Short communication: Probiotic induction of interleukin-10 and interleukin-12 production by macrophages is modulated by co-stimulation with microbial components.

Probiotic lactobacilli stimulate macrophages and dendritic cells to secrete cytokines and thereby regulate the immune responses of the host. The balance of the IL-10 and IL-12 production induced by a probiotic is crucial for determining the direction of the immune response. In the present study, we examined the ability of microbial components to modify IL-10 and IL-12 production induced by a popular probiotic strain, Lactobacillus casei strain Shirota (LcS), which itself predominantly induces IL-12 production. Microbial ligands for toll-like receptor (TLR)3 and TLR5 further enhanced the IL-12 induction by LcS, whereas ligands for TLR2, TLR4, TLR7, and TLR9 converted the cytokine production pattern from IL-12 predominant to IL-10 predominant. These results indicate that the probiotic induction of IL-10 and IL-12 production can be flexibly modified by co-stimulation with microbial components. This could explain the variety of immunomodulatory functions (immunoactivation or anti-inflammation) exerted by this probiotic strain.