Allergic sensitization: host-immune factors

Exploring the Complex Interplay of Obesity, Allergic Diseases, and Sleep-Disordered Breathing in Children

This narrative review study investigates the correlations between obesity, allergies, and sleep-disordered breathing in pediatric populations. Searches for pertinent articles were conducted on the Medline PubMed Advanced Search Builder, Scopus, and Web of Science databases from unlimited to April 2024. Sleep-disordered breathing causes repeated upper airway obstructions, leading to apneas and restless sleep. Childhood obesity, which affects around 20% of children, is often associated with sleep-disordered breathing and allergies such as asthma and allergic rhinitis. It is distinguished between diet-induced obesity (resulting from excess of diet and physical inactivity) and genetic obesity (such as is seen in Down syndrome and Prader-Willi syndrome). In children with diet-induced obesity, chronic inflammation linked to weight can worsen allergies and increase the risk and severity of asthma and rhinitis. Furthermore, the nasal congestion typical of rhinitis can contribute to upper respiratory tract obstruction and obstructive sleep apnea. A vicious circle is created between asthma and sleep-disordered breathing: uncontrolled asthma and sleep-disordered breathing can worsen each other. In children with genetic obesity, despite alterations in the immune system, fewer allergies are observed compared to the broader population. The causes of this reduced allergenicity are unclear but probably involve genetic, immunological, and environmental factors. Additional research is necessary to elucidate the underlying mechanisms. The present narrative review study emphasizes the importance of jointly evaluating and managing allergies, obesity, and obstructive sleep apnea in children considering their close interconnection.

Allergic to bureaucracy? Regulatory allergenicity assessments of novel food: Motivations, challenges, compromises, and possibilities

New sources of proteins are essential to meet the demands of the growing world population and evolving food trends. Assessing the allergenicity of proteins in novel food (NF) poses a significant food safety regulatory challenge. The Codex Alimentarius Commission presented an allergenicity assessment protocol for genetically modified (GM) foods, which can also be adapted for NF. Since no single laboratory test can adequately predict the allergenic potential of NF, the protocol follows a weight-of-evidence approach, evaluated by experts, as part of a risk management process. Regulatory bodies worldwide have adopted this safety protocol, which, among other things, promotes global harmonization. This review unravels the reliability and various motivations, terms, concepts, and approaches of allergenicity assessments, aiming to enhance understanding among manufacturers and the public. Health Canada, Food Safety Commission JAPAN, and Food Standards Australia New Zealand were surveyed, focusing on the European Food Safety Authority and the US Food Safety Administration for examples of scientific opinions regarding allergenicity assessments for novel and GM foods, from 2019 to 2023. According to our findings, current regulatory allergenicity assessments for NF approval primarily rely on literature reviews. Only a few of the NF assessments proactively presented additional tests. We recommend conducting bioinformatic analyses on NF when a panel of experts deems that there is insufficient prior scientific research.

A functional genomics pipeline to identify high-value asthma and allergy CpGs in the human methylome

BACKGROUND

DNA methylation of cytosines at cytosine-phosphate-guanine (CpG) dinucleotides (CpGs) is a widespread epigenetic mark, but genome-wide variation has been relatively unexplored due to the limited representation of variable CpGs on commercial high-throughput arrays.

OBJECTIVES

To explore this hidden portion of the epigenome, this study combined whole-genome bisulfite sequencing with in silico evidence of gene regulatory regions to design a custom array of high-value CpGs. This study focused on airway epithelial cells from children with and without allergic asthma because these cells mediate the effects of inhaled microbes, pollution, and allergens on asthma and allergic disease risk.

METHODS

This study identified differentially methylated regions from whole-genome bisulfite sequencing in nasal epithelial cell DNA from a total of 39 children with and without allergic asthma of both European and African ancestries. This study selected CpGs from differentially methylated regions, previous allergy or asthma epigenome-wide association studies (EWAS), or genome-wide association study loci, and overlapped them with functional annotations for inclusion on a custom Asthma&Allergy array. This study used both the custom and EPIC arrays to perform EWAS of allergic sensitization (AS) in nasal epithelial cell DNA from children in the URECA (Urban Environment and Childhood Asthma) birth cohort and using the custom array in the INSPIRE [Infant Susceptibility to Pulmonary Infections and Asthma Following RSV Exposure] birth cohort. Each CpG on the arrays was assigned to its nearest gene and its promotor capture Hi-C interacting gene and performed expression quantitative trait methylation (eQTM) studies for both sets of genes.

RESULTS

Custom array CpGs were enriched for intermediate methylation levels compared to EPIC CpGs. Intermediate methylation CpGs were further enriched among those associated with AS and for eQTMs on both arrays.

CONCLUSIONS

This study revealed signature features of high-value CpGs and evidence for epigenetic regulation of genes at AS EWAS loci that are robust to race/ethnicity, ascertainment, age, and geography.

Airway Epithelium: A Neglected but Crucial Cell Type in Asthma Pathobiology

The features of allergic asthma are believed to be mediated mostly through the Th2 immune response. In this Th2-dominant concept, the airway epithelium is presented as the helpless victim of Th2 cytokines. However, this Th2-dominant concept is inadequate to fill some of the vital knowledge gaps in asthma pathogenesis, like the poor correlation between airway inflammation and airway remodeling and severe asthma endotypes, including Th2-low asthma, therapy resistance, etc. Since the discovery of type 2 innate lymphoid cells in 2010, asthma researchers started believing in that the airway epithelium played a crucial role, as alarmins, which are the inducers of ILC2, are almost exclusively secreted by the airway epithelium. This underscores the eminence of airway epithelium in asthma pathogenesis. However, the airway epithelium has a bipartite functionality in sustaining healthy lung homeostasis and asthmatic lungs. On the one hand, the airway epithelium maintains lung homeostasis against environmental irritants/pollutants with the aid of its various armamentaria, including its chemosensory apparatus and detoxification system. Alternatively, it induces an ILC2-mediated type 2 immune response through alarmins to amplify the inflammatory response. However, the available evidence indicates that restoring epithelial health may attenuate asthmatic features. Thus, we conjecture that an epithelium-driven concept in asthma pathogenesis could fill most of the gaps in current asthma knowledge, and the incorporation of epithelial-protective agents to enhance the robustness of the epithelial barrier and the combative capacity of the airway epithelium against exogenous irritants/allergens may mitigate asthma incidence and severity, resulting in better asthma control.

Chemical modification by peroxynitrite enhances TLR4 activation of the grass pollen allergen Phl p 5

The chemical modification of aeroallergens by reactive oxygen and nitrogen species (ROS/RNS) may contribute to the growing prevalence of respiratory allergies in industrialized countries. Post-translational modifications can alter the immunological properties of proteins, but the underlying mechanisms and effects are not well understood. In this study, we investigate the Toll-like receptor 4 (TLR4) activation of the major birch and grass pollen allergens Bet v 1 and Phl p 5, and how the physiological oxidant peroxynitrite (ONOO-) changes the TLR4 activation through protein nitration and the formation of protein dimers and higher oligomers. Of the two allergens, Bet v 1 exhibited no TLR4 activation, but we found TLR4 activation of Phl p 5, which increased after modification with ONOO- and may play a role in the sensitization against this grass pollen allergen. We attribute the TLR4 activation mainly to the two-domain structure of Phl p 5 which may promote TLR4 dimerization and activation. The enhanced TLR4 signaling of the modified allergen indicates that the ONOO--induced modifications affect relevant protein-receptor interactions. This may lead to increased sensitization to the grass pollen allergen and thus contribute to the increasing prevalence of allergies in the Anthropocene, the present era of globally pervasive anthropogenic influence on the environment.

Peanut lipids influence the response of bronchial epithelial cells to the peanut allergens Ara h 1 and Ara h 2 by decreasing barrier permeability

Background: Peanut-allergic individuals react upon their first known ingestion of peanuts, suggesting sensitization occurs through non-oral exposure. Increasing evidence suggests that the respiratory tract is a probable site for sensitization to environmental peanuts. However, the response of the bronchial epithelium to peanut allergens has never been explored. Furthermore, food matrix-derived lipids play an important role in allergic sensitization. Objective: To contribute to a better understanding of the mechanisms of allergic sensitization to peanuts via inhalation, by exploring the direct effect of the major peanut allergens Ara h 1 and Ara h 2 and peanut lipids on bronchial epithelial cells. Methods: Polarized monolayers of the bronchial epithelial cell line 16HBE14o- were stimulated apically with peanut allergens and/or peanut lipids (PNL). Barrier integrity, transport of allergens across the monolayers, and release of mediators were monitored. Results: Ara h 1 and Ara h 2 impacted the barrier integrity of the 16HBE14o- bronchial epithelial cells and crossed the epithelial barrier. Ara h 1 also induced the release of pro-inflammatory mediators. PNL improved the barrier function of the cell monolayers, decreased paracellular permeability and reduced the amount of allergens crossing the epithelial layer. Conclusion: Our study provides evidence of the transport of Ara h 1 and Ara h 2 across the airway epithelium, of the induction of a pro-inflammatory milieu, and identifies an important role for PNL in controlling the amount of allergens that can cross the epithelial barrier. These, all together, contribute to a better understanding of the effects of peanuts exposure on the respiratory tract.

A scoping review of asthma and machine learning

OBJECTIVE

The objective of this study was to determine the extent of machine learning (ML) application in asthma research and to identify research gaps while mapping the existing literature.

DATA SOURCES

We conducted a scoping review. PubMed, ProQuest, and Embase Scopus databases were searched with an end date of September 18, 2020.

STUDY SELECTION

DistillerSR was used for data management. Inclusion criteria were an asthma focus, human participants, ML techniques, and written in English. Exclusion criteria were abstract only, simulation-based, not human based, or were reviews or commentaries. Descriptive statistics were presented.

RESULTS

A total of 6,317 potential articles were found. After removing duplicates, and reviewing the titles and abstracts, 102 articles were included for the full text analysis. Asthma episode prediction (24.5%), asthma phenotype classification (16.7%), and genetic profiling of asthma (12.7%) were the top three study topics. Cohort (52.9%), cross-sectional (20.6%), and case-control studies (11.8%) were the study designs most frequently used. Regarding the ML techniques, 34.3% of the studies used more than one technique. Neural networks, clustering, and random forests were the most common ML techniques used where they were used in 20.6%, 18.6%, and 17.6% of studies, respectively. Very few studies considered location of residence (i.e. urban or rural status).

CONCLUSIONS

The use of ML in asthma studies has been increasing with most of this focused on the three major topics (>50%). Future research using ML could focus on gaps such as a broader range of study topics and focus on its use in additional populations (e.g. location of residence).

Supplemental data for this article is available online at http://dx.doi.org/ .

The role of the CBM complex in allergic inflammation and disease

The caspase activation and recruitment domain-coiled-coil (CARD-CC) family of proteins-CARD9, CARD10, CARD11, and CARD14-is collectively expressed across nearly all tissues of the body and is a crucial mediator of immunologic signaling as part of the CARD-B-cell lymphoma/leukemia 10-mucosa-associated lymphoid tissue lymphoma translocation protein 1 (CBM) complex. Dysfunction or dysregulation of CBM proteins has been linked to numerous clinical manifestations known as "CBM-opathies." The CBM-opathy spectrum encompasses diseases ranging from mucocutaneous fungal infections and psoriasis to combined immunodeficiency and lymphoproliferative diseases; however, there is accumulating evidence that the CARD-CC family members also contribute to the pathogenesis and progression of allergic inflammation and allergic diseases. Here, we review the 4 CARD-CC paralogs, as well as B-cell lymphoma/leukemia 10 and mucosa-associated lymphoid tissue lymphoma translocation protein 1, and their individual and collective roles in the pathogenesis and progression of allergic inflammation and 4 major allergic diseases (allergic asthma, atopic dermatitis, food allergy, and allergic rhinitis).

Lack of Ecto-5′-Nucleotidase Protects Sensitized Mice against Allergen Challenge

Ecto-5′-nucleotidase (CD73), the ectoenzyme that together with CD39 is responsible for extracellular ATP hydrolysis and adenosine accumulation, regulates immune/inflammatory processes by controlling innate and acquired immunity cell functions. We previously demonstrated that CD73 is required for the assessment of a controlled allergic sensitization, in mice. Here, we evaluated the response to aerosolized allergen of female-sensitized mice lacking CD73 in comparison with their wild type counterpart. Results obtained show, in mice lacking CD73, the absence of airway hyperreactivity in response to an allergen challenge, paralleled by reduced airway CD23⁺B cells and IL4⁺T cells pulmonary accumulation together with reduced mast cells accumulation and degranulation. Our findings indicate CD73 as a potential therapeutic target for allergic asthma.

6-O-angeloylplenolin inhibits anti-IgE-stimulated human mast cell activation via suppressing calcium influx and ERK phosphorylation

Objectives

Mast cells are important immune cells that primarily localize in the interface between the host and external environment, and protect us from pathogen infection. However, they are also involved in the pathology of allergic diseases such as asthma and atopic dermatitis. A novel S phase kinase-associated protein 1 (SKP1) inhibitor 6-O-angeloylplenolin (6-OAP), was studied with its potential ability to alleviate the anti-IgE-induced inflammatory responses of primary human cultured mast cells (HCMCs) and LAD2 cell line.

Materials and Methods

We isolated the HCMCs from the buffy coat of voluntary blood donors. The effects of 6-OAP on mast cell activation were evaluated by measuring degranulation, cytokine release, migration, calcium influx, and ERK phosphorylation using spectro-fluorescence assay, multiplex cytometric bead assay/ELISA, migration assay, Fluo-4 calcium flux assay, and western blot, respectively.

Results

It was found that 6-OAP exerted anti-inflammatory effects on human mast cells by dose-dependently suppressing the anti-IgE-mediated degranulation and release of cytokines such as proinflammatory cytokines (IL-8 and TNF-α), growth factors (GM-CSF, VEGF, and FGF), and chemokines (CCL2 and CCL3) in HCMC and LAD2 cells. It also suppressed the migration of immature HCMCs induced by CXCL12. Moreover, the process of calcium influx and ERK phosphorylation in activated HCMC cells were inhibited by 6-OAP administration.

Conclusion

Our results showed that 6-OAP inhibited anti-IgE-induced inflammatory responses of human mast cells via suppressing calcium influx and ERK phosphorylation.

Inverse associations between food diversity in the second year of life and allergic diseases

BACKGROUND

The influence of diet in early childhood on later allergic diseases is currently a highly debated research topic. We and others have suggested that an increased diet diversity in the first year of life has a protective effect on the development of allergic diseases.

OBJECTIVE

This follow-up study aimed to investigate associations between diet in the second year of life and later allergic diseases.

METHODS

A total of 1014 children from rural areas in 5 European countries (the Protection against Allergy: Study in Rural Environments or PASTURE birth cohort) were included. Information on feeding practices in their second year of life and allergic diseases were collected up to age 6 years. Multivariate logistic regressions were performed with different models considering reverse causality, such as excluding children with a positive sensitization to egg and those with a positive sensitization to cow's milk at the age of 1 year.

RESULTS

An increased food diversity score during the second year of life was negatively associated with the development of asthma. Consumption of dairy products and eggs in the second year of life found an inverse association with reported allergic outcomes. Consumption of butter was strongly associated with protection against asthma and food sensitization. Egg was inversely associated with atopic dermatitis (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.04-0.77). Yogurt and cow's milk were inversely associated with food allergy (OR for yogurt, 0.05; 95% CI, 0.01-0.55; OR for cow's milk, 0.31; 95% CI, 0.11-0.89).

CONCLUSION

Increased food diversity in the second year of life is inversely associated with the development of asthma, and consumption of dairy products might have a protective effect on allergic diseases.

B Cell Functions in the Development of Type I Allergy and Induction of Immune Tolerance

B cells are key players in the mechanisms underlying allergic sensitization, allergic reactions, and tolerance to allergens. Allergen-specific immune responses are initiated when peptide:MHCII complexes on dendritic cells are recognized by antigen-specific receptors on T cells followed by interactions between costimulatory molecules on the surfaces of B and T cells. In the presence of IL-4, such T-B cell interactions result in clonal expansion and isotype class-switching to IgE in B cells, which will further differentiate into either memory B cells or PCs. Allergic reactions are then triggered upon cross-linking of IgE-FcɛRI complexes on basophils and mast cells, leading to cell degranulation and the release of pro-inflammatory mediators.Mechanisms underlying effective allergen-specific immunotherapy (AIT) involve the induction of Tregs and the secretion of blocking IgG4 antibodies, which together mediate the onset and maintenance of immune tolerance towards non-hazardous environmental antigens. However, the importance of regulatory B cells (Breg) for tolerance induction during AIT has gained more attention lately. Studies in grass pollen- and house dust mite-allergic patients undergoing SCIT reported increased frequencies of IL-10+ Breg cells and a positive correlation between their number and the improvement of clinical symptoms. Thus, Breg are emerging as biomarkers for monitoring tolerance to allergens under natural exposure conditions and during AIT. Further research on the role of other anti-inflammatory cytokines secreted by Breg will help to understand their role in disease development and tolerance induction.

Impact of Probiotic Bacteria on Respiratory Allergy Disorders

Respiratory allergy is a common disease with an increased prevalence worldwide. The effective remedy is still unknown, and a new therapeutic approach is highly desirable. The review elaborates the influence of probiotic bacteria on respiratory allergy prevention and treatment with particular emphasis on the impact of the current methods of their administration – oral and intranasal. The background of the respiratory allergy is complex thus, we focused on the usefulness of probiotics in the alleviation of different allergy factors, in particular involved in pathomechanism, local hypersensitive evidence and the importance of epithelial barrier. In this review, we have shown that (1) probiotic strains may vary in modulatory potential in respiratory allergy, (2) probiotic bacteria are beneficial in oral and intranasal administration, (3) recombinant probiotic bacteria can modulate the course of respiratory allergy.

Immunological Responses to Envenomation

Venoms are complex mixtures of toxic compounds delivered by bite or sting. In humans, the consequences of envenomation range from self-limiting to lethal. Critical host defence against envenomation comprises innate and adaptive immune strategies targeted towards venom detection, neutralisation, detoxification, and symptom resolution. In some instances, venoms mediate immune dysregulation that contributes to symptom severity. This review details the involvement of immune cell subtypes and mediators, particularly of the dermis, in host resistance and venom-induced immunopathology. We further discuss established venom-associated immunopathology, including allergy and systemic inflammation, and investigate Irukandji syndrome as a potential systemic inflammatory response. Finally, this review characterises venom-derived compounds as a source of immune modulating drugs for treatment of disease.

A national cross-sectional study of exposure to outdoor nitrogen dioxide and aeroallergen sensitization in Australian children aged 7-11 years

The prevalence of allergic diseases in Australian children is high, but few studies have assessed the potential role of outdoor air pollution in allergic sensitization. We investigated the association between outdoor air pollution and the prevalence of aeroallergen sensitization in a national cross-sectional study of Australian children aged 7-11 years. Children were recruited from 55 participating schools in 12 Australian cities during 2007-2008. Parents completed a detailed (70-item) questionnaire. Outdoor nitrogen dioxide (NO₂), as a proxy for exposure to traffic-related emissions, was estimated using measurements from regulatory monitors near each school and a national land-use regression (LUR) model. Three averaging periods were assessed, using information on duration of residence at the address, including lifetime, previous (lifetime, excluding the last year), and recent (the last year only). The LUR model was used as an additional source of recent exposure estimates at school and home addresses. Skin prick tests (SPTs) were performed to measure sensitization to eight common aeroallergens. Multilevel logistic regression estimated the association between NO₂ and sensitization (by individual allergens, indoor and outdoor allergens, and all allergens combined), after adjustment for individual- and area-level covariates. In total, 2226 children had a completed questionnaire and SPT. The prevalence of sensitization to any allergen was 44.4%. Sensitization to house dust mites (HDMs) was the most common (36.1%), while sensitization to Aspergillus was the least common (3.4%). Measured mean (±s.d.) NO₂ exposure was between 9 (±2.9) ppb and 9.5 (±3.2) ppb, depending on the averaging period. An IQR (4 ppb) increase in measured previous NO₂ exposure was associated with greater odds of sensitization to HDMs (OR: 1.21, 95% CI: 1.01-1.43, P = 0.035). We found evidence of an association between relatively low outdoor NO₂ concentrations and sensitization to HDMs, but not other aeroallergens, in Australian children aged 7-11 years.

Mast Cells as Regulators of Adaptive Immune Responses in Food Allergy

Mast cells are a critical first line of defense against endogenous and environmental threats. Their participation in innate immunity is well characterized; activation of toll like receptors as well as receptors for complement, adenosine, and a host of other ligands leads to mast cell release of preformed mediators contained within granules along with newly synthesized arachidonic acid metabolites, cytokines, and chemokines. These confer protective effects including the induction of mucus secretion, smooth muscle contraction, and activation of common itch and pain sensations, all of which act to promote expulsion of noxious agents. While their innate immune role as sentinel cells is well established, recent research has brought into focus their separate but also critical function in adaptive immunity particularly in the setting of IgE mediated food allergies. Crosslinking of FcεR1, the high affinity receptor for IgE, when bound to IgE and antigen, triggers the release of the same factors and elicits the same physiologic responses that occur after activation by innate stimuli. Though IgE-activated mast cells are best known for their role in acute allergic reactions, including the most severe manifestation, anaphylaxis, accumulating evidence has suggested an immunoregulatory effect in T cell-mediated immunity, modulating the balance between type 2 immunity and tolerance. In this review, we outline how mast cells act as adjuvants for food antigen driven Th2 cell responses, while curtailing Treg function.

Exacerbation of Allergic Airway Inflammation in Mice Lacking ECTO-5'-Nucleotidase (CD73)

The airways are a target tissue of type I allergies and atopy is the main etiological factor of bronchial asthma. A predisposition to allergy and individual response to allergens are dependent upon environmental and host factors. Early studies performed to clarify the role of extracellular adenosine in the airways highlighted the importance of adenosine-generating enzymes CD73, together with CD39, as an innate protection system against lung injury. In experimental animals, deletion of CD73 has been associated with immune and autoimmune diseases. Our experiments have been performed to investigate the role of CD73 in the assessment of allergic airway inflammation following sensitization. We found that in CD73^−/− mice sensitization, induced by subcutaneous ovalbumin (OVA) administration, increased signs of airway inflammation and atopy developed, characterized by high IgE plasma levels and increased pulmonary cytokines, reduced frequency of lung CD4⁺CD25+Foxp3+ T cells, but without bronchial hyperreactivity, compared to sensitized wild type mice. Our results provide evidence that the lack of CD73 causes an uncontrolled allergic sensitization, suggesting that CD73 is a key molecule at the interface between innate and adaptive immune response. The knowledge of host immune factors controlling allergic sensitization is of crucial importance and might help to find preventive interventions that could act before an allergy develops.

Free Amino Acids in Human Milk: A Potential Role for Glutamine and Glutamate in the Protection Against Neonatal Allergies and Infections

Breastfeeding is indicated to support neonatal immune development and to protect against neonatal infections and allergies. Human milk composition is widely studied in relation to these unique abilities, which has led to the identification of various immunomodulating components in human milk, including various bioactive proteins. In addition to proteins, human milk contains free amino acids (FAAs), which have not been well-studied. Of those, the FAAs glutamate and glutamine are by far the most abundant. Levels of these FAAs in human milk sharply increase during the first months of lactation, in contrast to most other FAAs. These unique dynamics are globally consistent, suggesting that their levels in human milk are tightly regulated throughout lactation and, consequently, that they might have specific roles in the developing neonate. Interestingly, free glutamine and glutamate are reported to exhibit immunomodulating capacities, indicating that these FAAs could contribute to neonatal immune development and to the unique protective effects of breastfeeding. This review describes the current understanding of the FAA composition in human milk. Moreover, it provides an overview of the effects of free glutamine and glutamate on immune parameters relevant for allergic sensitization and infections in early life. The data reviewed provide rationale to study the role of free glutamine and glutamate in human milk in the protection against neonatal allergies and infections.

TGFβ1 mimetic peptide modulates immune response to grass pollen allergens in mice

Background

Transforming growth factor β1 (TGFβ1) is a cytokine that exerts immunosuppressive functions, as reflected by its ability to induce regulatory T (Treg) cell differentiation and inhibit Th1 and Th2 responses. Hence, peptides that mimic the active core domain of TGFβ1 may be promising candidates for modulation of the allergic response. This study aimed to investigate a synthetic TGFβ1 mimetic peptide (TGFβ1‐mim) for its ability to modulate the immune response during allergic sensitization to grass pollen allergens.

Methods

The in vitro action of TGFβ1‐mim was evaluated in human lung epithelial cells, Jurkat cells, and rat basophilic leukemia cells. The in vivo action was evaluated in a murine model of Phl p 5 allergic sensitization. Additionally, the Th2 modulatory response was evaluated in IL‐4 reporter mice.

Results

In vitro, TGFβ1‐mim downregulated TNF‐α production, IL‐8 gene expression, and cytokine secretion, upregulated IL‐10 secretion, and inhibited Phl p 5‐induced basophil degranulation. During Phl p 5 sensitization in mice, TGFβ1‐mim downregulated IL‐2, IL‐4, IL‐5, IL‐13, and IFN‐γ, upregulated IL‐10, and induced Treg cell production. Furthermore, mice treated with TGFβ1‐mim had lower levels of IgE, IgG1, IgG2a and higher levels of IgA antibodies than control mice. In a reporter mouse, the mimetic inhibited Th2 polarization.

Conclusion

The TGFβ1‐mim efficiently modulated various important events that exacerbate the allergic microenvironment, including the production of main cytokines that promote Th1 and Th2 differentiation, and the induction of allergen‐specific regulatory T cells, highlighting its potential use in therapeutic approaches to modulate the immune response toward environmental allergens.

Endocrine Disruptor Bisphenol A (BPA) Triggers Systemic Para-Inflammation and is Sufficient to Induce Airway Allergic Sensitization in Mice

Allergic airway diseases are accompanied by increased permeability and an inflammatory state of epithelial barriers, which are thought to be susceptible to allergen sensitization. Although exogenous drivers (proteases, allergens) of epithelial barrier disruption and sensitization are well studied, endogenous contributors (diet, xenobiotics, hormones, and metabolism) to allergic sensitization are much less understood. Xenoestrogens are synthetic or natural chemical compounds that have the ability to mimic estrogen and are ubiquitous in the food and water supply of developed countries. By interfering with the estrogen produced by the endocrine system, these compounds have the systemic potential to disrupt the homeostasis of multiple tissues. Our study examined the potential of prototypical xenoestrogen bisphenol A (BPA) to disrupt epithelial homeostasis in vitro and promote allergic responses in vivo. We found that BPA exposure in epithelial cultures in vitro significantly inhibited epithelial cell proliferation and wound healing, as well as promoted the expression of the innate alarmin cytokine TSLP in a time-and dose-dependent manner. In vivo, the exposure to BPA through water supply or inhalation induced a systemic para-inflammatory response by promoting the expression of innate inflammatory mediators in the skin, gut, and airway. In a murine tolerogenic antigen challenge model, chronic systemic exposure to BPA was sufficient to induce airway sensitization to innocuous chicken egg ovalbumin in the complete absence of adjuvants. Mechanistic studies are needed to test conclusively whether endocrine disruptors may play an upstream role in allergic sensitization via their ability to promote a para-inflammatory state.

Fish-derived low molecular weight components modify bronchial epithelial barrier properties and release of pro-inflammatory cytokines

The prevalence of fish allergy among fish-processing workers is higher than in the general population, possibly due to sensitization via inhalation and higher exposure. However, the response of the bronchial epithelium to fish allergens has never been explored. Parvalbumins (PVs) from bony fish are major sensitizers in fish allergy, while cartilaginous fish and their PVs are considered less allergenic. Increasing evidence demonstrates that components other than proteins from the allergen source, such as low molecular weight components smaller than 3 kDa (LMC) from pollen, may act as adjuvants during allergic sensitization.

We investigated the response of bronchial epithelial cells to PVs and to LMC from Atlantic cod, a bony fish, and gummy shark, a cartilaginous fish. Polarized monolayers of the bronchial epithelial cell line 16HBE14o- were stimulated apically with fish PVs and/-or the corresponding fish LMC. Barrier integrity, transport of PVs across the monolayers and release of mediators were monitored.

Intact PVs from both the bony and the cartilaginous fish were rapidly internalized by the cells and transported to the basolateral side of the monolayers. The PVs did not disrupt the epithelial barrier integrity nor did they modify the release of proinflammatory cytokines. In contrast, LMC from both fish species modified the physical and immunological properties of the epithelial barrier and the responses differed between bony and cartilaginous fish. While the barrier integrity was lowered by cod LMC 24 h after cell stimulation, it was increased by up to 2.3-fold by shark LMC. Furthermore, LMC from both fish species increased basolateral and apical release of IL-6 and IL-8, while CCL2 release was increased by cod but not by shark LMC.

In summary, our study demonstrated the rapid transport of PVs across the epithelium which may result in their availability to antigen presenting cells required for allergic sensitization. Moreover, different cell responses to LMC derived from bony versus cartilaginous fish were observed, which may play a role in different allergenic potentials of these two fish classes.

Assessment of the potential allergenicity of genetically-engineered food crops

An extensive safety assessment process exists for genetically-engineered (GE) crops. The assessment includes an evaluation of the introduced protein as well as the crop containing the protein with the goal of demonstrating the GE crop is "as-safe-as" non-GE crops in the food supply. One of the evaluations for GE crops is to assess the expressed protein for allergenic potential. Currently, no single factor is recognized as a predictor for protein allergenicity. Therefore, a weight-of-the-evidence approach, which accounts for a variety of factors and approaches for an overall assessment of allergenic potential, is conducted. This assessment includes an evaluation of the history of exposure and safety of the gene(s) source; protein structure (e.g. amino acid sequence identity to human allergens); stability of the protein to pepsin digestion in vitro; heat stability of the protein; glycosylation status; and when appropriate, specific IgE binding studies with sera from relevant clinically allergic subjects. Since GE crops were first commercialized over 20 years ago, there is no proof that the introduced novel protein(s) in any commercialized GE food crop has caused food allergy.

TLR Activation and Allergic Disease: Early Life Microbiome and Treatment

PURPOSE OF REVIEW

Allergy and asthma are growing problems in the developed world. The accelerated increase of these diseases may be related to microbiome modification that leads to aberrant activation of Toll-like receptors (TLRs). Current research supports the concept that changes in microbial communities in early life impact TLR activation, resulting in an altered risk for the development of asthma and allergies.

RECENT FINDINGS

Prenatal and early childhood events that generate microbiome modification are closely related with TLR activation. Early childhood exposure to a rich array of TLR agonists, particularly lipopolysaccharide, strongly predicts protection against allergic disease later in life even when other lifestyle factors are accounted for. Genetic deletion of TLR signaling components in mice results in reduced function of tolerogenic cell populations in the gut. In contrast, weak TLR signaling can promote allergic sensitization later in life. This review summarizes the role of TLR signaling in microbiome-mediated protection against allergy.

Mast Cell Interactions and Crosstalk in Regulating Allergic Inflammation

PURPOSE OF REVIEW

This review summarizes recent findings on mast cell biology with a focus on IgE-independent roles of mast cells in regulating allergic responses.

RECENT FINDINGS

Recent studies have described novel mast cell-derived molecules, both secreted and membrane-bound, that facilitate cross-talk with a variety of immune effector cells to mediate type 2 inflammatory responses. Mast cells are complex and dynamic cells that are persistent in allergy and are capable of providing signals that lead to the initiation and persistence of allergic mechanisms.

Hyaluronan in immune dysregulation and autoimmune diseases

The tissue microenvironment contributes to local immunity and to the pathogenesis of autoimmune diseases - a diverse set of conditions characterized by sterile inflammation, immunity against self-antigens, and destruction of tissues. However, the specific factors within the tissue microenvironment that contribute to local immune dysregulation in autoimmunity are poorly understood. One particular tissue component implicated in multiple autoimmune diseases is hyaluronan (HA), an extracellular matrix (ECM) polymer. HA is abundant in settings of chronic inflammation and contributes to lymphocyte activation, polarization, and migration. Here, we first describe what is known about the size, amount, and distribution of HA at sites of autoimmunity and in associated lymphoid structures in type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Next, we examine the recent literature on HA and its impact on adaptive immunity, particularly in regards to the biology of lymphocytes and Foxp3+ regulatory T-cells (Treg), a T-cell subset that maintains immune tolerance in healthy individuals. We propose that HA accumulation at sites of chronic inflammation creates a permissive environment for autoimmunity, characterized by CD44-mediated inhibition of Treg expansion. Finally, we address potential tools and strategies for targeting HA and its receptor CD44 in chronic inflammation and autoimmunity.

Polydatin inhibits mast cell-mediated allergic inflammation by targeting PI3K/Akt, MAPK, NF-κB and Nrf2/HO-1 pathways

Polydatin(PD) shows anti-allergic inflammatory effect, and this study investigated its underlying mechanisms in in vitro and in vivo models. IgE-mediated passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA) models were used to confirm PD effect in vivo. Various signaling pathway proteins in mast cell were examined. RT-PCR, ELISA and western blotting were applied when appropriate. Activity of Lyn and Fyn kinases in vitro was measured using the Kinase Enzyme System. PD dose-dependently reduced the pigmentation of Evans blue in the PCA model and decreased the concentration of serum histamine in PSA model, and attenuated the degranulation of mast cells without generating cytotoxicity. PD decreased pro-inflammatory cytokine expression (TNF-α, IL-4, IL-1β, and IL-8). PD directly inhibited activity of Lyn and Syk kinases and down-regulated downstream signaling pathway including MAPK, PI3K/AKT and NF-kB. In addition, PD also targets Nrf2/HO-1 pathway to inhibit mast cell-derived allergic inflammatory reactions. In conclusion, the study demonstrates that PD is a possible therapeutic candidate for allergic inflammatory diseases. It directly inhibited activity of Lyn and Syk kinases and down-regulates the signaling pathway of MAPK, PI3K/AKT and NF-κB, and up-regulates the signaling pathway of Nrf2/HO-1 to inhibit the degranulation of mast cells.

The Impact of Sex and Age on the Prevalence of Clinically Relevant Sensitization and Asymptomatic Sensitization in the General Population

The objective of our study was to evaluate the impact of sex and age on the prevalence of sensitization to inhalant allergens. The study was performed as a part of Polish Epidemiology of Allergic Diseases study, and data concerning citizens of Wroclaw were analyzed. The participants were divided into three age groups (6-7, 13-14, and 20-44 years) with a subdivision according to sex. We randomly selected 1409 individuals, 439 people complied; the complete set of tests was performed on 421 of them. We found that 37.7 % of the study population demonstrated sensitization to at least one of the allergens tested. Positive skin tests were found more frequently in males than in females (p = 0.003); among 6-7-year-old children, the sensitization was independent of sex (p = 0.26), while in two other groups, it was higher in males (p = 0.002 and p = 0.03, respectively). Clinically asymptomatic sensitization (AS) was found more often in females than in males (p = 0.04). The higher rate of AS in women was observed only in the two younger age groups, while in the 20-44-year-old group AS did not differ between the sexes (p = 0.72). Female sex hormones may contribute to a later change in the nature of sensitization from clinically asymptomatic to symptomatic. Further studies are needed to confirm the results of our study.

Application of the adverse outcome pathway (AOP) concept to structure the available in vivo and in vitro mechanistic data for allergic sensitization to food proteins

BACKGROUND

The introduction of whole new foods in a population may lead to sensitization and food allergy. This constitutes a potential public health problem and a challenge to risk assessors and managers as the existing understanding of the pathophysiological processes and the currently available biological tools for prediction of the risk for food allergy development and the severity of the reaction are not sufficient. There is a substantial body of in vivo and in vitro data describing molecular and cellular events potentially involved in food sensitization. However, these events have not been organized in a sequence of related events that is plausible to result in sensitization, and useful to challenge current hypotheses. The aim of this manuscript was to collect and structure the current mechanistic understanding of sensitization induction to food proteins by applying the concept of adverse outcome pathway (AOP).

MAIN BODY

The proposed AOP for food sensitization is based on information on molecular and cellular mechanisms and pathways evidenced to be involved in sensitization by food and food proteins and uses the AOPs for chemical skin sensitization and respiratory sensitization induction as templates. Available mechanistic data on protein respiratory sensitization were included to fill out gaps in the understanding of how proteins may affect cells, cell-cell interactions and tissue homeostasis. Analysis revealed several key events (KE) and biomarkers that may have potential use in testing and assessment of proteins for their sensitizing potential.

CONCLUSION

The application of the AOP concept to structure mechanistic in vivo and in vitro knowledge has made it possible to identify a number of methods, each addressing a specific KE, that provide information about the food allergenic potential of new proteins. When applied in the context of an integrated strategy these methods may reduce, if not replace, current animal testing approaches. The proposed AOP will be shared at the www.aopwiki.org platform to expand the mechanistic data, improve the confidence in each of the proposed KE and key event relations (KERs), and allow for the identification of new, or refinement of established KE and KERs.

Current challenges facing the assessment of the allergenic capacity of food allergens in animal models

Food allergy is a major health problem of increasing concern. The insufficiency of protein sources for human nutrition in a world with a growing population is also a significant problem. The introduction of new protein sources into the diet, such as newly developed innovative foods or foods produced using new technologies and production processes, insects, algae, duckweed, or agricultural products from third countries, creates the opportunity for development of new food allergies, and this in turn has driven the need to develop test methods capable of characterizing the allergenic potential of novel food proteins. There is no doubt that robust and reliable animal models for the identification and characterization of food allergens would be valuable tools for safety assessment. However, although various animal models have been proposed for this purpose, to date, none have been formally validated as predictive and none are currently suitable to test the allergenic potential of new foods. Here, the design of various animal models are reviewed, including among others considerations of species and strain, diet, route of administration, dose and formulation of the test protein, relevant controls and endpoints measured.

Differential induction of total IgE by two Salmonella enterica serotypes

The main goal of this study was to establish how the inflammation caused by infection with two different Salmonella enterica serotypes, S. Typhimurium and S. Enteritidis, may lead to the predisposition to allergy as measured by total IgE level in the blood. Infection by S. Typhimurium did not affect the systemic IgE concentration while in S. Enteritidis-infected patients there was a significant 3.5-fold increase. This effect was especially profound in patients >4 years old, with up to the 8-fold increase above the norm. The degree of dysbiosis in these two infections measured with the comparative counts of cultivated bacteria showed an inverse relationship with the IgE concentration. Earlier we reported the elevated level of IL-17 in patients infected by S. Enteritidis. In the current study a significant correlation was found between the concentrations of IL-17 and IgE suggesting a possible role played by this cytokine in triggering the production of IgE in response to S. Enteritidis infection.

Colonization of germ-free mice with a mixture of three lactobacillus strains enhances the integrity of gut mucosa and ameliorates allergic sensitization

Increasing numbers of clinical trials and animal experiments have shown that probiotic bacteria are promising tools for allergy prevention. Here, we analyzed the immunomodulatory properties of three selected lactobacillus strains and the impact of their mixture on allergic sensitization to Bet v 1 using a gnotobiotic mouse model. We showed that Lactobacillus (L.) rhamnosus LOCK0900, L. rhamnosus LOCK0908 and L. casei LOCK0919 are recognized via Toll-like receptor 2 (TLR2) and nucleotide-binding oligomerization domain-containing protein 2 (NOD2) receptors and stimulate bone marrow-derived dendritic cells to produce cytokines in species- and strain-dependent manners. Colonization of germ-free (GF) mice with a mixture of all three strains (Lmix) improved the intestinal barrier by strengthening the apical junctional complexes of enterocytes and restoring the structures of microfilaments extending into the terminal web. Mice colonized with Lmix and sensitized to the Bet v 1 allergen showed significantly lower levels of allergen-specific IgE, IgG1 and IgG2a and an elevated total IgA level in the sera and intestinal lavages as well as an increased transforming growth factor (TGF)-β level compared with the sensitized GF mice. Splenocytes and mesenteric lymph node cells from the Lmix-colonized mice showed the significant upregulation of TGF-β after in vitro stimulation with Bet v 1. Our results show that Lmix colonization improved the gut epithelial barrier and reduced allergic sensitization to Bet v 1. Furthermore, these findings were accompanied by the increased production of circulating and secretory IgA and the regulatory cytokine TGF-β. Thus, this mixture of three lactobacillus strains shows potential for use in the prevention of increased gut permeability and the onset of allergies in humans.

Rhinosinusitis and asthma: a very long engagement

Upper and lower airways may be considered as a unique entity, interested by coexisting inflammatory processes that share common etiopathogenic mechanisms. Previous studies have strongly demonstrated a relationship between rhinosinusitis and asthma. This has led to the introduction of the concept of “United Airways”, which has also been included in the WHO document Allergic Rhinitis and its Impact on Asthma (ARIA); this concept has important consequences also on the treatment of these disorders. To better summarize the evident connection between upper and lower airway disease we decided to describe it as a multilayered construction, each level pointing out more deeply the relationship between these entities.

The contribution of biotechnology toward progress in diagnosis, management, and treatment of allergic diseases

'Biotechnology' has been intuitively used by humans since thousands of years for the production of foods, beverages, and drugs based on the experience without any scientific background. However, the golden era of this discipline emerged only during the second half of the last century. Incredible progresses have been achieved on all fields starting from the industrialization of the production of foods to the discovery of antibiotics, the decipherment of the genetic code, and rational approaches to understand and define the status we now call 'healthy'. The extremely complex interactions between genetic background, life style, and environmental factors influencing our continuously increasing life span have become more and more evident and steadily generate new questions which are only partly answered. Here, we try to summarize the contribution of biotechnology to our understanding, control, and cure of IgE-mediated allergic diseases. We are aware that a review of such a vast topic can never cover all aspects of the progress achieved in the different fields.

Factors determining immunological response to vaccination against tick-borne encephalitis virus in older individuals

We performed a cross-sectional study including 533 individuals (median age 61) from the highly TBE endemic Åland Islands in the archipelago between Sweden and Finland. Blood samples, questionnaires and vaccination records were obtained from all study participants. The aim was to investigate if there was any association between TBEV antibody titer and 12 health-related factors. Measurement of TBEV IgG antibodies was performed using two commercial ELISA assays (Enzygnost and Immunozym), and a third in-house rapid fluorescent focus inhibition test was used to measure TBEV neutralizing antibodies. The age of the individual and the number of vaccine doses were the two most important factors determining the immunological response to vaccination. The response to each vaccine dose declined linearly with increased age. A 35 year age difference corresponds to a vaccine dose increment from 3 to 4 to achieve the same immunological response. Participants previously vaccinated against other flaviviruses had lower odds of being seropositive for neutralizing TBEV antibodies on average, while participants with self-reported asthma had higher odds of being seropositive. By comparing the 3 serological assays we show that the Enzygnost and Immunozym assay differ due to choice of cutoffs, but not in overall accuracy.

Sensitizing properties of proteins: executive summary

The scope of allergy risk is diverse considering the myriad ways in which protein allergenicity is affected by physiochemical characteristics of proteins. The complexity created by the matrices of foods and the variability of the human immune system add additional challenges to understanding the relationship between sensitization potential and allergy disease. To address these and other issues, an April 2012 international symposium was held in Prague, Czech Republic, to review and discuss the state-of-the-science of sensitizing properties of protein allergens. The symposium, organized by the Protein Allergenicity Technical Committee of the International Life Sciences Institute’s Health and Environmental Sciences Institute, featured presentations on current methods, test systems, research trends, and unanswered questions in the field of protein sensitization. A diverse group of over 70 interdisciplinary scientists from academia, government, and industry participated in the symposium. Experts provided overviews on known mechanisms by which proteins in food may cause sensitization, discussed experimental models to predict protein sensitizing potential, and explored whether such experimental techniques may be applicable in regulatory settings. Three accompanying reviews address critical factors and methods for assessing allergic sensitization: 1) food-and protein-related factors; 2) host-specific factors and 3) screening methods, i.e., the ability of experimental models to predict the sensitizing potential of proteins and whether such models are applicable within regulatory settings.

Allergic sensitization: food- and protein-related factors

Presented here are emerging capabilities to precisely measure endogenous allergens in soybean and maize, consideration of food matrices on allergens, and proteolytic activity of allergens. Also examined are observations of global allergy surveys and the prevalence of food allergy across different locales. Allergenic potential is considered in the context of how allergens can be characterized for their biochemical features and the potential for proteins to initiate a specific immune response. Some of the limitations in performing allergen characterization studies are examined. A combination of physical traits of proteins, the molecular interaction between cells and proteins in the human body, and the uniqueness of human culture play a role in understanding and eventually predicting protein allergy potential. The impact of measuring food allergens on determining safety for novel food crops and existing allergenic foods was highlighted with the conclusion that measuring content without the context of clinically relevant thresholds adds little value to safety. These data and findings were presented at a 2012 international symposium in Prague organized by the Protein Allergenicity Technical Committee of the International Life Sciences Institute’s Health and Environmental Sciences Institute.

Allergic sensitization: screening methods

Experimental in silico, in vitro, and rodent models for screening and predicting protein sensitizing potential are discussed, including whether there is evidence of new sensitizations and allergies since the introduction of genetically modified crops in 1996, the importance of linear versus conformational epitopes, and protein families that become allergens. Some common challenges for predicting protein sensitization are addressed: (a) exposure routes; (b) frequency and dose of exposure; (c) dose-response relationships; (d) role of digestion, food processing, and the food matrix; (e) role of infection; (f) role of the gut microbiota; (g) influence of the structure and physicochemical properties of the protein; and (h) the genetic background and physiology of consumers. The consensus view is that sensitization screening models are not yet validated to definitively predict the de novo sensitizing potential of a novel protein. However, they would be extremely useful in the discovery and research phases of understanding the mechanisms of food allergy development, and may prove fruitful to provide information regarding potential allergenicity risk assessment of future products on a case by case basis. These data and findings were presented at a 2012 international symposium in Prague organized by the Protein Allergenicity Technical Committee of the International Life Sciences Institute's Health and Environmental Sciences Institute.