Heating Affects Structure, Enterocyte Adsorption and Signalling, As Well as Immunogenicity of the Peanut Allergen Ara h 2

Philipp Starkl,Eva Untersmayr,Dominik Oberthuer,Ines Swoboda,Christian Betzel,Hugh A Sampson,Erika Jensen-Jarolim,Ferdinand Felix,Durga Krishnamurthy,Anna Lukschal,Krisztina Szalai

doi:10.2174/1874838401104010024

Abstract

Previous studies have indicated that specific molecular properties of proteins may determine their allergenicity. Allergen interaction with epithelia as the first contact site could be decisive for a resulting immune response. We investigate here for the major peanut allergen Ara h 2 whether thermal processing results in structural changes which may impact the protein's molecular interactions with enterocytes, subsequent cellular signalling response, and immunogenicity.Ara h 2 was heat processed and analyzed in terms of patient IgE binding, structural alterations, interaction with human enterocytes and associated signalling as well as immunogenicity in a food allergy mouse model.Heating of Ara h 2 led to significantly enhanced binding to Caco-2/TC7 human intestinal epithelial cells. Structural analyses indicated that heating caused persistent structural changes and led to the formation of Ara h 2 oligomers in solution. Heated protein exhibited a significantly higher immunogenic potential in vivo as determined by IgG and IgE serum antibody levels as well as IL-2 and IL-6 release by splenocytes. In human Caco-2/TC7 cells, Ara h 2 incubation led to a response in immune- and stress signalling related pathway components at the RNA level, whereas heated allergen induced a stress-response only.We suggest from this peanut allergen example that food processing may change the molecular immunogenicity and modulate the interaction capacity of food allergens with the intestinal epithelium. Increased binding behaviour to enterocytes and initiation of signalling pathways could trigger the epimmunome and influence the sensitization capacity of food proteins.

Highlights

Food allergy is a rapidly spreading worldwide disease
In human Caco-2/TC7 cells, Ara h 2 incubation led to a response in immune- and stress signalling related pathway components at the RNA level, whereas heated allergen induced a stress-response only. We suggest from this peanut allergen example that food processing may change the molecular immunogenicity and modulate the interaction capacity of food allergens with the intestinal epithelium
IgE binding to Ara h 1 and Ara h 2 may increase upon heat associated food processing [2, 4, 12, 24]

Summary

INTRODUCTION

Food allergy is a rapidly spreading worldwide disease. Allergy against peanut (Arachis hypogaea) is one of the most dangerous and frequent type 1 food allergies [1, 2]. Based on the concept of the epimmunome [11], we used Ara h 2 as model allergen and studied its interactions with human intestinal epithelial cells, the subsequent cellular responses as well as its immunogenicity in vivo in a food allergy mouse model. We report here that besides its molecular properties, heating as one of the most important food processing methods influences the IgE triggering potential of peanut allergens [12] and affects the consecutive immune response. Purified proteins were thermally processed in vitro following a protocol previously used to assess the effect of heat treatment and the Maillard reaction on IgE binding from human peanut allergic patients to Ara h 2 [2]. 50g recombinant allergen or control protein was added onto the cells in triplicates and incubated on ice for 90min.

RESULTS

DISCUSSION

CONCLUSION

CONFLICT OF INTEREST