Figure 5.

TLR4-mediated IL-12 production by joint macrophages and mast cells plays crucial roles in promoting antibody-induced arthritis. To induce antibody-induced arthritis, mice were injected with K/BxN serum (150 μL) twice (A-E). (A) Intracellular interleukin(IL)-12 expression was estimated in c-kit⁺ mast cells and F4/80⁺ macrophages from wild type (WT) mice, some of which had been injected with lipopolysaccharide (LPS) 10 days after K/BxN serum transfer. (B and C) Macrophages from WT or Toll-like receptor (TLR)4^-/- mice were adoptively transferred into macrophage-depleted WT mice with antibody-induced arthritis. (D and E) Mast cells from WT or TLR4^-/- mice were adoptively transferred into mast cell-depleted WT mice with antibody-induced arthritis. (B and D) Ankle thickness and clinical scores were measured. (C and E) Interferon (IFN)-γ, transforming growth factor (TGF)-β, IL)-12p35, and IL-1β transcript levels in the joints 10 days after K/BxN serum transfer were measured by real-time PCR. The results shown are representative of three repeated independent experiments. n.s., not significant; * P < 0.05, ** P < 0.01, *** P < 0.001; B, C, D, and E, n = 3.