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Search Results (230)

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Keywords = arginine citrullination

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16 pages, 1803 KB  
Article
Independent Associations Between Arginine-Related Metabolites and Disease Activity in Pediatric Asthma: A Multivariable Biomarker Study
by Emine Aylin Şenol, Öner Özdemir, Aysel Özpınar and Muhittin A. Serdar
Biomolecules 2026, 16(5), 631; https://doi.org/10.3390/biom16050631 - 24 Apr 2026
Viewed by 452
Abstract
Asthma is a heterogeneous inflammatory airway disease with variable clinical phenotypes. Dysregulation of the arginine–nitric oxide (NO) pathway contributes to airway hyperresponsiveness and endothelial dysfunction, but its role across stages of pediatric asthma remains unclear. In order to replicate real-world clinical heterogeneity, this [...] Read more.
Asthma is a heterogeneous inflammatory airway disease with variable clinical phenotypes. Dysregulation of the arginine–nitric oxide (NO) pathway contributes to airway hyperresponsiveness and endothelial dysfunction, but its role across stages of pediatric asthma remains unclear. In order to replicate real-world clinical heterogeneity, this investigation assessed serum levels of L-arginine, symmetric dimethylarginine (SDMA), asymmetric dimethylarginine (ADMA), L-citrulline, and the SDMA/ADMA ratio in children with managed asthma, asthma exacerbation, upper respiratory tract infections (URTIs), pneumonia, COVID-19, and healthy controls. Discovering stage-specific arginine pathway changes and evaluating their ability to distinguish asthma and asthma exacerbations from other clinically similar respiratory disorders was the primary aim of our research study. Receiver operating characteristic (ROC) analysis demonstrated that the SDMA/ADMA ratio achieved the strongest individual discriminative performance for distinguishing asthma exacerbation from controlled asthma (AUC: 0.917), while the combined multimarker model incorporating all four metabolites yielded an AUC of 0.983 with a sensitivity of 87.5% and specificity of 95.5%. These results indicate that arginine pathway metabolites, especially the SDMA/ADMA ratio, may merit additional research as possible markers of acute disease activity in asthma, even though they are exploratory and need external confirmation. Full article
(This article belongs to the Section Molecular Biomarkers)
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28 pages, 1407 KB  
Review
Sucralose and the Gut–Immune Axis: Emerging Evidence Linking Dysbiosis, Barrier Alterations, and Implications for Colitis and Colorectal Cancer Immunotherapy
by Aranza Mejía-Muñoz, Jessica Cedillo Monter, Héctor Iván Saldívar-Cerón, Galileo Escobedo and Sonia Leon-Cabrera
Biomedicines 2026, 14(4), 917; https://doi.org/10.3390/biomedicines14040917 - 17 Apr 2026
Viewed by 2689
Abstract
Sucralose is one of the most widely used non-nutritive sweeteners and has long been considered metabolically inert and safe within established acceptable daily intake levels. However, emerging evidence suggests that chronic exposure to sucralose may alter gut microbial composition, epithelial barrier function, mucosal [...] Read more.
Sucralose is one of the most widely used non-nutritive sweeteners and has long been considered metabolically inert and safe within established acceptable daily intake levels. However, emerging evidence suggests that chronic exposure to sucralose may alter gut microbial composition, epithelial barrier function, mucosal inflammation, and immune responses. This review examines current experimental and clinical evidence on the effects of sucralose on the gut–immune axis, with particular attention to its potential implications for colitis and colorectal cancer (CRC). Preclinical studies indicate that sucralose may reduce beneficial short-chain fatty acid-producing taxa, alter microbial metabolic pathways, disrupt epithelial barrier-related molecules, and promote inflammatory and immune changes associated with colitis severity and inflammation-driven tumorigenesis. Experimental evidence also suggests that sucralose may impair CD8+ T-cell fitness and reduce responsiveness to immune checkpoint inhibitors through microbiome-dependent mechanisms involving altered arginine and citrulline metabolism. Human studies further indicate that sucralose can modify gut and oral microbiome composition and influence metabolic responses, although these effects appear heterogeneous and context-dependent. Overall, the current literature suggests that sucralose may act as a modifier of microbiome–immune interactions in susceptible settings, but most mechanistic evidence remains preclinical, and human data are still insufficient to establish causality. These findings highlight the need for prospective studies to determine whether sucralose-associated microbial and immune alterations translate into clinically meaningful effects in colitis, CRC, and immunotherapy response. Full article
(This article belongs to the Special Issue Advancements in the Treatment of Colorectal Cancer)
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40 pages, 2982 KB  
Review
Beyond PAD Inhibition: Emerging Avenues and Natural Products for Targeting Citrullination in Immune Diseases
by Qilei Chen, Yuhang Ma, Yingyi Liu, Xiaojie Wang, Guanhua Huang, Yizhao Yang, Joshua Ka-Shun Ko and Hubiao Chen
Biomedicines 2026, 14(4), 850; https://doi.org/10.3390/biomedicines14040850 - 8 Apr 2026
Viewed by 997
Abstract
Immune-mediated inflammatory diseases, such as rheumatoid arthritis, multiple sclerosis, and systemic lupus erythematosus, impose a severe and growing global health burden, where current therapies are limited by poor specificity and significant side effects. The peptidylarginine deiminase (PAD)/citrullination axis, in which protein citrullination catalyzed [...] Read more.
Immune-mediated inflammatory diseases, such as rheumatoid arthritis, multiple sclerosis, and systemic lupus erythematosus, impose a severe and growing global health burden, where current therapies are limited by poor specificity and significant side effects. The peptidylarginine deiminase (PAD)/citrullination axis, in which protein citrullination catalyzed by PADs drives autoantigen generation and sustains inflammation, has emerged as a critical therapeutic target. This review outlines a comprehensive strategy for targeting this axis using natural products. We first detail the established role of natural compounds as direct PAD inhibitors, covering their chemical diversity, inhibitory mechanisms, and therapeutic applications in disease models. Subsequently, the discussion extends to their broader, indirect modulatory functions, highlighting how these compounds can suppress pathogenic citrullination by regulating upstream processes like NETosis and inflammatory signaling. Furthermore, the review introduces the innovative substrate-centric intervention strategy, which represents a paradigm shift toward shielding key arginine residues on autoantigens, thereby preventing the formation of immunogenic neoepitopes. The translational challenges and future directions for each of these avenues are outlined, addressing persistent obstacles including achieving isoform selectivity and biomarker validation. By integrating these multifaceted strategies, from direct inhibition and indirect modulation to substrate protection, this work provides a strategic roadmap for advancing the next generation of more precise, effective, and safe anti-citrullination therapies, ultimately moving beyond conventional enzyme inhibition toward targeted immunomodulation in immune-mediated inflammatory diseases. Full article
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19 pages, 1040 KB  
Article
Does Capillary or Intravenous Collection of Dried Blood Spots Affect the Results of Amino Acid and Acylcarnitine Profile Studied with Tandem Mass Spectrometry?
by Banu Kadıoğlu Yılmaz, Abdullah Sivrikaya and Ali Ünlü
Metabolites 2026, 16(4), 244; https://doi.org/10.3390/metabo16040244 - 4 Apr 2026
Viewed by 535
Abstract
Background and Objectives: This study investigated whether capillary and intravenous sampling affect acylcarnitine and amino acid profile results analyzed by tandem mass spectrometry. Methods: The study included 120 patients either diagnosed with an inherited metabolic disease or undergoing evaluation for a suspected metabolic [...] Read more.
Background and Objectives: This study investigated whether capillary and intravenous sampling affect acylcarnitine and amino acid profile results analyzed by tandem mass spectrometry. Methods: The study included 120 patients either diagnosed with an inherited metabolic disease or undergoing evaluation for a suspected metabolic disorder at the Department of Pediatric Nutrition and Metabolism, Selçuk University Faculty of Medicine. Paired capillary and intravenous blood samples were collected simultaneously, applied to filter paper, and analyzed by LC-MS/MS to determine acylcarnitine and amino acid profiles. Results: Significant differences were observed between capillary and intravenous samples for several acylcarnitines, including C0, C2, C8, C8.1, C10, C10.1, C14.1, C16, and C18.1 (p < 0.05). In the amino acid profile, arginine, aspartic acid, citrulline, glutamic acid, glycine, leucine + isoleucine, methionine, tyrosine, and the methionine/phenylalanine ratio differed significantly between sampling methods (p < 0.05). Despite these differences, Cohen’s kappa analysis showed high agreement between capillary and venous samples for most parameters (78.3–100%) when categorized as low, normal, or high based on reference ranges. Additionally, no significant discrepancies were found in key diagnostic parameters among patients with specific inherited metabolic diseases. Conclusions: Although certain acylcarnitine and amino acid levels differed between capillary and intravenous samples, overall diagnostic agreement was high. However, since the study group did not include any patients with fatty acid oxidation disorders, a separate confirmatory study is needed for this condition. Larger multicenter studies involving more patients and a wider range of metabolic disorders are needed to better understand the clinical impact of sampling method on dried blood spot analyses. Full article
(This article belongs to the Section Metabolomic Profiling Technology)
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17 pages, 3472 KB  
Article
Energy-Metabolism-Enhancing Probiotics Enhance the Therapeutic Response to a Glucagon-like Peptide-1 Receptor Agonist
by A-Ram Kim, Seong-Gak Jeon, So-Jung Park, Byoung-Kook Kim, Mi-Na Kweon, Myoung Ho Jang and Bo-Gie Yang
Nutrients 2026, 18(7), 1050; https://doi.org/10.3390/nu18071050 - 26 Mar 2026
Viewed by 971
Abstract
Background/Objectives: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective treatments for obesity, but substantial weight regain is common after therapy is discontinued. This study investigated whether probiotic strains with anti-obesity effects could enhance GLP-1RA-induced weight loss and attenuate post-treatment weight rebound. Methods: [...] Read more.
Background/Objectives: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective treatments for obesity, but substantial weight regain is common after therapy is discontinued. This study investigated whether probiotic strains with anti-obesity effects could enhance GLP-1RA-induced weight loss and attenuate post-treatment weight rebound. Methods: Candidate lactic acid bacteria were screened for anti-obesity efficacy in a high-fat-diet (HFD)-induced obese mouse model, and the selected strain was further characterized using metabolomic profiling of culture supernatants. To examine its interaction with GLP-1RA therapy, obese mice received dulaglutide for 4 weeks and were monitored for 2 weeks after treatment withdrawal, while the probiotic was orally administered for a total of 6 weeks. Body weight, glycemic parameters, and muscle strength were assessed throughout the study. Results: Limosilactobacillus fermentum GB102 reduced body weight and improved glycemic control in HFD-fed mice. These metabolic benefits were associated with alterations in circulating metabolic hormones, including adipokines, along with attenuated inflammatory responses in adipose tissue. Metabolomic profiling revealed that GB102 produced high levels of succinic acid, a metabolite previously linked to thermogenic activation. This strain increased whole-body energy expenditure in HFD-fed mice, produced glutamine, and showed enhanced conversion of arginine into ornithine and citrulline. When combined with dulaglutide, GB102 enhanced weight loss, preserved muscle strength, and attenuated both weight regain and glycemic rebound following dulaglutide withdrawal. Conclusions: These findings suggest that energy-metabolism-enhancing probiotics such as GB102 may enhance the metabolic effects of GLP-1RA therapy and help attenuate weight regain after treatment discontinuation. Full article
(This article belongs to the Special Issue Probiotics and the Gut Microbiome in Obesity)
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31 pages, 8507 KB  
Review
Natural Products Targeting PAD4 in NETosis: Structural and Mechanistic Insights into Direct and Indirect Inhibition
by Dong Oh Moon
Biomolecules 2026, 16(3), 420; https://doi.org/10.3390/biom16030420 - 12 Mar 2026
Cited by 1 | Viewed by 1021
Abstract
Peptidyl arginine deiminase 4 (PAD4) is a Ca2+-dependent enzyme that catalyzes histone citrullination and plays a central role in chromatin decondensation during neutrophil extracellular trap (NET) formation. Dysregulated PAD4-mediated NETosis contributes to the pathogenesis of diverse inflammatory and immune-related diseases, including [...] Read more.
Peptidyl arginine deiminase 4 (PAD4) is a Ca2+-dependent enzyme that catalyzes histone citrullination and plays a central role in chromatin decondensation during neutrophil extracellular trap (NET) formation. Dysregulated PAD4-mediated NETosis contributes to the pathogenesis of diverse inflammatory and immune-related diseases, including autoimmune disorders, cancer, and thrombosis. Although several synthetic PAD4 inhibitors have been developed, their therapeutic application has been limited by issues related to selectivity, irreversible covalent reactivity, and suboptimal pharmacokinetic properties, prompting growing interest in natural products as alternative modulators of PAD4 activity and NETosis. This article presents a structural and mechanistic overview of natural products that target PAD4 and regulate NETosis. Based on enzyme kinetics, structural analyses, and functional validation, natural PAD4 modulators are classified into four categories: (i) active-site-directed inhibitors that bind within the U-shaped substrate tunnel, (ii) mixed and active-site-adjacent inhibitors that engage surface pockets flanking the catalytic site, (iii) allosteric and hybrid modulators that bind to regulatory regions distinct from the active site, and (iv) functionally validated PAD4 binders supported by biophysical and cellular evidence. Integration of structural, biochemical, and cellular data highlights that indirect or noncanonical modes of PAD4 regulation represent biologically coherent strategies for controlling pathological NETosis. Full article
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14 pages, 2606 KB  
Article
Ionizing Radiation Induces Extracellular Trap Release from Macrophages
by Yongchan Lee, Monowar Aziz and Ping Wang
Int. J. Mol. Sci. 2026, 27(2), 993; https://doi.org/10.3390/ijms27020993 - 19 Jan 2026
Viewed by 882
Abstract
Macrophages are key innate immune cells in the host defense against pathogens. Ionizing radiation can impair macrophage functions such as phagocytosis and activate them, potentially exacerbating tissue injury. Macrophage extracellular traps (METs) are formed upon stimulation of macrophages with PAMPs or DAMPs. We [...] Read more.
Macrophages are key innate immune cells in the host defense against pathogens. Ionizing radiation can impair macrophage functions such as phagocytosis and activate them, potentially exacerbating tissue injury. Macrophage extracellular traps (METs) are formed upon stimulation of macrophages with PAMPs or DAMPs. We hypothesized that macrophages exposed to ionizing radiation can release extracellular traps. Peritoneal macrophages were collected from C57BL/6 mice and subjected to 5 Gy radiation. We performed assays to detect METs, including the immunofluorescence of citrullination of histone H3 and cell-free DNA measurement in cell culture medium as well as cell death. The exposure of ionizing radiation killed a significant number of mouse peritoneal macrophages through pyroptosis, which was mediated by Gasdermin D (GSDMD). The onset of pyroptosis eventually caused METs by suicidal METosis via pyroptosis and vital METosis occurring in the cells surviving after exposure to radiation. We found that exposure of peritoneal macrophages to 5 Gy radiation significantly increased METosis, as revealed by increased levels of citrullinated histone H3 and an increased surface area of extracellular DNA surrounding the cells. We discovered that peptidyl arginine deiminase (PAD) 2 and 4 are required for peritoneal macrophages to generate extracellular traps in response to radiation exposure. Our data demonstrate that the ionizing radiation induces METs via the activation of GSDMD, and we confirmed the requirement of PADs for METosis after exposure to the ionizing radiation. Targeting METs may direct a new therapeutic strategy for mitigating radiation-induced tissue injury. Full article
(This article belongs to the Section Molecular Biology)
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24 pages, 4088 KB  
Article
Enhanced Alarmin Secretion Exacerbates Neutrophil Extracellular Trap (NET) Formation in Active Psoriasis: Implication of IL-33 and TSLP in Driving NET Formation, Inflammation and Oxidative Stress in Psoriasis
by Vanshika Ojha, Manoj Kumar Tembhre and Vishal Gupta
Antioxidants 2026, 15(1), 71; https://doi.org/10.3390/antiox15010071 - 6 Jan 2026
Viewed by 1178
Abstract
Psoriasis is a common inflammatory skin disease with chronic manifestation in which the role of neutrophil extracellular traps (NETs) and alarmins are increasingly recognized as contributors to systemic and cutaneous inflammation. However, the interaction between alarmins and NET-driven immune responses remains poorly defined. [...] Read more.
Psoriasis is a common inflammatory skin disease with chronic manifestation in which the role of neutrophil extracellular traps (NETs) and alarmins are increasingly recognized as contributors to systemic and cutaneous inflammation. However, the interaction between alarmins and NET-driven immune responses remains poorly defined. The main aim of this study is to define the role of target alarmins (i.e., IL-33 and TSLP) in NETs induction and its subsequent impact on oxidative stress and inflammation in the peripheral blood. In the present study, we recruited active psoriasis patients (n = 56) and control (n = 56) subjects. The frequency of circulating neutrophils, the levels of NET-associated markers (MPO (myeloperoxidase)–DNA complex, CitH3 (citrullinated histone H3), PAD4 (peptidyl arginine deiminase4), NADPH oxidase, and NE (neutrophil elastase)), and alarmin transcripts (IL (interleukin)-33, TSLP (thymic stromal lymphopoietin), S100A7, S100B, HSP (heat shock protein) 60/70 were quantified using flow cytometry, ELISA (Enzyme-linked immunosorbent assay), and qPCR (quantitative polymerase chain reaction), respectively, in each group. The NET formation potential of isolated neutrophils was assessed in the presence or absence of rhIL-33 and rhTSLP by immunocytofluorescence. The effect of rhIL-33- and rhTSLP-primed NETs in augmenting oxidative stress and inflammation was evaluated on peripheral blood mononuclear cells (PBMCs) by ELISA. Significantly higher circulating neutrophils (p < 0.001) and levels of NET-associated markers (i.e., MPO–DNA complex, CitH3, PAD4, NADPH oxidase, and NE) were observed in active psoriasis patients compared to controls. Lesional skin exhibited strong expression of MPO (p < 0.001) compared to normal skin. The alarmins, IL-33 and TSLP, were markedly upregulated in the blood and skin (p < 0.05). The rhIL-33 and rhTSLP treated neutrophils demonstrated enhanced NETosis in patients (p < 0.001). Increased expression of inflammatory cytokines and oxidative stress markers were reported in PBMCs when incubated with rhIL-33- and rhTSLP-primed NETs. Taken together, our investigation demonstrated the novel mechanism wherein the alarmins IL-33 and TSLP exacerbate NET formation that may drive enhanced inflammation and oxidative stress in psoriasis. Full article
(This article belongs to the Special Issue Antioxidants and Oxidative Stress in Skin Health and Diseases)
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12 pages, 509 KB  
Article
Manganese Exposure in Occupational Settings: Disruptions in Endothelial Function and Thyroid Regulation
by Melih Gaffar Gözükara, Servet Birgin İritaş, Lütfiye Tutkun, Murat Büyükşekerci, Özlem İritaş, Vugar Ali Türksoy, Deniz Özkan Vardar, Serdar Deniz and Engin Tutkun
Metabolites 2026, 16(1), 1; https://doi.org/10.3390/metabo16010001 - 19 Dec 2025
Cited by 1 | Viewed by 893
Abstract
Background: Manganese (Mn) exposure is common in welding and metal-processing occupations and has been implicated in both thyroid disruption and endothelial dysfunction through oxidative and nitric-oxide–related pathways. However, endocrine and vascular biomarkers have rarely been examined together in occupational settings. Methods: In this [...] Read more.
Background: Manganese (Mn) exposure is common in welding and metal-processing occupations and has been implicated in both thyroid disruption and endothelial dysfunction through oxidative and nitric-oxide–related pathways. However, endocrine and vascular biomarkers have rarely been examined together in occupational settings. Methods: In this cross-sectional study, 95 Mn-exposed workers and 95 non-exposed controls were evaluated. Whole-blood Mn, triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), arginine and citrulline were measured using validated Inductively Coupled Plasma—Mass Spectrometer and chemiluminescent immunoassays. Group differences were assessed using independent samples t-tests, and exposure–biomarker associations were evaluated using Pearson correlations (p < 0.05). Results: Mn-exposed workers had significantly higher blood Mn levels than controls (19.82 ± 4.54 vs. 10.22 ± 3.07 µg/L; p < 0.001). Thyroid hormones (T3, T4, and TSH) were significantly lower among Mn workers, representing a non-classical hormonal pattern, including T3 (2.47 ± 0.31 vs. 3.14 ± 0.42 ng/L; p < 0.001), T4 (1.02 ± 0.13 vs. 1.21 ± 0.18 ng/L; p < 0.001), and TSH (1.75 ± 0.53 vs. 2.88 ± 0.37 mIU/L; p < 0.001). Endothelial biomarkers also differed: ADMA (0.26 ± 0.14 vs. 0.19 ± 0.08 µmol/L; p < 0.001) and SDMA (0.24 ± 0.06 vs. 0.20 ± 0.03 µmol/L; p < 0.001) were higher, while citrulline was lower (18.77 ± 10.23 vs. 22.82 ± 6.70 µmol/L; p = 0.002). In Mn workers, blood Mn showed negative correlations with T3 (r = –0.535, p < 0.01), T4 (r = –0.331, p < 0.01), and TSH (r = –0.652, p < 0.01), and positive correlations with ADMA (r = 0.205, p < 0.05) and SDMA (r = 0.193, p < 0.05). Conclusions: These findings indicate measurable differences in thyroid hormones and dimethylarginine-related endothelial markers among Mn-exposed workers. While the cross-sectional design precludes causal inference, the combined pattern suggests a possible unusual biological response involving both endocrine regulation and nitric-oxide–related pathways. Further longitudinal studies incorporating oxidative stress markers, co-exposure assessment, and functional endothelial testing are needed to clarify the biological relevance of these associations. Full article
(This article belongs to the Special Issue The Impact of Toxic Metals on Human Metabolism and Health)
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20 pages, 470 KB  
Review
Peptidylarginine Deiminases: An Overview of Recent Advances in Citrullination Research
by Magdalena Kijak-Boćkowska, Joanna Czerwińska and Agnieszka Owczarczyk-Saczonek
Int. J. Mol. Sci. 2025, 26(24), 12060; https://doi.org/10.3390/ijms262412060 - 15 Dec 2025
Cited by 4 | Viewed by 2541
Abstract
The peptidylarginine deiminase (PAD) family includes five isozymes (PAD1–4 and PAD6) with unique tissue distributions and substrate specificities. These enzymes facilitate citrullination, a post-translational modification where positively charged arginine residues are converted into neutral citrulline residues in the presence of calcium ions. This [...] Read more.
The peptidylarginine deiminase (PAD) family includes five isozymes (PAD1–4 and PAD6) with unique tissue distributions and substrate specificities. These enzymes facilitate citrullination, a post-translational modification where positively charged arginine residues are converted into neutral citrulline residues in the presence of calcium ions. This process significantly changes protein properties, affecting molecular interactions, structural stability, and biological functions. Over the past six years (2019–2025), there has been significant progress in understanding PAD activity mechanisms and their therapeutic potential. Recent discoveries include the regulated nuclear translocation of PAD2, PAD4’s specific role in forming cancer extracellular chromatin networks (CECNs), and the development of next-generation inhibitors with greatly improved pharmacological profiles. PAD4 is crucial in forming neutrophil extracellular traps (NETs). Citrullination of histones H3 and H4 by PAD4 destabilizes chromatin, helping release DNA-protein networks as an antibacterial defense. However, excessive NET formation can contribute to autoimmune diseases and thrombosis. Similarly, the bacterial peptidylarginine deiminase from Porphyromonas gingivalis (PPAD)—the only known prokaryotic citrullinating enzyme—plays a key role. Working with R-gingipains, PPAD triggers pathological citrullination of host proteins, leading to immune tolerance breakdown and linking periodontal disease with systemic autoimmune disorders such as rheumatoid arthritis, atherosclerosis, and Alzheimer’s disease. Once thought to be a rare post-translational modification, citrullination is now understood as a vital regulatory mechanism in both normal physiology and disease, involving both internal processes of homeostasis and external mechanisms of bacterial pathogenesis. Full article
(This article belongs to the Special Issue Current Progress in Neutrophil Extracellular Traps (NETs))
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17 pages, 1723 KB  
Article
Impact of Cadmium on Prostate-Specific Antigen and Endothelial Markers: A Risk for Prostatic Damage
by Servet Birgin İritaş, Melih Gaffar Gözükara, Lütfiye Tutkun, Deniz Özkan Vardar, Murat Büyükşekerci, Gülsüm Abusoğlu, Serdar Deniz, Vugar Ali Türksoy and Engin Tutkun
Toxics 2025, 13(12), 1049; https://doi.org/10.3390/toxics13121049 - 4 Dec 2025
Viewed by 1026
Abstract
Cadmium (Cd) is a persistent toxic metal that bioaccumulates in human tissues and may disrupt redox and endocrine pathways, yet the metabolic mechanisms linking Cd exposure to both endothelial and prostate dysfunctions remain insufficiently defined. This study investigated whether chronic occupational Cd exposure [...] Read more.
Cadmium (Cd) is a persistent toxic metal that bioaccumulates in human tissues and may disrupt redox and endocrine pathways, yet the metabolic mechanisms linking Cd exposure to both endothelial and prostate dysfunctions remain insufficiently defined. This study investigated whether chronic occupational Cd exposure alters methylated arginine metabolism and prostate-specific antigen (PSA) levels, indicating a shared toxicometabolic axis. A total of 150 male workers were enrolled, including 75 metallurgical employees with documented Cd exposure and 75 matched controls. All participants were non-smokers, eliminating confounding from tobacco-related oxidative or endocrine effects. Urinary Cd concentrations were quantified using Inductively Coupled Plasma–Mass Spectrometry (ICP–MS), and serum asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), L-arginine, citrulline, and PSA were measured by Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) and electrochemiluminescence. The use of Inductively Coupled Plasma–Mass Spectrometry for cadmium quantification and LC-MS/MS for methylated arginine profiling provided high analytical specificity and sensitivity, strengthening the validity of biomarker measurements. Correlation and multivariable analyses adjusted for age and body mass index. Cd-exposed workers demonstrated significantly elevated urinary Cd, PSA, ADMA, and SDMA levels, alongside reduced arginine/ADMA ratios, consistent with impaired nitric oxide bioavailability. Urinary Cd strongly correlated with PSA and ADMA levels. These findings indicate that Cd may disrupt the nitric oxide pathway and elevates PSA, supporting a mechanistic link between vascular and prostate stress. Combined ADMA, SDMA, and PSA profiling may serve as an early biomarker panel for Cd-related metabolic injury in occupational settings. Full article
(This article belongs to the Special Issue Toxicity and Safety Assessment of Exposure to Heavy Metals)
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19 pages, 3470 KB  
Article
Research on the Changing Characteristics of Milk Composition and Serum Metabolites Across Various Lactation Periods in Xinggao Sheep
by Jingda Yuan, Zhenbo Wu, Biao Wang, Shaoyin Fu, Rigele Te, Lai Da, Liwei Wang, Qing Qin and Xiaolong He
Metabolites 2025, 15(10), 678; https://doi.org/10.3390/metabo15100678 - 20 Oct 2025
Cited by 1 | Viewed by 1200
Abstract
Background: The variation in sheep milk composition is closely related to the sheep’s metabolic status. This study aimed to analyze the milk composition and serum metabolic characteristics of Xinggao sheep during different lactation periods and to evaluate the association between milk quality traits [...] Read more.
Background: The variation in sheep milk composition is closely related to the sheep’s metabolic status. This study aimed to analyze the milk composition and serum metabolic characteristics of Xinggao sheep during different lactation periods and to evaluate the association between milk quality traits and body metabolism. Methods: Eighteen intensively reared ewes were divided into three groups: an early lactation group (MA), a mid-lactation group (MB), and a late lactation group (MC). Milk components were detected by infrared spectroscopy, and the ewes’ serum metabolomic characteristics were detected by liquid chromatography–mass spectrometry (LC-MS). K-means correlation analysis revealed that the milk fat percentage was positively correlated with L-aspartic acid and negatively correlated with citrulline levels. Random forest analysis for metabolite importance ranking showed that methionine sulfoxide and methionine exhibited high mean decrease accuracy and mean decrease Gini index values. Results: The milk composition results showed that, compared with MA, the milk fat content and total solids in MB and MC were significantly higher, while the freezing point in the MC was significantly lower. Metabolomic studies showed that 207, 210, and 238 differential metabolites were identified in the comparisons of MA vs. MB MA vs. MC, and MB vs. MC, respectively, and these metabolites were mainly enriched in the pyrimidine metabolism, arachidonic acid metabolism, and arginine biosynthesis pathways. Evaluation of metabolite importance using random forest models revealed that 27 metabolites, including 2-Arachidonyl glycerol ether, methionine, and methionine sulfoxide, showed a high mean decrease accuracy and mean decrease Gini index. Correlation analysis revealed that milk fat percentage and total solids were positively correlated with 11 metabolites, including citrulline, phenylalanine, and octadecylamine, and negatively correlated with isoproterenol, cortisol, and kynurenic acid. The freezing point was positively correlated with cortisol, isoproterenol, and kynurenic acid and negatively correlated with aldosterone, dehydroepiandrosterone, and betaine. Conclusions: This study showed that there were significant differences in the milk composition and metabolites of Xinggao sheep during different lactation periods, highlighting the impact of lactation stage on milk composition and production performance. We recommend developing targeted nutritional strategies based on the specific metabolic profiles of different lactation periods to optimize the feeding management and nutritional regulation of Xinggao sheep. Full article
(This article belongs to the Section Animal Metabolism)
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24 pages, 2391 KB  
Review
Watermelon Nutritional Composition with a Focus on L-Citrulline and Its Cardioprotective Health Effects—A Narrative Review
by Diego dos Santos Baião, Davi V. T. da Silva and Vania M. F. Paschoalin
Nutrients 2025, 17(20), 3221; https://doi.org/10.3390/nu17203221 - 14 Oct 2025
Cited by 2 | Viewed by 9807
Abstract
Nitric oxide is a gaseous molecule endogenously produced by endothelial cells, which stands out for its vascular tone regulation effects after crossing through the endothelium and diffusing to smooth blood vessel muscle cells. Reduced nitric oxide bioavailability contributes to the development of hypertension, [...] Read more.
Nitric oxide is a gaseous molecule endogenously produced by endothelial cells, which stands out for its vascular tone regulation effects after crossing through the endothelium and diffusing to smooth blood vessel muscle cells. Reduced nitric oxide bioavailability contributes to the development of hypertension, atherosclerosis, worsening endothelial function, arterial stiffness, and ineffective stimulation of smooth muscle relaxation. L-citrulline, an amino acid found in high concentrations in watermelon, may serve as a recycling substrate, increasing L-arginine availability and, consequently, nitric oxide synthesis. By enhancing circulating L-arginine, L-citrulline indirectly improves the synthesis and bioavailability of nitric oxide, promoting smooth muscle vasodilation. Herein, this narrative review critically examines current evidence of the cardiovascular benefits of L-citrulline ingestion obtained exclusively through watermelon consumption, exploring the nutritional and bioactive composition of the edible parts of this fruit and the metabolism and effects of L-citrulline supplementation on vascular and metabolic physiology and proposing directions for future research, such as long-term studies and studies in specific populations. The beneficial effects of oral L-citrulline ingestion through watermelon require additional evidence, but it has already been demonstrated that it does not undergo hepatic metabolism, instead being transported to the kidneys to participate in de novo L-arginine synthesis. The generation of endogenous NO then causes positive biochemical, hemodynamic, and vascular effects, remodeling the physio-pathological conditions of those adults that present risk factors for cardiovascular diseases. Full article
(This article belongs to the Special Issue Benefits of Fruit Intake on Cardiovascular Health)
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16 pages, 1526 KB  
Article
Metabolic Characteristics of PGPR-Induced Growth Promotion in Alfalfa (Medicago sativa L.)
by Rina Dao, Ying Zhang, Qiang Li and Shengyan Lei
Metabolites 2025, 15(10), 652; https://doi.org/10.3390/metabo15100652 - 30 Sep 2025
Cited by 1 | Viewed by 934
Abstract
Background/Objectives: Plant growth-promoting rhizobacteria (PGPR) have demonstrated potential for enhancing plant growth; existing research inadequately characterizes the metabolic underpinnings of PGPR-induced plant phenotypes. Methods: A deeper investigation into the impact of PGPR on plant metabolic pathways is crucial for a comprehensive [...] Read more.
Background/Objectives: Plant growth-promoting rhizobacteria (PGPR) have demonstrated potential for enhancing plant growth; existing research inadequately characterizes the metabolic underpinnings of PGPR-induced plant phenotypes. Methods: A deeper investigation into the impact of PGPR on plant metabolic pathways is crucial for a comprehensive understanding of their growth-promoting mechanisms and for the development of more effective biofertilizers and plant protection strategies. Results: To clarify the core metabolic pathways targeted by PGPR strains, we selected alfalfa as the research object, employed two Pseudomonas combinations, and utilized a broad-targeted metabolomics approach to investigate the metabolic characteristics of alfalfa roots. Through the analysis of primary and secondary metabolites, a total of 2694 metabolites were identified, among which lipids were the main nutrients during the growth of alfalfa. The L-citrulline and L-arginine contents were significantly upregulated, thereby affecting nitrogen metabolism and ultimately promoting plant growth. In addition, different branches of the isoflavonoid biosynthesis pathway showed differential regulation, indicating their close relationship with plant growth promotion. Conclusions: This study provides a new perspective for a deeper understanding of the molecular mechanisms by which PGPR promotes plant growth and lays a theoretical foundation for the future development of PGPR-based agricultural biological agents. Full article
(This article belongs to the Section Plant Metabolism)
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Article
Dose–Response Effect of Watermelon Consumption on Ambulatory Blood Pressure in Adults with Elevated Blood Pressure: A Randomized Controlled Pilot Trial
by Kanishka Singh, Huiling Liao, Indika Edirisinghe, Britt Burton-Freeman and Amandeep K. Sandhu
Nutrients 2025, 17(19), 3073; https://doi.org/10.3390/nu17193073 - 26 Sep 2025
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Abstract
Background/Objectives: Watermelon (Citrullus lanatus) is a natural dietary source of L-citrulline and L-arginine, the two amino acids involved in nitric oxide (NO) production and vasodilation. Pre-clinical and clinical studies using isolated amino acids or watermelon extracts suggest blood pressure (BP)-lowering [...] Read more.
Background/Objectives: Watermelon (Citrullus lanatus) is a natural dietary source of L-citrulline and L-arginine, the two amino acids involved in nitric oxide (NO) production and vasodilation. Pre-clinical and clinical studies using isolated amino acids or watermelon extracts suggest blood pressure (BP)-lowering potential; however, limited research has been conducted on the impact of watermelon flesh (WM) on BP in adults at risk for hypertension. Therefore, the primary objective of this study was to assess the effect of daily WM intake for four weeks on 24 h ambulatory BP in adults with elevated blood pressure. The secondary outcomes of this study include changes in glucose and insulin markers, lipid profile, NO, L-citrulline, L-arginine, asymmetric dimethylarginine (ADMA) concentrations, and the L-arginine/ADMA ratio. Methods: In this randomized, placebo controlled parallel study design, 39 adults (age: 41 ± 14 years, BMI: 31 ± 6 kg/m2, mean ± SD) with elevated BP were randomly assigned to one of three groups for a 4-week intervention: control (0 g WM), WM-1 cup (152 g/day), or WM-2 cups (304 g/day). Ambulatory BP was measured over 24 h at baseline and the end of the intervention period. Fasting plasma samples were analyzed for metabolic biomarkers on a clinical analyzer and NO using a colorimetric assay. L-citrulline, L-arginine, and ADMA were analyzed using an ultra-high-performance liquid chromatography triple quadrupole mass spectrometer (UHPLC-QQQ-MS/MS). Statistical analyses were conducted using SPSS software (IBM SPSS Statistics, Version 29.0.0). Results: After 4 weeks, mean 24 h ambulatory BP was 130.2 ± 3.9 mm Hg (control), 130 ± 3.2 mm Hg (WM-1 cup), and 124.9 ± 3.9 mm Hg (WM-2 cups), with no statistically significant differences between study interventions (p > 0.05). Similarly, no significant changes were observed in fasting plasma glucose, insulin, lipid profile, or NO concentrations. However, plasma L-arginine concentrations and L-arginine/ADMA ratios significantly increased in the WM groups compared to the control (p = 0.009) after adjusting for age, BMI, race, and gender in the statistical model. Conclusion: Overall, BP was not significantly different after two different doses of watermelon compared to control; however, improvements in NO synthesis pathway precursors (L-arginine, ADMA) suggest potential for dietary modulation to support endothelial function and BP regulation. Full article
(This article belongs to the Section Clinical Nutrition)
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