Gut microbiota: immune system crosstalk: implications for metabolic disease

The gut microbiome has emerged as a key modulator of human health and disease and one intricately involved in host metabolism and immune function. It contributes an important genetic and metabolic contribution to the human “super-organism” in the shape of gene functions encoded by its metagenome which outnumbers human genes by a factor of 100. Cumulative evidence from diverse human studies and model systems is now showing that the gut microbiota occupies a critical functional fulcrum within this human “super-organism”, regulating both metabolic and inflammatory processes which not only appear to mediate chronic disease especially the metabolic syndrome, diabetes, cardiovascular disease but also autoimmune diseases and dementia and possibly the aging processes itself. Diet plays a critical role in shaping the gut microbiota and also in shaping its ability to regulate host metabolism and immune function through production of bioactive metabolites especially the shortchain fatty acids and regulation of bile acid metabolism. In this chapter we discuss the interplay between diet, the gut microbiota and the host immune system in regulating both metabolic and inflammatory processes with particular emphasis on how this interaction impinges on the development of the metabolic syndrome