作为生命物质基础的DNA主要通过内体TLR9和胞质识别受体来启动免疫应答。近年来TLR9受体研究的新进展主要体现在以下四个方面：（1）TLR9与其配体相互作用的决定因素；（2）TLR9由内质网到内体的转位机制及其重要性；（3）内体的酸化成熟和TLR9的剪切在信号转导中的作用；（4）TLR9区分自体与外源DNA的可能机制。同时，有关TLR9拮抗剂和TLR9缺陷小鼠的一系列实验有力地证实了TLR9非依赖性胞质DNA受体的存在，到目前为止共发现了3个分子：DAI、AIM2、RNA聚合酶Ⅲ。

DNA, as the material basis of all living cells, triggers innate immune responses through TLR9 and other cytosolic recognition receptors. In recent years, the research progress of TLR9 is mainly manifested by the following four aspects: (1) the determinants of TLR9 interacting with its ligands; (2) the mechanisms and the importance of TLR9 translocation from the endoplasmic reticulum to the endosome; (3) the roles of the endosomal acidification and maturation, and subsequent TLR9 cleavage in TLR9 signal transduction pathway; and (4) the possible mechanisms by which the organism distinguish self DNA from microbial DNA. Meanwhile, a series of experiments on TLR9 antagonists and TLR9 deficient mice confirmed the presence of TLR9independent cytosolic DNA sensors. So far, three TLR9independent DNA sensors have been found, and they are DAI, AIM2, and RNA polymerase Ⅲ.