Understanding immunomodulatory effects of probiotics

The intestinal microbiota is known to be a driving force in the development and maintenance of the immune system. While substantial shifts in the microbiota composition may influence immune functionality in a longer term, short occasional changes might also be sensed. The latter opens considerable perspectives for the use of nutritional interventions, intended to modulate immune functionality in a desired direction. Probiotics are discussed here as a possible way to achieve this goal. It seems that effects are not only strain specific, but will depend on many environmental factors that make the immune system receptive or not to the influences of a given probiotic strain. The interactions between probiotics on the one hand and enterocytes or immune cells on the other hand, are a complex interplay that is rarely mediated by a single mechanism. Immunomodulation through nutrition is therefore a complex phenomenon that needs careful consideration, understanding of immune functionality as well as insight into the mechanisms of probiotic activities. Only then can the proper clinical trials with proper readouts be set up to prove efficacy of each strain/mixture individually.