ABSTRACT
Interactions between nerves and immune and inflammatory cells of the intestine are critically involved in the pathogenesis of bacterial and viral infection and control important gastrointestinal functions, including intestinal motility changes and transport, permeability to ions and larger molecules, diarrhoea and intestinal inflammation. During the past few years, a large number of neuropeptides, including serotonin, substance P, calcitonin-gene related peptide, and more recently neurotensin and galanin have been identified as important mediators in the development and progress of intestinal infectious conditions. These and other peptides, released in response to infectious agents, exert their effects by interacting, directly or indirectly, with their receptors on nerves, epithelial cells, and immune and inflammatory cells such as mast cells, and macrophages. Activation of these cells leads to the release of immune cell mediators to initiate or augment diarrhoea and intestinal inflammation. Immune cell mediators can also activate nerve endings to release neuropeptides. This chapter summarizes our recent understanding on the identification of peptide hormones and immune cells and mediators participating in the pathophysiology of bacterial and viral infection with focus on the small and large intestine, and reviews the possible mechanism(s) of action involved in these processes.
