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

Abstract

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.

Fig. 1

Antigen specific IgG1 and IgG2a production from serum and mucosal lymphoid tissues. Mice (N=12) were immunized with either LPS containing H. pylori sonicate and CpG (LPS+/CpG) or LPS depleted sonicate and CT (LPS−/CT), followed by oral challenge with H. pylori. IgG1 and IgG2a antibody titers to H. pylori NAP are shown for serum and Peyer’s patches before (a, b) and after (c, d) H. pylori challenge. Titers were measured from mice seven days after the last immunization (prior to challenge) and seven days post-challenge. Data are represented as mean ± SEM. Statistical significance is denoted by * indicating P<0.05 and ** indicating P<0.01 compared to controls.

Fig. 2

IL-4 and IFN-γ antigen specific responses from immunized mice. Mice (N=12) were immunized with either LPS containing H. pylori sonicate and CpG (LPS+/CpG) or LPS depleted sonicate and CT (LPS−/CT), followed by oral challenge with H. pylori. Splenocytes were cultured with H. pylori sonicate and mean (± SEM) numbers of IL-4 (gray) and IFN-γ (black) secreting cells were measured by ELISPOT. Statistical significance is denoted by * indicating P<0.05 and ** indicating P<0.01 compared to controls.

Fig. 3

IL-5, IL-6, and IL-2 antigen specific responses from immunized mice. Mice (N=12) were immunized with either LPS containing H. pylori sonicate and CpG (LPS+/CpG) or LPS depleted sonicate and CT (LPS−/CT), followed by oral challenge with H. pylori. Splenocytes were cultured with H. pylori sonicate and culture supernatants were used to measure (a) IL-5, (b) IL-6, and (c) IL-2 production by Luminex. Data are represented as mean ± SEM. Statistical significance is denoted by * indicating P<0.05 and ** indicating P<0.01 compared to controls.

Fig. 4

GM-CSF, IL-1β, IL-10, and IL-12 responses from immunized mice. Mice (N=12) were immunized with either LPS containing H. pylori sonicate and CpG (LPS+/CpG) or LPS depleted sonicate and CT (LPS−/CT), followed by oral challenge with H. pylori. Splenocytes were cultured with H. pylori sonicate and culture supernatants were used to measure (a) GM-CSF, (b) IL-1β, (c) IL-10, and (d) IL-12 production by Luminex. Data are represented as mean ± SEM. Statistical significance is denoted by * indicating P<0.05 and ** indicating P<0.01 compared to controls.

Fig. 5

Log₁₀ CFU/gram of tissue obtained 8 days after challenged. Twelve mice were immunized with either LPS containing sonicate and CpG (LPS+/CpG) or LPS depleted sonicate and CT (LPS−/CT), followed by oral challenge one month later with 10⁸ CFU H. pylori SS1. LPS+/CpG immunized mice had significantly fewer bacteria than LPS−/CT immunized mice or mock controls (P<0.05). Bars represent means of the group. Statistical significance is denoted by * indicating P<0.05 and ** indicating P<0.01 compared to controls.