Les pathologies associées au blé et céréales apparentées

National audienc

Les pathologies associées au blé et céréales apparentées

National audienc

Diagnostic de l’IgE-réactivité par analyse des composants moléculaires (test ISAC)

National audienceSpecific IgE-reactivities have first been implemented by the use of allergenic extracts then purified or recombinant major allergens. The frequent cross-reactivity (CR) due to vegetal and insect carbohydrate determinants has been suppressed by the use of bacteria originated recombinant allergens. CR linked to homology of amino acid sequences leads to classification of allergens, either species specific or cross-reactive ones. The micro array technology (ISAC) makes a component-resolved diagnosis possible by the analysis of 103 allergens. The assessment of this technique may be applied to different pathologies. Negative tests in eight cases of idiopathic anaphylaxis are reported. The ISAC microassay applied to atopic dermatitis shows different polysensitization profiles in 22 children compared to adults. The extensive association of aeroallergen and food allergen sensitizations is a hallmark of eosinophilic esophagitis. Another indication is to set a patient-taylored immunotherapy to pollens and mites. Present restrictions are the CR without clinical relevance (PR-10 family and tropomyosins), the poor performance of certain allergens (wheat allergens, Ana c 2, Ana o 3), the absence of allergens from the following allergenic sources: mustard, lupine, lentils, almond, walnut, buckwheat. In the near future, ISAC could be applied to epidemiological studies and to the follow-up of immunotherapies studied by specific IgG4s. Present prospects are to conduct thorough investigations about the efficiency of the currently available allergens, and to develop computerized algorithms taking into account clinical profiles and patterns of sensitization to improve the diagnosis of clinically relevant sensitization and to achieve the prediction of persistence and severity.La caractérisation de l’IgE-réactivité, essentielle au diagnostic a fait appel aux sources allergéniques puis aux allergènes majeurs purifiés. Les réactivités croisées (RC) très fréquentes liées aux déterminants carbohydrates des végétaux et des insectes ont été abolies par l’utilisation d’allergènes recombinants. Les RC liées à l’homologie des séquences d’acides aminés, larges ou limitées, offrent la notion d’allergènes spécifiques et d’allergènes croisants. Le concept de la puce ISAC basé sur 103 allergènes purifiés ou recombinants, permet un diagnostic de sensibilisation paranalyse des composants. Les indications actuelles sont explorées. L’utilité de ce test pour affirmer/infirmer le diagnostic de choc anaphylactique idiopathique est présenté à partir de huit cas. Les polysensibilisations sont confirmées dans les dermatites atopiques sévères de l’enfant, selon des profils différents de ceux de l’adulte. L’exploration des oesophagites à éosinophiles montre l’importance des sensibilisations aux aéro-allergènes et trophallergènes. Une aide au choix d’une immunothérapie est envisagée dans le cas de l’allergie à différents pollens et acariens. Les restrictions actuelles d’utilisation concernent les RC non cliniquement relevantes (famille PR-10 et tropomyosines), les allergènes inopérants ou insuffisants (Ana c 2, allergènes du blé, Ana o 3) et l’absence de sources allergéniques alimentaires (moutarde, lupin, lentilles, noix, amande, sarrasin). Les applications du test ISAC à la recherche sont des études épidémiologiques et le suivi des immunothérapies par l’apparition d’IgG4 spécifiques. Le test ISAC devrait prochainement se développer par l’adjonction de nouveaux allergènes. L’aide au diagnostic et à la prédiction de persistance et de sévérité de l’allergie rendra nécessaire le traitement des données grâce à des systèmes experts d’informations

Towards a new gliadin reference material-isolation and characterisation

International audienceTwenty-eight wheat cultivars representative of the three main European wheat producing countries, France, UK and Germany, were selected as a source for the preparation of a reference gliadin. One kilogram of kernels from each cultivar were mixed and milled. The resulting white flour was defatted and vacuum dried. Albumins and globulins were eliminated by extraction using 0.4 M NaC1 solution and gliadins were extracted with 60% ethanol. The gliadin extracts were concentrated, desalted by ultrafiltration, freeze-dried, and homogenised. After tests had shown good solubility and homogeneity, aliquots of the reference gliadin were sent to 16 different laboratories for further investigations: The material was analysed by various methods including RP-HPLC, SE-HPLC, RP-HPLC-ESI-MS, MALDI-TOF, capillary electrophoresis, acid-PAGE, 2D-PAGE, SDS-PAGE and immunoblotting and ELISA-tests with different monoclonal and polyclonal antibodies. The results showed that the gliadin composition of the source flour and the reference gliadin matched perfectly, demonstrating that no major gliadin components had been lost during the isolation procedure. The reference gliadin showed good immunochemical sensitivity with different gliadin antibodies in enzyme immunoassays. Because of its high protein and gliadin content, good solubility, homogeneity, stability and representative character, the product is regarded as a suitable universal reference material

Application of the adverse outcome pathway (AOP) concept to structure the available in vivo and in vitro mechanistic data for allergic sensitization to food proteins

Background: The introduction of whole new foods in a population may lead to sensitization and food allergy. This constitutes a potential public health problem and a challenge to risk assessors and managers as the existing under‑ standing of the pathophysiological processes and the currently available biological tools for prediction of the risk for food allergy development and the severity of the reaction are not sufficient. There is a substantial body of in vivo and in vitro data describing molecular and cellular events potentially involved in food sensitization. However, these events have not been organized in a sequence of related events that is plausible to result in sensitization, and useful to chal‑ lenge current hypotheses. The aim of this manuscript was to collect and structure the current mechanistic under‑ standing of sensitization induction to food proteins by applying the concept of adverse outcome pathway (AOP). Main body: The proposed AOP for food sensitization is based on information on molecular and cellular mechanisms and pathways evidenced to be involved in sensitization by food and food proteins and uses the AOPs for chemical skin sensitization and respiratory sensitization induction as templates. Available mechanistic data on protein respira‑ tory sensitization were included to fill out gaps in the understanding of how proteins may affect cells, cell–cell interac‑ tions and tissue homeostasis. Analysis revealed several key events (KE) and biomarkers that may have potential use in testing and assessment of proteins for their sensitizing potential. Conclusion: The application of the AOP concept to structure mechanistic in vivo and in vitro knowledge has made it possible to identify a number of methods, each addressing a specific KE, that provide information about the food allergenic potential of new proteins. When applied in the context of an integrated strategy these methods may reduce, if not replace, current animal testing approaches. The proposed AOP will be shared at the www.aopwiki.org platform to expand the mechanistic data, improve the confidence in each of the proposed KE and key event relations (KERs), and allow for the identification of new, or refinement of established KE and KERs