IgE-mediated Allergic Inflammation Research Articles

Association between Type 2 Diabetes, Obesity and Key Immunological Components of IgE-mediated Inflammation.

Changes in lifestyle and obesity in recent decades have brought about a dramatic increase in type 2 diabetes mellitus (DM2) and allergic diseases. Clinical and epidemiological studies associate obesity with epidemics of allergic diseases. The link between obesity and DM2 with immunological components of IgE-mediated allergic inflammation is not yet conclusively established. To examine the key immunological components of IgE-mediated allergic inflammation in patients with DM2 and their relationship with glycemic control and anthropometric indicators. Fifty-five patients with DM2 and 32 healthy controls with normal weight and body mass index (BMI) of 18-24.9 kg/m2 were included in the study. Th2-cytokine profile (serum levels of IL-4 and IL-5, pg/ml) and total serum IgE IU/ml were assessed in all participants in the study using ELISA. In patients with DM2, levels of glycated hemoglobin (HbA1c%) in the blood were also measured. Serum levels of IL-4 and IL-5 are significantly higher in patients with DM2 compared to the control group. Serum levels of IL-4 and IL-5 positively correlated with BMI as well as serum levels of IL-4 with waist circumference. Total serum IgE positively correlated with HbA1c. Obesity and poor glycemic control in patients with DM2 affect key immunological components of IgE-mediated allergic inflammation and possibly alter the immune response to allergens and antigens.

Basophils require interaction with CD49b(+)/c-kit(+) cells through L-selectin for induction of IgE-mediated chronic allergic inflammation

Basophils require interaction with CD49b(+)/c-kit(+) cells through L-selectin for induction of IgE-mediated chronic allergic inflammation

Allerjik Rinit Tanı ve Tedavisindeki Yenilikler

Allergic rhinitis (AR) is one of the most common chronic diseases in all age groups. It is an IgE-mediated allergic inflammation of the nasal airways and is characterized by sneezing, swelling and inflammation of the nasal mucosa as well as itchy and watery eyes. It is a global health problem and a burdensome disorder affecting many people from childhood to adulthood. The prevalence of childhood AR shows wide variation throughout the world, ranging from 0.8 to 45%. The prevalence rates for different regions of Turkey ranges from 2.9 to 44%. The aim of the present review is to provide an update on AR treatment and diagnosis. Because of its burden on patient’s lives and its impact on asthma, AR should be taken care of properly with effective and safe treatments. Second-generation antihistamines and intranasal steroids represent the milestone of AR therapy. New formulations of available drugs (rupatadine oral solution, ebastine fast-dissolving tablets, combination of intranasal fluticasone propionate and azelastine hydrochloride), recently discovered molecules (ciclesonide, bilastine, roflumilast, etc.), immunologic targets (omalizumab) and unconventional treatments (homeopathic treatments) are representing new frontiers in AR management. An accurate diagnosis of AR is also crucial to increase treatment success. Further promising improvements in diagnostics are expected from recombinant allergen diagnostics identifying particular molecules of risk. Purified native or recombinant allergens, identifying the individual molecules to which patients are sensitized, can be determined by molecular or component resolved diagnostics. These may decrease the need for provocation testing and improve the specificity of allergen immunotherapy. Different methods to measure nasal nitric oxide (nNO) levels are currently being revealed. Decreased nNO concentration is also typical of cystic fibrosis, even though nNO is not as low as in primary ciliary dyskinesia. The clinical utility of nNO remains to be established in upper airway disorders such as AR.

Epidermal Neuromedin U Attenuates IgE-Mediated Allergic Skin Inflammation.

Although keratinocyte-derived neuropeptide neuromedin U (NMU) mediates the proinflammatory effects of innate-type mast cell activation, no information is available on the physiological roles. Here, to investigate the effects of NMU on IgE-mediated allergic skin inflammation, we determined whether IgE-mediated inflammation associated with severe scratching was induced in Nmu-/- mice administered repeated hapten applications to the ear or footpad. Dry skin was induced by targeted deletion of Nmu. Mice administered repeated hapten application developed IgE-mediated allergic inflammation characterized by severe scratching and increased serum IgE levels only when the ear, and not the footpad, was subjected to scratching, indicating that depletion of NMU from the epidermis alone does not drive such allergic inflammation. Thus, the susceptibility of Nmu-/- mice to allergic inflammation depends primarily on scratching dry skin. Further, allergic skin inflammation mediated by FcεRI cross-linking in Nmu-/-mice was inhibited by prior injection of NMU. These results indicate that NMU plays an important physiological role as a negative regulator during the late stage of IgE-mediated allergic skin inflammation.

Atopic dermatitis in older adults: A viewpoint from geriatric dermatology.

Atopic dermatitis (AD) in older adults represents a newly defined subgroup of AD. The prevalence of elderly AD is approximately 1-3% among elderly populations in industrialized countries. Elderly patients with AD show some common clinical characteristics, such as a male predominance, a lower incidence of lichenified eczema at the elbow and knee folds, and particular patterns of onset and clinical course. Both immunoglobulin (Ig)E-allergic and non-IgE-allergic types are observed in elderly AD. Elderly patients with IgE-allergic AD show high rates of positivity for specific IgE antibodies against house dust mites, associations with IgE allergic and asthmatic complications, histopathological features with a predominance of IgE-mediated allergic inflammation in the lesional skin, and a significantly lower incidence of malignancy as compared with control subjects. The etiology of elderly AD might be associated with immunosenescence, age-related changes to the sex hormone milieu, age-related barrier dysfunctions in the skin and gut, functional disturbance of sweat production, and environmental stimuli in the lifestyle of elderly individuals. Powerful anti-inflammatory treatments, such as oral corticosteroids, might be required together with standard treatments to manage moderate to severe cases of elderly AD. Finally, most elderly patients with AD reach the end of life with this disease, which should now be considered a lifelong allergic disease.

An Exploratory Pilot Study of Genetic Marker for IgE-Mediated Allergic Diseases with Expressions of FcεR1α and Cε.

The high affinity immunoglobulin E (IgE) receptor-FcεR1 is mainly expressed on the surface of effector cells. Cross-linking of IgE Abs bound to FcεR1 by multi-valent antigens can induce the activation of these cells and the secretion of inflammatory mediators. Since FcεR1 plays a central role in the induction and maintenance of allergic responses, this study aimed to investigate the association of FcεR1 with the allergic phenotype of Cε expression and cytokine and histamine release from peripheral leukocytes. Peripheral leukocytes from 67 allergic and 50 non-allergic subjects were used for genotyping analysis. Peripheral mononuclear cells (PBMCs) were used for Cε expression and ELISpot analysis, while polymorphonuclear cells (PMNs) were used for histamine release. The association between genotype polymorphism of the FcεR1α promoter region (rs2427827 and rs2251746) and allergic features of Cε expression and histamine were analyzed, and their effects on leukocytes function were compared with wild type. The genotype polymorphisms of FcεR1α promoter region with CT and TT in rs2427827 and TC in rs2251746 were significantly higher in allergic patients than in non-allergic controls. Patients with single nucleotide polymorphism (SNP) of FcεR1α promoter region had high levels of total IgE, mite-specific Der p 2 (Group 2 allergen of Dermatophagoides pteronyssinus)-specific IgE and IgE secretion B cells. The mRNA expression of FcεR1α was significantly increased after Der p2 stimulation in PBMCs with SNPs of the FcεR1α promoter region. Despite the increased Cε mRNA expression in PBMCs and histamine release from PMNs and the up-regulated mRNA expression of interleukin (IL)-6 and IL-8 secretions after Der p2 stimulation, there was no statistically significant difference between SNPs of the FcεR1α promoter region and the wild type. SNPs of FcεR1α promoter region were associated with IgE expression, IgE producing B cells, and increased Der p2-induced FcεR1α mRNA expression. These SNPs may be used as a disease marker for IgE-mediated allergic inflammation caused by Dermatophagoides pteronyssinus.

Persistence of IgE-associated allergy and allergen-specific IgE despite CD4+ T cell loss in AIDS.

The infection of CD4+ cells by HIV leads to the progressive destruction of CD4+ T lymphocytes and, after a severe reduction of CD4+ cells, to AIDS. The aim of the study was to investigate whether HIV-infected patients with CD4 cell counts <200 cells/µl can suffer from symptoms of IgE-mediated allergy, produce allergen-specific IgE antibody responses and show boosts of allergen-specific IgE production. HIV-infected patients with CD4 counts ≤200 cells/µl suffering from AIDS and from IgE-mediated allergy were studied. Allergy was diagnosed according to case history, physical examination, skin prick testing (SPT), and serological analyses including allergen microarrays. HIV infection was confirmed serologically and the disease was staged clinically. The predominant allergic symptoms in the studied patients were acute allergic rhinitis (73%) followed by asthma (27%) due to IgE-mediated mast cell activation whereas no late phase allergic symptoms such as atopic dermatitis, a mainly T cell-mediated skin manifestation, were found in patients suffering from AIDS. According to IgE serology allergies to house dust mites and grass pollen were most common besides IgE sensitizations to various food allergens. Interestingly, pollen allergen-specific IgE antibody levels in the patients with AIDS and in additional ten IgE-sensitized patients with HIV infections and low CD4 counts appeared to be boosted by seasonal allergen exposure and were not associated with CD4 counts. Our results indicate that secondary allergen-specific IgE production and IgE-mediated allergic inflammation do not require a fully functional CD4+ T lymphocyte repertoire.

α(1,3) Fucosyltransferases IV and VII Are Essential for the Initial Recruitment of Basophils in Chronic Allergic Inflammation

Basophils act as initiator cells for the development of IgE-mediated chronic allergic inflammation (IgE-CAI). However, detailed mechanisms of initial recruitment of basophils into the skin have yet to be clarified. Selectins mediate leukocyte capture and rolling on the vascular endothelium for extravasation. Counter-receptor activity of selectins is regulated by α(1, 3) fucosyltransferases (FTs) IV and VII. To clarify the contribution of selectin ligands regulated by FTs for initial basophil recruitment, IgE-CAI was induced in mice deficient in FT-IV and/or FT-VII genes. Although FT-IV(-/-) and FT-VII(-/-) mice exhibited comparable skin responses to wild-type mice, the FT-IV(-/-)/FT-VII(-/-) mice showed significantly impaired inflammation. Although the transfer of basophils to FcRγ(-/-) mice induced IgE-CAI, this induction was completely absent when basophils from FT-IV(-/-)/FT-VII(-/-) mice were transferred. L-selectin, but not P- and E-selectin, blocking Abs inhibited skin inflammation in vivo. P-selectin glycoprotein-1 (PSGL-1) antibody also ameliorated skin inflammation, and basophils were bound to L-selectin in a PSGL-1-dependent manner, which was regulated by FT-IV/VII. Functional PSGL-1 generated by basophil FT-IV/VII and its subsequent binding to L-selectin could be one of the essential steps required for initial basophil recruitment and the development of IgE-CAI in mice.

The basophil: Resolved questions and new avenues of investigation

The contribution that the subset of leukocytes known as basophils makes to immunity is controversial. A clear picture of the function of basophils has been slow to emerge, mainly due to functional studies on basophils in vivo being hampered by limitations in reagent availability and specificity. These issues were discussed by Schwartz and Voehringer in the June 2011 issue of BioEssays 1. The authors speculated that many outstanding issues surrounding basophil function would soon be resolved following recent development of specific means to delete and track basophils in vivo. Indeed, in subsequent months more definitive determination of basophil function has emerged using these tools. Thus, we here provide a brief update on the function of basophils in immunity. Whether basophils serve as antigen-presenting cells (APCs) that prime TH2 cell responses, the T cell subset controlling allergic and anti-parasitic immunity, was controversial 1. Sullivan and colleagues demonstrated that basophils do not play an essential role in the priming of TH2 cells following Schistosoma mansoni egg infection or in the papain-induced model of allergy 2. Moreover, their data revealed that basophils do not form stable conjugates with antigen-specific T cells, a prerequisite for an effective APC. The same study addressed another controversy pertaining to the function of basophils as effector cells in host defense against parasites. It was demonstrated that basophils provide a non-redundant source of IL-4 in infected tissues, which, in collaboration with T cell-derived IL-4, mediated worm expulsion following Nippostrongylus brasiliensis infection 2. Thus, a picture is now emerging whereby anti-parasitic immunity is not reliant on basophils as APCs, but requires cooperative responses between basophils and CD4+ T cells as effector cells. One explanation for discrepancies regarding reported functions of basophils may also be explained by recent findings demonstrating significant heterogeneity in basophils. Whilst IL-3 has long been considered the critical factor mediating basophil differentiation, recent studies have identified a novel function for the cytokine thymic stromal lymphopoetin (TSLP), which drives production of basophils distinct from those reliant on IL-3 3, 4. These studies further demonstrated that peripheral basophillia in murine models of atopic dermatitis and Trichinella spiralis infection are TSLP-dependent and can occur in the presence or absence of IL-3, raising the question of whether specific subtypes of basophils mediate distinct responses. Basophils have also been implicated as important effector cells driving pathogenesis of IgE-mediated chronic allergic inflammation (IgE-CAI) of the skin. However, recent work using new genetic tools to delete basophils surprisingly identified an anti-inflammatory role of basophils in this setting. Egawa et al. 5 demonstrated that basophils promoted differentiation of inflammatory monocytes into anti-inflammatory M2 macrophages rather than typical inflammatory M1 macrophages. Basophil-induced M2 macrophage differentiation subsequently dampened allergic inflammation during IgE-CAI. Thus, an intriguing possibility now emerges that basophils function as important regulators of macrophage differentiation in a range of inflammatory settings, which could have important implications for treatment in various inflammatory pathologies. Thus, as the important questions regarding the function of basophils in mice begin to be definitively addressed with novel genetic tools, new questions arise. Are there subsets of basophils yet to be identified that are capable of acting as APCs? Does boosting basophil responses provide a means to control macrophage-driven inflammation? Finally, and crucially, do these findings with regard to basophils in murine experimental models accurately reflect the functional significance of basophils in humans?

Novel Basophil- or Eosinophil-Depleted Mouse Models for Functional Analyses of Allergic Inflammation

Basophils and eosinophils play important roles in various host defense mechanisms but also act as harmful effectors in allergic disorders. We generated novel basophil- and eosinophil-depletion mouse models by introducing the human diphtheria toxin (DT) receptor gene under the control of the mouse CD203c and the eosinophil peroxidase promoter, respectively, to study the critical roles of these cells in the immunological response. These mice exhibited selective depletion of the target cells upon DT administration. In the basophil-depletion model, DT administration attenuated a drop in body temperature in IgG-mediated systemic anaphylaxis in a dose-dependent manner and almost completely abolished the development of ear swelling in IgE-mediated chronic allergic inflammation (IgE-CAI), a typical skin swelling reaction with massive eosinophil infiltration. In contrast, in the eosinophil-depletion model, DT administration ameliorated the ear swelling in IgE-CAI whether DT was administered before, simultaneously, or after, antigen challenge, with significantly lower numbers of eosinophils infiltrating into the swelling site. These results confirm that basophils and eosinophils act as the initiator and the effector, respectively, in IgE-CAI. In addition, antibody array analysis suggested that eotaxin-2 is a principal chemokine that attracts proinflammatory cells, leading to chronic allergic inflammation. Thus, the two mouse models established in this study are potentially useful and powerful tools for studying the in vivo roles of basophils and eosinophils. The combination of basophil- and eosinophil-depletion mouse models provides a new approach to understanding the complicated mechanism of allergic inflammation in conditions such as atopic dermatitis and asthma.

Basophil-derived mouse mast cell protease 11 is involved in the development of IgE-mediated chronic allergic inflammation

Event Abstract Back to Event Basophil-derived mouse mast cell protease 11 is involved in the development of IgE-mediated chronic allergic inflammation Hayato DEKI1, Yohei KAWANO1, Soichro YOSHIKAWA1, Mayumi EGAWA1, Misako IKI1 and Hajime KARASUYAMA1* 1 Tokyo Medical and Dental University, Japan Basophils are the least common granulocytes, and had long been considered as minor relatives of mast cells. However, recent studies have illustrated non-redundant roles for basophils in various immune responses, including allergic reactions and protective immunity against parasites. We previously demonstrated that basophils but not mast cells play an important role in the development of IgE-mediated, delayed-onset allergic inflammation in the skin, designated IgE-CAI. However, it remains elusive how basophils trigger the skin inflammation. In this study, we focused on mast cell protease 11 (mMCP-11) that shows a tryptase activity, and is expressed by basophils rather than mast cells. In order to elucidate the role for mMCP-11 in IgE-CAI, we generated engineered mice deficient for mMCP-11, in that the number of basophils was comparable to that in wild-type mice. Their basophils expressed normal levels of other proteases including mMCP-8 and surface FcεRI, and normally degranulated upon stimulation with IgE plus antigens, as judged by β-hexosaminidase release assay. Of note, skin swelling elicited by the IgE-CAI reaction was reduced in mMCP-11-deficient mice to half of that in wild-type mice. Moreover, the number of proinflammatory cells accumulating skin lesions, including eosinophils and neutrophils, was significantly reduced in mMCP-11-deficient mice. Thus, mMCP-11 released by basophils is a key effector molecule in the development of IgE-CAI. Keywords: basophil, mMCP-11, allergic inflammation, IgE, Tryptases Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Adaptive Immunity Citation: DEKI H, KAWANO Y, YOSHIKAWA S, EGAWA M, IKI M and KARASUYAMA H (2013). Basophil-derived mouse mast cell protease 11 is involved in the development of IgE-mediated chronic allergic inflammation. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00356 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Mar 2013; Published Online: 22 Aug 2013. * Correspondence: Prof. Hajime KARASUYAMA, Tokyo Medical and Dental University, Tokyo, Japan, karasuyama.mbch@tmd.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Hayato DEKI Yohei KAWANO Soichro YOSHIKAWA Mayumi EGAWA Misako IKI Hajime KARASUYAMA Google Hayato DEKI Yohei KAWANO Soichro YOSHIKAWA Mayumi EGAWA Misako IKI Hajime KARASUYAMA Google Scholar Hayato DEKI Yohei KAWANO Soichro YOSHIKAWA Mayumi EGAWA Misako IKI Hajime KARASUYAMA PubMed Hayato DEKI Yohei KAWANO Soichro YOSHIKAWA Mayumi EGAWA Misako IKI Hajime KARASUYAMA Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Determination of allergen specificity by heavy chains in grass pollen allergen–specific IgE antibodies

Affinity and clonality of allergen-specific IgE antibodies are important determinants for the magnitude of IgE-mediated allergic inflammation. We sought to analyze the contribution of heavy and light chains of human allergen-specific IgE antibodies for allergen specificity and to test whether promiscuous pairing of heavy and light chains with different allergen specificity allows binding and might affect affinity. Ten IgE Fabs specific for 3 non-cross-reactive major timothy grass pollen allergens (Phl p 1, Phl p 2, and Phl p 5) obtained by means of combinatorial cloning from patients with grass pollen allergy were used to construct stable recombinant single chain variable fragments (ScFvs) representing the original Fabs and shuffled ScFvs in which heavy chains were recombined with light chains from IgE Fabs with specificity for other allergens by using the pCANTAB 5 E expression system. Possible ancestor genes for the heavy chain and light chain variable region-encoding genes were determined by using sequence comparison with the ImMunoGeneTics database, and their chromosomal locations were determined. Recombinant ScFvs were tested for allergen specificity and epitope recognition by means of direct and sandwich ELISA, and affinity by using surface plasmon resonance experiments. The shuffling experiments demonstrate that promiscuous pairing of heavy and light chains is possible and maintains allergen specificity, which is mainly determined by the heavy chains. ScFvs consisting of different heavy and light chains exhibited different affinities and even epitope specificity for the corresponding allergen. Our results indicate that allergen specificity of allergen-specific IgE is mainly determined by the heavy chains. Different heavy and light chain pairings in allergen-specific IgE antibodies affect affinity and epitope specificity and thus might influence clinical reactivity to allergens.

Generation and characterization of mouse basophils from bone marrow and purification of basophils from spleen.

Basophils are rare circulating granulocytes that originate from progenitor cells in the bone marrow and have been considered important effector cells in IgE-mediated allergic inflammation. Basophils constitute <1% of blood leukocytes and are usually absent or present only in small numbers in tissues. They may, however, be recruited to inflammatory sites when an antigen is present and contribute immediately to hypersensitivity reactions. Basophils can therefore serve as primary effector cells in allergic disorders. Despite a large pool of experimental evidence that has led to the discovery of these functional attributes of basophils, many questions regarding their contribution to these immune responses remain unanswered. This is due, in part, to the lack of methods for generation and purification of basophils and the lack of animal models appropriate for their functional analysis. Recent studies, however, have revealed a role for basophils as antigen-presenting cells that preferentially induce Th2 cells in response to complexes of antigen plus antigen-specific IgE, to protease allergens, or to helminth parasites in vitro and in vivo through the production of "early IL-4" and the presentation to CD4(+) T cells of complexes of peptide plus MHC class II molecules. These findings have uncovered previously unknown functional characteristics of basophils. Knowledge of these and other functional properties of basophils may translate into the design of novel therapeutic strategies for Th2-IgE-mediated diseases, such as bronchial asthma. In this unit, protocols that will enable the study of mouse basophils are described.

Critical role of P1-Runx1 in mouse basophil development

AbstractRunx1P1N/P1N mice are deficient in the transcription factor distal promoter-derived Runt-related transcription factor 1 (P1-Runx1) and have a > 90% reduction in the numbers of basophils in the BM, spleen, and blood. In contrast, Runx1P1N/P1N mice have normal numbers of the other granulocytes (neutrophils and eosinophils). Although basophils and mast cells share some common features, Runx1P1N/P1N mice have normal numbers of mast cells in multiple tissues. Runx1P1N/P1N mice fail to develop a basophil-dependent reaction, IgE-mediated chronic allergic inflammation of the skin, but respond normally when tested for IgE- and mast cell–dependent passive cutaneous anaphylaxis in vivo or IgE-dependent mast cell degranulation in vitro. These results demonstrate that Runx1P1N/P1N mice exhibit markedly impaired function of basophils, but not mast cells. Infection with the parasite Strongyloides venezuelensis and injections of IL-3, each of which induces marked basophilia in wild-type mice, also induce modest expansions of the very small populations of basophils in Runx1P1N/P1N mice. Finally, Runx1P1N/P1N mice have normal numbers of the granulocyte progenitor cells, SN-Flk2+/−, which can give rise to all granulocytes, but exhibit a > 95% reduction in basophil progenitors. The results of the present study suggest that P1-Runx1 is critical for a stage of basophil development between SN-Flk2+/− cells and basophil progenitors.

Role of Mast Cells and Basophils in IgE Responses and in Allergic Airway Hyperresponsiveness

We established a diphtheria toxin (DT)-based conditional deletion system using Il4 enhancer elements previously shown to be specific for IL-4 production in mast cells (MCs) or basophils (Mas-TRECK and Bas-TRECK mice). DT treatment of Bas-TRECK mice resulted in specific deletion of basophils, whereas both MCs and basophils were deleted in Mas-TRECK mice. DT-treated Mas-TRECK mice had impaired passive cutaneous anaphylaxis, IgE-mediated passive systemic anaphylaxis, and IgE-mediated chronic allergic inflammation, whereas DT-treated Bas-TRECK mice had impaired IgE-mediated chronic allergic inflammation. Using these mice, we also sought to tease out the role of MCs and basophils in airway hyperresponsiveness (AHR). Although MC deletion resulted in a slight increase in basal Ag-specific IgE levels and significant increases in basal IgE levels, we found that this deletion markedly impaired the AHR effector phase and was accompanied by decreased histamine levels. By contrast, basophil deletion had no effect on the AHR effector phase or on IgE production induced by systemic OVA immunization. Our results, using these newly established Mas-TRECK and Bas-TRECK models, demonstrated an indispensable role for MCs as effector cells in AHR.

IgE-mediated Chronic Allergic Inflammation (IgE-CAI)

This system is one of a chronic allergic inflammation model. A single subcutaneous injection of antigens elicits a delayed-type response manifested by ear swelling. The entire response consists of three phases: Immediate, late, and chronic. The early-phase swelling peak within 1 h after allergen challenge is followed by the late-phase swelling 6-10 h late. Importantly, the ear swelling at the late-phase started on day2 and peak on day4. This late-phase ear swelling response is defined as IgE-mediated chronic allergic inflammation (IgE-CAI) and mainly regulated by basophils.

Distinct roles of prostaglandin D2 receptors in chronic skin inflammation

Prostaglandin D2 (PGD2) is a prostanoid implicated in allergic inflammation. However, the roles of PGD2 in immune and allergic responses remain controversial. PGD2 exerts its effect through the CRTH2 and DP receptors. To elucidate functional differences of PGD2 and its receptors in chronic skin inflammation, chronic contact hypersensitivity (chronic CHS) and IgE-mediated chronic allergic skin inflammation (IgE-CAI) were induced in mice deficient in the CRTH2 and/or DP genes. DP (−/−) mice and CRTH2 (−/−)/DP (−/−) mice showed exacerbated chronic CHS, and conversely, CRTH2 (−/−) mice exhibited diminished skin responses. Skin responses correlated with local levels of IL-13, CCL11, and CCL22. These phenotypic changes in chronic CHS of mutant mice were similar to those in acute CHS despite the differences in the cytokine milieus; chronic CHS and acute CHS were mediated by Th2 and Th1/Th17 immunity, respectively. However, in IgE-CAI, DP (−/−) mice showed comparable skin responses to wild-type mice. Alleviation of IgE-CAI was observed in CRTH2 (−/−) mice, and as a consequence, CRTH2 (−/−)/DP (−/−) mice exhibited diminished IgE-CAI compared with wild-type mice. IgE-CAI in mutant mice correlated with local IL-4 and CCL22 production. Consistent with these results, a CRTH2-specific antagonist exerted inhibitory effects in both chronic CHS and IgE-CAI. The present study demonstrates that functional roles of PGD2 and its receptors appear to depend on the nature of the inflammation. Nevertheless, tools targeted against PGD2-CRTH2 signals could offer therapeutic potential for both types of chronic skin inflammation.

NK Cell-Depleting Anti-Asialo GM1 Antibody Exhibits a Lethal Off-Target Effect on Basophils In Vivo

NK cells are innate immune lymphocytes and play a key role in both innate and adaptive immunity. Their pivotal functions in vivo have been illustrated in mice by means of their ablation with NK cell-depleting Abs, particularly anti-asialo GM1 (ASGM1). In this study, we show that the whole population of basophils constitutively expresses ASGM1 as well as CD49b (DX5) as does the NK cell population and was ablated in vivo by anti-ASGM1 as efficiently as by a basophil-depleting anti-FcεRIα Ab. Anti-ASGM1-mediated basophil depletion was operative as for NK cell depletion in various mouse strains, irrespective of NK1 allotype and MHC H2 haplotype, including C57BL/6, BALB/c, C3H, and A/J mice. These results identified basophils as a previously unrecognized target of anti-ASGM1-mediated cell depletion and raised concern about possible contribution of basophils, rather than or in addition to NK cells, to some of phenotypes observed in anti-ASGM1-treated mice. Indeed, regardless of the presence or absence of NK cells in mice, anti-ASGM1 treatment abolished the development of IgE-mediated chronic cutaneous allergic inflammation as efficiently as did the treatment with basophil-depleting Ab. Given the fact that basophils have recently been shown to play crucial roles in a variety of immune responses, our finding of the off-target effect on basophils issues a grave warning about the use of anti-ASGM1 and underscores the need for careful interpretation of phenotypes observed in anti-ASGM1-treated mice.

Basophils in skin inflammation

Basophils represent less than 1% of peripheral blood leukocytes. Under physiological conditions, basophils principally circulate in peripheral blood, while mast cells reside in peripheral tissues. Like mast cells, they express the high-affinity IgE receptor on their cell surface and release chemical mediators. Because of morphological and functional similarities, basophils have long been considered to be redundant "circulating mast cells" and minor (probably negligible) players in inflammation. Mouse and human basophils cannot be stained in routinely processed histological specimens, and thus, our understanding of tissue basophils in allergic inflammation had been limited. However, recent studies in mice have revealed that basopihls play non-redundant roles from mast cells. Basophils function as a source of IL-4, IL-13, and CCL22, thereby contributing Th2 immunity. They are also capable of presenting antigens. Basophils are essential for the development of IgE-mediated chronic allergic skin inflammation in mice. Recent immunohistochemical studies with an basophil-specific antibody revealed that, in humans, varying numbers of basophils infiltrate skin lesions of inflammatory diseases, such as atopic dermatitis, urticaria, prurigo, and eosinophilic pustular folliculitis. Basophils may play important roles in a variety of inflammatory skin diseases than previously thought.

Inhibitory Effect of Farnesylthiosalicylic Acid on Mediators Release by Mast Cells: Preferential Inhibition of Prostaglandin D2 and Tumor Necrosis Factor-α Release

There is substantial evidence suggesting that the Ras inhibitor farnesylthiosalicylic acid (FTS) may modulate various aspects of immune function and inflammation in addition to its well known anti-cancer activity. In this regard, we have recently shown that FTS suppresses T lymphocyte-mediated immune responses. Mast cells (MC), the main effector cells in the elicitation of the allergic response, are known to secrete granule-associated mediators and to release prostaglandins and cytokines on FCεRI-cross-linking, thereby contributing to the pathogenesis of allergic diseases. We hypothesized that MC act as an additional target for FTS. In the present work we analyze the effects of FTS on MC degranulation, prostaglandin release, and cytokine release in vitro, and on the elicitation of IgE-mediated MC dependent cutaneous allergic inflammation in vivo. First we have established that FTS inhibited Ras activation in MC. Next, we have shown that FTS preferentially inhibited prostaglandin (PG) D(2) and tumor necrosis factor (TNF)-α release without having any significant effect on MC β-hexosaminidase secretion. In vivo administration of FTS inhibited the late phase of passive cutaneous anaphylaxis reaction. The time course of FTS-induced inhibition in vivo correlated with mediators release and not with degranulation. This data suggests that FTS may have an inhibitory effect on MC mediated allergic inflammation, and thus may be considered as a possible therapeutic modality.