Intragastric administration of Lactobacillus casei BL23 induces regulatory FoxP3+RORγt+ T cells subset in mice.

Abstract

Many studies have highlighted the immunomodulatory properties of the probiotic strain Lactobacillus casei BL23. Recently, we demonstrated the ability of this strain to modulate the Th2-oriented immune response in a mouse model of cow's milk allergy based on the induction of a Th17-biased immune response. The probiotic function of L. casei has been also linked to gut-microbiota modifications which could been potentially involved in the immune regulation; however, its precise mechanism of action remains poorly understood. In this regard, recent studies suggest that gut microbiota induces a specific subset of CD4+FoxP3+ Treg cells that also express RORγt+, the specific transcription factor of Th17 cells. This new type of regulatory T cells, called type 3 Treg, displays suppressive function during intestinal inflammation, participating in inflammation control. We thus explored the ability of L. casei BL23 to specifically induce type 3 Treg cells, both in vitro and in vivo. Our results showed that intragastric administration of L. casei BL23 to mice induces local and systemic FoxP3+ RORγt+ type 3 Treg cells that could then participate in the beneficial effects of L. casei BL23 in different intestinal-related disorders.