Future directions in endometriosis research

Overview of miRNAs for the non-invasive diagnosis of endometriosis: evidence, challenges and strategies. A systematic review

OBJECTIVE

The aim of the study was to assess the evidence on miRNAs as biomarkers for the diagnosis of endometriosis, as well as to provide insights into the challenges and strategies associated with the use of these molecules as accessible tools in clinical practice.

METHODS

Systematic review conducted on PubMed®, Latin American and Caribbean Health Sciences Literature (LILACS), MEDLINE® and Web of Science databases using the search terms endometriosis (all fields) AND miRNA (all fields), evaluating all publication up to May 2019.

RESULTS

Most miRNAs found to be dysregulated in this study were harvested from tissue samples, which precludes their use as a non-invasive diagnostic test. However, differential expression of 62 miRNAs was reported in samples that may be used for non-invasive diagnosis of endometriosis, such as blood, serum and plasma.

CONCLUSION

Despite the identification of several candidates, studies are investigatory in nature and have been conducted with small number of samples. Also, no particular miRNA has been validated for diagnostic purposes so far. Studies based primarily on biological samples and applicable to translational research are warranted. Large databases comprising information on sample type and the use of saliva and vaginal fluid for miRNAs identification may prove essential to overcome current barriers to diagnosis of endometriosis.

Using social media to educate women and healthcare providers on endometriosis: preliminary results

Objective:

This study aimed to evaluate the performance of our Facebook fan page and compare it to similar pages.

Methods:

The authors reviewed page-specific metrics provided by Facebook, including number of fans, their age and sex, and country of origin; number of views, likes, and shares tied to our posts. A search for similar fan pages using keyword "endometriosis" found pages in Portuguese, English, and Spanish. They were analyzed for country of origin, authors, number of fans and posts, and were compared to our page.

Results:

Our fan page went online on April 2016 and 127 posts have been published up to December 2017. Most of its 1746 fans (89% women; 11% men) were Brazilians (n=1677). Our audience comprised primarily women aged 25-34 (39%) and 35-44 (30%) years. The most viewed posts discussed thrombosis and oral contraceptives (n =11078); continuous use of oral contraceptives (n=6448); deep endometriosis (n=4425); intrauterine levonorgestrel system (n=4045); IVF and endometriosis (n=2885); and endometriosis and cancer (n=2431). Our search found 399 Facebook pages from 44 different countries. The United States (n=81), Brazil (n=49), and the United Kingdom (n=46) topped the list of countries hosting pages, while most of the fan pages were written in English. The majority of the pages were active and 20% claimed they were based on science. Physicians administered four of the 10 most popular pages. Page heterogeneity prevented comparisons between them.

Conclusion:

Men and women have visited our Facebook fan page to obtain information on endometriosis. The pages found in our search were exceedingly heterogeneous and were not compared. Developing pages with sound information is an important step toward educating individuals about endometriosis and helping them make informed choices on available treatments.

Clinical prediction of deeply infiltrating endometriosis before surgery: is it feasible? A review of the literature

BACKGROUND

Endometriosis is a chronic benign gynecologic disease that can cause pelvic pain and infertility affecting almost 10% of reproductive-age women. Deeply infiltrating endometriosis (DIE) is a specific entity responsible for painful symptoms which are related to the anatomic location of the lesions. Definitive diagnosis requires surgery, and histological confirmation is advisable. The aim of this paper is to review the current literature regarding the possibility of diagnosing DIE accurately before surgery. Despite its low sensitivity and specificity, vaginal examination and evaluation of specific symptoms should not be completely omitted as a basic diagnostic tool in detecting endometriosis and planning further therapeutic interventions. Recently, transvaginal ultrasound (TVUS) has been reported as an excellent tool to diagnose DIE lesions in different locations (rectovaginal septum, retrocervical and paracervical areas, rectum and sigmoid, and vesical wall) with good accuracy.

CONCLUSION

There are neither sufficiently sensitive and specific signs and symptoms nor diagnostic tests for the clinical diagnosis of DIE, resulting in a great delay between onset of symptoms and diagnosis. Digital examination, in addition to TVS, may help to gain better understanding of the anatomical extent and dimension of DIE which is of crucial importance in defining the best surgical approach.

Baboon model for the study of endometriosis

Endometriosis is a benign, estrogen-dependent disease and is now recognized as an enigmatic disease owing to its various clinical manifestations and locations. The lack of a reliable and specific method for the early detection of endometriosis often results in delayed diagnosis. So far, research has born inadequate findings regarding understanding the basic etiology or pathophysiology of endometriosis. Animal models that accurately represent the cellular and molecular changes associated with the initiation and progression of human endometriosis have significant potential to facilitate the development of better methods for the early detection and treatment of endometriosis. A number of animal model systems have been developed for the study of this disease. These models replicate many of the known salient features of human endometriosis. This review provides an insight into the use of the baboon model for studies focused on understanding human endometriosis.

Immune interactions in endometriosis

Endometriosis is a common, complex gynecologic disorder characterized by the presence of endometrial glands and stroma at extrauterine (ectopic) sites. In women who develop this disease, alterations in specific biological processes involving both the endocrine and immune systems have been observed, which may explain the survival and growth of displaced endometrial tissue in affected women. In the past decade, a considerable amount of research has implicated a role for alterations in progesterone action at both eutopic and ectopic sites of endometrial growth which may contribute to the excessive inflammation associated with progression of endometriosis; however, it remains unclear whether these anomalies induce the condition or are simply a consequence of the disease process. In this article, we summarize current knowledge of alterations within the immune system of endometriosis patients and discuss how endometrial cells from women with this disease not only have the capacity to escape immunosurveillance, but also use inflammatory mechanisms to promote their growth within the peritoneal cavity. Finally, we discuss evidence that exposure to an environmental endocrine disruptor, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, can mediate the development of an endometrial phenotype that exhibits both reduced progesterone responsiveness and hypersensitivity to proinflammatory stimuli mimicking the endometriosis phenotype. Future studies in women with endometriosis should consider whether a heightened inflammatory response within the peritoneal microenvironment contributes to the development and persistence of this disease.

T helper (Th)1, Th2, and Th17 interleukin pathways in infertile patients with minimal/mild endometriosis

In the present study, interleukin (IL)-10, IL-12, IL-17, and IL-23 levels were measured in serum and peritoneal fluid of women with minimal or mild endometriosis and compared with levels in controls without endometriosis. Higher IL-23 levels were encountered in the peritoneal fluid of women with endometriosis, suggesting a possible role of this cytokine in these women's infertility.

New drugs in development for the treatment of endometriosis

Endometriosis is a common and enigmatic disease causing pelvic pain and infertility. Current treatment is mainly based on the use of surgery and ovarian suppressive agents. There is in particular the need for new therapeutic options able to allow a normal menstrual cycle to occur and also consent pregnancy. In the present review, we aimed to give a concise and practical overview in order to allow the clinician to clearly understand the level of development of these drugs. We have presented only treatments supported by in vivo researches with a special attention to studies in humans. Results show appealing new possibilities are emerging from agents counteracting the endometriosis-associated inflammation. Recent data also suggests that there is still the opportunity to refine the use of already available agents.

Effects of anti-TNF-mAb treatment on pregnancy in baboons with induced endometriosis

OBJECTIVE

Hormonal suppressive therapy is not effective for endometriosis-associated subfertility and can even prevent conception. Medical inhibition of TNFalpha, which has been shown to improve conception, is effective in the prevention and treatment of endometriosis in baboons.

DESIGN

Prospective, placebo-controlled fertility trial.

SETTING

Animal research and laboratory facility.

ANIMAL(S)

Sixteen adult female baboons with induced endometriosis.

INTERVENTION(S)

All animals received a single IV dose of the anti-TNFalpha monoclonal antibody c5N (n = 9) or placebo (n = 7) at four different time points. The animals were then exposed to timed mating up to nine completed cycles or until pregnancy was achieved.

MAIN OUTCOME MEASURE(S)

Pregnancy rate (PR), cycle fecundity rate (CFR), time to pregnancy (TTP), and cumulative pregnancy rate (CPR).

RESULT(S)

Inhibition of TNFalpha did not result in a significant improvement in PR (100% c5N vs. 86% placebo), CFR (18% c5N vs. 30% placebo), median TTP (5 cycles c5N vs. 2 cycles placebo), or CPR (100% c5N vs. 80% placebo). The duration of the menstrual cycle was unchanged in both groups before and after the study. Two nonpregnant baboons in the c5N-group died during the study.

CONCLUSION(S)

Medical inhibition of TNFalpha allowed for normal conception but did not improve fecundity in baboons with induced endometriosis when compared with placebo. Larger studies with clinically available TNFalpha blockers in baboons with moderate to severe endometriosis are needed to further test the potential of these agents in the prevention or treatment of endometriosis-associated subfertility.

Interleukin-12 but not interleukin-18 is associated with severe endometriosis

OBJECTIVE

To evaluate interleukin (IL)-12 and IL-18 levels in the serum and peritoneal fluid of women with and without endometriosis.

DESIGN

Cross-sectional survey.

SETTING

University hospital.

PATIENTS

Interleukin-12 and IL-18 levels were compared in 105 patients submitted to laparoscopy because of symptoms suggestive of endometriosis (pain and/or infertility). The disease was confirmed in 72 patients (study group), while in 33 patients findings were not compatible with endometriosis (control group). INTEVENTION(S): Blood sample and peritoneal fluid were obtained from patients during videolaparoscopy.

MAIN OUTCOME MEASURE(S)

The levels of IL-12 and IL-18 in peripheral blood and peritoneal fluid were determined and compared with the stage and site of the disease and histologic classification.

RESULT(S)

IL-12 levels measured in peritoneal fluid were higher in patients with endometriosis compared with the control group. A significant increase in IL-12 levels was found when the more advanced stages of the disease were compared with the initial stages. No statistically significant differences were found in IL-18 levels, either in serum or in peritoneal fluid samples.

CONCLUSION(S)

Patients with severe endometriosis have higher IL-12 levels irrespective of IL-18 levels, suggesting that in this disease an alternative pathway is involved in induction of the Th1 immune response.

Thoracic endometriosis syndrome

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity and is usually confined to the pelvis. Thoracic endometriosis syndrome (TES) is a rare disorder characterized by the presence of functioning endometrial tissue in the pleura, the lung parenchyma and the airways. TES may present with hemoptysis, due to the shedding of endometrial tissue in the bronchial tree, or spontaneous pneumothorax or hemothorax if the endometrial tissue is localized peripherally. Patients are of reproductive age, often nulliparous, with long-standing symptoms. The crucial issue for establishing the diagnosis is the cyclicity of the symptoms which occur along with the menstrual cycle. TES is virtually a diagnosis of exclusion, established on clinical grounds, since neither CT nor endoscopy are specific for TES. Treatment consists of gonadotropin-releasing hormone analogues, aiming to suppress the hypophyseal-gonadal axis, so as to ensure a regression of the endometrial implants. If medical treatment fails, surgical resection of the endometriomas is suggested, although relapse rate may be high.

Multi-disciplinary centres/networks of excellence for endometriosis management and research: a proposal

Centres/networks of excellence are the only way forward to ensure that women with endometriosis receive consistent, evidence-based care, ensuring excellence, continuity of care, multi-disciplinarity, research, training and cost-effectiveness. Clinical excellence should be achieved by proper training, adherence to evidence-based guidelines, quality management and continuous measurement of patient outcome as a central focus. To ensure continuity of care, the first step is to assign to each patient a central gynaecologist who must have continuously updated knowledge regarding all diagnostic and management options for endometriosis and who must set priorities and realistic expectations together with the woman using a long-term multi-disciplinary treatment plan. Scientific research within and scientific collaboration between centres/networks of excellence will create the critical mass of patients and tissue samples that is needed to make progress. Centres/networks of excellence should be accredited as training centres by professional bodies. They should aim at improving the cost-effectiveness of the management of endometriosis by a reduction in the time to diagnosis, a reduction in the time before individualized specialist care is invoked, a reduction of expensive hit-and-miss treatments and a reduction in expensive fertility treatments, if the disease is under control before fertility is impaired.

Uterine stem cells: what is the evidence?

The mucosal lining (endometrium) of the human uterus undergoes cyclical processes of regeneration, differentiation and shedding as part of the menstrual cycle. Endometrial regeneration also follows parturition, almost complete resection and in post-menopausal women taking estrogen replacement therapy. In non-menstruating species, there are cycles of endometrial growth and apoptosis rather than physical shedding. The concept that endometrial stem/progenitor cells are responsible for the remarkable regenerative capacity of endometrium was proposed many years ago. However, attempts to isolate, characterize and locate endometrial stem cells have only been undertaken in the last few years as experimental approaches to identify adult stem/progenitor cells in other tissues have been developed. Adult stem cells are defined by their functional properties rather than by marker expression. Evidence for the existence of adult stem/progenitor cells in human and mouse endometrium is now emerging because functional stem cell assays are being applied to uterine cells and tissues. These fundamental studies on endometrial stem/progenitor cells will provide new insights into the pathophysiology of various gynaecological disorders associated with abnormal endometrial proliferation, including endometrial cancer, endometrial hyperplasia, endometriosis and adenomyosis.

Emerging drugs in endometriosis

Endometriosis is a common, estrogen-dependent, gynaecological disease, defined as the presence of endometrial-like tissue outside the uterus. Although several medications are used for treatment of the disease, they are associated with high recurrence rates, considerable side effects and limited duration of application. Due to these limitations and to the impact of endometriosis on the quality of life of affected women, their environment and the society, there is a great need for new drugs able to abolish endometriosis and its symptoms. Studies in recent years investigating the (patho)physiological mechanisms involved in disease aetiology have fostered the development of novel therapeutic concepts for endometriosis, by targeting the hypothalamic-pituitary-gonadal axis, by selective modulation of estrogenic and progestogenic pathways, by inhibiting angiogenesis or by interfering with inflammatory and immunological factors. This article presents a brief summary of the currently available medications and an overview regarding the development of some of the most interesting and/or most promising novel drug candidates for endometriosis.

Future Directions in Endometriosis Research

Endometriosis is an important gynecological disease, pathologically defined by the ectopic presence of both endometrial glands and stroma, and clinically associated with pelvic pain and infertility. Our current knowledge of the pathogenesis, pathophysiology of related infertility, and spontaneous evolution is still limited, although endometriosis has been described for many years. Future research in endometriosis needs to focus on pathogenesis studies in the baboon model and on the early interactions between endometrial and peritoneal cells in the pelvic cavity at the time of menstruation. Proteomic and genomic approaches are needed to detect potential differences between eutopic endometrium and myometrium in women with and without endometriosis. Immunomodulatory drugs inhibiting endometriosis-associated pelvic inflammation may offer new medical treatment for endometriosis in the future.

FOXO1 and c-jun transcription factors mRNA are modulated in endometriosis

Endometriosis is a polygenic gynaecological condition affecting 5-15% of women of childbearing age. Major symptoms of the disease are pelvic pain and infertility. No clear link has been established between symptoms and the stage of the disease. Although some aspects have begun to be clarified, clinical understanding of endometriosis remains partial at the molecular level. In this perspective, we targeted isolation of differentially expressed genes in the eutopic endometrial tissue. Our assumption was that the endometrial cells of patients presented an unusual gene expression profile, allowing their implantation and survival in an ectopic site, leading to endometriotic lesions. Here, we report that mRNA steady-state levels of two key transcription factors are modulated in endometriosis. FOXO1 (also known as FKHR) levels were 1.6-fold lower in endometriosis compared to the control group at the onset of the secretory phase (day 15-21), while c-jun mRNA was present at higher amounts in endometriosis (1.5-fold) at the proliferative phase of the menstrual cycle. These results were derived from a large sample composed of 157 control subjects and 209 patients with endometriosis. Gene profiling was conducted by real-time quantitative PCR, and data were quality controlled before statistical analysis. Whether protein levels are affected as well remains to be investigated.

Potential involvement of the immune system in the development of endometriosis

This article presents an overview of immunological factors and their role in the development of endometriosis, with emphasis on inflammatory cytokines, growth and adhesion factors. Although retrograde menstruation is a common phenomenon among women of reproductive age, not all women who have retrograde menstruation develop endometriosis. The development of endometriosis is hypothesised to be a complex process, which may be facilitated by several factors, including the quantity and quality of endometrial cells in peritoneal fluid (PF), increased inflammatory activity in PF, increased endometrial-peritoneal adhesion and angiogenesis, reduced immune surveillance and clearance of endometrial cells, and increased production of autoantibodies against endometrial cells. Potential biomarkers like cytokines and autoantibodies upregulated during development of endometriosis may be useful in the development of a non-surgical diagnostic tool. Although endometriosis can be treated using hormonal suppression, there is need for non-hormonal drugs, which can inhibit the development of endometriosis and alleviate pain or infertility without inhibition of ovulation. New molecules that modulate immune function in endometriosis should be the targets for future research.