Project description:Intestinal mucosal mast cells are critically involved in the development of food-induced allergic disorders. However, factors that induce differentiation of mucosal mast cells in the intestinal mucosa are largely unknown. To identify factors involved in mucosal mast cell differentiation, we compared the gene expression profiles between mucosal mast cells isolated from the small intestine and bone marrow-derived mast cells cultured in the presence of TGF-β or Notch ligand. Mucosal mast cells were isolated from the small intestine of naïve BALB/c mice by flow cytometry. Bone marrow-derived mast cells (BMMCs) were generated by culturing BALB/c bone marrow cells with murine interleukin-3 and stem cell factor for 3-4 weeks, and then cells were cultured for 6 days in the presence or absence of TGF-β or Delta-like 1 (Dll1), which is a Notch ligand. Total RNAs extracted from these cells were processed and hybridized to Affymetrix GeneChips.
Project description:Mast cells are known to be the key players in type I hypersensitivity reactions in humans and mice. They are critically involved in the development of allergic rhinitis, allergic asthma and systemic anaphylaxis. In this study we investigated the role of the transcriptional regulator MAZR in mast cells by comparing the expression profile of mast cells generated from wild-type (MazrF/F) and MAZR-deficient (MazrF/F x Vav-iCre) bone marrow cells. Our results from the array data demonstrate that MAZR acts preferentially as a transcriptional repressor in mast cells.
Project description:Stem cell factor (SCF) mediated KIT receptor activation plays a pivotal role in mast cell growth, maturation and survival. However, the signaling events downstream from KIT are poorly understood. Mast cells express multiple regulatory subunits of class 1A PI3Kinase (PI3K) including p85α, p85β, p50α, and p55α. While it is known that PI3K plays an essential role in mast cells; the precise mechanism by which these regulatory subunits impact specific mast cell functions including growth, survival and cycling are not known. We show that loss of p85α impairs the growth, survival and cycling of mast cell progenitors (MCp). To delineate the molecular mechanism (s) by which p85α regulates mast cell growth, survival and cycling, we performed microarray analyses to compare the gene expression profile of MCps derived from WT and p85α-deficient mice in response to SCF stimulation. We identified 151 unique genes exhibiting altered expression in p85α-deficient cells in response to SCF stimulation compared to WT cells. Functional categorization based on DAVID bioinformatics tool and Ingenuity Pathway Analysis (IPA) software relates the altered genes due to lack of p85α to transcription, cell cycle, cell survival, cell adhesion, cell differentiation, and signal transduction. Our results suggest that p85α is involved in mast cell development through regulation of expression of growth, survival and cell cycle related genes. Two-condition experiment, wildtype vs. p85α-deficient mast cell progenitors stimulated with SCF. Biological replicates: 3 wildtype replicates, 3 p85α-deficient replicates.
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:CD25 (IL-2R) can be expressed on the surface of immune cells in the absence of other chains of the interleukin-2 receptor (IL-2R), which are indispensable for IL-2 signaling. We identified two novel mast cell subsets, characterized by the differential expression of surface CD25, and by the ability to produce different cytokines and to proliferate, both in vitro and in vivo. We provide evidence that functional differences between the two mast cell populations were dependent on CD25 itself, which directly modulated mast cell proliferation and responses in vivo. These effects were completely independent from IL-2 or the expression of the other chains of the high-affinity IL-2R, indicating an autonomous and previously unappreciated role for CD25 in regulating cell functions. Similar results were also obtained in dendritic cells, which are known to express CD25 but to be unresponsive to IL-2. Our findings indicate a general role for CD25 in contexts where IL-2 signaling is not involved, and may have important implications for all mast cell-related diseases, including mastocytosis, where CD25 is aberrantly expressed on pathogenic mast cells. Total mRNA of FACS-sorted CD25pos and CD25neg populations of primary bone marrow-derived mast cells (BMMCs) was extracted and subjected to by multiparallel sequencing.
Project description:MicroRNA 155 (miR-155) has been shown to regulate the gene expression of important players of physiological and pathological processes, like hematopoietic lineage differentiation, immunity and inflammation, viral infections, cancer and cardiovascular diseases, among others. Degranulation is an event in which mast cells, upon activation of the FceRI, release their granule content rich in vasoactive amines, proteases and TNFa. Additionally activation of the receptor promotes de novo synthesis of cytokines, chemokines and growth factors. Analysis of bone marrow derived mast cells (BMMC) deficient in miR-155 showed a significant increase in FceRI mediated degranulation and in the release of cytokines like TNFa, IL-6 and IL-13. In addition miR 155-/- mice presented higher anaphylaxis reactions compared to WT mice. Gene expression analysis of BMMC was performed in order to identify intermediaries of FceRI mediated degranulation under the control of miR-155. The results indicate that miR-155 regulates negatively the expression of the regulatory subunits of the kinase PI3Kgamma, Pik3r5 (p101) and Pik3r6 (p84, p87PIKAP), involved in Ca+ influx and degranulation. Total RNA from 3 independent cultures of WT and miR-155-/- BMMC treated with anti-DNP IgE and 20 ng/ml DNP-HSA for 1hr were used to performed gene expression analysis using the Affymetrix GenechipM-BM-. Mouse Gene 1.0 ST
Project description:The aim of this study was to investigate microRNA expression pattern and its functional relevance on the commitment toward mucosal differentiation and on IgE-mediated activation of mast cells. To identify microRNA genes the expression of which change during the differentiation and activation of murine primary mast cells in vitro, the putative committed progenitors (c-kit+ cells isolated on day 6 from differentiating cultures), immature mast cells (BMMC), mucosal-type mast cells (MMC), and IgE-activated mast cells were compared by Agilent microRNA array. RNA was isolated by miRNeasy (Qiagen) from: 1) c-kit+ cells, isolated from differentiating cultures (in the presence of IL3 and SCF) derived from the bone marrow using MACS column purification, 2) immature BMMCs obtained by cultivation of bone marrow cells in the presence of IL3 and SCF for 4 weeks, 3) mucosal-type mast cells by additional differentiation of immature BMMCs for 5 days by supplementation of IL9 and TGFbeta, and 4) activated mast cells by presensitization with anti-DNP IgE followed by IgE-crosslinking by DNP-antigen challenge for 2 hours. Agilent microRNA microarray was run on these experimental groups. Four biological replicates were included in every experimental group.
Project description:We used tyrosine phosphorylation profiling by anti-pTyr-antibody mediated enrichment and subsequent analysis by mass spectrometry in order to determine the changes in early signalling after mast cell activation. Mast cells were stimulated with varying concentrations of antigen for one minute and the differences between optimal (20 ng/ml) and supra-optimal (2000 ng/ml) antigen mast cell activation were analysed by nanoLC-MS/MS.
Project description:Interleukin-33 (IL-33) is elevated in afflicted tissues of patients with mast cell-dependent chronic allergic diseases. Based on its acute effects on mouse mast cells (MCs), IL-33 is thought to play a role in the pathogenesis of allergic disease through MC activation. However, the manifestations of chronic IL-33 exposure on human MC function, which best reflect the conditions associated with chronic allergic disease, are unknown. We now find that long-term exposure of human and mouse MCs to IL-33 results in a substantial reduction of MC activation in response to antigen. This reduction required >72 h exposure to IL-33 for onset and 1-2 wk for reversion following IL-33 removal. This hypo-responsive phenotype was determined to be a consequence of MyD88-dependent attenuation of signaling processes necessary for MC activation including antigen-mediated calcium mobilization and cytoskeletal reorganization; potentially as a consequence of down-regulation of the expression of PLCg1 and Hck. These findings suggest that IL-33 may play a protective, rather than a causative role in MC activation under chronic conditions and, furthermore, reveal regulated plasticity in the MC activation phenotype. The ability to down-regulate MC activation in this manner may provide alternative approaches for treatment of MC-driven disease. Mouse bone marrow-derived mast cells treated with IL3 or IL3+IL33. 6 replicates each.
Project description:Mast cells are hematopoietic cells that reside preferentially in tissues exposed to internal and external environments. Mast cells sense immunological, inflammatory and environmental stimuli, and can be activated to release granules and generate inflammatory mediators. Mast cell-derived products confer protection against snake venoms and some parasite infections. Aberrant activation of mast cells is a major contributor to human pathology, including allergy, asthma and adverse drug reactions. Their strict tissue location has largely impeded the isolation of large numbers of primary mast cell for further analysis. To better understand the biology of mast cells, we analyzed the proteome of primary human and mouse mast cells by quantitative mass spectrometry. We identified a mast cell-specific protein signature that was conserved from mouse to man. Compared to a comprehensive set of other immune cell lineages, proteome analysis identified a unique and distant mast cell cluster. The mast cell signature included proteins governing granule biosynthesis and secretion, as well as proteoglycan- and neurotransmitter metabolism. Proteome conservation across species suggests evolutionary maintenance of mast cell functions.