Targeting DNA fragment extrusion: a new therapeutic avenue for CCl

backgroundLiver injury is a major health concern with complex pathogenesis involving oxidative stress, apoptosis, and mitochondrial dysfunction. The carbon tetrachloride (CCl₄)-induced liver injury model is widely used, as CCl₄ is metabolized in mitochondria, generating reactive oxygen species that cause DNA damage. This study employed the novel in situ hybridization chain reaction (isHCR) method to investigate DNA fragment release dynamics during CCl₄ injury and evaluated the therapeutic potential of NIM811, a mitochondrial permeability transition pore inhibitor. METHODS AND

resultsC57BL/6 male mice were injected intraperitoneally with 10% CCl₄, with NIM811 (5 mg/kg) administered immediately post-injury. isHCR analysis revealed that DNA fragments first accumulated within hepatocyte mitochondria at 3–9 h post-injury, co-localizing with HSP60 (mitochondrial marker), and became widely distributed in cytoplasm and nuclei by 18 h. Combined isHCR/TUNEL assays demonstrated that isHCR detected apoptosis earlier than TUNEL. DNA fragments were subsequently phagocytosed by sinusoidal endothelial cells (CD31⁺), hepatic macrophages (Iba-1⁺), and portal fibroblasts (PDGFRβ⁺). NIM811 treatment significantly reduced serum ALT and AST levels (P < 0.05), decreased hepatocyte death and DNA fragment release (P < 0.05), inhibited cGAS-STING pathway activation in macrophages, and reduced TNF-α, IL-6, and fibronectin expression, thereby attenuating liver fibrosis.

conclusionsThis study demonstrates for the first time that mitochondrial DNA fragmentation occurs in CCl₄-induced liver injury and that released hepatocyte DNA fragments trigger inflammation via macrophage cGAS-STING activation. NIM811 prevents mitochondrial DNA efflux, suppresses the cGAS-STING pathway, and mitigates liver fibrosis, identifying it as a promising therapeutic strategy for acute liver injury.