Abstract
BACKGROUND & AIMS: Hepatic sinusoidal obstruction syndrome (HSOS) induced by pyrrolizidine alkaloids (PAs) is a life-threatening liver injury for which standardized chronic models are lacking. This study aimed to establish a clinically relevant chronic PA-HSOS murine model and to identify potential therapeutic targets. METHODS: A 28-day model was developed using key alkaloids from Gynura segetum (seneciphylline, senecionine, and N-oxide derivatives), mirroring human exposure. Disease characteristics were evaluated via hematological profiling, CT imaging, histopathology, and transcriptomics. A hepatocyte-liver sinusoidal endothelial cell (LSEC) co-culture system was used to validate molecular mechanisms. TM5441, a Serpine1 inhibitor, was evaluated for therapeutic efficacy. RESULTS: The model faithfully recapitulated human HSOS, characterized by elevated liver enzymes (ALT, 1.6-fold, p <0.001; AST, 5.7-fold, p <0.0001, n = 6), coagulation dysfunction (prothrombin time, 1.5-fold, p <0.001; activated partial thromboplastin time, 1.1-fold, p <0.05; D-dimer, 8.4-fold, p <0.0001, n = 6), increased liver weight (1.2-fold, p <0.0001, n = 6), reduced VE-cadherin expression (0.28-fold, p <0.001, n = 6), and sinusoidal fibrosis. RNA sequencing identified Serpine1 as the most significantly upregulated gene (|log(2)fold-change| ≥2, p <0.05) associated with p53 signaling. Serum Serpine1 was elevated in patients (5.0-fold, p <0.01, n = 16,) and mice (3.7-fold, p <0.001, n = 6) with PA-HSOS. Co-culture confirmed that Serpine1-driven p53 activation (1.8-fold, p <0.01, n = 3) promoted endothelial senescence. TM5441 reduced Serpine1-p53 activity (0.5-fold, p <0.001, n = 6), improved liver function (ALT and AST reduced 30-40%, p <0.001, n = 6), normalized coagulation, restored LSEC integrity (VE-cadherin, 3.2-fold, p <0.001, n = 6), and attenuated inflammation and fibrosis. CONCLUSIONS: This first chronic PA-HSOS murine model closely mirrors human disease and identifies Serpine1 as a critical therapeutic target. Targeting the Serpine1-p53 axis with TM5441 represents a promising strategy to mitigate endothelial injury in PA-HSOS. IMPACT AND IMPLICATIONS: This study establishes a chronic PA-HSOS (pyrrolizidine alkaloid-induced hepatic sinusoidal obstruction syndrome) model that more accurately replicates human disease progression, thereby overcoming the limitations of previous acute models for mechanistic and therapeutic research. The researchers identify Serpine1 as a key regulatory target that could lead to new therapies for PA-HSOS by reducing endothelial senescence and inflammation. These findings provide clinicians and researchers with improved tools for studying drug-induced liver injury and a pathway for translating discoveries into clinical trials. The therapeutic compound TM5441 shows promise for reversing liver dysfunction and vascular damage, while the model itself may aid in the development of better diagnostic criteria and prevention strategies. CLINICAL TRIAL NUMBER: Not applicable.