Cell subtypes and immune dysfunction in peritoneal fluid of endometriosis revealed by single-cell RNA-sequencing

Stress, pain, anxiety, and depression in endometriosis-Targeting glial activation and inflammation

Endometriosis (EM) is a gynecological inflammatory disease often accompanied by stress, chronic pelvic pain (CPP), anxiety, and depression, leading to a diminished quality of life. This review aims to discuss the relationship between systemic and local inflammatory responses in the central nervous system (CNS), focusing on glial dysfunctions (astrocytes and microglia) as in critical brain regions involved in emotion, cognition, pain processing, anxiety, and depression. The review presents that EM is connected to increased levels of pro-inflammatory cytokines in the circulation. Additionally, chronic stress and CPP as stressors may contribute to the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, depleting the production of inflammatory mediators in the circulatory system and the brain. The systemic cytokines cause blood-brain barrier (BBB) breakdown, activate microglia in the brain, and lead to neuroinflammation. Furthermore, CPP may induce neuronal morphological alterations in critical regions through central sensitization and the activation of glial cells. The activation of glial cells, particularly the polarization of microglia, leads to the activation of the NLRP3 inflammasome and the overproduction of inflammatory cytokines. These inflammatory cytokines interact with the signaling pathways involved in neural plasticity. Additionally, persistent inflammatory conditions in the brain lead to neuronal death, which is correlated with a reduced volume of key brain regions such as the hippocampus. This review highlights the involvement of glial cells in the pathogenesis of the mental comorbidities of EM (i.e., pain, anxiety, and depression) and to discuss potential therapeutic approaches for targeting the inflammation and activation of microglia in key brain regions.

The pathogenesis of endometriosis and adenomyosis: insights from single-cell RNA sequencing†

Endometriosis and adenomyosis are two similar gynecological diseases that are characterized by ectopic implantation and the growth of the endometrial tissue. Previous studies have reported that they share a common pathophysiology in some respects, such as a similar cellular composition and resistance to the progestogen of lesions, but their underlying mechanisms remain elusive. Emerging single-cell ribonucleic acid sequencing (scRNA-seq) technologies allow for the dissection of single-cell transcriptome mapping to reveal the etiology of diseases at the level of the individual cell. In this review, we summarized the published findings in research on scRNA-seq regarding the cellular components and molecular profiles of diverse lesions. They show that epithelial cell clusters may be the vital progenitors of endometriosis and adenomyosis. Subclusters of stromal cells, such as endometrial mesenchymal stem cells and fibroblasts, are also involved in the occurrence of endometriosis and adenomyosis, respectively. Moreover, CD8+ T cells, natural killer cells, and macrophages exhibit a deficiency in clearing the ectopic endometrial cells in the immune microenvironment of endometriosis. It seems that the immune responses are activated in adenomyosis. Understanding the immune characteristics of adenomyosis still needs further exploration. Finally, we discuss the application of findings from scRNA-seq for clinical diagnosis and treatment. This review provides fresh insights into the pathogenesis of endometriosis and adenomyosis as well as the therapeutic targets at the cellular level.

Omics-based novel strategies in the diagnosis of endometriosis

Endometriosis, an enigmatic and chronic disorder, is considered a debilitating condition despite being benign. Globally, this gynecologic disorder affects up to 10% of females of reproductive age, impacting almost 190 million individuals. A variety of genetic and environmental factors are involved in endometriosis development, hence the pathophysiology and etiology of endometriosis remain unclear. The uncertainty of the etiology of the disease and its complexity along with nonspecific symptoms have led to misdiagnosis or lack of diagnosis of affected people. Biopsy and laparoscopy are referred to as the gold standard for endometriosis diagnosis. However, the invasiveness of the procedure, the unnecessary operation in disease-free women, and the dependence of the reliability of diagnosis on experience in this area are considered the most significant limitations. Therefore, continuous studies have attempted to offer a noninvasive and reliable approach. The recent advances in modern technologies have led to the generation of large-scale biological data sets, known as -omics data, resulting in the proceeding of the -omics century in biomedical sciences. Thereby, the present study critically reviews novel and noninvasive biomarkers that are based on -omics approaches from 2020 onward. The findings reveal that biomarkers identified based on genomics, epigenomics, transcriptomics, proteomics, and metabolomics are potentially able to diagnose endometriosis, predict prognosis, and stage patients, and potentially, in the near future, a multi-panel of these biomarkers will generate clinical benefits.

Association between periodontitis and endometriosis: a bidirectional Mendelian randomization study

Introduction

A potential association between periodontitis and endometriosis has been indicated in previous observational studies. Nevertheless, the causal link between these two disorders has not been clarified.

Methods

Based on publicly available genome-wide association study (GWAS) summary datasets, we conducted a bidirectional Mendelian randomization (MR) study to investigate the relationship between periodontitis and endometriosis and its subtypes. Single nucleotide polymorphisms (SNPs) strongly associated with candidate exposures at the genome-wide significance level (P < 5 × 10-8) were selected as instrumental variables (IVs). The inverse variance-weighted regression (IVW) was performed to estimate the causal effect of periodontitis on endometriosis. We further conducted two sensitivity analyses, MR-Egger and weighted median, to test the validity of our findings. The main results were replicated via data from the UK Biobank. Finally, a reverse MR analysis was performed to evaluate the possibility of reverse causality.

Results

The IVW method suggested that periodontitis was positively associated with endometriosis of the pelvic peritoneum (OR = 1.079, 95% CI = 1.016 to 1.146, P = 0.014). No causal association was indicated between periodontitis and other subtypes of endometriosis. In reversed analyses, no causal association between endometriosis or its subtypes and periodontitis was found.

Conclusions

Our study provided genetic evidence on the causal relationship between periodontitis and endometriosis of the pelvic peritoneum. More studies are necessary to explore the underlying mechanisms.

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.

Recruitment of large peritoneal macrophages to capsular fibrosis developed on the liver surface

Upon injury to Glisson's capsule, mesothelial cells covering the liver surface differentiate into myofibroblasts and participate in capsular fibrosis. In the fibrotic area, infiltrating macrophages are present, but their origin and role in capsular fibrosis remain elusive. In the present study, we examined whether macrophages in the peritoneal cavity migrate to the liver and participate in capsular fibrosis. Capsular fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate. Chlorhexidine gluconate treatment induced disappearance of CD11bHigh F4/80High large peritoneal macrophages from the peritoneal cavity. Transplantation of TIMD4+ large peritoneal macrophages to the mouse peritoneal cavity resulted in their recruitment to the fibrotic area of the liver. Bone marrow-derived monocytes were also recruited to the chlorhexidine gluconate-induced fibrotic area upon their transplantation to the peritoneal cavity. However, bone marrow-derived macrophages, Kupffer cells, peritoneal B cells, and small peritoneal macrophages prepared from chlorhexidine gluconate-treated mice did not exhibit such potential. In the hepatic fibrotic area, peritoneal macrophages lost expression of unique markers (Gata6, Timd4) and increased expression of genes involved in inflammation (Il1b, Il6, Tnf) and extracellular matrix remodeling (Mmp13, Timp1). Depletion of peritoneal macrophages by clodronate liposomes reduced capsular fibrosis. Our data indicate that large peritoneal macrophages are recruited to the injured liver surface and promote capsular fibrosis by inducing inflammation and extracellular matrix remodeling. Modulating the function of peritoneal macrophages might be a new approach for suppressing capsular fibrosis.

Identification of central genes for endometriosis through integration of single-cell RNA sequencing and bulk RNA sequencing analysis

This study aimed to identify the key genes involved in the development of endometriosis and construct an accurate predictive model to provide new directions for the diagnosis and treatment of endometriosis. Using bioinformatics analysis, we employed the single-cell cell communication method to identify the key cell subtypes. By combining chip data and integrating differential analysis, WGCNA analysis, and the least absolute shrinkage and selection operator (LASSO) model, key genes were identified for immune infiltration and functional enrichment analyses. Cell communication analysis identified tissue stem cells as the key subtype. Differential analysis revealed 1879 differentially expressed genes, whereas WGCNA identified 357 module genes. The LASSO model further selects 4 key genes: Adipocyte Enhancer Binding Protein 1(AEBP1), MBNL1, GREM1, and DES. All 4 key genes showed significant correlations with immune cell content. Moreover, these genes were significantly expressed in single cells. The predictive model demonstrated good diagnostic performance. Through scRNA-seq, WGCNA, and LASSO methodologies, DES, GREM1, MBNL1, and AEBP1 emerged as crucial core genes linked to tissue stem cell markers in endometriosis. These genes have promising applications as diagnostic markers and therapeutic targets for endometriosis.

The deviations of CD4 + T cells during peripheral blood and peritoneal fluid of endometriosis: a systematic review and meta-analysis

OBJECTIVE

To assess whether endometriosis (EMs) was related to systematic and/or local deviations of cluster of differentiation (CD)4 + T cells.

METHODS

Until November 2022, we enrolled a total of 1363 EMs and 1564 healthy women from 32 studies who met the inclusion criteria.

RESULTS

After systematically retrieving the literature, we identified 1086 citations and 32 case-control studies were enrolled. Cumulative results suggested that there were insignificant deviations of CD4 + T cells during peripheral blood (PB) between EMs and healthy women (RR: - 0.83, I2 = 99%, p = 0.65), also no statistically significant difference was found between mild and severe EMs (RR: 3.19, I2 = 94%, p = 0.19). We also found insignificant deviations of CD4 + /CD8 + during PB between EMs and healthy women (RR: 0.09, I2 = 99%, p = 0.39), and between mild and severe EMs (RR: - 0.16, I2 = 99%, p = 0.29). The results might suggest that there was no significant correlation between EMs and systematic deviations of CD4 + T cells. When it came to local deviation during peritoneal fluid (PF), the polled results suggested that the frequency of CD4 + T cells during EMs was significantly lower than healthy women (RR: - 5.38, I2 = 93%, p = 0.01), and the ratio of CD4 + /CD8 + during EMs was significantly lower than healthy women (RR: - 0.13, I2 = 0%, p < 0.0001). However, there were insignificant deviations of CD4 + during PF between mild and severe EMs (RR: 1.65, I2 = 53%, p = 0.15), also there was an insignificant difference of CD4 + /CD8 + between mild and severe EMs (RR: - 0.09, I2 = 14%, p = 0.19). EMs might be closely related to local deviations of CD4 + T cells.

CONCLUSION

There was no obvious correlation between EMs and systematic deviations of CD4 + T cells, EMs might be closely related to local deviations of CD4 + T cells. Further study on the functional deviations and subpopulation distribution of CD4 + T cells is urgently needed.

Signatures of necroptosis-related genes as diagnostic markers of endometriosis and their correlation with immune infiltration

BACKGROUND

Endometriosis (EMS) occurs when normal uterine tissue grows outside the uterus and causes chronic pelvic pain and infertility. Endometriosis-associated infertility is thought to be caused by unknown mechanisms. In this study, using necroptosis-related genes, we developed and validated multigene joint signatures to diagnose EMS and explored their biological roles.

METHODS

We downloaded two databases (GSE7305 and GSE1169) from the Gene Expression Omnibus (GEO) database and 630 necroptosis-related genes from the GeneCards and GSEA databases. The limma package in Rsoftware was used to identify differentially expressed genes (DEGs). We interleaved common differentially expressed genes (co-DEGs) and necroptosis-related genes (NRDEGs) in the endometriosis dataset. The DEGs functions were reflected by gene ontology analysis (GO), pathway enrichment analysis, and gene set enrichment analysis (GSEA). We used CIBERSORT to analyze the immune microenvironment differences between EMS patients and controls. Furthermore, a correlation was found between necroptosis-related differentially expressed genes and infiltrating immune cells to better understand the molecular immune mechanism.

RESULTS

Compared with the control group, this study revealed that 10 NRDEGs were identified in EMS. There were two types of immune cell infiltration abundance (activated NK cells and M2 macrophages) in these two datasets, and the correlation between different groups of samples was statistically significant (P < 0.05). MYO6 consistently correlated with activated NK cells in the two datasets. HOOK1 consistently demonstrated a high correlation with M2 Macrophages in two datasets. The immunohistochemical result indicated that the protein levels of MYO6 and HOOK1 were increased in patients with endometriosis, further suggesting that MYO6 and HOOK1 can be used as potential biomarkers for endometriosis.

CONCLUSIONS

We identified ten necroptosis-related genes in EMS and assessed their relationship with the immune microenvironment. MYO6 and HOOK1 may serve as novel biomarkers and treatment targets in the future.

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.

The role of CD8+ T cells in endometriosis: a systematic review

Background

Endometriosis is a chronic disease affecting 6-10% of women of reproductive age. It is an important cause of infertility and chronic pelvic pain with poorly understood aetiology. CD8+ T (CD8 T) cells were shown to be linked to infertility and chronic pain and play a significant role in lesion clearance in other pathologies, yet their function in endometriosis is unknown. We systematically evaluated the literature on the CD8 T in peripheral blood and endometriosis-associated tissues to determine the current understanding of their pathophysiological and clinical relevance in the disease and associated conditions (e.g. infertility and pelvic pain).

Methods

Four databases were searched (MEDLINE, EMBASE, Web of Science, CINAHL), from database inception until September 2022, for papers written in the English language with database-specific relevant terms/free-text terms from two categories: CD8 T cells and endometriosis. We included peer-reviewed papers investigating CD8 T cells in peripheral blood and endometriosis-associated tissues of patients with surgically confirmed endometriosis between menarche and menopause, and animal models with oestrous cycles. Studies enrolling participants with other gynaecological pathologies (except uterine fibroids and tubal factor infertility used as controls), cancer, immune diseases, or taking immune or hormonal therapy were excluded.

Results

28 published case-control studies and gene set analyses investigating CD8 T cells in endometriosis were included. Data consistently indicate that CD8 T cells are enriched in endometriotic lesions in comparison to eutopic endometrium, with no differences in peripheral blood CD8 T populations between patients and healthy controls. Evidence on CD8 T cells in peritoneal fluid and eutopic endometrium is conflicting. CD8 T cell cytotoxicity was increased in the menstrual effluent of patients, and genomic analyses have shown a clear trend of enriched CD8 T effector memory cells in the eutopic endometrium of patients.

Conclusion

Literature on CD8 T cells in endometriosis-associated tissues is inconsistent. Increased CD8 T levels are found in endometriotic lesions, however, their activation potential is understudied in all relevant tissues. Future research should focus on identifying clinically relevant phenotypes to support the development of non-invasive diagnostic and treatment strategies.

Systematic Review Registration

PROSPERO identifier CRD42021233304.

Identification and validation of risk score model based on gene set activity as a diagnostic biomarker for endometriosis

Objective

The enigmatic nature of Endometriosis (EMS) pathogenesis necessitates investigating alterations in signaling pathway activity to enhance our comprehension of the disease's characteristics.

Methods

Three published gene expression profiles (GSE11691, GSE25628, and GSE7305 datasets) were downloaded, and the "combat" algorithm was employed for batch correction, gene expression difference analysis, and pathway enrichment difference analysis. The protein-protein interaction (PPI) network was constructed to identify core genes, and the relative enrichment degree of gene sets was evaluated. The Lasso regression model identified candidate gene sets with diagnostic value, and a risk scoring diagnostic model was constructed for further validation on the GSE86534 and GSE5108 datasets. CIBERSORT was used to assess the composition of immune cells in EMS, and the correlation between EMS diagnostic value gene sets and immune cells was evaluated.

Results

A total of 568 differentially expressed genes were identified between eutopic and ectopic endometrium, with 10 core genes in the PPI network associated with cell cycle regulation. Inflammation-related pathways, including cytokine-receptor signaling and chemokine signaling pathways, were significantly more active in ectopic endometrium compared to eutopic endometrium. Diagnostic gene sets for EMS, such as homologous recombination, base excision repair, DNA replication, P53 signaling pathway, adherens junction, and SNARE interactions in vesicular transport, were identified. The risk score's area under the curve (AUC) was 0.854, as indicated by the receiver operating characteristic (ROC) curve, and the risk score's diagnostic value was validated by the validation cohort. Immune cell infiltration analysis revealed correlations between the risk score and Macrophages M2, Plasma cells, resting NK cells, activated NK cells, and regulatory T cells.

Conclusion

The risk scoring diagnostic model, based on pathway activity, demonstrates high diagnostic value and offers novel insights and strategies for the clinical diagnosis and treatment of Endometriosis.

Intraperitoneal metastasis of ovarian cancer: new insights on resident macrophages in the peritoneal cavity

Ovarian cancer metastasis occurs primarily in the peritoneal cavity. Orchestration of cancer cells with various cell types, particularly macrophages, in the peritoneal cavity creates a metastasis-favorable environment. In the past decade, macrophage heterogeneities in different organs as well as their diverse roles in tumor settings have been an emerging field. This review highlights the unique microenvironment of the peritoneal cavity, consisting of the peritoneal fluid, peritoneum, and omentum, as well as their own resident macrophage populations. Contributions of resident macrophages in ovarian cancer metastasis are summarized; potential therapeutic strategies by targeting such cells are discussed. A better understanding of the immunological microenvironment in the peritoneal cavity will provide a stepping-stone to new strategies for developing macrophage-based therapies and is a key step toward the unattainable eradication of intraperitoneal metastasis of ovarian cancer.

New concepts on the etiology of endometriosis

Endometriosis is a serious, chronic disorder where endometrial tissue grows outside the uterus, causing severe pelvic pain and infertility. It affects 11% of women. Endometriosis is a multifactorial disorder of unclear etiology, although retrograde menstruation plays a major role. It has a genetic component with over 40 genetic risk factors mapped, although their mechanism of action is still emerging. New evidence suggests a role for retrograde menstruation of endometrial stem/progenitor cells, now that identifying markers of these cells are available. Recent lineage tracing and tissue clearing microscopy and 3D reconstruction has provided new understanding of endometrial glandular structure, particularly the horizontal orientation and interconnection of basalis glands. New sequencing technologies, particularly whole genome DNA sequencing are revealing somatic mutations, including in cancer driver genes, in normal and eutopic endometrium of patients with endometriosis, as well as ectopic endometriotic lesions. Methylome sequencing is offering insight into the regulation of genes and the role of the environmental factors. Single cell RNA sequencing reveals the transcriptome of individual endometrial cells, shedding new light on the diversity and range of cellular subpopulations of the major cell types present in the endometrium and in endometriotic lesions. New endometrial epithelial organoid cultures replicating glandular epithelium are providing tractable models for studying endometriosis. Organoids derived from menstrual fluid offer a non-invasive source of endometrial tissue and a new avenue for testing drugs and developing personalized medicine for treating endometriosis. These new approaches are rapidly advancing our understanding of endometriosis etiology.

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.

Single-Cell Analyses of the Oral Mucosa Reveal Immune Cell Signatures

Inflammatory bowel disease (IBD) is a common immune-related disease of the gastrointestinal tract that affects many people around the world. Extraintestinal manifestations of IBD have been frequently observed in recent years; one of these, periodontitis, has gained increasing attention. Periodontitis is a chronic inflammatory disease characterized by inflammation and destruction of periodontal tissues due to the disruption of host immune homeostasis. Clinical studies have revealed that periodontal inflammation is associated with IBD. However, the detailed heterogeneity of immune cells and their developmental relationships remain poorly understood at the single-cell level. In this study, we performed single-cell RNA (scRNA) sequencing to assess the transcriptome heterogeneity in periodontal tissues. We found the cellular composition and subclusters with specific gene expression profiles by uniform manifold approximation and projection. Pseudo-time analysis combined with gene enrichment analysis was performed to reveal cell states and key pathways. Ligand-receptor pairs revealed cell-cell communication among the immune cell types in periodontal tissues. Based on our analysis, we identified an essential role for Tcr⁺ macrophage, Prdx1⁺ neutrophil, and Mif⁺ T subpopulations with proinflammatory phenotype infiltration. Moreover, we examined the heterogeneity of monocytic cells and B cells. Collectively, the mapping of scRNA revealed the complex cellular landscape of oral mucosa immune cells and highlighted these immune cells as a previously unrecognized factor that may aggravate inflammation. Our analysis proves that periodontitis could exacerbate colitis and provides novel ideas for controlling and preventing IBD exacerbations.

The heterogeneity of fibrosis and angiogenesis in endometriosis revealed by single-cell RNA-sequencing

Fibrosis, angiogenesis and chronic inflammation are the inherent characteristics of endometriosis (EMS). The cellular heterogeneity of ectopic and non-ectopic endometrium by single-cell RNA-sequencing (scRNA-seq)at secretory phase without the disturbance of hormone drugs hasn't been explored so far. In this study, scRNA-seq was adopted to explore the properties of ectopic endometrium (ECE), eutopic endometrium (EUE) and normal endometrium (NOE) at secretory phase. We found that (i) The proportion of myofibroblasts, pericytes, endothelial cells and macrophages in ECE overwhelms that of non-ectopic tissues (EUE and NOE), and Myofibro.C2 was the predominant myofibroblast sub-cluster in ECE. (ii) Myofibroblasts were mainly fibroblast-to-myofibroblast transdifferentiation (FMT) and pericytes were endothelial cell-dependent differentiation in ECE. (iii) Both myofibroblasts and pericytes had a low differentiation potential. (iv) The increased inflammation score, deceased NK cells, T cell exhaustion score and antigen-presenting capacity in ECE confirmed the inflammatory properties and immunodeficiency of ECE. These findings suggested that myofibroblasts, pericytes and macrophages may be the potential targets for anti-fibrotic, anti-angiogenic and anti-inflammatory therapy of EMS.

Gata6(+) large peritoneal macrophages: an evolutionarily conserved sentinel and effector system for infection and injury

There are striking similarities between the sea urchin cavity macrophage-like phagocytes (coelomocytes) and mammalian cavity macrophages in not only their location, but also their behaviors. These cells are crucial for maintaining homeostasis within the cavity following a breach, filling the gap and functioning as a barrier between vital organs and the environment. In this review, we summarize the evolving literature regarding these Gata6⁺ large peritoneal macrophages (GLPMs), focusing on ontogeny, their responses to perturbations, including their rapid aggregation via coagulation, as well as scavenger receptor cysteine-rich domains and their potential roles in diseases, such as cancer. We challenge the 50-year old phenomenon of the 'macrophage disappearance reaction' (MDR) and propose the new term 'macrophage disturbance of homeostasis reaction' (MDHR), which may better describe this complex phenomenon.

Focus on the role of NLRP3 inflammasome in the pathology of endometriosis: a review on molecular mechanisms and possible medical applications

Endometriosis (EMS) is a gynecological disease that leads to pathological conditions, which are connected to the initiation of pro-inflammatory cytokine production. Inflammation plays a vital role in the pathogenesis of EMS. The activation and formation of cytoplasmic inflammasome complexes is considered an important step of inflammation and a key regulator of pyroptosis, a form of cell death. NLR family pyrin domain containing 3 (NLRP3) inflammasome complex modulates innate immune activity and inflammation. The NLRP3 inflammasome activates cysteine protease caspase-1, which produces active pro-inflammatory interleukins (ILs), including IL-1β and IL-18. The aim of this review article was to discuss the involvement of NLRP3 inflammasome assembly and its activation in the pathophysiology of EMS and target related pathways in designing appropriate therapeutic approaches. Dysregulation of sex hormone signaling pathways was associated with over-activation of the NLPR3 inflammasome. In this study, we demonstrated the involvement of NLRP3 inflammasome signaling pathways in the pathophysiology of EMS. The manuscript also discusses the beneficial effects of targeted therapy through synthetic inhibitors of NLRP3 signaling pathways to control EMS lesions.

Deficiency of MST1 in endometriosis related peritoneal macrophages promoted the autophagy of ectopic endometrial stromal cells by IL-10

Changes in the function of peritoneal macrophages contribute to the homeostasis of the peritoneal immune microenvironment in endometriosis. The mechanism by which ectopic tissues escape phagocytic clearance by macrophages to achieve ectopic colonization and proliferation is unknown. The expression of CD163 in peritoneal macrophages in patients with endometriosis is increased, with the overexpression of MAPK, which can promote the M2-type polarization of macrophages and reduce their ability to phagocytose ectopic endometrial cells. As an upstream regulator of MAPK, MST1 expression is deficient in peritoneal macrophages of patients with endometriosis. This process is regulated by miR-887-5p, a noncoding RNA targeting MST1. Moreover, MST1-knockout macrophages secrete anti-inflammatory factor IL-10, which promotes autophagy of ectopic endometrial stromal cells. These results suggest that MST1 deficient macrophages may accelerate the autophagy of ectopic endometrium via IL-10 which was regulated by miR-887-5p.

Transcriptome Profiling of Eutopic and Ectopic Endometrial Stromal Cells in Women with Endometriosis Based on High-Throughput Sequencing

Endometriosis is a common gynecological disease that affects approximately 5–10% of reproductive-aged women. However, the etiology and pathophysiology of endometriosis are currently unclear. The objective of this study was to identify a potential pathogenic gene of endometriosis using RNA sequencing (RNA-seq) analysis. Human endometrial stromal cells were isolated from four patients receiving surgical treatment for endometriosis during laparoscopic surgery, and RNA-seq was used to examine differentially expressed genes (DEGs) in eutopic and ectopic endometrial stromal cells. The functional significance of the differentially expressed genes was analyzed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. A total of 1309 upregulated and 663 downregulated genes were identified through the analysis of the transcriptomes of eutopic and ectopic endometrial stromal cells. Furthermore, KEGG analysis indicated that these DEGs were mainly enriched in the PI3K-Akt signaling pathway, cytokine–cytokine receptor interaction, and MAPK signaling pathway. Our study identified differential gene expression in eutopic as compared to ectopic endometrial tissue stromal cells. We strongly believe that our findings can bring new insights into the underlying mechanisms of endometriosis. However, future research is necessary to clarify the roles of the identified genes.

Research progress on application of single-cell TCR/BCR sequencing technology to the tumor immune microenvironment, autoimmune diseases, and infectious diseases

Single-cell omics is the profiling of individual cells through sequencing and other technologies including high-throughput analysis for single-cell resolution, cell classification, and identification as well as time series analyses. Unlike multicellular studies, single-cell omics overcomes the problem of cellular heterogeneity. It provides new methods and perspectives for in-depth analyses of the behavior and mechanism of individual cells in the cell population and their relationship with the body, and plays an important role in basic research and precision medicine. Single-cell sequencing technologies mainly include single-cell transcriptome sequencing, single-cell assay for transposase accessible chromatin with high-throughput sequencing, single-cell immune profiling (single-cell T-cell receptor [TCR]/B-cell receptor [BCR] sequencing), and single-cell transcriptomics. Single-cell TCR/BCR sequencing can be used to obtain a large amount of single-cell gene expression and immunomics data at one time, and combined with transcriptome sequencing and TCR/BCR diversity data, can resolve immune cell heterogeneity. This paper summarizes the progress in applying single-cell TCR/BCR sequencing technology to the tumor immune microenvironment, autoimmune diseases, infectious diseases, immunotherapy, and chronic inflammatory diseases, and discusses its shortcomings and prospects for future application.

“Iron triangle” of regulating the uterine microecology: Endometrial microbiota, immunity and endometrium

The uterus is the core place for breeding new life. The balance and imbalance of uterine microecology can directly affect or even dominate the female reproductive health. Emerging data demonstrate that endometrial microbiota, endometrium and immunity play an irreplaceable role in regulating uterine microecology, forming a dynamic iron triangle relationship. Up to nowadays, it remains unclear how the three factors affect and interact with each other, which is also a frontier topic in the emerging field of reproductive tract microecology. From this new perspective, we aim to clarify the relationship and mechanism of the interaction of these three factors, especially their pairwise interactions. Finally, the limitations and future perspectives of the current studies are summarized. In general, these three factors have a dynamic relationship of mutual dependence, promotion and restriction under the physiological or pathological conditions of uterus, among which the regulatory mechanism of microbiota and immunity plays a role of bridge. These findings can provide new insights and measures for the regulation of uterine microecology, the prevention and treatment of endometrial diseases, and the further multi-disciplinary integration between microbiology, immunology and reproductive medicine.

Single-cell analysis of endometriosis reveals a coordinated transcriptional programme driving immunotolerance and angiogenesis across eutopic and ectopic tissues

Endometriosis is characterized by the growth of endometrial-like tissue outside the uterus. It affects many women during their reproductive age, causing years of pelvic pain and potential infertility. Its pathophysiology remains largely unknown, which limits early diagnosis and treatment. We characterized peritoneal and ovarian lesions at single-cell transcriptome resolution and compared them to matched eutopic endometrium, unaffected endometrium and organoids derived from these tissues, generating data on over 122,000 cells across 14 individuals. We spatially localized many of the cell types using imaging mass cytometry. We identify a perivascular mural cell specific to the peritoneal lesions, with dual roles in angiogenesis promotion and immune cell trafficking. We define an immunotolerant peritoneal niche, fundamental differences in eutopic endometrium and between lesion microenvironments and an unreported progenitor-like epithelial cell subpopulation. Altogether, this study provides a holistic view of the endometriosis microenvironment that represents a comprehensive cell atlas of the disease in individuals undergoing hormonal treatment, providing essential information for future therapeutics and diagnostics.

The presence of living endometrial cells in ovarian endometriotic cyst fluid may contribute to the recurrence of endometriosis after surgical excision of endometriomas

BACKGROUND

Many factors can affect the recurrence of endometriosis after surgery, however, whether endometriotic cyst fluid contributes to endometriosis recurrence after surgical excision of ovarian endometriomas remains unclear. The objective of this study was to determine the presence of endometrial cells in ovarian endometriosis cyst fluid and the potential differences between these cells and those in the cyst wall.

METHODS

Samples of cyst fluid (n = 39) and drainage fluid (n = 14) were collected from patients with ovarian endometriomas undergoing laparoscopic surgery. Drainage fluid from 14 patients without endometriosis was used as a control. The presence of endometrial cells in cyst fluid and drainage fluid was determined by cell culture in vitro and immunostaining. In addition, cyst fluid endometrial fragments and viscosity were analysed by transcriptome sequencing analysis and apparent diffusion coefficients, respectively. An animal model was used to confirm the ability of endometrial cells in cyst fluid to form new lesions.

RESULTS

We found endometrium-like tissues in 71.8% (28/39) of cyst fluid and 71.4% (10/14) of drainage fluid samples by histopathological examination, and the presence of endometrioid tissue in cyst fluid was related to the viscosity of the cyst fluid. The living endometrial cells in cyst fluid and drainage fluid were confirmed by cell culture in vitro and immunostaining. Moreover, the adhesion ability of endometrial fragments in cyst fluid was significantly higher than that of ectopic tissues in the cyst wall (P < 0.05). In addition, living endometrial cells in the cyst fluid were able to adhere and alive in the animal model.

CONCLUSIONS

The existence of living endometrial cells with high adhesion ability in ovarian endometriotic cyst fluid may contribute to the recurrence of endometriosis after surgical excision of endometriomas due to cyst fluid outflow during the surgical procedure.

Evaluating the Phagocytic Index of Peripheral Leukocytes in Endometriosis by Plasma Experiments

Background and Objectives: Endometriosis is a benign, chronic disease, that negatively influences the quality of life of affected women and is responsible for a remarkable amount of infertility. The pathophysiology of the disease is still not clarified, but the insufficient immune surveillance plays a significant role in it. The phagocyte function of innate immune cells may play a role in the elimination of ectopic endometrium. The purpose of this study is to examine the phagocyte function of neutrophil granulocytes and monocytes, incubated in heat-inactivated and not-inactivated plasma samples from healthy women and from women with endometriosis before and after the surgical treatment. Materials and Methods: Blood samples were collected from eight preoperative and eight postoperative patients with endometriosis before and after the surgical treatment, and from 16 healthy patients as controls. Neutrophil granulocytes, monocytes and blood plasma samples were isolated. Cells were incubated in different plasma samples, and the phagocytic index was determined with a fluorescence microscope. Results: The phagocytic index of granulocytes and monocytes isolated from patients with endometriosis was significantly decreased compared to healthy women after the cells were incubated in their own plasma. Preoperatively isolated cells from patients with endometriosis demonstrated an improved phagocyte function after incubating them in plasma samples from healthy controls. In contrast, the phagocytic activity of cells from healthy women significantly reduced after being incubated in the plasma of preoperative endometriosis patients. The heat-inactivation of plasma samples did not affect the results. Conclusions: Active endometriosis lesions may produce heat-stable systemic immunomodulatory factors, which reduced the phagocyte function of peripheral monocytes and neutrophil granulocytes. The phagocyte function of these cells can be normalized after the complete surgical removal of endometriosis, which then demonstrates similar values as in healthy women.

Identification of NFASC and CHL1 as Two Novel Hub Genes in Endometriosis Using Integrated Bioinformatic Analysis and Experimental Verification

Background

Endometriosis (EMS) is a common and highly recurrent gynecological disease characterized by chronic pain and infertility. There are no definitive therapies for endometriosis since the pathogenesis remains undetermined. This study aimed to identify EMS-related functional modules and hub genes by integrated bioinformatics analysis.

Methods

Three endometriosis expression profiling series (GSE25628, GSE23339, and GSE7305) were obtained from Gene Expression Omnibus (GEO). The EMS-related module was constructed by weighted gene co-expression network analysis (WGCNA), followed by Gene Ontology (GO) enrichment analyses. Cytohubba and the MCODE plug-ins of Cytoscape were used to screen out the hub genes, which were verified via receiver operating characteristic (ROC) curves. Immunohistochemistry was performed to verify the protein expression of the hub genes in ectopic endometrial tissues. Moreover, CIBERSORT was used to analyze the relationship between the abundance of immune cells infiltration and the expression of hub genes.

Results

Among the 18 modules obtained, the darkmagenta module was identified as the EMS-related module, genes of which were significantly enriched to terms referring to cell migration and neurogenesis. NFASC and CHL1 were screened out and prioritized as hub genes through Cytoscape and confirmed to be differentially upregulated in ectopic endometrial samples. Finally, the expression of hub genes was related to the abundance of immune cells infiltration. The higher expression of NFASC or CHL1 correlated with increased M2 macrophages and decreased natural killer (NK) cells in ectopic lesions.

Conclusion

This study provided new insights into the molecular factors underlying the pathogenesis of endometriosis and provided a theoretical basis for the potential that the two hub genes, NFASC and CHL1, might be novel biomarkers and therapeutic targets in the future.

Bioinformatical analysis identifies PDLIM3 as a potential biomarker associated with immune infiltration in patients with endometriosis

Background

Endometriosis is a chronic systemic disease, whose classic symptoms are pelvic pain and infertility. This disease seriously reduces the life quality of patients. The pathogenesis, recognition and treatment of endometriosis is still unclear, and cannot be over emphasized. The aim of our study was to investigate the potential biomarker of endometriosis for the mechanism and treatment.

Methods

Using GSE11691, GSE23339 and GSE5108 datasets, differentially expressed genes (DEGs) were identified between endometriosis and normal samples. The functions of DEGs were reflected by the analysis of gene ontology (GO), pathway enrichment and gene set enrichment analysis (GSEA). The LASSO regression model was performed to identify candidate biomarkers. The receiver operating characteristic curve (ROC) was used to evaluate discriminatory ability of candidate biomarkers. The predictive value of the markers in endometriosis were further validated in the GSE120103 dataset. Then, the expression level of biomarkers was detected by qRT-PCR and Western blot. Finally, the relationship between candidate biomarker expression and immune infiltration was estimated using CIBERSORT.

Results

A total of 42 genes were identified, which were mainly involved in cytokine-cytokine receptor interaction, systemic lupus erythematosus and chemokine signaling pathway. We confirmed PDLIM3 was a specific biomarker in endometriosis (AUC = 0.955) and validated in the GSE120103 dataset (AUC = 0.836). The mRNA and protein expression level of PDLIM3 in endometriosis tissue was significantly higher than normal. Immune cell infiltration analysis revealed that PDLIM3 was correlated with M2 macrophages, neutrophils, CD4+ memory resting T cells, gamma delta T cells, M1 Macrophages, resting mast cells, follicular helper T cells, activated NK cells, CD8+ T cells, regulatory T cells (Tregs), naive B cells, plasma cells and resting NK cells.

Bioinformatics Analysis Identifies Molecular Markers Regulating Development and Progression of Endometriosis and Potential Therapeutic Drugs

Endometriosis, a common disease that presents as polymorphism, invasiveness, and extensiveness, with clinical manifestations including dysmenorrhea, infertility, and menstrual abnormalities, seriously affects quality of life in women. To date, its underlying etiological mechanism of action and the associated regulatory genes remain unclear. This study aimed to identify molecular markers and elucidate mechanisms underlying the development and progression of endometriosis. Specifically, we downloaded five microarray expression datasets, namely, GSE11691, GSE23339, GSE25628, GSE7305, and GSE105764, from the Gene Expression Omnibus (GEO) database. These datasets, obtained from endometriosis tissues, alongside normal controls, were subjected to in-depth bioinformatics analysis for identification of differentially expressed genes (DEGs), followed by analysis of their function and pathways via gene ontology (GO) and KEGG pathway enrichment analyses. Moreover, we constructed a protein–protein interaction (PPI) network to explore the hub genes and modules, and then applied machine learning algorithms support vector machine-recursive feature elimination and least absolute shrinkage and selection operator (LASSO) analysis to identify key genes. Furthermore, we adopted the CIBERSORTx algorithm to estimate levels of immune cell infiltration while the connective map (CMAP) database was used to identify potential therapeutic drugs in endometriosis. As a result, a total of 423 DEGs, namely, 233 and 190 upregulated and downregulated, were identified. On the other hand, a total of 1,733 PPIs were obtained from the PPI network. The DEGs were mainly enriched in immune-related mechanisms. Furthermore, machine learning and LASSO algorithms identified three key genes, namely, apelin receptor (APLNR), C–C motif chemokine ligand 21 (CCL21), and Fc fragment of IgG receptor IIa (FCGR2A). Furthermore, 16 small molecular compounds associated with endometriosis treatment were identified, and their mechanism of action was also revealed. Taken together, the findings of this study provide new insights into the molecular factors regulating occurrence and progression of endometriosis and its underlying mechanism of action. The identified therapeutic drugs and molecular markers may have clinical significance in early diagnosis of endometriosis.