Influence of Resident Intestinal Microflora on the Development and Functions of the Gut-Associated Lymphoid Tissue
- Publisher: Microbial Ecology in Health and Disease
Microbial Ecology in Health and Disease
(issn: 1651-2235, eissn: 1651-2235)
Gut-associated lymphoid tissue (GALT) is under constant exposure to environmental antigens. The digestive flora is the main antigenic stimulus. A huge population of live bacterial cells, estimated at 1014 in number, colonizes the human gastrointestinal tract (1). Bacterial numbers and composition vary considerably along the gastrointestinal tract, constituting complex ecosystems which depend on the physiology of the host and on interactions between bacteria. It has recently been shown that GALT has the ability to develop tolerance towards resident bacterial flora (2). Conversely, the digestive flora considerably influences the development and functioning of GALT. To understand the relationships between the digestive flora and GALT, it is important to consider the evolution of bacterial equilibrium during the main biological stages of life, from a digestive point of view, i.e. infancy (up to 2 years of age), adulthood and old age, as well as the bacterial colonization of the different parts of the intestine. In this chapter, we will begin by dealing with the role of the resident digestive flora on the development and functions of GALT. Then, we will focus on the neo-natal period which could be of particular importance for protection against some pathologies such as allergy and hypersensitivities.