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BACKGROUND: Unsupervised clustering of biomarkers derived from non-invasive samples such as nasal fluid is less evaluated as a tool for describing asthma endotypes. OBJECTIVE: To evauate whether protein expression in nasal fluid would identify distinct clusters of asthmatics with specific lower airway molecular phenotypes. METHODS: Unsupervised clustering of 168 nasal inflammatory and immune proteins and Shapley values was used to stratify 43 severe asthmatic patients (ENDANA) using a two 'modelling blocks' machine learning (ML) approach. This algorithm was also applied to nasal brushings transcriptomics from U-BIOPRED. Feature reduction and functional gene analysis were used to compare proteomic and transcriptomic clusters. Gene set variation analysis (GSVA) provided enrichment scores (ESs) of the ENDANA protein signature within U-BIOPRED sputum and blood. RESULTS: The nasal protein ML model identified two severe asthma endotypes, which were replicated in U-BIOPRED nasal transcriptomics. Cluster 1 patients had significant airway obstruction, small airways disease, air trapping, decreased diffusing capacity and increased oxidative stress, although only 4/18 were current smokers. Shapley identified 20 cluster-defining proteins. Forty-one proteins were significantly higher in Cluster 1. Pathways associated with proteomic and transcriptomic clusters were linked to Th1, Th2, neutrophil, JAK-STAT, TLR and infection activation. GSVA analysis of the nasal protein and gene signatures were enriched in subjects with sputum neutrophilic/mixed granulocytic asthma and in subjects with a molecular phenotype found in sputum neutrophil-high subjects. CONCLUSIONS: Protein or gene analysis may indicate molecular phenotypes within the asthmatic lower airway and provide a simple, non-invasive test for non-T2 asthma that is currently unavailable.

Background Respiratory infections with rhinoviruses (RV) are strongly associated with development and exacerbations of asthma, and they pose an additional health risk for subjects with allergy. Objective How RV infections and chronic allergic diseases are linked and what role RV plays in the breaking of tolerance in regulatory T (Treg) cells is unknown. Therefore, this study aims to investigate the effects of RV on Treg cells. Methods Treg cells were isolated from subjects with asthma and controls after experimental infection with the RV-A16 (RV16) and analyzed with next-generation sequencing. Additionally, suppression assays, quantitative PCR assays, and protein quantifications were performed with Treg cells after in vitro RV16 infection. Results RV16 induced a strong antiviral response in Treg cells from subjects with asthma and controls, including the upregulation of IFI44L, MX1, ISG15, IRF7, and STAT1. In subjects with asthma, the inflammatory response was exaggerated and showed a dysregulated immune response compared with that in the controls. Furthermore, subjects with asthma failed to upregulate several immunosuppressive molecules such as CTLA4 and CD69, and they upregulated the inflammasome-related genes PYCARD and AIM2. Additionally, RV16 reduced the suppressive capacity of Treg cells from healthy subjects and subjects with asthma in vitro and increased TH2 cell–type cytokine production. Conclusions Treg cells from healthy subjects and subjects with asthma displayed an antiviral response after RV infection and showed reduced suppressive capacity. These data suggest that Treg cell function might be altered or impaired during RV infections, which might play an important role in the association between RV and the development of asthma and asthma exacerbations.

Background: Recent findings strongly support hematopoietic stem cell transplantation (HSCT) in patients with severe presentation of LPS-responsive beige-like anchor protein (LRBA) deficiency, but long-term follow-up and survival data beyond previous patient reports or meta-reviews are scarce for those patients who do not receive a transplant. Objective: This international retrospective study was conducted to elucidate the longitudinal clinical course of patients with LRBA deficiency who do and do not receive a transplant. Method: We assessed disease burden and treatment responses with a specially developed immune deficiency and dysregulation activity score, reflecting the sum and severity of organ involvement and infections, days of hospitalization, supportive care requirements, and performance indices. Results: of 76 patients with LRBA deficiency from 29 centers (median follow-up, 10 years; range, 1-52), 24 underwent HSCT from 2005 to 2019. the overall survival rate after HSCT (median follow-up, 20 months) was 70.8% (17 of 24 patients); all deaths were due to nonspecific, early, transplant-related mortality. Currently, 82.7% of patients who did not receive a transplant (43 of 52; age range, 3-69 years) are alive. of 17 HSCT survivors, 7 are in complete remission and 5 are in good partial remission without treatment (together, 12 of 17 [70.6%]). in contrast, only 5 of 43 patients who did not receive a transplant (11.6%) are without immunosuppression. Immune deficiency and dysregulation activity scores were significantly lower in patients who survived HSCT than in those receiving conventional treatment (P = .005) or in patients who received abatacept or sirolimus as compared with other therapies, and in patients with residual LRBA expression. Higher disease burden, longer duration before HSCT, and lung involvement were associated with poor outcome. Conclusion: the lifelong disease activity, implying a need for immunosuppression and risk of malignancy, must be weighed against the risks of HSCT., Styrian Children's Cancer Aid Foundation; Slovenian Research AgencySlovenian Research Agency - Slovenia [P3-0343]; Jonas S_oderquist Foundation; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [217S847, 318S202]; Deutsche Forschungsgemeinschaft under Germany's Excellence StrategyGerman Research Foundation (DFG) [390939984, 39087428]; E-Rare program of the European Union by the Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG) [GR1617/14-1/iPAD]; Netzwerke Seltener Erkrankungen of the German Ministry of Education and Research [GAIN_ 01GM1910A]; Finnish Foundation for Pediatric Research and Pediatric Research Center, HUS Helsinki University Hospital; Graduate Research Training Scholarship of the Australian government; Hadassah Australia; ERN-RITA network [739543], M.G. Seidel and the Research Unit for Pediatric Hematology and Immunology are supported in part by the Styrian Children's Cancer Aid Foundation. M. Avbeli Stefanija was supported by the Slovenian Research Agency (grant P3-0343). H. Abolhassani was supported by the Jonas S_oderquist Foundation. S. Baris was supported by the Scientific and Technological Research Council of Turkey for the diagnosis of patients with LRBA deficiency (grants 217S847 and 318S202). B. Grimbacher receives support through the Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy (CIBSS-EXC-2189-Project ID 390939984 and RESIST-EXC 2155-Project ID 39087428); through the E-Rare program of the European Union, managed by the Deutsche Forschungsgemeinschaft (grant GR1617/14-1/iPAD); and through the Netzwerke Seltener Erkrankungen of the German Ministry of Education and Research (grant GAIN_ 01GM1910A). M.R.J. Sepp_anen was supported by the Finnish Foundation for Pediatric Research and Pediatric Research Center, HUS Helsinki University Hospital. I. Meyts is a member of the ERN-RITA network (project identification number 739543). B. Shadur is supported by a Graduate Research Training Scholarship of the Australian government and by Hadassah Australia.

Atopic dermatitis (AD) is a paradigmatic chronic inflammatory skin disease characterized by a complex pathophysiology and a wide spectrum of the clinical phenotype. Despite this high degree of heterogeneity, AD is still considered a single disease and usually treated according to the "one-size-fits-all" approach. Thus more tailored prevention and therapeutic strategies are still lacking. As for other disciplines, such as oncology or rheumatology, we have to approach AD in a more differentiated way (ie, to dissect and stratify the complex clinical phenotype into more homogeneous subgroups based on the endophenotype [panel of biomarkers]) with the aim to refine the management of this condition. Because we are now entering the era of personalized medicine, a systems biology approach merging the numerous clinical phenotypes with robust (ie, relevant and validated) biomarkers will be needed to best exploit their potential significance for the future molecular taxonomy of AD. This approach will not only allow an optimized prevention and treatment with the available drugs but also hopefully help assign newly developed medicinal products to those patients who will have the best benefit/risk ratio.

Background The induction of tolerance and protective immunity to microbes is significantly influenced by host- and microbiota-derived metabolites, such as histamine. Objective We sought to identify the molecular mechanisms for histamine-mediated modulation of pattern recognition receptor signaling. Methods Human monocyte-derived dendritic cells (MDDCs), myeloid dendritic cells, and plasmacytoid dendritic cells were examined. Cytokine secretion, gene expression, and transcription factor activation were measured after stimulation with microbial ligands and histamine. Histamine receptor 2 (H 2 R)–deficient mice, histamine receptors, and their signaling pathways were investigated. Results Histamine suppressed MDDC chemokine and proinflammatory cytokine secretion, nuclear factor κB and activator protein 1 activation, mitogen-activated protein kinase phosphorylation, and T H 1 polarization of naive lymphocytes, whereas IL-10 secretion was enhanced in response to LPS and Pam3Cys. Histamine also suppressed LPS-induced myeloid dendritic cell TNF-α secretion and suppressed CpG-induced plasmacytoid dendritic cell IFN-α gene expression. H 2 R signaling through cyclic AMP and exchange protein directly activated by cyclic AMP was required for the histamine effect on LPS-induced MDDC responses. Lactobacillus rhamnosus , which secretes histamine, significantly suppressed Peyer patch IL-2, IL-4, IL-5, IL-12, TNF-α, and GM-CSF secretion in wild-type but not H 2 R-deficient animals. Conclusion Both host- and microbiota-derived histamine significantly alter the innate immune response to microbes through H 2 R.

Background: Phenotypes of childhood-onset asthma are characterized by distinct trajectories and functional features. For atopy, definition of phenotypes during childhood is less clear. Objective: We sought to define phenotypes of atopic sensitization over the first 6 years of life using a latent class analysis (LCA) integrating 3 dimensions of atopy: allergen specificity, time course, and levels of specific IgE (sIgE). Methods: Phenotypes were defined by means of LCA in 680 children of the Multizentrische Allergiestudie (MAS) and 766 children of the Protection against allergy: Study in Rural Environments (PASTURE) birth cohorts and compared with classical nondisjunctive definitions of seasonal, perennial, and food sensitization with respect to atopic diseases and lung function. Cytokine levels were measured in the PASTURE cohort. Results: The LCA classified predominantly by type and multiplicity of sensitization (food vs inhalant), allergen combinations, and sIgE levels. Latent classes were related to atopic disease manifestations with higher sensitivity and specificity than the classical definitions. LCA detected consistently in both cohorts a distinct group of children with severe atopy characterized by high seasonal sIgE levels and a strong propensity for asthma; hay fever; eczema; and impaired lung function, also in children without an established asthma diagnosis. Severe atopy was associated with an increased IL-5/IFN-gamma ratio. A path analysis among sensitized children revealed that among all features of severe atopy, only excessive sIgE production early in life affected asthma risk. Conclusions: LCA revealed a set of benign, symptomatic, and severe atopy phenotypes. The severe phenotype emerged as a latent condition with signs of a dysbalanced immune response. It determined high asthma risk through excessive sIgE production and directly affected impaired lung function.

The worldwide incidence and prevalence of asthma continues to increase. Asthma is now understood as an umbrella term for different phenotypes or endotypes, which arise through different pathophysiologic pathways. Understanding the many factors contributing to development of the disease is important for the identification of novel therapeutic targets for the treatment of certain asthma phenotypes. The hygiene hypothesis has been formulated to explain the increasing prevalence of allergic disease, including asthma. This hypothesis postulates that decreased exposure at a young age to certain infectious agents as a result of improved hygiene, increased antibiotic use and vaccination, and changes in lifestyle and dietary habits is associated with changes in the immune system, which predispose subjects to allergy. Many microbes, during their coevolution with human subjects, developed mechanisms to manipulate the human immune system and to increase their chances of survival. Improving models of asthma, as well as choosing adequate end points in clinical trials, will lead to a more complete understanding of the underlying mechanisms, thus providing an opportunity to devise primary and secondary interventions at the same time as identifying new molecular targets for treatment. This article reports the discussion and conclusion of a workshop under the auspices of the Netherlands Lung Foundation to extend our understanding of how modulation of the immune system by bacterial, parasitic, and viral infections might affect the development of asthma and to map out future lines of investigation.

Background Atopic eczema (AE) is the most common chronic inflammatory skin disease. Recent data demonstrate the presence of autoreactive serum IgE antibodies correlating with the severity of the disease. Objective Although several IgE-binding self-antigens have been reported, the whole repertoire of IgE-binding self-antigens is unknown. We aimed to estimate the repertoire size of autoreactive proteins related to AE and clone, produce, and characterize humoral and T-cell responses against novel self-antigens. Methods Phage surface–displayed human cDNA libraries were enriched for clones binding to serum IgE from patients with AE and screened by using high-throughput technology. Selected clones were used to produce the encoded proteins, to test their IgE-binding ability in Western blots and ELISAs, and their ability to induce mediator release from basophils of sensitized individuals. Results One hundred forty sequences encoding potential IgE-binding self-antigens associated with AE were identified. Sixteen sequences encoded already described self-antigens. Three new sequences showed homology with environmental allergens, 86 encoded known human proteins, 7 predicted proteins, and 28 showed sequence identity with genomic contigs. Immunoblotting and ELISA experiments demonstrated the presence of IgE antibodies in sera from patients with AE to 5 selected recombinant self-antigens and their ability to induce mediator release from basophils of patients with AE who have self-antigen–specific IgE antibodies. Conclusion These data demonstrate a broad spectrum of at least 140 IgE-binding self-antigens associated with AE. By binding IgE antibodies or activating specific T cells, they might promote, perpetuate, or both existing skin inflammation.

Background Anaphylaxis in children and adolescents is a potentially life-threatening condition. Its heterogeneous clinical presentation and sudden occurrence in virtually any setting without warning have impeded a comprehensive description. Objective We sought to characterize severe allergic reactions in terms of elicitors, symptoms, emergency treatment, and long-term management in European children and adolescents. Methods The European Anaphylaxis Registry recorded details of anaphylaxis after referral for in-depth diagnosis and counseling to 1 of 90 tertiary allergy centers in 10 European countries, aiming to oversample the most severe reactions. Data were retrieved from medical records by using a multilanguage online form. Results Between July 2007 and March 2015, anaphylaxis was identified in 1970 patients younger than 18 years. Most incidents occurred in private homes (46%) and outdoors (19%). One third of the patients had experienced anaphylaxis previously. Food items were the most frequent trigger (66%), followed by insect venom (19%). Cow's milk and hen's egg were prevalent elicitors in the first 2 years, hazelnut and cashew in preschool-aged children, and peanut at all ages. There was a continuous shift from food- to insect venom– and drug-induced anaphylaxis up to age 10 years, and there were few changes thereafter. Vomiting and cough were prevalent symptoms in the first decade of life, and subjective symptoms (nausea, throat tightness, and dizziness) were prevalent later in life. Thirty percent of cases were lay treated, of which 10% were treated with an epinephrine autoinjector. The fraction of intramuscular epinephrine in professional emergency treatment increased from 12% in 2011 to 25% in 2014. Twenty-six (1.3%) patients were either admitted to the intensive care unit or had grade IV/fatal reactions. Conclusions The European Anaphylaxis Registry confirmed food as the major elicitor of anaphylaxis in children, specifically hen's egg, cow's milk, and nuts. Reactions to insect venom were seen more in young adulthood. Intensive care unit admissions and grade IV/fatal reactions were rare. The registry will serve as a systematic foundation for a continuous description of this multiform condition.

Allergen immunotherapy (AIT) has been used to treat allergic disease since the early 1900s. Despite numerous clinical trials and meta-analyses proving AIT efficacious, it remains underused and is estimated to be used in less than 10% of patients with allergic rhinitis or asthma worldwide. In addition, there are large differences between regions, which are not only due to socioeconomic status. There is practically no controversy about the use of AIT in the treatment of allergic rhinitis and allergic asthma, but for atopic dermatitis or food allergy, the indications for AIT are not well defined. The elaboration of a wider consensus is of utmost importance because AIT is the only treatment that can change the course of allergic disease by preventing the development of asthma and new allergen sensitizations and by inducing allergen-specific immune tolerance. Safer and more effective AIT strategies are being continuously developed both through elaboration of new allergen preparations and adjuvants and alternate routes of administration. A number of guidelines, consensus documents, or both are available on both the international and national levels. The international community of allergy specialists recognizes the need to develop a comprehensive consensus report to harmonize, disseminate, and implement the best AIT practice. Consequently, the International Collaboration in Asthma, Allergy and Immunology, formed by the European Academy of Allergy and Clinical Immunology; the American Academy of Allergy, Asthma & Immunology; the American College of Allergy, Asthma & Immunology; and the World Allergy Organization, has decided to issue an international consensus on AIT.

Background Distinct human IL-10–producing B-cell subsets with immunoregulatory properties have been described. However, the broader spectrum of their direct cellular targets and suppressive mechanisms has not been extensively studied, particularly in relation to direct and indirect IL-10–mediated functions. Objective The aim of the study was to investigate the effects of IL-10 overexpression on the phenotype and immunoregulatory capacity of B cells. Methods Primary human B cells were transfected with hIL-10, and IL-10–overexpressing B cells were characterized for cytokine and immunoglobulin production by means of specific ELISA and bead-based assays. Antigen presentation, costimulation capacity, and transcription factor signatures were analyzed by means of flow cytometry and quantitative RT-PCR. Effects of IL-10–overexpresing B cells on Toll-like receptor–triggered cytokine release from PBMCs, LPS-triggered maturation of monocyte-derived dendritic cells, and tetanus toxoid–induced PBMC proliferation were assessed in autologous cocultures. Results IL-10–overexpressing B cells acquired a prominent immunoregulatory profile comprising upregulation of suppressor of cytokine signaling 3 (SOCS3), glycoprotein A repetitions predominant (GARP), the IL-2 receptor α chain (CD25), and programmed cell death 1 ligand 1 (PD-L1). Concurrently, their secretion profile was characterized by a significant reduction in levels of proinflammatory cytokines (TNF-α, IL-8, and macrophage inflammatory protein 1α) and augmented production of anti-inflammatory IL-1 receptor antagonist and vascular endothelial growth factor. Furthermore, IL-10 overexpression was associated with a decrease in costimulatory potential. IL-10–overexpressing B cells secreted less IgE and potently suppressed proinflammatory cytokines in PBMCs, maturation of monocyte-derived dendritic cells (rendering their profile to regulatory phenotype), and antigen-specific proliferation in vitro . Conclusion Our data demonstrate an essential role for IL-10 in inducing an immunoregulatory phenotype in B cells that exerts substantial anti-inflammatory and immunosuppressive functions.

Background: IL 10 producing regulatory B cells suppress immune responses and lack of these cells leads to exacerbated symptoms in mouse models of chronic inflammation transplantation and chronic infection. IgG4 is a blocking antibody isotype with anti inflammatory potential that is induced in human high dose antigen tolerance models. Objective: We sought to characterize human inducible IL 10 secreting B regulatory 1 (BR1) cells and to investigate their immunoregulatory capacity through suppression of cellular immune responses and production of anti inflammatory immunoglobulins. Methods: Highly purified IL 10 secreting B cells were phenotypically and functionally characterized by means of whole genome expression analysis flow cytometry suppression assay and antibody production. B cells specific for the major bee venom allergen phospholipase A2 (PLA) were isolated from beekeepers who displayed tolerance to bee venom antigens and allergic patients before and after specific immunotherapy. Results: Human IL 10+ BR1 cells expressed high surface CD25 and CD71 and low CD73 levels. Sorting of CD73 CD25+CD71+ B cells allowed enrichment of human BR1 cells which produced high levels of IL 10 and potently suppressed antigen specific CD4+ T cell proliferation. IgG 4 was selectively confined to human BR1 cells. B cells specific for the major bee venom allergen PLA isolated from nonallergic beekeepers show increased expression of IL 10 and IgG4. Furthermore the frequency of IL 10+ PLA specific B cells increased in allergic patients receiving allergen specific immunotherapy. Conclusion: Our data show the characterization of IL 10+ BR1 cells and in vivo evidence for 2 essential features of allergen tolerance: the suppressive B cells and IgG4 expressing B cells that are confined to IL 10+ BR1 cells in human subjects. © 2013 American Academy of Allergy Asthma Immunology.

Substantial progress in understanding mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumors, organ transplantation, chronic infections, and pregnancy is in an exciting developmental phase that might lead to a variety of targeted therapeutic approaches. Recent progress in the interaction between immune/inflammatory cell subsets through cytokines, particularly the extension of the knowledge on reciprocal regulation and counterbalance between subsets of T(H)1, T(H)2, T(H)9, T(H)17, T(H)22, T follicular helper cells and different subsets of regulatory T cells, as well as corresponding and co-orchestrating B-cell, natural killer cell, dendritic cell, and innate lymphoid cell subsets, offers new possibilities for immune intervention. Studies on new subsets confirm the important role of T cells in the instruction of tissue cells and also demonstrate the important role of feedback regulation for the polarization toward distinct T-cell subsets. T(H)17 and T(H)22 cells are 2 emerging T(H) cell subsets that link the immune response to tissue inflammation; IL-17A and IL-17F and IL-22 are their respective prototype cytokines. Although both cytokines play roles in immune defense to extracellular bacteria, IL-17 augments inflammation, whereas IL-22 plays a tissue-protective role. This review focuses on current knowledge on T(H)17 and T(H)22 cells and their role in inflammation, with special focus on the mechanisms of their generation and driving and effector cytokines, as well as their role in host defense, autoimmunity, and allergic diseases.

Background Early desensitization of FceRI-bearing mast cells and basophils has been demonstrated in allergen-specific immunotherapy and drug desensitization. However, its mechanisms have not been elucidated in detail. Histamine is one of the main mediators released on FceRI triggering of basophils and mast cells, and it exerts its functions through histamine receptors (HRs). Objectives We sought to investigate HR expression on basophils of patients undergoing venom immunotherapy (VIT) and its effect on allergen, IgE, and FceRI cross-linking–mediated basophil function and mediator release. Methods Basophils were purified from the peripheral blood of patients undergoing VIT and control subjects and were studied functionally by using real-time PCR, flow cytometry and ELISA assays. Results Rapid upregulation of H2R within the first 6 hours of the build-up phase of VIT was observed. H2R strongly suppressed FceRI-induced activation and mediator release of basophils, including histamine and sulfidoleukotrienes, as well as cytokine production in vitro . Conclusion Immunosilencing of FceRI-activated basophils by means of selective suppression mediated by H2R might be highly relevant for the very early induction of allergen tolerance and the so-called desensitization effect of VIT.

BACKGROUND Subcutaneous allergen specific immunotherapy frequently causes allergic side effects and requires 30 to 80 injections over 3 to 5 years. OBJECTIVE We sought to improve immunotherapy by using intralymphatic allergen administration (intralymphatic immunotherapy [ILIT]) and by targeting allergen to the MHC class II pathway. METHODS Recombinant major cat dander allergen Fel d 1 was fused to a translocation sequence (TAT) and to part of the human invariant chain generating a modular antigen transporter (MAT) vaccine (MAT Fel d 1). In a randomized double blind trial ILIT with MAT Fel d 1 in alum was compared with ILIT with placebo (saline in alum) in allergic patients (ClinicalTrials.govNCT00718679). RESULTS ILIT with MAT Fel d 1 elicited no adverse events. After 3 placebo injections within 2 months nasal tolerance increased less than 3 fold whereas 3 intralymphatic injections with MAT Fel d 1 increased nasal tolerance 74 fold (P < .001 vs placebo). ILIT with MAT Fel d 1 stimulated regulatory T cell responses (P = .026 vs placebo) and increased cat dander specific IgG(4) levels by 5.66 fold (P = .003). The IgG(4) response positively correlated with IL 10 production (P < .001). CONCLUSION In a first in human clinical study ILIT with MAT Fel d 1 was safe and induced allergen tolerance after 3 injections.

Background Increased airway smooth muscle (ASM) mass is an essential component of airway remodeling and asthma development, and there is no medication specifically against it. Tight junction (TJ) proteins, which are expressed in endothelial and epithelial cells and affect tissue integrity, might exist in other types of cells and display additional functions in the asthmatic lung. Objective The aim of this study was to investigate the existence, regulation, and function of TJ proteins in ASM in asthmatic patients. Methods The expression and function of TJ proteins in primary ASM cell lines, human bronchial biopsy specimens, and a murine model of asthma were analyzed by means of RT-PCR, multispectral imaging flow cytometry, immunohistochemistry, Western blotting, 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester staining, tritiated thymidine incorporation, wound-healing assay, and luminometric bead array. Results Increased claudin-1 expression was observed in ASM of asthmatic patients, as well as in a murine model of asthma-like airway inflammation. Whereas IL-1β and TNF-α upregulated claudin-1 expression, it was downregulated by the T H 2 cytokines IL-4 and IL-13 in primary human ASM cells. Claudin-1 was localized to the nucleus and cytoplasm but not to the cell surface in ASM cells. Claudin-1 played a central role in ASM cell proliferation, as demonstrated by increased ASM cell proliferation seen with overexpression and decreased proliferation seen with small interfering RNA knockdown of claudin-1. Overexpression of claudin-1 induced vascular endothelial growth factor and downregulated IL-6, IL-8, and IFN-γ–induced protein 10 production by ASM cells. Claudin-1 upregulation by IL-1β or TNF-α was suppressed by dexamethasone but not by rapamycin, FK506, or salbutamol. Conclusion These results demonstrate that claudin-1 might play a role in airway remodeling in asthmatic patients by means of regulation of ASM cell proliferation, angiogenesis, and inflammation.

Background Patients with birch pollen allergy often develop allergic reactions to plant foods. Objective To evaluate the prevalence, main symptoms, and triggers of birch pollen–related food allergy and the role of food-specific IgG 4 antibodies in food tolerance. Methods Food-induced symptoms were evaluated in 225 individuals with birch pollen allergy by using a standardized questionnaire. IgE and IgG 4 levels specific for the major birch pollen allergen Bet v 1 and birch profilin Bet v 2 and the Bet v 1 homologs in apple (Mal d 1) and hazelnut (Cor a 1) were quantified by ImmunoCAP. Mock-treated and IgG-depleted sera from patients tolerating hazelnuts in food challenges were compared for their inhibitory activity for binding of Cor a 1–IgE complexes to B cells. Results In total, 73% of the study population experienced food allergy, which was perennial in 86% of the affected individuals. The oral allergy syndrome was the main clinical manifestation. However, more than 58% of the patients also experienced food-induced rhinoconjunctivitis. Apples and hazelnuts were identified as the most frequent triggers. Food allergy correlated with IgE reactivity to Bet v 1 but not to Bet v 2. Mal d 1–specific and Cor a 1–specific IgG 4 /IgE ratios were significantly higher in food-tolerant individuals than individuals with food allergy. Sera from IgG 4 -positive food-tolerant patients possessed IgG-dependent IgE-inhibitory activity. Conclusion Birch pollen–related food allergy is highly prevalent and often perennial. High food allergen–specific IgG 4 /IgE ratios seem associated with food tolerance, potentially because specific IgG 4 blocks IgE binding to food allergens. Thus, the presence of food allergen–specific IgG 4 antibodies is no diagnostic marker for birch pollen–related food allergy.

BACKGROUND: Allergen-specific desensitization (SIT) is the most effective therapy for allergies. Although allergen-specific antibodies have an important role in the process, mechanisms of IgG-mediated inhibition of allergic reactions are not well defined. OBJECTIVE: We investigated mechanisms by which SIT-induced allergen-specific IgGs inhibit allergic reactions. METHODS: We generated mAbs that recognize 3 nonoverlapping epitopes of the major cat allergen Fel d 1. Each of the mAbs was produced as an IgE and different IgG isotype. RESULTS: IgEs against 2 nonoverlapping epitopes on Fel d 1 are necessary and sufficient to sensitize mast cells for maximal FcepsilonRI signaling and degranulation on exposure to monomeric Fel d 1. IgE antibodies of a third specificity did not further increase mast cell degranulation, indicating that formation of large FcepsilonRI clusters are not required to induce maximal activation of mast cells. A single IgG that was specific for an epitope different from those recognized by the IgEs was a potent inhibitor of Fel d 1-mediated mast cell activation in vitro and in vivo. This inhibition required Fcgamma receptor-IIB. In human beings, IgGs of a single specificity were able to block degranulation of basophils from individuals with cat allergy. The inhibitory potential of these antibodies increased when larger allergen-IgG complexes were formed. CONCLUSIONS: These data reconcile conflicting theories in the literature and might explain the reason IgE levels do not necessarily decrease during therapy, despite clinical efficacy. These findings have important implications for vaccine design.

More than 50 years after Ogdeon Bruton’s discovery of congenital agammaglobulinemia, human primary immunodeficiencies (PIDs) continue to unravel novel molecular and cellular mechanisms that govern development and function of the human immune system. This report provides the updated classification of PIDs, that has been compiled by the International Union of Immunological Societies (IUIS) Expert Committee of Primary Immunodeficiencies after its biannual meeting, in Dublin (Ireland) in June 2009. Since the appearance of the last classification in 2007, novel forms of PID have been discovered, and additional pathophysiology mechanisms that account for PID in humans have been unraveled. Careful analysis and prompt recognition of these disorders is essential to prompt effective forms of treatment and thus to improve survival and quality of life in patients affected with PIDs.

Background Analysis of IgE antibody binding to epitopes provides information for food allergy diagnosis and management and construction of hypoallergenic candidate vaccines, but the contribution of sequential epitopes to functionally relevant IgE binding is not fully understood. Objectives We sought to study the impact of IgE-binding peptides described as major sequence epitopes in the literature on IgE-binding capacity of 2 selected food allergens. Methods IgE-binding peptides of the food allergens Ara h 2 (peanut) and Pen a 1 (shrimp) were identified. Synthetic soluble peptides representing the identified sequences were assessed for their capacity to inhibit IgE binding to the parent allergens by means of ELISA and in mediator release assay. The IgE-binding capacity of unfolded recombinant (r) Ara h 2 was analyzed. A hybrid tropomyosin carrying the IgE-binding regions of Pen a 1 grafted into the structural context of the nonallergenic mouse tropomyosin was applied in ELISA inhibition experiments and ImmunoCAP analysis. Results Although IgE-binding peptides representing sections of the allergen sequences were detected, no relevant capacity to inhibit the IgE binding to the parent allergen in ELISA or basophil activation test was observed. Unfolded rAra h 2 showed reduced IgE-binding capacity compared with folded rAra h 2 and failed to elicit mediator release. Hybrid tropomyosin bound less IgE than rPen a 1 in ImmunoCAP analysis and revealed marginal inhibitory capacity. Conclusion Peptides identified as major sequence epitopes on Pen a 1 and Ara h 2 show little contribution to the IgE binding of the allergens studied.