Microbial activities and intestinal homeostasis: A delicate balance between health and disease.

The concept that the intestinal microbiota modulates numerous physiological processes including immune development and function, nutrition and metabolism as well as pathogen exclusion is relatively well established in the scientific community. The molecular mechanisms driving these various effects and the events leading to the establishment of a "healthy" microbiome are slowly emerging. The objective of this review is to bring into focus important aspects of microbial/host interactions in the intestine and to discuss key molecular mechanisms controlling health and disease states. We will discuss recent evidence on how microbes interact with the host and one another and their impact on intestinal homeostasis.