The natural history of peanut and tree nut allergy

Viral Vector Based Immunotherapy for Peanut Allergy

Food allergy (FA) is estimated to impact up to 10% of the population and is a growing health concern. FA results from a failure in the mucosal immune system to establish or maintain immunological tolerance to innocuous dietary antigens, IgE production, and the release of histamine and other mediators upon exposure to a food allergen. Of the different FAs, peanut allergy has the highest incidence of severe allergic responses, including systemic anaphylaxis. Despite the recent FDA approval of peanut oral immunotherapy and other investigational immunotherapies, a loss of protection following cessation of therapy can occur, suggesting that these therapies do not address the underlying immune response driving FA. Our lab has shown that liver-directed gene therapy with an adeno-associated virus (AAV) vector induces transgene product-specific regulatory T cells (Tregs), eradicates pre-existing pathogenic antibodies, and protects against anaphylaxis in several models, including ovalbumin induced FA. In an epicutaneous peanut allergy mouse model, the hepatic AAV co-expression of four peanut antigens Ara h1, Ara h2, Ara h3, and Ara h6 together or the single expression of Ara h3 prevented the development of a peanut allergy. Since FA patients show a reduction in Treg numbers and/or function, we believe our approach may address this unmet need.

Health Promotion of Early and Sustained Allergenic Food Introduction for the Prevention of Food Allergy

Observational studies and landmark randomized control trials support early and sustained allergenic food introduction in infancy as an effective preventive strategy against food allergy development. Despite a consensus regarding the intended goals of early and sustained allergenic food introduction, there have been myriad policy recommendations among health authorities in how to achieve both individual and population-level health outcomes for food allergy prevention. This clinical management review provides an overview on the data that informs early and sustained allergenic food introduction strategies, suggestions on how to advise allergenic food introduction, principles of prevention programs as they relate to food allergy prevention, and health promotion and systems-level challenges that impede achievement of food allergy prevention goals.

Natural History of Hazelnut Allergy and Current Approach to Its Diagnosis and Treatment

Hazelnut allergy is the most prevalent type of nut allergy in Europe, with symptoms that can range from mild, such as hives and itching, to severe, such as anaphylaxis, particularly in patients who are sensitized to highly stable allergens, such as storage proteins. Compared to other types of food allergies, allergies to tree nuts, including hazelnuts, tend to persist throughout life. Although symptoms can appear in early childhood, they often continue into adulthood, with a minority of cases improving during adolescence. Currently, there is no curative treatment available for hazelnut allergy, and patients must adhere to a restrictive diet and carry autoinjective epinephrine. However, oral allergen immunotherapy (AIT) is a promising treatment option. Patients can be categorized based on their risk for severe reactions using various clinical, in vivo, and in vitro tests, including component-resolved diagnosis and oral food challenge. This review aims to provide an overview of the current knowledge of the natural history of hazelnut allergy and new approaches for its diagnosis and management.

Nutritional Management of Children with Food Allergies

Purpose of the Review

The purpose of the review is to review the evidence for the nutritional management of paediatric food allergy and provide a practical approach for healthcare professionals working in this area.

Recent Findings

Dietary elimination remains the mainstay for management of food allergies in children. However, the elimination of food allergens increases the risk for growth faltering, micronutrient deficiencies and feeding difficulties. Breastmilk remains the ideal source of nutrition for infants, but when not available, the vast majority will tolerate an extensively hydrolysed formula, and rice hydrolysate has also been suggested as a suitable alternative. Only in severe cases, including anaphylaxis, eosinophilic oesophagitis and growth faltering, is an amino acid formula indicated. The early introduction of peanut and egg and avoiding the delay in the introduction of other allergens, when not already allergic, has been highlighted by recent studies.

Summary

Whilst the elimination of allergens increases the risk of developing poor growth, micronutrient deficiencies and feeding difficulties, optimal, early dietary input, including advice on active introduction of allergens and alternative feeds, ideally from a registered dietitian/nutritionist, may be prevent and improve outcomes.

A practical focus on oral immunotherapy to tree nuts

Tree nut (TN) allergy is common, with a global prevalence of up to 4.9%. TN allergy is persistent in most patients, and accidental reactions are common. There is considerable clinical cross-reactivity between cashew and pistachio, and between walnut and pecan. A diagnosis of TN allergy is based on a history of clinical reaction on ingestion, along with confirmed sensitization through either skin-prick or serum immunoglobulin E (IgE) testing. Component testing and food challenges may be required in patients with birch pollinosis to distinguish between IgE-mediated allergy to a heat-stable protein and pollen food allergy syndrome. There is available evidence that TN oral immunotherapy (OIT) is reasonably safe and effective. There are numerous nonpharmaceutical food products to facilitate TN-OIT dosing. TN OIT should be offered as a treatment option for patients with TN allergy.

[Food Allergy in Childhood]

Food Allergy in Childhood Abstract. Food allergies in childhood are on the rise and are therefore a topical issue in practice. In this article, we describe the most common allergens and risk factors for the development of a food allergy. The classification of IgE- and non-IgE-mediated food allergies and their respective clinical manifestations are highlighted. The importance of a careful diagnosis with targeted history taking and allergy testing and finally the performance of oral provocation for the diagnosis will be presented in a practical manner. We will discuss the care of families of children with food allergies, whereby support through nutritional counselling as well as equipping families with an emergency kit, including appropriate instructions for use, are important. Finally, the latest therapeutic approaches of specific immunotherapy, which aims to induce tolerance, are presented and the prognosis of food allergies is discussed.

Peanut allergy: Beyond the oral immunotherapy plateau

BACKGROUND

There are a lack of disease-modifying treatments for peanut allergy, which is lifelong in most instances. Oral immunotherapy has remained at the forefront of prospective treatments, though its efficacy is consistently undermined by the risk of adverse reactions and meager sustained effects.

AIM

This review discusses the current state of oral immunotherapy, its strengths and limitations, and the future of therapeutics for the treatment of peanut allergy.

CONCLUSION

The persistence of peanut allergy is currently attributed to reservoirs of peanut-specific memory B cells and Th2 cells, though the cellular and molecular interplay that facilitates the replenishment of peanut-specific IgE remains elusive. Uncovering these events will prove critical for identification of novel targets as we forge ahead to a new age of peanut allergy treatment with biotherapeutics.

Prevalence and characteristics of peanut allergy in US adults

BACKGROUND

Peanut allergy (PA) is the leading pediatric food allergy and a common cause of anaphylaxis. Little is known, however, on the prevalence and characteristics of PA in the adult population and whether phenotypic differences exist between adult-onset and childhood-onset PA.

OBJECTIVES

This study describes the current US population-level burden of adult PA.

METHODS

A cross-sectional food allergy survey was administered via phone and web in 2015 and 2016, resulting in nationally representative complex-survey weighted data for 40,443 adults. Reported food allergies were considered "convincing" if symptoms to specific allergens were consistent with an IgE-mediated reaction.

RESULTS

The prevalence of current self-reported PA was 2.9% among US adults, with 1.8% having convincing PA. Over 17% of adults with peanut allergy reported onset of their PA in adulthood. In adults with childhood-onset PA, 75.4% reported physician-diagnosed PA, compared with only 58.9% of adult-onset PA. Despite a similar frequency of food allergy-related emergency department visits within the past year (approximately 1 in 5 adults with PA allergy), adults with childhood-onset PA were significantly more likely to have a current epinephrine prescription compared with those with adult-onset PA (56% vs 44% respectively; P = .02) and were more likely to use an epinephrine autoinjector (48% vs 35%, P = .01).

CONCLUSIONS

Approximately 4.6 million US adults have PA-over 800,000 of whom appear to have developed their PA after age 18 years. Further examination of phenotypic differences between childhood-onset and adult-onset PA may improve understanding and management of adult PA.

Fecal IgA, Antigen Absorption, and Gut Microbiome Composition Are Associated With Food Antigen Sensitization in Genetically Susceptible Mice

Food allergy is a potentially fatal disease affecting 8% of children and has become increasingly common in the past two decades. Despite the prevalence and severe nature of the disease, the mechanisms underlying sensitization remain to be further elucidated. The Collaborative Cross is a genetically diverse panel of inbred mice that were specifically developed to study the influence of genetics on complex diseases. Using this panel of mouse strains, we previously demonstrated CC027/GeniUnc mice, but not C3H/HeJ mice, develop peanut allergy after oral exposure to peanut in the absence of a Th2-skewing adjuvant. Here, we investigated factors associated with sensitization in CC027/GeniUnc mice following oral exposure to peanut, walnut, milk, or egg. CC027/GeniUnc mice mounted antigen-specific IgE responses to peanut, walnut and egg, but not milk, while C3H/HeJ mice were not sensitized to any antigen. Naïve CC027/GeniUnc mice had markedly lower total fecal IgA compared to C3H/HeJ, which was accompanied by stark differences in gut microbiome composition. Sensitized CC027/GeniUnc mice had significantly fewer CD3+ T cells but higher numbers of CXCR5+ B cells and T follicular helper cells in the mesenteric lymph nodes compared to C3H/HeJ mice, which is consistent with their relative immunoglobulin production. After oral challenge to the corresponding food, peanut- and walnut-sensitized CC027/GeniUnc mice experienced anaphylaxis, whereas mice exposed to milk and egg did not. Ara h 2 was detected in serum collected post-challenge from peanut-sensitized mice, indicating increased absorption of this allergen, while Bos d 5 and Gal d 2 were not detected in mice exposed to milk and egg, respectively. Machine learning on the change in gut microbiome composition as a result of food protein exposure identified a unique signature in CC027/GeniUnc mice that experienced anaphylaxis, including the depletion of Akkermansia. Overall, these results demonstrate several factors associated with enteral sensitization in CC027/GeniUnc mice, including diminished total fecal IgA, increased allergen absorption and altered gut microbiome composition. Furthermore, peanuts and tree nuts may have inherent properties distinct from milk and eggs that contribute to allergy.

Model of Walnut Allergy in CC027/GeniUnc Mice Recapitulates Key Features of Human Disease

Tree nut allergies affect 1% of the United States population, are often severe in nature and rarely outgrown. Despite the severity and prevalence, there are no FDA-approved treatments for tree nut allergy. Development of a therapeutic would be expedited by having a mouse model that mimics the human disease. We utilized the CC027/GeniUnc mouse strain, which was previously identified as an orally reactive model of peanut allergy, to develop a model of walnut allergy. Mice were sensitized with walnut and cholera toxin for 4 weeks and subsequently challenged by oral gavage. Blood samples were collected to measure serum IgE. Walnut-sensitized mice produced high levels of walnut-IgE and were cross-sensitized to pecan. Oral challenges with walnut resulted in severe anaphylaxis and accompanying allergic symptoms. Importantly, pecan challenges also led to severe allergic reactions, indicating cross-reactivity to pecan. Overall, this novel mouse model reproduces key characteristics of human walnut allergy, which provides a platform to develop novel therapies and better understand sensitization mechanisms.

A cashew specific monoclonal antibody recognizing the small subunit of Ana o 3

Food allergies represent a substantial medical liability and preventing accidental exposure to food allergens requires constant attention. Allergic reaction to cashew nuts is frequently serious, and the small 2S albumin, Ana o 3, is an immuno-dominant cashew allergen. Ana o 3 is composed of five alpha helices, contains 2 subunits linked by cysteine disulfide bonds, and remains soluble even after extensive heating of cashew nuts. The stability and solubility properties of Ana o 3 make it an excellent target for diagnostic and detection methods and tools. In this work, a monoclonal antibody, designated 2H5, aimed at amino acids 39–54 within helices I and II of the small subunit of Ana o 3 was developed that recognizes both recombinant and native Ana o 3 and is cashew specific in ELISA experiments. The K_D against the targeted amino-acid sequence was found to be approximately 7.0 × 10⁻⁶ mg/ml (3.3 nM), while the K_D against the native protein was found to be approximately 1.2 × 10^-3 mg/ml (92 nM). The 2H5 monoclonal anti-Ana o 3 antibody can distinguish between native and recombinant proteins and represents a useful reagent for the study of antibody cashew-allergen interactions and may enable the development of cashew-specific diagnostic tools that can be used to prevent accidental cashew allergen exposures.

Adjuvanted Immunotherapy Approaches for Peanut Allergy

Food allergies are a growing public health concern with an estimated 8% of US children affected. Peanut allergies are also on the rise and often do not spontaneously resolve, leaving individuals at-risk for potentially life-threatening anaphylaxis throughout their lifetime. Currently, two forms of peanut immunotherapy, oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT), are in Phase III clinical trials and have shown promise to induce desensitization in many subjects. However, there are several limitations with OIT and EPIT, such as allergic side effects, daily dosing requirements, and the infrequent outcome of long-term tolerance. Next-generation therapies for peanut allergy should aim to overcome these limitations, which may be achievable with adjuvanted immunotherapy. An adjuvant can be defined as anything that enhances, accelerates, or modifies an immune response to a particular antigen. Adjuvants may allow for lower doses of antigen to be given leading to decreased side effects; may only need to be administered every few weeks or months rather than daily exposures; and may induce a long-lasting protective effect. In this review article, we highlight examples of adjuvants and formulations that have shown pre-clinical efficacy in treating peanut allergy.

Allergy to Peanuts in Atopic Dermatitis Patients 14 Year or Older and the Association with Food Hypersensitivity, Inhalant Allergens, Asthma Bronchiale and Rhinitis

BACKGROUND

In adult patients suffering from atopic dermatitis (AD), studies investigating the co-prevalence of AD and food allergy are still scarce, and exact data are not available.

AIMS AND OBJECTIVES

To evaluate the occurrence of food allergy to peanuts in significant relation to food hypersensitivity, inhalant allergy and to asthma bronchial and rhinitis.

MATERIALS AND METHODS

Altogether 332 patients of AD 14 year or older were included in the study. The complete dermatological and allergological examinations were performed in all included patients (including examination of specific immunoglobulin E, skin prick test to different food and inhalant allergens, anamnestic data about food reactions, evaluation of allergic rhinitis, and allergic asthma bronchiale). We evaluated whether there was some relation between the food allergy to peanuts and followed parameters. Pairs of these categories were entered in the contingency tables, and the Chi-square test for the relationship of these variables was performed with the level of significance set to 5%.

RESULTS

Altogether 332 persons suffering from AD were included in the study of which 120 were male and 212 were female; the average age was 27.2 year. The significant relation between the allergy to peanuts and the occurrence of food hypersensitivity (FH) reactions to tomatoes, kiwi, apples, oranges, carrot and to the sensitization to grass, trees, mites, and the occurrence of rhinitis was found.

CONCLUSION

The significant relation between the allergy to peanuts and the occurrence of FH reactions and the sensitization to inhalant allergens and rhinitis was found. The future studies may show if the decrease in food allergy to peanuts can lead to the decrease of the occurrence of other FH reactions and sensitization to inhalant allergens and rhinitis in AD patients.

Sensitisation to fungi in atopic dermatitis patients over 14 years of age and the relation to the occurrence of food hypersensitivity reactions

The aim of this study was to evaluate if there is some relation between the sensitisation to fungi and the occurrence of food hypersensitivity reactions in atopic dermatitis patients aged 14 years and older. Complete dermatological and allergological examination was performed in all included patients; the occurrence of food hypersensitivity reactions was recorded and the sensitisation to mixture of fungi was examined (skin prick test, specific IgE). The statistical evaluation of the relation between the sensitisation to fungi and the occurrence of food hypersensitivity reactions was performed; 331 patients were included in the study, 110 men and 221 women, the average age was 26.8 years. The sensitisation to fungi was recorded in 100 patients (30%), the occurrence of food hypersensitivity reactions was recorded in 261 patients (79%). We confirmed that patients suffering from sensitisation to fungi suffer significantly more often from food hypersensitivity reactions to nuts (walnuts, peanuts) and sea fish; no significant relation was confirmed between the sensitisation to fungi and the occurrence of food hypersensitivity reactions to tomatoes, kiwi, apples, spices, oranges, capsicum, celery and carrot.

Effects of industrial cashew nut processing on anacardic acid content and allergen recognition by IgE

Cashew nuts are important both nutritionally and industrially, but can also cause food allergies in some individuals. The present study aimed to assess the effect(s) of industrial processing on anacardic acids and allergens present in cashew nuts. Sample analyses were performed using liquid chromatography coupled with mass spectrometry, SDS-PAGE and immunoassay. The anacardic acid concentration ranged from 6.2 to 82.6mg/g during processing, and this variation was attributed to cashew nut shell liquid incorporation during storage and humidification. Dehydrated and selected samples did not significantly differ in anacardic acid content, having values similar to the raw sample. SDS-PAGE and immunoassay analysis with rabbit polyclonal sera and human IgE indicated only minor differences in protein solubility and antibody binding following processing steps. The findings indicate that appreciable amounts of anacardic acid remain in processed nuts, and that changes to cashew allergens during industrial processing may only mildly affect antibody recognition.

Effect of acid treatment on allergenicity of peanut and egg

BACKGROUND

Many food experts have studied various treatments or processing techniques in order to develop hypoallergenic foods. In a previous study, acid treatment dramatically mitigated the allergenicity of peanut, especially Ara h 2.

RESULTS

Gel electrophoresis showed that most protein bands of acid-treated peanut were not detected, but protein bands of egg white became weaker and broader by acid treatment. In immunoblotting using a rabbit antibody, the antigenicity against ovalbumin or ovomucoid in acid-treated egg white was decreased but the antigenicity against Ara h 1 or Ara h 2 in peanut treated with pH 2 acetic acid was completely undetected. The allergenicity of ovalbumin and peanut fell significantly to 1/10²² and 1/5380, respectively, when measured as IC₅₀ in the sample treated with pH 2.0 acetic acid.

CONCLUSION

This study showed that acid treatment was more effective in peanut and barely effective in ovomucoid. This may contribute to the development of hypoallergenic food and clinical management of food allergy. © 2016 Society of Chemical Industry.

RNA-Seq Analysis of Developing Pecan (Carya illinoinensis) Embryos Reveals Parallel Expression Patterns among Allergen and Lipid Metabolism Genes

The pecan nut is a nutrient-rich part of a healthy diet full of beneficial fatty acids and antioxidants, but can also cause allergic reactions in people suffering from food allergy to the nuts. The transcriptome of a developing pecan nut was characterized to identify the gene expression occurring during the process of nut development and to highlight those genes involved in fatty acid metabolism and those that commonly act as food allergens. Pecan samples were collected at several time points during the embryo development process including the water, gel, dough, and mature nut stages. Library preparation and sequencing were performed using Illumina-based mRNA HiSeq with RNA from four time points during the growing season during August and September 2012. Sequence analysis with Trinotate software following the Trinity protocol identified 133,000 unigenes with 52,267 named transcripts and 45,882 annotated genes. A total of 27,312 genes were defined by GO annotation. Gene expression clustering analysis identified 12 different gene expression profiles, each containing a number of genes. Three pecan seed storage proteins that commonly act as allergens, Car i 1, Car i 2, and Car i 4, were significantly up-regulated during the time course. Up-regulated fatty acid metabolism genes that were identified included acyl-[ACP] desaturase and omega-6 desaturase genes involved in oleic and linoleic acid metabolism. Notably, a few of the up-regulated acyl-[ACP] desaturase and omega-6 desaturase genes that were identified have expression patterns similar to the allergen genes based upon gene expression clustering and qPCR analysis. These findings suggest the possibility of coordinated accumulation of lipids and allergens during pecan nut embryogenesis.

Lifelong memory responses perpetuate humoral TH2 immunity and anaphylaxis in food allergy

BACKGROUND

A number of food allergies (eg, fish, shellfish, and nuts) are lifelong, without any disease-transforming therapies, and unclear in their underlying immunology. Clinical manifestations of food allergy are largely mediated by IgE. Although persistent IgE titers have been attributed conventionally to long-lived IgE⁺ plasma cells (PCs), this has not been directly and comprehensively tested.

OBJECTIVE

We sought to evaluate mechanisms underlying persistent IgE and allergic responses to food allergens.

METHODS

We used a model of peanut allergy and anaphylaxis, various knockout mice, adoptive transfer experiments, and in vitro assays to identify mechanisms underlying persistent IgE humoral immunity over almost the entire lifespan of the mouse (18-20 months).

RESULTS

Contrary to conventional paradigms, our data show that clinically relevant lifelong IgE titers are not sustained by long-lived IgE⁺ PCs. Instead, lifelong reactivity is conferred by allergen-specific long-lived memory B cells that replenish the IgE⁺ PC compartment. B-cell reactivation requires allergen re-exposure and IL-4 production by CD4 T cells. We define the half-lives of antigen-specific germinal centers (23.3 days), IgE⁺ and IgG₁⁺ PCs (60 and 234.4 days, respectively), and clinically relevant cell-bound IgE (67.3 days).

CONCLUSIONS

These findings can explain lifelong food allergies observed in human subjects as the consequence of allergen exposures that recurrently activate memory B cells and identify these as a therapeutic target with disease-transforming potential.

The prevalence, natural history and time trends of peanut allergy over the first 10 years of life in two cohorts born in the same geographical location 12 years apart

BACKGROUND

The aim of this study was to explore the natural history of peanut allergy in childhood in two birth cohorts from the same geographical region in the South of England.

METHODS

The FAIR birth cohort was established on the Isle of Wight (UK) between 2001 and 2002 (n = 969). Children were followed up prospectively, skin prick tested (SPT) to peanut allergens at 1, 2, 3 and 10 years and food challenges performed. The Isle of Wight (IOW) birth cohort was established in 1989 (n = 1456). SPTs were performed at 1, 2, 4 and 10 years. Peanut allergy was based on positive SPT and a good clinical history.

RESULTS

In the FAIR cohort, the prevalence of sensitization to peanut was 0.4%, 2.0%, 2.0% and 2.4% at 1, 2, 3 and 10 years, respectively. At 10 years of age, 12 of 828 (1.5%) children were diagnosed with peanut allergy. One child (8%) outgrew her peanut allergy between 3 and 10 years and two children (15%) presented with new onset peanut allergy. Over the first 10 years of life, 13 of 934 (1.4%) children were diagnosed with peanut allergy. In the IOW cohort, 6 of 1034 (0.58%) were diagnosed with peanut allergy at 10 years. We found no significant differences between the FAIR and the IOW birth cohort for any of the time points studied.

CONCLUSION

Peanut allergy appears to be stable over the first 10 years of life in our cohorts. There was no significant difference in peanut sensitization or clinical peanut allergy between 1989 and 2001.

Food Allergy: Our Evolving Understanding of Its Pathogenesis, Prevention, and Treatment

Food allergy is defined as an IgE-mediated hypersensitivity response to ingested food with allergic symptoms ranging from urticaria to life-threatening anaphylaxis. Food allergy is thought to develop because of (1) failed induction of tolerance upon initial exposure to food antigen or (2) breakdown of established tolerance to food antigen. We review current understanding of the pathogenesis, epidemiology, and natural history of food allergy, including the unconventional IgE-mediated food allergy to mammalian meat known as alpha-gal food allergy. We highlight emerging data on food allergy treatment and prevention, emphasizing the growing appeal of manipulating the gut microenvironment using probiotics and helminth products to blunt systemic allergic responses to food.

Multicentre Double-Blind Placebo-Controlled Food Challenge Study in Children Sensitised to Cashew Nut

Background

Few studies with a limited number of patients have provided indications that cashew-allergic patients may experience severe allergic reactions to minimal amounts of cashew nut. The objectives of this multicentre study were to assess the clinical relevance of cashew nut sensitisation, to study the clinical reaction patterns in double-blind placebo-controlled food challenge tests and to establish the amount of cashew nuts that can elicit an allergic reaction.

Methods and Findings

A total of 179 children were included (median age 9.0 years; range 2–17 years) with cashew nut sensitisation and a clinical history of reactions to cashew nuts or unknown exposure. Sensitised children who could tolerate cashew nuts were excluded. The study included three clinical visits and a telephone consultation. During the first visit, the medical history was evaluated, physical examinations were conducted, blood samples were drawn and skin prick tests were performed. The children underwent a double-blind placebo-controlled food challenge test with cashew nut during the second and third visits. The study showed that 137 (76.5%) of the sensitised children suspected of allergy to cashew nut had a positive double-blind placebo-controlled food challenge test, with 46% (63) manifesting subjective symptoms to the lowest dose of 1 mg cashew nut protein and 11% (15) developing objective symptoms to the lowest dose. Children most frequently had gastro-intestinal symptoms, followed by oral allergy and skin symptoms. A total of 36% (49/137) of the children experienced an anaphylactic reaction and 6% (8/137) of the children were treated with epinephrine.

Conclusion

This prospective study demonstrated a strikingly high percentage of clinical reactions to cashew nut in this third line population. Severe allergic reactions, including anaphylaxis requiring epinephrine, were observed. These reactions were to minimal amounts of cashew nut, demonstrated the high potency of this allergens.

Trial Registration

www.ncbi.nlm.nih.gov/pubmed NTR3572

Sensitization profiles to peanut allergens in Belgium; cracking the code in infants, children and adults

OBJECTIVES

Peanut allergy shows distinct clinical patterns that can be predicted by component resolved diagnosis. However, data about peanut sensitization profiles in populations with a broad age stratification are scarce.

METHODS

Sera of 89 peanut allergic patients (age 1-70 years), 21 infants (<1 year) with atopic dermatitis (AD) sensitized to peanut, 24 age matched peanut-tolerant individuals with positive specific IgE (sIgE) to peanut and 15 healthy individuals were tested for sIgE reactivity to rAra h 1, rAra h 2, rAra h 3, rAra h 8, rAra h 9 and rBet v 1 (FEIA ImmunoCAP, Thermo Fisher Scientific).

RESULTS

In infants with AD, Ara h 1, Ara h 2 and Ara h 3 enabled to explain 14/21 (67%) of peanut sensitizations. No sensitization to Ara h 8 or Bet v 1 was observed. Patients with generalized reactions were more frequently sensitized to Ara h 1, Ara h 2 and Ara h 3 compared to patients with an oral allergy syndrome (OAS) and peanut-tolerant patients. Sensitization to Ara h 8 was significantly more observed in patients with an OAS. Ara h 2 showed to be the best marker to distinguish patients with generalized reactions from patients with an OAS and/or peanut sensitized patients but tolerating the legume.

CONCLUSION

Sensitization to Ara h 1, Ara h 2 and Ara h 3 can have an early onset and is predominantly associated with a more severe outcome. Ara h 2 is the best marker of a generalized peanut allergy.

Diagnostic Value of Specific IgE to Peanut and Ara h 2 in Korean Children with Peanut Allergy

PURPOSE

The purpose of this study was to establish the diagnostic decision point (DDP) of peanut specific IgE (sIgE) for predicting the outcome of oral food challenge (OFC). We also evaluated the usefulness of sIgE to peanut components (Ara h 1, 2, 3, 8, and 9) in diagnosing peanut allergy.

METHODS

Korean children aged over 12 months with a suspected peanut allergy were enrolled. Diagnosis of peanut allergy was confirmed by an open OFC or through the convincing history of anaphylaxis. Cutoff levels of sIgE to peanut and peanut components were determined by analyzing receiver operating characteristic curves.

RESULTS

Forty-eight children (22 boys and 26 girls) with a suspected peanut allergy were enrolled. The previously established DDP for peanut-sIgE antibodies (14 kU/L) showed a sensitivity of 22.7%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value of 60.4% in our study population. The median levels of peanut-sIgE (5.4 kU/L vs 1.1 kU/L, P<0.001) and Ara h 2-sIgE (0.8 kU/L vs 0 kU/L, P<0.001) were significantly higher in the peanut allergy group than in the peanut tolerance group. The peanut-sIgE concentration indicating a PPV of 100% was 10.3 kU/L. The Ara h 2-sIgE level of 4.0 kU/L had a PPV of 100%.

CONCLUSIONS

Our results showed that the cutoff levels for peanut (10.3 kU/L) and Ara h 2 (4.0 kU/L) established in this study is useful for the diagnosis of peanut allergy in Korean children.

Jug r 2-reactive CD4(+) T cells have a dominant immune role in walnut allergy

Background

Allergic reactions to walnut can be life threatening. While IgE epitopes of walnut have been studied, CD4⁺ T-cell specific epitopes for walnut remain uncharacterized. Particularly, the relationship of both phenotype and frequency of walnut specific T-cells to the disease have not been examined.

Objectives

We sought to provide a thorough phenotypic analysis for walnut reactive T-cells in allergic and non-allergic subjects. Particularly, the relationship of phenotypes and frequencies of walnut specific T-cells with the disease.

Methods

CD154 up-regulation assay was used to examine CD4⁺ T-cell reactivity towards walnut allergens.Jug r 1, Jug r 2 and Jug r 3. Tetramer-Guided epitope mapping approach was utilized to identify HLA-restricted CD4⁺ T-cells epitopes in Jug r 2. Direct ex vivo staining with peptide-major histocompatibility complex class II (pMHC-II) tetramers enabled the comparison of frequency and phenotype of Jug r 2-specific CD4⁺ T-cells between allergic and non-allergic subjects. Jug r 2-specific T-cell-clones were also generated and mRNA transcription factor levels were assessed by RT qPCR. Intracellular cytokine staining (ICS) assays were performed for further phenotypical analyses.

Results

Jug r 2 was identified as the major allergen that elicited CD4⁺ T-cell responses. Multiple Jug r 2 T-cell epitopes were identified. The majority of these T-cells in allergic subjects have a CCR4⁺ T_CM (central memory) phenotype. A subset of these T-cells express CCR4⁺CCR6⁺ irrespectively of the asthmatic status of the allergic subjects. ICS confirmed these T_H2, T_H2/T_H17 and T_H17-like heterogenic profiles. Jug r 2-specific T-cell-clones from allergic subjects mainly expressed GATA3; nonetheless, a portion of T-cell clones expressed either GATA3 and RORC, or RORC, confirming the presence of T_H2, T_H2/T_H17 and T_H17 cells.

Conclusions

Jug r 2 specific responses dominate walnut T-cell responses in subjects with walnut allergy. Jug r 2 central memory CD4⁺ cells and terminal effector T-cells were detected in peripheral blood with the central memory phenotype as the most prevalent phenotype. In addition to conventional T_H2-cells, T_H2/T_H17 and T_H17 cells were also detected in non-asthmatic and asthmatic subjects with walnut allergy. Understanding this T-cell heterogeneity may render better understanding of the disease manifestation.

Decreased immunoglobulin E (IgE) binding to cashew allergens following sodium sulfite treatment and heating

Cashew nut and other nut allergies can result in serious and sometimes life-threatening reactions. Linear and conformational epitopes within food allergens are important for immunoglobulin E (IgE) binding. Methods that disrupt allergen structure can lower IgE binding and lessen the likelihood of food allergy reactions. Previous structural and biochemical data have indicated that 2S albumins from tree nuts and peanuts are potent allergens, and that their structures are sensitive to strong reducing agents such as dithiothreitol. This study demonstrates that the generally regarded as safe (GRAS) compound sodium sulfite effectively disrupted the structure of the cashew 2S albumin, Ana o 3, in a temperature-dependent manner. This study also showed that sulfite is effective at disrupting the disulfide bond within the cashew legumin, Ana o 2. Immunoblotting and ELISA demonstrated that the binding of cashew proteins by rabbit IgG or IgE from cashew-allergic patients was markedly lowered following treatment with sodium sulfite and heating. The results indicate that incorporation of sodium sulfite, or other food grade reagents with similar redox potential, may be useful processing methods to lower or eliminate IgE binding to food allergens.

Emerging therapies for food allergy

Food allergy is a common condition for which there are currently no approved treatments except avoidance of the allergenic food and treatment of accidental reactions. There are several potential treatments that are under active investigation in animal and human studies, but it is not yet clear what the best approach may be. Here, we review approaches that are currently in clinical trials, including oral, sublingual, and epicutaneous immunotherapy, immunotherapy combined with anti-IgE, and Chinese herbal medicine as well as approaches that are in preclinical or early clinical investigation, including modified protein immunotherapy, adjuvants, DNA vaccines, and helminth administration. We discuss the importance of fully exploring the risks and benefits of any treatment before it is taken to general clinical practice and the need for clarity about the goals of treatment.

Probiotic VSL#3-induced TGF-β ameliorates food allergy inflammation in a mouse model of peanut sensitization through the induction of regulatory T cells in the gut mucosa

SCOPE

Among food allergies, peanut allergy is frequently associated with severe anaphylactic reactions. In the need for safe and effective therapeutic strategies, probiotics may be considered on the basis of their immunomodulatory properties. The aim of the present study was to investigate the immunological mediators involved in the effects of probiotic VSL#3 oral supplementation on Th2 inflammation and anaphylaxis in a mouse model of peanut allergy.

METHODS AND RESULTS

VSL#3 supplementation to peanut-sensitized mice was effective in ameliorating anaphylaxis and Th2-mediated inflammation, by promoting regulatory responses in the jejunum mucosa and in the mesenteric lymph node, as evaluated by ELISA, real-time PCR, histologic, and immunohistochemical analysis. Probiotic-induced TGF-β mediates its protective effects through the induction of regulatory T cells expressing FOXP3 and/or latency-associated peptide, as proven by in vivo blockade of TGF-β in VSL#3-treated mice with a neutralizing monoclonal antibody one day before challenge.

CONCLUSION

TGF-β, induced in the gut by VSL#3 supplementation, is capable of reducing the Th2 inflammation associated with food anaphylaxis in a mouse model of peanut sensitization. TGF-β acts through the induction/maintenance of regulatory T cells expressing FOXP3 and/or latency-associated peptide. Probiotics supplementation may represent an effective and safe strategy for treating food allergies in adult population.

Interpretation of food specific immunoglobulin E levels in the context of total IgE

BACKGROUND

Food specific immunoglobulin E (IgE) (fsIgE) cut points are used in the evaluation of food allergies. Concomitant measurement of total IgE (tIgE) is traditionally not obtained. We anecdotally observed elevations in fsIgE mirroring tIgE increases, which may confound accurate interpretation.

OBJECTIVE

To determine whether changes in tIgE were associated with fsIgE and whether predictions of fsIgE could be formulated based on tIgE.

METHODS

We studied children younger than 18 years who had both tIgE and fsIgE (egg, n = 136; milk, n = 123; peanut, n = 201; soy, n = 55) obtained simultaneously on 1 or more occasion between January 2008 and February 2011. After institutional review board approval, natural log-transformed (ln) tIgE and fsIgE levels were analyzed using univariate and multivariate regression models to assess associations and predict fsIgE using tIgE and other covariates.

RESULTS

Soy IgE levels were strongly correlated (ρ = 0.85, P < .001), whereas egg, milk, and peanut IgE levels were substantially correlated (ρ = 0.69, 0.69, and 0.66, respectively, P < .001) with tIgE. A 1-unit increase in ln(tIgE) was significantly correlated with unit increases in ln(egg IgE) (0.77), ln(milk IgE) (0.84), ln(peanut IgE) (0.87), and ln(soy IgE) (0.89) (P < .001). The ln(tIgE)-based univariate models could predict fsIgE in the validation data with strong (soy) and substantial (egg, milk, and peanut) predictive ability (P < .001).

CONCLUSION

Our study found significant and parallel relationships between tIgE and fsIgE levels to egg, milk, peanut, and soy. It underscores the importance of examining fsIgE levels in context of tIgE while making diagnostic and management decisions in children with food allergies.

Oral immunotherapy for food allergy: clinical and preclinical studies

Food allergies affect approximately 5% of the U.S. population and have increased in the last decade. In recent years, oral immunotherapy (OIT) has been tested in clinical trials for peanut, milk, and egg allergies in young children. OIT appears to be fairly well tolerated by most subjects and leads to desensitization with a greatly increased threshold of allergen required to induce reactions. Further approaches being investigated in preclinical studies in mouse models indicate the potential for using adjuvants, such as TLR9 agonists in combination with OIT; peptide OIT; and non-allergen specific applications such as herbal formulations. Further questions about OIT remain, including the optimal dosing and length of treatment; whether tolerance can be developed; and the exact cellular mechanisms resulting in protection following OIT. With many clinical trials underway across the United States and other countries, and a growing pipeline of preclinical research with translational potential, there is great hope for a widely applicable food allergy treatment.

Significance of Ara h 2 in clinical reactivity and effect of cooking methods on allergenicity

BACKGROUND

The prevalence and clinical severity of peanut allergy vary between Western countries and Asia. It has been suggested that cooking methods are responsible for this discrepancy.

OBJECTIVES

To evaluate the specific IgE responses to major peanut allergens in peanut allergic Korean children and to examine the influence of different cooking methods on peanut proteins.

METHODS

Raw peanut protein extracts were immunolabeled with serum samples from 42 children with a level of peanut specific IgE of 15 kUA/L or higher to detect specific binding to Ara h 1, Ara h 2, and Ara h 3. Clinical severity scores were assessed on a scale of 0 to 5. Protein extracts from boiled, roasted, fried, and pickled peanuts were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting with pooled serum samples from 7 patients.

RESULTS

Most patients' serum samples reacted with Ara h 1 (76.2%) and Ara h 3 (78.6%) from raw peanuts, whereas only 53.0% of patients had specific IgE against Ara h 2. IgE binding to Ara h 2 was more prevalent in patients with more severe reaction than in those with mild reactions. IgE binding to Ara h 2 was increased by roasting, but there was significantly less IgE binding after vinegar treatment.

CONCLUSION

Our results suggest that Ara h 2 is an important allergen to predict clinical symptoms but less prevalent in Korean children than in Western children. This finding may be attributed in part to different cooking methods and dietary habits among regions.

The future of food allergy therapeutics

Food allergy is increasing in prevalence in westernized countries, leading to significant morbidity including nutritional deficiencies and growth delay as well as psychosocial burdens and the potential for fatal anaphylaxis. There is currently no effective form of therapy, and the mainstay of treatment remains strict avoidance. However, there are a number of promising therapeutic strategies currently being investigated for the treatment of food allergies. Allergen-specific approaches, such as various forms of immunotherapy, have been a major focus of investigation and appear to be promising methods of desensitization. More recently, the addition of anti-IgE monoclonal antibodies (mAbs) to immunotherapy regimens has been studied. Early work with antigen-fixed leukocytes in a murine model has shown promise in inducing tolerance, as have vaccines containing modified recombinant food proteins coadministered with heat-killed Escherichia coli. Nonspecific approaches include a Chinese herbal formulation, anti-IgE mAbs, and Trichuris suis ova therapy. The array of treatment modalities currently being investigated increases the likelihood of finding one or more effective therapies for the treatment of food allergy.

Diagnostic value of hazelnut allergy tests including rCor a 1 spiking in double-blind challenged children

BACKGROUND

The diagnostic value of hazelnut allergy tests in double-blind challenged children is largely unknown. The aim of this study was to analyze the performance of current diagnostic tests for hazelnut allergy in children and the effect of spiking.

METHODS

Data of 151 children who underwent a double-blind placebo-controlled food challenge for hazelnut were analyzed. The positive predictive value and negative predictive value (PPV/NPV) of level of specific IgE (sIgE) for hazelnut, the influence of rCor a 1 spiking of the ImmunoCAP, and size of the skin prick test (SPT) for hazelnut were determined, also in relation to the severity of the hazelnut allergy. Reported accidental ingestion leading to an allergic reaction to hazelnut was also analyzed in relation to hazelnut allergy.

RESULTS

Specific IgE ≥0.35 kU(A) /l for hazelnut was a moderate predictor for hazelnut allergy. The spiking decreased the PPV from 41% to 38% and increased the NPV from 91% to 100% for sIgE ≥0.35 kU(A) /l. The maximum reached PPV was 73% for sIgE cutoff of 26 kU(A) /l. Level of sIgE before spiking was significantly different between different grades of severity and was lost after spiking. Skin prick test was a better predictor for hazelnut allergy and severity than the level of sIgE. A history of accidental ingestion leading to an allergic reaction to hazelnut had a predictive value of 59% for hazelnut allergy.

CONCLUSIONS

This study showed a good NPV of diagnostic tests for hazelnut allergy in children which further improved by rCor a 1 spiking. However, the PPVs are moderate and decreased by spiking.

Immunology in the Clinic Review Series; focus on allergies: immunotherapy for food allergy

There is no approved therapy for food allergy. The current standard of care is elimination of the triggering food from the diet and accessibility to epinephrine. Immunotherapy is a promising treatment approach. While desensitization to most foods seems feasible, it remains unclear if a permanent state of tolerance is achievable. The research team at Duke is pioneering immunotherapy for food allergies. Work here has evolved over time from small open-label pilot studies to larger randomized designs. Our data show that immunological changes associated with immunotherapy include reduction in mast cell reactivity, decreased basophil responses, decreased specific-immunoglobulin (Ig)E, increased IgG4 and induction of regulatory T cells. Immunotherapy has generated much excitement in the food allergy community; however, further studies are needed before it is ready for clinical use.

Structural and immunologic characterization of Ara h 1, a major peanut allergen

Allergic reactions to peanuts and tree nuts are major causes of anaphylaxis in the United States. We compare different properties of natural and recombinant versions of Ara h 1, a major peanut allergen, through structural, immunologic, and bioinformatics analyses. Small angle x-ray scattering studies show that natural Ara h 1 forms higher molecular weight aggregates in solution. In contrast, the full-length recombinant protein is partially unfolded and exists as a monomer. The crystal structure of the Ara h 1 core (residues 170-586) shows that the central part of the allergen has a bicupin fold, which is in agreement with our bioinformatics analysis. In its crystalline state, the core region of Ara h 1 forms trimeric assemblies, while in solution the protein exists as higher molecular weight assemblies. This finding reveals that the residues forming the core region of the protein are sufficient for formation of Ara h 1 trimers and higher order oligomers. Natural and recombinant variants of proteins tested in in vitro gastric and duodenal digestion assays show that the natural protein is the most stable form, followed by the recombinant Ara h 1 core fragment and the full-length recombinant protein. Additionally, IgE binding studies reveal that the natural and recombinant allergens have different patterns of interaction with IgE antibodies. The molecular basis of cross-reactivity between vicilin allergens is also elucidated.

The ability of adults and children to visually identify peanuts and tree nuts

BACKGROUND

Peanuts and tree nuts are common food allergens and are the leading cause of fatalities from food-induced anaphylaxis. Dietary avoidance is the primary management of these allergies and requires the ability to identify peanuts or tree nuts.

OBJECTIVES

To investigate the ability of adults and children to visually identify peanuts and tree nuts.

METHODS

A nut display was assembled that held peanuts and 9 tree nuts in a total of 19 different forms. Persons 6 years or older completed a worksheet to name the items.

RESULTS

One-thousand one-hundred five subjects completed the study. The mean number of peanuts and tree nuts identified by all subjects was 8.4 (44.2%) out of a possible 19. The mean for children ages 6 to 18 was 4.6 (24.2%), compared with 11.1 (58.4%) for adults older than 18 (P < .001). The most commonly identified items were peanut in the shell and without the shell. The least identified was hazelnut (filbert) in the shell and without the shell. No difference was seen in the performance of peanut- or tree nut-allergic subjects compared with nonallergic subjects. Fifty percent of subjects with a peanut or tree nut allergy correctly identified all forms of peanuts or tree nuts to which they are allergic. Parents of peanut- or tree nut-allergic children did no better than parents of children without such allergy.

CONCLUSIONS

Overall, both children and adults are unreliable at visually identifying most nuts. Treatment of nut allergies with dietary avoidance should include education for both adults and children on identification of peanuts and tree nuts.

A randomized controlled study of peanut oral immunotherapy: clinical desensitization and modulation of the allergic response

BACKGROUND

Open-label oral immunotherapy (OIT) protocols have been used to treat small numbers of patients with peanut allergy. Peanut OIT has not been evaluated in double-blind, placebo-controlled trials.

OBJECTIVE

To investigate the safety and effectiveness of OIT for peanut allergy in a double-blind, placebo-controlled study.

METHODS

In this multicenter study, children ages 1 to 16 years with peanut allergy received OIT with peanut flour or placebo. Initial escalation, build-up, and maintenance phases were followed by an oral food challenge (OFC) at approximately 1 year. Titrated skin prick tests (SPTs) and laboratory studies were performed at regular intervals.

RESULTS

Twenty-eight subjects were enrolled in the study. Three peanut OIT subjects withdrew early in the study because of allergic side effects. During the double-blind, placebo-controlled food challenge, all remaining peanut OIT subjects (n = 16) ingested the maximum cumulative dose of 5000 mg (approximately 20 peanuts), whereas placebo subjects (n = 9) ingested a median cumulative dose of 280 mg (range, 0-1900 mg; P < .001). In contrast with the placebo group, the peanut OIT group showed reductions in SPT size (P < .001), IL-5 (P = .01), and IL-13 (P = .02) and increases in peanut-specific IgG(4) (P < .001). Peanut OIT subjects had initial increases in peanut-specific IgE (P < .01) but did not show significant change from baseline by the time of OFC. The ratio of forkhead box protein 3 (FoxP3)(hi): FoxP3(intermediate) CD4+ CD25+ T cells increased at the time of OFC (P = .04) in peanut OIT subjects.

CONCLUSION

These results conclusively demonstrate that peanut OIT induces desensitization and concurrent immune modulation. The current study continues and is evaluating the hypothesis that peanut OIT causes long-term immune tolerance.

Epidemiology of food allergy

Food allergy (FA) is perceived as a common problem, especially during childhood. Accurate assessment of incidence and prevalence of FA has been difficult to establish, however, due to lack of universally accepted diagnostic criteria. Although many foods are reported to cause IgE-mediated FA, most studies focus on 4 common food groups: cow's milk, hen's egg, peanut/tree nuts, and fish/shellfish. There may be variation in the prevalence of FA in regions of the world and a likely increase in prevalence has been observed in recent decades. This cannot be stated with confidence, however, without the use of consistent methodology and diagnostic criteria.

Characterizing the relationship between sesame, coconut, and nut allergy in children

Sesame and coconut are emerging food allergens in the United States. We sought to examine whether children allergic to peanuts and tree nuts are at increased risk of having an allergy to sesame or coconut. We performed a retrospective chart review of children who underwent skin prick testing (SPT) to sesame and coconut and identified 191 children who underwent SPT to sesame and 40 to coconut. Sensitization to sesame was more likely in children with positive SPT to peanuts (odds ratio [OR] = 6.7, 95% confidence interval [CI] [2.7-16.8], p < 0.001) and tree nuts (OR = 10.5, 95% CI [4.0-27.7], p < 0.001). Children with histories of both peanut and tree nut reaction were more likely to have a history of sesame reaction (OR = 10.2, 95% CI [2.7-38.7], p < 0.001). Children with sensitization or allergy to peanuts or tree nuts were not more likely to be sensitized or allergic to coconut. In conclusion, children with peanut or tree nut sensitization were more likely to be sensitized to sesame but not coconut. Children with clinical histories of both peanut and tree nut allergy were more likely to be allergic to sesame.