Application of NMR-based metabonomics in the investigation of myocardial ischemia-reperfusion, ischemic preconditioning and antioxidant intervention in rabbits

Radiation metabolomics in the quest of cardiotoxicity biomarkers: the review

Purpose: Ionizing radiation is a risk factor to the whole organism, including the heart. Cardiac damage is considered to be a late effect of radiation exposure. While the acute cardiotoxicity of high doses is well characterized, the knowledge about nature and magnitude of the cardiac risk following lower doses exposure is incomplete. It has been shown that the cardiotoxic effects of radiation are source-, dose- and time-dependent. This paper provides an overview on these dependencies with regard to the molecular responses at the cellular and tissue levels. Main focus is put on the Nuclear Magnetic Resonance (NMR)-based and Mass Spectrometry (MS)-based metabolomic approaches in search of toxicity markers of relatively small doses of radiation.Conclusions: Available literature indicates that radiation exposure affects metabolites associated with: energy production, degradation of proteins and cell membranes, expression of proteins and stress response. Such effects are common for both animal and human studies. However, the specific metabolic response depends on several factors, including the examined organ. Radiation metabolomics can be used to explain the mechanisms of development of radiation-induced heart disease and to find an organ-specific biomarker of radiation exposure. The main aim of this review was to collect the information on the human cardiotoxicity biomarkers. In addition it also summarizes results of the studies on the metabolic responses to ionizing radiation for other organs, as well as the comparative data concerning animal studies.

1H NMR-based metabonomics approach in a rat model of acute liver injury and regeneration induced by CCl4 administration

The administration of carbon tetrachloride (CCl(4)) has been established as a model of toxin-induced acute and chronic liver injury. In the present study, we investigate the progression of the biochemical response to acute CCl(4)-induced liver injury, capturing metabolic variations during both toxic insult and regeneration using NMR-based metabonomic analysis of liver tissue and plasma. A single dose of CCl(4) (1 mL/kg BW) was intraperitoneally administered to male Wister rats sacrificed every 12h up to 72 h post treatment, while healthy animals served as controls. Acquired (1)H NMR spectra of liver tissue extracts and plasma samples were explored with multivariate analysis and the resulted models were correlated with conventional biochemical and histopathological indices of toxicity for monitoring the progression of experimental injury. The metabonomic analysis resulted in discrimination between the subjects under toxic insult (up to 36 h) and those at the regenerative phase (peaked at 48 h). At 72 h normalization of liver's pathology similar to the controls group was apparent. Principal component analysis (PCA) trajectories highlighted the time points of the greater degree of toxic insult and the regenerative state. A number of metabolites such as glucose, lactate, choline, formate exhibited variations suggesting CCl(4) induced impairment in essential biochemical pathways as energy metabolism, lipid biosynthesis and transmethylation reactions. The latter provides new evidence of B12 and folate pathways deficiency, indicative of new mechanistic implications possibly by direct inhibition of B12 dependent enzymes by the chlorinated radicals of CCl(4) metabolism.

Effect of Acupuncture on Rats with Acute Gouty Arthritis Inflammation: A Metabonomic Method for Profiling of Both Urine and Plasma Metabolic Perturbation

Acute gouty arthritis is a common inflammation model with multiple pathogenic mechanisms seen in clinical practice, for which acupuncture may potentially be an alternative therapy. To investigate the effect of acupuncture on acute gouty arthritis and search for its mechanism, a metabonomic method was developed in this investigation. Acute gouty arthritis model rats were induced by monosodium urate (MSU) crystals. The urine and plasma samples were collected at several time points and the endogenous metabolites were analyzed by an ultra-performance liquid chromatography coupled with a mass spectrometry (UPLC-MS). Data were analyzed using principal components analysis (PCA) and partial least squares (PLS) analysis to compare metabolic profiles of MSU crystal-induced acute gouty arthritis rats with MSU crystal-induced acute gouty arthritis, treated with acupuncture rats. The results showed that acupuncture could restore the metabolite network that disturbed by MSU administration. Our study indicates that UPLC-MS-based metabonomics can be used as a potential tool for the investigation of biological effect of acupuncture on acute gouty arthritis.

The Effect of LC-MS Data Preprocessing Methods on the Selection of Plasma Biomarkers in Fed vs. Fasted Rats

The metabolic composition of plasma is affected by time passed since the last meal and by individual variation in metabolite clearance rates. Rat plasma in fed and fasted states was analyzed with liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOF) for an untargeted investigation of these metabolite patterns. The dataset was used to investigate the effect of data preprocessing on biomarker selection using three different softwares, MarkerLynx^TM, MZmine, XCMS along with a customized preprocessing method that performs binning of m/z channels followed by summation through retention time. Direct comparison of selected features representing the fed or fasted state showed large differences between the softwares. Many false positive markers were obtained from custom data preprocessing compared with dedicated softwares while MarkerLynx^TM provided better coverage of markers. However, marker selection was more reliable with the gap filling (or peak finding) algorithms present in MZmine and XCMS. Further identification of the putative markers revealed that many of the differences between the markers selected were due to variations in features representing adducts or daughter ions of the same metabolites or of compounds from the same chemical subclasses, e.g., lyso-phosphatidylcholines (LPCs) and lyso-phosphatidylethanolamines (LPEs). We conclude that despite considerable differences in the performance of the preprocessing tools we could extract the same biological information by any of them. Carnitine, branched-chain amino acids, LPCs and LPEs were identified by all methods as markers of the fed state whereas acetylcarnitine was abundant during fasting in rats.

Metabolomic strategy to study therapeutic and synergistic effects of tanshinone IIA, salvianolic acid B and ginsenoside Rb1 in myocardial ischemia rats

AIM OF THE STUDY

Tanshinone IIA (T), salvianolic acid B (S) and ginsenoside Rb1 (G) are the three major active ingredients of Compound Danshen Formula (CDF) for its protective effects on myocardial ischemia (MI). In this study, we aimed to investigate therapeutic and synergistic effects of TSG (combination of T, S and G) on MI rats with metabolomic strategy.

MATERIALS AND METHODS

MI model were induced in Sprague-Dawley rats by left anterior descending coronary artery ligation. MI rats were respectively administrated T, S, G, TSG and CDF. Plasma was analyzed by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Partial least squares discriminate analysis (PLS-DA) models were built to evaluate the therapeutic and synergistic effects of TSG at whole level. 22 MI biomarkers in rat plasma were also investigated to explain that.

RESULTS

TSG brings nearly equal therapeutic effects on MI as CDF and it plays more stable regulated action on those 22 identified metabolites than single compound.

CONCLUSIONS

Overall, there were few methods for the study of synergistic effects of Chinese medicine. Our results suggested that metabolomics offers a new idea for Chinese medicine research.

The influence of EDTA and citrate anticoagulant addition to human plasma on information recovery from NMR-based metabolic profiling studies

The widely-used blood anticoagulants citrate and EDTA give rise to prominent peaks in (1)H NMR spectra of plasma samples collected in epidemiological and clinical studies, and these cause varying levels of interference in recovering biochemical information on endogenous metabolites. To investigate both the potential metabolic information loss caused by these substances and any possible inter-molecular interactions between the anticoagulants and endogenous components, the (1)H NMR spectra of 40 split human plasma samples collected from 20 individuals into either citrate or EDTA have been analysed. Endogenous metabolite peaks were selectively obscured by large citrate peaks or those from free EDTA and its calcium and magnesium complexes. It is shown that the endogenous metabolites that give rise to peaks obscured by those from EDTA or citrate almost invariably also have other resonances that allow their identification and potential quantitation. Also, metabolic information recovery could be maximised by use of spectral editing techniques such as spin-echo, diffusion-editing and J-resolved experiments. The NMR spectral effects of any interactions between the added citrate or EDTA and endogenous components were found to be negligible. Finally, identification of split samples was feasible using simple multivariate statistical approaches such as principal components analysis. Thus even when legacy epidemiological plasma samples have been collected using the NMR-inappropriate citrate or EDTA anticoagulants, useful biochemical information can still be recovered effectively.

Development of extractive electrospray ionization ion trap mass spectrometry for in vivo breath analysis

In metabolomics studies and clinical diagnosis, interest is increasing in the rapid analysis of exhaled breath. In vivo breath analysis offers a unique, unobtrusive, non-invasive method of investigating human metabolism. To analyze breath in vivo, we constructed a novel platform of extractive electrospray ionization (EESI) ion trap mass spectrometry (ITMS) using a home-made EESI source coupled to a linear trap quadrupole mass spectrometer. A reference compound (authentic n-octyl amine) was used to evaluate effects of systematically varying selected characteristics of the EESI source on signal intensity. Under the optimized working conditions, metabolic changes of human bodies were in vivo followed by performing rapid breath analysis using the multi-stage EESI-ITMS tandem mass spectrometry platform. For nicotine, a limit of determination was found to be 0.05 fg mL(-1) (S/N = 3, RSD = 5.0 %, n = 10) for nicotine in aerosol standard samples; the dynamic response range was from 0.0155 pg mL(-1) to 155 pg mL(-1). The concentration of nicotine in the exhaled breath of a regular smoker was in vivo determined to be 5.8 pg mL(-1), without any sample pre-treatment. Our results show that EESI-ITMS is a powerful analytical platform to provide high sensitivity, high specificity and high throughput for semi-quantitative analysis of complex samples in life science, particularly for in vivo metabolomics studies.

Metabonomic identification of novel biomarkers in doxorubicin cardiotoxicity and protective effect of the natural antioxidant oleuropein

Doxorubicin (DXR) is a commonly used antineoplastic agent; however, its use is limited due to cardiotoxicity. Oxidative stress and consequent alterations of cardiac energetics are involved in the development of DXR toxicity. Oleuropein (Oleu) is a phenolic antioxidant, present in olive tree, reported to confer protection against DXR cardiotoxicity. In this study, NMR based-metabonomics was applied to characterize the metabolic profile of the acute DXR cardiotoxicity in rats and to evaluate the metabolic alterations conferred by co-treatment with Oleu. Wistar rats were divided into six groups and treated as follows: control group with a single injection of 2 mL normal saline intraperitoneally (i.p.), DXR group with a single dose of 20 mg/kg, i.p and DXR plus Oleu groups with 20mg/kg DXR i.p., and 100 or 200 mg/kg/BW of Oleu i.p. for 5 or 3 consecutive days starting either 2 days before or on the day of DXR administration. Hearts were excised 72 h after DXR treatment and (1)H-NMR spectra of aqueous myocardium extracts were recorded. Principal Component Analysis (PCA) and Partial Least Square Discriminant Analysis (PLS-DA) revealed differences in the metabolic profile between control and DXR attributed to several metabolites. A number of them were quantified by integration of the NMR spectra. Myocardial levels of acetate and succinate were increased in DXR compared to controls, while branched amino acids were decreased. These results correlate with nonenzymatic conversion of pyruvate to acetate and of alpha-ketoglutarate to succinate by DXR free radicals. Oleu completely restored the changes of metabolites to the normal levels. Acetate and succinate constitute novel biomarkers related to DXR, and Oleu treatment aids the compensation of distressed energy metabolic pathways.

Intestinal ischemia/reperfusion injury: defining the role of the gut microbiome

Intestinal ischemia/reperfusion (I/R) injury initiates a systemic inflammatory response syndrome with a high associated mortality rate. Early diagnosis is essential for reducing surgical mortality, yet current clinical biomarkers are insufficient. Metabonomics is a novel strategy for studying intestinal I/R, which may be used as part of a systems approach for quantitatively analyzing the intestinal microbiome during gut injury. By deconvolving the mammalian–microbial symbiotic relationship systems biology thus has the potential for personalized risk stratification in patients exposed to intestinal I/R. This review describes the mechanism of intestinal I/R and explores the essential role of the intestinal microbiota in the initiation of systemic inflammatory response syndrome. Furthermore, it analyzes current and future approaches for elucidating the mechanism of this condition.