Figure 8.

GDF15 enhances Treg‐mediated suppression of T‐cell activation via IL‐10 production in Tregs. (a) Treg‐mediated suppression of the activation (% of suppression of CD25⁺ T cells) of CD4⁺ T cells stimulated with anti‐CD3 (2 μg/mL)/CD28 (5 μg/mL) in the absence or presence of different concentrations of recombinant GDF15 for 72 hr. (b–e) IFN‐γ levels in supernatants from co‐culturing WT or IL‐10‐deficient Tregs with CD4⁺ T cells stimulated by anti‐CD3 (2 μg/mL)/CD28 (5 μg/mL) at the indicated concentrations of recombinant GDF15 for 72 hr. (f) IL‐10 KO Treg‐mediated suppression of the activation (% of suppression of CD25⁺ T cells) of CD4⁺ T cells in the absence or presence of several concentrations of recombinant GDF15 for 72 hr. (g–j) IL‐10 KO Treg‐mediated suppression of IFN‐γ production of CD4⁺ T cells in the absence or presence of several concentrations of recombinant GDF15 for 72 hr. (k) Population of senescent CD8⁺ T cells in young (≤40) and elderly (≥60) human subjects. (l) IFN‐γ or TNF‐α production from senescent CD8⁺ T cells in the absence or presence of several concentrations of recombinant GDF15 for 48 hr. Data are expressed as mean ± SEM. *p < 0.05, **p < 0.01 ((a–h): one‐way ANOVA, (k): two‐tailed t tests, (i–l): one‐way ANOVA)