Novel activities of the Helicobacter pylori vacuolating cytotoxin: from epithelial cells towards the immune system.

H. pylori has developed a unique set of virulence factors, which allow its survival in a unique ecological niche, the human stomach. The vacuolating cytotoxin (VacA) and the cytotoxin-associated antigen (CagA) are major bacterial factors involved in modulating the host. VacA, so far mainly regarded as a cytotoxin for the gastric epithelial cell layer, apparently has profound effects in modulating the immune response. In this review we discuss some of the classical effects of VacA, such as cell vacuolation, and compare them with more recently identified mechanisms of VacA on immune cells.