Dexmethasone augments Der-p2-induced MKP-1-regulated TLR4/MD2 expressions and B cell proliferation.

In A, B cells (CESS) or primary B cells transfected with siRNA-MKP-1 or control siRNA (scrambled) were treated with Der-p2 for 24 h in the presence or absence of dexamethasone (Dex, 20 µM). TLR4/MD2 protein expressions were determined by Western blotting. Bacterial lipopolysaccharide or PMA were used as a positive control. B, B cells (CESS) were treated with Der-p2 (5 µg/ml) for 72 hours in the presence or absence of dexamethasone (Dex, 20 µM) or neutralizing Der-p2-antibody (B/N-Der-p2-Ab, 20 µg/ml), and then the cell proliferation was determined by [3H]-thymidine incorporation assay. Data are presented as mean±SEM (n = 5). In C, the efficiency of transfection in B cells was nearly 90%. In D, Der-p2 activates NFκB activity in human B cells. Human B cells from AD patient or CESS were transiently transfected with the NFκB-luciferase reporter plasmid constructs. NFκB activity was detected 24 hours after treatment with Der-p2 (5 µg/ml) in the presence or absence of N-acetylcysteine (NAC, 2 and 5 mM) or pyrrolidinedithiocarbamate (PDTC) (10 µM). In E, transfected B cells were treated with Der-p2 (5 µg/ml) for 24 hours in the presence or absence of dexamethasone (Dex, 20 µg/ml). Data are presented as mean±SEM (n = 5). # p<0.05 vs. control group.