Detection of Food Allergens in School and Home Environments of Elementary Students

Different airborne particulates trigger distinct immune pathways leading to peanut allergy in a mouse model

BACKGROUND

Environmental exposure to peanut through non-oral routes is a risk factor for peanut allergy. Early-life exposure to air pollutants, including particulate matter (PM), is associated with sensitization to foods through unknown mechanisms. We investigated whether PM promotes sensitization to environmental peanut and the development of peanut allergy in a mouse model.

METHODS

C57BL/6J mice were co-exposed to peanut and either urban particulate matter (UPM) or diesel exhaust particles (DEP) via the airways and assessed for peanut sensitization and development of anaphylaxis following peanut challenge. Peanut-specific CD4+ T helper (Th) cell responses were characterized by flow cytometry and Th cytokine production. Mice lacking select innate immune signaling genes were used to study mechanisms of PM-induced peanut allergy.

RESULTS

Airway co-exposure to peanut and either UPM- or DEP-induced systemic sensitization to peanut and anaphylaxis following peanut challenge. Exposure to UPM or DEP triggered activation and migration of lung dendritic cells to draining lymph nodes and induction of peanut-specific CD4+ Th cells. UPM- and DEP-induced distinct Th responses, but both stimulated expansion of T follicular helper (Tfh) cells essential for peanut allergy development. MyD88 signaling was critical for UPM- and DEP-induced peanut allergy, whereas TLR4 signaling was dispensable. DEP-induced peanut allergy and Tfh-cell differentiation depended on IL-1 but not IL-33 signaling, whereas neither cytokine alone was necessary for UPM-mediated sensitization.

CONCLUSION

Environmental co-exposure to peanut and PM induces peanut-specific Tfh cells and peanut allergy in mice.

Standardization of Food Allergen Measurements Using Multiplex Array Technology

Multiplex suspension array technology enables multiple protein analytes to be measured in a single assay. In this chapter, we describe a polystyrene bead-based fluorescent multiplex array for quantitative measurements of specific food allergens. The array uses monoclonal antibodies for allergen detection and purified allergens as reference standards. Each component of the array can be standardized. The array measures up to 17 foods that are regulated in the United States, the European Union, and Japan.

Understanding food allergy through neuroimmune interactions in the gastrointestinal tract

Food allergies are adverse immune reactions to food proteins in the absence of oral tolerance, and the incidence of allergies to food, including peanut, cow's milk, and shellfish, has been increasing globally. Although advancements have been made toward understanding the contributions of the type 2 immune response to allergic sensitization, crosstalk between these immune cells and neurons of the enteric nervous system is an area of emerging interest in the pathophysiology of food allergy, given the close proximity of neuronal cells of the enteric nervous system and type 2 effector cells, including eosinophils and mast cells. At mucosal sites, such as the gastrointestinal tract, neuroimmune interactions contribute to the sensing and response to danger signals from the epithelial barrier. This communication is bidirectional, as immune cells express receptors for neuropeptides and transmitters, and neurons express cytokine receptors, allowing for the detection of and response to inflammatory insults. In addition, it seems that neuromodulation of immune cells including mast cells, eosinophils, and innate lymphoid cells is critical for amplification of the type 2 allergic immune response. As such, neuroimmune interactions may be critical targets for future food allergy therapies. This review evaluates the contributions of local enteric neuroimmune interactions to the underlying immune response in food allergy and discusses considerations for future investigations into targeting neuroimmune pathways for treatment of food allergies.

Environmental Exposure to Foods as a Risk Factor for Food Allergy

PURPOSE OF REVIEW

Many factors have been reported to contribute to the development of food allergy. Here, we summarize the role of environmental exposure to foods as a major risk factor for developing food allergy.

RECENT FINDINGS

Peanut proteins are detectable and biologically active in household environments, where infants spend a majority of their time, providing an environmental source of allergen exposure. Recent evidence from clinical studies and mouse models suggests both the airway and skin are routes of exposure that lead to peanut sensitization. Environmental exposure to peanut has been clearly associated with the development of peanut allergy, although other factors such as genetic predisposition, microbial exposures, and timing of oral feeding of allergens also likely contribute. Future studies should more comprehensively assess the contributions of each of these factors for a variety of food allergens to provide more clear targets for prevention of food allergy.

Impact of the exposome on food allergy development

PURPOSE OF REVIEW

The increasing global prevalence of food allergy indicates that environmental exposures are likely contributing to food allergy development. This review summarizes recent studies on how specific factors within the external exposome may impact the development of food allergy.

RECENT FINDINGS

There is strong evidence that nonoral exposure to food allergens within the living environment is a risk factor for food sensitization and food allergy. The role of air pollution in food allergy development remains unclear, as cohort studies have not found consistent relationships between air pollutant exposure and food sensitization. Early-life microbial exposures linked to a rural lifestyle are likely protective against food allergy development, possibly through alteration of the infant microbiome. In contrast, factors associated with urbanization and decreased exposure to microbes may contribute to food allergy development. Recent studies on the role of residential greenness in food allergy development suggest either no relationship or a possible increased risk for food allergy.

SUMMARY

The external exposome comprises a number of exposures that can modify food allergy risk. Improved understanding of how complex environmental exposures interact with genetic factors will be necessary for developing effective interventions aimed at preventing food allergy development in children.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Intake of allergenic foods at 1.5 years and 3 years of age in a general child population in Japan: a cross-sectional study

BACKGROUND

Recent studies indicate that the timing of introduction of potentially allergenic food is crucial for the development of food allergy in children. This cross-sectional study aimed to clarify the reality of allergen food intake in a general population of young children in Japan.

METHODS

A questionnaire survey of caregivers was conducted at health checkups for 1.5-year (18-month)-old and 3-year-old children in the fall of 2020. The caregivers were asked about (1) the presence/absence of allergic disease symptoms based on the ISAAC questionnaire, and (2) foods that caregivers avoided giving their children. Ordinal logistic regression analyses were periformed to determine factors associated with food avoidance.

RESULTS

Questionnaires were distributed to 1720 caregivers, and 1603 (93%) responded. The responders consisted of 771 and 832 caregivers who participated in 1.5-year-old and 3-year-old checkups, respectively. The prevalence of allergic diseases was comparable to recent epidemiological studies in Japan, indicating that the population may be representative. At 1.5 years old, more than 50% of the children were not exposed to peanuts, tree nuts, fish eggs, shellfish, and buckwheat. At 3 years old, the avoidance rates of the foods had decreased but were still between 18.8% and 32.0%. On the other hand, the avoidance rates of chicken egg and cow's milk, the top 2 common allergenic foods in Japan, were much lower at 2.8% and 1.5% at 1.5 years, and they decreased to 1.4% and 0.7% at 3 years old, respectively. Ordinal logistic analysis showed that avoidance of chicken egg, cow's milk, and wheat was associated with food allergy diagnosis and chicken egg avoidance with eczema, but avoidance of other foods showed no associations with any risk factors for food allergy.

CONCLUSION

Caregivers avoided giving various foods, independent of allergy risk factors, to their young children. Since delayed introduction of an allergenic food has been reported to increase the risk of developing an allergy to the food, the results warrant future investigation of the development of food allergies in relation to current eating habits and recommendations.

Food Allergies in Inner-City Schools: Addressing Disparities and Improving Management

OBJECTIVE

Food allergy (FA) affects approximately 8% of children in the United States. Management comprises both preventing and treating allergic reactions, which poses unique challenges in the inner-city school setting. In this article, we review the epidemiology of FA in school-aged children and management challenges and opportunities specific to the inner-city population.

DATA SOURCES

A literature search of the PubMed database was performed to identify published literature on FA epidemiology, FA management, school policies, disparities, inner-city, race, ethnicity, and socioeconomic status.

STUDY SELECTIONS

Relevant articles on FA management best practices and challenges in schools, with a particular emphasis on inner-city schools and populations and socioeconomic, racial, and ethnic disparities, were reviewed in detail.

RESULTS

Disparities in FA prevalence, management, and treatment exist. Additional research is needed to better characterize these disparities and elucidate the mechanisms leading to them. There is a lack of evidence-based interventions for the prevention and treatment of food allergic reactions in schools and specifically in inner-city schools, in which a greater proportion of students may rely on school food.

CONCLUSION

There are opportunities for partnership among health care providers, schools, and communities to address unmet needs in FA management and disparities in the inner-city school setting.