Antigen-specific IgE Research Articles

Effects of Dietary Lactosucrose (4G-β-D-galactosylsucrose) on the IgE Response in Mice

In this study, we examined the effects of dietary lactosucrose (LS, a non-digestible oligosaccharide) on the IgE response in mice immunized with ovalbumin (OVA)/alum. In addition to IgG1 and IgG2a responses, the anti-OVA IgE response in mice fed LS diets was dose-dependently suppressed, as compared with the control mice, while the serum total IgG levels were comparable. Moreover, dietary LS feeding inhibited antigen-specific IgE and IgG1 productions even after a second immunization. Regarding with cytokine production, when stimulated in vitro with OVA, splenocytes obtained from LS-fed mice produced a similar level of IFN-gamma, and lower levels of IL-4 and IL-5, as compared with the control mice. But IL-10 production by OVA-stimulated splenocytes was augmented in LS-fed mice, suggesting that IL-10 producing cells are responsible for the immunoregulatory effect of LS. Our findings indicate the further possibility that dietary LS supplementation can be used to prevent IgE-mediated allergic diseases.

Regulatory dendritic cells protect against allergic airway inflammation in a murine asthmatic model

Dendritic cells (DCs) are crucial for the induction of immunity and tolerance. Despite an improved understanding of the DC-mediated control of T(H)1-biased immunity, little is known about how DCs regulate T(H)2-mediated immunity. The effects of immunostimulatory mature DCs (maDCs) and regulatory DCs (DCregs) on T(H)2-driven allergic immunity involving IgE production were examined. A murine model of airway hyperresponsiveness; the adoptive transfer of maDCs, DCregs, and T cells; and T-cell function were studied. Antigen-pulsed maDCs inhibited antigen-specific IgE production but enhanced the production of antigen-specific IgG1 and IgG2a. Analysis of Ifng-/- mice and Il21r-/- mice revealed that the inhibitory effect of antigen-pulsed maDCs on antigen-specific IgE production involved IL-21-producing T follicular helper cells but not IFN-gamma-producing T(H)1 cells. In contrast, antigen-pulsed DCregs impaired the production of antigen-specific IgE, IgG1, and IgG2a. In vivo blockade experiments showed that antigen-specific CD4+CD25+Foxp3+ regulatory T cells mainly mediated the suppressive effect of antigen-pulsed DCregs on the production of antigen-specific IgE. Antigen-pulsed maDCs promoted airway inflammation, whereas antigen-pulsed DCregs markedly suppressed the pathogenesis. DCregs abolish T(H)2-mediated IgE production and allergic inflammation based on antigen-specific dominant tolerance, whereas maDCs exacerbate the pathogenesis despite inhibiting the IgE response through the activation of diverse types of T(H) cell responses.

Effect of ageing on pulmonary inflammation, airway hyperresponsiveness and T and B cell responses in antigen‐sensitized and ‐challenged mice

The effect of ageing on several pathologic features of allergic asthma (pulmonary inflammation, eosinophilia, mucus hypersecretion), and their relationship with airway hyperresponsiveness (AHR) is not well characterized. To evaluate lung inflammation, mucus metaplasia and AHR in relationship with age in murine models of allergic asthma comparing young and older mice. Young (6 weeks) and older (6, 12, 18 months) BALB/c mice were sensitized and challenged with ovalbumin (OVA). AHR and bronchoalveolar fluid (BALF), total inflammatory cell count and differential were measured. To evaluate mucus metaplasia, quantitative PCR for the major airway mucin-associated gene, MUC-5AC, from lung tissue was measured, and lung tissue sections stained with periodic acid-Schiff (PAS) for goblet-cell enumeration. Lung tissue cytokine gene expression was determined by quantitative PCR, and systemic cytokine protein levels by ELISA from spleen-cell cultures. Antigen-specific serum IgE was determined by ELISA. AHR developed in both aged and young OVA-sensitized/challenged mice (OVA mice), and was more significantly increased in young OVA mice than in aged OVA mice. However, BALF eosinophil numbers were significantly higher, and lung histology showed greater inflammation in aged OVA mice than in young OVA mice. MUC-5AC expression and numbers of PAS+ staining bronchial epithelial cells were significantly increased in the aged OVA mice. All aged OVA mice had increased IL-5 and IFN-gamma mRNA expression in the lung and IL-5 and IFN-gamma protein levels from spleen cell cultures compared with young OVA mice. OVA-IgE was elevated to a greater extent in aged OVA mice. Although pulmonary inflammation and mucus metaplasia after antigen sensitization/challenge occurred to a greater degree in older mice, the increase in AHR was significantly less compared with younger OVA mice. Antigen treatment produced a unique cytokine profile in older mice (elevated IFN-gamma and IL-5) compared with young mice (elevated IL-4 and IL-13). Thus, the airway response to inflammation is lessened in ageing animals, and may represent age-associated events leading to different phenotypes in response to antigen provocation.

The α-adrenoceptor mediation of the immunomodulatory effects of electroacupuncture in DNP-KLH immunized mice

Our previous study demonstrated that successive electroacupuncture (EA) at ST36 acupoint reduces IgE production in BALB/c mice immunized with 2,4-dinitrophenylated keyhole limpet protein (DNP-KLH) by suppression of the Th2 cell lineage development. Here, we report that pretreatment of phentolamine (alpha-adrenoceptor antagonist, 10mg/kg, i.p.) completely blocks the EA-induced suppression of antigen-specific and total IgE levels in serum and IL-4 production in anti-CD3 mAb-activated splenocytes in DNP-KLH immunized mice. The results suggest that alpha-adrenoceptor play an important role in mediating the suppressive effects of EA on IgE production and Th2 cell response in DNP-KLH immunized mice.

Alterations of food antigen‐specific serum immunoglobulins G and E antibodies in patients with irritable bowel syndrome and functional dyspepsia

Post-prandial worsening of symptoms as well as adverse reactions to one or more foods are common in the patients with functional gastrointestinal diseases, such as irritable bowel syndrome (IBS) and functional dyspepsia (FD). However, the role played by true food allergy in the pathogenesis of these diseases is still controversial and there are no well-established tests to identify food allergy in this condition. To investigate serum food antigen-specific IgG, IgE antibody and total IgE antibody titres in controls and patients with IBS and FD, and to correlate symptoms with the food antigen-specific IgG titres in IBS and FD patients. Thirty-seven IBS patients, 28 FD patients and 20 healthy controls participated in this study. Serum IgG and IgE antibody titres to 14 common foods including beef, chicken, codfish, corn, crab, eggs, mushroom, milk, pork, rice, shrimp, soybean, tomatoes and wheat were analysed by ELISA. Serum total IgE titres were also measured. Last, symptomatology was assessed in the study. Results IBS patients had significantly higher titres of IgG antibody to crab (P=0.000), egg (P=0.000), shrimp (P=0.000), soybean (P=0.017) and wheat (P=0.004) than controls. FD patients had significantly higher titres of IgG antibody to egg (P=0.000) and soybean (P=0.017) than controls. The percentage of individuals with detectable positive food antigen-specific IgE antibodies of the three groups did not show any significant differences (P=0.971). There were no significant differences between IBS patients, FD patients and controls in the serum total IgE antibody titres (P=0.978). Lastly, no significant correlation was seen between symptom severity and serum food antigen-specific IgG antibody titres both in IBS and FD patients. Serum IgG antibody titres to some common foods increased in IBS and FD patients compared to controls. But there is no significant correlation between symptom severity and elevated serum food antigen-specific IgG antibodies in these patients.

Lipoteichoic acid downregulates FcεRI expression on human mast cells through Toll-like receptor 2

FcepsilonRI on the surface of mast cells (MCs) plays a central role in allergic responses. Recent evidence shows that exposure to microbial components corresponds with a significant reduction in the risk for allergic diseases. Although many reports suggest that this is due to changes in T-cell functions, how MC functions are altered by bacterial infection remains unknown. We sought to elucidate the effect of bacterial infection on MC function and expression of Fc receptors, such as FcepsilonRI. Isolated human pulmonary MCs and a human MC line (LAD2) were stimulated with bacterial components, and the function and surface expression of Fc receptors were measured. Lipoteichoic acid (LTA) and peptidoglycan, but not LPS, flagellin, or 3CpG-oligodeoxynucleotide, reduced the expression of FcepsilonRI on LAD2 cells. An antibody to Toll-like receptor (TLR) 2 partially blocked the effect of LTA but not peptidoglycan. Both LTA and peptidoglycan reduced MC degranulation caused by an antigen-specific IgE. Furthermore, exposure of pulmonary MCs to LTA reduced both FcepsilonRI expression and IgE-induced degranulation. None of the bacterial components affected the expression of other Fc receptors, such as Fcgamma receptors or Fcalpha receptor I. Our results indicate that LTA reduces the surface expression of FcepsilonRI through TLR2 and suggests that TLR2 ligands could be used as a novel therapy for controlling allergic disorders. By knowing how bacterial components modulate MC function, we can expand our possibilities for therapeutic interventions of allergic diseases.

Sublingual immunotherapy in sensitized mice

Many studies have demonstrated immunologic changes induced by sublingual immunotherapy (SLIT), but the definitive mechanism of action needs further investigation. To study the immunologic response induced by SLIT in sensitized mice. Timothy grass (Phleum pratense)-sensitized mice received SLIT for 2, 4, or 6 weeks at 3 different concentrations, including a buffer control. Serum samples and washes of the lungs (bronchoalveolar lavage [BAL]) and the nasal passages (nasal lavage [NAL]) were analyzed for allergen-specific antibodies. T cells were isolated from the spleen and cervical lymph nodes for the analysis of proliferation and cytokine production. Sublingual immunotherapy in sensitized mice resulted in a 30-fold increase in antigen specific IgA levels in BAL and NAL fluid compared with buffer-treated mice, whereas antigen specific IgE was undetectable in BAL and NAL fluid in animals treated with SLIT. Furthermore, IgA levels were proportional to the dose and duration of SLIT. Levels of specific IgA in serum correlated with levels in BAL and NAL fluid. Serum IgA levels were proportional to the duration of allergen exposure to the oral mucosa. Conversely, no changes in serum levels of IgE and IgG were induced by SLIT. Proliferation of T cells was increased in mice treated with SLIT compared with nontreated mice. High levels of IgA in serum and in BAL and NAL fluid of mice treated with SLIT demonstrate that SLIT induces a mucosal, nonallergic response in sensitized mice.

Basophils function as initiators rather than effectors in IgE-mediated chronic allergic inflammation, independently of T cells and mast cells (38.6)

Abstract Basophils have often been considered as minor and possibly redundant “circulating mast cells”. We recently demonstrated that basophils play a pivotal role in the development of IgE-mediated chronic allergic inflammation (IgE-CAI), independently of T cells and mast cells. A single subcutaneous injection of multivalent antigens elicited not only immediate- and late-phase ear swelling but also delayed-onset ear swelling with massive eosinophil infiltration in mice sensitized with antigen-specific IgE. Here, we show that basophils function as initiators of the recruitment of eosinophils and neutrophils rather than effectors of inflammation in IgE-CAI. Even though basophils accounted for only 1–2% of the infiltrating cells in the skin legions, treatment of the IgE-sensitized mice with a newly-developed basophil-depleting mAb during the progression of IgE-CAI resulted in suppression of delayed-onset ear swelling with drastic reduction in numbers of not only basophils but also eosinophils and neutrophils infiltrating in the skin legions. Upon activation with IgE and corresponding antigens in vitro, basophils secreted soluble factors that stimulated skin adherent cells to produce soluble factors capable of attracting eosinophils and neutrophils. These findings indicate a novel mechanism of development of chronic allergic inflammation that is initiated and amplified by basophils.

Blocking OX40L Function Inhibits TSLP-Induced Atopic Disease In Lung And Skin (37.11)

Abstract OX40L-OX40 interactions have been shown to be important for development of Th2-mediated diseases such as asthma through the use of mouse models in vivo. Thymic Stromal LymphoPoietin (TSLP), an IL7-like cytokine, has been shown to potently induce atopic immune responses and is highly expressed at sites of allergic inflammation. While the ability of TSLP to effectively induce an atopic immune cascade has been demonstrated through the use of transgenic mice, direct downstream in vivo mediators have not been identified. In our current study, we show that OX40L is a critical mediator of TSLP-mediated Th2 responses not only in vitro but also in vivo. TSLP strongly induces OX40L expression on dendritic cells and blocking a-OX40L antibodies efficiently inhibit Th2 responses induced by TSLP in vitro, and in the lung and skin in vivo. Inhibition of OX40L function was also very efficacious in decreasing Th2 cytokines and antigen-specific IgE in a mouse model of OVA-induced asthma. The use of blocking a-OX40L antibodies thus presents an effective strategy for the treatment of allergic disease associated with dysregulated Th2 immune responses. The source of research support is Genentech, Inc.

The neurotrans mechanism of electronic-acupuncture in DNP-KLH immunized mice. (B21)

Abstract Our previous study demonstrated that successive electroacupuncture (EA) at the ST36 acupoint reduces IgE production in BALB/c mice immunized with 2,4-dinitrophenylated keyhole limpet protein (DNP-KLH) by suppression of the Th2 cell lineage development. Here we report that pretreatment of phentolamine (¥á-adrenergic receptor antagonist, 10 mg/kg, i.p.) completely blocks the EA-induced suppression of antigen-specific and total IgE levels in serum, and IL-4 production in anti-CD3 mAb-activated splenocytes in DNP-KLH immunized mice. And pretreatment of Y-25130 (5HT3 receptor antagonist, 3 mg/kg, i.p.) partly blocks EA-induced suppression effect shown above. These results suggest that ¥á-adrenergic receptor play an important role in mediating the suppressive effects of EA on IgE production and Th2 cell response in DNP-KLH immunized mice, and 5HT3 receptor play as a minor factor. This work was supported by the Brain Korea 21 project in 2007

Active Induction of Tumor-Specific IgE Antibodies by Oral Mimotope Vaccination

A role of IgE antibodies in cancer surveillance has been implicated for a long time. Studies dealing with IgE antibodies directly targeted to tumor antigens have shown marked anticancer effects mediated by this antibody class. Thus, the basic function of IgE antibodies may be to control tumor growth. Thus far, cancer-specific IgE has only been applied passively. Consequently, the aim of this study was to establish an active vaccination protocol to induce tumor antigen-specific IgE antibodies, and to evaluate functional properties. We previously generated epitope mimics, so-called mimotopes, for the epitope recognized by the anti-HER-2 antibody trastuzumab. Upon i.p. immunizations, IgG antibodies with trastuzumab-like properties could be elicited. In the present study, we immunized BALB/c mice via the oral route with these trastuzumab mimotopes, under simultaneous neutralization and suppression of gastric acid. As shown in preceding experiments, this feeding regimen effectively induces Th2 immune responses. Oral immunizations with trastuzumab mimotopes under hypoacidic conditions indeed resulted in the formation of IgE antibodies towards the HER-2 antigen. Moreover, anti-HER-2 IgE-sensitized effector cells mediated SK-BR-3 target cell lysis in an antibody-dependent cytotoxicity assay. We conclude that directed and epitope-specific induction of IgE against tumor antigens is feasible with an oral mimotope vaccination regimen, and that these antibodies mediate anticancer effects.

Regulatory role of Peyer’s patches for the inhibition of OVA-induced allergic diarrhea

Intestinal allergic diseases are initiated by aberrant Th2-type immune responses, including elevation of IgE antibodies (Abs) and infiltration of eosinophils. However, little is known about the role of Peyer’s patches (PP) in the control of allergic diseases. Using a mouse model for food allergy, we here show that mice lacking PP are more susceptible to disease development and show higher levels of antigen-specific IgE Abs than do PP-intact mice. In our study, we noted that high numbers of eosinophils infiltrated into the small intestine of PP-null mice. In contrast, the PP of intact mice contained regulatory CD4 +CD25 + Foxp3 + T cells (Treg) that are known to produce high levels of IL-10, and inhibited the development of allergic diarrhea. PP-intact mice thus developed allergic diarrhea when treated with anti-CD25 or anti-IL-10 monoclonal antibody (mAb) in vivo. These studies demonstrate that PP, as the site where IL-10-producing Treg cells are created, mediate the mucosal regulatory network for the control of undesired allergic responses in the intestine.

Dose-dependent recruitment of CD25+ and CD26+ T cells in a novel F344 rat model of asthma

The ovalbumin (OVA)-induced airway inflammation in rats is a commonly used model to explore the pathobiology of asthma. However, its susceptibility varies greatly between rat strains, and presently Brown Norway (BN) rats are preferentially used. Since recruitment of T cells to the lungs depends on the CD26 (dipeptidyl peptidase IV, DPPIV) expression, Fischer 344 strain (F344) rats are a highly relevant rat strain, in particular because CD26-deficient substrains are available. To establish a F344 rat model of asthma, we challenged F344 rats using different doses of aerosolized antigen (0%, 1%, 2.5%, 5%, and 7.5% OVA) and compared these effects with intratracheal instillation of OVA (1.5 mg/0.3 ml). Asthmoid responsiveness was determined by analysis of early airway responsiveness (EAR), antigen-specific IgE levels, as well as airway inflammation including the composition of T cell subpopulations in the bronchoalveolar lavage (BAL) and lung tissue with special respect to the T cell activation markers CD25 and CD26. Even low allergen doses caused allergen-specific EAR and increases of antigen-specific IgE levels. However, EAR and IgE levels did not increase dose dependently. Higher concentrations of OVA led to a dose-dependent increase of several immunological markers of allergic asthma including an influx of eosinophils, T cells, and dendritic cells. Interestingly, a dose-dependent increase of CD4(+)/CD25(+)/CD26(+) T cells was found in the lungs. Summarizing, we established a novel F344 rat model of aerosolized OVA-induced asthma. Thereby, we found a dose-dependent recruitment of cellular markers of allergic asthma including the activated CD4(+)/CD25(+)/CD26(+) T cell subpopulation, which has not been described in asthma yet.

Oral administration of an IL-10–secreting Lactococcus lactis strain prevents food-induced IgE sensitization

Because tolerance to food is potentially modulated by IL-10, strategies to prevent food allergy should favor an increased delivery of IL-10 to the gut. We hypothesized that administration of a Lactococcus lactis transfected to secrete murine IL-10 could prevent sensitization in a mouse model of food allergy. Before each oral sensitization with beta-lactoglobulin in the presence of cholera toxin, young mice were administered the transfected Lactococcus lactis. Antigen-induced anaphylaxis after oral challenge assessed clinical protection achieved by the pretreatment. Serum and feces antigen-specific antibody concentrations were sequentially measured. Antibody titers were correlated with antibody and IL-10-secreting cell numbers in the spleen and in Peyer patches. Pretreatment with transfected Lactococcus lactis contributed to diminish anaphylaxis significantly, and inhibit antigen-specific serum IgE and IgG(1) production strongly. In addition, transfected Lactococcus lactis increased the production of antigen-specific IgA in the gut. Variations of antibody levels in the serum and the gut correlated with the numbers of antibody-producing cells. In addition, the presence of exogenous IL-10 in the gut by transfected Lactococcus lactis induced IL-10 secretion by Peyer patches cells. Increased IL-10 titers were also measured in the plasma. These results suggest that a microorganism bioengineered to deliver IL-10 in the gut can decrease food-induced anaphylaxis and provide an option to prevent IgE-type sensitization to common food allergens. Nonpathogenic IL-10-producing microorganisms in the gut could have a potential to prevent systemic food-induced anaphylaxis.

Establishment of an allergic rhinitis model in mice for the evaluation of nasal symptoms

The purpose of our study was to establish a new model of allergic rhinitis in mice, eliciting symptoms such as sneezing, infiltration of eosinophils into the nasal mucosa, and antigen-specific IgE production. One of the major human T-cell epitopes in Cry j 1, an allergen of Japanese cedar pollen, is also a major murine T-cell epitope in B10.S mice. Thus we tried to establish an allergic rhinitis model in B10.S mice with Cry j 1 as the antigen. We sensitized B10.S mice subcutaneously with Cry j 1/alum three times at intervals of 1 week. Five weeks after the final sensitization, we challenged the mice by instilling Cry j 1 intranasally from the day after intranasal histamine pretreatment. Soon after, we counted the number of sneezes. We then evaluated the infiltration of eosinophils into the nasal tissues and also measured the serum levels of antigen-specific IgE antibody. In addition, we confirmed the effects of ketotifen fumarate and dexamethasone hydrochloride on these animals. In Cry j 1-sensitized B10.S mice, sneezes, eosinophil peroxidase (EPO) activity in nasal tissues, and Cry j 1-specific IgE clearly increased after intranasal histamine pretreatment and 5 days of continuous intranasal Cry j 1 challenge. Both ketotifen and dexamethasone inhibited the increase in sneezing, and dexamethasone also inhibited EPO activity and Cry j 1-specific IgE. Thus we succeeded in establishing a new model of allergic rhinitis in Cry j 1-sensitized B10.S mice, which exhibited sneezing, eosinophil infiltration into the nasal mucosa, and Cry j 1-specific IgE production.

Effect of House Dust Mite (HDM) Avoidance Measure on The Clinical Symptoms in Dogs with Atopic Dermatitis (AD)

RATIONALE: Majority of dogs with atopic dermatitis (AD) are known to be spontaneously sensitive to house dust mite (HDM) allergen. Canine AD can be utilized as an animal model for human AD. We examined effect of HDM avoidance measure on the clinical symptoms in 6 dogs with AD. METHODS: Six dogs that suffered from AD and were sensitive to HDM allergen were enrolled. Clinical diagnosis with AD was based on Willemse's criteria. All of the 6 dogs were shown to be sensitive to HDM allergen by measurement of antigen-specific serum IgE or intradermal skin test. HDM avoidance measure was performed by withdrawing conventional bedding and introducing HDM-free bedding in the owner's houses. The clinical symptoms of the dogs were quantitatively evaluated by recording pruritus score, skin lesion index, and medication score before, during, and after the HDM avoidance measure for 6 months. RESULTS: Before the trial, Der 1 levels were 0.55∼35.0 μg/g of fine dust (mean 1.6 μg/g) in the bedding and 0.25∼8.8 μg/g (mean 1.8 μg/g) on the floor. After the trial, they decreased to 0.02∼0.37 μg/g (mean 0.1 μg/g) in the bedding and 0.04∼0.92 μg/g (0.3 μg/g) on the floor. Scores of the clinical symptoms of AD clearly decreased in 4 of the 6 dogs with AD after the trial. Serum HDM-specific IgE levels in 3 dogs examined also markedly decreased after the trial. CONCLUSIONS: Decreasing the amount of Der 1 in the house may have an efficacy to control the clinical symptom in dogs with AD.

Anti-IgE mAb Suppresses Systemic Anaphylaxis through the Inhibitory IgG Receptor FcγRIIb in Mice: Interaction between Anti-IgE and FcγRIIb

Anti-IgE mAb which binds circulating but not receptor-bound IgE has been shown to be effective in treatment for asthma and other allergic diseases. However, the mechanisms by which anti-IgE mAb influences the pathophysiological responses are remained to be illustrated. This study was undertaken to examine the therapeutic efficacy of non-anaphylactogenic anti-mouse IgE mAb using murine models of IgE-induced systemic fatal anaphylaxis. Methods: Active systemic anaphylaxis was induced by either penicillin V(Pen V) or OVA and passive systemic anaphylaxis was induced by either anaphylactogenic anti-mouse IgE or a mixture of anti-chicken gamma globulin (CGG) IgG1 mAb and CGG. The binding of the Fc portion of anti-IgE to CHO-stable cell line expressing mouse Fc γ RIIb was examined using flow cytometry. Fc fragments of anti-IgE mAb were prepared using papain digestion. The expression of phosphatases in lungs were assessed by Western blotting and immunohistochemistry. Results: Anti-IgE mAb prevented IgE- and IgG-induced active and passive systemic fatal reactions. In both types of anaphylaxis, anti-IgE mAb suppressed antigen-specific IgE responses, but not those of IgG. Anti-IgE mAb neither prevented anaphylaxis nor suppressed the IgE response in Fc γ RIIb-deficient mice. The Fc portion of anti-IgE mAb was bound to murine Fc γ RIIb gene-transfected CHO cells and inhibited systemic anaphylaxis. Anti-IgE mAb blocked the anaphylaxis-induced downregulation of Fc γ RIIb-associated phosphatases such as src homology 2 domain-containing inositol 5-phosphatase (SHIP) and phosphatase and tensin homologue deleted on chromosome ten (PTEN). Conclusion: Anti-IgE mAb prevented anaphylaxis by delivering nonspecific inhibitory signals through the inhibitory IgG receptor, Fc γ RIIb, rather than targeting IgE.

Interleukin-4 Receptor Alpha Chain ITIM Motif Mutant Mice Potentiate Stat6 Activation and IgE Production

RATIONALE: Signaling via the IL-4 receptor alpha chain (IL-4Rα) plays a critical role in the evolution of Th2 responses and the pathology of allergic diseases such as asthma. The IL-4Rα is endowed with an immunoreceptor tyrosine-based inhibitory motif (ITIM) at the fifth tyrosine residue in the cytoplasmic domain of IL-4Rα (Y709). This motif binds a number of SH2-containing phosphatases, including SHP-1, SHP-2, and SHIP. Its role in vivo remains unclear. METHODS: The in vivo function of this ITIM motif in IL-4R signaling was analyzed in mutant mice in which the Y709 residue was mutated into phenylalanine (Y709F) by knockin mutagenesis. RESULTS: B cells from the Y709F mutation demonstrated enhanced Stat6 but not Jak1 phosphorylation following IL-4 stimulation. In vivo, the Y709F mutant mice exhibited increased baseline levels of IgE in the serum and augmented total and antigen-specific IgE responses following immunization. T lymphocytes from this mutation also exhibit significantly increased production of IL-4 in a Th2 polarized milieu. CONCLUSIONS: These results point to a negative regulatory role for the Y709 ITIM motif in signaling via IL-4Rα in vivo. Mutations or polymorphisms that affect ITIM function may play an important role in disease pathogenesis of allergic inflammation such as asthma.

Effects of Dietary Nucleotides on Immune Responses

In this study, the effects of dietary nucleotides on the immune response balance between T helper cells type 1 (Th1) and type 2, and on the mucosal immune response in weanling mice were investigated. It was demonstrated that dietary nucleotides up-regulate the Th1 immune response and suppress the antigen-specific IgE antibody response in weanling mice. Thus, the results suggest that dietary nucleotides may be beneficial for the prevention of allergic diseases in early infancy. In addition, it was shown that dietary nucleotides increased the proportion of a γδT-cell receptor (TCR) -bearing intestinal intraepithelial lymphocyte (IEL) subset, IL-7 production by intestinal epithelial cells and the antigen-specific IgA response. Therefore, the present study indicates that dietary nucleotides may have an effect on the mucosal intranet in the intestinal mucosal immune system.

Inhibition of antigen-induced degranulation and IL-4 production from RBL-2H3 cells by Lavandula hybrida and L. angustifolia extracts

Allergic diseases are considered to be multifactorial inflammatory diseases that present a serious health problem worldwide while their prevalence have continuously increased during the past few decades. They are results of type I hypersensitivity mediated through the effects of antigen-specific IgE which binds to mast cells and, on subsequent cross-linking by allergen reexposure, causes cell degranulation with the release of preformed mediators in the early-phase as well as the production of cytokines in the late-phase. The aim of our study was to investigate the antiallergic activities of cultivated Lavandula hybrida Rev. and L. angustifolia P. Mill. using the rat basophilic leukaemia cell line (RBL-2H3), a well-characterised in vitro model of mast cells. The ethanolic extracts of flowers of L. hybrida (LHE) and L. angustifolia (LAE) were found to significantly inhibit release of β-hexosaminidase, the marker of antigen-IgE-mediated degranulation in RBL-2H3 cells, showing similar activities (IC50=37µg/mL and IC50=42µg/mL, respectively). Furthermore, using the enzyme-linked immunosorbent assay (ELISA), we established that LHE and LAE inhibit antigen-induced production of anti-inflammatory cytokine IL-4 (IC50=60µg/mL and IC50=45µg/mL, respectively). Among ten investigated principal bioactive compounds, luteolin, apigenin and ursolic acid were found to be the most potent inhibitors of degranulation as well as cytokine production. In conclusion, the tested extracts showed antiallergic effects acting on the both phases of type I reaction. Therefore, our results suggest a possible therapeutic application of Lavandula species in allergy and allergy-related diseases.