Hypersensitivity reactions to major allergenic foods such as wheat can be potentially deadly due to the high risk of systemic anaphylaxis. They are growing at an alarming rate for reasons not well understood and have become a major public concern at the global level. Wheats belong to four distinct genotypes (AA, AABB, AABBDD, and DD) that exist as thousands of lines and varieties. It is unknown whether there is naturally occurring variation in the intrinsic allergenic potential among genetically distinct wheats. Most published mouse models of wheat allergy are adjuvant-based, which fail to reveal the intrinsic allergenicity potential of wheat. A validated adjuvant-free mouse model to study the intrinsic allergenicity of salt-soluble protein extracts (SSPE) from wheat is unavailable. Therefore, a transdermal sensitization/oral elicitation (TS/OE) mouse model of food allergy established by Dr. Gangur, and colleagues was validated for wheat in this work.The central hypothesis guiding this research was that the salt-soluble protein extracts (SSPEs) obtained from four genetically distinct wheat species (Triticum monococcum, Triticum durum, Triticum aestivum, and Aegilops tauschii) will show significant natural variation in their intrinsic allergenicity in vivo. The central hypothesis was tested with two specific aims: Aim 1. Validate the TS/OE model for transdermal sensitization with salt-soluble protein extracts (SSPEs) from four wheats: Determine the natural variation in the intrinsic sensitization potencies from transdermal application of SSPEs from four wheats: T. monococcum (genome AA), T. durum (genomes AABB), T. aestivum (genomes AABBDD), and Ae. tauschii (genome DD). Aim 2. Validate the TS/OE model for oral allergic reaction to SSPEs from four wheats: Determine the natural variation in the oral allergic reaction elicitation potencies of SSPEs from the four wheats: T. monococcum (genome AA), T. durum (genomes AABB), T. aestivum (genomes AABBDD), and Ae. tauschii (genome DD).Results from this work show that: (i) repeated skin exposures to SSPEs from all four wheats elicited robust increases in the specific (s)IgE levels; (ii) skin exposures to SSPEs from all four wheats were sufficient to sensitize mice for oral anaphylaxis as measured by hypothermic shock response (HSR) and mucosal mast cell response (MMCR) to respective SSPEs from the four wheats; (iii) for durum wheat (T. durum) validation, both HSR and MMCR showed a strong correlation with each other, as well as with sIgE, and a modest correlation with total (t)IgE levels; (iv) in T. durum SSPE sensitized mice, selected Th2/Th17/Th1 cytokines were elevated; (v) in durum wheat allergy model, oral allergen-challenged mice showed selective elevation of IL-6 and a panel of chemokines compared to saline-challenged mice; (vi) among all four species tested, T. monococcum elicited the lowest sensitization, and the other three wheats were comparable in their sensitization potentials; (vii) among all four species tested, Ae. tauschii elicited the least HSR, followed by T. monococcum, T. durum, and T. aestivum; and (viii) among all four species tested, Ae. tauschii elicited the least MMCR, followed by T. durum and T. monococcum; however, all these three wheats were significantly less potent than the T. aestivum in eliciting MMCR. In summary, this study validates TS/OE mouse model for four genetically distinct wheat species, and reports establishment of a comparative map of intrinsic allergenic potential of four genetically distinct wheats using a novel adjuvant-free mouse model for the first time.The validated TS/OE mouse model of wheat allergenicity reported in this dissertation would be a cost-effective pre-clinical testing tool for evaluating the intrinsic allergenicity of wheat proteins. Furthermore, this model could also be used to examine the allergenic potencies of novel wheat lines/varieties and GM wheats when they are developed. In addition, this model can also be used to identify potentially hyper/hypo/non-allergenic wheat products. Lastly, a validated TS/OE model could facilitate advancing mechanisms of wheat allergenicity (e.g., role of genetics and environmental factors) leading to the development of novel preventive and therapeutic methods for life-threatening wheat allergies.
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