Prominent Hepatic Injury in 56-Week-Old Female Mice with Cyclic Guanosine Monophosphate–Adenosine Monophosphate Synthase (cGAS) Deficient

Current preclinical studies evaluating cGAS inhibition as a novel anti-inflammatory strategy rely predominantly on young murine models, leaving the impact of aging largely unexplored. At baseline, aged (56-week-old) female mice, in both WT and cGAS-/- mice, demonstrated more pronounced oxidative stress (malondialdehyde) and diminished antioxidant capacity (glutathione) relative to young (8-week-old) controls. Upon the induction of liver ischemia–reperfusion injury (IRI), the most severe hepatic damage was provoked exclusively in aged cGAS-/- mice. This exacerbated injury was confirmed by elevated liver enzymes, higher histological scores, widespread apoptosis (activated caspase-3), enhanced macrophage accumulation (F4/80+ cells), and increased serum cell-free DNA as a tissue damage marker. Additionally, aged cGAS-/- mice exhibited a significant surge in serum IL-6 and gut barrier dysfunction (FITC-dextran assay) at 6 h post-injury. Mechanistically, while cGAS-/- macrophages showed blunted inflammatory signaling upon lipopolysaccharide (LPS) stimulation, co-incubation with D-galactose, which induces intracellular peroxide accumulation, restored their pro-inflammatory responses to WT levels. Concurrently, starvation protocols revealed that cGAS-/- hepatocytes were more vulnerable to mitochondrial oxidative stress (MitoSOX) than WT cells. Ultimately, aging critically modifies the cGAS-deficient phenotype, warranting the careful re-evaluation of cGAS therapeutic models in aged populations.