Enhanced mucosal and systemic immune responses to Helicobacter pylori antigens through mucosal priming followed by systemic boosting immunizations

Abstract

SUMMARYIt is estimated that Helicobacter pylori infects the stomachs of over 50% of the world's population and if not treated may cause chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and gastric B-cell lymphoma. The aim of this study was to enhance the mucosal and systemic immune responses against the H. pylori antigens cytotoxin-associated gene A (CagA) and neutrophil-activating protein (NAP), through combinations of mucosal and systemic immunizations in female BALB/c mice. We found that oral or intranasal (i.n.) followed by i.m. immunizations induced signi®cantly higher serum titres against NAP and CagA compared to i.n. alone, oral alone, i.m. alone, i.m. followed by i.n. or i.m. followed by oral immunizations. However, only oral followed by i.m. immunizations induced anti-NAP antibody-secreting cells in the stomach. Moreover, mucosal immunizations alone or in combination with i.m., but not i.m. immunizations alone, induced mucosal immunoglobulin A (IgA) responses in faeces. Any single route or combination of immunization routes with NAP and CagA preferentially induced antigen-speci®c splenic interleukin-4-secreting cells and far fewer interferon-g-secreting cells in the spleen. Moreover, i.n. immunizations alone or in combination with i.m. immunizations induced predominantly serum IgG1 and far less serum IgG2a. Importantly, we found that while both i.n. and i.m. recall immunizations induced similar levels of serum antibody responses, mucosal IgA responses in faeces were only achieved through i.n. recall immunization. Collectively, our data show that mucosal followed by systemic immunization signi®cantly enhanced local and systemic immune responses and that i.n. recall immunization is required to induce both mucosal and systemic memory type responses.

Therapeutic Vaccination againstHelicobacter pyloriin the Beagle Dog Experimental Model: Safety, Immunogenicity, and Efficacy

“…In particular, primeboost vaccination protocols, combining mucosal and parenteral administration, seem to be more promising than mucosal or parenteral alone in eliciting both cellular and humoral response (18,37), as well as in providing protection against H. pylori challenge (18). Although these protection data have been obtained by prophylactic vaccination, they should be taken in account in attempts to design a more efficacious protocol of therapeutic vaccination since, in this case, the infection can act as an effective mucosal priming (35).…”

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

“…Antigen specific IL-4 and IFN-γ responses from lymphocytes were measured using ELISPOT as previously described [46]. Briefly, 2 × 10 6 lymphocytes were added to polyvinyldifluoride plates (Millipore) precoated with rat anti-mouse IL-4 (Endogen, Woburn, MA) or rat antimouse IFN-γ (BD/Pharmingen, San Diego, CA) and blocked with complete RPMI 10% FBS.…”

Possible Correlates of Long-Term Protection againstHelicobacter pylorifollowing Systemic or Combinations of Mucosal and Systemic Immunizations

“…Immunogenicity studies have also shown that the combination of mucosal priming followed by systemic boosting results in high antigenspecific antibody responses (25,39,40). However, in most H. pylori vaccine/protection studies immunized animals were challenged within a month after immunization, whereas we challenged the animals 3 months after immunization (11,13,15,20,24,34,35,43).…”

“…Antigen-specific cytokine assays. Antigen-specific IL-4 responses in lymphocytes from immunized mice were measured using an ELISPOT assay as previously described (40). Briefly, 2 ϫ 10 6 lymphocytes were added to polyvinylidene difluoride plates (Millipore) precoated with rat anti-mouse IL-4 (Endogen, Woburn, MA) and blocked with complete RPMI-10% FBS.…”

“…Unlike for Helicobacter felis, against which long-term protection can be achieved through immunization, a longterm-protection model for H. pylori has yet to be reported (27,33). Recent studies have demonstrated that immunization through a combination of mucosal and systemic routes may increase mucosal immunity (22,25,39,40).…”