ENTAMOEBA-HISTOLYTICA STIMULATES INTERLEUKIN-8 FROM HUMAN COLONIC EPITHELIAL-CELLS WITHOUT PARASITE-ENTEROCYTE CONTACT

Background & Aims: The mechanisms involved in the initiation of host m ucosal inflammation in amebiasis are not fully understood, This study characterized the effect of Entamoeba histolytica components on interl eukin 8 (IL-8) gene expression in human colonic cells. Methods: Coloni c cells were stimulated with amebic proteins, secretory components, or live trophozoites (separated with 0.45-mu m pores), and the levels of IL-8 messenger RNA (mRNA) and protein were detected. Results: Live am ebae or their components enhanced IL-8 mRNA levels in the colonic cell s (T84, LS174T, and Caco-2), In T84 cells, the accumulation of IL-8 mR NA induced by amebic components occurred in a dose- and time-dependent fashion, Increased secretion of IL-8 was noted after 12-hour stimulat ion; neutralizing antibodies against IL-1 beta or tumor necrosis facto r alpha did not inhibit IL-8 production, Nuclear run-on assays showed that amebae-induced IL-8 gene occurred by a posttranscriptional mechan ism, Cycloheximide treatment resulted in superinduction of IL-8 mRNA; however, dexamethasone inhibited E. histolytica-induced IL-8 gene expr ession. Conclusions: E. histolytica can directly stimulate the inducti on of IL-8 by colonic cells in the absence of cell-cell contact or inj ury.