FIG. 4.

Flagellin stimulates NF-κB and IL-8 production by TLR5-transfected HEK293T cells. (A) HEK293T cells were cotransfected with a TLR5 expression plasmid or pcDNA empty vector plus the pGL4.32 plasmid containing NF-κB response elements linked to a firefly luciferase reporter gene and the pRL-SV40 plasmid encoding Renilla luciferase, the cells were incubated for 24 h and treated for 6 h with the indicated concentrations of PAK flagellin or the negative control, and relative luciferase activity in cell lysates was determined. (B) HEK293T cells were transfected with the TLR5 plasmid or pcDNA vector, incubated for 24 h, and treated for 6 h with 10 ng/ml of flagellin, and IL-8 levels in culture supernatants were measured by ELISA. Each bar represents the mean ± SD (n = 3). *, significantly increased IL-8 levels comparing flagellin- and negative control-treated cells (P < 0.05).