Molecular biological mechanisms of mucosal inflammation in H. pylori-induced gastritis

点击翻译按钮获取中文摘要

Antigen-presenting cells are important in the orchestration of immune responses, and their expression of class II MHC enables them to present antigens to CD4+ T cells, A costimulatory signal is also needed for the activation of T cells. Gastric epithelial cells and another cells in the mucosa scarcely express class II MHC, and the amount is remarkably increases in H. pylori infection. Surface epithelial cells were stained for HLA-DR but not ICAM-1, B7-1, or B7-2. Eluctron microscopy of affected mucosa showed lymphocytes adhering to dendritic cells and macrophage stained for ICAM-1 or B7 or both, perhaps because these were presenting antigens to T cells. These results suggest that dendritic cells and macrophages, not surface epithelial cells, are the antigen-presenting cells in the gastric mucosa of patients with gastritis arising from H. pylori. H. pylori stimulates the production of proinflammatory cytokines such as IL-1β and TNF-α by monocytes. The local production of these cytokines … More is an important cause of gastric mucosal inflammation related to H. pylori. The H. pylori extract stimulated the production of these cytokines. PGE2 inhibited such production and also inhibited the expression of messenger RNA. Inhibition by PG of H. pylori-stimulated production of proinflammatory cytokines by monocytes may account for part of the protective and anti-inflammatory effects of PG on gastric mucosa. Gastric cancer continues to be one of the most common malignancies in the world. Recent reports demonstrate the relationship between H. pylori infection and gastric carcinogenesis in Mongolian gerbils. In an attempt to search for dietary factors affecting H. pylori -associated gastritis, we examined the effects of fish meal on H. pylori -infected animals. Fish meal had markedly enhanced H. pylori-induced gastritis in Mongolian gerbils. These results suggest that development of H. pylori -induced gastritis was affected environmental factors including dietary intake, as well as H. pylori strain diversity and host factors. Less