Allergic sensitization: screening methods

Experimental in silico, in vitro, and rodent models for screening and predicting protein sensitizing potential are discussed, including whether there is evidence of new sensitizations and allergies since the introduction of genetically modified crops in 1996, the importance of linear versus conformational epitopes, and protein families that become allergens. Some common challenges for predicting protein sensitization are addressed: (a) exposure routes; (b) frequency and dose of exposure; (c) dose-response relationships; (d) role of digestion, food processing, and the food matrix; (e) role of infection; (f) role of the gut microbiota; (g) influence of the structure and physicochemical properties of the protein; and (h) the genetic background and physiology of consumers. The consensus view is that sensitization screening models are not yet validated to definitively predict the de novo sensitizing potential of a novel protein. However, they would be extremely useful in the discovery and research phases of understanding the mechanisms of food allergy development, and may prove fruitful to provide information regarding potential allergenicity risk assessment of future products on a case by case basis. These data and findings were presented at a 2012 international symposium in Prague organized by the Protein Allergenicity Technical Committee of the International Life Sciences Institute’s Health and Environmental Sciences Institute

Immunological and Metabolomic Impacts of Administration of Cry1Ab Protein and MON 810 Maize in Mouse

We have investigated the immunological and metabolomic impacts of Cry1Ab administration to mice, either as a purified protein or as the Cry1Ab-expressing genetically modified (GM) MON810 maize. Humoral and cellular specific immune responses induced in BALB/cJ mice after intra-gastric (i.g.) or intra-peritoneal (i.p.) administration of purified Cry1Ab were analyzed and compared with those induced by proteins of various immunogenic and allergic potencies. Possible unintended effects of the genetic modification on the pattern of expression of maize natural allergens were studied using IgE-immunoblot and sera from maize-allergic patients. Mice were experimentally sensitized (i.g. or i.p. route) with protein extracts from GM or non-GM maize, and then anti-maize proteins and anti-Cry1Ab–induced immune responses were analyzed. In parallel, longitudinal metabolomic studies were performed on the urine of mice treated via the i.g. route. Weak immune responses were observed after i.g. administration of the different proteins. Using the i.p. route, a clear Th2 response was observed with the known allergenic proteins, whereas a mixed Th1/Th2 immune response was observed with immunogenic protein not known to be allergenic and with Cry1Ab. This then reflects protein immunogenicity in the BALB/c Th2-biased mouse strain rather than allergenicity. No difference in natural maize allergen profiles was evidenced between MON810 and its non-GM comparator. Immune responses against maize proteins were quantitatively equivalent in mice treated with MON810 vs the non-GM counterpart and no anti-Cry1Ab–specific immune response was detected in mice that received MON810. Metabolomic studies showed a slight “cultivar” effect, which represented less than 1% of the initial metabolic information. Our results confirm the immunogenicity of purified Cry1Ab without evidence of allergenic potential. Immunological and metabolomic studies revealed slight differences in mouse metabolic profiles after i.g. administration of MON810 vs its non-GM counterpart, but no significant unintended effect of the genetic modification on immune responses was seen

Rhinosinusitis derived Staphylococcal enterotoxin B plays a possible role in pathogenesis of food allergy

BACKGROUND: Staphylococcal enterotoxin B (SEB) is a potent immunomodulator and implicated with pathogenesis of inflammatory diseases mediated by Th1 or Th2 dominant immune responses. The objective of this study is to determine a possible association between rhinosinusitis derived SEB and pathogenesis of food allergy (FA). METHODS: The study included chronic rhinosinusitis (CRS) patients with FA (N = 46) or without FA (N = 33). Controls included FA patients without CRS (N = 26) and healthy volunteers (N = 25). In CRS patients, we assessed the parameters associated with FA including prick skin test (PST) reactivity to food allergens, serum levels of allergen-specific IgE and cytokines (IL-4, IL-13, IFN-Î(3)), and the number/reactivity of food-allergen specific Th1/Th2 cells in the peripheral blood before and 2 months after sinus surgery. Changes of these parameters were evaluated in comparison with changes in SEB concentration in the sinus lavage and stool samples and also in vitro reactivity to SEB. In CRS patients with FA, we also assessed changes in reactivity to oral challenge of offending food before and after sinus surgery. RESULTS: Two months following sinus surgery, we observed statistically significant reduction in PST and oral challenge reactivity in CRS patients with FA in parallel to decrease in serum levels of Th2 cytokines (IL-4 and IL-13) and allergen specific IgE. Improvement of reactivity to food allergens was positively associated with decline in SEB concentrations in the sinus lavage and stool samples. In vitro study results also indicated a role of SEB in aggravation of Th2 skewed responses to food allergens. Such changes were not observed in CRS-non FA patients or control FA patients. CONCLUSION: The rhinosinusitis derived SEB plays a certain role in the pathogenesis of FA by augmenting and/or maintaining polarized Th2 responses. Removal of SEB-producing pathogens from the rhinosinuses may be beneficial for attenuating the FA symptoms in patients with CRS-FA

Suggested Improvements for the Allergenicity Assessment of Genetically Modified Plants Used in Foods

Genetically modified (GM) plants are increasingly used for food production and industrial applications. As the global population has surpassed 7 billion and per capita consumption rises, food production is challenged by loss of arable land, changing weather patterns, and evolving plant pests and disease. Previous gains in quantity and quality relied on natural or artificial breeding, random mutagenesis, increased pesticide and fertilizer use, and improved farming techniques, all without a formal safety evaluation. However, the direct introduction of novel genes raised questions regarding safety that are being addressed by an evaluation process that considers potential increases in the allergenicity, toxicity, and nutrient availability of foods derived from the GM plants. Opinions vary regarding the adequacy of the assessment, but there is no documented proof of an adverse effect resulting from foods produced from GM plants. This review and opinion discusses current practices and new regulatory demands related to food safety

Effects of Feeding Bt MON810 Maize to Pigs for 110 Days on Peripheral Immune Response and Digestive Fate of the cry1Ab Gene and Truncated Bt Toxin

peer-reviewedBackground: The objective of this study was to evaluate potential long-term (110 days) and age-specific effects of feeding genetically modified Bt maize on peripheral immune response in pigs and to determine the digestive fate of the cry1Ab gene and truncated Bt toxin. Methodology/Principal Findings: Forty day old pigs (n = 40) were fed one of the following treatments: 1) isogenic maize-based diet for 110 days (isogenic); 2) Bt maize-based diet (MON810) for 110 days (Bt); 3) Isogenic maize-based diet for 30 days followed by Bt maize-based diet for 80 days (isogenic/Bt); and 4) Bt maize-based diet (MON810) for 30 days followed by isogenic maize-based diet for 80 days (Bt/isogenic). Blood samples were collected during the study for haematological analysis, measurement of cytokine and Cry1Ab-specific antibody production, immune cell phenotyping and cry1Ab gene and truncated Bt toxin detection. Pigs were sacrificed on day 110 and digesta and organ samples were taken for detection of the cry1Ab gene and the truncated Bt toxin. On day 100, lymphocyte counts were higher (P<0.05) in pigs fed Bt/isogenic than pigs fed Bt or isogenic. Erythrocyte counts on day 100 were lower in pigs fed Bt or isogenic/Bt than pigs fed Bt/isogenic (P<0.05). Neither the truncated Bt toxin nor the cry1Ab gene were detected in the organs or blood of pigs fed Bt maize. The cry1Ab gene was detected in stomach digesta and at low frequency in the ileum but not in the distal gastrointestinal tract (GIT), while the Bt toxin fragments were detected at all sites in the GIT. Conclusions/Significance: Perturbations in peripheral immune response were thought not to be age-specific and were not indicative of Th 2 type allergenic or Th 1 type inflammatory responses. There was no evidence of cry1Ab gene or Bt toxin translocation to organs or blood following long-term feeding.The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 211820 and the Teagasc Walsh Fellowship programme

Current challenges facing the assessment of the allergenic capacity of food allergens in animal models

Food allergy is a major health problem of increasing concern. The insufficiency of protein sources for human nutrition in a world with a growing population is also a significant problem. The introduction of new protein sources into the diet, such as newly developed innovative foods or foods produced using new technologies and production processes, insects, algae, duckweed, or agricultural products from third countries, creates the opportunity for development of new food allergies, and this in turn has driven the need to develop test methods capable of characterizing the allergenic potential of novel food proteins. There is no doubt that robust and reliable animal models for the identification and characterization of food allergens would be valuable tools for safety assessment. However, although various animal models have been proposed for this purpose, to date, none have been formally validated as predictive and none are currently suitable to test the allergenic potential of new foods. Here, the design of various animal models are reviewed, including among others considerations of species and strain, diet, route of administration, dose and formulation of the test protein, relevant controls and endpoints measured

Core Outcome Set for IgE ‐mediated food allergy clinical trials and observational studies of interventions: International Delphi consensus study ‘ COMFA ’

Background: IgE‐mediated food allergy (FA) is a global health concern with substantial individual and societal implications. While diverse intervention strategies have been researched, inconsistencies in reported outcomes limit evaluations of FA treatments. To streamline evaluations and promote consistent reporting, the Core Outcome Measures for Food Allergy (COMFA) initiative aimed to establish a Core Outcome Set (COS) for FA clinical trials and observational studies of interventions. Methods: The project involved a review of published clinical trials, trial protocols and qualitative literature. Outcomes found as a result of review were categorized and classified, informing a two‐round online‐modified Delphi process followed by hybrid consensus meeting to finalize the COS. Results: The literature review, taxonomy mapping and iterative discussions with diverse COMFA group yielded an initial list of 39 outcomes. The iterative online and in‐person meetings reduced the list to 13 outcomes for voting in the formal Delphi process. One more outcome was added based on participant suggestions after the first Delphi round. A total of 778 participants from 52 countries participated, with 442 participating in both Delphi rounds. No outcome met a priori criteria for inclusion, and one was excluded as a result of the Delphi. Thirteen outcomes were brought to the hybrid consensus meeting as a result of Delphi and two outcomes, ‘allergic symptoms’ and ‘quality of life’ achieved consensus for inclusion as ‘core’ outcomes. Conclusion: In addition to the mandatory reporting of adverse events for FA clinical trials or observational studies of interventions, allergic symptoms and quality of life should be measured as core outcomes. Future work by COMFA will define how best to measure these core outcomes

Les dosages d’IgG anti-aliments : méthodes et pertinence clinique des résultats. Position du groupe de travail de biologie de la Société française d’allergologie

International audienceThere is an increasing tendency in western countries to attribute to food intolerance various clinical types of gastrointestinal disorders, joint pain or rheumatoid arthritis (RA), migraine and chronic fatigue. Several authors have reported a greater frequency of positive anti-food IgG in patients presenting irritable bowel syndrome (IBS), chronic inflammatory bowel disease (IBD) and RA compared to healthy controls. Over the last decade, screening tests have become routinely available on prescription but are also freely available over the Internet. These assays are used to create diets that avoid IgG-positive foods in the hope of improving symptoms thought to be related to the consumption of these foods associated with IgG-mediated intolerance reactions. The purpose of this study is to review the mechanisms involved in food intolerance and the physiological and pathological role of IgG immune response. Commercially available assays for food IgG are reviewed. Studies based on anti-food IgG determination applied to various diseases are reviewed and discussed. Considerable controversy surrounds the clinical relevance of anti-food IgG assays because of their poor positive predictive value. The recommendations made on the basis of these assays are likely to jeopardize the health of patients by delaying correct diagnosis or encouraging them to follow a mostly useless and occasionally harmful diet. The frequently high direct and indirect costs of assays and avoidance diets may be avoided in favor of other diagnostic strategies. Finally, in the current state of medical knowledge, anti-food IgG tests should not be performed routinely to establish a food intolerance diagnosis or to devise an avoidance diet. They should be used solely for research purposes. (C) 2018 Elsevier Masson SAS. All rights reserved.De plus en plus de personnes dans les pays développés attribuent à une intolérance alimentaire diverses manifestations cliniques de types troubles gastro-intestinaux, douleurs articulaires voire polyarthrite rhumatoïde (PR), migraine ou fatigue chronique. Plusieurs auteurs ont rapporté une fréquence plus importante de la positivité des IgG anti-aliments chez les patients souffrant de syndrome de l’intestin irritable (SII), de maladies inflammatoires chroniques de l’intestin (MICI) ou de PR comparés aux témoins sains. Depuis une décennie, ces dosages de recherche sont disponibles en routine sur prescription médicale mais aussi en accès libre sans avis médical via internet. Ces dosages sont utilisés pour établir des régimes d’éviction des aliments pour lesquels la recherche d’IgG est positive, dans l’espoir d’une amélioration des symptômes supposés être en relation avec la consommation de ces aliments par le biais d’une réaction d’intolérance faisant intervenir les IgG. L’objectif de ce travail est de rappeler les mécanismes impliqués dans les intolérances et allergies alimentaires, et le rôle physiologique des réponses immunitaires à IgG. Les techniques de dosage des IgG anti-aliments commercialement disponibles sont passées en revue. Les principales études basées sur le dosage des IgG anti-aliments appliqué à diverses pathologies font l’objet d’une analyse critique, suivie d’une discussion. Il en ressort que l’intérêt clinique des dosages d’IgG anti-aliments est l’objet d’une vive polémique en raison de leur mauvaise valeur prédictive positive. Les recommandations établies sur la base de ces dosages sont susceptibles de faire prendre un risque au patient en retardant quelquefois le bon diagnostic ou en lui faisant suivre un régime alimentaire d’éviction le plus souvent inutile et parfois délétère pour sa santé. Les coûts directs liés aux dosages et indirects occasionnés par les régimes d’éviction, souvent élevés, peuvent être évités au profit d’autres stratégies diagnostiques. En conclusion, dans l’état actuel des connaissances médicales, les dosages d’IgG anti-aliments ne devraient plus être pratiqués en routine pour établir un diagnostic d’intolérance ou allergie alimentaire à IgG, ni mettre en place un régime d’éviction. Leur utilisation devrait être réservée à des fins de recherche