The Effect of the Food Matrix on the in vitro Bio-Accessibility and IgE Reactivity of Peanut Allergens.
Scope: Factors such as food processing, the food matrix and antacid medication may affect the bio-accessibility of proteins in the gastrointestinal tract and hence their allergenic activity. However, at present they are poorly understood. Methods and results: Roasted peanut flour was incurred into either a chocolate dessert or cookie matrix and bio-accessibility assessed using an in vitro digestion system comprising a model chew and simulated gastric and duodenal digestion. Protein digestion was monitored by SDS-PAGE and immunoreactivity analysed by immunoblotting and immunoassay. IgE reactivity was assessed by immunoassay using serum panels from peanut-allergic subjects. Roasted peanut flour proteins proved highly digestible following gastro-duodenal digestion even when incurred into a food matrix, with only low molecular weight polypeptides of Mr<8 kDa remaining. When gastric digestion was performed at pH 6.5 (simulating the effect of antacid medication) peanut proteins were not digested; subsequent duodenal digestion was also limited. IgE reactivity of the major peanut allergens Ara h 1, Ara h 2 and Ara h 6, although reduced, was retained after oral-gastro-duodenal digestion irrespective of digestion conditions employed. Conclusion: Peanut allergen bio-accessibility was unaffected by the dessert or cookie matrices whilst high intra-gastric pH conditions rendered allergens more resistant to digestion.
Prevalence of Food Sensitization and Food Allergy in Children across Europe.
Background: For adults, prevalence estimates of food sensitization (FS) and food allergy (FA) have been obtained in a standardized manner across Europe. For children, such estimates are lacking. Objectives: To determine prevalence of self-reported FA, FS, probable FA (symptoms plus IgE-sensitization), and challenge-confirmed FA in European school-age children. Methods: Data on self-reported FA were collected through a screening questionnaire sent to a random sample of the general population of 7- to 10-year-old children in eight European centres in phase I of the EuroPrevall study. Data on FS and probable FA were obtained in phase II, comprising an extensive questionnaire on reactions to 24 commonly implicated foods, and serology testing. Food challenge was performed in phase III. Results: Prevalence (95%-CI) of self-reported FA ranged from 6.5% (5.4-7.6) in Athens to 24.6% (22.8-26.5) in Lodz; prevalence of FS from 11.0% (9.7-12.3) in Reykjavik to 28.7% (26.9-30.6) in Zurich; and prevalence of probable FA from 1.9% (0.8-3.5) in Reykjavik to 5.6% (3.6-8.1) in Lodz. In all centres, the majority of food-sensitized subjects had primary (non-cross-reactive) FS. However, FS due to PR-10 cross-reactivity was also common in Central-Northern Europe. Probable FA to milk and egg occurred frequently throughout Europe; to fish and shrimp mainly in the Mediterranean and Reykjavik. Peach, kiwi and peanut were prominent sources of plant FA in most countries, along with notably hazelnut, apple, carrot and celery in Central-Northern Europe, and lentils and walnut in the Mediterranean. Conclusion: There are large geograhical differences in prevalence of FS and FA in school-age children across Europe. Both primary and cross-reactive FS and FA occur frequently.
Identification of cross‐reactive allergens in cashew‐and pistachio‐allergic children during oral immunotherapy.
It has been estimated that around 8% of the children in the U.S. suffer from food allergy and of those, 40% are allergic to multiple foods. Among tree nuts, allergies to pistachios are common in those with cashew nut allergy and multiple homologous allergenic components are shared between the two nuts. Three major allergens from cashew (Ana o 1 at 50 kDa, Ana o 2 major band at 33 kDa and minor band at 53 kDa, and Ana o 3 at 10 kDa) and five major allergens from pistachio (Pis v 1 at 7 kDa, Pis v 2 at 32 kDa, Pis v 3 at 50 kDa, Pis v 4 at 23 kDa, and Pis v 5 at 36 kDa) have been identified. Of those, Ana o 1 and Pis v 3, Ana o 2 and Pis v 2, Ana o 2 and Pis v 5, Ana o 3 and Pis v 1 have been recognized as homologues based on their sequence similarity and cross reactivity to IgE from the patients.
Peanut Oral Immunotherapy: a Current Perspective.
Purpose of the review: Peanut oral immunotherapy (OIT) is one of the most studied experimental therapies for food allergy. With the recently FDA-approved peanut product, Palforzia, the goal of this article is to review the most recent data from clinical trials, discuss recent trends, and anticipate future developments. Recent findings: The latest research suggests that peanut OIT could be a promising option for peanut-allergic patients, with the majority of participants in research studies achieving the primary efficacy endpoint of desensitization, as well as sustained unresponsiveness in select populations. Some studies also showed improvements in food allergy-related quality of life. However, peanut OIT is not without risk or side effects, including potentially serious allergic reactions. Future research will need to evaluate the short- and long-term effectiveness of the therapy in the real-world setting, predictors of important treatment outcomes, and the use of adjunctive therapies that may mitigate some of these allergic reactions.
Ara h 2 is the dominant peanut allergen despite similarities with Ara h 6.
Background: Ara h 2 specific-IgE (sIgE) is to date the best serologic marker to diagnose peanut allergy. Ara h 6 shares ∼60% sequence identity and multiple epitopes with Ara h 2. Objective: To assess the diagnostic utility and relative importance of Ara h 2 and Ara h 6 in peanut allergy. Methods: A cohort (n=100) of peanut allergic (PA), peanut sensitized but tolerant (PS) and non-sensitized non-allergic (NA) children were studied. sIgE levels to peanut and individual allergens were quantified using ImmunoCAP. ImmunoCAP inhibition experiments and mast-cell activation tests (MAT) were performed to both Ara h 2 and Ara h 6. Statistical analyses were performed using SPSS v14 and Prism v7. Results: Ara h 2-sIgE and Ara h 6-sIgE showed the greatest diagnostic accuracy for peanut allergy compared with sIgE to peanut and other peanut allergens. Most PA patients were sensitized to both Ara h 2 and Ara h 6. Ara h 2 reduced Ara h 2-sIgE binding more than Ara h 6 (p<0.001) whereas Ara h 6-sIgE binding was inhibited to a similar degree by Ara h 2 and Ara h 6 (p=0.432). On the MAT, Ara h 2 induced significantly greater maximal reactivity (p=0.001) and lower EC50 (p=0.002) than Ara h 6 when testing co-sensitized individuals. Conclusions: Ara h 2-sIgE and Ara h 6-sIgE provide the greatest accuracy for diagnosis peanut allergy. Ara h 2 is the dominant conglutin in peanut allergy in the UK, despite a degree of cross-reactivity with Ara h 6.
Sequence analysis of digestion-resistant peptides may be an efficient strategy for studying the linear epitopes of Jug r 1, the major walnut allergen.
Jug r 1, the major allergen of walnut, triggers severe allergic reactions through epitopes. Hence, research on the efficient strategy for analyzing the linear epitopes of Jug r 1 are necessary. In this work, bioinformatics analysis was used to predict the linear epitopes of Jug r 1. Overlapping peptide synthesis was used to map linear epitopes. In vitro simulated gastrointestinal digestion and HPLC-MS/MS were used to identify digestion-resistant peptides. The results showed that six predicted linear epitopes were AA28-35, AA42-49, AA55-62, AA65-73, AA97-104, and AA109-121. AA16-30 and AA125-139 were identified by the sera of walnut allergic patients. Five digestion-resistant peptides were AA19-33, AA40-45, AA54-74, AA96-106, and AA117-137. The predicted results only included one of the linear epitopes identified by sera, while the digestion-resistant peptides covered all. Therefore, the digestion-resistant property of food allergens may be a promising direction for studying the linear epitopes of Jug r 1.
Almond allergens: update and perspective on identification and characterization.
Almond (Prunus dulcis) is widely used as a human food due to its flavor, nutrients, and health benefits, but it is also one of the most likely tree nuts to trigger allergies. Almond allergens, though, have not been studied as extensively as those of peanuts and other selected tree nuts. This work presents an update of the molecular properties of almond allergens to clarify some confusion about the identities of almond allergens and our perspective on characterizing putative almond allergens. Presently, the following almond allergens have been designated by the WHO/IUIS Allergen Nomenclature Sub-Committee: Pru du 3 (a non-specific lipid transfer protein 1, nsLTP1), Pru du 4 (a profilin), Pru du 5 (60S acidic ribosomal protein 2), Pru du 6 (an 11S legumin known as prunin), and Pru du 8 (an antimicrobial protein with cC3C repeats). Besides, almond vicilin and almond γ-conglutin have been identified as food allergens, although further characterization of these allergens is still of interest. In addition, almond 2S albumin was reported as a food allergen due to the misidentification of Pru du 8. Two more almond proteins have been called allergens based on their sequence homology with known food allergens and their 'membership' in relevant protein families that contain allergens in many species. These include the pathogenesis related-10 protein (referred to as Pru du 1) and the thaumatin-like protein (referred to as Pru du 2). Almonds thus have 5 known food allergens and five more likely ones that need to be investigated further.
Influence of Instant Controlled Pressure Drop (DIC) on Allergenic Potential of Tree Nuts.
Pistachio and cashew contain allergenic proteins, which causes them to be removed from the diet of allergic people. Previous studies have demonstrated that food processing (thermal and non-thermal) can produce structural and/or conformational changes in proteins by altering their allergenic capacity. In this study, the influence of instant controlled pressure drop (DIC) on pistachio and cashew allergenic capacity has been studied. Western blot was carried out using IgG anti-11S and anti-2S and IgE antibodies from sera of patients sensitized to pistachio and cashew. DIC processing causes changes in the electrophoretic pattern, reducing the number and intensity of protein bands, as the pressure and temperature treatment increment, which results in a remarkable decrease in detection of potentially allergenic proteins. The harshest conditions of DIC (7 bar, 120 s) markedly reduce the immunodetection of allergenic proteins, not only by using IgG (anti 11S and anti 2S) but also when IgE sera from sensitized patients were used for Western blots. Such immunodetection is more affected in pistachio than in cashew nuts, but is not completely removed. Therefore, cashew proteins are possibly more resistant than pistachio proteins. According these findings, instant controlled pressure drop (DIC) can be considered a suitable technique in order to obtain hypoallergenic tree nut flour to be used in the food industry.
Allergen Removal and Transfer Using Wiping and Cleaning Methods in Retail and Food Service Establishments.
Preventing the transfer of allergens from one food to another via food-contact surfaces in retail food environments is an important aspect of retail food safety. Existing recommendations for wiping and cleaning food-contact surfaces is mainly focused on preventing microorganisms such as bacteria and viruses from contaminating foods. The effectiveness of these wiping and cleaning recommendations for preventing the transfer of food allergens in retail and food service establishments remains unclear. This project investigated: 1) allergen removal from surfaces by wiping with paper wipes, terry cloths and alcohol/quaternary ammonium chloride (quat) sanitizing wipes; 2) cleaning of allergen-contaminated surfaces using a wash-rinse-sanitize-air dry procedure; and 3) allergen transfer from contaminated wipes to multiple surfaces. Food-contact surfaces (stainless steel, textured plastic and maple wood) were contaminated with peanut-, milk- and egg-containing foods, and subjected to various wiping and cleaning procedures. For transfer experiments, dry paper wipes or wet cloths contaminated with allergenic foods were wiped on four surfaces of the same composition. Allergen-specific lateral flow devices were used to detect the presence of allergen residues on wiped or cleaned surfaces. While dry wipes and cloths were not effective for removing allergenic foods, terry cloths pre-soaked in water or sanitizer solution, use of multiple quat wipes, and the wash-rinse-sanitize-air dry procedure were effective in allergen removal from surfaces. Allergens present on dry wipes were transferred to wiped surfaces. In contrast, minimal or no allergen transfer to surfaces was found when allergen-contaminated terry cloths were submerged in sanitizer solution prior to wiping surfaces. The full cleaning method (wash-rinse-sanitize-air dry) and soaking the terry cloth in sanitizer solution prior to wiping were effective at allergen removal and minimizing allergen transfer.
Updated population minimal eliciting dose distributions for use in risk assessment of 14 priority food allergens.
Food allergy and allergen management are important global public health issues. In 2011, the first iteration of our allergen threshold database (ATDB) was established based on individual NOAELs and LOAELs from oral food challenge in roughly 1750 allergic individuals. Population minimal eliciting dose (EDp) distributions based on this dataset were published for 11 allergenic foods in 2014. Systematic data collection has continued (2011-2018) and the dataset now contains over 3400 data points. The current study provides new and updated EDp values for 14 allergenic foods and incorporates a newly developed Stacked Model Averaging statistical method for interval-censored data. ED01 and ED05 values, the doses at which 1%, and respectively 5%, of the respective allergic population would be predicted to experience any objective allergic reaction were determined. The 14 allergenic foods were cashew, celery, egg, fish, hazelnut, lupine, milk, mustard, peanut, sesame, shrimp (for crustacean shellfish), soy, walnut, and wheat. Updated ED01 estimates ranged between 0.03 mg for walnut protein and 26.2 mg for shrimp protein. ED05 estimates ranged between 0.4 mg for mustard protein and 280 mg for shrimp protein. The ED01 and ED05 values presented here are valuable in the risk assessment and subsequent risk management of allergenic foods.