Identification of integrative hepatotoxicity induced by lysosomal phospholipase A2 inhibition of cationic amphiphilic drugs via metabolomics

Drug-induced liver injury (DILI) is a condition caused by drugs that leads to abnormal hepatic function. Hepatotoxicity caused by DILI has been shown to be due to cellular stress, mitochondrial dysfunction, cell necrosis and apoptosis and many types of hepatotoxicity, such as phospholipidosis, steatosis and hepatitis, commonly share intracellular molecular mechanisms. Metabolomics can be useful for mechanism-based toxicity evaluations and has been recently utilized as a scientific technique that can effectively predict the risk factors for chemical substances. To evaluate the key events in hepatotoxicity associated with lysosomal phospholipase A2 (LPLA2) inhibition by cationic amphiphilic drugs (CADs), LPLA2 inhibition assays and phospholipid accumulation assays were performed in HepG2 cells. Additionally, to suggest the integrative molecular mechanisms of hepatotoxicity by CADs, we profiled intracellular metabolites. Cell-based metabolomics was performed using an UPLC-Orbitrap-MS instrument equipped with heated electrospray ionization in positive and negative ion modes. As a result, CADs such as amiodarone, fluoxetine, chlorpromazine and tamoxifen significantly inhibited LPLA2 and accumulated phospholipids. In metabolomics, a total of 17 significant metabolites were identified, and the changed metabolite types were as follows: nucleotide sugars, conjugated bile acids, branched-chain amino acids, polyamine biosynthesis, and long-chain fatty acid and glycerophospholipid metabolism. From these data, it was suggested that the integrative mechanism of DILI could be verified and that a toxicological approach is possible using metabolomics.