Biochemistry of uridine in plasma

Thermodynamic Studies of Complexes in Cu(II)/Uridine-5'-Diphosphoglucuronic Acid System

A binary system of uridine-5'-diphosphoglucuronic acid with copper (II) ions was studied. Potentiometric studies in aqueous solutions using computer data analysis were carried out. The pH of dominance, the overall stability constants (logβ), and the equilibrium constants of the formation reaction (logKe) were determined for each complex compound formed in the studied system. Spectroscopic studies were carried out to determine the mode of coordination in the compounds studied. Cytotoxicity and metabolic activity tests of the compounds obtained showed an increase in the biological activity of the complexes tested against the free ligand. The current research may contribute to the knowledge of complex compounds of biomolecules found in the human body and may also contribute to the characterization of a group of complex compounds with potential anticancer properties.

The longitudinal microbial and metabolic landscape of infant cystic fibrosis: the gut-lung axis

BACKGROUND AND AIM

In cystic fibrosis, gastrointestinal dysfunction and lower airway infection occur early and are independently associated with poorer outcomes in childhood. This study aimed to define the relationship between the microbiota at each niche during the first 2 years of life, its association with growth and airway inflammation, and explanatory features in the metabolome.

MATERIALS AND METHODS

67 bronchoalveolar lavage fluid (BALF), 62 plasma and 105 stool samples were collected from 39 infants with cystic fibrosis between 0 and 24 months who were treated with prophylactic antibiotics. 16S rRNA amplicon and shotgun metagenomic sequencing were performed on BALF and stool samples, respectively; metabolomic analyses were performed on all sample types. Sequencing data from healthy age-matched infants were used as controls.

RESULTS

Bacterial diversity increased over the first 2 years in both BALF and stool, and microbial maturation was delayed in comparison to healthy controls from the RESONANCE cohort. Correlations between their respective abundance in both sites suggest stool may serve as a noninvasive alternative for detecting BALF Pseudomonas and Veillonella. Multisite metabolomic analyses revealed age- and growth-related changes, associations with neutrophilic airway inflammation, and a set of core systemic metabolites. BALF Pseudomonas abundance was correlated with altered stool microbiome composition and systemic metabolite alterations, highlighting a complex gut-plasma-lung interplay and new targets with therapeutic potential.

CONCLUSION

Exploration of the gut-lung microbiome and metabolome reveals diverse multisite interactions in cystic fibrosis that emerge in early life. Gut-lung metabolomic links with airway inflammation and Pseudomonas abundance warrant further investigation for clinical utility, particularly in non-expectorating patients.

Uridine and its role in metabolic diseases, tumors, and neurodegenerative diseases

Uridine is a pyrimidine nucleoside found in plasma and cerebrospinal fluid with a concentration higher than the other nucleosides. As a simple metabolite, uridine plays a pivotal role in various biological processes. In addition to nucleic acid synthesis, uridine is critical to glycogen synthesis through the formation of uridine diphosphate glucose in which promotes the production of UDP-GlcNAc in the hexosamine biosynthetic pathway and supplies UDP-GlcNAc for O-GlcNAcylation. This process can regulate protein modification and affect its function. Moreover, Uridine has an effect on body temperature and circadian rhythms, which can regulate the metabolic rate and the expression of metabolic genes. Abnormal levels of blood uridine have been found in people with diabetes and obesity, suggesting a link of uridine dysregulation and metabolic disorders. At present, the role of uridine in glucose metabolism and lipid metabolism is controversial, and the mechanism is not clear, but it shows the trend of long-term damage and short-term benefit. Therefore, maintaining uridine homeostasis is essential for maintaining basic functions and normal metabolism. This article summarizes the latest findings about the metabolic effects of uridine and the potential of uridine metabolism as therapeutic target in treatment of metabolic disorders.

Silencing of aryl hydrocarbon receptor repressor restrains Th17 cell immunity in autoimmune hepatitis

Th17-cells play a key role in the pathogenesis of autoimmune hepatitis (AIH). Dysregulation of Th17-cells in AIH is linked to defective response to aryl-hydrocarbon-receptor (AhR) activation. AhR modulates adaptive immunity and is regulated by aryl-hydrocarbon-receptor-repressor (AHRR), which inhibits AhR transcriptional activity. In this study, we investigated whether defective Th17-cell response to AhR derives from aberrant AHRR regulation in AIH. Th17-cells, obtained from the peripheral blood of AIH patients (n = 30) and healthy controls (n = 30) were exposed to AhR endogenous ligands, and their response assessed in the absence or presence of AHRR silencing. Therapeutic effects of AHRR blockade were tested in a model of Concanavalin-A (Con-A)-induced liver injury in humanized mice. AHRR was markedly upregulated in AIH Th17-cells, following exposure to l-kynurenine, an AhR endogenous ligand. In patients, silencing of AHRR boosted Th17-cell response to l-kynurenine, as reflected by increased levels of CYP1A1, the main gene controlled by AhR; and decreased IL17A expression. Blockade of AHRR limited the differentiation of naïve CD4-cells into Th17 lymphocytes; and modulated Th17-cell metabolic profile by increasing the levels of uridine via ATP depletion or pyrimidine salvage. Treatment with 2'-deoxy-2'-fluoro-d-arabinonucleic acid (FANA) oligonucleotides to silence human AHRR in vivo, reduced ALT levels, attenuated lymphocyte infiltration on histology, and heightened frequencies of regulatory immune subsets in NOD/scid/gamma mice, reconstituted with human CD4 cells, and exposed to Con-A. In conclusion, blockade of AHRR in AIH restores Th17-cell response to AHR, and limits Th17-cell differentiation through generation of uridine. In vivo, silencing of AHRR attenuates liver damage in NOD/scid/gamma mice. Blockade of AHRR might therefore represent a novel therapeutic strategy to modulate effector Th17-cell immunity and restore homeostasis in AIH.

Causal relationship between human blood metabolites and risk of ischemic stroke: a Mendelian randomization study

Background: Ischemic stroke (IS) is a major cause of death and disability worldwide. Previous studies have reported associations between metabolic disorders and IS. However, evidence regarding the causal relationship between blood metabolites and IS lacking. Methods: A two-sample Mendelian randomization analysis (MR) was used to assess the causal relationship between 1,400 serum metabolites and IS. The inverse variance-weighted (IVW) method was employed to estimate the causal effect between exposure and outcome. Additionally, MR-Egger regression, weighted median, simple mode, and weighted mode approaches were employed as supplementary comprehensive evaluations of the causal effects between blood metabolites and IS. Tests for pleiotropy and heterogeneity were conducted. Results: After rigorous selection, 23 known and 5 unknown metabolites were identified to be associated with IS. Among the 23 known metabolites, 13 showed significant causal effects with IS based on 2 MR methods, including 5-acetylamino-6-formylamino-3-methyluracil, 1-ribosyl-imidazoleacetate, Behenoylcarnitine (C22), N-acetyltyrosine, and N-acetylputrescine to (N (1) + N (8))-acetate,these five metabolites were positively associated with increased IS risk. Xanthurenate, Glycosyl-N-tricosanoyl-sphingadienine, Orotate, Bilirubin (E,E), Bilirubin degradation product, C17H18N2O, Bilirubin (Z,Z) to androsterone glucuronide, Bilirubin (Z,Z) to etiocholanolone glucuronide, Biliverdin, and Uridine to pseudouridine ratio were associated with decreased IS risk. Conclusion: Among 1,400 blood metabolites, this study identified 23 known metabolites that are significantly associated with IS risk, with 13 being more prominent. The integration of genomics and metabolomics provides important insights for the screening and prevention of IS.

Protective Effect of Uridine on Structural and Functional Rearrangements in Heart Mitochondria after a High-Dose Isoprenaline Exposure Modelling Stress-Induced Cardiomyopathy in Rats

The pyrimidine nucleoside uridine and its phosphorylated derivates have been shown to be involved in the systemic regulation of energy and redox balance and promote the regeneration of many tissues, including the myocardium, although the underlying mechanisms are not fully understood. Moreover, rearrangements in mitochondrial structure and function within cardiomyocytes are the predominant signs of myocardial injury. Accordingly, this study aimed to investigate whether uridine could alleviate acute myocardial injury induced by isoprenaline (ISO) exposure, a rat model of stress-induced cardiomyopathy, and to elucidate the mechanisms of its action related to mitochondrial dysfunction. For this purpose, a biochemical analysis of the relevant serum biomarkers and ECG monitoring were performed in combination with transmission electron microscopy and a comprehensive study of cardiac mitochondrial functions. The administration of ISO (150 mg/kg, twice with an interval of 24 h, s.c.) to rats caused myocardial degenerative changes, a sharp increase in the serum cardiospecific markers troponin I and the AST/ALT ratio, and a decline in the ATP level in the left ventricular myocardium. In parallel, alterations in the organization of sarcomeres with focal disorganization of myofibrils, and ultrastructural and morphological defects in mitochondria, including disturbances in the orientation and packing density of crista membranes, were detected. These malfunctions were improved by pretreatment with uridine (30 mg/kg, twice with an interval of 24 h, i.p.). Uridine also led to the normalization of the QT interval. Moreover, uridine effectively inhibited ISO-induced ROS overproduction and lipid peroxidation in rat heart mitochondria. The administration of uridine partially recovered the protein level of the respiratory chain complex V, along with the rates of ATP synthesis and mitochondrial potassium transport, suggesting the activation of the potassium cycle through the mitoKATP channel. Taken together, these results indicate that uridine ameliorates acute ISO-induced myocardial injury and mitochondrial malfunction, which may be due to the activation of mitochondrial potassium recycling and a mild uncoupling leading to decreased ROS generation and oxidative damage.

Protective effect of uridine on atrial fibrillation: a Mendelian randomisation study

Uridine, a pyrimidine nucleoside, is crucial in the synthesis of metabolites. According to observational studies, a higher plasma uridine level is associated with a lower risk of atrial fibrillation (AF). However, the casual relationship between uridine and AF is still unknown. In this study, we used the Mendelian randomisation (MR) approach to explore causality. Three genetic variants associated with uridine were identified from the Metabolomics GWAS server (7824 participants); summary-level datasets associated with AF were acquired from a genome-wide association study (GWAS) meta-analysis with 1,030,836 European participants (60,620 AF cases). We duplicated the MR analyses using datasets from AF HRC studies and the FinnGen Consortium, and then conducted a meta-analysis which combined the main results. The risk of AF was significantly associated with the genetically determined plasma uridine level (odds ratio [OR] 0.27; 95% confidence interval [CI] 0.16, 0.47; p = 2.39 × 10-6). The association remained consistent in the meta-analysis of the various datasets (OR 0.27; 95% CI 0.17, 0.42; p = 1.34 × 10-8). In conclusion, the plasma uridine level is inversely associated with the risk of AF. Raising the plasma uridine level may have prophylactic potential against AF.

Multiplexed LC-MS/MS quantification of salivary RNA modifications in periodontitis

OBJECTIVE

To analyse the salivary epitranscriptomic profiles as periodontitis biomarkers using multiplexed mass spectrometry (MS).

BACKGROUND

The field of epitranscriptomics, which relates to RNA chemical modifications, opens new perspectives in the discovery of diagnostic biomarkers, especially in periodontitis. Recently, the modified ribonucleoside N6-methyladenosine (m6A) was revealed as a crucial player in the etiopathogenesis of periodontitis. However, no epitranscriptomic biomarker has been identified in saliva to date.

MATERIALS AND METHODS

Twenty-four saliva samples were collected from periodontitis patients (n = 16) and from control subjects (n = 8). Periodontitis patients were stratified according to stage and grade. Salivary nucleosides were directly extracted and, in parallel, salivary RNA was digested into its constituent nucleosides. Nucleoside samples were then quantified by multiplexed MS.

RESULTS

Twenty-seven free nucleosides were detected and an overlapping set of 12 nucleotides were detected in digested RNA. Among the free nucleosides, cytidine and three other modified nucleosides (inosine, queuosine and m6Am) were significantly altered in periodontitis patients. In digested RNA, only uridine was significantly higher in periodontitis patients. Importantly there was no correlation between free salivary nucleoside levels and the levels of those same nucleotides in digested salivary RNA, except for cytidine, m5C and uridine. This statement implies that the two detection methods are complementary.

CONCLUSION

The high specificity and sensitivity of MS allowed the detection and quantification of multiple nucleosides from RNA and free nucleosides in saliva. Some ribonucleosides appear to be promising biomarkers of periodontitis. Our analytic pipeline opens new perspectives for diagnostic periodontitis biomarkers.

Uridine alleviates high-carbohydrate diet-induced metabolic syndromes by activating sirt1/AMPK signaling pathway and promoting glycogen synthesis in Nile tilapia (Oreochromis niloticus)

Carbohydrates have a protein sparing effect, but long-term feeding of a high-carbohydrate diet (HCD) leads to metabolic disorders due to the limited utilization efficiency of carbohydrates in fish. How to mitigate the negative effects induced by HCD is crucial for the rapid development of aquaculture. Uridine is a pyrimidine nucleoside that plays a vital role in regulating lipid and glucose metabolism, but whether uridine can alleviate metabolic syndromes induced by HCD remains unknown. In this study, a total of 480 Nile tilapia (Oreochromis niloticus) (average initial weight 5.02 ± 0.03 g) were fed with 4 diets, including a control diet (CON), HCD, HCD + 500 mg/kg uridine (HCUL) and HCD + 5,000 mg/kg uridine (HCUH), for 8 weeks. The results showed that addition of uridine decreased hepatic lipid, serum glucose, triglyceride and cholesterol (P < 0.05). Further analysis indicated that higher concentration of uridine activated the sirtuin1 (sirt1)/adenosine 5-monophosphate-activated protein kinase (AMPK) signaling pathway to increase lipid catabolism and glycolysis while decreasing lipogenesis (P < 0.05). Besides, uridine increased the activity of glycogen synthesis-related enzymes (P < 0.05). This study suggested that uridine could alleviate HCD-induced metabolic syndrome by activating the sirt1/AMPK signaling pathway and promoting glycogen synthesis. This finding reveals the function of uridine in fish metabolism and facilitates the development of new additives in aquatic feeds.

Effects of Anemoside B4 on Plasma Metabolites in Cows with Clinical Mastitis

Anemoside B4 has a good curative effect on cows with CM; however, its impact on their metabolic profiles is unclear. Based on similar somatic cell counts and clinical symptoms, nine healthy dairy cows and nine cows with CM were selected, respectively. Blood samples were collected from cows with mastitis on the day of diagnosis. Cows with mastitis were injected with anemoside B4 (0.05 mL/kg, once daily) for three consecutive days, and healthy cows were injected with the same volume of normal saline. Subsequently, blood samples were collected. The plasma metabolic profiles were analyzed using untargeted mass spectrometry, and the concentrations of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) in serum were evaluated via ELISA. The cows with CM showed increased concentrations of IL-1β, IL-6, and TNF-α (p < 0.05). After treatment with anemoside B4, the concentrations of IL-1β, IL-6, and TNF-α were significantly decreased (p < 0.01). Untargeted metabolomics analysis showed that choline, glycocholic acid, PC (18:0/18:1), 20-HETE, PGF3α, and oleic acid were upregulated in cows with CM. After treatment with anemoside B4, the concentrations of PC (16:0/16:0), PC (18:0/18:1), linoleic acid, eicosapentaenoic acid, phosphorylcholine, and glycerophosphocholine were downregulated, while the LysoPC (14:0), LysoPC (18:0), LysoPC (18:1), and cis-9-palmitoleic acid were upregulated. This study indicated that anemoside B4 alleviated the inflammatory response in cows with CM mainly by regulating lipid metabolism.

Nontargeted metabolomics analysis of follicular fluid in patients with endometriosis provides a new direction for the study of oocyte quality

Endometriosis is a common, estrogen-dependent chronic gynecological disease that endangers the reproductive system and systemic metabolism of patients. We aimed to investigate the differences in metabolic profiles in the follicular fluid between infertile patients with endometriosis and controls. A total of 25 infertile patients with endometriosis and 25 infertile controls who were similar in age, BMI, fertilization method and ovulation induction treatment were recruited in this study. Metabolomics analysis of follicular fluid was performed by two methods of high-performance liquid chromatography tandem mass spectrometry. There were 36 upregulated and 17 downregulated metabolites in the follicular fluid of patients in the endometriosis group. KEGG pathway analysis revealed that these metabolites were enriched in phenylalanine, tyrosine and tryptophan biosynthesis, aminoacyl-tRNA biosynthesis, phenylalanine metabolism and pyrimidine metabolism pathways. A biomarker panel consisting of 20 metabolites was constructed by random forest, with an accuracy of 0.946 and an AUC of 0.988. This study characterizes differences in follicular fluid metabolites and associated pathway profiles in infertile patients with endometriosis. These findings can provide a better comprehensive understanding of the disease and a new direction for the study of oocyte quality, as well as potential metabolic markers for the prognosis of endometriosis.

Uridine Inhibits Hepatocellular Carcinoma Cell Development by Inducing Ferroptosis

Uridine is a key metabolite used as a substrate for the production of DNA, RNA, and glucose, and it is mainly synthesized in the liver. Currently, it is not known whether uridine levels are altered in the tumor microenvironment of patients with hepatocellular carcinoma (HCC) and whether uridine can be a target for tumor therapy. In this study, the detection of genes associated with de novo uridine synthesis, carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, dihydroorotase (CAD) (n = 115), and dihydroorotate dehydrogenase (DHODH) (n = 115) in HCC tissues through tissue microarrays revealed that the expression of CAD and DHODH was higher in tumor compared with paraneoplastic tissues. Next, we collected tumor tissues from surgically resected HCC patients and the corresponding adjacent non-tumor tissues (n = 46) for LC-MS/MS assays. The results showed that the median and interquartile ranges of uridine content in non-tumor and tumor tissues were 640.36 (504.45-807.43) and 484.22 (311.91-626.73) nmol/g, respectively. These results suggest that uridine metabolism is disturbed in HCC patients. To further investigate whether uridine can be used as a tumor-therapeutic target, a series of high concentrations of uridine were incubated with HCC cells in vitro and in vivo. It was observed that uridine dose-dependently inhibited the proliferation, invasion, and migration of HCC cells by activating the ferroptosis pathway. Overall, these results reveal for the first time the range of uridine content in human HCC tissues and suggest that uridine may be a new target for HCC therapy.

Uridine Alleviates Sepsis-Induced Acute Lung Injury by Inhibiting Ferroptosis of Macrophage

Uridine metabolism is extensively reported to be involved in combating oxidative stress. Redox-imbalance-mediated ferroptosis plays a pivotal role in sepsis-induced acute lung injury (ALI). This study aims to explore the role of uridine metabolism in sepsis-induced ALI and the regulatory mechanism of uridine in ferroptosis. The Gene Expression Omnibus (GEO) datasets including lung tissues in lipopolysaccharides (LPS) -induced ALI model or human blood sample of sepsis were collected. In vivo and vitro, LPS was injected into mice or administered to THP-1 cells to generate sepsis or inflammatory models. We identified that uridine phosphorylase 1 (UPP1) was upregulated in lung tissues and septic blood samples and uridine significantly alleviated lung injury, inflammation, tissue iron level and lipid peroxidation. Nonetheless, the expression of ferroptosis biomarkers, including SLC7A11, GPX4 and HO-1, were upregulated, while lipid synthesis gene (ACSL4) expression was greatly restricted by uridine supplementation. Moreover, pretreatment of ferroptosis inducer (Erastin or Era) weakened while inhibitor (Ferrostatin-1 or Fer-1) strengthened the protective effects of uridine. Mechanistically, uridine inhibited macrophage ferroptosis by activating Nrf2 signaling pathway. In conclusion, uridine metabolism dysregulation is a novel accelerator for sepsis-induced ALI and uridine supplementation may offer a potential avenue for ameliorating sepsis-induced ALI by suppressing ferroptosis.

Circulating uridine dynamically and adaptively regulates food intake in humans

Feeding behavior must be continuously adjusted to match energy needs. Recent discoveries in murine models identified uridine as a regulator of energy balance. Here, we explore its contribution to the complex control of food intake in humans by administering a single dose of uridine monophosphate (UMP; 0.5 or 1 g) to healthy participants in two placebo-controlled studies designed to assess food behavior (registration: DRKS00014874). We establish that endogenous circulating uridine correlates with hunger and ensuing food consumption. It also dynamically decreases upon caloric ingestion, prompting its potential role in a negative feedback loop regulating energy intake. We further demonstrate that oral UMP administration temporarily increases circulating uridine and-when within the physiological range-enhances hunger and caloric intake proportionally to participants' basal energy needs. Overall, uridine appears as a potential target to tackle dysfunctions of feeding behavior in humans.

The Effect of Uridine on the State of Skeletal Muscles and the Functioning of Mitochondria in Duchenne Dystrophy

Duchenne muscular dystrophy is caused by the loss of functional dystrophin that secondarily causes systemic metabolic impairment in skeletal muscles and cardiomyocytes. The nutraceutical approach is considered as a possible complementary therapy for this pathology. In this work, we have studied the effect of pyrimidine nucleoside uridine (30 mg/kg/day for 28 days, i.p.), which plays an important role in cellular metabolism, on the development of DMD in the skeletal muscles of dystrophin deficient mdx mice, as well as its effect on the mitochondrial dysfunction that accompanies this pathology. We found that chronic uridine administration reduced fibrosis in the skeletal muscles of mdx mice, but it had no effect on the intensity of degeneration/regeneration cycles and inflammation, pseudohypetrophy, and muscle strength of the animals. Analysis of TEM micrographs showed that uridine also had no effect on the impaired mitochondrial ultrastructure of mdx mouse skeletal muscle. The administration of uridine was found to lead to an increase in the expression of the Drp1 and Parkin genes, which may indicate an increase in the intensity of organelle fission and the normalization of mitophagy. Uridine had little effect on OXPHOS dysfunction in mdx mouse mitochondria, and moreover, it was suppressed in the mitochondria of wild type animals. At the same time, uridine restored the transport of potassium ions and reduced the production of reactive oxygen species; however, this had no effect on the impaired calcium retention capacity of mdx mouse mitochondria. The obtained results demonstrate that the used dose of uridine only partially prevents mitochondrial dysfunction in skeletal muscles during Duchenne dystrophy, though it mitigates the development of destructive processes in skeletal muscles.

Effect of Chronic Treatment with Uridine on Cardiac Mitochondrial Dysfunction in the C57BL/6 Mouse Model of High-Fat Diet-Streptozotocin-Induced Diabetes

Long-term hyperglycemia in diabetes mellitus is associated with complex damage to cardiomyocytes and the development of mitochondrial dysfunction in the myocardium. Uridine, a pyrimidine nucleoside, plays an important role in cellular metabolism and is used to improve cardiac function. Herein, the antidiabetic potential of uridine (30 mg/kg/day for 21 days, i.p.) and its effect on mitochondrial homeostasis in the heart tissue were examined in a high-fat diet-streptozotocin-induced model of diabetes in C57BL/6 mice. We found that chronic administration of uridine to diabetic mice normalized plasma glucose and triglyceride levels and the heart weight/body weight ratio and increased the rate of glucose utilization during the intraperitoneal glucose tolerance test. Analysis of TEM revealed that uridine prevented diabetes-induced ultrastructural abnormalities in mitochondria and sarcomeres in ventricular cardiomyocytes. In diabetic heart tissue, the mRNA level of Ppargc1a decreased and Drp1 and Parkin gene expression increased, suggesting the disturbances of mitochondrial biogenesis, fission, and mitophagy, respectively. Uridine treatment of diabetic mice restored the mRNA level of Ppargc1a and enhanced Pink1 gene expression, which may indicate an increase in the intensity of mitochondrial biogenesis and mitophagy, and as a consequence, mitochondrial turnover. Uridine also reduced oxidative phosphorylation dysfunction and suppressed lipid peroxidation, but it had no significant effect on the impaired calcium retention capacity and potassium transport in the heart mitochondria of diabetic mice. Altogether, these findings suggest that, along with its hypoglycemic effect, uridine has a protective action against diabetes-mediated functional and structural damage to cardiac mitochondria and disruption of mitochondrial quality-control systems in the diabetic heart.

Maternal pyrimidine nucleoside supplementation regulates fatty acid, amino acid and glucose metabolism of offspring

Pyrimidine nucleosides (PN) are abundant in mammalian milk and mainly involved in glycogen deposition and lipid metabolism. To investigate the effects of maternal supplementation with pyrimidine nucleoside on glucose, fatty acids (FAs), and amino acids (AAs) metabolism in neonatal piglets. Forty pregnant sows were randomly assigned into the control (CON) group (fed a basal diet, n = 20) or the PN group (fed a basal diet supplemented with PN at 150 g/t, n = 20). Litter size, born alive and birth litter weight were recorded. The serum and placenta of sows, and jejunum and liver of neonatal piglets were sampled. The results indicated that supplementing sow diets with PN decreased birth mortality and increased the birth weight of piglets (P < 0.05). In addition, neonates from sows supplemented with PN had higher glucose levels in serum and liver compared with the CON group (P < 0.05). Moreover, maternal PN supplementation regulated the ratio of saturated FAs and polyunsaturated FAs, and AAs content in serum and liver of piglets (P < 0.05). Furthermore, an up-regulation of mRNA expression of genes related to glucose and AA transport were observed in the neonatal jejunum from the PN group (P < 0.05). Additionally, hepatic protein expressions of phosphorylated hormone-sensitive lipase (P-HSL), HSL, sterol regulatory element-binding transcription factor 1c (SREBP-1c), and phosphorylated protein kinase B (P-AKT) was higher in the piglets from the PN group than the CON group (P < 0.05). Together, maternal PN supplementation may regulate nutrient metabolism of neonatal piglets by modulating the gene expression of glucose and AA transporters in placenta and jejunum, and the gene and protein expression of key enzymes related to lipid metabolism in liver of neonatal piglets, which may improve the reproductive performance of sows.

Metabolite, protein, and tissue dysfunction associated with COVID-19 disease severity

Proteins are direct products of the genome and metabolites are functional products of interactions between the host and other factors such as environment, disease state, clinical information, etc. Omics data, including proteins and metabolites, are useful in characterizing biological processes underlying COVID-19 along with patient data and clinical information, yet few methods are available to effectively analyze such diverse and unstructured data. Using an integrated approach that combines proteomics and metabolomics data, we investigated the changes in metabolites and proteins in relation to patient characteristics (e.g., age, gender, and health outcome) and clinical information (e.g., metabolic panel and complete blood count test results). We found significant enrichment of biological indicators of lung, liver, and gastrointestinal dysfunction associated with disease severity using publicly available metabolite and protein profiles. Our analyses specifically identified enriched proteins that play a critical role in responses to injury or infection within these anatomical sites, but may contribute to excessive systemic inflammation within the context of COVID-19. Furthermore, we have used this information in conjunction with machine learning algorithms to predict the health status of patients presenting symptoms of COVID-19. This work provides a roadmap for understanding the biochemical pathways and molecular mechanisms that drive disease severity, progression, and treatment of COVID-19.

Synthesis, antimicrobial, SAR, PASS, molecular docking, molecular dynamics and pharmacokinetics studies of 5'-O-uridine derivatives bearing acyl moieties: POM study and identification of the pharmacophore sites

Because of their superior antibacterial and pharmacokinetic capabilities, many nucleoside-based esters show potential against microorganisms, and may be used as pharmacological agents to address multidrug-resistant pathogenic problems. In this study, several aliphatic and aromatic groups were inserted to synthesize various 5'-O-decanoyluridine (2-5) and 5'-O-lauroyluridine derivatives (6-7) for antimicrobial, in silico computational, pharmacokinetic and POM (Petra/Osiris/Molinspiration). The chemical structures of the synthesized uridine derivatives were confirmed by physicochemical, elemental, and spectroscopic analyses. In vitro antimicrobial screening against five bacteria and two fungi, as well as the prediction of substance activity spectra (PASS), revealed that these uridine derivatives have promising antifungal properties when compared to the antibacterial activities. Density functional theory (DFT) was used to calculate the thermodynamic and physicochemical properties. Molecular docking was conducted against lanosterol 14a-demethylase CYP51A1 (3JUV) and Aspergillus flavus (1R4U) and revealed binding affinities and non-covalent interactions with the target. Then, a 150 ns molecular dynamic simulation was performed to confirm the behavior of the complex structure formed by microbial protein under in silico physiological conditions to examine its stability over time, which revealed a stable conformation and binding pattern in a stimulating environment of uridine derivatives. The acyl chain {CH₃(CH₂)₉CO-} and {CH₃(CH₂)₁₀CO-} in conjunction with sugar, was determined to have the most potent activity against bacterial and fungal pathogens in a structure-activity relationships (SAR) investigation. POM analyses were conducted with the presence of an antifungal (O ^δ- -- O' ^δ-) pharmacophore site. Overall, the present study might be useful for the development of uridine-based novel multidrug-resistant antimicrobial.

Metabolic perturbations and health impact from exposure to a combination of multiple harmful Maillard reaction products on Sprague-Dawley rats

The present study aimed to investigate the metabolic perturbations and health impact of the co-accumulation of Maillard reaction products (MRPs), including acrylamide, harmane, and N^ε-(carboxymethyl)lysine (CML), via serum biochemical and histopathological examinations as well as metabolomic analysis. Sprague-Dawley rats were treated with acrylamide (2 mg per kg body weight [bw]), harmane (1 mg per kg bw), CML (2 mg per kg bw), and combinations of these MRPs. Harmane did not cause adverse effects on the health of rats, whereas acrylamide and CML resulted in significantly (P < 0.05) decreased insulin sensitivity (HOMA-IR > 1), increased oxidative stress levels, and pathological injuries to the pancreas, liver, and gastrocnemius. Owing to the antioxidant and anti-diabetic activities of harmane, the effects of the combination of the MRPs on oxidative stress levels, blood glucose metabolism, and pathological injuries to the pancreas and gastrocnemius were relieved. However, new health problems, including pathological injury of the kidneys and increased cancer risk, were observed. Metabolomic analysis revealed that this may be related to the effects of MRPs on the arginine biosynthesis pathway, which resulted in the abnormal metabolism of fumaric acid and the tricarboxylic acid cycle. These results indicated that the mechanisms of the combined effect of MRPs and their effects on health cannot be predicted from the effects of individual MRPs.

In vitro antimicrobial, physicochemical, pharmacokinetics and molecular docking studies of benzoyl uridine esters against SARS-CoV-2 main protease

Different esters were found potential against microorganisms, and could be a better choice to solve the multidrug resistant (MDR) pathogenic global issue due to their improved biological and pharmacokinetic properties. In this view, several 4-t-butylbenzoyl uridine esters 4-15 with different aliphatic and aromatic groups were synthesized for antimicrobial, physicochemical and biological studies. In vitro antimicrobial tests against nine bacteria and three fungi along with prediction of activity spectra for substances (PASS) indicated promising antifungal functionality of these uridine esters compared to the antibacterial activities. In support of this observation their cytotoxicity and molecular docking studies have been performed against lanosterol 14α-demethylase (CYP51A1) and Aspergillus flavus (1R51). Significant binding affinities were observed against SARS-CoV-2 main protease (7BQY) considering hydroxychloroquine (HCQ) as standard. ADMET predictions were investigated to evaluate their absorption, metabolism and toxic properties. Most of the uridine esters showed better results than that of the HCQ. Overall, the present study might be useful for the development of uridine-based novel MDR antimicrobial and COVID-19 drugs.

Molnupiravir and Its Antiviral Activity Against COVID-19

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) constitutes a major worldwide public health threat and economic burden. The pandemic is still ongoing and the SARS-CoV-2 variants are still emerging constantly, resulting in an urgent demand for new drugs to treat this disease. Molnupiravir, a biological prodrug of NHC (β-D-N(4)-hydroxycytidine), is a novel nucleoside analogue with a broad-spectrum antiviral activity against SARS-CoV, SARS-CoV-2, Middle East respiratory syndrome coronavirus (MERS-CoV), influenza virus, respiratory syncytial virus (RSV), bovine viral diarrhea virus (BVDV), hepatitis C virus (HCV) and Ebola virus (EBOV). Molnupiravir showed potent therapeutic and prophylactic activity against multiple coronaviruses including SARS-CoV-2, SARS-CoV, and MERS-CoV in animal models. In clinical trials, molnupiravir showed beneficial effects for mild to moderate COVID-19 patients with a favorable safety profile. The oral bioavailability and potent antiviral activity of molnupiravir highlight its potential utility as a therapeutic candidate against COVID-19. This review presents the research progress of molnupiravir starting with its discovery and synthesis, broad-spectrum antiviral effects, and antiviral mechanism. In addition, the preclinical studies, antiviral resistance, clinical trials, safety, and drug tolerability of molnupiravir are also summarized and discussed, aiming to expand our knowledge on molnupiravir and better deal with the COVID-19 epidemic.

Integrated Metabolomics and Proteomics Analysis of Urine in a Mouse Model of Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a serious stress disorder that occurs in individuals who have experienced major traumatic events. The underlying pathological mechanisms of PTSD are complex, and the related predisposing factors are still not fully understood. In this study, label-free quantitative proteomics and untargeted metabolomics were used to comprehensively characterize changes in a PTSD mice model. Differential expression analysis showed that 12 metabolites and 27 proteins were significantly differentially expressed between the two groups. Bioinformatics analysis revealed that the differentiated proteins were mostly enriched in: small molecule binding, transporter activity, extracellular region, extracellular space, endopeptidase activity, zymogen activation, hydrolase activity, proteolysis, peptidase activity, sodium channel regulator activity. The differentially expressed metabolites were mainly enriched in Pyrimidine metabolism, D-Glutamine and D-glutamate metabolism, Alanine, aspartate and glutamate metabolism, Arginine biosynthesis, Glutathione metabolism, Arginine, and proline metabolism. These results expand the existing understanding of the molecular basis of the pathogenesis and progression of PTSD, and also suggest a new direction for potential therapeutic targets of PTSD. Therefore, the combination of urine proteomics and metabolomics explores a new approach for the study of the underlying pathological mechanisms of PTSD.

Uridine relieves MSCs and chondrocyte senescence in vitvo and exhibits the potential to treat osteoarthritis in vivo

Osteoarthritis (OA) is a degenerative disease of extremely high incidence in the elderly. Therefore, anti-aging may be an important prerequisite for treating OA. The senescence of chondrocytes and mesenchymal stem cells (MSCs) is one of the important factors that causes OA. Here, the effect of uridine (which is a functional food derived from plants or animals) on senescence of chondrocytes and MSCs was evaluated in in vivo and in vitro experiments. For this, we established the senescence model of chondrocyte and MSCs in vitro, and established the OA model in vivo, and a series of experiments (such as CLSM, ELISA, Western blot, etc.) were conducted to evaluate the effect of uridine on chondrocyte and MSCs senescence. The results showed that uridine could alleviate chondrocyte and MSCs senescence in vitro by evaluating a series of aging markers. Furthermore, uridine could also relieve OA in vivo. In summary, in the present work, we found that uridine can alleviate chondrocyte and MSCs senescence in in vitro and in vivo experiments. Uridine has shown great potential in the treatment of OA in vivo, suggesting that uridine could be used to treat and prevent OA induced by aging, and has potential clinical applications in future.

Analysis of circulating metabolites to differentiate Parkinson's disease and essential tremor

Parkinson disease (PD) and essential tremor (ET) are two common adult-onset tremor disorders in which prevalence increases with age. PD is a neurodegenerative condition with progressive disability. In ET, neurodegeneration is not an established etiology. We sought to determine whether an underlying metabolic pattern may differentiate ET from PD. Circulating metabolites in plasma and cerebrospinal fluid were analyzed using gas chromatography-mass spectroscopy. There were several disrupted pathways in PD compared to ET plasma including glycolysis, tyrosine, phenylalanine, tyrosine biosynthesis, purine and glutathione metabolism. Elevated α-synuclein levels in plasma and CSF distinguished PD from ET. The perturbed metabolic state in PD was associated with imbalance in the pentose phosphate pathway, deficits in energy production, and change in NADPH, NADH and nicotinamide phosphoribosyltransferase levels. This work demonstrates significant metabolic differences in plasma and CSF of PD and ET patients.

An Update on Pharmacological Relevance and Chemical Synthesis of Natural Products and Derivatives with Anti SARS-CoV-2 Activity

Natural products recognized traditionally as a vital source of active constituents in pharmacotherapy. The COVID-19 infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly transmissible, pathogenic, and considered an ongoing global health emergency. The emergence of COVID-19 globally and the lack of adequate treatment brought attention towards herbal medicines, and scientists across the globe instigated the search for novel drugs from medicinal plants and natural products to tackle this deadly virus. The natural products rich in scaffold diversity and structural complexity are an excellent source for antiviral drug discovery. Recently the investigation of several natural products and their synthetic derivatives resulted in the identification of promising anti SARS-CoV-2 agents. This review article will highlight the pharmacological relevance and chemical synthesis of the recently discovered natural product and their synthetic analogs as SARS-CoV-2 inhibitors. The summarized information will pave the path for the natural product-based drug discovery of safe and potent antiviral agents, particularly against SARS-CoV-2.

Uridine treatment prevents myocardial injury in rat models of acute ischemia and ischemia/reperfusion by activating the mitochondrial ATP-dependent potassium channel

The effect of uridine on the myocardial ischemic and reperfusion injury was investigated. A possible mechanism of its cardioprotective action was established. Two rat models were used: (1) acute myocardial ischemia induced by occlusion of the left coronary artery for 60 min; and (2) myocardial ischemia/reperfusion with 30-min ischemia and 120-min reperfusion. In both models, treatment with uridine (30 mg/kg) prevented a decrease in cell energy supply and in the activity of the antioxidant system, as well as an increase in the level of lipid hydroperoxides and diene conjugates. This led to a reduction of the necrosis zone in the myocardium and disturbances in the heart rhythm. The blocker of the mitochondrial ATP-dependent potassium (mitoKATP) channel 5-hydroxydecanoate limited the positive effects of uridine. The data indicate that the cardioprotective action of uridine may be related to the activation of the mitoKATP channel. Intravenously injected uridine was more rapidly eliminated from the blood in hypoxia than in normoxia, and the level of the mitoKATP channel activator UDP in the myocardium after uridine administration increased. The results suggest that the use of uridine can be a potentially effective approach to the management of cardiovascular diseases.

Uridine attenuates obesity, ameliorates hepatic lipid accumulation and modifies the gut microbiota composition in mice fed with a high-fat diet

Uridine (UR) is a pyrimidine nucleoside that plays an important role in regulating glucose and lipid metabolism. The aim of this study was to investigate the effect of UR on obesity, fat accumulation in liver, and gut microbiota composition in high-fat diet (HFD)-fed mice. ICR mice were, respectively, divided into 3 groups for 8 weeks, that is, control (CON, n = 12), high fat diet (HFD, n = 16), and HFD + UR groups (0.4 mg mL-1 in drinking water, n = 16). UR supplementation significantly reduced the body weight and suppressed the accumulation of subcutaneous, epididymal, and mesenteric WAT in HFD-fed mice (P < 0.05). Meanwhile, UR also decreased the lipid droplet accumulation in the liver and liver organoids (P < 0.05). In addition, UR supplementation increased bacterial diversity and Bacteroidetes abundance, and decreased the Firmicutes-to-Bacteroidetes ratio in HFD-fed mice significantly (P < 0.05). UR promoted the growth of butyrate-producing bacteria of Odoribacter, unidentified-Ruminococcaceae, Intestinimonas, Ruminiclostridium, and unidentified-Lachnospiraceae. A close correlation between several specific bacterial phyla or genera and the levels of WAT weight, hepatic TC, or hepatic TG genera was revealed through Spearman's correlation analysis. These results demonstrated that UR supplementation could be beneficial by attenuating HFD-induced obesity and nonalcoholic fatty liver disease.

Blood metabolomics in infants enrolled in a dose escalation pilot trial of budesonide in surfactant

BACKGROUND

The pathogenesis of BPD includes inflammation and oxidative stress in the immature lung. Corticosteroids improve respiratory status and outcome, but the optimal treatment regimen for benefit with low systemic effects is uncertain.

METHODS

In a pilot dose escalation trial, we administered ≤5 daily doses of budesonide in surfactant to 24 intubated premature infants (Steroid And Surfactant in ELGANs (SASSIE)). Untargeted metabolomics was performed on dried blood spots using UPLC-MS/MS. Tracheal aspirate IL-8 concentration was determined as a measure of lung inflammation.

RESULTS

Metabolomics data for 829 biochemicals were obtained on 121 blood samples over 96 h from 23 infants receiving 0.025, 0.05, or 0.1 mg budesonide/kg. Ninety metabolites were increased or decreased in a time- and dose-dependent manner at q ≤ 0.1 with overrepresentation in lipid and amino acid super pathways. Different dose response patterns occurred, with negative regulation associated with highest sensitivity to budesonide. Baseline levels of 22 regulated biochemicals correlated with lung inflammation (IL-8), with highest significance for sphingosine and thiamin.

CONCLUSIONS

Numerous metabolic pathways are regulated in a dose-dependent manner by glucocorticoids, which apparently act via distinct mechanisms that impact dose sensitivity. The findings identify candidate blood biochemicals as biomarkers of lung inflammation and systemic responses to corticosteroids.

IMPACT

Treatment of premature infants in respiratory failure with 0.1 mg/kg intra-tracheal budesonide in surfactant alters levels of ~11% of detected blood biochemicals in discrete time- and dose-dependent patterns. A subset of glucocorticoid-regulated biochemicals is associated with lung inflammatory status as assessed by lung fluid cytokine concentration. Lower doses of budesonide in surfactant than currently used may provide adequate anti-inflammatory responses in the lung with fewer systemic effects, improving the benefit:risk ratio.

The unaided recovery of marathon-induced serum metabolome alterations

Endurance athlete performance is greatly dependent on sufficient post-race system recovery, as endurance races have substantial physiological, immunological and metabolic effects on these athletes. To date, the effects of numerous recovery modalities have been investigated, however, very limited literature exists pertaining to metabolic recovery of athletes after endurance races without the utilisation of recovery modalities. As such, this investigation is aimed at identifying the metabolic recovery trend of athletes within 48 h after a marathon. Serum samples of 16 athletes collected 24 h before, immediately after, as well as 24 h and 48 h post-marathon were analysed using an untargeted two-dimensional gas chromatography time-of-flight mass spectrometry metabolomics approach. The metabolic profiles of these comparative time-points indicated a metabolic shift from the overall post-marathon perturbed state back to the pre-marathon metabolic state during the recovery period. Statistical analyses of the data identified 61 significantly altered metabolites including amino acids, fatty acids, tricarboxylic acid cycle, carbohydrates and associated intermediates. These intermediates recovered to pre-marathon related concentrations within 24 h post-marathon, except for xylose which only recovered within 48 h. Furthermore, fluctuations in cholesterol and pyrimidine intermediates indicated the activation of alternative recovery mechanisms. Metabolic recovery of the athletes was attained within 48 h post-marathon, most likely due to reduced need for fuel substrate catabolism. This may result in the activation of glycogenesis, uridine-dependent nucleotide synthesis, protein synthesis, and the inactivation of cellular autophagy. These results may be beneficial in identifying more efficient, targeted recovery approaches to improve athletic performance.

Turning the Tide: Natural Products and Natural-Product-Inspired Chemicals as Potential Counters to SARS-CoV-2 Infection

The novel and highly pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has become a continued focus of global attention due to the serious threat it poses to public health. There are no specific drugs available to combat SARS-CoV-2 infection. Natural products (carolacton, homoharringtonine, emetine, and cepharanthine) and natural product-inspired small molecules (ivermectin, GS-5734, EIDD-2801, and ebselen) are potential anti-SARS-CoV-2 agents that have attracted significant attention due to their broad-spectrum antiviral activities. Here, we review the research on potential landmark anti-SARS-CoV-2 agents, systematically discussing the importance of natural products and natural-product-inspired small molecules in the research and development of safe and effective antiviral agents.

Uridine Metabolism and Its Role in Glucose, Lipid, and Amino Acid Homeostasis

Pyrimidine nucleoside uridine plays a critical role in maintaining cellular function and energy metabolism. In addition to its role in nucleoside synthesis, uridine and its derivatives contribute to reduction of cytotoxicity and suppression of drug-induced hepatic steatosis. Uridine is mostly present in blood and cerebrospinal fluid, where it contributes to the maintenance of basic cellular functions affected by UPase enzyme activity, feeding habits, and ATP depletion. Uridine metabolism depends on three stages: de novo synthesis, salvage synthesis pathway and catabolism, and homeostasis, which is tightly relating to glucose homeostasis and lipid and amino acid metabolism. This review is devoted to uridine metabolism and its role in glucose, lipid, and amino acid homeostasis.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

Short-Term Oral UMP/UR Administration Regulates Lipid Metabolism in Early-Weaned Piglets

Simple Summary

Uridine monophosphate (UMP) and uridine (UR) are rich in sow’s milk. The results from this study showed that UMP and UR affect the lipid profile and lipid metabolism in weanling piglets. It is suggested that UMP and UR improve the energy status in early-weaned piglets.

Abstract

As a main ingredient of milk, the nucleotides content is about 12–58 mg/g, which plays a critical role in maintaining cellular function and lipid metabolism. This study was conducted to evaluate the effects of short-term uridine monophosphate (UMP) and uridine (UR) administration on lipid metabolism in early-weaned piglets. Twenty-one weaned piglets (7 d of age; 3.32 ± 0.20 kg average body weight) were randomly assigned into three groups: The control (CON), UMP, and UR group, and oral administered UMP or UR for 10 days, respectively. The results showed that supplementation with UMP significantly increased (p < 0.05) serum low density lipoprotein (LDL) and tended to increase (p = 0.062) serum total cholesterol (TC) content of piglets when compared with the other two groups. Oral administration with UMP and UR significantly decreased (p < 0.05) the serum total bile acid (TBA) and plasma free fatty acids (FFA) of piglets, and significantly reduced the fatty acid content of C12:0 (p < 0.01) and C14:0 (p < 0.05) in liver. Experiments about key enzymes that are involved in de novo synthesis of fatty acid showed that the gene expression of liver X receptors (LXRα), sterol regulatory element-binding transcription factor 1 (SREBP1c), fatty acid desaturase 2 (FADS2), and fatty acid elongase 5 (ELOVL5) were remarkably down-regulated (p < 0.05) with UMP and UR treatment, and key factors of adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and carnitine palmitoyl transferase 1 (CPT-1α) involved in fatty acid catabolism were also decreased (p < 0.05). Additionally, the protein expression of phosphorylated-mTOR was not affected while phosphorylation of AKT was repressed (p < 0.05). In conclusion, short-term oral UMP or UR administration could regulate fatty acid composition and lipid metabolism, thus providing energy for early-weaned piglets.

Characterization of the urinary metabolic profile of cholangiocarcinoma in a United Kingdom population

Background: Outside South-East Asia, most cases of cholangiocarcinoma (CCA) have an obscure etiology. There is often diagnostic uncertainty. Metabolomics using ultraperformance liquid chromatography mass spectrometry (UPLC-MS) offers the portent to distinguish disease-specific metabolic signatures. We aimed to define such a urinary metabolic signature in a patient cohort with sporadic CCA and investigate whether there were characteristic differences from those in patients with hepatocellular carcinoma (HCC), metastatic secondary liver cancer, pancreatic cancer and ovarian cancer (OCA). Methods: Spot urine specimens were obtained from 211 subjects in seven participating centers across the UK. Samples were collected from healthy controls and from patients with benign hepatic disease (gallstone, biliary strictures, sphincter of Oddi dysfunction and viral hepatitis) and patients with malignant conditions (HCC, pancreatic cancer, OCA and metastatic cancer in the liver). The spectral metabolite profiles were generated using a UPLC-MS detector and data were analyzed using multivariate and univariate statistical analyses. Results: The greatest class differences were seen between the metabolic profiles of disease-free controls compared to individuals with CCA with altered acylcarnitine, bile acid and purine levels. Individuals with benign strictures showed comparable urine profiles to patients with malignant bile duct lesions. The metabolic signatures of patients with bile duct tumors were distinguishable from patients with hepatocellular and ovarian tumors, but no difference was observed between CCA cases and patients with pancreatic cancer or hepatic secondary metastases. Conclusion: CCA causes subtle but detectable changes in the urine metabolic profiles. The findings point toward potential applications of metabonomics in early tumor detection. However, it is key to utilize both global and targeted metabonomics in a larger cohort for in-depth characterization of the urine metabolome in hepato-pancreato-biliary disease.

Functional disruption of pyrimidine nucleoside transporter CNT1 results in a novel inborn error of metabolism with high excretion of uridine and cytidine

Genetic defects in the pyrimidine nucleoside transporters of the CNT transporter family have not yet been reported. Metabolic investigations in a patient with infantile afebrile tonic-clonic seizures revealed increased urinary uridine and cytidine excretion. Segregation of this metabolic trait in the family showed the same biochemical phenotype in a healthy older brother of the index. Whole exome sequencing revealed biallelic mutations in SLC28A1 encoding the pyrimidine nucleoside transporter CNT1 in the index and his brother. Both parents and unaffected sibs showed the variant in heterozygous state. The transporter is expressed in the kidneys. Compelling evidence is available for the disrupting effect of the mutation on the transport function thus explaining the increased excretion of the pyrimidine nucleosides. The exome analysis also revealed a pathogenic mutation in PRRT2 in the index, explaining the epilepsy phenotype in infancy. At present, both the index (10 years) and his older brother are asymptomatic. Mutations in SLC28A1 cause a novel inborn error of metabolism that can be explained by the disrupted activity of the pyrimidine nucleoside transporter CNT1. This is the first report describing a defect in the family of CNT concentrative pyrimidine nucleoside transporter proteins encoded by the SLC28 gene family. In all likelihood, the epilepsy phenotype in the index is unrelated to the SLC28A1 defect, as this can be fully explained by the pathogenic PRRT2 variant. Clinical data on more patients are required to prove whether pathogenic mutations in SLC28A1 have any clinical consequences or are to be considered a benign metabolic phenotype.

Diverse metabolic reactions activated during 58-hr fasting are revealed by non-targeted metabolomic analysis of human blood

During human fasting, metabolic markers, including butyrates, carnitines, and branched-chain amino acids, are upregulated for energy substitution through gluconeogenesis and use of stored lipids. We performed non-targeted, accurate semiquantitative metabolomic analysis of human whole blood, plasma, and red blood cells during 34–58 hr fasting of four volunteers. During this period, 44 of ~130 metabolites increased 1.5~60-fold. Consistently fourteen were previously reported. However, we identified another 30 elevated metabolites, implicating hitherto unrecognized metabolic mechanisms induced by fasting. Metabolites in pentose phosphate pathway are abundant, probably due to demand for antioxidants, NADPH, gluconeogenesis and anabolic metabolism. Global increases of TCA cycle-related compounds reflect enhanced mitochondrial activity in tissues during fasting. Enhanced purine/pyrimidine metabolites support RNA/protein synthesis and transcriptional reprogramming, which is promoted also by some fasting-related metabolites, possibly via epigenetic modulations. Thus diverse, pronounced metabolite increases result from greatly activated catabolism and anabolism stimulated by fasting. Anti-oxidation may be a principal response to fasting.

Deficiency of perforin and hCNT1, a novel inborn error of pyrimidine metabolism, associated with a rapidly developing lethal phenotype due to multi-organ failure

Pyrimidine nucleotides are essential for a vast number of cellular processes and dysregulation of pyrimidine metabolism has been associated with a variety of clinical abnormalities. Inborn errors of pyrimidine metabolism affecting enzymes in the pyrimidine de novo and degradation pathway have been identified but no patients have been described with a deficiency in proteins affecting the cellular import of ribonucleosides. In this manuscript, we report the elucidation of the genetic basis of the observed uridine-cytidineuria in a patient presenting with fever, hepatosplenomegaly, persistent lactate acidosis, severely disturbed liver enzymes and ultimately multi-organ failure. Sequence analysis of genes encoding proteins directly involved in the metabolism of uridine and cytidine showed two variants c.1528C > T (p.R510C) and c.1682G > A (p.R561Q) in SLC28A1, encoding concentrative nucleotide transporter 1 (hCNT1). Functional analysis showed that these variants affected the three-dimensional structure of hCNT1, altered glycosylation and decreased the half-life of the mutant proteins which resulted in impaired transport activity. Co-transfection of both variants, mimicking the trans disposition of c.1528C > T (p.R510C) and c.1682G > A (p.R561Q) in the patient, significantly impaired hCNT1 biological function. Whole genome sequencing identified two pathogenic variants c.50delT; p.(Leu17Argfs*34) and c.853_855del; p.(Lys285del) in the PRF1 gene, indicating that our patient was also suffering from Familial Hemophagocytic Lymphohistiocytosis type 2. The identification of two co-existing monogenic defects might have resulted in a blended phenotype. Thus, the clinical presentation of isolated hCNT1 deficiency remains to be established.

Global metabolic responses of the lenok (Brachymystax lenok) to thermal stress

High temperature is a powerful stressor for fish living in natural and artificial environments, especially for cold water species. Understanding the impact of thermal stress on physiological processes of fish is crucial for better cultivation and fisheries management. However, the metabolic mechanism of cold water fish to thermal stress is still not completely clear. In this study, a NMR-based metabonomic strategy in combination with high-throughput RNA-Seq was employed to investigate global metabolic changes of plasma and liver in a typical cold water fish species lenok (Brachymystax lenok) subjected to a sub-lethal high temperature. Our results showed that thermal stress caused multiple dynamic metabolic alterations of the lenok with prolonged stress, including repression of energy metabolism, shifts in lipid metabolism, alterations in amino acid metabolism, changes in choline and nucleotide metabolisms. Specifically, thermal stress induced an activation of glutamate metabolism, indicating that glutamate could be an important biomarker associated with thermal stress. Evidence from Hsp 70 gene expression, blood biochemistry and histology confirmed that high temperature exposure had negative effects on health of the lenok. These findings imply that thermal stress has a severe adverse effect on fish health and demonstrate that the integrated analyses combining NMR-based metabonomics and transcriptome strategy is a powerful approach to enhance our understanding of metabolic mechanisms of fish to thermal stress.

Anomalous interaction of tri-acyl ester derivatives of uridine nucleoside with a l-α-dimyristoylphosphatidylcholine biomembrane model: a differential scanning calorimetry study

OBJECTIVES

Uridine was conjugated with fatty acids to improve the drug lipophilicity and the interaction with phospholipid bilayers.

METHODS

The esterification reaction using carbodiimides compounds as coupling agents and a nucleophilic catalyst allowed us to synthesize tri-acyl ester derivatives of uridine with fatty acids. Analysis of molecular interactions between these tri-acyl ester derivatives and l-α-dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLV) - as a mammalian cell membrane model - have been performed by differential scanning calorimetry (DSC).

KEY FINDINGS

The DSC thermograms suggest that nucleoside and uridine triacetate softly interact with phospholipidic multilamellar vesicles which are predominantly located between the polar phase, whereas the tri-acyl ester derivatives with fatty acids (myristic and stearic acids) present a strongly interaction with the DMPC bilayer due to the nucleoside and aliphatic chains parts which are oriented towards the polar and lipophilic phases of the phospholipidic bilayer, respectively. However, the effects caused by the tri-myristoyl uridine and tri-stearoyl uridine are different.

CONCLUSIONS

We show how the structural changes of uridine modulate the calorimetric behaviour of DMPC shedding light on their affinity with the phospholipidic biomembrane model.

Synthesis and interaction of sterol-uridine conjugate with DMPC liposomes studied by differential scanning calorimetry

Differential scanning calorimetry (DSC) is a thermoanalytical technique which provides information on the interaction between drugs and models of cell membranes. Studies on the calorimetric behavior of hydrated phospholipids within liposomes are employed to shed light on the changes in the physico-chemical properties when interacting with drugs. In this report, new potential anti-cancer drugs such as uridine and uridine derivatives (acetonide and its succinate), 3β-5α,8α-endoperoxide-cholestan-6-en-3-ol (5,8-epidioxicholesterol) and conjugate (uridine acetonide-epidioxicholesterol succinate) have been synthesized. Steglich esterification method using coupling agents allowed to obtain the uridine acetonide-sterol conjugate. The study on the interaction between the drugs and dimiristoyl-phophatidilcholine (DMPC) liposomes has been conducted by the use of DSC. The analysis of the DSC curves indicated that the uridine and derivatives (acetonide and its succinate) present a very soft interaction with the DMPC liposomes, whereas the 5,8-epidioxicholesterol and the conjugate showed a strong effect on the thermotropic behavior. Our results suggested that the lipophilic character of uridine acetonide-sterol conjugate improves the affinity with the DMPC liposomes.