Entamoeba histolytica stimulates interleukin 8 from human colonic epithelial cells without parasite-enterocyte contact.
OBJECTIVE
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.
Yu
Y
Y
Institute of Parasitology, McGill University, St-Anne de Bellevue, Quebec, Canada.
Chadee
K
K
D000818:Animals; D002450:Cell Communication; D002460:Cell Line; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004748:Entamoeba histolytica / Q000378:metabolism / Q000502:physiology*; D005938:Glucocorticoids / Q000494:pharmacology; D006790:Host-Parasite Interactions; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D005938:Glucocorticoids; D007375:Interleukin-1; D016209:Interleukin-8; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D003513:Cycloheximide