Airway exposure initiates peanut allergy by involving the IL-1 pathway and T follicular helper cells in mice

Publication date: Available online 14 December 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Joseph J. Dolence, Takao Kobayashi, Koji Iijima, James Krempski, Li Y. Drake, Alexander L. Dent, Hirohito Kita
BackgroundLittle is currently known regarding the immunological mechanism(s) that initiate peanut allergy. Notably, peanut proteins have been detected in house dust, and their levels correlate with peanut allergy prevalence.ObjectiveThis study aimed to develop a new mouse model for peanut allergy and to investigate the immunological mechanisms involved in peanut allergen sensitization.MethodsTo mimic environmental exposure, naïve mice were exposed to peanut flour by inhalation for up to 4 weeks. We then analyzed serum levels of IgE antibody and challenged mice with peanut proteins. Immunological mechanisms involved in sensitization were analyzed using cytokine reporter mice, an adoptive cell transfer model, and gene knockout mice.ResultsWhen exposed to peanut flour by inhalation, both BALB/c and C57BL/6 mice developed peanut allergy, as demonstrated by the presence of peanut-specific IgE antibodies and manifestation of acute anaphylaxis upon challenge. A large number of follicular helper T (Tfh) cells were also detected in draining lymph nodes of allergic mice. These cells produced IL-4 and IL-21, and more robustly promoted peanut-specific IgE production than Th2 cells. Genetic depletion of Tfh cells decreased IgE antibody levels and protected mice from anaphylaxis, without affecting Th2 cells. Furthermore, peanut flour exposure increased lung levels of IL-1α and IL-1β, and mice deficient in the receptor for these cytokines showed a significant decrease in Tfh cells compared to wild-type mice.ConclusionTfh cells play a key role in peanut allergy, and the IL-1 pathway is involved in the Tfh response to peanut allergen exposure.

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