Endometriosis Patients Show an Increased M2 Response in the Peritoneal CD14+low/CD68+low Macrophage Subpopulation Coupled with an Increase in the T-helper 2 and T-regulatory Cells

A transcriptomic analysis of the interplay of ferroptosis and immune filtration in endometriosis and identification of novel therapeutic targets

Endometriosis is an inflammatory disease, involving immune cell infiltration and production of inflammatory mediators. Ferroptosis has recently been recognized as a mode of controlled cell death and the iron overload and peroxidative environment prevailing in the ectopic endometrium facilitates the occurrence of ferroptosis. In the current investigation, gene expression data was obtained from the dataset GSE7305.The variation in infiltration of immune cells amongst the samples with endometriosis and normal tissue was analysed using the CIBERSORTx tool which revealed higher infiltration of T cells gamma delta, macrophages M2, B cells naïve, T cells CD4 memory resting cells, plasma cells, T cells CD8 and mast cells activated in the tissue samples with endometriosis. An overlap of the differentially expressed genes (DEGs) and ferroptosis related genes revealed 32 ferroptosis related DEGs (FR-DEGs). GO and KEGG pathway analysis showed the FR-DEGs to be enriched in ferroptosis. The PPI network of the FR-DEGs was constructed and TP53, HMOX1, CAV1, CDKN1A, CD44, EPAS1, SLC2A1, MAP3K5, GCLC and FANCD2 were identified as the hub genes. Pearson correlation revealed significant correlation between the hub genes and infiltrating immune cells in endometriosis, thereby suggesting existence of a regulatory crosstalk between immune responses and ferroptosis in endometriosis. Hub gene- miRNA network analysis revealed that 7 of the 10 hub genes were targets of 3 miRNAs -hsa-miR-20a-5p, hsa-miR-16-5p and hsa-miR-17-5p, thereby providing further insight into the regulatory mechanisms underlying disease progression. Predictive analysis and cross validation studies revealed TP53 and CDKN1A as common targets of hsa-miR-16-5p, hsa-miR-17-5p, and hsa-miR-20a-5p, thereby revealing their regulatory roles in ferroptosis and immune modulatory pathways relevant to endometriosis. The present study indicates an important role of both immune dysregulation and ferroptosis in the pathogenesis of endometriosis and identifies ferroptosis related hub genes and their miRNA regulators as favourable novel targets for further studies and therapeutic interventions.

Prospects for potential therapy targeting immune‑associated factors in endometriosis (Review)

Endometriosis (EM) is a chronic inflammatory disease that is one of the most common causes of gynecological systemic lesions in women before menopause. The most representative histological feature of EM is that the endometrium appears outside of the uterine cavity, often in the ovary. Although it is generally accepted that the epithelial and stromal cells of the ectopic endometrium are not malignant, they still have numerous similarities to malignant tumors, including considerable changes to the immune microenvironment (immune monitoring disorder), the creation of a specific hormone environment, high levels of oxidative stress, chronic inflammation and abnormal immune cell regulation. The pathogenesis of EM is not fully understood, which makes it difficult to identify specific biomarkers and potential therapeutic targets for early disease diagnosis and effective treatment. However, considerable progress has been made in this field over the past few decades. The purpose of the present review is to summarize the confirmed and potential biomarkers for EM, and to identify potential therapeutic targets based on changes in immunological factors (including natural killer cells, macrophages, the complement system, miRNA and P‑selectin) in the ectopic endometrial tissue. It is hoped that this work can be used as the basis for identifying accurate diagnostic markers for EM and developing personalized immune‑targeted therapy.

The Estrogen-Immune Interface in Endometriosis

Endometriosis is a gynecologic condition characterized by the growth of endometrium-like stroma and glandular elements outside of the uterine cavity. The involvement of hormonal dysregulation, specifically estrogen, is well established in the initiation, progression, and maintenance of the condition. Evidence also highlights the association between endometriosis and altered immune states. The human endometrium is a highly dynamic tissue that undergoes frequent remodeling in response to hormonal regulation during the menstrual cycle. Similarly, endometriosis shares this propensity, compounded by unclear pathogenic mechanisms, presenting unique challenges in defining its etiology and pathology. Here, we provide a lens to understand the interplay between estrogen and innate and adaptive immune systems throughout the menstrual cycle in the pathogenesis of endometriosis. Estrogen is closely linked to many altered inflammatory and immunomodulatory states, affecting both tissue-resident and circulatory immune cells. This review summarizes estrogenic interactions with specific myeloid and lymphoid cells, highlighting their implications in the progression of endometriosis.

Single-cell RNA sequencing reveals the intercellular crosstalk and the regulatory landscape of stromal cells during the whole life of the mouse ovary

The heterogeneity of ovarian mesenchymal/stromal cells has just been revealed in both mice and humans. However, it remains unclear about the cellular development trace and the intercellular communication network in the whole life of the ovary. In the study, we integrated ours and published single-cell RNA sequencing data from E11.5 (embryonic day 11.5) until M12 (12-month-old) ovaries to show the dynamics of somatic cells along the developmental timeline. The intercellular crosstalk among somatic cell types was depicted with collagen signaling pathway as the most outgoing signals from stromal cells. We identified mesenchymal progenitor cells (CD24+) as the origin of stromal cells. Although their numbers decreased significantly in adults, the cells served as the major signal sender until ovarian senescence. Moreover, the ovarian injury could activate these stem cells and induce stroma remodeling in the aged ovary. Thus, mesenchymal progenitor cells may represent a new strategy to delay ovarian aging in the future.

Targeting delivery of mifepristone to endometrial dysfunctional macrophages for endometriosis therapy

Endometriosis seriously affects 6-10 % of reproductive women globally and poses significant clinical challenges. The process of ectopic endometrial cell colonization shares similarities with cancer, and a dysfunctional immune microenvironment, characterized by non-classically polarized macrophages, plays a critical role in the progression of endometriosis. In this study, a targeted nano delivery system (BSA@Mif NPs) was developed using bovine serum albumin (BSA) as the carrier of mifepristone. The BSA@Mif NPs were utilized to selectively target M2 macrophages highly enriched in ectopic endometrial tissue via the SPARC receptor. This targeting strategy increases drug concentration at ectopic lesions while minimizing its distribution to normal tissue, thereby reducing side effects. In vitro studies demonstrated that BSA@Mif NPs not only enhanced the cellular uptake of M2-type macrophages and ectopic endometrial cells but also improved the cytotoxic effect of mifepristone on ectopic endometrial cells. Furthermore, the BSA@Mif NPs effectively induced immunogenic cell death (ICD) in ectopic endometrial cells and repolarized M2-type macrophages toward the M1 phenotype, resulting in a synergistic inhibition of ectopic endometrial cell growth. In vivo experiments revealed that BSA@Mif NPs exhibited significant therapeutic efficacy in endometriosis-bearing mice by increasing drug accumulation in the endometriotic tissues and modulating the immune microenvironment. This targeted biomimetic delivery strategy presents a promising approach for the development of endometriosis-specific therapies based on existing drugs. STATEMENT OF SIGNIFICANCE: Macrophages play an essential role in immune dysfunctional microenvironment promoting the occurrence and progression of endometriosis and can be a crucial target for developing immune microenvironment regulation strategies for the unmet long-term management of endometriosis. The albumin nanoparticles constructed based on SPARC overexpression in macrophages and endometrial cells and albumin biosafety can achieve the targeted therapy of endometriosis by increasing the passive- and active-mediated drug accumulation in ectopic endometrium and remodeling the immune microenvironment based on macrophage regulation. This study has the following implications: i) overcoming the inherent shortcomings of clinical drugs by nanotechnology is an alternative way of developing medication; ii) developing microenvironment modulation strategies based on macrophage regulation for endometriosis management is feasible.

Targeting TET3 in macrophages provides a concept strategy for the treatment of endometriosis

Endometriosis, characterized by the presence of endometrial-like tissue outside the uterus, is a condition associated with pain and infertility. In this issue of the JCI, Lv et al. illuminate the critical pathophysiological role of the ten-eleven translocation 3 (TET3) in endometriosis. TET3 expression levels were higher in macrophages of endometriotic lesions compared with control endometrial tissue, implicating TET3 as a contributing factor in the chronic inflammation that occurs in endometriosis. TGF-β1 and MCP1 are present in the peritoneal cavity of women with endometriosis, and macrophage exposure to these factors resulted in upregulation of TET3, thereby promoting their survival. Notably, Bobcat339, a selective TET inhibitor, induced apoptosis in these macrophages. Further, myeloid-specific TET3 loss reduced endometriosis in mice. RNA-Seq analysis following TET3 knockdown revealed alterations in cytokine signaling and cell-death pathways, underscoring the therapeutic potential of targeting TET3 in macrophages as a strategy for managing endometriosis.

Soluble Factors CD14, CD163, and Migration Inhibitory Factor Are Associated with Endometriosis-Related Infertility

OBJECTIVES

Myeloid cell-derived factors contribute to the immunopathology of endometriosis. Soluble CD14 (sCD14), CD163 (sCD163), and MIF serve as in vivo markers of myeloid function. However, these soluble molecules are largely unexplored in women with endometriosis-related infertility cases. We investigated three soluble markers, namely sCD14, sCD163, and MIF, in cases of infertility associated with endometriosis and correlated its level to the stage of endometriosis.

DESIGN

Eighty-seven women newly diagnosed with endometriosis or other benign gynecologic control cases linked to infertility were prospectively recruited and underwent diagnostic laparoscopy.

PARTICIPANTS

Forty-four patients with endometriosis were included in this study, comprising 19 patients with early-endometriosis (stages I and II) and 25 late-endometriosis (stages III and IV) based on the revised American Society for Reproductive Medicine (rASRM) classification. The remaining 43 patients constituted a control group with infertility due to other causes.

METHODS

The levels of sCD14, sCD163, and MIF in serum and peritoneal fluid were assessed using ELISA.

RESULTS

Endometriosis women exhibited significantly higher serum levels of sCD163 and MIF levels compared to the control group. Both sCD163 and MIF levels displayed a positive correlation with the rASRM adhesion score. Moreover, the MIF level in serum had a positive correlation with the rASRM endometriosis score. In receiver operating characteristic analysis, serum sCD163 and MIF could significantly discriminate endometriosis and non-endometriosis in infertility cases.

LIMITATIONS

Some limitations of the current study deserve to be underlined. First, the sensitive ELISA method was the sole-validated tool for detecting the markers in patient samples. Second, healthy or fertile women were not involved as the control group.

CONCLUSIONS

The elevated systemic levels of sCD163 and MIF correlated with the severity of endometriosis. These soluble molecules have a potential diagnostic capacity as a non-invasive biomarker. Furthermore, our data warrants future studies on the underlying mechanism of sCD163 and MIF in endometriosis-related infertility.

Identifying Immune Cell Infiltration and Hub Genes Related to M2 Macrophages in Endometriosis by Bioinformatics Analysis

Endometriosis (EM) is a chronic, estrogen-dependent inflammatory disease. Presently, the pathophysiology of EM is still unclear, and numerous studies have established that the immune system plays a major role in the pathophysiology of EM. Six microarray datasets were downloaded from the GEO public database. A total of 151 endometrial samples (72 ectopic endometria and 79 controls) were included in this study. CIBERSORT and ssGSEA were applied to calculate the immune infiltration of EM and control samples. Moreover, we validated four different correlation analyses to explore immune microenvironment of EM and finally identified M2 macrophage-related hub genes and further conducted the specific immunologic signaling pathway analysis by GSEA. The logistic regression model was investigated by ROC and further validated by two external datasets. From the results of the two immune infiltration assays, we concluded that M2 macrophages, regulatory T cells (Tregs), M1 macrophages, activated B cells, T follicular helper cells, activated dendritic cells, and resting NK cells have a significant difference between control and EM tissues. Through multidimensional correlation analysis, we found that macrophages play an important central role in cell-to-cell interactions, especially M2 macrophages. Four immune-related hub genes, namely FN1, CCL2, ESR1, and OCLN, are closely related to M2 macrophages and play a crucial role in the occurrence and immune microenvironment of endometriosis. The combined AUC of ROC prediction model in test and validation sets were 0.9815 and 0.8206, respectively. We conclude that M2 macrophages play a central role in the immune-infiltrating microenvironment of EM.

The Extracellular Vesicle-Macrophage Regulatory Axis: A Novel Pathogenesis for Endometriosis

Endometriosis (EMs) is a common disease among women whose pathogenesis is still unclear, although there are various hypotheses. Recent studies have considered macrophages the key part of the immune system in developing EMs, inducing inflammation, the growth and invasion of the ectopic endometrium, and angiogenesis. Extracellular vesicles (EVs) as novel intercellular vesicle traffic, can be secreted by many kinds of cells, including macrophages. By carrying long non-coding RNA (lncRNA), microRNA (miRNA), or other molecules, EVs can regulate the biological functions of macrophages in an autocrine and paracrine manner, including ectopic lesion growth, immune dysfunction, angiogenesis, and can further accelerate the progression of EMs. In this review, the interactions between macrophages and EVs for the pathogenesis of EMs are summarized. Notably, the regulatory pathways and molecular mechanisms of EVs secreted by macrophages during EMs are reviewed.

Macrophages and small extracellular vesicle mediated-intracellular communication in the peritoneal microenvironment: Impact on endometriosis development

Endometriosis is an inflammatory disease that is defined as the growth of endometrium-like tissue outside the uterus, commonly on the lining of the pelvic cavity, visceral organs and in the ovaries. It affects around 190 million women of reproductive age worldwide and is associated with chronic pelvic pain and infertility, which greatly impairs health-related life quality. The symptoms of the disease are variable, this combined with a lack of diagnostic biomarkers and necessity of surgical visualisation to confirm disease, the prognosis can take an average timespan of 6-8 years. Accurate non-invasive diagnostic tests and the identification of effective therapeutic targets are essential for disease management. To achieve this, one of the priorities is to define the underlying pathophysiological mechanisms that contribute to endometriosis. Recently, immune dysregulation in the peritoneal cavity has been linked to endometriosis progression. Macrophages account for over 50% of immune cells in the peritoneal fluid and are critical for lesion growth, angiogenesis, innervation and immune regulation. Apart from the secretion of soluble factors like cytokines and chemokines, macrophages can communicate with other cells and prime disease microenvironments, such as the tumour microenvironment, via the secretion of small extracellular vesicles (sEVs). The sEV-mediated intracellular communication pathways between macrophages and other cells within the peritoneal microenvironment in endometriosis remain unclear. Here, we give an overview of peritoneal macrophage (pMΦ) phenotypes in endometriosis and discuss the role of sEVs in the intracellular communication within disease microenvironments and the impact they may have on endometriosis progression.

Endometriosis and inflammatory immune responses: Indian experience

Endometriosis is a public health disorder affecting ∼ 247 million women globally and ∼ 42 million women in India. Women with endometriosis suffer from dysmenorrhea, chronic pelvic pain, dyspareunia, dyschezia, fatigue, depression, and infertility leading to significant socioeconomic impact and morbidity. The etiology of endometriosis is not understood well even after 100 years of research. Currently, there is no permanent cure for endometriosis. The inflammatory immune response is one of the important features of etiopathogenesis of endometriosis and therefore understanding the inflammatory immune response would lead to a better understanding of this enigmatic disorder and may also lead to biomarker discovery for diagnosis of endometriosis. We investigated the autoimmune etiology of endometriosis in the Indian population. Using the proteomics approach, anti-endometrial antibodies (AEAs) were detected in Indian women with endometriosis [anti-endometrial antibodies - tropomyosin 3 (TPM3), stomatin-like protein2 (SLP-2), and tropomodulin 3 (TMOD3)]. The studies on AEAs provided a better understanding of autoimmune mechanisms in endometriosis. All three subtypes of endometriosis; superficial peritoneal, ovarian endometrioma, and deep infiltrating endometriosis were reported in Indian women. In this review, we discuss our experiences of the inflammatory immune response, autoimmunity, comorbidities, and clinical phenotypes in women with endometriosis in India.

Niclosamide targets the dynamic progression of macrophages for the resolution of endometriosis in a mouse model

Due to the vital roles of macrophages in the pathogenesis of endometriosis, targeting macrophages could be a promising therapeutic direction. Here, we investigated the efficacy of niclosamide for the resolution of a perturbed microenvironment caused by dysregulated macrophages in a mouse model of endometriosis. Single-cell transcriptomic analysis revealed the heterogeneity of macrophages including three intermediate subtypes with sharing characteristics of traditional “small” or “large” peritoneal macrophages (SPMs and LPMs) in the peritoneal cavity. Endometriosis-like lesions (ELL) enhanced the differentiation of recruited macrophages, promoted the replenishment of resident LPMs, and increased the ablation of embryo-derived LPMs, which were stepwise suppressed by niclosamide. In addition, niclosamide restored intercellular communications between macrophages and B cells. Therefore, niclosamide rescued the perturbed microenvironment in endometriosis through its fine regulations on the dynamic progression of macrophages. Validation of similar macrophage pathogenesis in patients will further promote the clinical usage of niclosamide for endometriosis treatment.

Interleukin-33 Derived from Endometriotic Lesions Promotes Fibrogenesis through Inducing the Production of Profibrotic Cytokines by Regulatory T Cells

In endometriosis, it has been widely believed that the local immunological milieu is Th2-skewed. Regulatory T cells (Tregs) promote fibrogenesis of endometriosis through the transforming growth factor β1 (TGF-β1) and platelet-derived growth factor (PDGF) signaling pathways. We aimed to explore whether Tregs in endometriotic lesions acquire increased production of effector cytokines under the influence of lesion-derived interleukin (IL)-33. We extracted lymphocytes from normal endometrium and ovarian endometrioma to evaluate the expression of IL-4, IL-13, interferon-γ (IFN-γ), TGF-β1, and the IL-33 receptor (ST2) by Tregs from these tissues. Colocalization of IL-33 and FOXP3 in normal endometrium and ovarian endometrioma was evaluated by immunofluorescence. Tregs and endometriotic stromal cells were co-cultured and treated with anti-IL-33 antibody, and the cytokines produced by Tregs were analyzed by flow cytometry and enzyme-linked immunosorbent assay (ELISA). Tregs in ovarian endometrioma produced significant amounts of IL-4, IL-13, TGF-β1, and ST2. Colocalization of IL-33 and FOXP3 was detected in ovarian endometrioma. IL-33 from endometriotic stromal cells caused the differentiation of lesional Tregs into type 2 T helper (Th2)-like cells, along with increased production of TGF-β1 by Tregs. Thus, Tregs and endometriotic lesions engage active crosstalk through IL-33 to promote fibrogenesis in endometriosis, and, as such, this finding opens up new avenues to identify novel therapeutic targets for endometriosis.

A Systematic Review of Atypical Endometriosis-Associated Biomarkers

Ovarian endometriosis may increase the risk of malignancy. Several studies have suggested atypical endometriosis as the direct precursor of endometriosis-associated ovarian cancer. We performed an advanced, systematic search of the online medical databases PubMed and Medline. The search revealed n = 40 studies eligible for inclusion in this systematic review. Of these, n = 39 were finally included. The results from included studies are characterized by high heterogeneity, but some consistency has been found for altered expression in phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway, ARID1a, estrogen and progesterone receptors, transcriptional, nuclear, and growth factors in atypical endometriosis. Although many targets have been proposed as biomarkers for the presence of atypical endometriosis, none of them has such strong evidence to justify their systematic use in clinical practice, and they all need expensive molecular analyses. Further well-designed studies are needed to validate the evidence on available biomarkers and to investigate novel serum markers for atypical endometriosis.

Therapeutic effects of green tea on endometriosis

Endometriosis is a chronic disorder characterized by the presence of endometrial glands and stroma outside the uterine cavity. It affects 8%-10% of women in their reproductive years, and represents a major clinical problem with deleterious social, sexual and reproductive consequences. Current treatment options include pain relief, hormonal intervention and surgical removal. However, these treatments are deemed unsatisfactory owing to varying success, significant side effects and high recurrence rates. Green tea and its major bioactive component, (-)-epigallocatechin gallate (EGCG), possess diverse biological properties, particularly anti-angiogenic, anti-proliferation, anti-metastasis, and apoptosis induction. In recent years, preclinical studies have proposed the use of green tea to inhibit the growth of endometriosis. Herein, the aim of this review is to summarize the potential therapeutic effects of green tea on molecular and cellular mechanism through inflammation, oxidative stress, invasion and adhesion, apoptosis and angiogenesis in endometriosis.

The Role of Peritoneal Macrophages in Endometriosis

Endometriosis is an estrogen-dependent gynecological disorder, defined as the growth of endometrial stromal cells and glands at extrauterine sites. Endometriotic lesions are more frequently located into the abdominal cavity, although they can also be implanted in distant places. Among its etiological factors, the presence of immune dysregulation occupies a prominent place, pointing out the beneficial and harmful outcomes of macrophages in the pathogenesis of this disease. Macrophages are tissue-resident cells that connect innate and adaptive immunity, playing a key role in maintaining local homeostasis in healthy conditions and being critical in the development and sustainment of many inflammatory diseases. Macrophages accumulate in the peritoneal cavity of women with endometriosis, but their ability to clear migrated endometrial fragments seems to be inefficient. Hence, the characteristics of the peritoneal immune system in endometriosis must be further studied to facilitate the search for new diagnostic and therapeutic tools. In this review, we summarize recent relevant advances obtained in both mouse, as the main animal model used to study endometriosis, and human, focusing on peritoneal macrophages obtained from endometriotic patients and healthy donors, under the perspective of its future clinical translation to the role that these cells play on this pathology.

Immunoregulation by type I interferons in the peritoneal cavity

The peritoneal cavity, a fluid-containing potential space surrounding the abdominal and pelvic organs, is home to a rich network of immune cells that maintain tissue homeostasis and provide protection against infection. However, under pathological conditions such as peritonitis, endometriosis, and peritoneal carcinomatosis, the peritoneal immune system can become dysregulated, resulting in nonresolving inflammation and disease progression. An enhanced understanding of the factors that regulate peritoneal immune cells under both homeostatic conditions and in disease contexts is therefore required to identify new treatment strategies for these often life-limiting peritoneal pathologies. Type I interferons (T1IFNs) are a family of cytokines with broad immunoregulatory functions, which provide defense against viruses, bacteria, and cancer. There have been numerous reports of immunoregulation by T1IFNs within the peritoneal cavity, which can contribute to both the resolution or propagation of peritoneal disease states, depending on the specifics of the disease setting and local environment. In this review, we provide an overview of the major immune cell populations that reside in the peritoneal cavity (or infiltrate it under inflammatory conditions) and highlight their contribution to the initiation, progression, or resolution of peritoneal diseases. Additionally, we will discuss the role of T1IFNs in the regulation of peritoneal immune cells, and summarize the results of laboratory studies and clinical trials which have investigated T1IFNs in peritonitis/sepsis, endometriosis, and peritoneal carcinomatosis.

A History of Endometriosis Is Associated With Decreased Peripheral NK Cytotoxicity and Increased Infiltration of Uterine CD68+ Macrophages

Women with endometriosis may have a defective immune system. However, evidence of the immune responses of endometriosis patients with a history of endometriosis surgery is lacking, and the association between the location of endometriosis lesions and immune responses is unclear. This retrospective study included 117 females with reproductive failure and a history of endometriosis and 200 females with reproductive failure but without endometriosis to analyze their endometrial and peripheral immune responses. The results show that endometriosis was associated with decreased peripheral natural killer (NK) cytotoxicity and increased uterine macrophages. Peripheral NK cytotoxicity at effector-to-target ratios of 25:1 and 50:1 was significantly reduced in women with a history of endometriosis from that of the control group (26.6% versus 33.3% and 36.1% versus 43.3%, respectively, both P < 0.001). Furthermore, after further division of patients into three subgroups according to the location of endometriosis lesions, we observed that NK cytotoxicity in the endometriosis subgroups, especially the mixed endometriosis group, was strongly decreased from that of the controls (P = 0.001). The endometrial CD68⁺ macrophage proportion in the mixed endometriosis subgroup was higher than that in the control group (2.8% versus 2.1%, P = 0.043). In addition, the baseline estradiol (E2) level was weakly correlated with the percentage of endometrial macrophages (r = 0.251, P = 0.009), indicating a potential association among the endocrine system, endometrial immune environment, and endometriosis. This study indicated that peripheral NK cytotoxicity and endometrial immune cell profiles could be useful for diagnosing and treating endometriosis and endometriosis-related reproductive diseases.

Bacillus Calmette-Guerin (BCG) vaccination to treat endometriosis

Bacille Calmette-Guérin (BCG), a vaccine intended to protect against tuberculosis disease, can elicit protection against heterologous infections, and even specific types of cancer. In this mini-review, we will address the possible use of BCG as a therapeutic for endometriosis, a syndrome of chronic pelvic pain due to ectopic growth of endometrial-type tissue outside of the uterine lining. These implanted tissues cycle synchronously with menses in pre-menopausal women, generating cellular debris inciting chronic inflammation and tissue scarring leading to pelvic pain and infertility. Further, these lesions may evolve into ovarian clear cell carcinoma. We hypothesize that implantation, survival and transformation of these implants is enabled by a form of immune suppression within the peritoneum, which may be overcome by BCG vaccination.

Identification and Exploration of Novel Macrophage M2-Related Biomarkers and Potential Therapeutic Agents in Endometriosis

Endometriosis (EM) is a chronic neuroinflammatory disorder that is associated with pain and infertility that affects ∼10% of reproductive-age women. The pathophysiology and etiology of EM remain poorly understood, and diagnostic delays are common. Exploration of the underlying molecular mechanism, as well as novel diagnostic biomarkers and therapeutic targets, is urgently needed. Inflammation is known to play a key role in the development of lesions, which are a defining feature of the disorder. In our research, the CIBERSORT and WGCNA algorithms were used to establish a weighted gene co-expression network and to identify macrophage-related hub genes using data downloaded from the GEO database (GSE11691, 7305). The analysis identified 1,157 differentially expressed genes (DEGs) in EM lesions, of which five were identified as being related to M2 macrophages and were validated as differentially expressed by qRT-PCR and immunohistochemistry (IHC). Of these putative novel biomarker genes, bridging integrator 2 (BIN2), chemokine receptor 5 (CCR5), and macrophage mannose receptor 1 (MRC1) were upregulated, while spleen tyrosine kinase (SYK) and metalloproteinase 12 (ADAM12) were downregulated in ectopic endometria vs. normal endometria. Meanwhile, 23 potentially therapeutic small molecules for EM were obtained from the cMAP database, among which topiramate, isoflupredone, adiphenine, dexverapamil, MS-275, and celastrol were the top six molecules with the highest absolute enrichment values. This is our first attempt to use the CIBERSORT and WGCNA algorithms for the identification of novel Mϕ2 macrophage-related biomarkers of EM. Our findings provide novel insights into the impact of immune cells on the etiology of EM; nevertheless, further investigation of these key genes and therapeutic drugs is needed to validate their effects on EM.

Circulating and Endometrial Regulatory T Cell and Related Populations in Endometriosis and Infertility: Endometriosis Is Associated with Blunting of Endometrial Cyclical Effects and Reduced Proportions in Moderate-Severe Disease

Evidence to date supports regulatory T cell (Treg) alterations in endometriosis; however, the relationship remains unclear, and Tregs have not previously been investigated with respect to infertility in endometriosis. This prospective cross-sectional cohort study details circulating and endometrial tissue-specific disturbances in Tregs and broader gated populations in women of reproductive age with and without endometriosis (n = 57 and 29, respectively) using flow cytometry and immunohistochemistry. Participants were characterised by menstrual cycle phase, r-ASRM endometriosis disease stage and fertility status.In the endometrium of women with endometriosis, endometrial Tregs and CD4+ lymphocyte proportions did not change between the proliferative and secretory phases, while in women without the disease, they significantly decreased (p = 0.045 and p = 0.039, respectively). In women with endometriosis, endometrial Tregs were lower than in women without endometriosis overall (p = 0.050 as a proportion of all CD45+ immune cells). We have shown for the first time that proportions of CD4+ lymphocytes (p = 0.021), overall lymphocytes (p = 0.034) and non-granulocytes (p = 0.027) were significantly decreased in the endometrium of women with moderate-severe (r-ASRM stages III and IV) compared to minimal-mild (r-ASRM stages I and II) endometriosis. During the secretory phase, circulating Treg proportions were significantly increased in infertile compared to fertile women (p = 0.049). This study confirms differences in endometrial Tregs in women with endometriosis, with blunting of normal menstrual cyclical variations, reduced proportions during the proliferative phase and disease stage-specific relationships.

The Search for Biomarkers in Endometriosis: a Long and Windy Road

Endometriosis is a complex and chronic estrogen-dependent disease, affecting a significant proportion of women of reproductive age. Despite the long interest and extensive research, the pathogenesis of the disease is still debated. Although available non-invasive diagnostic methods have adequate accuracy, an invasive approach by laparoscopy is often necessary to obtain histological confirmation. In this scenario, the search for an accurate, reliable, cost-effective, clinically applicable non-invasive biomarker plays a crucial role in a potentially early diagnosis and, in this way, shape the future management of the disease. Considering these elements, the current review aims to summarize the most significant and novel results about biomarkers for the diagnosis and follow-up of women affected by endometriosis.

Endometriosis and Cancer: Exploring the Role of Macrophages

Endometriosis and cancer have much in common, notably their burgeoning of cells in hypoxic milieus, their invasiveness, and their capacity to trigger remodeling, vascularization, and innervation of other tissues. An important role in these processes is played by permissive microenvironments inhabited by a variety of stromal and immune cells, including macrophages. Remarkable phenotypical plasticity of macrophages makes them a promising therapeutic target; some key issues are the range of macrophage phenotypes characteristic of a particular pathology and the possible manners of its modulation. In both endometriosis and cancer, macrophages guard the lesions from immune surveillance while promoting pathological cell growth, invasion, and metastasis. This review article focuses on a comparative analysis of macrophage behaviors in endometriosis and cancer. We also highlight recent reports on the experimental modulation of macrophage phenotypes in preclinical models of endometriosis and cancer.

Concentrations of the endocannabinoid N-arachidonoylethanolamine in the follicular fluid of women with endometriosis: the role of M1 polarised macrophages

Although N-arachidonoylethanolamine (AEA; also known as anandamide) is present in human follicular fluid (FF), its regulation remains unknown. Therefore, the aims of the present study were to: (1) investigate the relationships between FF AEA concentrations in women undergoing assisted reproductive technology and their age, body mass index, ART characteristics and fertility treatment outcomes; and (2) assess how different inflammatory patterns may trigger AEA production by human granulosa cells (hGCs). FF AEA concentrations were higher in women undergoing IVF than in those undergoing intracytoplasmic sperm injection group. FF AEA median concentrations were lower in women undergoing ART because of male factor infertility than in women with endometriosis (1.6 vs 2.5nM respectively), but not women with tubal, hormonal or unexplained infertility (1.6, 2.4 and 1.9nM respectively). To evaluate the effects of macrophages on AEA production by hGCs, hGCs were cocultured with monocyte-derived macrophages. The conditioned medium from M1 polarised macrophages increased AEA production by hGCs. This was accompanied by an increase in AEA-metabolising enzymes, particularly N-acyl phosphatidylethanolamine-specific phospholipase D. The results of the present study show that high FF AEA concentrations in patients with endometriosis may be associated with the recruitment of inflammatory chemokines within the ovary, which together may contribute to the decreased reproductive potential of women with endometriosis. Collectively, these findings add a new player to the hormone and cytokine networks that regulate fertility in women.

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.

Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis

Endometriosis is a chronic, inflammatory, hormone-dependent disease characterized by histological lesions produced by the presence of endometrial tissue outside the uterine cavity. Despite the fact that an estimated 176 million women are affected worldwide by this gynecological disorder, risk factors that cause endometriosis have not been properly defined and current treatments are not efficient. Although the interaction between diet and human health has been the focus of many studies, little information about the correlation of foods and their bioactive derivates with endometriosis is available. In this framework, Brassica crops have emerged as potential candidates for ameliorating the chronic inflammatory condition of endometriosis, due to their abundant content of health-promoting compounds such as glucosinolates and their hydrolysis products, isothiocyanates. Several inflammation-related signaling pathways have been included among the known targets of isothiocyanates, but those involving aquaporin water channels have an important role in endometriosis. Therefore, the aim of this review is to highlight the promising effects of the phytochemicals present in Brassica spp. as major candidates for inclusion in a dietary approach aiming to improve the inflammatory condition of women affected with endometriosis. This review points out the potential roles of glucosinolates and isothiocyanates from Brassicas as anti-inflammatory compounds, which might contribute to a reduction in endometriosis symptoms. In view of these promising results, further investigation of the effect of glucosinolates on chronic inflammatory diseases, either as diet coadjuvants or as therapeutic molecules, should be performed. In addition, we highlight the involvement of aquaporins in the maintenance of immune homeostasis. In brief, glucosinolates and the modulation of cellular water by aquaporins could shed light on new approaches to improve the quality of life for women with endometriosis.

Diverse Immunoregulatory Roles of Oxysterols-The Oxidized Cholesterol Metabolites

Intermediates of both cholesterol synthesis and cholesterol metabolism can have diverse roles in the control of cellular processes that go beyond the control of cholesterol homeostasis. For example, oxidized forms of cholesterol, called oxysterols have functions ranging from the control of gene expression, signal transduction and cell migration. This is of particular interest in the context of immunology and immunometabolism where we now know that metabolic processes are key towards shaping the nature of immune responses. Equally, aberrant metabolic processes including altered cholesterol homeostasis contribute to immune dysregulation and dysfunction in pathological situations. This review article brings together our current understanding of how oxysterols affect the control of immune responses in diverse immunological settings.