Evaluation of taurine as a biomarker of liver damage in paracetamol poisoning

The Evolution of Circulating Biomarkers for Use in Acetaminophen/Paracetamol-Induced Liver Injury in Humans: A Scoping Review

Acetaminophen (APAP) is a widely used drug, but overdose can cause severe acute liver injury. The first reports of APAP hepatotoxicity in humans were published in 1966, shortly after the development of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as the first biomarkers of liver injury as opposed to liver function. Thus, the field of liver injury biomarkers has evolved alongside the growth in APAP hepatotoxicity incidence. Numerous biomarkers have been proposed for use in the management of APAP overdose patients in the intervening years. Here, we comprehensively review the development of these markers from the 1960s to the present day and briefly discuss possible future directions.

Systemic perturbations in amino acids/amino acid derivatives and tryptophan pathway metabolites associated with murine influenza A virus infection

BACKGROUND

Influenza A virus (IAV) is the only influenza virus causing flu pandemics (i.e., global epidemics of flu disease). Influenza (the flu) is a highly contagious disease that can be deadly, especially in high-risk groups. Worldwide, these annual epidemics are estimated to result in about 3 to 5 million cases of severe illness and in about 290,000 to 650,000 respiratory deaths. We intend to reveal the effect of IAV infection on the host's metabolism, immune response, and neurotoxicity by using a mouse IAV infection model.

METHODS

51 metabolites of murine blood plasma (33 amino acids/amino acid derivatives (AADs) and 18 metabolites of the tryptophan pathway) were analyzed by using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry with Electrospray Ionization at the acute (7 days post-infection (dpi)), resolution (14 dpi), and recovery (21 dpi) stages of the virus infection in comparison with controls.

RESULTS

Among the 33 biogenic amino acids/AADs, the levels of five amino acids/AADs (1-methylhistidine, 5-oxoproline, α-aminobutyric acid, glutamine, and taurine) increased by 7 dpi, whereas the levels of ten amino acids/AADs (4-hydroxyproline, alanine, arginine, asparagine, cysteine, citrulline, glycine, methionine, proline, and tyrosine) decreased. By 14 dpi, the levels of one AAD (3-methylhistidine) increased, whereas the levels of five amino acids/AADs (α-aminobutyric acid, aminoadipic acid, methionine, threonine, valine) decreased. Among the 18 metabolites from the tryptophan pathway, the levels of kynurenine, quinolinic acid, hydroxykynurenine increased by 7 dpi, whereas the levels of indole-3-acetic acid and nicotinamide riboside decreased.

CONCLUSIONS

Our data may facilitate understanding the molecular mechanisms of host responses to IAV infection and provide a basis for discovering potential new mechanistic, diagnostic, and prognostic biomarkers and therapeutic targets for IAV infection.

Plasma Concentration of Taurine Changes following Acetaminophen Overdose in Male Patients during Hospitalization

Changes in plasma concentration of taurine during hospitalization of acetaminophen poisoned patients have not been studied. Hepatotoxicity is a common consequence of acetaminophen overdose that may lead to acute liver failure. Numerous biomarkers for drug-induced liver injury have been explored. All biomarkers are usually obtainable 48 h following acetaminophen overdose. We have already introduced taurine as a non-specific early biomarker of acetaminophen overdose. This study aimed to follow up changes in plasma concentration of taurine during the first three days of acetaminophen overdose. Sixty-four male patients suffering from acetaminophen overdose were selected for the study. Four blood samples were taken from the patients every 12 h. Sixty blood samples were also taken from sixty healthy humans. The plasma concentration of taurine in both groups was analyzed an already developed HPLC method. Analysis of regression showed a significant correlation between means of plasma concentrations of taurine and acetaminophen, aspartate aminotransferase, Alanine aminotransferase, glutathione peroxidase, and prothrombin time during hospitalization. The high plasma concentration of taurine, 6 h or more after acetaminophen overdose, could be a useful early indicator of liver damage.

Protective role of taurine against oxidative stress (Review)

Taurine is a fundamental mediator of homeostasis that exerts multiple roles to confer protection against oxidant stress. The development of hypertension, muscle/neuro‑​associated disorders, hepatic cirrhosis, cardiac dysfunction and ischemia/reperfusion are examples of some injuries that are linked with oxidative stress. The present review gives a comprehensive description of all the underlying mechanisms of taurine, with the aim to explain its anti‑oxidant actions. Taurine is regarded as a cytoprotective molecule due to its ability to sustain normal electron transport chain, maintain glutathione stores, upregulate anti‑oxidant responses, increase membrane stability, eliminate inflammation and prevent calcium accumulation. In parallel, the synergistic effect of taurine with other potential therapeutic modalities in multiple disorders are highlighted. Apart from the results derived from research findings, the current review bridges the gap between bench and bedside, providing mechanistic insights into the biological activity of taurine that supports its potential therapeutic efficacy in clinic. In the future, further clinical studies are required to support the ameliorative effect of taurine against oxidative stress.

Taurine ameliorates thioacetamide induced liver fibrosis in rats via modulation of toll like receptor 4/nuclear factor kappa B signaling pathway

Liver fibrosis is a significant health problem that can cause serious illness and death. Unfortunately, a standard treatment for liver fibrosis has not been approved yet due to its complicated pathogenesis. The current study aimed at assessing the anti-fibrotic effect of taurine against thioacetamide induced liver fibrosis in rats through the modulation of toll like receptor 4/nuclear factor kappa B signaling pathway. Both concomitant and late taurine treatment (100 mg/kg, IP, daily) significantly reduced the rise in serum ALT and AST activities and significantly reversed the decrease in serum albumin and total protein. These results were confirmed by histopathological examinations and immunehistochemical inspection of α-SMA, caspase-3 and NF-κB. The antioxidant potential of taurine was verified by a marked increase of GSH content and a reduction of MDA level in liver tissue. The anti-fibrotic effects of taurine were evaluated by investigating the expression of TLR4, NF-κB. The protein levels of IL-6, LPS, MyD88, MD2, CD14, TGF-β1 and TNF-α were determined. Docking studies were carried out to understand how taurine interacts inside TLR4-MD2 complex and it showed good binding with the hydrophobic binding site of MD2. We concluded that the anti-fibrotic effect of taurine was attributable to the modulation of the TLR4/NF-κB signaling.

Components synergy between stilbenes and emodin derivatives contributes to hepatotoxicity induced by Polygonum multiflorum

Polygonum multiflorum Thunb. (PM) is a famous traditional Chinese medicine with liver tonic effect, but arousing great concerns for hepatotoxicity issue. In this study, we elucidated the contribution of the two major compounds, emodin-8-O-β-D-glucoside (EG) and 2,3,5,4´-tetrahydroxyl diphenylethylene-2-O-glucoside (TSG), in PM-induced liver injury.Based on LC-MS, the two concerned compounds were detected simultaneously in the sera of patients with PM-induced liver injury. In the lipopolysaccharide (LPS)-mediated inflammatory stress rat model, by the analysis of plasma biochemistry and liver histopathology, we observed that the solo treatment of EG, not TSG, could induce significant liver injury; and the combined administration of EG and TSG caused more severe liver injury than that of EG.Metabolomics analysis revealed that the EG-triggered liver injury was associated with significant disturbances of sphingolipids and primary bile acids metabolism pathways. In the combined administration group, much more disturbances in EG-triggered metabolic pathways, as well as alterations of several additional pathways such as retinol metabolism and vitamin B6 metabolism, were observed.Taken together, we considered EG was involved in the idiosyncratic liver injury of PM, and TSG played a synergetic role with EG, which contributed to the understanding of the hepatotoxic basis of PM.

Taurine Treatment Provides Neuroprotection in a Mouse Model of Manganism

Manganese (Mn) is a trace element involved in many physiological processes. However, excessive Mn exposure leads to neurological complications. Although no precise mechanism(s) has been found for Mn-induced neurotoxicity, oxidative stress and mitochondrial injury seem to play a relevant role in this complication. On the other hand, there is no protective strategy against Mn neurotoxicity so far. Taurine is an amino acid with significant neuroprotective properties. The current study was designed to evaluate the effect of taurine supplementation and its potential mechanism(s) of action in a mouse model of manganism. Animals were treated with Mn (100 mg/kg, s.c) alone and/or in combination with taurine (50, 100, and 500 mg/kg, i.p, for eight consecutive days). Severe locomotor dysfunction along with a significant elevation in brain tissue biomarkers of oxidative stress was evident in Mn-exposed mice. On the other hand, it was revealed that mitochondrial indices of functionality were hampered in Mn-treated animals. Taurine supplementation (50, 100, and 500 mg/kg, i.p) alleviated Mn-induced locomotor deficit. Moreover, this amino acid mitigated oxidative stress biomarkers and preserved brain tissue mitochondrial indices of functionality. These data introduce taurine as a potential neuroprotective agent against Mn neurotoxicity. Antioxidative and mitochondria protecting effects of taurine might play a fundamental role in its neuroprotective properties against Mn toxicity.

Effect of taurine on chronic and acute liver injury: Focus on blood and brain ammonia

Hyperammonemia is associated with chronic and acute liver injury. There is no promising therapeutic agent against ammonia-induced complications. Hence, finding therapeutic molecules with safe profile of administration has clinical value. The present study was conducted to evaluate the role of taurine (TA) administration on plasma and brain ammonia and its consequent events in different models of chronic and acute liver injury and hyperammonemia. Bile duct ligated (BDL) rats were used as a model of chronic liver injury. Thioacetamide and acetaminophen-induced acute liver failure were used as acute liver injury models. A high level of ammonia was detected in blood and brain of experimental groups. An increase in brain ammonia level coincided with a decreased total locomotor activity of animals and significant changes in the biochemistry of blood and also liver tissue. TA administration (500 and 1000 mg/kg, i.p), effectively alleviated liver injury and its consequent events including rise in plasma and brain ammonia and brain edema. The data suggested that TA is not only a useful and safe agent to preserve liver function, but also prevented hyperammonemia as a deleterious consequence of acute and chronic liver injury.

Paracetamol impairs the profile of amino acids in the rat brain

In our experiment we investigated the effect of subcutaneous administration of paracetamol on the levels of amino acids in the brain structures. Male Wistar rats received for eight weeks paracetamol at two doses: 10 mg/kg b.w. (group P10, n=9) and 50 mg/kg b.w. per day s.c. (group P50, n=9). The regional brain concentrations of amino acids were determined in the prefrontal cortex, hippocampus, hypothalamus and striatum of control (Con, n=9) and paracetamol-treated groups using HPLC. Evaluation of the biochemical results indicated considerable decrease of the content of amino acids in the striatum (glutamine, glutamic acid, taurine, alanine, aspartic acid) and hypothalamus (glycine) between groups treated with paracetamol compared to the control. In the prefrontal cortex paracetamol increased the level of γ-aminobutyric acid (GABA). The present study demonstrated significant effect of the long term paracetamol treatment on the level of amino acids in the striatum, prefrontal cortex and hypothalamus of rats.

Taurine and glutathione in plasma and cerebrospinal fluid in olanzapine treated patients with schizophrenia

Oxidative stress has been implicated in the pathophysiology of schizophrenia. Taurine and glutathione (GSH) have antioxidant and central nervous system protective properties, and are proposed to be involved in the pathology of schizophrenia. The aim of this study was to compare the blood and cerebrospinal fluid (CSF) levels of taurine and GSH in patients with schizophrenia, medicated with oral olanzapine, compared with controls. In total, 37 patients with schizophrenia and 45 healthy volunteers were recruited. We found the plasma taurine levels to be elevated in patients compared with controls. No differences were, however, found between patients and controls regarding taurine in CSF or GSH concentrations in plasma and CSF. Moreover, in the patient group no correlations between taurine and GSH levels and the symptoms or function of the disorder were found. The higher levels of plasma but not CSF taurine in patients with schizophrenia treated with OLA may implicate the involvement of taurine in the pathophysiology of the disease. The absence of GSH differences both in plasma and CSF between patients and controls is interesting in the perspective of earlier research proposing a dysregulation of GSH metabolism as a vulnerability factor for the development of schizophrenia.

Transcriptomic and proteomic analysis of human hepatic stellate cells treated with natural taurine

The aim of this study was to investigate the differential expression of genes and proteins between natural taurine (NTau)‑treated hepatic stellate cells (HSCs) and control cells as well as the underlying mechanism of NTau in inhibiting hepatic fibrosis. A microculture tetrazolium (MTT) assay was used to analyze the proliferation of NTau‑treated HSCs. Flow cytometry was performed to compare the apoptosis rate between NTau-treated and non‑treated HSCs. Proteomic analysis using a combination of 2-dimensional gel electrophoresis (2DE) and mass spectrometry (MS) was conducted to identify the differentially expressed proteins. Microarray analysis was performed to investigate the differential expression of genes and real-time polymerase chain reaction (PCR) was used to validate the results. The experimental findings obtained demonstrated that NTau decreased HSC proliferation, resulting in an increased number of cells in the G0/G1 phase and a reduced number of cells in the S phase. Flow cytometric analysis showed that NTau-treated HSCs had a significantly increased rate of apoptosis when compared with the non‑treated control group. A total of 15 differentially expressed proteins and 658 differentially expressed genes were identified by 2DE and MS, and microarray analysis, respectively. Gene ontology (GO) functional analysis indicated that these genes and proteins were enriched in the function clusters and pathways related to cell proliferation, cellular apoptosis and oxidation. The transcriptome and proteome analyses of NTau-treated HSCs demonstrated that NTau is able to significantly inhibit cell proliferation and promote cell apoptosis, highlighting its potential therapeutic benefits in the treatment of hepatic fibrosis.

Taurine and liver diseases: a focus on the heterogeneous protective properties of taurine

Taurine (2-aminoethylsulfonic acid) has many physiological and pharmacological functions in most tissues. It is abundantly maintained in the liver by both endogenous biosynthesis and exogenous transport, but is decreased in liver diseases. In the hepatic lobule, there are heterogeneous differences in metabolism between the pericentral (PC) and periportal regions, and the distributions of the biosynthesis capacity and specific taurine transporter expression are predominantly in the PC region. In cases of depletion of hepatic taurine level, serious liver damages were observed in the PC region. Taurine has protective effects against xenobiotics-induced liver damages in the PC region, but not xenobiotics-induced PP region damages. The xenobiotics that injure the PC region are mainly catabolized by NADPH-dependent cytochrome P450 2E1 that is also predominantly expressed in the PC region. Taurine treatment seems to be a useful agent for CYP2E1-related liver diseases with predominant damages in the PC region.

Antidepressant-like effects of the fractions of Xiaoyaosan on rat model of chronic unpredictable mild stress

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyaosan (XYS), composed of Radix Bupleuri, Radix Angelicae Sinensis, Radix Paeoniae Alba, Rhizoma Atractylodis Macrocephalae, Poria, Herba Menthae, Rhizoma Zingiberis Recens and Radix Glycyrrhizae, is a valuable traditional Chinese medicine (TCM) which is used for the treatment of depression in China. In the formula, Radix Bupleuri usually serves as the principal drug, Radix Angelicae Sinensis and Radix Paeoniae Alba serve as the ministerial drugs, Rhizoma Atractylodis Macrocephalae, Poria, Herba Menthae and Rhizoma Zingiberis Recens serve as adjunctive drugs, Radix Glycyrrhizae serves as messenger drug, they coordinate with each other and enhance the effect of the formula. In our previous experiments, the antidepressant effect of XYS was revealed. However, the antidepressant part (or component) of this prescription was still obscure. We divided the XYS into five different polar fractions, and explored the antidepressant activity of five different polar fractions to identify the active fraction.

MATERIALS AND METHODS

Behavior research and metabonomics method based on (1)H NMR were used for efficacy study of different fractions in chronic unpredictable mild stress (CUMS) model of depression. Rats were divided into 8 groups and drugs were administered during the 21 days model building period. The urine samples of rats were collected overnight (12h) on 21 day and the metabolic profiling of the urine was measured using NMR. Multivariate analysis was also utilized to evaluate the active fraction of XYS.

RESULTS

In the behavior research, there were significant difference between the lipophilic fraction group (XY-A) and the model group. In addition, with pattern recognition analysis of urinary metabolites, the results showed a clear separation of the model group and control group, while XY-A group was much closer to the control group in the OSC-PLS score plot. Seven endogenous metabolites contributing to the separation of the model group and control group were detected, while XY-A group regulated the 5 perturbed metabolites showing a tendency of recovering to control group.

CONCLUSIONS

The present work suggested that petroleum ether fraction was the most effective fraction, implying that lipophilic components contribute to the antidepressant effect of XYS.

Toxicology effects of morning glory seed in rat: a metabonomic method for profiling of urine metabolic changes

ETHNOPHARMACOLOGICAL RELEVANCE

Morning Glory Seed (MGS) is a valuable traditional Chinese medicine which is widely used for the treatment of edema, ascites, hydroncus, simple obesity, lung fever and ardent fever. In recent years, long-term exposure to Morning Glory Seed (MGS) has shown to pose progressive renal damage in clinical practice. We hypothesize that changes in metabolic profile could have occurred before symptoms were observed, which may allow early treatment.

AIM OF THE STUDY

To investigate the metabolic changes caused by Morning Glory Seed-induced renal damage.

METHOD

Metabonomics method was used for chronic toxicology study of MGS in Wistar rats. With a therapeutic dose, the model rats were orally administered the extract of MGS for 10 weeks continuously. The urine samples of model and control rats were collected in various time-points and the endogenous metabolites were analyzed by ultraperformance liquid chromatography coupled with mass spectrometry. The identification of all the potential biomarkers was performed using reference standard by comparing their mass spectra, MS/MS fragmentation and retention time. Furthermore, histopathology and clinical chemistry studies were carried out to ensure the success of MGS-induced nephrotoxicity model.

RESULTS

The difference in metabolic profiles between the control and the dosed rats was well observed by the principal component analysis (PCA) of the MS spectra. Significant changes of 12 metabolite biomarkers were detected in the rat urine samples. Metabonomics method could discriminate the model rats from the control rats in 2nd, 6th and 10th week respectively before serious organic damage of kidney was found in 10th week by histopathology method.

CONCLUSION

We believe that metabolic profiling may act as a preclinical protocol for MGS exposure before symptoms are observed.