Liver-Directed Cyp2e1 RNA Interference Attenuates Hepatotoxicity Induced by Triptolide, a Bioactive Diterpenoid from Tripterygium wilfordii Hook. f.

Objectives: Triptolide (TP), a bioactive diterpenoid from Tripterygium wilfordii Hook. f., has pharmacological activity, but repeated exposure is limited by hepatotoxicity. CYP2E1 is a hepatic metabolic-redox enzyme linked to oxidative liver injury. This study evaluated whether liver-directed Cyp2e1 RNA interference mitigates TP-induced subacute hepatotoxicity without evidence of a marked reduction in short-term systemic TP exposure. Methods: Cyp2e1-targeting siRNA was encapsulated in lipid nanoparticles (si-Cyp2e1 LNPs) and validated for hepatic CYP2E1 protein knockdown in female C57BL/6J mice. Subacute liver injury was induced by oral TP at 800 μg/kg/day for 7 days. Prophylactic and concurrent si-Cyp2e1 regimens were evaluated using serum transaminases, gross liver morphology, H&E histopathology with blinded semi-quantitative scoring, oxidative-stress indices, RNA-seq, RT-qPCR, Western blotting, and exploratory LC-MS/MS pharmacokinetic analysis. Results: si-Cyp2e1 LNPs showed favorable nanoscale properties and robust hepatic CYP2E1 protein knockdown. Both regimens reduced ALT/AST elevations, improved gross liver appearance and histological injury scores, decreased hepatic ROS and malondialdehyde, and restored glutathione and superoxide dismutase. Transcriptomic and molecular analyses indicated TP-associated PI3K/AKT activation and reduced PI3K/AKT phosphorylation after si-Cyp2e1 treatment. Exploratory pharmacokinetic profiling showed a lower early plasma TP peak, whereas AUC0–t and AUC0–∞ appeared broadly comparable within the 0–3 h observation window. Conclusions: Liver-directed Cyp2e1 silencing provided proof-of-concept hepatoprotection against repeated TP exposure, accompanied by redox recovery and attenuated stress-associated PI3K/AKT activation. Because CYP2E1 enzymatic activity, TP-derived reactive metabolites, and pathway causality were not directly tested, these findings should be interpreted as pathway-associated evidence requiring further validation.