Central role of immunoglobulin (Ig) E in the induction of lung eosinophil infiltration and T helper 2 cell cytokine production: inhibition by a non-anaphylactogenic anti-IgE antibody

Ablation of tumor progression locus 2 promotes a type 2 Th cell response in Ovalbumin-immunized mice

The protein kinase encoded by the Tpl2 proto-oncogene regulates ERK activation and cytokine gene expression in macrophages in response to LPS and TNF-alpha. In this study we show that OVA-immunized Tpl2(-/-) mice express high levels of IgE and develop more severe bronchoalveolar eosinophilic inflammation than Tpl2(+/+) controls, when challenged with OVA intranasally. Bronchoalveolar exudates and supernatants of OVA-stimulated splenocytes from immunized Tpl2(-/-) mice express elevated levels of IL-4 and IL-5, suggesting that Tpl2 ablation promotes the Th2 polarization of the T cell response. Anti-CD3 stimulation of CD4(+) T cells of wild-type and Tpl2 knockout mice revealed that Tpl2 ablation gives rise to a cell autonomous T cell defect that is primarily responsible for the Th2 polarization of the T cell response to Ag. This observation was further supported by experiments addressing the expression of Th1 and Th2 cytokines in OVA-stimulated mixed cultures of CD4(+) T cells from Tpl2(+/+)/OT2 or Tpl2(-/-)/OT2 mice and dendritic cells from Tpl2(+/+) or Tpl2(-/-) mice. Further studies revealed that Th1 cells express significantly higher levels of Tpl2 than Th2 cells. As a result, Tpl2(-/-) Th1 cells exhibit a stronger defect in ERK activation by anti-CD3 than Th2 cells and express low levels of T-bet. Given that the development of Th1 and Th2 cells depends on positive feedback signals from the T cells, themselves, the functional defect of the Tpl2(-/-) Th1 cells provides a mechanistic explanation for the T cell autonomous Th2 polarization in Tpl2(-/-) mice.

Similar response in male and female B10.RIII mice in a murine model of allergic airway inflammation

BACKGROUND

Several reports have been published on the gender differences associated with allergies in mice.

GOAL

In the present study we investigate the influence of gender on allergy response using a strain of mice, B10.RIII, which is commonly used in the collagen-induced arthritis murine model.

METHODS

Both male and female B10.RIII young mice were immunized with OVA and challenged four times with OVA intranasally. Samples were taken 24 h after the last challenge, and eosinophils in bronchoalveolar lavage (BAL) and parenchyma, Th-2 cytokines in BAL, total and antigen-specific IgE in sera, and antigen-specific T-cell proliferation were measured.

RESULTS

Immunization in both male and female B10.RIII mice with OVA elicited a classical Th2-type response. Results showed no significant differences among male and female mice. Also a high eosinophilia in BAL fluid and parenchyma was produced in both genders without any significant differences. However, the deviation of both parameters was higher in young males compared to young females.

CONCLUSIONS

Gender differences, classically associated with some strains of mice, are not reproducible in B10.RIII mice. Gender differences in murine models of allergic airway inflammation are probably strain-dependent.

Therapeutic manipulation of immune tolerance in allergic disease

Immune tolerance - the adaptation of the immune system to external antigens or allergens - might be therapeutically manipulated to restore normal immunity in conditions such as allergy, asthma and autoimmune diseases. The field of allergen-specific immunotherapy is experiencing exciting and novel developments for the treatment of allergic and autoimmune diseases, and recent insights into the reciprocal regulation and counter-balance between different T-cell subsets is foreseen to facilitate new strategies for immunointervention. This Review highlights current knowledge of immunomodulatory therapies for the manipulation of immune tolerance and highlights recent approaches to improve allergen-specific immunotherapy for the treatment of allergic diseases.

Animal models of airway inflammation and airway smooth muscle remodelling in asthma

Asthma is a complex disease that involves chronic inflammation and subsequent decline in airway function. The widespread use of animal models has greatly contributed to our understanding of the cellular and molecular pathways underlying human allergic asthma. Animal models of allergic asthma include smaller animal models which offer 'ease of use' and availability of reagents, and larger animal models that may be used to address aspects of allergic airways disease not possible in humans or smaller animal models. This review examines the application and suitability of various animal models for studying mechanisms of airway inflammation and tissue remodelling in allergic asthma, with a specific focus on airway smooth muscle.

Comparison of allergic lung disease in three mouse strains after systemic or mucosal sensitization with ovalbumin antigen

Murine models of allergic lung disease have many similar traits to asthma in humans and can be used to investigate mechanisms of allergic sensitization and susceptibility factors associated with disease severity. The purpose of this study was to determine strain differences in allergic airway inflammation, immunoglobulin production, and changes in respiratory responses between systemic and mucosal sensitization routes in BALB/cJ, FVB/NJ, and C57BL/6J, and to provide correlations between immune and pathophysiological endpoints. After a single intranasal ovalbumin (OVA) challenge, all three strains of mice systemically sensitized with OVA and adjuvant exhibited higher airflow limitation than non-sensitized mice. No changes were seen in mice that were pre-sensitized via the nose with OVA. Systemic sensitization resulted in an elevated response to methacholine (MCH) in BALB/cJ and FVB/NJ mice and elevated total and OVA-specific IgE levels and pulmonary eosinophils in all three strains. The mucosal sensitization and challenge produced weaker responses in the same general pattern with the C57BL/6J strain producing less serum IgE, IL5, IL13, and eosinophils in lung fluid than the other two strains. The converse was found for IL6 where the C57BL/6J mice had more than twice the amount of this cytokine. The results show that the FVB/NJ and BALB/cJ mice are higher Th2-responders than the C57BL/6J mice and that the levels of pulmonary eosinophilia and cytokines did not fully track with MCH responsiveness. These differences illustrate the need to assess multiple endpoints to provide clearer associations between immune responses and type and severity of allergic lung disease.

Airway smooth muscle in asthma: phenotype plasticity and function

Clinical asthma is characterized by reversible airway obstruction which is commonly due to an exaggerated airway narrowing referred to as airway hyperresponsiveness (AHR). Although debate exists on the complex etiology of AHR, it is clear that airway smooth muscle (ASM) mediated airway narrowing is a major contributor to airway dysfunction. More importantly, it is now appreciated that smooth muscle is far from being a simple cell with only contractile ability properties. Rather, it is more versatile with the capacity to exhibit numerous cellular functions as it adapts to the microenvironment to which it is exposed. The emerging ability of individual smooth muscle cells to undergo changes in their phenotype (phenotype plasticity) and function (functional plasticity) in response to physiological and pathological cues is an important and active area of research. This article provides a brief review of the current knowledge and emerging concepts in the field of ASM phenotype and function both under healthy and asthmatic conditions.

Hematopoietic protein tyrosine phosphatase mediates beta2-adrenergic receptor-induced regulation of p38 mitogen-activated protein kinase in B lymphocytes

Stimulation of the beta(2)-adrenergic receptor (beta(2)AR) on a CD40L/interleukin-4-activated B lymphocyte increases the level of immunoglobulin E (IgE) in a protein kinase A (PKA)- and p38 mitogen-activated protein kinase (MAPK)-dependent manner. However, the mechanism by which beta(2)AR stimulation mediates the increase in the level of p38 MAPK activation has remained unclear. Here we show that the beta(2)AR-induced increase in p38 MAPK activation occurred via a hematopoietic protein tyrosine phosphatase (HePTP)-mediated cross talk between PKA and p38 MAPK. beta(2)AR agonists, cAMP-elevating agents, and PKA inhibitors were used to show that beta(2)AR stimulation resulted in a PKA-dependent increase in p38 MAPK phosphorylation. Pharmacological agents and gene-deficient mice revealed that p38 MAPK phosphorylation was regulated by the G-stimulatory (Gs)/cAMP/PKA pathway independently of the G-inhibitory or beta-arrestin-2 pathways. Coimmunoprecipitation and Western blot analysis showed that HePTP was phosphorylated in a PKA-dependent manner, which inactivated HePTP and allowed for increased free p38 MAPK to be phosphorylated by the MAPK cascade that was activated by CD40L. HePTP short hairpin RNA confirmed that HePTP played a role in regulating the level of p38 MAPK phosphorylation in a B cell. Thus, beta(2)AR stimulation on a B cell phosphorylates and inactivates HePTP in a Gs/cAMP/PKA-dependent manner to release bound p38 MAPK, making more available for phosphorylation and subsequent IgE regulation.

YM-341619 suppresses the differentiation of spleen T cells into Th2 cells in vitro, eosinophilia, and airway hyperresponsiveness in rat allergic models

T helper (Th) 2 cells play a central role in the pathogenesis of allergic diseases such as allergic asthma, atopic dermatitis, and allergic rhinitis. We have found that YM-341619 hydrochloride, which suppressed IL-4-induced STAT6-dependent reporter gene expression, inhibited the differentiation of mouse spleen T cells into Th2 cells in vitro. YM-341619 suppressed the production of IL-4 and the expression of GATA-3 mRNA, a Th2 transcription factor, in T cells cultured with anti-CD3 antibody and anti-CD28 antibody in the presence of IL-4. In contrast, the production of IFN-gamma and the expression of T-bet mRNA, a Th1 transcription factor, in T cells cultured with anti-CD3 antibody in the presence of IL-12, were not effected by YM-341619. Orally administered YM-341619 (0.003-0.03 mg/kg) reduced the plasma IgE level of DNP-Ascaris-sensitized rats, but not the IgG(2a) level. YM-341619 suppressed IL-4 and IL-13 production in the splenocytes of these DNP-Ascaris-sensitized rats without augmenting IFN-gamma production. YM-341619 also dose-dependently suppressed eosinophil accumulation in the lung (0.003-3 mg/kg, p.o.) and airway hyperresponsiveness (0.3-3 mg/kg, p.o.) induced by repeated exposure to ovalbumin in ovalbumin-sensitized rats. These results suggest that YM-341619 has the ability to suppress allergen-induced Th2 responses by selectively inhibiting the differentiation of CD4(+) T cells into the Th2 subset.

Synthetic oligonucleotides as modulators of inflammation

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs mimic the immunostimulatory activity of bacterial DNA. CpG ODN directly stimulate human B cells and plasmacytoid dendritic cells, promote the production of Th1 and proinflammatory cytokines, and trigger the maturation/activation of professional APC. CpG ODN are finding use in the treatment of cancer, allergy, and infection. In contrast, ODN containing multiple TTAGGG motifs mimic the immunosuppressive activity of self-DNA, down-regulating the production of proinflammatory and Th1 cytokines. Preclinical studies suggest that "suppressive" ODN may slow or prevent diseases characterized by pathologic immune stimulation, including autoimmunity and septic shock. Extensive studies in animal models suggest that the therapeutic value of CpG and TTAGGG ODN may be optimized by early administration.

Allergen induces the migration of platelets to lung tissue in allergic asthma

RATIONALE

Platelets are essential for pulmonary leukocyte recruitment, airway hyperresponsiveness, and bronchial remodeling in animals with allergic inflammation and can be found in bronchoalveolar lavage of sensitized animals. No studies, however, have explored the direct migration of platelets to lungs.

OBJECTIVES

To assess whether platelets migrate into lung parenchyma in response to inhaled allergen in ovalbumin-sensitized mice; to assess the role of the FcepsilonRI receptor in this phenomenon; and to evaluate whether platelets from patients with asthma, or from sensitized mice, undergo chemotaxis in vitro in response to relevant antigens.

METHODS

Ovalbumin-sensitized wild-type (WT) mice, or FcRgamma(-/-) mice lacking the FcepsilonRIgamma, were challenged with aerosolized allergen and lungs analyzed by platelet-specific immunohistochemistry. In some experiments, mice were depleted of platelets and cross-transfused with either WT or FcRgamma(-/-) platelets to assess the role of platelet FcRgamma(-/-). Chemotaxis of platelets from patients with asthma or from sensitized mice was studied in vitro.

MEASUREMENTS AND MAIN RESULTS

Histology of lungs revealed isolated platelets, migrating out of vessels and localizing underneath the airways after allergen challenge in WT but not in FcRgamma(-/-) mice. Platelets from patients with asthma and from sensitized WT mice, but not from sensitized FcRgamma(-/-) mice, migrated in vitro toward the relevant allergen or an anti-IgE. Platelets from normal mice were found to express FcepsilonRIgamma and platelet-bound IgEs were increased in sensitized mice.

CONCLUSIONS

Platelets migrate extravascularly in response to a sensitizing allergen via a mechanism dependent on the interaction among allergen, allergen-specific IgE, and the FcepsilonRI, and this may allow them to participate directly in allergic tissue inflammation.

Anti-inflammatory effects of Lafoensia pacari and ellagic acid in a murine model of asthma

We have shown that the ethanolic extract of Lafoensia pacari inhibits eosinophilic inflammation induced by Toxocara canis infection, and that ellagic acid is the secondary metabolite responsible for the anti-eosinophilic activity seen in a model of beta-glucan peritonitis. In the present study, we investigated the preventive and curative effects of L. pacari extract and ellagic acid on allergic lung inflammation using a murine model of ovalbumin-induced asthma. In bronchoalveolar lavage fluid, preventive (22-day) treatment with L. pacari (200 mg/kg) and ellagic acid (10 mg/kg) inhibited neutrophil counts (by 75% and 57%) and eosinophil counts (by 78% and 68%). L. pacari reduced IL-4 and IL-13 levels (by 67% and 73%), whereas ellagic acid reduced IL-4, IL-5 and IL-13 (by 67%, 88% and 85%). To investigate curative anti-inflammatory effects, we treated mice daily with ellagic acid (0.1, 1, or 10 mg/kg), also treating selected mice with L. pacari (200 mg/kg) from day 18 to day 22. The highest ellagic acid dose reduced neutrophil and eosinophil numbers (by 59% and 82%), inhibited IL-4, IL-5, and IL-13 (by 62%, 61%, and 49%). Neither L. pacari nor ellagic acid suppressed ovalbumin-induced airway hyperresponsiveness or cysteinyl leukotriene synthesis in lung homogenates. In mice treated with ellagic acid (10 mg/kg) or L. pacari (200 mg/kg) at 10 min after the second ovalbumin challenge, eosinophil numbers were 53% and 69% lower, respectively. Cytokine levels were unaffected by this treatment. L. pacari and ellagic acid are effective eosinophilic inflammation suppressors, suggesting a potential for treating allergies.

Coordinated involvement of mast cells and T cells in allergic mucosal inflammation: critical role of the CC chemokine ligand 1:CCR8 axis

CCL1 is the predominant chemokine secreted from IgE-activated human and mouse mast cells in vitro, colocalizes to mast cells in lung biopsies, and is elevated in asthmatic airways. CCR8, the receptor for CCL1, is expressed by approximately 70% of CD4(+) T lymphocytes recruited to the asthmatic airways, and the number of CCR8-expressing cells is increased 3-fold in the airways of asthmatic subjects compared with normal volunteers. In vivo, CCL1 expression in the lung is reduced in mast cell-deficient mice after aeroallergen provocation. Neutralization of CCL1 or CCR8 deficiency results in reduced mucosal lung inflammation, airway hyperresponsiveness, and mucus hypersecretion to a similar degree as detected in mast cell-deficient mice. Adenoviral delivery of CCL1 to the lungs of mast cell-deficient mice restores airway hyperresponsiveness, lung inflammation, and mucus hypersecretion to the degree observed in wild-type mice. The consequences of CCR8 deficiency, including a marked reduction in Th2 cytokine levels, are comparable with those observed by depletion of CD4(+) T lymphocytes. Thus, mast cell-derived CCL1- and CCR8-expressing CD4(+) effector T lymphocytes play an essential role in orchestrating lung mucosal inflammatory responses.

Signaling through Fc gamma RIII is required for optimal T helper type (Th)2 responses and Th2-mediated airway inflammation

Although inhibitory Fc gamma receptors have been demonstrated to promote mucosal tolerance, the role of activating Fc gamma receptors in modulating T helper type (Th)2-dependent inflammatory responses characteristic of asthma and allergies remains unclear. Here, we demonstrate that signaling via activating Fc gamma receptors in conjunction with Toll-like receptor 4 stimulation modulated cytokine production from bone marrow-derived dendritic cells (DCs) and augmented their ability to promote Th2 responses. Ligation of the low affinity receptor Fc gamma RIII was specifically required for the enhanced Th2 responses, as Fc gamma RIII(-/-) DCs failed to augment Th2-mediated airway inflammation in vivo or induce Th2 differentiation in vitro. Further, Fc gamma RIII(-/-) mice had impaired Th2 cytokine production and exhibited reduced airway inflammation, whereas no defect was found in Fc gamma RI(-/-) mice. The augmentation of Th2 immunity was regulated by interleukin 10 production from the DCs but was distinct and independent of the well-established role of Fc gamma RIII in augmenting antigen presentation. Thus, our studies reveal a novel and specific role for Fc gamma RIII signaling in the regulation of Th cell responses and suggest that in addition to immunoglobulin (Ig)E, antigen-specific IgG also contributes to the pathogenesis of Th2-mediated diseases such as asthma and allergies.

Does anti-IgE therapy help in asthma? Efficacy and controversies

Omalizumab, a humanized monoclonal antibody against IgE, is clinically efficacious when it neutralizes almost all free IgE and reduces IgE receptors on basophils and mast cells. Asthmatic subjects on inhaled corticosteroids who are treated with omalizumab as an add-on therapy experience only modest benefits in symptoms and perhaps in quality of life, but the most significant effects are reductions in airway inflammation and in exacerbation rate. Airway obstruction and hyperresponsiveness do not change significantly. Although the magnitude of the beneficial effects is small, they are observed even in the most severe cases, particularly the reduction in exacerbation rate. The safety profile of omalizumab is very encouraging, although phase IV studies are ongoing to clarify the incidence of neoplasias. Because of its cost, omalizumab therapy may be most cost-effective in patients with severe and refractory asthma, particularly those with frequent exacerbations requiring hospital care. Further clinical studies are now evaluating the best place for omalizumab in the algorithm of asthma management.

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.

Inhibition of mite-induced immunoglobulin E synthesis, airway inflammation, and hyperreactivity by herbal medicine STA-1

The availability of STA-1 in suppressing allergen-induced immunoglobulin E (IgE) synthesis, airway inflammation and hyperreactivity in a murine model was investigated. The mice were intraperitoneally sensitized with Dermatophagoides pteronyssinus group 5 allergen (Der p 5) and orally treated with 300 mg/kg of STA-1 every other day for 14 days. The Der p 5-specific immunologic responses including changes of specific immunoglobulin G and E, cells in the broncholarvage fluid, and airway hyperreactivity were measured when mice received inhalation challenge with Der p 5 after sensitization for 21 days. By comparing with sham-treated groups, the synthesis of Der p 5-specific IgE was downregulated while the influx of eosinophils and neutrophils in the airway were remarkably reduced. In addition, Der p 5-induced airway hyperreactivity also was significantly eliminated by STA-1 treatment. These results showed that STA-1 could effectively suppress the Der p 5-induced allergic reactions, and the availability of STA-1 for the treatment of allergic asthma was demonstrated in this study.

Identification of polymorphisms in human interleukin-27 and their association with asthma in a Korean population

Interleukin 27 (IL-27) acts as a versatile cytokine in the early regulation of Th1 initiation and in the negative regulation of the Th2 factor GATA-3. IL-27, which was discovered as a novel heterodimeric cytokine of the IL-12 family, consists of two subunits, the Epstein-Barr virus-induced gene 3 (EBI3) and p28. The IL-27 cytokine is mediated by one of the receptor chains (WSX-1) of the IL-27 receptor that is highly expressed on CD4(+) T lymphocytes and NK cells. Although signaling of IL-27/WSX-1 interactions have been recognized in the down-regulation of airway hyper-reactivity and in lung inflammation during the development of allergic asthma, little is known about the role of single nucleotide polymorphisms (SNPs) of IL-27 and individual susceptibility to asthma. To address this question, we have examined the five exons and the boundary intron sequences of IL-27P28, including the promoter regions, with the aim of identifying sites of variation that may be useful for understanding the genetic influences of this gene. We identified four SNPs, g.-964A > G, g.2905T > G, g.4603G > A and g.4730T > C, and analyzed the genotype and allele frequencies between asthma patients and healthy controls. Our results strongly suggest that the g.-964A > G polymorphism of IL-27p28 is most likely associated with susceptibility to asthma. Moreover, we elucidate the haplotype frequencies of g.2905T > G, g.4603G > A and g.4730T > C in terms of their relative correlation with asthma patients and healthy controls.

Interleukin-16 Inhibits Immunoglobulin E Production by B Lymphocytes

BACKGROUND

The increased production of IgE is a hallmark of atopic disorders. CD4+ T cells regulate the production of Immunoglobulin (Ig) E by B cells. Interleukin (IL) 16, a CD4+ specific cytokine, is highly expressed at sites of allergic inflammation. Our aim was to determine the effect of IL-16 on IgE production in atopic subjects.

METHODS

Freshly isolated peripheral blood mononuclear cells (PBMC) from atopic subjects were stimulated with recombinant IL (rIL) 4 and anti-CD40 antibody to promote IgE production in the presence or absence of rIL-16 added at different time intervals prior to stimulation. The levels of IgE in cell culture supernatants collected at day 14 were measured by ELISA. The effect of IL-16 on the expression of the Cepsilon transcript was evaluated by reverse-transcription polymerase chain reaction. To evaluate whether the modulatory effect of IL-16 on IgE production was mediated by interferon-gamma (IFN-gamma), anti-CD40/IL-4-stimulated PBMC were cultured in the presence of rIL-16 and neutralizing concentrations of anti-IFN-gamma antibody.

RESULTS

PBMC stimulated with rIL-4 (400 U/ml) and anti-CD40 monoclonal antibody (0.5 microg/ml) produced significant amounts of IgE (range: 1.3-46.0 ng/ml). The addition of rIL-16 twenty-four hours before stimulation significantly reduced the levels of IgE released by anti-CD40/IL-4-stimulated PBMC (0.5-29.6 ng/ml, p < 0.05). IL-16 reduced the expression of the Cepsilon transcript in stimulated PBMC. IL-16 induced the expression of IFN-gamma mRNA. However, the use of anti-IFN-gamma antibody did not alter the effect of IL-16 on IgE production. Rescue doses of IL-13 did not restore the production of IgE by PBMC treated with IL-16. IL-16 did not alter IgE production in CD14-depleted cell preparations suggesting that the IL-16-mediated effects on IgE production may be related to CD14+ cells.

CONCLUSION

These data show that IL-16 inhibits IgE production and therefore may play an important regulatory role in atopic disorders.

Omalizumab is effective and safe in the treatment of Japanese cedar pollen-induced seasonal allergic rhinitis

BACKGROUND

Seasonal allergic rhinitis (SAR) induced by Japanese cedar pollen is a substantial problem in Japan. Omalizumab, a novel humanized monoclonal anti-immunoglobulin E (IgE) antibody, has already been proven to reduce symptoms associated with SAR. We investigated the safety and efficacy of omalizumab in the treatment of patients with Japanese cedar pollen-induced SAR compared to placebo.

METHODS

A randomized, placebo-controlled, double-blind study was conducted in 100 Japanese patients with a history of moderate-to-severe SAR induced by Japanese cedar pollens. Omalizumab (150, 225, 300, or 375mg) or placebo was administered subcutaneously every 2 or 4 weeks based on serum total IgE and body weight at baseline. The primary efficacy variable was the mean of daily nasal symptom medication scores (sum of the daily nasal symptom severity score and daily nasal rescue medication score) during the treatment period. Secondary efficacy variables included the daily ocular symptom medication score and related variables.

RESULTS

Primary and all secondary efficacy variable scores were significantly lower in the omalizumab group than in the placebo group (P < .01). Serum free IgE levels markedly decreased in the omalizumab group and were associated with clinical efficacy. The overall incidence of injection site reactions was higher in the omalizumab group than in the placebo group; however, the adverse reaction profile was similar between the two groups when excluding injection site reactions. No anti-omalizumab antibodies were detected.

CONCLUSIONS

Omalizumab was effective and safe in the treatment of SAR induced by Japanese cedar pollen.

The level of IgE produced by a B cell is regulated by norepinephrine in a p38 MAPK- and CD23-dependent manner

Although the causes of asthma vary, the severity of the disease correlates with the level of IgE produced. In this study we show that mice produced less IgE when they were depleted of the neurotransmitter norepinephrine (NE) before the administration of Ag. The suppression was prevented when a beta2-adrenergic receptor (beta2AR)-selective agonist was administered, suggesting that NE stimulated the beta2AR to regulate the level of an IgE response in vivo. Although the cell targeted by NE to produce this effect in vivo is unknown, we show in vitro that the level of IgE increased on a per cell basis without an effect on class switch recombination when NE stimulated the beta2AR on a B cell directly. The beta2AR-induced increase in IgE depended on p38 MAPK but not protein kinase A activation, was due to an increased rate of mature IgE mRNA transcription, and was lost when beta2AR-deficient B cells were used. Also, CD23 transcription was increased in a p38 MAPK-dependent manner and resulted in an increased level of soluble CD23 (sCD23). The beta2AR-induced increase in sCD23 was associated with IgE up-regulation and possibly interacted with CD21/CD19. Using B cells from respective knockout mice, data showed that the beta2AR-induced increase in IgE depended on B cell expression of CD23, CD21, and CD19. These findings suggest that at least one mechanism by which endogenous B cell activity in vivo is regulated by NE involves stimulation of the beta2AR on the B cell alone to increase the level of IgE produced in a p38 MAPK- and sCD23-dependent manner.

IgE-mediated allergen presentation and blocking antibodies: regulation of T-cell activation in allergy

It is well established that both the production of IgE by B lymphocytes and the maturation and recruitment of eosinophils in late-phase reactions are dependent on the activation of allergen-specific type-2 T-helper cells. What is less well known is the fact that efficient activation of allergen-specific T cells upon low-dose exposure to allergens is critically dependent on IgE-mediated or -facilitated allergen presentation. In fact, changes in the level of IgE-mediated allergen presentation may account for many of the immunological effects described for specific immunotherapy or anti-IgE treatment. This review aims to summarize the current knowledge, and will discuss the clinical relevance of blocking IgG antibodies induced by specific immunotherapy and anti-IgE monoclonal antibodies that both interfere with IgE-mediated allergen presentation.

Inhibition of Th2-Mediated Allergic Airway Inflammatory Disease by CD137 Costimulation

The engagement of CD137 (4-1BB), an inducible T cell costimulatory receptor and member of the TNF receptor superfamily, by agonistic Abs can promote strong tumor and viral immunity mediated by CD8(+) T cells and stimulate IFN-gamma production. However, its role in Th2-mediated immune responses has not been well defined. To address this issue, we studied the function of CD137 engagement using an allergic airway disease model in which the mice were sensitized with inactivated Schistosoma mansoni eggs followed by S. mansoni egg Ag challenge directly in the airways and Th1/2 cytokine production was monitored. Interestingly, treatment of C57BL/6 mice with agonistic anti-CD137 (2A) during sensitization completely prevents allergic airway inflammation, as shown by a clear inhibition of T cell and eosinophil infiltration into the lung tissue and airways, accompanied by diminished Th2 cytokine production and reduced serum IgE levels, as well as a reduction of airway hyperresponsiveness. At various time points after immunization, restimulated splenocytes from 2A-treated mice displayed reduced proliferation and Th2 cytokine production. In accordance with this, agonistic Ab to CD137 can directly coinhibit Th2 responses in vitro although it costimulates Th1 responses. CD137-mediated suppression of Th2 response is independent of IFN-gamma and T regulatory cells. Our study has identified a novel pathway to inhibit Th2 responses in a CD137-dependent fashion.

Targets in allergy-directed immunotherapy

Allergic diseases such as asthma, atopic dermatitis, rhinitis and urticaria are immunological disorders affecting almost one third of the population in industrialised countries. Therapeutic or prophylactic approaches to turn around the increasing prevalence of these diseases have been intensively investigated. Allergen-specific immunotherapy has been applied in clinical practice for many decades, although varying results and occasional severe side effects have called for more effective and safer vaccines. Recent advances in our knowledge of immunological mechanisms have created several options to comply with these demands. This article will focus on some of the most promising new developments.

Regulation of stromal cell-derived factor-1 and exhaled nitric oxide in asthmatic children following montelukast and ketotifen treatment

BACKGROUND

Montelukast and ketotifen are oral anti-allergy medications in asthmatic children. This study investigates the modulation effect of montelukast and ketotifen on children with intermittent to mild persistent asthma as demonstrated by the levels of peak expiratory flow (PEF), asthma scores (AS), exhaled nitric oxide (eNO) and plasma stromal cell-derived factor-1 (SDF-1) concentration in a randomized, prospective study.

METHODS

Fifty asthmatic children were enrolled and received 8 weeks of treatment with oral montelukast sodium 5mg chewable tablet administered once daily, or 1mg ketotifen, and were followed for a 4-week post-treatment washout period. ENO concentration, AS and PEF were measured before, 2, 4, 6 and 8 weeks after initial treatment, and 4 weeks after cessation of treatment.

RESULTS

Montelukast therapy was showed to improve AS, PEF and eNO within 2 weeks and remained the improvement during the treatment period. Montelukast also significantly decreased plasma SDF-1 levels after 8 weeks of treatment. In contrast, the ketotifen treatment revealed no significant effects in these clinical parameters until 4 and 6 weeks of the therapy, and did not suppress plasma SDF-1 levels after 8 weeks of treatment. To prove whether montelukast directly suppressed SDF-1 induction, we studied effects of montelukast on the LPS-induced SDF-1 expression and SDF-1-induced chemotaxis of monocytic (THP-1) cells. Montelukast, but not ketotifen, could suppress SDF-1 expression and its related chemotaxis on THP-1 monocytic cells.

CONCLUSIONS

Leukotriene receptor antagonist, such as montelukast, may be a better non-steroid anti-inflammatory drug for mild childhood asthma in preventing airway inflammation.

Fas-positive T cells regulate the resolution of airway inflammation in a murine model of asthma

Persistent airway inflammation, mucus production, and airway hyperreactivity are the major contributors to the frequency and severity of asthma. Why lung inflammation persists in asthmatics remains unclear. It has been proposed that Fas-mediated apoptosis of inflammatory cells is a fundamental mechanism involved in the resolution of eosinophilic airway inflammation. Because infiltrating eosinophils are highly sensitive to Fas-mediated apoptosis, it has been presumed that direct ligation of Fas on eosinophils is involved. Here, we utilize adoptive transfers of T cells to demonstrate that the delayed resolution of eosinophilia in Fas-deficient mice is a downstream effect of Fas deficiency on T cells, not eosinophils. Interestingly, the mice that received Fas-deficient T cells, but not the controls, developed a persistent phase of inflammation that failed to resolve even 6 wk after the last challenge. This persistent phase correlated with decreased interferon (IFN)γ production by Fas-deficient T cells and could be reproduced with adoptive transfer of IFNγ-deficient T cells. These data demonstrate that Fas deficiency on T cells is sufficient for the development of long-term allergic airway disease in mice and implies that deregulation of death receptors such as Fas on human T cells could be an important factor in the development and/or chronic nature of asthma.

Oral and nasal sensitization promote distinct immune responses and lung reactivity in a mouse model of peanut allergy

Despite structural and functional differences between the initial sites of contact with allergens in the gastrointestinal and nasal tracts, few animal models have examined the influence of the mucosal routes of sensitization on host reactivity to food or environmental antigens. We compared the oral and nasal routes of peanut sensitization for the development of a mouse model of allergy. Mice were sensitized by administration of peanut proteins in the presence of cholera toxin as adjuvant. Antibody and cytokine responses were characterized, as well as airway reactivity to nasal challenge with peanut or unrelated antigens. Oral sensitization promoted higher levels of IgE, but lower IgG responses, than nasal sensitization. Both orally and nasally sensitized mice experienced airway hyperreactivity on nasal peanut challenge. The peanut challenge also induced lung eosinophilia and type 2 helper T-cell-type cytokines in orally sensitized mice. In contrast, peanut challenge in nasally sensitized mice promoted neutrophilia and higher levels of lung MAC-1(+) I-A(b low) cells and inflammatory cytokines. In addition, nasal but not oral, sensitization promoted lung inflammatory responses to unrelated antigens. In summary, both oral and nasal peanut sensitization prime mice for airway hyperreactivity, but the initial mucosal route of sensitization influences the nature of lung inflammatory responses to peanut and unrelated allergens.

The encapsulation of enterotoxigenic Escherichia coli colonization factor CS3 in biodegradable microspheres enhances the murine antibody response following intranasal administration

The aim of this study was to measure serum and mucosal antibody responses following intranasal administration of biodegradable poly(dl-lactide-co-glycolide) (PLGA) microspheres loaded with the CS3 colonization factor isolated from enterotoxigenic Escherichia coli (ETEC). The response was compared against that measured in mice similarly administered the native CS3 antigen and in mice co-administered, along with the CS3 antigen, a known mucosal adjuvant, the R192G mutant heat-labile enterotoxin (mLT). The integrity of the CS3 antigen released from the microspheres was maintained as determined by SDS-PAGE and immunoblotting. Native CS3 induced serum and mucosal (bronchoalveolar, small intestinal and faecal) IgG and IgA responses. The co-administration of the mLT mucosal adjuvant significantly enhanced (P<0·001) serum and mucosal antibody responses to the CS3 protein. Likewise, the CS3-loaded PLGA microspheres induced significantly greater (P<0·001) serum and mucosal antibody responses than native CS3, as well as inducing antibody responses superior to those of the CS3 plus mLT formulation. Following administration of CS3 plus mLT, the mice became distressed (loss of activity, increased huddling, ruffled fur), a situation not seen following administration of the CS3-loaded PLGA microspheres. The results in this trial show that the CS3-loaded PLGA microspheres when administered intranasally to mice caused no observable distress to the mice and significantly (P<0·001) enhanced the immunogenicity of the CS3 protein.

Involvement of GATA-3-dependent Th2 lymphocyte activation in airway hyperresponsiveness

The pathophysiological characteristics of bronchial asthma consist of chronic inflammation of airways, airway hyperresponsiveness, and bronchoconstriction. Studies have shown that T helper type 2 (Th2) cytokines produced by both T cells and mast cells in the airway contribute substantially to the initiation of inflammation in both experimental and human bronchial asthma. GATA-3 is a transcription factor essential to the production of Th2 cytokines by T lymphocytes. To clarify the role of GATA-3-expressing T cells in the pathophysiology of bronchial asthma, we utilized transgenic (Tg) mice carrying the GATA-3 gene and the ovalbumin (OVA)-specific T cell receptor gene (GATA-3-Tg/OVA-Tg). Mice were intranasally administrated OVA without systemic immunization. Airway responses were analyzed with noninvasive and invasive whole body plethysmographs. GATA-3-Tg/OVA-Tg mice exhibited significantly higher IL-13 and IL-4 protein expression in the airway. Although there were no differences in the types of infiltrating cells between GATA-3-Tg/OVA-Tg and GATA-3-non-Tg/OVA-Tg mice and no significant increase in IgE level in either group compared with nontreated mice, the response after ACh inhalation was significantly elevated in GATA-3-Tg/OVA-Tg on the seventh day of intranasal treatment with OVA. This hyperresponsiveness was inhibited by 5-lipoxygenase inhibitor and IL-13 neutralization, suggesting that airway responses were induced through IL-13 and leukotriene pathway. In conclusion, airway hyperresponsiveness, a characteristic of bronchial asthma, is regulated at the level of GATA-3 transcription by T lymphocytes in vivo.

Altered allergic cytokine and antibody response in mice treated with Bisphenol A

The objective of this study was to elucidate if Bisphenol A (BPA) administration modulates T helper (Th) cell component of immune responses in a mouse challenged with ovalbumin (OVA), a major food antigen. BALB/c mice, (6 weeks old, female) were orally given either OVA (OVA-fed) or water (Water-fed), immunized intraperitoneally with OVA and injected with either BPA in corn oil or the vehicle alone. After subsequent 2nd immunization, serum titers of total IgE, OVA-specific IgE, IgG, IgG1 IgG2a and ability of their splenocytes for production of interferon (IFN) -gamma, interleukin (IL) -4 and IL-12 were examined by ELISA. Lymphocyte proliferation assay against concanavalin A (Con A) or OVA was also performed for 3H-Thymidine incorporation. In Water-fed groups, treatment with BPA resulted in lower titers of total IgE (P<0.01) and higher levels IgG2a (P<0.05) followed by a higher IFN-gamma (P<0.05) and IL-12 (P<0.05) with an intact IL-4. When OVA-fed groups were examined, the compound did not change production of total and OVA-specific IgE and -IgG2a but resulted in lower production of IFN-gamma (P<0.05). Also, BPA resulted in impaired lymphocyte proliferation to Con A in Water-fed groups (P<0.05) but not in tolerated animals. The findings indicate that BPA results in augmentation of Th1 immune responses but no significant effect on an established tolerance to OVA.

Prevention of allergy by a recombinant multi-allergen vaccine with reduced IgE binding and preserved T cell epitopes

Novel approaches for the prevention of allergy are required, because of the inevitably increasing prevalence of allergic diseases during the last 30 years. Here, a recombinant chimeric protein, which comprises the whole amino acid sequences of three bee venom major allergens has been engineered and used in prevention of bee venom sensitization in mice. Phospholipase A2 (Api m 1), hyaluronidase (Api m 2) and melittin (Api m 3) fragments with overlapping amino acids were assembled in a different order in the Api m (1/2/3) chimeric protein, which preserved entire T cell epitopes, whereas B cell epitopes of all three allergens were abrogated. Accordingly, IgE cross-linking leading to mast cell and basophil mediator release was profoundly reduced in humans. Supporting these findings, the Api m (1/2/3) induced 100 to 1000 times less type-1 skin test reactivity in allergic patients. Treatment of mice with Api m (1/2/3) led to a significant reduction of specific IgE development towards native allergen, representing a protective vaccine effect in vivo. These results demonstrate a novel prototype of a preventive allergy vaccine, which preserves the entire T cell epitope repertoire, but bypasses induction of IgE against native allergen, and side effects related to mast cell/basophil IgE FcepsilonRI cross-linking in sensitized individuals.

How antibodies act as natural adjuvants

Antibodies can act like adjuvants. They can potently enhance the antibody response, and in the case of IgG and IgE also the T cell response, to the very antigen they are specific for. In this review we will discuss the recent advances made in our understanding of the underlying mechanisms of antibody-mediated feedback enhancement. The immuno-stimulatory properties of IgM, IgG1, IgG2a, IgG2b, IgG3 and IgE will be reviewed in relationship to the complement system and Fc receptors and the physiological relevance will be discussed.

Mast cells and IgE-bearing cells in lungs of RAO-affected horses

Recurrent airway obstruction (RAO) is a common condition in stabled horses characterised by small airway inflammation and obstruction following exposure of susceptible horses to mouldy hay and straw. The aim of the present study was to investigate whether lung tissue from horses with RAO contains higher numbers of IgE-protein positive (+) cells and mast cells compared to controls after mouldy hay challenge. Furthermore, mast cell subtypes in lung tissue were investigated. IgE+ cells were detected in most lung tissue samples but no significant differences between RAO-affected and control horses were found. In the wall of the bronchi and bronchioli of both RAO-affected and control horses, mainly chymase+ mast cells (MC(C)) were present (85% in the bronchial wall and 77% in the wall of the bronchioli), while 73% of the mast cells (MC) around blood vessels were tryptase+ mast cells (MC(T)). No double stained MCs were detected. RAO-affected horses had significantly more MC(C) than controls in the wall of the bronchi (median=7.6 and 1.7 cell/mm(2), respectively, P< or =0.05). They also showed a tendency for more MC(C) in the wall of the bronchioli than controls (median=21 and 2.9 cells/mm(2), respectively, P=0.07) but there were no differences in MC(T) numbers. The data suggest an involvement of MC(C) in the pathogenesis of RAO. Independently of the clinical diagnosis, there was a significant relationship between high MC(C) numbers in the bronchial wall and lung fibrosis, suggesting that these MC(C) may be involved in tissue remodelling. Furthermore, high MC(C) numbers were also associated with increased infiltration with lymphocytes and neutrophils.

Nicotine: therapeutic potential for the treatment of ulcerative colitis

Ulcerative colitis (UC) is predominantly a disease of non-smokers, and nicotine may be the agent responsible for this association. Transdermal nicotine has been shown to improve disease activity and sigmoidoscopic appearance in the active disease but in one study had no effect on maintenance of remission. Since side-effects with nicotine patches occur in up to two thirds of patients, attempts to reduce systemic levels and improve drug tolerance have been developed with colonic delivery systems of nicotine. Preliminary observations with nicotine enemas in UC have shown clinical benefit, but controlled trials are needed. Mechanisms responsible for the association of smoking with colitis and for the therapeutic effect of nicotine remain an enigma; possibilities include: modulation of the immune response, alterations of colonic mucus and eicosanoid production, changes in rectal blood flow, decreased intestinal permeability and the release of endogenous glucocorticoids. With current treatment for UC limited to corticosteroids and formulations of 5-aminosalicylic acid, alternative treatments are required and nicotine may fulfil this role.

Cytokine networks in allergic lung inflammation: an opportunity for drug intervention

Eosinophils and mast cells have long been considered as the major effector cells ultimately responsible for bronchial obstruction and airway hyper-responsiveness in asthmatics. However, there is now accumulating evidence that products of Th2 lymphocytes may orchestrate the generation, accumulation, and activation of these cells within the airway wall. Since the first report by Mosmannet al. in 1986 that murine helper T-cell clones could be divided into two subsets, Th1 and Th2, depending on their pattern of cytokine secretion, and observations that polarisation of Th1- or Th2-dependent cytokine production could be correlated with distinct autoimmune and allergic disorders, there has been an increasing interest in the possibility that pharmacological manipulation of the Th1/Th2 paradigm could provide novel treatments for human disease. This review summarises the evidence to date, attempts to explain some apparent discrepancies, and indicates opportunities for therapeutic intervention.

Ca2+ influx-mediated histamine synthesis and IL-6 release in mast cells activated by monomeric IgE

We previously demonstrated that histamine synthesis is drastically induced upon sensitization with an anti-DNP IgE clone, SPE-7, in IL-3-dependent mouse bone marrow derived mast cells (BMMC). We found that Ca2+ mobilization induced by SPE-7 exhibited a similar profile to the capacitative Ca2+ entry evoked by thapsigargin. Potentials for activation of mast cells were found to vary between different IgE clones, and a monovalent hapten, DNP-lysine, suppressed the activation induced by SPE-7. Ca2+ mobilization induced by SPE-7 was suppressed potently by the specific store-operated Ca2+ channel inhibitor, SK&F 96365, but not at all by Ca2+ channel inhibitors with more broad spectrum, La3+ and Gd3+, whereas the Ca2+ mobilization induced by Ag stimulation was suppressed by these inhibitors. Ca2+ mobilization was also induced by SPE-7 in in vitro differentiated mast cells, although the increases in histamine synthesis and IL-6 release were smaller than those in BMMC. These results suggest that Ca2+ influx operated by a distinct mechanism from that in Ag stimulation is essential for increased histamine synthesis and IL-6 release in mast cells.

A major allergen gene-fusion protein for potential usage in allergen-specific immunotherapy

BACKGROUND

Specific immunotherapy is a common treatment of allergic diseases and could potentially be applied to other immunologic disorders. Despite its use in clinical practice, more defined and safer allergy vaccine preparations are required. Differences between epitopes of IgE that recognize the 3-dimensional structure of allergens and T cells that recognize linear amino acid sequences provide a suitable tool for novel vaccine development for specific immunotherapy.

OBJECTIVE

The aim of the study was to delete B-cell epitopes and prevent IgE crosslinking, but to preserve T-cell epitopes by fusion of 2 major allergens of bee venom because of a change in the conformation.

METHODS

By genetic engineering, we produced a fusion protein composed of the 2 major bee venom allergens: phospholipase A 2 (Api m 1) and hyaluronidase (Api m 2).

RESULTS

The Api m [1/2] fusion protein induced T-cell proliferation and both T H 1-type and T H 2-type cytokine responses. In contrast, IgE reactivity was abolished, and profoundly reduced basophil degranulation and type 1 skin test reactivity was observed. Pretreatment of mice with Api m [1/2] fusion protein significantly suppressed the development of specific IgE as well as other antibody isotypes after immunization with the native allergen.

CONCLUSION

The novel fusion protein of 2 major allergens bypasses IgE binding and mast cell/basophil IgE FcepsilonRI crosslinking and protects from IgE development.

Long-term exacerbation by interleukin 13 of IgE-mediated eosinophilia in rats

Recent work shows that at least two cycles of antigen challenge applied in a 7-day interval are required to yield tissue eosinophil accumulation in IgE-passively sensitized rats. Since interleukin (IL)-13 is widely regarded as a key mediator in eosinophilic responses associated with mast cells and IgE, we investigated whether this cytokine could replace the first cycle of sensitization and challenge in its proeosinophilic role. We found that IL-13 (25 and 50 ng/cavity) injected into the rat pleural space led to eotaxin generation and a dose-dependent accumulation of eosinophils following IgE-passive sensitization and challenge 7 days later. IL-13 failed to cause eosinophil chemotaxis in vitro but induced eosinophil accumulation into the pleural cavity of naïve rats, which peaked 1 day and faded 72 h post-challenge. No changes were found 1 week after intrapleural injection of IL-13, except an approximately 40-50% increase in the number of adhered and non-adhered pleural mast cells. As recovered from the pleural effluent 1 week after IL-13, mast cells expressed the same amount of IgE bound on their surface as compared to controls. However, they generated 3-fold more LTC(4) following IgE-sensitization and challenge in vitro, keeping intact the amount of histamine released. Finally, pretreatment with zileuton (50 microg/cavity) 1 h before allergen challenge prevented eosinophil accumulation in those animals injected with IL-13 1 week before. In conclusion, our findings show that IL-13 causes a long-term exacerbation of the IgE-mediated eosinophilic response in a mechanism associated with heightened cysteinyl-leukotriene (cys-LT) production by resident mast cells.

Anti-IgE therapy in allergic disease

PURPOSE OF REVIEW

Recombinant monoclonal humanized anti-IgE has put forward a fundamentally new concept for the control of allergic disorders. This review will present recent data from clinical studies with anti-IgE in asthma, allergic rhinitis, and food allergy and will examine the place of anti-IgE among current therapeutic options for the treatment of asthma.

RECENT FINDINGS

Therapy with anti-IgE depresses circulating free IgE to the limits of detection, inhibits early- and late-phase responses to allergens, suppresses inflammation and improves the control of allergic diseases. In moderate to severe asthma it results in fewer exacerbations and a lower requirement for both corticosteroids and beta-agonists. IgE appears to be an important regulator of high-affinity Fc receptors (FcepsilonRI) and, in the mouse, to enhance mast cell survival and activation. IgE receptors have been found on diverse inflammatory cells. Anti-IgE reduces the expression of FcepsilonRI on inflammatory cells. Current work has documented a marked decrease in tissue eosinophils, lymphocytes, and interleukin-4-positive cells by anti-IgE treatment and has provided insight into the mechanisms underlying improved control of asthma.

SUMMARY

Clinical studies with anti-IgE have promoted and will continue to advance the understanding of IgE-mediated disease mechanisms. They have documented its efficacy in the treatment of allergic diseases, but much remains to be learned about the most effective clinical strategies and the selection of patients for therapy.

Vitamin D receptor-deficient mice fail to develop experimental allergic asthma

The active metabolite of vitamin D (1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3))) is known to modulate the immune response in Th1 cell-directed diseases. To investigate the role of vitamin D in Th2 cell-directed diseases, experimental allergic asthma was induced in vitamin D receptor (VDR) knockout and in wild-type (WT) mice. As expected, WT mice developed symptoms of airway inflammation with an influx of eosinophils, elevated Th2 cytokine levels, mucous production, and airway hyperresponsiveness. The administration of 1,25(OH)(2)D(3) had no effect on asthma severity. The only discernable effect of 1,25(OH)(2)D(3) on experimental allergic asthma in WT mice was an increased expression of two Th2-related genes (soluble CD23 and GATA-3) in lungs of BALB/c mice exposed to Ag through the nasal route only. By contrast, asthma-induced VDR knockout mice failed to develop airway inflammation, eosinophilia, or airway hyperresponsiveness, despite high IgE concentrations and elevated Th2 cytokines. The data suggest that although 1,25(OH)(2)D(3) induced these Th2-type genes, the treatment failed to have any affect on experimental asthma severity. However, VDR-deficient mice failed to develop experimental allergic asthma, suggesting an important role for the vitamin D endocrine system in the generation of Th2-driven inflammation in the lung.

DNA, the immune system, and atopic disease

The prevalence and severity of atopic diseases (atopic dermatitis, asthma, and allergic rhinitis) have increased over recent decades, particularly in industrialized nations. Atopic dermatitis, like asthma, is more common in older siblings and in less crowded houses and with late entry to day care, increased maternal education, and higher socio-economic status. The inverse relationship between the incidence of atopy and childhood infections has led to the "hygiene hypothesis," which suggests that diminished exposure to childhood infections in modern society has led to decreased TH1-type responses. Reduced TH1 may lead to enhanced TH2-type inflammation, which is important in promoting asthma and allergic disease. Corticosteroids, commonly used to treat these conditions, inhibit the function of inflammatory cells, but they are ineffective in altering the initial TH2-type response to allergens in a sensitized individual. Treatment with TH1 cytokines not only has failed to make any significant impact on the outcome of these diseases, but it also has caused significant adverse reactions. A novel therapeutic approach, recently reported in the preclinical setting, is the use of oligodeoxynucleotides, which contain unmethylated motifs centered on CG dinucleotides. These CpG oligodeoxynucleotides potently induce TH1 cytokines and suppress TH2 cytokines, and can prevent manifestations of asthma and other allergic diseases in animal models. They have the potential to reverse TH2-type responses to allergens and thus restore balance to the immune system without the adverse effects of TH1 cytokines.

Analysis of the polymorphisms in eotaxin gene family and their association with asthma, IgE, and eosinophil

The eotaxin gene family (eotaxin, eotaxin-2, and eotaxin-3) has been implicated in the recruitment of eosinophils, basophiles, and Th2 lymphocytes that is a central aspect of allergic diseases such as asthma. To determine whether the single nucleotide polymorphisms (SNPs) of eotaxin gene family are associated with susceptibility to asthma, we scanned 225 asthma patients and 294 non-asthmatic controls using the direct sequencing method. We further investigated the relationships among each SNP, eosinophils, and serum total IgE levels in asthma patients. Eleven SNPs were identified in the eotaxin gene family. We found that EoB179T > C (P = 0.0001), EoB275C > T (P = 0.018) of the eotaxin-2 and EoA2497T > G (P = 0.003) of the eotaxin-3 were significantly associated with the susceptibility of asthma. Furthermore, our data demonstrated for the first time that EoA2497T > G (P = 0.005) is related to serum total IgE level while EoA77C > T (P = 0.035) and EoA2497T > G (P = 0.033) are related to the peripheral blood eosinophil counts in asthma. Our results suggest that the polymorphisms of the eotaxin gene family are associated with the susceptibility of asthma and Eotaxin-3 might play the critical role for the recruitment of eosinophils and the maintenance of IgE levels.

Negative regulation of immunoglobulin E-dependent allergic responses by Lyn kinase

A role for Lyn kinase as a positive regulator of immunoglobulin (Ig)E-dependent allergy has long been accepted. Contrary to this belief, Lyn kinase was found to have an important role as a negative regulator of the allergic response. This became apparent from the hyperresponsive degranulation of lyn-/- bone marrow-derived mast cells, which is driven by hyperactivation of Fyn kinase that occurs, in part, through the loss of negative regulation by COOH-terminal Src kinase (Csk) and the adaptor, Csk-binding protein. This phenotype is recapitulated in vivo as young lyn-/- mice showed an enhanced anaphylactic response. In vivo studies also demonstrated that as lyn-/- mice aged, their serum IgE increased as well as occupancy of the high affinity IgE receptor (FcepsilonRI). This was mirrored by increased circulating histamine, increased mast cell numbers, increased cell surface expression of the high affinity IgE receptor (FcepsilonRI), and eosinophilia. The increased IgE production was not a consequence of increased Fyn kinase activity in lyn-/- mice because both lyn-/- and lyn-/- fyn-/- mice showed high IgE levels. Thus, lyn-/- mice and mast cells thereof show multiple allergy-associated traits, causing reconsideration of the possible efficacy in therapeutic targeting of Lyn in allergic disease.

Effects of treatment with anti-immunoglobulin E antibody omalizumab on airway inflammation in allergic asthma

IgE plays an important role in allergic asthma. We hypothesized that reducing IgE in the airway mucosa would reduce airway inflammation. Forty-five patients with mild to moderate persistent asthma with sputum eosinophilia of 2% or more were treated with humanized monoclonal antibody against IgE (omalizumab) (n = 22) or placebo (n = 23) for 16 weeks. Outcomes included inflammatory cells in induced sputum and bronchial biopsies, and methacholine responsiveness. Treatment with omalizumab resulted in marked reduction of serum IgE and a reduction of IgE+ cells in the airway mucosa. The mean percentage sputum eosinophil count decreased significantly (p < 0.001) from 6.6 to 1.7% in the omalizumab group, a reduction significantly (p = 0.05) greater than with placebo (8.5 to 7.0%). This was associated with a significant reduction in tissue eosinophils; cells positive for the high-affinity Fc receptor for IgE; CD3+, CD4+, and CD8+ T lymphocytes; B lymphocytes; and cells staining for interleukin-4, but not with improvement in airway hyperresponsiveness to methacholine. This study shows antiinflammatory effects of omalizumab treatment and provides clues for mechanisms whereby omalizumab reduces asthma exacerbations and other asthma outcomes in more severe asthma. The lack of effect of omalizumab on methacholine responsiveness suggests that IgE or eosinophils may not be causally linked to airway hyperresponsiveness to methacholine in mild to moderate asthma.

Increased airway responsiveness, allergy-type-I skin responses and systemic anaphylaxis in a humanized-severe combined immuno-deficiency mouse model

BACKGROUND

In patients with allergic bronchial asthma, a strong relationship between elevated serum IgE antibody titres and the development of increased airway responsiveness (AR) has been demonstrated. To further elucidate the relationship between human (hu) IgE and development of increased AR, we developed an in vivo model utilizing immuno-compromised severe combined immuno-deficiency (SCID) mice.

METHODS

SCID mice were either reconstituted with peripheral blood mononuclear cells (PBMC) from non-atopic, healthy or atopic individuals sensitized against house dust mite allergen (Der p), or passively sensitized with plasma from non-atopic, healthy or atopic individuals.

RESULTS

In both systems, atopic hu-SCID mice developed increased AR. The following results suggest that these responses were mediated via IgE antibodies: increased AR did not occur after transfer of either PBMC or IgE-negative plasma from non-atopic individuals; increased AR occurred simultaneous with increased serotonin release detected 15 min after allergen-aerosol challenge in bronchoalveolar lavage fluid; and increased AR required at least two allergen-aerosol challenges. SCID mice reconstituted with serum containing anti-Der p IgE antibodies developed positive immediate-type skin test responses to intradermal injection of Der p as well as anti-hu-IgE antibody. In addition, IgE binding to skin mast cells was demonstrated by immunohistochemistry. Furthermore, intravenous challenge of hu anti-Der p positive SCID mice with Der p resulted in systemic anaphylaxis.

CONCLUSION

These data provide evidence that passive immunization of SCID mice with hu IgE alters AR and that T cells and eosinophils were not a requirement for the development of increased AR in this model.

Gender comparison in a murine model of allergen-driven airway inflammation and the response to budesonide treatment

Background

Evidence suggests that gender differences exist in the severity of many immunological diseases and their response to glucocorticosteroid treatment. In this report, we have used a murine model of ovalbumin-induced lung inflammation to address whether gender could affect the systemic response, airway inflammation and hyperreactivity and their responses to budesonide.

Results

Following an acute ovalbumin challenge, actively sensitised BALB/c mice developed a time-dependent increase in interleukin-4 and interleukin-5 production and inflammatory cell influx into bronchoalveolar lavage fluid. Apart from an increased number of lymphocytes in female mice at day 3 post-challenge, none of the above parameters were affected by gender. Blood leukocyte numbers were also unaffected, whereas a two-fold increase in total serum immunoglobulin E was observed in female mice. Budesonide, given intranasally, did not affect the blood parameters, but dose-dependently inhibited the pulmonary inflammation and airway hyperreactivity in both male and female mice. Female mice were slightly less sensitive to budesonide's inhibitory action on interleukin-5 production and the development of airway hyperreactivity.

Conclusions

Our results suggest that, apart from a 2-fold increase in serum immunoglobulin E levels observed in female mice, gender is not a major factor in the present murine model of ovalbumin-induced lung inflammation. In contrast, gender might slightly influence the potency of test compounds such as steroids.