Salvia miltiorrhiza water extract ameliorated cGAS-STING-mediated acute liver injury by blocking interaction between STING and TBK1.

Objective: To investigate the potential of Salvia miltiorrhiza water extract (SMWE) as a modulator of the cGAS-STING signaling pathway, which is implicated in the pathogenesis of immune and inflammatory disorders, and to elucidate its underlying mechanism of action through in vitro and in vivo experiments. Methods: The cGAS-STING signaling pathway was activated in bone marrow-derived macrophages (BMDMs), Tohoku hospital pediatrics-1 (THP-1) cells, and peripheral blood mononuclear cells (PBMCs). The effect of SMWE on the expression of phosphorylated interferon regulatory factor 3 (IRF3) and phosphorylated STING after aberrant activation of the cGAS-STING pathway was detected by immunoblotting. Subsequently, real-time quantitative PCR was performed to detect changes in the mRNA levels of interferon type I (IFN), interferon-stimulated genes and inflammatory factors. The effect of SMWE on STING oligomerisation and the interaction between STING, Tank Binding Kinase 1 (TBK1) and IRF3 was investigated by immunoblotting. A model of acute liver injury (ALI) caused by lipopolysaccharide/D-galactosamine (LPS/D-GaIN) was used to test the effects of SMWE on inflammation mediated by the cGAS-STING signaling cascade. Results: SMWE significantly inhibited the phosphorylation of STING and IRF3, thereby suppressing the activation of the cGAS-STING signaling pathway. It also stopped the cGAS-STING pathway from working by stopping the production of type I interferons and interferon-stimulated genes, like interferon-stimulated gene 15 (ISG15) and C-X-C motif chemokine ligand 10 (CXCL10). SMWE also reduced the production of pro-inflammatory cytokines, such as interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α). SMWE also significantly improved ALI resulting from LPS/D-GaIN by diminishing the hyperactivation of the cGAS-STING signalling pathway. Mechanistic analysis revealed that SMWE disrupted the interaction between STING and TBK1. Conclusion: SMWE is a potent modulator of aberrant activation of the cGAS-STING pathway and is able to prevent and treat LPS/D-GaIN-induced ALI by inhibiting activation of the cGAS-STING pathway.