Intrarenal Metabolomic Investigation of Chronic Kidney Disease and its TGF-β1 Mechanism in Induced-adenine Rats using UPLC Q-TOF/HSMS/MSE

Targeting Lactobacillus johnsonii to reverse chronic kidney disease

Accumulated evidence suggested that gut microbial dysbiosis interplayed with progressive chronic kidney disease (CKD). However, no available therapy is effective in suppressing progressive CKD. Here, using microbiomics in 480 participants including healthy controls and patients with stage 1-5 CKD, we identified an elongation taxonomic chain Bacilli-Lactobacillales-Lactobacillaceae-Lactobacillus-Lactobacillus johnsonii correlated with patients with CKD progression, whose abundance strongly correlated with clinical kidney markers. L. johnsonii abundance reduced with progressive CKD in rats with adenine-induced CKD. L. johnsonii supplementation ameliorated kidney lesion. Serum indole-3-aldehyde (IAld), whose level strongly negatively correlated with creatinine level in CKD rats, decreased in serum of rats induced using unilateral ureteral obstruction (UUO) and 5/6 nephrectomy (NX) as well as late CKD patients. Treatment with IAld dampened kidney lesion through suppressing aryl hydrocarbon receptor (AHR) signal in rats with CKD or UUO, and in cultured 1-hydroxypyrene-induced HK-2 cells. Renoprotective effect of IAld was partially diminished in AHR deficiency mice and HK-2 cells. Our further data showed that treatment with L. johnsonii attenuated kidney lesion by suppressing AHR signal via increasing serum IAld level. Taken together, targeting L. johnsonii might reverse patients with CKD. This study provides a deeper understanding of how microbial-produced tryptophan metabolism affects host disease and discovers potential pathways for prophylactic and therapeutic treatments for CKD patients.

Exploring sample treatment strategies for untargeted metabolomics: A comparative study of solid phase microextraction (SPME) and homogenization with solid-liquid extraction (SLE) in renal tissue

BACKGROUND

The selection of the sample treatment strategy is a crucial step in the metabolomics workflow. Solid phase microextraction (SPME) is a sample processing methodology with great potential for use in untargeted metabolomics of tissue samples. However, its utilization is not as widespread as other standard protocols involving steps of tissue collection, metabolism quenching, homogenization, and extraction of metabolites by solvents. Since SPME allows us to perform all these steps in one action in tissue samples, in addition to other advantages, it is necessary to know whether this methodology produces similar or comparable metabolome and lipidome coverage and performance to classical methods.

RESULTS

SPME and homogenization with solid-liquid extraction (Homo-SLE) sample treatment methods were applied to healthy murine kidney tissue, followed by comprehensive metabolomics and lipidomics analyses. In addition, it has been tested whether freezing and storage of the tissue causes alterations in the renal metabolome and lipidome, so the analyses were performed on fresh and frozen tissue samples Lipidomics analysis revealed the exclusive presence of different structural membrane and intracellular lipids in the Homo-SLE group. Conversely, all annotated metabolites were detected in both groups. Notably, the freezing of the sample mainly causes a decrease in the levels of most lipid species and an increase in metabolites such as amino acids, purines, and pyrimidines. These alterations are principally detected in a statistically significant way by SPME methodology. Finally, the samples of both methodologies show a positive correlation in all the analyses.

SIGNIFICANCE

These results demonstrate that in SPME processing, as long as the fundamentals of non-exhaustive extraction in a pre-equilibrium kinetic regime, extraction in a tissue localized area, the chemistry of the fiber coating and non-homogenization of the tissue are taken into account, is an excellent method to use in kidney tissue metabolomics; since this methodology presents an easy-to-use, efficient, and less invasive approach that simplifies the different sample processing steps.

Plasma Metabolomics of Dietary Intake of Protein-Rich Foods and Kidney Disease Progression in Children

OBJECTIVE

Evidence regarding the efficacy of a low-protein diet for patients with CKD is inconsistent and recommending a low-protein diet for pediatric patients is controversial. There is also a lack of objective biomarkers of dietary intake. The purpose of this study was to identify plasma metabolites associated with dietary intake of protein and to assess whether protein-related metabolites are associated with CKD progression.

METHODS

Nontargeted metabolomics was conducted in plasma samples from 484 Chronic Kidney Disease in Children (CKiD) participants. Multivariable linear regression estimated the cross-sectional association between 949 known, nondrug metabolites and dietary intake of total protein, animal protein, plant protein, chicken, dairy, nuts and beans, red and processed meat, fish, and eggs, adjusting for demographic, clinical, and dietary covariates. Cox proportional hazards models assessed the prospective association between protein-related metabolites and CKD progression defined as the initiation of kidney replacement therapy or 50% eGFR reduction, adjusting for demographic and clinical covariates.

RESULTS

One hundred and twenty-seven (26%) children experienced CKD progression during 5 years of follow-up. Sixty metabolites were significantly associated with dietary protein intake. Among the 60 metabolites, 10 metabolites were significantly associated with CKD progression (animal protein: n = 1, dairy: n = 7, red and processed meat: n = 2, nuts and beans: n = 1), including one amino acid, one cofactor and vitamin, 4 lipids, 2 nucleotides, one peptide, and one xenobiotic. 1-(1-enyl-palmitoyl)-2-oleoyl-glycerophosphoethanolamine (GPE, P-16:0/18:1) was positively associated with dietary intake of red and processed meat, and a doubling of its abundance was associated with 88% higher risk of CKD progression. 3-ureidopropionate was inversely associated with dietary intake of red and processed meat, and a doubling of its abundance was associated with 48% lower risk of CKD progression.

CONCLUSIONS

Untargeted plasma metabolomic profiling revealed metabolites associated with dietary intake of protein and CKD progression in a pediatric population.

Integrative phosphatidylcholine metabolism through phospholipase A2 in rats with chronic kidney disease

Dysregulation in lipid metabolism is the leading cause of chronic kidney disease (CKD) and also the important risk factors for high morbidity and mortality. Although lipid abnormalities were identified in CKD, integral metabolic pathways for specific individual lipid species remain to be clarified. We conducted ultra-high-performance liquid chromatography-high-definition mass spectrometry-based lipidomics and identified plasma lipid species and therapeutic effects of Rheum officinale in CKD rats. Adenine-induced CKD rats were administered Rheum officinale. Urine, blood and kidney tissues were collected for analyses. We showed that exogenous adenine consumption led to declining kidney function in rats. Compared with control rats, a panel of differential plasma lipid species in CKD rats was identified in both positive and negative ion modes. Among the 50 lipid species, phosphatidylcholine (PC), lysophosphatidylcholine (LysoPC) and lysophosphatidic acid (LysoPA) accounted for the largest number of identified metabolites. We revealed that six PCs had integral metabolic pathways, in which PC was hydrolysed into LysoPC, and then converted to LysoPA, which was associated with increased cytosolic phospholipase A2 protein expression in CKD rats. The lower levels of six PCs and their corresponding metabolites could discriminate CKD rats from control rats. Receiver operating characteristic curves showed that each individual lipid species had high values of area under curve, sensitivity and specificity. Administration of Rheum officinale significantly improved impaired kidney function and aberrant PC metabolism in CKD rats. Taken together, this study demonstrates that CKD leads to PC metabolism disorders and that the dysregulation of PC metabolism is involved in CKD pathology.

The Future of Biomarkers in Veterinary Medicine: Emerging Approaches and Associated Challenges

Simple Summary

In this review we seek to outline the role of new technologies in biomarker discovery, particularly within the veterinary field and with an emphasis on ‘omics’, as well as to examine why many biomarkers-despite much excitement-have not yet made it to clinical practice. Further we emphasise the critical need for close collaboration between clinicians, researchers and funding bodies and the need to set clear goals for biomarker requirements and realistic application in the clinical setting, ensuring that biomarker type, method of detection and clinical utility are compatible, and adequate funding, time and sample size are available for all phases of development.

Abstract

New biomarkers promise to transform veterinary practice through rapid diagnosis of diseases, effective monitoring of animal health and improved welfare and production efficiency. However, the road from biomarker discovery to translation is not always straightforward. This review focuses on molecular biomarkers under development in the veterinary field, introduces the emerging technological approaches transforming this space and the role of ‘omics platforms in novel biomarker discovery. The vast majority of veterinary biomarkers are at preliminary stages of development and not yet ready to be deployed into clinical translation. Hence, we examine the major challenges encountered in the process of biomarker development from discovery, through validation and translation to clinical practice, including the hurdles specific to veterinary practice and to each of the ‘omics platforms–transcriptomics, proteomics, lipidomics and metabolomics. Finally, recommendations are made for the planning and execution of biomarker studies with a view to assisting the success of novel biomarkers in reaching their full potential.

Serum metabolomics of end-stage renal disease patients with depression: potential biomarkers for diagnosis

Background

End-stage renal disease (ESRD) is the final stage during the development of renal failure. Depression is the most common psychiatric disorder in patients with ESRD, which in turn aggravates the progression of renal failure, however, its underlying mechanism remains unclear. This study aimed to reveal the pathogenesis and to discover novel peripheral biomarkers for ESRD patients with depression through metabolomic analysis.

Methods

Ultra-high-performance liquid chromatography coupled with mass spectrometry (UPLC-MS) was used to explore changes of serum metabolites among healthy controls, ESRD patients with or without depression. The differential metabolites between groups were subjected to clustering analysis, pathway analysis, receiver operating characteristic (ROC) curve analysis.

Results

A total of 57 significant serum differential metabolites were identified between ESRD patients with or without depression, which were involved in 19 metabolic pathways, such as energy metabolism, glycerolipid metabolism, and glutamate-centered metabolism. Moreover, the area under the ROC curve of gentisic acid, uric acid, 5-hydroxytryptamine, 2-phosphoglyceric acid, leucyl-phenylalanine, propenyl carnitine, naloxone, pregnenolone, 6-thioxanthene 5'-monophosphate, hydroxyl ansoprazole, zileuton O-glucuronide, cabergoline, PA(34:2), PG(36:1), probucol and their combination was greater than 0.90.

Conclusions

Inflammation, oxidative stress and energy metabolism abnormalities, glycerolipid metabolism, and glutamate-centered metabolism are associated with the pathogenesis of ESRD with depression, which may be promising targets for therapy. Furthermore, the identified differential metabolites may serve as biomarkers for the diagnosis of ESRD patients with depression.

1-Hydroxypyrene mediates renal fibrosis through aryl hydrocarbon receptor signalling pathway

BACKGROUND AND PURPOSE

In chronic kidney disease (CKD), patients inevitably reach end-stage renal disease and require renal transplant. Evidence suggests that CKD is associated with metabolite disorders. However, the molecular pathways targeted by metabolites remain enigmatic. Here, we describe roles of 1-hydroxypyrene in mediating renal fibrosis.

EXPERIMENTAL APPROACH

We analysed 5406 urine and serum samples from patients with Stage 1-5 CKD using metabolomics, and 1-hydroxypyrene was identified and validated using longitudinal and drug intervention cohorts as well as 5/6 nephrectomised and adenine-induced rats.

KEY RESULTS

We identified correlations between the urine and serum levels of 1-hydroxypyrene and the estimated GFR in patients with CKD onset and progression. Moreover, increased 1-hydroxypyrene levels in serum and kidney tissues correlated with decreased renal function in two rat models. Up-regulated mRNA expression of aryl hydrocarbon receptor and its target genes, including CYP1A1, CYP1A2 and CYP1B1, were observed in patients and rats with progressive CKD. Further we showed up-regulated mRNA expression of aryl hydrocarbon receptor and its three target genes, plus up-regulated nuclear aryl hydrocarbon receptor protein levels in mice and HK-2 cells treated with 1-hydroxypyrene, which caused accumulation of extracellular matrix components. Treatment with aryl hydrocarbon receptor short hairpin RNA or flavonoids inhibited mRNA expression of aryl hydrocarbon receptor and its target genes in 1-hydroxypyrene-induced HK-2 cells and mice.

CONCLUSION AND IMPLICATIONS

Metabolite 1-hydroxypyrene was demonstrated to mediate renal fibrosis through activation of the aryl hydrocarbon receptor signalling pathway. Targeting aryl hydrocarbon receptor may be an alternative therapeutic strategy for CKD progression.

Integrated metabolomics coupled with pattern recognition and pathway analysis to reveal molecular mechanism of cadmium-induced diabetic nephropathy

Diabetic nephropathy (DN) is becoming a worldwide public health problem and its pathophysiological mechanism is not well understood. Emerging evidences indicated that cadmium (Cd), an industrial material but also an environmental toxin, may be involved in the development and progression of diabetes and diabetes-related kidney disease. However, the underlying mechanism is still unclear. Herein, a DN animal model was constructed by exposing to Cd, the metabolomic profiling of DN mice were obtained by using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS), pattern recognition and pathway analysis were performed to screen potential biomarker. Moreover, western blotting was employed to verify the possible mechanism involved in the occurrence of Cd-induced DN. A total of 66 metabolites in serum have been screened out and identified as biomarkers, including free fatty acids, phospholipids, sphingomyelins, glycerides, and others. Significant differences were demonstrated between the metabolic profiles, including decreased levels of phospholipid and increased content of triglyceride, diacylglycerols, ceramide, lysophosphatidylcholine in Cd-induced DN mice compared with control. Protein expression level of p38 MAPK and Wnt/β-catenin were significantly increased. UPLC-Q-TOF/MS-based serum metabolomics coupled with pattern recognition methods and pathway analysis provide a powerful approach to identify potential biomarkers and is a new strategy to predict the underlying mechanism of disease caused by environmental toxicant.

Evaluation of liver tissue extraction protocol for untargeted metabolomics analysis by ultra-high-performance liquid chromatography/tandem mass spectrometry

The aim of the untargeted metabolomics study is to obtain a global metabolome coverage from biological samples. Therefore, a comprehensive and systematic protocol for tissue metabolite extraction is highly desirable. In this study, we evaluated a comprehensive liver pretreatment strategy based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry to obtain more metabolites using four different protocols. These protocols included (A) methanol protein precipitation, (B) two-step extraction of dichloromethane-methanol followed by methanol-water, (C) two-step extraction of methyl tert-butyl ether-methanol followed by methanol-water, and (D) two-step extraction of isopropanol-methanol followed by methanol-water. Our results showed that protocol D was superior to the others due to more extracted features, annotated metabolites, and better reproducibility. And then, the stability and extraction sequence of protocol D were evaluated. The results showed that extraction with isopropanol-methanol followed by methanol-water was the optimum preparation sequence, which offered higher extraction efficiency, satisfactory repeatability, and acceptable stability. Furthermore, the optimal protocol was successfully applied by liver samples of rats after high-fat intervention. In summary, our protocol enabled a comprehensive and systematic evaluation of liver pretreatment to obtain more medium-polar and nonpolar metabolites and was suitable for high-throughput metabolomics analysis.

The Dysregulation of Eicosanoids and Bile Acids Correlates with Impaired Kidney Function and Renal Fibrosis in Chronic Renal Failure

Chronic renal failure (CRF) is an irreversible deterioration of the renal functions that characterized by fluid electrolyte unbalance and metabolic-endocrine dysfunctions. Increasing evidence demonstrated that metabolic disturbances, especially dyslipidemia and profound changes in lipid and lipoprotein metabolism were involved in CRF. Identification of lipids associated with impaired kidney functions may play important roles in the understanding of biochemical mechanism and CRF treatment. Ultra-performance liquid chromatography coupled with high-definition mass spectrometry-based lipidomics was performed to identify important differential lipids in adenine-induced CRF rats and investigate the undergoing anti-fibrotic mechanism of Polyporus umbellatus (PPU) and ergone (ERG). Linear correlation analysis was performed between lipid species intensities and creatinine levels in serum. Adenine-induced rats exhibited declining kidney function and renal fibrosis. Compared with control rats, a panel of lipid species was identified in the serum of CRF rats. Our further study demonstrated that eight lipids, including leukotrienes and bile acids, presented a strong linear correlation with serum creatinine levels. In addition, receiver operating characteristics analysis showed that eight lipids exhibited excellent area under the curve for differentiating CRF from control rats, with high sensitivity and specificity. The aberrant changes of clinical biochemistry data and dysregulation of eight lipids could be significantly improved by the administration of PPU and ergone. In conclusion, CRF might be associated with the disturbance of leukotriene metabolism, bile acid metabolism and lysophospholipid metabolism. The levels of eicosanoids and bile acids could be used for indicating kidney function impairment in CRF. PPU could improve renal functions and either fully or partially reversed the levels of eicosanoids and bile acids.

Polyporus Umbellatus Protects Against Renal Fibrosis by Regulating Intrarenal Fatty Acyl Metabolites

Background: Chronic renal failure (CRF) results in significant dyslipidemia and profound changes in lipid metabolism. Polyporus umbellatus (PPU) has been shown to prevent kidney injury and subsequent kidney fibrosis.

Methods: Lipidomic analysis was performed to explore the intrarenal profile of lipid metabolites and further investigate the effect of PPU and its main bioactive component, ergone, on disorders of lipid metabolism in rats induced by adenine. Univariate and multivariate statistical analyses were performed for choosing intrarenal differential lipid species in CRF rats and the intervening effect of n-hexane extract of PPU and ergone on CRF rats.

Results: Compared with control group, decreased creatinine clearance rate indicated declining kidney function in CRF group. Based on the lipidomics, we identified 65 lipid species that showed significant differences between CRF and control groups. The levels of 12 lipid species, especially fatty acyl lipids including docosahexaenoic acid, docosapentaenoic acid (22n-3), 10,11-Dihydro-12R-hydroxy-leukotriene C4, 3-hydroxydodecanoyl carnitine, eicosapentaenoic acid, hypogeic acid and 3-hydroxypentadecanoic acid had a strong linear correlation with creatinine clearance rate, which indicated these lipid species were associated with impaired renal function. In addition, receiver operating characteristics analysis showed that 12 lipid species had high area under the curve values with high sensitivity and specificity for differentiating CRF group from control group. These changes are related to the perturbation of fatty acyl metabolism. Treatment with PPU and ergone improved the impaired kidney function and mitigated renal fibrosis. Both chemometrics and cluster analyses showed that rats treated by PPU and ergone could be separated from CRF rats by using 12 lipid species. Intriguingly, PPU treatment could restore the levels of 12 lipid species, while treatment with ergone could only reverse the changes of six fatty acids in CRF rats.

Conclusion: Altered intrarenal fatty acyl metabolites were implicated in pathogenesis of renal fibrosis. PPU and ergone administration alleviated renal fibrosis and partially improved fatty acyl metabolism. These findings suggest that PPU exerted its renoprotective effect by regulating fatty acyl metabolism as a potential biochemical mechanism. Therefore, these findings indicated that fatty acyl metabolism played an important role in renal fibrosis and could be considered as an effective therapeutic avenue against renal fibrosis.

Antioxidation, anti-inflammation and anti-fibrosis effect of phosphorylated polysaccharides from Pleurotus djamor mycelia on adenine-induced chronic renal failure mice

The mycelia polysaccharides (MPS) from Pleurotus djamor were prepared and purified by anion exchange column chromatography, and the phosphate content of phosphorylated MPS (PMPS) was 15.22 ± 0.37%. FT-IR spectra, HPLC and ¹H and ¹³C-NMR results showed the PMPS contained α-pyranose structure and the peak area percentage composition of galacturonic acid and glucose were 13.01% and 85.82%, respectively. Animal experiment investigated the antioxidant, anti-inflammation, anti-fibrosis effects of PMPS on kidney in adenine-induced chronic renal failure (CRF) mice. All results including serum biochemical indices, histopathological observation, qRT-PCR, western blotting, immunohistochemical staining manifested the kidney injury could be remitted by PMPS interventions. This experiment suggested that PMPS could remit CRF and other kidney injury related diseases as one kind of dietary supplements and functional foods without toxic side effects.

The Erythrocyte Membrane Lipidome of Healthy Dogs: Creating a Benchmark of Fatty Acid Distribution and Interval Values

Molecular-based approaches are rapidly developing in medicine for the evaluation of physiological and pathological conditions and discovery of new biomarkers in prevention and therapy. Fatty acid diversity and roles in health and disease in humans are topical subjects of lipidomics. In particular, membrane fatty acid-based lipidomics provides molecular data of relevance in the study of human chronic diseases, connecting metabolic, and nutritional aspects to health conditions. In veterinary medicine, membrane lipidomics, and fatty acid profiles have not been developed yet in nutritional approaches to health and in disease conditions. Using a protocol widely tested in human profiling, in the present study erythrocyte membrane lipidome was examined in 68 clinically healthy dogs, with different ages, sex, and sizes. In particular, a cluster composed of 10 fatty acids, present in membrane glycerophospholipids and representative of structural and functional properties of cell membrane, was chosen, and quantitatively analyzed. The interval values and distribution for each fatty acid of the cluster were determined, providing the first panel describing the healthy dog lipidomic membrane profile, with interesting correlation to bodyweight increases. This molecular information can be advantageously developed as benchmark in veterinary medicine for the evaluation of metabolic and nutritional status in healthy and diseased dogs.

The Serum Metabolic Biomarkers in Early Diagnosis and Risk Stratification of Acute Coronary Syndrome

Despite advances in the treatment of coronary diseases, acute coronary syndrome (ACS) remains the leading cause of death worldwide. ACS is associated with metabolic abnormalities of lipid oxidation stress. In this study, based on liquid chromatograph mass spectrometry technique, we conducted the metabolic profiling analysis of serum samples from stable plaques (SPs) and vulnerable plaques (VPs) in ACS patients for exploring the potential biomarkers of plaque stability. The results showed that four differential metabolites were identified between the SPs and VPs, including betaine, acetylcarnitine, 1-heptadecanoyl-sn-glycero-3-phosphocholine, and isoundecylic acid. Meanwhile, the diagnostic model was identified using stepwise logistic regression and internally validated with 10-fold cross-validation. We analyzed the correlations between serum metabolic perturbations and plaque stability, and the serum betaine and ejection fraction-based model was established with a good diagnostic efficacy [area under the curve (AUC) = 0.808, sensitivity = 70.6%, and specificity = 80.0%]. In summary, we firstly illustrate the comprehensive serum metabolic profiles in ACS patients, suggesting that the combined model of serum betaine and ejection fraction seems to be used as the potential diagnostic biomarker for the vulnerability of plaque stability.

Identification of endogenous 1-aminopyrene as a novel mediator of progressive chronic kidney disease via aryl hydrocarbon receptor activation

BACKGROUND AND PURPOSE

Increasing evidence has indicated that the high risk of cardiovascular disease in chronic kidney disease (CKD) patients cannot be sufficiently explained by classic risk factors.

EXPERIMENTAL APPROACH

Based on the least absolute shrinkage and selection operator method, we identified significantly altered renal tissue metabolites during progressive CKD in a 5/6 nephrectomized rat model and in CKD patients.

KEY RESULTS

Six aryl-containing metabolites (ACMs) were significantly increased from Week 1 to Week 20. They were associated with the activation of aryl hydrocarbon receptor (AhR) and its target genes including CYP1A1, CYP1A2 and CYP1B1, which were further validated by molecular docking. Our study further demonstrated that AhR signalling could be activated by ACM in patients with idiopathic membranous nephropathy, diabetic nephropathy and IgA nephropathy. Most importantly, 1-aminopyrene (AP) showed strong positive and negative correlation with serum creatinine and creatinine clearance, respectively. AP significantly up-regulated the mRNA expressions of AhR and its three target genes in both mice and NRK-52E cells, while this effect was partially weakened in AhR small hairpin RNA-treated mice and NRK-52E cells. Furthermore, dietary flavonoid supplementation ameliorated CKD and renal fibrosis through partially inhibiting the AhR activity via lowering the ACM levels. The antagonistic effect of flavonoids on AhR was deeply influenced by the number and location of hydroxyl and glycosyl groups.

CONCLUSION AND IMPLICATIONS

We uncovered that endogenous AP is a novel mediator of CKD progression via AhR activation; thus, AhR might serve as a promising target for CKD treatment.

Metabolomics approach based on utra-performance liquid chromatography coupled to mass spectrometry with chemometrics methods for high-throughput analysis of metabolite biomarkers to explore the abnormal metabolic pathways associated with myocardial dysfunction

Ultra-performance liquid chromatography/mass spectrometry-based metabolomics can been used for discovery of metabolite biomarkers to explore the metabolic pathway of diseases. Identification of metabolic pathways is key to understanding the pathogenesis and mechanism of disease. Myocardial dysfunction induced by sepsis (SMD) is a severe complication of septic shock and represents major causes of death in intensive care units; however its pathological mechanism is still not clear. In this study, ultrahigh-pressure liquid chromatography with mass spectrometry-based metabolomics with chemometrics anaylsis and multivariate pattern recognition analysis were used to detect urinary metabolic profile changes in a lipopolysaccharide-induced SMD mouse model. Multivariate statistical analysis including principal component analysis and orthogonapartial least squares discriminant analysis for the discrimination of SMD was conducted to identify potential biomarkers. A total of 19 differential metabolites were discovered by high-resolution mass spectrometry-based urinary metabolomics strategy. The altered biochemical pathways based on these metabolites showed that tyrosine metabolism, phenylalanine metabolism, ubiquinone biosynthesis and vitamin B6 metabolism were closely connected to the pathological processes of SMD. Consequently, integrated chemometric analyses of these metabolic pathways are necessary to extract information for the discovery of novel insights into the pathogenesis of disease.

4-Octyl itaconate protects against renal fibrosis via inhibiting TGF-β/Smad pathway, autophagy and reducing generation of reactive oxygen species

Renal fibrosis is an inevitable course of all kinds of progressive chronic kidney disease (CKD). Itaconic acid is an endogenous metabolite that has shown anti-inflammatory and antioxidant effects. 4-octyl itaconate (OI), a derivative of itaconic acid with higher fat solubility, can penetrate the cell membranes and be metabolized into itaconic acid in vitro. However, whether OI has an anti-renal fibrotic effect is still unclear. The current study purposed to investigate the anti-fibrotic effect in renal and the underlying mechanisms of OI. The unilateral ureteral occlusion (UUO) model and adenine-induced fibrosis model in Sprague-Dawley (SD) rats and Transforming growth factor-β1 (TGF-β1) induced HK-2 cells were applied to investigate the renoprotective effects of OI. This study reports for the first time that OI ameliorated renal fibrosis by suppressing the activation of TGF-β/Smad and nuclear factor kappa B (NF-κB) pathways, reducing generation of reactive oxygen species and inhibiting autophagy. These results clearly suggest that OI has great clinical potential for managing renal fibrosis.

UPLC-HDMS-based on serum metabolomics reveals the toxicity of arecae semen

ETHNOPHARMACOLOGICAL RELEVANCE

Arecae semen has been used as vermifuge and digestant in traditional Chinese medicine (TCM) for more than one thousand years. However, the toxicity effect of areca semen and its underlying mechanism are still unclear.

THE AIM OF THE STUDY

This study was aimed to investigate the toxicity of arecae semen and to explore its mechanisms by serum metabolomics.

MATERIALS AND METHODS

The male Wistar rats were divided into the control group and treated group (n = 6 in each group), which were given by gavage with distill water or arecae semen aqueous extract (ASAE) once a day for 30 days, respectively. Serum samples were collected from all the rats after treatment of 7-day, 14-day and 30-day for metabolomics analysis. Moreover, biochemistry analysis and histopathological examination were performed at the end of study.

RESULTS

The phenomenon of diarrhea, less physical activity, tremors and body curl up were observed in the treated group. Additionally, the body weights of treated rats were significantly decreased compared with control rats from the 8th day after oral administration. Except the level of creatinekinase (CK) in the treated group significantly increased compared with the control group, there were no differences on biochemistry parameters and histopathological test in the two groups. Combined with the methods of principal component analysis (PCA), orthogonal projection to latent structure-discrimination analysis (OPLS-DA) and available databases, the treated and control rats were clearly distinguished from each other and 19 metabolites were identified as the potential biomarkers in the arecae semen treated rats. The identified biomarkers indicated that there were perturbations of the phospholipid metabolism, amino acid metabolism and fat acid metabolism in the treated group.

CONCLUSIONS

This indicated that arecae semen possessed certain cardiotoxicity and inhibited the normal growth in Wistar male rats. In addition, the metabolomics approach is a useful tool to study the toxicity in TCM.

Toxicity and Its Mechanism Study of Arecae semen Aqueous Extract in Wistar Rats by UPLC-HDMS-Based Serum Metabolomics

Background

Arecae semen (AS) is officially recorded in Chinese Pharmacopoeia and it is known for its multiple functions, including antidepressive, antioxidant, anti-inflammatory, and cholesterol-lowering effects, which have been confirmed by modern pharmacological study. Previous study in our laboratory showed that long-term oral administration of Arecae semen (AS) is officially recorded in Chinese Pharmacopoeia and it is known for its multiple functions, including antidepressive, antioxidant, anti-inflammatory, and cholesterol-lowering effects, which have been confirmed by modern pharmacological study. Previous study in our laboratory showed that long-term oral administration of Hypothesis. The aim of this work was to characterize the metabolome, evaluate the metabolic changes, and study the mechanisms of the toxicity induced by different treatment doses of ASAE via metabolomics.

Methods

Wistar rats were administered orally two different doses of ASAE (1500 and 4500 mg/kg/d) for 30 days. The investigation was carried out to evaluate the safety of ASAE. And, the UPLC-HDMS-based serum metabolomics in conjunction with multivariate statistical techniques was applied to investigate the serum metabolite profile and potential markers of toxicity induced by different doses of ASAE.

Results

Coupled with blood biochemistry and histopathology results, the significant difference in metabolic profiling was observed between 1500 and 4500 mg/kg/d dosages of ASAE-treated rats and normal rats by using pattern recognition analysis, indicating that changes in serum metabolites must have occurred. Some significant changed metabolites such as arachidonic acid, linoleic acid, stearic acid, and LPC (18 : 1) have been found and identified. These biochemical changes in serum metabolites are related to the perturbation of linoleic acid metabolism, arachidonic acid metabolism, glycerophospholipid metabolism, and purine metabolism, which may be helpful to further understand the cardiotoxicity and neurotoxicity of ASAE.

Conclusion

The study shows that the metabolomic method may be a valuable tool for studying the essence of toxicity induced by traditional Chinese medicine.

Yiqihuoxue Formula Activates Autophagy and Offers Renoprotection in a Rat Model of Adenine-Induced Kidney Disease

Chronic kidney disease (CKD) is a worldwide health problem for which effective therapeutic methods are still lacking. Traditional Chinese medicine (TCM) has been indicated as an effective alternative treatment for kidney disease. In this study, a clinically effective therapy, yiqihuoxue (YQHX) formula, was administrated to adenine-induced kidney disease rats for 6 weeks. We found that the adenine rats displayed a significant reduction in renal function as evidenced by the increased levels of serum creatinine (Scr), blood urea nitrogen (BUN), and 24-h urinary albumin level, which were attenuated by the YQHX treatment. The glomerulosclerosis, interstitial fibrosis, arteriolosclerosis, interstitial inflammation, and tubular dilatation were reversed by the YQHX treatment in the adenine rats. Furthermore, the hepatic damage characterized by increased levels of aspartate aminotransferase and alanine aminotransferase and inflammatory cell infiltration was improved by YQHX. In addition, the number of apoptotic cells in the adenine rats was obviously reduced by the YQHX treatment as manifested by the lower expression level of cleaved caspase-3 protein. Moreover, the YQHX treatment downregulated the expression levels of fibronectin, type I collagen, α-smooth muscle actin, and TGF-β1 in the adenine rats. Furthermore, autophagy was activated by the YQHX treatment, which manifested as an increased LC3-II and Beclin-1 expression levels and a decreased p62 level. In conclusion, the YQHX formula might retard the progression of kidney disease by activating autophagy.

High-throughput liquid chromatography mass-spectrometry-driven lipidomics discover metabolic biomarkers and pathways as promising targets to reveal the therapeutic effects of the Shenqi pill

Lipidomics, a branch of metabonomics, could provide a powerful technique for discovery of lipid molecules to reveal disease status and drug efficacy.

Identification of Potential Serum Metabolic Biomarkers of Diabetic Kidney Disease: A Widely Targeted Metabolomics Study

Background and Objectives. Diabetic kidney disease is a leading cause of chronic kidney disease and end-stage renal disease across the world. Early identification of DKD is vitally important for the effective prevention and control of it. However, the available indicators are doubtful in the early diagnosis of DKD. This study is aimed at determining novel sensitive and specific biomarkers to distinguish DKD from their counterparts effectively based on the widely targeted metabolomics approach. Materials and Method. This case-control study involved 44 T2DM patients. Among them, 24 participants with DKD were defined as the cases and another 20 without DKD were defined as the controls. The ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry system was applied for the assessment of the serum metabolic profiles. Comprehensive analysis of metabolomics characteristics was conducted to detect the candidate metabolic biomarkers and assess their capability and feasibility.

RESULT

A total of 11 differential metabolites, including Hexadecanoic Acid (C16:0), Linolelaidic Acid (C18:2N6T), Linoleic Acid (C18:2N6C), Trans-4-Hydroxy-L-Proline, 6-Aminocaproic Acid, L-Dihydroorotic Acid, 6-Methylmercaptopurine, Piperidine, Azoxystrobin Acid, Lysopc 20:4, and Cuminaldehyde, were determined as the potential biomarkers for the DKD early identification, based on the multivariable generalized linear regression model and receiver operating characteristic analysis.

CONCLUSION

Serum metabolites might act as sensitive and specific biomarkers for DKD early detection. Further longitudinal studies are needed to confirm our findings.

Machine learning distilled metabolite biomarkers for early stage renal injury

INTRODUCTION

With chronic kidney disease (CKD), kidney becomes damaged overtime and fails to clean blood. Around 15% of US adults have CKD and nine in ten adults with CKD do not know they have it.

OBJECTIVE

Early prediction and accurate monitoring of CKD may improve care and decrease the frequent progression to end-stage renal disease. There is an urgent demand to discover specific biomarkers that allow for monitoring of early-stage CKD, and response to treatment.

METHOD

To discover such biomarkers, shotgun high throughput was applied to the detection of serum metabolites biomarker discovery for early stages of CKD from 703 participants. Ultra performance liquid chromatography coupled with high-definition mass spectrometry (UPLC-HDMS)-based metabolomics was used for the determination of 703 fasting serum samples from five stages of CKD patients and age-matched healthy controls.

RESULTS AND CONCLUSION

We discovered a set of metabolite biomarkers using a series of classic and neural network based machine learning techniques. This set of metabolites can separate early CKD stage patents from normal subjects with high accuracy. Our study illustrates the power of machine learning methods in metabolite biomarker study.

Microbiome-metabolomics reveals gut microbiota associated with glycine-conjugated metabolites and polyamine metabolism in chronic kidney disease

Dysbiosis of the gut microbiome and related metabolites in chronic kidney disease (CKD) have been intimately associated with the prevalence of cardiovascular diseases. Unfortunately, thus far, there is a paucity of sufficient knowledge of gut microbiome and related metabolites on CKD progression partly due to the severely limited investigations. Using a 5/6 nephrectomized (NX) rat model, we carried out 16S rRNA sequence and untargeted metabolomic analyses to explore the relationship between colon's microbiota and serum metabolites. Marked decline in microbial diversity and richness was accompanied by significant changes in 291 serum metabolites, which were mediated by altered enzymatic activities and dysregulations of lipids, amino acids, bile acids and polyamines metabolisms. Interestingly, CCr was directly associated with some microbial genera and polyamine metabolism. However, SBP was directly related to certain microbial genera and glycine-conjugated metabolites in CKD rats. Administration of poricoic acid A (PAA) and Poria cocos (PC) ameliorated microbial dysbiosis as well as attenuated hypertension and renal fibrosis. In addition, treatments with PAA and PC lowered serum levels of microbial-derived products including glycine-conjugated compounds and polyamine metabolites. Collectively, the present study confirmed the CKD-associated gut microbial dysbiosis and identified a novel dietary and therapeutic strategy to improve the gut microbial dysbiosis and the associated metabolomic disorders and retarded the progression of kidney disease in the rat model of CKD.

Promotion of a quality standard for Porana sinensis Hemsl. based on the efficacy-oriented Effect-Constituent Index

Multicompound determination for the quality control of traditional Chinese medicine (TCM) may often be inadequate, since these compounds may not be associated with, or fully represent, the clinical effects of TCM. Moreover, the individual contributions of each constituent to the pharmacological effect are often not considered. In China, Porana sinensis is widely used as a substitute for Erycibe sources to treat joint pain and rheumatoid arthritis. The existing quality control methods for P. sinensis neither consider the individual contributions of various compounds nor control the actual quality associated with different clinical efficacies. In the present study, a novel efficacy-oriented approach, named the effect-constituent index (ECI), was established for P. sinensis. Analyses of the spectrum-effect relationship and components in rat plasma were conducted to systematically and scientifically select quality markers. Quantitative analysis of multicomponents via a single marker method was introduced to enhance the practical application value of the established ECI. The established ECI shows a good ability to distinguish and predict the bioeffect-based quality of P. sinensis. The present study also provides a reference for the establishment and application of ECI as a quality control method for TCMs.

Therapeutic Effect and Mechanism Study of Rhodiola wallichiana var. cholaensis Injection to Acute Blood Stasis Using Metabolomics Based on UPLC-Q/TOF-MS

In traditional Chinese medicine theory, blood stasis syndrome (BSS), characterized by blood flow retardation and blood stagnation, is one of the main pathologic mechanisms and clinical syndromes of cardiovascular diseases (CVDs). Rhodiola wallichiana var. cholaensis injection (RWCI) is made from dry roots and stems of RWC via the processes of decoction, alcohol precipitation, filtration, and dilution. Studies indicated the extracts of RWC could alleviate CVDs; however, the mechanism had not been illustrated. In the present study, the acute blood stasis rat model was established to investigate the pathogenesis of BSS and the therapeutic mechanism of RWCI against BSS. Hemorheological parameters (whole blood viscosity and plasma viscosity) and inflammatory factors (TNF-α and IL-6) were used to evaluate the success of the BSS rat model and RWCI efficacy. 14 and 33 differential metabolites were identified from plasma and urine samples using the metabolomics approach based on ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The results of multivariate analysis displayed that there were significant separations among model, control, and treatment groups, but the high-dose RWCI treatment group was closer to the control group. 9 perturbed metabolic pathways were related to BSS's development and RWCI intervention. 5 metabolic pathways (arachidonic acid metabolism, linoleic acid metabolism, alpha-linolenic acid metabolism, retinol metabolism, and steroid hormone biosynthesis) showed apparent correlations. These differential metabolites and perturbed metabolic pathways might provide a novel view to understand the pathogenesis of BSS and the pharmacological mechanism of RWCI.

Discrimination of Different Parts of Saffron by Metabolomic-Based Ultra-Performance Liquid Chromatography Coupled with High-Definition Mass Spectrometry

In this study, the metabolite profiling of three different parts of Crocus sativus L. was measured by using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTof-MS/MS). Multivariate statistical analysis was used to distinguish among the samples from different parts. A total of 54 compounds were identified in tepals, stigmas and stamens by UPLC-QTof-MS/MS. The results stated that chemical characteristics of saffron were obviously diverse in terms of the parts of flower. Through analysis, coniferin and crocin-2 were special components in stigmas when compared to tepals and stamens. The content of flavonoids was high in tepals when compared with the stigmas. The tepal of saffron may processed as a source of flavonoids in the future. The research provided the basis for the theory that only the stigma can be used as medicine.

Chronic kidney disease: Biomarker diagnosis to therapeutic targets

Chronic kidney disease (CKD), characterized as renal dysfunction, is recognized as a major public health problem with high morbidity and mortality worldwide. Unfortunately, there are no obvious clinical symptoms in early stage disease until severe damage has occurred. Further complicating early diagnosis and treatment is the lack of sensitive and specific biomarkers. As such, novel biomarkers are urgently needed. Metabolomics has shown an increasing potential for identifying underlying disease mechanisms, facilitating clinical diagnosis and developing pharmaceutical treatments for CKD. Recent advances in metabolomics revealed that CKD was closely associated with the dysregulation of numerous metabolites, such as amino acids, lipids, nucleotides and glycoses, that might be exploited as potential biomarkers. In this review, we summarize recent metabolomic applications based on animal model studies and in patients with CKD and highlight several biomarkers that may play important roles in diagnosis, intervention and development of new therapeutic strategies.

Fumonisin B1 induced compositional modifications of the renal and hepatic membrane lipids in rats - Dose and exposure time dependence

Male Wistar rats were intraperitoneally dosed with fumonisin B1 (FB₁; 0, 20, 50 and 100 mg kg^-1 dietary dose equivalent) for 5 & 10 days to assess dose- and time-dependent effects on renal and hepatic phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidylethanolamine (PE) fatty acid (FA) profiles. Renal PC showed increasing FA saturation (SAT) after 5 days; after 10 days polyunsaturation (PUFA) decreased markedly (Σ n3 (total n3), Σ n6, PUFA, unsaturation index (UI) and average FA chain length (ACL)), mostly with linear dose response. In the PI FAs similar changes were observed, decreasing monounsaturated FA, PUFA, UI and ACL (5 & 10 days), while the PE fraction was responsive in Σ n6 (↓) and SAT (↑), but only after 5 days (without dose response for both PI & PE). Liver PC exhibited increasing saturation (C16:0), decreasing polyunsaturation (C20:3 n6 [dihomo-γ-linolenic acid, DGLA]; C20:3 n3); the PI FA profile showed similar alterations after 5 days. PC & PI FA failed to respond in a dose-dependent manner to FB₁. In PE FA profile DGLA decreased, with a decrease of the total n6 FA proportion and dose-dependent increase of n3 FAs. Results revealed expressed renal sensitivity, supporting our earlier published results in terms of oxidative stress and histopathological modifications.

Metabolomics analysis of Pulsatilla decoction on treatment of wetness-heat-induced diarrhea in rats based on UPLC-Q/TOF-MS/MS

Pulsatilla decoction (PD) is a classical prescription in traditional Chinese medicine that has therapeutic effects on wetness-heat-induced diarrhea (WHD). To investigate the therapeutic effects of PD in the treatment of WHD and elucidate the potential mechanism, we used a metabolomics strategy on the base of ultraperformance liquid chromatography coupled with quadrupole time-of-flight/mass spectrometry (UPLC-Q/TOF-MS/MS) and analyzed the serum samples of 32 rats to identify differential metabolites and pathways associated with the PD treatment of WHD. With variable importance for projection >1.0 in the Orthogonal partial least-squares discriminant analysis (OPLS-DA ) models and FC ≥1.2 or ≤0.8, 67 differential metabolites in the model and control groups and 33 differential metabolites in the model and PD groups were screened. A total of 23 differential metabolites were selected based on Venny analysis. Functional analysis showed that the differential metabolites identified were primarily involved in pentose and glucuronate interconversions, glycerophospholipid metabolism, tryptophan metabolism, starch and sucrose metabolism, and glycerolipid metabolism. This study suggested that PD exerts inhibitory effects on WHD. In particular, the significant roles of PD for treating WHD lie in regulating perturbed energy metabolism, glycerophospholipid metabolism and glycerolipid metabolism, and promoting lysoPC production restoring the function of intestinal tract.

Activated NF-κB/Nrf2 and Wnt/β-catenin pathways are associated with lipid metabolism in CKD patients with microalbuminuria and macroalbuminuria

Early diagnosis of CKD patients at risk for microalbuminuria or macroalbuminuria could facilitate clinical outcomes and long-term survival. Considering the few and limited efficacy of current biomarkers in early detection, we aim to discover plasma lipids that effectively predict the development of CKD paitents with microalbuminuria or macroalbuminuria. A total of 380 healthy controls and 1156 patients with CKD stages 3 to 5 were stratified by urine albumin-creatinine ratio as microalbuminuria (30-300 mg/g) and macroalbuminuria (>300 mg/g). Fasting plasma samples were determined by UPLC-HDMS based on lipidomics. Quantitative real-time polymerase chain reaction, Western blot and immunohistochemical analyses were used to validate the lipid metabolism-associated pathways. Pathway analysis demonstrated that these lipids were closely associated with PPARγ, inflammatory mediator regulation of TRP channels and RAS signaling, which were intimately involved in activated NF-κB and Nrf2 pathways. We further carried out pathway validation and demonstrated that NF-κB pathway was activated in patients with macroalbuminuria compared with CKD patients with microalbuminuria, while Nrf2-associated protein expression was downregulated, which was accompanied by the up-regulation of Wnt/β-catenin signaling pathway. Four lipids including DTA, 5,8-TDA, GGD3 and DHA that showed great potential in the discrimination of CKD patients with microalbuminuria and healthy controls were selected by logistic regression analysis. Additionally, six lipid species including CDCA, glucosylceramide, GGD2, TTA, DHA and EDA that contributed to the discrimination of CKD patients with microalbuminuria and macroalbuminuria were selected by logistic LASSO regression Gangliosides were first identified and might be promising therapeutic targets for CKD patients with the different degree of albuminuria. Collectively, this study first demonstrates the association of plasma inflammation, oxidative stress, Wnt/β-catenin and lipid metabolism in CKD patients with microalbuminuria and macroalbuminuria.

Anemoside B4 Protects Rat Kidney from Adenine-Induced Injury by Attenuating Inflammation and Fibrosis and Enhancing Podocin and Nephrin Expression

Anemoside B4 (B4) isolated from Radix Pulsatilla has anti-inflammatory activities in the colon and antitumor effects. However, its role in the prevention and treatment of kidney injury has not been reported. Here, we reported the effects of B4 on chronic kidney injury (CKI) and studied its related mechanism based on an adenine-induced kidney injury model in rats. The results showed that serum BUN (blood urea nitrogen), Crea (creatinine), and urinary proteins increased significantly after oral administration of adenine. Meanwhile, the adenine contents in both renal tissue and urine increased markedly compared with those of normal rats. Moreover, IL-1β, IL-6, TNFα, and NFκB expression was upregulated in the kidney. Simultaneously, the expression of NLRP3 (the nucleotide-binding and oligomerization domain–like receptor, leucine-rich repeat and pyrin domain–containing 3) in the inflammasome, which consists of Caspase 1, ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain), and IL-18, was significantly upregulated. B4 could significantly decrease BUN and Crea; reduce urinary proteins in rats; suppress the expression of IL-6, IL-1β, NFκB, NLRP3, Caspase 1, ASC, and IL-18; and increase urinary adenine contents and promote its excretion. In addition, B4 also upregulated the expression of podocin and nephrin, two major podocyte proteins, and reduced the fiber collagen in the renal interstitial, suggesting that B4 could protect the glomerular matrix from adenine injury in addition to its anti-inflammatory effects. The results of this study show new perspective of B4 as a potential drug against adenine-induced renal injury.

An update of urine and blood metabolomics in chronic kidney disease

Chronic kidney disease is considered as a serious obstacle in global health, with increasing incidence and prevalence. In spite of numerous attempts by using recent omics technologies, specially metabolomics, for understanding pathophysiology, molecular mechanism and identification reliable consensus biomarkers for diagnosis and prognosis of this complex disease, the current biomarkers are still insensitive and many questions about its pathomechanism are still to be unanswered. This review is focused on recent findings about urine and serum/plasma metabolite biomarkers and changes in the pathways that occurs in the disease conditions. The urine and blood metabolome content in the normal and disease state is investigated based on the current metabolomics studies and well known metabolite candidate biomarkers for chronic kidney disease are discussed.

Identification of serum metabolites associating with chronic kidney disease progression and anti-fibrotic effect of 5-methoxytryptophan

Early detection and accurate monitoring of chronic kidney disease (CKD) could improve care and retard progression to end-stage renal disease. Here, using untargeted metabolomics in 2155 participants including patients with stage 1–5 CKD and healthy controls, we identify five metabolites, including 5-methoxytryptophan (5-MTP), whose levels strongly correlate with clinical markers of kidney disease. 5-MTP levels decrease with progression of CKD, and in mouse kidneys after unilateral ureteral obstruction (UUO). Treatment with 5-MTP ameliorates renal interstitial fibrosis, inhibits IκB/NF-κB signaling, and enhances Keap1/Nrf2 signaling in mice with UUO or ischemia/reperfusion injury, as well as in cultured human kidney cells. Overexpression of tryptophan hydroxylase-1 (TPH-1), an enzyme involved in 5-MTP synthesis, reduces renal injury by attenuating renal inflammation and fibrosis, whereas TPH-1 deficiency exacerbates renal injury and fibrosis by activating NF-κB and inhibiting Nrf2 pathways. Together, our results suggest that TPH-1 may serve as a target in the treatment of CKD.

Accurate monitoring of chronic kidney disease (CKD) progression is essential for efficient disease management. Here Chen et al. identify five serum metabolites in patients with stage 1–5 CKD whose levels associate with disease progression, and find that 5-methoxytryptophan and its regulatory enzyme TPH-1 exert anti-fibrotic effects in mouse models of kidney injury.

Evaluating the performance of sample preparation methods for ultra-performance liquid chromatography/mass spectrometry based serum metabonomics

RATIONALE

Metabonomics investigating perturbation to endogenous metabolism in response to external stimuli is emerging as a powerful tool for clinical diagnosis as well as in many other areas. The ability to retrieve reliable and reproducible information from complex biological fluids such as serum is crucial for its further applications.

METHODS

In this study, the performance of the commonly used sample preparation methods for ultra-performance liquid chromatography/mass spectrometry (UPLC/MS)-based metabonomics was investigated. Specifically, we compared the extraction efficiencies, the method reproducibility, and the ability to identify potential biomarkers using solvent-based protein precipitation and solid-phase extraction (SPE) for serum metabonomic studies. Differences between extraction methods were explored using principal component analysis (PCA) and orthogonal partial least squares-discrimination analysis (OPLS-DA).

RESULTS

Among the sample preparation methods tested, solvent-based protein precipitation using methanol has demonstrated the best analytical precision and extraction efficiency. Furthermore, this study revealed, for the first time, gender-specific differences in levels of two lysophosphatidylcholines (lysoPC 18:0 and lysoPC 18:1) in rat serum samples.

CONCLUSIONS

The performance of sample preparation methods for UPLC/MS-based serum metabonomics was evaluated systematically. Results showed sample preparation by solvent precipitation using methanol provided the best analytical precision and extraction efficiency for UPLC/MS-based serum metabonomics.

Unilateral ureteral obstruction causes gut microbial dysbiosis and metabolome disorders contributing to tubulointerstitial fibrosis

Chronic kidney disease (CKD) increases the risk and prevalence of cardiovascular disease (CVD) morbidity and mortality. Recent studies have revealed marked changes in the composition of the microbiome and the metabolome and their potential influence in renal disease and CVD via the accumulation of microbial-derived uremic toxins. However, the effect of unilateral ureteral obstruction (UUO) on the gut microbiome and circulating metabolites is unknown. Male Sprague-Dawley rats were randomized to UUO and sham-operated control groups. Renal histology, colonic microbiota, and plasma metabolites were examined two weeks later. We employed 16S rRNA sequence and untargeted metabolomic analyses to explore the changes in colonic microbiota and plasma metabolites and their relationship with tubulointerstitial fibrosis (TIF). The UUO rats exhibited tubular atrophy and dilatation, interstitial fibrosis and inflammatory cell infiltration in the obstructed kidney. UUO rats showed significant colonic enrichment and depletion of genera. Significant differences were identified in 219 plasma metabolites involved in lipid, amino acid, and bile acid metabolism, which were consistent with gut microbiota-related metabolism. Interestingly, tryptophan and its metabolites kynurenine, 5-hydroxytryptophan and 5-hydroxytryptamine levels, which were linked with TIF, correlated with nine specific genera. Plasma tryptophan level was positively correlated with Clostridium IV, Turicibacter, Pseudomonas and Lactobacillales, and negatively correlated with Oscillibacter, Blautia, and Intestinimonas, which possess the genes encoding tryptophan synthase (K16187), indoleamine 2,3-dioxygenase (K00463) and tryptophan 2,3-dioxygenase (K00453) and their corresponding enzymes (EC:1.13.11.52 and EC:1.13.11.11) that exacerbate TIF. In conclusion, UUO results in profound changes in the gut microbiome and circulating metabolites, events that contribute to the pathogenesis of inflammation and TIF.

AKF-PD alleviates diabetic nephropathy via blocking the RAGE/AGEs/NOX and PKC/NOX Pathways

Diabetic nephropathy (DN) is a major complication of diabetes. Currently, drugs are not available to effectively control the disease. Fluorofenidone (AKF-PD) is a recently developed drug; it possesses activities in reducing DN progression in preclinical research. Nonetheless, its renal protection and the underlying mechanisms have not been thoroughly investigated. We report here that AKF-PD significantly alleviatesrenal oxidative stress (OS) in db/dbmice through downregulation of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase and upregulation of glutathione peroxidase and superoxide dismutase, thereby protecting kidney from DN pathogenesis. AKF-PD likely reduces OS through the advanced glycation end products (AGE) and protein kinase C (PKC) pathways. While renal AGEs, PKCα, PKCβ, and NADPH oxidase 4 (NOX4) were all substantially upregulated in db/db mice compared to db/m animals, AKF-PD robustly downregulated all these events to the basal levelsdetected in db/m mice. In primary human renal mesangial cells (HMCs), high glucose (HG) elevated receptor for advanced glycation endproducts (RAGE), PKCα, PKCβ and NOX4 activity, and induced the production of reactive oxygen species (ROS); these events were all inhibited by AKF-PD. Furthermore, HG led to mitochondrial damagein HMCs;AKF-PD conferred protection on the damage. Knockdown of either PKCα or PKCβ reduced HG-induced ROS production and mitochondrial damage in HMCs. The knockdown significantly enhanced AKF-PD-mediated inhibition of ROS production and mitochondrial damage in HG-treated HMCs. Collectively, our study demonstrates that AKF-PD protects renal function under diabetes conditions in part through inhibition of OS during DN pathogenesis. AKF-PD can be explored for clinical applications in DN therapy.

Metabolomics Approaches for the Diagnosis and Understanding of Kidney Diseases

Diseases of the kidney are difficult to diagnose and treat. This review summarises the definition, cause, epidemiology and treatment of some of these diseases including chronic kidney disease, diabetic nephropathy, acute kidney injury, kidney cancer, kidney transplantation and polycystic kidney diseases. Numerous studies have adopted a metabolomics approach to uncover new small molecule biomarkers of kidney diseases to improve specificity and sensitivity of diagnosis and to uncover biochemical mechanisms that may elucidate the cause and progression of these diseases. This work includes a description of mass spectrometry-based metabolomics approaches, including some of the currently available tools, and emphasises findings from metabolomics studies of kidney diseases. We have included a varied selection of studies (disease, model, sample number, analytical platform) and focused on metabolites which were commonly reported as discriminating features between kidney disease and a control. These metabolites are likely to be robust indicators of kidney disease processes, and therefore potential biomarkers, warranting further investigation.

Untargeted Metabolomics Reveals the Protective Effect of Fufang Zhenshu Tiaozhi (FTZ) on Aging-Induced Osteoporosis in Mice

Fufang Zhenzhu Tiaozhi (FTZ), as an effective traditional Chinese medicine, has been prescribed for more than 20 years. It has proven clinical efficacy as a prescription for patients with dyslipidemia, glucocorticoid- and high-fat-induced osteoporosis, but its effect on osteoporosis induced by aging is still unclear. The aim of this study was to investigate the anti-osteoporosis effect of FTZ in aging mice and revealed its biochemical action mechanism using metabolomics. Model of primary osteoporosis induced by aging was established. The mice in treatment group received a therapeutic dose of oral FTZ extract once daily during the experiment. The model and control groups received the corresponding volume of oral normal saline solution. Plasma samples of all three groups were collected after 12 weeks. Clinical biochemical parameters and biomechanics were determined in the osteoporosis model induced by normal aging to evaluate anti-osteoporosis effect of FTZ. Ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) was used to analyze metabolic changes. The changes of histomorphometric and biomechanic parameters of femurs, as well as osteoblast and osteoclast activity indicated that FTZ administration reduced the risk of osteoporosis. Partial least squares discriminant analysis (PLS-DA) score plot revealed a clear separation trend between model and controls. Moreover, PLS-DA score plot indicated the anti-osteoporosis effect of FTZ with sphingosine 1-phosphate, LPA (16:0) and arachidonic acid (AA) among key biomarkers. The pivotal pathways revealed by pathway analysis including sphingolipid metabolism, glycerophospholipid metabolism, and AA metabolism. The mechanism by which FTZ reduces the risk of primary age-related osteoporosis in mice might be related to disorders of the above-mentioned pathways. FTZ has a protective effect against osteoporosis induced by aging, which may be mediated via interference with sphingolipid, glycerophospholipid, and AA metabolisms in mice.

Huangqi-Danshen Decoction Ameliorates Adenine-Induced Chronic Kidney Disease by Modulating Mitochondrial Dynamics

Chronic kidney disease (CKD) is a leading public health problem with high morbidity and mortality. However, the therapies remain limited. Traditional Chinese medicine (TCM) has been used for treating kidney disease for thousands of years and is an effective alternative treatment for CKD patients in China and other Asian countries. In the present study, we aimed to investigate the effect and mechanism of Huangqi-Danshen decoction (HDD), a TCM herbal decoction, on treating CKD. CKD rat model was induced by adding 0.75% adenine to the diet for 4 weeks. HDD extract was administrated orally to CKD rats at the dose of 4.7 g/kg/d for consecutive 4 weeks in adenine-induced CKD rats. Kidney function was evaluated by the levels of serum creatinine (Scr) and blood urea nitrogen (BUN). The pathological changes of kidney tissues were observed by periodic acid-Schiff (PAS) and Masson's trichrome staining. The proteins expression of renal fibrosis and mitochondrial dynamics were determined and quantified by Western blot analysis. CKD rats showed obvious decline in renal function as evidenced by increased levels of Scr and BUN, which were blunted by HDD treatment. HDD could also improve tubular atrophy and interstitial fibrosis of CKD rats. Moreover, HDD downregulated fibronectin, type IV collagen, and α-smooth muscle actin expression in CKD rats. Furthermore, mitochondrial dynamics was disturbed in CKD rats, which manifested as increased mitochondrial fission and decreased mitochondrial fusion. HDD treatment restored mitochondrial dynamics in CKD rats by repressing dynamin-related protein 1 and Mid 49/51 expression, promoting mitofusin 2 expression, and suppressing optic atrophy 1 proteolysis. In conclusion, HDD could significantly retard CKD progression through modulating mitochondrial dynamics.

Danshen can interact with intestinal bacteria from normal and chronic renal failure rats

Danshen (Salviae Miltiorrhizae Radix et Rhizoma, SMR) has been used as a traditional Chinese medicine in clinic for treatment of coronary heart diseases. Previous works have shown that the chronic renal failure (CRF) is closely related to changes of intestinal bacteria. The aim is to explore the interaction between active components of SMR and intestinal bacteria from normal and CRF rats. The changes of intestinal bacteria were evaluated among normal rats, CRF model rats and SMR-treated rats via 16S rRNA gene sequencing technology. UPLC-QTOF/MS was applied for the analysis and identification of metabolites. RESULTS: Results showed that the following intestinal bacteria varied significantly in CRF rats, including Mucispirillum, Kurthia, Clostridium, Blautia, Butyrivibrio, Shuttleworthia, Peptococcus, Ruminococcus, Bradyrhizobium, Methylobacterium, Azospirillum, Thalassospira, Methylophilus, Pseudomonas, peptostreptococcaceae and bacteroidales. The ethanol extract of SMR (DS) significantly regulated Shuttleworthia, peptostreptococcaceae and Pseudomonas, while the water extract (DSS) significantly affected Peptococcus, peptostreptococcaceae and Ruminococcus. Methylation, demethylation, dehydrogenation, hydrogenation and hydroxylation were the major metabolic transformation of tanshinones in vitro by intestinal bacteria. Glucuronidation, methylation and hydrogenation were the main metabolic transformation of salvianolic acids. These results showed that the bioactive components of SMR, including tanshinones and salvianolic acids, might exert the medical effect via regulation intestinal bacteria.

Natural products for the prevention and treatment of kidney disease

BACKGROUND

Chronic kidney disease (CKD) is one of the common causes resulting in a high morbidity and mortality. Renal fibrosis is the main pathological features of CKD. Natural products have begun to gain widely popularity worldwide for promoting healthcare and preventing CKD, and have been used as a conventional or complementary therapy for CKD treatment.

PURPOSE

The present paper reviewed the therapeutic effects of natural products on CKD and revealed the molecular mechanisms of their anti-fibrosis.

METHODS

All the available information on natural products against renal fibrosis was collected via a library and electronic search (using Web of Science, Pubmed, ScienceDirect, Splinker, etc.).

RESULTS

Accumulated evidence demonstrated that natural products exhibited the beneficial effects for CKD treatment and against renal fibrosis. This review presents an overview of the molecular mechanism of CKD and natural products against renal fibrosis, followed by an in-depth discussion of their molecular mechanism of natural products including isolated compounds and crude extracts against renal fibrosis in vitro and in vivo. A number of isolated compounds have been confirmed to retard renal fibrosis.

CONCLUSION

The review provides comprehensive insights into pathophysiological mechanisms of CKD and natural products against renal fibrosis. Particular challenges are presented and placed within the context of future applications of natural products against renal fibrosis.

Amelioration of diabetic nephropathy in db/db mice treated with tibetan medicine formula Siwei Jianghuang Decoction Powder extract

Siwei Jianghuang Decoction Powder (SWJH) documented originally in the Four Medical Tantras-Blue Glaze exhibited beneficial effects on diabetic nephropathy (DN) via combined synergistically action of multiple formula components including Curcumae longae Rhizoma, Berberidis dictyophyllae Cortex, Phyllanthi Fructus and Tribuli Fructus. This study investigated the effects of SWJH on DN in db/db mice and possible underlying mechanisms. The ten weeks old db/db mice treated with SWJH by intra-gastric administration once a day for 8 weeks. After 8 weeks, body weight, water and food intake of mice were recorded. The level of fasting blood glucose (FBG) was measured. Serum creatinine (Scr), blood urea nitrogen (BUN), urine microalbumin (UMAlb), serum uric acid (UA) and urinary albumin excretion (UAE) were detected. An enzyme-linked immunosorbent assay was performed to test serum vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1). Real-time PCR and Western blot analysis were used to test mRNA and protein expression of hypoxia inducible factor-1α (HIF-1α), VEGF and TGF-β1 in kidney tissue. SWJH treatment significantly reduced the levels of FBG, Scr, BUN, UMAlb, UA and UAE and retarded renal fibrosis. SWJH treatment further significantly reduced serum TGF-β1 level and downregulated the expression of HIF-1α, VEGF and TGF-β1 at both mRNA and protein levels. Principal component analysis and partial least squares regression and hierarchical cluster analysis demonstrated that SWJH treatment significantly ameliorated renal damage in DN mice. These consequences suggested that SWJH formulations were effective in the treatment of DN through regulating the HIF-1α, VEGF and TGF-β1 overexpression.

Action Mechanisms and Therapeutic Targets of Renal Fibrosis

Renal fibrosis was a chronic and progressive process affecting kidneys in chronic kidney disease (CKD), regardless of cause. Although no effective targeted therapy yet existed to retard renal fibrosis, a number of important recent advances have highlighted the cellular and molecular mechanisms underlying the renal fibrosis. The advances including TGF-β/Smad pathway, oxidative stress and inflammation, hypoxia and gut microbiota-derived from uremic solutes were highlighted that could provide therapeutic targets. New therapeutic targets and strategies that are particularly promising for development of new treatments for patients with CKD were also highlighted.