Figure 2: Effect of MUC18 over-expression (OE) on IL-8 protein levels in cultured normal human primary tracheobronchial epithelial (NHTE) cells. Cells were transduced with MUC18 cDNA or green fluorescence protein (GFP) gene (control) encoded in replication-deficient lentivirus. After 72 hours of transduction, cells were stimulated with polyI:C (10 μg/ml) for 4 and 24 hours. (A) IL-8 fold changes in polyI:Cstimulated NHTE cells with or without MUC18 over-expression (MUC18 OE). MUC18 OE cells, as compared to non-OE cells, show greater IL-8 induction (fold change over cells without polyI:C) following polyI:C treatment at 24, but not 4 hours. Data are expressed as means ± SEM. N=4 human donors. (B) Net changes of IL-8 after polyI:C stimulation in NHTE cells with or without MUC18 OE. At 24 hours, MUC18 OE significantly increases IL-8 levels in supernatants of polyI:C-treated cells. This trend exists at 4 hours, but is not statistically significant. N=4 human donors. The horizontal bars indicate means.