Heating affects structure, enterocyte adsorption and signalling, as well as immunogenicity of the peanut allergen Ara h 2

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.