A monoclonal antibody to Siglec-8 suppresses non-allergic airway inflammation and inhibits IgE-independent mast cell activation.
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ABSTRACT:
SUBMITTER: Schanin J
PROVIDER: S-EPMC7946634 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Increased asthma severity is not only associated with enhanced recurrent hospitalization and mortality but also with higher social costs. Several cases of asthma are atopic in nature, with the trigger for acute asthma attacks and chronic worsening of inflammation being allergens inducing an immune, IgE mediated response. Anti-inflammatory treatments are effective for most of asthma patients, but there are subjects whose disease is incompletely controlled by inhaled or systemic corticosteroids and these patients account for about 50% of the healthcare costs of asthma. Omalizumab is a biological engineered, humanized recombinant monoclonal anti-IgE antibody developed for the treatment of allergic diseases and with clear efficacy in adolescent and adult patients with severe allergic asthma. The anti-IgE antibody inhibits IgE functions blocking free serum IgE and inhibiting their binding to cellular receptors. By reducing serum IgE levels and IgE receptor expression on inflammatory cells in the context of allergic cascade, omalizumab has demonstrated to be a very useful treatment of atopic asthma, improving quality of life of patients with severe persistent allergic asthma that is inadequately controlled by currently available asthma medications. Several trials have demonstrated that this therapy is well tolerated and significantly improves symptoms and disease control, reducing asthma exacerbations and the need to use high dosage of inhaled corticosteroids.
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Project description:Eucalyptus oil has been used since ancient times for its bactericidal, anti-inflammatory, analgesic and sedative effects. In recent years, the action of Eucalyptus oil has been scientifically proven, and there have been reports that Eucalyptus oil suppresses the production of chemokines, cytokines and lipid mediators in basophils, alveolar macrophages and monocytes. Based on this information, we aimed to verify whether Eucalyptus oil can be used for allergic dermatitis, the incidence of which has been increasing among human skin diseases. This effect was verified using a mouse IgE-mediated local allergic model. In conclusion, topical application of Eucalyptus oil suppressed oedema and vascular permeability enhancement due to IgE-mediated allergic on the skin. In addition, we also verified the degranuration of mast cells, which is a part of its action, and examined whether 1,8-cineole, which is the main component of Eucalyptus oil, suppresses the phosphorylation of PLCγ and p38 directly or indirectly. 1,8-cineole was found to suppress degranulation of mast cells.
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Project description:PurposeAsthma is a complex, heterogeneous chronic inflammatory airway disease with multiple phenotypes. There has been a great progress in managing asthma, but there are still unmet needs for developing uncontrolled asthma treatments. The present study aimed to determine the effectiveness of oleanolic acid acetate (OAA) from Vigna angularis against allergic airway inflammation and the underlying mechanism of action with a focus on mast cells.MethodsTo investigate the effect of OAA in allergic airway inflammation, we used the ovalbumin (OVA)-sensitized and challenged mice. To examine allergic airway inflammation associated with immune responses of mast cell activation in vitro, various types of mast cells were used. Systemic and cutaneous anaphylaxis models were used for mast cell-mediated hyper-responsiveness in vivo.ResultsOAA reduced OVA-induced airway inflammatory responses such as bronchospasm, increase of immune cell infiltration and serum immunoglobulin E and G1 levels. Especially, OAA decreased the mast cell infiltration, and β-hexosaminidase release as a mast cell activation marker in the bronchoalveolar lavage fluid. OAA inhibited mast cell degranulation in mast cell line (RBL-2H3) and primary cells (rat peritoneal mast cell and mouse bone marrow-derived mast cell). Mechanistically, OAA suppressed intracellular signaling pathways including the phosphorylation of phospholipase Cγ and nuclear factor-κB, resulting from the suppression of intracellular calcium influx and pro-inflammatory cytokine expression. Further, oral administration of OAA attenuated mast cell-mediated systemic and cutaneous anaphylaxis.ConclusionsOur study showed that OAA can inhibit mast cell-mediated allergic reaction. Consequently, the application of OAA to mast cells for the allergic airway inflammation facilitate a new direction of treating allergic asthma.
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Project description:The epithelial lining of the airway tract and allergen-specific IgE are considered essential controllers of inflammatory responses to allergens. The human low affinity IgE receptor, CD23 (Fc?RII), is capable of transporting IgE or IgE-allergen complexes across the polarized human airway epithelial cell (AEC) monolayer in vitro. However, it remains unknown whether the CD23-dependent IgE transfer pathway in AECs initiates and facilitates allergic inflammation in vivo, and whether inhibition of this pathway attenuates allergic inflammation. To this end, we show that in wild-type (WT) mice, epithelial CD23 transcytosed both IgE and ovalbumin (OVA)-IgE complexes across the airway epithelial barrier, whereas neither type of transcytosis was observed in CD23 knockout (KO) mice. In chimeric mice, OVA sensitization and aerosol challenge of WT/WT (bone-marrow transfer from the WT to WT) or CD23KO/WT (CD23KO to WT) chimeric mice, which express CD23 on radioresistant airway structural cells (mainly epithelial cells) resulted in airway eosinophilia, including collagen deposition and a significant increase in goblet cells, and increased airway hyperreactivity. In contrast, the absence of CD23 expression on airway structural or epithelial cells, but not on hematopoietic cells, in WT/CD23KO (the WT to CD23KO) chimeric mice significantly reduced OVA-driven allergic airway inflammation. In addition, inhalation of the CD23-blocking B3B4 antibody in sensitized WT mice before or during airway challenge suppressed the salient features of asthma, including bronchial hyperreactivity. Taken together, these results identify a previously unproven mechanism in which epithelial CD23 plays a central role in the development of allergic inflammation. Further, our study suggests that functional inhibition of CD23 in the airway is a potential therapeutic approach to inhibit the development of asthma.
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Project description:BackgroundClinical and experimental analyses have identified a central role for IgE/FcεRI/mast cells in promoting IgE-mediated anaphylaxis. Recent data from human studies suggest that bacterial infections can alter susceptibility to anaphylaxis.ObjectiveWe examined the effect of LPS exposure on the induction of IgE-mast cell (MC) mediated reactions in mice.MethodsC57BL/6 WT, tlr4-/- and IL10-/- mice were exposed to LPS, and serum cytokines (TNF and IL-10) were measured. Mice were subsequently treated with anti-IgE, and the symptoms of passive IgE-mediated anaphylaxis, MC activation, Ca2+ -mobilization and the expression of FcεRI on peritoneal MCs were quantitated.ResultsWe show that LPS exposure of C57BL/6 WT mice constraints IgE-MC-mediated reactions. LPS-induced suppression of IgE-MC-mediated responses was TLR-4-dependent and associated with increased systemic IL-10 levels, decreased surface expression of FcεRI on MCs and loss of sensitivity to IgE activation. Notably, LPS-induced desensitization of MCs was short term with MC sensitivity to IgE reconstituted within 48 hours, which was associated with recapitulation of FcεRI expression on the MCs. Mechanistic analyses revealed a requirement for IL-10 in LPS-mediated decrease in MC FcεRI surface expression.Conclusions & clinical relevanceCollectively, these studies suggest that LPS-induced IL-10 promotes the down-regulation of MC surface FcεRI expression and leads to desensitization of mice to IgE-mediated reactions. These studies indicate that targeting of the LPS-TLR-4-IL-10 pathway may be used as a therapeutic approach to prevent adverse IgE-mediated reactions.
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Project description:BackgroundPatients with eosinophilic esophagitis have increased numbers of mucosal mast cells. Administration of the proton pump inhibitor omeprazole can reduce both esophageal mast cell and eosinophil numbers and attenuate type 2 inflammation in these subjects.ObjectiveGiven that maintenance of an acidic environment within granules is important for mast cell homeostasis, we sought to evaluate the effects of omeprazole on mast cell functions including development, IgE:FcεRI-mediated activation, and responses to food allergen.MethodsMast cell degranulation, cytokine secretion, and early signaling events in the FcεRI pathway, including protein kinase phosphorylation and Ca2+ flux, were measured after IgE crosslinking in murine bone marrow-derived mast cells and human cord blood-derived mast cells. The effects of omeprazole on these responses were investigated as was its impact on mast cell-dependent anaphylaxis and food allergy phenotypes in vivo.ResultsMurine and human mast cells treated with omeprazole exhibited diminished degranulation and release of cytokines and histamine in response to allergen. In murine mast cells, phosphorylation of protein kinases, ERK and SYK, was decreased. Differentiation of mast cells from bone marrow progenitors was also inhibited. IgE-mediated passive anaphylaxis was blunted in mice treated with omeprazole as was allergen-induced mast cell expansion and mast cell activation in the intestine in a model of food allergy.ConclusionsOur findings suggest that omeprazole targets pathways important for the differentiation and activation of murine mast cells and for the manifestations of food allergy and anaphylaxis.
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Project description:BackgroundSialic acid-binding immunoglobulin-like lectin (Siglec)-8 is expressed on mast cells and eosinophils, but information about Siglec-8 expression and function in the lung is limited. A humanized antibody, AK002, targeting Siglec-8 is undergoing development for treatment of diseases associated with mast cell and eosinophil-driven inflammation.ObjectiveTo characterize Siglec-8 expression in the airway in asthma and determine whether antibodies that target Siglec-8 (S8mAbs) can decrease airway eosinophils in asthma or inhibit lung mast cell activation.MethodsGene expression profiling and flow cytometry were used to characterize Siglec-8 expression in sputum cells from stable asthma. An antibody-dependent cellular cytotoxicity (ADCC) assay was used to determine whether an S8mAb can decrease eosinophils in sputum from asthma patients ex vivo. A mast cell activation assay was used to determine whether an S8mAb can inhibit mast cell activation in human lung tissue ex vivo.ResultsGene expression for Siglec-8 is increased in sputum cells in asthma and correlates with gene expression for eosinophils and mast cells. Gene expression for Siglec-8 is inversely and significantly correlated with measures of airflow obstruction in asthma patients. Siglec-8 is prominently expressed on the surface of eosinophils and mast cells in sputum. S8mAbs decrease eosinophils in sputum from patients with asthma and inhibit FcεR1-activated mast cells in lung tissues.Conclusions and clinical relevanceSiglec-8 is highly expressed on eosinophils and mast cells in asthmatic sputum and targeting Siglec-8 with an antibody is a plausible strategy to decrease sputum eosinophils and inhibit lung mast cells in asthma.
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Project description:BackgroundDJ-1 is an antioxidant protein known to reduce levels of reactive oxygen species (ROS), but its presence or function in mast cells and allergic diseases is unknown.ObjectivesWe sought to determine the role and mechanism of DJ-1 in allergic responses in vitro and in vivo.MethodsROS and DJ-1 levels in serum or culture medium were measured with ELISA kits. The role of DJ-1 was evaluated in mast cell cultures and passive cutaneous anaphylaxis in normal or DJ-1 knockout (KO) mice. The mechanism of DJ-1 action was examined by using immunoblotting, immunoprecipitation, RT-PCR, and other molecular biological approaches.ResultsPatients with atopic dermatitis had increased levels of ROS and diminished levels of DJ-1. DJ-1 KO mice exhibited enhanced passive cutaneous anaphylaxis and augmented ROS levels in sera and bone marrow-derived mast cells (BMMCs). Furthermore, antigen-induced degranulation and production of TNF-? and IL-4 were significantly amplified in DJ-1 KO and anti-DJ-1 small interfering RNA-transfected BMMCs compared with that seen in wild-type (WT) BMMCs. Studies with these cells and BMMCs transfected with small interfering RNAs against the phosphatases Src homology domain 2-containing protein tyrosine phosphatase (SHP) 1 and SHP-2 revealed that the DJ-1 KO phenotype could be attributed to suppression of SHP-1 activity and enhancement of SHP-2 activity, leading to strengthened signaling through linker for activation of T cells, phospholipase C?, and mitogen-activated protein kinases.ConclusionsA deficiency or constitutive activation of DJ-1 can have implications in mast cell-driven allergic diseases, such as asthma and anaphylaxis.
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Project description:BackgroundSince food avoidance is currently the only way to prevent allergic reactions to shrimp, a better understanding of molecular events in the induction and progression of allergy, including food allergy, is needed for developing strategies to inhibit allergic responses. Pentraxin 3 (PTX3) is rapidly produced directly from inflammatory or damaged tissues and is involved in acute immunoinflammatory responses. However, the role of PTX3 in the development of immediate IgE-mediated shrimp allergy remains unknown.MethodsWild-type BALB/c mice were immunized intraperitoneally and were challenged with shrimp extract. Serum IgE and PTX3 levels were analyzed. RBL-2H3 cells were stimulated with either dinitrophenyl (DNP) or serum of shrimp-allergic mice, and markers of degranulation, proinflammatory mediators, and phosphorylation of signal proteins were analyzed. We further examined the effect of PTX3 in shrimp extract-induced allergic responses in vitro and in vivo.ResultsMice with shrimp allergy had increased PTX3 levels in the serum and small intestine compared with healthy mice. PTX3 augmented degranulation, the production of proinflammatory mediators, and activation of the Akt and MAPK signaling pathways in mast cells upon DNP stimulation. Furthermore, the expression of transcription factor CCAAT/enhancer-binding protein delta (CEBPD) was elevated in PTX3-mediated mast cell activation. Finally, the PTX3 inhibitor RI37 could attenuate PTX3-induced degranulation, proinflammatory mediator expression, and phosphorylation of the Akt and MAPK signaling.ConclusionsThe results suggested that PTX3 can facilitate allergic responses. Our data provide new insight to demonstrate that PTX3 is a cause of allergic inflammation and that RI37 can serve as a therapeutic agent in shrimp allergy.
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Project description:Calcium-activated potassium ion channel-3.1 (KCa3.1) plays a pivotal role in the potassium-calcium exchange involved in atopy. This study aimed to explore the impact of lentiviral-mediated shRNA silencing KCa3.1 on allergic response in a murine allergic rhinitis (AR) model. The BALB/c mice were divided into four groups: untreated AR group, negative control AR group, lentiviral KCa3.1-shRNA treated AR group and normal control group. Concentrations of ovalbumin (OVA)-specific IgE, histamine and leukotrienes C4 (LTC4) in serum, and IL-4, IL-9 and IL-17 in nasal lavage fluid (NLF) were analyzed. Goblet cells and mast cells were counted. KCa3.1 positive cells were counted after immunolabelling by immunofluorescence method. KCa3.1, Mucin 5AC (MUC5AC), and tryptase mRNA levels were determined using real-time polymerase chain reaction. Furthermore, P815 cell line was used to explore the role and mechanism of lentiviral KCa3.1-shRNA on mast cells. The results showed that LV-KCa3.1-shRNA intervention effectively attenuated allergic responses in LV-KCa3.1-shRNA treated mice. LV-KCa3.1-shRNA intervention effectively suppressed KCa3.1 levels and phosphorylation of AKT in P815 cells, leading to the downregulation of tryptase, IL-6 and IL-8 levels. LV-KCa3.1-shRNA intervention effectively attenuated the allergic responses in AR and suppressed mast cell activity by inhibiting PI3K/AKT signaling pathway.
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