Ergosterol and its derivatives from Grifola frondosa inhibit antigen-induced degranulation of RBL-2H3 cells by suppressing the aggregation of high affinity IgE receptors.

Grifola frondosa is an edible mushroom consumed as a health food and/or traditional medicine in Asia. However, the anti-allergic effects of G. frondosa are not yet understood. In this study, we demonstrated the effects of G. frondosa extract (GFE) on IgE-mediated allergic responses, using antigen-stimulated RBL-2H3 cells. Three active compounds: ergosterol, 6ß-methoxyergosta-7,22-dien-3ß,5α-diol (MEDD), and 6-oxoergosta-7,22-dien-3ß-ol (6-OXO) were isolated from GFE and shown to inhibit the antigen-induced release of ß-hexosaminidase and histamine. Among the three active components, we focused on ergosterol because of its high content in GFE. Ergosterol inhibited the aggregation of high-affinity IgE receptor (FcεRI), which is the first step in the activation of mast cells and antigen-induced tyrosine phosphorylation. Furthermore, ergosterol suppressed antigen-increased IL-4 and TNF-α mRNA. Taken together, our findings suggest that G. frondosa, including ergosterol and its derivatives as active components, has the potential to be a novel functional food that prevents type I allergies.

Houttuynia cordata water extract suppresses anaphylactic reaction and IgE-mediated allergic response by inhibiting multiple steps of FcepsilonRI signaling in mast cells.

Houttuynia cordata has been used as a traditional medicine in Korea and is known to have antioxidant, anti-cancer and anti-allergic activities. The precise effect of H. cordata, however, remains unknown. In this study, we investigated the effects of H. cordata water extract (HCWE) on passive cutaneous anaphylaxis (PCA) in mice and on IgE-mediated allergic response in rat mast RBL-2H3 cells. Oral administration of HCWE inhibited IgE-mediated systemic PCA in mice. HCWE also reduced antigen (DNP-BSA)-induced release of beta-hexosaminidase, histamine, and reactive oxygen species in IgE-sensitized RBL-2H3 cells. In addition, HCWE inhibited antigen-induced IL-4 and TNF-alpha production and expression in IgE-sensitized RBL-2H3 cells. HCWE inhibited antigen-induced activation of NF-kappaB and degradation of IkappaB-alpha. To investigate the inhibitory mechanism of HCWE on degranulation and cytokine production, we examined the activation of intracellular FcepsilonRI signaling molecules. HCWE suppressed antigen-induced phosphorylation of Syk, Lyn, LAT, Gab2, and PLC gamma2. Further downstream, antigen-induced phosphorylation of Akt and MAP kinases (ERK1/2 and JNK1/2 but not p38 MAP kinase) were inhibited by HCWE. Taken together, the in vivo/in vitro anti-allergic effect of HCWE suggests possible therapeutic applications of this agent in inflammatory allergic diseases through inhibition of cytokines and multiple events of FcepsilonRI-dependent signaling cascades in mast cells.

Platinum group elements enhance the allergic immune response by acting on dendritic cells.

BACKGROUND: Atmospheric pollution may play a role in the immune response to allergens either directly or by entering the food chain. While particulate platinum group elements (PLGE) emitted by catalytic converters can be considered biologically inert, approximately 10% of these species accumulate in the environment as bioavailable soluble forms. METHODS: We challenged in vitro human immature and mature monocyte-derived dendritic cells with subtoxic concentrations of soluble species of PLGE. Dendritic cells were studied both at baseline and following treatment with Na(2)PtCl(6), Na(2)PdCl(6) or Na(3)RhCl(6). (NH(4))(6)Mo(7)O(24) was included as control. The following end-points were considered: expression of differentiation markers, effectiveness of allergen presentation and Th2 cytokine production by cocultured T lymphocytes, expression of IgE-type I receptor and efficiency of IgE-dependent endocytosis. RESULTS: We found that treatment with PLGE (but not with the control metal) increased costimulatory molecule expression and antigen presentation, amplified IL-5 production by cocultured T lymphocytes, upregulated IgE-type I receptor membrane expression, and augmented IgE-type I receptor-mediated endocytosis. CONCLUSIONS: We conclude that PLGE have an adjuvant-like effect on dendritic cells that can favor and amplify the immune response to allergens.

Effects of resveratrol on mast cell degranulation and tyrosine phosphorylation of the signaling components of the IgE receptor.

The molecular mechanism of how resveratrol inhibits mast cell degranulation was studied by examining its effects on the signaling components of the high affinity IgE receptor (FcepsilonRI) pathway. Resveratrol inhibited mast cell degranulation in a dose-dependent manner and reduced the FcepsilonRI-mediated tyrosine phosphorylation of ERK and PLCgamma1 but not of Syk and PLCgamma2. U-73 122 and PD98059, which are PLC and MEK inhibitors, also had inhibitory effects on mast cell degranulation. These results suggest that FcepsilonRI-mediated tyrosine phosphorylation of PLCgamma1 and ERK could be potential cellular targets of resveratrol for the inhibition of mast cell degranulation.

Effects of arachidonic acid analogs on FcepsilonRI-mediated activation of mast cells.

Polyunsaturated fatty acids (PUFAs) such as arachidonic acid (AA) have been shown to modulate a number of inflammatory disorders. Mast cells play a critical role in the initiation and maintenance of inflammatory responses. However, the effects of PUFAs on mast cell functions have not been fully addressed. We here-in examined the effects of PUFAs on the high affinity IgE receptor (FcepsilonRI)-mediated mast cell activation using RBL-2H3 cells, a rat mast cell line, that were cultured in the medium containing palmitic acid (PA), AA, or the AA analogs mead acid (MA) and eicosapentaenoic acid (EPA). In AA-supplemented cells, the FcepsilonRI-mediated beta-hexosamidase and TNF-alpha release, calcium (Ca(2+)) influx, and some protein tyrosine phosphorylations including Syk and linker for activation of T cells (LAT) were enhanced, whereas, in MA- or PA-supplemented cells, they were not changed when compared with cells cultured in control medium. In EPA-supplemented cells, the enhancements of beta-hexosamidase release and protein tyrosine phosphorylations were observed. Furthermore, in AA- or EPA-supplemented cells, FcepsilonRI-mediated intracellular production of reactive oxygen species (ROS) that is required for the tyrosine phosphorylation of LAT and Ca(2+) influx were enhanced when compared with the other cells. Thus, preincubation of AA or EPA augmented FcepsilonRI-mediated degranulation in mast cells by affecting early events of FcepsilonRI signal transduction, which might be associated with the change of fatty acid composition of the cell membrane and enhanced production of ROS. The results suggest that some PUFAs can modulate FcepsilonRI-mediated mast cell activation and might affect FcepsilonRI/mast cell-mediated inflammation, such as allergic reaction.

Taban-Arshan: immunocorrector in atopic bronchial asthma.

Taban-Arshan extract decreased expression of T-lymphocyte activation markers, normalized T-cell-mediated immunity, and suppressed increased activity of natural killer receptors during culturing with lymphocytes of patients with atopic bronchial asthma. Taban-Arshan extract normalized activation processes in the B-cell immunity and stimulated expression of receptors of activation-induced apoptosis.

Tanshinones inhibit mast cell degranulation by interfering with IgE receptor-mediated tyrosine phosphorylation of PLCgamma2 and MAPK.

Recently we have isolated four active components from Tanshen (the root of Salvia miltiorrhiza Bunge, Labiatae) responsible for the anti-allergic activities. In this study, the molecular mechanism of action of tanshinones for the inhibition of mast cell degranulation was investigated by testing their effects on the signaling components of the high affinity IgE receptor FcepsilonRI. Activation of FcepsilonRI produced immediate tyrosine phosphorylation of Syk, mitogen-activated protein kinase extracellular signal-regulated kinase, ERK1/ERK2 (p44, p42), and phospholipase Cgamma2 (PLCgamma2). 5,16-Dihydrotanshinone-I possessed the strongest inhibitory effects on mast cell degranulation and markedly reduced FcepsilonRI-mediated tyrosine phosphorylation of ERK and PLCgamma2. This suggests that tanshinones possibly exert their anti-allergic activities by affecting FcepsilonRI-mediated tyrosine phosphorylation of ERK and PLCgamma2. Abbreviations. FcepsilonRI:high affinity IgE receptor ERK:extracellular signal regulated kinase PLC: phospholipase C

Effects of dopaminergic drugs on the mast cell degranulation and nitric oxide generation in RAW 264.7 cells.

Effects of dopaminergic drugs on the degranulation of mast cells (RBL-2H3 cells) and the nitric oxide production from macrophage cells (RAW 264.7) were studied. Among the dopaminergic agonists and antagonists tested, bromocriptine, 7-OH-DPAT, haloperidol, and clozapine showed potent inhibitions of mast cell degranualtion (IC50 value, 5 microM). However, these dopaminergic agents did not affect the tyrosine phosphorylations of the signaling components of the high affinity IgE receptor (FcepsilonRI), such as Syk, PLCgamma1, and PLCgamma2.; This suggested that these signaling components were not involved in the inhibition of the mast cell degranulation by these compounds. On the other hand, dopamine, bromocriptine, 7-OH-DAPT, and haloperidol markedly inhibited the nitric oxide production from RAW 264.7 cells (IC50 values, 10-20 microM). Bromocriptine, a dopamine agonist that is routinely used for the treatment of Parkinsons disease, inhibited the expression of the inducible nitric oxide synthase at an early stage of the LPS-induced protein expression in a dose-dependent manner. The results suggested that these dopaminergic agents, when used for the treatment of dopamine receptors-related diseases, such as Schizophrenia or Parkinsons disease, might have additional beneficial effects.

Tea polyphenol epigallocatechin-3-gallate associates with plasma membrane lipid rafts: lipid rafts mediate anti-allergic action of the catechin.

High-affinity IgE receptor FcepsilonRI is key molecule in the IgE-mediated allergic reactions. Epigallocatechin-3-gallate (EGCG) has a suppressive effect of the expression of the FcepsilonRI. We show here that EGCG highly associates with plasma membrane microdomains, lipid rafts. The disruption of these lipid rafts caused a reduction of the amount of raft-associated EGCG and the FcepsilonRI -suppressive effect of EGCG. These results suggest that the interaction between EGCG and the lipid rafts is important for EGCG's ability to downregulate FcepsilonRI expression.

Stem cell factor augments Fc epsilon RI-mediated TNF-alpha production and stimulates MAP kinases via a different pathway in MC/9 mast cells.

Mast cells express the receptor tyrosine kinase kit/stem cell factor receptor (SCFR) which is encoded by the proto-oncogene c-kit. Ligation of SCFR induces its dimerization and activation of its intrinsic tyrosine kinase activity leading to activation of Raf-1, phospholipases, phosphatidylinositol 3-kinase, and extracellular signal-regulated kinases. However, little is known about the downstream signals initiated by SCFR ligation except for activation of extracellular signal-regulated kinases. The murine mast cell line, MC/9, synthesizes and secretes TNF-alpha following the aggregation of high affinity Fc receptors for IgE (Fc epsilonRI). Ligation of SCFR or Fc epsilonRI on MC/9 cells resulted in the activation of all three MAP kinase family members, extracellular signal-regulated kinases, c-Jun amino-terminal kinase (JNK), and p38. Stem cell factor (SCF)-induced activation of JNK and p38 was insensitive to wortmannin, cyclosporin A, and FK506 whereas activation of these kinases through Fc epsilonRI was sensitive to these drugs. Coligation of SCFR augmented Fc epsilonRI-mediated activation of MAP kinases, especially JNK activation, and SCF augmented Fc epsilonRI-mediated TNF-alpha production in MC/9 cells, although SCF alone did not induce TNF-alpha production. This augmentation by SCF was regulated at the level of transcription, at least in part, since the promoter activity of TNF-alpha was enhanced following addition of SCF. These results demonstrate that SCF can augment Fc epsilonRI-mediated JNK activation and cytokine gene transcription but via pathways that are regulated differently than the ones activated through Fc epsilonRI.

Association of immunological changes with clinical efficacy in atopic eczema patients treated with traditional Chinese herbal therapy (Zemaphyte).

The efficacy of the Chinese herbal therapy (Zemaphyte) has been well established as a treatment for atopic eczema (AE) in clinical trials. The purpose of this study was to probe the immunological changes that occurred when patients were treated with the herbs for a period of 8 weeks. This treatment decreased serum IgE complexes (p less than 0.05) but did not affect total serum IgE or CD23 expression on peripheral blood monocytes. Peripheral blood mononuclear cells from patients before and after treatment were cultured overnight with interleukin 4 and the ability of this cytokine to induce CD23 on monocytes from treated patients was found to be significantly diminished (p less than 0.01). Soluble interleukin 2 receptor and soluble vascular cell adhesion molecule were both raised in the serum of AE patients compared to control individuals. Both these parameters were decreased following treatment (p less than 0.05). All these changes coincided with improvement in erythema and surface damage scores. There was no alteration in soluble intracellular adhesion molecule or soluble CD23. The results of these investigations would suggest that this herbal treatment has the ability to target various immunological parameters which may be involved in the pathogenesis of AE.

Alterations in Fc epsilon RI induced by protoporphyrin plus long-wavelength ultraviolet light in mouse bone marrow-derived mast cells.

As previously reported, protoporphyrin plus long-wavelength UV light (PP/UVA) inhibits IgE-mediated degranulation of mouse bone marrow-derived mast cells, as assessed by measurement of the release of beta-hexosaminidase. This inhibitory effect was seen with cells sensitized with IgE either before or after PP/UVA treatment (57.8 and 55.3% inhibition, respectively). PP/UVA did not dissociate IgE already bound to cells as assessed either by measuring release of bound 125I-IgE or by flow cytometric analysis. Results from immunoadsorption followed by SDS-PAGE analysis suggested that PP/UVA treatment may cause stable conjugation of IgE to its receptor. In unsensitized cells, PP/UVA did not cause conjugation of the unoccupied Fc epsilon RI to other proteins in the plasma membrane. Nevertheless, Scatchard analysis revealed that PP/UVA decreased the number of Fc epsilon RI per cell by 37% (0.95 x 10(5) vs 1.51 x 10(5)/cell), whereas affinity of the receptor for IgE was comparable between PP/UVA-treated and untreated cells (3.40 nM vs 3.27 nM). Flow cytometric analysis also confirmed the decrease in Fc epsilon RI number in PP/UVA-treated unsensitized mouse bone marrow-derived mast cells. Although 84% of PP/UVA-treated and 82% of untreated cells expressed positive fluorescence when stained with FITC-conjugated IgE, fluorescence intensity was reduced by 40% after PP/UVA treatment. We conclude that PP/UVA alters the conformational structure and/or number of Fc epsilon RI expressed on the mast cell surface. This effect could potentially explain the ability of PP/UVA to inhibit mast cell secretory function and may be related to an ability of PP/UVA to alter the properties of the plasma membrane.

Effect of saiboku-to (TJ-96) on bronchial asthma. Induction of glucocorticoid receptor, beta-adrenaline receptor, IgE-Fc epsilon receptor expression and its effect on experimental immediate and late asthmatic reaction.

A remarkable "steroid sparing" effect of Saiboku-to was noted within 6 to 12 months of treatment in steroid-dependent asthmatic patients. Saiboku-to spared the downregulation of glucocorticoid receptor of human lymphocytes, plasma ACTH, and cortisol levels. It also spared downregulation of beta 2 receptor by beta 2 agonists and suppressed mACh receptor at the same time. Saiboku-to increased tyrosine aminotransferase (TAT) production, which was inhibited by actinomycin-D, thus having steroid-like activity. In mite-allergic asthma, Saiboku-to inhibited the induction of expression of IgE-Fc epsilon R/CD23 in the lymphocytes by mite allergen. It also inhibited IgE production by mite allergens. In experimental asthma in guinea pigs the use of Saiboku-to resulted in a decrease in the number of eosinophils in the bronchoalveolar lavage fluid during late asthmatic response. These findings suggest that Saiboku-to may be effective in inhibiting both the expression of IgE-Fc epsilon R2 and the induction of expression of IgE-Fc epsilon R1. Saiboku-to also has a steroid-like action and polyhedral anti-asthmatic activities.