STING Induces Liver Ischemia-Reperfusion Injury by Promoting Calcium-Dependent Caspase 1-GSDMD Processing in Macrophages

Abstract

Objectives. Although a recent study reported that stimulator of interferon genes (STING) in macrophages has an important regulatory effect on liver ischemia-reperfusion injury (IRI), the underlying mechanism of STING-dependent innate immune activation in liver macrophages (Kupffer cells, KCs) remains unclear. Here, we investigated the effect of STING on liver macrophage pyroptosis and the associated regulatory mechanism of liver IRI. Methods. Clodronate liposomes were used to block liver macrophages. AAV-STING-RNAi-F4/80-EGFP, an adenoassociated virus (AAV), was transfected into the portal vein of mice in vivo, and the liver IRI model was established 14 days later. In vitro, liver macrophages were treated with STING-specific siRNA, and a hypoxia-reoxygenation (H/R) model was established. The level of STING was detected via Western blotting (WB), RT-PCR, and immunostaining. Liver tissue and blood samples were collected. Pathological changes in liver tissue were detected by hematoxylin and eosin (H&E) staining. Macrophage pyroptosis was detected by WB, confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and enzyme-linked immunosorbent assay (ELISA). The calcium concentration was measured by immunofluorescence and analyzed with a fluorescence microplate reader. Results. The expression of STING increased with liver IRI but decreased significantly after the clodronate liposome blockade of liver macrophages. After knockdown of STING, the activation of caspase 1-GSDMD in macrophages and liver IRI was alleviated. More interestingly, hypoxia/reoxygenation (H/R) increased the calcium concentration in liver macrophages, but the calcium concentration was decreased after STING knockdown. Furthermore, after the inhibition of calcium in H/R-induced liver macrophages by BAPTA-AM, pyroptosis was significantly reduced, but the expression of STING was not significantlydecreased. Conclusions. Knockdown of STING reduces calcium-dependent macrophage caspase 1-GSDMD-mediated liver IRI, representing a potential therapeutic approach in the clinic.

Pyroptosis: A Newly Discovered Therapeutic Target for Ischemia-Reperfusion Injury

“…In addition, in steatotic livers, I/R injury induces pyroptosis and aggravates hepatic injury through caspase-1 activation [ 109 ]. Furthermore, it has been suggested that the stimulator of interferon genes (STING) could exacerbate liver I/R injury by facilitating calcium-dependent caspase-1-GSDMD processing in macrophages [ 110 ]. Finally, Alaa et al found that the application of octreopeptide and melatonin can reduce inflammasome-induced pyroptosis by the iTLR4-NF-κB-NLRP3 pathway, thus attenuating hepatic I/R injury [ 111 ].…”

PPM1G regulates hepatic ischemia/reperfusion injury through STING‐mediated inflammatory pathways in macrophages

“…As previously reported, STING has a relationship with upstream noncoding miRNAs, which base pair with downstream STING mRNA, culminating in reduced type I IFN production and restoration of liver function 30 . Moreover, calcium‐dependent caspase 1‐GSDMD‐mediated pyroptosis and the NLRP3‐mediated inflammasome were amplified following STING activation in hepatic IRI 31,32 . However, not exclusive to the liver, the STING pathway appears to be overactivated as an accelerator of IRI in multiple other organs, including the brain and gut 33,34 .…”

MLKL deficiency attenuated hepatocyte oxidative DNA damage by activating mitophagy to suppress macrophage cGAS-STING signaling during liver ischemia and reperfusion injury

“…We previously showed that liver IR triggers macrophage STING activation [ 11 ], and STING inhibition attenuates different types of sterile inflammatory liver injuries, including liver IR [ 12 , 28 ]. A recent study reported that STING induces liver IR injury by promoting calcium-dependent caspase 1-Gasdermin D processing in macrophages [ 29 ]. Suppression of STING signaling alleviates liver inflammation and IR injury [ 30 ].…”