Y Yu1, K Chadee. 1. Institute of Parasitology, McGill University, St-Anne de Bellevue, Quebec, Canada.
Abstract
BACKGROUND & AIMS: The mechanisms involved in the initiation of host mucosal inflammation in amebiasis are not fully understood. This study characterized the effect of Entamoeba histolytica components on interleukin 8 (IL-8) gene expression in human colonic cells. METHODS: Colonic cells were stimulated with amebic proteins, secretory components, or live trophozoites (separated with 0.45-microm pores), and the levels of IL-8 messenger RNA (mRNA) and protein were detected. RESULTS: Live amebae or their components enhanced IL-8 mRNA levels in the colonic cells (T84, LS174T, and Caco-2). In T84 cells, the accumulation of IL-8 mRNA induced by amebic components occurred in a dose- and time-dependent fashion. Increased secretion of IL-8 was noted after 12-hour stimulation; neutralizing antibodies against IL-15 or tumor necrosis factor alpha did not inhibit IL-8 production. Nuclear run-on assays showed that amebae-induced IL-8 gene occurred by a posttranscriptional mechanism. Cycloheximide treatment resulted in superinduction of IL-8 mRNA; however, dexamethasone inhibited E. histolytica-induced IL-8 gene expression. CONCLUSIONS: E. histolytica can directly stimulate the induction of IL-8 by colonic cells in the absence of cell-cell contact or injury.
BACKGROUND & AIMS: The mechanisms involved in the initiation of host mucosal inflammation in amebiasis are not fully understood. This study characterized the effect of Entamoeba histolytica components on interleukin 8 (IL-8) gene expression in human colonic cells. METHODS: Colonic cells were stimulated with amebic proteins, secretory components, or live trophozoites (separated with 0.45-microm pores), and the levels of IL-8 messenger RNA (mRNA) and protein were detected. RESULTS: Live amebae or their components enhanced IL-8 mRNA levels in the colonic cells (T84, LS174T, and Caco-2). In T84 cells, the accumulation of IL-8 mRNA induced by amebic components occurred in a dose- and time-dependent fashion. Increased secretion of IL-8 was noted after 12-hour stimulation; neutralizing antibodies against IL-15 or tumor necrosis factor alpha did not inhibit IL-8 production. Nuclear run-on assays showed that amebae-induced IL-8 gene occurred by a posttranscriptional mechanism. Cycloheximide treatment resulted in superinduction of IL-8 mRNA; however, dexamethasone inhibited E. histolytica-induced IL-8 gene expression. CONCLUSIONS:E. histolytica can directly stimulate the induction of IL-8 by colonic cells in the absence of cell-cell contact or injury.