Kv1.3 blockers ameliorate allergic contact dermatitis by preferentially suppressing effector memory T cells in a rat model.

BACKGROUND: The Kv1.3 voltage-gated potassium channel is selectively upregulated upon activation in effector memory T (TEM ) cells in inflamed tissue, and plays an important role in maintenance of T-cell activation. Although Kv1.3 blockers have been shown to ameliorate allergic contact dermatitis (ACD) in a rat model, it remains unknown whether the effect of Kv1.3 blockers on ACD is mediated by suppressing TEM cell function and/or whether naive T-cells or central memory T (TCM ) cells are influenced. AIM: To analyse the detailed mechanism of Kv1.3 blockers in a rat model of ACD. METHODS: We examined the effects of a Kv1.3 blocker on inflammation and production of the effector cytokine interferon (IFN)-γ in inflamed tissue in rat ACD. Single-cell suspensions were isolated from inflamed rat ears (TEM cells), and regional lymph nodes (naive T/TCM cells), and the effect of Kv1.3 blockers on anti-CD3-stimulated IFN-γ production in vitro was measured. RESULTS: The Kv1.3 blocker significantly suppressed ear inflammation and IFN-γ production at the protein level in vivo. It also suppressed in vitro IFN-γ production from TEM cells from inflamed tissues, but did not suppress the function of naive T/TCM cells from lymph nodes. CONCLUSIONS: We found that the Kv1.3 blocker ameliorated ACD by inhibiting TEM cell functions only, thus Kv1.3 blockers could be a potentially selective therapeutic agent for TEM cell-mediated inflammatory skin diseases without producing harmful side-effects.

A prostaglandin D2 receptor antagonist modifies experimental asthma in sheep.

BACKGROUND: Prostaglandin (PG) D(2) is the major cylooxygenase metabolite released by mast cells upon allergen stimulation, and elicits responses through either the prostanoid DP1 receptor and/or the chemoattractant receptor homologous molecule expressed on T-helper type 2 (Th2) cells (CRTH2/DP2). Experimental evidence suggests that stimulation of one or both these receptors contributes to asthma pathophysiology. OBJECTIVE: The aim of this study was to test the hypothesis that the prostanoid DP1 receptor contributes to asthma pathophysiology by determining the efficacy of an orally active antagonist for this receptor, S-5751, on allergen-induced bronchoconstriction, airway hyperresponsiveness (AHR) and cellular inflammation in the sheep model of asthma. METHODS: PGD(2)-induced cyclic adenosine monophosphate (cAMP) production in platelet-rich plasma was used to establish the in vitro efficacy of S-5751. In vivo, sheep naturally allergic to Ascaris suum were challenged with an aerosolized antigen with and without S-5751 treatment (given 4 days before and for 6 days after the challenge). RESULTS: S-5751 inhibited PGD(2)-induced cAMP production in platelet-rich plasma with an IC(50) value of 0.12 microm. S-5751 at 30 mg/kg, but not at 3 mg/kg, reduced the early bronchoconstriction and inhibited the late bronchoconstriction. AHR and inflammatory cell infiltration in bronchoalveolar lavage fluid at days 1 and 7 were also inhibited with the 30 mg/kg dose. The responses observed with S-5751 at 30 mg/kg were comparable with those with montelukast treatment (0.15 mg/kg, twice a day, intravenous); however, S-5751 did not block inhaled leukotrieneD(4)-induced broncoconstriction. CONCLUSION: Prostanoid DP1 receptor inhibition may represent an alternative target for asthma therapy.

Cockroach allergen extract stimulates protease-activated receptor-2 (PAR-2) expressed in mouse lung fibroblast.

OBJECTIVE: To investigate whether cockroach allergen extract can stimulate Protease-activated receptor 2 (PAR-2) expressed in mouse lung fibroblast. MATERIALS: We established an immortalized lung fibroblast cell line, DM5, from PAR-2 deficient mice. By stable transfection with either an empty vector (DM5/EV) or an expression vector encoding mouse PAR-2 cDNA (DM5/Par2), a pair of lung fibroblast cell lines with or without functional PAR-2 expression were prepared. TREATMENT: The cells were exposed to cockroach allergen extract [up to 800 protein nitrogen unit (PNU)/ml], trypsin (up to 100 nM), SLIGRL agonist peptide (up to 500 microM), and trans-cinnamoyl-LIGRO agonist peptide (up to 400 microM). METHODS: The cells were loaded with Fluo-3 calcium indicator and mobilization of intracellular calcium with the stimuli was monitored by a fluorometric plate reader. Extracellular signal-regulated kinase (ERK) phosphorylation was examined by Western blot analysis using an anti-phospho ERK antibody. RESULTS: The cockroach extract induced intracellular calcium transients in a concentration dependent manner in DM5/Par2 but not in DM5/EV. The activity was abolished when the cockroach extract was heat denatured or pre-incubated with PMSF (phenylmethanesulfonyl fluoride) prior to the assay. Concomitantly, ERK phosphorylation was seen in DM5/Par2 with the cockroach extract but not with a heat-denatured extract. The responses were sensitive to an inositol-1,4,5 triphosphate antagonist (2-APB) indicating that calcium was mobilized from intracellular store. CONCLUSIONS: Cockroach allergen extract can activate PAR-2 and thereby stimulate mouse lung fibroblasts likely through protease(s). The present study proposes a potential mechanism for cockroach antigens, similar to house dust mite antigens, in the etiology of respiratory diseases.

Differential modulation of human basophil functions through prostaglandin D2 receptors DP and chemoattractant receptor-homologous molecule expressed on Th2 cells/DP2.

BACKGROUND: Both prostaglandin (PG) D receptor (DP) and CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells)/DP2 are high-affinity receptors for PGD2. Previous studies have demonstrated that PGD2 enhances releasability and induces CRTH2/DP2-mediated migration in human basophils, but the precise effects of PGD2 on basophils as well as receptor usage have not been fully clarified. OBJECTIVE: We comprehensively explored the roles of DP and CRTH2/DP2 in basophil functions by using selective agonists and antagonists for each receptor. METHODS: DP and CRTH2/DP2 transcripts were quantified by real-time PCR. We studied the effects of selective agonists (DP: BW245C; CRTH2/DP2: 13,14-dihydro-15-keto (DK)-PGD2) and/or antagonists (DP: BWA868C; CRTH2/DP2: ramatroban) on Ca2+ mobilization, migration, degranulation, CD11b expression and survival of human basophils. RESULTS: Basophils expressed transcripts of both DP and CRTH2/DP2, but the levels of CRTH2/DP2 transcripts were ca. 100-fold higher compared with DP transcripts. Ca2+ influx was induced in basophils by either PGD2 or DK-PGD2/CRTH2 agonist but not by BW245C/DP agonist. Basophils treated with PGD2 were completely desensitized to subsequent stimulation with DK-PGD2, but not vice versa. DK-PGD2 as well as PGD2 up-regulated CD11b expression, induced migration and enhanced degranulation, and those effects were completely antagonized by ramatroban/CRTH2 antagonist. In contrast, BW245C/DP agonist exhibited an inhibitory effect on basophil migration and IgE-mediated degranulation, and the migration inhibitory effect was effectively antagonized by BWA868C/DP antagonist. On the other hand, while PGD2 significantly shortened the basophil life-span, neither DK-PGD2/CRTH2 agonist nor BW245C/DP agonist did. CONCLUSION: CRTH2/DP2 is primarily responsible for the pro-inflammatory effects of PGD2 on human basophils, while DP introduces negative signals capable of antagonizing the effects of CRTH2/DP2 in these cells. The effects of PGD2 on longevity imply a mechanism(s) other than via DP or CRTH2/DP2. CRTH2/DP2 on basophils may afford opportunities for therapeutic targeting in allergic inflammation.

Effects of luteolin, quercetin and baicalein on immunoglobulin E-mediated mediator release from human cultured mast cells.

BACKGROUND: Flavonoids have a variety of activities including anti-allergic activities, and are known to inhibit histamine release from human basophils and murine mast cells. OBJECTIVE: The effects of luteolin, a flavone, on the immunoglobulin (Ig) E-mediated allergic mediator release from human cultured mast cells (HCMCs) were investigated and compared with those of baicalein and quercetin. METHODS: HCMCs were sensitized with IgE, and then treated with flavonoids before challenge with antihuman IgE. The amount of released mediators was determined as was mobilization of intracellular Ca2+ concentration, protein kinase C (PKC) translocation and phosphorylation of intracellular proteins were detected after anti-IgE stimulation. RESULTS: Luteolin, baicalein and quercetin inhibited the release of histamine, leukotrienes (LTs), prostaglandin D2 (PGD2), and granulocyte macrophage-colony stimulating factor (GM-CSF) from HCMC in a concentration-dependent manner. Additionally, the three flavonoids inhibited A23187-induced histamine release. As concerns Ca2+ signalling, luteolin and quercetin inhibited Ca2+ influx strongly, although baicalein did slightly. With regard to PKC signalling, luteolin and quercetin inhibited PKC translocation and PKC activity strongly, although baicalein did slightly. The suppression of Ca2+ and PKC signallings might contribute to the inhibition of mediator release. The activation of extracellular signal-regulated kinases (ERKs) and c-Jun NH2-terminal kinase (JNK), that were activated just before the release of LTs and PGD2 and GM-CSF mRNA expression in IgE-mediated signal transduction events, were clearly suppressed by luteolin and quercetin. In contrast, the flavonoids did not affect the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathway. CONCLUSION: These results indicate that luteolin is a potent inhibitor of human mast cell activation through the inhibition of Ca2+ influx and PKC activation.

IPD-1151T (suplatast tosilate) inhibits interleukin (IL)-13 release but not IL-4 release from basophils.

The effect of suplatast tosilate (IPD-1151T), which is known to suppress interleukin (IL)-4 release from T cells, on the release of IL-4 and IL-13 from human peripheral basophils was investigated. Basophils were obtained from 16 mite-sensitive atopic asthmatic patients. IPD-1151T clearly inhibited the antigen-induced release of IL-13 but not IL-4. These results suggest that IPD-1151T possesses different activity for the regulation of cytokine release in basophils and T cells.

Role of cyclic 3',5'-adenosine monophosphate in the regulation of chemical mediator release and cytokine production from cultured human mast cells.

BACKGROUND: Cultured human mast cells are known to resemble human lung mast cells in terms of the profiles of intracellular protease, the characteristics of histamine release, and the pharmacologic properties. OBJECTIVE: The role of cyclic 3',5'-adenosine monophosphate (cAMP) in chemical mediator release and cytokine production by human mast cells was determined. METHODS: We investigated the effects of cAMP-elevating agents on IgE-mediated chemical mediator release and cytokine production by cultured human mast cells. We also examined the relationship between intracellular cAMP levels and the inhibition of chemical mediator release or cytokine production by various drugs. RESULTS: beta-agonists significantly suppressed IgE-mediated release of histamine, leukotrienes, and PGD2 (chemical mediators) and the production of GM-CSF, IL-5 and macrophage inflammatory protein-1alpha (cytokines). Phosphodiesterase inhibitors (theophylline, rolipram, and cilostazol) had no effect on chemical mediators but suppressed cytokine production. Dibutyryl cAMP significantly suppressed both chemical mediator release and cytokine production, suggesting that their induction was regulated by intracellular cAMP. Elevation of cAMP by beta-agonists at 10 minutes after treatment correlated well with the inhibition of histamine release. There was a significant relationship between cAMP elevation at 180 minutes and the inhibition of GM-CSF production at 360 minutes by beta-agonists, rolipram, or cilostazol. Although 100 micromol/L theophylline significantly inhibited GM-CSF production, it had no effect on cAMP. CONCLUSION: Elevation of cAMP may be responsible for the inhibitory effect of beta-agonists, rolipram, and cilostazol on chemical mediator release and cytokine production by cultured human mast cells. In contrast, theophylline may inhibit GM-CSF production independently of cAMP.

Ca2+ and protein kinase C signaling for histamine and sulfidoleukotrienes released from human cultured mast cells.

Human cultured mast cells (HCMC) release histamine and sulfidoleukotrienes (LTs) upon IgE-FcepsilonRI-mediated mast cell activation. We analyzed the Ca2+ and PKC signaling in HCMC and compared it to that in rodent mast cells. In HCMC, after IgE-mediated stimulation, an elevation of [Ca2+]i and PKC translocation to the membrane fraction was observed. As concerns Ca2+ signaling, 1) IgE-mediated histamine and LTs release was abolished after Ca2+ depletion, and the reconstitution of Ca2+ recovered the release of histamine and LTs. As regards PKC signaling, 1) staurosporine inhibited IgE-mediated mediator release. 2) PKC-downregulated mast cells did not release histamine and LTs. A23187 and PMA synergistically potentiated the activation of extracellular-regulated kinase and synergistically induced histamine and LTs release. These results demonstrated that HCMC might be useful for analysis of the signal transduction pathway for mediator release, such as histamine and LTs.

The effects of anti-asthma drugs on mediator release from cultured human mast cells.

BACKGROUND: A method for generating human mast cells in vitro was recently established. Little is known about the pharmacological profiles of allergic mediator release from cultured mast cells. OBJECTIVE: The main objective was to investigate the nature of cultured mast cells from a pharmacological point of view. We examined the effect of anti-asthma drugs on the release of histamine, sulfidoleukotrienes (LTs) and prostaglandin D2 (PGD2) from the cultured mast cells. METHODS: Using the method established by Saito et al. we cultured cord blood mononuclear cells in the presence of 80 ng/mL stem cell factor (SCF), 50 ng/mL interleukin-6 (IL-6) and 300 nmol/L prostaglandin E2 (PGE2), and obtained almost pure (> 99%) mast cells. We sensitized cultured mast cells with immunoglobulin E (IgE)-rich serum, and then treated them with some anti-asthma drugs before challenge with anti-human IgE. Released histamine, LTs and PGD2 were measured by high-performance liquid chromatography, commercial enzyme-linked immunosorbent assay (ELISA) and enzyme immunoassay (EIA) systems, respectively. RESULTS: The cultured mast cells released histamine, LTs and PGD2 following immunological stimulation through IgE. The mast cell stabilizing agents disodium cromoglycate (DSCG, 1 mmol/L) and azelastine (100 micromol/L) significantly inhibited the release of these three mediators. The beta-adrenoceptor agonists isoproterenol, salbutamol, and clenbuterol also inhibited all three mediators' release in a concentration-dependent manner. The non-selective and selective phosphodiesterase (PDE) inhibitors theophylline, rolipram, and cilostazol had no significant effect on mediator release at clinically useful concentrations. BAY x 1005 (a 5-lipoxygenase-activating protein inhibitor) inhibited the LTs release, whereas indomethacin (a cyclo-oxygenase I and II inhibitor) and NS-398 (a cyclo-oxygenase II inhibitor) inhibited PGD2 release. CONCLUSIONS: The present results indicate that cultured mast cells release histamine, LTs and PGD2 following IgE crosslinking. Anti-asthma drugs showed a characteristic suppression of the release of each mediator. The suppressive actions of these drugs are similar to their pharmacological actions on human lung mast cells. These results suggest that cultured mast cells are useful for the analysis of function and pharmacological profiles of lung mast cells.

Mite antigen-induced IL-4 and IL-13 production by basophils derived from atopic asthma patients.

BACKGROUND: There is increasing evidence for the role of basophils in the pathogenesis of atopic diseases such as bronchial asthma, atopic dermatitis and atopic rhinitis. Recently, it has been reported that basophils derived from healthy donors produce the immunoregulatory cytokines interleukin (IL)-4 and IL-13 after cross-linking of cell surface IgE. In addition to well-known inflammatory mediators, such as histamine and leukotriene C4. these cytokines produced by basophils are also considered to be associated with atopic diseases. OBJECTIVE: Our first objective was to determine whether or not mite-sensitive atopic asthmatic basophils produce IL-4 and IL-13 in response to mite antigens. Our second objective was to investigate the relationship between antigen-specific or nonspecific IgE in the serum and the production of these cytokines in order to determine the association of basophil-derived cytokines with the pathogenesis of atopic asthma. Our final objective was to study how production of these cytokines could be regulated by some anti-asthma drugs. METHODS: Basophils were purified from peripheral venous blood of 67 atopic asthma patients with elevated RAST for the house dust mite. Cells were stimulated with mite antigens for 6 hours and then IL-4 and IL-13 levels in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Mite-sensitive asthmatic basophils produced IL-4 and IL-13 when stimulated with mite antigens. Mite-induced IL-4 production peaked at 6 hours after the stimulation. whereas IL-13 production continued up to 24 hours. The higher the concentration of mite-specific IgE but not total IgE released in the serum, the more IL-4 and IL-13 were produced by basophils in response to mite antigens. The production of these cytokines was significantly suppressed by the anti-asthma drugs theophylline (IL-4, p<0.001, n=6; IL-13, p<0.001, n=10) and dexamethasone (IL-4, p<0.001, n=15; IL-13, p<0.001, n=10). CONCLUSION: Mite-antigen-induced IL-4 and IL-13 production by basophils derived from mite-sensitive asthma patients was associated with the concentration of mite-specific IgE and may play an important role in the pathogenesis of atopic asthma. The inhibitory effect of dexamethasone and theophylline on allergic inflammation may be due to the inhibition of IL-4 and IL-13 production not only by T cells but also by basophils.

Pharmacological modulation of LPS-induced MIP-1 alpha production by peripheral blood mononuclear cells.

In the present study, we investigated the effects of some anti-asthmatic drugs on the production of the CC chemokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha), in response to lipopolysaccharide (LPS) by peripheral blood mononuclear cells (PBMC). MIP-1 alpha production was induced by LPS in a concentration-dependent fashion and reached the maximum at 10 micrograms/ml LPS (27.5 +/- 2.3 ng MIP-1 alpha/10(6) PBMC). At a submaximal concentration of LPS (1 microgram/ml), the release of MIP-1 alpha increased with time and reached the maximum 24 h after LPS stimulation. Actinomycin D and cycloheximide inhibited MIP-1 alpha production completely, but glucocorticoids did not completely inhibit MIP-1 alpha production, with a maximum inhibition of 70%. We examined the effect of beta-stimulants and phosphodiesterase inhibitors, which upregulate intracellular cyclic AMP levels, on MIP-1 alpha production. When PBMC were treated with beta-stimulants alone, beta-stimulants showed a slightly inhibitory effect on MIP-1 alpha production. However, the coadministration of roliplam significantly potentiated the inhibitory effect of beta-stimulants on MIP-1 alpha production. Moreover, db-cAMP suppressed MIP-1 alpha production dose-dependently. The above data indicate that the production of MIP-1 alpha is regulated by cyclic AMP and that cyclic AMP could provide a useful target for therapeutic treatment in asthmatic diseases and other diseases where MIP-1 alpha is involved in their etiology.

Cyclic AMP-elevating agents inhibit mite-antigen-induced IL-4 and IL-13 release from basophil-enriched leukocyte preparation.

Human peripheral blood basophils are known to secrete interleukin (IL)-4 and IL-13 after cross-linking of cell surface IgE. However, little is known about the pharmacological regulation of allergic cytokine release from basophils. In the present study, we investigated the effects of cyclic 3',5'-adenosine monophosphate (cAMP)-elevating agents on antigen-induced IL-4 and IL-13 release from basophil-enriched leukocyte preparations. We obtained venous blood from 27 atopic asthmatic patients (mean age was 45.8+/-3.6 years, all patients were sensitive to mite antigen) and prepared basophil-enriched leukocyte preparations by double-Percoll gradients (basophil purity was 13.4+/-1.6%). The cell preparations were treated with phosphodiesterase (PDE) inhibitors, dexamethasone, forskolin or dibutyryl cAMP for 10 min and were challenged with mite antigen for 6 h. The released IL-4 and IL-13 in the supernatants were measured by enzyme-linked immunosorbent assay systems. No IL-4 or IL-13 was detected in the supernatant of the basophil-depleted preparation after the challenge with mite antigen, suggesting that basophils specifically produce these cytokines. A nonselective PDE inhibitor, theophylline, and a PDE IV-selective inhibitor, rolipram, significantly suppressed the release of IL-4 and IL-13 from the basophil-enriched preparation. Although several concentrations of cilostazol, a PDE III-selective inhibitor, had no effect on the release of both cytokines, cilostazol suppressed the release of IL-4 additively when applied with rolipram. Forskolin and dibutyril cAMP also significantly suppressed the release of both cytokines, suggesting that the suppressive effects by PDE inhibitors were accompanied by the elevations in cAMP levels. We conclude that basophil-enriched leukocyte preparations produce IL-4 and IL-13 in response to antigen and that the release of these cytokines could be regulated by cAMP-modulating agents.

Interferon-beta prevents antigen-induced bronchial inflammation and airway hyperreactivity in mice.

The effects of IFN-beta and prednisolone (Pred) on antigen-induced IgE antibody production, airway eosinophilia and airway hyperreactivity (AHR) were studied in ovalbumin-sensitized Balb/c mice. Three inhalations of antigen (ovalbumin) caused an increase in the number of eosinophils and lymphocytes in bronchoalveolar lavage fluid and AHR to acetylcholine with a significant elevation in the serum IgE level. IFN-beta clearly inhibited the antigen-induced airway inflammation and AHR, but did not affect IgE antibody production. Pred inhibited antigen-induced IgE antibody production, airway inflammation and AHR to acetylcholine. In addition, IFN-beta inhibited T-helper type 2 (Th2) cell clone (D10G4.1)-induced peritoneal eosinophilia in mice, but did not affect neutrophilia, whereas Pred inhibited D10G4.1-induced peritoneal eosinophilia and neutrophilia. These results suggest that IFN-beta inhibits antigen-induced bronchial inflammation and AHR probably due to the inhibition of Th2-induced airway eosinophilia.

Selective growth of human mast cells induced by Steel factor, IL-6, and prostaglandin E2 from cord blood mononuclear cells.

To establish the method for generating a large number of mature human mast cells, we cultured cord blood mononuclear cells (CBMC) in several conditions in the presence of Steel factor (SF). Among several cytokines tested, IL-6 enhanced SF-dependent mast cell growth from purified CD34+ cells for more than 8 wk in culture. When CBMC were cultured instead of CD34+ cells, IL-6 enhanced the mast cell development in the presence but not in the absence of PGE2. PGE2 enhanced the SF- and IL-6-dependent development of mast cells from CBMC probably by blocking granulocyte-macrophage CSF (GM-CSF) secretion from accessory cells, because 1) PGE2, or anti-GM-CSF enhanced the mast cell development induced by SF and IL-6 from CBMC, but not from CD34+ cells; 2) GM-CSF inhibited the enhancing effect of IL-6 on the mast cell development from CD34+ cells; and 3) PGE2 inhibited GM-CSF secretion from CBMC. The mast cells cultured in the presence of SF, IL-6, and PGE2 for >10 wk were 99% pure, and seemed to be functionally mature, because 1) they contained 5.62 micrograms of histamine and 3.46 micrograms of tryptase per 10(6) cells; and 2) when sensitized with human IgE and then challenged with anti-human IgE, the cells released a variety of mediators such as histamine, and an increase in intracellular Ca2+ was found in advance of the activation of membrane movement by using a confocal laser-scanning microscope. Electron-microscopic analysis revealed that some of the cultured mast cells are morphologically mature since they filled with scroll granules and contained crystal granules.

Relationship between histamine release and leukotrienes production from human basophils derived from atopic dermatitis donors.

Basophils are known to release histamine and to produce leukotrienes (LTs) following both IgE-dependent and -independent stimuli. Although there exist a few reports which examined the relationship between histamine release and LTs production, their conclusions were not always in agreement with each other. In the present study, we examined the relationship between histamine release and LTs production from basophils in the presence or absence of 1 ng/ml of interleukin-3 (IL-3). Normal basophils released a smaller amount of histamine and LTs than atopic determatitis (AD) basophils, when basophils were stimulated with an optimal concentration of anti-IgE antibody. When we examined the relationship of histamine release and LTs production from AD donors induced through Fc epsilon RI, we found a significant exponential correlation between these two mediators (R2 = 0.58 in the absence of IL-3, R2 = 0.83 in the presence of IL-3). Although IL-3 enhanced both histamine release and LTs production from AD donors, the relationship between these two mediators was not affected. In conclusion, there was an exponential correlation between histamine release and LTs production from AD basophils, which was not affected by the pretreatment with IL-3.