Grantee Research Project Results
Final Report: Improved Animal Model for Assessment of Allergenic Potential of Foods Through Selective Deletion of T Cells and Global Gene Expression Analysis
EPA Grant Number: R833134Title: Improved Animal Model for Assessment of Allergenic Potential of Foods Through Selective Deletion of T Cells and Global Gene Expression Analysis
Investigators: HogenEsch, Harm , Muir, William
Institution: Purdue University
EPA Project Officer: Aja, Hayley
Project Period: November 1, 2006 through October 31, 2009 (Extended to November 30, 2010)
Project Amount: $398,497
RFA: Biotechnology: Potential Allergenicity of Genetically Engineered Foods (2006) RFA Text | Recipients Lists
Research Category: Human Health
Objective:
The overall goal of this research was to develop a new animal model to test for allergenic potential of foods that requires a short duration of testing; has increased sensitivity and discriminatory power over existing models; and is relatively easy to use. The research project had three specific objectives.
Objective 1 was to determine if mice that lack a subpopulation of T lymphocytes known as TCRγδ+ T cells, are more sensitive to food allergens than mice with an intact TCRγδ+ T cell population. The rationale for this objective was that the increased susceptibility would allow the induction of food allergy without the use of (mucosal) adjuvants and enhance the ability to discriminate between allergic and non-allergic foods. Mice with a genetically determined deficiency in TCRγδ+ T cells and mice treated with anti-TCRγδ+ antibodies were used and compared with wild-type mice.
Objective 2 was to determine if oral administration of food proteins to mice can discriminate between allergenic and non-allergenic proteins. To address this objective, three genetically different strains of mice were compared for the ability to generate IgE antibodies following oral administration of known food allergens (peanut protein and ovalbumin), but not following feeding of non-allergenic proteins (spinach and potato protein).
Objective 3 was to identify early biomarkers of food allergenicity in mice that shorten the exposure protocol and increase the sensitivity of the mouse model. This work was done by analysis of global gene expression in the spleen and duodenum using microarrays following oral administration of known food allergens in comparison with the appropriate controls.
Summary/Accomplishments (Outputs/Outcomes):
TCRγδ+ T cell-deficient mice were not more sensitive to orally administered allergenic proteins than wild-type mice. In the absence of an adjuvant, the oral administration of proteins did not induce an IgE antibody response.
Comparison of three inbred mouse strains indicated that A/J mice produce a stronger IgE response upon oral administration of allergenic proteins in combination with cholera toxin as a mucosal adjuvant than BALB/c and C3H/HeJ mice. The IgE response in A/J mice discriminated between known allergens such as peanut protein extract and ovalbumin and known non-allergenic proteins such as spinach and potato protein extract.
Analysis of global gene expression using microarrays in duodenum and spleen following oral administration of peanut protein extract with cholera toxin as adjuvant for 1 week or 3 weeks revealed that the pattern of gene expression segregated by experimental group. However, changes in the expression of specific genes identified in the microarray analysis could not be confirmed by RT-PCR in independent experiments.
Conclusions:
The objectives of these experiments were to establish an improved mouse model of food allergy and to identify early expressed biomarkers of food allergy. The depletion of TCRγδ-T cells through antibody treatment or through genetic manipulation did not enhance the sensitivity of mice to food allergens in the absence of cholera toxin as a mucosal adjuvant. The feeding of cholera toxin together with food proteins was necessary to induce an IgE antibody response to food allergens. A comparison of three different inbred mouse strains identified the A/J strain as a relatively high responder to food allergens in comparison with two other commonly used strains, BALB/c and C3H/HeJ. Analysis of global gene expression following short term (twice in 1 week) and longer term (six times over 3 weeks) inoculation of mice by oral gavage identified a pattern of gene expression that segregated with the different treatment groups. However, we were unable to confirm the changes in gene expression for specific genes in independent experiments.
Journal Articles:
No journal articles submitted with this report: View all 2 publications for this projectSupplemental Keywords:
food allergens, adjuvant, mouse model, strain differences, biomarkersProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.