Project description:Mast cells, activated by antigen via the high affinity receptor for IgE (FcεRI), release an array of pro-inflammatory mediators that contribute to allergic disorders such as asthma and anaphylaxis. The KIT ligand, stem cell factor (SCF), is critical for mast cell expansion, differentiation and survival, and, under acute conditions, enhances mast cell activation. However, extended SCF exposure in vivo conversely protects against fatal antigen-mediated anaphylaxis. In investigating this dichotomy, we identified a novel mode of regulation of the mast cell activation phenotype through SCF-mediated programming. We found that mouse bone marrow-derived mast cells chronically exposed to SCF displayed a marked attenuation of FcεRI-mediated degranulation and cytokine production. The hypo-responsive phenotype was not a consequence of altered signals regulating calcium flux or protein kinase C, but of ineffective cytoskeletal reorganization, with evidence implicating a down-regulation of expression of the Src kinase Hck. Collectively, these findings demonstrate a major role for SCF in the homeostatic control of mast cell activation with potential relevance to mast cell-driven disease and the development of novel approaches for the treatment of allergic disorders. Mouse bone marrow-derived mast cells were treated with IL3, IL3+IL33, or IL3+SCF. Six replicates each.
Project description:Mast cells, activated by antigen via the high affinity receptor for IgE (FcεRI), release an array of pro-inflammatory mediators that contribute to allergic disorders such as asthma and anaphylaxis. The KIT ligand, stem cell factor (SCF), is critical for mast cell expansion, differentiation and survival, and, under acute conditions, enhances mast cell activation. However, extended SCF exposure in vivo conversely protects against fatal antigen-mediated anaphylaxis. In investigating this dichotomy, we identified a novel mode of regulation of the mast cell activation phenotype through SCF-mediated programming. We found that mouse bone marrow-derived mast cells chronically exposed to SCF displayed a marked attenuation of FcεRI-mediated degranulation and cytokine production. The hypo-responsive phenotype was not a consequence of altered signals regulating calcium flux or protein kinase C, but of ineffective cytoskeletal reorganization, with evidence implicating a down-regulation of expression of the Src kinase Hck. Collectively, these findings demonstrate a major role for SCF in the homeostatic control of mast cell activation with potential relevance to mast cell-driven disease and the development of novel approaches for the treatment of allergic disorders.
Project description:Mast cells produce a large amount of several chemokines after cross-linking of FceRI and participate in the pathogenesis of allergic diseases. The objective of this study was to comprehensively investigate FceRI-mediated chemokine induction in human mast cells and the effect of a corticosteroid (dexamethasone) and a calcineurin inhibitor (FK506). Human peripheral blood-derived mast cells were stimulated with anti-IgE antibody in the presence of dexamethasone or FK506. Expression of eight chemokines was significantly induced in mast cells by anti-IgE stimulation. Induction of CCL2, CCL7, CXCL3 and CXCL8 by anti-IgE was significantly inhibited by dexamethasone. In contrast, induction of CCL1, CCL3, CCL4 and CCL18 was significantly inhibited by FK506. Combination of dexamethasone and FK506 suppressed production of all chemokines by anti-IgE stimulation. These results suggest that corticosteroids and calcineurin inhibitors inhibit expression of distinct subsets of chemokines and a combination of these drugs almost completely suppresses the induction of all chemokine genes in human mast cells in response to FceRI-dependent stimulation. Human peripheral blood-derived mast cells were stimulated with anti-IgE antibody in the presence of dexamethasone or FK506. Gene expression profiles were evaluated using GeneChip Human Genome U133 plus 2.0 probe arrays (Affymetrix).
Project description:Immunoglobulin (Ig) E-mediated activation of mast cells and basophils underlies allergic diseases such as asthma. Histamine-releasing factor (HRF), also known as translationally controlled tumor protein (TCTP) and fortilin, is a highly conserved protein with both intracellular and extracellular functions. Secreted HRF can stimulate histamine release and IL-4 and IL-13 production from IgE-sensitized basophils and mast cells. HRF is found in nasal, skin blister and bronchoalveolar lavage (BAL) fluids during late-phase allergic reactions (LPRs), which implicates HRF in the LPR and chronic allergic inflammation. Here we identify a subset of IgE and IgG antibodies as HRF-interacting molecules. HRF can exist as a dimer and bind to immunoglobulins (Igs) via interactions of its N-terminal and internal regions with the Fab region of Igs. Therefore, HRF together with HRF-reactive IgE can activate mast cells in vitro. The Ig-interacting HRF peptides that block HRF-Ig interactions can inhibit IgE+HRF-induced mast cell activation and in vivo cutaneous anaphylaxis and airway inflammation. Intranasally administered HRF can recruit inflammatory immune cells to the lung in naïve mice in a mast cell- and Fc receptor-dependent manner. These results strongly suggest the proinflammatory role of HRF in asthma and skin immediate hypersensitivity. A total of 6 samples were analyzed; wild type C57BL/6, FcRg KO and FceRIa KO mice were challenged with PBS (control) or mouse histamien-releasing factor
Project description:Summary: Long-lived IgE plasma cells reside in the bone marrow of allergic mice and atopic humans, confer IgE serological memory and produce allergen-specific IgE that can drive anaphylaxis. Abstract: Immunoglobulin E (IgE) plays an important role in allergic diseases. Nevertheless, the source of IgE serological memory remains controversial. We re-examined the mechanism of serological memory in allergy using a dual-reporter system to track IgE plasma cells (PCs) in mice. Short-term allergen exposure resulted in the generation of IgE plasma cells that resided mainly in secondarylymphoid organs and produced IgE that was unable to degranulate mast cells. In contrast, chronic allergen exposure led to the generation of long-lived IgE plasma cells that were primarily derived from sequential class switching of IgG1, accumulated in the bone marrow (BM) and produced IgE capable of inducing anaphylaxis. Most importantly, IgE plasma cells were found in the BM of human allergic, but not non-allergic donors, and allergen-specific IgE produced by these cells was able to induce mast cell degranulation when transferred to mice. These data demonstrate that longlived IgE BMPCs arise during chronic allergen exposure and establish serological memory in both mice and humans.
Project description:Purpose:The goal of this study is to asses the gene expression changes in non-stimulated mast cell and anti-IgE-stimulated mast cell Methods:RBL-2H3 mRNA profiles of non-stimulated mast cell and anti-IgE-stimulated mast cell were generated by deep sequencing, in triplicate. Differential expression analysis was performed using the DESeq2(v1.4.5) with Q value ≦0.05, following the heatmap was drawn by pheatmap(v1.0.8) . Results:Compared with non-stimulated mast cell, anti-IgE-stimulated mast cell induced a robust transcriptional response, with 191 differentially expressed genes following anti-IgE treatment (116 upregulated and 75 downregulated). Among the up-regulated genes. Conclusions:Our study represents the first detailed analysis of RBL-2H3 transcriptomes, with biologic replicates, generated by RNA-seq technology.
Project description:Experimental IgE-mediated food allergy depends on intestinal anaphylaxis driven by interleukin (IL)-9. However, the primary cellular source of IL-9 and the mechanisms underlying the susceptibility to food-induced intestinal anaphylaxis remain unclear. Herein, we have reported the identification of multifunctional IL-9-producing mucosal mast cells (MMC9s) that can secrete prodigious amounts of IL-9 and IL-13 in response to IL-33, and mast cell protease-1 (MCPt-1) in response to antigen and IgE complex crosslinking, respectively. Repeated intragastric antigen challenge induced MMC9 development that required T cells, IL-4, and STAT6 transcription factor, but not IL-9 signals. Mice ablated of MMC9 induction failed to develop intestinal mastocytosis, which resulted in decreased food allergy symptoms that could be restored by adoptively transferred MMC9s. Finally, atopic patients that developed food allergy displayed increased intestinal expression of Il9 and MC-specific transcripts. Thus, the induction of MMC9s is a pivotal step to acquire the susceptibility to IgE-mediated food allergy. dUTP mRNA-Seq profiles of indicated hematopoietic cell lineages were generated on Illumina HiSeq2500. Hematopoietic cells were isolated from Balb/C mice that developed food allergy and bone marrow-derived mast cells were generated from naïve Balb/C mice
Project description:Immunoglobulin (Ig) E-mediated activation of mast cells and basophils underlies allergic diseases such as asthma. Histamine-releasing factor (HRF), also known as translationally controlled tumor protein (TCTP) and fortilin, is a highly conserved protein with both intracellular and extracellular functions. Secreted HRF can stimulate histamine release and IL-4 and IL-13 production from IgE-sensitized basophils and mast cells. HRF is found in nasal, skin blister and bronchoalveolar lavage (BAL) fluids during late-phase allergic reactions (LPRs), which implicates HRF in the LPR and chronic allergic inflammation. Here we identify a subset of IgE and IgG antibodies as HRF-interacting molecules. HRF can exist as a dimer and bind to immunoglobulins (Igs) via interactions of its N-terminal and internal regions with the Fab region of Igs. Therefore, HRF together with HRF-reactive IgE can activate mast cells in vitro. The Ig-interacting HRF peptides that block HRF-Ig interactions can inhibit IgE+HRF-induced mast cell activation and in vivo cutaneous anaphylaxis and airway inflammation. Intranasally administered HRF can recruit inflammatory immune cells to the lung in naïve mice in a mast cell- and Fc receptor-dependent manner. These results strongly suggest the proinflammatory role of HRF in asthma and skin immediate hypersensitivity.
Project description:Mast cells produce a large amount of several chemokines after cross-linking of FceRI and participate in the pathogenesis of allergic diseases. The objective of this study was to comprehensively investigate FceRI-mediated chemokine induction in human mast cells and the effect of a corticosteroid (dexamethasone) and a calcineurin inhibitor (FK506). Human peripheral blood-derived mast cells were stimulated with anti-IgE antibody in the presence of dexamethasone or FK506. Expression of eight chemokines was significantly induced in mast cells by anti-IgE stimulation. Induction of CCL2, CCL7, CXCL3 and CXCL8 by anti-IgE was significantly inhibited by dexamethasone. In contrast, induction of CCL1, CCL3, CCL4 and CCL18 was significantly inhibited by FK506. Combination of dexamethasone and FK506 suppressed production of all chemokines by anti-IgE stimulation. These results suggest that corticosteroids and calcineurin inhibitors inhibit expression of distinct subsets of chemokines and a combination of these drugs almost completely suppresses the induction of all chemokine genes in human mast cells in response to FceRI-dependent stimulation.