Role of intestinal epithelial cells in the innate immune defence of the pig intestine.

The intestinal epithelium serves as a dynamic barrier, which in the course of its normal function, maintains regulated uptake of nutrients and water while excluding potential pathogens. Over the past decade many studies have also revealed the immunological importance of intestinal epithelial cells (IEC). IEC have developed a variety of mechanisms to reduce the risk of infection by invasive pathogens or damage by toxic compounds. The effective maintenance of a physical barrier function is dependent on the establishment of well-organised intercellular junctions and a constant state of regeneration/renewal of the epithelium. IEC also participate in the innate immune responsiveness of the intestine by their ability to secrete mucus and antimicrobial peptides. IEC are also able to secrete cytokines and to respond to exogenous chemokines. This review summarises the current knowledge of the innate immune mechanisms developed by porcine IEC.