualization and identification of endometriotic lesions next to conventional white light (WL) laparoscopy. Materials and methods: Fifteen women scheduled for diagnostic laparoscopy in whom peritoneal endometriosis was suspected were included. Peritoneal exploration was performed in WL, followed by NIRF imaging after ICG administration. Biopsies of all the suspected lesions were taken for histological examination. Subjective evaluations of the equipment and NIRF imaging were also performed. Results: Only 61% (44) of the biopsied lesions contained endometriosis. The positive predictive value (PPV) for the lesions found in WL was 64%. The PPV for the lesions found under NIRF was 69% and the PPV for the lesions found in both modes was 61%. The mean satisfaction of surgeons regarding the surgical procedure and equipment using both imaging modalities was 6.5 (p > 0.05) on a 10 item Likert scale and the mean satisfaction with the quality of the NIRF imaging was 7.4 (p > 0.05). Conclusion: In this study, the additional value of NIRF imaging, although feasible, was found to be limited for the intraoperative detection of endometriotic lesions.

Neurogenic Inflammation in the Context of Endometriosis-What Do We Know?

Endometriosis (EM) is an estrogen-dependent disease characterized by the presence of epithelial, stromal, and smooth muscle cells outside the uterine cavity. It is a chronic and debilitating condition affecting ~10% of women. EM is characterized by infertility and pain, such as dysmenorrhea, chronic pelvic pain, dyspareunia, dysuria, and dyschezia. Although EM was first described in 1860, its aetiology and pathogenesis remain uncertain. Recent evidence demonstrates that the peripheral nervous system plays an important role in the pathophysiology of this disease. Sensory nerves, which surround and innervate endometriotic lesions, not only drive the chronic and debilitating pain associated with EM but also contribute to a growth phenotype by secreting neurotrophic factors and interacting with surrounding immune cells. Here we review the role that peripheral nerves play in driving and maintaining endometriotic lesions. A better understanding of the role of this system, as well as its interactions with immune cells, will unearth novel disease-relevant pathways and targets, providing new therapeutics and better-tailored treatment options.

Peritoneal Modulators of Endometriosis-Associated Ovarian Cancer

Ovarian cancer is the 4th largest cause of cancer death in women. Approximately 10-15% of women of childbearing age suffer from endometriosis. Endometriosis is defined by the growth and presence of endometrial tissue (lesions) outside of the uterus. The women with endometriosis also have an increased presence of peritoneal fluid (PF) that comprises of inflammatory cells, growth factors, cytokines/chemokines, etc. Epidemiological studies have shown that >3% of women with endometriosis develop ovarian cancer (low-grade serous or endometrioid types). Our hypothesis is that the PF from women with endometriosis induces transformative changes in the ovarian cells, leading to ovarian cancer development. PF from women with and without endometriosis was collected after IRB approval and patient consent. IOSE (human normal ovarian epithelial cells) and TOV-21G cells (human ovarian clear cell carcinoma cell line) were treated with various volumes of PF (no endometriosis or endometriosis) for 48 or 96 h and proliferation measured. Expression levels of epigenetic regulators and FoxP3, an inflammatory tumor suppressor, were determined. A Human Cancer Inflammation and Immunity Crosstalk RT2 Profiler PCR array was used to measure changes in cancer related genes in treated cells. Results showed increased growth of TOV-21G cells treated with PF from women with endometriosis versus without endometriosis and compared to IOSE cells. Endo PF treatment induced EZH2, H3K27me3, and FoxP3. The RT2 PCR array of TOV-21G cells treated with endo PF showed upregulation of various inflammatory genes (TLRs, Myd88, etc.). These studies indicate that PF from women with endometriosis can both proliferate and transform ovarian cells and hence this microenvironment plays a major mechanistic role in the progression of endometriosis to ovarian cancer.

Eliapixant is a selective P2X3 receptor antagonist for the treatment of disorders associated with hypersensitive nerve fibers

ATP-dependent P2X3 receptors play a crucial role in the sensitization of nerve fibers and pathological pain pathways. They are also involved in pathways triggering cough and may contribute to the pathophysiology of endometriosis and overactive bladder. However, despite the strong therapeutic rationale for targeting P2X3 receptors, preliminary antagonists have been hampered by off-target effects, including severe taste disturbances associated with blocking the P2X2/3 receptor heterotrimer. Here we present a P2X3 receptor antagonist, eliapixant (BAY 1817080), which is both highly potent and selective for P2X3 over other P2X subtypes in vitro, including P2X2/3. We show that eliapixant reduces inflammatory pain in relevant animal models. We also provide the first in vivo experimental evidence that P2X3 antagonism reduces neurogenic inflammation, a phenomenon hypothesised to contribute to several diseases, including endometriosis. To test whether eliapixant could help treat endometriosis, we confirmed P2X3 expression on nerve fibers innervating human endometriotic lesions. We then demonstrate that eliapixant reduces vaginal hyperalgesia in an animal model of endometriosis-associated dyspareunia, even beyond treatment cessation. Our findings indicate that P2X3 antagonism could alleviate pain, including non-menstrual pelvic pain, and modify the underlying disease pathophysiology in women with endometriosis. Eliapixant is currently under clinical development for the treatment of disorders associated with hypersensitive nerve fibers.

Pathogenesis of Endometriosis: The Origin of Pain and Subfertility

Endometriosis (EM) and adenomyosis (AM) are common conditions with pain and infertility as the principal symptoms. The pathophysiology of pain in EM and AM comprises sensory and somatoform pain mechanisms. Over time, these may aggravate and lead to individual complex disease patterns if not diagnosed and treated. Despite the known facts, several years often pass between the onset of symptoms and diagnosis. Chronic pain disorders with changes on a neuronal level frequently arise and are linked to depressive disorders, with the process becoming a vicious cycle. Additionally, women with EM and AM suffer from sub- and infertility. Low fecundity rates are caused by anatomical changes in combination with behavioral changes in the sexual activity of women with chronic pain as well as local proinflammatory factors that not only decrease implantation rates but also promote early abortions.

Functional changes of immune cells: signal of immune tolerance of the ectopic lesions in endometriosis?

RESEARCH QUESTION

What is the potential role of immune cells and their inflammatory cytokines in the pathogenesis, development and establishment of endometriosis?

DESIGN

Peritoneal fluid from 59 women (43 with endometriosis and 16 controls) who had undergone laparoscopic surgery was analysed. Changes in the population of innate and adaptive immune cells, cytokines, chemokines and growth factor expression were measured by flow cytometry, Luminex Technology and enzyme-linked immunosorbent assay.

RESULTS

No differences were found in the frequencies of the innate and adaptive immune cells between women with and without endometriosis. In the peritoneal fluid of women with endometriosis, IL-1β, IL-1RN, IL-2, IL-4, IL-8, IL-10, IL-12 (p70), IL-17α, FGF2, G-CSF, MCP-1, MIP-1α and TNF-α were significantly increased compared with controls. A correlation between IL-2, MCP-1, MIP-1α, TNF-α and the severity of endometriosis was observed. The concentration of neopterin, a possible biomarker for this disease, was increased in women with endometriosis compared with controls.

CONCLUSIONS

The functional activity of immune cells seemed to be reduced despite their numbers remaining unchanged. The data indicate that a shift of T_H cytokine profile occurs, which increases the T_H1-T_H2 ratio. This is driven by the increased levels of the cytokines (TNF-α and IL-2) in women with severe endometriosis.

Peritoneal Modulators of EZH2-miR-155 Cross-Talk in Endometriosis

Activation of trimethylation of histone 3 lysine 27 (H3K27me3) by EZH2, a component of the Polycomb repressive complex 2 (PRC2), is suggested to play a role in endometriosis. However, the mechanism by which this complex is dysregulated in endometriosis is not completely understood. Here, using eutopic and ectopic tissues, as well as peritoneal fluid (PF) from IRB-approved and consented patients with and without endometriosis, the expression of PRC2 complex components, JARID2, miR-155 (known regulators of EZH2), and a key inflammatory modulator, FOXP3, was measured. A higher expression of EZH2, H3K27me3, JARID2, and FOXP3 as well as miR-155 was noted in both the patient tissues and in endometrial PF treated cells. Gain-or-loss of function of miR-155 showed an effect on the PRC2 complex but had little effect on JARID2 expression, suggesting alternate pathways. Chromatin immunoprecipitation followed by qPCR showed differential expression of PRC2 complex proteins and its associated binding partners in JARID2 vs. EZH2 pull down assays. In particular, endometriotic PF treatment increased the expression of PHF19 (p = 0.0474), a gene silencer and co-factor that promotes PRC2 interaction with its targets. Thus, these studies have identified the potential novel crosstalk between miR-155-PRC2 complex-JARID2 and PHF19 in endometriosis, providing an opportunity to test other epigenetic targets in endometriosis.

[Management of endometriosis pain : Stage-based treatment strategies and clinical experience]

BACKGROUND

Endometriosis is associated with various types of intense pain. In addition to nociceptive pain, there is also a nociplastic reaction with central sensitization. Atypical symptoms such as acyclic lower abdominal pain, radiating pain, non-specific bladder and intestinal complaints or even depression are frequent as are classic cyclical complaints such as severe dysmenorrhea, cyclical lower abdominal pain, dyspareunia, dysuria and dyschezia. In cases of a diverse range of symptoms, patients often consult not just gynecologists but specialists from other disciplines (e.g., internal medicine, gastroenterology, orthopedics, pain therapy, psychology).

AIMS

Overview about the pathophysiology and complexity of the disease and the resulting treatment options. A multimodal interdisciplinary concept might be able to take into consideration all aspects of the complex disease.

METHODS

Interdisciplinary concepts should be involved in the treatment of endometriosis patients along with hormonal and surgical therapy, which are generally under the supervision of a gynecologist. Pain management, dietary changes, psychological support, as well as physiotherapy should be included. The present article is intended to provide an overview of possible treatment strategies for chronic, symptomatic endometriosis.

CONCLUSION

The use of multimodal treatment strategies regarding the complex pathophysiological aspects of this disease might be helpful in significantly improving the quality of life of endometriosis patients.

When and how should peritoneal endometriosis be operated on in order to improve fertility rates and symptoms? The experience and outcomes of nearly 100 cases

Purpose

To analyze the follow-up results of patients suffering from symptomatic early-stage endometriosis after a consistent laparoscopic peritoneal stripping of the altered peritoneum (peritoneal endometriosis and surrounding inflamed tissue) was performed. This type of endometriosis is resistant to medical therapy and/or impairs fertility.

Methods

Using our prospectively maintained database, we were able to identify all symptomatic women with the suspicion of only peritoneal endometriosis who underwent laparoscopy at our endometriosis center over a period of 5 years. All procedures were carried out in a standardized fashion by one single surgeon, who is highly experienced in minimal invasive surgery, and included a suspended hormonal pretreatment for 2 months. Postoperative outcomes including complications, fertility and recurrence rates were analysed.

Results

Laparoscopic peritonectomy was performed on 94 women. Follow-up data were available in 87% of these cases. At the time of surgery, almost all patients tested showed signs of stage I or II endometriosis (44.7 and 48.9%, respectively). More than three-quarters of the women reported pain relief, inter alia, due to the post-surgical hormonal therapy. About one-third of the patients wanted to have children after the procedure. 62% of them became pregnant and the majority did so without the need for assisted reproductive therapy. In seven women a re-operation was performed.

Conclusion

According to our data, a consistent excision of altered peritoneum followed by adjuvant hormonal therapy and multimodal concepts results in better outcomes for the patient, particularly in regards to pregnancy and recurrence rates.

Post-operative management and follow-up of surgical treatment in the case of rectovaginal and retrocervical endometriosis

Introduction

Deep infiltrating endometriosis (DIE) affects between 3.8% and 37% of all endometriosis patients, mostly affecting rectovaginal septum or retrocervical space and characterized by the severe endometriosis-related complaints. Nowadays, generally managed with surgery. However, this is associated with a risk of postoperative complications. To better evaluate intra- and postoperative complications and outcomes for rectovaginal (RVE) and retrocervical endometriosis (RCE), the preoperative management should be accurately described and compared.

Methodology

This is a cohort retrospective study performed at the Endometriosis Centre of Charité-University Clinic, Berlin. 34 patients were investigated in their reproductive age, n = 19 with RVE and n = 15 RCE, operated between 2011 and 2015. The surgical approach was divergent in both groups. Single laparoscopy was performed in RCE patients (RCEP) and vaginal assisted laparoscopy in RVE patients (RVEP). Long-term postoperative outcome included complications, fertility rate and recurrence rate.

Results

The median follow-up time was three years (y). Symptom-free status was revealed in n = 12 RVEP and n = 9 RCEP. Postoperatively, endometriosis-related complaints were presented in n = 7 RVEP and n = 6 RCEP, but with significant pain relief. From n = 8 RVE patients seeking fertility, pregnancy occurred in n = 7 and from n = 9 RCEP pregnancy appeared in n = 5 patients in the meantime of 6 months. Postoperative complications were reported in n = 1 RVEP with early postoperative bleeding, after ureter leakage and n = 1 RCEP with postoperative anastomotic insufficiency. The postoperative recurrence rate was equivalent to zero.

Conclusion

The appropriate surgical approach for each group, preserving anatomy and functionality of the organs, seems to be very essential and efficient.

Redox regulation of microRNAs in endometriosis-associated pain

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

Characteristics of histologically confirmed endometriosis in cynomolgus monkeys

STUDY QUESTION

What are the characteristics of spontaneous endometriosis in cynomolgus monkeys?

SUMMARY ANSWER

Spontaneous endometriosis in cynomolgus monkeys exhibited similar characteristics to the human disease.

WHAT IS KNOWN ALREADY

One previous report described the prevalence and the basic histopathology of spontaneous endometriosis in cynomolgus monkeys.

STUDY DESIGN, SIZE, DURATION

Endometriotic lesions that had been histologically confirmed in 8 female cynomolgus monkeys between 5 and 21 years old were subjected to study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The monkeys died of, or were sacrificed because of, sickness consequent on endometriosis. Specimens were evaluated histopathologically with haematoxylin and eosin staining, iron staining and immunohistochemistry (CD10, CD31, α-SMA and PGP9.5), and by observing them under a microscope.

MAIN RESULTS AND THE ROLE OF CHANCE

Endometriotic and stromal cells (CD10-positive) with haemorrhage and inflammation were observed. Smooth muscle metaplasia and nerve fibres were also noted in the endometriotic lesions. Endometriotic lesions in lymph nodes were incidentally found.

LIMITATIONS AND REASONS FOR CAUTION

Since laparoscopic analysis for monitoring the disease state was not set as a parameter of the current study, time course changes (progression) of the disease were not assessed.

WIDER IMPLICATIONS OF THE FINDINGS

Further investigation of spontaneous endometriosis in cynomolgus monkeys may contribute to better understanding of the disease pathobiology.

STUDY FUNDING/COMPETING INTEREST(S)

No external funds were used for this study. A.N.K., S.M., S.H., T.I., O.K., A.K. and M.S. are full-time employees of Chugai Pharmaceutical Co., Ltd. R.K. received lecture fees from Chugai Pharmaceutical Co., Ltd., unrelated to the submitted work. S.N., S. O., L.Y., K.Y. and T.S. have nothing to declare.

TRIAL REGISTRATION NUMBER

N/A.

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

BACKGROUND

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

METHODS

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

RESULT

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

CONCLUSIONS

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

Estradiol is a critical mediator of macrophage-nerve cross talk in peritoneal endometriosis

Endometriosis occurs in approximately 10% of women and is associated with persistent pelvic pain. It is defined by the presence of endometrial tissue (lesions) outside the uterus, most commonly on the peritoneum. Peripheral neuroinflammation, a process characterized by the infiltration of nerve fibers and macrophages into lesions, plays a pivotal role in endometriosis-associated pain. Our objective was to determine the role of estradiol (E2) in regulating the interaction between macrophages and nerves in peritoneal endometriosis. By using human tissues and a mouse model of endometriosis, we demonstrate that macrophages in lesions recovered from women and mice are immunopositive for estrogen receptor β, with up to 20% being estrogen receptor α positive. In mice, treatment with E2 increased the number of macrophages in lesions as well as concentrations of mRNAs encoded by Csf1, Nt3, and the tyrosine kinase neurotrophin receptor, TrkB. By using in vitro models, we determined that the treatment of rat dorsal root ganglia neurons with E2 increased mRNA concentrations of the chemokine C-C motif ligand 2 that stimulated migration of colony-stimulating factor 1-differentiated macrophages. Conversely, incubation of colony-stimulating factor 1 macrophages with E2 increased concentrations of brain-derived neurotrophic factor and neurotrophin 3, which stimulated neurite outgrowth from ganglia explants. In summary, we demonstrate a key role for E2 in stimulating macrophage-nerve interactions, providing novel evidence that endometriosis is an estrogen-dependent neuroinflammatory disorder.

Endometriosis is associated with rare copy number variants

Endometriosis is a complex gynecological condition that affects 6-10% of women in their reproductive years and is defined by the presence of endometrial glands and stroma outside the uterus. Twin, family, and genome-wide association (GWA) studies have confirmed a genetic role, yet only a small part of the genetic risk can be explained by SNP variation. Copy number variants (CNVs) account for a greater portion of human genetic variation than SNPs and include more recent mutations of large effect. CNVs, likely to be prominent in conditions with decreased reproductive fitness, have not previously been examined as a genetic contributor to endometriosis. Here we employ a high-density genotyping microarray in a genome-wide survey of CNVs in a case-control population that includes 2,126 surgically confirmed endometriosis cases and 17,974 population controls of European ancestry. We apply stringent quality filters to reduce the false positive rate common to many CNV-detection algorithms from 77.7% to 7.3% without noticeable reduction in the true positive rate. We detected no differences in the CNV landscape between cases and controls on the global level which showed an average of 1.92 CNVs per individual with an average size of 142.3 kb. On the local level we identify 22 CNV-regions at the nominal significance threshold (P<0.05), which is greater than the 8.15 CNV-regions expected based on permutation analysis (P<0.001). Three CNV's passed a genome-wide P-value threshold of 9.3 × 10(-4); a deletion at SGCZ on 8p22 (P = 7.3 × 10(-4), OR = 8.5, Cl = 2.3-31.7), a deletion in MALRD1 on 10p12.31 (P = 5.6 × 10(-4), OR = 14.1, Cl = 2.7-90.9), and a deletion at 11q14.1 (P = 5.7 × 10(-4), OR = 33.8, Cl = 3.3-1651). Two SNPs within the 22 CNVRs show significant genotypic association with endometriosis after adjusting for multiple testing; rs758316 in DPP6 on 7q36.2 (P = 0.0045) and rs4837864 in ASTN2 on 9q33.1 (P = 0.0002). Together, the CNV-loci are detected in 6.9% of affected women compared to 2.1% in the general population.