Mechanistic aspects and novel biomarkers of responder and non-responder phenotypes in galactosamine-induced hepatitis.
ABSTRACT The amino sugar galactosamine (galN) induces alterations in the hepatic uridine nucleotide pool and has been widely used as a model of human viral hepatitis. Histopathological and clinical chemistry analyses of a cohort of rats following administration of galN revealed extreme interindividual variability in the extent of the toxic response which enabled classification of 'responder' and 'non-responder' phenotypes. An integrative metabolic profiling approach was applied to characterize biomarkers of exposure to galN in urine, serum, feces and liver from responders and non-responders. The presence of N-acetylglucosamine and galN in the urine correlated with the occurrence and extent of toxic response. Conversely, the novel identification of galN-pyrazines in the feces of non-responders and their virtual absence in the feces of responders suggests an alternative means of distribution and metabolism of galN in non-responders. The absence of the UDP-hexosamines in the liver of non-responders further supports differential metabolism of galN and suggests an ability of non-responders to avoid UDP-glucose depletion. An observed disturbance of gut microbial derived metabolites in the urine and feces of non-responders may suggest a role of the microflora in reducing the effective dose of galN. This systems level metabonomic approach has provided new mechanistic insights into differential response to galN and is widely applicable to the study of interindividual variation in metabolism for any xenobiotic intervention.
- SourceAvailable from: Huiru Tang[show abstract] [hide abstract]
ABSTRACT: CCl(4)-induced metabonomic changes have been extensively studied for mammalian liver, and such changes have not been reported for other organs. To investigate the CCl(4) effects on other organs, we analyzed the CCl(4)-induced metabonomic changes in rat kidney, lung, and spleen using (1)H NMR-based metabonomics approaches with complementary information on serum clinical chemistry and histopathology. We found that acute CCl(4) exposure caused significant level elevation for creatine and decline for glucose, taurine, trimethylamine, uridine, and adenosine in rat kidney. CCl(4)-treatment also induced elevation of amino acids (isoleucine, leucine, valine, threonine, alanine, lysine, ornithine, methionine, tyrosine, phenylalanine, and histidine), creatine, and betaine in rat lung together with depletion of glycogen, glucose, taurine, glycine, and hypoxanthine. Furthermore, CCl(4) caused elevation of lactate, alanine, betaine, and uracil in rat spleen accompanied with decline for glucose, choline, and hypoxanthine. These observations indicated that CCl(4) caused oxidative stresses to multiple rat organs and alterations of their functions including renal osmotic regulations, accelerated glycolysis, and protein and nucleotide catabolism. These findings provide essential information on CCl(4) toxicity to multiple rat organs and suggest that systems toxicological views are required for metabonomic studies of toxins by taking many other organs into consideration apart from so-called targeted ones.Journal of Proteome Research 05/2012; 11(7):3848-59. · 5.06 Impact Factor
- ALTEX. 01/2013; 2:209-225.
- [show abstract] [hide abstract]
ABSTRACT: Metabolomics, the comprehensive analysis of metabolites in a biological system, provides detailed information about the biochemical/physiological status of a biological system, and about the changes caused by chemicals. Metabolomics analysis is used in many fields, ranging from the analysis of the physiological status of genetically modified organisms in safety science to the evaluation of human health conditions. In toxicology, metabolomics is the -omics discipline that is most closely related to classical knowledge of disturbed biochemical pathways. It allows rapid identification of the potential targets of a hazardous compound. It can give information on target organs and often can help to improve our understanding regarding the mode-of-action of a given compound. Such insights aid the discovery of biomarkers that either indicate pathophysiological conditions or help the monitoring of the efficacy of drug therapies. The first toxicological applications of metabolomics were for mechanistic research, but different ways to use the technology in a regulatory context are being explored. Ideally, further progress in that direction will position the metabolomics approach to address the challenges of toxicology of the 21st century. To address these issues, scientists from academia, industry, and regulatory bodies came together in a workshop to discuss the current status of applied metabolomics and its potential in the safety assessment of compounds. We report here on the conclusions of three working groups addressing questions regarding 1) metabolomics for in vitro studies 2) the appropriate use of metabolomics in systems toxicology, and 3) use of metabolomics in a regulatory context.ALTEX. 01/2013; 30(2):209-25.