[Frontiers in Bioscience S4, 685-698, January 1, 2012]

Innate and adaptive immunity in host-microbiota mutualism

Andrew J. Macpherson1, Markus B. Geuking1, Kathy D. McCoy1

1Maurice Muller Laboratories, University Clinic for Visceral Surgery and Medicine, Murtenstrasse 35, University of Bern, CH-3010, Bern, Switzerland

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Adaptation of the host to the colonisation of the intestine with a commensal microbiota
4. Uncoupled mucosal and systemic immune responses to commensal intestinal microbes
5. The mucosal immune firewall
6. The role of innate immunity in mutualism with intestinal microbes
7. Conclusions
8. Acknowledgement
7. References

1. ABSTRACT

Healthy individuals live in peaceful co-existence with an immense load of intestinal bacteria. This symbiosis is advantageous for both the host and the bacteria. For the host it provides access to otherwise undigestible nutrients and colonization resistance against pathogens. In return the bacteria receive an excellent nutrient habitat. The mucosal immune adaptations to the presence of this commensal intestinal microflora are manifold. Although bacterial colonization has clear systemic consequences, such as maturation of the immune system, it is striking that the mutualistic adaptive (T and B cells) and innate immune responses are precisely compartmentalized to the mucosal immune system. Here we summarize the mechanisms of mucosal immune compartmentalization and its importance for a healthy host-microbiota mutualism.