TNF pretreatment of Salmonella contributes to enhanced IL-8 mRNA and proteins in human intestinal epithelial cells. Cells were cultured in DMEM, followed by Salmonella-containing HBSS for 30 min, washed 3 times in HBSS, and incubated at 37°C for 6 hours. Total RNA was extracted for real-time PCR. Cell supernatants were removed and assayed for IL-8 by ELISA. (A) IL-8 mRNA levels in the HCT116 cells after colonization with TNF-pretreated Salmonella. (B) IL-8 protein secreted into the cell culture media in the HCT116 cells after Salmonella infection. (C) IL-8 protein secreted into the cell culture media in the HCT116 cells after Salmonella infection. HCT116 cells were pretreated with a JNK inhibitor SP600125 (50 μM). In a single experiment, samples were assayed in triplicate. The data are reported as mean ± SD of three independent experiments. *P < 0.05 was considered significant.