Citation

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COMPREHENSIVE METABOLOMICS ANALYSIS OF PEANUT ALLERGY AND PEANUT-INDUCED ANAPHYLAXIS

Chalcraft, KR;

<p>The work in this thesis encompasses (a) the development of a robust analytical method suitable for the comprehensive analysis of polar and non-polar metabolites in a single analysis and (b) the application of this method to the study of the metabolites involved in peanut allergy. During the course of this work the methods for the analysis of large metabolite data sets evolved significantly and the approaches used in this work evolved in parallel to the literature. This work constitutes the first comprehensive metabolomic investigation of an allergy response.</p> <p>Hypersensitivity or allergy to peanuts is an increasingly problematic health concern around the world involving approximately 1-2% of children in North America. There are no useful clinical biomarkers for this allergy. Comprehensive metabolomics holds vast potential for the discovery of metabolites and metabolite pathways that may be involved during the development of peanut allergy and during peanut-induced anaphylaxis. The comprehensive study of metabolites involved in peanut allergy presented a significant challenge since no single analytical technique is capable of analysis of all metabolites within a single analytical run.</p> <p>The thesis begins with development of a tandem column liquid chromatography-electrospray ionization-mass spectrometry method which allowed the separation and analysis of both polar and non-polar metabolites in a single analysis. This tandem column technique was also shown to significantly reduce the amount of ion suppression observed compared to the ion suppression observed when using either column independently.</p> <p>This methodology was applied to the comprehensive metabolomics analysis of blood serum samples obtained from mice which were (a) being sensitized to peanuts and (b) undergoing anaphylaxis. This analysis discovered a profound impact on metabolites involved with purine metabolism, resulting in an elevation of uric acid levels. This discovery led to further investigations which confirmed that uric acid is essential for peanut sensitization in mice. This discovery was only possible due to the use of a comprehensive metabolomics approach.</p> <p>The analytical methodology was then applied to the study of metabolomic changes in sensitized mice as they experienced peanut-induced anaphylaxis. A number of metabolomic changes including taurine level elevation were correlated with peanut-induced anaphylaxis. Finally, a serendipitous opportunity arose to analyze blood serum samples from peanut allergic children that had undergone an oral peanut challenge. The comprehensive metabolomic study of these samples revealed massive changes in their serum metabolomes as a result of peanut exposure. A number of lipids and lysophospho-lipids were shown to have increased dramatically and may represent novel biomarker candidates for peanut-induced anaphylaxis in humans.</p> <p>In summary, this thesis had demonstrated that comprehensive metabolomic analyses can be successfully applied to complex syndromes such as peanut allergy and yield useful mechanistic and clinical insights to this disorder.</p>