Studies on the host related factors determining clinical manifestation of the Helicobacter pylori infection among patients with various ethnic backgrounds.

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Huge population in the world, more than two billions, and more than sixty millions of people in Japan are infected with Helicobacter pylori (H.pylori). Huge sum of money is also invested for the treatment as well as prevention of the diseases related to H.pylori infection. Not all of the patients with this infection develop such diseases as peptic ulcers, MALTOMAs or gastric cancers. The pathogenic mechanisms explaining why limited subgroups of the patients develop these diseases are not understood. The differences in seroprevalence, disease spectrum and clinical outcome of this infection among the population with various ethnic background has been reported in Asian countries, which cannot be explained solely by genetical differences of the pathogen infected or by thedifferences in the socioeconomic as well as social sanitation levels in these countries. The host related factors should also determine clinical outcome of the infection, which are mostly unknown. In order to accumulate cl … More inical data and to study mechanisms of pathogenesis, we have established collaboration among investigators in Japan and abroad. We have obtained several findings out ofstudies utilizing human clinical samples and animal disease models.1, Not only the inflammatory mediators produced by the interaction between H.pylori and gastric epithelia, the host mucosal immune system including salivary glands and GALT (gut associated lymphoid tissue) also play important roles for the histological manifestation of the gastritis.2, We found differences in seroprevalence and profiles of antibodies to H.pylori in the blood among different ethnic groups in Malaysia and Japanese. This may explain different rate of incidence of gastric cancer and differences in clinical manifestation of the infection among study groups.3. Collaboration with investigators in Czech was carried out. Multiple parametric analyses in the patients with H.pylori infection in Czech revealed correlation among presence of H.pylori infection, family history of gastric cancer, level of ammonia produced in the stomach and grade of histological gastritis. Less