The immuno-inflammatory mechanism for tissue injury in inflammatory bowel disease and Helicobacter pylori-infected chronic active gastritis: Roles of the mucosal immune system

The gastrointestinal mucosa is exposed to myriads of infectious and food antigens, and a unique barrier mechanism handles them on the mucosal surface, and specific immune responses to these antigens call on the mucosal immune system in the mucosal tissues to maintain homeostasis of gastrointestinal functions and structure. Abrogation of these mucosal defense mechanisms may lead to alter immunologic homeostasis in the gastrointestinal tract and to induce pathological features of inflammatory bowel disease (IBD) and Helicobacter pylori-infected chronic active gastritis, including chronic active inflammation, mucosal atrophy and tissue injuries. Regardless of the initiating cause of these long-standing chronic active mucosal inflammations, characteristic immuno-inflammatory mechanisms are involved in their pathogenesis, that is, similar and/or different specific prolonged impaired and excessive immuno-inflammatory responses following the abrogation of the mucosal barrier system are present in the diseased mucosa with IBD and H. pylori infection, respectively.