Metabolic characterization of the early stage of hepatic fibrosis in rat using GC‐TOF/MS and multivariate data analyses

Abstract

The aim of this study was to explore the changes in the urine metabolic spectrum in rats with the early stage of liver fibrosis using gas chromatography-time of flight/mass spectrometry (GC-TOF/MS), try to search for potential biomarkers and elucidate the probably metabonomic pathogenesis. The early stage of liver fibrosis was established with a single subcutaneous injection of carbon tetrachloride twice each week for 4 weeks continuously. At the end of the experiment, GC-TOF/MS technology with multivariate statistical approaches such as principal component analysis, partial least squares-discriminant analysis and orthogonal partial least squares-discriminant analysis was used to analyze the changes in the metabolic spectrum trajectory and identify potential biomarkers. Twelve potential biomarkers in the model group, such as succinic acid, threonine and lactose, were selected, which indicate that the metabonomic pathogenesis of the early stage of liver fibrosis may be related to disorders of energy metabolism, amino acid metabolism and fatty acid metabolism.

Identification of key metabolic changes during liver fibrosis progression in rats using a urine and serum metabolomics approach

“…L-tryptophan is an essential amino acid necessary for protein biosynthesis and is mostly metabolized via the kynurenine (Kyn) and serotonin pathways. Biosynthesis of reactive oxygen species (ROS) molecules plays a central role in the pathogenesis of liver damage and fibrosis 20 , 24 . The previous study suggested that L-tryptophan exacerbated the hepatic steatosis, ROS production, liver injury and fibrosis induced by a high-fat and high-fructose diet in mice 25 .…”

“…Therefore, KYNA most likely exerts an anti-inflammatory effect 29 . KYNA is also an endogenous antioxidant that can scavenge hydroxyl radicals and peroxynitrite 20 . Further, there is evidence that reduced concentrations of KYNA can be found in some types of tissue fibrosis, such as atherosclerosis and renal fibrosis 9 , 29 .…”

“…reported that lipid accumulation and a loss of insulin action resulted in the elevation of the oxidative and anaplerotic pathways of the hepatic TCA cycle in mice, which progressed to insulin resistance and a fatty liver due to a high-fat diet 34 . However, liver fibrosis occurred due to the on-going liver damage induced by oxidative stress, and the TCA cycle was slowed by cellular regulation to reduce the natural production of ROS; this effect has been related to liver diseases caused by various mechanisms 20 . Similarly, in our study, the model group showed significantly decreased urinary isocitric acid (TCA cycle intermediates) at weeks 4, 6 and 8 and significantly accumulated cis-aconitic acid (TCA cycle intermediates) at weeks 2 and 8 compared with the normal group (Supplementary Fig.…”

“…Repeated injections of CCl 4 cause liver damage, inflammation and fibrosis in rats that are clinically similar to the human pathology of liver fibrosis, as assessed by serum analysis and histological staining 19 . To data, this model has been used for the elucidation of the mechanism of underlying the pathogenesis of liver fibrosis and diagnostic biomarker discovery 20 – 22 . Nevertheless, these studies have limited value in identifying changes in biomarkers of hepatic fibrosis and for monitoring the entire development and disease progression process.…”

Technological advances in current metabolomics and its application in tradition Chinese medicine

“…35 MS (especially Q-TOF) also helps to identify previously uncharacterized metabolites. 13,36,37 MS in quantitative analysis of small molecules has been established, unlike its application to proteomics. Due to the complexity of metabolites and hundreds of metabolites therein, highresolution MS has combined with advanced and highthroughput separation techniques, but not exclusively, to perform these measurements.…”