10t,12c-conjugated linoleic acid inhibits lipopolysaccharide-induced cyclooxygenase expression in vitro and in vivo

Abstract

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 E 2 (PGE 2 ) 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 M in vitro. PGE 2 production was decreased from 5.39 to 1.12 ng/2 ؋ 10 6 cells by 10t,12c-CLA and from 5.7 to 4.5 ng/2 ؋ 10 6 cells by 9c,11t-CLA at 100 M. 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 PGE 2 release in the lung. 10t,12c-CLA reduced COX-2 mRNA expression level by 30% at 100 M in vitro and by 30% in mouse lung in vivo. Reduced COX-2 mRNA was attributable to an inhibition of the nuclear factor B (NF-B) pathway by 10t,12c-CLA. These data suggested that the inhibition of NF-B was one of the mechanisms for the reduced COX-2 expression and PGE 2 release by 10t,12c-

miR-27b*, an oxidative stress-responsive microRNA modulates nuclear factor-kB pathway in RAW 264.7 cells

“…NF-kB p65 nuclear translocation assay To determine nuclear translocation of p65 subunit of NFkB, TransAM NF-kB transcription factor assay was used as described previously [21,22]. RAW 264.7 cells were transfected with or without miR-27b* mimics or scrambled miRNAs (control mimics) as above, and the cells were plated in 6-well plates for 24 h. The cells were then treated with LPS for 6 h and the nuclear fractions were used for evaluating the translocation of p65 subunit of NF-kB by colorimetric reaction according to the manufacturer's recommendations (Active Motif, California).…”

A mechanistic approach to understanding conjugated linoleic acid's role in inflammation using murine models of rheumatoid arthritis

“…It is anticipated that the response of mice to individual isomers may be different than what is presented in this study. However, since each isomer alone (c9, t11-CLA affects TNF and t10, c12-CLA affects COX-2) has an effect on inflammatory mediators involved in arthritis (24,56), it was decided that a study of commercially available sources of CLA should be studied and reported.…”

“…COX-2 such as peroxisome proliferator-activated receptor ␥ (PPAR␥) (58), NF-B (2,24), and MAPK (25,41) have been implicated to be affected by CLA.…”

CLA Reduces Inflammatory Mediators from A427 Human Lung Cancer Cells and A427 Conditioned Medium Promotes Differentiation of C2C12 Murine Muscle Cells

“…COX-2 is the pro-inflammatory COX isoform, and is the rate-limiting enzyme in the synthesis of prostaglandin PGE2 from arachidonic acid, one of many fatty acids in the phospholipids of cell membranes [29].…”