Chemoprotection by phenolic antioxidants. Inhibition of tumor necrosis factor alpha induction in macrophages.
Phenolic antioxidants exhibit anti-inflammatory activity in protection against chemical toxicity and cancer. To investigate the molecular mechanism of anti-inflammation, we analyzed the regulation of tumor necrosis factor alpha (TNF-alpha) expression in macrophages, a key step in inflammation, by the antioxidants. Whereas lipopolysaccharide (LPS), an inflammatory inducer, stimulates rapid synthesis of TNF-alpha protein, phenolic antioxidants, exemplified by tert-butyl hydroquinone and 1,4-dihydroquinone, block LPS-induced production of TNF-alpha protein in a time- and dose-dependent manner. Inhibition of TNF-alpha induction correlates with the capacity of the antioxidants to undergo oxidation-reduction cycling, implicating oxidative signaling in the inhibition. The antioxidants blocked LPS-induced increase of the steady-state mRNA of TNF-alpha but did not affect the half-life of the mRNA. Electrophoretic mobility shift assay reveals a total inhibition of LPS-induced formation of nuclear factor kappaB.DNA binding complexes by phenolic antioxidants. Finally, 1,4-dihydroquinone blocks the induction of TNF-alpha target genes interleukin 1beta and interleukin 6 at both mRNA and protein levels. Our findings demonstrate that phenolic antioxidants potently inhibit signal-induced TNF-alpha transcription and suggest a mechanism of anti-inflammation by the antioxidants through control of cytokine induction during inflammation.
Ma
Qiang
Q
Receptor Biology Laboratory, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505, USA. qam1@cdc.gov
Kinneer
Krista
K
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D015152:Blotting, Northern; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006873:Hydroquinones / Q000737:chemistry; D007375:Interleukin-1 / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008956:Models, Chemical; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D019800:Phenol / Q000494:pharmacology*; D011485:Protein Binding; D011809:Quinones / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
C403008:1,4-dihydroquinone; D000975:Antioxidants; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011809:Quinones; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D019800:Phenol; D006861:Hydrogen Peroxide; C018855:2-tert-butylhydroquinone