Heikenwalder Mathias, Polymenidou Magdalini, Junt Tobias, Sigurdson Christina, Wagner Hermann, Akira Shizuo, Zinkernagel Rolf, Aguzzi Adriano
Institute of Neuropathology, University Hospital of Zürich, Schmelzbergstrasse 12, CH-8091 Zürich, Switzerland.
Nat Med. 2004 Feb;10(2):187-92. doi: 10.1038/nm987. Epub 2004 Jan 25.
DNA containing unmethylated cytidyl guanosyl (CpG) sequences, which are underrepresented in mammalian genomes but prevalent in prokaryotes, is endocytosed by cells of the innate immune system, including macrophages, monocytes and dendritic cells, and activates a pathway involving Toll-like receptor-9 (TLR9). CpG-containing oligodeoxynucleotides (CpG-ODN) are potent stimulators of innate immunity, and are currently being tested as adjuvants of antimicrobial, antiallergic, anticancer and antiprion immunotherapy. Little is known, however, about the consequences of repeated CpG-ODN administration, which is advocated for some of these applications. Here we report that daily injection of 60 microg CpG-ODN dramatically alters the morphology and functionality of mouse lymphoid organs. By day 7, lymphoid follicles were poorly defined; follicular dendritic cells (FDC) and germinal center B lymphocytes were suppressed. Accordingly, CpG-ODN treatment for > or =7 d strongly reduced primary humoral immune responses and immunoglobulin class switching. By day 20, mice developed multifocal liver necrosis and hemorrhagic ascites. All untoward effects were strictly dependent on CpG and TLR9, as neither the CpG-ODN treatment of Tlr9(-/-) mice nor the repetitive challenge of wild-type mice with nonstimulatory ODN (AT-ODN) or with the TLR3 agonist polyinosinic:cytidylic acid (polyI:C) were immunotoxic or hepatotoxic.
含有未甲基化胞嘧啶鸟嘌呤（CpG）序列的DNA在哺乳动物基因组中含量较少，但在原核生物中普遍存在，它可被包括巨噬细胞、单核细胞和树突状细胞在内的先天免疫系统细胞内吞，并激活一条涉及Toll样受体9（TLR9）的信号通路。含CpG的寡脱氧核苷酸（CpG-ODN）是先天免疫的有效刺激剂，目前正作为抗菌、抗过敏、抗癌和抗朊病毒免疫疗法的佐剂进行测试。然而，对于这些应用中提倡的重复给予CpG-ODN的后果却知之甚少。在此我们报告，每天注射60微克CpG-ODN会显著改变小鼠淋巴器官的形态和功能。到第7天时，淋巴滤泡界限不清；滤泡树突状细胞（FDC）和生发中心B淋巴细胞受到抑制。相应地，CpG-ODN处理≥7天会强烈降低初次体液免疫反应和免疫球蛋白类别转换。到第20天时，小鼠出现多灶性肝坏死和出血性腹水。所有不良影响都严格依赖于CpG和TLR9，因为Tlr9(-/-)小鼠的CpG-ODN处理以及野生型小鼠用无刺激作用的ODN（AT-ODN）或TLR3激动剂聚肌苷酸:胞苷酸（polyI:C）进行重复刺激均无免疫毒性或肝毒性。
