Diallyl Trisulfide From Garlic Regulates RAB18 Phase Separation to Inhibit Lipophagy and Induce Cuproptosis in Hepatic Stellate Cells for Antifibrotic Effects

Abstract Liver fibrosis, a common pathological process, severely impacts human health, yet effective treatments are lacking. Cuproptosis, a newly discovered form of cell death induced by copper ions, triggers cytotoxic stress through sulfenylated protein oligomerization and may offer a novel therapeutic strategy for liver fibrosis. However, the mechanisms underlying cuproptosis in liver fibrosis are not well understood. During liver fibrosis progression, hepatic stellate cells (HSCs) activate, proliferate, and secrete extracellular matrix components, contributing to fibrosis. Activated HSCs also undergo lipophagy, the degradation of lipid droplets. The study shows that Ras‐related protein Rab‐18 (RAB18), a protein involved in lipid metabolism, inhibits lipophagy, upregulates Carnitine palmitoyltransferase 1A (CPT1A), and promotes succinylation of dihydrolipoamide dehydrogenase (DLD) at site K320, triggering cuproptosis in HSCs. Diallyl trisulfides (DATs), a garlic‐derived compound, induces phase separation of RAB18 and promotes mitochondrial‐associated membrane structures (MAMs) formation, further accelerating RAB18 phase separation. DATs selectively protects hepatocytes while activating cuproptosis in HSCs. Interfering with RAB18 expression reverses the DATs‐induced inhibition of lipophagy and cuproptosis. These findings, confirmed in primary cells, human liver stellate cells (LX2), rodent models and clinical samples, suggest that DATs, by targeting RAB18 and inducing its phase separation, subsequently inhibit lipophagy and promote cuproptosis, making it a promising therapeutic approach for liver fibrosis.