Lysine Metabolism Research Articles

Comparative brain metabolomics reveals shared and distinct metabolic alterations in Alzheimer's disease and progressive supranuclear palsy.

Metabolic dysregulation is a hallmark of neurodegenerative diseases, including Alzheimer's disease (AD) and progressive supranuclear palsy (PSP). Although metabolic dysregulation is a common link between these two tauopathies, a comprehensive brain metabolic comparison of the diseases has not yet been performed. We analyzed 342 postmortem brain samples from the Mayo Clinic Brain Bank and examined 658 metabolites in the cerebellar cortex and the temporal cortex between the two tauopathies. Our findings indicate that both diseases display oxidative stress associated with lipid metabolism, mitochondrial dysfunction linked to lysine metabolism, and an indication of tau-induced polyamine stress response. However, specific to AD, we detected glutathione-related neuroinflammation, deregulations of enzymes tied to purines, and cognitive deficits associated with vitamin B. Our findings underscore vast alterations in the brain's metabolome, illuminating shared neurodegenerative pathways and disease-specific traits in AD and PSP. First high-throughput metabolic comparison of Alzheimer's diesease (AD) versus progressive supranuclear palsy (PSP) in brain tissue. Cerebellar cortex (CER) shows substantial AD-related metabolic changes, despite limited proteinopathy. AD impacts both CER and temporal cortex (TCX); PSP's changes are primarily in CER. AD and PSP share metabolic alterations despite major pathological differences.

A pilot metabolomics study across the continuum of interstitial lung disease fibrosis severity.

Interstitial lung diseases (ILDs) include a variety of inflammatory and fibrotic pulmonary conditions. This study employs high-resolution metabolomics (HRM) to explore plasma metabolites and pathways across ILD phenotypes, including non-fibrotic ILD, idiopathic pulmonary fibrosis (IPF), and non-IPF fibrotic ILD. The study used 80 plasma samples for HRM, and involved linear trend and group-wise analyses of metabolites altered in ILD phenotypes. We utilized limma one-way ANOVA and mummichog algorithms to identify differences in metabolites and pathways across ILD groups. Then, we focused on metabolites within critical pathways, indicated by high pathway overlap sizes and low p-values, for further analysis. Targeted HRM identified putrescine, hydroxyproline, prolyl-hydroxyproline, aspartate, and glutamate with significant linear increases in more fibrotic ILD phenotypes, suggesting their role in ILD fibrogenesis. Untargeted HRM highlighted pathway alterations in lysine, vitamin D3, tyrosine, and urea cycle metabolism, all associated with pulmonary fibrosis. In addition, methylparaben level had a significantly increasing linear trend and was higher in the IPF than fibrotic and non-ILD groups. This study highlights the importance of specific amino acids, metabolic pathways, and xenobiotics in the progression of pulmonary fibrosis.

Abstract A033: Metabolomics reveals racial differences in metabolites among women

Abstract Background: Non-Hispanic Black (NHB) women experience disparities in cancer outcomes and mortality compared with non-Hispanic White (NHW) women. While social determinants of health contribute to these differences, investigating potential biological factors behind the observed racial differences is essential for developing effective health interventions. Therefore, we performed a comprehensive analysis comparing the metabolomic profiles of NHB and NHW women to identify whether differences exist in metabolites. Methods: We performed metabolomic profiling on 674 women recruited at Washington University School of Medicine, St. Louis, MO. A total of 1074 metabolites were profiled at Metabolon. We excluded 246 metabolites with missing values in ≥300 women from the analyses. We used the 10-nearest neighbor method for imputing missing data. We investigated the associations between metabolites and race using linear regression models, adjusting for age, body mass index, alcohol consumption, and education level. Metabolites were log-transformed before regression analyses, and linear coefficients were back-transformed to the original scale. A Bonferroni-adjusted p-value<10-5 was considered statistically significant. Pathway enrichment analyses were conducted for differential metabolites within each super-pathway. Results: Twenty-five (3.0%) of the 828 metabolites differed significantly between NHW and NHB women at the Bonferroni-adjusted p- value<10-5 level, with 19 metabolites higher in NHW women and 6 metabolites higher in NHB women. These metabolites belong to amino acid (n=12), xenobiotics (n=9), lipid (n=2), cofactors and vitamins (n=1), and partially characterized molecules (n=1) super-pathways. In NHB women, the top 3 metabolites with the highest percentage differences compared with NHW women were 2-naphthol sulfate (89.7%, p=3.6×10-6)[chemical], 2-hydroxyfluorene sulfate (71.6%, p=5.9×10-8)[tobacco metabolite], and carotene diol (3) (35.6%, p=1.1×10-6)[vitamin A metabolism]. Conversely, the top 3 metabolites with the highest percentage differences in NHW women compared with NHB women were N6-methyllysine (59.0%, p=1.2×10-26)[lysine metabolism], tryptophan betaine (57.7%, p=2.1×10-11)[tryptophan metabolism], and theophylline (52.8%, p=2.2×10-7)[xanthine metabolism]. Conclusions: We identified racial differences in several functional metabolites among women that may contribute to the observed cancer disparities and have implications for cancer prevention. Citation Format: Ghazaleh Pourali, Liang Li, Kayla R. Getz, Myung Sik Jeon, Jingqin Luo, Chongliang Luo, Adetunji T. Toriola. Metabolomics reveals racial differences in metabolites among women [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A033.

Structural damage and organelle destruction: Mechanisms of pseudolaric acid B against S. parasitica

This study aimed to investigate the potential of Chinese herbs in treating aquatic diseases. More particularly, the antibacterial properties and mechanisms of Chinese herbs and their monomers against Saprolegnia parasitica were investigated. In vitro antibacterial testing revealed that Cortex pseudolaricis exhibited significant antibacterial activity, with a minimum inhibitory concentration (MIC) of 0.98 mg/mL. The primary monomer responsible for this antibacterial effect was identified as pseudolaric acid B (PAB), with an MIC of 0.03 mg/mL. SEM and TEM analyses demonstrated that treatment with PAB resulted in structural damage to the cell wall and cell membrane of hyphae, leading to lysis of the cell wall and membrane of spores, organelle destruction, and vacuole formation within the cells. Analysis of the transcriptome and metabolome revealed that PAB disrupts amino acid, lipid, and nucleic acid metabolism in S. parasitica. This disruption impacts the biosynthesis and metabolism of various amino acids, including arginine, proline, glycine, serine, cysteine, methionine, glutamate, lysine, histidine, phenylalanine, tyrosine, and tryptophan. PAB also results in increased energy consumption and hindered energy generation in S. parasitica, as well as interference with the synthesis of membrane components such as DAG and phytosphingosine. Furthermore, PAB disrupts RNA, DNA, and ATP production in S. parasitica. Consequently, protein synthesis, energy supply, immune function and barrier structure in S. parasitica are weakened, and potentially leading to death. This study identifies potential antibacterial agents for environmentally friendly solutions for controlling fish saprolegniasis.

Reconstruction and Analysis of a Genome-Scale Metabolic Model of Acinetobacter lwoffii.

Acinetobacter lwoffii is widely considered to be a harmful bacterium that is resistant to medicines and disinfectants. A. lwoffii NL1 degrades phenols efficiently and shows promise as an aromatic compound degrader in antibiotic-contaminated environments. To gain a comprehensive understanding of A. lwoffii, the first genome-scale metabolic model of A. lwoffii was constructed using semi-automated and manual methods. The iNX811 model, which includes 811 genes, 1071 metabolites, and 1155 reactions, was validated using 39 unique carbon and nitrogen sources. Genes and metabolites critical for cell growth were analyzed, and 12 essential metabolites (mainly in the biosynthesis and metabolism of glycan, lysine, and cofactors) were identified as antibacterial drug targets. Moreover, to explore the metabolic response to phenols, metabolic flux was simulated by integrating transcriptomics, and the significantly changed metabolism mainly included central carbon metabolism, along with some transport reactions. In addition, the addition of substances that effectively improved phenol degradation was predicted and validated using the model. Overall, the reconstruction and analysis of model iNX811 helped to study the antimicrobial systems and biodegradation behavior of A. lwoffii.

The Association of the Essential Amino Acids Lysine, Methionine, and Threonine with Clinical Outcomes in Patients at Nutritional Risk: Secondary Analysis of a Randomized Clinical Trial.

Lysine, methionine, and threonine are essential amino acids with vital functions for muscle and connective tissue health, metabolic balance, and the immune system. During illness, the demand for these amino acids typically increases, which puts patients at risk for deficiencies with harmful clinical consequences. In a secondary analysis of the Effect of Early Nutritional Support on Frailty, Functional Outcomes, and Recovery of Malnourished Medical Inpatients Trial (EFFORT), which compared individualized nutritional support to usual care nutrition in patients at nutritional risk, we investigated the prognostic impact of the lysine, methionine, and threonine metabolism. We had complete clinical and amino acid data in 237 patients, 58 of whom reached the primary endpoint of death at 30 days. In a model adjusted for comorbidities, sex, nutritional risk, and trial intervention, low plasma methionine levels were associated with 30-day mortality (adjusted HR 1.98 [95% CI 1.16 to 3.36], p = 0.01) and with a decline in functional status (adjusted OR 2.06 [95% CI 1.06 to 4.01], p = 0.03). The results for lysine and threonine did not show statistically significant differences regarding clinical outcomes. These findings suggest that low levels of methionine may be critical during hospitalization among patients at nutritional risk. Further studies should investigate the effect of supplementation of methionine in this patient group to improve outcomes.

Saliva, Plasma, and Multifluid Metabolomic Signatures of Periodontal Disease, Type 2 Diabetes Progression, and Markers of Glycemia and Dyslipidemia Among Puerto Rican Adults With Overweight and Obesity.

Evidence from cohort studies indicates a bidirectional relationship between periodontal disease and type 2 diabetes (T2D), but the underlying mechanisms remain unknown. In this study, we aimed to (1) identify saliva, plasma, and multifluid metabolomic signatures associated with periodontal disease and (2) determine if these signatures predict T2D progression and cardiometabolic biomarkers at year 3. We included participants from the SOALS (San Juan Overweight Adult Longitudinal Study) (n=911). Metabolites from saliva (k=635) and plasma (k=1051) were quantified using liquid chromatography-mass spectrometry. We applied elastic net regression with 10-fold cross-validation to identify baseline metabolomic signatures of periodontal disease. Multivariable Cox proportional hazards regression and linear regression were used to evaluate the association with T2D progression and biomarker concentrations. Metabolomic profilesincluded highly weighted metabolites related to lysine and pyrimidine metabolism. Periodontal disease or its 3 metabolomic signatures were not associated with T2D progression in 3 years. Prospectively, 1-SD increments in the multifluid and saliva metabolomic signatures were associated with higher low-density lipoprotein (multifluid: 12.9±5.70, P=0.02; saliva: 13.3±5.11, P=0.009). A 1-SD increment in the plasma metabolomic signature was also associated with Homeostatic Model Assessment for Insulin Resistance (2.67±1.14, P=0.02) and triglyceride (0.52±0.18, P=0.002). Although metabolomic signatures of periodontal disease could not predict T2D progression, they were associated with low-density lipoprotein, triglyceride, and Homeostatic Model Assessment for Insulin Resistance levels at year 3.

Gut Microbiota as Predictive Biomarker for Chronic Heart Failure in Patients with Different Nutritional Risk.

To examine the relationship between gut microbiota and disease development in chronic heart failure patients with different nutritional risk. The study analyzed stool samples from 62 CHF patients and 21 healthy peoples using 16S rRNA gene sequencing. CHF patients were separated into risk (n = 30) and non-risk group (n = 32) based on NRS2002 scores. Analysis methods used were LEfSe, random forest regression model, ROC curves, BugBase, PICRUSt2, metagenomeSeq. Risk group includes 11 cases of HFrEF, 6 cases of HFpEF, and 13 cases of HFmrEF. LefSe analysis confirmed that the risk group had higher levels of Enterobacter and Escherichia-Shigella. Correlation analysis revealed a negative correlation between prealbumin and Escherichia-Shigella. The presence of Enterobacter and Escherichia-Shigella worsens intestinal inflammation in CHF patients, impacting lysine metabolism by influencing its degradation metabolic function. This interference further disrupts albumin and prealbumin synthesis, leading to malnutrition in CHF patients and ultimately worsening the disease.

Screening a knowledge-based library of low molecular weight compounds against the proline biosynthetic enzyme 1-pyrroline-5-carboxylate 1 (PYCR1).

Δ1-pyrroline-5-carboxylate reductase isoform 1 (PYCR1) is the last enzyme of proline biosynthesis and catalyzes the NAD(P)H-dependent reduction of Δ1-pyrroline-5-carboxylate to L-proline. High PYCR1 gene expression is observed in many cancers and linked to poor patient outcomes and tumor aggressiveness. The knockdown of the PYCR1 gene or the inhibition of PYCR1 enzyme has been shown to inhibit tumorigenesis in cancer cells and animal models of cancer, motivating inhibitor discovery. We screened a library of 71 low molecular weight compounds (average MW of 131 Da) against PYCR1 using an enzyme activity assay. Hit compounds were validated with X-ray crystallography and kinetic assays to determine affinity parameters. The library was counter-screened against human Δ1-pyrroline-5-carboxylate reductase isoform 3 and proline dehydrogenase (PRODH) to assess specificity/promiscuity. Twelve PYCR1 and one PRODH inhibitor crystal structures were determined. Three compounds inhibit PYCR1 with competitive inhibition parameter of 100 μM or lower. Among these, (S)-tetrahydro-2H-pyran-2-carboxylic acid (70 μM) has higher affinity than the current best tool compound N-formyl-l-proline, is 30 times more specific for PYCR1 over human Δ1-pyrroline-5-carboxylate reductase isoform 3, and negligibly inhibits PRODH. Structure-affinity relationships suggest that hydrogen bonding of the heteroatom of this compound is important for binding to PYCR1. The structures of PYCR1 and PRODH complexed with 1-hydroxyethane-1-sulfonate demonstrate that the sulfonate group is a suitable replacement for the carboxylate anchor. This result suggests that the exploration of carboxylic acid isosteres may be a promising strategy for discovering new classes of PYCR1 and PRODH inhibitors. The structure of PYCR1 complexed with l-pipecolate and NADH supports the hypothesis that PYCR1 has an alternative function in lysine metabolism.

Single-cell landscape of immunological responses in elderly patients with sepsis

Sepsis is a dysregulated host response to severe infections, and immune dysfunction plays a crucial role in its pathogenesis. Elderly patients, a special population influenced by immunosenescence, are more susceptible to sepsis and have a worse prognosis. However, the immunopathogenic mechanisms underlying sepsis in elderly patients remain unclear. Here, we performed single-cell RNA sequencing of peripheral blood samples from young and old subjects and patients with sepsis. By exploring the transcriptional profiles of immune cells, we analyzed immune cell compositions, phenotype shifts, expression heterogeneities, and intercellular communication. In elderly patients with sepsis, innate immune cells (e.g., monocytes and DCs) exhibit decreased antigen presentation, presenting an overactive inflammatory and senescent phenotype. However, the immunophenotype of T cells shifted to characterize effector, memory, and exhaustion. Moreover, we identified strong interferon-γ responses of T cells in both aging and sepsis groups and a deranged inflammaging status in elderly sepsis patients. Tregs in elderly patients with sepsis showed increased abundance and enhanced immunosuppressive effects. In addition, metabolism-associated pathways were upregulated in T cells in elderly patients with sepsis, and the lysine metabolism pathway was enriched in Tregs. Cell–cell interaction analysis showed that the expression profile of ligand-receptor pairs was probably associated with aggravated immune dysfunction in elderly patients with sepsis. A novel HLA-KIR interaction was observed between Tregs and CD8 + T cells. These findings illustrate the immunological hallmarks of sepsis in elderly patients, and highlight that immunosuppressive and metabolic regulatory pathways may undergo important alterations in elderly patients with sepsis.

Comparative metabolomic analysis of minced grey mullet (Mugil cephalus) pasteurized by high hydrostatic pressure (HHP) during chilled storage

The beneficial antimicrobial effects of high hydrostatic pressures (HHP) treatments on chill-stored seafood are well documented. Less attention has been given to their impact on the metabolic profile of the seafood, which can offer valuable insights into the preservation mechanisms of these treatments. To address this gap, the present work describes the effects of HHP on the metabolome of chill-stored grey mullet using 1H-NMR. Samples were treated with HHP at 0, 400, 500, and 600 MPa for 10 min and stored at 2–4 °C. HHP effectively inactivated Lactobacillus spp., E. coli, Pseudomonas spp., total Coliforms, and sulfite-reducing anaerobic bacteria (AB), and significantly (p < 0.05) reduced the total mesophilic bacteria (TMB). Additionally, the microbiological shelf-life of grey mullet was extended from 9 to 35 days with the application of 600 MPa HHP. Unsupervised hierarchical cluster analysis and robust Principal Component Analysis (rPCA) revealed the overall changes in metabolites’ profile caused by HHP. HHP treatment significantly reduced the formation rate of decay-related metabolites, including hypoxanthine, trimethylamine (TMA), and biogenic amines, which significantly (p < 0.05) positively correlated with all considered microorganisms. A metabolic pathway analysis revealed several pathways that may underly the spoilage of grey mullet, including tyrosine metabolism, pyruvate metabolism, lysine metabolism, glycolysis/gluconeogenesis, butanoate metabolism, citrate cycle (TCA cycle), phenylalanine metabolism, and sulfur metabolism. Interestingly, among these pathways, lysine metabolism remained unaffected by the considered HHP treatments. These findings provide a better understanding of the mechanisms underlying the effects of HHP on chilled grey mullet.

Exploring altered free amino acids and metabolites: Insights into the metabolic landscape of preeclampsia

IntroductionPreeclampsia (PE) is a complex disease that poses a risk for maternal and perinatal morbidity and mortality. This study aimed to investigate the role of maternal serum amino acids (AAs) levels in PE. Materials and methodsA total of 56 pregnant women (26 with PE and 30 controls) were included in the study. The participants had a confirmed gestational age between 24 and 37 weeks. The mean body mass index (BMI) for the PE group was 33.1 kg/m2, while the control group had a mean BMI of 29.6 kg/m2. AAs levels were quantified, and statistical analyses were performed to identify significant differences between the two groups. Receiver Operating Characteristic (ROC) curve analysis was employed the diagnostic potential of specific AAs. ResultsWe observed significantly elevated levels of multiple AAs in the PE group, including citrulline, lysine, ethanolamine, ornithine and histidine. Citrulline exhibited exceptional predictive power for PE with 100.0% sensitivity and specificity at a cutoff of 7.79 µmol/L, reflected in an area under the curve (AUC) of 1.000. DiscussionOur study highlights the crucial involvement of altered amino acid levels, specifically in the urea cycle, disruptions in lysine and ethanolamine metabolism in PE development. Exploring these changes may reveal new therapeutic targets, providing insights into the disease's molecular mechanisms. Understanding amino acid metabolism in PE not only informs therapeutic strategies but also holds the potential to revolutionize early diagnosis and intervention.

Engineered probiotic cocktail with two cascade metabolic Escherichia coli for the treatment of hyperlysinemia.

Engineering probiotics have emerged as a potential strategy for the treatment of metabolic diseases. However, due to the exceptional complexity of these metabolic disorders and the intricate relationship between gut microbes, it is difficult to achieve an ideal therapeutic effect in a specific metabolic disorder using only a single engineered strain. In this work, we proposed a probiotic cocktail strategy by engineering two cascade metabolic bacteria to treat hyperlysinemia, an inherited lysine metabolic disorder with loss of α-aminoadipate semialdehyde synthase (AASS) activity. A probiotic E. coli Nissle 1917 strain EcNT (pTLS) with a heterologous enzyme pathway in Saccharomyces cerevisiae was engineered to metabolize the excess lysine. Another one EcNT (pK25) was engineered to consume the products of lysine metabolism. The bacterial cocktail enables the maintenance of a metabolic cascade with AASS-like functional activity to maintain the blood lysine concentrations and downstream metabolites. In vitro experimental results showed that the cocktail bacteria had a better metabolic capacity and metabolites balance at a ratio of EcNT (pTLS) and EcNT (pK25) of 1:2. Feeding of the cocktail bacteria to the mouse model effectively reduced the concentration of lysine and balanced saccharopine in the plasma of hyperlysinemia-like mice. These findings not only provide a promising strategy of probiotic stains for the treatment of hyperlysinemia but also highlight the potential of engineered cascade cocktails to intervene and even cure other inherited metabolic diseases.

NADPH Oxidase 4 Knockout in Dahl Salt-Sensitive Rats Impacts Kidney O2 Consumption and UCP2 Responses to a High Salt Diet

Rationale: The effects of a high salt (HS) diet upon renal metabolism and O2 utilization have not been extensively studied and there is a significant gap in our understanding of the role of oxidative stress in the effciency of energy production and substrate metabolism. The present study compared the effects of a HS diet (4% NaCl) on changes in O2 consumption and transcriptomic profiles in Dahl salt-sensitive (SS) rats to SS rats with a global knockout of NADPH oxidase 4 (NOX4) gene (SS Nox4−/−). Methods: Male SS (n=9) and SS Nox4−/− (n=10) rats were fed a 0.4% NaCl (LS) diet. At 7-8 weeks of age, the rats were implanted with a renal artery ultrasonic flow probe (Transonic) together with a femoral arterial catheter and a renal venous catheter. Renal blood flow (RBF) and mean arterial pressure (MAP) were measured continuously (24/7) and arterial (A) and renal venous (Vr) blood was sampled intermittently when rats were fed the LS and on days 7, 14, and 21 after switching to the HS diet. A and Vr blood O2 content was immediately measured by radiometer. From separate groups of rats subjected to the same protocol, the renal cortical tissue (Cx) and outer medulla (OM) were removed for mRNAseq analysis (Novogene, Inc). Results: When switching to the HS diet, the average 24-hour MAP of SS rats rose from 122 ± 2 to 140 ± 2 on HS7 to 164 ± 5 mmHg by HS21. In contrast, MAP in SS Nox4−/− rats increased from 121 ± 2 at LS to 132 ± 1 at HS7 to 152 ± 3 mmHg at HS21 (p&lt;0.05, compared to SS). RBF, normalized by changes of kidney weights obtained in another group of SS and SS Nox4−/− rats fed the same HS diet, SS rats exhibited a significant reduction of RBF over the 3 weeks of the HS diet averaging LS 7.2 ± 0.6, HS7 5.1 ± 0.5 and HS21 4.6 ± 0.7 mL/min/g kidney weight (gkw). This reduction of RBF was not observed in SS Nox4−/− rats (LS 6.8 ± 0.8, HS7 6.6 ± 0.6, HS21 6.0 ± 0.6 mL/min/gkw). The kidney O2 extraction ratio at LS tended to be lower in SS Nox4−/− (11.2 ± 1.7%) compared to SS (14.0 ± 1.1%) (p=0.10). When switched to the HS diet, O2 extraction was significantly reduced in the SS Nox4−/− rats reaching 8.3 ± 1.0% at HS21 (p&lt;0.05), while it did not change significantly in SS (12.7 ± 1.4%) at HS21. Notably, as determined by RNAseq analysis, Ucp2 expression in cortical tissue was significantly greater in SS fed HS than in SS Nox4−/−rats at HS21 . A gene enrichment analysis of the mRNAseq cortical tissue data (GSEA-KEGG pathways) focused on metabolic pathways indicated that knockout of Nox4 resulted in reduced expression of linoleic acid, lysine, and histidine metabolism pathways at LS when compared to SS. Those differences were not observed after HS feeding. However, upregulation of oxidative phosphorylation pathway was observed at HS21 in SS Nox4−/− when compared to SS rats. In the OM, a greater expression of genes associated with fatty acid degradation and carbon metabolism was observed in SS Nox4−/− rats when fed LS which was observed also at HS21. Conclusion: The preliminary results of this study suggest that reduced extraction of O2 in the SS Nox4−/− rats compared to SS rats may be partially explained by the differential response of Ucp2 to salt. Further studies are needed to determine whether the effciency of ATP production is enhanced in SS Nox4−/− as consequence of reduction of reactive oxygen species (e.g., H2O2) and the related downstream pathways such as phosphorylation of mTORC1. R01 HL151587, AHA 23POST1008714. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Analysis of Lysine Metabolism in a Rat Model of Type 2 Diabetes Reveals Modulation of Endocytosis and Glucose Metabolism

Lysine is an essential amino acid that serves as a building block for proteins and plays a role in metabolic processes. While a recent study provided evidence that lysine is beneficial for hypertension-associated kidney disease, possibly through inhibiting renal tubular reabsorption and forming new lysine conjugates, knowledge about the role of lysine in diabetic nephropathy (DN) is rudimentary. Therefore, the aim of the study was to investigate the role of lysine in kidney function in the setting of DN and its underlying mechanisms. We hypothesized that lysine may impact the kidneys in the following ways: 1) by mediating protein endocytosis in proximal tubules; 2) by altering protein abundance in the kidneys and other organs; and 3) by disrupting metabolic pathways through the formation of conjugates or degradation products. We investigated the effects of lysine on proximal tubule endocytosis and other organs using proteomic approaches and studied changes in lysine conjugates and metabolic products using targeted metabolomics. The results of urinary proteomics suggested that lysine’s impact on endocytosis may be associated with the inhibition of megalin and cubilin. Furthermore, lysine affected proteins related to glucose metabolism. Subsequently, we proceeded to investigate the influence of lysine on various organs in Type 2 Diabetic Nephropathy (T2DN) rats. Gene Ontology (GO) enrichment revealed that lysine exerts tissue-specific effects on different organs, with pathways enriched in the kidney including phagocytosis and enzyme inhibitor activity. Additionally, within the kidney, the lysine-treated group showed downregulation of glycolysis-related enzymes. The metabolomics results showed that lysine leads to a decrease in glucose and an increase in fructose 1,6-bisphosphate, while also resulting in an upregulation of related metabolites in the tricarboxylic acid cycle (TCA cycle). Our findings showed changes in the protein composition involved in lysine-mediated endocytosis and the impact of lysine on glucose metabolism enzymes and metabolites. The specific molecular mechanisms are still under investigation. R01 DK135644 and I01 BX004024 (to AS). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Dietary management for pyridoxine-dependent epilepsy due to α-aminoadipic semialdehyde dehydrogenase deficiency, a follow-on from the international consortium guidelines.

Pyridoxine-dependent epilepsy (PDE-ALDH7A1) is a neurometabolic disorder in the lysine metabolism pathway. In 2014 and 2021, the International PDE consortium published consensus guidelines about diagnosis and management. In this follow-on, a literature review was performed and nutrition management was evaluated through an international dietary questionnaire with 40 respondents. This manuscript discusses consensus dietary statements and the practical provision of lysine reduction therapies. Results from the questionnaire, statements from the PDE consensus guidelines, new data from the literature, as well as clinical practice experience of the metabolic dietitian group form the basis of these updated practical diet recommendations. These dietary management recommendations can support dietitians, nutritionists, and physicians in initiation and monitoring of lysine reduction therapies for PDE-ALDH7A1 patients and families.

Identifying plasma metabolic characteristics of major depressive disorder, bipolar disorder, and schizophrenia in adolescents

Major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SCZ) are classified as major mental disorders and together account for the second-highest global disease burden, and half of these patients experience symptom onset in adolescence. Several studies have reported both similar and unique features regarding the risk factors and clinical symptoms of these three disorders. However, it is still unclear whether these disorders have similar or unique metabolic characteristics in adolescents. We conducted a metabolomics analysis of plasma samples from adolescent healthy controls (HCs) and patients with MDD, BD, and SCZ. We identified differentially expressed metabolites between patients and HCs. Based on the differentially expressed metabolites, correlation analysis, metabolic pathway analysis, and potential diagnostic biomarker identification were conducted for disorders and HCs. Our results showed significant changes in plasma metabolism between patients with these mental disorders and HCs; the most distinct changes were observed in SCZ patients. Moreover, the metabolic differences in BD patients shared features with those in both MDD and SCZ, although the BD metabolic profile was closer to that of MDD than to SCZ. Additionally, we identified the metabolites responsible for the similar and unique metabolic characteristics in multiple metabolic pathways. The similar significant differences among the three disorders were found in fatty acid, steroid-hormone, purine, nicotinate, glutamate, tryptophan, arginine, and proline metabolism. Interestingly, we found unique characteristics of significantly altered glycolysis, glycerophospholipid, and sphingolipid metabolism in SCZ; lysine, cysteine, and methionine metabolism in MDD and BD; and phenylalanine, tyrosine, and aspartate metabolism in SCZ and BD. Finally, we identified five panels of potential diagnostic biomarkers for MDD-HC, BD-HC, SCZ-HC, MDD-SCZ, and BD-SCZ comparisons. Our findings suggest that metabolic characteristics in plasma vary across psychiatric disorders and that critical metabolites provide new clues regarding molecular mechanisms in these three psychiatric disorders.

One-carbon metabolites supplementation and nutrient restriction alter the fetal liver metabolomic profile during early gestation in beef heifers.

Maternal nutrition is pivotal for proper fetal development, with one-carbon metabolites (OCM) playing a key role in fetal epigenetic programming through DNA and histone methylation. The study aimed to investigate the effects of nutrient restriction and OCM supplementation on fetal liver metabolomics in pregnant beef-heifers, focusing on metabolites and pathways associated with amino acid, vitamin and cofactor, carbohydrate, and energy metabolism at day 63 of gestation. Thirty-one crossbred Angus heifers were artificially inseminated and allocated to 4 nutritional treatments in a 2 × 2 factorial arrangement of treatments, with the 2 factors being dietary intake/rate of gain (control-diet [CON]; 0.60kg/d ADG, vs. restricted-diet [RES]; -0.23kg/d ADG) and OCM supplementation (supplemented [+OCM] vs. not supplemented [-OCM]). The resulting treatment groups-CON - OCM, CON + OCM, RES - OCM, and RES + OCM were maintained for 63 day post-breeding. Following this period, fetal liver tissues were collected and subjected to metabolomic analysis using UPLC-tandem mass-spectrometry. We identified 288 metabolites, with the majority (n = 54) being significantly influenced by the main effect of gain (P ≤ 0.05). Moreover, RES showed decreased abundances of most metabolites in pathways such as lysine metabolism; leucine, isoleucine, and valine metabolism; and tryptophan metabolism, compared to CON. Supplementation with OCM vs. no OCM supplementation, resulted in greater abundance of metabolites (P ≤ 0.05) affecting pathways associated with methionine, cysteine, S-adenosylmethionine and taurine metabolism; guanidino and acetamido metabolism; and nicotinate and nicotinamide metabolism. Notably, OCM supplementation with a moderate rate of gain increased the concentrations of ophthalmate, N-acetylglucosamine, and ascorbic-acid 3-sulfate, which are important for proper fetal development (P ≤ 0.05). Nutrient restriction reduced the majority of liver metabolites, while OCM supplementation increased a smaller number of metabolites. Thus, OCM supplementation may be protective of metabolite concentrations in key developmental pathways, which could potentially enhance fetal development under nutrient-restricted conditions.

Metabolic changes preceding bladder cancer occurrence among Korean men: a nested case-control study from the KCPS-II cohort

BackgroundBladder cancer (BLCA) research in Koreans is still lacking, especially in focusing on the prediction of BLCA. The current study aimed to discover metabolic signatures related to BLCA onset and confirm its potential as a biomarker.MethodsWe designed two nested case-control studies using Korean Cancer Prevention Study (KCPS)-II. Only males aged 35–69 were randomly selected and divided into two sets by recruitment organizations [set 1, BLCA (n = 35) vs. control (n = 35); set 2, BLCA (n = 31) vs. control (n = 31)]. Baseline serum samples were analyzed by non-targeted metabolomics profiling, and OPLS-DA and network analysis were performed. Calculated genetic risk score (GRS) for BLCA from all KCPS participants was utilized for interpreting metabolomics data.ResultsCritical metabolic signatures shown in the BLCA group were dysregulation of lysine metabolism and tryptophan-indole metabolism. Furthermore, the prediction model consisting of metabolites (lysine, tryptophan, indole, indoleacrylic acid, and indoleacetaldehyde) reflecting these metabolic signatures showed mighty BLCA predictive power (AUC: 0.959 [0.929–0.989]). The results of metabolic differences between GRS-high and GRS-low groups in BLCA indicated that the pathogenesis of BLCA is associated with a genetic predisposition. Besides, the predictive ability for BLCA on the model using GRS and five significant metabolites was powerful (AUC: 0.990 [0.980–1.000]).ConclusionMetabolic signatures shown in the present research may be closely associated with BLCA pathogenesis. Metabolites involved in these could be predictive biomarkers for BLCA. It could be utilized for early diagnosis, prognostic diagnosis, and therapeutic targets for BLCA.

Integrative physiology of lysine metabolites.

Lysine is an essential amino acid that serves as a building block in protein synthesis. Beside this, lysine's metabolic activity has only recently been unraveled. Lysine metabolism is tissue specific and is linked to several renal, cardiovascular and endocrinological diseases through human metabolomics datasets. As a free molecule, lysine takes part in antioxidant response, engages in protein modifications and its chemistry shapes both proteome and metabolome. In the proteome, it is an acceptor for a plethora of posttranslational modifications. In the metabolome it can be modified, conjugated and degraded. Here, we provide an update on integrative physiology of mammalian lysine metabolites such as α-aminoadipic acid, saccharopine, pipecolic acid, and lysine conjugates such as acetyl-lysine, and sugar-lysine conjugates such as advanced glycation end products. We also comment on their emerging associative and mechanistic links to renal disease, hypertension, diabetes and cancer.