FIG. 6.

LPS-induced IL-8 promoter transactivation was eliminated by NAC and DMSO. To assess if antioxidants could block transactivation of the IL-8 gene, IL-8 promoter reporter constructs were transfected into HEK293 cells expressing TLR4 or not. Cells were incubated with various antioxidants and then treated with 10 μg of LPS per ml for 4 h. The IL-8 promoter construct was not transactivated by LPS in cells lacking TLR4 (open bars). (A) Full-length IL-8 promoter transactivation in TLR4-expressing HEK293 cells (solid bars) or non-TLR4-expressing cells (open bars). (B) Truncated IL-8 promoter (lacking an AP-1 binding site) transactivation in TLR4-expressing HEK293 cells (solid bars) or non-TLR4-expressing cells (open bars). Transactivation was not dependent on the presence of an AP-1 binding site. Data are expressed as the means ± standard error of the mean of three independent experiments carried out in triplicate. Statistical differences between LPS alone and LPS plus antioxidant samples are indicated; *, an overall P value of ≤0.05, as determined with the Wilcoxon test with an adjusted Bonferroni correction.