The deglycosylated metabolite of 2,3,5,4'-tetrahydroxystilbene-2-O-β-D- glucoside contributes to immune-mediated hepatotoxicity induced by Polygonum multiflorum.

Polygonum multiflorum (PM) has been reported to cause immune-mediated idiosyncratic liver injury. 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) has been identified as a hepatotoxic constituent responsible for PM-induced hepatotoxicity. Covalent protein modification by reactive metabolites plays a crucial role in herb and drug-induced liver injury. Whether it is essential for the hepatotoxicity of THSG needs further clarification. THSG can be hydrolyzed into its aglycone 2,3,5,4'-tetrahydroxystilbene (THS). This study aims to investigate the impact of THS on liver injury and elucidate its underlying mechanism. Metabolism of THSG and covalent modification of cysteine residues by THS were identified by mass spectrometry and proteomics. Hepatotoxicity and T-cell immune response induced by THS were evaluated in vitro and in vivo. The immunological mechanism was investigated using PBMC from healthy donors. THS was detected in both the liver and blood samples after oral administration of THSG to mice. Cysteine-based covalent modification of glutathione (GSH), glutathione S-transferase Pi (GSTP) and hepatic proteins by THS was identified. Liver injury accompanied by inflammatory cell infiltration and T-cell activation were observed in vivo and in vitro with THS treatment. PBMCs from healthy donors and drug-specific T-cell clones (TCCs) could be activated by THS possibly through the hapten pathway. THS, the deglycosylated metabolite of THSG, functions as a hapten by covalently binding to proteins to induce cellular stress and activate T-cells, which may contribute to PM-induced hepatotoxicity.