Arginine Biosynthesis Pathway Research Articles

Identification of metabolic biomarkers in idiopathic pulmonary arterial hypertension using targeted metabolomics and bioinformatics analysis

Pulmonary arterial hypertension (PAH) is a life-threatening disease with a poor prognosis, and metabolic abnormalities play a critical role in its development. This study used metabolomics, machine learning algorithms and bioinformatics to screen for potential metabolic biomarkers associated with the diagnosis of PAH. In this study, plasma samples were collected from 17 patients diagnosed with idiopathic pulmonary arterial hypertension (IPAH) and 20 healthy controls. Plasma metabolomic profiling was performed by high-performance liquid chromatography-mass spectrometry. Gene profiles of PAH patients were obtained from the GEO database. Key differentially expressed metabolites (DEMs) and metabolism-related genes were subsequently identified using machine learning algorithms. Twenty differential plasma metabolites associated with IPAH were identified (VIP score > 1 and p < 0 0.05), and enrichment analysis revealed the arginine biosynthesis pathway as the most altered pathway. Using machine learning models, including least absolute shrinkage and selection operator (LASSO), random forest (RF) and support vector machine (SVM), we extracted key metabolites that correlated with clinical phenotypes. Our results suggested that five metabolites, kynurenine, homoserine, tryptophan, AMP, and spermine, are potential biomarkers for IPAH. Bioinformatics analysis also identified 3 metabolism-related genes, MAPK6, SLC7A11 and CDC42BPA, that are strongly correlated with pulmonary hypertension, demonstrating strong predictive power and clinical relevance. Our findings revealed some key genes associated with metabolism in PH, and provided crucial information about complex metabolic reprogramming signals and may lead to the identification of useful metabolic biomarkers for the diagnosis of PAH.

Sputum Metabolomic Signature and Dynamic Change of Cough Variant Asthma.

Cough variant asthma (CVA), a common reason for chronic cough, is a globally prevalent and burdensome condition. The heterogeneity of CVA and a lack of knowledge concerning the exact molecular pathogenesis has hampered its clinical management. This study presented the first sputum metabolome of CVA patients, revealed the dynamic change during treatment, and explored biomarkers related to the occurrence and treatment response of CVA. We found arginine biosynthesis, purine metabolism, and pyrimidine metabolism pathways were enriched in CVA compared to healthy controls. Part of metabolic disturbances could be reversed by anti-asthmatic medication. The levels of dipeptides/tripeptides (alanyltyrosine, Gly-Tyr-Ala, Ala-Leu, and Thr-Leu) were significantly associated with sputum Neu% or Eos% of CVA patients. Differential metabolites pre-treatment between effective and ineffective groups enriched in purine metabolism, thiamine metabolism, and arginine metabolism. 2-isopropylmalate was down-regulated in CVA patients and increased after treatment, and effective group had a lower 2-isopropylmalate level pre-treatment. Random forest and logistic regression models identified glutathione, thiamine phosphate, alanyltyrosine, and 2'-deoxyadenosine as markers for distinguishing CVA from healthy controls (all AUC > 0.8). Thiamine phosphate might also be promising for predicting therapy responsiveness (AUC = 0.684). These findings implied that disturbed mitochondrial energy metabolism and imbalanced oxidation-reduction homeostasis probably underlay the metabolic pathogenesis of CVA.

Amino acid metabolites profiling in unpredictable chronic mild stress-induced depressive rats and the protective effects of Gastrodia elata Blume and gastrodin

Ethnopharmacological relevanceMajor depressive disorder (MDD) is a prevalent condition that affects approximately 350 million people worldwide. Several studies have identified changes in amino acids in the blood of MDD patients, suggesting their potential as biomarkers to better understand their role in depression. Gastrodia elata Blume (GEB) and its active compound gastrodin (GAS) are recognized for their antidepressant properties. However, their effects on amino acid profiles and their potential role in alleviating depression remain poorly understood. Understanding how GEB and GAS influence amino acid metabolism may offer novel insights into their mechanisms in alleviating depression, potentially leading to more targeted therapeutic strategies. Aim of the studyThis study aimed to investigate the potential role of supplementing GEB and its active compound GAS to reverse altered amino acid profiles in depressed rats. Materials and methodsTo achieve this, six-week-old SD rats were induced depressive-like behaviors by the UCMS rat model for 5 weeks. Groups receiving GEB or GAS were administered orally via gavage daily within the UCMS model. Serum samples were collected and analyzed using a targeted metabolomics approach employing LC-MS for amino acid profiling. ResultsA total of 38 amino acid metabolites were identified, 17 of which were significantly altered following UCMS. UCMS rats exhibited perturbed arginine biosynthesis, arginine and proline metabolism pathways. Changes in key amino acids in these metabolic pathways were reversed following supplementation with GEB and GAS, which also alleviated depressive symptoms. ConclusionsIn conclusion, UCMS-induced depression in rats causes changes in some amino acid metabolites similar to those found in human depression, validating its relevance as a model for studying depression. Additionally, the research suggests that GEB and GAS may exert antidepressant effects by regulating amino acid metabolism.

Comparative Metabolomics Reveals Changes in the Metabolic Pathways of Ampicillin- and Gentamicin-Resistant Staphylococcus aureus.

Antibiotic resistance is a major global challenge requiring new treatments and a better understanding of the bacterial resistance mechanisms. In this study, we compared ampicillin-resistant (R-AMP) and gentamicin-resistant (R-GEN) Staphylococcus aureus strains with a sensitive strain (ATCC6538) using metabolomics. We identified 109 metabolites; 28 or 31 metabolites in R-AMP or R-GEN differed from those in ATCC6538. Moreover, R-AMP and R-GEN were enriched in five and four pathways, respectively. R-AMP showed significantly up-regulated amino acid metabolism and down-regulated energy metabolism, whereas R-GEN exhibited an overall decrease in metabolism, including carbohydrate, energy, and amino acid metabolism. Furthermore, the activities of the metabolism-related enzymes pyruvate dehydrogenase and TCA cycle dehydrogenases were inhibited in antibiotic-resistant bacteria. Significant decreases in NADH and ATP levels were also observed. In addition, the arginine biosynthesis pathway, which is related to nitric oxide (NO) production, was enriched in both antibiotic-resistant strains. Enhanced NO synthase activity in S. aureus promoted NO production, which further reduced reactive oxygen species, mediating the development of bacterial resistance to ampicillin and gentamicin. This study reveals that bacterial resistance affects metabolic profile, and changes in energy metabolism and arginine biosynthesis are important factors leading to drug resistance in S. aureus.

Kidney tea [Orthosiphon aristatus (Blume) Miq.] improves diabetic nephropathy via regulating gut microbiota and ferroptosis.

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Due to its complex pathogenesis, new therapeutic agents are urgently needed. Orthosiphon aristatus (Blume) Miq., commonly known as kidney tea, is widely used in DN treatment in China. However, the mechanisms have not been fully elucidated. We used db/db mice as the DN model and evaluated the efficacy of kidney tea in DN treatment by measuring fasting blood glucose (FBG), serum inflammatory cytokines, renal injury indicators and histopathological changes. Furthermore, 16S rDNA gene sequencing, untargeted serum metabolomics, electron microscope, ELISA, qRT-PCR, and Western blotting were performed to explore the mechanisms by which kidney tea exerted therapeutic effects. Twelve polyphenols were identified from kidney tea, and its extract ameliorated FBG, inflammation and renal injury in DN mice. Moreover, kidney tea reshaped the gut microbiota, reduced the abundance of Muribaculaceae, Lachnoclostridium, Prevotellaceae_UCG-001, Corynebacterium and Akkermansia, and enriched the abundance of Alloprevotella, Blautia and Lachnospiraceae_NK4A136_group. Kidney tea altered the levels of serum metabolites in pathways such as ferroptosis, arginine biosynthesis and mTOR signaling pathway. Importantly, kidney tea improved mitochondrial damage, increased SOD activity, and decreased the levels of MDA and 4-HNE in the renal tissues of DN mice. Meanwhile, this functional tea upregulated GPX4 and FTH1 expression and downregulated ACSL4 and NCOA4 expression, indicating that it could inhibit ferroptosis in the kidneys. Our findings imply that kidney tea can attenuate DN development by modulating gut microbiota and ferroptosis, which presents a novel scientific rationale for the clinical application of kidney tea.

Metabolomic study on ostracods exposed to environmentally relevant concentrations of five pharmaceuticals selected via a novel approach

Pharmaceuticals (PhACs) are increasingly detected in aquatic ecosystems, yet their effects on biota remain largely unknown. The environmentally relevant concentrations of many PhACs may not result in individual-level responses, like mortality or growth inhibition, traditional toxicity endpoints. However, this doesn't imply the absence of negative effects on biota. Metabolomics offers a more sensitive approach, detecting responses at molecular and cellular levels and providing mechanistic understanding of adverse effects. We evaluated bioaccumulation and metabolic alterations in a benthic ostracod, Heterocypris incongruens, exposed to a mixture of five PhACs (carbamazepine, tiapride, tolperisone, propranolol and amlodipine) at environmentally relevant concentrations for 7 days using liquid chromatography coupled with mass spectrometry. The selection of PhACs was based, among other factors, on risk quotient values determined using toxicological data available in the literature and concentrations of PhACs quantified in our previous research in the sediments of the Odra River estuary. This represents a novel approach to PhACs selection for metabolomic studies that considers strictly quantitative data. Amlodipine and tolperisone exhibited the highest bioaccumulation. Significant impacts were observed in Alanine, aspartate and glutamate metabolism, Starch and sucrose metabolism, Arginine biosynthesis, Histidine metabolism, Tryptophan metabolism, Glycerophospholipid metabolism, and Glutathione metabolism pathways. Most of the below-individual-level responses were likely nonspecific and related to dysregulation in energy metabolism and oxidative stress response. Additionally, some pharmaceutical-specific responses were also observed. Therefore, untargeted metabolomics can be used to detect metabolic changes resulting from environmentally relevant concentrations of PhACs in aquatic ecosystems and to understand their underlying mechanism.

Plasma metabolomics and lipidomics reveal potential novel biomarkers in early gastric cancer: An explorative study.

Early identification and therapy can significantly improve the outcome for gastric cancer. However, there is still no perfect biomarker available for the detection of early gastric cancer. This study aimed to investigate the alterations in the plasma metabolites of early gastric cancer using metabolomics and lipidomics based on high-performance liquid chromatography-mass spectrometry (HPLC-MS), which detected potential biomarkers that could be used for clinical diagnosis. To investigate the changes in metabolomics and lipidomics, a total of 30 plasma samples were collected, consisting of 15 patients with early gastric cancer and 15 healthy controls. Extensive HPLC-MS-based untargeted metabolomic and lipidomic investigations were conducted. Differential metabolites and metabolic pathways were uncovered through the utilization of statistical analysis and bioinformatics analysis. Candidate biomarker screening was performed using support vector machine-based multivariate receiver operating characteristic analysis. A disturbance was observed in a combined total of 19 metabolites and 67 lipids of the early gastric cancer patients. The analysis of KEGG pathways showed that the early gastric cancer patients experienced disruptions in the arginine biosynthesis pathway, the pathway for alanine, aspartate, and glutamate metabolism, as well as the pathway for glyoxylate and dicarboxylate metabolism. Plasma metabolomics and lipidomics have identified multiple biomarker panels that can effectively differentiate early gastric cancer patients from healthy controls, exhibiting an area under the curve exceeding 0.9. These metabolites and lipids could potentially serve as biomarkers for the screening of early gastric cancer, thereby optimizing the strategy for the detection of early gastric cancer. The disrupted pathways implicated in early gastric cancer provide new clues for additional understanding of gastric cancer's pathogenesis. Nonetheless, large-scale clinical data are required to prove our findings.

Coaggregated E. faecalis with F. nucleatum regulated environmental stress responses and inflammatory effects

To investigate the cell-cell interactions of intergeneric bacterial species, the study detected the survival of Enterococcus faecalis (Ef) under monospecies or coaggregation state with Fusobacterium nucleatum subsp. polymorphum (Fnp) in environmental stress. Ef and Fnp infected the human macrophages with different forms (Ef and Fnp monospecies, Ef-Fnp coaggregates, Ef + Fnp cocultures) for exploring the immunoregulatory effects and the relevant molecular mechanisms. Meanwhile, the transcriptomic profiles of coaggregated Ef and Fnp were analyzed. Ef was shown to coaggregate with Fnp strongly in CAB within 90 min by forming multiplexes clumps. Coaggregation with Fnp reinforced Ef resistance against unfavorable conditions including alkaline, hypertonic, nutrient-starvation, and antibiotic challenges. Compared with monospecies and coculture species, the coaggregation of Ef and Fnp significantly facilitates both species to invade dTHP-1 cells and aid Ef to survive within the cells. Compared with coculture species, dual-species interaction of Ef and Fnp significantly decreased the levels of pro-inflammatory cytokines IL-6, TNF-α, and chemokines MCP-1 secreted by dTHP-1 cells and lessened the phosphorylation of p38, JNK, and p65 signaling pathways. The transcriptome sequencing results showed that 111 genes were differentially expressed or Ef-Fnp coaggregated species compared to Ef monospecies; 651 genes were differentially expressed for Fnp when coaggregation with Ef. The analysis of KEGG pathway showed that Ef differentially expressed genes (DEGs) were enriched in quorum sensing and arginine biosynthesis pathway; Fnp DEGs were differentially concentrated in lipopolysaccharide (LPS) biosynthesis, biofilm formation, and lysine degradation pathway compared to monospecies.Key points• Coaggregated with Fnp aids Ef’s survival in environmental stress, especially in root canals after endodontic treatment.• The coaggregation of Ef and Fnp may weaken the pro-inflammatory response and facilitate Ef to evade killed by macrophages.• The coaggregation between Ef and Fnp altered interspecies transcriptional profiles.

Antimycobacterial and healing effects of Pranlukast against MTB infection and pathogenesis in a preclinical mouse model of tuberculosis.

It is essential to understand the interactions and relationships between Mycobacterium tuberculosis (Mtb) and macrophages during the infection in order to design host-directed, immunomodulation-dependent therapeutics to control Mtb. We had reported previously that ornithine acetyltransferase (MtArgJ), a crucial enzyme of the arginine biosynthesis pathway of Mtb, is allosterically inhibited by pranlukast (PRK), which significantly reduces bacterial growth. The present investigation is centered on the immunomodulation in the host by PRK particularly the activation of the host's immune response to counteract bacterial survival and pathogenicity. Here, we show that PRK decreased the bacterial burden in the lungs by upregulating the population of pro-inflammatory interstitial macrophages (IMs) and reducing the population of Mtb susceptible alveolar macrophages (AMs), dendritic cells (DCs), and monocytes (MO). Additionally, we deduce that PRK causes the host macrophages to change their metabolic pathway from fatty acid metabolism to glycolytic metabolism around the log phage of bacterial multiplication. Further, we report that PRK reduced tissue injury by downregulating the Ly6C-positive population of monocytes. Interestingly, PRK treatment improved tissue repair and inflammation resolution by increasing the populations of arginase 1 (Arg-1) and Ym1+Ym2 (chitinase 3-like 3) positive macrophages. In summary, our study found that PRK is useful not only for reducing the tubercular burden but also for promoting the healing of the diseased tissue.

ARGININE METABOLISM AND ARTERIAL STIFFNESS IN HIGHLANDERS WITH HIGH ALTITUDE POLYCYTHEMIA

Objective: High altitude polycythemia (HAPC) is a health condition associated with hypoxemia and erythrocytosis. Patients with chronic hypoxemia often exhibit arterial stiffness. In the advanced stages of HAPC, patients can present changes in the pulmonary circulation, but limited information exists regarding arterial stiffness. Our study aims to investigate the relationship between HAPC and arterial stiffness, and explore the underlying mechanisms. Design and method: At an altitude of 3500m, we conducted a study examining arterial stiffness and vascular endothelial function in two groups of hypertensive highlanders with and without HAPC, each consisting of 30 participants. Plasma samples were measured using Ultra Performance Liquid Chromatography Tandem Mass Spectroscopy. Results: Hypertensive highlanders with HAPC exhibited notable vascular dysfunction, as indicated by significantly impaired flow-mediated dilation (FMD) (3.97±1.21% vs. 6.82±1.46%, P &lt; 0.001), and higher brachial-ankle pulse wave velocity (BaPWV) (1556±239 cm/s vs. 1890±459 cm/s, P &lt; 0.001). Metabolomics analysis revealed alterations in arginine/proline metabolism and the arginine biosynthesis pathway, involving L-arginine, L-ornithine, creatine and 4-guanidinobutanoic acid. The area under the curve (AUC) values for 4 metabolites and L-arginine/L-ornithine ratio were 0.753, 0.782, 0.720, 0.717 and 0.819, respectively. Pearson correlation analysis showed that L-arginine, L-ornithine, and L-arginine/L-ornithine ratio were associated with BaPWV (r=-0.4486, P=0.00032; r=0.3400, P=0.0078; r=0.3921, P=0.0019). L-arginine, L-ornithine, 4-guanidinobutanoic acid, creatine, and L-arginine/L-ornithine ratio were correlated with FMD. Multiple linear regression analysis revealed that L-arginine and L-arginine/L-ornithine ratio were independently correlated with BaPWV (beta= -0.370, t=-3.114, P=0.003; beta=-0.268, t=-2.211, P=0.032) and FMD (beta=0.434, t=3.114, P=0.003; beta= 0.457, t=3.445, P=0.001), but L-ornithine was not independently related to BaPWV and FMD. Conclusions: Our study indicates that HAPC may accelerate the progression of arterial stiffness in hypertensive patients. In fact, L-arginine takes an important role in the forming of NO in vascular endothelium. So The disorder of arginine metabolism may serve as the underlying metabolic mechanism.

Microbiome profiling and Co-metabolism pathway analysis in cervical cancer patients with acute radiation enteritis

BackgroundIntestinal bacteria significantly contribute to the metabolism of intestinal epithelial tissues. As the occurrence and development of radiation enteritis (RE) depend on the “co-metabolism” microenvironment formed by the host and intestinal microbiota, which involves complex influencing factors and strong correlations, ordinary techniques struggle to fully explain the underlying mechanisms. However, given that it is based on systems biology, metabolomics analysis is well-suited to address these issues. This study aimed to analyze the metabolomic changes in urine, serum, and fecal samples during volumetric modulated arc therapy (VMAT) for cervical cancer and screen for characteristic metabolites of severe acute radiation enteritis (SARE) and RE. MethodsWe enrolled 50 patients who received radiotherapy for cervical cancer. Urine, serum, and fecal samples of patients were collected at one day before radiotherapy and the second week, fourth week, and sixth week after the start of radiotherapy. Control group samples were collected during the baseline period. Differential metabolites were identified by metabolomics analysis; co-metabolic pathways were clarified. We used the mini-SOM library for incorporating characteristic metabolites, and established metabolite classification models for predicting SARE and RE. ResultsUrine and serum sample data showed remarkable clustering effect; metabolomics data of the fecal supernatant were evidently disturbed. Patient sample analyses during VMAT revealed the following. Urine samples: Downregulation of the pyrimidine and riboflavin metabolism pathways as well as initial upregulation followed by downregulation of arginine and proline metabolism pathways and the arginine biosynthesis pathway. Fecal samples: Upregulation of linoleic acid and phenylalanine metabolic pathways and initial downregulation followed by upregulation of arachidonic acid (AA) metabolic pathways. Serum samples: Initial upregulation followed by downregulation of the arginine biosynthesis pathway and downregulation of glutathione, AA, and arginine and proline metabolic pathways. ConclusionPatients with cervical cancer exhibited characteristic metabolic pathways and characteristic metabolites predicting RE and SARE were screened out. An effective RE mini-SOM classification model was successfully established.

Аминокислотный профиль при сниженном овариальном резерве

Diminished ovarian reserve (DOR) represents a relevant issue of reproductive medicine that is often associated with infertility and reduced efficacy of IVF programs. The changes in amino acid metabolism can play a role in the DOR pathogenesis as manifestations of the folliculogenesis and oogenesis epigenetic alterations. The study was aimed to assess alterations of amino acid metabolic pathways in blood plasma and follicular fluid and estimate their clinical significance in DOR. A total of 115 infertile women aged 25–42 years were included in the study. Groups were formed based on the ovarian reserve and age. Amino acid levels in blood plasma and follicular fluid were assessed by high performance liquid chromatography–mass spectrometry (HPLC-MS); bioinformatics analysis of amino acid metabolic pathways was performed. We revealed significant changes in the phenylalanine, tyrosine and tryptophan biosynthesis (effect = 0.5; p = 0.026), alanine, aspartate and glutamate metabolism (effect = 0.114; p = 0.013), and arginine biosynthesis (effect = 0.289; p &lt; 0.001) pathways playing a role in folliculogenesis, oogenesis, and embryogenesis. The detected differences in the amino acid levels in various body fluids made it possible to construct the logistic regression models confirming DOR with the 88% probability based on the amino acid levels in follicular fluid (sensitivity 88%, specificity 84%) and 82% probability based on plasma levels (sensitivity 65%, specificity 91%). The findings can be used for further research focused on the pathogenesis of infertility associated with DOR and for selection of the most optimal diagnostic and treatment tactics.

Transcriptome-metabolome and anatomy conjoint analysis of vital component change of photosynthesis of Foxtail millet under different drought conditions

Drought caused by extreme climate change has become more severe and unpredictable, causing imperceptible effects on leaf photosynthesis in foxtail millet. To investigate the damage, we performed light drought (LD) and heavy drought (HD) treatments at both the elongation (Y) and booting stages to obtain a comprehensive understanding of the morphological, anatomical, physiological, transcriptome, and metabolome levels. Under drought stress, the length and area of leaves decreased, especially during the HD treatment at the booting stage. The number of mesophyll cells and the area of large vascular bundles were both decreased under LD and HD treatments at the booting stage, as well as with more blurring vascular bundle structure and Kranz anatomy. However, these numbers decreased but with no significance under Y-LD and Y-HD treatments at the elongation stage. The net photosynthetic rate, stomatal conductivity, transpiration rate, and intercellular CO2 concentration significantly decreased at the booting stage. In addition, the efficiency of electron transfers in photosystem II (PS II) decreased. Conjunction analyses of the transcriptome and metabolome were utilized to uncover the underlying mechanism at the booting stage. The results showed that there was no common differentially enriched pathway in the transcriptome and metabolome under LD treatment but thirty-two pathways were enriched in both the transcript and metabolome under HD treatment. Among these, three pathways arginine, proline metabolism, tyrosine metabolism, ubiquinone, and other terpenoid-quinone biosynthesis pathways were differentially enriched in both the transcript and metabolome. The accumulation of Homogentisate, Salidroside, Homoprotocatechuate, L-DOPA, Tyramine, and L-Tyrosine increased under drought stress. Although genes related to PSII and the Calvin cycle were slightly up-regulated under LD conditions, they were down-regulated under HD condition. The metabolites of Ribose-5P, Glycerate-3P, D-Fructosel 1,6P2, and D-Fructose-6P were all decreased in both the LD and HD treatments, especially D-Fructose-6P, confirming that drought stress had a negative effect on the Calvin cycle. The results revealed that regardless of the severity of drought, photosynthetic function was compromised not only at the morphological and anatomical levels but also in terms of impaired ATP synthase and inhibited photosynthetic CO2 assimilation.

Zinc Imidazole Framework‐8 Nanoparticles Disperse MRSA Biofilm by Inhibiting Arginine Biosynthesis and Down‐Regulating Adhesion‐Related Proteins

AbstractNanomaterials, including ZIF‐8 nanoparticles (NPs), are shown to be effective antimicrobial agents against Methicillin‐resistant Staphylococcus aureus(MRSA). However, the antibiofilm properties and mechanisms of ZIF‐8 NPs remain uncertain. In this study, ZIF‐8 NPs are prepared using the room temperature solution reaction method and characterized. Biofilm formation inhibition test and biofilm eradication test are performed and the results show that ZIF‐8 NPs can inhibit the formation of MRSA biofilm as well as disperse established MRSA biofilm. Proteomics and real‐time fluorescence quantitative polymerase chain reaction (PCR) are conducted to prove that ZIF‐8 NPs reduce the expression of adhesion‐related proteins, namely the fibronectin‐binding proteins A and B (fnbA/fnbB), fibrinogen binding protein caking factors A and B (clfA/clfB), elastin binding protein (ebps), and fibrin binding protein (eno). ZIF‐8 NPs also inhibit the arginine biosynthesis pathway by affecting the activities of argininosuccinate lyase, ornithine carbamyl transferase, Glutamate dehydrogenase, carbamate kinase, and arginine deiminase. A conclusion can be drawn from the above results that ZIF‐8 NPs can inhibit bacterial adhesion and kill bacteria directly, ultimately destroying MRSA biofilm. This study provides a molecular basis for the treatment of MRSA biofilm with ZIF‐8 NPs.

Arginine inhibits the arginine biosynthesis rate-limiting enzyme and leads to the accumulation of intracellular aspartate in Synechocystis sp. PCC 6803

Cyanobacteria are oxygen-evolving photosynthetic prokaryotes that affect the global carbon and nitrogen turnover. Synechocystis sp. PCC 6803 (Synechocystis 6803) is a model cyanobacterium that has been widely studied and can utilize and uptake various nitrogen sources and amino acids from the outer environment and media. l-arginine is a nitrogen-rich amino acid used as a nitrogen reservoir in Synechocystis 6803, and its biosynthesis is strictly regulated by feedback inhibition. Argininosuccinate synthetase (ArgG; EC 6.3.4.5) is the rate-limiting enzyme in arginine biosynthesis and catalyzes the condensation of citrulline and aspartate using ATP to produce argininosuccinate, which is converted to l-arginine and fumarate through argininosuccinate lyase (ArgH). We performed a biochemical analysis of Synechocystis 6803 ArgG (SyArgG) and obtained a Synechocystis 6803 mutant overexpressing SyArgG and ArgH of Synechocystis 6803 (SyArgH). The specific activity of SyArgG was lower than that of other arginine biosynthesis enzymes and SyArgG was inhibited by arginine, especially among amino acids and organic acids. Both arginine biosynthesis enzyme-overexpressing strains grew faster than the wild-type Synechocystis 6803. Based on previous reports and our results, we suggest that SyArgG is the rate-limiting enzyme in the arginine biosynthesis pathway in cyanobacteria and that arginine biosynthesis enzymes are similarly regulated by arginine in this cyanobacterium. Our results contribute to elucidating the regulation of arginine biosynthesis during nitrogen metabolism.

High-fat and high-sucrose diet impairs female reproduction by altering ovarian transcriptomic and metabolic signatures

BackgroundExcessive energy intake in modern society has led to an epidemic surge in metabolic diseases, such as obesity and type 2 diabetes, posing profound threats to women’s reproductive health. However, the precise impact and underlying pathogenesis of energy excess on female reproduction remain unclear.MethodsWe established an obese and hyperglycemic female mouse model induced by a high-fat and high-sucrose (HFHS) diet, then reproductive phenotypes of these mice were evaluated by examing sexual hormones, estrous cycles, and ovarian morphologies. Transcriptomic and precise metabolomic analyses of the ovaries were performed to compare the molecular and metabolic changes in HFHS mice. Finally, orthogonal partial least squares discriminant analysis was performed to compare the similarities of traits between HFHS mice and women with polycystic ovary syndrome (PCOS).ResultsThe HFHS mice displayed marked reproductive dysfunctions, including elevated serum testosterone and luteinizing hormone levels, irregular estrous cycles, and impaired folliculogenesis, mimicking the clinical manifestations of women with PCOS. Precise metabolomic overview suggested that HFHS diet disrupted amino acid metabolism in the ovaries of female mice. Additionally, transcriptional profiling revealed pronounced disturbances in ovarian steroid hormone biosynthesis and glucolipid metabolism in HFHS mice. Further multi-omics analyses unveiled prominent aberration in ovarian arginine biosynthesis pathway. Notably, comparisons between HFHS mice and a cohort of PCOS patients identified analogous reproductive and metabolic signatures.ConclusionsOur results provide direct in vivo evidence for the detrimental effects of overnutrition on female reproduction and offer insights into the metabolic underpinnings of PCOS.

Dietary selenium levels affect mineral absorbability, rumen fermentation, microbial composition and metabolites of the grazing sheep

Selenium (Se) is an essential trace element for the growth of all livestock. However, little is known about the effects of dietary selenium levels on production metrics, nutrient digestion and absorption, ruminal microbiota, and metabolites in grazing sheep. Therefore, in this research, 28 individually-housed grazing sheep were randomly divided into a low-Se feeding group (LSe) and a control group for the low-Se feeding phase (LCG), supplemented with multi-nutrient salts containing 0 mg Se and 0.63 mg Se, respectively, for 53 days. After 53 days of feeding, a 7-day digestion test was conducted, then seven sheep in each group were randomly slaughtered. Then, the remaining sheep in LSe and LCG were transferred to a high-Se supplementation group (SSe) and a control group for the high-Se feeding phase (SCG), supplemented with multi-nutrient salts containing 1.90 mg and 0.63 mg Se, respectively. This phase consisted of a 34-day diet adaptation period, a 7-day digestive test, and eventual slaughter. LSe reduced and elevated ruminal Se and copper (Cu) content, respectively, and decreased Se apparent absorbability compared to LCG (P < 0.05). Conversely, SSe reduced and increased ruminal Cu and Se content, respectively, and increased Se apparent absorption in comparison to SCG (P < 0.05). It also increased the ruminal NH3-N concentration (P < 0.05). Amplicon sequencing analysis revealed a decrease in Lentimicrobium and Treponema abundance and an increase in Lawsonibacter and Sporobacter abundance (P < 0.05) in LSe group. Metabolomic analysis confirmed an elevated level of ruminal citrulline, ornithine and glutathione affecting amino acid and glutathione metabolic pathways (P < 0.05) in LSe group. In SSe group, Alistipes were significantly reduced (P < 0.05) with metabolomics showing elevated levels of L-carnitine and arginine, affecting ruminal antioxidant capacity and arginine biosynthesis pathways (P < 0.05). Notably, both treatments had no significant effect on production metrics and apparent digestibility of organic nutrients (P > 0.05). In conclusion, Se deficiency affects Se absorption and amino acid metabolism in grazing sheep, while supplementing Se in diet effectively ameliorates these deficiencies and improves ruminal antioxidant capacity.

Exopolysaccharide secreted by Lactiplantibacillus plantarum Y12 showed inhibitory effect on the pathogenicity of Shigella flexneri in vitro and in vivo

Shigella flexneri is a prevalent foodborne and waterborne pathogen that threatens human health. Our previous research indicated that the Lactiplantibacillus plantarum Y12 exopolysaccharide (L-EPS) potentially inhibited the pathogenicity of S. flexneri. The in vitro results of this study demonstrated that L-EPS effectively mitigated the symptoms induced by S. flexneri in HT-29 cells, including inhibited gene expression levels of IL-1β, IL-6, IL-8, TNF-α, TLR 2/4, and NOD1/2; decreased apoptosis ratio; and alleviated damage degree of intestinal barrier function (Zona occludens 1, Occludin, and Claudin-1). The in vivo results demonstrated that S. flexneri treated with L-EPS elicited mild adverse physiological manifestations, an inflammatory response, and tissue damage. The infection of S. flexneri caused significant alterations in the abundance of phylum (Firmicutes, Bacteroidota, Actinobacteriota, and Proteobacteria), family (Lachnospiraceae, Muribaculaceae, Rikenellaceae, Prevotellaceaea, Ruminococcaceae, and Lactobaillaceae), and genus (Escherichia Shigella and Lachnospirillaceae NK4A136 group) within the cecal microbiota. These changes were accompanied by perturbations in taurine and hypotaurine metabolism, tricarboxylic acid (TCA) cycle activity, arginine biosynthesis, and histidine metabolic pathways. However, intervention with L-EPS attenuated the dysbiosis of cecal microbiota and metabolic disturbances. In summary, our research suggested a potential application of L-EPS as a functional food additive for mitigating S. flexneri infection.

Abnormal arginine synthesis confers worse prognosis in patients with middle third gastric cancer

BackgroundGastric cancer at different locations has distinct prognoses and biological behaviors, but the specific mechanism is unclear.MethodsNon-targeted metabolomics was performed to examine the differential metabolite phenotypes that may be associated with the effects of tumor location on the prognosis of gastric cancer. And silencing of the rate-limiting enzyme to evaluate the effect of abnormal changes in metabolic pathway on the functional biological assays of gastric cancer cells HGC-27 and MKN28.ResultsIn a retrospective study of 94 gastric cancer patients, the average survival time of patients with gastric cancer in the middle third of the stomach was significantly lower than that of patients with gastric cancer in other locations (p < 0.05). The middle third location was also found to be an independent risk factor for poor prognosis (HR = 2.723, 95%CI 1.334–5.520), which was closely associated with larger tumors in this location. Non-targeted metabolomic analysis showed that the differential metabolites affected 16 signaling pathways including arginine synthesis, retrograde endocannabinoid signaling, arginine biosynthesis, and alanine and aspartate and glutamate metabolism between gastric cancer and normal tissue, as well as between tumors located in the middle third of the stomach and other locations. Argininosuccinate synthetase 1 (ASS1), the rate-limiting enzyme of the arginine biosynthesis pathway, catalyzes the production of argininosuccinic acid. Here, knockdown of ASS1 significantly inhibited the proliferation, colony formation, and migration/invasion of gastric cancer cells, and promoted apoptosis.ConclusionsOur study suggests that abnormal arginine synthesis may lead to larger tumor size and worse prognosis in gastric cancer located in the middle third position of the stomach. These findings may provide the basis for the stratification and targeted treatment of gastric cancer in different locations.

Effects of chitosan and its oligosaccharide on gut microbiota and metabolites disturbed by excessive protein consumption in vivo and in vitro

Chitosan (CTS) and its oligosaccharide (COS) can protect against excessive protein consumption (EPC)-induced constipation by regulating gut microbiota and metabolites. The imbalanced gut microbiota was observed in whey protein isolate (WPI) group by 16S rRNA gene sequencing. However, CTS and COS treatments reversed the abundance changes of several gut microbiota, which led to the balance in the production of metabolites. Interestingly, some metabolites associated with constipation were also regulated by CTS and COS in in vitro colonic fermentation model and EPC-induced constipated rats, including nicotinamide, glutamine, proline, cysteine, choline, tryptophan, and pipecolic acid, which were mainly associated with aminoacyl-tRNA biosynthesis, arginine biosynthesis, and d-glutamine and d-glutamate metabolism pathways. In conclusion, the present study shed light on the effects of CTS and COS on EPC by regulating gut microbiota and metabolites and explored the correlation between gut microbiota and metabolites, reinforcing its potential application as a prebiotic in maintaining intestinal health.