Enhanced immunogenicity of a tricomponent mannan tetanus toxoid conjugate vaccine targeted to dendritic cells via Dectin-1 by incorporating β-glucan

J Immunol. 2013 Apr 15;190(8):4116-28. doi: 10.4049/jimmunol.1202937. Epub 2013 Mar 20.

Abstract

In a previous attempt to generate a protective vaccine against Candida albicans, a β-mannan tetanus toxoid conjugate showed poor immunogenicity in mice. To improve the specific activation toward the fungal pathogen, we aimed to target Dectin-1, a pattern-recognition receptor expressed on monocytes, macrophages, and dendritic cells. Laminarin, a β-glucan ligand of Dectin-1, was incorporated into the original β-mannan tetanus toxoid conjugate providing a tricomponent conjugate vaccine. A macrophage cell line expressing Dectin-1 was employed to show binding and activation of Dectin-1 signal transduction pathway by the β-glucan-containing vaccine. Ligand binding to Dectin-1 resulted in the following: 1) activation of Src family kinases and Syk revealed by their recruitment and phosphorylation in the vicinity of bound conjugate and 2) translocation of NF-κB to the nucleus. Treatment of immature bone marrow-derived dendritic cells (BMDCs) with tricomponent or control vaccine confirmed that the β-glucan-containing vaccine exerted its enhanced activity by virtue of dendritic cell targeting and uptake. Immature primary cells stimulated by the tricomponent vaccine, but not the β-mannan tetanus toxoid vaccine, showed activation of BMDCs. Moreover, treated BMDCs secreted increased levels of several cytokines, including TGF-β and IL-6, which are known activators of Th17 cells. Immunization of mice with the novel type of vaccine resulted in improved immune response manifested by high titers of Ab recognizing C. albicans β-mannan Ag. Vaccine containing laminarin also affected distribution of IgG subclasses, showing that vaccine targeting to Dectin-1 receptor can benefit from augmentation and immunomodulation of the immune response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites / immunology
  • Cell Line
  • Dendritic Cells / immunology
  • Dendritic Cells / metabolism*
  • Drug Delivery Systems* / methods
  • Epitopes / immunology
  • Epitopes / metabolism
  • Glucans
  • Lectins, C-Type / administration & dosage*
  • Lectins, C-Type / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Polysaccharides / immunology
  • Polysaccharides / metabolism
  • Tetanus Toxoid / administration & dosage*
  • Tetanus Toxoid / immunology*
  • Tetanus Toxoid / metabolism
  • Trisaccharides / administration & dosage
  • Trisaccharides / immunology
  • Trisaccharides / metabolism
  • Vaccines, Conjugate / administration & dosage
  • Vaccines, Conjugate / immunology
  • Vaccines, Conjugate / metabolism
  • beta-Glucans / immunology
  • beta-Glucans / metabolism*

Substances

  • Epitopes
  • Glucans
  • Lectins, C-Type
  • Polysaccharides
  • Tetanus Toxoid
  • Trisaccharides
  • Vaccines, Conjugate
  • beta-Glucans
  • dectin 1
  • laminaran