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

Unmasking the NLRP3 inflammasome in dendritic cells as a potential therapeutic target for autoimmunity, cancer, and infectious conditions

Proper and functional immune response requires a complex interaction between innate and adaptive immune cells, which dendritic cells (DCs) are the primary actors in this coordination as professional antigen-presenting cells. DCs are armed with numerous pattern recognition receptors (PRRs) such as nucleotide-binding and oligomerization domain-like receptors (NLRs) like NLRP3, which influence the development of their activation state upon sensation of ligands. NLRP3 is a crucial component of the immune system for protection against tumors and infectious agents, because its activation leads to the assembly of inflammasomes that cause the formation of active caspase-1 and stimulate the maturation and release of proinflammatory cytokines. But, when NLRP3 becomes overactivated, it plays a pathogenic role in the progression of several autoimmune disorders. So, NLRP3 activation is strictly regulated by diverse signaling pathways that are mentioned in detail in this review. Furthermore, the role of NLRP3 in all of the diverse immune cells' subsets is briefly mentioned in this study because NLRP3 plays a pivotal role in modulating other immune cells which are accompanied by DCs' responses and subsequently influence differentiation of T cells to diverse T helper subsets and even impact on cytotoxic CD8+ T cells' responses. This review sheds light on the functional and therapeutic role of NLRP3 in DCs and its contribution to the occurrence and progression of autoimmune disorders, prevention of diverse tumors' development, and recognition and annihilation of various infectious agents. Furthermore, we highlight NLRP3 targeting potential for improving DC-based immunotherapeutic approaches, to be used for the benefit of patients suffering from these disorders.

The IL-33-ST2 axis plays a vital role in endometriosis via promoting epithelial-mesenchymal transition by phosphorylating β-catenin

OBJECTIVES

Interleukin 33 (IL-33) is a crucial inflammatory factor that functions as an alarm signal in endometriosis (EMs). Epithelial-mesenchymal transition (EMT), a process related to inflammatory signals, intracellular reactive oxygen species (ROS) production, and lipid peroxidation, have been proposed as potential mechanisms that contribute to the development and progression of EMs. IL-33 is highly upregulated in the ectopic milieu. Moreover, ectopic endometrial cells constitutively express interleukin-33 receptor ST2 (IL-33R). However, the role of IL-33/ST2 in the EMT of EMs remains largely unknown. In this study, we aimed to mechanistically determine the role of IL-33/ST2 in EMs-associated fibrosis.

MATERIALS AND METHODS

We established a non-lethal oxidative stress model to explore the conditions that trigger IL-33 induction. We performed α-smooth muscle actin (α-SMA) protein detection, cell counting kit-8 (CCK-8) assays, and scratch assays to analyze the impact of IL-33 on primary endometrial stromal cells (ESCs) proliferation and invasion. Clinical samples from patients with or without EMs were subjected to immunohistochemical (IHC) and and immunofluorescence(IF) staining to assess the clinical relevance of IL-33 receptor ST2 and EMT-related proteins. Furthermore, we used the ectopic human endometrial epithelial cell line 12Z and normal human epithelial cell line EEC to evaluate the effects of IL-33 on Wnt/β-catenin signaling. The effect of IL-33 on EMT-associated fibrosis was validated in vivo by intraperitoneal injections of IL-33 and antiST2.

RESULTS

We observed that ectopic milieu, characterized by ROS, TGF-β1, and high level of estrogen, triggers the secretion of IL-33 from ectopic ESCs. Ectopic endometrial lesions exhibited higher level of fibrotic characteristics and ST2 expression than that in the normal endometrium. Exogenous recombinant human (rhIL-33) enhanced ESC migration and survival. Similarly, 12Z cells displayed a higher degree of EMT characteristics with elevated expression of CCN4 and Fra-1, downstream target genes of the WNT/β-catenin pathway, than that observed in EECs. Conversely, blocking IL-33 with neutralizing antibodies, knocking down ST2 or β-catenin with siRNA, and β-catenin dephosphorylation abolished its effects on EMT promotion. In vivo validation demonstrated that IL-33 significantly promotes EMs-related fibrosis through the activation of Wnt/β-catenin signaling.

CONCLUSION

Our data strongly support the vital role of the IL-33/ST2 pathway in EMs-associated fibrosis and emphasize the importance of the EMT in the pathophysiology of fibrosis. Targeting the IL-33/ST2/Wnt/β-catenin axis may hold promise as a feasible therapeutic approach for controlling fibrosis in EMs.

Lack of Annexin A1 Exacerbates Inflammatory Response in Acute Endometritis Model

Annexin A1 (AnxA1) is a glucocorticoid-inducible protein and an important endogenous modulator of inflammation. However, its effect in the endometrial microenvironment is poorly explained. This study aimed to evaluate the role of endogenous AnxA1 in an endometritis mouse model induced by lipopolysaccharide (LPS). Female C57BL/6 wild-type (WT) and AnxA1-/- mice were divided into two groups: SHAM and LPS. To induce endometritis, mice received a vaginal infusion of 50 μL of LPS (1 mg/mL) dissolved in phosphate-buffered saline. After 24 h, the mice were euthanized, and blood and uteri samples were collected. The endometrium inflammatory scores were significantly increased in the LPS-treated group. AnxA1-/- mice from the LPS group demonstrated a significant increase in the number of degranulated mast cell levels compared to AnxA1-/- SHAM mice. The Western blotting analysis revealed that a lack of AnxA1 promoted the upregulation of NLRP3 and pro-IL-1β in the acute endometritis animal model compared to WT LPS animals. LPS-induced endometritis increased the number of blood peripheral leukocytes in both WT and AnxA1-/- mice compared with SHAM group mice (p < 0.001). AnxA1-/- mice also showed increased plasma levels of IL-1β (p < 0.01), IL-6, IL-10, IL-17, and TNF-α (p < 0.05) following LPS-induced endometritis. In conclusion, a lack of endogenous AnxA1 exacerbated the inflammatory response in an endometritis model via NLRP3 dysregulation, increased uterine mast cell activation, and plasma pro-inflammatory cytokine release.

Emerging bacterial factors for understanding pathogenesis of endometriosis

The pathogenesis of endometriosis is a complex process, and recent research has introduced novel hypotheses in this field. This review summarizes recent studies on the pathogenesis of endometriosis. We focused on several classical hypotheses, as well as their interactions with the microenvironment of hormonal dependence and immunosuppression. Furthermore, we highlighted the emergence of bacterial factors associated with endometriosis. Recent advances in next-generation sequencing (NGS) have revealed the presence and detailed distribution of these bacteria as well as the involvement of specific bacteria in pathogenesis. These factors alter the microenvironment in the early stages of endometriosis development, leading to lesion formation. Understanding the mechanisms underlying the early development of endometriosis from a new perspective would be helpful for the development of novel therapeutic agents for endometriosis.

Estrogen plays an important role by influencing the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is an important part of the natural immune system that plays an important role in many diseases. Estrogen is a sex hormone that plays an important role in controlling reproduction and regulates many physiological and pathological processes. Recent studies have indicated that estrogen is associated with disease progression. Estrogen can ameliorate some diseases (e. g, sepsis, mood disturbances, cerebral ischemia, some hepatopathy, Parkinson's disease, amyotrophic lateral sclerosis, inflammatory bowel disease, spinal cord injury, multiple sclerosis, myocardial ischemia/reperfusion injury, osteoarthritis, and renal fibrosis) by inhibiting the NLRP3 inflammasome. Estrogen can also promote the development of diseases (e.g., ovarian endometriosis, dry eye disease, and systemic lupus erythematosus) by upregulating the NLRP3 inflammasome. In addition, estrogen has a dual effect on the development of cancers and asthma. However, the mechanism of these effects is not summarized. This article reviewed the progress in understanding the effects of estrogen on the NLRP3 inflammasome and its mechanisms in recent years to provide a theoretical basis for an in-depth study.

Alloferon-1 ameliorates estrogen deficiency-induced osteoporosis through dampening the NLRP3/caspase-1/IL-1β/IL-18 signaling pathway

Alloferon-1 is an insect polypeptide that has anti-inflammatory, antitumor and antiviral activity. This study aimed to determine the effects of alloferon-1 on estrogen deficiency-induced osteoporosis and explore the associated mechanism using a murine model of ovariectomy (OVX)-induced osteoporosis. Results showed that alloferon-1 prevented ovariectomy‑induced body weight gain, bone loss and bone mineral content reduction, affected biochemical markers of bone turnover, and restored the microstructure of bone trabeculae. Moreover, alloferon-1 suppressed the expression of the ovariectomy‑mediated inflammatory cytokines in the vertebrae bone tissues, including nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3), cysteinyl aspartate specific proteinase-1 (Caspase-1), interleukin 1β (IL-1β) and interleukin 18 (IL-18) which were determined by immunofluorescence staining and western blot. Overall, the present study provides evidence for the effectiveness of alloferon-1 against estrogen deficiency-induced osteoporosis, suggesting an alternative drug or an auxiliary modulator for the treatment of postmenopausal osteoporosis (PMOP).

Role of the NLRP3 inflammasome in gynecological disease

The NLR family pyrin domain containing 3 (NLRP3) inflammasome is involved in the innate immune system and is a three-part macromolecular complex comprising the NLRP3 protein, apoptosis-associated speck-like protein containing a CARD (ASC) and the cysteine protease pro-caspase-1. When the NLRP3 inflammasome is activated, it can produce interleukin (IL)- 1β and IL-18 and eventually lead to inflammatory cell pyroptosis. Related studies have demonstrated that the NLRP3 inflammasome can induce an immune response and is related to the occurrence and development of gynecological diseases, such as endometriosis, polycystic ovary syndrome and breast cancer. NLRP3 inflammasome inhibitors are beneficial for maintaining cellular homeostasis and tissue health and have been found effective in targeting some gynecological diseases. However, excessive inhibitor concentrations have been found to cause adverse effects. Therefore, proper control of NLRP3 inflammasome activity is critical. This paper summarizes the structure and function of the NLRP3 inflammasome and highlights the therapeutic potential of targeting it in gynecological diseases, such as endometriosis, polycystic ovary syndrome and breast cancer The application of NLRP3 inflammasome inhibitors is also discussed.

RORα overexpression reduced interleukin-33 expression and prevented mast cell degranulation and inflammation by inducing autophagy in allergic rhinitis

BACKGROUND

Retinoid acid receptor related orphan receptor α (RORα) is a nuclear receptor that along with other bioactive factors regulates cell proliferation, differentiation, and immunomodulation in vivo.

AIMS

The objective of this study was to explore the function and mechanism of RORα in allergic rhinitis (AR).

MATERIALS AND METHODS

Derp1 was used to construct an AR cell model in HNEpC cells, and RORα was overexpressed or silenced in the AR HNEpC cells. Next, LAD2 cells were co-cultured with the Derp1-treated HNEpC cells. Additionally, an AR mouse model was established using by OVA, and a RORα Adenovirus was delivered by nebulizing. Pathological tissue structures were evaluated by hematoxylin-eosin staining, and the levels of RORα, interleukin-33 (IL-33), and other proteins were analyzed immunohistochemistry, western blotting, and immunofluorescence staining. IL-33, IL-4, IL-5, and IL-13 levels were detected using enzyme-linked immunosorbent assay kits and cell migration was assessed by Transwell assays.

RESULTS

Our data showed that RORα was downregulated in the nasal mucosa tissues of AR patients. Derp1 treatment could cause a downregulation of RORα, upregulation of IL-33, the induction of NLRP3 inflammasomes, and cell migration in HNEpC cells. Furthermore, RORα overexpression dramatically attenuated IL-33 levels, NLRP3 inflammasome activity, and the migration of AR HNEpC cells induced with Derp1. Moreover, RORα in AR HNEpC cells could prevent mast cell (MC) degranulation and inflammation by accelerating autophagy, RORα overexpression inhibited MC degranulation and NLRP3-induced inflammation in the AR model mice. RORα overexpression reduced IL-33 expression in nasal epithelial cells, and also suppressed MC degranulation and inflammation by promoting autophagy.

CONCLUSION

RORα inhibits NLRP3 inflammasome in HNEpC, and attenuated mast cells degranulation and inflammation through autophagy in AR.

Inflammasomes in human reproductive diseases

Inflammasomes are multi-protein complexes localized within immune and non-immune cells that induce caspase activation, proinflammatory cytokine secretion, and ultimately pyroptosis-a type of cell death. Inflammasomes are involved in a variety of human diseases, especially acute or chronic inflammatory diseases. In this review, we focused on the strong correlation between the NLRP3 inflammasome and various reproductive diseases, including ovarian aging or premature ovarian insufficiency, PCOS, endometriosis, recurrent spontaneous abortion, preterm labor, pre-eclampsia, and male subfertility, as well as the multifaceted role of NLRP3 in the pathogenesis and treatment of these diseases. In addition, we provide an overview of the structure and amplification of inflammasomes. This comprehensive review demonstrates the vital role of NLRP3 inflammasome activation in human reproductive diseases together with the underlying mechanisms, offers new insights for mechanistic studies of reproduction, and provides promising possibilities for the development of drugs targeting the NLRP3 inflammasome for the treatment of reproductive disorders in the future.

The Role of NLRP3 in Regulation of Antimicrobial Peptides and Estrogen Signaling in UPEC-Infected Bladder Epithelial Cells

The NLRP3 inflammasome, estrogen and antimicrobial peptides have all been found to have a vital role in the protection of the bladder urothelium. However, the interdependence between these protective factors during a bladder infection is currently unknown. Our aim was to investigate the role of NLRP3 in the regulation of antimicrobial peptides and estrogen signaling in bladder epithelial cells during a UPEC infection. Human bladder epithelial cells and CRISPR/Cas9-generated NLRP3-deficient cells were stimulated with the UPEC strain CFT073 and estradiol. The gene and protein expression were evaluated with microarray, qRT-PCR, western blot and ELISA. Microarray results showed that the expression of most antimicrobial peptides was reduced in CFT073-infected NLRP3-deficient cells compared to Cas9 control cells. Conditioned medium from NLRP3-deficient cells also lost the ability to suppress CFT073 growth. Moreover, NLRP3-deficient cells had lower basal release of Beta-defensin-1, Beta-defensin-2 and RNase7. The ability of estradiol to induce an increased expression of antimicrobial peptides was also abrogated in NLRP3-deficient cells. The decreased antimicrobial peptide expression might be linked to the observed reduced expression and activity of estradiol receptor beta in NLRP3-deficient cells. This study suggests that NLRP3 may regulate the release and expression of antimicrobial peptides and affect estrogen signaling in bladder epithelial cells.

Rab27b promotes endometriosis by enhancing invasiveness of ESCs and promoting angiogenesis

PROBLEM

Endometriosis (EMS) is an estrogen-dependent disease which is characterized with estrogen-dependent growth of ectopic endometrium and increased local estrogen production. EMS performs tumor-like biological functions such as invasiveness and angiogenesis. Rab27b is a member of the Rab family of GTPases, which is strongly associated with the growth, invasion and metastasis of a variety of tumors. However, little is known about the function of Rab27b in EMS. In this study, we intended to investigate the impact of Rab27b and its downstream molecule in the development of EMS.

METHOD OF STUDY

Normal endometrium and endometriotic lesions were collected to investigate the expression levels of Rab27b. Then, ESCs were transfected with Rab27b siRNA. We analyzed the influence of Rab27b on the proliferation and invasive activity of ESCs. Conditioned media harvested from Rab27b siRNA-treated ESCs were used to treat HUVECs. HUVEC Tube formation and ELISA were performed to explored the interactions between ESCs and HUVEC. In addition, ESCs were treated with different concentrations of estrogen. Based on biological database predictions, we explored possible mechanisms through which estrogen regulates the expression of Rab27b.

RESULTS

The expressions of Rab27b were significantly higher in endometriotic lesions than that in normal endometrium. Rab27b can promote the cell proliferation, migration and invasion of ESCs. The elevated expression of Rab27b, on the one hand, promotes the secretion of MMP9 and increases the invasiveness of ESCs. On the other hand, Rab27b may play a key role in the communication between ESC and endothelial cells, by simulating VEGF secretion and neovascularization. Besides, estrogen upregulated phosphorylated FOXO1 levels in ectopic ESCs, resulting in the promotion of Rab27b expression levels.

CONCLUSION

Rab27b plays a key role in the development of EMS, which may provide new insights into the pathogenesis of EMS. Our findings may also contribute to the development of therapeutic interventions for EMS.

Cell type-specific roles of NLRP3, inflammasome-dependent and -independent, in host defense, sterile necroinflammation, tissue repair, and fibrosis

The NLRP3 inflammasome transforms a wide variety of infectious and non-infectious danger signals that activate pro-inflammatory caspases, which promote the secretion of IL-1β and IL-18, and pyroptosis, a pro-inflammatory form of cell necrosis. Most published evidence documents the presence and importance of the NLRP3 inflammasome in monocytes, macrophages, and neutrophils during host defense and sterile forms of inflammation. In contrast, in numerous unbiased data sets, NLRP3 inflammasome-related transcripts are absent in non-immune cells. However, an increasing number of studies report the presence and functionality of the NLRP3 inflammasome in almost every cell type. Here, we take a closer look at the reported cell type-specific expression of the NLRP3 inflammasome components, review the reported inflammasome-dependent and -independent functions, and discuss possible explanations for this discrepancy.

NLRP3 inflammasome-mediated Pyroptosis induce Notch signal activation in endometriosis angiogenesis

Endometriosis is characterized by the presence of endometrial tissue outside the uterus that not only causes severe pelvic pain and infertility but also increased risk for ovarian carcinogenesis in women of reproductive age. Here, we found that angiogenesis was increased and accompanied with up-regulation of Notch1 in human endometriotic tissue sample, which is associated with pyroptosis induced by activation of endothelial NLRP3 inflammasome. Further, in endometriosis model induced in wild type and NLRP3-deficient (NLRP3-KO) mice, we found that deficiency of NLRP3 suppressing the development of endometriosis. In vitro, inhibiting the activation of NLRP3 inflammasome prevents LPS/ATP-induced tube formation in endothelial cells. Meanwhile, knockdown NLRP3 expression by gRNA disrupt the interaction between NICD and HIF-1α under the inflammatory microenvironment. This study demonstrates that activation of NLRP3 inflammasome-mediated pyroptosis affects angiogenesis in endometriosis via Notch1-dependent manner.

Research advances in endometriosis-related signaling pathways: A review

Endometriosis (EM) is characterized by the existence of endometrial mucosa outside the uterine cavity, which causesinfertility, persistent aches, and a decline in women's quality of life. Both hormone therapies and nonhormone therapies, such as NSAIDs, are ineffective, generic categories of EM drugs. Endometriosis is a benign gynecological condition, yet it shares a number of features with cancer cells, including immune evasion, survival, adhesion, invasion, and angiogenesis. Several endometriosis-related signaling pathways are comprehensively reviewed in this article, including E2, NF-κB, MAPK, ERK, PI3K/Akt/mTOR, YAP, Wnt/β-catenin, Rho/ROCK, TGF-β, VEGF, NO, iron, cytokines and chemokines. To find and develop novel medications for the treatment of EM, it is essential to implicitly determine the molecular pathways that are disordered during EM development. Additionally, research on the shared pathways between EM and tumors can provide hypotheses or suggestions for endometriosis therapeutic targets.

Rescuing fertility during COVID-19 infection: exploring potential pharmacological and natural therapeutic approaches for comorbidity, by focusing on NLRP3 inflammasome mechanism

The respiratory system was primarily considered the only organ affected by Coronavirus disease 2019 (COVID-19). As the pandemic continues, there is an increasing concern from the scientific community about the future effects of the virus on male and female reproductive organs, infertility, and, most significantly, its impact on the future generation. The general presumption is that if the primary clinical symptoms of COVID-19 are not controlled, we will face several challenges, including compromised infertility, infection-exposed cryopreserved germ cells or embryos, and health complications in future generations, likely connected to the COVID-19 infections of parents and ancestors. In this review article, we dedicatedly studied severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) virology, its receptors, and the effect of the virus to induce the activation of inflammasome as the main arm of the innate immune response. Among inflammasomes, nucleotide oligomerization domain-like receptor protein, pyrin domain containing 3 (NLRP3) inflammasome pathway activation is partly responsible for the inflicted damages in both COVID-19 infection and some reproductive disorders, so the main focus of the discussion is on NLRP3 inflammasome in the pathogenesis of COVID-19 infection alongside in the reproductive biology. In addition, the potential effects of the virus on male and female gonad functions were discussed, and we further explored the potential natural and pharmacological therapeutic approaches for comorbidity via NLRP3 inflammasome neutralization to develop a hypothesis for averting the long-term repercussions of COVID-19. Since activation of the NLRP3 inflammasome pathway contributes to the damage caused by COVID-19 infection and some reproductive disorders, NLRP3 inflammasome inhibitors have a great potential to be considered candidates for alleviating the pathological effects of the COVID-19 infection on the germ cells and reproductive tissues. This would impede the subsequent massive wave of infertility that may threaten the patients.

Upregulation of HTRA1 mediated by the lncRNA NEAT1/miR-141-3p axis contributes to endometriosis development through activating NLRP3 inflammasome-mediated pyroptotic cell death and cellular inflammation

The present study identified a novel upstream long chain non-coding (lncRNA) NEAT1/miR-141-3p/HTRA1 axis that regulated the activation of NLR family pyrin domain containing 3 (NLRP3) inflammasome to modulate endometriosis (EM) development. Specifically, clinical data suggested that the expression of NLRP3 and apoptosis-associated speck-like protein containing CARD (ASC), the cleavage of caspase-1 and gasdermin D (GSDMD), and the production of inflammatory cytokines (interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-18) were all significantly increased in the ectopic endometrium (EE) tissues, compared to the normal endometrium (NE) tissues. Then, through analyzing the datasets from GEO database (GSE2339, GSE58178, and GSE7305) using the GEO2R bioinformatics tools, we verified that HtrA Serine Peptidase 1 (HTRA1) was especially enriched in the EE tissues compared to the NE tissues. To further confirm the biological functions of HTRA1, HTRA1 was overexpressed or downregulated in primary human endometrial stromal cells (hESCs) isolated from NE tissues or EE tissues, respectively. The results showed that upregulation of HTRA1 activated NLRP3 inflammasome-mediated pyroptotic cell death and cellular inflammation in NE-derived hESCs, whereas silencing of HTRA1 played an opposite role in EE-derived hESCs. In addition, the lncRNA NEAT1/miR-141-3p axis was screened as the upstream regulator of HTRA1. Mechanistically, lncRNA NEAT1 sponged miR-141-3p to positively regulate HTRA1 in a competing endogenous RNA (ceRNA) mechanisms-dependent manner. The recovery experiments in hESCs from NE and EE tissues confirmed that lncRNA NEAT1 overexpression promoted NLRP3 inflammasome-mediated pyroptotic cell death through regulating the miR-141-3p/HTRA1 axis. Taken together, this study firstly uncovered the underlying mechanisms by which a novel lncRNA NEAT1/miR-141-3p/HTRA1-NLRP3 pathway contributed to the development of EM, which provided novel diagnostic and therapeutic biomarkers for this disease.

Fisetin, a Natural Polyphenol, Ameliorates Endometriosis Modulating Mast Cells Derived NLRP-3 Inflammasome Pathway and Oxidative Stress

A chronic, painful, and inflammatory condition known as endometriosis is defined by the extra-uterine development of endometrial tissue. The aim of this study was to evaluate the beneficial effects of fisetin, a naturally occurring polyphenol that is frequently present in a variety of fruits and vegetables. Uterine fragments were injected intraperitoneally to cause endometriosis, and fisetin was given orally every day. At 14 days of treatment, laparotomy was performed, and the endometrial implants and peritoneal fluids were collected for histological, biochemical, and molecular analyses. Rats subjected to endometriosis presented important macroscopic and microscopic changes, increased mast cell (MC) infiltration, and fibrosis. Fisetin treatment reduced endometriotic implant area, diameter, and volumes, as well as histological alterations, neutrophil infiltration, cytokines release, the number of MCs together with the expression of chymase and tryptase, and diminished α smooth muscle actin (α-sma) and transforming growth factor beta (TGF β) expressions. In addition, fisetin was able to reduce markers of oxidative stress as well as nitrotyrosine and Poly ADP ribose expressions and increase apoptosis in endometrial lesions. In conclusion, fisetin could represent a new therapeutic strategy to control endometriosis perhaps by targeting the MC-derived NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome pathway and oxidative stress.

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.

Pattern-recognition receptors in endometriosis: A narrative review

Endometriosis is closely associated with ectopic focal inflammation and immunosuppressive microenvironment. Multiple types of pattern recognition receptors (PRRs) are present in the innate immune system, which are able to detect pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) in both intracellular and external environments. However, the exact role of PRRs in endometriosis and the underlying molecular mechanism are unclear. PRRs are necessary for the innate immune system to identify and destroy invasive foreign infectious agents. Mammals mainly have two types of microbial recognition systems. The first one consists of the membrane-bound receptors, such as toll-like receptors (TLRs), which recognize extracellular microorganisms and activate intracellular signals to stimulate immune responses. The second one consists of the intracellular PRRs, including nod-like receptors (NLRs) and antiviral proteins retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA-5) with helix enzyme domain. In this review, we mainly focus on the key role of PRRs in the pathological processes associated with endometriosis. PRRs recognize PAMPs and can distinguish pathogenic microorganisms from self, triggering receptor ligand reaction followed by the stimulation of host immune response. Activated immune response promotes the transmission of microbial infection signals to the cells. As endometriosis is characterized by dysregulated inflammation and immune response, PRRs may potentially be involved in the activation of endometriosis-associated inflammation and immune disorders. Toll-like receptor 2 (TLR2), toll-like receptor 3 (TLR3), toll-like receptor 4 (TLR4), nod-like receptor family caspase activation and recruitment domain (CARD) domain containing 5 (NLRC5), nod-like receptor family pyrin domain containing 3 (NLRP3), and c-type lectin receptors (CLRs) play essential roles in endometriosis development by regulating immune and inflammatory responses. Absent in melanoma 2 (AIM2)-like receptors (ALRs) and retinoic acid-inducible gene I-like receptors (RLRs) may be involved in the activation of endometriosis-associated immune and inflammation disorders. PRRs, especially TLRs, may serve as potential therapeutic targets for alleviating pain in endometriosis patients. PRRs and their ligands interact with the innate immune system to enhance inflammation in the stromal cells during endometriosis. Thus, targeting PRRs and their new synthetic ligands may provide new therapeutic options 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.

Interferon Signaling in the Endometrium and in Endometriosis

Endometriosis is an estrogen-dependent inflammatory disease that develops in reproductive-aged women who experience pelvic pain and infertility. Even though endometriosis is not a new disease, its molecular etiology has not been clearly elucidated. Defects in the immune system might be one of the factors that promote endometriosis progression. For example, elevated levels of proinflammatory cytokines are associated with endometriosis. Interferon is one of the cytokines that is elevated in endometriotic tissues compared with normal endometrium. Therefore, high interferon levels play a crucial role in endometriosis progression. In addition to endometriosis, however, interferon has a critical role in endometrial function, particularly in the initiation and maintenance of pregnancy. Therefore, this review describes the double-edged sword of interferon signaling in normal endometrial function versus endometriosis progression and also discusses interferon targeting as a new nonhormonal therapy for endometriosis. This approach may increase the efficacy of endometriosis treatment and reduce the adverse effects associated with current hormonal therapy for this disease.

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.

The NLRP3 Inflammasome Inhibitor Dapansutrile Attenuates Cyclophosphamide-Induced Interstitial Cystitis

Interstitial cystitis (IC)/bladder pain syndrome (BPS), hereafter referred together as IC, is a clinical syndrome characterized by sterile inflammation in the bladder. While the etiology and pathophysiology of IC remain unclear, it may involve autoimmunity in light of the significant role played by the NLRP3 inflammasome. However, the effect of NLRP3 inhibitors including dapansutrile (Dap) on IC had not been explored previously. Here, we investigated the effect of Dap in the cyclophosphamide (CYP)-induced experimental mouse model of IC, which results in functional and histological alterations confined to the urinary bladder (UB) comparable to that of clinical IC. CYP-induced mice treated with Dap exhibited improved UB pathology and reductions in inflammation scores and the frequency and the number of mast cells and neutrophils, relative to mice that received CYP alone. Dap- and CYP-treated mice also exhibited infiltration of T cells in the spleen and iliac lymph nodes (ILNs) and a concurrent significant decrease (p<0.01) in CXCR3⁺CD8⁺ T cells in the UB, induction of systemic and mucosal dendritic cells (DCs), and reduced levels of systemic proinflammatory cytokines, as compared to CYP alone. We also observed decreases in the expression of several signaling pathways regulators, including interleukin-1 beta (IL-1β), NLRP3, caspase-1, nuclear factor kappa B (NF-κB), and inducible nitric oxide synthase (iNOS) in the UB of CYP- and Dap-treated mice, relative to those receiving CYP alone. Taken together, these results suggest that Dap suppresses IC through the reduction of CXCR3⁺T cells, mast cells, and neutrophils in the UB and induces DCs as a protective measure. The present study identifies the mechanisms underlying the amelioration of IC by the NLRP3 inhibitor Dap and may provide an avenue for a potential therapeutic agent for the treatment of IC.

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.

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.

Fibroblast growth factor receptor 2 promotes the proliferation, migration, and invasion of ectopic stromal cells via activation of extracellular-signal-regulated kinase signaling pathway in endometriosis

Endometriosis is defined as the presence of endometrial tissues with cancer-like features in extrauterine locations. Fibroblast growth factor receptor 2 (FGFR2) is a tyrosine kinase that is involved in cancer pathogenesis. This study aimed to determine the role of FGFR2 in endometriosis. A total of 29 pairs of ectopic and eutopic endometrial tissues were collected from women with endometriosis. Endometrial tissues from women with hysteromyomas were considered as normal controls. Primary ectopic stromal cells (ESCs) were isolated from the ectopic endometrium. The role of FGFR2 in ESCs was assessed using immunohistochemistry, polymerase chain reaction, cell counting kit-8 assay, EdU staining, flow cytometry, transwell assay, and western blotting. The following signaling pathways were detected using bioinformatic analysis and confirmed in vitro. By searching the GSE171154, GSE86543, and GSE77182 datasets, FGFR2 was identified as an upregulated overlapping gene in endometriosis. Compared to eutopic and normal endometria, FGFR2 was highly expressed in ectopic tissues. Transfection of primary ESCs with FGFR2 small interfering RNA (siRNA) repressed the viability and proliferation of cells and induced apoptosis. FGFR2 siRNA inhibited the migration, invasion, and transforming growth factor-β1-triggered epithelial-mesenchymal transition (EMT). Extracellular signal-regulated kinase (ERK) signaling was found to be a downstream signaling pathway for FGFR2. The ERK1/2 inhibitor PD98059 was found to reverse the promoting effects of FGFR2 on ESC proliferation and invasion. FGFR2 silencing effectively inhibited the growth, migration, invasion, and EMT of ESCs. The effects of FGFR2 on endometriosis might be mediated via the activation of ERK signaling.

Integrated Bioinformatics and Validation Reveal IL1B and Its Related Molecules as Potential Biomarkers in Chronic Spontaneous Urticaria

Background

The etiopathogenesis of chronic spontaneous urticaria (CSU) has not been fully understood, and there has been extensive interest in the interaction between inflammatory dermatosis and pyroptosis. This study intends to investigate the molecular mechanism of pyroptosis-related genes in CSU via bioinformatic ways, aiming at identifying the potential key biomarker.

Methods

GSE72540, the RNA expression profile dataset of CSU, was utilized as the training set, and GSE57178 as the validation set. Differently expressed pyroptosis-related genes (DEPRGs), GO, KEGG, and DO analyses were performed. The hub genes were explored by the protein–protein interaction analysis. Moreover, CIBERSORT was employed for estimating immune cell types and proportions. Then, we constructed a DEmRNA–miRNA–DElncRNA ceRNA network and a drug–gene interaction network. Finally, ELISA was used for gene expression analysis.

Results

We recognized 17 DEPRGs, whose enrichment analyses showed that they were mostly enriched in inflammatory response and immunomodulation. Moreover, 5 hub genes (IL1B, TNF, and IRF1 are upregulated, HMGB1 and P2RX7 are downregulated) were identified via the PPI network and verified by a validation set. Then immune infiltration analysis displayed that compared with normal tissue, CSU owned a significantly higher proportion of mast cells activated, but a lower proportion of T cells CD4 naive and so on. Furthermore, IL1B was statistically and positively associated with mast cells activated in CSU, and SNHG3, the upstream factor of IL1B in the ceRNA we constructed, also related with mast cells in CSU. Further analysis exhibited that the protein subcellular localization of IL1B was extracellular, according with its intercellular regulation role; IL1B was significantly correlated with key immune checkpoints; and the NOD-like receptor signaling pathway was the mainly involved pathway of IL1B based on the couple databases. What is more, the result of ELISA of CSU patients was the same as the above analyses about IL1B. In addition, the drug–gene interaction network contained 15 potential therapeutic drugs targeting IL1B, and molecular docking might make this relationship viable.

Conclusion

IL1B and its related molecules might play a key role in the development of CSU and could be potential biomarkers in CSU.