Structural and Functional Characterization of the Hazelnut Allergen Cor a 8
Nonspecific lipid transfer proteins (nsLTPs) are basic proteins, stabilized by four disulfide bonds, and are expressed throughout the plant kingdom. These proteins are also known as important allergens in fruits and tree nuts. In this study, the nsLTP from hazelnuts, Cor a 8, was purified and its crystal structure determined. The protein is stable at low pH and refolds after thermal denaturation. Molecular dynamics simulations were used to provide an insight into conformational changes of Cor a 8 upon ligand binding. When known epitope areas from Pru p 3 were compared to those of Cor a 8, differences were obvious, which may contribute to limited cross-reactivity between peach and hazelnut allergens. Differences in epitope regions may contribute to limited cross-reactivity between Cor a 8 and nsLTPs from other plant sources. The structure of Cor a 8 represents the first resolved structure of a hazelnut allergen.
Insoluble and soluble roasted walnut proteins retain antibody reactivity
Thermal processing techniques commonly used during food production have the potential to impact food allergens by inducing physical and/or chemical changes to the proteins. English walnuts (Juglans regia) are among the most commonly allergenic tree nuts, but little information is available regarding how walnut allergens respond to thermal processing. This study evaluated the effects of dry roasting (132 or 180°C for 5, 10, or 20min) on the solubility and immunoreactivity of walnut proteins. A dramatic decrease in walnut protein solubility was observed following dry roasting at 180°C for 20min. However, both the soluble and insoluble protein fractions from roasted walnuts maintained substantial amounts of IgG immunoreactivity (using anti-raw and anti-roasted walnut antisera), with similar patterns of reactivity observed for human IgE from walnut-allergic individuals. Thus, walnut proteins are relatively stable under certain thermal processing conditions, and IgE reactivity remains present even when insoluble aggregates are formed.
Sensitive and specific detection of pine nut (Pinus spp.) by real-time PCR in complex food products
Pine nuts are a known source of food allergens and several cases of adverse immunological reaction after ingestion have been reported. To protect allergic consumers, methods to unequivocally detect the presence of pine nuts in complex matrices must be developed. A Taqman-based real time PCR method for the detection of Pinus spp. was set up. A homemade pesto spiked at known concentration of pine nut powder was used as model food. Moreover, DNA was purified from commercial foods declaring or not the presence of pine nuts. The method displayed a very high efficiency and specificity for the genus Pinus. The intrinsic LOD was 1pg of DNA, while the practical LOD evaluated on model foods was 0.1ppm of pine nuts powder, the lowest ever registered for the detection of food allergens via real-time PCR. Finally, the declared presence/absence of pine nut in commercial foods was confirmed.
Peanut allergy as a trigger for the deterioration of atopic dermatitis and precursor of staphylococcal and herpetic associated infections - case report
Atopic dermatitis (AD) is a multifactorial and chronic disease, with genetic, environmental, immunological and nutritional origins. AD may be aggravated by allergies associated with infections. This study aims to describe a paediatric case of AD in which the peanut allergy was the triggering factor to aggravate the disease, and was also the concomitant precursor of staphylococcal (methicillin-sensitive Staphylococcus aureus, carrier of the Panton-Valentine leukocidine (PVL) genes) and herpetic (Herpes Simplex - HSV) infections. The clinical management approach and nursing strategies promoted a favourable evolution during the hospitalization period, besides the family approach, which was essential to control any flare-up of the disease. Adherence to a recommended diet and the use of strategies to prevent any recurrent infections were important to ensure the patient's quality of life.
The Learning Early About Peanut Allergy Study: The Benefits of Early Peanut Introduction, and a New Horizon in Fighting the Food Allergy Epidemic
Observational studies have explored associations between timing of peanut, egg, and milk introduction and food allergy development, noting significant associations with reduced respective rates of milk, egg, and peanut allergy associated with earlier timing of introduction. Interventional studies developed to more definitively explore these outcomes have been published for egg and peanut, and are ongoing for multiple other allergens. This review focuses on the recent publication regarding the LEAP (Learning Early About Peanut Allergy) study, its highly favorable results, the policy implications of its findings, and the horizon for primary prevention as a realistic strategy to prevent food allergy.
Food allergic infants have impaired regulatory T cell responses following in vivo allergen exposure
BACKGROUND: Regulatory T cells (Tregs) are critical for development of oral tolerance, and studies suggest that dysfunction of Tregs may lead to food allergy. However to date no study has investigated Treg responses following in vivo exposure to peanut or egg allergens in humans. OBJECTIVES: To examine changes in peripheral blood CD4+ CD25+ FoxP3+ Treg populations (total, activated, and naive) in food allergic, food-sensitised but tolerant, and healthy (non-sensitised non-allergic) patients over time following in vivo allergen exposure. METHODS: A subset of infants from the HealthNuts study with egg or peanut allergy (n=37), egg or peanut sensitisation (n=35), or who were non-sensitised non-allergic (n=15) were studied. All subjects underwent oral food challenge (OFC) to egg or peanut. PBMC were obtained within 1 hour of OFC (in vivo allergen exposure); and Treg populations enumerated ex vivo on day 0, and after 2 and 6 days rest in vitro. RESULTS: Non-allergic infants showed stable total Treg frequencies over time; food-sensitised infants had a transient fall in Treg percentage with recovery to baseline by day 6 (6.87% day 0, 5.27% day 2, 6.5% day 6); and food allergic infants showed persistent reduction in Treg (6.85% day 0, 5.4% day 2, 6.2% day 6) following in vivo allergen exposure. Furthermore, food allergic infants had a significantly lower ratio of activated Treg:activated T-cells (10.5±0.77) at day 0 compared to food-sensitised (14.6±1.24) and non-allergic subjects (16.2±1.23). CONCLUSION: Our data suggest that the state of allergen sensitisation is associated with depletion of Treg following allergen exposure. Impaired capacity to regenerate the Treg pool following allergen exposure may be an important factor that determines clinical allergy versus sensitisation without allergic reaction.
Food entries in a large allergy data repository
OBJECTIVE: Accurate food adverse sensitivity documentation in electronic health records (EHRs) is crucial to patient safety. This study examined, encoded, and grouped foods that caused any adverse sensitivity in a large allergy repository using natural language processing and standard terminologies. METHODS: Using the Medical Text Extraction, Reasoning, and Mapping System (MTERMS), we processed both structured and free-text entries stored in an enterprise-wide allergy repository (Partners' Enterprise-wide Allergy Repository), normalized diverse food allergen terms into concepts, and encoded these concepts using the Systematized Nomenclature of Medicine - Clinical Terms (SNOMED-CT) and Unique Ingredient Identifiers (UNII) terminologies. Concept coverage also was assessed for these two terminologies. We further categorized allergen concepts into groups and calculated the frequencies of these concepts by group. Finally, we conducted an external validation of MTERMS's performance when identifying food allergen terms, using a randomized sample from a different institution. RESULTS: We identified 158 552 food allergen records (2140 unique terms) in the Partners repository, corresponding to 672 food allergen concepts. High-frequency groups included shellfish (19.3%), fruits or vegetables (18.4%), dairy (9.0%), peanuts (8.5%), tree nuts (8.5%), eggs (6.0%), grains (5.1%), and additives (4.7%). Ambiguous, generic concepts such as "nuts" and "seafood" accounted for 8.8% of the records. SNOMED-CT covered more concepts than UNII in terms of exact (81.7% vs 68.0%) and partial (14.3% vs 9.7%) matches. DISCUSSION: Adverse sensitivities to food are diverse, and existing standard terminologies have gaps in their coverage of the breadth of allergy concepts. CONCLUSION: New strategies are needed to represent and standardize food adverse sensitivity concepts, to improve documentation in EHRs.
Utility of component analyses in subjects undergoing sublingual immunotherapy for peanut allergy
BACKGROUND: Sublingual immunotherapy (SLIT) with peanut changes clinical and immune responses in most peanut-allergic individuals, but the response is highly variable. OBJECTIVE: We sought to examine the component-specific effects of peanut SLIT and determine whether peanut component testing could predict the outcome of a double-blind, placebo-controlled food challenge (DBPCFC) after 12 months of peanut SLIT. METHODS: We included 33 subjects who underwent peanut SLIT with a DBPCFC of 2500 mg of peanut protein performed after 12 months on therapy. Plasma samples from baseline and after 12 months of peanut SLIT were assayed using ImmunoCAP for IgE and IgG4 against whole peanut, Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Ara h 9.
RESULTS: Following 12 months of SLIT, 10 subjects (30%) passed the DBPCFC without symptoms and were considered desensitized. Subjects that failed the DBPCFC tolerated a median of 460 mg peanut protein (range: 10-1710 mg). The desensitized group had significantly lower baseline levels of IgE against peanut (median 40.8 vs 231 kUA /L, p = 0.0082), Ara h 2 (median 17 vs 113 kUA /L, p=0.0082), and Ara h 3 (median 0.3 vs 8.5 kUA /L, p = 0.0396). ROC curves indicated that baseline IgE against peanut and Ara h 2 were equally effective at discriminating between the two groups (AUC = 0.7957, p = 0.007752 for both). CONCLUSION AND CLINICAL RELEVANCE: In this cohort of subjects undergoing SLIT for peanut allergy, lower baseline levels of IgE against Ara h 2, Ara h 3, and peanut were associated with successful desensitization.
Consensus Communication on Early Peanut Introduction and Prevention of Peanut Allergy in High-Risk Infants.
The purpose of this brief communication is to highlight emerging evidence regarding potential benefits of supporting early rather than delayed peanut introduction during the period of complementary food introduction in infants. This document should be considered as interim guidance based on consensus among the following organizations: American Academy of Allergy, Asthma, and Immunology, American Academy of Pediatrics, American College of Allergy, Asthma, and Immunology, Australasian Society of Clinical Immunology and Allergy, Canadian Society of Allergy and Clinical Immunology, European Academy of Allergy and Clinical Immunology, Israel Association of Allergy and Clinical Immunology, Japanese Society for Allergology, Society for Pediatric Dermatology, and World Allergy Organization. More formal guidelines regarding early-life, complementary feeding practices and the risk of allergy development will follow in the next year from the National Institute of Allergy and Infectious Diseases-sponsored Working Group and the European Academy of Allergy and Clinical Immunology.
Oral Immunotherapy for Peanut Allergy
Peanut allergy is a common disease and the cause of severe, life-threatening allergic reactions and death. It is rarely outgrown; most pediatric patients carry the disease into adulthood. Peanut allergy poses a significant burden on the quality of life of sufferers and their families, which results mainly from the fear of accidental peanut ingestion but is also due to dietary and social restrictions. Current standard management involves avoidance advice, patient education, and provision of emergency rescue medication. Immunotherapy, commonly used to treat other allergic diseases, has shown promise as a disease-modifying therapy for peanut allergy. Results from studies of oral immunotherapy show high efficacy rates, improvement in quality of life, and a good safety profile. Treatment may result in sustained unresponsiveness in a proportion of patients, whereas others require ongoing treatment.