title: 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.
abstract: Intragastric immunization with recombinant chimeric immunogen, SBR-CTA2/B, constructed from the saliva-binding region (SBR) of Streptococcus mutans antigen AgI/II and the A2/B subunits of cholera toxin (CT) induces salivary and circulating antibodies against S. mutans that protect against dental caries. We previously found that SBR-CTA2/B activated dendritic cells (DC) in the Peyer's patches (PP) and mesenteric lymph nodes (MLN). To identify the cells involved in the intestinal uptake of SBR-CTA2/B and the initiation of immune responses, mice were immunized intragastrically with fluorescein-labeled SBR-CTA2/B or SBR, and intestinal cells were examined by imaging flow cytometry after fluorescent staining for cell surface markers. SBR-CTA2/B was preferentially taken up by CD103(+) DC in the PP and by both CD103(+) and CD11c(+) DC in intestinal lamina propria (LP), whereas SBR was taken up to a lesser extent by PP CD11c(+) DC, within 2 to 16 h. By 16 h, CD103(+) and CD11c(+) DC containing fluorescein-labeled SBR-CTA2/B were found in MLN and showed upregulation of the chemokine receptor CCR7. Large numbers of SBR-CTA2/B-containing DC were found interacting with CD4(+) (T helper) cells, which costained for nuclear transcription factors T-bet or RORγt, identifying them as Th1 or Th17 cells. In contrast, SBR-containing CD11c(+) DC interacted preferentially with GATA3(+) (Th2) cells. No SBR- or SBR-CTA2/B-containing DC were found interacting with Foxp3(+) (T regulatory) cells. We conclude that the coupling of SBR to CTA2/B enhances its immunogenicity by promoting uptake by DC in both PP and LP and that these antigen-containing DC migrated to MLN and interacted preferentially with Th1 and Th17 cells to induce active immune responses.
authors.affiliation: Department of Microbiology and Immunology and Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, Buffalo, New York, USA.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhao
authors.forename: Hans
authors.initials: H
authors.lastname: Minderman
authors.forename: Michael W
authors.initials: MW
authors.lastname: Russell
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D005751:Gastric Lavage; D007413:Intestinal Mucosa / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011994:Recombinant Proteins / Q000276:immunology* / Q000378:metabolism; D022541:Streptococcal Vaccines / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism; D013295:Streptococcus mutans / Q000235:genetics / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D022541:Streptococcal Vaccines; D014614:Vaccines, Synthetic