Increased percentage of Th17 cells in peritoneal fluid is associated with severity of endometriosis

Adoptive transfer of regulatory T cells inhibits the progression of endometriosis-like lesions in regulatory T-cell-depleted mice

STUDY QUESTION

Does the restoration of regulatory T cells (Tregs) suppress the progression of endometriosis?

SUMMARY ANSWER

Adoptive transfer of Tregs suppresses the progression of endometriosis and reduces the levels of helper T (Th)-cell-related and proinflammatory cytokines in mice.

WHAT IS KNOWN ALREADY

Endometriosis is a chronic inflammatory gynecological disease, which involves multiple immune components. Activated Treg counts decrease in the endometrioma and endometrium of patients with endometriosis, and depletion of Tregs exacerbates endometriosis in mice.

STUDY DESIGN, SIZE, DURATION

We evaluated the effects of adoptive transfer of Tregs on the progression of endometriosis in mice. We used Foxp3tm3Ayr/J (Foxp3DTR) mice with temporarily ablated Tregs by injecting diphtheria toxin to develop an endometriosis model, which was generated by ovariectomy, estradiol administration and transplantation of uterine fragments from donor mice. Foxp3DTR mice were randomly divided into Treg adoptive transfer (n = 12) and control (n = 11) groups. Tregs were isolated from lymph nodes and spleens of wild-type (WT) mice and were adoptively transferred into mice that were temporarily Treg-depleted. Control mice were injected with vehicle. Treg adoptive transfer was performed on the day of uterine implantation, and a second adoptive transfer was performed after 14 days. Mice were euthanized 28 days after uterine implantation, and blood, peritoneal fluid, spleen, and endometriosis-like lesion samples were collected.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Foxp3DTR mice were intravenously injected with Tregs isolated from WT mice. The number, total weight, and total volume of the endometriosis-like lesions were evaluated on Day 28 following implantation of uterine fragments. The proportion of Tregs in endometriosis-like lesions, ascites, and peripheral blood was analyzed by flow cytometry. Inflammation in lesions and serum was examined using real-time PCR and ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Injection of Tregs increased their total count and decreased the number (P < 0.0001), weight (P = 0.0021), and volume (P = 0.0010) of endometriosis-like lesions in Foxp3DTR Treg-depleted mice. Furthermore, injection of Tregs decreased the mRNA expression of Th 1-, 2-, and 17-related cytokines, including interferon gamma (P = 0.0101), interleukin (IL)-4 (P = 0.0051), and IL-17 (P = 0.0177), as well as the levels of the proinflammatory cytokine IL-6 (P = 0.0002), in endometriosis-like lesions of Foxp3DTR Treg-depleted mice.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Treg-related immune mechanisms in mice may not precisely reflect those in humans.

WIDER IMPLICATIONS OF THE FINDINGS

Restoration of Tregs may be a useful therapeutic strategy for inhibiting the progression of endometriosis in cases where the decrease in the Treg population is an exacerbating factor.

STUDY FUNDING/COMPETING INTEREST(S)

This study was partially supported by the Grants-in-Aid for Scientific Research (grant numbers 18K16808 and 20K22983) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan. The sponsor had no role in the study design, collection, analysis and interpretation of data, writing of the report, and decision to submit the article for publication. The authors have no conflicts of interest to disclose.

Increased circulating T helper 17 (TH17) cells and endometrial tissue IL-17-producing cells in patients with endometriosis compared with non-endometriotic subjects

Endometriosis, an inflammatory disease, is characterized by the aberrant presence of endometrial tissues at ectopic locations. Accumulating evidence suggests that inflammatory cells, such as interleukin-17 (IL-17)-producing cells, may be involved in the pathogenesis of endometriosis. This investigation assessed the frequency of IL-17A (commonly known as IL-17)-producing cells in peripheral blood mononuclear cells (PBMCs), ectopic, and eutopic endometrial tissues in patients with endometriosis compared to non-endometriotic subjects. PBMCs, ectopic, and eutopic endometrial tissues were collected from 23 patients with endometriosis. PBMCs and endometrial tissues from 20 non-endometriotic women were used as the control group. The frequency of T helper 17 (TH17) lymphocytes in PBMCs was assessed using flow cytometry, and the expression level of IL-17 in eutopic and ectopic endometrial tissues was evaluated through immunohistochemistry. The percentage of TH17 and IL-17-producing lymphocytes was significantly higher in the PBMCs of patients with endometriosis compared to non-endometriotic subjects (P < 0.01 and P < 0.001, respectively). The expression of IL-17 protein in ectopic (P < 0.001) and eutopic (P < 0.05) endometrial tissues of patients with endometriosis increased compared to controls' endometrial tissue. Furthermore, the eutopic endometrium of patients with endometriosis showed a higher expression of IL-17 protein than the eutopic endometrial tissue of control subjects (P < 0.05). The findings suggest that the higher frequency of IL-17-producing cells in the PBMCs and endometrial tissues of patients with endometriosis contributes to the pathogenesis of endometriosis.

SCM-198 Inhibits EMS Development by Reversing Decreased Proportions of IFN-γ+T Cells and CCR5+T Cells

Endometriosis is a common gynecological disease that causes severe pain and infertility. However, the available treatments for EMS are limited. SCM-198, a synthetic form of leonurine, possesses various abilities, including anti-inflammatory, immunomodulatory, antioxidant, anti-fibrotic, and anti-proliferative effects. Previous studies have shown that SCM-198 can inhibit the growth of ectopic lesions, but the specific mechanism remains unknown. The results of our studies indicate that SCM-198 significantly suppresses the endometriotic growth of EMS mice. Enrichment analysis of RNA-seq indicates that SCM-198 is involved in T cell differentiation, activation, cytokine production, stimulation of chemotaxis, and migration. Flow cytometry reveals that SCM-198 reverses the decreased proportions of IFN-γ + T cells and CCR5 + T cells in ectopic lesions. RNA-seq analysis shows that SCM-198 enhances the expression of CCL5 in the ectopic lesions, and western blot is conducted to verify this conclusion both in vivo and in vitro. These findings demonstrate that SCM-198 reverses the decreased proportions of IFN-γ + T cells and CCR5 + T cells, alleviating the growth of mouse ectopic lesions, and the changes in CCR5 + T cells are likely due to the reduced expression of CCL5.

Unveiling the Mechanisms of Pain in Endometriosis: Comprehensive Analysis of Inflammatory Sensitization and Therapeutic Potential

Endometriosis is a complicated, estrogen-dependent gynecological condition with a high morbidity rate. Pain, as the most common clinical symptom of endometriosis, severely affects women's physical and mental health and exacerbates socioeconomic burden. However, the specific mechanisms behind the occurrence of endometriosis-related pain remain unclear. It is currently believed that the occurrence of endometriosis pain is related to various factors, such as immune abnormalities, endocrine disorders, the brain-gut axis, angiogenesis, and mechanical stimulation. These factors induce systemic chronic inflammation, which stimulates the nerves and subsequently alters neural plasticity, leading to nociceptive sensitization and thereby causing chronic pain. In this paper, we compile and review the articles published on the study of nociceptive sensitization and endometriosis pain mechanisms. Starting from the factors influencing the chronic pain associated with endometriosis, we explain the relationship between these factors and chronic inflammation and further elaborate on the potential mechanisms by which chronic inflammation induces nociceptive sensitization. We aim to reveal the possible mechanisms of endometriosis pain, as well as nociceptive sensitization, and offer potential new targets for the treatment of endometriosis pain.

Decreased CCL5 expression in endometrial stromal cells induces deficient CCR5 +CD4 + T cells in endometriosis

Endometriosis (EMS) is a benign gynecological disease characterized by the growth of endometrial tissue outside the uterine cavity. Evidence shows that the survival of patients with ectopic endometrial implants is associated with a dysregulated immune microenvironment. CD4 + T cells can regulate EMS through diverse cytokines, the inflammatory response, and angiogenesis. CCR5 +CD4 + T cells exhibit increased cellular immunogenicity and play a role in infectious diseases, host defense, and cancer progression. However, the specific mechanisms of CCR5 +CD4 + T cells in EMS remain unknown. In the present study, flow cytometry and RNA-seq are utilized to assess the proportions and features of CCR5 +CD4 + T cells in EMS patients, RT-PCR and ELISA are used to assess the production of CCL5 by ectopic endometrial stromal cells (ecESCs). Two EMS models are established through C57B6 wild-type and CCL5 ‒/‒ mice and utilized to explore the in vivo effects of CCR5 +CD4 + T cells on ectopic lesions. Compared with CCR5 ‒CD4 + T cells, CCR5 +CD4 + T cells display a more activated and cytotoxic phenotype. Diminished CCR5 +CD4 + T cells and their impaired ability to produce IFN-γ are observed in the ectopic lesions of EMS patients and in murine EMS models. Impaired production of CCL5 has been detected in human ecESCs. Moreover, endometria stripped from CCL5 ‒/‒ mice are more likely to generate ectopic lesions in the peritoneum of recipient mice. These findings demonstrate that the attenuated recruitment of CCR5 + CD4 + T cells in ectopic lesions caused by decreased production of CCL5 in ecESCs may facilitate the progression of EMS.

Vitamin D and Endometriosis: Is There a Mechanistic Link?

Endometriosis is a prevalent chronic gynaecological disorder, but its cause is still unclear, and both genetic and environmental factors may contribute disease aetiology. Prominent amongst the latter is vitamin D which can be obtained either by the action of sunlight on skin or from dietary sources. Serum levels of the main circulating form of vitamin D, 25-hydroxvitamin D (25(OH)D), have been reported to be inversely correlated with endometriosis, suggesting that vitamin D-deficiency may be a risk factor for the disease. Crucially, the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D) is known to exert many functions beyond its established role in the endocrinology of mineral homoeostasis and prevention of rickets. Several of these extra-skeletal effects of 1,25(OH)2D may impact the risk and progression of endometriosis. The following review details the studies that have assessed associations between vitamin D status/supplementation and endometriosis severity and disease progression, but also describes the mechanistic targets for 1,25(OH)2D in endometriosis with specific reference to immunomodulatory responses and effects on angiogenesis. Endometriosis is an under-reported health issue with poor non-invasive options for diagnosis. Given that vitamin D-deficiency may trigger or exacerbate key pathophysiological responses linked to endometriosis, analysis of vitamin D status in women may provide an alternative risk marker for endometriosis. Treatment options for endometriosis are also limited and the review will also consider whether vitamin D supplementation has a role in the management of endometriosis, either in prevention or treatment.

Diagnostic Potential of Cytokine Biomarkers in Endometriosis: Challenges and Insights

Endometriosis is a common gynecological condition affecting approximately 10% of women of reproductive age, characterized by the abnormal presence of endometrial-like tissue outside the uterus. Although endometriosis was first described over 300 years ago, its underlying mechanisms remain poorly understood, and accurate, prompt diagnosis continues to be challenging. Currently, there is a lack of effective, non-invasive diagnostic methods, and available treatments often come with significant side effects and high recurrence rates. This has spurred interest in investigating the role of pro- and anti-inflammatory molecules, particularly cytokines, in endometriosis, as these molecules play a key role in its progression by influencing cell growth and differentiation. Previous studies suggest that various cytokines could serve as potential biomarkers for diagnosing endometriosis, as they are detectable in both serum and peritoneal fluid. This review provides an overview of the expression, origin, function, and regulation of specific cytokines in endometriosis, along with a brief discussion on their potential clinical implications for diagnosis. Due to the complexity of endometriosis, a panel of multiple biomarkers may ultimately be necessary for accurate diagnosis. It is essential to consider factors such as patient selection, sample collection, and analytical variability when initiating or evaluating biomarker studies.

An update on endometriosis biomarkers

Endometriosis is a debilitating gynecologic disorder characterized by chronic pelvic pain, pelvic adhesions and infertility. The gold standard diagnostic modality is histologically by tissue biopsy, although it can be diagnosed empirically if symptoms improve with medical treatment. A delayed diagnosis of endometriosis often leads to a significant impairment in quality of life and work productivity; hence, significant morbidity has been shown to bear a detrimental impact on society and the economy. The ongoing novel investigation into biomarkers for diagnostic or prognostic evaluation of endometriosis may aid in earlier detection, and thereby, improve patient quality-of-life as well as minimize morbidity. Currently, no single biomarker has been validated for endometriosis; however, there are emerging data on the utility of microRNA for diagnosis and prognosis of disease activity. In this brief review, we will identify and categorize the novel biomarkers for endometriosis.

The Role of NK and T Cells in Endometriosis

Endometriosis, a debilitating condition, affects one in ten women of reproductive age. Its pathophysiology remains unclear, though deficiencies in immune surveillance are thought to create an environment conducive to the evasion of ectopic endometrial cells from the immune system. Our research explores the immunological impact of endometriosis both locally and systemically, emphasizing natural killer (NK) and T cell subpopulations. We incorporated 62 female patients who underwent laparoscopic surgery; of those, 47 had endometriosis, and 15 were controls. We collected peritoneal fluid (PF) and peripheral blood (PB) samples which were tagged with monoclonal antibodies and subsequently scrutinized using flow cytometry. Our findings revealed significant differences in immunological profiles based on demographic factors and symptomatology. In the endometriosis cohort, there was an increase in PB CD56HiCD16dim and PF CD8+ CD56dimCD16Hi NK cells. CD16+ CD4 T cell levels were significantly lower in the PB of endometriosis patients who smoke. Individuals with more severe disease displayed significantly higher levels of PB CD16+ CD8 T cells, which also increased in those with non-menstrual pelvic pain. Dysmenorrhea severity correlated with a progressive increase in PF CD8+ CD56dimCD16Hi NK cells. These variations in specific lymphocyte subsets, namely, within NK and T cells, suggest potential immunological mechanisms in the evolution and clinical presentation of endometriosis.

MCP-1 exerts the inflammatory response via ILK activation during endometriosis pathogenesis

AIMS

MCP-1 has been shown to be elevated in endometriosis. ILK functions in several cellular events and interacts with MCP-1-signaling. In the current study, we evaluated the role of MCP-1-ILK signaling in human endometriotic cell's (Hs832(C).TCs) potential for colonization, invasion, adhesion, etc. and differentiation of macrophage along with inflammation in an endometriosis mouse model.

MATERIALS AND METHODS

A mouse model of endometriosis with elevated levels of MCP-1 was developed by injecting MCP-1. We examined the migration, adhesion, colonization and invasion of Hs832(C).TCs in response to MCP-1-ILK signaling. We also examined the differentiation of THP-1 cells to macrophage in response to MCP-1-ILK signaling.

KEY FINDINGS

We observed that MCP-1 increased Ser246 phosphorylation of ILK in Hs832(C).TCs and enhanced the migration, adhesion, colonization, and invasion of Hs832(C).TCs. In the mouse model of endometriosis, we found elevated chemokines (CCL-11, CCL-22 and CXCL13) levels. An increased level of MCP-1 mediated ILK activation, leading to increased inflammatory reaction and infiltration of residential and circulatory macrophages, and monocyte differentiation, but suppressed the anti-inflammatory reaction. The inhibitor (CPD22) of ILK reversed the MCP-1-mediated action by restoring Hs832(C).TCs and THP-1 phenotype. ILK inhibition in a mouse model of endometriosis reduced the effects of MCP-1 mediated pro-inflammatory cytokines, but increased anti-inflammatory response along with T-regulatory and T-helper cell restoration.

SIGNIFICANCE

Targeting ILK restores MCP-1 milieu in the peritoneal cavity and endometrial tissues, reduces the inflammatory response, improves the T-regulatory and T-helper cells in the endometriosis mouse model and decreases the migration, adhesion, colonization and invasion of endometriotic cells.

The association between genetically predicted systemic inflammatory regulators and endometriosis: A bidirectional Mendelian randomization study

Elevated levels of various cellular inflammatory markers have been observed in patients with endometriosis (EMs). However, a causal relationship between these markers and EMS has not been firmly established. This study aimed to assess the causality between cellular inflammatory markers and the onset of EMS using a bidirectional Mendelian randomization approach. Genetic associations for EMs were derived from the largest and most recent genome-wide association study (GWAS) involving 1937 EMS cases and 245,603 controls of European ancestry. Single nucleotide polymorphisms associated with 41 cellular cytokines and other systemic inflammatory regulators were identified from 8293 Finnish participants. Estimates were obtained using inverse-variance weighted, with sensitivity analyses conducted using MR-Egger, weighted median, and MR-PRESSO. Among the 41 systemic inflammatory regulators included in the analysis, none were associated with the risk of EMs. Elevated levels of IL-6 were associated with an increased risk of EMs (OR = 1.351, 95%CI = 1.015-1.797). Conversely, genetically predicted elevated levels of platelet-derived growth factor (PDGF-BB) were associated with a reduced risk of EMs (OR = 0.856, 95%CI = 0.742-0.987). Genetically predicted elevations in IL-6 may contribute to an increased risk of EMs, while elevated PDGF-BB levels appear protective, suggesting potential therapeutic targets for EMs. Other systemic inflammatory regulators seem unrelated to EMs risk, potentially representing downstream effects or consequences of shared factors between inflammation and EMs.

The Impacts of Inflammatory and Autoimmune Conditions on the Endometrium and Reproductive Outcomes

Background: A healthy pregnancy begins with an adequate endometrial state, even before the arrival of a blastocyst. Proper endometrial priming and the development of a tolerogenic decidua are key steps in creating the perfect environment for implantation and pregnancy. In these processes, the involvement of the maternal immune system seems to be of great relevance, modulating the different decidual immune populations to prepare the endometrium for a potential pregnancy. However, certain local pathologies of an inflammatory and autoimmune nature appear to have a direct impact on these phenomena, thus altering patients' reproductive outcomes. Methods: This literature review analyzes original articles, reviews, systematic reviews, and meta-analyses published between 1990 and 2024, concerning the impact of different inflammatory and autoimmune conditions on endometrial status and fertility. The included papers were obtained from Medline (Pubmed) and the Cochrane library. Results: There is evidence that endometriosis, adenomyosis, and chronic endometritis, through the promotion of a chronic inflammatory environment, are capable of altering endometrial immune populations, and, thus, processes essential for early pregnancy. Among other effects, these conditions have been linked to impaired decidualization, alterations in progesterone responsiveness, and hindered placentation. Similarly, antiphospholipid syndrome (APS), thyroid dysfunction, diabetes, and other pathologies related to glucose and gluten metabolism, due to their autoimmune nature, also appear to have a local impact on the uterine environment, affecting reproductive success through different mechanisms, including altered hormonal response and, again, impaired decidualization. Conclusions: The management of inflammatory and autoimmune diseases in assisted reproduction patients is gaining importance due to their direct impact on the endometrium. It is necessary to follow current expert recommendations and established therapeutic approaches in order to improve patients' prospects, ranging from antibiotic treatment in chronic endometritis to heparin and aspirin in APS, as well as hormonal treatments for endometriosis/adenomyosis or a gluten-free diet in celiac disease. All of them and the rest of the therapeutic perspectives, both current and under investigation, are presented throughout this work, assessing the possible improvements for reproductive outcomes.

Effects of the gut microbiota and its metabolite short-chain fatty acids on endometriosis

In recent years, a growing body of research has confirmed that the gut microbiota plays a major role in the maintenance of human health and disease. A gut microbiota imbalance can lead to the development of many diseases, such as pregnancy complications, adverse pregnancy outcomes, polycystic ovary syndrome, endometriosis, and cancer. Short-chain fatty acids are metabolites of specific intestinal bacteria and are crucial for maintaining intestinal homeostasis and regulating metabolism and immunity. Endometriosis is the result of cell proliferation, escape from immune surveillance, and invasive metastasis. There is a strong correlation between the anti-proliferative and anti-inflammatory effects of short-chain fatty acids produced by gut microbes and the development of endometriosis. Given that the mechanism of action of gut microbiota and Short-chain fatty acids in endometriosis remain unclear, this paper aims to provide a comprehensive review of the complex interactions between intestinal flora, short-chain fatty acids and endometriosis. In addition, we explored potential microbial-based treatment strategies for endometriosis, providing new insights into the future development of diagnostic tests and prevention and treatment methods for endometriosis.

Endometriosis, Pain, and Related Psychological Disorders: Unveiling the Interplay among the Microbiome, Inflammation, and Oxidative Stress as a Common Thread

Endometriosis (EM), a chronic condition in endometrial tissue outside the uterus, affects around 10% of reproductive-age women, significantly affecting fertility. Its prevalence remains elusive due to the surgical confirmation needed for diagnosis. Manifesting with a range of symptoms, including dysmenorrhea, dyschezia, dysuria, dyspareunia, fatigue, and gastrointestinal discomfort, EM significantly impairs quality of life due to severe chronic pelvic pain (CPP). Psychological manifestations, notably depression and anxiety, frequently accompany the physical symptoms, with CPP serving as a key mediator. Pain stems from endometrial lesions, involving oxidative stress, neuroinflammation, angiogenesis, and sensitization processes. Microbial dysbiosis appears to be crucial in the inflammatory mechanisms underlying EM and associated CPP, as well as psychological symptoms. In this scenario, dietary interventions and nutritional supplements could help manage EM symptoms by targeting inflammation, oxidative stress, and the microbiome. Our manuscript starts by delving into the complex relationship between EM pain and psychological comorbidities. It subsequently addresses the emerging roles of the microbiome, inflammation, and oxidative stress as common links among these abovementioned conditions. Furthermore, the review explores how dietary and nutritional interventions may influence the composition and function of the microbiome, reduce inflammation and oxidative stress, alleviate pain, and potentially affect EM-associated psychological disorders.

The role of innate and adaptive immunity in endometriosis

The innate and adaptive immune systems are the two key branches that determine host protection at all mucosal surfaces in human body, including the female reproductive tract. The pattern recognition receptors within the host that recognize pathogen-associated molecular patterns are expressed on the cells of the innate immune system. Rapidly reactive, theinnate immune system, responds immediately to the presence of infectious or other non-self agents, thereby launching an inflammatory response to protect the host until the activation of slower adaptive immune system. Macrophages, dendritic cells, and toll-like receptors are integral components of the innate immune system. In contrast, T-helper (Th1/Th2/Th17) cells and regulatory T (Treg) cells are the primary components of adaptive immune system. Studies showed that the growth and progression of endometriosis continue even in unilateral ovariectomized animal suggesting that besides ovarian steroid hormones, the growth of endometriosis could be regulated by innate/adaptive immune systems in pelvic environment. Recent reports demonstrated a potential role of Th1/Th2/Th17/Treg cells either individually or collectively in the initiation, maintenance, and progression of endometriosis. Herewe review the fundamental knowledge of innate and adaptive immunity and elaborate the role of innate and adaptive immunity in endometriosis based on both human and experimental data.

The Known, the Unknown and the Future of the Pathophysiology of Endometriosis

Endometriosis is one of the most common causes of chronic pelvic pain and infertility, affecting 10% of women of reproductive age. A delay of up to 9 years is estimated between the onset of symptoms and the diagnosis of endometriosis. Endometriosis is currently defined as the presence of endometrial epithelial and stromal cells at ectopic sites; however, advances in research on endometriosis have some authors believing that endometriosis should be re-defined as "a fibrotic condition in which endometrial stroma and epithelium can be identified". There are several theories on the etiology of the disease, but the origin of endometriosis remains unclear. This review addresses the role of microRNAs (miRNAs), which are naturally occurring post-transcriptional regulatory molecules, in endometriotic lesion development, the inflammatory environment within the peritoneal cavity, including the role that cytokines play during the development of the disease, and how animal models have helped in our understanding of the pathology of this enigmatic disease.

The Dysregulated IL-23/TH17 Axis in Endometriosis Pathophysiology

Endometriosis is a chronic inflammatory disease in which endometrial-like tissue grows ectopically, resulting in pelvic pain and infertility. IL-23 is a key contributor in the development and differentiation of TH17 cells, driving TH17 cells toward a pathogenic profile. In a variety of inflammatory and autoimmune disorders, TH17 cells secrete proinflammatory cytokines, including IL-17, contributing to disease pathophysiology. Our studies and others have implicated IL-17 and TH17 cell dysregulation in endometriosis, which is associated with disease severity. In this article, we address whether IL-23-driven TH17 cells contribute to cardinal features of lesion proliferation, vascularization, and inflammation in endometriosis using patient samples, representative cell lines, and our established mouse model of endometriosis. The results indicated dysregulated expression of key genes in the IL-23/TH17 axis in patient ectopic and eutopic endometrial samples and increased IL-23 protein in patient plasma compared with controls. In vitro studies using primary human TH cells determined that rIL-23 mixture treatment increased pathogenic TH17 cell frequency. Similarly, rIL-23 treatment of cell lines (12Z cells, EECCs, HUVECs, and hESCs) representative of the endometriotic lesion microenvironment increased cytokines and growth factors, which play a role in lesion establishment and maintenance. In a syngeneic mouse model of endometriosis, rIL-23 treatment altered numbers of myeloid and T cell subsets in peritoneal fluid and increased giant cells within the lesion. Lesions from rIL-23-treated mice did not reveal significant alterations in proliferation/vascularization, although trends of increased proliferation and vascularization were observed. Collectively, these findings provide insights into the impact of the IL-23/TH17 axis on local immune dysfunction and broadly on endometriosis pathophysiology.

Immune pathway through endometriosis to ovarian cancer

Endometriosis is an estrogen-dependent inflammatory disease, defined by the presence of functional endometrial tissue outside of the uterine cavity. This disease is one of the main gynecological diseases, affecting around 10%-15% women and girls of reproductive age, being a common gynecologic disorder. Although endometriosis is a benign disease, it shares several characteristics with invasive cancer. Studies support that it has been linked with an increased chance of developing endometrial ovarian cancer, representing an earlier stage of neoplastic processes. This is particularly true for women with clear cell carcinoma, low-grade serous carcinoma and endometrioid. However, the carcinogenic pathways between both pathologies remain poorly understood. Current studies suggest a connection between endometriosis and endometriosis-associated ovarian cancers (EAOCs) via pathways associated with oxidative stress, inflammation, and hyperestrogenism. This article aims to review current data on the molecular events linked to the development of EAOCs from endometriosis, specifically focusing on the complex relationship between the immune response to endometriosis and cancer, including the molecular mechanisms and their ramifications. Examining recent developments in immunotherapy and their potential to boost the effectiveness of future treatments.

Vaginal extracellular vesicles impair fertility in endometriosis by favoring Th17/Treg imbalance and inhibiting sperm activity

Extracellular vesicles (EVs) play a key role in various diseases. However, their effect on endometriosis (EMs)-associated infertility is poorly understood. We co-cultured EVs from the female vaginal secretions with human sperm and also generated a mouse model of EMs by allogenic transplant to explore the effect of EVs on fertility. EVs from individuals with EMs-associated infertility (E-EVs) significantly inhibited the total motility (26.46% vs. 47.1%), progressive motility (18.78% vs. 41.06%), linear velocity (21.98 vs. 41.91 µm/s) and the acrosome reaction (AR) rate (5% vs. 22.3%) of human sperm in contrast to the control group (PBS). Furthermore, E-EVs dose-dependently decreased the intracellular Ca2+ ([Ca2+]i), a pivotal regulator of sperm function. Conversely, healthy women (H-EVs) increased human sperm motion parameters, the AR rate, and sperm [Ca2+]i. Importantly, the mouse model of EMs confirmed that E-EVs further decreased the conception rate and the mean number of embryo implantations (7.6 ± 3.06 vs. 4.5 ± 3.21) compared with the control mice by inducing the production of inflammatory cytokines leading to a Th17/Treg imbalance. H-EVs could restore impaired fertility by restoring the Th17/Treg balance. We determined the impact of EVs derived from the female genital tract on human sperm function and studied the possible mechanisms by which it affects fertility. Our findings provide a novel rationale to ameliorate EMs-associated infertility.

Role of the gut microbiota in the pathogenesis of endometriosis: a review

Endometriosis is classically defined as a chronic inflammatory heterogeneous disorder occurring in any part of the body, characterized by estrogen-driven periodic bleeding, proliferation, and fibrosis of ectopic endometrial glands and stroma outside the uterus. Endometriosis can take overwhelmingly serious damage to the structure and function of multi-organ, even impair whole-body systems, resulting in severe dysmenorrhea, chronic pelvic pain, infertility, fatigue and depression in 5-10% women of reproductive age. Precisely because of a huge deficiency of cognition about underlying etiology and complex pathogenesis of the debilitating disease, early diagnosis and treatment modalities with relatively minor side effects become bottlenecks in endometriosis. Thus, endometriosis warrants deeper exploration and expanded investigation in pathogenesis. The gut microbiota plays a significant role in chronic diseases in humans by acting as an important participant and regulator in the metabolism and immunity of the body. Increasingly, studies have shown that the gut microbiota is closely related to inflammation, estrogen metabolism, and immunity resulting in the development and progression of endometriosis. In this review, we discuss the diverse mechanisms of endometriosis closely related to the gut microbiota in order to provide new approaches for deeper exploration and expanded investigation for endometriosis on prevention, early diagnosis and treatment.

Unraveling the microbial puzzle: exploring the intricate role of gut microbiota in endometriosis pathogenesis

Endometriosis (EMs) is a prevalent gynecological disorder characterized by the growth of uterine tissue outside the uterine cavity, causing debilitating symptoms and infertility. Despite its prevalence, the exact mechanisms behind EMs development remain incompletely understood. This article presents a comprehensive overview of the relationship between gut microbiota imbalance and EMs pathogenesis. Recent research indicates that gut microbiota plays a pivotal role in various aspects of EMs, including immune regulation, generation of inflammatory factors, angiopoietin release, hormonal regulation, and endotoxin production. Dysbiosis of gut microbiota can disrupt immune responses, leading to inflammation and impaired immune clearance of endometrial fragments, resulting in the development of endometriotic lesions. The dysregulated microbiota can contribute to the release of lipopolysaccharide (LPS), triggering chronic inflammation and promoting ectopic endometrial adhesion, invasion, and angiogenesis. Furthermore, gut microbiota involvement in estrogen metabolism affects estrogen levels, which are directly related to EMs development. The review also highlights the potential of gut microbiota as a diagnostic tool and therapeutic target for EMs. Interventions such as fecal microbiota transplantation (FMT) and the use of gut microbiota preparations have demonstrated promising effects in reducing EMs symptoms. Despite the progress made, further research is needed to unravel the intricate interactions between gut microbiota and EMs, paving the way for more effective prevention and treatment strategies for this challenging condition.

Differential expression of interleukin-35 receptor distinguishes different subsets of granulocyte-macrophage-colony-stimulating factor-producing T helper cells in a mouse endometriosis model

The immune system contributes to the pathophysiology of endometriosis. The role of ThGM cells, which produce granulocyte macrophage-colony-stimulating factor (GM-CSF), in the pathogenesis of endometriosis remains unknown. To analyze the features of ThGM cells in endometriosis, a mouse endometriosis model was established. ThGM cells in the spleen, peritoneal fluid (PF), and endometriotic lesions (EL) were measured by flow cytometry, based on the expression of surface markers and intracellular proteins. Live ThGM cells were sorted according to chemokine receptor expression profiles and their effects on other CD4+ T cell subsets were determined by co-culture assays. An adoptive transfer assay was performed to characterize the effect of ThGM cells on endometriosis. We found that ThGM cells were present in endometriotic PF and EL. Live EL ThGM cells were enriched in CD4+CXCR3-CCR8-CCR4+CCR10+ T cells. EL ThGM cells differentially express interleukin-35 receptor (IL-35R), consisting of an IL-35R+ subset and an IL-35R- subset. The IL-35R+ subset expressed less GM-CSF, interleukin-2 (IL-2), and tumor necrosis factor-alpha (TNF-α) and proliferated slower than the IL-35R- subset. Meanwhile, the IL-35R+ subset was weaker than the IL-35R- subset in promoting the functions of Th1 and Th17 cells. ThGM cell transfer did not influence EL development but significantly alleviated pro-inflammatory cytokines in PF and ELs. Interleukin-35 (IL-35), the ligand of IL-35R, suppressed ThGM cell function and proliferation in an IL-35R-dependent manner. In summary, ThGM cells in the PF and ELs might exacerbate endometriotic inflammation. IL-35 might suppress the function of ThGM cells via IL-35R.

Diagnostic significance of neutrophil to lymphocyte ratio in endometriosis: a systematic review and meta-analysis

BACKGROUND

The purpose of this systematic review and meta-analysis was to compile existing evidence on the significance of the NLR in predicting endometriosis in order to aid clinical decision-making and outcomes.

METHODS

We searched ProQuest, Web of Science, and PubMed for related studies published before January 2, 2023. Standardized mean difference (SMD) with a 95% confidence interval (CI) was reported for each outcome. Because a significant level of heterogeneity was found, we used the random-effects model to calculate pooled effects. We used Newcastle-Ottawa Scale (NOS) for quality assessment.

RESULTS

Overall, 18 article with were included in the analysis. A random-effect model revealed that patients with endometriosis had elevated levels of NLR compared to healthy controls (SMD = 0.79, 95% CI = 0.33 to 1.25, P < 0.001). Patients with endometriosis had elevated levels of NLR compared to those with other benign tumors (SMD = 0.85, 95% CI = 0.17 to 1.53, P = 0.014). In addition, NLR level of patients with stage III and IV endometriosis was not different from that of patients with stage I and II endometrioma (SMD = 0.30, 95% CI = -0.14 to 0.74, P = 0.18). However, NLR level was not different between endometriosis patients with and without peritoneal lesions (SMD = -0.12, 95% CI = -0.34to 0.10, P = 0.28), between patients with and without endometrioma (SMD = 0.20, 95% CI = -0.15 to 0.55, P = 0.26) and between endometriosis patients with and without deep lesions (SMD = 0.04, 95% CI = -0.20 to 0.28, P = 0.72). The pooled sensitivity of NLR was 0.67 (95% CI = 0.60-0.73), and the pooled specificity was 0.68 (95% CI, 0.62-0.73).

CONCLUSIONS

NLR might be utilized in clinics as a possible predictor to help clinicians diagnose endometriosis in affected women.

MicroRNAs in Endometriosis: Insights into Inflammation and Progesterone Resistance

Endometriosis, a non-malignant gynecological disorder influenced by estrogen, involves the growth of endometrial tissue outside the uterus. Its development includes processes such as inflammation, progesterone resistance, angiogenesis, and cell proliferation. Epigenetic factors, particularly the dysregulation of microRNAs (miRNAs), have emerged as key factors in these mechanisms in endometriosis. This review aims to unveil the intricate molecular processes that control inflammation, progesterone resistance, and miRNA functions in endometriosis. In addition, it provides a comprehensive overview of the current understanding regarding the involvement of miRNAs in the inflammatory aspects of this condition. This synthesis encompasses research investigating the molecular underpinnings of inflammation, along with the biogenesis and roles of miRNAs in endometriosis. Furthermore, it examines human studies and functional analyses to establish the intricate connection between miRNAs, inflammation, and progesterone resistance in the context of endometriosis. The results highlight the significant impact of dysregulated miRNAs on the inflammatory pathways and hormonal imbalances characteristic of endometriosis. Consequently, miRNAs hold promise as potential non-invasive biomarkers and targeted therapeutic agents aimed at addressing inflammation and enhancing the response to progesterone treatment in individuals with endometriosis.

The landscape of non-coding RNAs in the immunopathogenesis of Endometriosis

Endometriosis is a complex disorder that is characterized by the abnormal growth of endometrial-like tissue outside the uterus. It is associated with chronic inflammation, severe pelvic pain, infertility, and significantly reduced quality of life. Although the exact mechanism of endometriosis remains unknown, inflammation and altered immunity are considered key factors in the immunopathogenesis of the disorder. Disturbances of immune responses result in reduced clearance of regurgitated endometrial cells, which elicits oxidative stress and progression of inflammation. Proinflammatory mediators could affect immune cells' recruitment, fate, and function. Reciprocally, the activation of immune cells can promote inflammation. Aberrant expression of non-coding RNA (ncRNA) in patient and animal lesions could be suggestive of their role in endometriosis establishment. The engagement of these RNAs in regulating diverse biological processes, including inflammatory responses and activation of inflammasomes, altered immunity, cell proliferation, migration, invasion, and angiogenesis are widespread and far-reaching. Therefore, ncRNAs can be identified as a determining candidate regulating the inflammatory responses and immune system. This review aims in addition to predict the role of ncRNAs in the immunopathogenesis of endometriosis through regulating inflammation and altered immunity based on previous studies, it presents a comprehensive view of inflammation role in the pathogenesis of endometriosis.

Understanding endometriosis from an immunomicroenvironmental perspective

ABSTRACT

Endometriosis, a heterogeneous, inflammatory, and estrogen-dependent gynecological disease defined by the presence and growth of endometrial tissues outside the lining of the uterus, affects approximately 5-10% of reproductive-age women, causing chronic pelvic pain and reduced fertility. Although the etiology of endometriosis is still elusive, emerging evidence supports the idea that immune dysregulation can promote the survival and growth of retrograde endometrial debris. Peritoneal macrophages and natural killer (NK) cells exhibit deficient cytotoxicity in the endometriotic microenvironment, leading to inefficient eradication of refluxed endometrial fragments. In addition, the imbalance of T-cell subtypes results in aberrant cytokine production and chronic inflammation, which contribute to endometriosis development. Although it remains uncertain whether immune dysregulation represents an initial cause or merely a secondary enhancer of endometriosis, therapies targeting altered immune pathways exhibit satisfactory effects in preventing disease onset and progression. Here, we summarize the phenotypic and functional alterations of immune cells in the endometriotic microenvironment, focusing on their interactions with microbiota and endocrine and nervous systems, and how these interactions contribute to the etiology and symptomology of endometriosis.

The Sphingosine 1-Phosphate Axis: an Emerging Therapeutic Opportunity for Endometriosis

Endometriosis is a common condition in women of reproductive age, but its current interventions are unsatisfactory. Recent research discovered a dysregulation of the sphingosine 1-phosphate (S1P) signaling pathway in endometriosis and showed a positive outcome by targeting it. The S1P axis participates in a series of fundamental pathophysiological processes. This narrative review is trying to expound the reported and putative (due to limited reports in this area for now) interactions between the S1P axis and endometriosis in those pathophysiological processes, to provide some perspectives for future research. In short, S1P signaling pathway is highly activated in the endometriotic lesion. The S1P concentration has a surge in the endometriotic cyst fluid and the peritoneal fluid, with the downstream dysregulation of its receptors. The S1P axis plays an essential role in the migration and activation of the immune cells, fibrosis, angiogenesis, pain-related hyperalgesia, and innervation. S1P receptor (S1PR) modulators showed an impressive therapeutic effect by targeting the different S1P receptors in the endometriosis model, and many other conditions resemble endometriosis. And several of them already got approval for clinical application in many diseases, which means a drug repurposing direction and a rapid clinical translation for endometriosis treatments.

How Do Microorganisms Influence the Development of Endometriosis? Participation of Genital, Intestinal and Oral Microbiota in Metabolic Regulation and Immunopathogenesis of Endometriosis

Microorganisms inhabiting the human body play an extremely key role in its proper functioning, as well as in the development of the immune system, which, by maintaining the immune balance, allows you to enjoy health. Dysbiosis of the intestinal microbiota, or in the oral cavity or reproductive tract, understood as a change in the number and diversity of all microorganisms inhabiting them, may correlate with the development of many diseases, including endometriosis, as researchers have emphasized. Endometriosis is an inflammatory, estrogen-dependent gynecological condition defined by the growth of endometrial cells outside the uterine cavity. Deregulation of immune homeostasis resulting from microbiological disorders may generate chronic inflammation, thus creating an environment conducive to the increased adhesion and angiogenesis involved in the development of endometriosis. In addition, research in recent years has implicated bacterial contamination and immune activation, reduced gastrointestinal function by cytokines, altered estrogen metabolism and signaling, and abnormal progenitor and stem cell homeostasis, in the pathogenesis of endometriosis. The aim of this review was to present the influence of intestinal, oral and genital microbiota dysbiosis in the metabolic regulation and immunopathogenesis of endometriosis.

Peritoneal immune microenvironment of endometriosis: Role and therapeutic perspectives

Endometriosis, an estrogen-dependent chronic inflammatory disease characterized by the growth of endometrium-like tissues outside the uterine cavity, affects 10% of reproductive-age women. Although the pathogenesis of endometriosis is uncertain, it is widely accepted that retrograde menstruation results in ectopic endometrial tissue implantation. Given that not all women with retrograde menstruation develop endometriosis, immune factors have been hypothesized to affect the pathogenesis of endometriosis. In this review, we demonstrate that the peritoneal immune microenvironment, including innate immunity and adaptive immunity, plays a central role in the pathogenesis of endometriosis. Current evidence supports the fact that immune cells, such as macrophages, natural killer (NK) cells, dendritic cells (DCs), neutrophils, T cells, and B cells, as well as cytokines and inflammatory mediators, contribute to the vascularization and fibrogenesis of endometriotic lesions, accelerating the implantation and development of ectopic endometrial lesions. Endocrine system dysfunction influences the immune microenvironment through overexpressed estrogen and progesterone resistance. In light of the limitations of hormonal therapy, we describe the prospects for potential diagnostic biomarkers and nonhormonal therapy based on the regulation of the immune microenvironment. Further studies are warranted to explore the available diagnostic biomarkers and immunological therapeutic strategies for endometriosis.

Non-invasive diagnosis of endometriosis: Immunologic and genetic markers

Endometriosis, a benign gynecologic and chronic inflammatory disease, is defined by the presence of endometrial tissue outside the uterus characterized mainly by pelvic pain and infertility. Because endometriosis affects approximately 10% of females, it represents a significant socioeconomic burden worldwide having tremendous impact on daily quality of life. Accurate and prompt diagnosis is crucial for the management of this debilitating disorder. Unfortunately, diagnosis is typically delayed to lack of specific symptoms and readily accessible biomarkers. Although histopathologic examination remains the current gold standard, this approach is highly invasive and not applicable for early screening. Recent work has focused on the identification of reliable biomarkers including immunologic, ie, immune cells, antibodies and cytokines, as well as genetic and biochemical markers, ie, microRNAs, lncRNAs, circulating and mitochondrial nucleic acids, along with some hormones, glycoproteins and signaling molecules. Confirmatory research studies are, however, needed to more fully establish these markers in the diagnosis, progression and staging of these endometrial lesions.

Myeloid-derived suppressor cells: A new emerging player in endometriosis

Endometriosis is a common gynecological disorder defined by the presence of endometrial tissue outside the uterus. This is commonly associated with chronic pelvic pain, infertility, and dysmenorrhea, which occurs in approximately 10% of women of reproductive age. Although the exact mechanism remains uncertain, it has been widely accepted to be an estrogen-dependent and inflammatory disease. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of immune cells with immunosuppressive capacity and non-immunological functions. They have been found to be aggressively involved in the pathologies of various disorders. In regards to tumors, the functions of MDSCs have been profoundly shown to inhibit tumor immune response and to promote angiogenesis, tumor metastasis, fibrosis, and epithelial-mesenchymal transition (EMT). In recent years, the elevation of MDSCs in endometriosis was reported by several studies that provoke the assumption that MDSCs might exert similar roles to promote the development of endometriosis. Such that, precision treatments targeting MDSCs might be a promising direction for future study. Herein, we will review the research progress of MDSCs in endometriosis and its potential relevance to the pathogenesis, progression, and therapeutics strategy of endometriosis.

Immunogenetic Role of IL17A Polymorphism in the Pathogenesis of Recurrent Miscarriage

Interleukin-17A (IL17A) is a proinflammatory cytokine and is assumed to play an important role in fetal rejection. In order to evaluate the potential role of IL17A polymorphism in the pathogenesis of recurrent miscarriage (RM), serum IL17A levels were estimated by ELISA. Single-nucleotide polymorphism was assessed by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) using gene-specific primers and the EcoNI restriction enzyme. Serum IL17A levels were nonsignificantly (p > 0.5) low in RM patients compared with the control group. IL17A gene amplification by PCR yielded the undigested product of 815 bp, and its digestion with EcoNI enzyme produced 815, 529, 286, and 270 bp fragments for the GG genotype; 529, 286, and 270 bp fragments for the GA genotype; and 529 and 286 bp fragments for the AA genotype. The genotype frequency between the RM and control groups exhibited a significant difference (p = 0.001), whereas no significant difference was observed between allele frequencies in the two groups (p = 0.0954). These data suggest that the IL17A gene polymorphism exhibits no significant effect on IL17A gene expression. However, it significantly decreases and increases RM risk in the homozygous and recessive models, suggesting its potential pregnancy-protecting and -harming roles in the AA and GA + GG genotypes, respectively.

γδ T Lymphocytes as a Double-Edged Sword-State of the Art in Gynecological Diseases

Human gamma-delta (γδ) T cells are a heterogeneous cell population that bridges the gap between innate and acquired immunity. They are involved in a variety of immunological processes, including tumor escape mechanisms. However, by being prolific cytokine producers, these lymphocytes also participate in antitumor cytotoxicity. Which one of the two possibilities takes place depends on the tumor microenvironment (TME) and the subpopulation of γδ T lymphocytes. The aim of this paper is to summarize existing knowledge about the phenotype and dual role of γδ T cells in cancers, including ovarian cancer (OC). OC is the third most common gynecological cancer and the most lethal gynecological malignancy. Anticancer immunity in OC is modulated by the TME, including by immunosuppressive cells, cytokines, and soluble factors. Immune cells are exposed in the TME to many signals that determine their immunophenotype and can manipulate their functions. The significance of γδ T cells in the pathophysiology of OC is enigmatic and remains to be investigated.

Contribution of CD4+ cells in the emotional alterations induced by endometriosis in mice

Endometriosis is a disease defined by the presence of endometrial tissue in extrauterine locations. This chronic condition is frequently associated with pain and emotional disorders and has been related with altered immune function. However, the specific involvement of immune cells in pain and behavioral symptoms of endometriosis has not been yet elucidated. Here, we implement a mouse model of non-surgical endometriosis in which immunocompetent mice develop abdomino-pelvic hypersensitivity, cognitive deficits, anxiety and depressive-like behaviors. This behavioral phenotype correlates with expression of inflammatory markers in the brain, including the immune cell marker CD4. Depletion of CD4 + cells decreases the anxiety-like behavior of mice subjected to the endometriosis model, whereas abdomino-pelvic hypersensitivity, depressive-like behavior and cognitive deficits remain unaltered. The present data reveal the involvement of the immune response characterized by CD4 + white blood cells in the anxiety-like behavior induced by endometriosis in mice. This model, which recapitulates the symptoms of human endometriosis, may be a useful tool to study the immune mechanisms involved in pain and behavioral alterations associated to endometriosis.

Epigenetic regulation and T-cell responses in endometriosis – something other than autoimmunity

Endometriosis is defined as the presence of endometrial-like glands and stroma located outside the uterine cavity. This common, estrogen dependent, inflammatory condition affects up to 15% of reproductive-aged women and is a well-recognized cause of chronic pelvic pain and infertility. Despite the still unknown etiology of endometriosis, much evidence suggests the participation of epigenetic mechanisms in the disease etiopathogenesis. The main rationale is based on the fact that heritable phenotype changes that do not involve alterations in the DNA sequence are common triggers for hormonal, immunological, and inflammatory disorders, which play a key role in the formation of endometriotic foci. Epigenetic mechanisms regulating T-cell responses, including DNA methylation and posttranslational histone modifications, deserve attention because tissue-resident T lymphocytes work in concert with organ structural cells to generate appropriate immune responses and are functionally shaped by organ-specific environmental conditions. Thus, a failure to precisely regulate immune cell transcription may result in compromised immunological integrity of the organ with an increased risk of inflammatory disorders. The coexistence of endometriosis and autoimmunity is a well-known occurrence. Recent research results indicate regulatory T-cell (Treg) alterations in endometriosis, and an increased number of highly active Tregs and macrophages have been found in peritoneal fluid from women with endometriosis. Elimination of the regulatory function of T cells and an imbalance between T helper cells of the Th1 and Th2 types have been reported in the endometria of women with endometriosis-associated infertility. This review aims to present the state of the art in recognition epigenetic reprogramming of T cells as the key factor in the pathophysiology of endometriosis in the context of T-cell-related autoimmunity. The new potential therapeutic approaches based on epigenetic modulation and/or adoptive transfer of T cells will also be outlined.

COVID-19 susceptibility in endometriosis patients: a case control study

PROBLEM

Starting from November 2019, the world has had to face a devastating pandemic caused by SARS-CoV-2. Various studies have identified potential risk factors facilitating the infection, however it hasn't been demonstrated whether endometriosis might represent one of them. The purpose of this study was to evaluate if patients with endometriosis had a higher risk of contracting COVID-19 infection and, in such case, whether they developed a more severe infection than the general population. Furthermore, this study evaluated the possible correlation with the stage of endometriosis, based on the r-ASRM score, and the potential worsening of the disease during the SARS-CoV-2 infection.

METHOD OF STUDY

A case-control study was conducted from March 2020 to April 2021 at Macedonio Melloni Hospital, in Milan. A total of 401 women were recruited. The cases were 201 women with clinical or surgical diagnosis of endometriosis. The control group consisted of 200 women, without the disease. All women completed a self-administered questionnaire which evaluated their demographic and clinical characteristics, as well as a potential diagnosis of Covid-19.

RESULTS

Comparison between the two groups showed that women with endometriosis had a higher frequency of COVID-19 than the control subjects (23% vs 13.5%, P = 0.014), with a greater prevalence of fever (14.4% vs 6%, P = 0.008) and myalgias or arthralgias (11.4% vs 4.5%, P = 0.01). In multivariable logistic regression analyses, women with endometriosis had a higher risk of contracting SARS-CoV-2 infection (OR = 2.11, 95% IC: 1.20-3.80), regardless the stage of the disease.

CONCLUSION

Endometriosis increases the susceptibility to COVID-19, and women who suffer from it should be considered as fragile patients, worthy of prior access to SARS-CoV-2 vaccination campaign. This article is protected by copyright. All rights reserved.

The role of the Immune System in the Development of Endometriosis

Endometriosis is a chronic disease that affects about 10% of women of reproductive age. It can contribute to pelvic pain, infertility or other conditions such as asthma, cardiovascular disease, breast or ovarian cancer. Research has shown that one of the conditions for the development of endometrial lesions is the dysfunction of the immune system. It appears that immune cells, such as neutrophils, macrophages, NK cells and dendritic cells, may play a specific role in the angiogenesis, growth and invasion of endometriosis cells. Immune cells secrete cytokines and defensins that also affect the endometriosis environment. This review discusses the various components of the immune system that are involved in the formation of endometrial lesions in women.

Immunopathogenesis of endometriosis: An overview of the role of innate and adaptive immune cells and their mediators

BACKGROUND

Endometriosis is a chronic inflammatory disease associated with the growth and proliferation of endometrial-like tissues outside the uterus. Although the exact etiology and mechanism of the pathogenesis of the disease have not been fully elucidated, the immune system cells and the mediators produced by them can be named as effective factors in the onset and progression of the disease.

AIMS

We aim to attempt to review studies on the role of the immune system in endometriosis to better understand the pathogenesis of endometriosis.

CONTENT

Abundant production of inflammatory mediators by neutrophils and macrophages and reduced cytotoxicity of defined cells promote endometriosis at the early stages of the disease. Following an increase in the inflammation of the environment, the body takes compensatory mechanisms to reduce inflammation and establish homeostasis. For this purpose, the body produces remodeling and anti-inflammatory factors leading to slow conversion of the inflammatory environment into a non-inflammatory environment with proliferative and immunosuppressive properties. Environmental conditions induce M2 macrophages, TH2 cells, and Tregs differentiation, promoting disease progression by producing angiogenic and immunosuppressive factors. However, the exact molecular mechanism involved in changing inflammatory to non-inflammatory conditions is not yet fully understood.

IMPLICATIONS

Due to the common characteristics of endometriotic cells and cancer cells, most potential treatment options for endometriosis have been suggested due to the results of these methods in the treatment of cancer. In this pathway, immune system cells and soluble mediators can be used as targets.

Effects of endometriosis on immunity and mucosal microbial community dynamics in female olive baboons

Endometriosis is defined as the growth of endometrial tissue in ectopic locations, and is associated with altered immune and microbial phenotypes. It is unclear if these changes are the result of the disease or may be causative. We induced endometriosis in non-human primates (Papio Anubis) to test our hypothesis that the growth of endometriotic lesions results in alterations in immune and microbial dynamics that may advance disease progression. Baboon samples were collected pre-inoculation (prior to disease induction), at 3, 6, 9, and 15 months after disease induction. Tolerant regulatory T-cells (Tregs) and inflammatory T-helper 17 (Th17) cells were identified in peripheral blood and within the eutopic/ectopic endometrial tissues. Microbiome communities were identified in fecal/urine samples. The induction of endometriosis decreased peripheral Tregs cells while Th17 cells increased at all post-induction collections, thus reducing the Tregs:Th17 cells ratio, indicating systemic inflammation. Microbiome diversity and abundance were altered at each sample site after disease induction. Thus, induction of endometriosis in baboons caused an immune shift toward an inflammatory profile and altered mucosal microbial profiles, which may drive inflammation through production of inflammatory mediators. Immune and microbial profiling may lead to innovative diagnostic tools and novel therapies for endometriosis treatment.

Interleukin 17 receptor E identifies heterogeneous T helper 17 cells in peritoneal fluid of moderate and severe endometriosis patients

Endometriosis is a chronic inflammatory disorder resulting in pelvic pain and infertility. The role of T helper 17 (Th17) cells in endometriosis remains elusive. In this study, through detecting CXCR3, CCR4, CCR10, CCR6, interleukin-17 Receptor E (IL-17RE), and CD27, RORγt-and-IL-17A-expressing Th17 cells were distinguished and sorted from peritoneal fluid (PF) of patients with stage III and IV endometriosis. Furthermore, we found that IL-17RE and CD27 were the labels of heterogeneous PF Th17 subsets, i.e. IL-17RE-CD27- subset, IL-17RE+CD27- subset, and IL-17RE+CD27+ subset. The former two subsets expressed higher IL-17A, GM-CSF, and IL-22 and were more proliferative than the latter subset. RNA-Seq analysis on IL-17RE+ Th17 subset and IL-17RE- Th17 subset revealed up-regulation of genes involved in oxidative phosphorylation and electron transport chain in IL-17RE+ Th17 subset relative to IL-17RE- Th17 subset. Consistently, the IL-17RE+ Th17 subset produced more adenosine triphosphate (ATP) and reactive oxygen species (ROS) than IL-17RE- Th17 subset. In conclusion, this study provides a novel method to detect and isolate live PF Th17 cells from endometriosis patients and unveils the functional and metabolic heterogeneity of PF Th17 subsets. Therefore, it sheds light on the elucidation of molecular mechanisms that modulate the function of pathological Th17 cells in endometriosis.

RNA-sequencing identifies differentially expressed genes in T helper 17 cells in peritoneal fluid of patients with endometriosis

Innate and adaptive immune factors play significant roles in the pathophysiology of endometriosis. T helper 17 (Th17) cells, a pro-inflammatory T cell subset, were considered to contribute to the progression of endometriosis lesions. However, the regulatory mechanisms of Th17 cells in endometriosis remain unidentified, partially due to the difficulty in recovering live Th17 cells from endometriosis patients. In this study, by flow cytometry analysis of a set of chemokine receptors including CXCR3, CCR4, CCR10, and CCR6, live RORγt-and-IL-17A-expressing Th17 cells were enriched from peritoneal fluid (PF) of patients with different stages of endometriosis for the first time, RNA-sequencing (RNA-Seq) of these PF Th17 cells revealed significantly up-regulated genes and down-regulated genes in stage I-II and stage III-IV endometriosis, compared with their counterparts in normal PF. In conclusion, this study provides a novel method to isolate live Th17 cells from endometriosis patients, unveils an array of differentially expressed genes in endometriosis Th17 cells, and offers valuable gene expression profile information for endometriosis clinical research.

Altered eutopic endometrial T-regulatory and T-helper 17 lymphocyte ratio in women with unexplained subfertility

PROBLEM

Perturbations in T-helper lymphocyte profiles have previously been associated with endometriosis related subfertility and conception failure. Hence a retrospective in vitro study was conducted to evaluate the relationship between T-regulatory (Treg) and T-helper 17 (Th17) lymphocytes in the eutopic endometrium of women with unexplained subfertility and correlate these profiles to their conception status.

METHOD OF STUDY

Eutopic endometrial biopsies were collected during the mid-secretory phase of the menstrual cycle, from women with unexplained subfertility. These samples were evaluated immunohistochemically for Treg and Th17 lymphocytes as well as the related proinflammatory cytokine, Interleukin-17 (IL-17). These eutopic endometrial T lymphocyte subpopulations were compared to the patients' conception status in subsequent cycles.

RESULTS

Though Treg cells were not indicative of conception success in subsequent cycles, patients who maintained their subfertile (no conception) status were observed to have a higher Th17 cell count in their eutopic endometrium. The ratio of Treg:Th17 cell counts was significantly correlated to patient conception status as well. These trends stayed consistent irrespective of concurrent endometriosis.

CONCLUSION

Patients with a high proinflammatory Th17 lymphocyte profile and low Treg:Th17 ratio in their eutopic endometrium during the secretory phase of their menstrual cycle are more likely to not conceive in subsequent cycles.

Endometriotic Peritoneal Fluid Stimulates Recruitment of CD4+CD25highFOXP3+ Treg Cells

Endometriosis is a common gynecological disorder characterized by the presence of endometrial-like tissue outside the uterus. The disease is associated with disturbed local and systemic immunity. It has been reported that the proportion of CD4⁺CD25^highFOXP3⁺ Treg cells may be significantly increased in the peritoneal fluid of patients with endometriosis. Therefore, the aim of our study was to investigate whether the proportions of Treg cells in the peritoneal cavity of patients with endometriosis are related to the chemotactic and stimulatory activity of the local peritoneal milieu. The peritoneal fluid was collected from 13 women with ovarian endometriosis and 12 control women without the disease. T cell populations were analyzed by flow cytometry, cytokines and chemokines were evaluated using the cytometric bead kit, and cell chemotaxis was studied by cell migration assay. We confirmed that the proportions of Treg cells are increased in the peritoneal fluid of women with endometriosis as compared to the control women. Endometriosis was also associated with elevated concentrations of IL-6, IL-10, and TGF-β1/2 as well as CCL20, CXCL8, CXCL9, and CXCL10. We did not reveal any changes in the proportion of peritoneal Th17 cells and concentrations of IL-17A. Peritoneal Treg cells positively correlated with concentrations of TGF-β, IL-10, and CCL20. Endometriotic peritoneal fluid stimulated chemotaxis of both CD4⁺ and Treg cells. This chemotactic activity positively correlated with concentrations of CCL20. CCL20 stimulated the migration of Treg cells, and the chemotactic activity of the endometriotic peritoneal fluid was inhibited by neutralizing anti-CCL20 antibodies. These results imply that increased proportions of the peritoneal Treg cells in women with endometriosis may result from attraction and activation by local chemokines and cytokines, especially CCL20 and TGF-β. Since Treg cells contribute to the immunopathogenesis of endometriosis, their chemotaxis and activation may be considered as a target for therapeutic intervention.

Peritoneal Fluid from Patients with Ovarian Endometriosis Displays Immunosuppressive Potential and Stimulates Th2 Response

Endometriosis is a common gynaecological disorder characterized by the ectopic growth of endometrial tissue outside the uterine cavity. It is associated with chronic pelvic inflammation and autoimmune reactivity manifesting by autoantibody production and abrogated cellular immune responses. Endometriotic peritoneal fluid contains various infiltrating leucocyte populations and a bulk of proinflammatory and immunoregulatory cytokines. However, the nature and significance of the peritoneal milieu in women with endometriosis still remains obscure. Therefore, the aim of the present study was to investigate the immunoregulatory activity of the peritoneal fluid (PF) from women with endometriosis. The peritoneal fluid samples were collected during laparoscopic surgery from 30 women with and without endometriosis. Immunoregulatory cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ and TNF) and chemokines (CCL2, CCL5, CXCL8 and CXCL9) were evaluated in PF and culture supernatants generated by unstimulated and CD3/CD28/IL-2-stimulated CD4⁺ T cells cultured in the presence of PF. The effect of PF on the generation of Treg and Th17 cells in CD4⁺ T cell cultures, as well as the natural cytotoxic activity of peripheral blood mononuclear cells, was also investigated. Concentrations of IL-6, IL-10, CCL2, CXCL8 and CXCL9 were significantly upregulated in the PF from women with endometriosis when compared to control women, whereas concentrations of other cytokines and chemokines were unaffected. The culturing of unstimulated and CD3/CD28/IL-2-stimulated CD4⁺ T cells in the presence of endometriotic PF resulted in the downregulation of their IL-2, IFN-γ, IL-17A and TNF production as compared to culture medium alone. On the other side, endometriotic PF significantly stimulated the production of IL-4 and IL-10. Endometriotic PF also stimulated the release of CCL2 and CXCL8, whereas the production of CCL5 and CXCL9 was downregulated. Endometriotic PF stimulated the generation of Treg cells and had an inhibitory effect on the generation of Th17 cells in cultures of CD4⁺ T cells. It also inhibited the NK cell cytotoxic activity of the peripheral blood lymphocytes. These results strongly imply that the PF from patients with endometriosis has immunoregulatory/immunosuppressive activity and shifts the Th1/Th2 cytokine balance toward the Th2 response, which may account for deviation of local and systemic immune responses. However, a similar trend, albeit not a statistically significant one, was also observed in case of PF from women without endometriosis, thus suggesting that peritoneal milieu may in general display some immunoregulatory/immunosuppressive properties. It should be stressed, however, that our present observations were made on a relatively small number of PF samples and further studies are needed to reveal possible mechanism(s) responsible for this phenomenon.

Interleukin-9 produced by helper T cells stimulates interleukin-8 expression in endometriosis

PROBLEM

Inflammation and immune responses play crucial roles in the development of endometriosis. Although interleukin-9 (IL-9) has a pro-inflammatory function in chronic inflammatory diseases, its function in endometriosis remains unknown. Here, we aimed to investigate the significance of IL-9 and IL-9-producing lymphocytes in endometriosis.

METHOD OF STUDY

Specimens were obtained from patients with and without endometriosis. Peritoneal fluid (PF), peripheral blood (PB), and ovarian endometrioma (OE) tissues were analyzed for the proportion of CD4⁺ IL-9⁺ lymphocytes and IL-9 concentration using flow cytometry and enzyme-linked immunosorbent assay. OE, endometrium with endometriosis (EE), and normal endometrium (NE) were analyzed for IL-9 receptor (IL-9R) expression using immunohistochemical staining. IL-9-dependent changes in Interleukin-8 (IL-8) expression in endometrial stromal cells from OE (OESCs) were evaluated using real-time PCR.

RESULTS

The proportion of CD4⁺ IL-9⁺ lymphocytes was higher in the PF, but not the PB, of patients with endometriosis than individuals without endometriosis (p < .05). However, IL-9 levels in the PF did not differ between those with and without endometriosis. We detected CD4+ IL-9+ lymphocytes in OE tissues and IL-9R in OE tissues and OESCs. In OESC culture, IL-9 significantly elevated IL-8 expression in a dose-dependent manner (p < .05), which was nullified by the addition of the anti-IL-9 receptor antibody. Furthermore, IL-9 additively stimulated IL-8 expression in the presence of TNF-α (p < .05).

CONCLUSION

Our findings show that IL-9 produced by helper T cells induces IL-8 expression, suggesting that IL-9 plays an important role in the development of endometriosis by stimulating IL-8 expression.

Protein arginine methyltransferase 5 mediates THP-1-derived macrophage activation dependent on NF-κB in endometriosis

Macrophage-induced inflammation is a major factor in the pathogenesis of endometriosis. The underlying mechanisms, however, remain largely unknown. TNF-α, IL-6, IL-10 and C-C motif chemokine 20 (CCL20) levels in endometrial extracts were determined using Luminex cytokine kits. Additionally, protein arginine methyltransferase 5 (PRMT5) levels were measured using reverse transcription-quantitative PCR and western blotting. IL-6 and IP-10 levels in cells were measured using ELISA kits. In the present study, it was revealed that PRMT5 expression at both the mRNA and protein levels in THP-1-derived macrophages was significantly decreased following treatment with serum or extracts of endometrium from patients with endometriosis in the presence of lipopolysaccharide, compared with that in control cells, suggesting a possible role for macrophage-derived PRMT5 in mediating the interaction between macrophages and endometrium in endometriosis. Mechanistically, macrophage PRMT5 expression was regulated in an NF-κB-dependent and Smad2/3-independent manner, indicating that PRMT5 is a downstream target of NF-κB. Importantly, macrophage-derived PRMT5 was required for macrophage activation in endometriosis, as evidenced by the PRMT5-dependent secretion of IL-6 and IFN-γ-induced protein 10 from THP-1-derived macrophages. The present study identified NF-κB-dependent PRMT5 as a novel regulator of macrophage activation in endometriosis. Targeting PRMT5 in macrophages may be a potential therapeutic strategy against endometriosis.

Intricate Connections between the Microbiota and Endometriosis

Imbalances in gut and reproductive tract microbiota composition, known as dysbiosis, disrupt normal immune function, leading to the elevation of proinflammatory cytokines, compromised immunosurveillance and altered immune cell profiles, all of which may contribute to the pathogenesis of endometriosis. Over time, this immune dysregulation can progress into a chronic state of inflammation, creating an environment conducive to increased adhesion and angiogenesis, which may drive the vicious cycle of endometriosis onset and progression. Recent studies have demonstrated both the ability of endometriosis to induce microbiota changes, and the ability of antibiotics to treat endometriosis. Endometriotic microbiotas have been consistently associated with diminished Lactobacillus dominance, as well as the elevated abundance of bacterial vaginosis-related bacteria and other opportunistic pathogens. Possible explanations for the implications of dysbiosis in endometriosis include the Bacterial Contamination Theory and immune activation, cytokine-impaired gut function, altered estrogen metabolism and signaling, and aberrant progenitor and stem-cell homeostasis. Although preliminary, antibiotic and probiotic treatments have demonstrated efficacy in treating endometriosis, and female reproductive tract (FRT) microbiota sampling has successfully predicted disease risk and stage. Future research should aim to characterize the "core" upper FRT microbiota and elucidate mechanisms behind the relationship between the microbiota and endometriosis.

Platelets and Regulatory T Cells May Induce a Type 2 Immunity That Is Conducive to the Progression and Fibrogenesis of Endometriosis

Endometriosis is a hormonal disease, as well as a chronic inflammatory disease. While various immune cells are documented to be involved in endometriosis, there is a wanton lack of a bigger picture on how these cells are coordinated to work concertedly. Since endometriotic lesions experience cyclical bleeding, they are fundamentally wounds that undergo repeated tissue injury and repair (ReTIAR). In this study, we attempted to characterize the role of platelets and regulatory T cells (Tregs) in modulating the lesional immune microenvironment and its subsequent effects on lesional progression and fibrogenesis. Through two mouse experiments, we show that, by disrupting predominantly a type 2 immune response in lesional microenvironment, both platelets and Tregs depletion decelerated lesional progression and fibrogenesis, likely through the suppression of the TGF-β1/Smad3 and PDGFR-β/PI3K/Akt signaling pathways. In particular, platelet depletion resulted in significantly reduced lesional expression of thymic stromal lymphopoietin (TSLP), leading to reduced aggregation of macrophages and alternatively activated (M2) macrophages, and of Tregs, T helper 2 (Th2) and Th17 cells but increased aggregation of Th1 cells, in lesions, which, in turn, yields retarded fibrogenesis. Similarly, Tregs depletion resulted in suppression of platelet aggregation, and reduced aggregation of M2 macrophages, Th2 and Th17 cells but increased aggregation of Th1 cells, in lesions. Thus, both platelet and Tregs depletion decelerated lesional progression and fibrogenesis by disrupting predominantly a type 2 immunity in lesional microenvironment. Taken together, this suggests that both platelets and Tregs may induce a type 2 immunity in lesional microenvironment that is conducive to lesional progression and fibrogenesis.

Alteration of systemic and uterine endometrial immune populations in patients with endometriosis

PROBLEM

Endometriosis is defined as growth of endometrial tissue in ectopic locations; it is associated with infertility and chronic pain and affects ~12% of reproductive-aged women. Although inflammation is known to play a key role in endometriosis, knowledge related to immune phenotypes associated with this disease is lacking. This study aimed to characterize immune profiles in patients with endometriosis, to assess inflammatory mediators, to and determine if surgical and/or hormonal therapies restore immune homeostasis.

METHODS OF STUDY

Samples from nine controls and 20 histologically confirmed endometriosis patients were collected upon surgery and ~1-3 weeks post-surgical intervention. Subjects were either not utilizing hormonal suppression or were currently on monophasic hormonal therapy. Tolerant regulatory T cells (Tregs = natural [nTregs] +inducible [iTregs]) and inflammatory T helper 17 (Th17) cells were identified in peripheral blood via flow cytometry and within the eutopic/ectopic endometrial tissues via immunohistochemistry and real-time-qPCR. Cytokines were assessed via 10-plex-ELISA.

RESULTS

Patients with endometriosis not utilizing hormonal therapy exhibited lower iTregs (tolerant), greater Th17 (inflammatory), and a reduction in Treg/Th17 ratio (P < .05), indicative of systemic inflammation. Treg and Th17 localizations were enhanced within the ectopic endometrial implant, which promotes lesion development. Hormonal therapy decreased systemic and local inflammation (eutopic/ectopic endometrium) via decreased iTregs and Th17 cells in patients with endometriosis (P < .05). Thus, imbalance within immune populations correlated with increased inflammation in patients with endometriosis, which was mitigated by hormonal therapy.

CONCLUSIONS

Patients with endometriosis exhibited systemic and localized inflammation within ectopic and endometrial tissues. Hormonal therapy dampened inflammation caused by disease.

Immunological changes associated with adenomyosis: a systematic review

BACKGROUND

Adenomyosis is a benign gynecological disorder associated with subfertility, pelvic pain and abnormal uterine bleeding that have significant consequences for the health and quality of life of women. Histologically, it is defined as the presence of ectopic endometrial islets within the myometrium. Its pathogenesis has not yet been elucidated and several pieces of the puzzle are still missing. One process involved in the development of adenomyosis is the increased capacity of some endometrial cells to infiltrate the myometrium. Moreover, the local and systemic immune systems are associated with the onset of the disease and with maintaining it. Numerous observations have highlighted the activation of immune cells and the release of immune soluble factors in adenomyosis. The contribution of immunity occurs in conjunction with hormonal aberrations and activation of the epithelial to mesenchymal transition (EMT) pathway, which promotes migration of endometrial cells. Here, we review current knowledge on the immunological changes in adenomyosis, with the aim of further elucidation of the pathogenesis of this disease.

OBJECTIVE AND RATIONALE

The objective was to systematically review the literature regarding the role of the immune system in development of adenomyosis in the inner and the outer myometrium, in humans.

SEARCH METHODS

A systematic review of published human studies was performed in MEDLINE, EMBASE and Cochrane Library databases from 1970 to February 2019 using the combination of Medical Subject Headings (MeSH): Adenomyosis AND ('Immune System' OR 'Gonadal Steroid Hormones'), and free-text terms for the following search terms (and their variants): Adenomyosis AND (immunity OR immune OR macrophage OR 'natural killer cell' OR lymphocyte* OR leucocyte* OR HLA OR inflammation OR 'sex steroid' OR 'epithelial to mesenchymal transition' OR 'EMT'). Studies in which no comparison was made with control patients, without adenomyosis (systemic sample and/or eutopic endometrium), were excluded.

OUTCOMES

A total of 42 articles were included in our systematic review. Changes in innate and adaptive immune cell numbers were described in the eutopic and/or ectopic endometrium of women with adenomyosis compared to disease-free counterparts. They mostly described an increase in lymphocyte and macrophage cell populations in adenomyosis eutopic endometrium compared to controls. These observations underscore the immune contributions to the disease pathogenesis. Thirty-one cytokines and other markers involved in immune pathways were studied in the included articles. Pro-inflammatory cytokines (interleukin (IL) 6, IL1β, interferon (IFN) α, tumor necrosis factor α, IFNγ) as well as anti-inflammatory or regulatory mediators (IL10, transforming growth factor β…) were found to be elevated in the eutopic endometrium and/or in the ectopic endometrium of the myometrium in women with adenomyosis compared to controls. Moreover, in women affected by adenomyosis, immunity was reported to be directly or indirectly linked to sex steroid hormone aberrations (notably changes in progesterone receptor in eutopic and ectopic endometrium) in three studies and to EMT in four studies.

WIDER IMPLICATIONS

The available literature clearly depicts immunological changes that are associated with adenomyosis. Both systemic and local immune changes have been described in women affected by adenomyosis, with the coexistence of changes in inflammatory as well as anti-inflammatory signals. It is likely that these immune changes, through an EMT mechanism, stimulate the migration of endometrial cells into the myometrium that, together with an endocrine imbalance, promote this inflammatory process. In light of the considerable impact of adenomyosis on women's health, a better understanding of the role played by the immune system in adenomyosis is likely to yield new research opportunities to better understand its pathogenesis.