Cortez-Gonzalez Xochitl, Pellicciotta Ilenia, Gerloni Mara, Wheeler Matthew C, Castiglioni Paola, Lenert Petar, Zanetti Maurizio
The Laboratory of Immunology, Department of Medicine and Cancer Center, University of California, San Diego, La Jolla, California 92093-0837, USA.
DNA Cell Biol. 2006 May;25(5):253-61. doi: 10.1089/dna.2006.25.253.
The intracellular Toll-like receptor 9 (TLR9) is unique in its ability to recognize single-stranded DNA unmethylated at CpG motifs. Work from this laboratory showed that plasmid DNA is spontaneously internalized in B lymphocytes. This event is followed by the upregulation of costimulatory molecules and the acquisition of antigen presenting function by these cells. However, it is not known whether this phenomenon depends on TLR9. Because of the relevant role played by DNA-based drugs in immunotherapy and vaccination, and the central role of TLR9 signaling by CpG motifs, we decided to investigate whether signaling through TLR9 is a prerequisite for spontaneous transgenesis of lymphocytes. Here we found that transgene expression and upregulation of CD40 and CD86 costimulatory molecules was not inhibited by chloroquine treatment. Spontaneous transgenesis also occurred in B lymphocytes from TLR9-/- mice, and the injection of TLR9-/- transgenic B lymphocytes in C57Bl/6 mice induced both CD4 and CD8 T cell responses comparable to those induced by wild-type B lymphocytes. Collectively, these results suggest that plasmid DNA activates mammalian B lymphocytes through a TLR9 independent pathway.
细胞内Toll样受体9（TLR9）在识别CpG基序处未甲基化的单链DNA的能力方面独具特色。本实验室的研究表明，质粒DNA可在B淋巴细胞中自发内化。此事件之后，共刺激分子上调，这些细胞获得抗原呈递功能。然而，尚不清楚这种现象是否依赖于TLR9。鉴于基于DNA的药物在免疫治疗和疫苗接种中的相关作用，以及CpG基序在TLR9信号传导中的核心作用，我们决定研究通过TLR9的信号传导是否是淋巴细胞自发转基因的先决条件。在此我们发现，氯喹处理并未抑制转基因表达以及CD40和CD86共刺激分子的上调。TLR9基因敲除小鼠的B淋巴细胞中也发生了自发转基因现象，并且将TLR9基因敲除的转基因B淋巴细胞注射到C57Bl/6小鼠体内可诱导与野生型B淋巴细胞诱导的CD4和CD8 T细胞反应相当的反应。总体而言，这些结果表明质粒DNA通过TLR9非依赖性途径激活哺乳动物B淋巴细胞。
