Expression of Interleukin-26 is upregulated in inflammatory bowel disease

Figure 7 Involvement of nuclear factor-κB and AP-1 activation in the induction of inflammatory mediators induced by interleukin-26. A: Activation of NF-B and AP-1 (c-Jun) in response to IL-26 in human colonic SEMFs. The cells were stimulated with 100 ng/mL of IL-26 for 15 min, following which nuclear proteins were extracted and analyzed by immunoblotting for NF-κB (p65) and phosphorylated (P-) c-Jun. Lamin A/C was used as a loading control. The data are representative of two individual experiments; B: The effects of siRNAs specific for NF-κBp65 and c-Jun (AP-1) on IL-26-induced expression of IL-6 and IL-8 in human colonic SEMFs. The cells were transfected with siRNA specific for NF-κBp65, c-Jun (AP-1) or a control siRNA, and were incubated for 24 h with or without 100 ng/mL of IL-26. The mRNA expression of IL-6 and IL-8 was evaluated using real-time PCR. The mRNA expression of IL-6 and IL-8 mRNA was converted to a value relative to β-actin mRNA expression and presented as fold-increase relative to the results for medium alone (no stimulation). Data are expressed as mean ± SE of four independent experiments. ^aP < 0.05 vs IL-26 stimulation; C: The effect of MAPKs and PI3K/Akt on the activation of NF-κBp65 and c-Jun (AP-1). The cells were pretreated with 10 μmol/L of a p38 MAPK inhibitor (SB203580) or an MEK1/2 inhibitor (U0216 or PD098059), or with 3 μmol/L of a JNK inhibitor (JNK inhibitor I) or 25 μmol/L of a PI3K inhibitor (LY294002) for 30 min, and were then incubated with or without 100 ng/mL of IL-26 for 15 min. Nuclear proteins were then extracted and analyzed by immunoblotting for NF-κBp65 and phosphorylated (P-) c-Jun. Lamin A/C was used as a loading control. The data are representative of two individual experiments. IL: Interleukin.