The mast cells - Cytokines axis in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disturbance, diagnosed in early childhood. It is associated with varying degrees of dysfunctional communication and social skills, repetitive and stereotypic behaviors. Regardless of the constant increase in the number of diagnosed patients, there are still no established treatment schemes in global practice. Many children with ASD have allergic symptoms, often in the absence of mast cell (MC) positive tests. Activation of MCs may release molecules related to inflammation and neurotoxicity, which contribute to the pathogenesis of ASD. The aim of the present paper is to enrich the current knowledge regarding the relationship between MCs and ASD by providing PPI network analysis-based data that reveal key molecules and immune pathways associated with MCs in the pathogenesis of autism. Network and enrichment analyzes were performed using receptor information and secreted molecules from activated MCs identified in ASD patients. Our analyses revealed cytokines and key marker molecules for MCs degranulation, molecular pathways of key mediators released during cell degranulation, as well as various receptors. Understanding the relationship between ASD and the activation of MCs, as well as the involved molecules and interactions, is important for elucidating the pathogenesis of ASD and developing effective future treatments for autistic patients by discovering new therapeutic target molecules.

Role of Mast Cells in Eosinophilic Gastrointestinal Diseases

Mast cells play a central role in the pathogenesis of eosinophilic gastrointestinal disorders (EGIDs), including eosinophilic esophagitis. Their interactions with immune and structural cells, involvement in tissue remodeling, and contribution to symptoms make them attractive targets for therapeutic intervention. More is being discovered regarding the intricate interplay of mast cells and eosinophils. Recent studies demonstrating that depletion of eosinophils is insufficient to improve symptoms of EGIDs have raised the question of whether other cells may play a role in symptomatology and pathogenesis of EGIDs.

PGR-KITLG signaling drives a tumor-mast cell regulatory feedback to modulate apoptosis of breast cancer cells

The immune microenvironment constructed by tumor-infiltrating immune cells and the molecular phenotype defined by hormone receptors (HRs) have been implicated as decisive factors in the regulation of breast cancer (BC) progression. Here, we found that the infiltration of mast cells (MCs) informed impaired prognoses in HR(+) BC but predicted improved prognoses in HR(-) BC. However, molecular features of MCs in different BC remain unclear. We next discovered that HR(-) BC cells were prone to apoptosis under the stimulation of MCs, whereas HR(+) BC cells exerted anti-apoptotic effects. Mechanistically, in HR(+) BC, the KIT ligand (KITLG), a major mast cell growth factor in recruiting and activating MCs, could be transcriptionally upregulated by the progesterone receptor (PGR), and elevate the production of MC-derived granulin (GRN). GRN attenuates TNFα-induced apoptosis in BC cells by competitively binding to TNFR1. Furthermore, disruption of PGR-KITLG signaling by knocking down PGR or using the specific KITLG-cKIT inhibitor iSCK03 potently enhanced the sensitivity of HR(+) BC cells to MC-induced apoptosis and exerted anti-tumor activity. Collectively, these results demonstrate that PGR-KITLG signaling in BC cells preferentially induces GRN expression in MCs to exert anti-apoptotic effects, with potential value in developing precision medicine approaches for diagnosis and treatment.

Xin-Yi-Qing-Fei-Tang and its critical components reduce asthma symptoms by suppressing GM-CSF and COX-2 expression in RBL-2H3 cells

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine (TCM) XYQFT is composed of 10 herbs. According to the NHIRD, XYQFT is one of the top ten most commonly used TCM prescriptions for asthma treatment.

AIM OF THE STUDY

The aim of this study was to explore whether XYQFT reduces asthma symptoms in a mouse model of chronic asthma and determine the immunomodulatory mechanism of mast cells.

MATERIALS AND METHODS

BALB/c mice were intratracheally (it) stimulated with 40 μL (2.5 μg/μL) of Dermatophagoides pteronyssinus (Der p) once a week for 6 consecutive weeks and orally administered XYQFT at 1 g/kg 30 min before Der p stimulation. Airway hypersensitivity, inflammatory cells in the BALF and total IgE in the blood were assessed in mice. In addition, RBL-2H3 cells (mast cells) were stimulated with DNP-IgE, after which different concentrations of XYQFT were added for 30 min to evaluate the effect of XYQFT on the gene expression and degranulation of DNP-stimulated RBL-2H3 cells. After the compounds in XYQFT were identified using LC‒MS/MS, the PBD method was used to identify the chemical components that inhibited the expression of the GM-CSF and COX-2 genes in mast cells.

RESULTS

The airway hypersensitivity assay demonstrated that XYQFT significantly alleviated Der p-induced airway hypersensitivity. Moreover, cell counting and typing of bronchoalveolar lavage fluid revealed a significant reduction in Der p-induced inflammatory cell infiltration with XYQFT treatment. ELISA examination further indicated a significant decrease in Der p-induced total IgE levels in serum following XYQFT administration. In addition, XYQFT inhibited the degranulation and expression of genes (IL-3, IL-4, ALOX-5, IL-13, GM-CSF, COX-2, TNF-α, and MCP-1) in RBL-2H3 cells after DNP stimulation. The compounds timosaponin AIII and genkwanin in XYQFT were found to be key factors in the inhibition of COX-2 and GM-CSF gene expression in mast cells.

CONCLUSION

By regulating mast cells, XYQFT inhibited inflammatory cell infiltration, airway hypersensitivity and specific immunity in a mouse model of asthma. In addition, XYQFT synergistically inhibited the expression of the GM-CSF and COX-2 genes in mast cells through timosaponin AIII and genkwanin.

Recruitment or activation of mast cells in the liver aggravates the accumulation of fibrosis in carbon tetrachloride-induced liver injury

Liver diseases caused by viral infections, alcoholism, drugs, or chemical poisons are a significant health problem: Liver diseases are a leading contributor to mortality, with approximately 2 million deaths per year worldwide. Liver fibrosis, as a common liver disease characterized by excessive collagen deposition, is associated with high morbidity and mortality, and there is no effective treatment. Numerous studies have shown that the accumulation of mast cells (MCs) in the liver is closely associated with liver injury caused by a variety of factors. This study investigated the relationship between MCs and carbon tetrachloride (CCl4)-induced liver fibrosis in rats and the effects of the MC stabilizers sodium cromoglycate (SGC) and ketotifen (KET) on CCl4-induced liver fibrosis. The results showed that MCs were recruited or activated during CCl4-induced liver fibrosis. Coadministration of SCG or KET alleviated the liver fibrosis by decreasing SCF/c-kit expression, inhibiting the TGF-β1/Smad2/3 pathway, depressing the HIF-1a/VEGF pathway, activating Nrf2/HO-1 pathway, and increasing the hepatic levels of GSH, GSH-Px, and GR, thereby reducing hepatic oxidative stress. Collectively, recruitment or activation of MCs is linked to liver fibrosis and the stabilization of MCs may provide a new approach to the prevention of liver fibrosis.

Bioinformatics analysis revealed underlying molecular mechanisms associated with asthma severity and identified GABAergic related pathway as a potential therapy for Th2-high endotype asthma

Background

Asthma, a principally T helper 2 (Th2) cell mediated immunological disease, is categorized into Th2-high and Th2-low endotypes. The influence of these endotypes on clinical characteristics and treatment responsiveness in asthma is yet to be completely understood. This study delves into the underlying molecular mechanisms of Th2 endotypes on asthma.

Methods

Transcriptomics data of airway epithelial and corresponding clinical information were sourced from the GEO. The co-expression modules were established by WGCNA. Cytoscape was applied to construct PPI networks, and hub genes were determined via the Cytohubba plugin. Additionally, a functional enrichment analysis was conducted on the co-expressed genes from the relevant modules. The relative abundances levels of 22 different types of immune cells in asthma patients were evaluated by CIBERSORT algorithm.

Results

There were 471 genes in the pink module significantly correlated with Th2 endotype. Overall, 151 DEGs were identified in the various Th2 endotypes, and 66 were obtained through intersection with the pink module. In the PPI network, the ten most important genes that regulate Th2 endotypes were selected as hub genes. In Th2-high endotype asthma, the hub genes were significantly related to γ-aminobutyric acid (GABA) pathways, indicating that hub genes can mainly regulate Th2-high endotype asthma through GABAergic system.

Conclusions

The severity of asthma is influenced by different Th2 endotypes. GABAergic related hub genes may provide innovative insights for the treatment of Th2-high asthma.

β1 integrin-mediated mast cell immune-surveillance of blood vessel content

BACKGROUND

Immunoglobulin E, IgE)-mediated degranulation of mast cells, MCs) provides rapid protection against environmental hazards, including animal venoms. A fraction of tissue-resident MCs intimately associates with blood vessels. These perivascular MCs were reported to extend projections into the vessel lumen and to be the first MCs to acquire intravenously injected IgE, suggesting that IgE loading of MCs depends on their vascular association.

OBJECTIVE

We sought to elucidate the molecular basis of the MC-blood vessel interaction and to determine its relevance for IgE-mediated immune responses.

METHODS

We selectively inactivated the Itgb1 gene, encoding the β1 chain of integrin adhesion molecules, ITGB1; in MCs by conditional gene targeting in mice. We analyzed skin MCs for blood vessel association, surface IgE density, capability to bind circulating antibody specific for MC surface molecules, as well as in vivo responses to antigen administered via different routes.

RESULTS

Lack of ITGB1 expression severely compromised MC blood vessel association. ITGB1-deficient MCs showed normal densities of surface IgE but reduced binding of intravenously injected antibodies. While their capacity to degranulate in response to IgE ligation in vivo was unimpaired, anaphylactic responses to antigen circulating in the vasculature were largely abolished.

CONCLUSION

ITGB1-mediated association of MCs with blood vessels is key for MC immune-surveillance of blood vessel content, but is dispensable for slow steady-state loading of endogenous IgE onto tissue-resident MCs.

Quercetin and Kaempferol inhibit HMC-1 activation via SOCE/NFATc2 signaling and suppress hippocampal mast cell activation in lipopolysaccharide-induced depressive mice

OBJECTIVE AND DESIGN

Mast cells (MCs), as the fastest immune responders, play a critical role in the progression of neuroinflammation-related diseases, especially in depression. Quercetin (Que) and kaempferol (Kae), as two major diet-derived flavonoids, inhibit MC activation and exhibit significant antidepressant effect due to their anti-inflammatory capacity. The study aimed to explore the mechanisms of inhibitory effect of Que and Kae on MC activation, and whether Que and Kae suppress hippocampal mast cell activation in LPS-induced depressive mice.

SUBJECTS AND TREATMENT

In vitro assays, human mast cells (HMC-1) were pretreated with Que or Kae for 1 h, then stimulated by phorbol 12-myristate 13-acetate (PMA) and 2,5-di-t-butyl-1,4-benzohydroquinone (tBHQ) for 3 h or 12 h. In vivo assays, Que or Kae was administered by oral gavage once daily for 14 days and then lipopolysaccharide (LPS) intraperitoneally injection to induce depressive behaviors.

METHODS

The secretion and expression of TNF-α were determined by ELISA and Western blotting. The nuclear factor of activated T cells (NFAT) transcriptional activity was measured in HMC-1 stably expressing NFAT luciferase reporter gene. Nuclear translocation of NFATc2 was detected by nuclear protein extraction and also was fluorescently detected in HMC-1 stably expressing eGFP-NFATc2. We used Ca2+ imaging to evaluate changes of store-operated calcium entry (SOCE) in HMC-1 stably expressing fluorescent Ca2+ indicator jGCamP7s. Molecular docking was used to assess interaction between the Que or Kae and calcium release-activated calcium modulator (ORAI). The  hippocampal mast cell accumulation and activation  were detected by toluidine blue staining and immunohistochemistry with β-tryptase.

RESULTS

In vitro assays of HMC-1 activated by PtBHQ (PMA and tBHQ), Que and Kae significantly decreased expression and secretion of TNF-α. Moreover, NFAT transcriptional activity and nuclear translocation of NFATc2 were remarkably inhibited by Que and Kae. In addition, the Ca2+ influx mediated by SOCE was suppressed by Que, Kae and the YM58483 (ORAI inhibitor), respectively. Importantly, the combination of YM58483 with Que or Kae had no additive effect on the inhibition of SOCE. The molecular docking also showed that Que and Kae both exhibit high binding affinities with ORAI at the same binding site as YM58483. In vivo assays, Que and Kae significantly reversed LPS-induced depression-like behaviors in mice, and inhibited hippocampal mast cell activation  in LPS-induced depressive mice.

CONCLUSIONS

Our results indicated that suppression of SOCE/NFATc2 pathway-mediated by ORAI channels may be the mechanism of inhibitory effect of Que and Kae on MC activation, and also suggested Que and Kae may exert the antidepressant effect through suppressing hippocampal mast cell activation.

Luteolin Is More Potent than Cromolyn in Their Ability to Inhibit Mediator Release from Cultured Human Mast Cells

INTRODUCTION

Mast cells are known for their involvement in allergic reactions but also in inflammatory reactions via secretion of numerous pro-inflammatory chemokines, cytokines, and enzymes. Drug development has focused on antiproliferative therapy for systemic mastocytosis and not on inhibitors of mast cell activation. The only drug available as a "mast cell blocker" is disodium cromoglycate (cromolyn), but it is poorly absorbed after oral administration, is a weak inhibitor of histamine release from human mast cells, and it develops rapid anaphylaxis. Instead, certain natural flavonoids, especially luteolin, can inhibit mast cell activation.

METHODS

Here, we compared pretreatment (0-120 min) with equimolar concentration (effective dose for 50% inhibition = 100 mm for inhibition of histamine release by cromolyn) of cromolyn and luteolin on release of mediators from the cultured human LADR mast cell line stimulated either by immunoglobulin E (IgE) and anti-IgE or with IL-33.

RESULTS

We show that luteolin is significantly more potent than cromolyn inhibiting release of histamine, tryptase, metalloproteinase-9, and vascular endothelial growth factor. Moreover, while luteolin also significantly inhibited release of IL-1β, IL-6, and IL-8 (CXCL8) and TNF, cromolyn had no effect.

CONCLUSION

These findings support the use of luteolin, especially in liposomal form to increase oral absorption, may be a useful alternative to cromolyn.

Bergapten inhibits airway inflammation and MRGPRX2-mediated mast cells activation by targeting NR4A1

Asthma is a serious global health problem affecting 300 million persons around the world. Mast cells (MCs) play a major role in airway hyperresponsiveness (AHR) and inflammation in asthma, their exact effector mechanisms remain unclear. Here, we aim to investigate the inhibitory effect of Bergapten (BER) on MRGPRX2-mediated MCs activation through asthma model. Mouse model of asthma was established to examine the anti-asthmatic effects of BER. Calcium (Ca2+) influx, β-hexosaminidase and histamine release were used to assess MCs degranulation in vitro. RNA-Seq technique was conducted to study the gene expression profile. RT-PCR and Western Blotting were performed to examine targeting molecules expression. BER inhibited AHR, inflammation, mucous secretion, collagen deposition and lung MCs activation in asthma model. BER dramatically reduced levels of IL4, IL-5, and IL-13 in bronchoalveolar lavage fluid (BALF), as well as inflammatory cells. BER also reduced serum IgE levels. Pretreatment MCs with BER inhibited substance P (SP)-induced Ca2+ influx, degranulation and cytokines release from MCs. BER also reduced the phosphorylation levels of PKC, PLC, IP3R, AKT and ERK, which were induced by SP. Furthermore, RNA-seq analysis showed that SP up-regulated 68 genes in MCs, while were reversed by BER. Among these 68 genes, SP up-regulated NR4A1 expression, and this effect was inhibited by BER. Meanwhile, knockdown of NR4A1 significantly attenuated SP-induced MCs degranulation. In conclusion, NR4A1 plays a major role in MRGPRX2-mediated MCs activation, BER inhibited AHR and inflammation in asthmatic model by inhibiting MCs activation through MRGPRX2-NR4A1 pathway.

N-benzyl-N-methyldecan-1-amine, derived from garlic, and its derivative alleviate 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in mice

Given the intricate etiology and pathogenesis of atopic dermatitis (AD), the complete cure of AD remains challenging. This study aimed to investigate if topically applying N-benzyl-N-methyldecan-1-amine (BMDA), derived from garlic, and its derivative [decyl-(4-methoxy-benzyl)-methyl-1-amine] (DMMA) could effectively alleviate AD-like skin lesions in 2,4-dinitrochlorobenzene (DNCB)-treated mice. Administering these compounds to the irritated skin of DNCB-treated mice significantly reduced swelling, rash, and excoriation severity, alongside a corresponding decrease in inflamed epidermis and dermis. Moreover, they inhibited spleen and lymph node enlargement and showed fewer infiltrated mast cells in the epidermis and dermis through toluidine-blue staining. Additionally, they led to a lower IgE titer in mouse sera as determined by ELISA, compared to vehicle treatment. Analyzing skin tissue from the mice revealed decreased transcript levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6), IL-4, iNOS, and COX-2, compared to control mice. Simultaneously, the compounds impeded the activation of inflammation-related signaling molecules such as JNK, p38 MAPK, and NF-κB in the mouse skin. In summary, these findings suggest that BMDA and DMMA hold the potential to be developed as a novel treatment for healing inflammatory AD.

A microbially produced AhR ligand promotes a Tph1-driven tolerogenic program in multiple sclerosis

Multiple sclerosis is a debilitating autoimmune disease, characterized by chronic inflammation of the central nervous system. While the significance of the gut microbiome on multiple sclerosis pathogenesis is established, the underlining mechanisms are unknown. We found that serum levels of the microbial postbiotic tryptophan metabolite indole-3-carboxaldehyde (3-IAld) inversely correlated with disease duration in multiple sclerosis patients. Much like the host-derived tryptophan derivative L-Kynurenine, 3-IAld would bind and activate the Aryl hydrocarbon Receptor (AhR), which, in turn, controls endogenous tryptophan catabolic pathways. As a result, in peripheral lymph nodes, microbial 3-IAld, affected mast-cell tryptophan metabolism, forcing mast cells to produce serotonin via Tph1. We thus propose a protective role for AhR-mast-cell activation driven by the microbiome, whereby natural metabolites or postbiotics will have a physiological role in immune homeostasis and may act as therapeutic targets in autoimmune diseases.

Mast cell activation disrupts interactions between endothelial cells and pericytes during early life allergic asthma

Allergic asthma generally starts during early life and is linked to substantial tissue remodeling and lung dysfunction. Although angiogenesis is a feature of the disrupted airway, the impact of allergic asthma on the pulmonary microcirculation during early life is unknown. Here, using quantitative imaging in precision-cut lung slices (PCLSs), we report that exposure of neonatal mice to house dust mite (HDM) extract disrupts endothelial cell/pericyte interactions in adventitial areas. Central to the blood vessel structure, the loss of pericyte coverage was driven by mast cell (MC) proteases, such as tryptase, that can induce pericyte retraction and loss of the critical adhesion molecule N-cadherin. Furthermore, spatial transcriptomics of pediatric asthmatic endobronchial biopsies suggests intense vascular stress and remodeling linked with increased expression of MC activation pathways in regions enriched in blood vessels. These data provide previously unappreciated insights into the pathophysiology of allergic asthma with potential long-term vascular defects.

Tumor-infiltrating mast cells stimulate ICOS+ regulatory T cells through an IL-33 and IL-2 axis to promote gastric cancer progression

INTRODUCTION

In solid tumors, regulatory T cell (Treg) and mast cell perform different roles depending on the microenvironment. Nevertheless, mast cell and Treg-mediated interactions in gastric cancer (GC) are unclear, as are their regulation, function, and clinical significance.

OBJECTIVE

The present study demonstrated the mechanism of tumor-infiltrating mast cells stimulating ICOS+ regulatory T cells via the IL-33/IL-2 axis to promote the growth of gastric cancer.

METHODS

Analyses of 98 patients with GC were conducted to examine mast cell counts, ICOS+ Tregs, and the levels of IL-33 or IL-2. Isolated ICOS+ Treg and CD8+ T cell were stimulated, cultured and tested for their functional abilities in vitro and in vivo.

RESULTS

GC patients exhibited a significantly more production of IL-33 in tumors. Mast cell stimulated by tumor-derived IL-33 exhibited a prolonged lifespan through IL-33 mediated inhibition of apoptosis. Moreover, mast cells stimulated by tumor-derived IL-33 secreted IL-2, which induced Treg expansion. These inducible Tregs displayed an activated immunosuppressive phenotype with positive expression for the inducible T cell co-stimulator (ICOS). In vitro, IL-2 from IL to 33-stimulated mast cells induced increased numbers of ICOS+ Tregs with increased immunosuppressive activity against proliferation and effector function of CD8+ T cell. In vivo, ICOS+ Tregs were treated with anti-IL-2 neutralizing antibody followed by co-injection with CD8+ T cells in GC mouse model, which showed an increased CD8+ T cell infiltration and effector molecules production, meanwhile tumor growth and progression were inhibited. Besides, reduction in GC patient survival was associated with tumor-derived ICOS+ Tregs.

CONCLUSION

Our results highlight a crosstalk between GC-infiltrating mast cells and ICOS+ Tregs and provide a novel mechanism describing ICOS+ Treg expansion and induction by an IL-33/mast cell/IL-2 signaling axis in GC, and also provide functional evidence that the modulation of this immunosuppressive pathway can attenuate GC-mediated immune tolerance.

Reversible Elevation of Tryptase Over the Individual's Baseline: Why is It the Best Biomarker for Severe Systemic Mast Cell Activation and MCAS?

PURPOSE OF REVIEW

Mast cell (MC) activation syndromes (MCAS) are conditions defined by recurrent episodes of severe systemic anaphylaxis or similar systemic events triggered by MC-derived mediators that can be measured in biological fluids. Since some symptoms of MC activation may occur due to other, non-MC etiologies and lead to confusion over diagnosis, it is of crucial importance to document the involvement of MC and their products in the patients´ symptomatology.

RECENT FINDINGS

The most specific and generally accepted marker of severe systemic MC activation is an event-related, transient increase in the serum tryptase level over the individual baseline of the affected individual. However, baseline concentrations of serum tryptase vary among donors, depending on the genetic background, age, kidney function, and underlying disease. As a result, it is of critical importance to provide a flexible equation that defines the diagnostic increase in tryptase qualifying as MCAS criterion in all patients, all situations, and all ranges of baseline serum tryptase. In 2012, the consensus group proposed the 120% + 2 ng/ml formula, which covers the great majority of groups, including cases with low, normal, or elevated basal serum tryptase level. This formula has been validated in subsequent studies and has proven to be a robust and consistent diagnostic criterion of MCAS. The present article is discussing the impact of this formula and possible limitations as well as alternative markers and mediators that may be indicative of MCAS.

Non-IgE-Mediated Immediate Drug-Induced Hypersensitivity Reactions

Immediate drug-induced hypersensitivity reactions (IDHSRs) have conventionally been attributed to an immunoglobulin E (IgE)-mediated mechanism. Nevertheless, it has now been acknowledged that IDHSRs can also occur independently of IgE involvement. Non-IgE-mediated IDHSRs encompass the activation of effector cells, both mast cell-dependent and -independent and the initiation of inflammatory pathways through immunogenic and nonimmunogenic mechanisms. The IDHSRs involve inflammatory mediators beyond histamine, including the platelet-activating factor, which activates multiple cell types, including smooth muscle, endothelium, and MC, and evidence supports its importance in IgE-mediated reactions in humans. Clinically, distinguishing IgE from non-IgE mechanisms is crucial for future treatment strategies, including drug(s) restriction, readministration approaches, and pretreatment considerations. However, this presents significant challenges because certain drugs can trigger both mechanisms, and their presentations can appear similarly, ranging from mild to life-threatening symptoms. Thus, history alone is often inadequate for differentiation, and skin tests lack a standardized approach. Moreover, drug-specific IgE immunoassays have favorable specificity but low sensitivity, and the usefulness of the basophil activation test remains debatable. Lastly, no biomarker reliably differentiates between both mechanisms. Whereas non-IgE-mediated mechanisms likely predominate in IDHSRs, reclassifying most drug-related IDHSRs as non-IgE-mediated, with suggested prevention through dose administration adjustments, is premature and risky. Therefore, continued research and validated diagnostic tests are crucial to improving our capacity to distinguish between these mechanisms, ultimately enhancing patient care.

Mast Cell Activation Profile and TFH13 Detection Discriminate Food Anaphylaxis Versus Sensitization

BACKGROUND AND OBJECTIVE

The prevalence of food allergy (FA) has increased significantly, and the risk of developing anaphylaxis is unpredictable. Thus, discriminating between sensitized patients and those at risk of having a severe reaction is of utmost interest. To explore mast cell activation pattern and T follicular helper (TFH) 13 presence in sensitized and food anaphylaxis patients.

METHODS

Patients sensitized to Lipid transfer protein (LTP) were classified as anaphylaxis or sensitized depending on the symptoms elicited by LTP-containing food. CD34+-derived MCs from patients and controls were obtained, sensitized with pooled sera, and challenged with Pru p 3 (peach LTP). Degranulation, PGD2, and cytokine/chemokine release were measured. The TFH13 population was examined by flow cytometry in the peripheral blood of all groups. In parallel, LAD2 cells were activated similarly to patients' MCs.

RESULTS

A distinguishable pattern of mast cell activation was found in anaphylaxis compared to sensitized patients. Robust degranulation, PGD2, and IL-8 and GM-CSF secretion were higher in anaphylaxis, whereas TFG- and CCL2 secretion increased in sensitized patients. Concomitantly, anaphylaxis patients had a larger TFH13 population. MC activation profile was dependent on the sera rather than the MC source. In agreement with that, LAD2 cells reproduce the same pattern as MCs from anaphylactic and sensitized patients.

CONCLUSION

The distinct profile of mast cell activation allows to discriminate between anaphylaxis and sensitized patients. Pooled sera may determine mast cell activation independently of mast cell origin. Besides, the presence of TFH13 cells in anaphylaxis patients points to an essential role of IgE affinity.

Combined effect of trifluoperazine and sodium cromoglycate on reducing acute edema and limiting lasting functional impairments after spinal cord injury in rats

Edema formation is one of the very first events to occur after spinal cord injury (SCI) leading to an increase of the intrathecal pressure and consequently to serious spinal tissue and functional impairments. Current edema treatments are still symptomatic and/or non-specific. Since edema formation mechanisms are mainly described as vasogenic and cytotoxic, it becomes crucial to understand the interplay between these two subtypes. Acting on key targets to inhibit edema formation may reduce secondary damage and related functional impairments. In this study, we characterize the edema kinetic after T9-10 spinal contusion. We use trifluoperazine (TFP) to block the expression and the functional subcellular localization of aquaporin-4 supposed to be implicated in the cytotoxic edema formation. We also use sodium cromoglycate (SCG) to deactivate mast cell degranulation known to be implicated in the vasogenic edema formation. Our results show a significant reduction of edema after TFP treatment and after TFP-SCG combined treatment compared to control. This reduction is correlated with limited onset of initial sensorimotor impairments particularly after combined treatment. Our results highlight the importance of potential synergetic targets in early edema therapy after SCI as part of tissue sparing strategies.

Cellular and Molecular Mechanisms of Mast Cells in Atherosclerotic Plaque Progression and Destabilization

Mast cells (MCs) are commonly recognized for their crucial involvement in the pathogenesis of allergic diseases, but over time, it has come to light that they also play a role in the pathophysiology of non-allergic disorders including atherosclerosis. The involvement of MCs in the pathology of atherosclerosis is supported by their accumulation in atherosclerotic plaques upon their progression and the association of intraplaque MC numbers with acute cardiovascular events. MCs that accumulate within the atherosclerotic plaque release a cocktail of mediators through which they contribute to neovascularization, plaque progression, instability, erosion, rupture, and thrombosis. At a molecular level, MC-released proteases, especially cathepsin G, degrade low-density lipoproteins (LDL) and mediate LDL fusion and binding of LDL to proteoglycans (PGs). Through a complicated network of chemokines including CXCL1, MCs promote the recruitment of among others CXCR2+ neutrophils, therefore, aggravating the inflammation of the plaque environment. Additionally, MCs produce extracellular traps which worsen inflammation and contribute to atherothrombosis. Altogether, evidence suggests that MCs actively, via several underlying mechanisms, contribute to atherosclerotic plaque destabilization and acute cardiovascular syndromes, thus, making the study of interventions to modulate MC activation an interesting target for cardiovascular medicine.

Regulatory T cells Are Increased and Correlate With Mast Cells in Eosinophilic Esophagitis

Background/Aims

The incidence of eosinophilic esophagitis (EoE) has been increasing recently. The role of regulatory T cells (Tregs) and correlations with other inflammatory cells in EoE remain unknown. We aim to clarify the role of Tregs and their correlations with inflammatory cells in EoE patients.

Methods

Biopsies from controls and EoE patients before and after treatments were analyzed. Eosinophil infiltration was evaluated by hematoxylin and eosin staining. Immunohistochemical staining was performed to examine infiltration of T cells, Tregs, and mast cells. Gene expressions of chemokines were evaluated by reverse transcription-quantitative polymerase chain reaction.

Results

Tregs and mast cells were increased in the esophageal epithelial layers of EoE patients. After treatments, Tregs and mast cells were decreased when histologic remission was achieved. Infiltration of Tregs correlated significantly with numbers of eosinophils and mast cells. Filaggrin mRNA was decreased in patients with EoE before treatment and upregulated after treatment, even when histologic remission was not achieved.

Conclusions

Tregs were increased in esophageal epithelium of patients with EoE, and correlated with mast cell infiltration.

Prognostic role of macrophages and mast cells in the microenvironment of hepatocellular carcinoma after resection

BACKGROUND

The prognostic significance of mast cells and different phenotypes of macrophages in the microenvironment of hepatocellular carcinoma (HCC) following resection is unclear. We aimed in this study to assess the local distribution of infiltrating macrophages and mast cells of specific phenotypes in tissues of HCC and to evaluate their prognostic values for survival of post-surgical patients.

METHODS

The clinicopathological and follow-up data of 70 patients with HCC, who underwent curative resection of tumor from 1997 to 2019, were collected. The infiltration of CD68+ and CD163+ macrophages and CD117+ mast cells was assessed immunohistochemically in representative resected specimens of HCC and adjacent tissues. The area fraction (AF) of positively stained cells was estimated automatically using QuPath image analysis software in several regions, such as tumor center (TC), inner margin (IM), outer margin (OM), and peritumor (PT) area. The prognostic significance of immune cells, individually and in associations, for time to recurrence (TTR), disease-free survival (DFS), and overall survival (OS) was evaluated using Kaplan-Meier and Cox regression analyses.

RESULTS

High AF of CD68+ macrophages in TC and IM and high AF of mast cells in IM and PT area were associated with a longer DFS. High AF of CD163+ macrophages in PT area correlated with a shorter DFS. Patients from CD163TChigh & CD68TClow group had a shorter DFS compared to all the rest of the groups, and cases with CD163IMlow & CD68IMhigh demonstrated significantly longer DFS compared to low AF of both markers. Patients from CD68IMhigh & CD163PTlow group, CD117IMhigh & CD163PTlow group, and CD117PThigh & CD163PTlow group had a significantly longer DFS compared to all other combinations of respective cells.

CONCLUSIONS

The individual prognostic impact of CD68+ and CD163+ macrophages and mast cells in the microenvironment of HCC after resection depends on their abundance and location, whereas the cumulative impact is built upon combination of different cell phenotypes within and between regions.

Transient immune activation without loss of intraepidermal innervation and associated Schwann cells in patients with complex regional pain syndrome

BACKGROUND

Complex regional pain syndrome (CRPS) develops after injury and is characterized by disproportionate pain, oedema, and functional loss. CRPS has clinical signs of neuropathy as well as neurogenic inflammation. Here, we asked whether skin biopsies could be used to differentiate the contribution of these two systems to ultimately guide therapy. To this end, the cutaneous sensory system including nerve fibres and the recently described nociceptive Schwann cells as well as the cutaneous immune system were analysed.

METHODS

We systematically deep-phenotyped CRPS patients and immunolabelled glabrous skin biopsies from the affected ipsilateral and non-affected contralateral finger of 19 acute (< 12 months) and 6 chronic (> 12 months after trauma) CRPS patients as well as 25 sex- and age-matched healthy controls (HC). Murine foot pads harvested one week after sham or chronic constriction injury were immunolabelled to assess intraepidermal Schwann cells.

RESULTS

Intraepidermal Schwann cells were detected in human skin of the finger-but their density was much lower compared to mice. Acute and chronic CRPS patients suffered from moderate to severe CRPS symptoms and corresponding pain. Most patients had CRPS type I in the warm category. Their cutaneous neuroglial complex was completely unaffected despite sensory plus signs, e.g. allodynia and hyperalgesia. Cutaneous innate sentinel immune cells, e.g. mast cells and Langerhans cells, infiltrated or proliferated ipsilaterally independently of each other-but only in acute CRPS. No additional adaptive immune cells, e.g. T cells and plasma cells, infiltrated the skin.

CONCLUSIONS

Diagnostic skin punch biopsies could be used to diagnose individual pathophysiology in a very heterogenous disease like acute CRPS to guide tailored treatment in the future. Since numbers of inflammatory cells and pain did not necessarily correlate, more in-depth analysis of individual patients is necessary.

The regulatory role and mechanism of mast cells in tumor microenvironment

Mast cells (MCs) have emerged as pivotal contributors to both the defensive immune response and immunomodulation. They also exhibit regulatory functions in modulating pathological processes across various allergic diseases. The impact of MC presence within tumor tissues has garnered considerable attention, yielding conflicting findings. While some studies propose that MCs within tumor tissues promote tumor initiation and progression, others advocate an opposing perspective. Notably, evidence emphasizes the dual role of MCs in cancer, both as promoters and suppressors, is crucial for optimizing cancer treatment strategies. These conflicting viewpoints have generated substantial controversy, underscoring the need for a comprehensive understanding of MC's role in tumor immune responses.

A one-pot and eco-friendly synthesis of novel β-substituted-α-halomethyl acrylates and the bioactivity of these compounds in an in vitro model of mast cell degranulation induced by pro-inflammatory stimuli

The goal of the present work was to develop novel β-substituted-α-halomethyl acrylates from a methodology in an aqueous phase and to evaluate their bioactivity as potential inhibitors of mast cell activation. Eleven β-substituted-α-halomethyl acrylates were synthesized through a modified Horner-Wadsworth-Emmons reaction. Compound 48/80 and the calcium ionophore A23187 stimulated the release of β-hexosaminidase from mast cells. The effect induced by compound 48/80 was inhibited by compound 5 (320 µM) and compound 9 (160 and 320 µM) without causing cytotoxic effects. The effect induced by A23187 was inhibited by compound 5 (40, 80, 160, and 320 µM) without affecting cell viability. The inhibitory effects exhibited by compounds 5 and 9 were more potent than those of the reference compound sodium cromoglycate at the same concentrations. The biochemical results were consistent with the morphological findings obtained by light and transmission electron microscopy. This study reports, for the first time, that the new synthetic compounds methyl (Z)- 2-bromo-3-(furan-3-yl)acrylate (compound 5) and methyl (E)- 2-bromo-3-(3-bromophenyl)acrylate (compound 9) strongly inhibit mast cell degranulation, without affecting cell viability. The implications of these results are relevant as a basis for developing new anti-inflammatory and mast cell stabilizing drugs.

[Mastocytosis-a frequently unrecognized disease]

Mastocytosis is a rare disease characterized by clonal expansion and accumulation of mast cells (MC) in various organs. Mastocytosis results from an activating mutation of the KIT surface receptor leading to an increased proliferation of MC. There are significant differences between children and adult patients with mastocytosis. Children mainly present the cutaneous form, whereas adults more often exhibit the systemic form of mastocytosis. Patients with mastocytosis may be asymptomatic or affected by a variety of symptoms. Treatment is primarily supportive and aims at symptom control. New approved targeted therapies such as midostaurin and avapritinib changed the treatment paradigm in advanced forms of the disease, and next-generation inhibitors currently in clinical trials are expected in the near future.

Deficiency of BMAL1 promotes ROS generation and enhances IgE-dependent degranulation in mast cells

BACKGROUND

Bmal1 (Brain and muscle arnt-like, or Arntl) is a bHLH/PAS domain transcription factor central to the transcription/translation feedback loop of the circadian clock. Mast cells are crucial for effector functions in allergic reaction and their activity follows a circadian rhythm. However, the functional roles of Bmal1 in mast cells remain to be determined.

PURPOSE

This study aimed to elucidate the specific roles of Bmal1 in IgE-dependent mast cell degranulation.

RESULTS

IgE-dependent degranulation was enhanced in bone marrow-derived mast cells (BMMCs) derived from Bmal1-deficient mice (Bmal1-KO mice) compared to that in BMMCs derived from wild-type mice (WT mice) in the absence of 2-Mercaptoethanol (2-ME) in culture. Mast cell-deficient KitW-sh mice reconstituted with Bmal1-KO BMMCs showed more robust passive cutaneous anaphylactic (PCA) reactions, an in vivo model of IgE-dependent mast cell degranulation, than KitW-sh mice reconstituted with WT BMMCs. In the absence of 2-ME in culture, the mRNA expression of the anti-oxidative genes NF-E2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2), and heme oxygenase-1 (HO-1) was lower and reactive oxygen species (ROS) generation was higher in Bmal1-KO BMMCs than in WT BMMCs at steady state. The IgE-dependent ROS generation and degranulation were enhanced in Bmal1-KO BMMCs compared to WT BMMCs in the absence of 2-ME in culture. The addition of 2-ME into the culture abrogated or weakened the differences in anti-oxidative gene expression, ROS generation, and IgE-dependent degranulation between WT and Bmal1-KO BMMCs.

CONCLUSION

The current findings suggest that Bmal1 controls the expression of anti-oxidative genes in mast cells and Bmal1 deficiency enhanced IgE-dependent degranulation associated with promotion of ROS generation. Thus, Bmal1 may function as a key molecule that integrates redox homeostasis and effector functions in mast cells.

Role of mast cells activation in the tumor immune microenvironment and immunotherapy of cancers

The mast cell is an important cellular component that plays a crucial role in the crosstalk between innate and adaptive immune responses within the tumor microenvironment (TME). Recently, numerous studies have indicated that mast cells related to tumors play a dual role in regulating cancers, with conflicting results seemingly determined by the degranulation medium. As such, mast cells are an ignored but very promising potential target for cancer immunotherapy based on their immunomodulatory function. In this review, we present a comprehensive overview of the roles and mechanisms of mast cells in diverse cancer types. Firstly, we evaluated the infiltration density and location of mast cells on tumor progression. Secondly, mast cells are activated by the TME and subsequently release a range of inflammatory mediators, cytokines, chemokines, and lipid products that modulate their pro-or anti-tumor functions. Thirdly, activated mast cells engage in intercellular communication with other immune or stromal cells to modulate the immune status or promote tumor development. Finally, we deliberated on the clinical significance of targeting mast cells as a therapeutic approach to restrict tumor initiation and progression. Overall, our review aims to provide insights for future research on the role of mast cells in tumors and their potential as therapeutic targets for cancer treatment.

Meta-analysis of single-cell RNA-sequencing data for depicting the transcriptomic landscape of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by airflow limitation and chronic inflammation of the lungs that is a leading cause of death worldwide. Since the complete pathological mechanisms at the single-cell level are not fully understood yet, an integrative approach to characterizing the single-cell-resolution landscape of COPD is required. To identify the cell types and mechanisms associated with the development of COPD, we conducted a meta-analysis using three single-cell RNA-sequencing datasets of COPD. Among the 154,011 cells from 16 COPD patients and 18 healthy subjects, 17 distinct cell types were observed. Of the 17 cell types, monocytes, mast cells, and alveolar type 2 cells (AT2 cells) were found to be etiologically implicated in COPD based on genetic and transcriptomic features. The most transcriptomically diversified states of the three etiological cell types showed significant enrichment in immune/inflammatory responses (monocytes and mast cells) and/or mitochondrial dysfunction (monocytes and AT2 cells). We then identified three chemical candidates that may potentially induce COPD by modulating gene expression patterns in the three etiological cell types. Overall, our study suggests the single-cell level mechanisms underlying the pathogenesis of COPD and may provide information on toxic compounds that could be potential risk factors for COPD.

Histological Characteristics of Chronic Allergic Rhinitis Versus Non-allergy: Is There a Difference in the Remodeling?

Demonstrate the histological remodeling changes in the turbinates, identify the frequency of the two forms of rhinitis in the samples studied and determine the remodeling differences found in the two variants. Patients attended an otolaryngology service at the Social Security Hospital of city Sangolqui-Ecuador from February 2016 to June 2017. The allergic variant was determined when eosinophils were found by higher magnification field and non-allergic when they were not found in the submucosal segment. Epithelial, inflammatory, and stromal markers were analyzed. One hundred twenty histopathological samples were analyzed, 75% presented allergic rhinitis, the age averaged 36.2 years. When we compared between the allergic and non-allergic variants: epithelial and stromal markers we had significant differences, as well as between each of its components; except fibrosis. In relation to the inflammatory pattern, there were significant differences between the number of mast cells and stromal markers with eosinophils > 10 by field. The allergic type corresponded to 75% of patients with persistent severe rhinitis who underwent turbinectomy. Regarding remodeling, there was a statistically significant difference in favor of the allergic variant. Eosinophilia greater than 10 was directly related to mastocytosis and subepithelial edema.

Mast Cell Disorders of the Gastrointestinal Tract: Clarity out of Chaos

Pathologists are increasingly asked to evaluate mast cell infiltrates in the gastrointestinal tract when there is clinical concern for systemic mastocytosis or a variety of functional disorders, including irritable bowel syndrome and mast cell activation syndrome. Neoplastic mast cells have established quantitative, morphologic, and immunohistochemical features that facilitate their identification in gastrointestinal mucosal biopsies. Specific qualitative and quantitative findings are lacking for inflammatory mast cell-mediated disorders. This review covers histopathologic features of mast cell disorders that affect the gastrointestinal tract and offers practical guidance for their assessment in mucosal biopsies.

Development and evaluation of mouse anti-Ara h 1 and Ara h 3 IgE monoclonal antibodies for advancing peanut allergy research

Immediate hypersensitivity reactions to peanuts are a considerable public health concern due to the acute and severe IgE mediated reactions. To conduct research on the pathogenesis and therapeutics of peanut allergies, it is imperative to have mouse anti-crude peanut extract (CPE) IgE monoclonal antibodies (mAbs) for both in-vitro and in-vivo assays. Without these tools, it is difficult to advance research in this field. In this study, four hybridomas producing anti-CPE IgE mAbs were developed and the IgE mAbs were validated using immune-blot analysis, Sandwich ELISA, Indirect ELISA, a cell-based assay using RBL-2H3 cells, and footpad type I hypersensitivity reaction studies in mice. The results indicate that two of the four mAbs can be effectively used for both in-vitro and in-vivo peanut allergy studies, as they induce allergic reactions with sensitization alone in mice. These novel anti-Ara h1 and Ara h 3 IgE mAbs, in combination with the detailed protocols outlined in this article, offer valuable guidance for studying acute allergic reactions involving mast cells across various platforms. With some considerations, the IgE mAbs can significantly advance peanut allergy research.

Single-cell analysis unveils activation of mast cells in colorectal cancer microenvironment

The role of mast cells (MCs) in colorectal cancer (CRC) remains unclear, and a comprehensive single-cell study on CRC MCs has not been conducted. This study used a multi-omics approach, integrating single-cell sequencing, spatial transcriptomics, and bulk tissue sequencing data to investigate the heterogeneity and impact of MCs in CRC. Five MC signature genes (TPSAB1, TPSB2, CPA3, HPGDS, and MS4A2) were identified, and their average expression was used as a marker of MCs. The MC density was found to be lower in CRC compared to normal tissue, but MCs in CRC demonstrated distinct activation features. Activated MCs were defined by high expression of receptors and MC mediators, while resting MCs had low expression. Most genes, including the five MC signature genes, were expressed at higher levels in activated MCs. The MC signature was linked to a better prognosis in both CRC and pan-cancer patient cohorts. Elevated KITLG expression was observed in fibroblasts and endothelial cells in CRC samples compared to normal tissue, and co-localization of MCs with these cell types was revealed by spatial transcriptome analysis. In conclusion, this study finds decreased MC density in CRC compared to normal tissue, but highlights a shift in MC phenotype from CMA1high resting cells to activated TPSAB1high, CPA3high, and KIThigh cells. The elevated KITLG expression in the tumor microenvironment's fibroblasts and endothelial cells may activate MCs through the KITLG-KIT axis, potentially suppressing tumor progression.

Effect of acupuncture on the expression of neuropeptides and related inflammatory factors in rats with diarrhea-predominant irritable bowel syndrome

OBJECTIVES

To observe the effect of acupuncture on the expressions of neuropeptides and related inflammatory factors in rats with diarrhea-predominant irritable bowel syndrome(IBS-D), so as to explore the mechanism of acupuncture in the treatment of IBS-D.

METHODS

Male Wistar rats were randomly divided into blank group, model group, medication group, and acupuncture group, with 6 rats in each group. Except for the blank group, the other groups were subjected to 14-day "acetic acid enema + restraint stress" to establish the IBS-D rat model. After successful modeling, the medication group received gavage of pinaverium bromide(15 mg/kg) once a day, and the acupuncture group received acupuncture at "Baihui"(GV20) and bilateral "Tianshu"(ST25), "Shangjuxu"(ST37), "Zusanli"(ST36), and "Taichong"(LR3) for 20 min every day, both groups were treated continuously for 14 days. The general state of the rats in each group was observed, and the body weight of the rats was measured. The open-field experiment was conducted to measure the horizontal and vertical movements, and the number of fecal pellets of rats. The histopathological morphology of hypothalamus and colon of rats was observed by HE staining. Toluidine blue staining was used to observe and count the mast cells(MCs) in the colon tissue of rats. ELISA was used to detect the serum contents of tumor necrosis factor-α(TNF-α) and interleukin(IL)-10. Real-time fluorescence quantitative PCR was performed to detect the mRNA expressions of calcitonin gene-related peptide(CGRP) in the hypothalamus and colon tissue. Western blot was used to detect the expressions of corticotropin-releasing factor(CRF) in the hypothalamus and colon tissue.

RESULTS

HE staining showed that there was inflammatory cell infiltration in the lamina propria of colon in the model group, and it was reduced in the other groups. Compared with the blank group, the model group showed significantly decreased body weight, decreased walking distance and upright times in open field experiment, decreased serum IL-10 contents(P<0.05, P<0.01), increased fecal pellet number (P<0.01), increased MC number in the colon tissue, serum TNF-α contents, and CGRP mRNA expressions and CRF expressions in the hypothalamus and colon tissue(P<0.01). Compared with the model group, both medication and acupuncture groups showed significantly increased body weight, walking distance and upright times in the open-field experiment, and serum IL-10 contents(P<0.01, P<0.05), significantly decreased fecal pellet number (P<0.05), significantly decreased MC number in the colon tissue, serum TNF-α contents, and CGRP mRNA expressions in the hypothalamus and colon tissue(P<0.01)；at the same time, the acupuncture group showed significantly decreased CRF expressions in the hypothalamus and colon tissue(P<0.01, P<0.05). There was no significant difference in the above indicators between the medication group and the acupuncture group.

CONCLUSIONS

Acupuncture can improve the general and emotional state, inflammatory response, and neuropeptide expression in rats with IBS-D, and alleviate the symptoms of IBS-D, which may be related to the regulation of neuropeptides and inflammatory factors levels.

Mechanism of analgesic effect of fire needle on peripheral sensitization in rats with neuropathic pain induced by chemotherapy

OBJECTIVES

This study aims to explore the analgesic mechanism of fire needle on peripheral sensitization in rats with neuropathic pain(NP) induced by oxaliplatin, so as to investigate its mechanism in improving peri-pheral sensitization.

METHODS

Male SD rats aged 8 weeks were randomly divided into 4 groups：normal group(n=6), model group(n=6), fire needle group(n=6), and medication group(n=6). NP rat model was established by intraperitoneal injection of oxaliplatin(4 mg/kg) on days 1, 2, 8, 9, 15, 16, 22, and 23. For rats in the fire needle group, fire needle treatment was performed at the "Jiaji"(EX-B2) acupoints of the L4-L6 segments on days 24, 26, and 28, ie. 1 day, 3 and 5 days after modeling. The medication group received intraperitoneal injection of pregabalin(100 mg/kg). Mechanical pain thresholds of the rats were measured before modeling, after modeling and intervention. Serum contents of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) and chemokine ligand 12(CXCL12) were detected by ELISA. Skin histopathology changes in the acupoint area were observed using HE staining. The number of mast cells in the skin of the acupoints was observed using toluidine blue staining. Immunohistochemical staining was performed to detect the postive expressions of transient receptor potential vanilloid 1(TRPV1), protease-activated receptor 2(PAR2) and tryptase(TPS) in the skin of the acupoint area. Western blot was used to detect the protein expressions of TRPV1 and PAR2 in the dorsal root ganglia(DRG).

RESULTS

Compared with the normal group, the model group had decreased paw withdrawal threshold(PWT) after modeling(P<0.05), increased serum contents of IL-6, TNF-α, and CXCL12(P<0.05), increased number of mast cells in the acupoint area(P<0.05), and increased positive protein expressions of TPS, TRPV1, and PAR2 in the skin of the acupoint area(P<0.05). Compared with the model group, the fire needle group and medication group had increased PWT after intervention(P<0.05), decreased serum contents of IL-6, TNF-α, and CXCL12, and postive protein expressions of TPS, TRPV1, and PAR2 in the skin of the acupoint area(P<0.05)；while the medication group had decreased protein expressions of TRPV1 and PAR2 in DRG(P<0.05). HE staining showed thickened epidermis, disordered cellular arrangement, significant intercellular edema, and inflammatory cell infiltration in the model group. In the medication and fire needle groups, the epidermis was thinner, cellular arrangement was clearer, and the extent of tissue edema and inflammatory cell infiltration was reduced compared to the model group.

CONCLUSIONS

Fire needle can improve mechanical pain threshold and reduce the contents of peripheral inflammatory factors in rats with oxaliplatin-induced NP. This effect may be related to the inhibition of mast cell activation and the inhibition of TPS, TRPV1 and PAR2 protein expressions, in the local areas of acupoints.

Effects of photobiomodulation in the experimental acetic acid-induced colitis: comparison between male and female

Ulcerative colitis (UC) is an important chronic and multifactorial disease, which alters the colon mucosal with a significant impact on life quality affecting both men and women. The difference between genders causes changes in the inflammatory processes, modulating the development of several diseases. The available drugs to treat UC exhibit limited outcomes and side effects; thus, new therapies are needed. Photobiomodulation (PBM) emerges as potential treatment by modulating the inflammatory process without side effects and low costs. The aim of this study was to evaluate the effects of PBM in acetic acid-induced UC comparing the responses between male and females. For this purpose, male and female Wistar rats (36) were submitted to induction of UC by rectal administration of 10% acetic acid (colitis group) and treated or not with PBM (colitis-PBM group) (LED, 660 nm, 100 mW, 150 s) in three points: right side and left of the ventral surface and in the external anal region. Non-manipulated rats were used as control (basal group). We investigated the disease activity index (DAI score), myeloperoxidase enzyme activity (MPO) and release of cytokines in the intestine homogenates, and histological analysis. PBM reduces DAI score, MPO activity, and mast cell degranulation while increased mucous production in both females and males. Moreover, PBM reduced histopathological score as well as the levels of IL-6 and IL-4 in the bowel only in males. We also showed reduced levels of IL-1beta and TNF-alpha after PBM in both males and females, while the levels of IL-10 and IFN-gamma were increased. In conclusion, despite our study has shown some differences between males and females, PBM attenuated the biomarkers of UC in both genders constituting a potential combined treatment that is non-invasive and low cost.

S. aureus biofilm metabolic activity correlates positively with patients' eosinophil frequencies and disease severity in chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a persistent inflammation of the sinus mucosa. Recalcitrant CRS patients are unresponsive to medical and surgical interventions and often present with nasal polyps, tissue eosinophilia, and Staphylococcus aureus dominant mucosal biofilms. However, S. aureus sinonasal mucosal colonisation occurs in the absence of inflammation, questioning the role of S. aureus in CRS pathogenesis. Here, we aimed to investigate the relationship between S. aureus biofilm metabolic activity and virulence genes, innate immune cells, and disease severity in CRS. Biospecimens, including sinonasal tissue and nasal swabs, and clinical datasets, including disease severity scores, were obtained from CRS patients and non-CRS controls. S. aureus isolates were grown into biofilms in vitro, characterised, and sequenced. The patients' innate immune response was evaluated using flow cytometry. S. aureus was isolated in 6/19 (31.58%) controls and 23/53 (43.40%) CRS patients of 72 recruited patients. We found increased S. aureus biofilm metabolic activity in relation to increased eosinophil cell frequencies and disease severity in recalcitrant CRS cases. Mast cell frequencies were higher in tissue samples of patients carrying S. aureus harbouring lukF.PV, sea, and fnbB genes. Patients with S. aureus harbouring lukF.PV and sdrE genes had more severe disease. This offers insights into the pathophysiology of CRS and could lead to the development of more targeted therapies.

KIT Mutations and Other Genetic Defects in Mastocytosis: Implications for Disease Pathology and Targeted Therapies

A KIT activating mutation (usually KIT D816V) is detected in neoplastic cells in greater than 90% of indolent patients with systemic mastocytosis (SM). In more advanced variants of SM, additional genetic defects can be found in several myeloid malignancy-related genes, which can be detected by applying next-generation sequencing. Currently, the techniques recommended to detect the KIT D816V mutation and quantify the mutational burden in peripheral blood, bone marrow, or other organs/tissues are allele specific-quantitative PCR or droplet digital PCR. These techniques are useful for diagnosis, prognostication, follow-up and monitoring of therapeutic efficacy of cytoreductive agents in patients with SM.

Thymic stromal lymphopoietin (TSLP) is a substrate for tryptase in patients with mastocytosis

Mastocytosis is a heterogeneous disease associated to uncontrolled proliferation and increased density of mast cells in different organs. This clonal disorder is related to gain-of-function pathogenic variants of the c-kit gene that encodes for KIT (CD117) expressed on mast cell membrane. Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine, which plays a key role in allergic disorders and several cancers. TSLP is a survival and activating factor for human mast cells through the engagement of the TSLP receptor. Activated human mast cells release several preformed mediators, including tryptase. Increased mast cell-derived tryptase is a diagnostic biomarker of mastocytosis. In this study, we found that in these patients serum concentrations of TSLP were lower than healthy donors. There was an inverse correlation between TSLP and tryptase concentrations in mastocytosis. Incubation of human recombinant TSLP with sera from patients with mastocytosis, containing increasing concentrations of tryptase, concentration-dependently decreased TSLP immunoreactivity. Similarly, recombinant β-tryptase reduced the immunoreactivity of recombinant TSLP, inducing the formation of a cleavage product of approximately 10 kDa. Collectively, these results indicate that TSLP is a substrate for human mast cell tryptase and highlight a novel loop involving these mediators in mastocytosis.

World Health Organization Classification and Diagnosis of Mastocytosis: Update 2023 and Future Perspectives

Experts of the European Competence Network on Mastocytosis (ECNM) and the American Initiative on Mast Cell Disorders have discussed and updated diagnostic criteria and the classification of mastocytosis, based on new insights in the field and data collected in recent years, mostly within ECNM registry projects in which studies on several thousand cases have been performed. Based on this proposal, the World Health Organization has updated its classification of mastocytosis. This article discusses the revised classification of mastocytosis in light of a rapidly moving field and the advent of new diagnostic parameters, new prognostication tools, and new therapies.

PTX3 shapes profibrotic immune cells and epithelial/fibroblast repair and regeneration in a murine model of pulmonary fibrosis

The long pentraxin 3 (PTX3) is protective in different pathologies but was not analyzed in-depth in Idiopathic Pulmonary Fibrosis (IPF). Here, we have explored the influence of PTX3 in the bleomycin (BLM)-induced murine model of IPF by looking at immune cells (macrophages, mast cells, T cells) and stemness/regenerative markers of lung epithelium (SOX2) and fibro-blasts/myofibroblasts (CD44) at different time points that retrace the progression of the disease from onset at day 14, to full-blown disease at day 21, to incomplete regression at day 28. We took advantage of transgenic PTX3 overexpressing mice (Tie2-PTX3) and Ptx3 null ones (PTX3-KO) in which pulmonary fibrosis was induced. Our data have shown that PTX3 overexpression in Tie2-PTX3 compared to WT or PTX3-KO: reduced CD68+ and CD163+ macrophages and the Tryptase+ mast cells during the whole experimental time; on the contrary, CD4+ T cells are consistently present on day 14 and dramatically decreased on day 21; CD8+ T cells do not show significant differences on day 14, but are significantly reduced on day 21; SOX2 is reduced on days 14 and 21; CD44 is reduced on day 21. Therefore, PTX3 could act on the proimmune and fibrogenic microenvironment to prevent fibrosis in BLM-treated mice.

Psychosocial stress-induced intestinal permeability in healthy humans: What is the evidence?

An impaired intestinal barrier function can be detrimental to the host as it may allow the translocation of luminal antigens and toxins into the subepithelial tissue and bloodstream. In turn, this may cause local and systemic immune responses and lead to the development of pathologies. In vitro and animal studies strongly suggest that psychosocial stress is one of the factors that can increase intestinal permeability via mast-cell dependent mechanisms. Remarkably, studies have not been able to yield unequivocal evidence that such relation between stress and intestinal permeability also exists in (healthy) humans. In the current Review, we discuss the mechanisms that are involved in stress-induced intestinal permeability changes and postulate factors that influence these alterations and that may explain the translational difficulties from in vitro and animal to human studies. As human research differs highly from animal research in the extent to which stress can be applied and intestinal permeability can be measured, it remains difficult to draw conclusions about the presence of a relation between stress and intestinal permeability in (healthy) humans. Future studies should bear in mind these difficulties, and more research into in vivo methods to assess intestinal permeability are warranted.

Connective tissue mast cells store and release noradrenaline

Mast cells are present in mucosal and connective tissues throughout the body. They synthesize and release a wide variety of bioactive molecules, such as histamine, proteases, and cytokines. In this study, we found that a population of connective tissue mast cells (CTMCs) stores and releases noradrenaline, originating from sympathetic nerves. Noradrenaline-storing cells, not neuronal fibers, were predominantly identified in the connective tissues of the skin, mammary gland, gastrointestinal tract, bronchus, thymus, and pancreas in wild-type mice but were absent in mast cell-deficient W-sash c-kit mutant KitW-sh/W-sh mice. In vitro studies using bone marrow-derived mast cells revealed that extracellular noradrenaline was taken up but not synthesized. Upon ionomycin stimulation, noradrenaline was released. Electron microscopy analyses further suggested that noradrenaline is stored in and released from the secretory granules of mast cells. Finally, we found that noradrenaline-storing CTMCs express organic cation transporter 3 (Oct3), which is also known as an extraneuronal monoamine transporter, SLC22A3. Our findings indicate that mast cells may play a role in regulating noradrenaline concentration by storing and releasing it in somatic tissues.

Stabilizing histamine release in gut mast cells mitigates peripheral and central inflammation after stroke

Stroke is the most common cause of long-term disability and places a high economic burden on the global healthcare system. Functional outcomes from stroke are largely determined by the extent of ischemic injury, however, there is growing recognition that systemic inflammatory responses also contribute to outcomes. Mast cells (MCs) rapidly respond to injury and release histamine (HA), a pro-inflammatory neurotransmitter that enhances inflammation. The gut serves as a major reservoir of HA. We hypothesized that cromolyn, a mast cell stabilizer that prevents the release of inflammatory mediators, would decrease peripheral and central inflammation, reduce MC trafficking to the brain, and improve stroke outcomes. We used the transient middle cerebral artery occlusion (MCAO) model of ischemic stroke in aged (18 mo) male mice to investigate the role of MC in neuroinflammation post-stroke. After MCAO we treated mice with 25 mg/kg body weight of cromolyn (MC stabilizer) by oral gavage. Cromolyn was administered at 3 h, 10 h, 24 h and every 24 h for 3 days post-stroke. Three control groups were used. One group underwent a sham surgery and was treated with cromolyn, one received sham surgery with PBS vehicle and the third underwent MCAO with PBS vehicle. Mice were euthanized at 24 h and 3 days post-stroke. Cromolyn administration significantly reduced MC numbers in the brain at both 24 h and 3 days post-stroke. Infarct volume was not significantly different between groups, however improved functional outcomes were seen at 3 days post-stroke in mice that received cromolyn. Treatment with cromolyn reduced plasma histamine and IL-6 levels in both the 24-h and 3-day cohorts. Gut MCs numbers were significantly reduced after cromolyn treatment at 24 h and 3 days after stroke. To determine if MC trafficking from the gut to the brain occurred after injury, GFP+MCs were adoptively transferred to c-kit-/- MC knock-out animals prior to MCAO. 24 h after stroke, elevated MC recruitment was seen in the ischemic brain. Preventing MC histamine release by cromolyn improved gut barrier integrity and an improvement in stroke-induced dysbiosis was seen with treatment. Our results show that preventing MC histamine release possesses prevents post-stroke neuroinflammation and improves neurological and functional outcomes.

Mast cell activation in lungs during SARS-CoV-2 infection associated with lung pathology and severe COVID-19

Lung inflammation is a hallmark of Coronavirus disease 2019 (COVID-19) in patients who are severely ill, and the pathophysiology of disease is thought to be immune mediated. Mast cells (MCs) are polyfunctional immune cells present in the airways, where they respond to certain viruses and allergens and often promote inflammation. We observed widespread degranulation of MCs during acute and unresolved airway inflammation in SARS-CoV-2-infected mice and nonhuman primates. Using a mouse model of MC deficiency, MC-dependent interstitial pneumonitis, hemorrhaging, and edema in the lung were observed during SARS-CoV-2 infection. In humans, transcriptional changes in patients requiring oxygen supplementation also implicated cells with a MC phenotype in severe disease. MC activation in humans was confirmed through detection of MC-specific proteases, including chymase, the levels of which were significantly correlated with disease severity and with biomarkers of vascular dysregulation. These results support the involvement of MCs in lung tissue damage during SARS-CoV-2 infection in animal models and the association of MC activation with severe COVID-19 in humans, suggesting potential strategies for intervention.

Nanoparticulate chitosan-TNF-α-VLPs activate mast cells and enhance adaptive immunity induced by foot-and-mouth disease virus-like particles in mice

Chitosan nanoparticulate vaccines have attracted considerable attention to potentiate immune responses. A chitosan-TNF-α-VLPs nanoparticle vaccine against foot-and-mouth disease virus (FMDV) prepared though inotropic gelation method and whether this nanoparticulate vaccine can activate mast cells and enhance immune responses induced by FMDV virus-like particles (VLPs) in mice was investigated. The nanoparticle was approximately spherical, and its size was approximately 200-300 nm. Following immunization via subcutaneous injection, the chitosan-TNF-α-VLPs nanoparticles could induce higher levels of FMDV-specific antibodies and stimulation index value than VLPs only (P < 0.01) and had similar levels to commercial vaccine group and VLPs+adjuvant group (P > 0.05). No significant differences were observed in the concentrations of IL-4, IFN-γ and IL-10 among the chitosan-TNF-α-VLPs group, VLPs+adjuvant group and commercial vaccine group (P > 0.05). Of note, the chitosan-TNF-α-VLPs nanoparticles can effectively activate mast cells in lymph nodes. These results indicated that the chitosan-TNF-α-VLPs nanoparticles can enhance both humoral and cell-mediated immunity, and both Th1 and Th2 responses, even activate mast cells, demonstrating that chitosan-TNF-α nanoparticles are potential as a vaccine adjuvant to enhance immune responses induced by FMDV-VLPs.

Anti-tumor activity of trimethoprim-sulfamethoxazole against melanoma skin cancer through triggering allergic reaction and promoting immunity

The anti-cancer impact of an allergic reaction is strongly linked to immunity enhancement. Trimethoprim-sulfamethoxazole (TMP-SMX), an antibiotic, has potential immunomodulatory effects, but has side effects such as allergies. Thus far, the effects and underlying mechanisms of TMP-SMX in melanoma have not been clarified. This study examined the potential roles of TMP-SMX in melanoma skin cancer using an immunodeficient mouse model. TMP-SMX significantly improved the survival rate and reduced the tumor weight and growth and vascular endothelial growth factor levels in melanoma skin cancer of immunodeficient mice. In the forced swimming test, TMP-SMX significantly reduced immobility time compared to the melanoma skin cancer of immunodeficient mice, indicating improved immunity. TMP-SMX significantly increased infiltration of mast cells and release of allergy-related mediators (IgE, histamine, interleukin (IL)-4, IL-5, IL-13, and IL-33) and immune-enhancing mediators (tumor necrosis factor-α, IL-2, IL-6, and IL-12). In addition, the administration of TMP-SMX significantly increased the caspase-3, 8, and 9 activities. Furthermore, mice given TMP-SMX showed no adverse reactions according to the blood biochemical parameters. TMP-SMX significantly inhibits the growth of melanoma skin cancer by triggering an allergic reaction and promotingimmunity. Hence, we propose that TMP-SMX may be used as an immune booster in cancer chemotherapy.

Airway inflammatory changes in the lungs of patients with asthma-COPD overlap (ACO): a bronchoscopy endobronchial biopsy study

BACKGROUND

Although asthma and chronic obstructive pulmonary disease (COPD) are two distinct chronic airway inflammatory diseases, they often co-exist in a patient and the condition is referred to as asthma-COPD overlap (ACO). Lack of evidence regarding the inflammatory cells in ACO airways has led to their poor prognosis and treatment. The objective of this endobronchial biopsy (EBB) study was to enumerate inflammatory cellular changes in the airway wall of ACO compared with asthma, COPD current smokers (CS) and ex-smokers (ES), normal lung function smokers (NLFS), and non-smoker controls (HC).

METHODS

EBB tissues from 74 patients were immunohistochemically stained for macrophages, mast cells, eosinophils, neutrophils, CD8+ T-cells and CD4+ T-cells. The microscopic images of stained tissues were evaluated in the epithelium, reticular basement membrane (RBM) cells/mm RBM length, and lamina propria (LP) cells/mm2 up to a depth of 120 µM using the image analysis software Image-Pro Plus 7.0. The observer was blinded to the images and disease diagnosis. Statistical analysis was performed using GraphPad Prism v9.

RESULTS

The tissue macrophages in ACO were substantially higher in the epithelium and RBM than in HC (P < 0.001 for both), COPD-ES (P < 0.001 for both), and -CS (P < 0.05 and < 0.0001, respectively). The ACO LP macrophages were significantly higher in number than COPD-CS (P < 0.05). The mast cell numbers in ACO were lower than in NLFS (P < 0.05) in the epithelium, lower than COPD (P < 0.05) and NLFS (P < 0.001) in RBM; and lower than  HC (P < 0.05) in LP. We noted lower eosinophils in ACO LP than HC (P < 0.05) and the lowest neutrophils in both ACO and asthma. Furthermore, CD8+ T-cell numbers increased in the ACO RBM than HC (P < 0.05), COPD-ES (P < 0.05), and NLFS (P < 0.01); however, they were similar in number in epithelium and LP across groups. CD4+ T-cells remained lower in number across all regions and groups.

CONCLUSION

These results suggest that the ACO airway tissue inflammatory cellular profile differed from the contributing diseases of asthma and COPD with a predominance of macrophages.

Tumoral Densities of T-Cells and Mast Cells Are Associated With Recurrence in Early-Stage Lung Adenocarcinoma

Introduction

Lung cancer is the deadliest cancer in the United States and worldwide, and lung adenocarcinoma (LUAD) is the most prevalent histologic subtype in the United States. LUAD exhibits a wide range of aggressiveness and risk of recurrence, but the biological underpinnings of this behavior are poorly understood. Past studies have focused on the biological characteristics of the tumor itself, but the ability of the immune response to contain tumor growth represents an alternative or complementary hypothesis. Emerging technologies enable us to investigate the spatial distribution of specific cell types within the tumor nest and characterize this immune response. This study aimed to investigate the association between immune cell density within the primary tumor and recurrence-free survival (RFS) in stage I and II LUAD.

Methods

This study is a prospective collection with retrospective evaluation. A total of 100 patients with surgically resected LUAD and at least 5-year follow-ups, including 69 stage I and 31 stages II tumors, were enrolled. Multiplexed immunohistochemistry panels for immune markers were used for measurement.

Results

Cox regression models adjusted for sex and EGFR mutation status revealed that the risk of recurrence was reduced by 50% for the unit of one interquartile range (IQR) change in the tumoral T-cell (adjusted hazard ratio per IQR increase = 0.50, 95% confidence interval: 0.27-0.93) and decreased by 64% in mast cell density (adjusted hazard ratio per IQR increase = 0.36, confidence interval: 0.15-0.84). The analyses were reported without the type I error correction for the multiple types of immune cell testing.

Conclusions

Analysis of the density of immune cells within the tumor and surrounding stroma reveals an association between the density of T-cells and RFS and between mast cells and RFS in early-stage LUAD. This preliminary result is a limited study with a small sample size and a lack of an independent validation set.