The “inner tube of life”: how does the gastrointestinal tract age?

The gastrointestinal (GI) tract is the primary and largest area of contact with environmental factors and antigens and it contains the largest number of immune cells in the body. The intestinal barrier is integral to GI-defence in preventing or limiting exposure of the host and its immune system to luminal antigens. One of the main consequences of this is that such a vast mucosal surface of the intestine requires constant and effective patrolling by a large number of lymphocytes forming the intestinal immune system. Recent advance in the field suggested that alterations of the intestinal epithelial barrier, including its associated immune system are linked to both local and systemic disorders of various natures. However, like any other system in the body, the various components of the intestinal epithelial barrier, including the immune system deteriorate with the advancing of age; therefore, the identification of the events underlying the ageing process in the gut might have important consequences on health and wellbeing far beyond the GI-tract. In spite of its critical role in maintaining health up to date very little attention has been given to how ageing affects this critical structure; as a result our knowledge on the effects of ageing on the physical and immunological properties of the intestinal epithelial barrier is still poor. This chapter describes the impact of ageing on the highly integrated components of the intestinal epithelial barrier; also, the possibility to devise novel strategies to achieve a healthier aging by targeting the GI-tract is discussed.