Synergy between Entamoeba histolytica and Escherichia coli in the induction of cytokine gene expression in human colon epithelial cells.

Entamoeba histolytica induces the expression and secretion of interleukin 8 (IL-8) by cultured colon epithelial cells. We assessed the array of cytokine genes expressed by human colon epithelial cells in response to co-culture with E. histolytica trophozoites and tested the hypothesis that enteric bacteria may alter the E. histolytica-induced expression of such genes. HT-29 colon epithelial cells were co-cultured with E. histolytica trophozoites in the presence or absence of Escherichia coli. Cytokine gene expression was assessed by quantitative reverse-transcription polymerase chain reaction (RT-PCR). IL-8 mRNA in colon epithelial cells was up-regulated following exposure to E. histolytica and this was paralleled by increased IL-8 secretion. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-1alpha/beta mRNAs were also up-regulated in these cells. When HT-29 cells were co-cultured with E. coli DH5alpha and E. histolytica there was a synergistic increase in the expression of IL-8, IL-1alpha, and GM-CSF. These results suggest that enteric bacteria may significantly affect early proinflammatory signals produced in host tissues in response to E. histolytica infection.