Probiotics and the immune response.

Beneficial effects exerted by probiotic bacteria in the treatment of human disease may be broadly classified as those effects which arise due to activity in the large intestine and are related to colonization or inhibition of pathogen growth; and those effects which arise in both the small and large intestine, and are related to enhancement of the host immune response and intestinal barrier function. In a strain dependent fashion, probiotic bacteria can enhance intestinal barrier function and modulate signal transduction pathways and gene expression in epithelial and immune cells. Oral administration of live probiotics and bacterial structural components can also differentially modulate dendritic cells resulting in an increased production of IL-10 and regulatory T cells. Both innate and adaptive immune responses can be modulated by probiotic bacteria.