Increased levels of urinary phenylacetylglycine associated with mitochondrial toxicity in a model of drug-induced phospholipidosis

Cyclosporine A-induced systemic metabolic perturbations in rats: A comprehensive metabolome analysis

A better understanding of cyclosporine A (CsA)-induced nephro- and hepatotoxicity at the molecular level is necessary for safe and effective use. Utilizing a sophisticated study design, this study explored metabolic alterations after long-term CsA treatment in vivo. Rats were exposed to CsA with 4, 10, and 25 mg/kg for 4 weeks and then sacrificed to obtain liver, kidney, urine, and serum for untargeted metabolomics analysis. Differential network analysis was conducted to explore the biological relevance of metabolites significantly altered by toxicity-induced disturbance. Dose-dependent toxicity was observed in all biospecimens. The toxic effects were characterized by alterations of metabolites related to energy metabolism and cellular membrane composition, which could lead to the cholestasis-induced accumulation of bile acids in the tissues. The unfavorable impacts were also demonstrated in the serum and urine. Intriguingly, phenylacetylglycine was increased in the kidney, urine, and serum treated with high doses versus controls. Differential correlation network analysis revealed the strong correlations of deoxycytidine and guanosine with other metabolites in the network, which highlighted the influence of repeated CsA exposure on DNA synthesis. Overall, prolonged CsA administration had system-level dose-dependent effects on the metabolome in treated rats, suggesting the need for careful usage and dose adjustment.

Type 2-resistant starch and Lactiplantibacillus plantarum NCIMB 8826 result in additive and interactive effects in diet-induced obese mice

Little is known about how combining a probiotic with prebiotic dietary fiber affects the ability of either biotic to improve health. We hypothesized that prebiotic, high-amylose maize type 2-resistant starch (RS) together with probiotic Lactiplantibacillus plantarum NCIMB8826 (LP) as a complementary synbiotic results in additive effects on the gut microbiota in diet-induced obese mice and other body sites. Diet-induced obese C57BL/6J male mice were fed a high-fat diet adjusted to contain RS (20% by weight), LP (109 cells every 48 hours), or both (RS+LP) for 6 weeks. As found for mice fed RS, cecal bacterial alpha diversity was significantly reduced in mice given RS+LP compared with those fed LP and high-fat controls. Similarly, both RS+LP and RS also conferred lower quantities of cecal butyrate and serum histidine and higher ileal TLR2 transcript levels and adipose tissue interleukin-6 protein. As found for mice fed LP, RS+LP-fed mice had higher colonic tissue TH17 cytokines, reduced epididymal fat immune and oxidative stress responses, reduced serum carnitine levels, and increased transcript quantities of hepatic carnitine palmitoyl transferase 1α. Notably, compared with RS and LP consumed separately, there were also synergistic increases in colonic glucose and hepatic amino acids as well antagonistic effects of LP on RS-mediated increases in serum adiponectin and urinary toxin levels. Our findings show that it is not possible to fully predict outcomes of synbiotic applications based on findings of the probiotic or the prebiotic tested separately; therefore, studies should be conducted to test new synbiotic formulations.

Effects of Xinjiang wild cherry plum (Prunus divaricata Ledeb) anthocyanin-rich extract on the plasma metabolome of atherosclerotic apoE-deficient mice fed a high-fat diet

It is well-known that many vegetables and fruits have abundant polyphenols, such as anthocyanins, which benefit many cardiovascular diseases due to their anti-oxidative and anti-inflammatory effects. To explore the protective effect of anthocyanin on atherosclerosis from a metabolic perspective, alterations in plasma metabolic profiling of apoE-deficient (apoE^–/–) mice in response to treatment with anthocyanin extracts derived from Xinjiang wild cherry plum (Prunus divaricata Ledeb) peel was investigated through UHPLC-Q-TOF/MS. The mice were fed with a normal diet or high-fat diet supplementation with or without anthocyanin extracts (ACNE, 75, 150, 250 mg/kg body weight) for 18 weeks, corresponding to control (Con), model (Mod), and treatment group (LD, low dose; MD, medium dose; HD, high dose), respectively, along with a positive control group (posCon, treatment with Atorvastatin, 0.003 mg/kg body weight). The results showed that ACNE could significantly enhance the antioxidant capacity and lower the plasma lipid, but have no evident influence on the body weight of apoE^–/– mice. A series of differential metabolites, predominantly related to lipid metabolism, were identified, including docosahexaenoic acid, palmitoyl ethanolamide, stearoylcarnitine, L-palmitoylcarnitine, indoxyl sulfate (IS), 1-palmitoyl-lysophosphatidylcholine, phenylacetylglycine (PAGly), and so on. Among these, both IS and PAGly were host-microbial metabolites. These differential metabolites were mainly enriched in the pathway of glycerophospholipid metabolism and linoleic acid metabolism. Several important enzymes related to glycerophospholipid metabolisms such as LCAT, LPCAT, GPCPD1, PLA2G1B, PPARG, LIPE, PNPLA2, AGPAT1, and ENPP2 were recognized as underlying targets for anti-atherogenic effects of ACNE. These findings suggest that ACNE derived from Xinjiang wild cherry plum exhibits protective effects against atherosclerosis via modulating glycerophospholipid metabolism.

Toxicity and Metabolomic Impact of Cobalt, Chromium, and Nickel Exposure on HepaRG Hepatocytes

Cobalt, chromium, and nickel are used in orthopedic prostheses. They can be released, accumulate in many organs, and be toxic. The aim of this study is to evaluate the cytotoxicity of these metals on human hepatocytes and to improve our knowledge of their cellular toxicity mechanisms by metabolomic analysis. HepaRG cells were incubated for 48 h with increasing concentrations of metals to determine their IC₅₀. Then, a nontargeted metabolomic study using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was done at IC₅₀ and at a lower concentration (100 nM), near to those found in the blood and liver of patients with prostheses. IC₅₀ were defined at 940, 2, and 1380 μM for Co, Cr, and Ni, respectively. In vitro, Cr appears to be much more toxic than Co and Ni. Metabolomic analysis revealed the disruption of metabolic pathways from the low concentration of 100 nM, in particular tryptophan metabolism and lipid metabolism illustrated by an increase in phenylacetylglycine, a marker of phospholipidosis, for all three metals. They also appear to be responsible for oxidative stress. Dysregulation of these pathways impacts hepatocyte metabolism and may result in hepatotoxicity. Further investigations on accessible biological matrices should be conducted to correlate our in vitro results with the clinical data of prostheses-bearing patients.

Blood pressure and urine metabolite changes in spontaneously hypertensive rats treated with leaf extract of Ficus deltoidea var angustifolia

Ficus deltoidea var angustifolia (FD-A) reduces blood pressure in spontaneously hypertensive rats (SHR) but the mechanism remains unknown. Changes in urine metabolites following FD-A treatment in SHR were, therefore, examined to identify the mechanism of its antihypertensive action. Male SHR were given either FD-A (1000 mg kg^-1 day^-1) or losartan (10 mg kg^-1 day^-1) or 0.5 mL of ethanolic-water (control) daily for 4 weeks. Systolic blood pressure (SBP) was measured every week and urine spectra data acquisition, on urine collected after four weeks of treatment, were compared using multivariate data analysis. SBP in FD-A and losartan treated rats was significantly lower than that in the controls after four weeks of treatment. Urine spectra analysis revealed 24 potential biomarkers with variable importance projections (VIP) above 0.5. These included creatine, hippurate, benzoate, trimethylamine N-oxide, taurine, dimethylamine, homocysteine, allantoin, methylamine, n-phenylacetylglycine, guanidinoacetate, creatinine, lactate, glucarate, kynurenine, ethanolamine, betaine, 3-hydroxybutyrate, glycine, lysine, glutamine, 2-hydroxyphenylacetate, 3-indoxylsulfate and sarcosine. From the profile of these metabolites, it seems that FD-A affects urinary levels of metabolites like taurine, hypotaurine, glycine, serine, threonine, alanine, aspartate and glutamine. Alterations in these and the pathways involved in their metabolism might underlie the molecular mechanism of its antihypertensive action.

The gut microbial metabolite phenylacetylglycine protects against cardiac injury caused by ischemia/reperfusion through activating β2AR

BACKGROUND

Myocardial ischemia/reperfusion (I/R) injury is closely related to cardiomyocyte apoptosis. Stimulating β2 adrenergic receptor (β2AR) can effectively combat cardiomyocyte apoptosis. Previous studies demonstrate that the gut microbial metabolite phenylacetylglycine (PAGly) can stimulate β2AR. However, the effect of PAGly on myocardial I/R injury remains unknown.

METHODS

The hypoxia/reoxygenation (H/R) model was established using the neonatal mouse cardiomyocytes (NMCMs). Different doses of PAGly were used to treat NMCMs, and apoptosis was detected by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) staining. Additionally, the level of cyclic adenosine monophosphate (cAMP) was examined by using a cAMP detection kit. Mouse model of myocardial I/R injury was established in C57BL/6 mice, and different doses of phenylacetic acid were administrated intraperitoneally. Apoptosis of myocardial cells was detected by TUNEL and α-actin staining. The area at risk and the infarct areas were identified by 2,3,5-triphenyltetrazolium chloride (TTC) and Evans blue staining. Western blotting was used to measure the protein expression levels of phosphorylated phosphatidylinositol 3-kinase (p-PI3K), total Akt (t-Akt), phosphorylated Akt (p-AKT), Bcl-2-associated X protein (Bax), B-cell lymphoma-2 (Bcl-2), cleaved caspase-3.

RESULTS

PAGly significantly suppressed H/R injury-induced apoptosis in NMCMs and inhibited apoptosis in myocardial I/R injured mice in vivo. We verified that PAGly activated the anti-apoptotic Gαi/PI3K/AKT signaling cascade in NMCMs via stimulating β2AR signaling. Continuous administration of PAGly at an appropriate dose could inhibit apoptosis and reduce the infarct size resulting from I/R injury in mice. However, high-dose PAGly treatment was associated with a higher mortality rate. Moreover, we demonstrated that Aspirin reduced the infarct size and the high mortality caused by high doses of PAGly in I/R injured mice.

CONCLUSIONS

These findings suggest that treatment with the gut microbial metabolite PAGly could suppress cardiomyocyte apoptosis caused by myocardial I/R injury and reduce the infarct size, which provides a novel therapeutic strategy for patients with myocardial infarction.

Metabolomics study of fasudil on cisplatin-induced kidney injury

Fasudil is a derivative of 5-isoquinoline sulfonamide, which is a Rho kinase inhibitor, a wide range of pharmacological effects. Fasudil has been shown to attenuate kidney injury caused by certain substances. In the present study, metabolomic analysis of mouse kidney tissues ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry was used to determine the metabolomic changes in cisplatin-induced kidney injury and the fasudil-induced attenuation of cisplatin-induced kidney injury. Metabolomic profiling of kidney tissues revealed significant differences in metabolites between the control group and the cisplatin group and between the cisplatin group and the fasudil-intervention group. With metabolomic approach, 68 endogenous differential metabolites were found, and multivariate statistical analysis, accurate molecular weights, isotope tracers, mass-spectrometry secondary-fragment information, and standard-reference comparisons were used to identify these substances. Based on these differential metabolites, a metabolic-pathway network was constructed and revealed that fasudil primarily attenuated cisplatin-induced renal injury by modulating lipid and amino-acid metabolism. These results further demonstrate that kidney injury can be induced by cisplatin and, moreover, suggest that fasudil can be used to reduce kidney injury at early stages in patients treated with cisplatin.

Effects of long-term cadmium exposure on urinary metabolite profiles in mice

Cadmium (Cd) is a common environmental pollutant with known toxic effects on the kidney. Urinary metabolomics is a promising approach to study mechanism by which Cd-induced nephrotoxicity. The aim of this study was to elucidate the mechanism of Cd toxicity and to develop specific biomarkers by identifying urinary metabolic changes after a long-term of Cd exposure and with the critical concentration of Cd in the kidney. Urine samples were collected from wild-type 129/Sv mice after 67 weeks of 300 ppm Cd exposure and analyzed by ultra performance liquid chromatography connected with quadrupole time of flight mass spectrometer (UPLC-QTOF-MS) based metabolomics approach. A total of 40 most differentiated metabolites (9 down-regulated and 31 up-regulated) between the control and Cd-exposed group were identified. The majority of the regulated metabolites are amino acids (glutamine, L-aspartic acid, phenylalanine, tryptophan, and D-proline) indicating that amino acid metabolism pathways are affected by long-term exposure of Cd. However, there are also some nucleotides (guanosine, guanosine monophosphate, cyclic AMP, uridine), amino acid derivatives (homoserine, N-acetyl-L-aspartate, N-acetylglutamine, acetyl-phenylalanine, carboxymethyllysine), and peptides. Results of pathway analysis showed that the arginine and proline metabolism, purine metabolism, alanine, aspartate and glutamate metabolism, and aminoacyl-tRNA biosynthesis were affected compared to the control. This study demonstrates that metabolomics is useful to elucidate the metabolic responses and biological effects induced by Cd-exposure.

Nuclear magnetic resonance- and mass spectrometry-based metabolomics to study maleic acid toxicity from repeated dose exposure in rats

Maleic acid (MA), a chemical intermediate used in many consumer and industrial products, was intentionally adulterated in a variety of starch-based foods and instigated food safety incidents in Asia. We aim to elucidate possible mechanisms of MA toxicity after repeated exposure by (1) determining the changes of metabolic profile using ¹ H nuclear magnetic resonance spectroscopy and multivariate analysis, and (2) investigating the occurrence of oxidative stress using liquid chromatography tandem mass spectrometry by using Sprague-Dawley rat urine samples. Adult male rats were subjected to a 28 day subchronic study (0, 6, 20 and 60 mg kg^-1 ) via oral gavage. Urine was collected twice a day on days 0, 7, 14, 21 and 28; organs underwent histopathological examination. Changes in body weight and relative kidney weights in medium- and high-dose groups were significantly different compared to controls. Morphological alterations were evident in the kidneys and liver. Metabolomic results demonstrated that MA exposure increases the urinary concentrations of 8-hydroxy-2'-deoxyguanosine, 8-nitroguanine and 8-iso-prostaglandin F_2α ; levels of acetoacetate, hippurate, alanine and acetate demonstrated time- and dose-dependent variations in the treatment groups. Findings suggest that MA consumption escalates oxidative damage, membrane lipid destruction and disrupt energy metabolism. These aforementioned changes in biomarkers and endogenous metabolites elucidate and assist in characterizing the possible mechanisms by which MA induces nephro- and hepatotoxicity.

Unravelling the metabolic impact of SBS-associated microbial dysbiosis: Insights from the piglet short bowel syndrome model

Liver disease is a major source of morbidity and mortality in children with short bowel syndrome (SBS). SBS-associated microbial dysbiosis has recently been implicated in the development of SBS-associated liver disease (SBS-ALD), however the pathological implications of this association have not been explored. In this study high-throughput sequencing of colonic content from the well-validated piglet SBS-ALD model was examined to determine alterations in microbial communities, and concurrent metabolic alterations identified in urine samples via targeted mass spectrometry approaches (GC-MS, LC-MS, FIA-MS) further uncovered impacts of microbial disturbance on metabolic outcomes in SBS-ALD. Multi-variate analyses were performed to elucidate contributing SBS-ALD microbe and metabolite panels and to identify microbe-metabolite interactions. A unique SBS-ALD microbe panel was clearest at the genus level, with discriminating bacteria predominantly from the Firmicutes and Bacteroidetes phyla. The SBS-ALD metabolome included important alterations in the microbial metabolism of amino acids and the mitochondrial metabolism of branched chain amino acids. Correlation analysis defined microbe-metabolite clustering patterns unique to SBS-ALD and identified a metabolite panel that correlates with dysbiosis of the gut microbiome in SBS.