Modulation of the immune response by probiotic strains in a mouse model of gluten sensitivity

Probiotic strains play an important role in modulating activities in the gut-associated lymphoid tissue. Elucidation of the mechanisms that mediate probiotic-driven immunomodulation may facilitate their therapeutic application for specific immune-mediated diseases or for prophylaxis. In this study, we explored the effect of different Lactobacillus spp. and Bifidobacterium lactis in transgenic mice expressing the human DQ8 heterodimer, a HLA molecule linked to Celiac Disease (CD). In vitro analysis on immature bone marrow-derived dendritic cells (iBMDCs) showed that all strains up-regulated surface B7-2 (CD86), indicative of DC maturation, however, with different intensity. No strain induced appreciable levels of IL-10 or IL-12 in iBMDCs, whereas TNF-α expression was essentially elicited by Lactobacillus paracasei and Lactobacillus fermentum. Interestingly, these strains were found also to increase the antigen-specific TNF-α secretion in vivo, following co-administration of probiotic bacteria in mice mucosally immunized with the gluten component gliadin. Together these findings highlighted the ability of probiotics to exert strain-specific inductive rather than suppressive effects both on the innate and adaptive immunity in a mouse model of food antigen sensitivity.