Yasuda Kei, Ogawa Yoshiyuki, Kishimoto Michiyuki, Takagi Toshihide, Hashida Mitsuru, Takakura Yoshinobu
Department of Biopharmaceutics and Drug Metabolism, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshidashimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Biochem Biophys Res Commun. 2002 Apr 26;293(1):344-8. doi: 10.1016/S0006-291X(02)00210-3.
Plasmid DNA (pDNA) is very important in non-viral gene therapy and DNA vaccination. Unmethylated CpG motifs in bacterial DNA, but not in vertebrate DNA, are known to trigger an inflammatory response, which inhibits gene expression while improving immunological consequences. In this report, we investigated the cytokine secretion induced by pDNA/cationic liposome complexes using murine macrophages. Naked CpG DNA induced tumor necrosis factor-alpha (TNF-alpha) secretion from the macrophages, but DNA without CpG motif did not, demonstrating that the cytokine induction was mediated by CpG motifs. pDNA complexed with cationic liposomes, but not the cationic liposomes alone, produced a significant amount of TNF-alpha from the macrophages. Surprisingly, methylated pDNA and calf thymus DNA complexed with the cationic liposomes were also able to induce TNF-alpha production, indicating that these responses were not dependent on CpG motifs. Taken together, the present study demonstrated that for the first time DNA can stimulate murine macrophages in a CpG motif-independent manner when it is complexed with the cationic liposomes.
质粒DNA（pDNA）在非病毒基因治疗和DNA疫苗接种中非常重要。已知细菌DNA中的未甲基化CpG基序可引发炎症反应，而脊椎动物DNA中的未甲基化CpG基序则不会引发炎症反应，这种炎症反应会抑制基因表达，同时改善免疫效果。在本报告中，我们使用小鼠巨噬细胞研究了pDNA/阳离子脂质体复合物诱导的细胞因子分泌。裸露的CpG DNA可诱导巨噬细胞分泌肿瘤坏死因子-α（TNF-α），但不含CpG基序的DNA则不能，这表明细胞因子的诱导是由CpG基序介导的。与阳离子脂质体复合的pDNA（而非单独的阳离子脂质体）可使巨噬细胞产生大量TNF-α。令人惊讶的是，与阳离子脂质体复合的甲基化pDNA和小牛胸腺DNA也能够诱导TNF-α的产生，这表明这些反应不依赖于CpG基序。综上所述，本研究首次证明，当DNA与阳离子脂质体复合时，它可以以不依赖CpG基序的方式刺激小鼠巨噬细胞。
