title: Interactions of beta-carotene and flavonoids on the secretion of pro-inflammatory mediators in an in vitro system.
abstract: Chronic inflammation, a process linked to increased oxidative stress, may induce many diseases. Whether beta-carotene prevents inflammation is unclear. Using phorbol-12-myristate-13-acetate (PMA)-stimulated HL-60 cells, we investigated the effects of 2 or 20 microM beta-carotene on the inflammatory reaction of monocyte/macrophage-like cells and the modulation of 20 microM quercetin or naringenin, two flavonoids, of the effects of beta-carotene. The effects of quercetin and naringenin were compared with that of alpha-tocopherol, a well-known antioxidant. The stimulated HL-60 cells were also co-incubated with A549 cells to investigate the DNA-damaging ability of the stimulated monocyte/macrophage-like cells on target cells. Our results showed that preincubation with 20 microM beta-carotene significantly enhanced the release of two pro-inflammatory mediators, interleukin-8 and tumor necrosis factor-alpha, in PMA-stimulated HL-60 cells and slightly increased the DNA-damaging ability of these cells. By contrast, 2 microM beta-carotene had an inhibitory effect on the inflammatory reaction in PMA-stimulated cells. The higher dose of beta-carotene also exerted pro-inflammatory effects in lipopolysaccharide-stimulated RAW264.7 cells. Furthermore, quercetin, naringenin, and alpha-tocopherol partly suppressed the pro-inflammatory effects of 20 microM beta-carotene on PMA-stimulated HL-60 cells, and the suppressing effects of quercetin and naringenin were better than or similar to those of alpha-tocopherol. Quercetin also additively or synergistically enhanced the inhibitory effects of 2 microM beta-carotene on the secretion of pro-inflammatory mediators and the DNA-damaging ability of PMA-stimulated HL-60 cells. The mechanisms underlying the effect of the flavonoids were associated with their antioxidant activity and inhibition of the production of pro-inflammatory cytokines. Our results urge consideration of the safety of beta-carotene supplementation concerning effects on inflammation and suggest that the interaction between beta-carotene and quercetin or naringenin may alter the effects of beta-carotene on the secretion of pro-inflammatory mediators.
authors.affiliation: Institute of Nutritional Science, Chung Shan Medical University, Taichung, Taiwan, ROC. suzyyeh@csmu.edu.tw
authors.forename: Shu-Lan
authors.initials: SL
authors.lastname: Yeh
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Wang
authors.forename: Pei-Ying
authors.initials: PY
authors.lastname: Chen
authors.forename: Tzu-Chin
authors.initials: TC
authors.lastname: Wu
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D044950:Flavanones / Q000737:chemistry / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors / Q000494:pharmacology; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D024502:alpha-Tocopherol / Q000494:pharmacology; D019207:beta Carotene / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D044950:Flavanones; D016209:Interleukin-8; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D014409:Tumor Necrosis Factor-alpha; D019207:beta Carotene; D011794:Quercetin; D024502:alpha-Tocopherol; C005273:naringenin; D013755:Tetradecanoylphorbol Acetate