Caco-2 cocultured with THP-1, time course

Previously, we constructed a coculture model to analyze the effect of macrophages on intestinal epithelial cells, and found that TNF-a secreted from human macrophage-like THP-1 cells induced cell damage to intestinal epithelial Caco-2 cells (Exp.Cell.Res. 2006, 312(19):3909-19). In this study, we present activation of NF-kB in Caco-2 cells within 15 min after coculturing. To reveal how TNF-a secreted from THP-1 cells affects Caco-2 cells in an early stage of coculture, we exhaustively analyzed the changes of gene expression in Caco-2 cells cocultured with THP-1 cells over the time periods of 0, 1, 3, 6, 24, and 48 h by using a DNA microarray. Differentially expressed genes extracted with maSigPro demonstrated that IEX-1 was the lowest p-value gene, that is, the most significantly changed gene among the up-regulated genes. The genes expressed in a similar pattern to IEX-1 involved immunity, apoptosis, and protein kinase cascade. These findings suggest that the stimuli of TNF-a from THP-1 cells activates NF-kB, leading induction of various gene expression. This pattern of gene expression indicates that not only early defense response but also cell death occurs at the same time, causing inflammatory condition. Caco-2 cells were cultured for 14 days on a semi-permeable support, and THP-1 cells were differentiated with phorbol myristate acetate (PMA) for 4 days in 12-well plates. Then, the semi-permeable support membrane in which Caco-2 cells had been cultured was placed on the 12-well plates on which THP-1 has been cultured.