Cyclic GMP-AMP synthase (cGAS) is an essential sensor of aberrant cytosolic DNA for initiating innate immunity upon invading pathogens and cellular stress, which is considered as a potential drug target for autoimmune and autoinflammatory diseases. Here, we report the discovery of a class of cyclopeptide inhibitors of cGAS identified by an in vitro screening assay from a focused library of cyclic peptides. These cyclopeptides specifically bind to the DNA binding site of cGAS and block the binding of dsDNA with cGAS, subsequently inhibit dsDNA-induced liquid phase condensation and activation of cGAS. The specificity and potency of one optimal lead XQ2B were characterized in cellular assays. Concordantly, XQ2B inhibited herpes simplex virus-1 (HSV-1)-induced antiviral immune responses and enhanced HSV-1 infection in vitro and in vivo. Furthermore, XQ2B significantly suppressed the elevated levels of type I interferon and proinflammatory cytokines in primary macrophages from Trex1^-/- mice and systemic inflammation in Trex1^-/- mice. XQ2B represents the specific cGAS inhibitor targeting protein-DNA interaction and phase separation and serves as a scaffold for the development of therapies in the treatment of cGAS-dependent inflammatory diseases.

环 GMP-AMP 合酶 (cGAS) 是异常胞质 DNA 的重要传感器，可在病原体入侵和细胞应激时启动先天免疫，被认为是自身免疫和自身炎症疾病的潜在药物靶点。在此，我们报告发现了一类 cGAS 环肽抑制剂，该抑制剂是通过体外筛选试验从环肽重点库中鉴定出来的。这些环肽特异性结合cGAS的DNA结合位点并阻断dsDNA与cGAS的结合，随后抑制dsDNA诱导的cGAS的液相凝聚和活化。在细胞测定中表征了一种最佳先导 XQ2B 的特异性和效力。同样，XQ2B 抑制单纯疱疹病毒 1 (HSV-1) 诱导的抗病毒免疫反应，并在体外和体内增强 HSV-1 感染。此外，XQ2B 显着抑制Trex1 ^-/-小鼠原代巨噬细胞中 I 型干扰素和促炎细胞因子的升高水平以及Trex1 ^-/-小鼠的全身炎症。XQ2B 代表针对蛋白质-DNA 相互作用和相分离的特异性 cGAS 抑制剂，可作为开发治疗 cGAS 依赖性炎症疾病的疗法的支架。