Immunomodulatory effects of potential probiotics in a mouse peanut sensitization model

Peanut allergy accounts for the majority of severe food-related allergic reactions and there is a need for new prevention and treatment strategies. Probiotics may be considered for treatment on the basis of their immunomodulating properties. Cytokine profiles of probiotic strains were determined by in vitro co-culture with human PBMCs. Three strains were selected to investigate their prophylactic potential in a peanut sensitization model by analysing peanut-specific antibodies, mast cell degranulation and ex vivo cytokine production by splenocytes. The probiotic strains induced highly variable cytokine profiles in PBMCs. L. salivarius HMI001, L. casei Shirota (LCS) and L. plantarum WCFS1 were selected for further investigation owing to their distinct cytokine patterns. Prophylactic treatment with both HMI001 and LCS attenuated the Th2 phenotype (reduced mast cell responses and ex vivo IL-4 and/or IL-5 production). In contrast, WCFS1 augmented the Th2 phenotype (increased mast cell and antibody responses and ex vivo IL-4 production). In vitro PBMC screening was useful in selecting strains with anti-inflammatory and Th1 skewing properties. In case of HMI001 (high IL-10/IL-12 ratio) and LCS (high interferon-γ and IL-12), partial protection was seen in a mouse peanut allergy model. Strikingly, certain strains may worsen the allergic reaction as shown in the case of WCFS1.