Immunosuppressive and Proinflammatory Activities of the VacA Toxin of Helicobacter pylori

20 yr have elapsed since the discovery of the association of the then novel bacterium Helicobacter pylori with different gastroduodenal diseases, including severe active chronic gastritis, gastroduodenal ulcers, adenocarcinoma, and lymphoma (1). The amount of research performed from the clinical to the molecular level is impressive (2). It is presently well established that H. pylori infects the large majority of the human population with a very high prevalence in countries with poor hygienic conditions. H. pylori is human specific and resides in a defined ecological niche comprising the stomach mucus layer and the stomach epithelial lining. The infection is chronic and life lasting if not treated with antibiotics. Only a minority of the infected persons develop gastroduodenal diseases, suggesting that an adverse outcome of the infection depends strongly on the response of the host and/or on the interplay with the genetic...