SOCS2 and DC Maturation Figure 4. SOC2 siRNA affects LPS inducible gene expression both in the MyD88-dependent and -independent signaling pathway. Enriched monocytes were cultured in the presence of GM- CSF and IL-4 for 6 days. iDCs were transfected with SOCS2 siRNA or control siRNA and incubated for 24 hours. Cells were further incubated with LPS (200 ng/ml) for additional 2 h. LPS inducible gene mRNA expressions were measured by real-time PCR. (A). LPS inducible gene expression of TNF-a, IL-6, IL-1b and CCL-4 via the MyD88-dependent signaling pathway. (B) LPS inducible gene expression of IFN-b, CXCL-9, CXCL-10 via the MyD88-independent signaling pathway. Data shown are the mean of triplicate sample, and are representative of at least two donors with similar results. Values for the control were set to 1. Error bars illustrate s.d. * P,0.05; ** P,0.01. doi:10.1371/journal.pone.0007178.g004 which targets p38MAP kinase [49] mention some of the possibilities. Obviously this is a complex problem that requires a careful examination in future studies. It is important to note that SOCS2 is known to have stimulatory activity on certain cytokine signaling pathways. It can increase the action of IL-6, an effects that has been attributed to SOCS2 reversing the inhibitory action Figure 5. Effect of SOCS2 siRNA in DC maturation. Enriched monocytes were cultured in the presence of GM-CSF and IL-4 for 6 days. iDCs were transfected with SOCS2 siRNA or control siRNA and incubated for 24 hours. Histograms showing the effect of SOCS2 knock- down on DC maturation. LPS (200 ng/ml) was added and were present for 24 hours. Afterwards, cells were harvested, stained, and analyzed by flow cytometry. The histogram shows changes of indicated surface molecules in DCs from the different groups. Matched isotype controls are presented as solid histograms. Percentage of positive cells is indicated in the upper right corner of each histogram. doi:10.1371/journal.pone.0007178.g005 of SOCS1 on IL-6 signaling [50]. This phenomenon may also affect the activity of cytokines produced during dendritic cell maturation that have a positive feed back on the process. Animal experiments support a role for SOCS2 in immune regulatory pathways. Mice where the SOCS2 gene has been ablated demonstrate an increased inflammation and mortality during T.gondii infection [27]. However, LPS treatment of splenic DCs of SOCS2 knock out mice did not influence proinflammatory PLoS ONE | www.plosone.org 5 September 2009 | Volume 4 | Issue 9 | e7178