Nicotine induces human neutrophils to produce IL-8 through the generation of peroxynitrite and subsequent activation of NF-kappaB.
Leukocytosis in tobacco smokers has been well recognized; however, the exact cause has not been elucidated. To test the hypothesis that tobacco nicotine stimulates neutrophils in the respiratory tract to produce IL-8, which causes neutrophilia in vivo, we examined whether nicotine induces neutrophil-IL-8 production in vitro; the causative role of NF-kappaB in its production, in association with the possible production of reactive oxygen intermediates that activate NF-kappaB; and the nicotinic acetylcholine receptors (nAChRs) involved in IL-8 production. Nicotine stimulated neutrophils to produce IL-8 in both time- and concentration-dependent manners with a 50% effective concentration of 1.89 mM. A degradation of IkappaB-alpha/beta proteins and an activity of NF-kappaB p65 and p50 were enhanced following nicotine treatment. The synthesis of superoxide and the oxidation of dihydrorhodamine 123 (DHR) were also enhanced. The NOS inhibitor, nomega-Nitro-l-arginine methyl ester, prevented nicotine-induced IL-8 production, with an entire abrogation of DHR oxidation, IkappaB degradation, and NF-kappaB activity. Neutrophils spontaneously produced NO whose production was not increased, but rather decreased by nicotine stimulation, suggesting that superoxide, produced by nicotine, generates peroxynitrite by reacting with preformed NO, which enhances the NF-kappaB activity, thereby producing IL-8. The nAChRs seemed to be involved in IL-8 production. In smokers, blood IL-8 levels were significantly higher than those in nonsmokers. In conclusion, nicotine stimulates neutrophil-IL-8 production via nAChR by generating peroxynitrite and subsequent NF-kappaB activation, and the IL-8 appears to contribute to leukocytosis in tobacco smokers.
Iho
Sumiko
S
Department of Immunology and Medical Zoology, Fukui Medical University, Yoshida-gun, Fukui, Japan. ihosumik@fmsrsa.fukui-med.ac.jp
Tanaka
Yukie
Y
Takauji
Rumiko
R
Kobayashi
Chino
C
Muramatsu
Ikunobu
I
Iwasaki
Hiromichi
H
Nakamura
Kishiko
K
Sasaki
Yutaka
Y
Nakao
Kazuwa
K
Takahashi
Takayuki
T
D006801:Humans; D020672:I-kappa B Proteins / Q000097:blood; D016209:Interleukin-8 / Q000096:biosynthesis / Q000097:blood*; D007700:Kinetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000097:blood*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009504:Neutrophils / Q000276:immunology*; D009538:Nicotine / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis; D009195:Peroxidase / Q000097:blood; D030421:Peroxynitrous Acid / Q000097:blood*; D021381:Protein Transport; D017382:Reactive Oxygen Species / Q000378:metabolism; D012907:Smoking / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D020672:I-kappa B Proteins; D016209:Interleukin-8; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D009538:Nicotine; D009195:Peroxidase; D019331:NG-Nitroarginine Methyl Ester