Effects of a Th1- versus a Th2-biased immune response in protection against Helicobacter pylori challenge in mice

The roles that T helper type 1 (Th1) and T helper type 2 (Th2) Helicobacter pylori-specific immune responses play in protection from H. pylori challenge are poorly understood. It is expected that Th2 immune responses are required for protection against extracellular bacteria, such as H. pylori. However, recent studies have suggested that Th1 immunity is required for protection. The mechanisms by which this might occur are unknown. Our goal in this study was to more clearly define the effects of a Th1- versus a Th2-promoting H. pylori vaccine on immunity and protection. Therefore, we tested a Th1 vaccine consisting of an H. pylori sonicate and CpG oligonucleotides (CpG) and a Th2 vaccine consisting of a lipopolysaccharide (LPS)-depleted H. pylori sonicate combined with cholera toxin (CT). We demonstrate that although the Th2-promoting vaccine induced stronger systemic and local immune responses, only the Th1-promoting vaccine was protective.