Changes in biological and virulent characteristics of Helicobacter pylori exposed to high salt.

The effect of high salt environments on biological characteristics of Helicobacter pylori is still unclear. In the present study, we therefore investigated biological characteristics of the bacterium exposed to high salt concentrations. H. pylori strain, L301, was cultured in media supplemented with different concentrations (3%, 15% and 30%) of sodium chloride (NaCl) under microaerophilic conditions for 48 h. Morphology was assessed by light microscopy, the ATP content was quantitated by single-tube fluorescent light-emission and the levels of CagA and UreB proteins were determined by Western blotting. After exposure to NaCl, H. pylori transformed from common spiral shape to U or even coccoid shapes. The ATP content was significantly higher in 30% NaCl group than in 15% and 3% NaCl group and the level of CagA protein increased with the salt concentration. The urease reaction was all strongly positive in H. pylori exposed to different salt concentrations. The level of 8-OHdG expression was significantly increased in GES-1 cells co-cultured with H. pylori exposed to high salt, compared with the level in uninfected cells. H. pylori survives under exposure to high salt concentrations up to 30%, exhibiting changes in mobility, morphology and CagA expression, associated with increased 8-OHdG in the gastric epithelial cells, indicative of DNA damage.