Figure 6

Glucocorticoids enhance IL-1β-induced TLR2 up-regulation likely via upregulation of MKP-1. A, MKP-1 protein expression is induced by DEX and the MKP-1 induction is counteracted by RU486 in HeLa cells. HeLa cells were first treated with RU486 (10^-6 M) for 2 h and were then treated with DEX (10^-6 M) for 2 h. Protein level of MKP-1 was assessed by Western blot analysis. β-Actin was used as a protein loading control. B, Overexpression of wild-type MKP-1 inhibits IL-1β-induced p38 and JNK phosphorylation, whereas overexpression of MKP-1 mutant has almost no effect on IL-1β-induced p38 and JNK phosphorylation. Transfected HeLa cells were stimulated with IL-1β (10 ng/ml) for 20 min. IL-1β-induced phosphorylation of p38 MAPK and JNK was then assessed by Western blot analysis. C, Overexpression of wild-type MKP-1 enhances the IL-1β-induced TLR2 expression, whereas overexpression of MKP-1 mutant has almost no effect on the IL-1β-induced TLR2 expression in HeLa cells. Values are the mean ± SD; n = 3. The symbols indicate results significantly different (p < 0.01) from unstimulated condition (*) and IL-1β-stimulated condition (without MKP-1 construct)(**). D, Overexpression of wild-type MKP-1 enhances the IL-1β-induced TLR2 expression, whereas overexpression of MKP-1 mutant has almost no effect on the IL-1β-induced TLR2 expression in NHBE cells. Values are the mean ± SD; n = 3. The symbols indicate results significantly different (p < 0.01) from unstimulated condition (*) and IL-1β-stimulated condition (without MKP-1 construct)(**). For all of the TLR2 mRNA measurement, cells were treated with IL-1β (10 ng/ml) for 3 h.