Rutin attenuates liver fibrosis via the IRG1-itaconate-Nrf2 axis

Liver fibrosis is a common consequence of chronic liver injury, driven by persistent inflammation, oxidative stress, and excessive extracellular matrix deposition. The natural flavonoid rutin possesses antioxidant and anti-inflammatory properties and has shown hepatoprotective potential; however, its anti-fibrotic mechanism remains incompletely understood. This study aimed to investigate the protective effects of rutin and its underlying molecular mechanism in a carbon tetrachloride (CCl₄)-induced mouse model of liver fibrosis, with a particular focus on the role of immune-responsive gene 1 (IRG1).

Liver fibrosis was induced in mice by CCl₄ administration. Hepatic injury, collagen deposition, inflammatory activation, and oxidative stress were evaluated using histological, biochemical, molecular, and transcriptomic approaches. The involvement of IRG1 was assessed by employing IRG1-deficient mice. Direct binding between rutin and IRG1 was examined through molecular docking, molecular dynamics simulations, and the cellular thermal shift assay (CETSA).

Rutin treatment markedly alleviated CCl₄-induced hepatic injury, fibrotic deposition, inflammatory cytokine production, and reactive oxygen species accumulation. Mechanistically, rutin directly bound to and stabilized IRG1, which was associated with enhanced IRG1 enzymatic activity and increased endogenous itaconate production. This led to activation of Nrf2-mediated antioxidant signaling and suppression of NLRP3 inflammasome activation. Importantly, the protective effects of rutin were largely abolished in IRG1-deficient mice, confirming that IRG1 is essential for rutin-mediated hepatoprotection.

These findings identify rutin as a potential anti-fibrotic agent that targets the IRG1/itaconate axis to coordinate antioxidant and anti-inflammatory responses during liver fibrosis.