Author + information
Interleukin-35 (IL-35) was identified as a novel anti-inflammatory cytokine composed of IL-12p35 (p35) and Ebi3. We hypothesized that IL-35 is a potent inhibitory cytokine that regulates dendritic cell (DC) maturation and subsequently increases regulatory T cells.
Bone marrow-derived DCs were cultured for 7 days in the presence of IL-4 and GM-CSF to obtain immature DCs and then treated with LPS, TNF-α, IFN-γ or IL-1 for 24h. An ELISA assay kit was used to detect the expression levels of IL-12 cytokine family. The expression levels of IL-12p35 and Ebi3 mRNA were detected by qRT-PCR in DCs. DCs were treated with exogenous IL-35/Ebi3 or Ebi-3 neutralizing antibody for 24h before stimulation with LPS. The mature DC subtypes (CD80,CD86,MHC-II) were analyzed using flow cytometry. DCs were harvested and co-cultured with splenocytes. The T cells were incubated with CD4+, CD25+, and Foxp3+ antibodies or CD4+ and IL-17A+ antibodies. T cells were detected using flow cytometry. STAT activation in differently treated DCs was analyzed by Western blotting. DCs were transfected with a miR-let-7i mimic or an inhibitor or si-SOCS1 (60 nM), the expression levels of SOCS1 and IL-12 family were then detected.
Here, we showed that IL-35 expression was significantly increased in a time-dependent manner in mouse mature dendritic cells (mDCs) stimulated by lipopolysaccharide (LPS) but not by TNF-α, IFN-γ and IL-1.Recombinant IL-35 suppressed DC maturation after stimulation by LPS and increased the secretion of anti-inflammatory cytokines. Co-culturing IL-35-treated DCs with T cells significantly increased the population of CD4+CD25+Foxp3+ T cells. IL-35 may activate STAT1, STAT3 and STAT4 in DCs to achieve its biological function.MicroRNA let-7i (miR-let-7i), as the prototype of the miR-let-7 family, could inhibit IL-35 expression by targeting suppressor of cytokine signaling 1 (SOCS1).
IL-35 expression was significantly increased in LPS-induced DC maturation.Exogenous IL-35 can regulate the maturation and function of DCs.MiR-let-7i regulates IL-35 secretion in DCs by targeting SOCS1.Collectively, our data show that IL-35-treated DCs may be a promising approach to regulate immunity.