Figure 5.

H. influenzae induction of ICAM-1 expression requires p38 MAP kinase. (A) ICAM-1 mRNA levels were determined using realtime RT-PCR analysis of total RNA from hTBE cells monolayers that were left untreated or were pretreated with a p38 inhibitor at the indicated concentrations. Cells were then incubated without or with H. influenzae for 8 hours. Values are expressed as mean mRNA level compared with control HPRT mRNA ± S.D. (n = 3), and a significant difference in mRNA levels compared with cells not treated with the inhibitor is indicated by an asterisk. Results are representative of three experiments. (B) ICAM-1 gene promoter activity was assessed using reporter gene assays with hTBE cells that were cotransfected with a reporter plasmid containing a luciferase gene driven by ICAM-1 gene sequence from −1294 to +7 and either no expression plasmid, a control expression plasmid, or plasmid that expressed dominant-negative p38 (DN) in the indicated amount. Cells were then incubated without or with H. influenzae for 18 hours. Values are expressed as mean luciferase level relative to uninfected cells ± SD (n = 4 experiments, each with duplicate samples), and a significant difference between levels in cells transfected with dominant-negative p38 compared with control is indicated with an asterisk.