Treg-inducing membrane vesicles from Bifidobacterium bifidum LMG13195 as potential adjuvants in immunotherapy

Abstract

Allergen-specific immunotherapy is the only treatment shown to induce antigen-specific regulatory T (Treg) cells and peripheral tolerance to restore human homeostasis. Specific probiotic strains are valid candidates to improve the allergen-specific tolerance, since they are able to generate Treg cells from naïve precursors. We recently reported that exposing dendritic cells (DCs) to Bifidobacterium bifidum LMG13195 in vitro induced the polarization of naïve T cells into functional Treg cells. In the present study, we evaluated the ability of DCs exposed to different B. bifidum subcellular fractions to promote Treg differentiation. We found that DCs exposed to B. bifidum LMG13195 membrane vesicles most strongly promoted differentiation of functional CD25(high)FOXP3(high)CD127(-/low) Treg cells as well as induced the highest IL-10 levels respect to the proinflammatory cytokines IFNγ, TNFα and IL-17. Our results suggest the potential use of B. bifidum LMG13195 membrane vesicles as a safe and clinically effective adjuvant for immunotherapy.