Reactions from rat gastric mucosa during one year of Helicobacter pylori infection

The aim of the present study was to investigate responses from the gastric mucosa of rats during long-term H. pylori infection. Twenty-four Sprague-Da wley rats were inoculated with a mouse-adapted strain of human H. pylori (v acA(+), cagA(+)), 16 uninfected rats served as controls. Three to six rats from each group were killed two weeks or two, six, or 12 months later. At s acrifice, blood was sampled and the gastric mucosa was taken for bacterial culture, histology, immunocytochemistry and in situ hybridization. H. pylor i colonized the antrum in 23/24 inoculated rats; with time the density of b acteria increased. The inflammation in the antral mucosa was mild to modera te and was dominated by infiltration of lymphocytes and macrophages. Serum H. pylori-specific IgG(2a) was significantly increased in the infected rats . The frequency of epithelial cell apoptosis was significantly increased in the early months of infection. The mucosal expression of trefoil peptide m RNA remained unchanged. We conclude that after one year of H. pylori infect ion in rats, the mucosal responses were rather mild, indicating that the an imals may adapt to the infection by mechanisms which remain to be identifie d.