Inhibition of TBK1 by amlexanox attenuates paraquat-induced acute lung injury

The specific mechanism of paraquat (PQ)-induced acute lung injury (ALI) is unclear, though inflammation is a likely contributor. Amlexanox, a TANK binding kinase 1 (TBK1) inhibitor, is a strong anti-inflammatory drug. We investigated the role of TBK1 and the potential therapeutic effect of amlexanox in the pathogenesis of PQ-induced ALI. After 30 mg/kg PQ treatment for 72 h, mouse lung pathological injury occurred, and the protein concentration in alveolar lavage fluid was increased. Next, RAW264.7 mouse macrophages were treated with 100 mu M PQ for 24 h, which decreased cell viability. PQ induced oxidative damage and increased IL-1 beta, IFN beta, NF-kappa Bp65, IRF3, and pTBK1/TBK1 levels in mouse lungs and RAW264.7 cells. Inhibiting the activation of TBK1 with amlexanox (100 mg/kg in mice and 50 mu M in RAW264.7 cells) attenuated mouse lung injury and decreased the protein concentration in alveolar lavage fluid. Further, amlexanox relieved the oxidative damage in mouse lungs and RAW264.7 cells, reduced the levels of inflammatory factors such as IL-1 beta and IFN beta, and inhibited the activation of NF-kappa Bp65 and IRF3. These results suggest that TBK1 plays a key role in the pathogenesis of PQ-induced ALI. Further, amlexanox treatment alleviates PQ-induced ALI by inhibiting the TBK1-NF-kappa B/IRF3 signalling pathway. Our study provides evidence that TBK1 inhibition by amlexanox alleviates PQ-induced ALI and may be a new therapeutic strategy.