Chapter

GI Microbiota and Regulation of the Immune System

Volume 635 of the series Advances in Experimental Medicine and Biology pp 1-14

Overview of Gut Immunology

  • Katie Lynn MasonAffiliated withDepartment of Microbiology and Immunology, University of Michigan Medical School
  • , Gary B. HuffnagleAffiliated withDepartment of Internal Medicine Division of Pulmonary and Critical Care Medicine, University of Michigan Medical School
  • , Mairi C. NoverrAffiliated withDepartment of Immunology and Microbiology, Wayne State University
  • , John Y. KaoAffiliated withDepartment of Internal Medicine Division of Pulmonary and Critical Care Medicine, University of Michigan Medical SchoolDivision of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The gastrointestinal tract (GI tract) plays dual roles in human physiology: digestion and uptake of nutrients and the more daunting task of maintaining immune homeostasis (protecting the body from potentially harmful microbes, while inducing tolerogenic responses to innocuous food, commensals and self-antigens). The unique architecture of the GI tract facilitates both of these functions; multiple levels of infolding results in an immense overall surface area that allows maximal nutrient absorption while housing the largest number of immune cells in the body. This review will focus on how mucosal immune responses generated in the GI tract are organized and controlled. The gastro-intestinal associated lymphoid tissue (GALT), which is composed of discrete inductive and effectors sites, is able to discriminate between harmful and harmless antigens while maintaining homeostasis. Inductive sites are organized into specialized aggregations of lymphoid follicles called Peyer’s patches (PP), while effector sites are more diffusely dispersed. The separation of these sites serves to limit and control immune responses. In addition to its distinct architecture, the GI tract has specialized immune cells that aid in promoting a tolerogenic response to orally introduced antigens, (e.g. subsets of dendritic cells (DCs) and regulatory T-cells (TR)). Secretory IgA (sIgA), which is produced in appreciable quantities at mucosal surfaces, also promotes an anti-inflammatory environment by neutralizing immune stimulatory antigens. The mechanisms of induction tolerance are currently poorly understood; however, this tolerant environment limits potentially damaging inflammatory responses to inappropriate stimuli.