Virulence factors of Helicobacter pylori in Korean isolates do not influence proinflammatory cytokine gene expression and apoptosis in human gastric epithelial cells, nor do these factors influence the clinical outcome

The cytotoxin-associated gene (cagA) and vacuolating cytotoxin (Vac) produc tion have been reported to be major virulence factors of Helicobacter pylor i. However, there have been some disputes regarding the correlation between these virulence factors and clinical outcomes. We evaluated whether the ca gA-positive genotype and Vac production might be correlated with various ga stroduodenal diseases in Korea and whether this correlation could be due to differences in proinflammatory cytokine gene expression and apoptosis of g astric epithelial cells in vitro. The presence of the cagA gene was examine d by the polymerase chain reaction (PCR), and Vac production was detected u sing the bacterial culture supernatant and HeLa cells after H. pylori was i solated from Korean patients. Gastric epithelial cells were infected with c agA(+)Vac(+), cagA(+)Vac(-), or cagA(-)Vac(-) strains, after which cytokine gene expression was evaluated, using quantitative reverse transcription (R T)-PCR. Apoptosis and caspase-3 activation were measured in H. pylori-infec ted gastric epithelial cells. There was no significant correlation between the presence of these virulence factors in H. pylori isolates and peptic ul cer or gastric cancer. Upregulation of cytokine gene expression, including that of interleukin (IL)-1 alpha, IL-8, granulocyte macrophage colony-stimu lating factor (GM-CSF), and monocyte chemotactic protein (MCP)-1, as well a s apoptosis and caspase-3 activation, were similar in infections with cagA -positive and cagA-negative strains but were not correlated with the produc tion of Vac. These results suggest that the lack of correlation between vir ulence factors of isolated H. pylori strains and serious gastroduodenal dis ease entities in Korea may be due to the similar capacity for proinflammato ry cytokine gene expression and apoptosis caused by infection with each of the H. pylori strains.