Preventive and therapeutic effects of rapamycin, a mammalian target of rapamycin inhibitor, on food allergy in mice

Background Because few curative treatments are available for food allergy, we investigated the therapeutic potential of rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, on mouse food allergy. Methods The preventive and therapeutic effects of oral rapamycin on anaphylactic symptoms induced by oral ovalbumin (OVA) challenge in food allergy mice were investigated. Mast cell functions in response to rapamycin were also measured in the passive systemic anaphylaxis model and bone marrowderived mast cells (BMMCs). Results Daily rapamycin from the first challenge (preventive protocol) attenuated food allergy symptoms including diarrhea, anaphylactic reactions, and hypothermia in mice. The treatment decreased the challenge-induced increases in mouse mast cell protease-1 in serum and mast cell numbers in the intestine. Notably, the mice that already showed food allergy symptoms by previous challenges recovered from the disease with daily administration of rapamycin (therapeutic protocol). Anti-OVA IgG1 and IgE levels in serum, as well as IFN-?, IL-4, IL-13, IL-9, IL-10, and IL-17 secretion from splenocytes, were decreased by the treatments. In contrast, a single dose of rapamycin failed to affect passive systemic anaphylaxis. Spontaneous and IL-9-dependent survival and IgE-induced IL-13 secretion, but not degranulation, of BMMCs were reduced by rapamycin. Conclusion Our data show that mouse food allergy was attenuated by rapamycin through an immunosuppressive effect and inhibition of intestinal mast cell hyperplasia. Inhibition of the IL-9 productionmast cell survival axis is one of the mechanisms of the therapeutic effect of rapamycin. Rapamycin and other mTOR inhibitors might be good candidates for therapeutic drugs for food allergy.