Identification of key metabolic changes in renal interstitial fibrosis rats using metabonomics and pharmacology

Metabolic reprogramming heterogeneity in chronic kidney disease

Fibrosis driven by excessive accumulation of extracellular matrix (ECM) is the hallmark of chronic kidney disease (CKD). Myofibroblasts, which are the cells responsible for ECM production, are activated by cross talk with injured proximal tubule and immune cells. Emerging evidence suggests that alterations in metabolism are not only a feature of but also play an influential role in the pathogenesis of renal fibrosis. The application of omics technologies to cell-tracing animal models and follow-up functional data suggest that cell-type-specific metabolic shifts have particular roles in the fibrogenic response. In this review, we cover the main metabolic reprogramming outcomes in renal fibrosis and provide a future perspective on the field of renal fibrometabolism.

Gut microbiota combined with fecal metabolomics reveals the effects of FuFang Runzaoling on the microbial and metabolic profiles in NOD mouse model of Sjögren's syndrome

OBJECTIVE

Sjögren's syndrome (SS) is an inflammatory autoimmune disease characterized by high levels of chronic lymphocyte infiltration. Differences and dysfunction in the gut microbiota and metabolites may be closely related to the pathogenesis of SS. The purpose of this study was to reveal the relationship between the gut microbiota and metabolome in NOD mice as a model of SS and the role of FuFang Runzaoling (FRZ), which is a clinically effective in treating SS.

METHODS

NOD mice were gavaged with FRZ for 10 weeks. The ingested volume of drinking water, submandibular gland index, pathologic changes of the submandibular glands, and serum cytokines interleukin (IL)-6, IL-10, IL-17 A, and tumor necrosis factor-alpha (TNF-α) were determined. The roles of FRZ on gut microbiota and fecal metabolites were explored by 16 S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MC), respectively. The correlation between them was determined by Pearson correlation analysis.

RESULTS

Compared with the model group, the drinking water volume of NOD mice treated with FRZ increased and the submandibular gland index decreased. FRZ effectively ameliorated lymphocyte infiltration in the small submandibular glands in mice. Serum levels of IL-6, TNF-α, and IL-17 A decreased, and IL-10 increased. The Firmicutes/Bacteroidetes ratio in the FRZ treatment group was higher. FRZ significantly downregulated the relative abundance of the family Bacteroidaceae and genus Bacteroides, and significantly upregulated the relative abundance of genus Lachnospiraceae_UCG-001. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed the significant change in fecal metabolites after FRZ treatment. Based on criteria of OPLS-DA variable influence on projection > 1, P < 0.05, and fragmentation score > 50, a total of 109 metabolites in the FRZ-H group were differentially regulated (47 downregulated and 62 upregulated) compared to their expressions in the model group. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed enriched metabolic of sphingolipid metabolism, retrograde endocannabinoid signaling, GABAergic synapse, necroptosis, arginine biosynthesis, and metabolism of histidine, alanine, aspartate, and glutamate. Correlation analysis between gut microbiota and fecal metabolites suggested that the enriched bacteria were related to many key metabolites.

CONCLUSIONS

Taken together, we found FRZ could reduce the inflammatory responses in NOD mice by regulating the gut microbiota, fecal metabolites, and their correlation to emerge a therapeutic effect on mice with SS. This will lay the foundation for the further studies and applications of FRZ, and the use of gut microbiotas as drug targets to treat SS.

Fumarate mitigates disruption induced by fenpropathrin in the silkworm Bombyx mori (Lepidoptera): A metabolomics study

The silkworm Bombyx mori L. is a model organism of the order Lepidoptera. Understanding the mechanism of pesticide resistance in silkworms is valuable for Lepidopteran pest control. In this study, comparative metabolomics was used to analyze the metabolites of 2 silkworm strains with different pesticide resistance levels at 6, 12, and 24 h after feeding with fenpropathrin. Twenty-six of 27 metabolites showed significant differences after fenpropathrin treatment and were classified into 6 metabolic pathways: glycerophospholipid metabolism, sulfur metabolism, glycolysis, amino acid metabolism, the urea cycle, and the tricarboxylic acid (TCA) cycle. After analyzing the percentage changes in the metabolic pathways at the 3 time points, sulfur metabolism, glycolysis, and the TCA cycle showed significant responses to fenpropathrin. Confirmatory experiments were performed by feeding silkworms with key metabolites of the 3 pathways. The combination of iron(II) fumarate + folic acid (IF-FA) enhanced fenpropathrin resistance in silkworms 6.38 fold, indicating that the TCA cycle is the core pathway associated with resistance. Furthermore, the disruption of several energy-related metabolic pathways caused by fenpropathrin was shown to be recovered by IF-FA in vitro. Therefore, IF-FA may have a role in boosting silkworm pesticide resistance by modulating the equilibrium between the TCA cycle and its related metabolic pathways.

Myo-Inositol Attenuates Renal Interstitial Fibrosis in Obstructive Nephropathy by Inhibiting PI3K/AKT Activation

Emerging evidence suggests that myo-inositol (MI) has a critical role in reducing renal inflammatory processes and improving podocyte function and preventing diabetes-related renal damage. We aimed to explore the function and underlying workings of MI in renal interstitial fibrosis (RIF). Based on a mouse model, we explored the effect of MI in unilateral ureteral obstruction (UUO) and in transforming growth factor-β1 (TGF-β1)-treated HK-2 cells. Pathological changes of the kidney tissues were examined following staining of the tissues with hematoxylin, eosin, and Masson's trichrome. The mRNA quantities of fibrosis markers, fibronectin, α-smooth muscle actin (α-SMA), and collagen I, were analyzed by means of real-time polymerase chain reaction, whereas those of protein levels were assessed with Western blotting. We also determined the expression of collagen I by immunofluorescence, and the levels of phosphorylated phosphotidylinositol-3-kinase and protein kinase B (PI3K/AKT) by Western blot. In vivo, histopathological examination in the UUO mice revealed renal tubular epithelial cell necrosis, inflammatory cell infiltration, and RIF. UUO mice showed higher expression levels of collagen I, fibronectin, α-SMA, pPI3K, and pAKT compared with sham-operated mice. However, MI treatment diminished the pathological alterations of RIF in UUO mice and downregulated the expression of fibrosis markers and phosphorylated PI3K/AKT. In vitro, TGF-β1 positively influenced the propagation and differentiation of HK-2 cells and upregulated the levels of α-SMA, fibronectin, collagen I, pPI3K, and pAKT, but these became significantly reversed by MI treatment. In conclusion, MI ameliorates RIF, possibly by negatively regulating TGF-β1-induced epithelial transdifferentiation and PI3K/AKT activation.

Identifying disease progression in chronic kidney disease using proton magnetic resonance spectroscopy

Chronic kidney disease (CKD) affects approximately 10% of the world population, higher still in some developing countries, and can cause irreversible kidney damage eventually leading to kidney failure requiring dialysis or kidney transplantation. However, not all patients with CKD will progress to this stage, and it is difficult to distinguish between progressors and non-progressors at the time of diagnosis. Current clinical practice involves monitoring estimated glomerular filtration rate and proteinuria to assess CKD trajectory over time; however, there remains a need for novel, validated methods that differentiate CKD progressors and non-progressors. Nuclear magnetic resonance techniques, including magnetic resonance spectroscopy and magnetic resonance imaging, have the potential to improve our understanding of CKD progression. Herein, we review the application of magnetic resonance spectroscopy both in preclinical and clinical settings to improve the diagnosis and surveillance of patients with CKD.

Emerging role for branched-chain amino acids metabolism in fibrosis

Fibrosis is a common pathological feature of organ diseases resulting from excessive production of extracellular matrix, which accounts for significant morbidity and mortality. However, there is currently no effective treatment targeting fibrogenesis. Recently, metabolic alterations are increasingly considered as essential factors underlying fibrogenesis, and especially research on metabolic regulation of amino acids is flourishing. Among them, branched-chain amino acids (BCAAs) are the most abundant essential amino acids, including leucine, isoleucine and valine, which play significant roles in the substance and energy metabolism and their regulation. Dysregulation of BCAAs metabolism has been proven to contribute to numerous diseases. In this review, we summarize the metabolic regulation of fibrosis and the changes in BCAAs metabolism secondary to fibrosis. We also review the effects and mechanisms of the BCAAs intervention, and its therapeutic targeting in hepatic, renal and cardiac fibrosis, with a focus on the fibrosis in liver and associated hepatocellular carcinoma.

Gut microbiota combined with metabolomics reveal the mechanism of curcumol on liver fibrosis in mice

OBJECTIVE

Liver fibrosis is a reversible pathological process, and its prevention and treatment hold great significance for patients with chronic liver disease. This study combined 16S rRNA analysis of gut microbiota and serum metabolomics to explore the mechanism of curcumol's effect on liver fibrosis in mice. The results clarified the relationship between the gut microbiota and metabolites in the process of liver fibrosis.

MATERIALS AND METHODS

In this study, we randomly divided mice into a control group, a model group, and a curcumol treatment group to analyze the pathological changes in the liver tissue as well as the activities of the toll-like receptor 4 (TLR4)/nuclear factory kappa B (NF-κB) signaling pathway and inflammatory factors, such as tumor necrosis factor (TNF), interleukin 6 (IL-6), and IL-8. The gut microbiota were analyzed by 16 S rRNA sequencing, and serum metabolites were examined by liquid chromatography-mass spectrometry (LC-MS) metabolomic analysis.

RESULTS

Molecular biological testing found that curcumol could significantly improve the pathological changes of the liver tissue and inhibit the occurrence of liver inflammation. Intestinal flora testing found that curcumol could significantly change the abundances of Veillonellaceae, Prerotella_oulorum, and Alistipes_finegoldii. Metabolomics analysis found that curcumol's antihepatic fibrosis effect may be related to its regulation of arachidonic acid metabolism. Correlation analysis suggested that curcumol regulated the abundances of Bacteroidota and Bacteroides and participated in the metabolism of Prostaglandin B2.

CONCLUSIONS

When liver fibrosis occurs, the intestinal flora and metabolic network are altered. The effect of curcumol on liver fibrosis may be related to its regulation of intestinal flora and the resulting interference with metabolic pathways, thereby reducing liver inflammation.

NMR-based metabolomics approach to evaluate the toxicological risks of Tibetan medicine 'Ershiwuwei Shanhu' pill in rats

ETHNOPHARMACOLOGICAL RELEVANCE

'Ershiwuwei Shanhu' Pill (ESP) is a classic Tibetan medicine to treat neurological disorders in nervous system, especially for neurological pains and epilepsy. It contains many Tibet-specific mineral medicines, among which Halloysite (Halloysitum rubrum, HR) was regarded as the main active one. As mineral medicines contain heavy metals with poor solubility, the doubts about its safety restricted its clinical application and further development.

AIM OF THE STUDY

A 7-day acute toxicity of ESP and its main active mineral medicine HR was systematically studied for investigating the safety of ESP and exploring the role of HR in ESP's potential toxicity.

MATERIALS AND METHODS

In this study, the acute oral toxicity assessment of formula-ESP and HR were performed on rats for 7 days at doses equivalent to 10 (1 g/kg) and 40 times (4 g/kg) the typical clinical dose (0.1 g/kg). ¹H NMR based metabolomics profiling, aided with biochemical analysis and histopathology, was conducted to explore the global metabolic changes in the livers and kidneys of the administrated rats.

RESULTS

High-dose HR caused oxidative stress, energy metabolism disorders, purine metabolism impairments and amino acid metabolism imbalance in rats, resulting in hepatotoxicity and nephrotoxicity, which in accordance with the increased biochemical index in blood (ALT, AST, BUN and CRE). ESP (low-dose) induced metabolites changes were far more less than HR in livers, showcasing the distinct advantage of formula in reducing toxicity. Furthermore, low-dose ESP disturbed renal metabolism in a way similar to high-dose HR, which implies that HR might be the major source of the potential nephrotoxicity of ESP.

CONCLUSION

HR exhibited potential hepatoxicity and nephrotoxicity, but the formula- 'Ershiwuwei Shanhu' Pill which contains HR is considered relatively safe.

Metabolomics reveals the renoprotective effect of n-butanol extract and amygdalin extract from Amygdalus mongolica in rats with renal fibrosis

Renal fibrosis (RF) is a pathological process of progression from chronic kidney disease to end-stage renal disease. Amygdalus mongolica is a traditional Chinese medicine, and our previous studies demonstrated that the n-butanol extract (BUT) and amygdalin extract (AMY) from its seeds can prevent RF. However, the underlying mechanism remains unclear. The present study investigated the exact mechanism of the protective effect of A. mongolica on RF. A renal fibrosis rat model was induced with unilateral ureteral obstruction. Biochemical indicators were measured and combined with histopathology of renal tissue to evaluate the anti-RF effects. A serum metabonomic method was used to clarify the changes in the metabolic profile. The tubulointerstitial damage and fibrosis were significantly improved and metabolic perturbations were restored after treatment with BUT and AMY. Thirty-eight metabolites associated with RF progression and related to the regulation of arginine and proline metabolism, nicotinate and nicotinamide metabolism, and histidine metabolism were identified. They were restored to levels similar to those in controls after treatment. Moreover, no significant differences in efficacy were observed between the BUT and AMY groups. This study reveals and compares the potential mechanisms of the renoprotective effects after treatment with BUT and AMY from a metabolomic perspective.

Comprehensive Metabolic Signature of Renal Dysplasia in Children. A Multiplatform Metabolomics Concept

Renal dysplasia is a severe congenital abnormality of the kidney parenchyma, which is an important cause of end-stage renal failure in childhood and early adulthood. The diagnosis of renal dysplasia relies on prenatal or postnatal ultrasounds as children show no specific clinical symptoms before chronic kidney disease develops. Prompt diagnosis is important in terms of early introduction of nephroprotection therapy and improved long-term prognosis. Metabolomics was applied to study children with renal dysplasia to provide insight into the changes in biochemical pathways underlying its pathology and in search of early indicators for facilitated diagnosis. The studied cohort consisted of 72 children, 39 with dysplastic kidneys and 33 healthy controls. All subjects underwent comprehensive urine metabolic profiling with the use of gas chromatography and liquid chromatography coupled to mass spectrometry, with two complementary separation modes of the latter. Univariate and multivariate statistical calculations identified a total of nineteen metabolites, differentiating the compared cohorts, independent of their estimated glomerular filtration rate. Seven acylcarnitines, xanthine, and glutamine were downregulated in the urine of renal dysplasia patients. Conversely, renal dysplasia was associated with higher urinary levels of dimethylguanosine, threonic acid or glyceric acid. This is the first metabolomic study of subjects with renal dysplasia. The authors define a characteristic urine metabolic signature in children with dysplastic kidneys, irrespective of renal function, linking the condition with altered fatty acid oxidation, amino acid and purine metabolisms.

Axl-inhibitor bemcentinib alleviates mitochondrial dysfunction in the unilateral ureter obstruction murine model

Renal fibrosis is a progressive histological manifestation leading to chronic kidney disease (CKD) and associated with mitochondrial dysfunction. In previous work, we showed that Bemcentinib, an Axl receptor tyrosine kinase inhibitor, reduced fibrosis development. In this study, to investigate its effects on mitochondrial dysfunction in renal fibrosis, we analysed genome‐wide transcriptomics data from a unilateral ureter obstruction (UUO) murine model in the presence or absence of bemcentinib (n = 6 per group) and SHAM‐operated (n = 4) mice. Kidney ligation resulted in dysregulation of mitochondria‐related pathways, with a significant reduction in the expression of oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), citric acid cycle (TCA), response to reactive oxygen species and amino acid metabolism‐related genes. Bemcentinib treatment increased the expression of these genes. In contrast, AKT/PI3K signalling pathway genes were up‐regulated upon UUO, but bemcentinib largely inhibited their expression. At the functional level, ligation reduced mitochondrial biomass, which was increased upon bemcentinib treatment. Serum metabolomics analysis also showed a normalizing amino acid profile in UUO, compared with SHAM‐operated mice following bemcentinib treatment. Our data suggest that mitochondria and mitochondria‐related pathways are dramatically affected by UUO surgery and treatment with Axl‐inhibitor bemcentinib partially reverses these effects.

The Nax (SCN7A) channel: an atypical regulator of tissue homeostasis and disease

Within an articulately characterized family of ion channels, the voltage-gated sodium channels, exists a black sheep, SCN7A (Nax). Nax, in contrast to members of its molecular family, has lost its voltage-gated character and instead rapidly evolved a new function as a concentration-dependent sensor of extracellular sodium ions and subsequent signal transducer. As it deviates fundamentally in function from the rest of its family, and since the bulk of the impressive body of literature elucidating the pathology and biochemistry of voltage-gated sodium channels has been performed in nervous tissue, reports of Nax expression and function have been sparse. Here, we investigate available reports surrounding expression and potential roles for Nax activity outside of nervous tissue. With these studies as justification, we propose that Nax likely acts as an early sensor that detects loss of tissue homeostasis through the pathological accumulation of extracellular sodium and/or through endothelin signaling. Sensation of homeostatic aberration via Nax then proceeds to induce pathological tissue phenotypes via promotion of pro-inflammatory and pro-fibrotic responses, induced through direct regulation of gene expression or through the generation of secondary signaling molecules, such as lactate, that can operate in an autocrine or paracrine fashion. We hope that our synthesis of much of the literature investigating this understudied protein will inspire more research into Nax not simply as a biochemical oddity, but also as a potential pathophysiological regulator and therapeutic target.

Urine metabolite profiling of Indian Antarctic Expedition members: NMR spectroscopy-based metabolomic investigation

The southernmost region of earth, Antarctica, has world's most challenging environments. Those who live for long time and work in Antarctic stations are subjected to environmental stresses such as cold weather, photoperiod variations leading to disrupted sleep cycles, constrained living spaces, dry air, non-availability of fresh food items, and high electromagnetic radiations, psychological factors, such as geographical and social isolation, etc. All these factors have a significant impact on the human body. The present study investigated the impact of Antarctica harsh environment on human physiology and its metabolic processes by evaluating urine metabolome, using 1H NMR spectroscopy and analyzing certain physiological and clinical parameters for correlation with physiological expression data and metabolite results. Two study groups - before Antarctic exposure (B) and after Antarctic exposure (E), consisting of 11 subjects, exposed to one-month summer expedition, were compared. 35 metabolites in urine samples were identified from the 700 MHz ¹H NMR spectra from where integral intensity of 22 important metabolites was determined. Univariate analysis indicated significant decrease in the levels of citrate and creatinine in samples collected post-expedition. Multivariate analysis was also performed using 1H NMR spectroscopy, because independent metabolite abundances may complement each other in predicting the dependent variables. 10 metabolites were identified among the groups; the OPLS-DA and VIP score indicated variation in appearance of metabolites over different time periods with insignificant change in the intensities. Metabolite results illustrate the impact of environmental stress or altered life style including the diet with absence of fresh fruits and vegetables, on the pathophysiology of the human health. Metabolic adaptation to Antarctic environmental stressors may help to highlight the effect of short-term physiological status and provide important information during Antarctic expeditions to formulate management programmes.

An Integrated Transcriptomic Approach to Identify Molecular Markers of Calcineurin Inhibitor Nephrotoxicity in Pediatric Kidney Transplant Recipients

Calcineurin inhibitors are highly efficacious immunosuppressive agents used in pediatric kidney transplantation. However, calcineurin inhibitor nephrotoxicity (CNIT) has been associated with the development of chronic renal allograft dysfunction and decreased graft survival. This study evaluated 37 formalin-fixed paraffin-embedded biopsies from pediatric kidney transplant recipients using gene expression profiling. Normal allograft samples (n = 12) served as negative controls and were compared to biopsies exhibiting CNIT (n = 11). The remaining samples served as positive controls to validate CNIT marker specificity and were characterized by other common causes of graft failure such as acute rejection (n = 7) and interstitial fibrosis/tubular atrophy (n = 7). MiRNA profiles served as the platform for data integration. Oxidative phosphorylation and mitochondrial dysfunction were the top molecular pathways associated with overexpressed genes in CNIT samples. Decreased ATP synthesis was identified as a significant biological function in CNIT, while key toxicology pathways included NRF2-mediated oxidative stress response and increased permeability transition of mitochondria. An integrative analysis demonstrated a panel of 13 significant miRNAs and their 33 CNIT-specific gene targets involved with mitochondrial activity and function. We also identified a candidate panel of miRNAs/genes, which may serve as future molecular markers for CNIT diagnosis as well as potential therapeutic targets.

Diminished Systemic Amino Acids Metabolome and Lipid Peroxidation in Ureteropelvic Junction Obstruction (UPJO) Infants Requiring Surgery

Congenital anomalies of the urinary tract, and particularly of obstructive nephropathy such as ureteropelvic junction obstruction (UPJO) in infants, can later lead to chronic kidney disease and hypertension. Fundamental questions regarding underlying mechanisms remain unanswered. The aim of the present study was to quantitate the systemic amino acids metabolome in 21 UPJO infants requiring surgery (Group A) and 21 UPJO infants under conservative treatment (Group B). Nineteen healthy age-matched infants served as controls (Group C). Serum amino acids involved in several pathways and representative metabolites, including the L-arginine-derived nitric oxide (NO) metabolites nitrite and nitrate and the lipid peroxidation biomarker malondialdehyde (MDA) were measured by gas chromatography–mass spectrometry (GC–MS) methods using their stable-isotope labeled analogs as internal standards after derivatization to their methyl esters N-pentafluoropropionic amides (amino acids) and to their pentafluorobenzyl derivatives (nitrite, nitrate, MDA). The concentrations of the majority of the biomarkers were found to be lower in Group A compared to Group B. Statistical analysis revealed clear differentiation between the examined study groups. Univariate statistical analysis highlighted serum homoarginine (q = 0.006), asymmetric dimethylarginine (q = 0.05) and malondialdehyde (q = 0.022) as potential biomarkers for UPJO infants requiring surgery. Group A also differed from Group B with respect to the diameter of the preoperative anterior–posterior renal pelvis (AP) as well as regarding the number and extent of inverse correlations between AP and the serum concentrations of the biomarkers. In Group A, but not in Group B, the AP diameter strongly correlated with hydroxy-proline (r = −0.746, p = 0.0002) and MDA (r = −0.754, p = 0.002). Our results indicate a diminished amino acids metabolome in the serum of UPJO infants requiring surgery comparing to a conservative group.

Serum Metabolomic Profiling to Reveal Potential Biomarkers for the Diagnosis of Fatty Liver Hemorrhagic Syndrome in Laying Hens

Fatty liver hemorrhage syndrome (FLHS), a nutritional and metabolic disease that frequently occurs in laying hens, causes serious losses to the poultry industry. Nowadays, the traditional clinical diagnosis of FLHS still has its limitations. Therefore, searching for some metabolic biomarkers and elucidating the metabolic pathway in vivo are useful for the diagnosis and prevention of FLHS. In the present study, a model of FLHS in laying hens induced by feeding a high-energy, low-protein diet was established. Gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) was used to analyze the metabolites in serum at days 40 and 80. The result showed that, in total, 40 differential metabolites closely related to the occurrence and development of FLHS were screened and identified, which were mainly associated with lipid metabolism, amino acid metabolism, and energy metabolism pathway disorders. Further investigation of differential metabolites showed 10 potential biomarkers such as 3-hydroxybutyric acid, oleic acid, palmitoleic acid, and glutamate were possessed of high diagnostic values by analyzing receiver operating characteristic (ROC) curves. In conclusion, this study showed that the metabolomic method based on GC-TOF-MS can be used in the clinical diagnosis of FLHS in laying hens and provide potential biomarkers for early risk evaluation of FLHS and further insights into FLHS development.

Uremic toxin indoxyl sulfate promotes proinflammatory macrophage activation by regulation of β-catenin and YAP pathways

Evidence has been shown that indoxyl sulfate (IS) could impair kidney and cardiac functions. Moreover, macrophage polarization played important roles in chronic kidney disease and cardiovascular disease. IS acts as a nephron-vascular toxin, whereas its effect on macrophage polarization during inflammation is still not fully elucidated. In this study, we aimed to investigate the effect of IS on macrophage polarization during lipopolysaccharide (LPS) challenge. THP-1 monocytes were incubated with phorbol 12-myristate-13-acetate (PMA) to differentiate into macrophages, and then incubated with LPS and IS for 24 h. ELISA was used to detect the levels of TNFα, IL-6, IL-1β in THP-1-derived macrophages. Western blot assay was used to detect the levels of arginase1 and iNOS in THP-1-derived macrophages. Percentages of HLA-DR-positive cells (M1 macrophages) and CD206-positive cells (M2 macrophages) were detected by flow cytometry. IS markedly increased the production of the pro-inflammatory factors TNFα, IL-6, IL-1β in LPS-stimulated THP-1-derived macrophages. In addition, IS induced M1 macrophage polarization in response to LPS, as evidenced by the increased expression of iNOS and the increased proportion of HLA-DR+ macrophages. Moreover, IS downregulated the level of β-catenin, and upregulated the level of YAP in LPS-stimulated macrophages. Activating β-catenin signaling or inhibiting YAP signaling suppressed the IS-induced inflammatory response in LPS-stimulated macrophages by inhibiting M1 polarization. IS induced M1 macrophage polarization in LPS-stimulated macrophages via inhibiting β-catenin and activating YAP signaling. In addition, this study provided evidences that activation of β-catenin or inhibition of YAP could alleviate IS-induced inflammatory response in LPS-stimulated macrophages. This finding may contribute to the understanding of immune dysfunction observed in chronic kidney disease and cardiovascular disease.

Protective effects of Amygdalus mongolica on rats with renal fibrosis based on serum metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Renal fibrosis (RF) is a common outcome of various progressive chronic kidney diseases (CKDs) and, thus, seriously endangers human health. As the active ingredient of Amygdalus mongolica, amygdalin inhibits RF. Furthermore, our previous studies demonstrated that n-butanol extract (BUT) and petroleum ether extract (PET), which are effective components of A. mongolica, have an anti-renal fibrosis effect. However, their potential mechanisms of action are unclear and need further verification.

AIMS OF THE STUDY

The aims of this study were to further investigate the effects and potential mechanisms of A. mongolica extracts in the treatment of RF.

MATERIALS AND METHODS

The animals were divided into the control group, RF model group, PET group and BUT group. The RF rat model was established through unilateral ureteral obstruction (UUO). Biochemical indicators, including blood urea nitrogen (BUN), serum creatinine (Scr), and hydroxyproline (HYP, a routine marker of fibrosis), and the antioxidant index (including superoxide dismutase (SOD) and malondialdehyde (MDA)) were measured to evaluate the anti-RF effects of the extracts of A. mongolica. The histomorphology of renal tissue was observed and scored by HE and Masson staining. A serum metabonomic analysis based on UPLC-Q-TOF/MS was performed to assess the changes in the metabolic profile among the different groups.

RESULTS

The results showed that PET and BUT significantly improved tubulointerstitial damage and fibrosis by reducing the levels of Scr, BUN, HYP, and MDA and increasing the level of SOD. Moreover, no significant differences in efficacy were observed between the BUT and PET groups. According to the metabolomics analysis, seventy-four potential biomarkers were identified, and eight crucial biomarkers were further selected. These key biomarkers significantly contributed to RF progression by participating in six metabolic pathways, including pathways involved in arginine and proline metabolism, histidine metabolism, nicotinamide metabolism, pentose and glucuronate interconversion, ascorbate and aldarate metabolism, and amino sugar and nucleotide sugar metabolism. In addition, eight key biomarkers and six crucial biomarkers were restored to levels similar to those observed in controls following the treatment with PET and BUT, respectively.

CONCLUSIONS

The outcomes of these studies demonstrate the renoprotective effects of A. mongolica extracts in rats with RF and revealed the mechanism underlying these antifibrotic effects on metabolic activity for the first time.

Serum-Targeted HILIC-MS Metabolomics-Based Analysis in Infants with Ureteropelvic Junction Obstruction

Ureteropelvic junction obstruction (UPJO) constitutes the predominant cause of obstructive nephropathy in both neonates and infants. Fundamental questions regarding UPJO's mechanism, assessment, and treatment still remain unanswered. The aim of the present study was to elucidate potential differences through serum metabolic profiling of surgical cases of infants with UPJO compared to both nonsurgical cases and healthy age-matched controls. Early diagnosis of renal dysfunction in this cohort based on highlighted biomarkers was the ultimate goal. Thus, serum samples were collected from 20 patients preoperatively, 19 patients with mild stenosis treated conservatively, and 17 healthy controls. All samples were subjected to targeted metabolomics analysis by hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC LC-MS/MS). Both univariate and multivariate statistical analyses were performed. Principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) score plots showed that the studied groups differed significantly, with a panel of metabolites, including creatinine, tryptophan, choline, and aspartate, distinguishing patients who required surgery from those followed by systematical monitoring as well as from healthy controls, showing high performance as indicators of UPJO disease.

Untargeted Urinary 1H NMR-Based Metabolomic Pattern as a Potential Platform in Breast Cancer Detection

Breast cancer (BC) remains the second leading cause of death among women worldwide. An emerging approach based on the identification of endogenous metabolites (EMs) and the establishment of the metabolomic fingerprint of biological fluids constitutes a new frontier in medical diagnostics and a promising strategy to differentiate cancer patients from healthy individuals. In this work we aimed to establish the urinary metabolomic patterns from 40 BC patients and 38 healthy controls (CTL) using proton nuclear magnetic resonance spectroscopy (1H-NMR) as a powerful approach to identify a set of BC-specific metabolites which might be employed in the diagnosis of BC. Orthogonal partial least squares-discriminant analysis (OPLS-DA) was applied to a 1H-NMR processed data matrix. Metabolomic patterns distinguished BC from CTL urine samples, suggesting a unique metabolite profile for each investigated group. A total of 10 metabolites exhibited the highest contribution towards discriminating BC patients from healthy controls (variable importance in projection (VIP) >1, p < 0.05). The discrimination efficiency and accuracy of the urinary EMs were ascertained by receiver operating characteristic curve (ROC) analysis that allowed the identification of some metabolites with the highest sensitivities and specificities to discriminate BC patients from healthy controls (e.g. creatine, glycine, trimethylamine N-oxide, and serine). The metabolomic pathway analysis indicated several metabolism pathway disruptions, including amino acid and carbohydrate metabolisms, in BC patients, namely, glycine and butanoate metabolisms. The obtained results support the high throughput potential of NMR-based urinary metabolomics patterns in discriminating BC patients from CTL. Further investigations could unravel novel mechanistic insights into disease pathophysiology, monitor disease recurrence, and predict patient response towards therapy.

Early detection of unilateral ureteral obstruction by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) is an emerging analytical tool for rapid in situ assessment of metabolomic profiles on tissue sections without tissue pretreatment or labeling. We applied DESI-MS to identify candidate metabolic biomarkers associated with kidney injury at the early stage. DESI-MS was performed on sections of kidneys from 80 mice over a time course following unilateral ureteral obstruction (UUO) and compared to sham controls. A predictive model of renal damage was constructed using the LASSO (least absolute shrinkage and selection operator) method. Levels of lipid and small metabolites were significantly altered and glycerophospholipids comprised a significant fraction of altered species. These changes correlate with altered expression of lipid metabolic genes, with most genes showing decreased expression. However, rapid upregulation of PG(22:6/22:6) level appeared to be a hitherto unknown feature of the metabolic shift observed in UUO. Using LASSO and SAM (significance analysis of microarrays), we identified a set of well-measured metabolites that accurately predicted UUO-induced renal damage that was detectable by 12 h after UUO, prior to apparent histological changes. Thus, DESI-MS could serve as a useful adjunct to histology in identifying renal damage and demonstrates early and broad changes in membrane associated lipids.

Metabolomic and biochemical characterization of a new model of the transition of acute kidney injury to chronic kidney disease induced by folic acid

Background

Renal diseases represent a major public health problem. The demonstration that maladaptive repair of acute kidney injury (AKI) can lead to the development of chronic kidney disease (CKD) and end-stage renal disease has generated interest in studying the pathophysiological pathways involved. Animal models of AKI–CKD transition represent important tools to study this pathology. We hypothesized that the administration of multiple doses of folic acid (FA) would lead to a progressive loss of renal function that could be characterized through biochemical parameters, histological classification and nuclear magnetic resonance (NMR) profiling.

Methods

Wistar rats were divided into groups: the control group received a daily intraperitoneal (I.P.) injection of double-distilled water, the experimental group received a daily I.P. injection of FA (250 mg kg body weight⁻¹). Disease was classified according to blood urea nitrogen level: mild (40–80 mg dL⁻¹), moderate (100–200 mg dL⁻¹) and severe (>200 mg dL⁻¹). We analyzed through biochemical parameters, histological classification and NMR profiling.

Results

Biochemical markers, pro-inflammatory cytokines and kidney injury biomarkers differed significantly (P < 0.05) between control and experimental groups. Histology revealed that as damage progressed, the degree of tubular injury increased, and the inflammatory infiltrate was more evident. NMR metabolomics and chemometrics revealed differences in urinary metabolites associated with CKD progression. The main physiological pathways affected were those involved in energy production and amino-acid metabolism, together with organic osmolytes. These data suggest that multiple administrations of FA induce a reproducible model of the induction of CKD. This model could help to evaluate new strategies for nephroprotection that could be applied in the clinic.

Increased expression and phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isoforms in urinary exosomes in pre-eclampsia

Background

Glycolysis is altered in various kidney diseases, but little is known about glycolysis in pre-eclampsia, a multi-system disorder with major pathological effects on the kidney. Urinary exosomes provide a non-invasive alternative for studying changes in kidney metabolism. This study aims to characterise the expression and phosphorylation of isozymes of the key glycolytic regulatory protein, 6-phosphofructokinase-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2), in urinary exosomes of subjects with pre-eclampsia (PE), compared to normotensive non-pregnant (NC) and normotensive pregnant (NP) controls.

Methods

A cross-sectional study of NC (n = 19), NP (n = 23) and PE (n = 29) subjects was performed. Exosomes were isolated from urine samples by differential ultracentrifugation, and then analyzed by Western blot and densitometry for expression of PFK-2/FBPase-2 isozymes (PFKFB2, PFKFB3 and PFKFB4) and phosphorylation of PFKFB2 at residues Ser483 and Ser466 and PFKFB3 at Ser461.

Results

PFKFB2 expression was increased 4.7-fold in PE compared to NP (p < 0.001). PFKFB2 phosphorylation at Ser483 was increased 2.6-fold in PE compared to NP (p = 0.002). Expression of phosphorylated PFKFB2/PFKFB3 at Ser466/Ser461 was increased in PE, being present in 77.4% (95% CI 59.9–88.9%) of PE and 8.3% (95% CI 1.2–27.0%) of NP samples (p < 0.001). PFKFB3 was more commonly expressed in PE, detected in 90.3% (95% CI 74.3–97.4%) of PE and 8.3% (95% CI 1.2–27.0%) of NP samples (p < 0.001). PFKFB4 had a 7.2-fold increase in expression in PE compared to NP (p < 0.001). No significant differences between NP and NC groups were observed.

Conclusion

Regulatory proteins that increase glycolysis are increased in the urinary exosomes of subjects with pre-eclampsia, suggesting that renal glycolysis may be increased in this condition.

Gene Expression Studies and Targeted Metabolomics Reveal Disturbed Serine, Methionine, and Tyrosine Metabolism in Early Hypertensive Nephrosclerosis

Introduction

Hypertensive nephrosclerosis is among the leading causes of end-stage renal disease, but its pathophysiology is poorly understood. We wanted to explore early metabolic changes using gene expression and targeted metabolomics analysis.

Methods

We analyzed gene expression in kidneys biopsied from 20 patients with nephrosclerosis and 31 healthy controls with an Affymetrix array. Thirty-one amino acids were measured by liquid chromatography coupled with mass spectrometry (LC-MS) in urine samples from 62 patients with clinical hypertensive nephrosclerosis and 33 age- and sex-matched healthy controls, and major findings were confirmed in an independent cohort of 45 cases and 15 controls.

Results

Amino acid catabolism and synthesis were strongly underexpressed in hypertensive nephrosclerosis (13- and 7-fold, respectively), and these patients also showed gene expression patterns indicating decreased fatty acid oxidation (12-fold) and increased interferon gamma (10-fold) and cellular defense response (8-fold). Metabolomics analysis revealed significant distribution differences in 11 amino acids in hypertensive nephrosclerosis, among them tyrosine, phenylalanine, dopamine, homocysteine, and serine, with 30% to 70% lower urine excretion. These findings were replicated in the independent cohort. Integrated gene-metabolite pathway analysis showed perturbations of renal dopamine biosynthesis. There were also significant differences in homocysteine/methionine homeostasis and the serine pathway, which have strong influence on 1-carbon metabolism. Several of these disturbances could be interconnected through reduced regeneration of tetrahydrofolate and tetrahydrobiopterin.

Conclusion

Early hypertensive nephrosclerosis showed perturbations of intrarenal biosynthesis of dopamine, which regulates natriuresis and blood pressure. There were also disturbances in serine/glycine and methionine/homocysteine metabolism, which may contribute to endothelial dysfunction, atherosclerosis, and renal fibrosis.

Characteristic Metabolic Alterations Identified in Primary Neurons Under High Glucose Exposure

Cognitive dysfunction is a central nervous system (CNS) complication of diabetes mellitus (DM) that is characterized by impaired memory and cognitive ability. An in-depth understanding of metabolic alterations in the brain associated with DM will facilitate our understanding of the pathogenesis of cognitive dysfunction. The present study used an in vitro culture of primary neurons in a high-glucose (HG) environment to investigate characteristic alterations in neuron metabolism using nuclear magnetic resonance (NMR)-based metabonomics. High performance liquid chromatography (HPLC) was also used to measure changes in the adenosine phosphate levels in the hippocampal regions of streptozotocin (STZ)-induced diabetic rats. Our results revealed significant elevations in phosphocholine and ATP production in neurons and decreased formate, nicotinamide adenine dinucleotide (NAD⁺), tyrosine, methionine, acetate and phenylalanine levels after HG treatment. However, the significant changes in lactate, glutamate, taurine and myo-inositol levels in astrocytes we defined previously in astrocytes, were not found in neurons, suggested cell-specific metabolic alterations. We also confirmed an astrocyte-neuron lactate shuttle between different compartments in the brain under HG conditions, which was accompanied by abnormal acetate transport. These alterations reveal specific information on the metabolite levels and transport processes related to neurons under diabetic conditions. Our findings contribute to the understanding of the metabolic alterations and underlying pathogenesis of cognitive decline in diabetic patients.

NMR-based urine metabolic profiling and immunohistochemistry analysis of nephron changes in a mouse model of hypoxia-induced acute kidney injury

Acute kidney injury can be caused by multiple factors, including sepsis, respiratory failure, heart failure, trauma, or nephrotoxic medications, among others. Here, a mouse model was used to investigate potential urinary metabolic biomarkers of hypoxia-induced AKI. Urine metabolic profiles of 48 Swiss Webster mice were assessed using nuclear magnetic resonance spectroscopy (NMR) for 7 days following 72 h exposure to a hypoxic 6.5% oxygen environment. Histological analyses indicated a lack of gross nephron structural changes in the aftermath of hypoxia. Immunohistochemical (IHC) analyses, however, indicated elevated expression of protein injury biomarkers in distal and proximal tubules but not glomeruli. Kidney injury molecule-1 levels peaked in distal tubules at 72 h and were still increasing in proximal tubules at 7 days posthypoxia, whereas cystatin C levels were elevated at 24 h but decreased thereafter, and were elevated and still increasing in proximal tubules at 7 days posthypoxia. Neutrophil gelatinase-associated lipocalin levels were modestly elevated from 24 h to 7 days posthypoxia. NMR-based metabolic profiling revealed that urine metabolites involved in energy metabolism and associated biosynthetic pathways were initially decreased at 24 h posthypoxia, consistent with metabolic suppression as a mechanism for cell survival, but were significantly elevated at 48 and 72 h posthypoxia, indicating a burst in organism metabolism associated with reactivation of cellular energetics during recovery after cessation of hypoxia and return to a normoxic environment. The IHC results indicated that kidney injury persists long after plasma and urine biomarkers of hypoxia return to normal values.

8u, a pro-apoptosis/cell cycle arrest compound, suppresses invasion and metastasis through HSP90α downregulating and PI3K/Akt inactivation in hepatocellular carcinoma cells

8u, an acridine derivative, has been proved effective anti-hepatocarcinoma effect, while the underlying mechanism remains unclear. Here, metabolomics and proteomics approaches were applied to study its anti-cancer mechanism and explore its effect on HepG2 cells' invasion and metastasis abilities. The results showed that 8u significantly suppressed HepG2 cells migration and enhanced cell-to-cell junctions. The inhibition effect of 8u on invasion and metastasis disappeared after HSP90α gene silencing, and was reversed after HSP90α overexpression. The biological experimental results indicated that 8u also blocked PI3K/Akt pathway, thereby reducing fatty acid synthase (FASN) protein expression and disordering intracellular lipid metabolism to inhibit cell invasion and metastasis. In addition, HSP90α protein and PI3K/Akt pathway could co-adjust to each other. These findings demonstrated that 8u could efficiently suppress the invasion and metastasis of HepG2 cells by decreasing the expression of HSP90α protein and inhibiting the PI3K/Akt signaling pathway, which could be used as a potential candidate for the treatment of HCC.

Metabolomics identifies metabolite biomarkers associated with acute rejection after heart transplantation in rats

The aim of this study was to identify metabolite biomarkers associated with acute rejection after heart transplantation in rats using a LC-MS-based metabolomics approach. A model of heterotopic cardiac xenotransplantation was established in rats, with Wistar rats as donors and SD rats as recipients. Blood and cardiac samples were collected from blank control rats (Group A), rats 5 (Group B) and 7 days (Group C) after heart transplantation, and pretreated rats 5 (Group D) and 7 days (Group E) post-transplantation for pathological and metabolomics analyses. We assessed International Society for Heart and Lung Transplantation (ISHLT) grades 0, 3B, 4, 1 and 1 rejection in groups A to E. There were 15 differential metabolites between groups A and B, 14 differential metabolites between groups A and C, and 10 differential metabolites between groups B and C. In addition, four common differential metabolites, including D-tagatose, choline, C16 sphinganine and D-glutamine, were identified between on days 5 and 7 post-transplantation. Our findings demonstrate that the panel of D-tagatose, choline, C16 sphinganine and D-glutamine exhibits a high sensitivity and specificity for the early diagnosis of acute rejection after heart transplantation, and LC-MS-based metabolomics approach has a potential value for screening post-transplantation biomarkers.

NMR spectroscopy and electron microscopy identification of metabolic and ultrastructural changes to the kidney following ischemia-reperfusion injury

Cellular, molecular, and ultrastructural nephron changes associated with ischemia-reperfusion injury-induced acute kidney injury (IRI-AKI) are not completely understood. Here, a multidisciplinary study was used to identify nephron changes in a mouse model of IRI-AKI. Histological analyses indicated distended Bowman's glomerular spaces and proximal and distal tubules. Increased filtrate volume in nephrons was caused by reduced water reabsorption by severely damaged proximal tubule brush borders and blocked flow of filtrate into collecting tubules by mucoprotein casts in distal tubules. Immunohistochemistry revealed protein AKI biomarkers in proximal tubules and glomeruli but not in distal tubules. Nuclear magnetic resonance spectroscopy revealed several metabolites that increased such as valine, alanine, and lactate. Other metabolites such as trigonelline, succinate, 2-oxoisocaproate, and 1- methyl-nicotinamide decreased or were absent in urine following IRI due to altered kidney function or metabolism. Urinary glucose increased due to reduced reabsorption by damaged proximal tubule brush borders. Scanning electron microscopy revealed flattening of podocytes and pedicals surrounding glomerular capillaries, and transmission electron microscopy (TEM) revealed effacement of podocyte pedicals, both consistent with increased hydrostatic pressure in nephrons following IRI-AKI. TEM revealed shortened proximal tubule microvilli in IRI kidneys with diminished lamina propia. TEM showed dramatic loss of mitochondria in distal tubule epithelia of IRI kidneys and emergence of multivesicular bodies of endosomes indicating ongoing cellular death. Collectively, the data define ultrastructural changes to nephrons and altered kidney metabolism associated with IRI-AKI.

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

Reversibility of hepatic fibrosis is an intrinsic response to chronic injury, and with on-going damage, fibrosis can progress to its end-stage consequence, cirrhosis. Non-invasive and reliable biomarkers for early detection of liver fibrosis are needed. Based on the CCl4-induced liver fibrosis rat model, urinary and serum metabolic profiling performed by LC-QTOF-MS associated with histological progression were utilized to identify liver fibrosis-specific potential biomarkers for early prediction and to reveal significant fibrotic pathways and their dynamic changes in different stages of liver fibrosis. Finally, nine differential metabolites in urine and ten in serum were selected and identified involving the most relevant metabolic pathways. Perturbations of tryptophan, valine, leucine, isoleucine, and citrate (TCA) cycle metabolites, along with sphingolipid and glycerophospholipid metabolites, occurred from the onset of liver fibrosis. Furthermore, dysregulation of valine and bile acid biosynthesis metabolites occurred in the intermediate and advanced stages. More importantly, among these metabolites, urinary kynurenic acid, 5-hydroxyindoleacetyl glycine, 4-(2-amino-3-hydroxyphenyl)-2,4-dioxobutanoic acid and serum sphinganine, sphingomyelin, L-leucine, L-tryptophan, and LysoPC(17:0) changed at all time points and may serve as potential early biomarkers for the diagnosis of hepatic fibrosis and as therapeutic targets. Overall, this work evaluates the potential of these metabolites for the early detection of liver fibrosis.

Traumatic Brain Injury Alters the Metabolism and Facilitates Alzheimer's Disease in a Murine Model

A majority of Alzheimer's disease (AD) cases are sporadic without known cause. People who suffered from traumatic brain injury (TBI) are more likely to develop neurodegeneration and cognitive impairments. However, the role of TBI in pathophysiology of AD remains elusive. The present study intended to explore the effect of TBI on metabolism and its role in AD pathogenesis. We subjected double transgenic AD model mice APP23/PS45 to TBI. We found that TBI promoted β-secretase cleavage of amyloid β precursor protein and amyloid β protein deposition, and exuberated the cognitive impairments in AD mouse models. ¹H nuclear magnetic resonance (¹H-NMR)-based metabolomics with multivariate analysis was performed to investigate the characteristic metabolites and the related metabolic pathways in the serum and urine samples of the mice. TBI affected the metabolic patterns, methylamine metabolism, and amino acid metabolism in serum samples. Urinary metabolites showed that glycolysis and the tricarboxylic acid (TCA) cycle were perturbed. The results indicate that TBI might facilitate Alzheimer's pathogenesis by altering metabolism and inducing mitochondrial dysfunction. The study suggests that metabolite changes could also serve as biomarkers for TBI-induced neurodegeneration.

Kidney Tissue Targeted Metabolic Profiling of Unilateral Ureteral Obstruction Rats by NMR

Renal interstitial fibrosis is a common pathological process in the progression of kidney disease. A nuclear magnetic resonance (NMR) based metabolomic approach was used to analyze the kidney tissues of rats with renal interstitial fibrosis (RIF), induced by unilateral ureteral obstruction (UUO). The combination of a variety of statistical methods were used to screen out 14 significantly changed potential metabolites, which are related with multiple biochemical processes including amino acid metabolism, adenine metabolism, energy metabolism, osmolyte change and induced oxidative stress. The exploration of the contralateral kidneys enhanced the understanding of the disease, which was also supported by serum biochemistry and kidney histopathology results. In addition, the pathological parameters (clinical chemistry, histological and immunohistochemistry results) were correlated with the significantly changed differential metabolites related with RIF. This study showed that targeted tissue metabolomic analysis can be used as a useful tool to understand the mechanism of the disease and provide a novel insight in the pathogenesis of RIF.