Curcumin, a constituent of curry, suppresses IgE-mediated allergic response and mast cell activation at the level of Syk.
ABSTRACT Activation of mast cells through the high-affinity receptor for IgE (FcepsilonRI) underlies atopic allergic reactions. Curcumin can block this activation, but the mechanism and the effects of curcumin on IgE-mediated allergic reactions are unknown.
We sought to determine the antiallergic activity of curcumin in vivo and its mechanism of action in mast cells.
The antiallergic activity of curcumin was evaluated in mast cell cultures and the passive cutaneous anaphylaxis model. The effects of curcumin on mast cell signaling events were examined by using immunoblotting, immunoprecipitation, RT-PCR, and other molecular biologic approaches.
Curcumin inhibited antigen-mediated activation of mast cells and passive cutaneous anaphylaxis in mice. Suppression of degranulation and secretion of TNF-alpha and IL-4 was apparent at concentrations as low as 3 micromol/L curcumin in activated mast cells. Similar concentrations of curcumin suppressed Syk-dependent phosphorylations of the adaptor proteins linker of activated T cells and Grb2-associated binder 2, which are critical for mast cell activation. Although curcumin did not inhibit the phosphorylation of Syk itself, it directly inhibited Syk kinase activity in vitro. Further downstream, activating phosphorylations of Akt and the mitogen-activated protein kinases p38, p44/42 (extracellular signal-regulated kinase 1/2), and c-Jun N-terminal kinase, which are critical for the production of inflammatory cytokines, were also inhibited.
Curcumin inhibits Syk kinase-dependent signaling events in mast cells and might thus contribute to its antiallergic activity. Therefore curcumin might be useful for the treatment of mast cell-related immediate and delayed allergic diseases.
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ABSTRACT: Dexamethasone and other glucocorticoids suppress FcepsilonRI-mediated release of inflammatory mediators from mast cells. Suppression of cytokine production is attributed to repression of cytokine gene transcription but no mechanism has been described for the suppression of degranulation. We show that therapeutic concentrations of dexamethasone inhibit intermediate signaling events, in particular the activation of phosphatidylinositol (PI)3-kinase and downstream signaling events that lead to degranulation in rat basophilic leukemia 2H3 cells. This inhibitory action is mediated via the glucocorticoid receptor and is not apparent when cells are stimulated via Kit in a mouse bone marrow-derived mast cell line. The primary perturbation appears to be the failure of the regulatory p85 subunit of PI3-kinase to engage with the adaptor protein Grb2-associated binder 2 leading to suppression of phosphorylation of phospholipase Cgamma2, the calcium signal, and degranulation. Suppression of PI3-kinase activation by dexamethasone may also contribute to reduced cytokine production because the PI3-kinase inhibitor LY294002, like dexamethasone, inhibits Ag-induced transcription of cytokine genes as well as degranulation.The Journal of Immunology 07/2004; 172(12):7254-62. · 5.52 Impact Factor
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ABSTRACT: R112 inhibits Syk kinase, a transducer of signaling through the Fcepsilon receptor of mast cells, blocking mast cell responses to allergic stimuli. Examine the efficacy and safety of intranasal R112 in volunteers with symptomatic seasonal allergic rhinitis compared with a placebo in a park setting. In this double-blind, placebo-controlled study of 319 volunteers with seasonal allergic rhinitis, 160 were randomized to intranasal R112 and 159 to a vehicle control during 2 days at 2 separate locations in spring 2004. Subjects were evaluated for symptoms of allergic rhinitis (i.e., sneezes, runny nose/sniffles, itchy nose, stuffy nose) on the basis of a possible maximum score of 32 for the Global Symptom Complex (GSC) scale. The primary outcome evaluated was the difference in the reduction in GSC (area under the curve over a period of 8 hours) from baseline between R112 and vehicle placebo. At baseline, the combined GSC was approximately 18/32 and equal between treatment groups. After 8 hours (dosing 3 mg/nostril every 4 hours x 2), R112 significantly reduced the GSC compared with placebo (7 vs 5.4 units, respectively; P = .0005). Each individual symptom combined to form the GSC was also significantly improved in the R112 group compared with control ( P < .05). As early as 45 minutes after dosing, R112 showed a significant improvement in symptoms over placebo, and the duration of action exceeded 4 hours. Adverse effects were indistinguishable between the groups and clinically insignificant. Intranasal R112 was effective in this park study and is a promising new treatment for seasonal allergic rhinitis.Journal of Allergy and Clinical Immunology 04/2005; 115(4):791-6. · 12.05 Impact Factor
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ABSTRACT: There has been a worldwide increase in allergy and asthma over the last few decades, particularly in industrially developed nations. This resulted in a renewed interest to understand the pathogenesis of allergy in recent years. The progress made in the pathogenesis of allergic disease has led to the exploration of novel alternative therapies, which include herbal medicines as well. Curcumin, present in turmeric, a frequently used spice in Asia has been shown to have anti-allergic and inflammatory potential. We used a murine model of latex allergy to investigate the role of curcumin as an immunomodulator. BALB/c mice were exposed to latex allergens and developed latex allergy with a Th2 type of immune response. These animals were treated with curcumin and the immunological and inflammatory responses were evaluated. Animals exposed to latex showed enhanced serum IgE, latex specific IgG1, IL-4, IL-5, IL-13, eosinophils and inflammation in the lungs. Intragastric treatment of latex-sensitized mice with curcumin demonstrated a diminished Th2 response with a concurrent reduction in lung inflammation. Eosinophilia in curcumin-treated mice was markedly reduced, co-stimulatory molecule expression (CD80, CD86, and OX40L) on antigen-presenting cells was decreased, and expression of MMP-9, OAT, and TSLP genes was also attenuated. These results suggest that curcumin has potential therapeutic value for controlling allergic responses resulting from exposure to allergens.Clinical and Molecular Allergy 02/2007; 5:1. · 1.39 Impact Factor