Bacterial Colonization in the Developing Gastrointestinal Tract: Role in the Pathogenesis of Intestinal Diseases

Bacterial colonization plays an important role in the normal development, differentiation, function and regulation of intestinal mucosal immune system. Through mechanisms that are still not fully understood, the intestinal mucosal immune system generates effective protective immunity against pathogen invasion and at the same time it develops immune tolerance, preventing the development of disease conditions, such as IBD and food allergy. The regulatory role of the intestinal flora in the development and function of the intestinal mucosal immune system is well established. Recent work has suggested that colonization with probiotics in the gut may play an essential role in balancing the intestinal mucosal immune system, which may contribute to the induction and maintenance of immunological tolerance to other luminal antigens in the normal host or to the inhibition of the dysregulated responses induced by luminal antigens in diseased hosts. A better understanding of the cellular and molecular mechanisms controlling the development and regulation of intestinal mucosal epithelial system by intestinal bacteria (commensal and probiotics) and their regulatory role in various diseases will help establish new strategies to prevent and control these disease conditions.