Immunology: Edited by W. Allan WalkerRole of microbiota in postnatal maturation of intestinal T-cell responsesGaboriau-Routhiau, Valérie; Lécuyer, Emelyne; Cerf-Bensussan, NadineAuthor Information INSERM U989, Université Paris Descartes, Paris and INRA, UMR1319 Micalis, Jouy-en-Josas, France Correspondence to Nadine Cerf-Bensussan, MD, PhD, INSERM U989, Université Paris Descartes, 156 rue de Vaugirard, 75730 Paris Cedex 15, FranceTel: +33 1 4061 5637; fax: +33 1 4061 5637; e-mail: email@example.com Current Opinion in Gastroenterology: October 2011 - Volume 27 - Issue 6 - p 502-508 doi: 10.1097/MOG.0b013e32834bb82b Buy Metrics Abstract Purpose of review Taking advantage of their rapid growth and capacity for continuous genetic adaptation, prokaryotes have colonized all possible ecological environments on earth, including the body surfaces of eukaryotes and their gastrointestinal tract. The mammalian gut contains a complex community of 1014 bacteria with a meta-genome containing 1500-fold more genes than the human genome. The forces that control the relationships between eukaryotic hosts and their intestinal bacterial symbionts have, thus, become a major focus of interest. Recent findings Recent data have highlighted how the dialogue between mammalian hosts and their microbiota stimulates the postnatal maturation of an efficient intestinal barrier that promotes niche colonization by symbiotic bacteria and opposes colonization by pathogens. Herein, we review microbiota-induced T-cell responses and discuss how individual bacteria may shape the balance between regulatory and inflammatory responses. We will also show how host factors might influence the outcome of gut immune responses and affect the structure of the microbiota. Summary Deciphering host–microbiota reciprocal influence may not only help in understanding the recent outburst of intestinal inflammatory diseases but also point to strategies able to maintain or restore intestinal homeostasis. © 2011 Lippincott Williams & Wilkins, Inc.