NF-κB and mucosal homeostasis.

NF-κB is well characterized as a primary mediator of inflammatory responses during infection and immune reactions, but it has recently become evident that NF-κB also mediates a potent cytoprotective, homeostatic function under basal conditions. This role is especially evident in the mammalian intestine, which is challenged not only with a range of microbial pathogens, but is also in constant contact with potent proinflammatory commensal bacteria and their products. Present data lead to the overall conclusion that antiapoptotic actions of NF-κB in intestinal epithelial cells dominate tissue responses to many acute inflammatory and injurious challenges, whereas proinflammatory and cell survival functions of NF-κB in macrophages and T cells govern chronic intestinal inflammation. This review focuses on the protective and homeostatic functions of NF-κB, and the importance of NF-κB in determining host-microbe interactions in the intestinal tract.