It has been widely accepted in allergen research that general characteristics including protein stability and abundance from source are common determining factors of allergens. However, rigorous statistical comparisons of allergens versus non-allergens on genomic and proteomic scales are lacking. In our study performed this year, the house dust mite Dermatophagoides pteronyssinus (DP) proteome was evaluated using RNA-seq methods as a proxy to assess the abundance of all proteins in this source. In addition, the thermodynamic stabilities of 700 non-allergens and 20 allergens were evaluated using a combined chemical denaturation and mass spectrometry approach. The results showed that when expression and stability are considered in combination, the allergens are a statistically different population from other DP proteins. The allergens are more stable and more highly expressed. Further research is needed to evaluate if this trend is true of other allergen sources. We are planning to interrogate cockroach and pollen extracts in a similar set of experiments. Understanding the biophysical properties of allergens is a major goal of this research. These molecular characterizations may be useful in evaluations of new GMOs to assess the potential for introduction of new allergenic proteins. Our studies on pollen extracts were motivated by previous work on ragweed and birch pollen that suggested the adenosine content was an important factor in allergic sensitization. This study compared the metabolite profile of 22 pollen species important for allergic disease, measured the adenosine content, and evaluated exposure to pollen-derived adenosine. A principal component analysis of the various metabolites identified by NMR showed that pollen extracts could be differentiated primarily by sugar content (glucose, fructose, and sucrose), and to a lesser extent glycerol, and myo-inositol. Adenosine was highest for grasses followed by trees and weeds. Pollen count data showed that tree pollen was typically 5-10 times the level of other pollens. At the daily peaks of tree, grass, and weed season the pollen-derived adenosine exposure per day is likely to only be 0.6, 0.04, and 0.07 g, respectively. We concluded that sugar content and other metabolites may be useful in classifying pollens. Unless other factors create exposures that are very different from the models we developed, pollen-derived adenosine is unlikely to be a major factor in allergic sensitization.
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