Fig. 3.

Serine metabolism regulates macrophage polarization in vivo. a–c PHGDH-WT and PHGDH-KO mice were subcutaneously injected with 2 × 10⁶ LLC cells per mouse (n = 6). Tumor volume was calculated every 2 days beginning 4 days after cell inoculation (a). Tumor xenografts and tumor weights on the 21st day are shown (b). Immunofluorescence staining was performed with the indicated antibodies on tumor sections from PHGDH-WT and PHGDH-KO mice. Representative images are shown (c). Scale bars, 100 μm. Semiquantitative histological analysis was performed (10 fields of 5 biological replicates for each group). d–g Eosinophil populations in the peritoneal cavities of PHGDH-WT and PHGDH-KO mice (n = 4) were analyzed by flow cytometry 2 days post-chitin administration. The percentages of eosinophils among CD45⁺ cells (d, e) and the total numbers of eosinophils (f) are shown. The expression of Arg1 mRNA in isolated peritoneal macrophages was measured by qPCR (g). h–k Eosinophil populations in the peritoneal cavities of wild-type mice treated with or without CBR-5884 and/or SG starvation (n = 4) were analyzed as described above. Shown are the percentages of eosinophils among CD45⁺ cells (h, i) and the total numbers of eosinophils (j). The expression of Arg1 mRNA in isolated peritoneal macrophages was measured by qPCR (k). The data are shown as the mean ± SEM values (n = 6 in a and the right panel of b; n = 10 in the right panel of c; n = 4 in e–g and i–k) or are representative of four mice (d, h). *p < 0.05, **p < 0.01, ***p < 0.001