The metabolomics of acetaminophen toxicity observed in human biofluids and cultured primary human hepatocytes

The mechanisms of acetaminophen toxicity are well-established. However, the use of metabolomics to identify small molecule ( 10 kD) inactivation in primary human hepatocyte cultures is original. By tracking the metabolism of 13C tracers, a metabolomic surrogate of enzyme inactivation due to acetaminophen toxicity was discovered. The enzyme inactivation is likely via arylation by the cytochrome P450 bio-activated acetaminophen metabolic product N-acetyl-para-quinonimine. Furthermore, it was observed that the human hepatocytes appeared to be in a stressed metabolic state, due to the lack of glycolysis or glutaminolysis, even in the presence of high insulin and glucose concentrations. This metabolism was compared to that of primary rat hepatocyte cultures, which did not exhibit these features, likely due to absence of stress inducing hormones prior to hepatocyte isolation. This has yet to be described in the literature, likely because this is the first report of the use of 13C-labeled nutrients in primary human hepatocyte cultures

Metabolic Flux Profiling of Reaction Modules in Liver Drug Transformation. Pac Symp Biocomput

With appropriate models, the metabolic profile of a biological system may be interrogated to obtain both significant discriminatory markers as well as mechanistic insight into the observed phenotype. One promising application is the analysis of drug toxicity, where a single chemical triggers multiple responses across cellular metabolism. Here, we describe a modeling framework whereby metabolite measurements are used to investigate the interactions between specialized cell functions through a metabolic reaction network. As a model system, we studied the hepatic transformation of troglitazone (TGZ), an antidiabetic drug withdrawn due to idiosyncratic hepatotoxicity. Results point to a welldefined TGZ transformation module that connects to other major pathways in the hepatocyte via amino acids and their derivatives. The quantitative significance of these connections depended on the nutritional state and the availability of the sulfur containing amino acids. 1