Figure 4. IL-6 and IL-21 promote Areg expression through activation of Stat3 in CD4+ T cells.

(A) CD4⁺T cells were cultured under Th17-polarization conditions with or without the RORγt inhibitor. Areg expression was detected by qRT-PCR. (B) CD4⁺T cells were cultured with or without 10 ng/ml IL-6, 10 ng/ml IL-23, or 10 ng/ml IL-1β for 5 days. Areg expression was detected by qRT-PCR. (C) CD4⁺T cells were cultured with IL-6 alone or together with IL-23 and IL-1β for 5 days. Areg expression was detected by RT-PCR. (D) CD4⁺T cells were cultured with 10 ng/ml IL-6 for indicated days. Areg expression was detected by qRT-PCR. (E) CD4⁺T cells were cultured with IL-6 at indicated dose for 5 days. Areg expression was detected by qRT-PCR. (F) CD4⁺T cells were cultured in the presence of IL-17 or IL-21 for 5 days. Areg expression was detected by qRT-PCR. (G) CD4⁺T cells were cultured with or without IL-6 and IL-21 for 5 minutes. Phosphorylated Stat3 and total Stat3 were detected by western blot. (H-I) CD4⁺T cells were isolated from Stat3^−/− mice and treated with IL-6 or IL-21 for 5 days. Areg expression was detected by qRT-PCR. Representative data from 2–3 independent experiments with similar results. (A, D, H, and I) Unpaired Student’s t-test; (B, C, F, and G) one-way ANOVA. *p < .05; **p < .01; ***p < .001.