PubMed

Int J Biol Macromol. 2023 Jul 1:125661. doi: 10.1016/j.ijbiomac.2023.125661. Online ahead of print.ABSTRACTParamylon (β-1,3-glucan) produced by Euglena gracilis displays antioxidant, antitumor, and hypolipidaemic functions. The biological properties of paramylon production by E. gracilis can be understood by elucidating the metabolic changes within the algae. In this study, the carbon sources in AF-6 medium were replaced with glucose, sodium acetate, glycerol, or ethanol, and the paramylon yield was measured. Adding 0.1260 g/L glucose to the culture medium resulted in the highest paramylon yield of 70.48 %. The changes in metabolic pathways in E. gracilis grown on glucose were assessed via non-targeted metabolomics analysis using ultra-high-performance liquid chromatography coupled to high-resolution quadrupole-Orbitrap mass spectrometry. We found that glucose, as a carbon source, regulated some differentially expressed metabolites, including l-glutamic acid, γ-aminobutyric acid (GABA), and l-aspartic acid. Pathway analysis using the Kyoto Encyclopedia of Genes and Genomes further showed that glucose regulated the carbon and nitrogen balance through the GABA shunt, which enhanced photosynthesis, regulated the flux of carbon and nitrogen into the tricarboxylic acid cycle, promoted glucose uptake, and increased the accumulation of paramylon. This study provides new insights into E. gracilis metabolism during paramylon synthesis.PMID:37399871 | DOI:10.1016/j.ijbiomac.2023.125661

Environ Int. 2023 Jun 28;178:108073. doi: 10.1016/j.envint.2023.108073. Online ahead of print.ABSTRACTWearing masks is used as an effective way to prevent the spread of viruses. However, the effect of wearing masks on skin health requires further assessment. In this study, a non-invasive D-squame sampling method coupled with an untargeted metabolomics analysis by liquid chromatography high-resolution mass spectrometry was developed to identify the changes in the skin metabolome caused by wearing masks. D-squame method was found to have advantages over the commonly used sterile gauze method, especially for the lipids and lipid-like molecules. A total of 356 skin metabolites were putatively identified from the stratum corneum of 10 volunteers, and 17 differential metabolites were significantly downregulated after wearing surgical masks or N95 respirators. The downregulation of metabolites such as phosphatidylethanolamine and sphingomyelin might be related to hypoxia or increased skin moisture caused by wearing masks. Changes in skin metabolomics indicated a potential risk of skin barrier disruption and skin inflammation. Intermittent removal of the masks can effectively alleviate changes in the skin metabolome.PMID:37399768 | DOI:10.1016/j.envint.2023.108073

ISME Commun. 2023 Jul 3;3(1):67. doi: 10.1038/s43705-023-00275-z.ABSTRACTWhile biodegradable polymers have received increased attention due to the recent marine plastic problem, few studies have compared microbiomes and their degradation processes among biodegradable polymers. In this study, we set up prompt evaluation systems for polymer degradation, allowing us to collect 418 microbiome and 125 metabolome samples to clarify the microbiome and metabolome differences according to degradation progress and polymer material (polycaprolactone [PCL], polybutylene succinate-co-adipate [PBSA], polybutylene succinate [PBS], polybutylene adipate-co-terephthalate [PBAT], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [PHBH]). The microbial community compositions were converged to each polymer material, and the largest differences were observed between PHBH and other polymers. Such gaps were probably formed primarily by the presence of specific hydrolase genes (i.e., 3HB depolymerase, lipase, and cutinase) in the microorganisms. Time-series sampling suggested several steps for microbial succession: (1) initial microbes decrease abruptly after incubation starts; (2) microbes, including polymer degraders, increase soon after the start of incubation and show an intermediate peak; (3) microbes, including biofilm constructers, increase their abundance gradually. Metagenome prediction showed functional changes, where free-swimming microbes with flagella adhered stochastically onto the polymer, and certain microbes started to construct a biofilm. Our large-dataset-based results provide robust interpretations for biodegradable polymer degradation.PMID:37400632 | DOI:10.1038/s43705-023-00275-z

Fish Physiol Biochem. 2023 Jul 3. doi: 10.1007/s10695-023-01216-2. Online ahead of print.ABSTRACTThe aim of this study was to investigate the survival rate, biochemical indices, and metabolome changes of the large yellow croaker after 48 h of live transportation. Two hundred and forty large yellow croakers (body weight: 23.4 ± 5.3 g, total length: 12.2 ± 0.7 cm) were used in this experiment. The transport buckets were filled with fresh seawater and the parameters of the water were a temperature of 16 ± 0.5 °C and a dissolved oxygen content of 6.0-7.2 mg/L. Large yellow crokers were first divided to 0, 10, 20, and 30 mg/L MS-222 groups to observe the 12 h survival rate. The survival rate of 10 mg/L MS-222 group (T1) was the 95%, highest of all, and was further analyzed. The results of liver biochemical indices indicated inhibition of gluconeogenesis and pentose phosphate pathway metabolism. In addition, metabolomics analysis identified significantly differentially expressed metabolites between T1 group and 0 mg/L MS-222 control (C) groups. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) results revealed that the pathways of amino acid metabolism, especially the lysine, aspartate, and homoserine in the liver were significantly affected. In conclusion, the combination of metabolomics and liver biochemical assays provided a characterization of the response mechanism of L. crocea exposed to live transportation.PMID:37400602 | DOI:10.1007/s10695-023-01216-2

Adv Sci (Weinh). 2023 Jul 3:e2300569. doi: 10.1002/advs.202300569. Online ahead of print.ABSTRACTHarmful algal blooms (HABs), which are promoted by eutrophication and intensified by global warming, occur worldwide. Allelochemicals, which are natural chemicals derived from plants or microbes, are emerging weapons to eliminate these blooms. However, the cost and technical challenges have limited the discovery of novel antialgal allelochemicals. Herein, the decomposition of agricultural straws is manipulated by white-rot fungi and achieved elevated antialgal efficiency. The transcriptomic analysis reveals that nutrient limitation activated fungal decomposition. By using a comparative nontarget metabolomics approach, a new type of allelochemical sphingosines (including sphinganine, phytosphingosine, sphingosine, and N-acetylsphingosine) is identified. These novel natural algaecides exhibit superior antialgal capability, with as high as an order of magnitude lower effective concentration on blooming species than other prevalent allelochemicals. The co-expression relationship between transcriptomic and metabolomic results indicate that sphinganine is strongly correlated with the differentially expressed lignocellulose degradation unigenes. The algal growth suppression is triggered by the activation of programmed cell death, malfunction of algal photosystem and antioxidant system, the disruption on CO2 assimilation and light absorption. The sphingosines reported here are a new category of allelochemicals in addition to the well-known antialgal natural chemicals, which are potential species-specific agents for HABs control identified by multi-omics methodology.PMID:37400420 | DOI:10.1002/advs.202300569

Proc Natl Acad Sci U S A. 2023 Jul 11;120(28):e2301007120. doi: 10.1073/pnas.2301007120. Epub 2023 Jul 3.ABSTRACTWood-decaying fungi are the major decomposers of plant litter. Heavy sequencing efforts on genomes of wood-decaying fungi have recently been made due to the interest in their lignocellulolytic enzymes; however, most parts of their proteomes remain uncharted. We hypothesized that wood-decaying fungi would possess promiscuous enzymes for detoxifying antifungal phytochemicals remaining in the dead plant bodies, which can be useful biocatalysts. We designed a computational mass spectrometry-based untargeted metabolomics pipeline for the phenotyping of biotransformation and applied it to 264 fungal cultures supplemented with antifungal plant phenolics. The analysis identified the occurrence of diverse reactivities by the tested fungal species. Among those, we focused on O-xylosylation of multiple phenolics by one of the species tested, Lentinus brumalis. By integrating the metabolic phenotyping results with publicly available genome sequences and transcriptome analysis, a UDP-glycosyltransferase designated UGT66A1 was identified and validated as an enzyme catalyzing O-xylosylation with broad substrate specificity. We anticipate that our analytical workflow will accelerate the further characterization of fungal enzymes as promising biocatalysts.PMID:37399371 | DOI:10.1073/pnas.2301007120

J Agric Food Chem. 2023 Jul 3. doi: 10.1021/acs.jafc.3c02015. Online ahead of print.ABSTRACTCarambola is a tropical fruit that is highly sought after by consumers due to its unique flavor, star shape, and nutritional value. Enhancing the flavor quality of this fruit can increase the consumer acceptance and market demand. However, flavor is an intrinsic characteristic of fruits. Its decoding requires in-depth knowledge based on recognizing key biological pathways relevant to flavor formation and development. In this study, the volatile and non-volatile metabolites contributing to the flavor variation of five carambola cultivars were investigated by a novel strategy combining GC-MS/O-based volatilomics with LC-MS-based metabolomics. Several significant flavor-related pathways, involving biosynthesis or metabolism of amino acids, terpenoids, fatty acids, sugar and organic acid, and flavonoids were identified based on the enrichment analysis of important volatile and non-volatile metabolites. The results indicated that there were metabolites in the flavor-related pathways being up- or downregulated, leading to the differences in flavor traits of different carambola cultivars. This study could provide a valuable reference for breeders and researchers of interest in the mechanisms underlying the regulation of flavor, which would ultimately lead to the creation of carambola cultivars with more attractive flavor profiles and pleasurable consuming experiences.PMID:37399281 | DOI:10.1021/acs.jafc.3c02015

Am J Physiol Regul Integr Comp Physiol. 2023 Jul 3. doi: 10.1152/ajpregu.00016.2023. Online ahead of print.ABSTRACTINTRODUCTION: Diet is considered a culprit for symptoms in irritable bowel syndrome (IBS), although mechanistic understanding of underlying causes is lacking. Metabolomics, i.e. the analysis of metabolites in biological samples may offer a diet-responsive fingerprint for IBS. Our aim was to explore alterations in the plasma metabolome after interventions with fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) or gluten versus control in IBS, and to relate such alterations to symptoms.METHODS: People with IBS (n=110) were included in a double-blind, randomized, crossover study with one-week provocations of FODMAPs, gluten or placebo. Symptoms were evaluated with the IBS severity scoring system (IBS-SSS). Untargeted metabolomics was performed on plasma samples using LC-qTOF-MS. Discovery of metabolite alterations by treatment was performed using random forest followed by linear mixed modelling. Associations were studied using Spearman correlation.RESULTS: The metabolome was affected by FODMAP (classification rate (CR) 0.88, p<0.0001), but less by gluten intake CR 0.72, p=0.01). FODMAP lowered bile acids, whereas phenolic-derived metabolites and 3-indolepropionic acid (IPA) were higher compared to placebo. IPA and some unidentified metabolites correlated weakly to abdominal pain and quality of life. Gluten affected lipid metabolism weakly, but with no interpretable relationship to IBS.CONCLUSIONS: FODMAP affected gut microbial-derived metabolites relating to positive health outcomes. IPA and unknown metabolites correlated weakly to IBS severity. Minor symptom worsening by FODMAP intake must be weighed against general positive health aspects of FODMAP. The gluten intervention affected lipid metabolism weakly with no interpretable association to IBS severity.REGISTRATION: www.CLINICALTRIALS: gov as NCT03653689.PMID:37399002 | DOI:10.1152/ajpregu.00016.2023

Front Physiol. 2023 Jun 14;14:1197224. doi: 10.3389/fphys.2023.1197224. eCollection 2023.ABSTRACTObjective: The purpose of this study was to employ metabolomics for the analysis of urine metabolites in swimmers, with the aim of establishing models for assessing their athletic status and competitive potential. Furthermore, the study sought to compare the identification efficacy of multi-component (urine and blood) model versus single-component (urine or blood) models, in order to determine the optimal approach for evaluating training and competitive status. Methods: A total of 187 Chinese professional swimmers, comprising 103 elite and 84 sub-elite level athletes, were selected as subjects for this study. Urine samples were obtained from each participant and subjected to nuclear magnetic resonance (NMR) metabolomics analysis. Significant urine metabolites were screened through multivariable logistic regression analysis, and an identification model was established. Based on the previously established model of blood metabolites, this study compared the discriminative and predictive performance of three models: either urine or blood metabolites model and urine + blood metabolites model. Results: Among 39 urine metabolites, 10 were found to be significantly associated with the athletic status of swimmers (p < 0.05). Of these, levels of 2-KC, cis-aconitate, formate, and LAC were higher in elite swimmers compared to sub-elite athletes, while levels of 3-HIV, creatinine, 3-HIB, hippurate, pseudouridine, and trigonelline were lower in elite swimmers. Notably, 2-KC and 3-HIB exhibited the most substantial differences. An identification model was developed to estimate physical performance and athletic level of swimmers while adjusting for different covariates and including 2-KC and 3-HIB. The urine metabolites model showed an area under the curve (AUC) of 0.852 (95% CI: 0.793-0.912) for discrimination. Among the three identification models tested, the combination of urine and blood metabolites showed the highest performance than either urine or blood metabolites, with an AUC of 0.925 (95% CI: 0.888-0.963). Conclusion: The two urine metabolites, 2-KC and 3-HIV, can serve as significant urine metabolic markers to establish a discrimination model for identifying the athletic status and competitive potential of Chinese elite swimmers. Combining two screened urine metabolites with four metabolites reported exhibiting significant differences in blood resulted in improved predictive performance compared to using urine metabolites alone. These findings indicate that combining blood and urine metabolites has a greater potential for identifying and predicting the athletic status and competitive potential of Chinese professional swimmers.PMID:37398904 | PMC:PMC10307620 | DOI:10.3389/fphys.2023.1197224

Front Immunol. 2023 Jun 15;14:1222662. doi: 10.3389/fimmu.2023.1222662. eCollection 2023.ABSTRACT[This corrects the article DOI: 10.3389/fimmu.2023.1135588.].PMID:37398675 | PMC:PMC10311434 | DOI:10.3389/fimmu.2023.1222662

medRxiv. 2023 Jun 21:2023.06.12.23291054. doi: 10.1101/2023.06.12.23291054. Preprint.ABSTRACTInvestigating the association of lipidome profiles with central Alzheimer's disease (AD) biomarkers, including amyloid/tau/neurodegeneration (A/T/N), can provide a holistic view between the lipidome and AD. We performed cross-sectional and longitudinal association analysis of serum lipidome profiles with AD biomarkers in the Alzheimer's Disease Neuroimaging Initiative cohort (N=1,395). We identified lipid species, classes, and network modules that were significantly associated with cross-sectional and longitudinal changes of A/T/N biomarkers for AD. Notably, we identified the lysoalkylphosphatidylcholine (LPC(O)) as associated with "A/N" biomarkers at baseline at lipid species, class, and module levels. Also, G M3 ganglioside showed significant association with baseline levels and longitudinal changes of the "N" biomarkers at species and class levels. Our study of circulating lipids and central AD biomarkers enabled identification of lipids that play potential roles in the cascade of AD pathogenesis. Our results suggest dysregulation of lipid metabolic pathways as precursors to AD development and progression.PMID:37398438 | PMC:PMC10312871 | DOI:10.1101/2023.06.12.23291054

bioRxiv. 2023 Jun 13:2023.06.13.544113. doi: 10.1101/2023.06.13.544113. Preprint.ABSTRACTThe highly conserved Rnf complex is important for energy conservation and ion transport in many bacteria, yet its potential role in bacterial virulence is poorly understood. Here, we illuminate the Rnf complex function in Fusobacterium nucleatum , a pathobiont of the human oral cavity that promotes many oral and extraoral diseases including periodontitis, preterm birth, and colorectal cancer. We show that the fusobacterial rnf locus, comprised of rnfCDGEAB genes, is functional and that the genetic disruption of the Rnf complex via non-polar, in-frame deletion of rnfC (Δ rnfC ) abrogates not only polymicrobial interaction (or coaggregation) associated with adhesin RadD and biofilm formation, but also hydrogen sulfide production. The defect in coaggregation is not due to reduced cell surface of RadD, but rather an increased level of extracellular lysine, which binds RadD and inhibits coaggregation. Indeed, removal of extracellular lysine via washing Δ rnfC cells restores coaggregation, while addition of lysine inhibits this process. These phenotypes mirror that of a mutant (Δ kamA ) that fails to metabolize extracellular lysine. Strikingly, the Δ rnfC mutant is defective in ATP production, cell growth, cell morphology, and expression of the enzyme MegL that produces hydrogen sulfide from cysteine. Metabolic profiling demonstrated that catabolism of many amino acids, including histidine and lysine, is altered in Δ rnfC cells, leading to reduction in butyrate. Most importantly, we show that the Δ rnfC mutant is severely attenuated in a mouse model of preterm birth. Thus, the Rnf complex plays a critical role in fusobacterial virulence via modulation of many metabolic pathways.IMPORTANCE: Although viewed as an oral commensal, the Gram-negative F. nucleatum is an opportunistic pathogen that can traverse to extra-oral sites, such as placenta and colon, promoting adverse pregnancy outcomes and colorectal cancer, respectively. How this anaerobe sustains the various metabolically changing environments enabling its virulence potential remains unclear. Here, we demonstrate that the Rnf complex is key to F. nucleatum metabolism and virulence as genetic disruption of Rnf causes pleiotropic defects in polymicrobial interaction, biofilm formation, cell growth and morphology, hydrogen sulfide production, and ATP synthesis. Targeted metabolomic profiling demonstrates that the loss of this highly conserved respiratory enzyme significantly diminishes catabolism of numerous amino acids, which negatively impacts fusobacterial virulence as tested in a preterm birth model in mice.PMID:37398403 | PMC:PMC10312631 | DOI:10.1101/2023.06.13.544113

bioRxiv. 2023 Jun 14:2023.06.13.544885. doi: 10.1101/2023.06.13.544885. Preprint.ABSTRACTCurtailed reproduction affects lifespan and fat metabolism in diverse organisms, suggesting a regulatory axis between these processes. In Caenorhabditis elegans , ablation of germline stem cells (GSCs) leads to extended lifespan and increased fat accumulation, suggesting GSCs emit signals that modulate systemic physiology. Previous studies mainly focused on the germline-less glp-1(e2141) mutant, however, the hermaphroditic germline of C. elegans provides an excellent opportunity to study the impact of different types of germline anomalies on longevity and fat metabolism. In this study, we compared the metabolomic, transcriptomic, and genetic pathway differences in three sterile mutants: germline-less glp-1 , feminized fem-3 , and masculinized mog-3 . We found that although the three sterile mutants all accumulate excess fat and share expression changes in stress response and metabolism genes, the germline-less glp-1 mutant exhibits the most robust lifespan increase, whereas the feminized fem-3 mutant only lives longer at specific temperatures, and the masculinized mog-3 mutant lives drastically shorter. We demonstrated that overlapping but distinct genetic pathways are required for the longevity of the three different sterile mutants. Our data showed that disruptions of different germ cell populations result in unique and complex physiological and longevity consequences, highlighting exciting avenues for future investigations.PMID:37398385 | PMC:PMC10312764 | DOI:10.1101/2023.06.13.544885

Res Sq. 2023 Jun 13:rs.3.rs-3038923. doi: 10.21203/rs.3.rs-3038923/v1. Preprint.ABSTRACTBackground: Duchenne muscular dystrophy (DMD) is a severe form of muscular dystrophy without an effective treatment, caused by mutations in the DMD gene, leading to the absence of dystrophin. DMD results in muscle weakness, loss of ambulation and death at an early age. Metabolomics studies in mdx mice, the most used model for DMD, reveal changes in metabolites associated with muscle degeneration and aging. In DMD, the tongue muscles exhibit unique behavior, initially showing partial protection against inflammation but later experiencing fibrosis and loss of muscle fibers. Certain metabolites and proteins, like TNF-α and TGF-β, are potential biomarkers for dystrophic muscle characterization. Methods: To investigate disease progression and aging, we utilized young (1-month old) and old (21-25 months old) mdx and wild-type mice. Metabolite changes were analyzed using 1-H Nuclear Magnetic Resonance, while TNF-α and TGF-β were assessed using Western blotting to examine inflammation, and fibrosis. Morphometric analysis was conducted to assess the extent of myofiber damage between groups. Results: The histological analysis of the tongue showed no differences between groups. No differences were found between the concentrations of metabolites from wild type or mdx animals of the same age. The metabolites alanine, methionine, 3-methylhistidine were higher, and taurine and glycerol were lower in young animals in both wild type and mdx (p < 0.001). The metabolites glycine (p < 0.001) and glutamic acid (p = 0.0018) were different only in the mdx groups, being higher in young mdx mice. Acetic acid, phosphocreatine, isoleucine, succinic acid, creatine and the proteins TNF-α and TGF-β had no difference in the analysis between groups (p > 0.05). Conclusions: Surprisingly, histological and protein analysis reveals that the tongue of young and old mdx animals is protected from severe myonecrosis observed in other muscles. The metabolites alanine, methionine, 3-methylhistidine, taurine, and glycerol may be effective for specific assessments, although their use for disease progression monitoring should be cautious due to age-related changes. Acetic acid, phosphocreatine, isoleucine, succinate, creatine, TNF-α, and TGF-β do not vary with aging and remain constant in spared muscles, suggesting their potential as specific biomarkers for DMD progression independent of aging.PMID:37398370 | PMC:PMC10312970 | DOI:10.21203/rs.3.rs-3038923/v1

bioRxiv. 2023 May 30:2023.05.30.542962. doi: 10.1101/2023.05.30.542962. Preprint.ABSTRACTAcross the tree of life, clonal populations-from cancer to chronic bacterial infections - frequently give rise to subpopulations with different metabolic phenotypes. Metabolic exchange or cross-feeding between subpopulations can have profound effects on both cell phenotypes and population-level behavior. In Pseudomonas aeruginosa , subpopulations with loss-of-function mutations in the lasR gene are common. Though LasR is often described for its role in density-dependent virulence factor expression, interactions between genotypes suggest potential metabolic differences. The specific metabolic pathways and regulatory genetics enabling such interactions were previously undescribed. Here, we performed an unbiased metabolomics analysis that revealed broad differences in intracellular metabolomes, including higher levels of intracellular citrate in LasR- strains. We found that while both strains secreted citrate, only LasR- strains, consumed citrate in rich media. Elevated activity of the CbrAB two component system which relieves carbon catabolite repression enabled citrate uptake. Within mixed genotype communities, we found that the citrate responsive two component system TctED and its gene targets OpdH (porin) and TctABC (transporter) required for citrate uptake were induced and required for enhanced RhlR signalling and virulence factor expression in LasR- strains. Enhanced citrate uptake by LasR- strains eliminates differences in RhlR activity between LasR+ and LasR- strains thereby circum-venting the sensitivity of LasR- strains to quorum sensing controlled exoproducts. Citrate cross feeding also induces pyocyanin production in LasR- strains co-cultured with Staphylococcus aureus , another species known to secrete biologically-active concentrations of citrate. Metabolite cross feeding may play unrecognized roles in competitive fitness and virulence outcomes when different cell types are together.IMPORTANCE: Cross-feeding can change community composition, structure and function. Though cross-feeding has predominantly focused on interactions between species, here we unravel a cross-feeding mechanism between frequently co-observed isolate genotypes of Pseudomonas aeruginosa . Here we illustrate an example of how such clonally-derived metabolic diversity enables intraspecies cross-feeding. Citrate, a metabolite released by many cells including P. aeruginosa , was differentially consumed between genotypes, and this cross-feeding induced virulence factor expression and fitness in genotypes associated with worse disease.PMID:37398201 | PMC:PMC10312497 | DOI:10.1101/2023.05.30.542962

medRxiv. 2023 Jun 4:2023.05.31.23290681. doi: 10.1101/2023.05.31.23290681. Preprint.ABSTRACTDiabetic kidney disease (DKD) can lead to end-stage kidney disease (ESKD) and mortality, however, few mechanistic biomarkers are available for high risk patients, especially those without macroalbuminuria. Urine from participants with diabetes from Chronic Renal Insufficiency Cohort (CRIC), Singapore Study of Macro-Angiopathy and Reactivity in Type 2 Diabetes (SMART2D), and the Pima Indian Study determined if urine adenine/creatinine ratio (UAdCR) could be a mechanistic biomarker for ESKD. ESKD and mortality were associated with the highest UAdCR tertile in CRIC (HR 1.57, 1.18, 2.10) and SMART2D (HR 1.77, 1.00, 3.12). ESKD was associated with the highest UAdCR tertile in patients without macroalbuminuria in CRIC (HR 2.36, 1.26, 4.39), SMART2D (HR 2.39, 1.08, 5.29), and Pima Indian study (HR 4.57, CI 1.37-13.34). Empagliflozin lowered UAdCR in non-macroalbuminuric participants. Spatial metabolomics localized adenine to kidney pathology and transcriptomics identified ribonucleoprotein biogenesis as a top pathway in proximal tubules of patients without macroalbuminuria, implicating mammalian target of rapamycin (mTOR). Adenine stimulated matrix in tubular cells via mTOR and stimulated mTOR in mouse kidneys. A specific inhibitor of adenine production was found to reduce kidney hypertrophy and kidney injury in diabetic mice. We propose that endogenous adenine may be a causative factor in DKD.PMID:37398187 | PMC:PMC10312877 | DOI:10.1101/2023.05.31.23290681

medRxiv. 2023 Jun 16:2023.06.13.23291346. doi: 10.1101/2023.06.13.23291346. Preprint.ABSTRACTGDM is a strong risk factor for progression to T2D after pregnancy. Although both GDM and T2D exhibit heterogeneity, the link between the distinct heterogeneity of GDM and incident T2D has not been established. Herein, we evaluate early postpartum profiles of women with recent GDM who later developed incident T2D using a soft clustering method, followed by the integration of both clinical phenotypic variables and metabolomics to characterize these heterogeneous clusters/groups clinically and their molecular mechanisms. We identified three clusters based on two indices of glucose homeostasis at 6-9 weeks postpartum - HOMA-IR and HOMA-B among women who developed incident T2D during the 12-year follow-up. The clusters were classified as follows: pancreatic beta-cell dysfunction group (cluster-1), insulin resistant group (cluster-3), and a combination of both phenomena (cluster-2) comprising the majority of T2D. We also identified postnatal blood test parameters to distinguish the three clusters for clinical testing. Moreover, we compared these three clusters in their metabolomics profiles at the early stage of the disease to identify the mechanistic insights. A significantly higher concentration of a metabolite at the early stage of a T2D cluster than other clusters indicates its essentiality for the particular disease character. As such, the early-stage characters of T2D cluster-1 pathology include a higher concentration of sphingolipids, acyl-alkyl phosphatidylcholines, lysophosphatidylcholines, and glycine, indicating their essentiality for pancreatic beta-cell function. In contrast, the early-stage characteristics of T2D cluster-3 pathology include a higher concentration of diacyl phosphatidylcholines, acyl-carnitines, isoleucine, and glutamate, indicating their essentiality for insulin actions. Notably, all these biomolecules are found in the T2D cluster-2 with mediocre concentrations, indicating a true nature of a mixed group. In conclusion, we have deconstructed incident T2D heterogeneity and identified three clusters with their clinical testing procedures and molecular mechanisms. This information will aid in adopting proper interventions using a precision medicine approach.PMID:37398098 | PMC:PMC10312884 | DOI:10.1101/2023.06.13.23291346

bioRxiv. 2023 May 31:2023.05.30.542973. doi: 10.1101/2023.05.30.542973. Preprint.ABSTRACTAcross the tree of life, clonal populations-from cancer to chronic bacterial infections - frequently give rise to subpopulations with different metabolic phenotypes. Metabolic exchange or cross-feeding between subpopulations can have profound effects on both cell phenotypes and population-level behavior. In Pseudomonas aeruginosa , subpopulations with loss-of-function mutations in the lasR gene are common. Though LasR is often described for its role in density-dependent virulence factor expression, interactions between genotypes suggest potential metabolic differences. The specific metabolic pathways and regulatory genetics enabling such interactions were previously undescribed. Here, we performed an unbiased metabolomics analysis that revealed broad differences in intracellular metabolomes, including higher levels of intracellular citrate in LasR- strains. We found that while both strains secreted citrate, only LasR- strains, consumed citrate in rich media. Elevated activity of the CbrAB two component system which relieves carbon catabolite repression enabled citrate uptake. Within mixed genotype communities, we found that the citrate responsive two component system TctED and its gene targets OpdH (porin) and TctABC (transporter) required for citrate uptake were induced and required for enhanced RhlR signalling and virulence factor expression in LasR- strains. Enhanced citrate uptake by LasR- strains eliminates differences in RhlR activity between LasR+ and LasR- strains thereby circumventing the sensitivity of LasR- strains to quorum sensing controlled exoproducts. Citrate cross feeding also induces pyocyanin production in LasR- strains co-cultured with Staphylococcus aureus , another species known to secrete biologically-active concentrations of citrate. Metabolite cross feeding may play unrecognized roles in competitive fitness and virulence outcomes when different cell types are together.IMPORTANCE: Cross-feeding can change community composition, structure and function. Though cross-feeding has predominantly focused on interactions between species, here we unravel a cross-feeding mechanism between frequently co-observed isolate genotypes of Pseudomonas aeruginosa . Here we illustrate an example of how such clonally-derived metabolic diversity enables intraspecies cross-feeding. Citrate, a metabolite released by many cells including P. aeruginosa , was differentially consumed between genotypes, and this cross-feeding induced virulence factor expression and fitness in genotypes associated with worse disease.PMID:37398089 | PMC:PMC10312601 | DOI:10.1101/2023.05.30.542973

bioRxiv. 2023 Jun 1:2023.05.30.542769. doi: 10.1101/2023.05.30.542769. Preprint.ABSTRACTSarcopenia, the age-related loss of muscle mass and function, contributes to decreased quality of life in the elderly and increased healthcare costs. Decreased skeletal muscle mass, specific force, increased overall fatty depositions in the skeletal muscle, frailty and depressed energy maintenance are all associated with increased oxidative stress and the decline in mitochondrial function with age. We hypothesized that elevated mitochondrial stress with age alters the capacity of mitochondria to utilize different substrates following muscle contraction. To test this hypothesis, we designed two in vivo muscle-stimulation protocols to simulate high-intensity intervals (HII) or low intensity steady-state (LISS) exercise to characterize the effect of age and sex on mitochondrial substrate utilization in skeletal muscle following muscle contraction. Following HII stimulation, mitochondria from young skeletal muscle increased fatty acid oxidation compared to non-stimulated control muscle; however, mitochondria from aged muscle decreased fatty acid oxidation. In contrast, following LISS, mitochondrial from young skeletal muscle decreased fatty acid oxidation, whereas aged mitochondria increased fatty acid oxidation. We also found that HII can inhibit mitochondrial oxidation of glutamate in both stimulated and non-stimulated aged muscle, suggesting HII initiates circulation of an exerkine capable of altering whole-body metabolism. Analyses of the muscle metabolome indicates that changes in metabolic pathways induced by HII and LISS contractions in young muscle are absent in aged muscle. Treatment with elamipretide, a mitochondrially targeted peptide, restored glutamate oxidation and metabolic pathway changes following HII suggesting rescuing redox status and improving mitochondrial function in aged muscle enhances the metabolic response to muscle contraction.PMID:37398086 | PMC:PMC10312519 | DOI:10.1101/2023.05.30.542769

bioRxiv. 2023 Jun 3:2023.06.02.542598. doi: 10.1101/2023.06.02.542598. Preprint.ABSTRACTGlobal plastic use has consistently increased over the past century with several different types of plastics now being produced. Much of these plastics end up in oceans or landfills leading to a substantial accumulation of plastics in the environment. Plastic debris slowly degrades into microplastics (MPs) that can ultimately be inhaled or ingested by both animals and humans. A growing body of evidence indicates that MPs can cross the gut barrier and enter into the lymphatic and systemic circulation leading to accumulation in tissues such as the lungs, liver, kidney, and brain. The impacts of mixed MPs exposure on tissue function through metabolism remains largely unexplored. To investigate the impact of ingested MPs on target metabolomic pathways, mice were subjected to either polystyrene microspheres or a mixed plastics (5 µm) exposure consisting of polystyrene, polyethylene and the biodegradability and biocompatible plastic, poly-(lactic-co-glycolic acid). Exposures were performed twice a week for four weeks at a dose of either 0, 2, or 4 mg/week via oral gastric gavage. Our findings demonstrate that, in mice, ingested MPs can pass through the gut barrier, be translocated through the systemic circulation, and accumulate in distant tissues including the brain, liver, and kidney. Additionally, we report on the metabolomic changes that occur in the colon, liver and brain which show differential responses that are dependent on dose and type of MPs exposure. Lastly, our study provides proof of concept for identifying metabolomic alterations associated with MPs exposure and adds insight into the potential health risks that mixed MPs contamination may pose to humans.PMID:37398080 | PMC:PMC10312509 | DOI:10.1101/2023.06.02.542598