ABSTRACT
The intestinal epithelium is constantly exposed to many resident symbiotic bacteria and foreign bacterial pathogens that establish a docking in the gut. To cope with this microbial challenge, intestinal epithelial cells rely on multiple networks of microbial sensing and defense systems that act synergistically against bacterial invaders. Mucosal immunity consists of an innate and adaptive immune response playing a major role as dedicated host defense mechanism against pathogen survival and dissemination in the host (Macdonald and Monteleone 2005). Both the intestinal epithelial cell layer and the mucosal surface act as defensive barriers against bacterial intruders. The intestinal epithelium is covered by protective layers consisting of cell surface and gel forming mucins, antigen-specifi c secretory
1 Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 25-28 Rue du Docteur Roux, 75724 Paris Cedex 15, France.
