Effect of Intestinal Microbiota on the Immune System Preclinical Studies

Effect of Intestinal Microbiota on the Immune System Preclinical Studies 

There is accumulating evidence that the interaction between the intestinal microbiota and the gut plays an important role for the postnatal development of the immune system. However, the interactions between the intestinal epithehal and immune cells and the different species of the intestinal microbiota are very complex and not fully understood. The complexity of these interactions is based on the fact that on the one hand the human defense system consists of several layers, for example, of mechanical and chemical barriers (first line of defence) as well as innate and adaptive immunity (67) all of which can be influenced by microbiota (68). 

Following the PASSCLAIM recommendation (69), studies in mice were recommended to substantiate conclusions related to immunological effects of dietary compounds. As for the prebiotic function, the most systematic studies were performed with a mixture of GOS/lcFOS. The experimental data have been intensively reviewed recently by Vos et al. (70). 

In mice, it could be shown that GOS/lcFOS was bifidogenic in a dose-dependent manner, resulting in a reduction of the fecal pH and in a fecal SCFA pattern as found in human infants, thus, supporting the relevance of the animal data for the human situation (71). 

In a mouse vaccination model adapted to study the effect of prebiotics, the animals were vaccinated twice with the Influvac Orthomyxovirus influenza) vaccine (booster vaccination after 21 days). The response to the vaccination was measured at day 30 after the first vaccination. Parameters used to identify the response to vaccination were DTH response (skin response after local subcutaneous vaccine injection as an in vivo measure for Thl-mediated immunity), plasma titers of specific antibodies, ex vivo lymphocyte stimulation, T-cell prohferation, cytokine production, and natural killer cell activity. A specific prebiotic mixture (GOS/lcFOS) significantly stimulated the vaccination response in a dose-dependent manner and increased the DTH response indicating a modulation of the immune system toward a Thl-dominated immune response. This effect only 

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