Bradykinin B2 Receptors of dendritic cells, acting as sensors of kinins proteolytically released by Trypanosoma cruzi, are critical for the development of protective type-1 responses

PLoS Pathog. 2007 Nov;3(11):e185. doi: 10.1371/journal.ppat.0030185.

Abstract

Although the concept that dendritic cells (DCs) recognize pathogens through the engagement of Toll-like receptors is widely accepted, we recently suggested that immature DCs might sense kinin-releasing strains of Trypanosoma cruzi through the triggering of G-protein-coupled bradykinin B2 receptors (B2R). Here we report that C57BL/6.B2R-/- mice infected intraperitoneally with T. cruzi display higher parasitemia and mortality rates as compared to B2R+/+ mice. qRT-PCR revealed a 5-fold increase in T. cruzi DNA (14 d post-infection [p.i.]) in B2R-/- heart, while spleen parasitism was negligible in both mice strains. Analysis of recall responses (14 d p.i.) showed high and comparable frequencies of IFN-gamma-producing CD4+ and CD8+ T cells in the spleen of B2R-/- and wild-type mice. However, production of IFN-gamma by effector T cells isolated from B2R-/- heart was significantly reduced as compared with wild-type mice. As the infection continued, wild-type mice presented IFN-gamma-producing (CD4+CD44+ and CD8+CD44+) T cells both in the spleen and heart while B2R-/- mice showed negligible frequencies of such activated T cells. Furthermore, the collapse of type-1 immune responses in B2R-/- mice was linked to upregulated secretion of IL-17 and TNF-alpha by antigen-responsive CD4+ T cells. In vitro analysis of tissue culture trypomastigote interaction with splenic CD11c+ DCs indicated that DC maturation (IL-12, CD40, and CD86) is controlled by the kinin/B2R pathway. Further, systemic injection of trypomastigotes induced IL-12 production by CD11c+ DCs isolated from B2R+/+ spleen, but not by DCs from B2R-/- mice. Notably, adoptive transfer of B2R+/+ CD11c+ DCs (intravenously) into B2R-/- mice rendered them resistant to acute challenge, rescued development of type-1 immunity, and repressed TH17 responses. Collectively, our results demonstrate that activation of B2R, a DC sensor of endogenous maturation signals, is critically required for development of acquired resistance to T. cruzi infection.

Publication types

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

MeSH terms

  • Adoptive Transfer
  • Animals
  • Chagas Disease / immunology*
  • Chagas Disease / metabolism
  • Dendritic Cells / immunology*
  • Dendritic Cells / metabolism
  • Flow Cytometry
  • Interferon-gamma / biosynthesis
  • Interleukin-12 / biosynthesis
  • Interleukin-17 / biosynthesis
  • Kinins / immunology
  • Kinins / metabolism*
  • Lymphocyte Activation / immunology
  • Mice
  • Mice, Mutant Strains
  • Polymerase Chain Reaction
  • Receptor, Bradykinin B2 / immunology*
  • Receptor, Bradykinin B2 / metabolism
  • Th1 Cells / immunology*
  • Th1 Cells / metabolism
  • Trypanosoma cruzi
  • Tumor Necrosis Factor-alpha / biosynthesis

Substances

  • Interleukin-17
  • Kinins
  • Receptor, Bradykinin B2
  • Tumor Necrosis Factor-alpha
  • Interleukin-12
  • Interferon-gamma