TAK1 deficiency promotes liver injury and tumorigenesis via ferroptosis and macrophage cGAS-STING signalling.

Background & Aims: Oxidative stress-mediated ferroptosis and macrophage-related inflammation play an important role in various liver diseases. Here, we explored if and how hepatocyte ferroptosis regulates macrophage stimulator of interferon genes (STING) activation in the development of spontaneous liver damage, fibrosis, and tumorigenesis.

Methods: We used a transforming growth factor-beta-activated kinase 1 (TAK1) deficiency-induced model of spontaneous liver damage, fibrosis, and tumorigenesis to investigate hepatocyte ferroptosis and its impact on macrophage STING signalling. Primary hepatocytes and macrophages were used for experiments.

Results: Significant liver injury and increased numbers of intrahepatic M1 macrophages were found in hepatocyte-specific TAK1-deficient (TAK1) mice, peaking at 4 weeks and gradually decreasing at 8 and 12 weeks. Meanwhile, activation of STING signalling was observed in livers from TAK1 mice at 4 weeks and had decreased at 8 and 12 weeks. Treatment with a STING inhibitor promoted macrophage M2 polarisation and alleviated liver injury, fibrosis, and tumour burden. TAK1 deficiency exacerbated liver iron metabolism in mice with a high-iron diet. Moreover, consistent with the results from single-cell RNA-Seq dataset, TAK1 mice demonstrated an increased oxidative response and hepatocellular ferroptosis, which could be inhibited by reactive oxygen species scavenging. Suppression of ferroptosis by ferrostatin-1 inhibited the activation of macrophage STING signalling, leading to attenuated liver injury and fibrosis and a reduced tumour burden. Mechanistically, increased intrahepatic and serum levels of 8-hydroxydeoxyguanosine were detected in TAK1 mice, which was suppressed by ferroptosis inhibition. Treatment with 8-hydroxydeoxyguanosine antibody inhibited macrophage STING activation in TAK1 mice.

Conclusions: Hepatocellular ferroptosis-derived oxidative DNA damage promotes macrophage STING activation to facilitate the development of liver injury, fibrosis, and tumorigenesis. Inhibition of macrophage STING may represent a novel therapeutic approach for the prevention of chronic liver disease.

Impact And Implications: The precise mechanism by which hepatocyte ferroptosis regulates macrophage STING activation in the progression of liver damage, fibrosis, and tumorigenesis remains unclear. Herein, we show that deletion of TAK1 in hepatocytes caused oxidative stress-mediated ferroptosis and macrophage-related inflammation in the development of spontaneous liver injury, fibrosis, and hepatocellular carcinoma.