Activation of Rab7-mediated lipophagy is required for triptolide to induce ferroptosis in hepatic cells

The aim of this study was to investigate the regulation of triptolide on Rab7-mediated lipophagy to elucidate the potential association between lipophagy and ferroptosis in triptolide-induced hepatotoxicity. Human normal liver HL7702 cells and C57BL/6J mice were treated with triptolide to establish in vitro and in vivo models. The results revealed that triptolide caused a severe hepatic cell damage in vitro and in vivo. Concurrently, triptolide induced the remarkable activation of Rab7-mediated lipophagy, as evidenced by the decreased levels of lipid droplets and p62, the increased Rab7, microtubule-associated protein light chain 3Ⅱ (LC3Ⅱ) and phosphorylated adenosine monophosphate-activated protein kinase (AMPK) levels, as well as the increased colocalization of LC3 and Rab7 proteins. Moreover, triptolide obviously increased the levels of ferroptotic markers, including MDA, iron, prostaglandin endoperoxide synthase 2, and induced GSH and GPX4 exhaustion and oxidative stress in hepatic cells. Importantly, the inhibition of lipophagy mitigated ferroptosis and alleviated the hepatic cell damage induced by triptolide. our results demonstrated that triptolide-activated lipophagy with Rab7 serves as a pivotal factor in triggering ferroptosis and exacerbating hepatoxicity. The manipulation of lipophagy is thus a potential therapeutic strategy for ameliorating triptolide-induced hepatotoxicity.