Figure 3: Amelioration of DSS-induced colitis in CD169-DTR mice.

(a) Depletion and kinetics of recovery of CD169⁺ cells in the colon of DT-injected CD169-DTR mice. Top, numbers indicate frequencies of CD169⁺ cells among 7AAD⁻ myeloid cells enriched by magnetic sorting at indicated time points. Bottom, average frequencies of CD169⁺ (R1) and CD169⁻ cells (R2–R4, see Fig. 1c). Error bars mark s.d., n=3 mice, *P<0.05, one-way analysis of variance (ANOVA) with multiple comparison. (b) Injection of DT into CD169-DTR mice depletes CD64^hi, CD169⁺ but not CD64^hi, CD169⁻-resident macrophages. Left, numbers indicate frequencies of CD64^lo monocytes, CD64^int monocytes and CD64^hi-resident macrophages among 7AAD⁻ myeloid cells. Right, frequencies of CD169⁺ cells among Ly6C^lo, CD64^hi-resident macrophages. Shadow, isotype control. (c) Depletion of CD169⁺ macrophages protects mice from DSS-induced colitis. DT was injected on days −1 and 3. The average body weight change and s.e.m. of 4–6 mice. *P<0.05, two-way ANOVA with multiple comparison. Representative data of five independent experiments. (d) Macroscopic observation of colons on day 7. Representative images of 12 mice. (e) Left, haematoxylin and eosin staining of paraffin sections from naive (left) or colitis (right) WT (top) or CD169-DTR mice (bottom). Loss of goblet cells in WT day 7, but not in CD169-DTR day 7 colon (insets). Scale bar, 100 μm. Original magnification, × 20. (f) F4/80 staining of the colon on DSS day 5. Original magnification, × 20. Scale bars, 200 μm. Inset, diffuse infiltration of F4/80⁺ cells in the villi of WT colon. Original magnification, × 40. Scale bar, 20 μm. Right, average numbers and s.d. of F4/80⁺cells per high-power field (HPF). *P<0.05, Student’s t-test. Representative of two independent experiments. (g) Flow cytometry of colon myeloid cells from WT naive (top left), WT colitis (middle left) or CD169-DTR colitis (bottom left) mice. Numbers indicate frequencies among 7AAD⁻ myeloid cells. Representative data of four mice are shown. (h) Selective reduction of Ly6C^hi, CD64^lo and Ly6C^int, CD64^int monocytes in the colon LP of CD169-DTR colitis mice. Absolute numbers of infiltrating cells in g. Average numbers and s.d. of four mice. Eos: Siglec-F⁺ eosinophils, Neu: Ly6G⁺ neutrophils. *P<0.05, NS, not significant, one-way ANOVA. (g,h) Mice were injected with DT on days −1 and 3, and analysed on day 5.