Inhibition of cytokine-induced IkappaB kinase activation as a mechanism contributing to the anti-atherogenic activity of tilianin in hyperlipidemic mice.
Tilianin has been shown to down-regulate TNF-alpha induced expression of vascular cell adhesion molecules in endothelial cells. In this study, we examined the anti-atherogenic effects and molecular mechanism of tilianin in vitro and in vivo. Male low-density lipoprotein receptor null mice (Ldlr-/-) fed a high cholesterol diet showed significant increases in the size of atherosclerotic lesions, as well as increased plasma levels of total cholesterol, triglycerides, and the pro-inflammatory cytokines TNF-alpha and IL-1beta, when compared with Ldlr-/- mice fed a normal diet. Mice fed the high cholesterol diet supplemented with tilianin showed significantly reduced lesion sizes and reductions in cytokine levels, without significant changes in serum cholesterol levels. Primary cultured peritoneal macrophages from Ldlr-/- mice showed increased level of TNF-alpha andIL-1beta mRNA in response to treatment with lipopolysaccharide; these increases were inhibited by co-treatment with tilianin. Moreover, tilianin inhibited NF-kappaB activation, as determined by electrophoretic mobility shift and NF-kappaB promoter assays. Upstream of NF-kappaB activation, tilianin inhibited IkappaB kinase activation and the subsequent phosphorylation and degradation of IkappaBalpha protein. These results suggest that tilianin ameliorates atherosclerosis by inhibiting the production of the NF-kappaB-dependent pro-inflammatory cytokines, TNF-alpha and IL-1beta, via the inhibition of IkappaB kinase activity.
Nam
Kung-woo
KW
Natural Products Research Institute, Seoul National University, Seoul 110-460, South Korea.
Kim
Jiyun
J
Hong
Jung-Joo
JJ
Choi
Jae-Hoon
JH
Mar
Woonchon
W
Cho
Myung-Haing
MH
Kim
Young-Myeong
YM
Oh
Sei-Ryang
SR
Lee
Hyeong-kyu
HK
Nam
Ki-Hoan
KH
Oh
Goo Taeg
GT
D000818:Animals; D001161:Arteriosclerosis / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D005419:Flavonoids / Q000494:pharmacology*; D006027:Glycosides / Q000494:pharmacology*; D006949:Hyperlipidemias / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000378:metabolism; D007375:Interleukin-1 / Q000097:blood / Q000235:genetics; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D005419:Flavonoids; D006027:Glycosides; D020672:I-kappa B Proteins; D007375:Interleukin-1; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D012333:RNA, Messenger; D011973:Receptors, LDL; D014409:Tumor Necrosis Factor-alpha; C426884:tilianin; D000072000:NF-KappaB Inhibitor alpha; D017346:Protein Serine-Threonine Kinases; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse