Diesel exhaust particles upregulate eotaxin gene expression in human bronchial epithelial cells via nuclear factor-kappa B-dependent pathway.
Fine particles derived from diesel engines, diesel exhaust particles (DEP), have been shown to augment gene expression of several inflammatory cytokines in human airway epithelial cells in vitro. However, it remains unclear whether or not DEP have any effect on the expression and production of eotaxin, an important chemokine involved in eosinophil recruitment into the airways. We studied the effects of DEP by using a conventional suspended DEP and by a recently established in vitro cell exposure system to diesel exhaust (Abe S, Takizawa H, Sugawara I, and Kudoh S, Am J Respir Cell Mol Biol 22: 296-303, 2000). DEP showed a dose-dependent stimulatory effect on eotaxin production by normal human peripheral airway epithelial cells as well as by bronchial epithelial cell line BET-1A as assessed by specific ELISA. mRNA levels increased by DEP were shown by RT-PCR. DEP showed an additive effect on IL-13-stimulated eotaxin expression. DEP induced NF-kappaB activation by EMSA as previously reported but did not induce signal transducer and activator of transcription (STAT) 6 activation according to Western blot analysis. Finally, antioxidant agents (N-acetyl cysteine and pyrrolidine dithiocarbamate), which inhibited NF-kappaB activation but failed to affect STAT6 activation, almost completely attenuated DEP-induced eotaxin production, whereas these agents failed to attenuate IL-13-induced eotaxin production. These findings suggested that DEP stimulated eotaxin gene expression via NF-kappaB-dependent, but STAT6-independent, pathways.
Takizawa
Hajime
H
Departments of Laboratory Medicine and Respiratory Medicine, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan. takizawa-phy@h.u-tokyo.ac.jp
Abe
Shinji
S
Okazaki
Hitoshi
H
Kohyama
Tadashi
T
Sugawara
Isamu
I
Saito
Yoshinobu
Y
Ohtoshi
Takayuki
T
Kawasaki
Shin
S
Desaki
Masashi
M
Nakahara
Kazuhiko
K
Yamamoto
Kazuhiko
K
Matsushima
Kouji
K
Tanaka
Mitsuru
M
Sagai
Masaru
M
Kudoh
Shoji
S
D000111:Acetylcysteine / Q000494:pharmacology; D000906:Antibodies; D000975:Antioxidants / Q000494:pharmacology; D001980:Bronchi / Q000166:cytology / Q000378:metabolism; D002478:Cells, Cultured; D054413:Chemokine CCL11; D019742:Chemokines, CC / Q000235:genetics* / Q000276:immunology; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005100:Expectorants / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D018793:Interleukin-13 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D011392:Proline / Q000031:analogs & derivatives* / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*; D050800:STAT6 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects; D013859:Thiocarbamates / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D001335:Vehicle Emissions / Q000009:adverse effects*
D000906:Antibodies; D000975:Antioxidants; C515456:CCL11 protein, human; D054413:Chemokine CCL11; D019742:Chemokines, CC; D005100:Expectorants; D018793:Interleukin-13; D016328:NF-kappa B; D012333:RNA, Messenger; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D013859:Thiocarbamates; D015534:Trans-Activators; D001335:Vehicle Emissions; C066229:prolinedithiocarbamate; D011392:Proline; D000111:Acetylcysteine