title: Increase in CpG DNA-induced inflammatory responses by DNA oxidation in macrophages and mice.
abstract: Unmethylated CpG dinucleotide (CpG motif) is involved in the exacerbation of DNA-associated autoimmune diseases. We investigated the effect of DNA containing 8-hydroxydeoxyguanosine (oxo-dG), a representative DNA biomarker for oxidative stress in the diseases, on CpG motif-dependent inflammatory responses. ODN1668 and ODN1720 were selected as CpG-DNA and non-CpG DNA, respectively. Deoxyguanosine in the CpG motif (G9) or outside the motif (G15) of ODN1668 was substituted with oxo-dG to obtain oxo(G9)-1668 and oxo(G15)-1668, respectively. Oxo(G15)-1668 induced a significantly higher amount of tumor necrosis factor (TNF)-α from RAW264.7 macrophage-like cells than ODN1668, whereas oxo(G9)-1668, oxo(G8)-1720, or oxo(G15)-1720 hardly did. CpG DNA-induced TNF-α production was significantly increased by addition of oxo(G8)-1720 or oxo(G15)-1720, but not of ODN1720. This oxo-dG-containing DNA-induced increase in TNF-α production was also observed in primary cultured macrophages isolated from wild-type mice, but not observed in those from Toll-like receptor (TLR)-9 knockout mice. In addition, TNF-α production by ligands for TLR3, TLR4, or TLR7 was not affected by oxo-dG-containing DNA. Then, the footpad swelling induced by subcutaneous injection of ODN1668 into mice was increased by coinjection with oxo(G8)-1720, but not with ODN1720. These results indicate that oxo-dG-containing DNA increases the CpG motif-dependent inflammatory responses, which would exacerbate DNA-related autoimmune diseases.
authors.affiliation: Department of Biopharmaceutics and Drug Metabolism, Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshidashimoadachi-cho 46–29, Sakyo-ku, Kyoto 606–8501, Japan. h.yoshida@nihs.go.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshida
authors.forename: Makiya
authors.initials: M
authors.lastname: Nishikawa
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kiyota
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Toyota
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Takakura
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018899:CpG Islands; D004247:DNA / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010084:Oxidation-Reduction
chemical_list: D004247:DNA