G. Kolios et al., INTERLEUKIN-8 PRODUCTION BY THE HUMAN COLON EPITHELIAL-CELL LINE HT-29 - MODULATION BY INTERLEUKIN-13, British Journal of Pharmacology, 119(2), 1996, pp. 351-359
1 We have determined which cytokines induce and modulate the productio
n of the chemokine interleukin-8 (IL-8) by the human colonic epithelia
l cell line HT-29. 2 Growth arrested cell cultures were stimulated wit
h the human recombinant cytokines interleukin-1 alpha (IL-1 alpha), tu
mour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma),
interleukin-13 (IL-13), interleukin-10 (IL-10) or vehicle added alone
or in combination. The production of IL-8 was determined by enzyme-lin
ked immunosorbent assay (ELISA) and IL-8 messenger RNA expression by N
orthern blot analysis. 3 The production of IL-8 in unstimulated cells
was undetectable by both ELISA and Northern blot analysis. 4 HT-29 cel
ls produced IL-8 following stimulation with IL-1 alpha or TNF-alpha in
a time- and a concentration-dependent manner, while IFN-gamma, IL-10
and IL-13 did not induce IL-8 production by HT-29 cells. 5 IL-13 was f
ound to up-regulate significantly (P<0.01) the IL-1 alpha but not the
TNF-alpha-induced IL-8 generation by HT-29 cells. In contrast, IL-10 h
ad no effect on either IL-1 alpha or TNF-alpha-induced IL-8 production
. 6 Experiments using cycloheximide demonstrated that this synergistic
effect of IL-13 and IL-1 alpha on IL-8 secretion was not through de n
ovo protein synthesis. Using actinomycin-D, we demonstrated that the I
L-13 up-regulation was at the level of transcription rather than messe
nger RNA stability. 7 These findings suggest that colonic epithelial c
ells have a functional IL-13 receptor, which is coupled to an up-regul
ation of IL-1 alpha, but not TNF-alpha induced IL-8 generation.