Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In patients with allergic asthma, T-cell cytokines are implicated in the regulation of the local inflammation in the airways. The ability of sensitized mast cells to release mediators and cytokines early upon allergen stimulation makes them important candidates for local immunoregulation. We have studied the effects of human mast cells on T cells with the use of the human mast cell line HMC-1. We showed that activated human mast cells or their soluble products induced and enhanced the interferon-gamma (IFN-gamma) production by T cells up to about 60-fold. The production of interleukin (IL)-4 was hardly affected and that of IL-5 was slightly enhanced. The enhancement of IFN-gamma production was induced both in polyclonal CD4+ and CD8+ T cells and in CD4+ and CD8+ T-cell clones. Further characterization of the factors involved demonstrated a molecular mass above 30 000. Our results implicate that by this mechanism mast cells may account for a negative feedback system locally down-regulating allergen-induced T helper 2 responses via IFN-gamma production by the T cells.
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PMID:Products from human mast cell line cells enhance the production of interferon-gamma by CD8+ and CD4+ T cells. 1197 27

Schistosome granulomas produce IL-4, important for Th2 granuloma expression. We defined the origins of IL-4 within these granulomas and the role of IL-4-producing CD4(+) T cells in Th2 granuloma development. Dispersed granuloma cells spontaneously produced IL-4 independently of T cells, whereas IL-5 production was T cell dependent. Granuloma IL-4 mRNA localized to the non-T cells and IL-5 to T cells. Granuloma CD4(+) T and NK cells, but not B cells produced IL-4 and IL-5 in vitro. B cell-/- mice generated Th2 granulomas that produced IL-4 and IL-5 normally. Granuloma eosinophils expressed no IL-4 or IL-5 mRNA. Granulomas in WWv mast cell-deficient mice lacked mast cells. The dispersed granuloma cells from WWv mice released IL-4 only after T cell stimulation, suggesting that mast cells influenced the constitutive component of IL-4 production. Rag-1 animals (T/B/NK T cell deficient) given schistosomiasis after reconstitution with splenocytes from naive mice produced Th2 granulomas. Mice reconstituted to create selective CD4(+) T cell IL-4 knockout animals developed eosinophilic granulomas that made IL-4. Thus, granulomas contain several cell types that produce IL-4. Mast cells are not needed to form Th2 granulomas, but influence IL-4 release. Th2 granuloma development in schistosomiasis is only partly dependent on IL-4-producing CD4(+) T cells.
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PMID:Th2-type granuloma development in acute murine schistosomiasis is only partly dependent on CD4+ T cells as the source of IL-4. 1198 11

Toll-like receptor 2 (TLR2) and TLR4 play important roles in the early innate immune response to microbial challenge. To clarify the functional roles of TLRs 2 and 4 in mast cells, we examined bone marrow-derived mast cells (BMMCs) from TLR2 or TLR4 gene-targeted mice. Peptidoglycan (PGN) from Staphylococcus aureus stimulated mast cells in a TLR2-dependent manner to produce TNF-alpha, IL-4, IL-5, IL-6, and IL-13, but not IL-1beta. In contrast, LPS from Escherichia coli stimulated mast cells in a TLR4-dependent manner to produce TNF-alpha, IL-1beta, IL-6, and IL-13, but not IL-4 nor IL-5. Furthermore, TLR2- but not TLR4-dependent mast cell stimulation resulted in mast cell degranulation and Ca2+ mobilization. In a mast cell-dependent model of acute sepsis, TLR4 deficiency of BMMCs in mice resulted in significantly higher mortality because of defective neutrophil recruitment and production of proinflammatory cytokines in the peritoneal cavity. Intradermal injection of PGN led to increased vasodilatation and inflammation through TLR2-dependent activation of mast cells in the skin. Taken together, these results suggest that direct activation of mast cells via TLR2 or TLR4 by respective microligands contributes to innate and allergic immune responses.
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PMID:Differential responses of mast cell Toll-like receptors 2 and 4 in allergy and innate immunity. 1202 Dec 51

Human mast cells are multifunctional tissue-dwelling cells that play a crucial role in eosinophil-dependent disorders, such as asthma and parasitic diseases, by the secretion of eosinophil-active mediators. Mast cell-derived cytokines, generated in response to cross-linking of the high-affinity IgE receptor, can regulate eosinophil activation, survival, and chemotaxis. In this study, mast cells generated from human cord blood progenitors (stem cells) were studied for eosinophil-active inflammatory cytokine expression. Cord blood-derived mast cells (CBDMC) expressed typical intracellular scroll granules and microvilli-like structures on their cell surfaces, demonstrated the presence of tryptase, and elaborated prostaglandin D2 (PGD2) after cross-linkage of the high-affinity receptor for IgE (FcepsilonRI). CBDMC expressed tumor necrosis factor-alpha (TNF-alpha) and the eosinophil-active growth factors, interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF) after activation. (IL-1beta greatly enhanced IgE-dependent production of these cytokines in response to FcepsilonRI cross-linkage, suggesting a role for bystander/phagocytic cells in modulating mast cell function. In contrast, interferon-alpha (IFN-alpha) inhibited IL-5 and GM-CSF generation, and the glucocorticoid, dexamethasone (Dex), inhibited production of IL-5 and GM-CSF from CBDMC. A macrophage-mast cell-eosinophil axis may exist in vivo that may be susceptible to pharmacologic manipulation.
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PMID:Regulation of eosinophil-active cytokine production from human cord blood-derived mast cells. 1203 46

We have studied murine models of asthma using FcepsilonRIalpha-chain-deficient (FcepsilonRIalpha(-/-)) mice to investigate the role of IgE-dependent mast cell activation in these models. When mice were either 1) immunized once with OVA in alum i.p. and then challenged with OVA intranasally, or 2) repeatedly immunized with OVA in the absence of adjuvant and subsequently challenged with nebulized OVA, FcepsilonRalpha(-/-) mice had significantly fewer eosinophils and lower IL-4 levels in their bronchoalveolar lavage fluid compared with wild-type mice. When mice were given anti-IL-5 antibody before OVA challenge in protocol 1, eosinophilic infiltration into the airways was significantly suppressed in both genotypes, but only FcepsilonRIalpha(-/-) mice showed significantly reduced airway hyperresponsiveness (AHR). In addition, when mice immunized and challenged with OVA also received a late OVA provocation at a higher concentration and were then exposed to methacholine, only wild-type mice developed a substantial increase in AHR. Since FcepsilonRI is expressed mainly on mast cells in mouse airways, we conclude that IgE-dependent activation of this cell type plays an important role in the development of allergic airway inflammation and AHR in mice. The models used may be of value for testing inhibitors of IgE or mast cells for development of therapeutic agents for human asthma.
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PMID:IgE-dependent mast cell activation potentiates airway responses in murine asthma models. 1216 33

Eosinophilic esophagitis (EE) is an important esophageal disorder with distinct clinicopathologic features, and the condition is associated with a high prevalence of food allergies and atopy. In the past decade, we have improved our ability to recognize the phenotype of EE, but our ability to treat EE effectively remains limited despite several reports of successful treatment using elemental or elimination diets, and systemic and topical corticosteroids. The limitations for developing effective treatment regimens are due to some still unresolved and ambiguous aspects of the pathogenesis of EE. Neither the predisposing factors for developing EE in a subset of patients with atopy, nor the variable responsiveness to control measures for allergens are fully understood. There also remain questions about the precise role of gastroesophageal reflux, and the natural history of the disorder, contingent on which is the optimal treatment of EE. In devising treatment for a patient with EE, all attempts should be made to identify and control food and other allergies. In patients who have no diagnosed allergies or who are unresponsive to allergy treatment, topical steroids are a safe and effective treatment option. Systemic steroids should be reserved for those patients who are refractory to topical steroids. Beyond the initial phase of induction treatment, it is crucial to develop effective and safe maintenance treatment regimens based on ongoing allergen control and mast cell inhibitors. There are limited but encouraging data to support further exploration of the role of leukotriene and interleukin-5 inhibitors as safe, effective, and steroid-sparing treatment options.
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PMID:Treatment of Eosinophilic Esophagitis in Children. 1220 60

What do we know? CD4+ T cells are strongly implicated in asthma pathogenesis. The "T(H)2 hypothesis" postulates two patterns of cytokine secretion by stimulated CD4+ T cells: a "T(H)1" response and a "T(H)2" response. T(H)2-type cytokines (interleukins IL-4, IL-5, IL-9, IL-13) regulate eosinophilia, mast cell growth, IgE and mucus production and have been proposed as key regulatory factors in asthma. T(H)1-type cytokines include interferon-gamma, IL-2, IL-12, IL-18, and tumour necrosis factor beta.T(H)2 responses are reciprocally inhibited by T(H)1 responses in animal models, but this may not be so in asthma in humans. In humans, T(H)1- and T(H)2-type cytokines are often coexpressed in early asthma. What do we need to know? Is cross-regulation between T(H)1 and T(H)2 immune biases truly lost in in early asthma? Can induction of T(H)1-type responses actually protect against asthma, as predicted by the "hygiene hypothesis"? If so, how might this induction be achieved safely in infants? Can the in-utero environment be subtly manipulated to minimise asthma risk? Does early childhood treatment with current anti-asthma drugs lead to long-term immune changes?
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PMID:The immunobiology of early asthma. 1222 57

Gastrointestinal nematode infections generally invoke a type 2 cytokine response, characterized by the production of IL-4, IL-5, IL-9, and IL-13. Among these cytokines, IL-4 and IL-13 exhibit a functional overlap that can be explained by the sharing of a common receptor or receptor component (IL-4Ralpha). Binding of IL-4 by either the type 1 or 2 IL-4R, or of IL-13 by the type 2 IL-4R, initiates Jak-dependent tyrosine phosphorylation of the IL-4Ralpha-chain and the transcription factor, STAT6. In the present study, we investigated: 1) whether IL-13 has effects on intestinal epithelial cells similar to those observed with IL-4, and 2) whether the effects of IL-4 and IL-13 depend on STAT6 signaling and/or mast cells. BALB/c, STAT6(-/-), and mast cell-deficient W/W(v) mice or their +/+ littermates were treated with a long-lasting formulation of recombinant mouse IL-4 (IL-4C) or with IL-13 for seven days. Segments of jejunum were mounted in Ussing chambers to measure mucosal permeability; chloride secretion in response to PGE(2), histamine, 5-hydroxytryptamine, or acetylcholine; and Na(+)-linked glucose absorption. IL-4C and IL-13 increased mucosal permeability, decreased glucose absorption, and decreased chloride secretion in response to 5-hydroxytryptamine. These effects were dependent on STAT6 signaling. Responses to PGE(2) and histamine, which were dependent on mast cells and STAT6, were enhanced by IL-4C, but not by IL-13. The effects of IL-4 and IL-13 on intestinal epithelial cell function may play a critical role in host protection against gastrointestinal nematodes.
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PMID:Role of STAT6 and mast cells in IL-4- and IL-13-induced alterations in murine intestinal epithelial cell function. 1237 Mar 75

To investigate the role of mast cells in treatment-associated adverse reactions in patients with onchocerciasis, changes in plasma tryptase levels and skin mast cell counts were examined in 2 groups of Onchocerca volvulus-infected subjects after ivermectin treatment. After treatment, an increase in tryptase levels was observed concurrent with the onset of blood eosinopenia and preceding the appearance of plasma eosinophil-derived neurotoxin (EDN) and interleukin-5. Tryptase levels were correlated with development of peripheral eosinopenia and markers of eosinophil activation and degranulation. Dermal mast cell numbers increased transiently at 24 h after treatment, preceding the onset of dermal eosinophil infiltration and the development of clinically apparent inflammation. Local reactions were strongly correlated with levels of plasma tryptase and EDN, and the severity of systemic reactions was correlated with levels of tryptase, EDN, and interleukin-5. The data indicate that mast cells play a role in initiation of tissue inflammatory reactions after ivermectin treatment of onchocerciasis.
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PMID:Association of transient dermal mastocytosis and elevated plasma tryptase levels with development of adverse reactions after treatment of onchocerciasis with ivermectin. 1240

Mast cells, historically known for their involvement in type I hypersensitivity, also serve critical protective and homeostatic functions. They directly recognize the products of bacterial infection through several surface receptor proteins, releasing proteases, cytokines, and eicosanoid mediators that recruit neutrophils, limit the spread of bacterial infection, and facilitate subsequent tissue repair. In vitro studies suggest that the spectrum of microbes capable of initiating mast cell activation is broad and extends to common respiratory viruses, mycoplasma, and even products of tissue injury, such as nucleotides. TH2-polarized inflammation elicits a reactive hyperplasia of mast cells at the involved mucosal surfaces in both mice and human subject. Several recombinant TH2 cytokines (IL-3, IL-4, IL-5, and IL-9) act synergistically with stem cell factor to facilitate proliferation of nontransformed human mast cells in vitro. IL-4 induces the expression of critical inflammation-associated genes by human mast cells, such as those encoding leukotriene C4 synthase, Fc(epsilon)RI, and several cytokines. Consequently, priming with IL-4 not only amplifies classical Fc(epsilon)RI-dependent mast cell activation but also dramatically alters the product profile of mast cells activated by innate signals and by chemical mediators of inflammation. Strikingly, IL-4 induces an activation response by mast cells to cysteinyl leukotrienes, which act through a receptor shared with uridine diphosphate to induce cytokine generation without exocytosis. It Is possible that alterations in mast cell phenotype by the TH2 milieu of allergy permits otherwise trivial infections or homeostatic chemical signals to initiate harmful inflammatory cascades and sustain tissue pathology. Drug development must take these nonclassical mast cell activation pathways into account without compromising the beneficial and protective functions of mast cells.
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PMID:Mast cells: beyond IgE. 1253 90


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