TY - JOUR T1 - Immune regulation and colitis: suppression of acute inflammation allows the development of chronic inflammatory bowel disease JF - Gut JO - Gut SP - 4 LP - 6 DO - 10.1136/gut.2004.047084 VL - 54 IS - 1 AU - B Eksteen AU - L S K Walker AU - D H Adams Y1 - 2005/01/01 UR - http://gut.bmj.com/content/54/1/4.abstract N2 - Persistent colitis is the result of a balance between local inflammation and regulatory networks. Regulatory T cells have potent anti-inflammatory effects and are likely to be important in the pathogenesis of chronic inflammatory bowel disease The success of the gastrointestinal immune system depends on a balance between mounting effective immune responses to pathogenic antigens while suppressing potentially damaging responses against commensal organisms or food antigens. Both the innate and acquired immune system contribute to fighting pathogens. The innate immune system, which includes phagocytes, dendritic cells (DCs), and natural killer (NK) cells, does not require previous exposure to a pathogen and instead relies on evolutionarily ancient pathways such as Toll-like receptors (TLRs) to recognise molecular patterns associated with harmful pathogens.1 Different TLRs are able to recognise bacterial products or motifs in viral RNA or DNA. TLR activation triggers an immediate response resulting in the activation of phagocytic mechanisms and the production of cytokines and costimulatory signals that activate the cognate immune response. The cognate or acquired immune system developed in higher vertebrates to provide a more sophisticated response to a wide variety of antigens. It involves lymphocytes that recognise specific antigens from pathogens processed and presented by specialised antigen presenting cells called DCs. A crucial feature of the cognate immune system is immunological memory whereby a subsequent exposure to the same antigen leads to a more potent and sustained immune response. Antigens from pathogens that penetrate the mucosal barrier are taken up by local DCs and carried via lymphatics to draining mesenteric lymph nodes.2 In addition, DCs situated in gut associated lymphoid tissue such as Peyer’s patches sample luminal antigens either directly, by extending finger-like processes into the lumen, or via specialised epithelial cells (M cells) that actively transport luminal antigens to the underlying DCs.3 Antigen containing DCs … ER -