Mast Cell Activation Research Articles

Inflammation-induced mast cell-derived nerve growth factor: a key player in chronic vulvar pain?

Provoked vulvodynia (PV) is characterized by localized chronic vulvar pain. It is associated with a history of recurrent inflammation, mast cell (MC) accumulation, and neuronal sprouting in the vulva. However, the mechanism of how vulvar-inflammation promotes neuronal sprouting and gene-expression adaptation in the spinal cord, leading to hypersensitivity and painful sensations, is unknown. Here, we found that vulvar tissue from women with PV (n=8) is characterized by MC accumulation and neuronal sprouting compared to women without PV (n=4). In addition, we observed these changes in an animal study of PV. Thus, we found that repeated vulvar zymosan-inflammation challenges lead to long-lasting mechanical and thermal vulvar hypersensitivity, which was mediated by MC accumulation, neuronal sprouting, overexpression of the pain channels (TRPV1 and TRPA1) in vulvar neurons, as well as a long-term increase of gene expression related to neuroplasticity, neuroinflammation, and nerve growth factor (NGF) in the spinal cord/DRG(L6-S3). However, regulation of the NGF pathway by stabilization of MC activity with ketotifen fumarate (KF) during vulvar inflammation attenuated the local increase of NGF and histamine, as well as the elevated transcription of pro-inflammatory cytokines, and NGF pathway in the spinal cord. Additionally, KF treatment during inflammation modulates MC accumulation, neuronal hyperinnervation, and overexpression of the TRPV1 and TRPA1 channels in the vulvar neurons, consequently preventing the development of vulvar pain. A thorough examination of the NGF pathway during inflammation revealed that blocking NGF activity by using an NGF-non-peptide-inhibitor (Ro08-2750) regulates the upregulation of genes related to neuroplasticity, and NGF pathway in the spinal cord, as well as modulates neuronal sprouting and overexpression of the pain channels, resulting in a reduced level of vulvar hypersensitivity. On the other hand, stimulation of the NGF pathway in the vulvar promotes neuronal sprouting, overexpression of pain channels, and increase of gene expression related to neuroplasticity, neuroinflammation, and NGF in the spinal cord, resulting in long-lasting vulvar hypersensitivity. In conclusion, our findings suggest that vulvar allodynia induced by inflammation is mediated by MC accumulation, neuronal sprouting, and neuromodulation in the vulvar. Additionally, chronic vulvar pain may involve a long-term adaptation in gene expression in the spinal cord, which probably plays a critical role in central sensitization and pain maintenance. Strikingly, regulating the NGF pathway during the critical period of inflammation prevents vulvar pain development via modulating the neuronal changes in the vestibule and spinal cord, suggesting a fundamental role for the NGF pathway in PV development.

Prevalence of type 2 inflammation in patients with chronic rhinosinusitis with nasal polyps in Saudi Arabia

BackgroundChronic Rhinosinusitis (CRS) is a common condition causing a significant worldwide burden, affecting 5%–12% of the general population. CRS is classified into type 2 and non-type 2 disease based on endotype dominance. Type 2 inflammation is distinguished by the presence of IL-4, IL-5, and IL-13 cytokines, along with eosinophil and mast cell activation and recruitment. Evidence of type 2 inflammation is ascertained by tissue eosinophil count >10/high-power field (HPF) or serum eosinophil >250 cells/mcL or total immunoglobulin E (IgE) > 100 IU/ml.ObjectivesTo investigate the prevalence and characteristics of type 2 inflammation in patients who presented with nasal polyps and underwent Endoscopic Sinus Surgery (ESS) in Saudi Arabia.DesignA retrospective cross-sectional Study.MethodsThis study was conducted among patients who presented with nasal polyps and underwent ESS at King Saud University Medical City (KSUMC) from 2015 to 2020. Patients with nasal/sinus diseases other than Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) were excluded. Demographic data, olfaction status, and co-morbidities were collected, and radiological images were evaluated. Type 2-CRS was determined by meeting at least one of three predictor criteria (blood eosinophils ≥250 cells/mcL, tissue eosinophils ≥10/HPF, or total IgE levels ≥100 IU/ml). Blood parameters and histopathologic analysis were obtained for each patient.ResultsOf the 381 patients included in the study, the prevalence of type 2-CRS, based on the EPOS2020 criteria, was 99.7% in our population. Among these patients, 47.5% had hyposmia, 38.8% had anosmia, and 13.6% had normal olfaction. The most prevalent co-morbidity was allergic rhinitis, followed by bronchial asthma.ConclusionThis study aimed to determine the prevalence of type 2 inflammation among patients Diagnosed with CRSwNP and underwent ESS in Saudi Arabia. The results showed a prevalence of 99.7%, indicating that almost all recorded patients with CRSwNP in our population had type 2 inflammation.

Relationships between systemic sclerosis and atherosclerosis: screening for mitochondria-related biomarkers

BackgroundPatients with systemic sclerosis (SSc) are known to have higher incidence of atherosclerosis (AS). Mitochondrial injuries in SSc can cause endothelial dysfunction, leading to AS; thus, mitochondria appear to be hubs linking SSc to AS. This study aimed to identify the mitochondria-related biomarkers of SSc and AS.MethodsWe identified common differentially expressed genes (DEGs) in the SSc (GSE58095) and AS (GSE100927) datasets of the Gene Expression Omnibus (GEO) database. Considering the intersection between genes with identical expression trends and mitochondrial genes, we used the least absolute shrinkage and selection operator (LASSO) as well as random forest (RF) algorithms to identify four mitochondria-related hub genes. Diagnostic nomograms were then constructed to predict the likelihood of SSc and AS. Next, we used the CIBERSORT algorithm to evaluate immune infiltration in both disorders, predicted the transcription factors for the hub genes, and validated these genes for the two datasets.ResultsA total of 112 genes and 13 mitochondria-related genes were identified; these genes were then significantly enriched for macrophage differentiation, collagen-containing extracellular matrix, collagen binding, antigen processing and presentation, leukocyte transendothelial migration, and apoptosis. Four mitochondria-related hub DEGs (IFI6, FSCN1, GAL, and SGCA) were also identified. The nomograms showed good diagnostic values for GSE58095 (area under the curve (AUC) = 0.903) and GSE100927 (AUC = 0.904). Further, memory B cells, γδT cells, M0 macrophages, and activated mast cells were significantly higher in AS, while the resting memory CD4+ T cells were lower and M1 macrophages were higher in SSc; all of these were closely linked to multiple immune cells. Gene set enrichment analysis (GSEA) showed that IFI6 and FSCN1 were involved in immune-related pathways in both AS and SSc; GAL and SGCA are related to mitochondrial metabolism pathways in both SSc and AS. Twenty transcription factors (TFs) were predicted, where two TFs, namely BRCA1 and PPARγ, were highly expressed in both SSc and AS.ConclusionFour mitochondria-related biomarkers were identified in both SSc and AS, which have high diagnostic value and are associated with immune cell infiltration in both disorders. Hence, this study provides new insights into the pathological mechanisms underlying SSc and AS. The specific roles and action mechanisms of these genes require further clinical validation in SSc patients with AS.

Nematode Galectin Inhibits Basophilic Leukaemia RBL-2H3 Cells Apoptosis in IgE-Mediated Activation.

Mast cells are essential immune cells involved in the host's defence against gastrointestinal nematodes. To evade the immune response, parasitic nematodes produce a variety of molecules. Galectin 1, produced by Teladorsagia circumcincta (Tci-gal-1), reduces mast cell degranulation and selectively regulates mediator production and release in an IgE-dependent manner. To uncover the activity of Tci-gal-1, we have examined the effect of the protein on gene expression, protein production, and apoptosis in activated basophilic leukaemia RBL-2H3 cells. Rat RBL-2H3 cells were activated with anti-DNP IgE and DNP-HSA, and then treated with Tci-gal-1. Microarray analysis was used to examine gene expression. The levels of several apoptosis-related molecules and cytokines were determined using antibody arrays and ELISA. Early and late apoptosis was evaluated cytometrically. Degranulation of cells was determined by a β-hexosaminidase release assay. Treatment of activated RBL-2H3 cells with Tci-gal-1 resulted in inhibited apoptosis and decreased degranulation, although we did not detect significant changes in gene expression. The production of pro-apoptotic molecules, receptor for advanced glycation end products (RAGE) and Fas ligand (FasL), and the cytokines IL-9, IL-10, IL-13, TNF-α, and IL-2 was strongly inhibited. Tci-gal-1 modulates apoptosis, degranulation, and production of cytokines by activated RBL-2H3 cells without detectable influence on gene transcription. This parasite protein is crucial for modulation of the protective immune response and the inhibition of chronic inflammation driven by mast cell activity.

Inhibition of Mast Cell Degranulation by Novel Small Molecule MRGPRX2 Antagonists

BackgroundMas-related G-protein coupled receptor X2 (MRGPRX2) is a promiscuous receptor on mast cells that mediates IgE-independent degranulation and has been implicated in multiple mast cell-mediated disorders, including chronic urticaria, atopic dermatitis, and pain disorders. Although it is a promising therapeutic target, few potent, selective, small molecule antagonists have been identified, and functional effects of human MRGPRX2 inhibition have not been evaluated in vivo. ObjectiveWe identified and characterized novel, potent, and selective orally active small molecule MRGPRX2 antagonists for potential treatment of mast cell-mediated disease. MethodsAntagonists were identified using multiple functional assays in cell lines overexpressing human MRGPRX2, LAD2 mast cells, human peripheral stem cell-derived mast cells, and isolated skin mast cells. Skin mast cell degranulation was evaluated in Mrgprb2em(-/-) knockout (KO) and Mrgprb2em(MRGPRX2) transgenic human MRGPRX2 knock-in (KI) mice by assessment of agonist-induced skin vascular permeability. Ex vivo skin mast cell degranulation and associated histamine release was evaluated by microdialysis of human skin tissue samples. ResultsMRGPRX2 antagonists potently inhibited agonist-induced MRGPRX2 activation and mast cell degranulation in all mast cell types tested, in an IgE-independent manner. Orally administered MRGPRX2 antagonists also inhibited agonist-induced degranulation and resulting vascular permeability in MRGPRX2 KI mice. In addition, antagonist treatment dose dependently inhibited agonist-induced degranulation in ex vivo human skin. ConclusionMRGPRX2 small molecule antagonists potently inhibited agonist-induced mast cell degranulation in vitro and in vivo as well as ex vivo in human skin, supporting potential therapeutic utility as a novel treatment for multiple human diseases involving clinically relevant mast cell activation.

Disulfidptosis-related Protein RPN1 may be a Novel Anti-osteoporosis Target of Kaempferol.

Osteoporosis (OP) is an age-related skeletal disease. Kaempferol can regulate bone mesenchymal stem cells (BMSCs) osteogenesis to improve OP, but its mechanism related to disulfidptosis, a newly discovered cell death mechanism, remains unclear. The study aimed to investigate the biological function and immune mechanism of disulfidptosis- related ribophorin I (RPN1) in OP and to experimentally confirm that RPN1 is the target for the treatment of OP with kaempferol. Differential expression analysis was conducted on disulfide-related genes extracted from the GSE56815 and GSE7158 datasets. Four machine learning algorithms identified disease signature genes, with RPN1 identified as a significant risk factor for OP through the nomogram. Validation of RPN1 differential expression in OP patients was performed using the GSE56116 dataset. The impact of RPN1 on immune alterations and biological processes was explored. Predictive ceRNA regulatory networks associated with RPN1 were generated via miRanda, miRDB, and TargetScan databases. Molecular docking estimated the binding model between kaempferol and RPN1. The targeting mechanism of kaempferol on RPN1 was confirmed through pathological HE staining and immunohistochemistry in ovariectomized (OVX) rats. RPN1 was abnormally overexpressed in the OP cohort, associated with TNF signaling, hematopoietic cell lineage, and NF-kappa B pathway. Immune infiltration analysis showed a positive correlation between RPN1 expression and CD8+ T cells and resting NK cells, while a negative correlation with CD4+ naive T cells, macrophage M1, T cell gamma delta, T cell follicular helper cells, activated mast cells, NK cells, and dendritic cells, was found. Four miRNAs and 17 lncRNAs associated with RPN1 were identified. Kaempferol exhibited high binding affinity (-7.2 kcal/mol) and good stability towards the RPN1. The experimental results verified that kaempferol could improve bone microstructure destruction and reverse the abnormally high expression of RPN1 in the femur of ovariectomized rats. RPN1 may be a new diagnostic biomarker in patients with OP, and may serve as a new target for kaempferol to improve OP.

Postpartum acute myometritis suppresses expression of contraction-associated proteins in the gravid uterus

Uterine atony is a major contributor to postpartum hemorrhage. We previously proposed the novel histological concept of postpartum acute myometritis (PAM) to elucidate the pathophysiology of uterine atony. This concept involves the infiltration of macrophages and neutrophils, as well as mast cell and complement activation in the myometrium. However, the pathological mechanism underlying uterine atony in the context of PAM remains unclear. Herein, we focused on uterine contraction-associated proteins (CAPs) including connexin 43 (Cx43), oxytocin receptors (OXR), prostaglandin receptors EP1, EP3, FP, and protease-activated receptor (PAR)-1. This follow-up study aimed to compare CAP expression between PAM and control groups. We selected 38 PAM subjects from the cases enrolled in our amniotic fluid embolism registry between 2011 and 2018. Control tissues from 10 parturients were collected during cesarean section. We stained the myometrial tissues with the following CAP markers, inflammatory cell markers, and other markers: Cx43, OXR, EP1, EP3, FP, PAR-1, C5a receptor, tryptase, neutrophil elastase, CD68, β-actin, and Na+/K+-ATPase. The immunostaining-positive areas of Cx43, OXR, EP1, EP3, and FP standardized by β-actin in the PAM tissue were significantly smaller than in the control group, whereas those of PAR-1 and Na+/K+-ATPase increased significantly in the PAM group. The Cx43- and OXR-positive areas correlated negatively with the immunostaining-positive cell numbers of CD68 and tryptase with halo, respectively. PAM may impair individual and synchronized myocyte contraction, leading to uterine atony refractory to uterotonics. Further cell-based studies are needed to elucidate the molecular mechanism by which inflammatory cells suppress CAP expression.

Peripheral mast cells derive the effects of acupuncture in Parkinson's disease.

This research investigates the peripheral mechanisms of acupuncture in treating Parkinson's disease (PD), a progressive neurodegenerative disorder marked by motor impairments. While the central mechanisms of acupuncture have been extensively studied, our focus lies in the peripheral mechanisms at the acupoints, the sites of acupuncture signal initiation. Employing a PD model, we analyzed the local responses to acupuncture stimulation at these points. Our key finding was a significant elevation in both the number and activity of mast cells (MCs) in the peripheral tissues following acupuncture. Intriguingly, pre-treatment with an MC stabilizer diminished the acupuncture's therapeutic effects on PD symptoms. Similarly, local anesthesia with lidocaine at the acupoints attenuated the symptom improvement typically observed with acupuncture. Meanwhile, the augmentation of MC activity induced by acupuncture was significantly impeded by cromolyn, an MC stabilizer, but remained unaffected by lidocaine. This finding suggests that MC activity is a more upstream regulator of acupuncture effects compared to nerve conduction. This study provides groundbreaking insights into the initiation and transmission of acupuncture signals, highlighting the significant role of peripheral MC modulation in PD treatment.

Identification of anoikis-related gene signatures and construction of the prognosis model in prostate cancer.

One of the primary reasons for tumor invasion and metastasis is anoikis resistance. Biochemical recurrence (BCR) of prostate cancer (PCa) serves as a harbinger of its distant metastasis. However, the role of anoikis in PCa biochemical recurrence has not been fully elucidated. Differential expression analysis was used to identify anoikis-related genes based on the TCGA and GeneCards databases. Prognostic models were constructed utilizing LASSO regression, univariate and multivariate Cox regression analyses. Moreover, Gene Expression Omnibus datasets (GSE70770 and GSE46602) were applied as validation cohorts. Gene Ontology, KEGG and GSVA were utilized to explore biological pathways and molecular mechanisms. Further, immune profiles were assessed using CIBERSORT, ssGSEA, and TIDE, while anti-cancer drugs sensitivity was analyzed by GDSC database. In addition, gene expressions in the model were examined using online databases (Human Protein Atlas and Tumor Immune Single-Cell Hub). 113 differentially expressed anoikis-related genes were found. Four genes (EEF1A2, RET, FOSL1, PCA3) were selected for constructing a prognostic model. Using the findings from the Cox regression analysis, we grouped patients into groups of high and low risk. The high-risk group exhibited a poorer prognosis, with a maximum AUC of 0.897. Moreover, larger percentage of immune infiltration of memory B cells, CD8 Tcells, neutrophils, and M1 macrophages were observed in the high-risk group than those in the low-risk group, whereas the percentage of activated mast cells and dendritic cells in the high-risk group were lower. An increased TIDE score was founded in the high-risk group, suggesting reduced effectiveness of ICI therapy. Additionally, the IC50 results for chemotherapy drugs indicated that the low-risk group was more sensitive to most of the drugs. Finally, the genes EEF1A2, RET, and FOSL1 were expressed in PCa cases based on HPA website. The TISCH database suggested that these four ARGs might contribute to the tumor microenvironment of PCa. We created a risk model utilizing four ARGs that effectively predicts the risk of BCR in PCa patients. This study lays the groundwork for risk stratification and predicting survival outcomes in PCa patients with BCR.

Mast cell activation syndrome: An up-to-date review of literature.

Mast cells are a subtype of white blood cells and are involved in the immune system. These cells contain many chemical substances called mediators, which are involved in the allergic response. The fact that mast cells play a role in many events that require urgent intervention, especially anaphylaxis, has led to a more detailed study of these cells. The diseases also caused by dysfunctions of mast cells have been examined in many circumstances. For instance, mast cell activation syndrome is known as an augmented number of cells due to decreased cell death, resulting in clinical symptoms affecting many systems. The main common symptoms include flushing, hypotension, urticaria, angioedema, headache, vomiting and diarrhea. Although the underlying mechanism is not yet clearly known, we aim to review the literature in a broad perspective and bring together the existing knowledge in the light of the literature due to the diversity of its involvement in the body and the fact that it is a little known syndrome.

Comprehensive Analysis of angiogenesis associated genes and tumor microenvironment infiltration characterization in cervical cancer

BackgroundCervical cancer is among the most prevalent malignancies worldwide. This study explores the relationships between angiogenesis-related genes (ARGs) and immune infiltration, and assesses their implications for the prognosis and treatment of cervical cancer. Additionally, it develops a diagnostic model based on angiogenesis-related differentially expressed genes (ARDEGs). MethodsWe systematically evaluated 15 ARDEGs using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Set Enrichment Analysis (GSEA), and Gene Set Variation Analysis (GSVA). Immune cell infiltration was assessed using a single-sample gene-set enrichment analysis (ssGSEA) algorithm. We then constructed a diagnostic model for ARDEGs using Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis and evaluated the diagnostic value of this model and the hub genes in predicting clinical outcomes and immunotherapy responses in cervical cancer. ResultsA set of ARDEGs was identified from the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and UCSC Xena database. We performed KEGG, GO, and GSEA analyses on these genes, revealing significant involvement in cell proliferation, differentiation, and apoptosis. The ARDEGs diagnostic model, constructed using LASSO regression analysis, showed high predictive accuracy in cervical cancer patients. We developed a reliable nomogram and decision curve analysis to evaluate the clinical utility of the ARDEG diagnostic model. The 15 ARDEGs in the model were associated with clinicopathological features, prognosis, and immune cell infiltration. Notably, ITGA5 expression and the abundance of immune cell infiltration (specifically mast cell activation) were highly correlated. ConclusionThis study identifies the prognostic characteristics of ARGs in cervical cancer patients, elucidating aspects of the tumor microenvironment. It enhances the predictive accuracy of immunotherapy outcomes and establishes new strategies for immunotherapeutic interventions.

The immune landscape of uterine fibroids as determined using mass cytometry

ObjectiveTo study the differences in immune cell profile in uterine fibroids (Fib) and matched myometrium (Myo). DesignObservational Study SettingLaboratory Study PatientsThe study included tissue that was collected from ten pairs of fibroid and matched myometrium from women, not on hormonal medications, undergoing hysterectomy and myomectomy. InterventionsNone Main Outcome MeasuresDifferences in immune cell and cytokine composition between fibroid and matched myometrium Result(s)The mass cytometry analysis indicated that fibroids had a significantly higher number of NK cells, total macrophages, M2 macrophages, and conventional dendritic cells when compared to matched myometrium from the same patient. In contrast, fibroids had significantly fewer CD3 and CD4 T cells when compared to myometrium. The mass cytometry analysis did not show any significant difference in the number of resting mast cells. IFC and IHC imaging confirmed the CytoF results, showing a significantly higher (p<0.05) number of NK, tryptase-positive mast cells indicative of mast cell activation, total macrophage, and M2 cells in Fibroids and a significantly lower (p<0.05) number of CD3 and CD4 T cells. The cytokine assay revealed significantly increased (p<0.05) levels of IFNA2, Il-1α, and PDGF-AA and significantly lower levels of M-CSF and IL-1RA in Fib. ConclusionOur results show significant differences in immune cell populations and cytokine levels between Fib and Myo. There was a significant increase in total number of macrophages, M2 macrophages, NK cells, and dendritic cells and a significant decrease in CD3 and CD4 T cells in Fib. IHC confirmed no differences in total resting mast cell count, but a significant increase in tryptase-positive mast cells in Fib. Fibs also expressed significantly higher levels of IFNA2, IL-1α, and PDGF-AA and significantly lower levels of IL-1RA and M-CSF as compared with matched myometrium. These findings provide a foundation for further studies exploring the role of immune cells in Fib development.

Discovery of core genes and intercellular communication role in osteosarcoma.

Osteosarcoma is a primary malignant bone tumor that affects children and young adults. Understanding the molecular mechanisms underlying osteosarcoma is critical to develop effective treatments. This study aimed to identify core genes and explore the role of intercellular communication in osteosarcoma. We used GSE87437 and GSE152048 dataset to conduct a weighted correlation network analysis (WGCNA) and identify co-expression modules. The enriched biological processes and cellular components of the genes in the steelblue module were analyzed. Next, we explored the expression, diagnostic value, correlation, and association with immune infiltrate of CCSER1 and LOC101929154. Finally, we utilized CIBERSORT algorithm to predict the infiltrated immune cells in osteosarcoma tissues. Our results identified 44 co-expression modules, and the steelblue module was mainly associated with axon development, axonogenesis, and innervation. CCSER1 and LOC101929154 were significantly upregulated in osteosarcoma tissues with poor response to preoperative chemotherapy. Moreover, the expressions of CCSER1 and LOC101929154 were positively correlated. The area under the receiver operating characteristic curve of CCSER1 and LOC101929154 was 0.800 and 0.773, respectively. The expression of CCSER1 was negatively correlated with follicular helper T cells and positively correlated with M0 macrophages, while LOC101929154 was negatively correlated with activated mast cells. Besides, CD4 memory-activated T cells were observed at lower levels in patients who responded well to chemotherapy. Our study identified core genes CCSER1 and LOC101929154 and provided insight into the intercellular communication profile in osteosarcoma. Our results suggested that targeting CCSER1, LOC101929154, and CD4 memory-activated T cells may be a promising strategy for the treatment of osteosarcoma.

Aging promotes mast cell activation and antigen presenting capacity in atherosclerosis

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation Aging is an independent and dominant risk factor for atherosclerosis and is associated with a low-grade chronic inflammation termed inflammaging. This age-induced pro-inflammatory environment may have great impact on plaque-residing immune cells, including mast cells. Mast cells have been found to accumulate in the human atherosclerotic plaque upon disease progression and have been associated with plaque instability. However, it is currently unknown whether aging drives the pro-atherogenic effects of mast cells in atherosclerosis. To assess the effects of aging on mast cell phenotype, we examined mast cell populations in young and old male Ldlr-/- mice fed either a chow (CD) or Western-type (WD) diet. We observed a 6-fold increase in the number of mast cells in the aged atherosclerotic aorta compared to young (Y-CD: 4.5±0.7 vs. O-CD: 279.4±9 cells, p&amp;lt;0.01; Y-WD: 45.3±15.2 vs. O-CD: 279.4±9 cells, p&amp;lt;0.01). Furthermore, we detected a marked increase in activation status with age as shown by the significantly augmented number of CD63+ mast cells in the atherosclerotic aorta (Y-CD: 1.8±0.6 vs. O-CD: 259.7±85.4 cells, p&amp;lt;0.01; Y-WD: 41.3±13.6 vs. O-CD: 259.7±85.4 cells, p&amp;lt;0.01). In line, we identified that aged bone-marrow derived mast cells displayed elevated basal CD63 expression compared to young cells, indicative of intrinsic low-grade activation. Moreover, we demonstrated that aging increases the amount of MHCII+ mast cells in atherosclerosis, allowing them to act as antigen-presenting cells, which correspondingly led to increased CD4+ T cell proliferation in vitro (young: 35.2±1.2% vs. old: 45.8±1.2%, p&amp;lt;0.001). Finally, single-cell RNA sequencing of human atherosclerotic plaques confirmed mast cell-specific expression of MHC-II orthologs. To conclude, we established that aging induces phenotypic changes of mast cells in atherosclerosis, regarding both activation status and antigen presenting capacity, which can contribute to disease progression.

PACAP38/mast-cell-specific receptor axis mediates repetitive stress-induced headache in mice.

Pain, an evolutionarily conserved warning system, lets us recognize threats and motivates us to adapt to those threats. Headache pain from migraine affects approximately 15% of the global population. However, the identity of any putative threat that migraine or headache warns us to avoid is unknown because migraine pathogenesis is poorly understood. Here, we show that a stress-induced increase in pituitary adenylate cyclase-activating polypeptide-38 (PACAP38), known as an initiator of allosteric load inducing unbalanced homeostasis, causes headache-like behaviour in male mice via mas-related G protein-coupled receptor B2 (MrgprB2) in mast cells. The repetitive stress model and dural injection of PACAP38 were performed to induce headache behaviours. We assessed headache behaviours using the facial von Frey test and the grimace scale in wild-type and MrgprB2-deficient mice. We further examined the activities of trigeminal ganglion neurons using in vivo Pirt-GCaMP Ca2+ imaging of intact trigeminal ganglion (TG). Repetitive stress and dural injection of PACAP38 induced MrgprB2-dependent headache behaviours. Blood levels of PACAP38 were increased after repetitive stress. PACAP38/MrgprB2-induced mast cell degranulation sensitizes the trigeminovascular system in dura mater. Moreover, using in vivo intact TG Pirt-GCaMP Ca2+ imaging, we show that stress or/and elevation of PACAP38 sensitized the TG neurons via MrgprB2. MrgprB2-deficient mice showed no sensitization of TG neurons or mast cell activation. We found that repetitive stress and dural injection of PACAP38 induced headache behaviour through TNF-a and TRPV1 pathways. Our findings highlight the PACAP38-MrgprB2 pathway as a new target for the treatment of stress-related migraine headache. Furthermore, our results pertaining to stress interoception via the MrgprB2/PACAP38 axis suggests that migraine headache warns us of stress-induced homeostatic imbalance.

Phenylacetic acid, an anti-vaginitis metabolite produced by the vaginal symbiotic bacterium Chryseobacterium gleum

The human microbiome contains genetic information that regulates metabolic processes in response to host health and disease. While acidic vaginal pH is maintained in normal conditions, the pH level increases in infectious vaginitis. We propose that this change in the vaginal environment triggers the biosynthesis of anti-vaginitis metabolites. Gene expression levels of Chryseobacterium gleum, a vaginal symbiotic bacterium, were found to be affected by pH changes. The distinctive difference in the metabolic profiles between two C. gleum cultures incubated under acidic and neutral pH conditions was suggested to be an anti-vaginitis molecule, which was identified as phenylacetic acid (PAA) by spectroscopic data analysis. The antimicrobial activity of PAA was evaluated in vitro, showing greater toxicity toward Gardnerella vaginalis and Candida albicans, two major vaginal pathogens, relative to commensal Lactobacillus spp. The activation of myeloperoxidase, prostaglandin E2, and nuclear factor-κB, and the expression of cyclooxygenase-2 were reduced by an intravaginal administration of PAA in the vaginitis mouse model. In addition, PAA displayed the downregulation of mast cell activation. Therefore, PAA was suggested to be a messenger molecule that mediates interactions between the human microbiome and vaginal health.

Multi-omic integration reveals alterations in nasal mucosal biology that mediate air pollutant effects on allergic rhinitis.

Allergic rhinitis is a common inflammatory condition of the nasal mucosa that imposes a considerable health burden. Air pollution has been observed to increase the risk of developing allergic rhinitis. We addressed the hypotheses that early life exposure to air toxics is associated with developing allergic rhinitis, and that these effects are mediated by DNA methylation and gene expression in the nasal mucosa. In a case-control cohort of 505 participants, we geocoded participants' early life exposure to air toxics using data from the US Environmental Protection Agency, assessed physician diagnosis of allergic rhinitis by questionnaire, and collected nasal brushings for whole-genome DNA methylation and transcriptome profiling. We then performed a series of analyses including differential expression, Mendelian randomization, and causal mediation analyses to characterize relationships between early life air toxics, nasal DNA methylation, nasal gene expression, and allergic rhinitis. Among the 505 participants, 275 had allergic rhinitis. The mean age of the participants was 16.4 years (standard deviation = 9.5 years). Early life exposure to air toxics such as acrylic acid, phosphine, antimony compounds, and benzyl chloride was associated with developing allergic rhinitis. These air toxics exerted their effects by altering the nasal DNA methylation and nasal gene expression levels of genes involved in respiratory ciliary function, mast cell activation, pro-inflammatory TGF-β1 signaling, and the regulation of myeloid immune cell function. Our results expand the range of air pollutants implicated in allergic rhinitis and shed light on their underlying biological mechanisms in nasal mucosa.

Bioinformatics identification and validation of maternal blood biomarkers and immune cell infiltration in preeclampsia: An observational study.

Preeclampsia (PE) is a pregnancy complication characterized by placental dysfunction. However, the relationship between maternal blood markers and PE is unclear. It is helpful to improve the diagnosis and treatment of PE using new biomarkers related to PE in the blood. Three PE-related microarray datasets were obtained from the Gene Expression Synthesis database. The limma software package was used to identify differentially expressed genes (DEGs) between PE and control groups. Least absolute shrinkage and selection operator regression, support vector machine, random forest, and multivariate logistic regression analyses were used to determine key diagnostic biomarkers, which were verified using clinical samples. Subsequently, functional enrichment analysis was performed. In addition, the datasets were combined for immune cell infiltration analysis and to determine their relationships with core diagnostic biomarkers. The diagnostic performance of key genes was evaluated using the receiver operating characteristic (ROC) curve, C-index, and GiViTi calibration band. Genes with potential clinical applications were evaluated using decision curve analysis (DCA). Seventeen DEGs were identified, and 6 key genes (FN1, MYADM, CA6, PADI4, SLC4A10, and PPP4R1L) were obtained using 3 types of machine learning methods and logistic regression. High diagnostic performance was found for PE through evaluation of the ROC, C-index, GiViti calibration band, and DCA. The 2 types of immune cells (M0 macrophages and activated mast cells) were significantly different between patients with PE and controls. All of these genes except SLC4A10 showed significant differences in expression levels between the 2 groups using quantitative reverse transcription-polymerase chain reaction. This model used 6 maternal blood markers to predict the occurrence of PE. The findings may stimulate ideas for the treatment and prevention of PE.

Kamebakaurin Suppresses Antigen-Induced Mast Cell Activation by Inhibition of FcεRI Signaling Pathway

Introduction: Kamebakaurin is an active constituent of both Rabdosia japonica and Rabdosia excisa, which are utilized in Chinese traditional medicine for improving symptoms in patients with allergies. We investigated the molecular mechanisms of the anti-allergic effects of kamebakaurin using BMMCs. Methods: The degranulation ratio, histamine release, and the interleukin (IL)-4, leukotriene B4 (LTB4), and cysteinyl leukotriene productions on antigen-triggered BMMC were investigated. Additionally, the effects of kamebakaurin on signal transduction proteins were examined by Western blot and binding to the Syk and Lyn kinase domain was calculated. The effects of kamebakaurin on antigen-induced hyperpermeability were investigated using mouse model. Results: At 10 μm, kamebakaurin partially inhibited degranulation, histamine release, and IL-4 production. At 30 μm, kamebakaurin partially reduced LTB4 and cysteinyl leukotriene productions and suppressed degranulation, histamine release, and IL-4 production. Phosphorylation of both Syk Y519/520 and its downstream protein, Gab2, was reduced by kamebakaurin, and complete inhibition was observed with 30 μm kamebakaurin. In contrast, phosphorylation of Erk was only partially inhibited, even in the presence of 30 μm kamebakaurin. Syk Y519/520 is known to be auto-phosphorylated via intramolecular ATP present in its own ATP-binding site, and this auto-phosphorylation triggers degranulation, histamine release, and IL-4 production. Docking simulation study indicated kamebakaurin blocked ATP binding to the ATP-binding site in Syk. Therefore, inhibition of Syk auto-phosphorylation by kamebakaurin binding to the Syk ATP-binding site appeared to cause a reduction of histamine release and IL-4 production. Kamebakaurin inhibited antigen-induced vascular hyperpermeability in a dose-dependent fashion but did not reduce histamine-induced vascular hyperpermeability. Conclusion: Kamebakaurin ameliorates allergic symptoms via inhibition of Syk phosphorylation; thus, kamebakaurin could be a lead compound for the new anti-allergic drug.

Aspalathin, a Primary Rooibos Flavonoid, Alleviates Mast Cell-Mediated Allergic Inflammation by the Inhibition of FcεRI Signaling Pathway.

Mast cells are primary cells initiating allergic inflammation by the release of various allergic mediators, such as histamine and pro-inflammatory cytokines. Aspalathin (ASP) is the predominant flavonoid found exclusively in rooibos, an herb that has been traditionally used in allergy relief therapy. In the present study, we investigated the beneficial effects of ASP on mast cell-mediated allergic inflammation. For in vivo study, two well-known mast cell-mediated local and systemic allergic inflammation mouse models were used: passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis mouse models (ASA). Oral administration of ASP dose-dependently suppressed immunoglobulin (Ig)E-mediated PCA responses evidenced by Evans blue extravasation, ear thickening, and mast cell degranulation. ASP also significantly mitigated ovalbumin-induced ASA responses, including hypothermia, histamine secretion, and the production of IgE and interleukin-4. Notably, ASP was more effective in suppressing allergic inflammation than nothofagin, another prominent flavonoid known as an anti-allergic component of rooibos. The regulatory mechanism of mast cell activation by ASP was clarified using mast cell line and primary cultured mast cells (RBL-2H3 and mouse bone marrow-derived mast cells). ASP reduced IgE-stimulated mast cells degranulation and intracellular calcium influx by the inhibition of FcεRI signaling pathway (Lyn, Fyn, and Syk). Moreover, ASP reduced pro-inflammatory cytokine expressions by inhibiting two major transcription factors, nuclear factor of activated T cells and nuclear factor-κB. Collectively, we proposed that ASP could be a potential therapeutic candidate for the treatment of mast cell-mediated allergic inflammatory diseases.