Arginase-1–dependent synthesis of polyamines is important for IL-4–mediated Cdh1 induction in mouse macrophages. (A) BALB/c thio-PEMs were stimulated for 24 hours with indicated cytokines. The fold Arg1 induction relative to the expression in untreated macrophages (= 1) is shown (left y-axis). Intracellular polyamine concentrations were determined and shown as pmol/5 × 106 macrophages (right y-axis). (B) thio-PEMs were pretreated for 24 hours with DFMO or DENSPM, and after an additional 24 hours of IL-4 stimulation, intracellular polyamine concentrations were measured and plotted relative to the polyamine levels in nondepleted IL-4–treated macrophages (100%). (C) Same as panel B, with or without 10μM putrescine (PUT) or spermine (SPM) supplementation. The fold Cdh1 induction in polyamine-depleted IL-4–treated thio-PEM is shown relative to the induction level in IL-4–treated thio-PEMs (100%). Values represent the mean ± SEM of 3 mice. **P < .01. ***P < .001. ns indicates not significant.
