Inhibition of Sirt3 activates the cGAS-STING pathway to aggravate hepatocyte damage in hepatic ischemia–reperfusion injury mice

• Published in: International immunopharmacology 2024-02, Vol.128, p.111474-111474, Article 111474
• Main Authors: Kong, Erliang, Zhang, Yang, Geng, Xuqiang, Zhao, Yuanyuan, Yue, Wei, Feng, Xudong
• Format: Article
• Language: English
• Subjects: cGAS-STING; Hepatic ischemia–reperfusion injury; Inflammation; Nuclear translocation; p65; Sirt3
• ISSN: 1567-5769; 1878-1705
• DOI: 10.1016/j.intimp.2023.111474

•Hepatic ischemia–reperfusion injury damages hepatocytes through promoting inflammation induced by activating the cGAS-STING pathway.•Hepatic ischemia–reperfusion injury inhibits Sirt3 expression, resulting in the activation of cGAS-STING pathway and enhanced inflammation.•Sirt3 inhibition aggravates hepatocyte damage by promoting nuclear translocation of p65 and facilitating cGAS transcription. Hepatic ischemia–reperfusion injury (IRI) typically manifests during subtotal hepatectomy and inflicts substantial damage to liver function in the perioperative period. Although the central role of cGAS-STING-mediated immune inflammation in hepatocyte damage during hepatic IRI is acknowledged, the precise regulatory mechanisms remain elusive. The current study aims to elucidate how Sirt3 inhibition activates the cGAS-STING pathway and exacerbates hepatocyte damage in hepatic IRI. We established both in vivo and in vitro models by creating hepatic IRI mice model and subjecting AML-12 hepatocyte cell lines to oxygen-glucose deprivation/reperfusion (OGD/R). Hepatic IRI compromised liver and mitochondrial function while elevating cytosolic mitochondrial DNA (mtDNA) levels in hepatocytes. Additionally, both in vivo hepatic IRI and in vitro OGD/R induced increased phosphorylation and activation of cGAS, STING, and IRF3, accompanied by heightened levels of pro-inflammatory factors, including TNF-α, IL-1β, and type I interferon (IFN-β). Importantly, knockdown of cGAS or STING through siRNA effectively attenuated hepatic IRI-induced inflammation and ameliorated liver function in both experimental settings, underscoring the dynamic involvement of the cGAS-STING pathway in hepatic IRI-induced inflammation. Furthermore, we observed a significant reduction in Sirt3 expression following hepatic IRI, both in vivo and in vitro. Then we generated Sirt3-deficient mice and applied Sirt3 knockdown in AML-12 hepatocytes. Notably, Sirt3 deficiency led to increased phosphorylation and activation of cGAS, STING, and IRF3, coupled with elevated TNF-α, IL-1β, and IFN-β levels in both in vivo and in vitro conditions. Moreover, upon silencing various downstream targets of Sirt3, such as transcription factors Sp1, Pu1, and p65, we observed that specifically knocking down p65 in AML-12 hepatocytes reduced cGAS mRNA levels. Co-immunoprecipitation assays confirmed a direct interaction between Sirt3 and p65. The absence of Sirt3 significantly increased nuclear translocation of p65 in mice, whereas