Lung Mast Cells Research Articles

Detection of respiratory allergies caused by environmental chemical allergen via measures of hyper-activation and degranulation of mast cells in lungs of NC/Nga mice

Respiratory allergy triggered by exposure to environmental chemical allergen is a serious problem in many Asian countries and has the potential to cause severe health problems. Here, we aimed to elucidate the pathogenic mechanisms of this disease and develop an in vivo detection method for respiratory allergy induced by environmental chemical allergen. Both BALB/c and NC/Nga mice were sensitized topically for 3 weeks and were then subjected to inhalation challenge with pulverized trimellitic anhydride into particles measuring 2-μm in diameter. On the day after the final challenge, all mice were sacrificed, and IgE levels, immunocyte counts, and cytokine levels in the serum, hilar lymph nodes, and bronchoalveolar lavage fluid were measured. We also monitored the expression of genes encoding pro-inflammatory cytokines in the lung. We found that all endpoints were significantly increased in mice of both strains subjected to trimellitic anhydride inhalation as compared with the respective control groups. However, worsening of respiratory status was noted only in NC/Nga mice. Interestingly, type 2 helper T-cell reactions were significantly increased in BALB/c mice compared with that in NC/Nga mice. In contrast, the number of mast cells, levels of mast cell-related cytokine/chemokines, and production of histamine in NC/Nga mice were significantly higher than those in BALB/c mice. Thus, environmental chemical allergen induced respiratory allergy in NC/Nga mice in terms of functional and inflammatory symptoms. Furthermore, mast cells may be involved in the aggravation of airway allergic symptoms induced by environmental chemical allergens.

Cyclic nucleotide phosphodiesterase isoforms in human basophils and mast cells.

Cyclic nucleotide phosphodiesterase (PDE) exists as multiple molecular forms. Of the 11 families of PDE identified so far, PDE4, a cAMP-specific PDE, has been identified as the major isoform regulating inflammatory activity. The principle aim of the present study was to determine whether human basophils and human lung mast cells express PDE4. Four sub-classes of PDE4 (A, B, C, and D) have been identified and expression of these was determined by RT-CPR and by western blotting. In basophils, prominent expression of mRNA for PDE4A and PDE4D was observed whereas little if any expression of PDE4B and PDE4C was detected. These findings were paralleled by immunoblotting experiments as human basophils were found to express PDE4A and PDE4D with little evidence for the presence of either PDE4B or PDE4C. By contrast, human lung mast cells expressed very little, if any, mRNA for PDE4 sub-classes although, in some preparations, some modest levels of mRNA for PDE4D were detected. However, there was no evidence, at the protein level, that mast cells express PE4. Overall, these data indicate that basophils express PDE4 (4A and 4D) whereas human lung mast cells do not.

Identification of Biological and Pharmaceutical Mast Cell‐ and Basophil‐Related Targets

Identification of Biological and Pharmaceutical Mast Cell‐ and Basophil‐Related Targets

Daily global stress is associated with nocturnal asthma awakenings in school-age children

Daily global stress is associated with nocturnal asthma awakenings in school-age children

Lin− CD34hi CD117int/hi FcεRI+ cells in human blood constitute a rare population of mast cell progenitors

AbstractMast cells are rare tissue-resident immune cells that are involved in allergic reactions, and their numbers are increased in the lungs of asthmatics. Murine lung mast cells arise from committed bone marrow–derived progenitors that enter the blood circulation, migrate through the pulmonary endothelium, and mature in the tissue. In humans, mast cells can be cultured from multipotent CD34+ progenitor cells. However, a population of distinct precursor cells that give rise to mast cells has remained undiscovered. To our knowledge, this is the first report of human lineage-negative (Lin−) CD34hi CD117int/hi FcεRI+ progenitor cells, which represented only 0.0053% of the isolated blood cells in healthy individuals. These cells expressed integrin β7 and developed a mast cell–like phenotype, although with a slow cell division capacity in vitro. Isolated Lin− CD34hi CD117int/hi FcεRI+ blood cells had an immature mast cell–like appearance and expressed high levels of many mast cell–related genes as compared with human blood basophils in whole-transcriptome microarray analyses. Furthermore, serglycin, tryptase, and carboxypeptidase A messenger RNA transcripts were detected by quantitative reverse transcription–polymerase chain reaction. Altogether, we propose that the Lin− CD34hi CD117int/hi FcεRI+ blood cells are closely related to human tissue mast cells and likely constitute an immediate precursor population, which can give rise to predominantly mast cells. Furthermore, asthmatics with reduced lung function had a higher frequency of Lin− CD34hi CD117int/hi FcεRI+ blood mast cell progenitors than asthmatics with normal lung function.

Bidirectional Counterregulation of Human Lung Mast Cell and Airway Smooth Muscle β2 Adrenoceptors.

Human lung mast cells (HLMCs) play a central role in asthma pathogenesis through their relocation to the airway smooth muscle (ASM) bundles. β2 adrenoceptor (β2-AR)-agonists are used to relieve bronchoconstriction in asthma, but may reduce asthma control, particularly when used as monotherapy. We hypothesized that HLMC and human ASM cell (HASMC) responsiveness to β2-AR agonists would be attenuated when HLMCs are in contact with HASMCs. Cells were cultured in the presence of the short-acting β2-agonist albuterol, and the long-acting β2-agonists formoterol and olodaterol. Constitutive and FcεRI-dependent HLMC histamine release, HASMC contraction, and β2-AR phosphorylation at Tyr(350) were assessed. Constitutive HLMC histamine release was increased in HLMC-HASMC coculture and this was enhanced by β2-AR agonists. Inhibition of FcεRI-dependent HLMC mediator release by β2-agonists was greatly reduced in HLMC-HASMC coculture. These effects were reversed by neutralization of stem cell factor (SCF) or cell adhesion molecule 1 (CADM1). β2-AR agonists did not prevent HASMC contraction when HLMCs were present, but this was reversed by fluticasone. β2-AR phosphorylation at Tyr(350) occurred within 5 min in both HLMCs and HASMCs when the cells were cocultured, and was inhibited by neutralizing SCF or CADM1. HLMC interactions with HASMCs via CADM1 and Kit inhibit the potentially beneficial effects of β2-AR agonists on these cells via phosphorylation of the β2-AR. These results may explain the potentially adverse effects of β2-ARs agonists when used for asthma therapy. Targeting SCF and CADM1 may enhance β2-AR efficacy, particularly in corticosteroid-resistant patients.

Specific allergen immunotherapy attenuates allergic airway inflammation in a rat model of Alstonia scholaris pollen induced airway allergy

Pollen grains are well established to be an important cause of respiratory allergy. Current pharmacologic therapies for allergic asthma do not cure the disease. Allergen specific immunotherapy is the only treatment method which re-directs the immune system away from allergic response leading to a long lasting effect. The mechanism by which immunotherapy achieves this goal is an area of active research world-wide. The present experimental study was designed to develop an experimental model of allergic lung inflammation based on a relevant human allergen, Alstonia scholaris pollen, and to establish the immunological and cellular features of specific allergen immunotherapy using this same pollen extract. Our results revealed that Alstonia scholaris pollen sensitization and challenge causes eosinophilic airway inflammation with mucin hypersecretion. This is associated with increased total IgE, increased expression of FcɛRI on lung mast cells and increased levels of IL-4, IL-5 & IL-13 as confirmed by ELISA, in-situ immunofluorescence and FACS assay. Allergen specific immunotherapy reduced airway inflammation and also decreased total IgE level, FcɛRI expression, IL-4, IL-5 & IL-13 levels. It was further noted that the reduction of these levels was more by intra-nasal route than by intra-peritoneal route. Thus we present a novel animal model of Alstonia scholaris pollen allergic disease and specific allergen immunotherapy which will pave the way towards the development of better treatment modalities.

The expression differences of miRNA in lung tissue and mast cells of asthmatic mice

Objective To study miRNA expression differences in ovalbumin (OVA)-induced murine asthma models of mice and mast cells stimulated by inflammatory cytokines stimulation, and to better understand asthma deve-lopment so as to provide potential target for its prevention and treatment. Methods OVA-induced murine asthma models were validated by detecting cells in bronchoalveolar lavage fluid (BALF) and histopathology.And miRNA expression differences in the lung tissues between the model group and the normal control group were detected by real-time polymerose chain reaction PCR .After tumor necrosis factor-α(TNF-α), interleukin 12 (IL-12) stimulation, miRNA expression differences in murine mast cells P815 were detected. Results The number of total cells and eosinophil cells both increased in BALF of the model group [(12.8±2.2)×107 /L vs (5.6±2.5)×107 /L, t=4.760, P<0.05; (6.6±1.9)×107 /L vs (0.8±0.8)×107 /L, t=8.068, P<0.05]. In addition, histopathology showed more inflammatory cell infiltration in the model group than that in the normal control group, indicating that the models were validated.The expression of miRNA-155 was up-regulated approximately 5.0-fold in the lung tissues of the model group (P<0.05), while miRNA-192 showed no differences compared with the controls.After TNF-α and IL-12 stimulated P815 mast cells, miRNA-192 expressions in P815 were expression in P815 was up-regulated approximately 1.9-fold and 1.7-fold after TNF-α and IL-12 stimulation, respectively(P<0.05). Conclusions It is concluded that miRNAs are differentially expressed in the presence of OVA-induced murint asthma models and mast cells stimulated by inflammatory cytokines.These differentially expressed miRNAs may regulate the function of mast cells and involved in the pathogenesis of asthma. Key words: Asthma; miRNA; Mast cell; Inflammatory cytokines

Activation of the Prostaglandin E2 receptor EP2 prevents house dust mite-induced airway hyperresponsiveness and inflammation by restraining mast cells' activity.

Prostaglandin E2 (PGE2 ) has been proposed to exert antiasthmatic effects in patients, to prevent antigen-induced airway pathology in murine models, and to inhibit mast cells (MC) activity invitro. To assess in a murine model whether the protective effect of PGE2 may be a consequence of its ability to activate the E-prostanoid (EP)2 receptor on airway MC. Either BALB/c or C57BL/6 mice were exposed intranasally (i.n.) to house dust mite (HDM) aeroallergens. Both strains were given PGE2 locally (0.3mg/kg), but only BALB/c mice were administered butaprost (EP2 agonist: 0.3mg/kg), or AH6809 (EP2 antagonist; 2.5mg/kg) combined with the MC stabilizer sodium cromoglycate (SCG: 25mg/kg). Airway hyperresponsiveness (AHR) and inflammation, along with lung MC activity, were evaluated. In addition, butaprost's effect was assessed in MC-mediated passive cutaneous anaphylaxis (PCA) in mice challenged with 2,4-dinitrophenol (DNP). Selective EP2 agonism attenuated aeroallergen-caused AHR and inflammation in HDM-exposed BALB/c mice, and this correlated with a reduced lung MC activity. Accordingly, the blockade of endogenous PGE2 by means of AH6809 worsened airway responsiveness in sensitive BALB/c mice, and such worsening was reversed by SCG. The relevance of MC to PGE2 -EP2 driven protection was further highlighted in MC-dependent PCA, where butaprost fully prevented MC-induced ear swelling. Unlike in BALB/c mice, PGE2 did not protect the airways of HDM-sensitized C57BL/6 animals, a strain in which we showed MC to be irrelevant to aeroallergen-driven AHR and inflammation. The beneficial effect of both exogenous and endogenous PGE2 in aeroallergen-sensitized mice may be attributable to the activation of the EP2 receptor, which in turn acts as a restrainer of airway MC activity. This opens a path towards the identification of therapeutic targets against asthma along the 'EP2 -MC-airway' axis.

Orai/CRACM1 and KCa3.1 ion channels interact in the human lung mast cell plasma membrane.

BackgroundOrai/CRACM1 ion channels provide the major Ca2+ influx pathway for FcεRI-dependent human lung mast cell (HLMC) mediator release. The Ca2+-activated K+ channel KCa3.1 modulates Ca2+ influx and the secretory response through hyperpolarisation of the plasma membrane. We hypothesised that there is a close functional and spatiotemporal interaction between these Ca2+- and K+-selective channels.ResultsActivation of FcεRI-dependent HLMC KCa3.1 currents was dependent on the presence of extracellular Ca2+, and attenuated in the presence of the selective Orai blocker GSK-7975A. Currents elicited by the KCa3.1 opener 1-EBIO were also attenuated by GSK-7975A. The Orai1 E106Q dominant-negative mutant ablated 1-EBIO and FcεRI-dependent KCa3.1 currents in HLMCs. Orai1 but not Orai2 was shown to co-immunoprecipitate with KCa3.1 when overexpressed in HEK293 cells, and Orai1 and KCa3.1 were seen to co-localise in the HEK293 plasma membrane using confocal microscopy.ConclusionKCa3.1 activation in HLMCs is highly dependent on Ca2+ influx through Orai1 channels, mediated via a close spatiotemporal interaction between the two channels.

Evidence for a novel Kit adhesion domain mediating human mast cell adhesion to structural airway cells.

BackgroundHuman lung mast cells (HLMCs) infiltrate the airway epithelium and airway smooth muscle (ASM) in asthmatic airways. The mechanism of HLMC adhesion to both cell types is only partly defined, and adhesion is not inhibited by function-blocking anti-Kit and anti-stem cell factor (SCF) antibodies. Our aim was to identify adhesion molecules expressed by human mast cells that mediate adhesion to human ASM cells (HASMCs) and human airway epithelial cells.MethodsWe used phage-display to isolate single chain Fv (scFv) antibodies with adhesion-blocking properties from rabbits immunised with HLMC and HMC-1 membrane proteins.ResultsPost-immune rabbit serum labelled HLMCs in flow cytometry and inhibited their adhesion to human BEAS-2B epithelial cells. Mast cell-specific scFvs were identified which labelled mast cells but not Jurkat cells by flow cytometry. Of these, one scFv (A1) consistently inhibited mast cell adhesion to HASMCs and BEAS-2B epithelial cells by about 30 %. A1 immunoprecipitated Kit (CD117) from HMC-1 lysates and bound to a human Kit-expressing mouse mast cell line, but did not interfere with SCF-dependent Kit signalling.ConclusionKit contributes to human mast cell adhesion to human airway epithelial cells and HASMCs, but may utilise a previously unidentified adhesion domain that lies outside the SCF binding site. Targeting this adhesion pathway might offer a novel approach for the inhibition of mast cell interactions with structural airway cells, without detrimental effects on Kit signalling in other tissues.

EPS06.2 Immune cell localization in different compartments of human end-stage CF lungs

Objectives The localization of immune cells along airways, blood vessels or in parenchyma in CF lung disease has insufficiently been established. A comprehensive quantitative immunohistochemical analysis was performed on lung tissue from CF patients and healthy controls (HC). Methods Sections (8 mm) of lung biopsies of CF patients taken during transplantation (n = 20) and control lung biopsies (n = 22) were stained for Th-lymphocytes (CD4), mast cells (tryptase) and eosinophils (EG-2). Quantification was performed by counting all single cells normalized over total area (mm 2 ) of biopsy (Th cells), or in 10 high power fields averaged per compartment (airways, blood vessels and parenchyma) per subject (mast cells and eosinophils). Results CD4+ T-lymphocyte counts were significantly increased in CF vs. HC (p = 0.001) and were present as dispersed single cells (CF & HC), or organized in follicles mainly situated in parenchyma (predominantly CF). Both total & compartmental mast cell counts were significantly increased in CF vs. HC (all p Conclusion There is an increased presence of Th lymphocytes and mast cells in the end-stage CF lung, albeit in different compartments of the lung. Inflammation was more severe in female CF patients irrespective of FEV 1 , colonization status or genotype, corroborating previous data suggesting a direct deleterious effect of female hormone on inflammation in the CF lung.

20(S)-Protopanaxatriol inhibits release of inflammatory mediators in immunoglobulin E-mediated mast cell activation

BackgroundAntiallergic effect of 20(S)-protopanaxatriol (PPT), an intestinal metabolite of ginseng saponins, was investigated in guinea pig lung mast cells and mouse bone marrow-derived mast cells activated by a specific antigen/antibody reaction. MethodsIncreasing concentrations of PPT were pretreated 5min prior to antigen stimulation, and various inflammatory mediator releases and their relevant cellular signaling events were measured in those cells. ResultsPPT dose-dependently reduced the release of histamine and leukotrienes in both types of mast cells. Especially, in activated bone marrow-derived mast cells, PPT inhibited the expression of Syk protein, cytokine mRNA, cyclooxygenase-1/2, and phospholipase A2 (PLA2), as well as the activities of various protein kinase C isoforms, mitogen-activated protein kinases, PLA2, and transcription factors (nuclear factor-κB and activator protein-1). ConclusionPPT reduces the release of inflammatory mediators via inhibiting multiple cellular signaling pathways comprising the Ca2+ influx, protein kinase C, and PLA2, which are propagated by Syk activation upon allergic stimulation of mast cells.

Prostaglandin E2 prevents hyperosmolar-induced human mast cell activation through prostanoid receptors EP2 and EP4.

BackgroundMast cells play a critical role in allergic and inflammatory diseases, including exercise-induced bronchoconstriction (EIB) in asthma. The mechanism underlying EIB is probably related to increased airway fluid osmolarity that activates mast cells to the release inflammatory mediators. These mediators then act on bronchial smooth muscle to cause bronchoconstriction. In parallel, protective substances such as prostaglandin E2 (PGE2) are probably also released and could explain the refractory period observed in patients with EIB.ObjectiveThis study aimed to evaluate the protective effect of PGE2 on osmotically activated mast cells, as a model of exercise-induced bronchoconstriction.MethodsWe used LAD2, HMC-1, CD34-positive, and human lung mast cell lines. Cells underwent a mannitol challenge, and the effects of PGE2 and prostanoid receptor (EP) antagonists for EP1–4 were assayed on the activated mast cells. Beta-hexosaminidase release, protein phosphorylation, and calcium mobilization were assessed.ResultsMannitol both induced mast cell degranulation and activated phosphatidyl inositide 3-kinase and mitogen-activated protein kinase (MAPK) pathways, thereby causing de novo eicosanoid and cytokine synthesis. The addition of PGE2 significantly reduced mannitol-induced degranulation through EP2 and EP4 receptors, as measured by beta-hexosaminidase release, and consequently calcium influx. Extracellular-signal-regulated kinase 1/2, c-Jun N-terminal kinase, and p38 phosphorylation were diminished when compared with mannitol activation alone.ConclusionsOur data show a protective role for the PGE2 receptors EP2 and EP4 following osmotic changes, through the reduction of human mast cell activity caused by calcium influx impairment and MAP kinase inhibition.

Inhibition of TRPM7 Channels Reduces Degranulation and Release of Cytokines in Rat Bone Marrow-Derived Mast Cells

Background: mast cells play an important role in airway inflammation in asthma. The transient receptor potential melastatin-like 7 (TRPM7) channel is expressed in primary human lung mast cells and plays a critical role for cell survival. This study aimed to investigate the role of TRPM7 on degranulation and release of cytokines in rat bone marrow-derived mast cells (BMMCs). Methods: the expression levels of TRPM7 were observed by immunocytochemistry and RT-PCR between normal and asthmatic rat BMMCs. TRPM7-specific shRNA and 2-aminoethoxydiphenyl borate (2-APB) and specific shTRPM7 were used to inhibit the function of TRPM7. Degranulation levels were analyzed by beta-hexosaminidase assay. Histamine, TNF-α, IL-6 and IL-13 levels were measured by ELISA. Results: the expression of TRPM7 was significantly higher in asthmatic rat BMMCs than in the normal control group. After application of 2-APB and down-regulation of TRPM7, the beta-hexosaminidase activity and secretion of histamine, IL-6, IL-13 and TNF-α were significantly decreased in the asthmatic group compared to the control group. Conclusion: this study indicates that TRPM7 channels may be involved in the process of degranulation and release of cytokines in rat bone marrow-derived mast cells.

Mast Cells in a Murine Lung Ischemia-Reperfusion Model of Primary Graft Dysfunction.

Primary graft dysfunction (PGD), as characterized by pulmonary infiltrates and high oxygen requirements shortly after reperfusion, is the major cause of early morbidity and mortality after lung transplantation. Donor, recipient and allograft-handling factors are thought to contribute, although new insights regarding pathogenesis are needed to guide approaches to prevention and therapy. Mast cells have been implicated in ischemic tissue injury in other model systems and in allograft rejection, leading to the hypothesis that mast cell degranulation contributes to lung injury following reperfusion injury. We tested this hypothesis in a mouse model of PGD involving a unilateral hilar clamp for 1 hour followed by 4 hours of reperfusion. Metrics of injury included albumin permeability, plasma extravasation, lung histopathology, and mast cell degranulation. Responses were assessed in wild type (Kit+/+) and mast cell-deficient (KitW-sh/W-sh) mice. Because mouse lungs have few mast cells compared with human lungs, we also tested responses in mice with lung parenchyma “humanized” by injecting bone marrow-derived cultured mast cells (BMCMC). We found that ischemic lung responses of mast cell-deficient KitW-sh/W-sh mice did not differ from those of Kit+/+ mice, even after priming for injury using LPS. Degranulated mast cells were more abundant in ischemic than in non-ischemic BMCMC-injected KitW-sh/W-sh lungs. However, lung injury in BMCMC-injected KitW-sh/W-sh and Kit+/+ mice did not differ in globally mast cell-deficient, uninjected KitW-sh/W-sh mice or in wild-type Kit+/+ mice relatively deficient in lung mast cells. These findings predict that mast cells, although activated in lungs injured by ischemia and reperfusion, are not necessary for the development of PGD.

A steroid-mimicking nanomaterial that mediates inhibition of human lung mast cell responses (IRM9P.725)

Abstract Water-soluble fullerenes can be engineered to regulate activation of mast cells (MC) and control MC-driven diseases in vivo. To further understand their anti-inflammatory mechanisms a C70-based fullerene conjugated to four myo-inositol molecules (C70-I) was examined in vitro for its effects on the signaling pathways leading to mediator release from human lung MC. The C70-I fullerene stabilize MC and act synergistically with long-acting β2-adrenergic receptor agonists (LABA) to enhance inhibition of MC mediator release through FcεRI-simulation. The inhibition was paralleled by the upregulation of dual-specificity phosphatase one (DUSP1) gene and protein levels. Concomitantly, increases in MAPK were blunted in C70-I treated cells. The increase in DUSP1 expression was due to the ability of C70-I to prevent the ubiquitination and degradation of DUSP1. These findings identify a mechanism of how fullerenes inhibit inflammatory mediator release from MC and suggest they could potentially be an alternative therapy for steroid resistant asthmatics.

Histone Deacetylase-3 Mediates Positive Feedback Relationship between Anaphylaxis and Tumor Metastasis

Allergic inflammation has been known to enhance the metastatic potential of tumor cells. The role of histone deacetylase-3 (HDAC3) in allergic skin inflammation was reported. We investigated HDAC3 involvement in the allergic inflammation-promotion of metastatic potential of tumor cells. Passive systemic anaphylaxis (PSA) induced HDAC3 expression and FcεRI signaling in BALB/c mice. PSA enhanced the tumorigenic and metastatic potential of mouse melanoma cells in HDAC3- and monocyte chemoattractant protein 1-(MCP1)-dependent manner. The PSA-mediated enhancement of metastatic potential involved the induction of HDAC3, MCP1, and CD11b (a macrophage marker) expression in the lung tumor tissues. We examined an interaction between anaphylaxis and tumor growth and metastasis at the molecular level. Conditioned medium from antigen-stimulated bone marrow-derived mouse mast cell cultures induced the expression of HDAC3, MCP1, and CCR2, a receptor for MCP1, in B16F1 mouse melanoma cells and enhanced migration and invasion potential of B16F1 cells. The conditioned medium from B16F10 cultures induced the activation of FcεRI signaling in lung mast cells in an HDAC3-dependent manner. FcεRI signaling was observed in lung tumors derived from B16F10 cells. Target scan analysis predicted HDAC3 to be as a target of miR-384, and miR-384 and HDAC3 were found to form a feedback regulatory loop. miR-384, which is decreased by PSA, negatively regulated HDAC3 expression, allergic inflammation, and the positive feedback regulatory loop between anaphylaxis and tumor metastasis. We show the miR-384/HDAC3 feedback loop to be a novel regulator of the positive feedback relationship between anaphylaxis and tumor metastasis.

A steroid-mimicking nanomaterial that mediates inhibition of human lung mast cell responses

Water-soluble fullerenes can be engineered to regulate activation of mast cells (MC) and control MC-driven diseases in vivo. To further understand their anti-inflammatory mechanisms a C70-based fullerene conjugated to four myo-inositol molecules (C70-I) was examined in vitro for its effects on the signaling pathways leading to mediator release from human lung MC. The C70-I fullerene stabilizes MC and acts synergistically with long-acting β2-adrenergic receptor agonists (LABA) to enhance inhibition of MC mediator release through FcεRI-simulation. The inhibition was paralleled by the upregulation of dual-specificity phosphatase one (DUSP1) gene and protein levels. Concomitantly, increases in MAPK were blunted in C70-I treated cells. The increase in DUSP1 expression was due to the ability of C70-I to prevent the ubiquitination and degradation of DUSP1. These findings identify a mechanism of how fullerenes inhibit inflammatory mediator release from MC and suggest they could potentially be an alternative therapy for steroid resistant asthmatics. From the Clinical EditorThis study investigates the role and mechanism of action of fullerenes in deactivating mast cell-based inflammation, paving the way to the development of a novel, non-steroid therapy in reactive airway disease.

Human Lung Mast Cell Products Regulate Airway Smooth Muscle CXCL10 Levels

In asthma, the airway smooth muscle (ASM) produces CXCL10 which may attract CXCR3+ mast/T cells to it. Our aim was to investigate the effects of mast cell products on ASM cell CXCL10 production. ASM cells from people with and without asthma were stimulated with IL-1β, TNF-α, and/or IFNγ and treated with histamine (1–100 μM) ± chlorpheniramine (H1R antagonist; 1 μM) or ranitidine (H2R antagonist; 50 μM) or tryptase (1 nM) ± leupeptin (serine protease inhibitor; 50 μM), heat-inactivated tryptase, or vehicle for 4 h or 24 h. Human lung mast cells (MC) were isolated and activated with IgE/anti-IgE and supernatants were collected after 2 h or 24 h. The supernatants were added to ASM cells for 48 h and ASM cell CXCL10 production detected using ELISA (protein) and real-time PCR (mRNA). Histamine reduced IL-1β/TNF-α-induced CXCL10 protein, but not mRNA, levels independent of H1 and H2 receptor activation, whereas tryptase and MC 2 h supernatants reduced all cytokine-induced CXCL10. Tryptase also reduced CXCL10 levels in a cell-free system. Leupeptin inhibited the effects of tryptase and MC 2 h supernatants. MC 24 h supernatants contained TNF-α and amplified IFNγ-induced ASM cell CXCL10 production. This is the first evidence that MC can regulate ASM cell CXCL10 production and its degradation. Thus MC may regulate airway myositis in asthma.