Characterization of antigen‐presenting cells induced by intragastric immunization with recombinant chimeric immunogens constructed from Streptococcus mutans AgI/II and type I or type II heat‐labile enterotoxins

Abstract

SummaryIntragastric (i.g.) immunization with recombinant chimeric proteins constructed from the salivabinding region (SBR) of Streptococcus mutans surface antigen AgI/II and the A2/B subunits of enterobacterial heat-labile enterotoxins has been successfully used to induce salivary and circulating antibodies against S. mutans that have protective potential against dental caries. To investigate the mode of action of these vaccine constructs, mice were immunized i.g. with chimeric proteins constructed from SBR and cholera toxin (CT) or the type II enterotoxins of Escherichia coli, LT-IIa and LT-IIb. Antigen-presenting cells (APC) in Peyer's patches (PP) and mesenteric lymph nodes (MLN) were characterized by flow cytometry. Compared to immunization with SBR alone, chimeric proteins SBR-LTIIaA2/B and SBR-LTIIbA2/B increased the number of B cells and macrophages in PP and diminished B cell numbers in MLN, whereas SBR-CTA2/B diminished the numbers of B cells and macrophages in PP and MLN. Immunization with all three chimeric proteins led to upregulation of MHC class II molecules and costimulatory receptors CD40, CD80, and CD86 especially on dendritic cells in PP and also on APC in MLN. The results provide a molecular basis for the enhanced immune responses induced by chimeric proteins compared to uncoupled antigen, and for differential responses to chimeric proteins based on CT or type II enterotoxins.

B Cells, Dendritic Cells, and Macrophages Are Required To Induce an Autoreactive CD4 Helper T Cell Response in Experimental Epidermolysis Bullosa Acquisita

“…Overall, this indicates that signals from several APCs are required to lead to the formation of vWFA2-reactive CD4 T cells. Previous studies showed that different APCs were required in the Agpresenting process (50)(51)(52). Particularly in the collagen-induced arthritis model in rats, similar results like in our model were observed (50).…”

Immunogenicity and In Vitro and In Vivo Protective Effects of Antibodies Targeting a Recombinant Form of the Streptococcus mutans P1 Surface Protein

“…Our results suggest that the adjuvant effect of heat-labile toxins favors the generation of antibodies against conformational determinants relevant for the function of the P1 adhesin. Previous studies employing the saliva-binding region (SBR) of P1 have also reported positive results when the immunogen was administered in combination with different LT derivatives, either as an isolated polypeptide or as a chimeric protein genetically fused to the B subunit of cholera toxin (52,53).…”

“…As a mediator of sucroseindependent attachment, P1 is an important target of such antibodies (21,22,27,(52)(53)(54)(55). To infer the potential protective effects conferred by immunization with P1 39 -512 , we determined if serum samples collected from vaccinated mice would reduce the initial adhesion of S. mutans to the dental surface of nonimmunized mice.…”

Identification and Characterization of Intestinal Antigen-Presenting Cells Involved in Uptake and Processing of a Nontoxic Recombinant Chimeric Mucosal Immunogen Based on Cholera Toxin Using Imaging Flow Cytometry

“…This finding raises the question of what cells are involved in the uptake and processing of SBR-CTA2/B at mucosal surfaces, leading to the induction of antibody responses. In a previous study (16), we investigated the antigen-presenting cells (APC) induced by i.g. immunization with recombinant chimeric immunogens prepared from SBR and the A2/B subunits of CT or the type II heat-labile enterotoxins, LT-IIa or LT-IIb.…”

“…We found that the chimeric immunogens induced the upregulation of costimulatory molecules on APC recovered from Peyer's patches (PP) and mesenteric lymph nodes (MLN). CD11c ϩ dendritic cells (DC) were identified as major APC in the PP and MLN (16). However, that study did not have the resolution to determine where chimeric immunogens were taken up in the intestinal tract, what cells were involved in the uptake, and how immune responses were initiated.…”