Fucoidan Attenuates Lead-Induced Liver Injury Associated with IGFBP1 and Gut Microbiota-Derived Tryptophol Metabolism

Lead (Pb) exposure induces liver injury through oxidative stress, inflammation, and gut-liver axis disruption. This study evaluated the protective effects and associated mechanisms of fucoidan (FU) against Pb-induced liver injury in mice. C57BL/6 mice were exposed to lead acetate and treated with FU. High-dose FU (FU-H) improved food intake, body weight, and liver index; decreased Pb levels in serum and liver; and increased fecal Pb content. Compared with the Model group, FU-H reduced serum ALT, AST, and ALP by 54.8%, 38.6%, and 21.7%, respectively. FU-H restored hepatic SOD and GSH by 10.9% and 46.5% and decreased hepatic MDA by 45.9%; it also restored serum SOD and GSH by 30.4% and 24.0%, decreased serum MDA by 19.6%, and suppressed TNF-α, IL-6, and IL-1β by 15.7%, 21.1%, and 14.9%, respectively. Integrated RNA sequencing and network toxicology suggested that insulin-like growth factor-binding protein 1 (IGFBP1) may be associated with FU-mediated protection, and recombinant IGFBP1 partly weakened FU-associated hepatoprotection. Moreover, 16S rRNA sequencing and untargeted metabolomics showed that FU reshaped Pb-disrupted gut microbiota and altered fecal tryptophan metabolism. Exogenous tryptophol supplementation partially alleviated Pb-induced liver injury. Overall, FU protection was associated with reduced Pb burden, IGFBP1-related redox modulation, and gut microbiota-derived tryptophol metabolism.