Early interleukin-4: its role in the switch towards a Th2 response and IgE-mediated allergy

Acteoside exerts immunomodulatory effects on dendritic cells via aryl hydrocarbon receptor activation and ameliorates Th2-mediated allergic asthma by inducing Foxp3+ regulatory T cells

Dendritic cells (DCs) are professional antigen-presenting cells that play a key role in directing T-cell responses and are involved in the pathogenesis of allergic asthma. Acteoside, an active phenylethanoid glycoside, is widely distributed in many medicinal plants. Herein, we explored the immunomodulatory effects of acteoside on bone marrow-derived DCs in vitro, and further investigated the immunosuppressive ability of acteoside to manipulate T helper type 2 (Th2)-mediated allergic asthma in mice. Following lipopolysaccharide activation, 50 μM of acteoside significantly reduced the production of proinflammatory mediators, including interleukin (IL)-12 and tumor necrosis factor (TNF)-α, whereas it enhanced secretion of the anti-inflammatory cytokine, IL-10, by DCs. However, these effects of acteoside on DCs were reversed by pretreatment with CH223191, an aryl hydrocarbon receptor (AhR) antagonist. Additionally, coculture of acteoside-treated DCs with CD4⁺ T cells promoted the generation of forkhead box P3-positive (Foxp3⁺) regulatory T cells (Tregs) via AhR activation. Using a murine asthma model, our results demonstrated that oral administration of 50 mg/kg of acteoside decreased levels of Th2-type cytokines, such as IL-4, IL-5, and IL-13, whereas the level of IL-10 and the frequency of CD4⁺Foxp3⁺ Tregs were augmented. Moreover, acteoside treatment markedly inhibited the elevated serum level of ovalbumin-specific immunoglobulin E, attenuated the development of airway hyperresponsiveness, and reduced inflammatory cell counts in bronchoalveolar lavage fluid. Additionally, histological results reveled that acteoside ameliorated pulmonary inflammation in asthmatic mice. Taken together, these results indicated that acteoside exhibits immunomodulatory effects on DCs and plays an anti-inflammatory role in the treatment of allergic asthma.

Immune System in Action

Tumor exists as a complex network of structures with an ability to evolve and evade the host immune surveillance mechanism. The immune milieu which includes macrophages, dendritic cells, natural killer cells, neutrophils, mast cells, B cells, and T cells is found in the core, the invasive margin, or the adjacent stromal or lymphoid component of the tumor. The immune infiltrate is heterogeneous and varies within a patient and between patients of the same tumor histology. The location, density, functionality, and the crosstalk between the immune cells in the tumor microenvironment influence the nature of immune response, prognosis, and treatment outcomes in cancer patients. Therefore, an understanding of the characteristics of the immune cells and their role in tumor immune surveillance is of paramount importance to identify immune targets and to develop novel immune therapeutics in the war against cancer. In this chapter, we provide an overview of the individual components of the human immune system and the translational relevance of predictive biomarkers.

Significance of Interleukin (IL)-4 and IL-13 in Inflammatory Arthritis

Interleukin (IL)-4 and IL-13 belong to the T helper 2 (Th2) cytokine family, along with IL-3, IL-5, and IL-9. These cytokines are key mediators of allergic inflammation. They have important immunomodulatory activities and exert influence on a wide variety of immune cells, such as B cells, eosinophils, basophils, monocytes, fibroblasts, endothelial cells, airway epithelial cells, smooth muscle cells, and keratinocytes. Recent studies have implicated IL-4 and IL-13 in the development of various autoimmune diseases. Additionally, these cytokines have emerged as potential players in pathogenesis of inflammatory arthritis. Recent findings suggest that the IL-4 and IL-13 might play a significant role in the downregulation of inflammatory processes underlying RA pathology, and beneficially modulate the course of the disease. This review summarizes the biological features of the IL-4 and IL-13 and provides current knowledge regarding the role of these cytokines in inflammatory arthritis.

Overview of Basic Immunology and Clinical Application

Tumor exists as a complex network of structures with an ability to evolve and evade the host immune surveillance mechanism. The immune milieu which includes macrophages, dendritic cells, natural killer cells, neutrophils, mast cells, B cells, and T cells are found in the core, the invasive margin, or the adjacent stromal or lymphoid component of the tumor. The immune infiltrate is heterogeneous and varies within a patient and between patients of the same tumor histology. The location, density, functionality, and cross-talk between the immune cells in the tumor microenvironment influence the nature of immune response, prognosis, and treatment outcomes in cancer patients. Therefore, an understanding of the characteristics of the immune cells and their role in tumor immune surveillance is of paramount importance to identify immune targets and to develop novel immune therapeutics in the war against cancer. In this chapter, we provide an overview of the individual components of the human immune system and the translational relevance of predictive biomarkers.

Ethanol Induction of Innate Immune Signals Across BV2 Microglia and SH-SY5Y Neuroblastoma Involves Induction of IL-4 and IL-13

Innate immune signaling molecules, such as Toll-like receptors (TLRs), cytokines and transcription factor NFκB, are increased in post-mortem human alcoholic brain and may play roles in alcohol dependence and neurodegeneration. Innate immune signaling involves microglia -neuronal signaling which while poorly understood, may impact learning and memory. To investigate mechanisms of ethanol induction of innate immune signaling within and between brain cells, we studied immortalized BV2 microglia and SH-SY5Y human neuroblastoma to model microglial and neuronal signaling. Cells were treated alone or in co-culture using a Transwell system, which allows transfer of soluble mediators. We determined immune signaling mRNA using real-time polymerase chain reaction. Ethanol induced innate immune genes in both BV2 and SH-SY5Y cultured alone, with co-culture altering gene expression at baseline and following ethanol exposure. Co-culture blunted ethanol-induced high mobility group box protein 1 (HMGB1)-TLR responses, corresponding with reduced ethanol induction of several proinflammatory NFκB target genes. In contrast, co-culture resulted in ethanol upregulation of cytokines IL-4 and IL-13 in BV2 and corresponding receptors, that is, IL-4 and IL-13 receptors, in SH-SY5Y, suggesting induction of a novel signaling pathway. Co-culture reduction in HMGB1-TLR levels occurs in parallel with reduced proinflammatory gene induction and increased IL-4 and IL-13 ligands and receptors. Findings from these immortalized and tumor-derived cell lines could provide insight into microglial-neuronal interactions via release of soluble mediators in vivo.

Schistosoma mansoni Egg-Released IPSE/alpha-1 Dampens Inflammatory Cytokine Responses via Basophil Interleukin (IL)-4 and IL-13

Schistosomes control inflammation in their hosts via highly effective mechanisms such as induction of Tregs, Bregs, and alternatively activated macrophages (AAMs). Notably, IPSE/alpha-1, the major secretory product from Schistosoma mansoni eggs, triggers basophils to release interleukin (IL)-4 and IL-13. Both cytokines are essential for AAM induction, suggesting an important role for IPSE/alpha-1 in inflammation control. Here, we show by in vitro co-culture experiments that IPSE/alpha-1-induced basophil IL-4/IL-13 inhibited pro-inflammatory cytokine release from human LPS-activated monocytes. This effect was cell/cell contact-independent but dependent on IL-4, since it was abrogated in the presence of anti-IL-4 antibodies. Importantly, the IPSE/alpha-1-induced IL-4/IL-13 release from basophils was amplified in the presence of LPS. Moreover, monocytes co-cultured in the presence of LPS with IPSE/alpha-1-stimulated basophils adopted an AAM-like phenotype as assessed by elevated expression of CD206 and CD209. The putative in vivo relevance of these findings was supported by immunohistological staining of S. mansoni-infected murine tissue revealing close physical contact between IPSE/alpha-1 and basophils in schistosome egg granulomas. Taken together, we found that IPSE/alpha-1 dampens inflammatory cytokine responses by triggering basophil IL-4/IL-13, in particular in the context of TLR activation, thereby turning inflammatory monocytes into anti-inflammatory AAMs. This might represent a mechanism used by schistosomes to control inflammation in the host.

IL-4 enhances survival of in vitro-differentiated mouse basophils through transcription-independent signaling downstream of PI3K

Interleukin 4 (IL-4) is a critical cytokine implicated with T_H2 immune reactions, which are linked to pathologic conditions of allergic diseases. In that context, the initiation of T_H2 responses can critically depend on early basophil-derived IL-4 to activate T-cell responses, which then amplify IL-4 secretion. As a pleiotropic cytokine, IL-4 acts on a broad variety of hematopoietic and non-hematopoietic cells. However, the effect of IL-4 on basophils themselves, which are emerging as relevant players in allergic as well as autoimmune diseases, was only scarcely addressed so far. Here we used in vitro-differentiated mouse basophils to investigate the direct effects of IL-4 on cellular viability and surface expression of the high-affinity receptor for IgE, FcεRI. We observed that IL-4 elicits pronounced pro-survival signaling in basophils, delaying spontaneous apoptosis in vitro to a degree comparable to the known pro-survival effects of IL-3. Our data indicate that IL-4-mediated survival depends on PI3K/AKT signaling and—in contrast to IL-3—seems to be largely independent of transcriptional changes but effectuated by post-translational mechanisms affecting BCL-2 family members among others. Additionally, we found that IL-4 signaling has a stabilizing effect on the surface expression levels of the critical basophil activation receptor FcεRI. In summary, our findings indicate an important regulatory role of IL-4 on in vitro-differentiated mouse basophils enhancing their survival and stabilizing FcεRI receptor expression through PI3K-dependent signaling. A better understanding of the regulation of basophil survival will help to define promising targets and consequently treatment strategies in basophil-driven diseases.

Assessing the effect of 5-hydroxymethylfurfural on selected components of immune responses in mice immunised with ovalbumin

BACKGROUND

5-Hydroxymethylfurfural (5-HMF) is one of the most important products of the Maillard reaction. In recent years, many profitable biological effects of this compound have been demonstrated. This study sought to elucidate the anti-allergic effect of 5-HMF by investigating some selected components of the immune response in BALB/c mice immunised with ovalbumin (OVA).

RESULTS

Immunised animals had an increased level of serum total and OVA-specific antibodies when compared to the control (P < 0.01).We found that the OVA-induced increase in serum IgE and OVA-specific IgE were significantly suppressed in the groups treated with 5-HMF (P < 0.05). Moreover, interleukin-4 (IL-4) and interferon gamma (IFN-γ) were significantly reduced in a dose-independent manner when compared to the sensitised group (P < 0.05).

CONCLUSION

5-HMF inhibited the up-regulation of total and OVA-specific IgE through the suppression of the Th2-type immune response in immunised BALB/c mice. 5-HMF could therefore be a novel therapeutic approach for the prevention of IgE-mediated allergic diseases. © 2017 Society of Chemical Industry.

Overview of Basic Immunology for Clinical Investigators

Tumor exists as a complex network of structures with an ability to evolve and evade the host immune surveillance mechanism. The immune milieu which includes macrophages, dendritic cells, natural killer cells, neutrophils, mast cells, B cells, and T cells are found in the core, the invasive margin, or the adjacent stromal or lymphoid component of the tumor. The immune infiltrate is heterogeneous and varies within a patient and between patients of the same tumor histology. The location, density, functionality, and the cross talk between the immune cells in the tumor microenvironment influence the nature of immune response, prognosis, and treatment outcomes in cancer patients. Therefore, an understanding of the characteristics of the immune cells and their role in tumor immune surveillance is of paramount importance to identify immune targets and to develop novel immune therapeutics in the war against cancer. In this chapter, we provide an overview of the individual components of the human immune system and the translational relevance of predictive biomarkers.

Neuroimmunology of the Interleukins 13 and 4

The cytokines interleukin 13 and 4 share a common heterodimeric receptor and are important modulators of peripheral allergic reactions. Produced primarily by T-helper type 2 lymphocytes, they are typically considered as anti-inflammatory cytokines because they can downregulate the synthesis of T-helper type 1 pro-inflammatory cytokines. Their presence and role in the brain is only beginning to be investigated and the data collected so far shows that these molecules can be produced by microglial cells and possibly by neurons. Attention has so far been given to the possible role of these molecules in neurodegeneration. Both neuroprotective or neurotoxic effects have been proposed based on evidence that interleukin 13 and 4 can reduce inflammation by promoting the M2 microglia phenotype and contributing to the death of microglia M1 phenotype, or by potentiating the effects of oxidative stress on neurons during neuro-inflammation. Remarkably, the heterodimeric subunit IL-13Rα1 of their common receptor was recently demonstrated in dopaminergic neurons of the ventral tegmental area and the substantia nigra pars compacta, suggesting the possibility that both cytokines may affect the activity of these neurons regulating reward, mood, and motor coordination. In mice and man, the gene encoding for IL-13Rα1 is expressed on the X chromosome within the PARK12 region of susceptibility to Parkinson’s disease (PD). This, together with finding that IL-13Rα1 contributes to loss of dopaminergic neurons during inflammation, indicates the possibility that these cytokines may contribute to the etiology or the progression of PD.

Antibiotics, pediatric dysbiosis, and disease

Antibiotics are by far the most common medications prescribed for children. Recent epidemiological data suggests an association between early antibiotic use and disease phenotypes in adulthood. Antibiotic use during infancy induces imbalances in gut microbiota, called dysbiosis. The gut microbiome's responses to antibiotics and its potential link to disease development are especially complex to study in the changing infant gut. Here, we synthesize current knowledge linking antibiotics, dysbiosis, and disease and propose a framework for studying antibiotic-related dysbiosis in children. We recommend future studies into the microbiome-mediated effects of antibiotics focused on four types of dysbiosis: loss of keystone taxa, loss of diversity, shifts in metabolic capacity, and blooms of pathogens. Establishment of a large and diverse baseline cohort to define healthy infant microbiome development is essential to advancing diagnosis, interpretation, and eventual treatment of pediatric dysbiosis. This approach will also help provide evidence-based recommendations for antibiotic usage in infancy.

Glycans expressed on Trichinella spiralis excretory-secretory antigens are important for anti-inflamatory immune response polarization

Trichinella spiralis muscle larvae excretory-secretory antigens (ES L1) are most likely responsible for the induction of immune response during infection by this parasitic. The antigens bear carbohydrate structures that may contribute to immune system activation resulting in a Th2/anti-inflammatory immune response. We show that T. spiralis glycans affect the expression and the production of IL-4 and IL-10 in vivo. Alteration of carbohydrate structures on ES L1 altered dendritic cell (DC) maturation. Periodate treatment of ES L1 led to the reduction in both ERK and p38 phosphorylation which may be the cause of reduced IL-10 and IL-12p70 production. In vitro priming of naïve T cells with DCs stimulated with native and periodate-treated ES L1 emphasized the importance of intact glycans for IL-10 production. We conclude that T. spiralis glycans affect the anti-inflammatory environment and can interfere with the development of inflammatory diseases.

Differential expression and function of human IL-12Rβ2 polymorphic variants

The receptor for interleukin-12, formed by IL-12Rβ1 and IL-12Rβ2, mediates the type I immune responses of various types of lymphocytes. Polymorphisms in IL12RB2, the gene encoding IL-12Rβ2, were reported to be associated with several immune related diseases, such as Crohn's disease. Because the IL23R and IL12RB2 genes are located in close proximity on the genome, the reported associations might also be attributable to linked polymorphisms in IL23R, which were found to be associated with immune related diseases as well. To clarify the role of IL-12Rβ2 in immune diseases, we investigated the functional consequences of thirteen amino acid substitutions in IL-12Rβ2. We developed a model with retroviral expression of IL-12Rβ2 in B cell lines. With the use of this model the expression and function of the variants was compared within the same genetic background. Four of the IL-12Rβ2 variants, N271Y, R313G, A604V and L808R showed reduced IL-12 responses compared to the wild type variant. Two of these are relatively common in some populations and may be used in future association studies to reveal a role for IL-12 in infectious and/or immune related diseases.

Basophils as Key Regulators of Allergic Inflammation and Th2-type Immunity

Basophils have long been suspected as playing more than a bystander role in initiating and maintaining allergic disorders, despite their relatively low numbers compared with other effector cells, such as mast cells and eosinophils. In vitro studies clearly demonstrated their propensity to generate proallergic cytokines, such as interleukin 4 and interleukin 13, as well as histamine and leukotrienes after simulation with allergens and innate IgE-dependent triggers. However, only very recently have mouse basophils been identified as key regulators of allergy in vivo, including orchestrating Th2 immunity to protease allergens in the induction phase. This review highlights these exciting advances that go far in unraveling our understanding of basophil function in the orchestration of allergic inflammation.

Protective effects of Mentha haplocalyx ethanol extract (MH) in a mouse model of allergic asthma

Mentha haplocalyx Briq., a commonly used herb in traditional Oriental medicine, has a variety of known pharmacological properties. However, neither the protective effects of Mentha haplocalyx ethanol extract (MH) against inflammation of the airway in an asthmatic model nor the mechanisms involved, have previously been reported. In the present study, an ovalbumin (OVA)-induced mouse model of allergic asthma was used to investigate whether MH was effective against the disease through regulation of airway inflammation. The MH treatment significantly inhibited increases in immunoglobulin (Ig) E and T-helper 2 (Th2)-type cytokines such as IL-4 and IL-5 in bronchoalveolar lavage fluid (BALF) and lung tissue. Inflammatory cell infiltration of the airway in mice treated with MH was effectively alleviated when compared with infiltration seen in the OVA-induced group. These data indicated that decreased cytokine levels are the result of the decreased number of invaded leukocytes. Also, the generation of reactive oxygen species (ROS) in BALF was diminished by MH treatment. Taken together, these findings indicate that the administration of MH may have potential therapeutic value in the treatment of inflammatory disease.

Anti-inflammatory effect of glycoprotein isolated from Cudrania tricuspidata Bureau: involvement of MAPK/NF-κB signaling

The aim of this study was to evaluate inhibitory effect of glycoprotein isolated from Cudrania tricuspidata Bureau (CTB glycoprotein) on allergic responses. We evaluated the activities of mitogen-activated protein kinase (MAPK), transcriptional factor, and production of immunoglobulin (Ig)E and interleukin (IL)-4 in RBL-2H3 cells and BALB/c mice. Our results showed that CTB glycoprotein inhibited the production of IgE and IL-4 in serum from ovalbumin (OVA)-treated BALB/c mice. We also found that CTB glycoprotein inhibited the phosphorylation of p38 MAPK, and transcriptional activation of nuclear factor (NF)-κB in RBL-2H3 cells. The activation of NF-κB was effectively blocked by treatment with p38 MAPK inhibitor (SKF86002). The results from these experiments indicate that the CTB glycoprotein inhibits release of β-hexosaminidase, and production of IgE and IL-4 via down regulation of MAPK/ NF-κB on the stage of mast cell degranulation. In conclusion, we suggest that the CTB glycoprotein might be a potent preventive agent in allergic responses.

Interferon gamma and interleukin 4 have contrasting effects on immunopathology and the development of protective adaptive immunity against mycoplasma respiratory disease

For vaccine development, it is critical to understand the regulatory mechanisms determining resistance and immunopathology against mycoplasma respiratory diseases. The present study evaluated the contribution of the polarizing cytokines interferon gamma (IFN-gamma) and interleukin 4 (IL-4) in the regulation of mycoplasma-specific immunity. The absence of a single cytokine (either IFN-gamma or IL-4) uniquely altered the expression of multiple chemokines and cytokines in the lungs of uninfected mice and influenced responses to mycoplasma infection. Most importantly, prior nasal-pulmonary immunization of IFN-gamma(-/-) mice led to exacerbated mycoplasma disease, whereas immunized IL-4(-/-) mice were dramatically more resistant than wild-type mice. Helper T cell type 2 responses in IFN-gamma(-/-) mice corresponded to immunopathologic reactions that developed after mycoplasma infection or immunization. Thus, adaptive immunity clearly can independently promote either protection or immunopathology against mycoplasma infection, and optimal vaccination appears to be dependent on promoting protective IFN-gamma-dependent networks (perhaps helper T cell type 1 responses) while minimizing the effect of IL-4-mediated responses, which dampen the generation of protective immunity.

Bambusae Caulis in Taeniam extract reduces ovalbumin-induced airway inflammation and T helper 2 responses in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Bambusae Caulis in Taeniam (BC) was known as traditional herbal medicine with anti-inflammatory property in the Orient.

AIM OF THE STUDY

Allergic asthma is inflammatory disease of airways associated with enhanced T helper (Th) 2 lymphocytes responses to allergens, leading to eosinophilic infiltration and elevated serum IgE levels. Although there were some studies that BC extract had an anti-inflammatory property, there was no study on asthma. In present study, we investigated the suitability of BC extract as a therapeutic candidate in the treatment of allergic airway disease in ovalbumin-induced asthma model.

MATERIALS AND METHODS

Balb/C mice (female, 6 weeks old) were treated by ovalbumin sensitization and nebulization, and used as asthma model. The number of eosinophil in bronchoalveolar lavage (BAL) fluid and the degree of eosinophila were investigated by hematoxylin and eosin stain and the infiltration of inflammatory cells into lung tissues was examined by staining by hematoxylin and eosin solution. The levels of interleukin (IL)-4 in BAL fluid, immunoglobulin E (IgE) in serum, interferon (IFN)-gamma and IL-4 production in splenocyte culture from Balb/C mice (not treated, 6 weeks old) that incubated with or without BC extract for 48 h were determined by enzyme-linked immunosorbent assay.

RESULTS

The level of eosinophils was decreased by treatment of the animals with BC extract (40 mg/kg) and correspondingly, a significantly lowered degree of eosinophila was also reported (p<0.01). In lung tissue, BC extract reduced the increased immune cell infiltration induced by OVA (p<0.05). Furthermore, the levels of IL-4 and IgE in BAL fluid or serum up-regulated by OVA was decreased by BC extract. Finally, IFN-gamma production was significantly increased (p<0.01), while IL-4 production significantly decreased (p<0.01), after treatment of the culture supernatants of splenocytes with BC extract.

CONCLUSIONS

These results indicated that BC extract reduces OVA-induced airway inflammation and Th 2 response in mice, suggesting that BC extract can be a therapeutic candidate for allergic airway disease, including asthma.

Basophils: what they 'can do' versus what they 'actually do'

Basophils, the least abundant granulocytes, have poorly understood functions. They have been linked to the development of T helper type 2 immunity during parasite infection and allergic inflammation. Emerging evidence has not only shown the critical involvement of basophils in the development of T helper type 2 immunity but also provided useful animal models with which basophil functions can be further examined. However, distinctions must be made between what basophils 'can do' after in vitro manipulation and what they 'actually do' during in vivo immune responses; these may be very different. In this review, the functions of basophils determined on the basis of analysis of in vitro and in vivo systems and their potential involvement in clinical settings are discussed.

Disruption of the gamma c cytokine network in T cells during HIV infection

The common gamma chain (gammac)-sharing cytokines (IL's-2, 4, 7, 9, 15, and 21) play a vital role in the survival, proliferation, differentiation and function of T lymphocytes. As such, disruption of their signaling pathways would be expected to have severe consequences on the integrity of the immune system. Indeed, it appears that the signaling network of these cytokines is both disrupted and exploited by HIV at various stages of infection. IL-2 secretion and signaling downstream of its receptor are impaired in T cells from chronically-infected HIV+ patients. Elevated plasma IL-7 levels and decreased IL-7Ralpha expression in patient T cells results in significantly decreased responsiveness to this critical cytokine. Interestingly, IL-2 and IL-15 are also able to render CD4+ T cells permissive to HIV infection through their influence on the activity of the APOBEC3G deaminase enzyme. Herein, we describe the current state of knowledge on how the gammac cytokine network is affected during HIV infection, with a focus on how this impairs CD4+ and CD8+ T cell function while also benefiting the virus itself. We also address the use of cytokines as adjuncts to highly active antiretroviral therapy to bolster immune reconstitution in infected patients.

Anti-inflammatory and Immune-regulatory Effects of Subcutaneous Perillae Fructus Extract Injections on OVA-induced Asthma in Mice

Perillae fructus (perilla seed) is a traditional medicinal herb used to treat bronchial asthma in Oriental medical clinics. ST36 is one of the most widely used acupuncture points, particularly for immune system regulation. Injection of an herbal extract into an acupuncture point (herbal acupuncture) is a therapeutic technique combining both acupuncture and herbal treatment. Perillae fructus extract was injected subcutaneously (Perillae fructus herbal acupuncture; PF-HA) at acupoint ST36 of OVA-induced asthmatic mice. The lung weight, bronchoalveolar fluid (BALF) cell count, the number of CCR3+, CD11b+, CD4+ and CD3e+/CD69+ cells in the lung, and the level of IgE, IL-4, IL-5 and IL-13 in BALF and serum were then measured. RT-PCR was used to measure the mRNA expression of IL-4, IL-5, IL-13 and TNF-α in the lung. Lung sections were analyzed histologically. PF-HA significantly reduced lung weight, the number of inflammatory cells in the lung and BALF, the levels of IgE and Th2 cytokines in BALF and serum, mRNA expression of Th2 cytokines in the lung, and pathological changes in lung tissue. Our results suggest that PF-HA may have an anti-inflammatory and immune-regulatory effect on bronchial allergic asthma by restoring the Th1/Th2 imbalance in the immune system and suppressing eosinophilic inflammation in airways.

Potato lectin activates basophils and mast cells of atopic subjects by its interaction with core chitobiose of cell-bound non-specific immunoglobulin E

A major factor in non-allergic food hypersensitivity could be the interaction of dietary lectins with mast cells and basophils. Because immunoglobulin E (IgE) contains 10-12% carbohydrates, lectins can activate and degranulate these cells by cross-linking the glycans of cell-bound IgE. The present objective focuses on the effect of potato lectin (Solanum tuberosum agglutinin; STA) for its ability to release histamine from basophils in vitro and mast cells in vivo from non-atopic and atopic subjects. In this study, subjects were selected randomly based on case history and skin prick test responses with food, pollen and house dust mite extracts. Skin prick test (SPT) was performed with STA at 100 microg/ml concentration. Histamine release was performed using leucocytes from non-atopic and atopic subjects and rat peritoneal exudate cells. SPT on 110 atopic subjects using STA showed 39 subjects positive (35%); however, none showed STA-specific IgE; among 20 non-atopic subjects, none were positive by SPT. Maximal histamine release was found to be 65% in atopic subjects (n = 7) compared to 28% in non-atopic subjects (n = 5); the release was inhibited specifically by oligomers of N-acetylglucosamine and correlates well with serum total IgE levels (R(2) = 0.923). Binding of STA to N-linked glycoproteins (horseradish peroxidase, avidin and IgG) was positive by dot blot and binding assay. As potato lectin activates and degranulates both mast cells and basophils by interacting with the chitobiose core of IgE glycans, higher intake of potato may increase the clinical symptoms as a result of non-allergic food hypersensitivity in atopic subjects.

The 21st century renaissance of the basophil? Current insights into its role in allergic responses and innate immunity

Basophils and mast cells express all the three subchains of the high-affinity immunoglobulin E (IgE) receptor Fc epsilon RI and contain preformed histamine in the cytoplasmic granules. However, it is increasingly clear that these cells play distinct roles in allergic inflammatory disease. Despite their presence throughout much of the animal kingdom, the physiological function of basophils remains obscure. As rodent mast cells are more numerous than basophils, and generate an assortment of inflammatory cytokines, basophils have often been regarded as minor players in allergic inflammation. In humans, however, basophils are the prime early producers of interleukin (IL)-4 and IL-13, T helper (Th)2-type cytokines crucial for initiating and maintaining allergic responses. Basophils also express CD40 ligand which, in combination with IL-4 and IL-13, facilitates IgE class switching in B cells. They are the main cellular source for early IL-4 production, which is vital for the development of Th2 responses. The localization of basophils in various tissues affected by allergic inflammation has now been clearly demonstrated by using specific staining techniques and the new research is shedding light on their selective recruitment to the tissues. Finally, recent studies have shown that basophil activation is not restricted to antigen-specific IgE crosslinking, but can be caused in non-sensitized individuals by a growing list of parasitic antigens, lectins and viral superantigens, binding to non-specific IgE antibodies. This, together with novel IgE-independent routes of activation, imparts important new insights into the potential role of basophils in both adaptive and innate immunity.

Attenuated Salmonella typhimurium reduces ovalbumin-induced airway inflammation and T-helper type 2 responses in mice

Cytokines produced by Th2 cells are responsible for the pathogenesis of asthma. Th1-biased immune responses caused by attenuated salmonella have the potential to relieve asthmatic symptoms. We evaluated whether oral administration of attenuated salmonella could modulate allergic responses in a chicken ovalbumin (OVA)-induced asthmatic murine model. Mice were fed with attenuated salmonella SL7207 one dose before and three doses during the induction of an allergic response. Lung histology, percentages of eosinophil in bronchoalveolar lavage fluid, serum levels of OVA-specific antibodies and cytokine production by OVA-activated splenocytes were evaluated in mice with or without the administration of SL7207. A significant reduction in pulmonary eosinophilic infiltration was observed in mice receiving attenuated salmonella. Lower levels of OVA-specific IgG1 but higher titres of OVA-IgG2a in serum were also detected in this group. Splenocytes from salmonella-fed mice produced lower levels of Th2 cytokines upon OVA stimulation. The administration of attenuated salmonella significantly suppressed immunopathological symptoms in OVA-sensitized mice. Inhibition of Th2 responses might explain the potential mechanisms. This study provides some evidence for the feasibility of attenuated salmonella as an effective vaccine for allergic diseases.

Interleukin-4 can induce interleukin-4 production in dendritic cells

The presence of interleukin-4 (IL-4) during the generation of dendritic cells (DC) from precursor cells results in measurable increases of IL-12 in supernatants but IL-4 secretion has not been reported. However, DC have IL-4 receptors and are able to make IL-4. We therefore sought evidence for autocrine effects of IL-4 on DC. IL-4 gene expression was low in DC generated from bone-marrow stem cells in the presence of granulocyte-macrophage colony-stimulating factor but was up-regulated by exposure of the developing DC to IL-4. Exposure to IL-4 also induced intracellular IL-4 production in DC. The intracellular IL-4 induced in the presence of IL-4 was increased following further DC maturation with tumour necrosis factor-alpha. By contrast, in supernatants of DC, IL-4 was rarely detected and only at late culture periods. However, after exposure of DC to IL-4, cell-bound IL-4 was detected transiently, which suggested binding and internalization of the cytokine. Binding via IL-4 receptor-alpha was indicated from phosphorylation of the signal transducer and activator of transcription (STAT) protein 6, which is known to mediate IL-4 function. Cytokine persisting within the supernatants of the cells may therefore be unrepresentative of the actual production and function of IL-4 in the cells; IL-4 may be produced in DC in response to exposure to IL-4 but may then be lost from the supernatants during cell binding and activation of the cells.

Negative control of basophil expansion by IRF-2 critical for the regulation of Th1/Th2 balance

Although basophils are known to produce interleukin 4 (IL-4), the roles of these cells have been documented only in mice infected with parasites or in the effector phase of allergic inflammations. Here we show that naive mice lacking the transcription factor, interferon regulatory factor 2 (IRF-2), exhibited signal transducer and activator of transcription 6 (Stat6)–independent expansion of basophils in the periphery. IRF-2 appeared to act autonomously in the cells to negatively regulate the expansion of, but not cytokine production by, basophils. Spontaneous Th2 polarization of CD4+ T cells was observed in these mice and the genetic reduction of basophil numbers by mutating the Kit gene abolished such a polarization in vivo. We also found that both basophils and IL-4 derived from them were indeed essential for Th2 development under neutral conditions in vitro. Furthermore, neutralization of IL-3 abolished IL-4 production by basophils during Th1/Th2 differentiation cultures and subsequent Th2 development. These results indicated that basophils acted as a cellular converter to turn the neutral IL-3 into the Th2-inducing IL-4 during the initiation of Th1/Th2 differentiation. Thus, the negative regulatory role of IRF-2 on the basophil population size is critically important for preventing excess Th2 polarization and the Th1/Th2 balance in naive animals.

Differential Role for Mitogen-Activated Protein Kinases in IgE-Dependent Signaling in Human Peripheral Blood Basophils: In Contrast to p38 MAPK, c-Jun N-Terminal Kinase Is Poorly Expressed and Does Not Appear to Control Mediator Release

BACKGROUND

Exposure of human basophils to allergens results in a rapid secretion of histamine, LTC(4), IL-4 and IL-13, which dominate both the symptomology of allergic diseases and support the underlying Th2/IgE predominance associated with these reactions. The IgE-dependent release of these mediators in basophils crucially involves PI 3-kinase and the subsequent activation of p38 MAPK and ERK1&2. Here, we investigated the role of the third major member of the mitogen activated kinase family, namely the c-Jun amino terminal kinase (JNK), which is rapidly activated following IgE receptor cross-linking in murine mast cells.

METHODS

Human basophils were highly purified by magnetic cell sorting. The activities of various intracellular signaling components, in basophils that had been stimulated under various conditions, were assessed by Western blotting. Mediator secretions were also determined using either spectrofluorometric analysis (histamine) or ELISA (LTC(4), IL-4 and IL-13).

RESULTS

Our results show that while JNK is moderately expressed in human basophils, it is not consistently phosphorylated upon anti-IgE stimulation. Phosphorylation of the transcription factor c-Jun, a downstream target of JNK, was also undetected in contrast to p38 MAPK and ERK1&2, which were clearly activated following anti-IgE stimulation of the cells. Additionally, inhibitors of the JNK pathway failed to prevent basophil mediator release and had no effect on the phosphorylation of p38 MAPK or ERK1&2 at concentrations which were specific for JNK blockade.

CONCLUSIONS

These data suggest major differences in utilizing various members of the mitogen-activated kinase family in the signal transduction cascade of IgE-receptor-bearing cells.

Impact of cethromycin (ABT-773) therapy on microbiological, histologic, immunologic, and respiratory indices in a murine model of Mycoplasma pneumoniae lower respiratory infection

Mycoplasma pneumoniae is a major etiologic agent of acute lower respiratory infections. We evaluated the antimicrobial and immunologic effects of cethromycin (ABT-773), a ketolide antibiotic, for the treatment of M. pneumoniae pneumonia in a mouse model. Eight-week-old BALB/c mice were inoculated intranasally once with 10(6) CFU of M. pneumoniae on day 0. Treatment was started 24 h after inoculation. Groups of mice were treated subcutaneously with cethromycin at 25 mg/kg of body weight or with placebo daily until sacrifice. Five to ten mice per group were evaluated at days 1, 4, 7, and 10 after inoculation. Outcome variables included bronchoalveolar lavage (BAL) for M. pneumoniae quantitative culture and cytokine and chemokine concentration determinations by enzyme-linked immunosorbent assay (tumor necrosis factor alpha [TNF-alpha], gamma interferon [IFN-gamma], interleukin-1beta [IL-1beta], IL-2, IL-4, IL-12, granulocyte-macrophage colony-stimulating factor, IL-8, monocyte chemoattractant protein 1 [MCP-1], and macrophage inflammatory protein 1alpha [MIP-1alpha]), histopathologic score of the lungs (HPS), and pulmonary function tests (PFT) using whole-body, unrestrained plethysmography at the baseline and post-methacholine exposure as indicators of airway obstruction (AO) and airway hyperresponsiveness (AHR), respectively. The cethromycin-treated mice had a greater reduction in M. pneumoniae culture titers than placebo-treated mice, reaching statistical significance on days 7 and 10 (P < 0.05). HPS was significantly reduced in cethromycin-treated mice compared with placebo-treated mice on days 4, 7, and 10 (P < 0.05). Cytokine concentrations in BAL samples were reduced in mice that received cethromycin, and the differences were statistically significant for 7 of the 10 cytokines measured (TNF-alpha, IFN-gamma, IL-1beta, IL-8, IL-12, MCP-1, and MIP-1alpha) on day 4 (P < 0.05). PFT values were improved in the cethromycin-treated mice, with AO and AHR significantly reduced on day 4 (P < 0.05). In this mouse model, treatment with cethromycin significantly reduced M. pneumoniae culture titers in BAL samples, cytokine and chemokine concentrations in BAL samples, histologic inflammation in the lungs, and disease severity as defined by AO and AHR.

The upper and lower respiratory tracts differ in their requirement of IFN-gamma and IL-4 in controlling respiratory mycoplasma infection and disease

The purpose of this study is to evaluate the significance of IFN-gamma and IL-4 production in controlling mycoplasma infection and the pathogenesis of disease in the upper and lower respiratory tract. By using IFN-gamma knockout and IL-4 knockout BALB/c mice, we were able to study the contribution of these cytokines in the development of pathogenesis and/or protection in response to mycoplasma respiratory infection, in both the upper and lower respiratory tracts. The loss of either IFN-gamma or IL-4 does not affect disease pathogenesis or mycoplasma organism numbers in the upper respiratory tract. However, in the absence of IL-4, the nasal passages developed a compensatory immune response, characterized by higher numbers of macrophages and CD8(+) T cells, which may be masking detrimental effects due to IL-4 deficiency. This is in contrast to the lower respiratory tract, where the loss of IFN-gamma, but not IL-4, leads to higher mycoplasma numbers and increased disease severity. The loss of IFN-gamma impacted the innate immune system's ability to effectively clear mycoplasma, as the number of organisms was higher by day 3 postinfection. This higher organism burden most likely impacted disease pathogenesis; however, the development of Th2 cell-mediated adaptive immune response most likely contributed to lesion severity at later time points during infection. Our studies demonstrate that the upper and lower respiratory tracts are separate and distinct in their cytokine requirements for generating immunity against mycoplasma infection.

Enhancement of Interleukin-4 Production in Activated CD4+ T Cells by Diphthalate Plasticizers via Increased NF-AT Binding Activity

BACKGROUND

Diethylhexyl phthalate (DEHP) and diisononyl phthalate (DINP), two commonly used plasticizers in flexible polyvinylchloride formulations, have potentially adverse effects on human health. However, the influence of these diphthalates on allergic responses remains unclear. In this study we examined the effects of DEHP and DINP on IL-4 production in CD4+ T cells and the level of IgE in sera, critical hallmarks associated with allergic diseases.

METHODS

Mouse T cells were exposed to two diphthalates in vitro and in vivo. The levels of IL-4 and IgE were determined by ELISA, and the degree of NF-AT activation was determined by IL-4 gene promoter assay and electrophoretic mobility shift assay.

RESULTS AND DISCUSSION

Both DEHP and DINP significantly enhanced IL-4 production in activated CD4+ T cells in a concentration-dependent manner. Treatment with DEHP or DINP in vivo resulted in a significant increase of IL-4 production in CD4+ T cells and of IgE levels in sera. Furthermore, DEHP and DINP enhanced the activation of IL-4 gene promoter in EL4 T cells and the enhancing effect mapped to a region in the IL-4 promoter containing binding sites for a transcription factor, NF-AT. The activation of T cells resulted in markedly enhanced binding activities to the NF-AT site, which significantly increased upon addition of DEHP or DINP, indicating that NF-AT was involved in the enhancing effect of DEHP and DINP on IL-4 production. These findings suggest that both DEHP and DINP enhance allergic responses by enhancement of IL-4 production in CD4+ T cells via stimulation of NF-AT-binding activity.

Exposure to 4-tert-octylphenol, an environmentally persistent alkylphenol, enhances interleukin-4 production in T cells via NF-AT activation

4-tert-Octylphenol (OP) is a representative endocrine disruptor that may have adverse effects on human health. The influence of this compound on allergic immune responses remains unclear. In this study, we have examined the effects of OP on production of interleukin-4 (IL-4), a pro-inflammatory cytokine closely associated with allergic immune responses. OP significantly enhanced IL-4 production in antigen-primed T cells in a dose-dependent manner. Treatment with OP in vivo resulted in significant increase of IL-4 production in T cells and of IgE levels in sera of antigen-primed mice. Furthermore, OP enhanced the activation of IL-4 gene promoter in EL4 T cells transiently transfected with IL-4 promoter/reporter constructs, and the enhancing effect mapped to a region in the IL-4 promoter containing binding sites for nuclear factor of activated T cell (NF-AT). Activation of T cells by phorbol-12-myristate-13-acetate (PMA) resulted in markedly enhanced binding activities to the NF-AT site, which significantly increased upon addition of OP, indicating that the transcription factor NF-AT was involved in the enhancing effect of OP on IL-4 production. The enhancement of IL-4 production by OP was blocked by FK506, a calcineurin inhibitor, but not by the estrogen receptor (ER) antagonist ICI 182780. FK506 inhibited the NF-AT-DNA binding activity and IL-4 gene promoter activity enhanced by OP in a dose-dependent manner. These findings demonstrate that OP enhances IL-4 production in T cells via the stimulation of calcineurin-dependent NF-AT activation.

Rosmarinic acid in perilla extract inhibits allergic inflammation induced by mite allergen, in a mouse model

BACKGROUND

Perilla and its constituent rosmarinic acid have been suggested to have anti-allergic activity. However, few studies have examined the effects on allergic asthma.

OBJECTIVE

The purpose of this study was to evaluate the effect of oral administration of perilla leaf extract, which contains high amount of rosmarinic acid, on a murine model of allergic asthma induced by house dust mite allergen.

METHODS

C3H/He mice were sensitized by intratracheal administration of Dermatophagoides farinae (Der f). Mice were orally treated with rosmarinic acid in perilla extract (PE) (1.5 mg/mouse/day).

RESULTS

Der f challenge of sensitized mice elicited pulmonary eosinophilic inflammation, accompanied by an increase in lung expression of IL-4 and IL-5, and eotaxin. Daily treatment with rosmarinic acid in PE significantly prevented the increases in the numbers of eosinophils in bronchoalveolar lavage fluids and also in those around murine airways. Rosmarinic acid in PE treatment also inhibited the enhanced protein expression of IL-4 and IL-5, and eotaxin in the lungs of sensitized mice. Der f challenge also enhanced allergen-specific IgG1, which were also inhibited by rosmarinic acid in PE.

CONCLUSION

These results suggest that oral administration of perilla-derived rosmarinic acid is an effective intervention for allergic asthma, possibly through the amelioration of increases in cytokines, chemokines, and allergen-specific antibody.

Both free-living and parasitic nematodes induce a characteristic Th2 response that is dependent on the presence of intact glycans

Infection with parasitic nematodes is characterized by the induction of a profound type 2 immune response. We have studied the role of glycans in the induction of the skewed type 2 response by antigens of the parasitic nematode Brugia malayi as well as the free-living nematode Caenorhabditis elegans. Lymph node cells from BALB/c mice immunized with soluble extracts of the two nematodes showed distinct antigen-specific proliferation and cytokine production; however, both nematodes induced antigen-specific interleukin 4 (IL-4) production, demonstrating that the induction of a biased type 2 response is not unique to parasitic nematodes. Sodium periodate-treated soluble extracts of both nematodes consistently induced significantly less IL-4 production than the respective mock-treated extracts, indicating that glycans play a critical role in the induction of the Th2 immune response by these nematodes. The glycan-dependent induction of the Th2-potentiating cytokine IL-4 occurs by 72 h postinoculation. Our data suggest that glycan determinants common to nematodes act as ligands, displaying distinct molecular patterns that trigger the immune system to launch a biased Th2 immune response upon exposure to these organisms or their products. Further, the similarity of our findings to those for Schistosoma mansoni egg antigen is striking considering the enormous phylogenetic distance between nematodes and trematodes. These data thus have important implications for how the mammalian host responds to widely divergent metazoan invaders and suggest that the powerful C. elegans model system can be used to address these questions.

Activation of mast cells is essential for development of house dust mite Dermatophagoides farinae-induced allergic airway inflammation in mice

In this study, we demonstrate that Dermatophagoides farinae (Der f), a major source of airborne allergens, but not OVA, could rapidly activate mast cells in mice. This was indicated by an elevation of serum mouse mast cell protease 1, a mast cell-specific proteinase, as early as 30 min after intratracheal challenge. Administration of sodium cromoglycate (40 mg/kg, i.p., 1 h before Der f instillation), a mast cell stabilizer, not only suppressed acute mouse mast cell protease 1 production but also attenuated the allergic airway inflammation provoked by repetitive Der f challenge in mice (five times at 1-wk interval). Der f induced the expression of mRNA for TNF-alpha, IL-1beta, IL-4, IL-6, IL-9, and IL-13 in mastocytoma P815 cells and stimulated both P815 cells and bone marrow-derived mast cells to produce IL-4, IL-6, and TNF-alpha in a dose- and time-dependent manner. Cycloheximide as well as sodium cromoglycate blocked the Der f-induced IL-4 production, indicating a de novo protein synthesis process. Supernatants of Der f-stimulated mast cells chemoattracted monocytes and T lymphocytes; they up-regulated the expression of costimulatory B7 molecules, eotaxin, RANTES, monocyte chemoattractant protein 1, and IFN-inducible protein 10 mRNA of alveolar macrophages; they supported PHA-induced T cell proliferation; and they promoted Th2 cell development. Our data indicate that mast cells may be an important cell type during the initiation of Der f sensitization in the airway by modulating the function of alveolar macrophages and T cells.

Lectins interact differentially with purified human eosinophils, cultured cord blood-derived mast cells and the myeloid leukaemic cell line AML14.3D10: induction of interleukin-4 secretion is conserved among granulocytes, but is not proportional to agglutination or lectin-glycoprotein interaction

BACKGROUND

Atopy is closely associated with the cellular T helper type-2 (Th2) phenotype, that is dominated by the pleiotrophic cytokine IL-4. The cellular source of IL-4 has yet to be determined, although basophils have been proposed. Eosinophils and mast cells are likely contenders investigated here, and the eosinophil-like leukaemia line AML14.3D10 is compared to eosinophils as an in vitro culturable model for eosinophils. Lectins can cross-link-specific surface glycoproteins and are found in the ingested (processed foods) and inhaled (airborne pollen grains) human environment. Therefore it is of interest to determine whether lectins can elicit the release of IL-4 from Th2-associated granulocytes other than basophils.

METHOD

This study investigated the ability of eosinophils, AML14.3D10 and mast cells to secrete preformed IL-4 in response to stimulation with lectins, and explored molecular mechanisms underlying the interaction.

RESULTS

Purified eosinophils and basophils, and cultured mast cells and AML14.3D10 cells were incubated with 1 micro m lectin. Agglutination was scored by microscopy. IL-4 secretion was measured by enzyme-linked immunosorbent assay. Biotinylated lectins were used to determine binding to cells by flow cytometry and in lectin blots of sodium dodecyl sulphate (SDS) gels.

DISCUSSION

Purified human eosinophils, AML14.3D10 cells and cultured mast cells secrete IL-4 with a pattern similar to that found in basophils when stimulated with a panel of reactive and unreactive lectins. The lectin SNA induces IL-4 secretion from mast cells and basophils, but not from eosinophils or AML14.3D10. Eosinophils appear to secrete only pre-formed IL-4, whereas mast cells may synthesize IL-4 on ligation with the lectin LCA. Lectins that agglutinate the granulocytes investigated do not necessarily induce secretion of IL-4. Lectins that elicit secretion of IL-4 bind more to eosinophils than unreactive lectins as determined by flow cytometry and lectin blotting of SDS gels.

CONCLUSION

As granulocytes with functions related to that of basophils, eosinophils, AML14.3D10 and cultured mast cells respond to stimulation with lectins similarly to basophils. This emphasizes the possibility that eosinophils and mast cells may be linked in their cellular heritage as the cellular partners, and lectins as ligands, may contribute to the maintenance of a Th2-favoured microenvironment that is thought to underlie the allergic march.

Immunomodulation during sublingual therapy in allergic children

The clinical efficacy of sublingual immunotherapy (SLIT) has been demonstrated, but its mechanism of action is still controversial. The most recent experimental observations suggest that a critical role in the modulation of immune response is sustained by Th2 cytokines, such as interleukin-4 (IL-4), IL-5 and IL-13, by co-stimulatory molecules, such as CD40 on B cells, and by hormones and neuropeptides. To better understand whether SLIT affects immune responses we used a double-blind placebo-controlled design. Eighty-six children with mild asthma due to allergy to Dermatophagoides pteronyssinus (33 of whom also had rhinoconjunctivitis) were randomly assigned SLIT (n = 47) or placebo (n = 39). We assessed symptom scores using diary cards of each patient and determined the expression of CD40 on B cells and the serum concentration of ECP, IL-13, prolactin (PRL) and ACTH at enrolment and after 6 months of therapy. We observed a significant reduction in asthma and rhinitis scores in the immunotherapy group compared with the placebo group, no variation in CD40 and ACTH, but a significant decrease in ECP, IL-13 and PRL after 6 months of therapy (p <0.01). Our results confirm the efficacy and safety of SLIT, and lead us to believe that it could modulate the synthesis of Th2 cytokines, as revealed from the decrease of IL-13. In addition, the reduction of PRL might be a signal of reduced activation of T lymphocytes.

Molecular characterization of an interleukin-4-inducing factor from Schistosoma mansoni eggs

The eggs of the parasitic trematode Schistosoma mansoni are powerful inducers of a T helper type 2 (Th2) immune response and immunoglobulin E (IgE) production. S. mansoni egg extract (SmEA) stimulates human basophils to rapidly release large amounts of interleukin (IL)-4, the key promoter of a Th2 response. Here we show purification and sequence of the IL-4-inducing principle of S. mansoni eggs (IPSE). Stimulation studies with human basophils using SmEA fractions and natural and recombinant IPSE as well as neutralization and immunodepletion studies using antibodies to recombinant IPSE demonstrate that IPSE is the bioactive principle in SmEA leading to activation of basophils and to expression of IL-4 and IL-13. Regarding the mechanism of action, blot analysis showed that IPSE is an IgE-binding factor, suggesting that it becomes effective via cross-linking receptor-bound IgE on basophils. Immunohistology revealed that IPSE is enriched in and secreted from the subshell area of the schistosome egg. We conclude from these data that IPSE may be an important parasite-derived component for skewing the immune response toward Th2.

Enhanced interleukin-4 production in CD4+ T cells and elevated immunoglobulin E levels in antigen-primed mice by bisphenol A and nonylphenol, endocrine disruptors: involvement of nuclear factor-AT and Ca2+

Bisphenol A (BPA) and p-nonylphenol (NP) are representative endocrine disruptors (EDs) that may have adverse effects on human health. The influence of these compounds on allergic immune responses remains unclear. In this study, we have examined the effects of BPA and NP on production of interleukin-4 (IL-4), a pro-inflammatory cytokine closely associated with allergic immune responses. Both BPA and NP significantly enhanced IL-4 production in keyhole limpet haemocyanin (KLH)-primed CD4+ T cells in a concentration-dependent manner. Treatment with BPA or NP in vivo resulted in significant increase of IL-4 production in CD4+ T cells and of antigen-specific immunoglobulin E (IgE) levels in the sera of KLH-primed mice. Furthermore, BPA and NP enhanced the activation of IL-4 gene promoter in EL4 T cells transiently transfected with IL-4 promoter/reporter constructs, and the enhancing effect mapped to a region in the IL-4 promoter containing binding sites for nuclear factor (NF)-AT. Activation of T lymphocytes by phorbol 12-myristate 13-acetate/ionomycin resulted in markedly enhanced binding activities to the NF-AT site, which significantly increased upon addition of BPA or NP, as demonstrated by the electrophoretic mobility shift assay, indicating that the transcription factor NF-AT was involved in the enhancing effect of BPA and NP on IL-4 production. The enhancement of IL-4 production by BPA or NP was significantly reduced by nitrendipine, a blocker of Ca2+ influx, and by FK506, a calcineurin inhibitor. FK506 inhibited the NF-AT-DNA binding activity and IL-4 gene promoter activity enhanced by BPA or NP. These results represent the first report describing possible enhancement of allergic response by EDs through increasing IL-4 production in CD4+ T cells and antigen-specific IgE levels in the sera via the stimulation of Ca2+/calcineurin-dependent NF-AT activation.

Structural and functional properties of IL-4delta2, an alternative splice variant of human IL-4

Structural and functional properties of recombinant IL-4delta2, a naturally occurring splice variant of human IL-4 with a deletion of the loop region 22-37, have been analyzed. IL-4delta2 has alpha-helical structure and most likely preserves the "up-up-down-down" topology typical of the four-helix-bundle cytokines. IL-4delta2 interacts specifically with the alpha chain of IL-4R and competes effectively with IL-4 for the common binding sites. Thus, IL-4delta2 may act as a regulator of the cytokine net, being the natural antagonist of IL-4.

Basophils express a type 2 cytokine profile on exposure to proteases from helminths and house dust mites

The proteolytic activities frequently associated with sources of allergens and parasite secretions have been suggested as important immunomodulators. We have investigated whether the protease activity of the house dust mite allergen Der p1 and the secreted proteases of the hookworm Necator americanus are able to directly induce type 2 cytokine production by basophils. Der p1 and the secretions of N. americanus induced interleukin (IL)-4, IL-5, and IL-13 but not interferon-gamma mRNA in KU812 basophils. Enzyme-linked immunosorbent assay confirmed that IL-4 and IL-13 were secreted. A nonproteolytic antigen failed to induce cytokine expression, and preincubation of Der p1 or N. americanus secretions with protease inhibitors inhibited cytokine expression. Data were confirmed using basophils purified from human peripheral blood. We speculate that this innate mechanism may contribute to the development of a cytokine milieu that could promote immunoglobulin E synthesis, eosinophil recruitment, and the development of type 2 T cells.

Interleukin-4 receptor alpha chain and STAT6 signaling inhibit gamma interferon but not Th2 cytokine expression within schistosome granulomas

Compared to wild-type (WT) mice, schistosome granulomas in Stat6 knockout (KO) mice lacked eosinophils and had Th1 features. Interleukin-4 (IL-4) acts through Stat6 in assisting Th2 cell development. The importance of Stat6 for Th2-cell development within schistosome granulomas had not been explored. Therefore we studied gamma interferon (IFN-gamma), IL-4, and IL-5 production in granulomas from Stat6 KO and WT mice. Dispersed granuloma cells from Stat6 KO and WT mice made similar amounts of IL-4 and IL-5. Only Stat6 KO granuloma cells released IFN-gamma. Granuloma T cells contained most of the IL-4, IL-5, and IFN-gamma mRNA and secreted these cytokines. In Stat6 KO mice, 16.6% of the granuloma cells were CD4(+). Of these, 10.7% stained for IFN-gamma and/or IL-4 by intracytoplasmic flow analysis. Few CD4(-) T cells stained positively. The IL-4-producing T cells did not stain for DX5 or with labeled alpha-GalCer CD1d tetramer, suggesting an absence of NK T cells. Thus, conventional Th cells in Stat6 KO granulomas produce IFN-gamma and Th2 cytokines. Stat6 limits IFN-gamma production but is unnecessary for Th2-cell development or localization within the granuloma.

Hydroquinone, a reactive metabolite of benzene, enhances interleukin-4 production in CD4+ T cells and increases immunoglobulin E levels in antigen-primed mice

Exposure to cigarette smoke is known to increase the risk of the development of allergic disease. The mechanism is not well understood. In this study, we determined the effect of hydroquinone (HQ), a major metabolite of benzene present in large quantities in cigarette tar, on interleukin-4 (IL-4) production by CD4+ T cells. HQ significantly enhanced IL-4 production by keyhole limpet haemocyanin (KLH)-primed CD4+ T cells in a dose-dependent manner. The enhancing effect of HQ on IL-4 production was maximal at a concentration of 50 micro m. It increased the level of IL-4 production approximately 10-fold. HQ enhanced IL-4 mRNA expression and also IL-4 gene promoter activity, suggesting that the enhancing effect of HQ on IL-4 production may occur at the transcriptional level. Furthermore, the injection of KLH-primed mice with HQ resulted in a significant increase in the levels of IL-4 and immunoglobulin E. These findings provide evidence that HQ, a major component of cigarette tar, may enhance allergic immune responses by inducing the production of IL-4 in CD4+ T cells.

Local allergic reaction in food-hypersensitive adults despite a lack of systemic food-specific IgE

BACKGROUND

Objective tools are lacking for the diagnosis of local gastrointestinal inflammatory reactions in skin prick test (SPT)-negative and serum IgE antibody (s-IgE Ab)-negative patients with suspected food allergy.

OBJECTIVE

The purpose of this investigation was to evaluate the presence of eosinophils, T cells, local IgE-bearing cells, IL-4, and IFN-gamma in small intestinal biopsy specimens from adult SPT-negative/s-IgE Ab-negative patients with food allergy during symptomatic and nonsymptomatic periods.

METHODS

Fourteen patients with food allergy-related gastrointestinal symptoms confirmed by double-blinded, placebo-controlled food challenge (DBPCFC) were investigated. Eleven of the patients were SPT-negative and s-IgE Ab-negative. Sex- and age-matched healthy volunteers were used as controls. Duodenal biopsies were studied with immunostaining through use of a panel of mouse monoclonal antibodies specific for eosinophils, CD3, CD4, CD8, IgE, IL-4, and IFN-gamma.

RESULTS

Significant increases in numbers of MBP+ eosinophils, IgE-bearing cells, and T cells were found in the duodenal mucosa of the patients when they were symptomatic in comparison with when they were asymptomatic and in comparison with healthy controls. Numbers of IL-4+ cells were increased and numbers of IFN-gamma+ cells were reduced in the patients when they were symptomatic in comparison with when they were asymptomatic and in comparison with the controls. There were no differences in total s-IgE levels between any of the groups.

CONCLUSION

A significant correlation was found between the appearance of symptoms of food hypersensitivity and the duodenal presence of IgE-bearing cells, activated eosinophils, and T cells in patients with negative SPT results and negative s-IgE Ab to the offending food. We suggest that a localized IgE-mediated response caused the gastrointestinal symptoms seen in these patients.

Induction of a proliferative response of T cells by a high-molecular antigen in Dermatophagoides farinae feces

BACKGROUND

We have previously demonstrated that high-molecular mite antigen (HM1) from Dermatophagoides farinae feces is an allergen which binds to mite-allergic patients IgE. HM1 also induced a proliferative response in lymph node cells from mite-immunized mice as well as nonimmunized mice. In the present study, we demonstrated that HM1 induced T cell proliferation and investigated the HM1-stimulated T cell proliferative pathways using nonallergic human peripheral blood mononuclear cells (PMBC).

METHODS

Blood samples were obtained from 10 healthy donors. Using primary culture, T cell response stimulated with HM1 was performed on purified T cells, CD19+ cell-depleted PBMC and CD11b+ cell-depleted PBMC. In addition, interleukin (IL)-5 and interferon (IFN)-gamma produced by mite-allergic and healthy donors stimulated with HM1 were estimated by enzyme immunoassay.

RESULTS

T cell proliferation was detected only in CD19+ cell-depleted PBMC. When T cells were cocultured with CD11b+ cells they recovered their proliferative response to HM1. In addition, the pathway of HM1-stimulated T cell proliferation did not involve HLA class II restriction. Both activated CD11b+ cells and their conditioned media were needed to induce HM1-stimulated T cell proliferation. Furthermore, HM1 induced IFN-gamma production in both healthy and allergic donors.

CONCLUSION

The high-molecular mite antigen, HM1, induced a proliferative response of T cells in healthy as well as allergic donors, without HLA class II restriction. Our results suggest that further investigation of HM1 could constitute a valuable avenue of research into complex allergic diseases.