CASALL · Why casein is a major food allergen?
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2006-12-01 → 2007-11-30
- EU contribution
- €115,230
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - CasAll (Why casein is a major food allergen ?)
This project had two main objectives, namely the development of an infant in vitro digestion model along with the application of dairy samples of various complexities to the infant gut and the identification of the sequences that were resistant to in vitro digestion. In this first part, we developed a new infant gut model that was applied to the digestion of three model proteins. Hydrolysis of b-CN and Ova was reduced in this infant model compared to the adult one. Surprisingly, b-lg was more hydrolysed in the infant model than in the adult one because of decreased protection of the molecule by the lower concentration of phosphatidylcholine which was used in this model. 15 different proteins or dairy products obtained from the same original raw milk were submitted to the infant gut model. Digested samples were analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), reversed phase high performance liquid chromatography (RP-HPLC) and enzyme-linked immunosorbent assay (ELISA) and four samples, namely raw, pasteurised, sterilised whole milks and full-fat yoghurt, were further investigated to determine the areas that were resistant to digestion. The regions b-CN(f76-93), k-CN(f98-169) and as2-CN(f36-75) were found resistant to in vitro digestion as well as as1-CN(f149-199) to a lesser extent. LC-MS-MS of the digested raw, pasteurised and sterilised milk and yoghurt showed that some area of the proteins generated peptides was found in all analysed samples whereas other area generated peptides were only found in the heavily processed materials. When the protected peptides were matched to the hydrophobicity profiles of as1-, as2-, b- and k-casein at pH 3.0, i.e. the ones used for the gastric phase of in vitro digestion, it was shown that all areas that were resistant to digestion were those that were highly hydrophobic at pH 3.0. As a general conclusion, a physiologically-relevant infant in vitro digestion model was developed and applied to a variety of dairy samples. It showed that some regions of the casein molecule were resistant to digestion and could therefore elicit an allergic response. This resistance could be explained by the low pH in the stomach that made these areas highly hydrophobic and hardly cleavable by the proteases.
Data: CORDIS, © European Union
Project objective
Food allergy is a major health concern in Europe since 6 to 8% of children are suffering from it. Furthermore, the prevalence of this pathology has significantly increased during recent years. Among the foods responsible for allergy, milk is one of the most important especially in infants and young children. The proteins involved in milk allergy are the whey proteins and the caseins. During the recent years, sensitivity to casein has increased in terms of both frequency and intensity of IgE response, which is quite surprising since caseins are known to be rapidly and extensively degraded by proteolytic enzyme during digestion, limiting their allergenicity. The objective of the present project is therefore to understand why casein is a major food allergen.Several hypotheses may explain this phenomenon and will be investigated during this project:(1) role of casein phosphorylated sequences resistant to digestion,(2) protection of caseins from digestion by lipids,(3) impact of technological processes on case in digestibility.This 3-year project will be realized thanks to a close cooperation between the Institute of Food Research (IFR) in Norwich UK (Drs Mackie and Mills) and the National Institute for Agricultural Research (INRA) in Poligny France (Dr Dupont). Most of the technical work will be done by Dr. Dupont during a one year stay at IFR where the applicant will deepen his knowledge and expertise in the food allergy area and will acquire technical skills, in particular proteomic techniques, he will need for his future scientific projects. He will use an in vitro digestion gut model previously developed at IFR that he will be able to transfer to INRA after his stay at IFR.Finally, he will learn about EU project management, as well as networking with other centres involved in the projects IFR leads. On the other side, Dr Dupont will transfer to IFR some immunochemical techniques (ELISA, protein arrays) he has developed to follow the antigenicity of caseins.
Original text from CORDIS.
Participants
- INSTITUTE OF FOOD RESEARCH · NORWICHCoordinatorCity levelUnited Kingdom
Links
Data: CORDIS, © European Union