Microbiota, probiotics and natural immunity of the gut

Abstract

The mammalian intestine is host to a rich microbiota whose composition is determined by the host's diet and by the various physiological and immunological forces at play in the local microenvironment. In turn, the complex bacterial communities which form the microbiota bestow important nutritional, metabolic and protective functions. The precise mechanisms underlying this intimate relationship are slowly being uncovered and the knowledge gained is being used in the selection of probiotic microorganisms. In the healthy host, tightly regulated immune mechanisms ensure that the microbiota does not pose a threat to the integrity of the intestinal barrier or to gut homeostasis. Although the following treatise discusses how innate and adaptive immunity cooperate to achieve this homeostasis, it focuses primarily on the role of innate immune responses. © 2011 Springer Science+Business Media B.V.