Inflammatory Diseases of the Gastrointestinal Tract and Pharmacological Treatments

The human gastrointestinal (GI) tract is critical for the digestion and absorption of food and the elimination of waste products. The absorption of dietary nutrients is facilitated through a physical epithelial barrier consisting of numerous finger-like projections called villi that promote the uptake of nutrients throughout the body. This same epithelial barrier also prevents bacterial invasion, a remarkable accomplishment, considering that trillions of bacteria normally live within the lumen of the gut, reaching densities of up to 1012 organisms per gram in the colon. These normal intestinal flora or microbiota, the composition of which varies from individual to individual, play a pivotal role in the shaping and direction of mucosal immune responses within the GI tract. Mucosal immune responses within the GI tract are tailored toward limiting opportunistic infections caused by commensal bacteria, while protecting the body’s inner surfaces from colonization by pathogens. Perturbations of normal immune homeostasis within the GI tract, either due to infection or injury, defects in barrier function, induction of autoimmune mechanisms, and disruption of commensal bacterial composition, may lead to chronic inflammatory processes, leading to the development of diseases such as inflammatory bowel disease, celiac disease, food allergy and other conditions. In this chapter, we will examine the inflammatory processes and immunotherapeutic drug targets involved in the development of the above diseases.