Discovery And Evaluation Of Biological Activity Of Small Molecule Inhibitors Targeting STING

Stimulator of interferon gene（STING）is an important adaptor protein in the innate immune signaling pathway cyclic guanylate-adenylate synthase（c GAS）-STING signaling pathway.Recent studies have shown that the c GAS-STING pathway plays an important role in the pathogenesis of many inflammatory diseases.c GAS can sense double-stranded DNA in the cytoplasm and catalyze the formation of cyclic dinucleotides（c GAMP）from ATP and GTP to activate STING.In most cases,activation of this pathway plays a key regulatory role in host defense against pathogenic microbial infection and anti-tumor immunity.However,accumulation of abnormal self-DNA or mutations in STING function can cause persistent activation of this pathway,resulting in the continuous production of type I interferons and proinflammatory cytokines,which in turn promote the occurrence of inflammatory and autoimmune diseases,such as Aicardi-Goutières syndrome（AGS）,systemic lupus erythematosus（SLE）,STING-associated vascular disease（SAVI）,etc.Therefore,STING is considered as a promising therapeutic target for inflammatory immune diseases.In this paper,we discovered Licochalcone D,a natural product inhibitor that directly targets STING,through AI-based virtual screening and biochemical experiments.Molecular-level experiments such as protein thermal shift,surface plasmon resonance and isothermal titration calorimetry confirmed that Licochalcone D can specifically bind to STING protein directly.At the cellular level,Licochalcone D can specifically block the activation of STING signaling pathway induced by double-stranded DNA and various STING small molecule agonists,thereby inhibiting the secretion of type I interferons and inflammatory cytokines.Furthermore,in Trex1^-/-mice,Licochalcone D can significantly inhibit inflammation and features of autoimmune diseases.In addition,we further applied Licochalcone D to the treatment of dextran sodium sulfate（DSS）-induced acute colitis in mice,and the results showed that Licochalcone D also showed significant alleviating effects on acute colitis in mice.All in all,the research work of this paper has discovered and confirmed a specific STING small molecule inhibitor,Licochalcone D,which is expected to be applied to the treatment of STING-mediated related inflammatory immune diseases and provides a reference for the subsequent drug development targeting STING for the treatment of related inflammatory immune diseases.