The immunomodulatory activity of the intestinal microbiota

The intestinal microbiota plays a key role in promoting maturation of the immune system, particularly during the neonatal period, and is influenced throughout life by environmental factors. In particular, diet plays a central role in the structure and constitution of the gut microbiota. Moreover, it has been suggested that a healthy microbiota exists when there is a balance between symbionts, commensal organisms, and pathobionts. Alterations in this balance can lead to dysbiosis, which has been implicated in numerous pathologies. Epidemiologic evidence also suggests that modulation of immune response mechanisms in the gut can positively affect the development of allergic disease mechanisms in the lung and also other systemic sites of allergic disease, such as the skin. This activity is primarily conducted by Lactobacilli and Bifidobacteria that constitute a major part of the normal intestinal microbiota in animals and humans. Also, the composition of a healthy microbiota, which is required to confer maximum immune protection is not known. This issue represents a main objective of the Immunobiology Unit activity at ISA that is addressed by establishing whether the different microbe arrangements arising from specific diets actually translate to the modulation of the immune function. Data relative to possible effects of selected intestinal bacteria and probiotics on the maturation and functionality of immune cells, as well as on inducible immune mediators are normally collected to establish the modulation degree and the phenotype of the immune response.