Possible involvement of crosstalk between endometrial cells and mast cells in the development of endometriosis via CCL8/CCR1

KLF4's role in regulating nitric oxide production and promoting microvascular formation following ischemic stroke

This study examines KLF4's role in endothelial cells (ECs), emphasizing its effects on nitric oxide (NO) production, microvascular formation, and oxidative stress regulation following ischemic stroke. Through high-throughput sequencing, we identified eight cell subpopulations in carotid artery tissues post-stroke, with KLF4 notably elevated in ECs. KLF4 overexpression in ECs promoted NO synthesis, enhanced endothelial tube formation, mitigated oxidative stress, and improved smooth muscle cells (SMCs) function, collectively boosting blood flow in ischemic regions. These findings highlight KLF4 as pivotal in vascular regeneration and oxidative stress reduction, positioning it as a promising target for cardiovascular and cerebrovascular therapies.

Overexpressed nicotinamide N‑methyltransferase in endometrial stromal cells induced by macrophages and estradiol contributes to cell proliferation in endometriosis

Endometriosis, an estrogen-dependent chronic inflammatory condition, afflicts reproductive-aged women. However, the underlying pathological mechanisms remain to be elucidated. Nicotinamide N-methyltransferase (NNMT) is a critical enzyme involved in cellular metabolism and methylation regulation. This study investigated the role of NNMT in endometriosis. By analyzing datasets GSE5108, GSE7305, GSE141549, GSE23339, and GSE25628, we identified a significant overexpression of NNMT in the eutopic endometrium and ectopic lesions of endometriosis patients compared to normal endometrium. Furthermore, NNMT was upregulated in collected endometrioma specimens and isolated primary endometrial stromal cells (ESCs) compared to their respective controls. Inhibition of NNMT using JBSNF-000088 attenuated the proliferation, migration, and invasion of ESCs. In vivo, treatment of mouse models of endometriosis with JBSNF-000088 resulted in a marked reduction in lesion weight and quantity. NNMT expression in ESCs was dose-dependently upregulated by 17β-estradiol at concentrations of 1 nM, 10 nM, and 100 nM, an effect that was attenuated by 10 nM progesterone. Additionally, treating HESCs with macrophage-conditioned medium elevated NNMT expression at both mRNA and protein levels. Knockdown of NNMT impeded the proliferation, migration, and invasion of ESCs, which was paralleled by decreased phosphorylation levels of Erb-b2 receptor tyrosine kinase 4 (ERBB4), PI3K, and AKT. Conversely, overexpressing ERBB4 mitigated the NNMT knockdown-induced decline in phosphorylated PI3K and AKT and rescued the proliferation of ESCs. Altogether, these results indicate that the overexpression of NNMT induced by estrogen and macrophage interaction modulates ESC proliferation via the NNMT-ERBB4-PI3K/AKT signaling pathway, as well as promotes cellular migration and invasion, contributing to the development of endometriosis.

Screening and identification of key biomarkers associated with endometriosis using bioinformatics and next-generation sequencing data analysis

Background

Endometriosis is a common cause of endometrial-type mucosa outside the uterine cavity with symptoms such as painful periods, chronic pelvic pain, pain with intercourse and infertility. However, the early diagnosis of endometriosis is still restricted. The purpose of this investigation is to identify and validate the key biomarkers of endometriosis.

Methods

Next-generation sequencing dataset GSE243039 was obtained from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) between endometriosis and normal control samples were identified. After screening of DEGs, gene ontology (GO) and REACTOME pathway enrichment analyses were performed. Furthermore, a protein–protein interaction (PPI) network was constructed and modules were analyzed using the Human Integrated Protein–Protein Interaction rEference database and Cytoscape software, and hub genes were identified. Subsequently, a network between miRNAs and hub genes, and network between TFs and hub genes were constructed using the miRNet and NetworkAnalyst tool, and possible key miRNAs and TFs were predicted. Finally, receiver operating characteristic curve analysis was used to validate the hub genes.

Results

A total of 958 DEGs, including 479 upregulated genes and 479 downregulated genes, were screened between endometriosis and normal control samples. GO and REACTOME pathway enrichment analyses of the 958 DEGs showed that they were mainly involved in multicellular organismal process, developmental process, signaling by GPCR and muscle contraction. Further analysis of the PPI network and modules identified 10 hub genes, including vcam1, snca, prkcb, adrb2, foxq1, mdfi, actbl2, prkd1, dapk1 and actc1. Possible target miRNAs, including hsa-mir-3143 and hsa-mir-2110, and target TFs, including tcf3 (transcription factor 3) and clock (clock circadian regulator), were predicted by constructing a miRNA-hub gene regulatory network and TF-hub gene regulatory network.

Conclusions

This investigation used bioinformatics techniques to explore the potential and novel biomarkers. These biomarkers might provide new ideas and methods for the early diagnosis, treatment and monitoring of endometriosis.

Inflammatory Role of CCR1 in the Central Nervous System

BACKGROUND

Chemokine ligands and their corresponding receptors are essential for regulating inflammatory responses. Chemokine receptors can stimulate immune activation or inhibit/promote signaling pathways by binding to specific chemokine ligands. Among these receptors, CC chemokine receptor 1 (CCR1) is extensively studied as a G protein-linked receptor target, predominantly expressed in various leukocytes, and is considered a promising target for anti-inflammatory therapy. Furthermore, CCR1 is essential for monocyte extravasation and transportation in inflammatory conditions. Its involvement in inflammatory diseases of the central nervous system (CNS), including multiple sclerosis, Alzheimer's disease, and stroke, has been extensively studied along with its ligands. Animal models have demonstrated the beneficial effects resulting from inhibiting CCR1 or its ligands.

SUMMARY

This review demonstrates the significance of CCR1 in CNS inflammatory diseases, the molecules implicated in the inflammatory pathway, and potential drugs or molecules for treating CNS diseases. This evidence may offer new targets or strategies for treating inflammatory CNS diseases.

Unraveling pathogenesis, biomarkers and potential therapeutic agents for endometriosis associated with disulfidptosis based on bioinformatics analysis, machine learning and experiment validation

BACKGROUND

Endometriosis (EMs) is an enigmatic disease of yet-unknown pathogenesis. Disulfidptosis, a novel identified form of programmed cell death resulting from disulfide stress, stands a chance of treating diverse ailments. However, the potential roles of disulfidptosis-related genes (DRGs) in EMs remain elusive. This study aims to thoroughly explore the key disulfidptosis genes involved in EMs, and probe novel diagnostic markers and candidate therapeutic compounds from the aspect of disulfidptosis based on bioinformatics analysis, machine learning, and animal experiments.

RESULTS

Enrichment analysis on key module genes and differentially expressed genes (DEGs) of eutopic and ectopic endometrial tissues in EMs suggested that EMs was closely related to disulfidptosis. And then, we obtained 20 and 16 disulfidptosis-related DEGs in eutopic and ectopic endometrial tissue, respectively. The protein-protein interaction (PPI) network revealed complex interactions between genes, and screened nine and ten hub genes in eutopic and ectopic endometrial tissue, respectively. Furthermore, immune infiltration analysis uncovered distinct differences in the immunocyte, human leukocyte antigen (HLA) gene set, and immune checkpoints in the eutopic and ectopic endometrial tissues when compared with health control. Besides, the hub genes mentioned above showed a close correlation with the immune microenvironment of EMs. Furthermore, four machine learning algorithms were applied to screen signature genes in eutopic and ectopic endometrial tissue, including the binary logistic regression (BLR), the least absolute shrinkage and selection operator (LASSO), the support vector machine-recursive feature elimination (SVM-RFE), and the extreme gradient boosting (XGBoost). Model training and hyperparameter tuning were implemented on 80% of the data using a ten-fold cross-validation method, and tested in the testing sets which determined the excellent diagnostic performance of these models by six indicators (Sensitivity, Specificity, Positive Predictive Value, Negative Predictive Value, Accuracy, and Area Under Curve). And seven eutopic signature genes (ACTB, GYS1, IQGAP1, MYH10, NUBPL, SLC7A11, TLN1) and five ectopic signature genes (CAPZB, CD2AP, MYH10, OXSM, PDLIM1) were finally identified based on machine learning. The independent validation dataset also showed high accuracy of the signature genes (IQGAP1, SLC7A11, CD2AP, MYH10, PDLIM1) in predicting EMs. Moreover, we screened 12 specific compounds for EMs based on ectopic signature genes and the pharmacological impact of tretinoin on signature genes was further verified in the ectopic lesion in the EMs murine model.

CONCLUSION

This study verified a close association between disulfidptosis and EMs based on bioinformatics analysis, machine learning, and animal experiments. Further investigation on the biological mechanism of disulfidptosis in EMs is anticipated to yield novel advancements for searching for potential diagnostic biomarkers and revolutionary therapeutic approaches in EMs.

Extracellular vesicles in endometriosis: role and potential

Endometriosis is a chronic inflammatory gynecological disease, which profoundly jeopardizes women's quality of life and places a significant medical burden on society. The pathogenesis of endometriosis remains unclear, posing major clinical challenges in diagnosis and treatment. There is an urgent demand for the development of innovative non-invasive diagnostic techniques and the identification of therapeutic targets. Extracellular vesicles, recognized for transporting a diverse array of signaling molecules, have garnered extensive attention as a novel mode of intercellular communication. A burgeoning body of research indicates that extracellular vesicles play a pivotal role in the pathogenesis of endometriosis, which may provide possibility and prospect for both diagnosis and treatment. In light of this context, this article focuses on the involvement of extracellular vesicles in the pathogenesis of endometriosis, which deliver information among endometrial stromal cells, macrophages, mesenchymal stem cells, and other cells, and explores their potential applications in the diagnosis and treatment, conducing to the emergence of new strategies for clinical diagnosis and treatment.

A method for isolating and culturing ectopic epithelial and stromal cells to study human adenomyosis

PURPOSE

Although adenomyosis is a common and benign gynecological disease, the specific pathogenesis of this condition is yet to be fully elucidated. It is difficult to culture primary cells of the ectopic endometrial epithelia and stroma from human adenomyosis lesions. Most of the previous of studies on adenomyosis were based on primary eutopic endometrium cells. However, as yet, no efficient protocols have been developed for the isolation, culture or purification of primary ectopic epithelial and stromal cells from human adenomyosis lesions. Therefore, the present study aimed to develop an efficient protocol for the isolation and culture of primary ectopic epithelial and stromal cells from human adenomyosis lesions.

METHODS

In the present study, we aimed to obtain ectopic endometrium tissue from human adenomyosis foci and use a simple and operable type I collagenase digestion method for primary culture. Cells were isolated by sterile cell strainer filtration and flow cytometry was performed to identify, purify, and evaluate the viability of isolated ectopic endometrial cells.

RESULTS

Using our method, we successfully isolated and cultured highly purified and active ectopic endometrial epithelial and stromal cells from human adenomyosis foci. Ep-CAM was expressed in ectopic epithelial cells of human adenomyosis with a purity of 93.74% and a viability of 80.58%. In addition, CD10 were robustly expressed by ectopic stromal cells in human adenomyosis. Cellular purity and viability were determined to be 96.37 and 93.49%, respectively.

CONCLUSION

Our method provides a new experimental model for studying the molecular pathogenesis of human adenomyosis.

GPER involvement in inflammatory pain

Chronic pain is a worldwide refractory health disease that causes major financial and emotional burdens and that is devastating for individuals and society. One primary source of pain is inflammation. Current treatments for inflammatory pain are weakly effective, although they usually replace analgesics, such as opioids and non-steroidal anti-inflammatory drugs, which display serious side effects. Emerging evidence indicates that the membrane G protein-coupled estrogen receptor (GPER) may play an important role in the regulation of inflammation and pain. Herein, we focus on the consequences of pharmacological and genetic GPER modulation in different animal models of inflammatory pain. We also provide a brief overview of the putative mechanisms including the direct action of GPER on pain transmission and inflammation.

Single-cell transcriptome analysis reveals endometrial immune microenvironment in minimal/mild endometriosis

Endometriosis is a common inflammatory disorder in women of reproductive age due to an abnormal endometrial immune environment and is associated with infertility. This study aimed to systematically understand the endometrial leukocyte types, inflammatory environment, and impaired receptivity at single-cell resolution. We profiled single-cell RNA transcriptomes of 138 057 endometrial cells from endometriosis patients (n = 6) and control (n = 7), respectively, using 10x Genomics platform. We found that one cluster of epithelial cells that expressed PAEP and CXCL14 was mostly from the control during the window of implantation (WOI). This epithelial cell type is absent in the eutopic endometrium during the secretory phase. The proportion of endometrial immune cells decreased in the secretory phase in the control group, whereas the cycle variation of total immune cells, NK cells, and T cells was absent in endometriosis. Endometrial immune cells secreted more IL-10 in the secretory phase than in the proliferative phase in the control group; the opposite trend was observed in endometriosis. Proinflammatory cytokines levels in the endometrial immune cells were higher in endometriosis than in the control group. Trajectory analysis revealed that the secretory phase epithelial cells decreased in endometriosis. Ligand-receptor analysis revealed that 11 ligand-receptor pairs were upregulated between endometrial immune and epithelial cells during WOI. These results provide new insights into the endometrial immune microenvironment and impaired endometrial receptivity in infertile women with minimal/mild endometriosis.

Mast Cell Tryptase and Carboxypeptidase A3 in the Formation of Ovarian Endometrioid Cysts

The mechanisms of ovarian endometrioid cyst formation, or cystic ovarian endometriosis, still remain to be elucidated. To address this issue, we analyzed the involvement of mast cell (MC) tryptase and carboxypeptidase A3 (CPA3) in the development of endometriomas. It was found that the formation of endometrioid cysts was accompanied by an increased MC population in the ovarian medulla, as well as by an MC appearance in the cortical substance. The formation of MC subpopulations was associated with endometrioma wall structures. An active, targeted secretion of tryptase and CPA3 to the epithelium of endometrioid cysts, immunocompetent cells, and the cells of the cytogenic ovarian stroma was detected. The identification of specific proteases in the cell nuclei of the ovarian local tissue microenvironment suggests new mechanisms for the regulatory effects of MCs. The cytoplasmic outgrowths of MCs propagate in the structures of the stroma over a considerable distance; they offer new potentials for MC effects on the structures of the ovarian-specific tissue microenvironment under pathological conditions. Our findings indicate the potential roles of MC tryptase and CPA3 in the development of ovarian endometriomas and infer new perspectives on their uses as pharmacological targets in personalized medicine.

Could senescence phenotypes strike the balance to promote tumor dormancy?

After treatment and surgery, patient tumors can initially respond followed by a rapid relapse, or respond well and seemingly be cured, but then recur years or decades later. The state of surviving cancer cells during the long, undetected period is termed dormancy. By definition, the dormant tumor cells do not proliferate to create a mass that is detectable or symptomatic, but also never die. An intrinsic state and microenvironment that are inhospitable to the tumor would bias toward cell death and complete eradication, while conditions that favor the tumor would enable growth and relapse. In neither case would clinical dormancy be observed. Normal cells and tumor cells can enter a state of cellular senescence after stress such as that caused by cancer therapy. Senescence is characterized by a stable cell cycle arrest mediated by chromatin modifications that cause gene expression changes and a secretory phenotype involving many cytokines and chemokines. Senescent cell phenotypes have been shown to be both tumor promoting and tumor suppressive. The balance of these opposing forces presents an attractive model to explain tumor dormancy: phenotypes of stable arrest and immune suppression could promote survival, while reversible epigenetic programs combined with cytokines and growth factors that promote angiogenesis, survival, and proliferation could initiate the emergence from dormancy. In this review, we examine the phenotypes that have been characterized in different normal and cancer cells made senescent by various stresses and how these might explain the characteristics of tumor dormancy.

GPR30-mediated non-classic estrogen pathway in mast cells participates in endometriosis pain via the production of FGF2

Pain is one of the main clinical symptoms of endometriosis, but its underlying mechanism is still not clear. Recent studies have shown that the secretory mediators of mast cells activated by estrogen are involved in the pathogenesis of endometriosis-related pain, but how estrogen-induced mast cell mediators are involved in endometriosis-related pain remains unclear. Here, mast cells were found to be increased in the ovarian endometriotic lesions of patients. They were also closely located closely to the nerve fibers in the ovarian endometriotic lesions from of patients with pain symptoms. Moreover, fibroblast growth factor 2 (FGF2)-positive mast cells were upregulated in endometriotic lesions. The concentration of FGF2 in ascites and the protein level of fibroblast growth factor receptor 1 (FGFR1) were higher in patients with endometriosis than in those without endometriosis, and they were correlated with pain symptoms. In vitro, estrogen could promote the secretion of FGF2 through G-protein-coupled estrogen receptor 30 (GPR30) via the MEK/ERK pathway in rodent mast cells. Estrogen-stimulated mast cells enhanced the concentration of FGF2 in endometriotic lesions and aggravated endometriosis-related pain in vivo. Targeted inhibition of the FGF2 receptor significantly restrained the neurite outgrowth and calcium influx in dorsal root ganglion (DRG) cells. Administration of FGFR1 inhibitor remarkably elevated the mechanical pain threshold (MPT) and prolonged the heat source latency (HSL) in a rat model of endometriosis. These results suggested that the up-regulated production of FGF2 by mast cells through non-classic estrogen receptor GPR30 plays a vital role in the pathogenesis of endometriosis-related pain.

microRNA-100 shuttled by human umbilical cord MSC-secreted extracellular vesicles induces endometriosis by inhibiting HS3ST2

In recent years, the function of human umbilical cord mesenchymal stem cell-originated extracellular vesicles (hUC-MSC-EVs) on endometriosis has been reported, while its specific mechanisms remain largely unknown. This study aimed at investigating the mechanisms underlying the modulation of EVs harboring miR-100 derived from hUC-MSCs in the growth dynamics of endometrial stromal cells in endometriosis. Endometriosis mouse models were established. miR-100 was upregulated and HS3ST2 was downregulated in endometriosis. Ectopic endometrial tissues and umbilical cord tissues were obtained to extract endometrial stromal cells and hUC-MSCs, from which EVs were isolated. Next, the endometrial stromal cells were co-cultured with hUC-MSC-EVs, during which gain- or loss-of-function approaches were employed for gene overexpression or silencing. The binding affinity among miR-100 and HS3ST2 was identified using multiple assays. It was unveiled that miR-100 could target and inhibit HS3ST2. miR-100 from hUC-MSCs could be transferred into the endometrial stromal cells via EVs. Moreover, miR-100 shuttled by hUC-MSC-EVs facilitated endometrial stromal cell proliferation, invasion, and migration, as well as EMT by inhibiting HS3ST2. In vivo experiments also confirmed that hUC-MSC-derived EVs carrying miR-100 induced the occurrence and development of endometriosis. Collectively, hUC-MSC-EV-loaded miR-100 downregulated HS3ST2 to facilitate the development of endometriosis, which highlights a promising therapeutic target for treating endometriosis.

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.

Estrogen mediates inflammatory role of mast cells in endometriosis pathophysiology

Endometriosis is an estrogen dependent, chronic inflammatory disease characterized by the growth of endometrial lining outside of the uterus. Mast cells have emerged as key players in regulating not only allergic responses but also other mechanisms such as angiogenesis, fibrosis, and pain. The influence of estrogen on mast cell function has also been recognized as a potential factor driving disease pathophysiology in number of allergic and chronic inflammatory conditions. However, precise information is lacking on the cross talk between endocrine and immune factors within the endometriotic lesions and whether that contributes to the involvement of mast cells with disease pathophysiology. In this study, we observed a significant increase in mast cell numbers within endometriotic lesions compared to matched eutopic endometrium from the same patients. Compared to eutopic endometrium, endometriotic lesions had significantly higher levels of stem cell factor (SCF), a potent growth factor critical for mast cell expansion, differentiation, and survival for tissue resident mast cells. Targeted mRNA Q-PCR array revealed that the endometriotic lesions harbour microenvironment (upregulation of CPA3, VCAM1, CCL2, CMA1, CCR1, and KITLG) that is conducive to mast cells recruitment and subsequent differentiation. To examine cross-talk of mast cells within the endometriotic lesion microenvironment, endometriotic epithelial cells (12Z) and endometrial stromal cells (hESC) incubated with mast cell-conditioned media showed significantly increased production of pro-inflammatory and chemokinetic cytokines. To further understand the impact of estrogen on mast cells in endometriosis, we induced endometriosis in C57BL/6 mice. Mature mast cells were significantly higher in peritoneal fluid of estrogen-treated mice compared to untreated mice within the sham operated groups. Mouse endometriotic lesion tissue revealed several genes (qRT-PCR) relevant in mast cell biology significantly upregulated in the estrogen treated, endometriosis-induced group compared to control endometrium. The endometriotic lesions from estrogen treated mice also had significantly higher density of Alcian blue stained mast cells compared to untreated lesions or control endometrium. Collectively, these findings suggest that endometriotic lesions provide a microenvironment necessary for recruitment and differentiation of mast cells. In turn, mast cells potentially release pro-inflammatory mediators that contribute to chronic pelvic pain and endometriosis disease progression.

Hyaluronic Acid-Modified Nanoplatforms as a Vector for Targeted Delivery of Autophagy-Related Gene to the Endometriotic Lesions in Mice

This investigation probed endometriosis treatment using targeted nanoparticles (NPs) to modulate autophagic activity. To that end, a novel form of polymer-based NP gene delivery platform consisting of polyethyleneimine (PEI) conjugated to stearic acid (SA) and nucleotides (DNA/siRNAs) and enclosed by hyaluronic acid (HA) was prepared. CD44 is highly upregulated in cystic lesions, and HA–CD44 binding in this specific nanoplatform was used to achieve targeted drug delivery to CD44-expression endometriotic tissues. The expression of autophagy-related genes was modulated to explore the importance of this process in the development of endometriosis. By inducing autophagic activity, we were able to reduce the size of endometriotic cysts and suppress the development of ectopic endometrium. To further confirm the relationship between autophagic activity and this disease in humans and animals, numbers of autophagic vesicles and autophagic protein expression were assessed in lesion tissue samples from patients, revealing there may be consistency between animal and human data. Overall, these data revealed the ability of this (PEI–SA/DNA) HA gene delivery system to regulate autophagic activity and, thereby, aid in the treatment of endometriosis.

Mast Cell Activation Syndrome in COVID-19 and Female Reproductive Function: Theoretical Background vs. Accumulating Clinical Evidence

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can affect almost all systems and organs of the human body, including those responsible for reproductive function in women. The multisystem inflammatory response in COVID-19 shows many analogies with mast cell activation syndrome (MCAS), and MCAS may be an important component in the course of COVID-19. Of note, the female sex hormones estradiol (E2) and progesterone (P4) significantly influence mast cell (MC) behavior. This review presents the importance of MCs and the mediators from their granules in the female reproductive system, including pregnancy, and discusses the mechanism of potential disorders related to MCAS. Then, the available data on COVID-19 in the context of hormonal disorders, the course of endometriosis, female fertility, and the course of pregnancy were compiled to verify intuitively predicted threats. Surprisingly, although COVID-19 hyperinflammation and post-COVID-19 illness may be rooted in MCAS, the available clinical data do not provide grounds for treating this mechanism as significantly increasing the risk of abnormal female reproductive function, including pregnancy. Further studies in the context of post COVID-19 condition (long COVID), where inflammation and a procoagulative state resemble many aspects of MCAS, are needed.

Interactions between Macrophages and Mast Cells in the Female Reproductive System

Mast cells (MCs) and macrophages (Mϕs) are innate immune cells that differentiate from early common myeloid precursors and reside in all body tissues. MCs have a unique capacity to neutralize/degrade toxic proteins, and they are hypothesized as being able to adopt two alternative polarization profiles, similar to Mϕs, with distinct or even opposite roles. Mϕs are very plastic phagocytic cells that are devoted to the elimination of senescent/anomalous endogenous entities (to maintain tissue homeostasis), and to the recognition and elimination of exogenous threats. They can adopt several functional phenotypes in response to microenvironmental cues, whose extreme profiles are the inflammatory/killing phenotype (M1) and the anti-inflammatory/healing phenotype (M2). The concomitant and abundant presence of these two cell types and the partial overlap of their defensive and homeostatic functions leads to the hypothesis that their crosstalk is necessary for the optimal coordination of their functions, both under physiological and pathological conditions. This review will examine the relationship between MCs and Mϕs in some situations of homeostatic regulation (menstrual cycle, embryo implantation), and in some inflammatory conditions in the same organs (endometriosis, preeclampsia), in order to appreciate the importance of their cross-regulation.

The role of peripheral nerve signaling in endometriosis

A hallmark of endometriosis - a chronic debilitating condition whose causes are poorly understood - is neuronal innervation of lesions. Recent evidence demonstrates that the peripheral nervous system plays an important role in the pathophysiology of this disease. Sensory nerves, which surround and innervate endometriotic lesions, not only drive the chronic and debilitating pain associated with endometriosis but also contribute to a pro-growth phenotype by secreting neurotrophic factors and interacting with surrounding immune cells. The diverse array of contributions that neurons play in endometriosis indicate that it should be considered as a nerve-centric disease. This review is focused on the emerging field of exoneural biology and how it applies to the field of endometriosis, in particular the role that peripheral nerves play in driving and maintaining endometriotic lesions. A better understanding of the mechanisms of neuronal contribution to endometriosis, as well as their interactions with accompanying stromal and immune cells, will unearth novel disease-relevant pathways and targets, providing additional, more selective therapeutic horizons.

NLRP3 Inflammasome Activation of Mast Cells by Estrogen via the Nuclear-Initiated Signaling Pathway Contributes to the Development of Endometriosis

Endometriosis is an estrogen-dependent gynecological disease. The pathogenesis of endometriosis remains controversial, although it is generally accepted that the inflammatory immune response plays a crucial role in this process. Mast cells (MCs) are multifunctional innate immune cells that accumulate in endometriotic lesions. However, the molecular mechanism by which estrogen modulates MCs in the development of endometriosis is not well understood. Here we report that estrogen can induce the expression of NOD-like receptor family pyrin domain containing 3 (NLRP3) through estrogen receptor (ER)-α via the estrogen responsive element (ERE) in MCs. Such transcriptional regulation is necessary for the activation of NLRP3 inflammasome and the production of mature interleukin (IL)-1β in MCs. Targeted inhibition of NLRP3 significantly restrained lesion progression and fibrogenesis in a mouse model of endometriosis. Collectively, these findings suggest that MCs contribute to the development of endometriosis through NLRP3 inflammasome activation mediated by nuclear-initiated estrogen signaling pathway.

The Aryl hydrocarbon receptor mediates reproductive toxicity of polychlorinated biphenyl congener 126 in rats

Polychlorinated biphenyls (PCBs) are endocrine disrupting chemicals with documented, though mechanistically ill-defined, reproductive toxicity. The toxicity of dioxin-like PCBs, such as PCB126, is mediated via the aryl hydrocarbon receptor (AHR) in non-ovarian tissues. The goal of this study was to examine the uterine and ovarian effects of PCB126 and test the hypothesis that the AHR is required for PCB126-induced reproductive toxicity. Female Holzman-Sprague Dawley wild type (n = 14; WT) and Ahr knock out (n = 11; AHR-/-) rats received a single intraperitoneal injection of either corn oil vehicle (5 ml/kg: WT_O and AHR-/-_O) or PCB126 (1.63 mg/kg in corn oil: WT_PCB and AHR-/-_PCB) at four weeks of age. The estrous cycle was synchronized and ovary and uterus were collected 28 days after exposure. In WT rats, PCB126 exposure reduced (P < 0.05) body and ovary weight, uterine gland number, uterine area, progesterone, 17β-estradiol and anti-Müllerian hormone level, secondary and antral follicle and corpora lutea number but follicle stimulating hormone level increased (P < 0.05). In AHR-/- rats, PCB126 exposure increased (P ≤ 0.05) circulating luteinizing hormone level. Ovarian or uterine mRNA abundance of biotransformation, and inflammation genes were altered (P < 0.05) in WT rats due to PCB126 exposure. In AHR-/- rats, the transcriptional effects of PCB126 were restricted to reductions (P < 0.05) in three inflammatory genes. These findings support a functional role for AHR in the female reproductive tract, illustrate AHR's requirement in PCB126-induced reprotoxicity, and highlight the potential risk of dioxin-like compounds on female reproduction.

The Inflammatory Feed-Forward Loop Triggered by the Complement Component C3 as a Potential Target in Endometriosis

The complement system is a major component of humoral innate immunity, acting as a first line of defense against microbes via opsonization and lysis of pathogens. However, novel roles of the complement system in inflammatory and immunological processes, including in cancer, are emerging. Endometriosis (EM), a benign disease characterized by ectopic endometrial implants, shows certain unique features of cancer, such as the capacity to invade surrounding tissues, and in severe cases, metastatic properties. A defective immune surveillance against autologous tissue deposited in the peritoneal cavity allows immune escape for endometriotic lesions. There is evidence that the glandular epithelial cells found in endometriotic implants produce and secrete the complement component C3. Here, we show, using immunofluorescence and RT-qPCR, the presence of locally synthesized C3 in the ectopic endometriotic tissue, but not in the eutopic tissue. We generated a murine model of EM via injection of minced uterine tissue from a donor mouse into the peritoneum of recipient mice. The wild type mice showed greater amount of cyst formation in the peritoneum compared to C3 knock-out mice. Peritoneal washings from the wild type mice with EM showed more degranulated mast cells compared to C3 knock-out mice, consistent with higher C3a levels in the peritoneal fluid of EM patients. We provide evidence that C3a participates in an auto-amplifying loop leading to mast cell infiltration and activation, which is pathogenic in EM. Thus, C3 can be considered a marker of EM and its local synthesis can promote the engraftment of the endometriotic cysts.

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

BACKGROUND

Endometriosis is a refractory and recurrent disease and it affects nearly 10% of reproductive-aged women and 40% of infertile patients. The commonly accepted theory for endometriosis is retrograde menstruation where endometrial tissues invade into peritoneal cavity and fail to be cleared due to immune dysfunction. Therefore, the comprehensive understanding of immunologic microenvironment of peritoneal cavity deserves further investigation for the previous studies mainly focus on one or several immune cells.

RESULTS

High-quality transcriptomes were from peritoneal fluid samples of patients with endometriosis and control, and firstly subjected to 10 × genomics single-cell RNA-sequencing. We acquired the single-cell transcriptomes of 10,280 cells from endometriosis sample and 7250 cells from control sample with an average of approximately 63,000 reads per cell. A comprehensive map of overall cells in peritoneal fluid was first exhibited. We unveiled the heterogeneity of immune cells and discovered new cell subtypes including T cell receptor positive (TCR+) macrophages, proliferating macrophages and natural killer dendritic cells in peritoneal fluid, which was further verified by double immunofluorescence staining and flow cytometry. Pseudo-time analysis showed that the response of macrophages to the menstrual debris might follow the certain differentiation trajectory after endometrial tissues invaded into the peritoneal cavity, that is, from antigen presentation to pro-inflammation, then to chemotaxis and phagocytosis. Our analyses also mirrored the dysfunctions of immune cells including decreased phagocytosis and cytotoxic activity and elevated pro-inflammatory and chemotactic effects in endometriosis.

CONCLUSION

TCR+ macrophages, proliferating macrophages and natural killer dendritic cells are firstly reported in human peritoneal fluid. Our results also revealed that immune dysfunction happens in peritoneal fluid of endometriosis, which may be responsible for the residues of invaded menstrual debris. It provided a large-scale and high-dimensional characterization of peritoneal microenvironment and offered a useful resource for future development of immunotherapy.