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Background: The increased prevalence of many chronic inflammatory diseases linked to gut epithelial barrier leakiness has prompted us to investigate the role of extensive use of dishwasher detergents, among other factors., Objective: We sought to investigate the effects of professional and household dishwashers, and rinse agents, on cytotoxicity, barrier function, transcriptome, and protein expression in gastrointestinal epithelial cells., Methods: Enterocytic liquid-liquid interfaces were established on permeable supports, and direct cellular cytotoxicity, transepithelial electrical resistance, paracellular flux, immunofluorescence staining, RNA-sequencing transcriptome, and targeted proteomics were performed., Results: The observed detergent toxicity was attributed to exposure to rinse aid in a dose-dependent manner up to 1:20,000 v/v dilution. A disrupted epithelial barrier, particularly by rinse aid, was observed in liquid-liquid interface cultures, organoids, and gut-on-a-chip, demonstrating decreased transepithelial electrical resistance, increased paracellular flux, and irregular and heterogeneous tight junction immunostaining. When individual components of the rinse aid were investigated separately, alcohol ethoxylates elicited a strong toxic and barrier-damaging effect. RNA-sequencing transcriptome and proteomics data revealed upregulation in cell death, signaling and communication, development, metabolism, proliferation, and immune and inflammatory responses of epithelial cells. Interestingly, detergent residue from professional dishwashers demonstrated the remnant of a significant amount of cytotoxic and epithelial barrier-damaging rinse aid remaining on washed and ready-to-use dishware., Conclusions: The expression of genes involved in cell survival, epithelial barrier, cytokine signaling, and metabolism was altered by rinse aid in concentrations used in professional dishwashers. The alcohol ethoxylates present in the rinse aid were identified as the culprit component causing the epithelial inflammation and barrier damage., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Unsupervised clustering of biomarkers derived from noninvasive samples such as nasal fluid is less evaluated as a tool for describing asthma endotypes., Objective: We sought to evaluate whether protein expression in nasal fluid would identify distinct clusters of patients with asthma with specific lower airway molecular phenotypes., Methods: Unsupervised clustering of 168 nasal inflammatory and immune proteins and Shapley values was used to stratify 43 patients with severe asthma (endotype of noneosinophilic asthma) using a 2 "modeling blocks" machine learning approach. This algorithm was also applied to nasal brushings transcriptomics from U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Diseases Outcomes). Feature reduction and functional gene analysis were used to compare proteomic and transcriptomic clusters. Gene set variation analysis provided enrichment scores of the endotype of noneosinophilic asthma protein signature within U-BIOPRED sputum and blood., Results: The nasal protein machine learning model identified 2 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 of 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 T H 1, T H 2, neutrophil, Janus kinase-signal transducer and activator of transcription, TLR, and infection activation. Gene set variation 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, noninvasive test for non-type 2 immune response asthma that is currently unavailable., (Copyright © 2022. Published by Elsevier Inc.)

The prevalence of food allergy (FA) is increasing in some areas of the globe, highlighting the need for better strategies for prevention, diagnosis, and therapy. In the last few decades, we have made great strides in understanding the causes and mechanisms underlying FAs, prompting guideline updates. Earlier guidelines recommended avoidance of common food allergens during pregnancy and lactation and delaying the introduction of allergenic foods in children aged between 1 and 3 years. Recent guidelines for allergy prevention recommend consumption of a healthy and diverse diet without eliminating or increasing the consumption of allergenic foods during pregnancy or breast-feeding. Early introduction of allergenic foods is recommended by most guidelines for allergy prevention after a period of exclusive breast-feedng (6 months [World Health Organization] or 4 months [European Academy of Allergy and Clinical Immunology]). New diagnostics for FA have been developed with varied availability of these tests in different countries. Finally, the first oral immunotherapy drug for FA was approved by the US Food and Drug Administration and European Medicines Agency in 2020. In this review, we will address the global prevalence of FA, our current understanding of the causes of FA, and the latest guidelines for preventing, diagnosing, and treating FA. We will also discuss similarities and differences between FA guidelines., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

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 T H 2 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., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

Background: Despite the efficacy of allergen-specific immunotherapy (AIT), the role of trained immunity and tolerance in this process has not been elucidated., Objective: Here, we have performed a comprehensive longitudinal analysis of the systemic innate immune cell repertoire during the course of AIT., Methods: Patients with allergy received standard preseasonal subcutaneous AIT with allergoids to birch and/or grass. Healthy controls were monitored without any intervention. Flow cytometry of innate lymphoid cell (ILC), natural killer cell, monocyte cell, and dendritic cell (DC) subsets was performed at baseline, 3 months (birch season), 6 months (grass seasons), and 12 months after the therapy in patients or at similar seasonal time points in controls. Additional analyses were performed in the third-year birch and grass season., Results: We observed a durable decrease in group 2 ILCs and an increase of group 1 ILCs after AIT, with dynamic changes in their composition. We found that an expansion of CD127 + CD25 ++ clusters caused observed shifts in the heterogeneity of group 1 ILCs. In addition, we observed development of CD127 + CD25 ++ c-Kit + group 3 ILC clusters. Moreover, we found an increase in the number of intermediate monocytes in parallel with a reduction in nonclassical monocytes during the first year after AIT. Classical and intermediate monocytes presented significant heterogeneity in patients with allergy, but AIT reduced the HLA-DR ++ clusters. Finally, an increase in plasmacytoid DCs and CD141 + myeloid DCs was observed in individuals with allergy, whereas the number of CD1c + myeloid DCs was reduced during the first year of AIT., Conclusion: AIT induces changes in the composition and heterogeneity of circulating innate immune cells and brings them to the level observed in healthy individuals. Monitoring of ILCs, monocytes, and DCs during AIT might serve as a novel biomarker strategy., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

The main interfaces controlling and attempting to homeostatically balance communications between the host and the environment are the epithelial barriers of the skin, gastrointestinal system, and airways. The epithelial barrier constitutes the first line of physical, chemical, and immunologic defenses and provides a protective wall against environmental factors. Following the industrial revolution in the 19th century, urbanization and socioeconomic development have led to an increase in energy consumption, and waste discharge, leading to increased exposure to air pollution and chemical hazards. Particularly after the 1960s, biological and chemical insults from the surrounding environment-the exposome-have been disrupting the physical integrity of the barrier by degrading the intercellular barrier proteins at tight and adherens junctions, triggering epithelial alarmin cytokine responses such as IL-25, IL-33, and thymic stromal lymphopoietin, and increasing the epithelial barrier permeability. A typical type 2 immune response develops in affected organs in asthma, rhinitis, chronic rhinosinusitis, eosinophilic esophagitis, food allergy, and atopic dermatitis. The aim of this article was to discuss the effects of environmental factors such as protease enzymes of allergens, detergents, tobacco, ozone, particulate matter, diesel exhaust, nanoparticles, and microplastic on the integrity of the epithelial barriers in the context of epithelial barrier hypothesis., (Copyright © 2020. Published by Elsevier Inc.)

Background: p-Phenylenediamine (PPD) is a strong contact allergen used in hair dye that is known to cause allergic contact dermatitis (ACD). Both private and occupational exposure to PPD is frequent, but the effect of PPD exposure in nonallergic occupationally exposed subjects is unknown., Objective: We sought to investigate the effects of PPD exposure on the skin of occupationally exposed subjects with and without clinical symptoms., Methods: Skin biopsy specimens were collected from 4 patients with mild and 5 patients with severe PPD-related ACD and 7 hairdressers without contact dermatitis on day 4 after patch testing with 1% PPD in petrolatum. RNA sequencing and transcriptomics analyses were performed and confirmed by using quantitative RT-PCR. Protein expression was analyzed in skin from 4 hairdressers and 1 patient with ACD by using immunofluorescence staining. Reconstructed human epidermis was used to test the effects of PPD in vitro., Results: RNA sequencing demonstrated downregulation of tight junction and stratum corneum proteins in the skin of patients with severe ACD after PPD exposure. Claudin-1 (CLDN-1), CLDN8, CLDN11, CXADR-like membrane protein (CLMP), occludin (OCLN), membrane-associated guanylate kinase inverted 1 (MAGI1), and MAGI2 mRNA expression was downregulated in patients with severe ACD. CLDN1 and CLMP expression were downregulated in nonresponding hairdressers and patients with mild ACD. Filaggrin 1 (FLG1), FLG2, and loricrin (LOR) expression were downregulated in patients with ACD. Confocal microscopic images showed downregulation of CLDN-1, FLG-1, and FLG-2 expression. In contrast, 3-dimensional skin cultures showed upregulation of FLG-1 in response to PPD but downregulation of FLG-2., Conclusion: PPD-exposed skin is associated with extensive transcriptomic changes, including downregulation of tight junction and stratum corneum proteins, even in the absence of clinical symptoms., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: A defective epithelial barrier is found in patients with allergic rhinitis (AR) and asthma; however, the underlying mechanisms remain poorly understood. Histone deacetylase (HDAC) activity has been identified as a crucial driver of allergic inflammation and tight junction dysfunction., Objective: We investigated whether HDAC activity has been altered in patients with AR and in a mouse model of house dust mite (HDM)-induced allergic asthma and whether it contributed to epithelial barrier dysfunction., Methods: Primary nasal epithelial cells of control subjects and patients with AR were cultured at the air-liquid interface to study transepithelial electrical resistance and paracellular flux of fluorescein isothiocyanate-dextran (4 kDa) together with mRNA expression and immunofluorescence staining of tight junctions. Air-liquid interface cultures were stimulated with different concentrations of JNJ-26481585, a broad-spectrum HDAC inhibitor. In vivo the effect of JNJ-26481585 on mucosal permeability and tight junction function was evaluated in a mouse model of HDM-induced allergic airway inflammation., Results: General HDAC activity was greater in nasal epithelial cells of patients with AR and correlated inversely with epithelial integrity. Treatment of nasal epithelial cells with JNJ-26481585 restored epithelial integrity by promoting tight junction expression and protein reorganization. HDM-sensitized mice were treated with JNJ-26481585 to demonstrate the in vivo role of HDACs. Treated mice did not have allergic airway inflammation and had no bronchial hyperreactivity. Moreover, JNJ-26481585 treatment restored nasal mucosal function by promoting tight junction expression., Conclusion: Our findings identify increased HDAC activity as a potential tissue-injury mechanism responsible for dysregulated epithelial cell repair, leading to defective epithelial barriers in AR. Blocking HDAC activity is a promising novel target for therapeutic intervention in patients with airway diseases., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Group 2 innate lymphoid cells (ILC2s) play critical roles in induction and exacerbation of allergic airway inflammation. Thus clarification of the mechanisms that underlie regulation of ILC2 activation has received significant attention. Although innate lymphoid cells are divided into 3 major subsets that mirror helper effector T-cell subsets, counterpart subsets of regulatory T cells have not been well characterized., Objective: We sought to determine the factors that induce regulatory innate lymphoid cells (ILCregs)., Methods: IL-10 + ILCregs induced from ILC2s by using retinoic acid (RA) were analyzed with RNA-sequencing and flow cytometry. ILCregs were evaluated in human nasal tissue from healthy subjects and patients with chronic rhinosinusitis with nasal polyps and lung tissue from house dust mite- or saline-treated mice., Results: RA induced IL-10 secretion by human ILC2s but not type 2 cytokines. IL-10 + ILCregs, which were converted from ILC2s by means of RA stimulation, expressed a regulatory T cell-like signature with expression of IL-10, cytotoxic T lymphocyte-associated protein 4, and CD25, with downregulated effector type 2-related markers, such as chemoattractant receptor-homologous molecule on T H 2 cells and ST2, and suppressed activation of CD4 + T cells and ILC2s. ILCregs were rarely detected in human nasal tissue from healthy subjects or lung tissue from saline-treated mice, but numbers were increased in nasal tissue from patients with chronic rhinosinusitis with nasal polyps and in lung tissue from house dust mite-treated mice. Enzymes for RA synthesis were upregulated in airway epithelial cells during type 2 inflammation in vivo and by IL-13 in vitro., Conclusion: We have identified a unique immune regulatory and anti-inflammatory pathway by which RA converts ILC2s to ILCregs. Interactions between airway epithelial cells and ILC2s play an important roles in the generation of ILCregs., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Defects in the epithelial barrier have recently been associated with asthma and other allergies. The influence of laundry detergents on human bronchial epithelial cells (HBECs) and their barrier function remain unknown., Objective: We investigated the effects of laundry detergents on cytotoxicity, barrier function, the transcriptome, and the epigenome in HBECs., Methods: Air-liquid interface cultures of primary HBECs from healthy control subjects, patients with asthma, and patients with chronic obstructive pulmonary disease were exposed to laundry detergents and detergent residue after rinsing. Cytotoxicity and epithelial barrier function were evaluated. RNA sequencing, Assay for Transposase Accessible Chromatin with high-throughput sequencing, and DNA methylation arrays were used for checking the transcriptome and epigenome., Results: Laundry detergents and rinse residue showed dose-dependent toxic effects on HBECs, with irregular cell shape and leakage of lactate dehydrogenase after 24 hours of exposure. A disrupted epithelial barrier function was found with decreased transepithelial electrical resistance, increased paracellular flux, and stratified tight junction (TJ) immunostaining in HBECs exposed to laundry detergent at 1:25,000 dilutions or rinse residue at further 1:10 dilutions. RNA sequencing analysis showed that lipid metabolism, apoptosis progress, and epithelially derived alarmin-related gene expression were upregulated, whereas cell adhesion-related gene expression was downregulated by laundry detergent at 1:50,000 dilutions after 24 hours of exposure without substantially affecting chromatin accessibility and DNA methylation., Conclusion: Our data demonstrate that laundry detergents, even at a very high dilution, and rinse residue show significant cell-toxic and directly disruptive effects on the TJ barrier integrity of HBECs without affecting the epigenome and TJ gene expression., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Infections with human rhinoviruses (RVs) are responsible for millions of common cold episodes and the majority of asthma exacerbations, especially in childhood. No drugs specifically targeting RVs are available., Objective: We sought to identify specific anti-RV molecules based on DNAzyme technology as candidates to a clinical study., Methods: A total of 226 candidate DNAzymes were designed against 2 regions of RV RNA genome identified to be sufficiently highly conserved between virus strains (ie, the 5'-untranslated region and cis-acting replication element) by using 3 test strains: RVA1, RVA16, and RVA29. All DNAzymes were screened for their cleavage efficiency against in vitro-expressed viral RNA. Those showing any catalytic activity were subjected to bioinformatic analysis of their reverse complementarity to 322 published RV genomic sequences. Further molecular optimization was conducted for the most promising candidates. Cytotoxic and off-target effects were excluded in HEK293 cell-based systems. Antiviral efficiency was analyzed in infected human bronchial BEAS-2B cells and ex vivo-cultured human sinonasal tissue., Results: Screening phase-generated DNAzymes characterized by either good catalytic activity or by high RV strain coverage but no single molecule represented a satisfactory combination of those 2 features. Modifications in length of the binding domains of 2 lead candidates, Dua-01(-L12R9) and Dua-02(-L10R11), improved their cleavage efficiency to an excellent level, with no loss in eminent strain coverage (about 98%). Both DNAzymes showed highly favorable cytotoxic/off-target profiles. Subsequent testing of Dua-01-L12R9 in BEAS-2B cells and sinonasal tissue demonstrated its significant antiviral efficiency., Conclusions: Effective and specific management of RV infections with Dua-01-L12R9 might be useful in preventing asthma exacerbations, which should be verified by clinical trials., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Long-term follow-up of allergen-specific B cells in terms of immunoglobulin isotype expression, plasmablast differentiation, and regulatory B (Breg) cell development during allergen-specific immunotherapy (AIT) has not been reported., Objective: Allergen-specific B-cell responses during 2 years of house dust mite AIT were compared between responder and nonresponder patients., Methods: B cells specific for Der p 1 were detected by using the fluorochrome-labeled allergen method. The frequency of IgA-, IgG 1 - and IgG 4 -switched Der p 1-specific B cells, plasmablasts, and IL-10- and IL-1 receptor antagonist (IL-1RA)-producing Breg cells were investigated and correlated to clinical response to AIT., Results: Sixteen of 25 patients completed the 2-year study. Eleven responder patients showed a successful response to AIT, as measured by a decrease in symptom-medication scores from 13.23 ± 0.28 to 2.45 ± 0.24 (P = .001) and a decrease in skin prick test reactivity to house dust mite from 7.0 ± 1.3 to 2.7 ± 0.5 mm (P = .001). IgG 4 + and IgA + Der p 1-specific B cells showed a significant increase after AIT, with a significantly greater frequency in responders compared with nonresponders in the IgG 4 + but not the IgA + fraction. The frequency of plasmablasts and IL-10- and/or IL-1RA-producing Breg cells was greater among responders compared with nonresponders after 2 years. The increased frequency of Der p 1-specific IgG4 + B cells, plasmablasts, and IL-10 + and dual-positive IL-10 + IL-1RA + Breg cells significantly correlated with improved clinical symptoms over the course of AIT., Conclusion: Allergen-specific B cells in patients responding to AIT are characterized by increased numbers of IgA- and IgG 4 -expressing Der p 1-specific B cells, plasmablasts, and IL-10 + and/or IL-1RA + Breg cells., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: IL-33 plays a critical role in regulation of tissue homeostasis, injury, and repair. Whether IL-33 regulates neutrophil recruitment and functions independently of airways hyperresponsiveness (AHR) in the setting of ozone-induced lung injury and inflammation is unclear., Objective: We sought to examine the role of the IL-33/ST2 axis in lung inflammation on acute ozone exposure in mice., Methods: ST2- and Il33-deficient, IL-33 citrine reporter, and C57BL/6 (wild-type) mice underwent a single ozone exposure (1 ppm for 1 hour) in all studies. Cell recruitment in lung tissue and the bronchoalveolar space, inflammatory parameters, epithelial barrier damage, and airway hyperresponsiveness (AHR) were determined., Results: We report that a single ozone exposure causes rapid disruption of the epithelial barrier within 1 hour, followed by a second phase of respiratory barrier injury with increased neutrophil recruitment, reactive oxygen species production, AHR, and IL-33 expression in epithelial and myeloid cells in wild-type mice. In the absence of IL-33 or IL-33 receptor/ST2, epithelial cell injury with protein leak and myeloid cell recruitment and inflammation are further increased, whereas the tight junction proteins E-cadherin and zonula occludens 1 and reactive oxygen species expression in neutrophils and AHR are diminished. ST2 neutralization recapitulated the enhanced ozone-induced neutrophilic inflammation. However, myeloid cell depletion using GR-1 antibody reduced ozone-induced lung inflammation, epithelial cell injury, and protein leak, whereas administration of recombinant mouse IL-33 reduced neutrophil recruitment in Il33-deficient mice., Conclusion: Data demonstrate that ozone causes an immediate barrier injury that precedes myeloid cell-mediated inflammatory injury under the control of the IL-33/ST2 axis. Thus IL-33/ST2 signaling is critical for maintenance of intact epithelial barrier and inflammation., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Type 3 innate lymphoid cells (ILC3s) are involved in maintenance of mucosal homeostasis; however, their role in immunoregulation has been unknown. Immature transitional regulatory B (itBreg) cells are innate-like B cells with immunosuppressive properties, and the in vivo mechanisms by which they are induced have not been fully clarified., Objective: We aimed to investigate the ILC3-B-cell interaction that probably takes place in human tonsils., Methods: ILC3s were isolated from peripheral blood and palatine tonsils, expanded, and cocultured with naive B cells. Tonsillar ILC3s and regulatory B cells were visualized with immunofluorescence histology. ILC3 frequencies were measured in tonsil tissue of allergic and nonallergic patients and in peripheral blood of allergic asthmatic patients and healthy control subjects., Results: A mutually beneficial relationship was revealed between ILC3s and B cells: ILC3s induced IL-15 production in B cells through B cell-activating factor receptor, whereas IL-15, a potent growth factor for ILC3s, induced CD40 ligand (CD40L) expression on circulating and tonsillar ILC3s. IL-15-activated CD40L + ILC3s helped B-cell survival, proliferation, and differentiation of IL-10-secreting, PD-L1-expressing functional itBreg cells in a CD40L- and B cell-activating factor receptor-dependent manner. ILC3s and regulatory B cells were in close connection with each other in palatine tonsils. ILC3 frequency was reduced in tonsil tissue of allergic patients and in peripheral blood of allergic asthmatic patients., Conclusion: Human CD40L + ILC3s provide innate B-cell help and are involved in an innate immunoregulatory mechanism through induction of itBreg cell differentiation, which takes place in palatine tonsils in vivo. This mechanism, which can contribute to maintenance of immune tolerance, becomes insufficient in allergic diseases., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Allergic rhinitis (AR) is characterized by mucosal inflammation, driven by activated immune cells. Mast cells and T H 2 cells might decrease epithelial barrier integrity in AR, maintaining a leaky epithelial barrier., Objective: We sought to investigate the role of histamine and T H 2 cells in driving epithelial barrier dysfunction in AR., Methods: Air-liquid interface cultures of primary nasal epithelial cells were used to measure transepithelial electrical resistance, paracellular flux of fluorescein isothiocyanate-dextran 4 kDa, and mRNA expression of tight junctions. Nasal secretions were collected from healthy control subjects, AR patients, and idiopathic rhinitis patients and were tested in vitro. In addition, the effect of activated T H 1 and T H 2 cells, mast cells, and neurons was tested in vitro. The effect of IL-4, IL-13, IFN-γ, and TNF-α on mucosal permeability was tested in vivo., Results: Histamine as well as nasal secretions of AR but not idiopathic rhinitis patients rapidly decreased epithelial barrier integrity in vitro. Pretreatment with histamine receptor-1 antagonist, azelastine prevented the early effect of nasal secretions of AR patients on epithelial integrity. Supernatant of activated T H 1 and T H 2 cells impaired epithelial integrity, while treatment with anti-TNF-α or anti-IL-4Rα monoclonal antibodies restored the T H 1- and T H 2-induced epithelial barrier dysfunction, respectively. IL-4, IFN-γ, and TNF-α enhanced mucosal permeability in mice. Antagonizing IL-4 prevented mucosal barrier disruption and tight junction downregulation in a mouse model of house dust mite allergic airway inflammation., Conclusions: Our data indicate a key role for allergic inflammatory mediators in modulating nasal epithelial barrier integrity in the pathophysiology in AR., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Bronchial epithelial barrier leakiness and type 2 innate lymphoid cells (ILC2s) have been separately linked to asthma pathogenesis; however, the influence of ILC2s on the bronchial epithelial barrier has not been investigated previously., Objective: We investigated the role of ILC2s in the regulation of bronchial epithelial tight junctions (TJs) and barrier function both in bronchial epithelial cells of asthmatic patients and healthy subjects and general innate lymphoid cell- and ILC2-deficient mice., Methods: Cocultures of human ILC2s and bronchial epithelial cells were used to determine transepithelial electrical resistance, paracellular flux, and TJ mRNA and protein expressions. The effect of ILC2s on TJs was examined by using a murine model of IL-33-induced airway inflammation in wild-type, recombination-activating gene 2 (Rag2) -/- , Rag2 -/- Il2rg -/- , and Rora sg/sg mice undergoing bone marrow transplantation to analyze the in vivo relevance of barrier disruption by ILC2s., Results: ILC2s significantly impaired the epithelial barrier, as demonstrated by reduced transepithelial electrical resistance and increased fluorescein isothiocyanate-dextran permeability in air-liquid interface cultures of human bronchial epithelial cells. This was in parallel to decreased mRNAs and disrupted protein expression of TJ proteins and was restored by neutralization of IL-13. Intranasal administration of recombinant IL-33 to wild-type and Rag2 -/- mice lacking T and B cells triggered TJ disruption, whereas Rag2 -/- Il2rg -/- and Rora sg/sg mice undergoing bone marrow transplantation that lack ILC2s did not show any barrier leakiness. Direct nasal administration of IL-13 was sufficient to induce deficiency in the TJ barrier in the bronchial epithelium of mice in vivo., Conclusion: These data highlight an essential mechanism in asthma pathogenesis by demonstrating that ILC2s are responsible for bronchial epithelial TJ barrier leakiness through IL-13., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

The prevalence of IgE-mediated food allergy is an increasing public health concern effecting millions of persons worldwide. The current standard of treatment is strict avoidance of the offending food or foods, and to date, there are no regulatory approved treatments for food allergy. A significant amount of research has been directed at various forms of food immunotherapy, including oral, sublingual, and epicutaneous delivery routes. Although oral immunotherapy has shown the greatest promise for efficacy in terms of the amount of protein that can be ingested, it has also demonstrated less tolerability and a less favorable safety profile compared with sublingual immunotherapy and epicutaneous immunotherapy, which offers the least protection but has the best safety and tolerability profile. Studies have been conducted with adding adjuvants and anti-IgE to enhance either the efficacy or safety of food immunotherapy. Multiple concepts of food immunotherapy beyond these first-generation treatments are in either animal or early phase 1 studies., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

Although oral tolerance is the normal physiologic response to ingested antigens, a breakdown in this process appears to have occurred in the past 2 decades, leading to an increasing prevalence of sensitization to food allergens. Over the past decade, basic research has intensified in an attempt to better understand the mechanisms leading to sensitization and disease versus desensitization and short- and long-term tolerance. In this review we assess various factors that can influence tissue and immune responses to food antigens, the current understanding of immune tolerance development, the role of the gastrointestinal microbiota, and current knowledge regarding immunologic mechanisms involved in desensitization and sustained unresponsiveness, although perhaps the latter is more appropriately termed remission., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Childhood exposure to a farm environment has been shown to protect against the development of inflammatory diseases, such as allergy, asthma, and inflammatory bowel disease., Objective: We sought to investigate whether both exposure to microbes and exposure to structures of nonmicrobial origin, such as the sialic acid N-glycolylneuraminic acid (Neu5Gc), might play a significant role., Methods: Exposure to Neu5Gc was evaluated by quantifying anti-Neu5Gc antibody levels in sera of children enrolled in 2 farm studies: the Prevention of Allergy Risk factors for Sensitization in Children Related to Farming and Anthroposophic Lifestyle (PARSIFAL) study (n = 299) and the Protection Against Allergy Study in Rural Environments (PASTURE) birth cohort (cord blood [n = 836], 1 year [n = 734], 4.5 years [n = 700], and 6 years [n = 728]), and we associated them with asthma and wheeze. The effect of Neu5Gc was examined in murine airway inflammation and colitis models, and the role of Neu5Gc in regulating immune activation was assessed based on helper T-cell and regulatory T-cell activation in mice., Results: In children anti-Neu5Gc IgG levels correlated positively with living on a farm and increased peripheral blood forkhead box protein 3 expression and correlated inversely with wheezing and asthma in nonatopic subjects. Exposure to Neu5Gc in mice resulted in reduced airway hyperresponsiveness and inflammatory cell recruitment to the lung. Furthermore, Neu5Gc administration to mice reduced the severity of a colitis model. Mechanistically, we found that Neu5Gc exposure reduced IL-17 + T-cell numbers and supported differentiation of regulatory T cells., Conclusions: In addition to microbial exposure, increased exposure to non-microbial-derived Neu5Gc might contribute to the protective effects associated with the farm environment., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Of the many possible hypotheses that explain the recent increase in childhood food allergy (FA), the dual-allergen exposure hypothesis has been the most extensively investigated. This chapter serves as a review and update on the prevention of FA and focuses on recently published randomized controlled trials exploring the efficacy of oral tolerance induction in infancy for the prevention of FA. As a result of these RCTs, National Institutes of Health recommendations now actively encourage the early introduction of peanut for the prevention of peanut allergy, and other countries/settings recommend the inclusion of potential common food allergens, including peanut and egg, in complementary feeding regimens commencing at approximately 6 months but not before 4 months of age. Further studies that explore the efficacy of oral tolerance induction to other common food allergens and that focus on optimal timing, duration, and adherence are required., (Copyright © 2017. Published by Elsevier Inc.)

Allergen immunotherapy (AIT) is an effective treatment strategy for allergic diseases and has been used for more than 100 years. In recent years, however, the expectations on concepts, conduct, statistical evaluation, and reporting have developed significantly. Products have undergone dose-response and confirmative studies in adults and children to provide evidence for the optimal dosage, safety, and efficacy of AIT vaccines using subcutaneous and sublingual delivery pathways in large patient cohorts, ensuring solid conclusions to be drawn from them for the advantage of patients and societies alike. Those standards should be followed today, and products answering to them should be preferred over others lacking optimization and proof of efficacy and safety. Molecular and cellular mechanisms of AIT include early mast cell and basophil desensitization effects, regulation of T- and B-cell responses, regulation of IgE and IgG 4 production, and inhibition of responses from eosinophils, mast cells, and basophils in the affected tissues. There were many developments to improve vaccination strategies, demonstration of new molecules involved in molecular mechanisms, and demonstration of new biomarkers for AIT during the last few years. The combination of probiotics, vitamins, and biological agents with AIT is highlighting current advances. Development of allergoids and recombinant and hypoallergenic vaccines to skew the immune response from IgE to IgG 4 and regulation of dendritic cell, mast cell, basophil, innate lymphoid cell, T-cell, and B-cell responses to allergens are also discussed in detail., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Field clinical trials of pollen allergy are affected by the impossibility of predicting and determining individual allergen exposure because of many factors (eg, pollen season, atmospheric variations, pollutants, and lifestyles). Environmental exposure chambers, delivering a fixed amount of allergen in a controlled environmental setting, can overcome these limitations. Environmental exposure chambers are currently already used in phase 2, 3, and even 4 trials. Unfortunately, few chambers exist in the world, and this makes it difficult to perform large, multicenter clinical trials. The new Global Allergy and Asthma European Network (GA 2 LEN) mobile exposure chamber is a step forward because the mobility of the chamber makes it convenient for patients to participate in clinical testing., Objective: This study was made to validate the reproducibility, sensitivity, and specificity of the results obtained in the new GA 2 LEN chamber., Methods: Seventy-two adult patients (19-61 years old) with allergic rhinitis with or without asthma caused by grass pollen were included in different clinical validation tests. Total symptom scores and total nasal symptom scores were recorded at time zero (0) and every 10 minutes during exposures, along with nasal and respiratory parameters., Results: Exposure tests confirmed the reproducibility between subsequent runs and the sensitivity (P < .00001 vs patients exposed to placebo) and specificity (very low score in nonallergic subjects) in the GA 2 LEN chamber. No adverse reactions were recorded during the tests., Conclusions: The mobility of the GA 2 LEN chamber provides a new, potentially effective, and safe way of generating reliable data in allergy multicenter clinical trials., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Asthma, rhinitis, and eczema are complex diseases with multiple genetic and environmental factors interlinked through IgE-associated and non-IgE-associated mechanisms. Mechanisms of the Development of ALLergy (MeDALL; EU FP7-CP-IP; project no: 261357; 2010-2015) studied the complex links of allergic diseases at the clinical and mechanistic levels by linking epidemiologic, clinical, and mechanistic research, including in vivo and in vitro models. MeDALL integrated 14 European birth cohorts, including 44,010 participants and 160 cohort follow-ups between pregnancy and age 20 years. Thirteen thousand children were prospectively followed after puberty by using a newly standardized MeDALL Core Questionnaire. A microarray developed for allergen molecules with increased IgE sensitivity was obtained for 3,292 children. Estimates of air pollution exposure from previous studies were available for 10,000 children. Omics data included those from historical genome-wide association studies (23,000 children) and DNA methylation (2,173), targeted multiplex biomarker (1,427), and transcriptomic (723) studies. Using classical epidemiology and machine-learning methods in 16,147 children aged 4 years and 11,080 children aged 8 years, MeDALL showed the multimorbidity of eczema, rhinitis, and asthma and estimated that only 38% of multimorbidity was attributable to IgE sensitization. MeDALL has proposed a new vision of multimorbidity independent of IgE sensitization, and has shown that monosensitization and polysensitization represent 2 distinct phenotypes. The translational component of MeDALL is shown by the identification of a novel allergic phenotype characterized by polysensitization and multimorbidity, which is associated with the frequency, persistence, and severity of allergic symptoms. The results of MeDALL will help integrate personalized, predictive, preventative, and participatory approaches in allergic diseases., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Tight junctions (TJs) form a barrier on the apical side of neighboring epithelial cells in the bronchial mucosa. Changes in their integrity might play a role in asthma pathogenesis by enabling the paracellular influx of allergens, toxins, and microbes to the submucosal tissue., Objective: The regulation of bronchial epithelial TJs by T H 2 cells and their cytokines and their involvement in epigenetic regulation of barrier function were investigated., Methods: The expression, regulation, and function of TJs were determined in air-liquid interface (ALI) cultures of control and asthmatic primary human bronchial epithelial cells (HBECs) by means of analysis of transepithelial electrical resistance, paracellular flux, mRNA expression, Western blotting, and immunofluorescence staining., Results: HBECs from asthmatic patients showed a significantly low TJ integrity in ALI cultures compared with HBECs from healthy subjects. T H 2 cell numbers and levels of their cytokines, IL-4 and IL-13, decreased barrier integrity in ALI cultures of HBECs from control subjects but not in HBECs from asthmatic patients. They induced a physical separation of the TJs of adjacent cells in immunofluorescence staining of the TJ molecules occludin and zonula occludens-1. We observed that expression of histone deacetylases (HDACs) 1 and 9, and Silent information regulator genes (sirtuins [SIRTs]) 6 and 7 were significantly high in HBECs from asthmatic patients. IL-4 and IL-13 significantly increased the expression of HDACs and SIRTs. The role of HDAC activation on epithelial barrier leakiness was confirmed by HDAC inhibition, which improved barrier integrity through increased synthesis of TJ molecules in epithelium from asthmatic patients to the level seen in HBECs from control subjects., Conclusion: Our data demonstrate that barrier leakiness in asthmatic patients is induced by T H 2 cells, IL-4, and IL-13 and HDAC activity. The inhibition of endogenous HDAC activity reconstitutes defective barrier by increasing TJ expression., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

There have been extensive developments on cellular and molecular mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections during the last few years. Better understanding the functions, reciprocal regulation, and counterbalance of subsets of immune and inflammatory cells that interact through interleukins, interferons, TNF-α, and TGF-β offer opportunities for immune interventions and novel treatment modalities in the era of development of biological immune response modifiers particularly targeting these molecules or their receptors. More than 60 cytokines have been designated as interleukins since the initial discoveries of monocyte and lymphocyte interleukins (called IL-1 and IL-2, respectively). Studies of transgenic or gene-deficient mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided essential information about their functions. Here we review recent developments on IL-1 to IL-38, TNF-α, TGF-β, and interferons. We highlight recent advances during the last few years in this area and extensively discuss their cellular sources, targets, receptors, signaling pathways, and roles in immune regulation in patients with allergy and asthma and other inflammatory diseases., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Atopic dermatitis (AD) is a complex skin disease frequently associated with other diseases of the atopic diathesis. Recent evidence supports the concept that AD can also recognize other comorbidities, such as chronic inflammatory bowel or cardiovascular diseases. These comorbidities might result from chronic cutaneous inflammation or from a common, yet-to-be-defined immunologic background leading to immune deviations. The activation of immune cells and their migration to the skin play an essential role in the pathogenesis of AD. In patients with AD, an underlying immune deviation might result in higher susceptibility of the skin to environmental factors. There is a high unmet medical need to define immunologic endotypes of AD because it has significant implications on upcoming stratification of the phenotype of AD and the resulting targeted therapies in the development of precision medicine. This review article emphasizes studies on environmental factors affecting AD development and novel biological agents used in the treatment of AD. Best evidence of the clinical efficacy of novel immunologic approaches using biological agents in patients with AD is available for the anti-IL-4 receptor α-chain antibody dupilumab, but a number of studies are currently ongoing with other specific antagonists to immune system players. These targeted molecules can be expressed on or drive the cellular players infiltrating the skin (eg, T lymphocytes, dendritic cells, or eosinophils). Such approaches can have immunomodulatory and thereby beneficial clinical effects on the overall skin condition, as well as on the underlying immune deviation that might play a role in comorbidities. An effect of these immunologic treatments on pruritus and the disturbed microbiome in patients with AD has other potential consequences for treatment., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

This review highlights some of the advances in mechanisms of allergic disease, particularly anaphylaxis, including food allergy, drug hypersensitivity, atopic dermatitis (AD), allergic conjunctivitis, and airway diseases. During the last year, a mechanistic advance in food allergy was achieved by focusing on mechanisms of allergen sensitization. Novel biomarkers and treatment for mastocytosis were presented in several studies. Novel therapeutic approaches in the treatment of atopic dermatitis and psoriasis showed that promising supplementation of the infant's diet in the first year of life with immunoactive prebiotics might have a preventive role against early development of AD and that therapeutic approaches to treat AD in children might be best directed to the correction of a TH2/TH1 imbalance. Several studies were published emphasizing the role of the epithelial barrier in patients with allergic diseases. An impaired skin barrier as a cause for sensitization to food allergens in children and its relationship to filaggrin mutations has been an important development. Numerous studies presented new approaches for improvement of epithelial barrier function and novel biologicals used in the treatment of inflammatory skin and eosinophilic diseases. In addition, novel transcription factors and signaling molecules that can develop as new possible therapeutic targets have been reported., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

In this consensus document we summarize the current knowledge on major asthma, rhinitis, and atopic dermatitis endotypes under the auspices of the PRACTALL collaboration platform. PRACTALL is an initiative of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma & Immunology aiming to harmonize the European and American approaches to best allergy practice and science. Precision medicine is of broad relevance for the management of asthma, rhinitis, and atopic dermatitis in the context of a better selection of treatment responders, risk prediction, and design of disease-modifying strategies. Progress has been made in profiling the type 2 immune response-driven asthma. The endotype driven approach for non-type 2 immune response asthma, rhinitis, and atopic dermatitis is lagging behind. Validation and qualification of biomarkers are needed to facilitate their translation into pathway-specific diagnostic tests. Wide consensus between academia, governmental regulators, and industry for further development and application of precision medicine in management of allergic diseases is of utmost importance. Improved knowledge of disease pathogenesis together with defining validated and qualified biomarkers are key approaches to precision medicine., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Tight junction (TJ) defects have recently been associated with asthma and chronic rhinosinusitis. The expression, function, and regulation of nasal epithelial TJs remain unknown in patients with allergic rhinitis (AR)., Objective: We investigated the expression, function, and regulation of TJs in the nasal epithelium of patients with house dust mite (HDM)-induced AR and in an HDM-induced murine model of allergic airway disease., Methods: Air-liquid interface cultures of primary nasal epithelial cells of control subjects and patients with HDM-induced AR were used for measuring transepithelial resistance and passage to fluorescein isothiocyanate-dextran 4 kDa (FD4). Ex vivo transtissue resistance and FD4 permeability of nasal mucosal explants were measured. TJ expression was evaluated by using real-time quantitative PCR and immunofluorescence. In addition, the effects of IL-4, IFN-γ, and fluticasone propionate (FP) on nasal epithelial cells were investigated in vitro. An HDM murine model was used to study the effects of allergic inflammation and FP treatment on transmucosal passage of FD4 in vivo., Results: A decreased resistance in vitro and ex vivo was found in patients with HDM-induced AR, with increased FD4 permeability and reduced occludin and zonula occludens-1 expression. AR symptoms correlated inversely with resistance in patients with HDM-induced AR. In vitro IL-4 decreased transepithelial resistance and increased FD4 permeability, whereas IFN-γ had no effect. FP prevented IL-4-induced barrier dysfunction in vitro. In an HDM murine model FP prevented the allergen-induced increased mucosal permeability., Conclusion: We found impaired nasal epithelial barrier function in patients with HDM-induced AR, with lower occludin and zonula occludens-1 expression. IL-4 disrupted epithelial integrity in vitro, and FP restored barrier function. Better understanding of nasal barrier regulation might lead to a better understanding and treatment of AR., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

This article continues the comprehensive international consensus (ICON) statement on allergen immunotherapy (AIT). The initial article also recently appeared in the Journal. The conclusions below focus on key mechanisms of AIT-triggered tolerance, requirements in allergen standardization, AIT cost-effectiveness, and regulatory guidance. Potential barriers to and facilitators of the use of AIT are described in addition to future directions. International allergy specialists representing the European Academy of Allergy and Clinical Immunology; the American Academy of Allergy, Asthma & Immunology; the American College of Allergy, Asthma and Immunology; and the World Allergy Organization critically reviewed the existing literature and prepared this summary of recommendations for best AIT practice. The authors contributed equally and reached consensus on the statements presented herein., (Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)