IL-27 inhibits the development of regulatory T cells via STAT3

Abstract

Regulatory CD4+ T cells are important for the homeostasis of the immune system and their absence correlates with autoimmune disorders. Here, we investigate the capacity of IL-27, a cytokine with pro- and anti-inflammatory properties, to regulate the generation of transforming growth factor beta (TGFbeta)-inducible forkhead box P3 (Foxp3)-positive regulatory T (Treg) cells. Our results demonstrate that IL-27 inhibits the acquisition of the Treg phenotype at the level of Foxp3, CD25 and CTLA-4 (CD152) expression as well as the suppressive function. In contrast to TGFbeta-induced Treg cells, the cells generated after differentiation in the presence of TGFbeta and IL-27 maintained the ability for IL-2 and tumour necrosis factor alpha (TNFalpha) production. The inhibitory effect of IL-27 on Treg generation was at least partially signal transducer and activator of transcription 3 (STAT3) dependent as examined by targeted STAT3 protein inhibition using small interfering RNA (siRNA), while STAT1-dependent signals seemed to oppose the STAT3 signals. In turn, TGFbeta blocked IL-27-induced T(h)1 differentiation. Thus, IL-27 and TGFbeta mutually control their effects on CD4+ T-cell differentiation, whereby IL-27 favours inflammatory conditions through a STAT3-dependent inhibition of Treg generation.

c‐Rel is crucial for the induction of Foxp3+ regulatory CD4+ T cells but not TH17 cells

“…Foxp3-expressing cells were detected by using the Foxp3 staining kit (anti-Foxp3-PE, FJK, FJK-16s, eBioscience). In some experiments, the amounts of IL-2 secreted by activated cells were measured by ELISA (BD), as described earlier [32].…”

“…For the IRF-4 immunoblots, whole-cell lysates were prepared as described earlier [32]. In brief, phosphatase inhibitors (0.2 mM sodium vanadate, 10 mM sodium fluoride) and 1 Â complete protease inhibitor (Roche Applied Science) were added into RIPA lysis buffer.…”

IRF4 is essential for IL-21-mediated induction, amplification, and stabilization of the Th17 phenotype

“…Levels of each gene were normalized to Hprt1 expression using the ⌬⌬Ct method. The primer sets and probes for Ifng, Il21, Il23r, Rora, Rorc, and Socs3 were previously described (7,12,16,18,33).…”

“…The siRNAs were designed as described (34) and prepared by IBA. Nucleofection was performed as described (33), then the cells were cultured under the conditions indicated in the experiments. The sequences of the siRNAs were previously described (18).…”

“…For the phospho-STAT3 (pSTAT3) and IRF4 immunoblots, whole-cell lysates were prepared as described (33). To study pSTAT3 and NFATc2 translocation, nuclear extracts were made as described (35).…”