Influences of aflatoxin B1 on reactive oxygen species generation and chemotaxis of human polymorphonuclear leukocytes.
The effects of aflatoxin (AF), a hepatotoxic agent and the strongest carcinogen in nature, on polymorphonuclear leukocyte (PMN) chemotaxis and chemiluminescence (CL) were studied. Luminol-dependent CL activity, which reflects the production of reactive oxygen species (ROS) from PMNs, was up-regulated to approximately 150% when PMNs were treated with 0.05 ng/ml of AFB1 upon stimulation with N-formyl-methionine-leucine-phenylalanine (fMLP) or zymosan. On the other hand, PMN CL activity was down-regulated to approximately 25% of the control when PMNs were treated with 50 ng/ml of AFB1 upon stimulation with zymosan. The effect of AFB1 on PMN chemotaxis was also investigated using the Boyden chamber method. The chemotactic ability of PMNs when interleukin (IL)-8 was used as a chemoattractant was inhibited in a dose-dependent manner at AFB1 concentrations of >10 ng/ml. In reverse transcriptase (RT)-PCR analysis, gene expression levels of CXC chemokine receptor (CXCR)1/2, whose ligands are IL-8, granulocyte chemotactic protein (GCP)-2, neutrophil attractant-activation protein (NAP)-2, and epithelial neutrophil-activating protein (ENA)-78, which regulate PMN chemotaxis, were also down-regulated in a dose-dependent manner by 50 ng/ml AFB1. mRNA expression levels of CXCR1/2 were down-regulated to approximately 85% of that in the controls when PMNs were treated with 100 ng/ml AFB1. These results suggest that a high concentration of AFB1 reduces the chemotactic ability of PMNs via the CXCR1/2 cascade indirectly.
Ubagai
Tsuneyuki
T
Department of Microbiology & Immunology, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan. ubat@med.teikyo-u.ac.jp <ubat@med.teikyo-u.ac.jp>
Tansho
Shigeru
S
Ito
Tadashi
T
Ono
Yasuo
Y
D016604:Aflatoxin B1 / Q000008:administration & dosage / Q000633:toxicity*; D002273:Carcinogens / Q000008:administration & dosage / Q000633:toxicity; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D049449:Luminescence; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D011042:Poisons / Q000008:administration & dosage / Q000633:toxicity*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D023062:Receptors, Interleukin-8A / Q000187:drug effects / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002273:Carcinogens; D011042:Poisons; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B; D016604:Aflatoxin B1