SETDB1 in Macrophage Protects the Liver from IRI by Inhibiting the P2RX7-Mediated Pyroptosis Pathway

Aims: Liver ischemia-reperfusion injury (IRI) is a sterile inflammatory process that contributes significantly to graft rejection following liver transplantation. Although SET domain bifurcated histone lysine methyltransferase 1 (SETDB1) is known to preserve genomic stability and restrain inflammation under oxidative stress, its immunoregulatory function in myeloid cells during liver IRI has not been elucidated. This study aimed to investigate the role and mechanism of SETDB1 in regulating macrophage-driven inflammatory responses in liver IRI. Results: Myeloid-specific SETDB1 knockout (SETDB1 cKO) mice exhibited exacerbated liver injury, increased infiltration of pro-inflammatory macrophages and neutrophils, and amplified inflammatory responses compared with SETDB1 fl/fl controls. Depletion of macrophages alleviated liver damage, reduced neutrophil infiltration and hepatocyte apoptosis, and eliminated the excessive injury observed in SETDB1 cKO mice. Mechanistically, SETDB1 suppressed the expression of purinergic receptor P2X7 (P2RX7). Pharmacological inhibition of P2RX7 with oxidized adenosine triphosphate significantly attenuated liver injury and macrophage infiltration in SETDB1 cKO mice. In vitro assays confirmed that SETDB1 inhibited the P2RX7/Caspase-1/Gasdermin D (GSDMD) pathway in macrophages, thereby limiting pyroptosis and inflammation. Innovation: This study identifies SETDB1 as a previously unrecognized regulator of macrophage pyroptosis during liver IRI. By linking epigenetic regulation to suppression of the P2RX7/Caspase-1/GSDMD pathway, our findings provide novel mechanistic insight into how SETDB1 protects against sterile liver inflammation. Conclusion: SETDB1 plays a pivotal role in protecting the liver from IRI by restraining macrophage-mediated pyroptosis and inflammation. These findings suggest that targeting the SETDB1/P2RX7/Caspase-1/GSDMD axis may represent a promising therapeutic strategy for mitigating liver IRI and improving transplant outcomes. Antioxid. Redox Signal. 45, 133–148.