IADR Abstract Archives
Canonical Wnt Signaling Primes Macrophage to a Pro-Inflammatory Phenotype
Objectives: Surface characteristics like roughness and hydrophilicity can activate macrophages to a pro- or anti-inflammatory phenotype on titanium (Ti). Recently, we demonstrated that Wnt signaling regulates macrophage response to biomaterials and that macrophages are an important source of Wnt ligands during inflammation. However, it remains unclear how Wnts control macrophage phenotype. The aim of this study was to elucidate the role of Wnt-canonical signaling on macrophage activation on modified Ti surfaces.
Methods: Primary bone-marrow-derived macrophages isolated from 12-week-old C57BL/6 mice were seeded on polystyrene or smooth, rough, or rough-hydrophilic Ti disks (n=6/variable), and treated ± Wnt-canonical activators (Wnt3a, AZD2858, SB2126763) or an inhibitor (PNU74654) for 12h for gene expression or 24h for cytokine analysis. For in vivo studies, intrafemoral smooth or rough-hydrophilic Ti implants were placed in 12-week-old C57BL/6 mice (n=6/variable) ± AZD2858, SB2126763, or PNU74654. After 3d or 7d, immune and stem cells were analyzed by flow cytometry.
Results: Activating Wnt-canonical signaling increased gene expression of toll-like receptors (1, 2, 4, 5, 9) and interleukin-receptors (Ilr1, Ilr6) and secreted pro-inflammatory cytokines (IL-1β, IL-6, TNF) and reduced levels of anti-inflammatory cytokines (IL-4, IL-10) on all Ti surfaces. Inhibiting Wnt-canonical signaling reduced levels or pro-inflammatory cytokines on all Ti surfaces and increased anti-inflammatory cytokines only on rough or rough-hydrophilic Ti surfaces. In vivo, activating Wnt-canonical signaling increased total macrophages, pro-inflammatory macrophages, and T-cell percentages and decreased anti-inflammatory macrophages on smooth and rough-hydrophilic implants when compared to controls. Inhibiting Wnt-canonical signaling did not affect pro-inflammatory macrophages but reduced T-cell percentage.
Conclusions:
Activating Wnt-canonical signaling increased pro-inflammatory cytokines and reduced anti-inflammatory cytokines. Furthermore, activation of Wnt-canonical signaling increased the presence of macrophages and T-cells in response to Ti implants. Our results showed that activating Wnt-canonical signal primes macrophages to a pro-inflammatory phenotype by increasing pro-inflammatory cytokine receptors and pattern-recognition-receptors.
Methods: Primary bone-marrow-derived macrophages isolated from 12-week-old C57BL/6 mice were seeded on polystyrene or smooth, rough, or rough-hydrophilic Ti disks (n=6/variable), and treated ± Wnt-canonical activators (Wnt3a, AZD2858, SB2126763) or an inhibitor (PNU74654) for 12h for gene expression or 24h for cytokine analysis. For in vivo studies, intrafemoral smooth or rough-hydrophilic Ti implants were placed in 12-week-old C57BL/6 mice (n=6/variable) ± AZD2858, SB2126763, or PNU74654. After 3d or 7d, immune and stem cells were analyzed by flow cytometry.
Results: Activating Wnt-canonical signaling increased gene expression of toll-like receptors (1, 2, 4, 5, 9) and interleukin-receptors (Ilr1, Ilr6) and secreted pro-inflammatory cytokines (IL-1β, IL-6, TNF) and reduced levels of anti-inflammatory cytokines (IL-4, IL-10) on all Ti surfaces. Inhibiting Wnt-canonical signaling reduced levels or pro-inflammatory cytokines on all Ti surfaces and increased anti-inflammatory cytokines only on rough or rough-hydrophilic Ti surfaces. In vivo, activating Wnt-canonical signaling increased total macrophages, pro-inflammatory macrophages, and T-cell percentages and decreased anti-inflammatory macrophages on smooth and rough-hydrophilic implants when compared to controls. Inhibiting Wnt-canonical signaling did not affect pro-inflammatory macrophages but reduced T-cell percentage.
Conclusions:
Activating Wnt-canonical signaling increased pro-inflammatory cytokines and reduced anti-inflammatory cytokines. Furthermore, activation of Wnt-canonical signaling increased the presence of macrophages and T-cells in response to Ti implants. Our results showed that activating Wnt-canonical signal primes macrophages to a pro-inflammatory phenotype by increasing pro-inflammatory cytokine receptors and pattern-recognition-receptors.