Gastroduodenal mucosal defense

The term mucosal defense refers to the ability of the gastroduodenal mucosa to resist injury induced by luminal irritants. Although it is becoming clear that most, if not all, peptic ulcers can be attributed to either Helicobacter pylori or nonsteroidal anti-inflammatory drugs (NSAIDs), the importance of mucosal defense remains undiminished. Most people who are infected with H. pylori never develop an ulcer, Likewise, the majority of patients who regularly consume NSAIDs do not develop gastric or duodenal ulcers. These observations strongly suggest that differences in the mucosal defensive response determine which patients who are exposed to H. pylori or NSAIDs develop an ulcer. Significant progress continues to be made in understanding the contribution of various components of the mucosal defense network to resistance to injury. This includes advances in understanding the regulation of mucus and bicarbonate secretion, the factors contributing to changes in mucosal blood flow in response to luminal irritants, and the role of the mucosal immune system in preventing or, in some cases, causing mucosal injury. Advances have also been made in understanding the mechanisms by which the mucosa adapts to repeated exposure to damaging agents and through which repair of ulcerated tissue occurs.