Figure 6. IL-1β–reprogrammed Tregs contribute directly to bone injury under arthritic conditions.

(A and D) BALB/c WT mice were injected with 75 μL i.p. K/BxN serum on days 0 and 2. Sorted CD4⁺Foxp3^eGFP+ cells from the lymph nodes of WT (n = 5) or Il1rn^–/– (n = 5) mice or FOXP3^eGFP+ iTreg cells differentiated with or without IL-1β (n = 5) (or an equal volume of PBS n = 5) were transferred into BALB/c WT recipient mice 1 day before K/BxN serum injection. (A) Arthritis score (0–3/per paw, 0–12 total) and (B) ankle and wrist thickening measured by calipers was followed for 14 days after K/BxN injection. (C) High-resolution micro-computed tomography (μCT) imaging of wrists from BALB/c WT recipient mice 14 days after K/BxN injection. (D) Bone erosion score (0–3 total). Data are expressed as mean ± SEM. Statistical significance was determined using 1-way ANOVA (A and B) or Mann-Whitney U test (D).