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Erschienen in:
01.09.2004 | Original Article
Interferon gamma downregulates IL-8 production in primary human colonic epithelial cells without induction of apoptosis
Erschienen in: International Journal of Colorectal Disease | Ausgabe 5/2004
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Background
In acute or chronic inflammatory bowel disease (IBD) interferon gamma (IFNγ) is still considered to be an important pro-inflammatory mediator. In the present study we investigated the impact of IFNγ on interleukin-8 (IL-8) production as a read-out for cell activation in intestinal epithelial cell (IEC) lines and primary human colonic epithelial cells (CEC).
Methods
Primary cultures of human CEC were established from the mucosa of patients without inflammatory disease. CEC, HT-29 or Caco-2 cells were incubated with either IFNγ, tumor necrosis factor (TNF)α or IL-10. IL-8 and IL-1Ra secretion was determined by ELISA. Competicon PCR was used for quantification of IL-8mRNA. Apoptosis was quantified by propidium iodine incorporation and fluorescence activated cell sorting (FACS) analysis.
Results
In contrast to HT-29 cells in primary human CEC 100 U/ml IFNγ inhibited IL-8 secretion significantly to 70±15% of unstimulated primary CEC (p<0.005) more effectively than IL-10 (87±21% versus unstimulated cells, n.s.). In HT-29 cells, IL-8 secretion was induced to 405±101% of unstimulated cells. In Caco-2 cells, IFNγ had no significant effect on IL-8 secretion. The effect in HT-29 and CEC was concentration dependent. In primary CEC, 200 U/ml IFNγ further reduced IL-8 secretion to 48±18% of unstimulated CEC (p<0.05). Whereas IL-8 mRNA was strongly upregulated in HT-29 cells, no upregulation or even a downregulation was found in CEC. Pre-incubation with 100 U/ml IFNγ did not increase the susceptibility to apoptosis mediated by anti-Fas antibody (CH-11) in primary CEC, whereas HT-29 cells showed increased rates of apoptosis after priming with IFNγ.
Conclusion
In contrast to HT-29, IFNγ downregulated IL-8 secretion and did not induce IL-8 mRNA expression in primary human CEC. This effect was not due to induction of apoptosis.