Fish oil decreases macrophage tumor necrosis factor gene transcription by altering the NF kappa B activity.
BACKGROUND
Fish oil-supplemented diets have anti-inflammatory and immunomodulating effects, though the exact mechanism(s) are unknown. This study investigated the effects of eicosapentanenoic acid (EPA), a major component of fish oil, on transcriptional regulation of tumor necrosis factor (TNF) gene in lipopolysaccharide (LPS)-stimulated macrophages (MO).


METHODS
RAW 264.7 cells, a mouse MO cell line, were grown in EPA-rich media for 24-48 h. MO were washed and exposed to Escherichia coli LPS (1 microg/ml) for 2 h. TNF mRNA expression was measured by Northern blot assays. Total nuclear extracts were harvested for the measurement of NF kappa B with electrophoretic mobility shift assays. Supershift assays were performed with anti-P50 or anti-P65 antibodies to show components of NF kappa B dimers. TNF production was determined by L929 bioassays.


RESULTS
LPS stimulated RAW cell TNF mRNA expression and NF kappa B activity. In contrast, RAW cells grown in EPA-rich media had less TNF mRNA expression and an altered composition of the NF kappa B subunits (P65/P50 dimers) in the presence of LPS. TNF production by LPS-stimulated MO was reduced by EPA.


CONCLUSIONS
The inhibitory effect of EPA on LPS-stimulated MO TNF gene transcription and protein elaboration is, in part, mediated through altering NF kappa B activation by reducing the P65/P50 dimers.
Lo
C J
CJ
Department of Surgery, University of California, Los Angeles, California, 90095, USA. clo@surgery.medsch.ucla.edu
Chiu
K C
KC
Fu
M
M
Lo
R
R
Helton
S
S
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D015118:Eicosapentaenoic Acid / Q000494:pharmacology*; D004926:Escherichia coli; D005227:Fatty Acids / Q000378:metabolism; D005395:Fish Oils / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D016328:NF-kappa B / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*
D005227:Fatty Acids; D005395:Fish Oils; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015118:Eicosapentaenoic Acid