Oral therapeutic administration of a probiotic mixture suppresses established Th2 responses and systemic anaphylaxis in a murine model of food allergy

BACKGROUND: No effective treatment is available for food allergy and its primary management still consists of avoiding relevant allergens. Probiotics are claimed to beneficially affect the immune system. We sought to investigate the therapeutic potential of VSL#3 probiotic mixture on specific immune responses and anaphylactic reaction induced in mice by the major food allergen shrimp tropomyosin (ST). METHODS: The cytokine production by spleen cell from ST-sensitized mice upon allergen re-stimulation in the presence of VSL#3 was analysed. Next, the effects of oral administration of VSL#3 on allergen-induced anaphylaxis and Th2 response in the murine model of food allergy to ST was investigated by evaluating symptom score and histamine content in the faeces after allergen challenge, antibody response in serum and faeces, and cytokine and transcription factor expression in the jejunum. RESULTS: The in vitro studies on mouse spleen cells indicates that the VSL#3 preparation has the capacity to shift a polarized Th2 response to a Th1/T regulatory-type profile. Oral therapeutic administration of VSL#3 to ST-sensitized mice significantly reduces symptom score and histamine release in the faeces following allergen challenge, as well as specific IgE response. In the jejunum, IL-4, IL-5 and IL-13 tissue content was significantly reduced, whereas FOXP3 and IL-27 mRNA expression, IL-10, TGF-β and IFN-γ tissue content were up-regulated. CONCLUSIONS: Oral therapeutic treatment with the probiotic mixture VSL#3 is effective in redirecting allergen-specific Th2-polarized immune responses towards Th1-T regulatory responses and in the protection against anaphylactic reactions induced by the allergen in a murine model of food allergy.