Figure 7. Increased Arg1 in Fra-1–deleted macrophages from arthritic joints.

K/BxN arthritis was induced in Fra-1 mutant mice and their respective control mice. Healthy or arthritic mice were analyzed 10 days after serum transfer. (A) Arg1 mRNA levels were determined in paws of healthy, arthritic control and Fra-1 mutant mice (Fra-1^ΔMx, Fra-1^ΔMx→WT, and Fra-1^ΔLysM). (B) The concentrations of ʟ-arg and ʟ-ornithine in paw lysates of Fra-1^ΔMx and control littermate mice were analyzed by HPLC. (C) Arg-1 mRNA levels in stromal cells (CD11b^–), neutrophils (CD11b⁺Ly6G⁺), monocytes (CD11b⁺Ly6C⁺), and macrophages (CD11b⁺F4/80⁺) sorted from arthritic Fra-1^ΔMx, Fra-1^ΔLysM, and control littermate mice. (D) Intracellular Arg1 protein levels observed as MFI in neutrophils, monocytes, and macrophages isolated from healthy control or arthritic joints of WT, Fra-1^ΔMx, and Fra-1^ΔLysM mice. Shown are ΔMFI as compared with unstained and normalized to healthy controls of each respective cell type. A representative histogram of MFI is shown for macrophages from healthy control mice, arthritic control mice, and arthritic Fra-1^ΔMx mice. Graph points indicate individual mice. Data are shown as mean values, and error bars represent SEM. *P < 0.05; **P < 0.01; ***P < 0.001, ANOVA.