Collaborative action of NF-kappaB and p38 MAPK is involved in CpG DNA-induced IFN-alpha and chemokine production in human plasmacytoid dendritic cells

• Published in: The Journal of immunology (1950) Vol. 177; no. 7; pp. 4841 - 4852
• Main Authors: Osawa, Youko, Iho, Sumiko, Takauji, Rumiko, Takatsuka, Hisakazu, Yamamoto, Saburo, Takahashi, Takayuki, Horiguchi, Satomi, Urasaki, Yoshimasa, Matsuki, Takasumi, Fujieda, Shigeharu
• Format: Journal Article
• Language: English
• Published: United States 01.10.2006
• Subjects: Blotting, Western; Chemokines - biosynthesis; CpG Islands - immunology; Dendritic Cells - immunology; Dendritic Cells - metabolism; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Gene Expression; Humans; Interferon Regulatory Factor-7 - immunology; Interferon Regulatory Factor-7 - metabolism; Interferon-alpha - immunology; Interferon-alpha - metabolism; NF-kappa B - immunology; NF-kappa B - metabolism; p38 Mitogen-Activated Protein Kinases - immunology; p38 Mitogen-Activated Protein Kinases - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction - immunology; Toll-Like Receptor 9 - immunology; Toll-Like Receptor 9 - metabolism
• ISSN: 0022-1767

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.