Targeting of DC-SIGN on human dendritic cells by minor fimbriated Porphyromonas gingivalis strains elicits a distinct effector T cell response

J Immunol. 2009 Nov 1;183(9):5694-704. doi: 10.4049/jimmunol.0901030. Epub 2009 Oct 14.

Abstract

The oral mucosal pathogen Porphyromonas gingivalis expresses at least two adhesins: the 67-kDa mfa-1 (minor) fimbriae and the 41-kDa fimA (major) fimbriae. In periodontal disease, P. gingivalis associates in situ with dermal dendritic cells (DCs), many of which express DC-SIGN (DC-specific ICAM-3 grabbing nonintegrin; CD209). The cellular receptors present on DCs that are involved in the uptake of minor/major fimbriated P. gingivalis, along with the effector immune response induced, are presently unclear. In this study, stably transfected human DC-SIGN(+/-) Raji cell lines and monocyte-derived DCs (MoDCs) were pulsed with whole, live, wild-type Pg381 or isogenic major (DPG-3)-, minor (MFI)-, or double fimbriae (MFB)-deficient mutant P. gingivalis strains. The influence of blocking Abs, carbohydrates, full-length glycosylated HIV-1 gp120 envelope protein, and cytochalasin D on the uptake of strains and on the immune responses was determined in vitro. We show that the binding of minor fimbriated P. gingivalis strains to Raji cells and MoDCs is dependent on DC-SIGN, whereas the double fimbriae mutant strain does not bind. Binding to DC-SIGN on MoDCs is followed by the internalization of P. gingivalis into DC-SIGN-rich intracellular compartments, and MoDCs secrete low levels of inflammatory cytokines and remain relatively immature. Blocking DC-SIGN with HIV-1 gp120 prevents the uptake of minor fimbriated strains and deregulates the expression of inflammatory cytokines. Moreover, MoDCs promote a Th2 or Th1 effector response, depending on whether they are pulsed with minor or major fimbriated P. gingivalis strains, respectively, suggesting distinct immunomodulatory roles for the two adhesins of P. gingivalis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Adhesion / genetics
  • Bacterial Adhesion / immunology*
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism*
  • Cell Adhesion Molecules / physiology
  • Cell Compartmentation / genetics
  • Cell Compartmentation / immunology
  • Cell Line, Tumor
  • Cells, Cultured
  • Coculture Techniques
  • Dendritic Cells / immunology*
  • Dendritic Cells / metabolism*
  • Dendritic Cells / microbiology
  • Endocytosis / immunology
  • Fimbriae, Bacterial / genetics
  • Fimbriae, Bacterial / immunology*
  • Fimbriae, Bacterial / metabolism*
  • Gene Targeting / methods
  • Humans
  • Lectins, C-Type / genetics
  • Lectins, C-Type / metabolism*
  • Lectins, C-Type / physiology
  • Monocytes / immunology
  • Monocytes / metabolism
  • Monocytes / microbiology
  • Porphyromonas gingivalis / genetics
  • Porphyromonas gingivalis / immunology*
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Receptors, Cell Surface / physiology
  • Th1 Cells / immunology
  • Th1 Cells / metabolism
  • Th1 Cells / microbiology
  • Th2 Cells / immunology*
  • Th2 Cells / metabolism
  • Th2 Cells / microbiology

Substances

  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • Lectins, C-Type
  • Receptors, Cell Surface