Role of Peyer's patches in the induction of Helicobacter pylori-induced gastritis

Helicobacterpylori is a Gram-negative spiral bacterium that causes gastritis and peptic ulcer and has been implicated in the pathogenesis of gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. Although Thl immunity is involved in gastritis and the accumulation of H. py/ori-specific CD4(+) T cells in theH.pylori-infected gastricmucosa in human patients, how T cells are primed with H. pylori antigens is unknown because no apparent lymphoid tissues are present in the stomach. We demonstrate here that Peyer's patches (PPs) in the small intestine play critical roles in H. pylori-induced gastritis; no gastritis is induced in H. py/ori-infected mice lacking PPs. Wealsoobserved thatthe coccoid form of H. pylori is phagocytosed by dendritic cells in PPs. We propose that H. pylori converts to the coccoid form intheanaerobIc small intestine and stimulates the host immune system through PPs.