CpG oligodeoxynucleotides induce IL-8 expression in CD34+ cells via mitogen-activated protein kinase-dependent and NF-kappaB-independent pathways.
To elucidate the role of Toll-like receptor 9 (TLR9) activation along with the intracellular signaling pathways triggered by CpG DNA in CD34+ cells, we investigated whether synthetic oligodeoxynucleotides (ODNs), containing unmethylated CpG motifs, could induce IL-8 expression in CD34+ cells through mitogen-activated protein kinase (MAPK) or nuclear factor-kappaB (NF-kappaB) pathway. We demonstrated evidence for the first time that CD34+ cells constitutively expressed TLR9. Exposure of the cells to CpG ODN resulted in a time- and dose-dependent increase of IL-8 expression, and activation of phosphorylated ERK1/2 and phosphorylated p38. In addition, CpG ODN stimulated AP-1, but not NF-kappaB, signals. Moreover, inhibitors of MAPK (U0126 and SB203580) significantly reduced the IL-8 production, while the inhibition of NF-kappaB (pyrrolidinedithiocarbamate and retrovirus containing dominant-negative IkappaB alpha plasmid) did not affect the IL-8 expression increased by CpG ODN. Moreover, co-stimulation with LPS and CpG synergistically up-regulates IL-8 in CD34+ cells. These results suggest that CpG DNA, acting on TLR9, activates CD34+ cells to express IL-8 through MAPK-dependent and NF-kappaB-independent pathways.
Kim
Jung Mogg
JM
Department of Microbiology and Institute of Biomedical Science, Hanyang University College of Medicine, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791, Korea. jungmogg@hanyang.ac.kr
Kim
Nam In
NI
Oh
Yu-Kyoung
YK
Kim
Young-Jeon
YJ
Youn
Jeehee
J
Ahn
Myung-Ju
MJ
D018952:Antigens, CD34 / Q000378:metabolism; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology*; D020862:GC Rich Sequence / Q000276:immunology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D016209:Interleukin-8 / Q000096:biosynthesis*; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000276:immunology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D009838:Oligodeoxyribonucleotides / Q000276:immunology / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology; D051217:Toll-Like Receptor 9 / Q000276:immunology
D018952:Antigens, CD34; D002070:Butadienes; C508606:CXCL8 protein, human; D004791:Enzyme Inhibitors; D007093:Imidazoles; D016209:Interleukin-8; D016328:NF-kappa B; D009570:Nitriles; D009838:Oligodeoxyribonucleotides; D011725:Pyridines; C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9; C113580:U 0126; D020928:Mitogen-Activated Protein Kinases; C093642:SB 203580