Figure 5
Glucocorticoids synergistically enhance IL-1β-induced TLR2 up-regulation via negative cross-talks with MAPK p38 and JNK1/2 pathways. A, Dexamethasone (DEX) synergistically enhances IL-1β-induced TLR2 up-regulation and RU486 counteracts the enhancing effect of DEX on IL-1β-induced TLR2 up-regulation at mRNA level in HeLa cells. HeLa cells were first pretreated with RU486 (10-6 M) for 2 h and were then treated with DEX (10-6 M) for 2 h. The cells were stimulated with IL-1β (10 ng/ml) for 3 h, and the TLR2 mRNA levels were then assessed by real-time quantitative PCR. Values are the mean ± SD; n = 3. The symbols indicate results significantly different (p < 0.01) from unstimulated condition (*) and IL-1β-DEX-stimulated condition (without RU486)(**). B, DEX (10-6 M) synergistically enhances IL-1β-induced TLR2 up-regulation and RU486 (10-6 M) counteracts the enhancing effect of DEX on IL-1β-induced TLR2 up-regulation at mRNA level in NHBE cells. Cells were first pretreated with RU486 (10-6 M) for 2 h and were then treated with DEX (10-6 M) for 2 h. The cells were stimulated with IL-1β (10 ng/ml) for 3 h, and the TLR2 mRNA levels were then assessed. Values are the mean ± SD; n = 3. The symbols indicate results significantly different (p < 0.01) from unstimulated condition (*) and IL-1β-DEX-stimulated condition (without RU486)(**). C, Glucocorticoids also synergistically enhance the induction of TLR2 at protein level in HeLa cells. HeLa cells were first treated for 2 h with DEX (10-6 M). The cells were then stimulated with IL-1β (10 ng/ml) for 5 h. Protein level of TLR2 was assessed by Western blot analysis using an anti-hTLR2 antibody. β-Actin was used as a protein loading control. D, DEX inhibits IL-1β-induced phosphorylation of p38, but not MKK3/6, and the inhibitory effect of DEX is blocked by RU486. 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. The cells were stimulated with IL-1β (10 ng/ml) for 20 min. IL-1β-induced phosphorylation of p38 MAPK and MKK3/6 was then assessed by Western blot analysis. E, DEX inhibits IL-1β-induced phosphorylation of JNK, but not MKK4, and the inhibitory effect of DEX is blocked by RU486. 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. The cells were stimulated with IL-1β (10 ng/ml) for 20 min.