Arginine metabolism: nitric oxide and beyond

Arginine depletion-induced autophagy and metabolic dysregulation are involved in the disease severity of hand, foot, and mouth disease

Amino acid metabolism provides significant insight into the development and prevention of many viral diseases. Therefore, the present study aimed to compare the amino acid profiles of hand, foot, and mouth disease (HFMD) patients with those of healthy individuals and to further reveal the molecular mechanisms of HFMD severity. Using UPLC-MS/MS, we determined the plasma amino acid expression profiles of pediatric patients with HFMD (mild, n = 42; severe, n = 43) and healthy controls (n = 25). Brain tissues from CVA6-infected mice were examined using untargeted metabolomics. Several amino acids were significantly different between the three groups. Pathway analysis revealed that arginine, proline, and tryptophan metabolism are implicated in the pathogenesis of HFMD. A similar arginine depletion was observed in the brain tissues of CVA6-infected mice. Importantly, L-arginine supplementation improved the survival rate of CVA6-infected mice, inhibited virus multiplication, and reduced pathological autophagy associated with mTOR-autophagy pathway in the brain. Collectively, arginine, as the hub amino acid metabolite of the mammalian target of rapamycin (mTOR) signaling pathway affecting autophagy, plays an important role in the pathogenesis of severe HFMD. L-arginine supplementation may serve as a potential therapeutic option for critical patients with HFMD.

Mild Blast Exposure Dysregulates Metabolic Pathways and Correlation Networking as Evident from LC-MS-Based Plasma Profiling

Blast-induced trauma is emerging as a serious threat due to its wide pathophysiology where not only the brain but also a spectrum of organs is being affected. In the present study, we aim to identify the plasma-based metabolic dysregulations along with the associated temporal changes at 5-6 h, day 1 and day 7 post-injury in a preclinical animal model for blast exposure, through liquid chromatography-mass spectrometry (LC-MS). Using significantly advanced metabolomic and statistical bioinformatic platforms, we were able to elucidate better and unravel the complex networks of blast-induced neurotrauma (BINT) and its interlinked systemic effects. Significant changes were evident at 5-6 h with maximal changes at day 1. Temporal analysis also depicted progressive changes which continued till day 7. Significant associations of metabolic markers belonging to the class of amino acids, energy-related molecules, lipids, vitamin, hormone, phenolic acid, keto and histidine derivatives, nucleic acid molecules, uremic toxins, and uronic acids were observed. Also, the present study is the first of its kind where comprehensive, detailed pathway dysregulations of amino acid metabolism and biosynthesis, perturbed nucleotides, lipid peroxidation, and nucleic acid damage followed by correlation networking and multiomics networking were explored on preclinical animal models exposed to mild blast trauma. In addition, markers for systemic changes (renal dysfunction) were also observed. Global pathway predictions of unannotated peaks also presented important insights into BINT pathophysiology. Conclusively, the present study depicts important findings that might help underpin the biological mechanisms of blast-induced brain or systemic trauma.

L-arginine administration exacerbates myocardial injury in diabetics via prooxidant and proinflammatory mechanisms along with myocardial structural disruption

BACKGROUND

L-arginine (L-Arg) is one of the most widely used amino acids in dietary and pharmacological products. However, the evidence on its usefulness and dose limitations, especially in diabetics is still controversial.

AIM

To investigate the effects of chronic administration of different doses of L-Arg on the cardiac muscle of type 2 diabetic rats.

METHODS

Of 96 male rats were divided into 8 groups as follows (n = 12): Control, 0.5 g/kg L-Arg, 1 g/kg L-Arg, 1.5 g/kg L-Arg, diabetic, diabetic + 0.5 g/kg L-Arg, diabetic + 1 g/kg L-Arg, and diabetic + 1.5 g/kg L-Arg; whereas L-Arg was orally administered for 3 months to all treated groups.

RESULTS

L-Arg produced a moderate upregulation of blood glucose levels to normal rats, but when given to diabetics a significant upregulation was observed, associated with increased nitric oxide, inflammatory cytokines, and malonaldehyde levels in diabetic rats treated with 1 g/kg L-Arg and 1.5 g/kg L-Arg. A substantial decrease in the antioxidant capacity, superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione concentrations, and Nrf-2 tissue depletion were observed at 1 g/kg and 1.5 g/kg L-Arg diabetic treated groups, associated with myocardial injury, fibrosis, α-smooth muscle actin upregulation, and disruption of desmin cardiac myofilaments, and these effects were not noticeable at normal treated groups. On the other hand, L-Arg could significantly improve the lipid profile of diabetic rats and decrease their body weights.

CONCLUSION

L-Arg dose of 1 g/kg or more can exacerbates the diabetes injurious effects on the myocardium, while 0.5 g/kg dose can improve the lipid profile and decrease the body weight.

Characteristics of Plasmodium vivax apicomplexan amino acid transporter 8 (PvApiAT8) in the cationic amino acid transport

Plasmodium vivax is the most widespread malaria parasite affecting humans, and its eradication is challenging due to the spread of drug-resistant parasites and their ability to remain in liver as a dormant stage. These parasites invade and multiply extensively within hepatocytes and erythrocytes in the host, relying on nutrient acquisition for their growth and replication. A promising new treatment aimed at targeting P. vivax involves blocking cationic amino acid uptake, which is a biological source of nutrients for the parasite. Novel Putative Transporter 1 (NPT1), identified as a cationic amino acid transporter in Apicomplexan, has a homologue in Plasmodium species known as apicomplexan amino acid transporter 8 (ApiAT8). This study focuses on P. vivax ApiAT8 to understand its precise role. PvApiAT8 was expressed in Xenopus laevis oocytes and shown to selectively uptake cationic amino acids. The uptake activity of [3H] L-arginine was shown to depend on PvApiAT8 expression time and substrate incubation time. PvApiAT8 was sodium-independent and functioned at pH levels between 6.5 and 8.5, with no efflux activity observed. Kinetic analysis showed saturable uptake for L-arginine consistent with Michaelis-Menten kinetics, with a Km of 1.5 ± 0.3 µM and a Vmax of 25.0 ± 4.8 pmol/oocyte/hr. Inhibition assays further confirmed its selectivity for cationic amino acids such as L-arginine, L-lysine, L-histidine, and L-ornithine. Sequence and structural analyses revealed a conserved binding pocket for cationic amino acids in Plasmodium species, distinct from that in Toxoplasma gondii NPT1. These findings highlight the potential of targeting PvApiAT8 in developing new treatments for P. vivax malaria.

Arginase Activity Inhibition With Thymoquinone Induces a Hybrid Type of Cell-Death in MDA-MB-231 Cell Line

Arginase plays a crucial role in the urea cycle; it also has immunosuppressive and pro-tumor effects. The present study aimed to assess the effects of arginase inhibition by thymoquinone (2-Isopropyl-5-methyl-1,4-benzoquinone), an active compound of Nigella sativa, on cell death in the MDA-MB-231 triple-negative breast tumor cell line. Cell viability assays, Western blot analysis, and flow cytometry analysis were used to characterize oxidative stress and cell death. Our results showed that inhibition of arginase activity with thymoquinone significantly increased intracellular nitric oxide levels and resulted in overproduction of cellular and mitochondrial reactive oxygen species. Reductions in cell viability, cycle arrest, and increased cell death were also observed. Loss of transmembrane mitochondrial potential, activation of caspase-3, -7, and -9, cleavage of PARP, condensation and/or fragmentation of the nuclei, suggest that this cell death involved apoptosis. Furthermore, a cytoplasm vacuole formation and an increase in the ratio of [LC3-II/LC3-I] suggests a concomitant activation of autophagy with apoptosis. Altogether, the present study highlighted that arginase inhibition with thymoquinone induces a hybrid type of cell death defined as oxiapoptophagy. Thus, arginase inhibition with thymoquinone in the MDA-MB-231 cell line could be, in part, involved in the anticancer effect of thymoquinone.

Arginine and colorectal cancer: Exploring arginine-related therapeutic strategies and novel insights into cancer immunotherapies

Concerning the progression of societies and the evolution of lifestyle and dietary habits, the potential for the development of human malignancies, particularly colorectal cancer (CRC), has markedly escalated, positioning it as one of the most prevalent and lethal forms of cancer globally. Empirical evidence indicates that the metabolic processes of cancerous and healthy cells can significantly impact immune responses and the fate of tumors. Arginine, a multifaceted amino acid, assumes a crucial and paradoxical role in various metabolic pathways, as certain tumors exhibit arginine auxotrophy while others do not. Notably, CRC is classified as arginine non-auxotrophic, possessing the ability to synthesize arginine from citrulline. Systemic arginine deprivation and the inhibition of arginine uptake represent two prevalent therapeutic strategies in oncological treatment. However, given the divergent behaviors of tumors concerning the metabolism and synthesis of arginine, one of these therapeutic approaches-namely systemic arginine deprivation-does not apply to CRC. This review elucidates the characteristics of arginine uptake inhibition and systemic arginine deprivation alongside their respective benefits and limitations in CRC. Furthermore, the involvement of arginine in immunotherapeutic strategies is examined in light of the most recent discoveries on various human malignancies.

Bioluminescent Probes for the Detection of Superoxide and Nitric Oxide

The regulation of reactive oxygen species (ROS) such as superoxide (SO) and nitric oxide (NO) is crucial in biology, influencing metabolism and signaling pathways. Imbalances in these species lead to oxidative stress and various diseases. Traditional methods for measuring SO and NO face challenges in terms of sensitivity and specificity, particularly in complex biological matrices. This report introduces bioluminescent probes that leverage the intrinsic sensitivity of bioluminescence for direct and selective detection of SO and NO. These probes release analogs of d-luciferin upon reaction with their target ROS. Following addition of luciferase, luminescence is generated proportional to the amount of accumulated luciferin, allowing for quantitation of SO or NO. Both probes exhibit high specificity, confirmed through cell-free assays and cell-based studies in macrophages, demonstrating their utility in measuring cellular SO and NO production. These assays offer a robust, high-throughput platform for studying ROS, providing direct insights into oxidative stress-related mechanisms.

Hepatotoxic effects of environmentally relevant concentrations of polystyrene microplastics on senescent Zebrafish (Danio rerio): Patterns of stress response and metabolomic alterations

The hepatotoxicity of microplastics (MPs) has garnered increasing attention, but their effects on elderly organisms remain inadequately characterized, particularly concerning hepatic stress response patterns in environmental conditions. In this study, a 10-day exposure period of elderly zebrafish to polystyrene microplastics (PS-MPs, 1 µm) was conducted, with exposure concentrations set at 5.6 × 10-7 µg/L, 5.6 × 10-4 µg/L, and 5.6 × 10-1 µg/L. PS-MPs-induced toxicity varied with concentration: superoxide dismutase (SOD), complement 3 (C3), and complement 4 (C4) initially decreased before rising; 8‑hydroxy-2-deoxyguanosine (8-OhdG), interleukin-6 (IL-6), and interleukin-8 (IL-8) increased at high concentrations. Additionally, catalase (CAT) activity and thiobarbituric acid reactive substances (TBARS) contents rose with concentration. The aged zebrafish liver exhibited differentiation driven by responsiveness; low levels cause homeostatic disruption, and high levels induce genotoxicity and immune activation. LC-MS identified twelve crucial metabolites involved in 18 metabolic pathways, including amino acids (L-tyrosine, l-arginine), lipids (phospholipids, 12(S)-leukotriene B4 and triglycerides), and N-acetylneuraminic acid, related to energy, immunity, and neurological health. Overall, elderly zebrafish exhibited clear dose-dependent thresholds and distinct physiological stress responses under varying concentrations of PS-MPs. These findings reveal how PS-MP exposure can affect physiological health and metabolism, offering critical insights into the ecological risks faced by aging organisms.

Nanoparticles for Biomedical Use Derived from Natural Biomolecules: Tannic Acid and Arginine

Background/Objectives: Tannic acid (TA) is a well-known natural phenolic acid composed of ten gallic acids linked to each other with ester bonding possessing excellent antioxidant properties in addition to antimicrobial and anticancer characteristics. Arginine (ARG) is a positively charged amino acid at physiological pH because of nitrogen-rich side chain. Method: Here, poly(tannic acid-co-arginine) (p(TA-co-ARG)) particles at three mole ratios, TA:ARG = 1:1, 1:2, and 1:3, were prepared via a Mannich condensation reaction between TA and ARG by utilizing formaldehyde as a linking agent. Results: The p(TA-co-ARG) particles in 300-1000 nm size range with smooth surfaces visualized via SEM analysis were attained. Abundant numbers of functional groups, -OH, -NH2, and -COOH stemming from TA and ARG constituent confirmed by FT-IR analysis. The isoelectric point (IEP) of the particles increased from pH 4.98 to pH 7.30 by increasing the ARG ratios in p(TA-co-ARG) particles. The antioxidant capacity of p(TA-co-ARG) particles via gallic acid (GA) and rosmarinic acid (RA) equivalents tests revealed that particles possess concentration-dependent antioxidant potency and increased by TA content. The α-glucosidase inhibition of p(TA-co-ARG) particles (2 mg/mL) 1:1 and 1:2 mole ratios revealed significant enzyme inhibition ability, e.g., 91.3 ± 3.1% and 77.6 ± 12.0%. Interestingly, p(TA-co-ARG) (1:3 ratio) possessed significant antibacterial effectiveness against Escherichia coli (ATCC 8739) and Staphylococcus aureus (ATCC 6538) bacteria. Furthermore, all p(TA-co-ARG) particles at 1000 mg/mL concentration showed >80% toxicity on L929 fibroblast cells and increased as ARG content of p(TA-co-ARG) particles is increased. Conclusions: p(TA-co-ARG) showed significant potential as natural biomaterials for biomedical use.

Synthesis of Arginase Inhibitors: An Overview

Arginase (ARG) is a binuclear manganese-containing metalloenzyme that can convert L-arginine to L-ornithine and urea and plays a key role in the urea cycle. It also mediates different cellular functions and processes such as proliferation, senescence, apoptosis, autophagy, and inflammatory responses in various cell types. In mammals, there are two isoenzymes, ARG-1 and ARG-2; they are functionally similar, but their coding genes, tissue distribution, subcellular localization, and molecular regulation are distinct. In recent decades, the abnormal expression of ARG-1 or ARG-2 has been reported to be increasingly linked to a variety of diseases, including cardiovascular disease, inflammatory bowel disease, Alzheimer's disease, and cancer. Therefore, considering the current relevance of this topic and the need to address the growing demand for new and more potent ARG inhibitors in the context of various diseases, this review was conceived. We will provide an overview of all classes of ARG inhibitors developed so far including compounds of synthetic, natural, and semisynthetic origin. For the first time, the synthesis protocol and optimized reaction conditions of each molecule, including those reported in patent applications, will be described. For each molecule, its inhibitory activity in terms of IC50 towards ARG-1 and ARG-2 will be reported specifying the type of assay conducted.

Innovative insights into the enzymatic hydrolysis of salmon milt: Structural and functional analysis influenced by protease type and enzymolysis time

In this study, hydrolysates were obtained from salmon milts using four proteases (neutrase, papain, trypsin and novozym 11028). The effects of protease type and enzymolysis time (30, 60, 90, and 120 min) on the structural characteristics and functional properties of the hydrolysates were assessed. The fluorescence intensity of all hydrolysates increased as the extension of enzymolysis time, accompanied by an increase in solubility, emulsifying and foaming ability. Trypsin-hydrolysates showed the highest protein recovery and degree of hydrolysis (DH). The electrophoresis indicated that papain-hydrolysates contained more aggregates (>60 kDa), which was confirmed by larger particle size and lower DH. Neutrase-hydrolysate exhibited the smallest particle size and the highest emulsifying and foaming ability, while the highest emulsifying stability appeared in papain-hydrolysates. Neutrase-hydrolysate displayed the strongest antioxidant potential while papain-hydrolysate possessed the weakest. Results demonstrated that the salmon milt protein hydrolysates can be utilized as nutraceutical and functional food ingredients.

Amino Acid Patterns in Children with Autistic Spectrum Disorder: A Preliminary Biochemical Evaluation

BACKGROUND

The metabolism of plasma amino acid (AA) in children with autism spectrum disorder (ASD) has been extensively investigated, yielding inconclusive results. This study aims to characterize the metabolic alterations in AA profiles among early-diagnosed children with ASD and compare the findings with those from non-ASD children.

METHODS

We analyzed plasma AA profiles, measured by ion exchange chromatography, from 1242 ASD children (median age = 4 years; 81% male). Additionally, we studied AA profiles from 488 children, matched for age and free of ASD (control group). Principal component and cluster analysis were employed to explore potential associations within the ASD group and to identify subgroups.

RESULTS

We observed lower plasma levels of glutamine in children with ASD compared to non-ASD children (p < 0.001). Six essential, two conditionally essential, and four non-essential AA were found to be increased in children with ASD. The clustering analysis revealed two groups, labeled Neurological (NEU) and Nutritional (NUT), which included a majority of ASD children (94% and 78%, respectively). The NEU group exhibited high levels of taurine, aspartate, glutamic acid, and ornithine, while the NUT group showed elevated levels of branched-chain AA.

CONCLUSIONS

In children with ASD, we identified some heterogeneous AA patterns that may serve as biochemical signatures of neurological impairment in some individuals, while in others they may indicate nutritional dysregulation.

Herbal and Dietary Supplements as Adjunctive Treatment for Mild SARS-CoV-2 Infection in Italy

During the COVID-19 pandemic, several observational studies proved a certain efficacy of nutraceuticals, herbal products, and other dietary supplements as adjuvant therapies used alongside antiviral drugs. Although their use has not been widespread in Italy, according to preliminary evidence, many supplements with demonstrated immunomodulatory effects, such as vitamins C and D, herbal medicines and essential oils, might relieve the respiratory symptoms of COVID-19, since SARS-CoV-2 can activate inflammasome-mediated inflammatory signaling pathways. Other observational studies have shown that herbal treatments, such as Echinacea purpurea and ginseng, help alleviate respiratory symptoms and reduce serum levels of inflammatory cytokines, which are typically overexpressed in both adult and pediatric SARS-CoV-2 patients. Further, vitamins C and D can attenuate the immune response thanks to their cytokine suppression ability and to their known antimicrobial activity and potential to modulate T helper cell response. The strong immune response triggered by SARS-CoV-2 infection is responsible for the severity of the disease. Preliminary data have also shown that L-arginine, an endothelial-derived relaxing factor, is able to modulate endothelial damage, which appears to be one of the main targets of this systemic disease. Finally, some essential oils and their isolated compounds, such as eucalyptol, may be helpful in reducing many of the respiratory symptoms of COVID-19, although others, such as menthol, are not recommended, since it can lead to an undervaluation of the clinical status of a patient. In this narrative review, despite the lack of strong evidence in this field, we aimed to give an overview of the current available literature (mainly observational and cross-sectional studies) regarding herbal products and dietary supplements and their use in the treatment of mild disease from SARS-CoV-2 infection. Obviously, dietary supplements and herbal products do not constitute a standardized treatment for COVID-19 disease, but they could represent an adjunctive and useful treatment when used together with antivirals.

Effect of Ideal Amino Acid Ratio of Arginine to Lysine on Intake, Nutrient Digestibility, Growth Performance, Antibody Titers of Newcastle Disease and Infectious Bronchitis Disease, and Carcass Characteristics of Broilers

This study aimed to assess the effects of different arginine (Arg) to lysine (Lys) ratios on feed intake, nutrient digestibility, growth performance, carcass characteristics, and antibody titers of Newcastle disease (ND) and infectious bronchitis (IB) disease in broilers during 35 days of trial. For this purpose, a total of 816 day-old broiler birds having an average weight of 38 ± 3 g were divided into six dietary treatments in such a way that each treatment had eight replicates and each replicate had 17 birds. The treatments were 0.95 (1.19/1.25, 1.12/1.18, and 1.05/1.1), 1 (1.25/1.25, 1.18/1.18, and 1.1/1.1), 1.05 (1.31/1.25, 1.24/1.18, and 1.17/1.1), 1.10 (1.38/1.25, 1.30/1.18, and 1.23/1.1), 1.15 (1.44/1.25, 1.36/1.18, and 1.28/1.1), and 1.20 (1.50/1.25, 1.42/1.18, and 1.34/1.1) Arg/Lys divided into different amounts according to the nutritional needs of starter, grower, and finisher diets, respectively. The results showed that in the finisher phase, the FI was influenced cubically, while in the overall period, a quadratic effect was observed for the FI (p < 0.05). The results of BWG showed that BWG was linearly increased in birds given different Arg/Lys in the grower, finisher, and overall period (p < 0.05). The results also showed that during the grower, finisher, and overall phases, the body weight gain (BWG) was better in birds fed with 1.05 and 1.10 Arg/Lys (p < 0.05). Furthermore, a better feed conversion ratio (FCR) was shown in the starter and grower phases at 1.10 and 1.15 Arg/Lys (p < 0.05). The results of nutrient digestibility explored showed that the experimental treatments had a better effect (p < 0.05) on dry matter and crude fat digestibility in birds fed with 1.19/1.25, 1.12/1.18, and 1.05/1.1 and 1.25/1.25, 1.18/1.18, and 1.1/1.1 Arg/Lys in their diets while the crude protein digestibility remained unaffected with different treatments (p > 0.05). The treatments had no effect (p > 0.05) on relative organ weights, immune organs, and carcass characteristics. However, higher titers of ND and IBD were observed in birds fed with Arg/Lys of 1.38/1.25, 1.30/1.18, and 1.23/1.1 and 1.50/1.25, 1.42/1.18, and 1.34/1.1 in their diets (p < 0.05). Based on the results of the current study, it is concluded that the inclusion levels of 1.38/1.25, 1.30/1.18, and 1.23/1.1, and 1.44/1.25, 1.36/1.18, and 1.28/1.1 Arg/Lys resulted in better growth performance and immune response in the broiler birds, respectively. Therefore, adjusting the levels of Arg/Lys in feed is recommended to enhance broilers' growth performance and immune response.

Putative biomarkers of hepatic dysfunction in critically ill sepsis patients

Sepsis is a major cause of morbidity and mortality worldwide. Among the various types of end-organ damage associated with sepsis, hepatic injury is linked to significantly higher mortality rates compared to dysfunction in other organ systems. This study aimed to investigate potential biomarkers of hepatic injury in sepsis patients through a multi-center, case-control approach. We enrolled three matched cohorts: 37 sepsis patients with hepatic dysfunction (S-HD), 37 sepsis patients without hepatic dysfunction (S-CON), and 18 healthy controls (HC). We measured five proposed biomarkers of hepatic dysfunction-ARG1, MDH1, GSTα, 5-NT, and SDH-using multiplex immunoassays. These biomarkers were compared to traditional markers of hepatic dysfunction, including albumin, bilirubin, ALT, AST, and GGT, across the cohorts using both conventional statistical methods and machine learning techniques. The median age of participants was comparable across cohorts: S-HD (65.0 years, IQR 49.5-82.5), S-CON (65.0 years, IQR 48.0-81.5), and HC (62.5 years, IQR 53.0-65.0; P = 0.794). Patients with hepatic dysfunction (S-HD) exhibited higher illness severity scores compared to those without hepatic dysfunction (S-CON): MODS scores were median 7.0 (IQR 4.0-10.0) in S-HD versus median 4.0 (IQR 2.0-7.0) in S-CON (P = 0.005), and SOFA scores were median 7.0 (IQR 4.0-11.0) in S-HD versus median 3.0 (IQR 2.0-6.0) in S-CON (P < 0.001). Hemoglobin and platelet counts were lower, while creatinine levels were higher in S-HD compared to S-CON (P < 0.05). On ICU Day 1, bilirubin, ALT, AST, GGT, and INR were significantly elevated in S-HD relative to S-CON (P ≤ 0.001), and albumin levels were lower (P < 0.05). Additionally, ARG1, GSTα, 5-NT, and SDH were significantly higher in S-HD patients on ICU Day 1 compared to S-CON (P < 0.05). ARG1, MDH1, and SDH showed positive correlations with AST, ALT, and MODS (P < 0.01). From ICU Day 1 to Day 7, ARG1, GSTα, SDH, and AST levels significantly decreased in S-HD patients (P < 0.05), whereas MDH1 and 5-NT levels did not. Among the proposed biomarkers, GSTα and 5-NT did not correlate with traditional hepatic dysfunction markers but were significant in identifying S-HD patients (feature importance 0.131 and 0.097, respectively) in a random forest classification model. This comprehensive model demonstrated excellent performance in distinguishing sepsis patients with hepatic injury, with sensitivity 0.93, specificity 0.94, NPV 0.94, PPV 0.94, and AUC 0.94. The biomarkers ARG1, MDH1, GSTα, 5-NT, and SDH show promise as novel indicators of hepatic dysfunction associated with sepsis. This study provides a foundational basis for subsequent research aimed at characterizing and clinically validating these markers. Future investigations should focus on integrating these potential biomarkers into routine laboratory assessments for sepsis and related hepatic injury.

Molecular and cellular regulators of embryo implantation and their application in improving the implantation potential of IVF-derived blastocysts

Background

In vitro fertilization (IVF) and embryo transfer (ET) are widely used in reproductive biology. Despite the transfer of high-quality blastocysts, the implantation rate of IVF-derived blastocysts remains low after ET.

Methods

This article provides a comprehensive review of current research on embryo implantation regulators and their application to improve the implantation potential of IVF-derived blastocysts.

Main Findings

The in vivo mouse model revealed selective proteolysis immediately after expression in activated blastocysts, that is, degradation of ERα expression in activated blastocysts regulated by the ubiquitin-proteasome pathway, followed by completion of blastocyst implantation. Treatment of blastocysts to induce appropriate protein expression during in vitro culture prior to ET is a useful approach for improving implantation rates. This approach showed that combined treatment with PRL, EGF, and 4-OH-E2 (PEC) improved the blastocyst implantation rates. Furthermore, arginine and leucine drive reactive oxygen species (ROS)-mediated integrin α5β1 expression and promote blastocyst implantation.

Conclusion

Findings based on analysis of molecular and cellular regulators are useful for improving the implantation potential of IVF-derived blastocysts. These approaches may help to elucidate the mechanisms underlying the completion of the blastocyst implantation, although further investigation is required to improve the success of implantation and pregnancy.

Impact of Lysine to Methionine Ratios on Antioxidant Capacity and Immune Function in the Rumen of Tibetan Sheep: An RNA-Seq Analysis

With global protein prices on the rise, lowering protein levels in animal feed, together with balancing diet composition and reducing nitrogen emissions, can both reduce the environmental impact of agriculture and save on feed costs. However, the formulation of an ideal amino acid (AA) composition is crucial for better protein utilization by livestock. This study aimed to investigate the effects of different lysine to methionine ratios on the antioxidant capacity and immune function of the rumen in Tibetan sheep. Ninety male Tibetan sheep, weaned at 2 months of age, were randomly divided into three groups (1:1, 2:1 and 3:1 lysine ratios) and subjected to a 100-day feeding trial. RNA sequencing (RNA-seq) was utilized to analyse the impact of different AA ratios on gene expression in rumen tissue, whereas the levels of antioxidant enzymes (total antioxidant capacity [T-AOC], superoxide dismutase [SOD], glutathione peroxidase [GSH-Px] and catalase [CAT]) and immunoglobulins (immunoglobulin A [IgA], immunoglobulin G [IgG] and immunoglobulin M [IgM]) were evaluated. The results indicated that the 1:1 group significantly upregulated the expression of PTGS2, PLA2G12A and PLA2G4 genes, enhancing antioxidant enzyme activity, reducing free radical production and modulating systemic immune responses. COL16A1 and KCNK5 were highly expressed in the protein digestion and absorption pathway, maintaining the structural integrity and function of the rumen epithelium. BMP4 and TGFBR2 were significantly enriched in the cytokine-cytokine receptor interaction pathway and positively correlated with CAT and T-AOC. ITGA8 was upregulated in the 1:1 group, participating in the regulation of various cellular signalling pathways. ATP2B1 was enriched in the cyclic guanosine monophosphate (cGMP)- protein kinase G (PKG) signalling and mineral absorption pathways, primarily influencing oxidative stress and immune responses by regulating intracellular calcium ion concentration. This study demonstrates that a 1:1 lysine to methionine ratio is most beneficial for enhancing the antioxidant capacity and immune function of the rumen in Tibetan sheep.

The potential role of amino acids in myopia: inspiration from metabolomics

BACKGROUND

Due to the high prevalence of myopia, there is a growing need for the identification of myopia intervention mechanisms and targets. Metabolomics has been gradually used to investigate changes in myopia tissue metabolites over the last few years, but the potential physiological and pathological roles of amino acids and their downstream metabolites discovered by metabolomics in myopia are not fully understood.

AIM OF REVIEW

Aim to explore the possible relationship between amino acid metabolism and the occurrence and development of myopia, we collected a total of 21 experimental studies related to myopia metabolomics. Perform pathway analysis using MetaboAnalyst online software. We have identified over 20 amino acids that may be associated with the development of myopia. Among them, 19 types of amino acids are common amino acids. We discussed their possible mechanisms affecting myopia and proposed future prospects for treating myopia.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Our analysis results show that metabolomics research on myopia involves many important amino acids. We have collected literature and found that research on amino acid metabolism in myopia mainly focuses on downstream small molecule substances. Amino acids and their downstream metabolites affect the development of myopia by participating in important biochemical processes such as oxidative stress, glucose metabolism, and lipid metabolism. Enzymes, receptors, and cytokines that regulate amino acid metabolism may become potential targets for myopia treatment.

The central role of creatine and polyamines in fetal growth restriction

Placental insufficiency often correlates with fetal growth restriction (FGR), a condition that has both short- and long-term effects on the health of the newborn. In our study, we analyzed placental tissue from infants with FGR and from infants classified as small for gestational age (SGA) or appropriate for gestational age (AGA), performing comprehensive analyses that included transcriptomics and metabolomics. By examining villus tissue biopsies and 3D trophoblast organoids, we identified significant metabolic changes in placentas associated with FGR. These changes include adaptations to reduced oxygen levels and modifications in arginine metabolism, particularly within the polyamine and creatine phosphate synthesis pathways. Specifically, we found that placentas with FGR utilize arginine to produce phosphocreatine, a crucial energy reservoir for ATP production that is essential for maintaining trophoblast function. In addition, we found polyamine insufficiency in FGR placentas due to increased SAT1 expression. SAT1 facilitates the acetylation and subsequent elimination of spermine and spermidine from trophoblasts, resulting in a deficit of polyamines that cannot be compensated by arginine or polyamine supplementation alone, unless SAT1 expression is suppressed. Our study contributes significantly to the understanding of metabolic adaptations associated with placental dysfunction and provides valuable insights into potential therapeutic opportunities for the future.

PEG-BCT-100 and Canavanine Synergistically Induce Apoptosis in Arginine Biosynthetic Enzyme-Deficient Pancreatic Cancer

SIGNIFICANCE

This study investigates the synergistic antitumor effect of PEG-BCT-100, an arginase, in clinical trials, with canavanine in pancreatic cancer, in vitro and in vivo. The treatment induces cancer cell apoptosis while sparing normal fibroblasts. Our findings suggest heightened susceptibility of pancreatic tumors deficient in arginine biosynthesis enzymes ASS1 and OTC.

Effects of dietary methionine on the growth and protein synthesis of juvenile Chinese mitten crabs (Eriocheir sinensis) fed fish meal-free diets

This study investigated the effects of dietary methionine (Met) on growth performance and protein synthesis in juvenile Chinese mitten crabs (Eriocheir sinensis) fed fish meal (FM)-free diets. Three diets free of FM containing 0.48% (LM), 1.05% (MM), and 1.72% (HM) Met were assessed, and the cysteine content in all the diets was adjusted to 0.46%. The control diet contained 35% FM without Met supplementation. Extra lysine was added to all of the FM-free diets to match the lysine level in the control diet. Juvenile E. sinensis (800 crabs weighing 0.74 ± 0.01 g each) were fed these four diets for eight weeks, with five replicates for each treatment. Both the LM and HM groups presented lower weight gain than all the other groups did (P = 0.002). The survival of the crabs was lower in the LM and HM groups than in the MM group (P = 0.005). Compared with those in the other groups, the growth performance of the crabs in the MM group improved, and lipid deposition and protein accumulation increased. These positive outcomes are associated with high protein expression linked to the mammalian target of the rapamycin (mTOR) pathway and low expression of genes and proteins linked to the PRKR-like endoplasmic reticulum kinase (PERK) pathway. The study of Met supplementation has explored the response of the PERK pathway through reducing glutathione (GSH) levels to promote protein synthesis. The injection of Met and L-buthionine-sulfoximine (BSO), an inhibitor of GSH synthesis, suppressed GSH production and altered the expression of genes and proteins related to protein synthesis pathways. This study suggests that Met supplementation in FM-free diets can increase the growth and protein synthesis of E. sinensis by modulating specific cellular pathways, particularly the mTOR and PERK pathways.

Microbial changes and associated metabolic responses modify host plant adaptation in Stephanitis nashi

Symbiotic microorganisms are essential for the physiological processes of herbivorous pests, including the pear lace bug Stephanitis nashi, which is known for causing extensive damage to garden plants and fruit trees due to its exceptional adaptability to diverse host plants. However, the specific functional effects of the microbiome on the adaptation of S. nashi to its host plants remains unclear. Here, we identified significant microbial changes in S. nashi on 2 different host plants, crabapple and cherry blossom, characterized by the differences in fungal diversity as well as bacterial and fungal community structures, with abundant correlations between bacteria or fungi. Consistent with the microbiome changes, S. nashi that fed on cherry blossom demonstrated decreased metabolites and downregulated key metabolic pathways, such as the arginine and mitogen-activated protein kinase signaling pathway, which were crucial for host plant adaptation. Furthermore, correlation analysis unveiled numerous correlations between differential microorganisms and differential metabolites, which were influenced by the interactions between bacteria or fungi. These differential bacteria, fungi, and associated metabolites may modify the key metabolic pathways in S. nashi, aiding its adaptation to different host plants. These results provide valuable insights into the alteration in microbiome and function of S. nashi adapted to different host plants, contributing to a better understanding of pest invasion and dispersal from a microbial perspective.

Considerations on amino acid patterns in the natural felid diet: a review

Amino acids are essential for the growth, development, and reproduction of carnivores. This literature review summarizes the amino acid patterns of different raw diets including whole prey, body tissue and muscle for felids under human care. In general, natural prey (and its parts) meet the minimum essential amino acid requirements outlined by the National Research Council for adult cats. On a whole-prey diet, lysine and methionine far exceed requirements, while histidine approaches the minimum threshold. However, histidine concentration is higher in muscle meat. Body tissues, except for the skin, demonstrate no deficiency in essential amino acids. Notably, non-essential amino acids are found in raw meat diets in elevated concentrations, and their levels remain stable, akin to those of essential amino acids. Although felid requirements for non-essential amino acids are not specified, attention should be paid to their role in nutrition. While the amino acid patterns of diverse raw diets show no significant variation, the impact of prolonged single-source protein may require attention.

SYNLAC prime probiotics enhances growth performance, and resistance of white shrimp, Penaeus vannamei to Enterocytozoon hepatopenaei and Vibrio alginollyticus: Insights into immune and metabolic pathway modulations

This study explores the impact of SYNLAC Prime probiotics on the growth performance, health status, and metabolic profile of white shrimp, Penaeus vannamei. Shrimp fed with the experimental diets, including the control diet without probiotic supplementation, and the diets supplemented with SYNLAC Prime probiotics at concentrations of 105 CFU (g diet)-1 (P5) and 106 CFU (g diet)-1 (P6) for 56 days. Results indicated a significant enhancement in growth performance in probiotic-treated shrimp relative to the control group, attributed to structural improvements in the digestive tract, particularly the increased abundances of B cells in the hepatopancreas. The administration of dietary probiotics markedly reduced the severity of Enterocytozoon hepatopenaei (EHP) infection and decreased cumulative mortalities following Vibrio alginolyticus challenge. Shrimp in the P6 group exhibited significant elevations in phenoloxidase activity, respiratory burst, lysozyme activity and phagocytic activity compared to control group. Furthermore, there was an upregulation of several immune-related genes in hepatopancreas, including serine protease (SP), prophenoloxidase (proPO) I, proPO II, and penaeidin 3a. Additionally, the expression of β-1, 3-glucan binding protein and SP mRNA was significantly increased in hemocytes. Untargeted metabolomics analysis using LC-MS/MS revealed significant changes in the hepatopancreas metabolic profile, highlighting alterations in energy metabolisms pathways, such as citrate cycle and nicotinate and nicotinamide metabolism, as well as amino acid metabolisms pathways including arginine and proline metabolism, taurine and hypotaurine metabolism, and histidine metabolism. These findings underscore the potential of SYNLAC Prime probiotics in enhancing shrimp growth, immune function, and metabolic pathways, offering valuable insights for advancing health management strategies in shrimp aquaculture.

Macrophage polarization and metabolic reprogramming in abdominal aortic aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) is a macrovascular disease with high morbidity and mortality in the elderly. The limitation of the current management is that most patients can only be followed up until the AAA diameter increases to a threshold, and surgical intervention is recommended. The development of preventive and curative drugs for AAA is urgently needed. Macrophage-mediated immune inflammation is one of the key pathological links in the occurrence and development of AAA.

AIMS

This review article aims to evaluate the impact of immunometabolism on macrophage biology and its role in AAA.

METHODS

We analyze publications focusing on the polarization and metabolic reprogramming in macrophages as well as their potential impact on AAA, and summarize the potential interventions that are currently available to regulate these processes.

RESULTS

The phenotypic and functional changes in macrophages are accompanied by significant alterations in metabolic pathways. The interaction between macrophage polarization and metabolic pathways significantly influences the progression of AAA.

CONCLUSION

Macrophage polarization is a manifestation of the gross dichotomy of macrophage function into pro-inflammatory killing and tissue repair, that is, classically activated M1 macrophages and alternatively activated M2 macrophages. Macrophage functions are closely linked to metabolic changes, and the emerging field of immunometabolism is providing unique insights into the role of macrophages in AAA. It is essential to further investigate the precise metabolic changes and their functional consequences in AAA-associated macrophages.

Gene expression differences associated with intrinsic hindfoot muscle loss in the jerboa, Jaculus jaculus

Vertebrate animals that run or jump across sparsely vegetated habitats, such as horses and jerboas, have reduced the number of distal limb bones, and many have lost most or all distal limb muscle. We previously showed that nascent muscles are present in the jerboa hindfoot at birth and that these myofibers are rapidly and completely lost soon after by a process that shares features with pathological skeletal muscle atrophy. Here, we apply an intra- and interspecies differential RNA-Seq approach, comparing jerboa and mouse muscles, to identify gene expression differences associated with the initiation and progression of jerboa hindfoot muscle loss. We show evidence for reduced hepatocyte growth factor and fibroblast growth factor signaling and an imbalance in nitric oxide signaling; all are pathways that are necessary for skeletal muscle development and regeneration. We also find evidence for phagosome formation, which hints at how myofibers may be removed by autophagy or by nonprofessional phagocytes without evidence for cell death or immune cell activation. Last, we show significant overlap between genes associated with jerboa hindfoot muscle loss and genes that are differentially expressed in a variety of human muscle pathologies and rodent models of muscle loss disorders. All together, these data provide molecular insight into the process of evolutionary and developmental muscle loss in jerboa hindfeet.

Supplementation of l-arginine in pregnant gilts affects the protein abundance of DNMT1 in 35-day fetuses

Maternal nutrition is one of the main environmental factors regulating gene expression during fetal development through epigenetic modifications. Some nutrients, such as the amino acid l-arginine, are added to maternal diets to modulate gene expression, improve the reproductive performance of females, and enhance conceptus development. This study investigated the hypothesis that supplementation of pregnant gilts with l-arginine regulates gene expression in conceptuses through epigenetic mechanisms. For this, fetal programming phenotypic markers, the expression of key epigenetic genes, and the abundance of DNA methylation proteins (DNMT3A and DNMT1) were evaluated in 25- and 35-day conceptuses from gilts supplemented (ARG) or not (CON) with 1.0 % l-arginine during early gestation. At 25 days, there were no significant differences in phenotypic markers between CON and ARG embryos (P > 0.05). Similarly, no differences were found between CON and ARG fetuses at 35 days (P > 0.05). Maternal supplementation with l-arginine did not influence the expression of the evaluated key epigenetic genes in pig embryos or fetuses, nor DNMT3A protein abundance (P > 0.05); on the other hand, DNMT1 protein abundance was lower in ARG fetuses (P = 0.002). It is concluded that supplementation of l-arginine in pregnant gilts affects epigenetic mechanisms, such as DNA methylation, in 35-day fetuses through regulation of DNMT1 levels. Further studies using transcriptomic and proteomic analysis could reveal additional epigenetic modifications in embryos and fetuses following maternal supplementation with l-arginine.

Amino acid metabolic reprogramming in the tumor microenvironment and its implication for cancer therapy

Amino acids are essential building blocks for proteins, crucial energy sources for cell survival, and key signaling molecules supporting the resistant growth of tumor cells. In tumor cells, amino acid metabolic reprogramming is characterized by the enhanced uptake of amino acids as well as their aberrant synthesis, breakdown, and transport, leading to immune evasion and malignant progression of tumor cells. This article reviews the altered amino acid metabolism in tumor cells and its impact on tumor microenvironment, and also provides an overview of the current clinical applications of amino acid metabolism. Innovative drugs targeting amino acid metabolism hold great promise for precision and personalized cancer therapy.

Nutraceutical interventions for erectile dysfunction: a systematic review and network meta-analysis

BACKGROUND

Although nutraceutical-based treatments are often offered for erectile dysfunction (ED), their efficacy remains doubtful, and the choice of one substance over the other is challenged by the dearth of head-to-head comparative studies.

AIM

We aimed to compare the efficacy of available nutraceutical interventions, alone or in combination with phosphodiesterase type 5 inhibitors (PDE5i), in improving erectile function in men with ED through a network meta-analysis (NMA), which incorporates direct and indirect evidence into one model thus generating a hierarchy of effectiveness.

METHODS

PubMed, Scopus, Web of Sciences, and Cochrane Library databases were searched for randomized placebo-controlled trials (RCTs) assessing the effect of any nutraceutical regimen in improving erectile function when compared to each other, placebo, and/or PDE5i in men with ED. Data were included in a random-effects NMA, where efficacy of treatments was ranked by surface under the cumulative ranking curve (SUCRA). Two NMAs were also conducted separately for organic and non-organic ED. Reciprocal comparisons between all treatments were analyzed by league tables.

OUTCOMES

The main outcome was the standardized mean difference in the score of the International Index of Erectile Function (IIEF)-5 or IIEF-6.

RESULTS

Fifteen RCTs provided information on 1000 men with ED. In the overall NMA, compared to placebo, the combination propionyl L-carnitine (PLC) + acetyl L-carnitine (ALC) + Sildenafil was associated with the highest SUCRA (97%) in improving erectile function score, followed by L-Arginine + Tadalafil (84%), Sildenafil (79%), Tadalafil (72%), and L-Arginine (52%). No other treatment regimen showed efficacy with statistical significance. In patients with organic ED, the efficacy of Sildenafil and Tadalafil was significantly improved by PLC + ALC and L-Arginine, respectively. On the contrary, in non-organic ED, nutraceuticals did not improve the therapeutic performance of daily Tadalafil.

CLINICAL IMPLICATIONS

This NMA contributes valuable insights into the potential of nutraceutical interventions for ED.

STRENGTHS AND LIMITATIONS

We employed strict inclusion criteria related to study design and diagnostic tool, ensuring the assumption of transitivity and the consistency of the analysis.

CONCLUSION

Against a background of general ineffectiveness of most nutraceutical interventions, L-Arginine and the mix PLC + ALC appeared to be of some usefulness in improving erectile function, especially in combination with PDE5i in organic ED.

The roles of arginases and arginine in immunity

Arginase activity and arginine metabolism in immune cells have important consequences for health and disease. Their dysregulation is commonly observed in cancer, autoimmune disorders and infectious diseases. Following the initial description of a role for arginase in the dysfunction of T cells mounting an antitumour response, numerous studies have broadened our understanding of the regulation and expression of arginases and their integration with other metabolic pathways. Here, we highlight the differences in arginase compartmentalization and storage between humans and rodents that should be taken into consideration when assessing the effects of arginase activity. We detail the roles of arginases, arginine and its metabolites in immune cells and their effects in the context of cancer, autoimmunity and infectious disease. Finally, we explore potential therapeutic strategies targeting arginases and arginine.

Nitric Oxide Signaling and Sensing in Age-Related Diseases

Nitric oxide (NO) is a key signaling molecule involved in numerous physiological and pathological processes within the human body. This review specifically examines the involvement of NO in age-related diseases, focusing on the cardiovascular, nervous, and immune systems. The discussion delves into the mechanisms of NO signaling in these diseases, emphasizing the post-translational modifications of involved proteins, such as S-nitrosation and nitration. The review also covers the dual nature of NO, highlighting both its protective and harmful effects, determined by concentration, location, and timing. Additionally, potential therapies that modulate NO signaling, including the use of NO donors and nitric oxide synthases (NOSs) inhibitors in the treatment of cardiovascular, neurodegenerative, and oncological diseases, are analyzed. Particular attention is paid to the methods for the determination of NO and its derivatives in the context of illness diagnosis and monitoring. The review underscores the complexity and dual role of NO in maintaining cellular balance and suggests areas for future research in developing new therapeutic strategies.

Effects of supplementing rumen-protected arginine on performance of transition cows

An experiment was conducted to determine the effects of supplementing rumen-protected arginine (RPA) on productive performance in dairy cows. One-hundred and 2 cows were blocked by parity and then by energy-corrected milk (ECM) yield. Within block, cows were randomly assigned to control (CON) that received 200 g/d of a mixture of hydrogenated soybean oil and heat-treated soybean meal to supply 30 g of metabolizable protein (MP), or 200 g/d of a product containing 30 g of metabolizable arginine (RPA), which increased the dietary arginine from 5.7 to 7.5% of the MP from 250 d of gestation to 21 d postpartum. After 21 d postpartum, cows were fed the same diet and data were collected until 84 d postpartum. Cows fed RPA produced an additional 2.5 kg of colostrum (5.3 vs. 7.8 ± 1.0 kg) and 220 g more immunoglobulin G (526 vs. 746 ± 93 g) than CON cows. Supplementing RPA increased the yields of milk (32.8 vs. 34.9 ± 1.0 kg/d), ECM (37.8 vs. 40.9 ± 1.2 kg/d), and milk total solids (4.48 vs. 4.86 ± 0.14 kg/d) in the first 21 DIM. The benefits of RPA extended beyond the period of supplementation, with a 6.4% increase in yield of ECM per kg of dry matter consumed in all cows (1.88 vs. 2.00 ± 0.05 kg/kg) and an increase in ECM yield, but only in parous cows (44.2 vs. 48.5 ± 1.5 kg/d). Feeding RPA increased the concentrations of urea N in plasma pre- (12.5 vs. 13.9 ± 0.4 mg/dL) and postpartum (11.6 vs. 13.2 ± 0.4 mg/dL), and in milk during the first 21 d postpartum (11.0 vs. 12.0 ± 0.3 mg/dL). Treatment did not affect the concentrations of AA in plasma prepartum, but feeding RPA tended to increase citrulline (72.5 vs. 77.5 ± 2.7 μM), whereas RPA either tended to decrease isoleucine (129.5 vs. 120.9 ± 5.7 μM) or decreased the concentrations of leucine (181.3 vs. 170.2 ± 6.4 μM) and valine (293.2 vs. 276.7 ± 10.4 μM) postpartum. Feeding RPA increased the relative expression of transcripts involved in AA transport (SLC38A4), urea cycle (ARG1), and gluconeogenesis (PC, PEPCK, and G6PC) in hepatic tissue. Feeding diets to supply additional arginine as RPA during the transition period benefited productive performance in dairy cows that extended beyond the period of supplementation despite minor changes in plasma AA concentrations.

Extracellular vesicles of Bacteroides uniformis induce M1 macrophage polarization and aggravate gut inflammation during weaning

Weaning process is commonly associated with gastrointestinal inflammation and dysbiosis of the intestinal microbes. In particular, the impact of gut bacteria and extracellular vesicles on the etiology of intestinal inflammation during weaning is not well understood. We have uncovered a potential link between gut inflammation and the corresponding variation of macrophage bacterial sensing and pro-inflammatory polarization during the weaning process of piglets through single-cell transcriptomic analyses. We conducted a comprehensive analysis of bacterial distribution across the gastrointestinal tract and pinpointed Bacteroides uniformis enriching in piglets undergoing weaning. Next, we found out that exposure to B. uniformis-derived extracellular vesicles (BEVs) exacerbated gut inflammation in a murine colitis model while recruiting and polarizing intestinal macrophages toward a pro-inflammatory phenotype. BEVs modulated the function of macrophages cultured in vitro by suppressing the granulocyte-macrophage colony-stimulating factor/signal transducer and activator of transcription 5/arginase 1 pathway, thereby affecting polarization toward an M1-like state. The effects of BEVs were verified both in the macrophage clearance murine model and by using an adoptive transfer assay. Our findings highlight the involvement of BEVs in facilitating the polarization of pro-inflammatory macrophages and promoting gut inflammation during weaning.

Redox remodeling of central metabolism as a driving force for cellular protection, proliferation, differentiation, and dysfunction

The production of reactive oxygen species (ROS) is elevated via metabolic hyperactivation in response to a variety of stimuli such as growth factors and inflammation. Tolerable amounts of ROS moderately inactivate enzymes via oxidative modification, which can be reversed back to the native form in a redox-dependent manner. The excessive production of ROS, however, causes cell dysfunction and death. Redox-reactive enzymes are present in primary metabolic pathways such as glycolysis and the tricarboxylic acid cycle, and these act as floodgates for carbon flux. Oxidation of a specific form of cysteine inhibits glyceraldehyde-3-phosphate dehydrogenase, which is reversible, and causes an accumulation of upstream intermediary compounds that increases the flux of glucose-6-phosphate to the pentose phosphate pathway. These reactions increase the NADPH and ribose-5-phosphate that are available for reductive reactions and nucleotide synthesis, respectively. On the other hand, oxidative inactivation of mitochondrial aconitase increases citrate, which is then recruited to synthesize fatty acids in the cytoplasm. Decreases in the use of carbohydrate for ATP production can be compensated via amino acid catabolism, and this metabolic change makes nitrogen available for nucleic acid synthesis. Coupling of the urea cycle also converts nitrogen to urea and polyamine, the latter of which supports cell growth. This metabolic remodeling stimulates the proliferation of tumor cells and fibrosis in oxidatively damaged tissues. Oxidative modification of these enzymes is generally reversible in the early stages of oxidizing reactions, which suggests that early treatment with appropriate antioxidants promotes the maintenance of natural metabolism.

Metabolomic differences between exanthematous drug eruption and infectious mononucleosis

BACKGROUND

Exanthematous drug eruption and infectious mononucleosis (IM) are both exanthematous diseases. Current research on exanthematous drug eruption and IM mainly targets identifying these disorders, the resulting differences at the metabolism level have not yet been systematically analyzed.

MATERIALS AND METHODS

A total of 30 cases of exanthematous drug eruption and IM, 10 patients without exanthema and 10 healthy volunteers were enrolled, 3 mL of fasting venous blood was collected, the serum metabolite content was detected by gas chromatography-mass spectrometry metabolomics.

RESULTS

A total of 165 metabolites were identified, exhibiting significant differences in plasma metabolic trends between exanthematous drug eruption and IM, and pinpointed 28 potential biomarkers. Notable changes were seen in the metabolic activities of the pentose phosphate pathway (PPP), tricarboxylic acid cycle (TCA-cycle), and galactose metabolism, characterized by increased levels of gluconate, gluconolactone, glucose, galactaric acid, and mannose, along with decreased amounts of pyruvic acid, succinic acid, malic acid, and glycerol, indicating an impairment in the exanthematous drug eruption group's capacity to endure oxidative stress and regulate energy metabolism. In contrast to its medication without rash counterpart, the exanthematous drug eruption group's plasma displayed distinct metabolic routes, predominantly in the processing of arginine and proline, along with the TCA. This resulted in a marked reduction in urea levels and a rise in pyruvate, citrate, and ornithine, indicating hypoxic stress as the primary cause of these rashes. In contrast to the healthy control group, the IM group showed 26 potential biomarkers, marked by increased levels of ketoglutaric acid, malic acid, pyruvic acid, and oxoglutaric acid, and reduced amounts of glutamine, galacturonic acid, arachidonic acid, trimethylphosphonic acid ester, gluconolactone, and indole acetic acid. Mainly, the metabolic pathways included the TCA, breaking down alanine, aspartate and glutamate metabolism, and the processing of D-glutamine and D-glutamate metabolism, underscoring the body's crucial role in generating energy and inflammatory agents through the citric acid cycle.

CONCLUSIONS

The comparison of serum metabolomic features of exanthematous drug eruptions and IM outlines a unique pattern closely related to the differences in the pathogenesis of these two exanthematous diseases.

The nutritional metabolic risk index as a predictor of all-cause and cardiovascular mortality: A national cohort study

BACKGROUND

Recent studies show that malnutrition increases all-cause mortality by 1.11 times and cardiovascular mortality by 2.60 times. Similarly, metabolic syndrome raises overall mortality by 40% and cardiovascular mortality by 37%. This research assesses the Nutritional Metabolic Risk Index (NMRI) for predicting these mortality risks.

METHODS

We analyzed data from 14,209 participants in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018, where the NMRI was calculated based on the ratio of GNRI to TyG-WHtR. The relationship between NMRI and mortality was investigated using Kaplan-Meier methods and Cox regression models, with restricted cubic splines (RCS) employed to examine non-linear associations. The predictive capabilities of NMRI, GNRI, and TyG-WHtR for mortality were assessed using receiver operating characteristic curve (ROC) curve analysis.

RESULTS

Over a median follow-up period of 89 months, there were 1358 all-cause deaths and 345 cardiovascular deaths recorded. Cox regression analysis indicated that each unit increase in NMRI was associated with an 8% reduction in all-cause mortality risk and a 15% reduction in cardiovascular mortality risk. RCS analysis found a nonlinear negative correlation between NMRI and both all-cause and cardiovascular mortality. NMRI demonstrated superior predictive accuracy for all-cause mortality (AUC: 0.696, 95% CI: 0.682-0.710) and cardiovascular mortality (AUC: 0.713, 95% CI: 0.689-0.737) compared to GNRI and TyG-WHtR (P < 0.05).

CONCLUSIONS

The NMRI is inversely associated with the risk of all-cause and cardiovascular mortality in American adults.

Comprehensive phytochemical profiling and biological activities of Hodgsonia heteroclita subsp. indochinensis seed extracts

Hodgsonia heteroclita subsp. indochinensis, a member of the Cucurbitaceae family, is utilized in traditional medicinal remedies based on indigenous wisdom. This study aimed to comprehensively identify and analyze the bioactive phytoconstituents within H. heteroclita subsp. indochinensis seeds. Seeds were sequentially extracted with n-hexane, ethyl acetate, and methanol. Liquid chromatography-mass spectrometry analysis detected ferulic acid, salicylic acid, cucurbitacin E, stigmasterol glucoside, and β-sitosterol glucoside in all extracts. The total phenolic content in the HH(S)-EtOAc and HH(S)-MeOH was 14.22 ± 1.58 and 12.98 ± 1.03 mg gallic acid equivalent/g, respectively. Consequently, the HH(S)-EtOAc demonstrated antioxidant activity with an IC50 of 1.10 ± 0.28 mg/mL, while the HH(S)-MeOH displayed strong antioxidant potential with an IC50 of 0.04 ± 0.00 mg/mL according to an ABTS assay. Antibacterial evaluations of both the HH(S)-hexane and HH(S)-EtOAc revealed significant activity against Staphylococcus aureus (zone of inhibition (ZOI): 13.67 ± 2.31 and 11.67 ± 1.53 mm, respectively) but limited activity against Escherichia coli (ZOI: 7.33 ± 0.58 and 7.67 ± 0.58 mm, respectively). Additionally, the extracts exhibited low minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values, ranging from 62.50 to 250 mg/mL. The antiproliferative activity of seed extracts was assessed against two breast cancer cell lines (MCF-7 and MDA-MB-231), normal breast cells (MCF10A), and human embryonic kidney (HEK) 293T cells, through MTT and clonogenic assays. The results revealed IC50 values exceeding 400 μg/mL, indicating that the extracts are safe. Furthermore, all seed extracts (50 μg/mL) exhibited potent anti-inflammatory activity, evident by their substantial inhibition of nitric oxide production (p < 0.001) and inducible nitric oxide synthase (iNOS) gene expression (p < 0.05) in LPS-induced RAW264.7. These findings demonstrate the potential for H. heteroclita subsp. indochinensis seed extracts in the development of functional foods, nutraceuticals, and dietary supplements due to their diverse bioactive compounds and substantial biological activities, particularly their anti-inflammatory effects.

Cell volume regulation modulates macrophage-related inflammatory responses via JAK/STAT signaling pathways

Cell volume as a characteristic of changes in response to external environmental cues has been shown to control the fate of stem cells. However, its influence on macrophage behavior and macrophage-mediated inflammatory responses have rarely been explored. Herein, through mediating the volume of macrophages by adding polyethylene glycol (PEG), we demonstrated the feasibility of fine-tuning cell volume to regulate macrophage polarization towards anti-inflammatory phenotypes, thereby enabling to reverse macrophage-mediated inflammation response. Specifically, lower the volume of primary macrophages can induce both resting macrophages (M0) and stimulated pro-inflammatory macrophages (M1) to up-regulate the expression of anti-inflammatory factors and down-regulate pro-inflammatory factors. Further mechanistic investigation revealed that macrophage polarization resulting from changing cell volume might be mediated by JAK/STAT signaling pathway evidenced by the transcription sequencing analysis. We further propose to apply this strategy for the treatment of arthritis via direct introduction of PEG into the joint cavity to modulate synovial macrophage-related inflammation. Our preliminary results verified the credibility and effectiveness of this treatment evidenced by the significant inhibition of cartilage destruction and synovitis at early stage. In general, our results suggest that cell volume can be a biophysical regulatory factor to control macrophage polarization and potentially medicate inflammatory response, thereby providing a potential facile and effective therapy for modulating macrophage mediated inflammatory responses. STATEMENT OF SIGNIFICANCE: Cell volume has recently been recognized as a significantly important biophysical signal in regulating cellular functionalities and even steering cell fate. Herein, through mediating the volume of macrophages by adding polyethylene glycol (PEG), we demonstrated the feasibility of fine-tuning cell volume to induce M1 pro-inflammatory macrophages to polarize towards anti-inflammatory M2 phenotype, and this immunomodulatory effect may be mediated by the JAK/STAT signaling pathway. We also proposed the feasible applications of this PEG-induced volume regulation approach towards the treatment of osteoarthritis (OA), wherein our preliminary results implied an effective alleviation of early synovitis. Our study on macrophage polarization mediated by cell volume may open up new pathways for immune regulation through microenvironmental biophysical clues.

Pathophysiology of Arginases in Cancer and Efforts in Their Pharmacological Inhibition

Arginases are key enzymes that hydrolyze L-arginine to urea and L-ornithine in the urea cycle. The two arginase isoforms, arginase 1 (ARG1) and arginase 2 (ARG2), regulate the proliferation of cancer cells, migration, and apoptosis; affect immunosuppression; and promote the synthesis of polyamines, leading to the development of cancer. Arginases also compete with nitric oxide synthase (NOS) for L-arginine, and their participation has also been confirmed in cardiovascular diseases, stroke, and inflammation. Due to the fact that arginases play a crucial role in the development of various types of diseases, finding an appropriate candidate to inhibit the activity of these enzymes would be beneficial for the therapy of many human diseases. In this review, based on numerous experimental, preclinical, and clinical studies, we provide a comprehensive overview of the biological and physiological functions of ARG1 and ARG2, their molecular mechanisms of action, and affected metabolic pathways. We summarize the recent clinical trials' advances in targeting arginases and describe potential future drugs.

AutoFocus: a hierarchical framework to explore multi-omic disease associations spanning multiple scales of biomolecular interaction

Recent advances in high-throughput measurement technologies have enabled the analysis of molecular perturbations associated with disease phenotypes at the multi-omic level. Such perturbations can range in scale from fluctuations of individual molecules to entire biological pathways. Data-driven clustering algorithms have long been used to group interactions into interpretable functional modules; however, these modules are typically constrained to a fixed size or statistical cutoff. Furthermore, modules are often analyzed independently of their broader biological context. Consequently, such clustering approaches limit the ability to explore functional module associations with disease phenotypes across multiple scales. Here, we introduce AutoFocus, a data-driven method that hierarchically organizes biomolecules and tests for phenotype enrichment at every level within the hierarchy. As a result, the method allows disease-associated modules to emerge at any scale. We evaluated this approach using two datasets: First, we explored associations of biomolecules from the multi-omic QMDiab dataset (n = 388) with the well-characterized type 2 diabetes phenotype. Secondly, we utilized the ROS/MAP Alzheimer's disease dataset (n = 500), consisting of high-throughput measurements of brain tissue to explore modules associated with multiple Alzheimer's Disease-related phenotypes. Our method identifies modules that are multi-omic, span multiple pathways, and vary in size. We provide an interactive tool to explore this hierarchy at different levels and probe enriched modules, empowering users to examine the full hierarchy, delve into biomolecular drivers of disease phenotype within a module, and incorporate functional annotations.

Muscle protein catabolism and splanchnic arginine consumption drive arginine dysregulation during Pseudomonas Aeruginosa induced early acute sepsis in swine

Human sepsis is characterized by increased protein breakdown and changes in arginine and citrulline metabolism. However, it is unclear whether this is caused by changes in transorgan metabolism. We therefore studied in a Pseudomonas aeruginosa induced pig sepsis model the changes in protein and arginine related metabolism on whole body (Wb) and transorgan level. We studied 22 conscious pigs for 18 hours during sepsis, induced by infusing live bacteria (Pseudomonas aeruginosa) or after placebo infusion (control). We used stable isotope tracers to measure Wb and skeletal muscle protein synthesis and breakdown, as well as Wb, splanchnic, skeletal muscle, hepatic and portal drained viscera (PDV) arginine and citrulline disposal and production rates. During sepsis, arginine Wb production (p=0.0146), skeletal muscle release (p=0.0035) and liver arginine uptake were elevated (p=0.0031). Wb de novo arginine synthesis, citrulline production, and transorgan PDV release of citrulline, glutamine and arginine did not differ between sepsis and controls. However, Wb (p<0.0001) and muscle (p<0.001) protein breakdown were increased, suggesting that the enhanced arginine production is predominantly derived from muscle breakdown in sepsis. In conclusion, live-bacterium sepsis increases muscle arginine release and liver uptake, mirroring previous pig endotoxemia studies. In contrast to observations in humans, acute live-bacterium sepsis in pigs does not change citrulline production or arterial arginine concentration. We therefore conclude that the arginine dysregulation observed in human sepsis is possibly initiated by enhanced protein catabolism and splanchnic arginine catabolism, while decreased arterial arginine concentration and citrulline metabolism may require more time to fully manifest in patients.

The immunomicrotope of Leishmania control and persistence

Leishmania is an intracellular protozoan transmitted by sand fly vectors; it causes cutaneous, mucocutaneous, or visceral disease. Its growth and survival are impeded by type 1 T helper cell responses, which entail interferon (IFN)-γ-mediated macrophage activation. Leishmania partially escapes this host defense by triggering immune cell and cytokine responses that favor parasite replication rather than killing. Novel methods for in situ analyses have revealed that the pathways of immune control and microbial evasion are strongly influenced by the tissue context, the micro milieu factors, and the metabolism at the site of infection, which we collectively term the 'immunomicrotope'. Understanding the components and the impact of the immunomicrotope will enable the development of novel strategies for the treatment of chronic leishmaniasis.

Methylphenidate Exposing During Neurodevelopment Alters Amino Acid Profile, Astrocyte Marker and Glutamatergic Excitotoxicity in the Rat Striatum

There is a public health concern about the use of methylphenidate (MPH) since the higher prescription for young individuals and non-clinical purposes is addressed to the limited understanding of its neurochemical and psychiatric consequences. This study aimed to evaluate the impact of early and chronic MPH treatment on the striatum focusing on amino acid profile, glutamatergic excitotoxicity, redox status, neuroinflammation and glial cell responses. Male Wistar rats were treated with MPH (2.0 mg/kg) or saline solution from the 15th to the 44th postnatal day. Biochemical and histological analyses were conducted after the last administration. MPH altered the amino acid profile in the striatum, increasing glutamate and ornithine levels, while decreasing the levels of serine, phenylalanine, and branched-chain amino acids (leucine, valine, and isoleucine). Glutamate uptake and Na+,K+-ATPase activity were decreased in the striatum of MPH-treated rats as well as increased ATP levels, as indicator of glutamatergic excitotoxicity. Moreover, MPH caused lipid peroxidation and nitrative stress, increased TNF alpha expression, and induced high levels of astrocytes, and led to a decrease in BDNF levels. In summary, our results suggest that chronic early-age treatment with MPH induces parallel activation of damage-associated pathways in the striatum and increases its vulnerability during the juvenile period. In addition, data presented here contribute to shedding light on the mechanisms underlying MPH-induced striatal damage and its potential implications for neurodevelopmental disorders.

Development of a quantification method for arginase inhibitors by LC-MS/MS with benzoyl chloride derivatization

Arginase is an enzyme responsible for converting arginine, a semi-essential amino acid, to ornithine and urea. Arginine depletion suppresses immunity via multiple mechanisms including inhibition of T-cell and NK cell proliferation and activity. Arginase inhibition is therefore an attractive mechanism to potentially reverse immune suppression and thus has been explored as a therapy for oncology and respiratory indications. Small molecules targeting arginase present significant bioanalytical challenges for in vitro and in vivo characterization as inhibitors of arginase are typically hydrophilic in nature. The resulting low or negative LogD characteristics are incompatible with common analytical methods such as RP-ESI-MS/MS. Accordingly, a sensitive, high-throughput bioanalytical method was developed by incorporating benzoyl chloride derivatization to increase the hydrophobic characteristics of these polar analytes. Samples were separated by reversed phase chromatography on a Waters XBridge BEH C18 3.5 μm, 30 × 3 mm column using gradient elution. The mass spec was operated in positive mode using electrospray ionization. The m/z 434.1→176.1, 439.4→181.2, 334.9→150.0 and 339.9→150.0 for AZD0011, AZD0011 IS, AZD0011-PL and AZD0011-PL IS respectively were used for quantitation. The linear calibration range of the assay was 1.00-10,000 ng/mL with QC values of 5, 50 and 500 ng/mL. The qualified method presented herein exhibits a novel, robust analytical performance and was successfully applied to evaluate the in vivo ADME properties of boronic acid-based arginase inhibitor prodrug AZD0011 and its active payload AZD0011-PL.

Targeting Leishmania Promastigotes and Amastigotes Forms through Amino Acids and Peptides: A Promising Therapeutic Strategy

Millions of people worldwide are affected by leishmaniasis, caused by the Leishmania parasite. Effective treatment is challenging due to the biological complexity of the parasite, drug toxicity, and increasing resistance to conventional drugs. To combat this disease, the development of specific strategies to target and selectively eliminate the parasite is crucial. This Review highlights the importance of amino acids in the developmental stages of Leishmania as a factor determining whether the infection progresses or is suppressed. It also explores the use of peptides as alternatives in parasite control and the development of novel targeted treatments. While these strategies show promise for more effective and targeted treatment, further studies to address the remaining challenges are imperative.

Salmonella Typhimurium exploits host polyamines for assembly of the type 3 secretion machinery

Bacterial pathogens utilize the factors of their hosts to infect them, but which factors they exploit remain poorly defined. Here, we show that a pathogenic Salmonella enterica serovar Typhimurium (STm) exploits host polyamines for the functional expression of virulence factors. An STm mutant strain lacking principal genes required for polyamine synthesis and transport exhibited impaired infectivity in mice. A polyamine uptake-impaired strain of STm was unable to inject effectors of the type 3 secretion system into host cells due to a failure of needle assembly. STm infection stimulated host polyamine production by increasing arginase expression. The decline in polyamine levels caused by difluoromethylornithine, which inhibits host polyamine production, attenuated STm colonization, whereas polyamine supplementation augmented STm pathogenesis. Our work reveals that host polyamines are a key factor promoting STm infection, and therefore a promising therapeutic target for bacterial infection.

Gut microbiota and metabolic changes in children with idiopathic short stature

BACKGROUND

Idiopathic short stature (ISS) is characterized by short stature with unknown causes. Recent studies showed different gut microbiota flora and reduced fecal short-chain fatty acids in ISS children. However, the roles of the microbiome and metabolites in the pathogenesis of ISS remains largely unknown.

METHODS

We recruited 51 Chinese subjects, comprising 26 ISS children and 25 normal-height control individuals. Untargeted metabolomics was performed to explore the fecal metabolic profiles between groups. A shotgun metagenomic sequencing approach was used to investigate the microbiome at the strains level. Mediation analyses were done to reveal correlations between the height standard deviation (SD) value, the gut microbiome and metabolites.

RESULTS

We detected marked differences in the composition of fecal metabolites in the ISS group, particularly a significant increase in erucic acid and a decrease in spermidine, adenosine and L-5-Hydroxytryptophan, when compared to those of controls. We further identified specific groups of bacterial strains to be associated with the different metabolic profile. Through mediation analysis, 50 linkages were established. KEGG pathway analysis of microbiota and metabolites indicated nutritional disturbances. 13 selected features were able to accurately distinguish the ISS children from the controls (AUC = 0.933 [95%CI, 79.9-100%]) by receiver operating characteristic (ROC) analysis.

CONCLUSION

Our study suggests that the microbiome and the microbial-derived metabolites play certain roles in children's growth. These findings provide a new research direction for better understanding the mechanism(s) underlying ISS.

Impact of increasing dietary standardized ileal digestible arginine to lysine ratio from 0.85 to 1.15 and water-based arginine supplementation on growth performance and gut integrity of weaned pigs

The objective of this experiment was to assess the influence of arginine (Arg) supplementation in water and/or feed on the growth performance and gastrointestinal health of newly weaned pigs. Two hundred and forty pigs (5.06 kg; PIC, Hendersonville, TN) were randomly allocated into 80 mixed-sex pens (3 pigs/pen) and subjected to a 2 × 4 factorial design. Two levels of Arg were supplemented in water (0% or 8% stock, dosed through a 1:128 proportioner) for the first phase (days 0 to 7), and four dietary arginine levels (0.85, 0.95, 1.05, and 1.15) standardized ileal digestible (SID) Arg to Lysine (Lys) ratios for the first two phases (days 0 to 7 and 7 to 21). All treatments were provided a common diet (0.96 SID Arg:Lys) for the last phase days 21 to 42. One pig per pen underwent a dual sugar absorption test of lactulose at 500 mg/kg and mannitol at 50 mg/kg of body weight (BW) via gastric tube on days 7 and 21 postweaning, with blood plasma collected 4 h later. The pig tested on day 7 was subsequently euthanized for intestinal tissue collection. Pen growth performance and feed disappearance were evaluated for 3 phases: days 0 to 7, 7 to 21, and 21 to 42 postweaning. The statistical analysis used linear models to examine the effects of SID Arg:Lys in the feed, Arg level in water, and their interactions, with pen as the experimental unit. Orthogonal contrasts were used to test the linear and quadratic effects of increasing SID Arg:Lys in the diet. Growth performance during the first period exhibited variability, reflected by negative gain-to-feed (G:F) ratios, caused by the enteric health challenge. Consequently, data were analyzed separately for each phase. Increasing dietary SID Arg:Lys caused a linear improvement (P = 0.04) in final BW (18.47 and 21.90 kg, for 0.85 and 1.15 SID Arg:Lys, respectively). A trend (P = 0.09) suggested a linear impact of dietary SID Arg:Lys on average daily gain during days 21 to 42. Arg supplementation, whether administered through water or diet, did not affect lactulose and mannitol absorption on both days 7 and 21, nor did it alter histological measurements in the collected ileum tissues on day 7 postweaning. In conclusion, increasing dietary SID Arg:Lys increased final BW but had no clear impacts on intestinal health within the parameters measured, potentially impacted by the rotavirus diagnosis in the first week post-wean.

Dual mass spectrometry imaging and spatial metabolomics to investigate the metabolism and nephrotoxicity of nitidine chloride

Evaluating toxicity and decoding the underlying mechanisms of active compounds are crucial for drug development. In this study, we present an innovative, integrated approach that combines air flow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and spatial metabolomics to comprehensively investigate the nephrotoxicity and underlying mechanisms of nitidine chloride (NC), a promising anti-tumor drug candidate. Our quantitive AFADESI-MSI analysis unveiled the region specific of accumulation of NC in the kidney, particularly within the inner cortex (IC) region, following single and repeated dose of NC. High spatial resolution ToF-SIMS analysis further allowed us to precisely map the localization of NC within the renal tubule. Employing spatial metabolomics based on AFADESI-MSI, we identified over 70 discriminating endogenous metabolites associated with chronic NC exposure. These findings suggest the renal tubule as the primary target of NC toxicity and implicate renal transporters (organic cation transporters, multidrug and toxin extrusion, and organic cation transporter 2 (OCT2)), metabolic enzymes (protein arginine N-methyltransferase (PRMT) and nitric oxide synthase), mitochondria, oxidative stress, and inflammation in NC-induced nephrotoxicity. This study offers novel insights into NC-induced renal damage, representing a crucial step towards devising strategies to mitigate renal damage caused by this compound.

Arginine-NO metabolites are associated with morbidity in single ventricle infants undergoing stage 2 palliation

BACKGROUND

Infants with single ventricle heart disease (SVHD) suffer morbidity from insufficient pulmonary blood flow, which may be related to impaired arginine metabolism. No prior study has reported quantitative mapping of arginine metabolites to evaluate the relationship between circulating metabolite levels and outcomes.

METHODS

Prospective cohort study of 75 SVHD cases peri-Stage 2 and 50 healthy controls. We targeted pre- and post-op absolute serum quantification of 9 key members of the arginine metabolism pathway by tandem mass spectrometry. Primary outcomes were length of stay (LOS) and post-Stage 2 hypoxemia.

RESULTS

Pre-op cases showed alteration in 6 metabolites including decreased arginine and increased asymmetric dimethyl arginine (ADMA) levels compared to controls. Post-op cases demonstrated decreased arginine and citrulline levels persisting through 48 h. Adjusting for clinical variables, lower pre-op and 2 h post-op concentrations of multiple metabolites, including arginine and citrulline, were associated with longer post-op LOS (p < 0.01). Increased ADMA at 24 h was associated with greater post-op hypoxemia burden (p < 0.05).

CONCLUSION

Arginine metabolism is impaired in interstage SVHD infants and is further deranged following Stage 2 palliation. Patients with greater metabolite alterations experience greater post-op morbidity. Decreased arginine metabolism may be an important driver of pathology in SVHD.

IMPACT

Interstage infants with SVHD have significantly altered arginine-nitric oxide metabolism compared to healthy children with deficiency of multiple pathway intermediates persisting through 48 h post-Stage 2 palliation. After controlling for clinical covariates and classic catheterization-derived predictors of Stage 2 readiness, both lower pre-operation and lower post-operation circulating metabolite levels were associated with longer post-Stage 2 LOS while increased post-Stage 2 ADMA concentration was associated with greater post-op hypoxemia. Arginine metabolism mapping offers potential for development using personalized medicine strategies as a biomarker of Stage 2 readiness and therapeutic target to improve pulmonary vascular health in infants with SVHD.