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Journal of Lipid Research, Vol. 46, 2134-2142, October 2005 10t,12c-conjugated linoleic acid inhibits lipopolysaccharide-induced cyclooxygenase expression in vitro and in vivo
* Molecular and Environmental Toxicology, University of Wisconsin-Madison, Madison, WI 53706 Published, JLR Papers in Press, August 1, 2005. DOI 10.1194/jlr.M500064-JLR200 1 Present address of D. Barnes: Standard Process, Inc., Palmyra, WI 53156.
2 To whom correspondence should be addressed. e-mail: mcook{at}wisc.edu
Previous data demonstrated that conjugated linoleic acid (CLA) reduced eicosanoid release from select organs. We hypothesized that one active CLA isomer was responsible for the reduced prostaglandin release and that the mechanism was through the inhibition of inducible cyclooxygenase-2 (COX-2). Here, we examined the effects of 10t,12c-CLA and 9c,11t-CLA on COX-2 protein/mRNA expression, prostaglandin E2 (PGE2) production, and the mechanism by which CLA affects COX-2 expression and prostaglandin release. The COX-2 protein expression level was inhibited 80% by 10t, 12c-CLA and 26% by 9c,11t-CLA at 100 µM in vitro. PGE2 production was decreased from 5.39 to 1.12 ng/2 x 106 cells by 10t,12c-CLA and from 5.7 to 4.5 ng/2 x 106 cells by 9c,11t-CLA at 100 µM. Mice fed 10t,12c-CLA but not 9c,11t-CLA were found to have a 34% decrease in COX-2 protein and a 43% reduction of PGE2 release in the lung. 10t,12c-CLA reduced COX-2 mRNA expression level by 30% at 100 µM in vitro and by 30% in mouse lung in vivo. Reduced COX-2 mRNA was attributable to an inhibition of the nuclear factor
These data suggested that the inhibition of NF-
Abbreviations: CLA, conjugated linoleic acid; COX, cyclooxygenase; EIA, enzyme immunoassay; G3PDH, glyceraldehyde-3-phosphate dehydrogenase; IL-l, interleukin-l; iNOS, inducible nitric oxide synthase; LA, linoleic acid; LPS, lipopolysaccharide; NF- Supplementary key words inflammation polyunsaturated fatty acid prostaglandin inducible nitric oxide synthase
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