Fraxinellone mitigates acute lung injury by targeting HIF-1α to suppress pyroptosis and inflammation

Acute pulmonary contusion (APC), a life-threatening trauma-associated condition, currently lacks targeted pharmacological therapies. Fraxinellone (FRA) inhibits Hypoxia-inducible factor-1α (HIF-1α) synthesis, but its binding mechanism and anti-APC action remain unclear. This study was designed to assess the therapeutic potential of FRA, a natural substance with known anti-inflammatory properties, as a means of attenuating APC progression through the inhibition of HIF-1α.

An in vivo APC model was generated via weight-drop lung injury in C57BL/6 mice, and an in vitro model was established using thrombin (THR)-injured MLE-12 cells. The efficacy of FRA (10 μM in vitro; 5 mg/kg in vivo) was evaluated through cell viability assays, measurement of inflammatory cytokines via enzyme-linked immunosorbent assay (ELISA), histopathological examination, and molecular analyses including Western blot (WB) and real-time quantitative polymerase chain reaction (RT-qPCR). Mechanistic validation was performed through HIF-1α siRNA knockdown and mutation, ML228-mediated activation, and molecular docking simulations.

FRA notably diminished APC severity by reducing pulmonary edema (wet/dry ratio), lowering pro-inflammatory cytokine levels ((interleukin-1β [IL-1β], interleukin-6 [IL-6], interleukin-18 [IL-18]), and decreasing pyroptosis markers (NOD-like receptor family pyrin domain containing 3 [NLRP3], gasdermin D [GSDMD]) in both in vitro and in vivo models. Molecular docking revealed FRA binding to HIF-1α at Arg258, and HIF-1α activation abrogated the protective effects of FRA. HIF-1α knockdown and mutation reproduced the anti-pyroptotic effects of FRA, confirming pathway specificity.

FRA mitigates APC progression by targeting HIF-1α to suppress NLRP3/GSDMD-mediated pyroptosis and inflammation, providing a novel therapeutic approach for trauma-induced lung injury.