Potential relevance of agmatine as a virulence factor of Helicobacter pylori.

The polyamine agmatine is able to increase gastric acid secretion. Therefore, we investigated whether Helicobacter pylori is able to form and release agmatine in vitro and in the human stomach in vivo, and if so, whether a relationship exists among agmatine concentration in gastric juice, H. pylori infection, and gastroduodenal lesions. Agmatine was determined by means of HPLC. In the supernatant of H. pylori cultures, agmatine concentrations up to 1500 ng/ml (approximately 12 microM) were determined, depending on the number of the bacteria in the individual cultures. Agmatine concentration in gastric juice from H. pylori-positive patients was higher than in that from H. pylori-negative patients. Gastrin in blood was elevated in H. pylori-positive patients compared with H. pylori-negative patients. Agmatine concentration in gastric juice and serum gastrin level appeared to be related. In conclusion, H. pylori is able to form and to release agmatine in vitro and in vivo. This may be assumed to be relevant in vivo, since higher amounts of agmatine are present in gastric juice from H. pylori-positive than from H. pylori-negative patients. Accordingly, agmatine produced by H. pylori may be a virulence factor of this bacterium and may be involved in the pathogenesis of gastroduodenal lesions.