Interleukin-13 inhibits nitric oxide production in human colonic mucosa.
OBJECTIVE
Nitric oxide synthesis is increased in rectal biopsies from patients with ulcerative colitis and colonic epithelial cells are considered to be a major source of nitric oxide in intestinal inflammation.


METHODS
Human colonic biopsies from normal bowel mucosa and colonic epithelial cell line HT-29 were cultured in the presence of the inflammatory cytokines IL-1 alpha + TNF-alpha + IFN-alpha added after 1 hour pretreatment with vehicle or Interleukin-13. Nitrite levels were determined at 30 hours in culture supernatants by a fluorometric assay.


RESULTS
Unstimulated human colonic biopsies and HT-29 cells produced a basal amount of nitrite. Stimulation with IL-1 alpha + TNF-alpha + IFN-alpha induced a significant (P < 0.001) increase of nitrite generation by both human colonic biopsies and HT-29 cells. The presence of Interleukin-13 produced a significant (P < 0.001) suppression of the cytokine-induced nitrite generation from both colonic biopsies and HT-29 cells.


CONCLUSIONS
Nitric oxide generation in human colonic mucosa is susceptible to manipulation by proinflammatory cytokines. Interleukin-13 has an inhibitory effect on cytokine induced nitrite production in colonic mucosa and could play an anti-inflammatory role in intestinal inflammation.
Kolios
G
G
Department of Pharmacology, University of Bath, UK.
Wright
K L
KL
Linehan
J D
JD
Robertson
D A
DA
Westwick
J
J
D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D003106:Colon / Q000378:metabolism*; D005260:Female; D006801:Humans; D018793:Interleukin-13 / Q000502:physiology*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II
D018793:Interleukin-13; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II