Collaborative action of NF-kappaB and p38 MAPK is involved in CpG DNA-induced IFN-alpha and chemokine production in human plasmacytoid dendritic cells.
CpG DNA induces plasmacytoid dendritic cells (pDC) to produce type I IFN and chemokines. However, it has not been fully elucidated how the TLR9 signaling pathway is linked to these gene expressions. We examined the mechanisms involving the TLR9 and type I IFN signaling pathways, in relation to CpG DNA-induced IFN-alpha, IFN regulatory factor (IRF)-7, and chemokines CXCL10 and CCL3 in human pDC. In pDC, NF-kappaB subunits p65 and p50 were constitutively activated. pDC also constitutively expressed IRF-7 and CCL3, and the gene expressions seemed to be regulated by NF-kappaB. CpG DNA enhanced the NF-kappaB p65/p50 activity, which collaborated with p38 MAPK to up-regulate the expressions of IRF-7, CXCL10, and CCL3 in a manner independent of type I IFN signaling. We then examined the pathway through which IFN-alpha is expressed. Type I IFN induced the expression of IRF-7, but not of IFN-alpha, in a NF-kappaB-independent way. CpG DNA enabled the type I IFN-treated pDC to express IFN-alpha in the presence of NF-kappaB/p38 MAPK inhibitor, and chloroquine abrogated this effect. With CpG DNA, IRF-7, both constitutively and newly expressed, moved to the nuclei independently of NF-kappaB/p38 MAPK. These findings suggest that, in CpG DNA-stimulated human pDC, the induction of IRF-7, CXCL10, and CCL3 is mediated by the NF-kappaB/p38 MAPK pathway, and that IRF-7 is activated upstream of the activation of NF-kappaB/p38 MAPK in chloroquine-sensitive regulatory machinery, thereby leading to the expression of IFN-alpha.
Osawa
Youko
Y
Department of Otorhinolaryngology-Head and Neck Surgery, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuoka-Shimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan.
Iho
Sumiko
S
Takauji
Rumiko
R
Takatsuka
Hisakazu
H
Yamamoto
Saburo
S
Takahashi
Takayuki
T
Horiguchi
Satomi
S
Urasaki
Yoshimasa
Y
Matsuki
Takasumi
T
Fujieda
Shigeharu
S
D015153:Blotting, Western; D018925:Chemokines / Q000096:biosynthesis*; D018899:CpG Islands / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D050839:Interferon Regulatory Factor-7 / Q000276:immunology / Q000378:metabolism; D016898:Interferon-alpha / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000276:immunology / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology / Q000378:metabolism*
D018925:Chemokines; D050839:Interferon Regulatory Factor-7; D016898:Interferon-alpha; D016328:NF-kappa B; D051217:Toll-Like Receptor 9; D048051:p38 Mitogen-Activated Protein Kinases