An adipo-biliary-uridine axis that regulates energy homeostasis

Multi-omics correlates of insulin resistance and circadian parameters mapped directly from human serum

While it is generally known that metabolic disorders and circadian dysfunction are intertwined, how the two systems affect each other is not well understood, nor are the genetic factors that might exacerbate this pathological interaction. Blood chemistry is profoundly changed in metabolic disorders, and we have previously shown that serum factors change cellular clock properties. To investigate if circulating factors altered in metabolic disorders have circadian modifying effects, and whether these effects are of genetic origin, we measured circadian rhythms in U2OS cell in the presence of serum collected from diabetic, obese or control subjects. We observed that circadian period lengthening in U2OS cells was associated with serum chemistry that is characteristic of insulin resistance. Characterizing the genetic variants that altered circadian period length by genome-wide association analysis, we found that one of the top variants mapped to the E3 ubiquitin ligase MARCH1 involved in insulin sensitivity. Confirming our data, the serum circadian modifying variants were also enriched in type 2 diabetes and chronotype variants identified in the UK Biobank cohort. Finally, to identify serum factors that might be involved in period lengthening, we performed detailed metabolomics and found that the circadian modifying variants are particularly associated with branched chain amino acids, whose levels are known to correlate with diabetes and insulin resistance. Overall, our multi-omics data showed comprehensively that systemic factors serve as a path through which metabolic disorders influence circadian system, and these can be examined in human populations directly by simple cellular assays in common cultured cells.

Comparative analysis of bile acid composition and metabolism in the liver of Bufo gargarizans aquatic larvae and terrestrial adults

Bile acids are crucial for lipid metabolism and their composition and metabolism differ among species. However, there have been no data on the differences in the composition and metabolism of bile acids between aquatic larvae and terrestrial adults of amphibians. This study explored the differences in composition and metabolism of bile acid between Bufo gargarizans larvae and adults. The results demonstrated that adult liver had a lower total bile acid level and a higher conjugated/total bile acid ratio than larval liver. Meanwhile, histological analysis revealed that the larvae showed a larger cross-sectional area of bile canaliculi lumen compared with the adults. The transcriptomic analysis showed that B. gargarizans larvae synthesized bile acids through both the alternative and the 24-hydroxylase pathway, while adults only synthesized bile acids through the 24-hydroxylase pathway. Moreover, bile acid regulator-related genes FXR and RXRα were highly expressed in adult, whereas genes involved in bile acid synthesis (CYP27A1 and CYP46A1) were highly expressed in larvae. The present study will provide valuable insights into understanding metabolic disorders and exploring novel bile acid-based therapeutics.

A mendelian randomization study investigating the causal relationships between 1400 serum metabolites and autoimmune diseases

Objective

This study aims to explore the causal relationships between 1400 serum metabolites (SMs) and five autoimmune diseases (Myasthenia gravis [MG], Multiple sclerosis [MS], Systemic lupus erythematosus [SLE], Type 1 diabetes mellitus [T1DM], and Ulcerative colitis [UC]) through Mendelian randomization analysis.

Method

Data on MG, MS, SLE, T1DM, and UC were obtained from the IEU OpenGWAS Project database, while information on 1400 SMs was extracted from GWAS summary statistics provided by Chen et al. Causal relationships were assessed using the inverse variance weighted (IVW), MR-Egger, Weighted Median (WME), and Simple median (SME) methods. The robustness of instrumental variables was verified through computation of the F-statistic. Heterogeneity was evaluated using Cochran's Q test and the leave-one-out (LOO) method. Horizontal pleiotropy was assessed using MR-Egger regression and MR-PRESSO.

Result

Following correction of the IVW P values using the False Discovery Rate (FDR) method, it was found that increased levels of 5-methyluridine (ribothymidine) (OR = 1.191, 95%CI 1.086-1.307, FDR-P = 0.000) and 2'-deoxyuridine (OR = 1.337, 95%CI 1.127-1.586, FDR-P = 0.001) were found to be correlated with a higher risk of MS. Conversely, the ratio of S-adenosylhomocysteine (SAH) to 5-methyluridine (ribothymidine) (OR = 0.771, 95%CI 0.649-0.916, FDR-P = 0.007) was linked to a decreased risk of MS. Levels of 1,2-dilinoleoyl-GPE (18:2/18:2) (OR = 0.877, 95%CI 0.791-0.974, FDR-P = 0.003) appear to be a protective factor for T1DM. No notable correlations between SMs and MG, SLE, or UC. The study detected no heterogeneity or horizontal pleiotropy.

Conclusion

Levels of 5-methyluridine (ribothymidine), 2'-deoxyuridine, and the ratio of S-adenosylhomocysteine (SAH) to 5-methyluridine (ribothymidine) can serve as predictors for MS. Similarly, 1,2-dilinoleoyl-GPE (18:2/18:2) levels can be used to predict T1DM. However, no significant causal relationships were found between SMs and MG, SLE, or UC. This observation holds significant clinical implications for crafting tailored preventive and therapeutic approaches for ADs.

Untargeted metabolomics reveal signatures of a healthy lifestyle

This cross-sectional study investigated differences in the plasma metabolome in two groups of adults that were of similar age but varied markedly in body composition and dietary and physical activity patterns. Study participants included 52 adults in the lifestyle group (LIFE) (28 males, 24 females) and 52 in the control group (CON) (27 males, 25 females). The results using an extensive untargeted ultra high-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) metabolomics analysis with 10,535 metabolite peaks identified 486 important metabolites (variable influence on projections scores of VIP ≥ 1) and 16 significantly enriched metabolic pathways that differentiated LIFE and CON groups. A novel metabolite signature of positive lifestyle habits emerged from this analysis highlighted by lower plasma levels of numerous bile acids, an amino acid profile characterized by higher histidine and lower glutamic acid, glutamine, β-alanine, phenylalanine, tyrosine, and proline, an elevated vitamin D status, higher levels of beneficial fatty acids and gut microbiome catabolism metabolites from plant substrates, and reduced levels of N-glycan degradation metabolites and environmental contaminants. This study established that the plasma metabolome is strongly associated with body composition and lifestyle habits. The robust lifestyle metabolite signature identified in this study is consistent with an improved life expectancy and a reduced risk for chronic disease.

Effects of Maternal Dietary Enteromorpha prolifera Polysaccharide Iron Supplement on Mineral Elements and Iron Level of Neonatal Piglets

Iron plays a key role in maternal health during pregnancy and fetal growth. Enteromorpha polysaccharide-iron (EP-Fe) as an organic iron chelate may improve the iron transmission of mother and offspring, ameliorate the poor pregnancy outcomes of sows, and alleviate the growth restriction of piglets caused by iron deficiency. This study aimed to evaluate the effects of maternal dietary supplementation with EP-Fe on reproductive performance and placental iron transmission of sows, as well as growth performance of piglets. Sixty pregnant sows at the 95th day of gestation were randomly divided into control group and EP-Fe group (EP-Fe, 139 mg kg-1). Blood samples of sows and neonatal piglets, colostrum, and tissue samples were collected on the day of delivery. The animal experiment ended at the 21st day of post-delivery. Results showed that maternal dietary EP-Fe increased colostrum iron (P < 0.05) of sows, as well as final litter weight (P < 0.05) and average daily weight of piglets (P < 0.05) during days 1-21 of lactation, as well as iron and manganese content in umbilical cord blood (P < 0.05) and hepatic iron of neonatal piglets (P < 0.01), and decreased fecal iron (P < 0.001), serum calcium (P < 0.05), phosphorus (P < 0.05), and zinc (P < 0.01) in the parturient sow. RT-qPCR results showed that Fpn1 and Zip14 in placenta, as well as TfR1 and Zip14 in duodenum of neonatal piglets, were activated by maternal EP-Fe supplement. These findings suggest that maternal dietary EP-Fe could increase iron storage of neonatal piglets via improving placental iron transport and iron secretion in colostrum, thus enhancing the growth performance of sucking piglets.

The predictive value of plasma uridine for type 2 diabetes and its atherosclerotic complications

Objective

Uridine might be a common link between pathological pathways in diabetes and cardiovascular diseases. This study aimed to investigate the predictive value of plasma uridine for type 2 diabetes (T2D) and T2D with atherosclerosis.

Methods

Individuals with T2D and healthy controls (n = 218) were randomly enrolled in a cross-sectional study. Patients with T2D were divided into two groups based on carotid ultrasound: patients with carotid atherosclerosis (CA) (group DCA) and patients without CA (group D). Plasma uridine was determined using HPLC-MS/MS. Correlation and logistic regression analyses were used to analyze the results.

Results

Fasting and postprandial uridine were significantly increased in patients with T2D compared with healthy individuals. Logistic regression suggested that fasting and postprandial uridine were independent risk factors for T2D. The receiver operating characteristic (ROC) curve showed that fasting uridine had a predictive value on T2D (95% CI, 0.686-0.863, sensitivity 74.3%, specificity 71.8%). Fasting uridine was positively correlated with LDL-c, FBG, and PBG and negatively correlated with fasting C-peptide (CP-0h) and HOMA-IS. The change in postprandial uridine from fasting baseline (Δuridine) was smaller in T2D patients with CA compared with those without (0.80 (0.04-2.46) vs 2.01 (0.49-3.15), P = 0.010). Δuridine was also associated with T2D with CA and negatively correlated with BMI, CP-0h, and HOMA-IR.

Conclusion

Fasting uridine has potential as a predictor of diabetes. Δuridine is closely associated with carotid atherosclerosis in patients with T2D.

Nucleosides are overlooked fuels in central carbon metabolism

From our daily nutrition and synthesis within cells, nucleosides enter the bloodstream and circulate throughout the body and tissues. Nucleosides and nucleotides are classically viewed as precursors of nucleic acids, but recently they have emerged as a novel energy source for central carbon metabolism. Through catabolism by nucleoside phosphorylases, the ribose sugar group is released and can provide substrates for lower steps in glycolysis. In environments with limited glucose, such as at sites of infection or in the tumor microenvironment (TME), cells can use, and may even require, this alternative energy source. Here, we discuss the implications of these new findings in health and disease and speculate on the potential new roles of nucleosides and nucleic acids in energy metabolism.

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.

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.

N-acetylaspartate from fat cells regulates postprandial body temperature

N-acetylaspartate (NAA), the brain's second most abundant metabolite, provides essential substrates for myelination through its hydrolysis. However, activities and physiological roles of NAA in other tissues remain unknown. Here, we show aspartoacylase (ASPA) expression in white adipose tissue (WAT) governs systemic NAA levels for postprandial body temperature regulation. Proteomics and mass spectrometry revealed NAA accumulation in WAT of Aspa knockout mice stimulated the pentose phosphate pathway and pyrimidine production. Stable isotope tracing confirmed higher incorporation of glucose-derived carbon into pyrimidine metabolites in Aspa knockout cells. Additionally, serum NAA positively correlates with the pyrimidine intermediate orotidine and this relationship predicted lower body mass index in humans. Using whole-body and tissue-specific knockout mouse models, we demonstrate that fat cells provided plasma NAA and suppressed postprandial body temperature elevation. Furthermore, exogenous NAA supplementation reduced body temperature. Our study unveils WAT-derived NAA as an endocrine regulator of postprandial body temperature and physiological homeostasis.

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.

Characteristics of Transcriptome and Metabolome Concerning Intramuscular Fat Content in Beijing Black Pigs

To study the characteristics of genes and metabolites related to intramuscular fat (IMF) content with less influence by breed background and individual differences, the skeletal muscle samples from 40 Beijing black pigs with either high or low IMF content were used to perform transcriptome and metabolome analyses. About 99 genes (twofold-change) were differentially expressed. Up-regulated genes in the high IMF pigs were mainly related to fat metabolism. The key genes in charge of IMF deposition are ADIPOQ, CIDEC, CYP4B1, DGAT2, LEP, OPRL1, PLIN1, SCD, and THRSP. KLHL40, TRAFD1, and HSPA6 were novel candidate genes for the IMF trait due to their high abundances. In the low IMF pigs, the differentially expressed genes involved in virus resistance were up-regulated. About 16 and 18 differential metabolites (1.5 fold-change) were obtained in the positive and negative modes, respectively. Pigs with low IMF had weaker fatty acid oxidation due to the down-regulation of various carnitines. Differentially expressed genes were more important in determining IMF deposition than differential metabolites because relatively few differential metabolites were obtained, and they were merely the products under the physiological status of diverged IMF content. This study provided valuable information for further studies on IMF deposition.

Liver mitochondrial cristae organizing protein MIC19 promotes energy expenditure and pedestrian locomotion by altering nucleotide metabolism

Liver mitochondria undergo architectural remodeling that maintains energy homeostasis in response to feeding and fasting. However, the specific components and molecular mechanisms driving these changes and their impact on energy metabolism remain unclear. Through comparative mouse proteomics, we found that fasting induces strain-specific mitochondrial cristae formation in the liver by upregulating MIC19, a subunit of the MICOS complex. Enforced MIC19 expression in the liver promotes cristae formation, mitochondrial respiration, and fatty acid oxidation while suppressing gluconeogenesis. Mice overexpressing hepatic MIC19 show resistance to diet-induced obesity and improved glucose homeostasis. Interestingly, MIC19 overexpressing mice exhibit elevated energy expenditure and increased pedestrian locomotion. Metabolite profiling revealed that uracil accumulates in the livers of these mice due to increased uridine phosphorylase UPP2 activity. Furthermore, uracil-supplemented diet increases locomotion in wild-type mice. Thus, MIC19-induced mitochondrial cristae formation in the liver increases uracil as a signal to promote locomotion, with protective effects against diet-induced obesity.

N-arachidonylglycine is a caloric state-dependent circulating metabolite which regulates human CD4+T cell responsiveness

Caloric deprivation interventions such as intermittent fasting and caloric restriction ameliorate metabolic and inflammatory disease. As a human model of caloric deprivation, a 24-h fast blunts innate and adaptive immune cell responsiveness relative to the refed state. Isolated serum at these time points confers these same immunomodulatory effects on transformed cell lines. To identify serum mediators orchestrating this, metabolomic and lipidomic analysis was performed on serum extracted after a 24-h fast and re-feeding. Bioinformatic integration with concurrent peripheral blood mononuclear cells RNA-seq analysis implicated key metabolite-sensing GPCRs in fasting-mediated immunomodulation. The putative GPR18 ligand N-arachidonylglycine (NAGly) was elevated during fasting and attenuated CD4⁺T cell responsiveness via GPR18 MTORC1 signaling. In parallel, NAGly reduced inflammatory Th1 and Th17 cytokines levels in CD4⁺T cells isolated from obese subjects, identifying a fasting-responsive metabolic intermediate that may contribute to the regulation of nutrient-level dependent inflammation associated with metabolic disease.

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.

N-carbamoyl aspartate reduced body weight by stimulating the thermogenesis of iBAT

Uridine has formerly been shown to alleviate obesity and hepatic lipid accumulation. N-carbamoyl aspartate (NCA) provides carbon atoms to uridine in de novo pyrimidine biosynthesis pathway. However, whether NCA is involved in the lipid metabolism remains elusive. Here we showed that NCA supplementation significantly decreased (P < 0.05) serum cholesterol (CHOL), high-density lipoprotein (HDL), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) levels of mice, and significantly increased (P < 0.05) relative mRNA expression of genes related to the synthesis of pyrimidine nucleotides and polyunsaturated fatty acids. Besides, supplemented with NCA significantly decreased body weight and area under the curve (AUC), and increased body temperature in the high-fat diet fed mice. For further, relative protein expression of uridine monophosphate synthase (UMPS), sterol regulatory element-binding protein 1(SREBP-1) and phosphorylated hormone-sensitive triglyceride lipase (P-HSL) in the liver, and uncoupling protein 1 (UCP-1) in interscapular brown adipose tissue (iBAT) also showed upregulated in the high-fat diet fed mice. Thus, NCA promoted de novo synthesis of pyrimidine and polyunsaturated fatty acid, and reduced body weight by stimulating high-fat diet-induced thermogenesis of iBAT.

Cytidine Alleviates Dyslipidemia and Modulates the Gut Microbiota Composition in ob/ob Mice

Cytidine and uridine are endogenous metabolites in the pyrimidine metabolism pathway, and cytidine is a substrate that can be metabolized into uridine via cytidine deaminase. Uridine has been widely reported to be effective in regulating lipid metabolism. However, whether cytidine could ameliorate lipid metabolism disorder has not yet been investigated. In this research, ob/ob mice were used, and the effect of cytidine (0.4 mg/mL in drinking water for five weeks) on lipid metabolism disorder was evaluated in terms of an oral glucose tolerance test, serum lipid levels, liver histopathological analysis and gut microbiome analysis. Uridine was used as a positive control. Our findings reveal that cytidine could alleviate certain aspects of dyslipidemia and improve hepatic steatosis via modulating the gut microbiota composition in ob/ob mice, especially increasing the abundance of short-chain fatty acids-producing microbiota. These results suggest that cytidine supplementation could be a potential therapeutic approach for dyslipidemia.

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.

Ramadan diurnal intermittent fasting is associated with significant plasma metabolomics changes in subjects with overweight and obesity: A prospective cohort study

Introduction

During the holy month of Ramadan, adult healthy Muslims are mandated to abstain from dawn to sunset, with free eating at night hours that may extend up to 12 h. The current work was designed to investigate the metabolomics changes incurred upon the observance of Ramadan diurnal intermittent fasting (RDIF).

Methods

Twenty-five metabolically healthy participants with overweight and obesity (7 females and 18 males, with a mean age of 39.48 ± 10.0 years) were recruited for the study and were followed before and at the end of RDIF month. Dietary, anthropometric, biochemical, and physical activity assessments were performed before and at the end of the fasting month. The metabolomic assay was performed using liquid chromatography-mass spectrometry for the two-time points.

Results and discussion

Metabolomics assay revealed a significant reduction in a few metabolites. The analysis revealed that 27 metabolites differed significantly (P < 0.05) between pre-and post-RDIF. Among the differentially abundant metabolites, 23 showed a decrease with fasting, these included several amino acids such as aspartame, tryptophan, phenylalanine, histidine, and other metabolites including valeric acid, and cortisol. On the other hand, only four metabolites showed increased levels after RDIF including traumatic acid, 2-pyrrolidinone, PC[18:1(9Z)/18:1(9Z)], and L-sorbose. The MetaboAnalyst^® platform reported that the top enriched metabolic pathways included: (1) histidine metabolism; (2) folate biosynthesis (3) phenylalanine, tyrosine, and tryptophan biosynthesis; (4) aminoacyltRNA biosynthesis; (5) caffeine metabolism; (6) vitamin B₆ metabolism; and several other pathways relating to lipid metabolisms such as arachidonic acid metabolism, glycerophospholipid metabolism, and linoleic acid metabolism. In conclusion, RDIF entails significant changes in various metabolic pathways that reflect different dietary and lifestyle behaviors practiced during the fasting month.

Proof-of-principle studies on a strategy to enhance nucleotide imbalance specifically in cancer cells

Highly specific and potent inhibitors of dihydroorotate dehydrogenase (DHODH), an essential enzyme of the de novo pyrimidine ribonucleotide synthesis pathway, are in clinical trials for autoimmune diseases, viral infections and cancer. However, because DHODH inhibitors (DHODHi) are immunosuppressants they may reduce the anticancer activity of the immune system. Therefore, there may be a need to improve the therapeutic index of DHODHi in cancer patients. The aim of this study was to find strategies to protect activated T cells from DHODHi and to identify cancer types hypersensitive to these inhibitors. First, we observed that like uridine supplementation, adding cytidine to the culture medium protects T cells from DHODH blockage. Next, we identified tumor types with altered expression of pyrimidine ribonucleotide synthesis enzymes. In this regard, we detected that the expression of cytidine deaminase (CDA), which converts cytidine into uridine, is low in an important proportion of cancer cell lines and consistently low in neuroblastoma samples and in cell lines from neuroblastoma and small cell lung carcinoma. This suggested that in the presence of a DHODHi, an excess of cytidine would be deleterious for low CDA expressing cancer cell lines. We show that this was the case (as could be seen almost immediately after treatment) when cells were cultured with fetal bovine serum but, was significantly less evident when cultures contained human serum. One interesting feature of CDA is that aside from acting intracellularly, it is also present in human plasma/serum. Altogether, experiments using recombinant CDA, human serum, pharmacologic inhibition of CDA and T cell/cancer cell co-cultures suggest that the therapeutic index of DHODHi could be improved by selecting patients with low-CDA expressing cancers in combination with strategies to increase cytidine or the cytidine/uridine ratio in the extracellular environment. Collectively, this proof-of-principle study warrants the discovery of agents to deplete extracellular CDA.

MLN4924 Treatment Diminishes Excessive Lipid Storage in High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease (NAFLD) by Stimulating Hepatic Mitochondrial Fatty Acid Oxidation and Lipid Metabolites

MLN4924 is a selective neddylation inhibitor that has shown great potential in treating several cancer and metabolic diseases, including obesity. However, it remains largely unknown whether MLN4924 has similar effect on non-alcoholic liver disease (NAFLD), which is closely associated with metabolic disorders. Here, we investigated the role of MLN4924 in NAFLD treatment and the underlying mechanism of the action using primary hepatocytes stimulated with free fatty acid, as well as high-fat diet (HFD)-induced NAFLD mouse models. We found that MLN4924 can inhibit the accumulation of lipid and reduce the expression of peroxisome proliferator-activated receptor γ (PPARγ), a key player in adipocyte differentiation and function in both in vivo and in vitro models. Moreover, we verified its important role in decreasing the synthesis and accumulation of fat in the liver, thus mitigating the development of NAFLD in the mouse model. The body weight and fat mass in MLN4924-treated animals were significantly reduced compared to the control group, while the metabolic activity, including O₂ consumption, CO₂ and heat production, also increased in these animals. Importantly, we demonstrated for the first time that MLN4924 can markedly boost mitochondrial fat acid oxidation (FAO) to alter liver lipid metabolism. Finally, we compared the metabolites between MLN4924-treated and untreated Huh7 cells after fatty acid induction using lipidomics methods and techniques. We found induction of several metabolites in the treated cells, including Beta-guanidinopropionic acid (b-GPA) and Fluphenazine, which was in accordance with the increase of FAO and metabolism. Together, our study provided a link between neddylation modification and energy metabolism, as well as evidence for targeting neddylation as an emerging therapeutic approach to tackle NAFLD.

Physicochemical properties calculated using DFT method and changes of 5-methyluridine hemihydrate crystals at high temperatures

5-methyluridine hemihydrate (5 mU) single crystals were synthesized by the slow solvent evaporation method. The physicochemical properties, such as frontier molecular orbitals, global reactivity indices and vibrational were computationally studied through density functional theory (DFT). In addition, structural, vibrational, and thermal properties were obtained by powder X-ray diffraction (PXRD), Raman spectroscopy, thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). PXRD evaluated the structural behavior of 5 mU crystal in the temperature range of 300-460 K. The high-temperature PXRD results suggested that the crystal undergoes two dehydration processes, being a first occurring from the orthorhombic structure (P2₁2₁2) to triclinic (P1), in which the water losses occurred around 380 K. A second dehydration triggers the change from the triclinic structure to monoclinic (P2₁) within the 420-435 K temperature range. Furthermore, after this temperature, the anhydrous 5 mU suffers a melting process near 460 K, which is remarkably characterized as an irreversible process. Raman spectroscopy was carried out to identify the vibrational modes linked to the water molecule and the noticeable changes in these bands due to high-temperature effects around 380 K and 410 K. Indeed, changes on Raman bands, such as intensity inversion, the disappearance of bands associated with the hydrogen bonds formed from the water molecules and uracil group, and the ribose group were observed. Finally, this study provided details on the structural and vibrational changes caused by the dehydration of 5 mU crystals and the importance of hydrogen bonds for understanding the intermolecular interactions of the 5 mU, a methylated nucleoside with important biological functions.

Metabolome-Wide Association Study of Multiple Plasma Metals with Serum Metabolomic Profile among Middle-to-Older-Aged Chinese Adults

Metal exposure has been associated with risk of various cardio-metabolic disorders, and investigation on the association between exposure to multiple metals and metabolic responses may reveal novel clues to the underlying mechanisms. Based on a metabolome-wide association study of 17 plasma metals with untargeted metabolomic profiling of 189 serum metabolites among 1992 participants within the Dongfeng-Tongji cohort, we replicated two metal-associated pathways, linoleic acid metabolism and aminoacyl-tRNA biosynthesis, with novel metal associations (false discovery rate, FDR < 0.05), and we also identified two novel pathways, including biosynthesis of unsaturated fatty acids and alpha-linolenic acid metabolism, as associated with metal exposure (FDR < 0.05). Moreover, two-way orthogonal partial least-squares analysis showed that five metabolites, including aspartylphenylalanine, free fatty acid 14:1, uridine, carnitine C14:2, and LPC 18:2, contributed most to the joint covariation between the two data matrices (12.3%, 8.3%, 8.0%, 7.4%, and 7.3%, respectively). Further BKMR analysis showed significant positive joint associations of plasma Al, As, Ba, and Zn with aspartylphenylalanine and of plasma Ba, Co, Mn, and Pb with carnitine C14:2, when all the metals were at the 55th percentiles or above, compared with the median. We also found significant interactions between As and Ba in the association with aspartylphenylalanine (P for interaction = 0.048) and between Ba and Pb in the association with carnitine C14:2 (P for interaction < 0.001). Together, these findings may provide new insights into the mechanisms underlying the adverse health effects induced by metal exposure.

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.

A nexus of lipid and O-Glcnac metabolism in physiology and disease

Although traditionally considered a glucose metabolism-associated modification, the O-linked β-N-Acetylglucosamine (O-GlcNAc) regulatory system interacts extensively with lipids and is required to maintain lipid homeostasis. The enzymes of O-GlcNAc cycling have molecular properties consistent with those expected of broad-spectrum environmental sensors. By direct protein-protein interactions and catalytic modification, O-GlcNAc cycling enzymes may provide both acute and long-term adaptation to stress and other environmental stimuli such as nutrient availability. Depending on the cell type, hyperlipidemia potentiates or depresses O-GlcNAc levels, sometimes biphasically, through a diversity of unique mechanisms that target UDP-GlcNAc synthesis and the availability, activity and substrate selectivity of the glycosylation enzymes, O-GlcNAc Transferase (OGT) and O-GlcNAcase (OGA). At the same time, OGT activity in multiple tissues has been implicated in the homeostatic regulation of systemic lipid uptake, storage and release. Hyperlipidemic patterns of O-GlcNAcylation in these cells are consistent with both transient physiological adaptation and feedback uninhibited obesogenic and metabolic dysregulation. In this review, we summarize the numerous interconnections between lipid and O-GlcNAc metabolism. These links provide insights into how the O-GlcNAc regulatory system may contribute to lipid-associated diseases including obesity and metabolic syndrome.

Uncovering the roles of dihydropyrimidine dehydrogenase in fatty-acid induced steatosis using human cellular models

Pyrimidine catabolism is implicated in hepatic steatosis. Dihydropyrimidine dehydrogenase (DPYD) is an enzyme responsible for uracil and thymine catabolism, and DPYD human genetic variability affects clinically observed toxicity following 5-Fluorouracil administration. In an in vitro model of fatty acid-induced steatosis, the pharmacologic inhibition of DPYD resulted in protection from lipid accumulation. Additionally, a gain-of-function mutation of DPYD, created through clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR-Cas9) engineering, led to an increased lipid burden, which was associated with altered mitochondrial functionality in a hepatocarcionma cell line. The studies presented herein describe a novel role for DPYD in hepatocyte metabolic regulation as a modulator of hepatic steatosis.

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.

Lactobacillus plantarum Ameliorates High-Carbohydrate Diet-Induced Hepatic Lipid Accumulation and Oxidative Stress by Upregulating Uridine Synthesis

The overconsumption of carbohydrates induces oxidative stress and lipid accumulation in the liver, which can be alleviated by modulation of intestinal microbiota; however, the underlying mechanism remains unclear. Here, we demonstrated that a strain affiliated with Lactobacillus plantarum (designed as MR1) efficiently attenuated lipid deposition, oxidative stress, as well as inflammatory response, which are caused by high-carbohydrate diet (HC) in fish with poor utilization ability of carbohydrates. Serum untargeted metabolome analysis indicated that pyrimidine metabolism was the significantly changed pathway among the groups. In addition, the content of serum uridine was significantly decreased in the HC group compared with the control group, while it increased by supplementation with L. plantarum MR1. Further analysis showed that addition of L. plantarum MR1 reshaped the composition of gut microbiota and increased the content of intestinal acetate. In vitro experiment showed that sodium acetate could induce the synthesis of uridine in hepatocytes. Furthermore, we proved that uridine could directly ameliorate oxidative stress and decrease liver lipid accumulation in the hepatocytes. In conclusion, this study indicated that probiotic L. plantarum MR1 ameliorated high-carbohydrate diet-induced hepatic lipid accumulation and oxidative stress by increasing the circulating uridine, suggesting that intestinal microbiota can regulate the metabolism of nucleotides to maintain host physiological homeostasis.

The comparison of nucleotide metabolites and amino acids patterns in patients with eating disorders, with and without symptoms of depression

Purines, pyrimidines, and amino acid level have gained attention recently as potential determinants of mental disorders. However, eating disorders patients (ED) have not been yet appropriately studied, especially subjects with coexisting mood disorders. This paper examines the serum level of nucleotide catabolites and plasma amino acids in eating disorders with hyperphagia, with and without Major Depressive Disorder (MDD). Samples were taken from adult persons suffering from eating disorders (two forms: simple obesity and binge eating disorder) with MDD (n = 20) and without (n = 17). Serum nucleotides and plasma amino acids concentrations were analyzed with high-performance liquid chromatography-mass spectrometry. The nucleotides metabolite in MDD patients had a significantly (p < 0.05) lower uridine. Among MDD patients with ED significantly (p < 0.05) higher levels of asparagine, glutamine, proline, and arginine were found as compared to the control group. This study demonstrated differences in nucleotide metabolite and amino acid pattern in depression patients with eating disorders. This may be relevant to the mechanisms and may help identify biomarkers.

Adipocyte purinergic receptors activated by uracil nucleotides as obesity and type 2 diabetes targets

Extracellular uridine nucleotides regulate physiological and pathophysiological metabolic processes through the activation of P2Y₂, P2Y₄, P2Y₆ and P2Y₁₄ purinergic receptors, which play a key role in adipogenesis, glucose uptake, lipolysis and adipokine secretion. Using adipocyte-specific knockout mouse models, it has been demonstrated that lack of the P2Y₆R or P2Y₁₄R can protect against diet-induced obesity and improve whole-body glucose metabolism. The P2Y₂R facilitated adipogenesis and inflammation, and the loss of P2Y₄R or P2Y₁₄R raised the levels of the protective endocrine factor adiponectin. Hence, potent antagonists for these receptors may be tested to identify drug candidates for the treatment of obesity and type 2 diabetes. However, future studies are required to provide insight into purinergic regulation of brown adipocytes and their role in thermogenesis. This review summarizes the current studies on uridine nucleotide-activated P2YRs and their role in adipocyte function, diet-induced obesity and associated metabolic deficits.

Acclimations to Cold and Warm Conditions Differently Affect the Energy Metabolism of Diapausing Larvae of the European Corn Borer Ostrinia nubilalis (Hbn.)

The European corn borer Ostrinia nubilalis is a pest species, whose fifth instar larvae gradually develop cold hardiness during diapause. The physiological changes underlying diapause progression and cold hardiness development are still insufficiently understood in insects. Here, we follow a complex of changes related to energy metabolism during cold acclimation (5°C) of diapausing larvae and compare this to warm-acclimated (22°C) and non-diapause controls. Capillary electrophoresis of nucleotides and coenzymes has shown that in gradually cold-acclimated groups concentrations of ATP/ADP and, consequently, energy charge slowly decrease during diapause, while the concentration of AMP increases, especially in the first months of diapause. Also, the activity of cytochrome c oxidase (COX), as well as the concentrations of NAD+ and GMP, decline in cold-acclimated groups, until the latter part of diapause, when they recover. Relative expression of NADH dehydrogenase (nd1), coenzyme Q-cytochrome c reductase (uqcr), COX, ATP synthase (atp), ADP/ATP translocase (ant), and prohibitin 2 (phb2) is supressed in cold-acclimated larvae during the first months of diapause and gradually increases toward the termination of diapause. Contrary to this, NADP+ and UMP levels significantly increased in the first few months of diapause, after gradual cold acclimation, which is in connection with the biosynthesis of cryoprotective molecules, as well as regeneration of small antioxidants. Our findings evidence the existence of a cold-induced energy-saving program that facilitates long-term maintenance of larval diapause, as well as gradual development of cold hardiness. In contrast, warm acclimation induced faster depletion of ATP, ADP, UMP, NAD+, and NADP+, as well as higher activity of COX and generally higher expression of all energy-related genes in comparison to cold-acclimated larvae. Moreover, such unusually high metabolic activity, driven by high temperatures, lead to premature mortality in the warm-acclimated group after 2 months of diapause. Thus, our findings strongly support the importance of low temperature exposure in early diapause for gradual cold hardiness acquisition, successful maintenance of the resting state and return to active development. Moreover, they demonstrate potentially adverse effects of global climate changes and subsequent increase in winter temperatures on cold-adapted terrestrial organisms in temperate and subpolar regions.

AgRP neuronal activity across feeding-related behaviours

AgRP neurons trigger one of the most potent orexigenic responses and are both necessary and sufficient for feeding. Recent technical advances for monitoring in vivo neuronal activity have revisited a previously well-established model of AgRP neurons' feeding regulatory effects. Our current understanding of AgRP neurons has increased in complexity and revealed a fine-tuned regulation of their activity dynamics across the whole sequence of feeding-related behaviours. This review focuses on recent studies that refined and re-evaluated our understanding of the regulatory principles and behavioural effects of AgRP circuits. We aim to cover major discoveries on the dynamic regulation of AgRP neuronal activity by exteroceptive and interoceptive food-related cues, their pleiotropic effects in feeding and whole-body homeostasis, and the associated AgRP circuits. The function and regulation of AgRP neuron will be sequentially discussed across the temporal series of behavioural and physiological changes occurring during the appetitive (food craving and foraging), the anticipatory (discovery of food-predicting cues), and the consummatory/post-ingestive phase of feeding (calorie ingestion).

The Adipokine Component in the Molecular Regulation of Cancer Cell Survival, Proliferation and Metastasis

A hormonal imbalance may disrupt the rigorously monitored cellular microenvironment by hampering the natural homeostatic mechanisms. The most common example of such hormonal glitch could be seen in obesity where the uprise in adipokine levels is in virtue of the expanding bulk of adipose tissue. Such aberrant endocrine signaling disrupts the regulation of cellular fate, rendering the cells to live in a tumor supportive microenvironment. Previously, it was believed that the adipokines support cancer proliferation and metastasis with no direct involvement in neoplastic transformations and tumorigenesis. However, the recent studies have reported discrete mechanisms that establish the direct involvement of adipokine signaling in tumorigenesis. Moreover, the individual adipokine profile of the patients has never been considered in the prognosis and staging of the disease. Hence, the present manuscript has focused on the reported extensive mechanisms that culminate the basis of poor prognosis and diminished survival rate in obese cancer patients.

Amyotrophic lateral sclerosis alters the metabolic aging profile in patient derived fibroblasts

Aging is a major risk factor for neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). As metabolic alterations are a hallmark of aging and have previously been observed in ALS, it is important to examine the effect of aging in the context of ALS metabolic function. Here, using a newly established phenotypic metabolic approach, we examined the effect of aging on the metabolic profile of fibroblasts derived from ALS cases compared to controls. We found that ALS fibroblasts have an altered metabolic profile, which is influenced by age. In control cases, we found significant increases with age in NADH metabolism in the presence of several metabolites including lactic acid, trehalose, uridine and fructose, which was not recapitulated in ALS cases. Conversely, we found a reduction of NADH metabolism with age of biopsy, age of onset and age of death in the presence of glycogen in the ALS cohort. Furthermore, we found that NADH production correlated with disease progression rates in relation to a number of metabolites including inosine and α-ketoglutaric acid. Inosine or α-ketoglutaric acid supplementation in ALS fibroblasts was bioenergetically favourable. Overall, we found aging related defects in energy substrates that feed carbon into glycolysis at various points as well as the tricarboxylic acid (TCA) cycle in ALS fibroblasts, which was validated in induced neuronal progenitor cell derived iAstrocytes. Our results suggest that supplementing those pathways may protect against age related metabolic dysfunction in ALS.

Therapeutic targeting of both dihydroorotate dehydrogenase and nucleoside transport in MYCN-amplified neuroblastoma

Metabolic reprogramming is an integral part of the growth-promoting program driven by the MYC family of oncogenes. However, this reprogramming also imposes metabolic dependencies that could be exploited therapeutically. Here we report that the pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase (DHODH) is an attractive therapeutic target for MYCN-amplified neuroblastoma, a childhood cancer with poor prognosis. Gene expression profiling and metabolomic analysis reveal that MYCN promotes pyrimidine nucleotide production by transcriptional upregulation of DHODH and other enzymes of the pyrimidine-synthesis pathway. Genetic and pharmacological inhibition of DHODH suppresses the proliferation and tumorigenicity of MYCN-amplified neuroblastoma cell lines. Furthermore, we obtain evidence suggesting that serum uridine is a key factor in determining the efficacy of therapeutic agents that target DHODH. In the presence of physiological concentrations of uridine, neuroblastoma cell lines are highly resistant to DHODH inhibition. This uridine-dependent resistance to DHODH inhibitors can be abrogated by dipyridamole, an FDA-approved drug that blocks nucleoside transport. Importantly, dipyridamole synergizes with DHODH inhibition to suppress neuroblastoma growth in animal models. These findings suggest that a combination of targeting DHODH and nucleoside transport is a promising strategy to overcome intrinsic resistance to DHODH-based cancer therapeutics.

Maternal yeast-based nucleotide supplementation decreased stillbirth by regulating nutrient metabolism

BACKGROUND

As an enzymatic product of yeast, yeast-based nucleotide (YN) is rich in nucleotides. To test the effects of maternal dietary supplementation with YN during late pregnancy on placental nutrient transport and nutrient metabolism in neonatal piglets, 64 pregnant sows (day 85 ± 3) were assigned into two groups: (i) control (CON) and (ii) treatment (YN; 4 g kg^-1 ). Blood, placenta and liver samples of neonates during delivery were collected.

RESULTS

The results showed that maternal YN supplementation decreased stillbirth rate and intra-uterine growth restriction rate (P < 0.05). In addition, maternal YN supplementation increased total serum protein, albumin and total cholesterol (P < 0.05). Furthermore, in neonatal piglets in the YN group, both serum amino acidand nucleotide profiles were affected, as well as liver amino acid, and fatty acid profiles were regulated (P < 0.05). Moreover, maternal YN supplementation increased liver mRNA expression of SLC28A3, SLC29A1, SLC29A2, PC, PCK1, FBP1, SREBP1c, HSL and CYP7a1 of neonatal piglets (P < 0.05). Meanwhile, there was a decrease in placental gene expression of EAAT2, EAAT3, LAT1 and PAT1, as well as lower protein expression of peroxisome proliferator-activated receptor (PPAR)γ, AKT, phosphorylated-AKT, phosphorylated-mammalian target of rapamycin (mTOR) and Raptor, in the YN group (P < 0.05).

CONCLUSION

Taken together, these results indicate that maternal YN supplementation regulates placental nutrient transport by regulating the mTOR complex 1-PPAR pathway, and affects the liver metabolism of nucleotides, amino acids and fatty acids in neonatal piglets, thereby improving the reproductive performance of sow to a certain extent. © 2020 Society of Chemical Industry.

Proteostasis in thermogenesis and obesity

The proper production, degradation, folding and activity of proteins, proteostasis, is essential for any cellular function. From single cell organisms to humans, selective pressures have led to the evolution of adaptive programs that ensure proteins are properly produced and disposed of when necessary. Environmental factors such as temperature, nutrient availability, pathogens as well as predators have greatly influenced the development of mechanisms such as the unfolded protein response, endoplasmic reticulum-associated protein degradation and autophagy, working together in concert to secure cellular proteostasis. In our modern society, the metabolic systems of the human body face the distinct challenge of changed diets, chronic overnutrition and sedentary lifestyles. Obesity and excess white adipose tissue accumulation are linked to a cluster of metabolic diseases and disturbed proteostasis is a common feature. Conversely, processes that promote energy expenditure such as exercise, shivering as well as non-shivering thermogenesis by brown adipose tissue (BAT) and beige adipocytes counteract metabolic dysfunction. Here we review the basic concepts of proteostasis in obesity-linked metabolic diseases and focus on adipocytes, which are critical regulators of mammalian energy metabolism.

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.

Human Safety, Tolerability, and Pharmacokinetics of Molnupiravir, a Novel Broad-Spectrum Oral Antiviral Agent with Activity Against SARS-CoV-2

Molnupiravir, EIDD-2801/MK-4482, the prodrug of the active antiviral ribonucleoside analog ß-d-N4-hydroxycytidine (NHC; EIDD-1931), has activity against a number of RNA viruses including severe acute respiratory syndrome coronavirus 2, severe acute respiratory syndrome coronavirus, Middle East respiratory syndrome coronavirus, and seasonal and pandemic influenza viruses.Single and multiple doses of molnupiravir were evaluated in this first-in-human, phase 1, randomized, double-blind, placebo-controlled study in healthy volunteers, which included evaluation of the effect of food on pharmacokinetics.EIDD-1931 appeared rapidly in plasma, with a median time of maximum observed concentration of 1.00 to 1.75 hours, and declined with a geometric half-life of approximately 1 hour, with a slower elimination phase apparent following multiple doses or higher single doses (7.1 hours at the highest dose tested). Mean maximum observed concentration and area under the concentration versus time curve increased in a dose-proportional manner, and there was no accumulation following multiple doses. When administered in a fed state, there was a decrease in the rate of absorption, but no decrease in overall exposure.Molnupiravir was well tolerated. Fewer than half of subjects reported an adverse event, the incidence of adverse events was higher following administration of placebo, and 93.3% of adverse events were mild. One discontinued early due to rash. There were no serious adverse events and there were no clinically significant findings in clinical laboratory, vital signs, or electrocardiography. Plasma exposures exceeded expected efficacious doses based on scaling from animal models; therefore, dose escalations were discontinued before a maximum tolerated dose was reached.

Yeast-based nucleotide supplementation in mother sows modifies the intestinal barrier function and immune response of neonatal pigs

In the present study, we aimed to evaluate the effects of maternal yeast-based nucleotide (YN) supplementation on the intestinal immune response and barrier function in neonatal pigs, as well as the diarrhoea rate and growth performance in suckling piglets. Sixty-four late-gestation sows were assigned to the following groups: the CON (fed a basal diet) and YN groups (fed a basal diet with 4 g YN/kg diet). The experiment started on d 85 of gestation and ended on d 20 of lactation. Diarrhoea rate and average daily gain of the piglets were recorded, and samples of blood and intestines from neonatal piglets were collected before they consumed colostrum during farrowing. Compared with the CON group, maternal YN supplementation increased the weaning weight of litter and decreased the diarrhoea rate (P < 0.01). In addition, maternal YN supplementation promoted the ileal villus development in the neonates compared with that in the CON group (P < 0.01). Maternal YN supplementation also increased the ileal secretory immunoglobulin A (sIgA) level compared with that in the CON group (P < 0.05). The real-time PCR results showed that maternal dietary YN supplementation increased the jejunal and ileal expression of interleukin (IL)-17, IL-8, IL-1β, IL-10 and tumor necrosis factor (TNF)- α in the neonates compared with that in the CON group (P < 0.05). Overall, maternal nucleotide supplementation improved the villus development and innate immunity of neonatal piglets during late pregnancy. This may be associated with the decrease in diarrhoea and the increase in weaning weight of the litter of suckling piglets.

The Circadian Physiology: Implications in Livestock Health

Circadian rhythms exist in almost all types of cells in mammals. Thousands of genes exhibit approximately 24 h oscillations in their expression levels, making the circadian clock a crucial regulator of their normal functioning. In this regard, environmental factors to which internal physiological processes are synchronized (e.g., nutrition, feeding/eating patterns, timing and light exposure), become critical to optimize animal physiology, both by managing energy use and by realigning the incompatible processes. Once the circadian clock is disrupted, animals will face the increased risks of diseases, especially metabolic phenotypes. However, little is known about the molecular components of these clocks in domestic species and by which they respond to external stimuli. Here we review evidence for rhythmic control of livestock production and summarize the associated physiological functions, and the molecular mechanisms of the circadian regulation in pig, sheep and cattle. Identification of environmental and physiological inputs that affect circadian gene expressions will help development of novel targets and the corresponding approaches to optimize production efficiency in farm animals.

Brown Fat-Activating Lipokine 12,13-diHOME in Human Milk Is Associated With Infant Adiposity

CONTEXT

Little is known about the specific breastmilk components responsible for protective effects on infant obesity. Whether 12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME), an oxidized linoleic acid metabolite and activator of brown fat metabolism, is present in human milk, or linked to infant adiposity, is unknown.

OBJECTIVE

To examine associations between concentrations of 12,13-diHOME in human milk and infant adiposity.

DESIGN

Prospective cohort study from 2015 to 2019, following participants from birth to 6 months of age.

SETTING

Academic medical centers.

PARTICIPANTS

Volunteer sample of 58 exclusively breastfeeding mother-infant pairs; exclusion criteria included smoking, gestational diabetes, and health conditions with the potential to influence maternal or infant weight gain.

MAIN OUTCOME MEASURES

Infant anthropometric measures including weight, length, body mass index (BMI), and body composition at birth and at 1, 3, and 6 months postpartum.

RESULTS

We report for the first time that 12,13-diHOME is present in human milk. Higher milk 12,13-diHOME level was associated with increased weight-for-length Z-score at birth (β = 0.5742, P = 0.0008), lower infant fat mass at 1 month (P = 0.021), and reduced gain in BMI Z-score from 0 to 6 months (β = -0.3997, P = 0.025). We observed similar associations between infant adiposity and milk abundance of related oxidized linoleic acid metabolites 12,13-Epoxy-9(Z)-octadecenoic acid (12,13-epOME) and 9,10-Dihydroxy-12-octadecenoic acid (9,10-diHOME), and metabolites linked to thermogenesis including succinate and lyso-phosphatidylglycerol 18:0. Milk abundance of 12,13-diHOME was not associated with maternal BMI, but was positively associated with maternal height, milk glucose concentration, and was significantly increased after a bout of moderate exercise.

CONCLUSIONS

We report novel associations between milk abundance of 12,13-diHOME and adiposity during infancy.

Disruption of Endoplasmic Reticulum Proteostasis in Age-Related Nervous System Disorders

Endoplasmic reticulum (ER) stress is a prominent cellular alteration of diseases impacting the nervous system that are associated to the accumulation of misfolded and aggregated protein species during aging. The unfolded protein response (UPR) is the main pathway mediating adaptation to ER stress, but it can also trigger deleterious cascades of inflammation and cell death leading to cell dysfunction and neurodegeneration. Genetic and pharmacological studies in experimental models shed light into molecular pathways possibly contributing to ER stress and the UPR activation in human neuropathies. Most of experimental models are, however, based on the overexpression of mutant proteins causing familial forms of these diseases or the administration of neurotoxins that induce pathology in young animals. Whether the mechanisms uncovered in these models are relevant for the etiology of the vast majority of age-related sporadic forms of neurodegenerative diseases is an open question. Here, we provide a systematic analysis of the current evidence linking ER stress to human pathology and the main mechanisms elucidated in experimental models. Furthermore, we highlight the recent association of metabolic syndrome to increased risk to undergo neurodegeneration, where ER stress arises as a common denominator in the pathogenic crosstalk between peripheral organs and the nervous system.

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.

Comparison of plasma nucleotide metabolites and amino acids pattern in patients with binge eating disorder and obesity

Binge eating disorder (BED) increasingly affects population, but the mechanisms of the disease and its biomarkers are not well characterized. Recently, plasma purines, pyrimidines, amino acid and nicotinamide metabolites profiling attracted attention in studies on pathology and biomarkers of mental disorders but has not been adequately studied in BED. Blood and plasma samples were taken from patients with adult obese with BED (n = 20) and control adult obese without BED (n = 17). Plasma samples were analyzed for nucleotides and amino acid concentrations with high-performance liquid chromatography-mass spectrometry. BED had a significantly (p < 0.05) lower uridine and hypoxanthine to creatinine ratio compared to the control group. Among the amino acids BED patients had significantly (p < 0.05) lower concentrations of glutamic acid, leucine, isoleucine and the whole branched-chain amino acids group, while the concentration of citrulline was increased. Among nicotinamide metabolites, 1-methylnicotinamide levels were significantly (p < 0.05) lower. This study highlights potential use of profiling nucleotide metabolite and amino acid pattern in BED patients that may provide information on mechanisms and potential biomarkers. However, further investigation in larger population is necessary to identify clinical correlates of the observed changes.

Modulating pyrimidine ribonucleotide levels for the treatment of cancer

By providing the necessary building blocks for nucleic acids and precursors for cell membrane synthesis, pyrimidine ribonucleotides are essential for cell growth and proliferation. Therefore, depleting pyrimidine ribonucleotide pools has long been considered as a strategy to reduce cancer cell growth. Here, we review the pharmacological approaches that have been employed to modulate pyrimidine ribonucleotide synthesis and degradation routes and discuss their potential use in cancer therapy. New developments in the treatment of myeloid malignancies with inhibitors of pyrimidine ribonucleotide synthesis justify revisiting the literature as well as discussing whether targeting this metabolic pathway can be effective and sufficiently selective for cancer cells to warrant an acceptable therapeutic index in patients.

Maternal supplementation with uridine influences fatty acid and amino acid constituents of offspring in a sow-piglet model

To investigate the cumulative effects of maternal supplementation with nucleotides in the form of uridine (UR) on fatty acid and amino acid constituents of neonatal piglets, fifty-two sows in late gestation were assigned randomly into the control (CON) group (fed a basal diet) or UR group (fed a basal diet with 150 g/t UR). Samples of neonates were collected during farrowing. Results showed that supplementing with UR in sows' diet significantly decreased the birth mortality of pigs (P = 0·05), and increased serum total cholesterol, HDL and LDL of neonatal piglets (P < 0·05). Moreover, the amino acid profile of serum and liver of neonatal piglets was affected by the addition of UR in sows' diets (P < 0·05). Furthermore, an up-regulation of mRNA expression of energy metabolism-related genes, including fatty acid elongase 5, fatty acid desaturase 1, hormone-sensitive lipase and cholesterol-7a-hydroxylase, was observed in the liver of neonates from the UR group. Additionally, a decrease in placental gene expression of excitatory amino acid transporters 2, excitatory amino acid transporter 3 and neutral AA transporter 1 in the UR group was concurrently observed (P < 0·05), and higher protein expression of phosphorylated protein kinase B, raptor, PPARα and PPARγ in placenta from the UR group was also observed (P < 0·05). Together, these results showed that maternal UR supplementation could regulate placental nutrient transport, largely in response to an alteration of mTORC1-PPAR signalling, thus regulating the nutrition metabolism of neonatal piglets and improving reproductive performance.

Leptin-Mediated Changes in the Human Metabolome

CONTEXT

While severe obesity due to congenital leptin deficiency is rare, studies in patients before and after treatment with leptin can provide unique insights into the role that leptin plays in metabolic and endocrine function.

OBJECTIVE

The aim of this study was to characterize changes in peripheral metabolism in people with congenital leptin deficiency undergoing leptin replacement therapy, and to investigate the extent to which these changes are explained by reduced caloric intake.

DESIGN

Ultrahigh performance liquid chromatography-tandem mass spectroscopy (UPLC-MS/MS) was used to measure 661 metabolites in 6 severely obese people with congenital leptin deficiency before, and within 1 month after, treatment with recombinant leptin. Data were analyzed using unsupervised and hypothesis-driven computational approaches and compared with data from a study of acute caloric restriction in healthy volunteers.

RESULTS

Leptin replacement was associated with class-wide increased levels of fatty acids and acylcarnitines and decreased phospholipids, consistent with enhanced lipolysis and fatty acid oxidation. Primary and secondary bile acids increased after leptin treatment. Comparable changes were observed after acute caloric restriction. Branched-chain amino acids and steroid metabolites decreased after leptin, but not after acute caloric restriction. Individuals with severe obesity due to leptin deficiency and other genetic obesity syndromes shared a metabolomic signature associated with increased BMI.

CONCLUSION

Leptin replacement was associated with changes in lipolysis and substrate utilization that were consistent with negative energy balance. However, leptin's effects on branched-chain amino acids and steroid metabolites were independent of reduced caloric intake and require further exploration.