Triptolide-induced hepatotoxicity is mediated by NLRP3-dependent pyroptosis and inhibited by mitophagy

This study investigated the regulatory effects of triptolide on PTEN-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy and NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated pyroptosis. Furthermore, it aimed to elucidate the potential relationship between mitophagy and pyroptosis in triptolide-induced hepatotoxicity. We established in vitro and in vivo models using a human normal hepatic cell line, HL7702, and C57BL/6J mice treated with triptolide. Furthermore, mitophagy inhibition experiments were performed using cyclosporin A, chloroquine, or PINK1 knockdown. The results revealed that triptolide induced severe hepatic cell damage accompanied by mitochondrial impairment. PINK1/Parkin-mediated mitophagy was concurrently induced, which manifested via increased levels of PINK1, Parkin, and microtubule-associated protein light chain 3II, and decreased p62. Moreover, triptolide increased the levels of NLRP3-mediated pyroptotic markers, including NLRP3, caspase-1, cleaved caspase-1, and gasdermin D N-terminal fragment, and promoted the extracellular release of IL-1β and IL-18. Notably, mitophagy inhibition further augmented the triptolide-induced hepatic cell pyroptosis and worsened hepatic damage. Taken together, our results indicate that the triptolide-activated pyroptosis induces hepatotoxicity, which is subsequently suppressed by mitophagy. Therefore triptolide-induced hepatotoxicity is mediated by NLRP3-dependent pyroptosis and inhibited by mitophagy.