Nitric oxide inhibits LPS-induced IL-6 production in enterocytes.
In recent studies, production of interleukin-6 (IL-6) in cultured enterocytes was stimulated by lipolysaccharide (LPS). In other cell types, IL-6 production was inhibited by nitric oxide (NO). We tested the hypothesis that LPS-induced IL-6 production in the enterocyte is regulated, at least in part, by NO. IEC-6 cells (a rat intestinal epithelial cell line) were cultured for 3 days with different combinations of LPS (1-10 micrograms/ml), the NO synthase inhibitor N-omega-nitro-L-arginine (NNA, 3-300 microM), L-arginine (10 mM), the NO donor sodium nitroprusside (SNP, 0.5-1 microM), or medium alone as control. IL-6 levels in the culture medium were determined by the B9 murine hybridoma bioassay. Nitrite, a stable end product of NO metabolism, was measured by HPLC. PCR was performed to determine inducible NO synthase (iNOS) mRNA expression in the IEC-6 cells. Treatment of IEC-6 cells with LPS stimulated IL-6 production. LPS-induced IL-6 production was further increased by NNA in a dose-dependent fashion. This effect of NNA was abolished by the addition of L-arginine. SNP caused a dose-dependent decrease in IL-6 production. Nitrite production was increased in a dose-dependent fashion after LPS treatment. PCR revealed an increase in iNOS mRNA expression in IEC-6 cells after administration of 1 microgram/ml LPS. The results suggest that NO inhibits LPS-induced IL-6 production in the enterocyte. NO may be an important regulator of intestinal cytokine response during sepsis and endotoxemia.
Meyer
T A
TA
Department of Surgery, University of Cincinnati Medical Center, Ohio, USA.
Tiao
G M
GM
James
J H
JH
Noguchi
Y
Y
Ogle
C K
CK
Fischer
J E
JE
Hasselgren
P O
PO
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology*; D019335:Nitroarginine; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats
D015850:Interleukin-6; D008070:Lipopolysaccharides; D009599:Nitroprusside; D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D015232:Dinoprostone