Metabolites

12 pages, 12206 KB

Open AccessArticle

Efficacy of Oral Vitamin K2 Supplementation in Experimental Knee Osteoarthritis

by Emre Uzun, İbrahim Tekeoğlu, Hüseyin Çakıroğlu, Özcan Budak, Elvan Şahin, Kemal Nas, Muhammed Zahid Sahin and Ayhan Kamanlı

Metabolites 2026, 16(6), 425; https://doi.org/10.3390/metabo16060425 (registering DOI) - 17 Jun 2026

Abstract

Background/Objectives: Although vitamin K has been implicated in osteoarthritis pathophysiology, the specific effects of vitamin K2 (menaquinone) on cartilage degeneration remain poorly characterized. This study aimed to investigate the effect of oral vitamin K2 supplementation in a monosodium iodoacetate-induced osteoarthritis model. Methods [...] Read more.

Background/Objectives: Although vitamin K has been implicated in osteoarthritis pathophysiology, the specific effects of vitamin K2 (menaquinone) on cartilage degeneration remain poorly characterized. This study aimed to investigate the effect of oral vitamin K2 supplementation in a monosodium iodoacetate-induced osteoarthritis model. Methods: Twenty-four male Sprague Dawley rats were included in the study and divided into 3 equal groups: sham group, control (osteoarthritis) group, and treatment group. Saline was applied to the right knee of the sham group, and MIA was applied intra-articularly to the right knee of the control and treatment groups to create an osteoarthritis model. Rats in the treatment group were given 8 micrograms (μg)/day of vitamin K2 orally in addition to the standard diet. After 28 days of follow-up, all rats were euthanized. The right knee articular cartilage was examined histologically with Hematoxylin–Eosin and Safranin O and immunohistochemically with type II collagen alpha 1 and Matrix Metalloproteinase-13. Results: Histological evaluation demonstrated significantly lower Mankin scores in the treatment group (4.25 ± 0.83) compared with the control group (11.10 ± 0.83). Immunohistochemical analysis showed more intense type II collagen staining and reduced matrix metalloproteinase-13 staining in the treatment group relative to the control group. Conclusions: Oral vitamin K2 administration was associated with reduced cartilage degeneration and improved matrix preservation at the 28-day endpoint in an induced MIA osteoarthritis rat model. Full article

(This article belongs to the Section Nutrition and Metabolism)

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17 pages, 12815 KB

Open AccessArticle

Gut–Liver Axis Mechanisms Underlying Spontaneous Reversal of Liver Fibrosis: A Gut Microbiota-Metabolomics Analysis

by Yuanying Zhao, Hao Chang, Chenxue Hou, Bingqing Yang and Yue Li

Metabolites 2026, 16(6), 424; https://doi.org/10.3390/metabo16060424 (registering DOI) - 17 Jun 2026

Abstract

Background: The reversal of liver fibrosis is crucial for improving outcomes in chronic liver disease. The gut–liver axis, mediated by the intestinal microbiota, plays a significant role in this process. However, its dynamic changes and mechanisms during reversal remain unclear. This study aimed [...] Read more.

Background: The reversal of liver fibrosis is crucial for improving outcomes in chronic liver disease. The gut–liver axis, mediated by the intestinal microbiota, plays a significant role in this process. However, its dynamic changes and mechanisms during reversal remain unclear. This study aimed to systematically reveal these dynamics and explore the link between gut microbiota and metabolism in a spontaneous reversal model. Methods: Intestinal contents were collected from mouse model groups (fibrosis, 4-week reversal, and 12-week reversal). The use of 16S rRNA gene sequencing was employed to analyze gut microbiota structure, and untargeted metabolomics was used to profile metabolic changes. Differential metabolites and microbial taxa were identified using multivariate statistical analysis, followed by pathway enrichment analysis. Spearman correlation analysis was used to construct metabolite–microbiota association networks across different reversal stages. Results: Metabolomic analysis showed significant alterations in multiple pathways during reversal. Linoleic and α-linolenic acid metabolism had a high impact in later stages. Taurine and biotin metabolism remained active throughout. Branched-chain amino acid degradation was enriched later. Microbiota analysis revealed significant structural shifts via beta-diversity. Bacteroidota decreased while Firmicutes increased in 4 weeks. Butyrate-producing families increased, and Akkermansia was enriched later. Integrated analysis demonstrated significant correlations between specific bacteria and metabolites, indicating a close microbiota–metabolism association during reversal. Conclusions: This integrated multi-omics study delineates the potential dynamic reorganization of the gut microbiota and host metabolism during spontaneous liver fibrosis reversal. These findings provide a theoretical basis for understanding the gut–liver axis mechanism in fibrosis reversal and for developing microbiota-targeted intervention strategies. Full article

(This article belongs to the Special Issue Lipid Metabolism in Chronic Diseases)

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27 pages, 7550 KB

Open AccessArticle

Malic Enzyme 1 Limits Acetaminophen-Induced Liver Injury by Sustaining Redox and Bioenergetic Homeostasis

by Chang Guo and Zizhi Tang

Metabolites 2026, 16(6), 423; https://doi.org/10.3390/metabo16060423 (registering DOI) - 16 Jun 2026

Abstract

Background: Acetaminophen (APAP) overdose remains a major cause of acute liver injury. Although N-acetylcysteine (NAC) is the clinically established antidote for APAP toxicity, its efficacy is greatest when administered early, and additional therapeutic strategies are still needed for patients with delayed presentation [...] Read more.

Background: Acetaminophen (APAP) overdose remains a major cause of acute liver injury. Although N-acetylcysteine (NAC) is the clinically established antidote for APAP toxicity, its efficacy is greatest when administered early, and additional therapeutic strategies are still needed for patients with delayed presentation or progressive injury. Because APAP hepatotoxicity involves coupled disturbances in redox control, mitochondrial performance, and cellular metabolism, metabolic enzymes that sustain NADPH availability may critically influence disease severity. Malic enzyme 1 (ME1), a cytosolic NADPH-generating enzyme, has not been functionally defined in this context. Methods: To determine the contribution of ME1 to APAP-induced liver injury (AILI), we used hepatocyte-specific ME1 knockout mice, hepatic overexpression and reconstitution approaches, primary mouse hepatocytes, and an enzymatically inactive ME1 mutant. Liver injury and associated changes in oxidative stress, mitochondrial function, energy metabolism, autophagic flux, and endoplasmic reticulum (ER) stress were evaluated using biochemical, histological, molecular, and ultrastructural analyses, together with pharmacological interventions. Results: Genetic loss of ME1 did not substantially alter early APAP metabolic activation-related indices, including APAP-protein adduct formation, but markedly increased hepatocellular metabolic vulnerability after APAP challenge. This phenotype was characterized by enhanced lipid peroxidation, impaired mitochondrial polarization, reduced ATP availability, defective autophagic flux, and amplified ER stress, leading to more severe liver damage. In contrast, ME1 overexpression or reconstitution promoted a more adaptive metabolic response and limited tissue injury. These effects depended largely on ME1 catalytic activity, as protection was markedly weakened with the mutant enzyme. Pharmacological analyses further supported the involvement of AMPK/mTOR-associated autophagy regulation and ER stress adaptation in the downstream actions of ME1. Malic acid also partially attenuated APAP-induced hepatotoxicity in vivo and in vitro. Conclusions: ME1 functions as an endogenous metabolic factor that influences the outcome of APAP-induced liver injury. Its catalytic activity supports hepatocyte survival primarily by preserving reductive capacity, bioenergetic balance, and adaptive stress responses, rather than by altering APAP metabolic activation. Full article

(This article belongs to the Section Cell Metabolism)

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15 pages, 970 KB

Open AccessArticle

Sex Differences in the Socioeconomic Gradient of Latent Cardiometabolic Phenotypes in a Working-Age Population from the Balearic Islands (Spain): A Population-Based Analysis

by María Teófila Vicente-Herrero, Pedro J. Tárraga López, Carla Busquets-Cortés, Lluis Rodas Cañellas, Ángel Arturo López González and José Ignacio Ramírez-Manent

Metabolites 2026, 16(6), 422; https://doi.org/10.3390/metabo16060422 (registering DOI) - 16 Jun 2026

Abstract

Background: Cardiometabolic diseases are shaped by complex interactions between biological and social determinants. While socioeconomic inequalities in cardiometabolic risk are well established, less is known about how these inequalities are distributed across multidimensional cardiometabolic phenotypes and whether they differ by sex. Objective: We [...] Read more.

Background: Cardiometabolic diseases are shaped by complex interactions between biological and social determinants. While socioeconomic inequalities in cardiometabolic risk are well established, less is known about how these inequalities are distributed across multidimensional cardiometabolic phenotypes and whether they differ by sex. Objective: We aimed to examine sex differences in the socioeconomic gradient of cardiometabolic phenotypes using latent class analysis in a working-age population. Methods: A cross-sectional study was conducted in 3108 adults aged 18–65 years undergoing occupational health assessments in the Balearic Islands (Spain). Educational level was used as an indicator of socioeconomic position. Cardiometabolic risk was assessed using obesity, insulin resistance (METS-IR), metabolic dysfunction-associated steatotic liver disease (FLI), atherogenic index of plasma, and metabolic syndrome. Latent class analysis was applied to identify cardiometabolic phenotypes. Multinomial logistic regression models stratified by sex and interaction analyses were used to assess associations between educational level and class membership. Tests for linear trend and predicted probabilities were also estimated. Results: Four cardiometabolic phenotypes were identified: low-risk (40.8%), obesity-dominant (24.1%), dysmetabolic (19.3%), and high-risk multimorbid (15.8%). A clear socioeconomic gradient was observed, with lower educational attainment associated with a higher likelihood of belonging to adverse cardiometabolic profiles. This gradient was stronger among women. For the high-risk multimorbid class, the relative risk ratio comparing low vs. high educational level was 1.82 (95% CI 1.34–2.46) in men and 2.47 (95% CI 1.68–3.64) in women (p for interaction = 0.012). A significant linear trend across educational levels was observed in both sexes (p for trend < 0.001). Predicted probabilities further confirmed a steeper increase in high-risk profiles among women with lower educational attainment. Conclusions: Cardiometabolic risk is structured into distinct phenotypic profiles that are socially patterned. Socioeconomic inequalities are strongly associated with adverse cardiometabolic phenotypes, with a more pronounced gradient among women. These findings highlight the need for gender-sensitive strategies addressing social determinants to reduce cardiometabolic health inequalities. Full article

(This article belongs to the Special Issue Exploring Pathological Mechanisms in Obesity, Diabetes, and Metabolic Syndrome: 2nd Edition)

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16 pages, 590 KB

Open AccessReview

Ceramide-Driven Mechanisms in Pulmonary Fibrosis

by Zifan Li, Yaqian Li, Na Mao, Xuemin Gao, Hong Xu, Wenchen Cai and Tian Li

Metabolites 2026, 16(6), 421; https://doi.org/10.3390/metabo16060421 (registering DOI) - 16 Jun 2026

Abstract

Pulmonary fibrosis, particularly idiopathic pulmonary fibrosis (IPF), is a chronic and progressive interstitial lung disease characterized by alveolar epithelial injury, fibroblast activation, and excessive extracellular matrix deposition, which collectively lead to respiratory failure. Despite the availability of antifibrotic agents, disease-modifying therapies remain limited. [...] Read more.

Pulmonary fibrosis, particularly idiopathic pulmonary fibrosis (IPF), is a chronic and progressive interstitial lung disease characterized by alveolar epithelial injury, fibroblast activation, and excessive extracellular matrix deposition, which collectively lead to respiratory failure. Despite the availability of antifibrotic agents, disease-modifying therapies remain limited. Emerging evidence has identified dysregulated sphingolipid metabolism, especially ceramide accumulation, as a key driver of fibrotic pathogenesis. Ceramide is a central bioactive lipid in the sphingolipid pathway that regulates multiple cellular processes, including apoptosis, inflammation, endothelial barrier dysfunction, and fibroblast activation, all of which contribute to pulmonary fibrosis. This review is a narrative review that systematically summarizes the biosynthetic and metabolic pathways of ceramide, with an emphasis on chain length-specific functions and the ceramide to S1P rheostat. We further discuss the mechanistic roles of ceramide in alveolar epithelial cell apoptosis, inflammatory responses, and vascular barrier disruption in fibrotic lung disease. Finally, we highlight emerging therapeutic strategies that target ceramide metabolism, including inhibitors of acid sphingomyelinase (ASMase) and serine palmitoyltransferase (SPT), and propose future directions for clinical translation. Full article

(This article belongs to the Special Issue Advances in Immune Metabolism: Lipid Regulation and Disease Outcomes)

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17 pages, 6525 KB

Open AccessArticle

Melatonin Modulates Macrophage Polarization and Immunometabolic Responses in the Colostrum of Obese Mothers

by Silvia Hannah Bilotti Ratto Gomes da Silva, Danielle Cristina Honorio França, Kênia Maria Resende Silva, Emanuelle Carolina Honorio França, Viviane Francelina Luz, Arce dos Santos Sfredo, Tassiane Cristina Morais, Eduardo Luzía França and Adenilda Cristina Honorio-França

Metabolites 2026, 16(6), 420; https://doi.org/10.3390/metabo16060420 (registering DOI) - 15 Jun 2026

Abstract

Background/Objectives: Obesity is a major public health problem associated with chronic inflammation and functional alterations in multiple organs and systems. Few studies have examined colostrum from obese mothers, particularly with respect to macrophage function, enzyme and cytokine concentrations, and the role of [...] Read more.

Background/Objectives: Obesity is a major public health problem associated with chronic inflammation and functional alterations in multiple organs and systems. Few studies have examined colostrum from obese mothers, particularly with respect to macrophage function, enzyme and cytokine concentrations, and the role of melatonin in immune modulation. This study aimed to evaluate melatonin levels and their effects on macrophage polarization, cytokine concentrations, nitric oxide synthase [iNOS], and arginase in colostrum from obese mothers. Colostrum samples were collected from eutrophic mothers [BMI: 18.5–24.9 kg/m²] and obese mothers [BMI: ≥30 kg/m²]. Methods: Macrophages were isolated by density gradient and treated with melatonin. The expression of M1 and M2 macrophages and cytokine concentrations were assessed by flow cytometry, while melatonin levels in colostrum supernatants, iNOS, and arginase in cell lysates were determined by ELISA. Results: An endogenous increase in melatonin was also observed in the colostrum of obese mothers. Maternal obesity has been shown to reduce M1 and M2 macrophage expression, increase nitric oxide synthase [NOS] activity, and elevate interleukin-6 [IL-6] and interleukin-17 [IL-17] levels. However, melatonin treatment restored M1 and M2 macrophage levels and reduced inducible nitric oxide synthase [iNOS] and arginase production to levels similar to those observed in mothers of healthy weight. Conclusions: these findings suggest that maternal obesity creates a pro-inflammatory environment in colostrum, characterized by altered macrophage polarization, altered cytokine secretion, and an imbalance in the enzymatic activities of iNOS and arginase within the L-arginine metabolic pathway. Both natural and supplemental melatonin exhibited immunomodulatory, antioxidant, and anti-inflammatory effects, helping to restore immune balance in colostrum. These results emphasize the potential benefits of melatonin as an immunometabolic modulator and its contribution to understanding immunometabolic regulation in obese mothers. Full article

(This article belongs to the Special Issue Effects of Nutrition Intake and Lifestyle Intervention on Human Metabolic Health)

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22 pages, 9169 KB

Open AccessArticle

Identification and Transcriptomic Analysis of Mitochondria-Related Gene Signatures in Obesity

by Hezhang Yun, Chang Liu, Binghong Gao and Peijie Chen

Metabolites 2026, 16(6), 419; https://doi.org/10.3390/metabo16060419 (registering DOI) - 15 Jun 2026

Abstract

Objectives: This study aimed to identify core genes associated with mitochondria-related transcriptomic signatures and evaluate their potential as computational biomarkers, immune characteristics, regulatory mechanisms, and potential therapeutic relevance. Methods: Obesity-related transcriptome datasets were obtained from the GEO database. Differentially expressed genes [...] Read more.

Objectives: This study aimed to identify core genes associated with mitochondria-related transcriptomic signatures and evaluate their potential as computational biomarkers, immune characteristics, regulatory mechanisms, and potential therapeutic relevance. Methods: Obesity-related transcriptome datasets were obtained from the GEO database. Differentially expressed genes (DEGs) were intersected with mitochondria-related genes (MRGs) to identify obesity-related MRGs. Functional enrichment, protein–protein interaction (PPI) analysis, CytoHubba, LASSO and random forest algorithms were used to screen core genes. External validation, ROC analysis, immune infiltration analysis, regulatory network construction, candidate drug prediction, and molecular docking were further performed. Results: A total of 527 DEGs and 15 differentially expressed MRGs were identified. Enrichment analysis suggested that these mitochondria-related genes were mainly associated with disrupted mitochondrial energy metabolism, lipid metabolic remodeling, and altered substrate utilization. ECHDC2, FASN, NAT8L, and AASS were identified as core MRGs; these genes are respectively associated with mitochondrial metabolic regulation, de novo fatty acid synthesis, N-acetylaspartate-related mitochondrial metabolism, and lysine degradation. These genes were significantly downregulated in obesity and showed good diagnostic performance. Immune infiltration analysis revealed alterations in the immune microenvironment, and the core genes were negatively correlated with multiple immune cell types. Molecular docking showed that Genistein had the lowest predicted binding free energy with NAT8L (−8.89 kcal/mol), suggesting relatively favorable binding among the tested ligand–target pairs. Conclusions: ECHDC2, FASN, NAT8L, and AASS may serve as candidate computational biomarkers, among which FASN represents a known lipid metabolism-related gene, supporting the biological plausibility of the workflow. Full article

(This article belongs to the Special Issue Obesity and Metabolic Health, 2nd Edition)

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23 pages, 8041 KB

Open AccessArticle

Gɑ_q Is a Heterotrimeric G-Protein Subunit That Directs the Selectivity of PPARγ-Induced Gene Pathways Toward Energy-Related Processes Rather than Adiposity

by Evelyn A. Bates, Zachary A. Kipp, Wang-Hsin Lee, Genesee J. Martinez, Sally N. Pauss, Philipp E. Scherer and Terry D. Hinds, Jr.

Metabolites 2026, 16(6), 418; https://doi.org/10.3390/metabo16060418 (registering DOI) - 15 Jun 2026

Abstract

Background/Objectives: Signaling mediators of PPARγ influence pathways involved in adipogenesis, lipid storage, inflammation, energy-related processes, and glucose utilization. Recent research indicates that PPARγ coregulators, recruited or released during ligand binding, govern specific gene pathways. It was recently discovered that Gα_q, a [...] Read more.

Background/Objectives: Signaling mediators of PPARγ influence pathways involved in adipogenesis, lipid storage, inflammation, energy-related processes, and glucose utilization. Recent research indicates that PPARγ coregulators, recruited or released during ligand binding, govern specific gene pathways. It was recently discovered that Gα_q, a heterotrimeric G protein subunit, also signals to PPARγ and may significantly affect adipogenesis and glucose sensitivity. Methods: To explore Gα_q’s role in adipocytes, we generated CRISPR-mediated Gα_q (Gnaq) knockout (Gnaq KO) and scramble control cells from 3T3-L1 preadipocytes. Results: The absence of Gα_q resulted in increased lipid accumulation and elevated serine 273 (but not serine 112) phosphorylation of PPARγ. Gα_q deficiency also decreased mitochondrial abundance and respiration in response to PPARγ ligands such as rosiglitazone, pioglitazone, and troglitazone. RNA sequencing comparing differentiated Gnaq KO and control adipocytes identified over 800 differentially expressed genes, including those associated with enhanced lipid metabolism and reduced inflammation. Corresponding PamGene kinome profiling showed increased serine/threonine kinase activity and decreased phosphotyrosine kinase signaling in Gnaq KO adipocytes. Conclusions: These findings support Gα_q as a regulator of adipocyte function, linking kinase signaling pathways to PPARγ-mediated transcription. This research provides mechanistic insights into targeting Gα_q as a potential treatment for individuals with obesity and metabolic disorders. Full article

(This article belongs to the Special Issue Interplay Between Metabolism, Oxidative Stress, and Cellular Signaling in Health and Disease)

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19 pages, 347 KB

Open AccessReview

Roles of Metabolites Unveiled by Metabolomics in Brassica rapa, B. napus and B. juncea

by Yunong Xia, Silin Su, Xianyu Tang, Lei Qin, Junxing Lu and Shitou Xia

Metabolites 2026, 16(6), 417; https://doi.org/10.3390/metabo16060417 (registering DOI) - 15 Jun 2026

Abstract

Rapeseed is a major source of vegetable oil and contains a wide variety of metabolites. Recent advances, particularly the integration of metabolomics with other omics approaches, have enabled not only comprehensive but also detailed analyses of key metabolites that respond to specific conditions. [...] Read more.

Rapeseed is a major source of vegetable oil and contains a wide variety of metabolites. Recent advances, particularly the integration of metabolomics with other omics approaches, have enabled not only comprehensive but also detailed analyses of key metabolites that respond to specific conditions. To date, these recent advances in the metabolomics of Brassica crops have not yet been fully clarified. In this review, we seek to summarize the recent progresses in metabolomics studies of Brassica rapa, B. napus and B. juncea, introduce the key metabolites spanning nucleic acids, amino acids, fatty acids, lipids, organic acids, alkaloids, phenylpropanoids, terpenoids, flavonoids and glucosinolates uncovered by this approach, focusing on those associated with growth and development, and abiotic/biotic stresses, including macronutrient availability, temperature, water stress, salt stress, aluminum and cadmium toxicity, and infection of Sclerotinia sclerotiorum, Leptosphaeria maculans, and Plasmodiophora brassicae. Future perspectives and current challenges in metabolomics integrating with other omics are also discussed, along with its potential for breeding applications, especially in new marker discovery, trait prediction, and even metabolic selection, aimed at developing new rapeseed varieties with stable, high-yielding, and quality traits. Full article

(This article belongs to the Special Issue Metabolomics and Plant Defence, 2nd Edition)

24 pages, 16704 KB

Open AccessArticle

Immunometabolic Stratification of Autism Spectrum Disorder by CD4⁺ T-Cell Phenotype Reveals Subtype-Specific Energetic Deficit and Coordinated Suppression of Micronutrient Acquisition Pathways

by Albion Dervishi

Metabolites 2026, 16(6), 416; https://doi.org/10.3390/metabo16060416 (registering DOI) - 15 Jun 2026

Abstract

Background: Autism spectrum disorder (ASD) is associated with immune dysregulation in a subset of individuals, though findings remain heterogeneous and poorly defined, particularly regarding immune subtypes and metabolic context. Methods: We analyzed whole-blood microarray data from GSE18123 (GPL570: ASD n = 46, controls [...] Read more.

Background: Autism spectrum disorder (ASD) is associated with immune dysregulation in a subset of individuals, though findings remain heterogeneous and poorly defined, particularly regarding immune subtypes and metabolic context. Methods: We analyzed whole-blood microarray data from GSE18123 (GPL570: ASD n = 46, controls n = 19; GPL6244: ASD n = 68, controls n = 21) using an integrated immunometabolic framework. CD4⁺ T-cell transcriptional programs were used to assign dominant immune phenotypes (TH1, TH2, TH17, Tfh, FOXP3⁺ Treg, Tr1-like). Metabolic demand was quantified via the τ-axis; execution capacity was assessed using cytosolic and mitochondrial energy compensation ratios (CECR, MECR). Induction–execution mismatch was captured by three Gap metrics (Cytosolic, Warburg, Global). Functional validation correlated these metrics with transcriptional signatures of folate transport, one-carbon metabolism, receptor-mediated micronutrient uptake (LRP2–CUBN–AMN), cobalamin processing, and vitamin D activation across both platforms. Results: Six immunometabolic CD4⁺ subtypes were identified within ASD. τ-axis discrimination was strongest for Tr1-like (AUC = 0.811) and Tfh (AUC = 0.825) states, while TH17 profiles were indistinguishable from controls. Despite variation in metabolic demand, CECR and MECR remained relatively preserved, indicating decoupling between induction and execution capacity. Global Gap values were most negative in Tfh and TH1 states and positive in TH17 and controls. Negative Gap states showed coordinated suppression of ATP-intensive micronutrient acquisition pathways, including folate transport (FOLR1/2, SLC19A1), megalin–cubilin-mediated uptake (r ≈ 0.77–0.79), and vitamin D activation (CYP27B1). Intracellular cobalamin processing was upregulated in proportion to metabolic demand (r > 0.9). Findings were directionally replicated across both datasets. Conclusions: These data demonstrate that ASD exhibits structured immunometabolic heterogeneity characterized by subtype-specific demand–capacity imbalance. The Global Gap framework provides transcriptomic evidence of energetic deficit in Tfh- and Tr1-like-dominant states. Future clinical studies should incorporate subtype-stratified assessment of micronutrient status and metabolic execution capacity. Full article

(This article belongs to the Special Issue Computational Modeling of Metabolite-Modulated Cellular Processes)

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17 pages, 777 KB

Open AccessArticle

Discriminative Ability of TyG, TyG-WC, BAI, FGIR, and QUICKI Indexes in Identifying Metabolic Syndrome in a Pediatric Population with Obesity

by Sofia Tamini, Adele Bondesan, Diana Caroli, Francesca Frigerio and Alessandro Sartorio

Metabolites 2026, 16(6), 415; https://doi.org/10.3390/metabo16060415 (registering DOI) - 14 Jun 2026

Abstract

Background/Objectives: Pediatric obesity is closely associated with metabolic syndrome (MetS), a condition linked to increased cardiometabolic risk. Early identification of high-risk individuals remains challenging. This study aimed to evaluate the diagnostic performance of selected anthropometric, metabolic dysfunction and insulin resistance indexes for [...] Read more.

Background/Objectives: Pediatric obesity is closely associated with metabolic syndrome (MetS), a condition linked to increased cardiometabolic risk. Early identification of high-risk individuals remains challenging. This study aimed to evaluate the diagnostic performance of selected anthropometric, metabolic dysfunction and insulin resistance indexes for identifying MetS in children and adolescents with obesity. Methods: In this retrospective, cross-sectional, single-center study, 758 children and adolescents with obesity (mean age 14.8 ± 2.1 years; 59.9% females) hospitalized for a body weight-reduction program were included. MetS was defined according to International Diabetes Federation criteria, in which central obesity is a mandatory diagnostic component. The triglyceride–glucose (TyG), TyG–waist circumference (TyG-WC), body adiposity index (BAI), fasting glucose-to-insulin ratio (FGIR), and quantitative insulin sensitivity check index (QUICKI) were calculated. Receiver operating characteristic curve analysis was used to assess their discriminative ability. Results: The prevalence of MetS was 27.8% and was significantly higher in males than females (34.9% vs. 23.1%, p < 0.0001). TyG and TyG-WC showed the best discriminative performance (AUC 0.75 and 0.76, respectively), although with only moderate sensitivity and specificity. FGIR and QUICKI demonstrated lower accuracy (AUC 0.64 and 0.63), whereas BAI showed no discriminative ability (AUC 0.48). These findings were consistent across sexes, although sex-specific differences in both MetS prevalence and optimal cut-off values were observed. Correlation analyses confirmed moderate associations between TyG-based indexes and MetS, whereas other indexes showed weaker relationships. Conclusions: In the present cohort of children and adolescents with obesity, TyG and TyG-WC showed the best performance in identifying MetS compared with the other evaluated indexes. However, their performance remained moderate, and the proposed cut-off values require validation in independent populations. These indexes may represent simple supportive screening and risk-stratification tools but should be used alongside comprehensive clinical assessment and established diagnostic criteria rather than as stand-alone diagnostic measures. Full article

(This article belongs to the Section Endocrinology and Clinical Metabolic Research)

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22 pages, 3444 KB

Open AccessArticle

Temperature-Dependent Modulation of Cardiac Metabolism, Post-Injury Survival and Regenerative Rate in Axolotls

by Anita Dittrich, Sofie Amalie Andersson, Aage Kristian Olsen Alstrup, Pernille Lajer Sørensen, Mette Irene Theilgaard Simonsen, Maibritt Hald Arildsen, Rasmus Roost Aabling and Henrik Lauridsen

Metabolites 2026, 16(6), 414; https://doi.org/10.3390/metabo16060414 (registering DOI) - 13 Jun 2026

Abstract

Background/Objectives: Cardiac regenerative ability varies in vertebrates. Adult mammals cannot mount a regenerative response, while fetal mammals and some salamanders and teleosts fully regenerate the heart after a cryoinjury mimicking a myocardial infarction. This contrast is suggested to be regulated in part [...] Read more.

Background/Objectives: Cardiac regenerative ability varies in vertebrates. Adult mammals cannot mount a regenerative response, while fetal mammals and some salamanders and teleosts fully regenerate the heart after a cryoinjury mimicking a myocardial infarction. This contrast is suggested to be regulated in part by metabolism, with high regenerative capacity correlating with a comparatively lower mass-specific metabolic rate, ectothermy rather than endothermy and a metabolic phenotype favoring glycolysis in cardiac muscle. Methods: In this physiological study on axolotl salamanders, we altered the housing temperatures from the standard 20 °C to 10 °C, 25 °C and 30 °C and assayed key metabolic parameters as well as cardiac function, survival and regenerative capacity. Results: Our study demonstrated that while axolotls could be housed at temperatures ranging from 10 °C to 30 °C in an uninjured state, signs of a pathological response involving cardiac and metabolic insufficiency and mortality, especially after cryoinjury, increased progressively with increasing temperatures. We observed several metabolic effects, including differences in oxygen consumption, plasma metabolites and cardiac function. Cardiac regeneration after cryoinjury progressed as expected with only a small remaining injury after 60 days at the standard housing temperature of 20 °C. Regeneration was highly reduced in a reversible manner at 10 °C while regenerative rate was not affected at 25 °C. At 30 °C, cardiac regeneration could not be evaluated as the majority of animals (five out of six) did not survive the injury, likely reflecting insufficient cardiac reserve capacity to simultaneously sustain thermal metabolic effects and support tissue repair. Conclusions: The ectothermic axolotl undergoes several metabolic changes when exposed to different housing temperatures, with heart regeneration showing a narrower permissive temperature range than survival of the axolotl in an uninjured state. Full article

(This article belongs to the Special Issue Metabolism of Ectotherms: Insights from Amphibians and Reptiles)

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14 pages, 5665 KB

Open AccessArticle

High-Intensity Interval Training Attenuates Hepatic Fibrosis by Remodeling Lactate Metabolism in MASLD

by Xuefei Chen, Jie Su, Wenhua Huang, Yanjun Li and Jing Zhang

Metabolites 2026, 16(6), 413; https://doi.org/10.3390/metabo16060413 (registering DOI) - 13 Jun 2026

Abstract

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as a global metabolic disorder. As a non-pharmacological intervention, the effects of high-intensity interval training (HIIT) on MASLD and its molecular mechanisms remain poorly understood. This study aimed to investigate whether HIIT could [...] Read more.

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as a global metabolic disorder. As a non-pharmacological intervention, the effects of high-intensity interval training (HIIT) on MASLD and its molecular mechanisms remain poorly understood. This study aimed to investigate whether HIIT could ameliorate high-fat diet (HFD)-induced liver fibrosis by recalibrating the intrahepatic lactate metabolic axis. Methods: An HFD-induced murine MASLD model combined with HIIT intervention was utilized to evaluate the therapeutic efficacy and underlying mechanisms. Hepatosomatic indices, histological architecture and fibrosis severity were examined. Lactate concentrations within the systemic circulation and hepatic parenchyma, alongside comprehensive lipid profiles, were measured. The expressions of genes and proteins involved in hepatic lactate metabolism were delineated via qPCR and Western blotting. Results: The 8-week HIIT intervention effectively improved liver lipid accumulation, hepatocellular injury, and oxidative stress caused by a high-fat diet. Fibrotic expansion and suppressed hepatic stellate cell activation were restricted markedly, as evidenced by the downregulation of collagen type I alpha 1 chain and alpha-smooth muscle actin(α-SMA). HIIT reversed the HFD-induced accumulation of lactate in both systemic circulation and liver tissues, which was found to positively correlate with hepatic α-SMA. Mechanistically, HIIT regulated the expression of the lactate metabolism-related proteins lactate dehydrogenase A and monocarboxylate transporter 1, while selectively enhancing the expression of the gluconeogenic enzymes. Conclusions: Our findings indicate that HIIT effectively ameliorated MASLD and associated hepatic fibrosis by remodeling the hepatic lactate metabolic axis, specifically through the suppression of lactate production and the enhancement of its clearance. These results indicate that targeting lactate homeostasis might be a promising therapeutic strategy for MASLD. Full article

(This article belongs to the Section Endocrinology and Clinical Metabolic Research)

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16 pages, 1339 KB

Open AccessProtocol

Practical Workflow for Building Local Mass Spectral Libraries for Untargeted Metabolomics

by Torbjørn Norberg Myhre, Terkel Hansen, Tetiana Lutchyn, Marie Mardal and Terje Vasskog

Metabolites 2026, 16(6), 412; https://doi.org/10.3390/metabo16060412 (registering DOI) - 12 Jun 2026

Abstract

Background: Metabolite identification and annotation remain major bottlenecks in untargeted metabolomics because mass spectral features often lack sufficient specificity. High-confidence annotation requires experimental validation using authentic standards analyzed under matched chromatographic and ionization conditions, providing greater reliability than in silico predictions or [...] Read more.

Background: Metabolite identification and annotation remain major bottlenecks in untargeted metabolomics because mass spectral features often lack sufficient specificity. High-confidence annotation requires experimental validation using authentic standards analyzed under matched chromatographic and ionization conditions, providing greater reliability than in silico predictions or database matching alone. This study aimed to develop a practical and scalable workflow for constructing a high-quality mass spectral library using a commercially available analytical standards kit. Methods: A total of 603 metabolites from the MSMLS kit were organized into 42 mixtures, each containing approximately 15 compounds. Mixture design was based on molecular mass and distribution coefficient values, specifically logD at pH 3.1, with a minimum logD spacing of 0.15 to improve chromatographic separation and reduce co-elution. This strategy was used to minimize the total number of injections while maintaining spectral quality. The resulting spectra were evaluated against online spectral resources and in silico fragmentation predictions. A preliminary proof-of-concept analysis was also performed using human serum samples. Results: Using this workflow, 471 metabolites, corresponding to approximately 78% of the standards, were successfully detected and incorporated into the spectral library. Comparison with online resources and in silico fragmentation predictions demonstrated improved spectral quality and reliability. The proof-of-concept serum analysis enabled identification of endogenous metabolites using the constructed library. In addition, the robustness and applicability of the workflow were further supported by a method validation study using metabolites derived from this library. Conclusions: This workflow provides a scalable strategy for constructing mass spectral libraries that balances spectral quality with analytical throughput. By using rational mixture design and authentic standards analyzed under matched experimental conditions, the approach enables substantial metabolite coverage while maintaining data reliability and minimizing experimental effort. Full article

(This article belongs to the Collection Advances in Metabolomics)

38 pages, 1870 KB

Open AccessReview

Multi-Targeted Intervention of Eucommia ulmoides and Its Bioactive Constituents Against Metabolic Syndrome: From Molecular Mechanisms and Gut Microbiota Modulation to Clinical Translation

by Fanjia Cheng, Chenghao Lv, Yuhang Yi, Dongsheng Wang, Wenbo Wang, Tao Li, Runze Zhou, Qili Li and Si Qin

Metabolites 2026, 16(6), 411; https://doi.org/10.3390/metabo16060411 (registering DOI) - 12 Jun 2026

Abstract

Background/Objectives: Metabolic syndrome (MetS) is a pressing global health challenge comprising obesity, hyperglycemia, hypertension, and hyperlipidemia. Conventional polypharmacy often presents long-term compliance issues and side effects. Eucommia ulmoides Oliv., a traditional medicinal and edible plant rich in iridoids, lignans, flavonoids, and polysaccharides, has [...] Read more.

Background/Objectives: Metabolic syndrome (MetS) is a pressing global health challenge comprising obesity, hyperglycemia, hypertension, and hyperlipidemia. Conventional polypharmacy often presents long-term compliance issues and side effects. Eucommia ulmoides Oliv., a traditional medicinal and edible plant rich in iridoids, lignans, flavonoids, and polysaccharides, has emerged as a promising natural intervention. This review aims to systematically summarize the bioavailability and multifaceted pharmacological mechanisms of E. ulmoides and its bioactive components in alleviating MetS. Methods: We comprehensively reviewed the recent in vitro and in vivo literature to map the functional evidence, specific signaling pathways, and gut microbiota–host interactions associated with E. ulmoides extracts and its key phytochemicals (e.g., asperuloside) against various metabolic dysfunctions. Results: Current evidence indicates that E. ulmoides operates through a “multi-component, multi-target, and multi-pathway” paradigm. For hyperlipidemia and obesity, it activates hepatic lipid metabolism (PPARα/CPT1A, FXR/CYP7A1) and mitigates oxidative stress (Nrf2/ARE). Furthermore, it dose-dependently reshapes the gut microbiota by enriching beneficial bacteria like Akkermansia and increasing butyrate production, exerting profound gut–liver axis regulation. It also ameliorates hypertension by activating the ACE2-Ang-(1–7)-Mas axis, improves insulin resistance via the AMPK/PI3K/Akt cascade, and manages hyperuricemia by modulating XOD and renal transporters. Notably, the low oral bioavailability of its glycosides highlights the crucial role of gut microbial hydrolysis in its efficacy. Conclusions: E. ulmoides holds substantial therapeutic potential as a multi-target natural supplement for MetS. However, future translational applications necessitate large-scale randomized clinical trials, multi-omics studies to further clarify host–microbiome interactions, and the development of standardized formulations to ensure clinical efficacy. Full article

(This article belongs to the Special Issue The Impact of Polyphenols on Metabolic Health and Disease)

28 pages, 1482 KB

Open AccessReview

Exploring the Health Effects of Phytoestrogens

by Vladimír Kraus, Anna Birková, Miroslava Majerníková and Beáta Čižmárová

Metabolites 2026, 16(6), 410; https://doi.org/10.3390/metabo16060410 (registering DOI) - 12 Jun 2026

Abstract

Background/Objectives: Phytoestrogens are secondary plant metabolites produced via the phenylpropanoid pathway. They include a broad spectrum of chemical compounds, such as phenolics, flavonoids, isoflavones, coumestans, lignans, and others. Their chemical structures resemble those of estradiol, and they exhibit biological effects similar to those [...] Read more.

Background/Objectives: Phytoestrogens are secondary plant metabolites produced via the phenylpropanoid pathway. They include a broad spectrum of chemical compounds, such as phenolics, flavonoids, isoflavones, coumestans, lignans, and others. Their chemical structures resemble those of estradiol, and they exhibit biological effects similar to those of human estrogens, influencing many physiological processes throughout life in both men and women—including the timing and progression of puberty. Methods: The literature search included databases such as PubMed, Scopus, Web of Science, and Google Scholar with the use of specific keywords. Studies were considered eligible if they reported original findings from observational studies (cohort, case–control, and cross-sectional) or from experimental studies. Results: Phytoestrogens can modulate estrogenic activity and interact with a variety of biological pathways. These compounds may play a role in human development and pubertal processes, contribute to overall health, and potentially help alleviate menopausal symptoms and reduce the risk of certain cancers. Conclusions: Phytoestrogens have numerous positive effects on the human body across various stages of life. Their overall impact and potency, however, seem to be influenced by factors such as intake level, individual genetic variability, and the specific phytoestrogen class consumed. Full article

(This article belongs to the Special Issue Effects of Secondary Plant Metabolites on Human Health)

11 pages, 2695 KB

Open AccessArticle

Functional Role of AveC Residues Ser138 and Ala139 for Avermectin and Doramectin Biosynthesis in Streptomyces avermitilis

by Zhangqun Li, Ling Zhang, Xiaofang Li, Mingjie Li and Haiyang Xia

Metabolites 2026, 16(6), 409; https://doi.org/10.3390/metabo16060409 - 12 Jun 2026

Abstract

Background: Doramectin (CHC-B1) is an excellent antiparasitic drug produced by feeding cyclohexanecarboxylic acid (CHC) to Streptomycesavermitilis bkd⁻ mutants. AveC, a bifunctional enzyme encoded by aveC (sav_0940), catalyzes the stereospecific spiroketalization and selective dehydration of dihydroxy ketone polyketide intermediates and [...] Read more.

Background: Doramectin (CHC-B1) is an excellent antiparasitic drug produced by feeding cyclohexanecarboxylic acid (CHC) to Streptomycesavermitilis bkd⁻ mutants. AveC, a bifunctional enzyme encoded by aveC (sav_0940), catalyzes the stereospecific spiroketalization and selective dehydration of dihydroxy ketone polyketide intermediates and modulates both the yield and the proportion of avermectin/doramectin in Streptomyces avermitilis. In our previous work, we constructed a strain harboring a synthetic aveC* gene encoding ten amino acid mutations, which produced nearly pure doramectin. However, the doramectin yield achieved only approximately 60% of the total doramectin and CHC-B2 output observed in the parental strain. Methods: To investigate the roles of Ser138 and Ala139 of AveC in the biosynthesis of doramectin and avermectin, site-directed mutagenesis was performed at both sites. The production and proportion of avermectin and doramectin were determined using high-performance liquid chromatography (HPLC). AlphaFold2-based molecular docking simulations were used to interpret the results. Results: Among the tested mutants, S138G, S138T, and A139H exhibited the highest doramectin production, achieving 143.87%, 151.22%, and 153.36% of the control level, respectively. Unfortunately, almost none of the tested mutants showed a positive effect on avermectin production. Molecular docking simulations revealed distinct affinities of these mutants for the dihydroxy ketone polyketide intermediate, both with and without a cyclohexyl group. Notably, all three mutants displayed larger substrate-binding cavity volumes compared with the wild-type enzyme, which likely facilitates doramectin synthesis by effectively accommodating the cyclohexyl moiety. Docking results further indicated that Ser138 and Ala139 are positioned within the binding cavity but probably do not directly participate in the dehydration activity. Conclusions: These findings suggest that optimizing cavity size through residue substitutions can enhance substrate specificity for doramectin production while preserving catalytic functionality. Full article

(This article belongs to the Section Microbiology and Ecological Metabolomics)

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18 pages, 3135 KB

Open AccessReview

Elabela in Lipid-Related Cardiometabolic Dysfunction: A Critical Narrative Review

by Zuzanna Chęcińska-Maciejewska, Ewa Pruszyńska-Oszmałek, Paweł Kołodziejski, Andrzej Ciborek and Hanna Krauss

Metabolites 2026, 16(6), 408; https://doi.org/10.3390/metabo16060408 - 11 Jun 2026

Abstract

Elabela (ELA/APELA/Toddler) is an endogenous peptide ligand of the apelin receptor APLNR (also known as APJ) and, together with apelin, forms the apelinergic signalling system. Its role in embryonic development, the cardiovascular system, the kidneys and the endothelium is becoming increasingly well characterised, [...] Read more.

Elabela (ELA/APELA/Toddler) is an endogenous peptide ligand of the apelin receptor APLNR (also known as APJ) and, together with apelin, forms the apelinergic signalling system. Its role in embryonic development, the cardiovascular system, the kidneys and the endothelium is becoming increasingly well characterised, whilst its function in metabolic regulation remains unresolved. Elabela activates pathways essential for metabolic homeostasis—PI3K/Akt, AMPK-related pathways, redox regulation, inflammatory control and pro-survival cascades—but no study has shown that it directly regulates adipocyte lipid metabolism. This narrative review categorises the evidence at the receptor, organ, immunometabolic and intra-adipocyte levels, and also considers the adipose tissue microenvironment as a distinct level of potential relevance. The available data support a role for Elabela as a candidate mediator of lipid-related metabolic dysfunction—via anti-inflammatory, antioxidant and tissue-protective mechanisms—with macrophage lipid metabolism representing the most informative immunometabolic interface. Human studies remain scarce, heterogeneous and limited by a lack of standardisation in assay methods and the unresolved specificity of isoforms. Elabela should therefore be regarded as a candidate indirect modulator of metabolic homeostasis and a candidate biomarker of cardiometabolic stress or adaptation—not as a confirmed direct regulator of adipocyte lipid metabolism. Full article

(This article belongs to the Special Issue Human Nutrition and Metabolic Health)

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17 pages, 3707 KB

Open AccessArticle

Exogenous Melatonin Alleviates NaCl-Induced Salinity Stress in Forage Pea (Pisum sativum L.): Concentration Optimization and Genotype-Specific Responses

by Melih Okcu, Zuhal Okcu, Funda Kaya and Kamil Haliloglu

Metabolites 2026, 16(6), 407; https://doi.org/10.3390/metabo16060407 - 10 Jun 2026

Abstract

Background/Objectives: Soil salinity is a major constraint on legume productivity worldwide, threatening forage pea (Pisum sativum L.) cultivation in semiarid regions. This study evaluated the effect of exogenous melatonin in attenuating NaCl-induced salinity stress across diverse forage pea genotypes. Methods: [...] Read more.

Background/Objectives: Soil salinity is a major constraint on legume productivity worldwide, threatening forage pea (Pisum sativum L.) cultivation in semiarid regions. This study evaluated the effect of exogenous melatonin in attenuating NaCl-induced salinity stress across diverse forage pea genotypes. Methods: A three-factor factorial experiment was conducted under greenhouse conditions, testing three NaCl levels (0, 100 and 200 mM) and four melatonin concentrations (0, 100, 150 and 200 µM) across 13 genotypes with three replications (468 pots). Nine vegetative traits were measured and analyzed by factorial ANOVA and Tukey’s HSD test. Results: Increasing NaCl from 0 to 200 mM reduced plant height by ~28% and node number by ~32%. Application of 100 µM melatonin under 100 mM NaCl reduced canopy temperature from 28.1 °C to 23.7 °C and restored SPAD values from 21.7 to 26.5 under 200 mM NaCl. By contrast, 200 µM melatonin under severe salinity paradoxically suppressed SPAD to 8.9 and reduced root length. Emirbey and Kirazlí showed the greatest vegetative growth, while Özkaynak exhibited the highest chlorophyll content. Conclusions: 100 µM melatonin emerged as the optimal concentration for alleviating moderate salt stress in forage pea, and genotype selection is critical when deploying melatonin as a biostimulant under saline conditions. Direct measurement of biomass, yield, and forage quality under field conditions remains an essential next step before agronomic deployment. Full article

(This article belongs to the Special Issue Bioactive Compounds: Plant Stress Responses, Metabolic Regulation, and Therapeutic Insights)

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