The role of inflammasome activation in Triptolide-induced acute liver toxicity

Triptolide (TP), the major active compound derived from the traditional Chinese medicine Tripterygium wilfordii Hook. F, possesses an excellent pharmacological profile of immunomodulatory and anti-tumor activities. However, the application of TP was restricted due to its narrow therapeutic window and side effects, especially its hepatotoxicity. This study was designed to investigate the role of inflammasome in TP-induced acute liver toxicity. After the administration of TP at the dose of 600 μg/kg for 12 h or 24 h, we examined the serum biochemical parameters, liver histopathological changes, the expression of liver inflammatory factors, and the activation of NLRP3 inflammasome. Mice treated with TP displayed liver injury with a time-dependent increase of serum transaminases and activation of NLRP3 inflammasome, accompanied by the elevation of neutrophils infiltration. Further results implied that the activation of TLR4-Myd88-NF-κB pathway and oxidative stress induced by a single dose of TP (600 μg/kg) might participate in the activation of NLRP3 inflammasome. To investigate whether the activation of inflammasome participates in the liver damage induced by TP, a single dose of Ac-Yvad-Cmk (Caspase-1 inhibitor) was injected before TP administration. Ac-Yvad-Cmk pretreatment effectively prevented the increase of Cleaved Caspase-1 and inhibited the maturity of IL-1β. Additional studies revealed that Ac-Yvad-Cmk pretreatment decreased the recruitment of neutrophils and inhibited the production of massive pro-inflammatory factors. Taken together, our results revealed that activation of inflammasome aggravated the acute liver toxicity induced by TP. Inhibition of inflammasome could serve as a novel therapeutic target for the amelioration of TP-induced hepatotoxicity.