TLR9 regulates the mycobacteria-elicited pulmonary granulomatous immune response in mice through DC-derived Notch ligand delta-like 4
Toshihiro Ito, Matthew Schaller, Cory M. Hogaboam, Theodore J. Standiford, Matyas Sandor, Nicholas W. Lukacs, Stephen W. Chensue, Steven L. Kunkel
Toshihiro Ito, Matthew Schaller, Cory M. Hogaboam, Theodore J. Standiford, Matyas Sandor, Nicholas W. Lukacs, Stephen W. Chensue, Steven L. Kunkel
View: Text | PDF
Research Article Infectious disease

TLR9 regulates the mycobacteria-elicited pulmonary granulomatous immune response in mice through DC-derived Notch ligand delta-like 4

Abstract

TLR9 activation is important for the maintenance of mycobacteria-elicited pulmonary granulomatous responses, hallmarks of protective immune responses following mycobacterial infection. However, the mechanism or mechanisms underlying this effect of TLR9 are not clear. Here, we show that Tlr9-deficient mice challenged with a Mycobacterium antigen display an altered Th17 cytokine profile, decreased accumulation of granuloma-associated myeloid DCs, and profoundly impaired delta-like 4 (dll4) Notch ligand expression. Mechanistic analysis revealed that WT bone marrow–derived DCs but not macrophages promoted the differentiation of Th17 cells from bacillus Calmette-Guérin–challenged (BCG-challenged) lung CD4+ T cells. Both lung and bone marrow DCs isolated from Tlr9-deficient mice inoculated with Mycobacterium antigen expressed lower levels of dll4 Notch ligand than the same cells isolated from WT mice. Passively immunizing WT mice with neutralizing antibodies specific for dll4 during granuloma formation resulted in larger granulomas and lower levels of Th17-related cytokines. In addition, dll4 specifically regulated Th17 activation in vitro. Together, these results suggest dll4 plays an important role in promoting Th17 effector activity during a mycobacterial challenge. Furthermore, TLR9 seems to be required for optimal dll4 expression and the regulation of Mycobacterium antigen–elicited granuloma formation in mice.

Authors

Toshihiro Ito, Matthew Schaller, Cory M. Hogaboam, Theodore J. Standiford, Matyas Sandor, Nicholas W. Lukacs, Stephen W. Chensue, Steven L. Kunkel

×

Figure 8

The differentiation of Th17 cells from T cells restimulated with BCG was specifically regulated in a dll4-dependent manner.

Options: View larger image (or click on image) Download as PowerPoint
The differentiation of Th17 cells from T cells restimulated with BCG was...
(A–D) Lung CD4+ T cells were isolated from WT mice and stimulated with BCG-pulsed BM-derived DCs from either WT or Tlr9–/– mice. (E and F) Splenic CD4+ T cells were isolated from DO11.10 mice and stimulated with OVA-pulsed BM-derived DCs from either WT or Tlr9–/– mice. Cells were cocultured with recombinant dll4 (rdll4) or PBS controls (A and B) or with anti-dll4 Ab or control IgG (C–F). Supernatants were assayed for IFN-γ production (A, C, and E) or IL-17 production (B, D, and F). *P < 0.05 compared with WT DC. #P < 0.01 compared with PBS (A and B) or control Ab (C and D). Data shown are mean ± SEM and are from a representative experiment of 3 independent experiments. Each time point represents 4 mice per group.