The Epidemiology of Food Allergy in the Global Context

Streamlining basophil activation testing to enable assay miniaturization and automation of sample preparation

BACKGROUND

Numerous studies have demonstrated the capabilities of the basophil activation test (BAT) but various parameters such as a lack of standardization and a time consuming and labor intensive workflow continue to hinder the field to fully leverage the capabilities of this technique. When pediatric patients have to be considered, an additional limitation is related to blood volume consumption.

OBJECTIVES

This work aimed at developing and characterizing a simplified and standardized whole-blood based BAT prototype procedure and at further assessing the feasibility of automating and miniaturizing the developed assay into a 96 well plate format.

METHODS

A dry and room temperature stable reagent technology was used to simplify and standardize BAT. Under optimized conditions, EDTA anticoagulated whole blood samples of non-allergic and allergic donors (<24 h old) together with calcium containing buffer were added to ready-to-use dry reagent tubes or 96 well plates (negative controls, positive controls and allergen tests) containing a 5 color compensation-free antibody panel (CD45-KrO/CD3-PC7/CRTH2-A647/CD203c-PE/CD63-PB). Upon mixing and incubation at 37 °C for 15 min, erythrocytes were lysed and samples were analyzed by flow cytometry without further washing steps. While it is important to precisely control the incubation time to minimize the assay variability, herein, a 15 min incubation time was chosen as it provides a suitable compromise for both the magnitude of basophil activation and the quality of the staining. A Biomek NXP robotic platform (Beckman Coulter) was used for automation and both CD203c and CD63 levels were monitored to characterize basophil reactivity.

RESULTS

This streamlined BAT protocol is no-wash, compensation free and only requires 4 pipetting steps to be completed. The assessment of assay performance characteristics showed wide applicability, satisfactory repeatability and a high degree of standardization as demonstrated by very low intra-assay and inter-operator variabilities (CVs < 10%). Leveraging these technical foundations, it was then proven that this new BAT procedure can easily be transposed into the 96 well plate format, thereby benefiting from a miniaturized format and full automation capabilities. When considering 8 dilution points to characterize the ex vivo basophil reactivity of a given whole blood sample, we found that as little as 5 μL of blood per point could be used.

CONCLUSIONS

A whole blood based and simplified procedure for BAT is proposed. It relies on a dry antibody formulation technology and requires only a few manual steps to be completed. This procedure can also be transposed in a 96 well plate format, fully automated and miniaturized, when sample volume reduction, throughput increase or unattended sample preparation is required.

Preventing immediate-onset food allergy in infants, children and adults: Systematic review protocol

BACKGROUND

More than 17 million people across Europe have allergies to food and the burden of food allergies is increasing. In 2014, the European Academy of Allergy and Clinical Immunology (EAACI) published guidelines for preventing food allergy. Important research has been published since then and it is essential to ensure the guidelines reflect the latest evidence. A systematic review will be undertaken to help prepare new guidelines due to be published in 2020.

METHODS

Eleven bibliographic databases will be searched from inception to 31 October 2019 for randomized controlled trials about any intervention designed to prevent the development of new cases of immediate-type/IgE-mediated food allergy in infants, children and adults. There are few randomized controlled trials about the impact of breastfeeding on food allergy so prospective cohort studies about breastfeeding with at least 1000 participants at general risk or 200 at high risk of food allergy will also be eligible. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach will be used to assess the certainty of the evidence and tabulate summary data. The risk of bias in individual trials will be assessed using the Cochrane risk of bias tool. All data extraction and quality appraisal will be undertaken independently by two reviewers in partnership with a taskforce of EAACI members.

CONCLUSIONS

Preventing food allergy has the potential to improve personal well-being and reduce societal healthcare costs. It is important that forthcoming European guidelines take the latest research into account. Past reviews have tended to focus on single interventions or combined food allergy with other outcomes, making it difficult to draw robust conclusions about potential impacts for policy and practice.

Food allergy among university students: uncharted territory

Background

Food allergy is a growing global health concern, with limited studies conducted in developing countries. High-risk behavior regarding allergies is common among young adults, making them prone to severe allergic reactions. This study aimed to estimate the prevalence of food allergies among Imam Abdulrahman Bin Faisal University (IAU) students and to determine the rate of high-risk behaviors in this group.

Methods

An online survey was conducted among IAU students enrolled between the academic years of 2008 and 2018. The survey addressed food allergies with respect to age of onset, allergy testing, self-injectable epinephrine (SIE) prescription, associated allergic conditions, and attitude and behavior of university students regarding food avoidance and epinephrine use.

Results

In total, 5497 completed surveys were analyzed; 526 participants were clinically diagnosed with allergies to at least one food item. A SIE device was prescribed for only 129 (24.5%) of the diagnosed individuals, of which only 4.7% carried the device at all times. Thirty-nine individuals (30.2%) reported that they and their family members know the proper epinephrine device technique. Strict avoidance of food allergens was reported by 30.2% of the individuals. Associated allergic conditions were observed in 69.3% of the clinically diagnosed individuals.

Conclusion

Food allergies are prevalent among IAU students, with under-prescription of SIE devices. A high rate of high-risk behaviors with respect to food avoidance and carrying SIE was noted. Interventional strategies are needed to mitigate the risk of severe reactions among these university students.

New Perspectives in Food Allergy

The improvement of the knowledge of the pathophysiological mechanisms underlying the tolerance and sensitization to food antigens has recently led to a radical change in the clinical approach to food allergies. Epidemiological studies show a global increase in the prevalence of food allergy all over the world and manifestations of food allergy appear increasingly frequent also in elderly subjects. Environmental and nutritional changes have partly changed the epidemiology of allergic reactions to foods and new food allergic syndromes have emerged in recent years. The deepening of the study of the intestinal microbiota has highlighted important mechanisms of immunological adaptation of the mucosal immune system to food antigens, leading to a revolution in the concept of immunological tolerance. As a consequence, new prevention models and innovative therapeutic strategies aimed at a personalized approach to the patient affected by food allergy are emerging. This review focuses on these new perspectives and their practical implications in the management of food allergy, providing an updated view of this complex pathology.

Study protocol for the Melbourne Infant Study: BCG for Allergy and Infection Reduction (MIS BAIR), a randomised controlled trial to determine the non-specific effects of neonatal BCG vaccination in a low-mortality setting

INTRODUCTION

BCG vaccination reduces all-cause infant mortality in high-mortality settings by more than can be attributed to protection against tuberculosis. This is proposed to result from non-specific protection against non-vaccine targeted ('off-target') infections. There is also evidence that BCG protects against allergic diseases.

METHODS AND ANALYSIS

The Melbourne Infant Study: BCG for Allergy and Infection Reduction is a phase III multicentre, single-blinded, randomised controlled trial. A total of 1438 healthy neonates will be randomised to receive either BCG vaccination or no BCG vaccination in the first 10 days of life. Measures of allergy, eczema, infection and asthma will be obtained from parent-completed questionnaires 3 monthly in the first year and 6 monthly from 1 to 5 years of age, and clinical assessments at 1 and 5 years of age. Biological samples will also be collected for future immunological studies.

ANALYSIS PRIMARY OUTCOME

The proportion of participants with measures of allergy and infection (atopic sensitisation, eczema, lower respiratory tract infection) at 1 and 5 years of age, and asthma at 5 years of age.

SECONDARY OUTCOMES

(1) the proportion of participants with additional measures of allergy, eczema, asthma and infections; (2) medication use for eczema and asthma; (3) the severity and age of onset of eczema and asthma; (4) the number of episodes of infection; (5) hospitalisations for infections and (6) laboratory measures of immune responses.

ETHICS AND DISSEMINATION

This trial has ethical and governance approval from Mercy Health Human Research Ethics Committee (HREC, No. R12-28) and Royal Children's Hospital HREC (No. 33025) with additional governance approval from Barwon Health and St John of God, Geelong, Victoria. Results of this trial will be published in peer-reviewed journals and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT01906853.

Evaluation of the epidemiology of peanut allergy in the United Kingdom

Aims: To describe the epidemiology of peanut allergy (PA) in the UK over the last three decades.Methods: PA patients were identified from the Clinical Practice Research Datalink between 1987 and 2015. Incidence and prevalence of PA were compared between 2000 and 2015. Prevalence and relative risk (RR) of atopic comorbidities, anaphylaxis, adrenaline prescriptions versus matched controls were calculated.Results: Point prevalence of PA in the entire population and those <18 years increased from 31 to 202 and 116 to 635 per 100,000, respectively, between 2000 and 2015. Incidence increased from 8.6 to 18.2 per 100,000. Incidence in 2015 was 105 cases per 100,000 aged 0-4 years versus 13.4 per 100,000 aged 5+ years. Anaphylactic events affected 1.2% of the cases and 0.007% of the controls. The rate of adrenaline prescriptions was 5,910 per 100,000 person-years for PA patients. RRs for asthma, eczema and allergic rhinitis in PA patients versus controls were 4.5 (95% CI 4.2-4.8), 3.2 (3.1-3.4) and 2.6 (2.4-3.0), respectively.Conclusions: The prevalence and incidence of PA increased markedly over the study period. PA was associated with atopic conditions and anaphylaxis. PA patients had increased adrenaline prescriptions.

Accidental ingestion of food allergens: A nationwide survey of Japanese nursery schools

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Challenges of managing food allergy in the developing world

Food allergy (FA) is currently a significant health care problem in the developing world. Widely varying study populations and methodologies, the use of surrogate markers such as self report or hospitalization rates due to anaphylaxis rather than objective methods, limits robust estimation of FA prevalence in low income settings. Also, allergy is under-recognized as a clinical specialty in the developing world which compromises the chance for accurate diagnosis. In this review, most published data on food allergens from developing or low income countries are displayed. The diagnostic challenges and limitations of treatment options are discussed. It seems that FA is an under-appreciated health care issue in the developing world, and accurate determination of its burden in low-income settings represents an important unmet need. Multicenter surveillance studies, using standardized methodologies, are, therefore, needed to reveal the true extent of the problem and provide epidemiological clues for prevention. Preventive strategies should be tailored to fit local circumstances in different geographic regions. In addition, studying the gene environment interactions and impact of early life microbiota on the expression of FA in developing communities would be worthwhile. Efforts and resources should be directed toward public health education and training of health care providers dealing with food allergic patients.

Safety assessment of miraculin using in silico and in vitro digestibility analyses

Miraculin is a glycoprotein with the ability to make sour substances taste sweet. The safety of miraculin has been evaluated using an approach proposed by the Food and Agriculture Organization of the United Nations and the World Health Organization for assessing the safety of novel proteins. Miraculin was shown to be fully and rapidly digested by pepsin in an in vitro digestibility assay. The proteomic analysis of miraculin's pepsin digests further corroborated that it is highly unlikely that any of the protein will remain intact within the gastrointestinal tract for potential absorption. The potential allergenicity and toxigenicity of miraculin, investigated using in silico bioinformatic analyses, demonstrated that miraculin does not represent a risk of allergy or toxicity to humans with low potential for cross-reactivity with other allergens. The results of a sensory study, characterizing the taste receptor activity of miraculin, showed that the taste-modifying effect of miraculin at the concentration intended for product development has a rapid onset and disappearance with no desensitizing impact on the receptor. Overall, the results of this study demonstrate that the use of miraculin to impact the sensory qualities of orally administered products with a bitter/sour taste profile is not associated with any safety concerns.

Pre-Conception Maternal Food Intake and the Association with Childhood Allergies

BACKGROUND

Periconceptional nutrition may have an important function in programming the immune function and allergies, however, there is a lack of studies assessing pre-conception food intake and childhood allergic disorders. The aim of the current study was to identify maternal pre-conception dietary components that may be associated with allergic disorders in children up to 3 years of age.

METHODS

Pregnant women attending their first antenatal visit and who were aged >18 years were invited to participate. Pre-conception food frequency data was retrospectively collected at 18 weeks' gestation. Childhood eczema, current wheeze, and rhinitis was assessed at 36 months of age using a questionnaire and doctor diagnosis (n = 234). Linear discriminant analysis (LDA) was used to explore the combination of dietary food components that best discriminated between allergy status in children.

RESULTS

Maternal pre-conception food intake such as low and high fat dairy, fresh fruit, unsaturated spreads, and take-away foods, were protective for any allergy assessed. Non-oily fish was protective for eczema and current wheeze; saturated spreads (e.g., butter) was protective for eczema, current wheeze, and rhinitis; poultry and fruit juice were adversely associated with each allergy.

CONCLUSIONS

Pre-conception food intakes demonstrate inconsistent and somewhat contrary relationships to the development of child allergies. Whether and how maternal food intake impacts the underlying fetal programming and the mechanisms of childhood allergy warrants further investigation.

Wheat Allergy in Children: A Comprehensive Update

Gluten-related disorders are very common in pediatric patients. Wheat allergy is triggered by an immunoglobulin E (IgE)-dependent mechanism; its prevalence varies according to the age and region, and in Europe has been estimated to be lower than 1%. Many studies investigated the potential role of several external factors that can influence the risk to developing wheat allergy, but results are still inconclusive. It can be responsible for several clinical manifestations depending on the route of allergen exposure: food-dependent exercise-induced anaphylaxis (FDEIA), occupational rhinitis or asthma (also known as baker’s asthma), and contact urticaria. The prognosis of IgE-mediated wheat allergy in children is generally favorable, with the majority of children becoming tolerant by school age. Patients who experienced an anaphylactic reaction prior to 3 years of age and patients with higher level of wheat- or ω-5 gliadin-specific IgE antibodies seem to be at higher risk of persistent wheat allergy. The current management of patients is dietary avoidance. Nowadays, oral immunotherapy has been proposed for wheat allergy with promising results, even if further studies are necessary to establish the best protocol in order to promote tolerance in wheat-allergic children.

Molecular clustering of genes related to the atopic syndrome: Towards a more tailored approach and personalized medicine?

Background

The atopic syndrome consists of heterogeneous manifestations, in which multiple associated genetic loci have recently been identified. It is hypothesized that immune dysregulation plays a role in the pathogenesis. In primary immunodeficiency diseases (PIDs), which are often monogenic immunodysregulation disorders, the atopic syndrome is a frequently occurring comorbidity. Based on the genetic defects in PIDs, novel gene/pathway-targeted therapies have been evaluated, which could be relevant in the atopic syndrome as well. Therefore, we aimed to define subclasses within the atopic syndrome based on the expression profiles of immune cell lineages of healthy mice.

Methods

Overlap between known atopy-related genes as described in the Human Gene Mutation Database and disease-causing genes of monogenic PIDs was evaluated. Clusters of atopy-related genes were based on the overlap in their co-expressed genes using the gene expression profiles of immune cell lineages of healthy mice from the Immunological Genome Project. We analyzed pathways involved in the atopic syndrome using Ingenuity Pathway Analysis.

Results

Twenty-two (5.3%) genes were overlapping between the atopy-related genes (n = 160) and PID-related genes (n = 278). We identified seven distinct clusters of atopy-related genes. Functional pathway analysis of all atopy-related genes showed relevance of T helper cell-mediated pathways.

Conclusions

This study shows a model to define clusters within the atopic syndrome based on gene expression profiles of immune cell lineages. Our results support the hypothesis that both genetic mechanisms and immune dysregulation play a role in the pathogenesis. It also opens up the possibility for novel therapeutic targets and a more tailored approach towards personalized medicine.

Electronic supplementary material

The online version of this article (10.1186/s13601-019-0273-8) contains supplementary material, which is available to authorized users.

Epidemiologic studies about food allergy and food sensitization in tropical countries. Results and limitations

The variety of foods and methods of preparation are part of the cultural identity of each population, and thus the main foods that cause symptoms vary among different regions. Due to their increasing frequency, Adverse Reactions to Food (AFR) have been the subject of extensive study, especially in North America and Europe but few studies have been conducted in other areas, especially in populations located in the tropics and subtropics. In this article, we review available information on the epidemiology of food sensitization and food allergies in tropical regions and explore the different epidemiological data considering the major food involved, the underlying immune mechanism and clinical symptoms partners. In addition, we identify the possible limitations and questions that arise from studies conducted in tropical countries, which helps to generate objectives for future research.

A hybridization chain reaction coupled with gold nanoparticles for allergen gene detection in peanut, soybean and sesame DNAs

Food allergy is an abnormal immune response of the immune system to some foods, which has caused great harm to people's health. Therefore, it is particularly important to detect allergens in food. In this article, a hybridization chain reaction (HCR) was coupled with gold nanoparticles (AuNPs) to detect the allergen genes of peanut, soybean and sesame DNAs. Two hairpin probes (H1 and H2) were designed for the allergen target genes of peanut, soybean and sesame DNAs. In the presence of target DNA, the hybridization chain reaction was triggered by it producing long double-stranded DNA (dsDNA) products. In the gold nanoparticle system, long dsDNA couldn't be adsorbed on the surface of AuNPs. When the concentration of salt ions in the solution increased, gold nanoparticles accumulated and led to a decrease of ultraviolet absorption. In the absence of target DNA, no hybridization chain reaction occurred. The hairpin probes could be adsorbed on the surface of AuNPs and no accumulation happened for gold nanoparticles even if the concentration of salt ions in the solution was increased. This method required no enzymes and had a strong specificity, so it was very easy to distinguish target DNA from non-target DNA. The detection limit of three allergens detected by this method was as low as 0.5 nM. The feasibility of this method for the detection of commercial commodities had been demonstrated by the successful detection of the DNAs extracted from commercial commodities, which were treated with extreme thermostable single-stranded binding protein (ET SSB).

Newly identified T cell subsets in mechanistic studies of food immunotherapy

Allergen-specific immunotherapy has shown promise for the treatment of food allergy and is currently being evaluated in clinical trials. Although immunotherapy can induce desensitization, the mechanisms underlying this process are not completely understood. Recent advances in high-throughput technologies along with concomitant advances in data analytics have enabled monitoring of cells at the single-cell level and increased the research focus on upstream cellular factors involved in the efficacy of immunotherapy, particularly the role of T cells. As our appreciation of different T cell subsets and their plasticity increases, the initial simplistic view that restoring Th1/Th2 balance by decreasing Th2 or increasing Th1 responses can ameliorate food allergy is being enhanced by a more complex model involving other T cell subsets, particularly Tregs. In this Review, we focus on the current understanding of T cell functions in food allergy, tolerance, and immunotherapy.

Prevalence of food hypersensitivity in relation to IgE sensitisation to common food allergens among the general adult population in West Sweden

Background

The prevalence of self-experienced adverse reactions to foods seems to have an increasing trend in both adults and children. However, it is unclear if the prevalence of food hypersensitivity in the Swedish adult population is still rising, what symptoms are caused by different foods and which are the most common foods to which adults are more frequently IgE-sensitised.

Methods

In a cross-sectional study based on questionnaire responses, interviews and clinical examinations as part of the West Sweden Asthma Study, 1042 subjects from the general population, 17–78 years of age, living in Västra Götaland, Sweden, were included. The subjects reported symptoms for 56 specified foods and blood samples were taken to examine the IgE-sensitisation pattern for 9 common foods.

Results

Approximately 32% of adults reported food hypersensitivity, affecting mostly women and subjects less than 61 years old. The foods most often reported to cause adverse reactions were hazelnut (8.9%), apple (8.4%), milk (7.4%) and kiwi (7.3%). Less than one percent (0.9%) reported symptoms from ingestion of meat. Symptoms mostly affected the gastrointestinal tract (15%) and the skin (2.7%). Sixteen per cent were IgE-sensitised to common foods, most often to hazelnut (13.3%), peanut (4.9%) and almond (3.0%), while 5.9% reported symptoms and were IgE-sensitised to the same food, mainly to hazelnut (5.3%).

Conclusions

The prevalence of self-reported food hypersensitivity in West Sweden indicates a rising trend. The correspondence between self-reported symptoms and IgE-sensitisation to foods is generally poor, except for hazelnut and almond which exhibit moderate or fair correlation.

Gut Microbiome as Target for Innovative Strategies Against Food Allergy

The dramatic increase in food allergy prevalence and severity globally requires effective strategies. Food allergy derives from a defect in immune tolerance mechanisms. Immune tolerance is modulated by gut microbiota function and structure, and microbiome alterations (dysbiosis) have a pivotal role in the development of food allergy. Environmental factors, including a low-fiber/high-fat diet, cesarean delivery, antiseptic agents, lack of breastfeeding, and drugs can induce gut microbiome dysbiosis, and have been associated with food allergy. New experimental tools and technologies have provided information regarding the role of metabolites generated from dietary nutrients and selected probiotic strains that could act on immune tolerance mechanisms. The mechanisms are multiple and still not completely defined. Increasing evidence has provided useful information on optimal bacterial species/strains, dosage, and timing for intervention. The increased knowledge of the crucial role played by nutrients and gut microbiota-derived metabolites is opening the way to a post-biotic approach in the stimulation of immune tolerance through epigenetic regulation. This review focused on the potential role of gut microbiome as the target for innovative strategies against food allergy.

The role of incurred materials in method development and validation to account for food processing effects in food allergen analysis

The issue of undeclared allergens represents a matter of great concern, being the subject of many alert notifications by the Rapid Alert System for Food and Feed portal of the European Commission, often leading to food recalls. The availability of reliable analytical approaches able to detect and quantify hidden allergens in processed foods is increasingly requested by the food industry, food safety authorities and regulatory bodies to protect sensitive consumers' health. The present review discusses the fundamental role of incurred materials for method development and analytical performance assessment in a metrology perspective on testing for undeclared allergens in processed foodstuffs. Due to the nature of the analytes and their susceptibility to various processing effects, reliability and comparability of results have posed a great challenge. In this context, the use of incurred samples as reference materials permits simulation of the effects of food processing on target analyte structure affecting analyte extractability and detectability. Graphical abstract ᅟ.

Goat's milk anaphylaxis in a cow's milk tolerant child

Goat's milk (GM) allergy commonly occurs together with cow's milk (CM) allergy due to cross-reactivity between highly homologous proteins. We present an unusual case of GM anaphylaxis in a CM tolerant child.

Higher Polygenetic Predisposition for Asthma in Cow's Milk Allergic Children

Cow’s milk allergy (CMA) is an early-onset allergy of which the underlying genetic factors remain largely undiscovered. CMA has been found to co-occur with other allergies and immunological hypersensitivity disorders, suggesting a shared genetic etiology. We aimed to (1) investigate and (2) validate whether CMA children carry a higher genetic susceptibility for other immunological hypersensitivity disorders using polygenic risk score analysis (PRS) and prospective phenotypic data. Twenty-two CMA patients of the Dutch EuroPrevall birth cohort study and 307 reference subjects were genotyped using single nucleotide polymorphism (SNP) array. Differentially genetic susceptibility was estimated using PRS, based on multiple P-value thresholds for SNP inclusion of previously reported genome-wide association studies (GWAS) on asthma, autism spectrum disorder, atopic dermatitis, inflammatory bowel disease and rheumatoid arthritis. These associations were validated with prospective data outcomes during a six-year follow-up in 19 patients. We observed robust and significantly higher PRSs of asthma in CMA children compared to the reference set. Association analyses using the prospective data indicated significant higher PRSs in former CMA patients suffering from asthma and related traits. Our results suggest a shared genetic etiology between CMA and asthma and a considerable predictive sensitivity potential for subsequent onset of asthma which indicates a potential use for early clinical asthma intervention programs.