Xanthurenic Acid Research Articles

Targeted metabolomic profiling of acute ST-segment elevation myocardial infarction

Myocardial infarction is a major cause of morbidity and mortality worldwide. Metabolomic investigations may be useful for understanding the pathogenesis of ST-segment elevation myocardial infarction (STEMI). STEMI patients were comprehensively examined via targeted metabolomic profiling, machine learning and weighted correlation network analysis. A total of 195 subjects, including 68 STEMI patients, 84 patients with stable angina pectoris (SAP) and 43 non-CVD patients, were enrolled in the study. Metabolomic profiling involving the quantitative analysis of 87 endogenous metabolites in plasma was conducted. This study is the first to perform targeted metabolomic profiling in patients with STEMI. We identified 36 significantly altered metabolites in STEMI patients. Increased levels of four amino acids, eight acylcarnitines, six metabolites of the NO–urea cycle and neurotransmitters, and three intermediates of tryptophan metabolism were detected. The following metabolites exhibited decreased levels: six amino acids, three acylcarnitines, three components of the NO–urea cycle and neurotransmitters, and three intermediates of tryptophan metabolism. We found that the significant changes in tryptophan metabolism observed in STEMI patients—the increase in anthranilic acid and tryptophol and decrease in xanthurenic acid and 3-OH-kynurenine—may play important roles in STEMI pathogenesis. On the basis of the differences in the constructed weighted correlation networks, new significant metabolite ratios were identified. Among the 22 significantly altered metabolite ratios identified, 13 were between STEMI patients and non-CVD patients, and 17 were between STEMI patients and SAP patients. Seven of these ratios were common to both comparisons (STEMI patients vs. non-CVD patients and STEMI patients vs. SAP patients). Additionally, two ratios were consistently observed among the STEMI, SAP and non-CVD groups (anthranilic acid: aspartic acid and GSG (glutamine: serine + glycine)). These findings provide new insight into the diagnosis and pathogenesis of STEMI.

Effects of complex probiotics on intestinal function and its regulatory mechanism in patients with constipation.

Chronic constipation is a multi-symptomatic, multifactorial, and heterogeneous gastrointestinal disorder. Current pharmacological treatments for chronic constipation are limited and might negatively impact the patients' quality of life. Although probiotics have been shown to improve constipation symptoms, their specific regulatory mechanisms remain unclear. This study sought to explore how probiotic complexes may affect chronic constipation by improving patients' defecation habits. Furthermore, microbial profiles and non-targeted metabolites were assessed to explore the metabolic pathways involved in the improvement of constipation by probiotics. Patients with chronic constipation were treated using a single-blind, randomised, placebo-controlled trial design. The experimental group was administered Lactobacillus powder prepared from 15 probiotic products, and maltodextrin was used as a placebo. Samples were collected twice daily for 4 weeks, and faecal samples were analysed using 16S rRNA sequencing and untargeted metabolic histology. Probiotic treatment changed the makeup of the gut microbiota, enhanced the quantity of Bifidobacterium and Lactobacillus, and markedly reduced clinical symptoms. The 16S rRNA analysis revealed that the abundance of Bifidobacterium and Prevotella increased while that of Thickettsia declined. Moreover, there was a decrease in the abundance of Faecalibacterium and Roseburia. Non-targeted metabolomics analysis identified several differential metabolites, including succinic acid, fumaric acid, cholesterol, xanthurenic acid, 3-alpha,7-alpha-trihydroxy-5beta-cholestan-26-oic, and N-methyltryptamine. KEGG analysis showed that these metabolites were mainly associated with metabolic pathways such as primary bile acid biosynthesis, tryptophan metabolism, alanine, aspartate and glutamate metabolism, phenylalanine metabolism, cholesterol metabolism, and propanoate metabolism. In this study, gut microbiome and non-targeted metabolome analyses were performed on collected faecal samples to compare characteristic microorganisms and differential metabolites to provide new insights and references for probiotic intervention in constipation. Trial registered at chictr.org.cn under number: ChiCTR2200056274.

Circulating tryptophan–kynurenine pathway metabolites are associated with all‐cause mortality among patients with stage I–III colorectal cancer

AbstractAlterations within the tryptophan–kynurenine metabolic pathway have been linked to the etiology of colorectal cancer (CRC), but the relevance of this pathway for prognostic outcomes in CRC patients needs further elucidation. Therefore, we investigated associations between circulating concentrations of tryptophan–kynurenine pathway metabolites and all‐cause mortality among CRC patients. This study utilizes data from 2102 stage I–III CRC patients participating in six prospective cohorts involved in the international FOCUS Consortium. Preoperative circulating concentrations of tryptophan, kynurenine, kynurenic acid (KA), 3‐hydroxykynurenine (HK), xanthurenic acid (XA), 3‐hydroxyanthranilic acid (HAA), anthranilic acid (AA), picolinic acid (PA), and quinolinic acid (QA) were measured by liquid chromatography–tandem mass spectrometry. Using Cox proportional hazards regression, we examined associations of above‐mentioned metabolites with all‐cause mortality, adjusted for potential confounders. During a median follow‐up of 3.2 years (interquartile range: 2.2–4.9), 290 patients (13.8%) deceased. Higher blood concentrations of tryptophan, XA, and PA were associated with a lower risk of all‐cause mortality (per doubling in concentrations: tryptophan: HR = 0.56; 95%CI:0.41,0.76, XA: HR = 0.74; 95%CI:0.64,0.85, PA: HR = 0.76; 95%CI:0.64,0.92), while higher concentrations of HK and QA were associated with an increased risk of death (per doubling in concentrations: HK: HR = 1.80; 95%CI:1.47,2.21, QA: HR = 1.31; 95%CI:1.05,1.63). A higher kynurenine‐to‐tryptophan ratio, a marker of cell‐mediated immune activation, was associated with an increased risk of death (per doubling: HR = 2.07; 95%CI:1.52,2.83). In conclusion, tryptophan–kynurenine pathway metabolites may be prognostic markers of survival in CRC patients.

Vinegar-processed Schisandra Chinensis enhanced therapeutic effects on colitis-induced depression through tryptophan metabolism

BackgroundUlcerative colitis (UC) is an inflammatory bowel disease characterized by its incurable nature and undefined etiology, which is often accompanied by a high prevalence of comorbid depression. The gut-brain axis has emerged as a promising treatment target in recent years. Purpose: This study aimed to investigate how vinegar-processed Schisandra Chinensis (VSC) enhances therapeutic effects on depressive behavior in chronic UC mice. Methods: A chronic UC model was induced in mice using dextran sulfate sodium. The therapeutic effects of both raw and vinegar-processed Schisandra Chinensis on UC and associated depressive symptoms were assessed. Colonic mucosal damage was evaluated using hematoxylin and eosin (H&E) and Alcian blue staining. The integrity of the blood-brain barrier (BBB) and synaptic structures was visualized via transmission electron microscopy (TEM). Enzyme-linked immunosorbent assay (ELISA) was employed to quantify inflammatory cytokine levels in the colon, serum, and brain, while western blotting was performed for protein expression analysis. Additionally, metagenomic analysis was conducted to investigate gut microbiota composition. Nissl staining and immunofluorescence were used to assess hippocampal neuronal damage, and behavioral assessments including the morris water maze, open field test, forced swimming test and tail suspension test, were implemented to evaluate depressive states. Serum metabolites were analyzed using UPLC-MS/MS. Results: Both raw and vinegar-processed Schisandra Chinensis significantly upregulated aryl hydrocarbon receptor (AhR), inhibited NF-κB p-p65 activation, and reduced levels of pro-inflammatory cytokine. These treatments also enhanced the expression of tight junction proteins, restored colonic mucosal and BBB integrity, alleviated damage to hippocampal neurons, and improved synaptic structure. Behavioral assessments indicated that VSC was particularly effective in ameliorating depressive-like behaviors in chronic UC mice. In the gut, both treatments reshaped the gut microbial composition, restoring the relative abundance of Duncaniella, Candidatus_Amulumruptor, Alistipes, Parabacteroides, Lachnospiraceae_bacterium, uncultured_Bacteroides_sp., Candidatus_Amulumruptor_caecigallinarius, with VSC showing more pronounced effects. Serum metabolomics revealed an increase in tryptophan levels and a decrease in kynurenine and xanthurenic acid levels with VSC, indicating that tryptophan metabolism shifted from the kynurenine pathway to the 5-HT or indole pathway. However, this phenomenon did not occur with Schisandra Chinensis (SC). Conclusion: This study demonstrated that the disruption of tryptophan metabolic balance served as a biological mechanism underlying the occurrence of depressive behaviors induced by UC. The application of SC following vinegar processing enhanced its regulatory effects on gut microbiota and tryptophan metabolism. This findings provided a new insight for the clinical management of gut-brain comorbidities.

Alterations in the Blood Kynurenine Pathway Following Long-Term PM2.5 and PM10 Exposure: A Cross-Sectional Study.

Human exposure to PM2.5 and PM10 has been linked to respiratory and cardiovascular diseases through inflammation activation. The kynurenine pathway is associated with inflammation, and it is necessary to investigate the effects of long-term PM2.5 and PM10 exposure on this pathway. This study aimed to conduct a cross-sectional analysis of long-term PM2.5 and PM10 exposure's impact on the kynurenine pathway using proton NMR spectroscopy (1H-NMR). The participants were divided into a low-PM-exposure group (LG; n = 98), and a high-PM-exposure group (HG; n = 92). The metabolites of tryptophan were determined in blood by 1H-NMR. Serotonin, cinnabarinic acid, xanthurenic acid, 5-hydroxytryptophan, indoleacetic acid, tryptamine, melatonin, L-tryptophan, 5-hydroxy-L-tryptophol, indoxyl, 2-aminobenzoic acid, 5-HTOL, hydroxykynurenine, L-3-hydroxykynurenine, N-formyl kynurenine, 3-hydroxy anthranilic acid, kynurenic acid, and picolinic acid significantly increased (p < 0.05) in the HG group. Conversely, NAD and quinolinic acid significantly decreased in the HG group compared to the LG group. The enzyme activities of indoleamine 2,3-dioxygenase and formamidase significantly decreased, while kynureninase and kynurenine monooxygenase significantly increased. The kynurenine pathway is linked to inflammation and non-communicable diseases. Disruption of the kynurenine pathway from particulate matter might promote diseases. Reducing exposure to the particulate matter is crucial for preventing adverse health effects.

Immune-based Machine learning Prediction of Diagnosis and Illness State in Schizophrenia and Bipolar Disorder

BackgroundSchizophrenia and bipolar disorder frequently face significant delay in diagnosis, leading to being missed or misdiagnosed in early stages. Both disorders have also been associated with trait and state immune abnormalities. Recent machine learning-based studies have shown encouraging results using diagnostic biomarkers in predictive models, but few have focused on immune-based markers. Our main objective was to develop supervised machine learning models to predict diagnosis and illness state in schizophrenia and bipolar disorder using only a panel of peripheral kynurenine metabolites and cytokines. MethodsThe cross-sectional I-GIVE cohort included hospitalized acute bipolar patients (n = 205), stable bipolar outpatients (n = 116), hospitalized acute schizophrenia patients (n = 111), stable schizophrenia outpatients (n = 75) and healthy controls (n = 185). Serum kynurenine metabolites, namely tryptophan (TRP), kynurenine (KYN), kynurenic acid (KA), quinaldic acid (QUINA), xanthurenic acid (XA), quinolinic acid (QUINO) and picolinic acid (PICO) were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), while V-plex Human Cytokine Assays were used to measure cytokines (interleukin-6 (IL-6), IL-8, IL-17, IL-12/IL23-P40, tumor necrosis factor-alpha (TNF-ɑ), interferon-gamma (IFN-γ)). Supervised machine learning models were performed using JMP Pro 17.0.0. We compared a primary analysis using nested cross-validation to a split set as sensitivity analysis. Post-hoc, we re-ran the models using only the significant features to obtain the key markers. ResultsThe models yielded a good Area Under the Curve (AUC) (0.804, Positive Prediction Value (PPV) = 86.95; Negative Prediction Value (NPV) = 54.61) for distinguishing all patients from controls. This implies that a positive test is highly accurate in identifying the patients, but a negative test is inconclusive. Both schizophrenia patients and bipolar patients could each be separated from controls with a good accuracy (SCZ AUC 0.824; BD AUC 0.802). Overall, increased levels of IL-6, TNF-ɑ and PICO and decreased levels of IFN-γ and QUINO were predictive for an individual being classified as a patient. Classification of acute versus stable patients reached a fair AUC of 0.713. The differentiation between schizophrenia and bipolar disorder yielded a poor AUC of 0.627. ConclusionsThis study highlights the potential of using immune-based measures to build predictive classification models in schizophrenia and bipolar disorder, with IL-6, TNF-ɑ, IFN-γ, QUINO and PICO as key candidates. While machine learning models successfully distinguished schizophrenia and bipolar disorder from controls, the challenges in differentiating schizophrenic from bipolar patients likely reflect shared immunological pathways by the both disorders and confounding by a larger state-specific effect. Larger multi-centric studies and multi-domain models are needed to enhance reliability and translation into clinic.

The GLP-1 Receptor Agonist Liraglutide Decreases Primary Bile Acids and Serotonin in the Colon Independently of Feeding in Mice.

Liraglutide, a glucagon-like peptide 1 analog used to treat type 2 diabetes and obesity, is a potential new treatment modality for bile acid (BA) diarrhea. Here, we show that administration of liraglutide significantly decreased total BAs, especially the primary BAs, including cholic acid, chenodeoxycholic acid, taurocholic acid, taurochenodeoxycholic acid, glycocholic acid, and β-muricholic acid, in the liver and feces. In addition, liraglutide significantly decreased tryptophan metabolites, including L-tryptophan, serotonin, 5-hydroxy indole-3-acetic acid, L-kynurenine, and xanthurenic acid, in the colon, whereas it significantly increased indole-3-propionic acid. Moreover, the administration of liraglutide remarkably decreased the expression of apical sodium-dependent bile acid transporter, which mediates BA uptake across the apical brush border member in the ileum, ileal BA binding protein, and fibroblast growth factor 15 in association with decreased expression of the BA-activated nuclear receptor farnesoid X receptor and the heteromeric organic solute transporter Ostα/β, which induces BA excretion, in the ileum. Liraglutide acutely decreased body weight and blood glucose levels in association with decreases in plasma insulin and serotonin levels in food-deprived mice. These findings suggest the potential of liraglutide as a novel inhibitor of primary BAs and serotonin in the colon.

Ribonuclease 4 functions as an intestinal antimicrobial protein to maintain gut microbiota and metabolite homeostasis

Antimicrobial proteins contribute to host-microbiota interactions and are associated with inflammatory bowel disease (IBD), but our understanding on antimicrobial protein diversity and functions remains incomplete. Ribonuclease 4 (Rnase4) is a potential antimicrobial protein with no known function in the intestines. Here we find that RNASE4 is expressed in intestinal epithelial cells (IEC) including Paneth and goblet cells, and is detectable in human and mouse stool. Results from Rnase4-deficient mice and recombinant protein suggest that Rnase4 kills Parasutterella to modulate intestinal microbiome, thereby enhancing indoleamine-2,3-dioxygenase 1 (IDO1) expression and subsequently kynurenic and xanthurenic acid production in IECs to reduce colitis susceptibility. Furthermore, deceased RNASE4 levels are observed in the intestinal tissues and stool from patients with IBD, correlating with increased stool Parasutterella. Our results thus implicate Rnase4 as an intestinal antimicrobial protein regulating gut microbiota and metabolite homeostasis, and as a potential diagnostic biomarker and therapeutic target for IBD.

Circulating Metabolite Biomarkers of Glycemic Control in Youth-Onset Type 2 Diabetes.

We aimed to identify metabolites associated with loss of glycemic control in youth-onset type 2 diabetes. We measured 480 metabolites in fasting plasma samples from the TODAY (Treatment Options for Type 2 Diabetes in Adolescents and Youth) study. Participants (N = 393; age 10-17 years) were randomly assigned to metformin, metformin plus rosiglitazone, or metformin plus lifestyle intervention. Additional metabolomic measurements after 36 months were obtained in 304 participants. Cox models were used to assess baseline metabolites, interaction of metabolites and treatment group, and change in metabolites (0-36 months), with loss of glycemic control adjusted for age, sex, race, treatment group, and BMI. Metabolite prediction models of glycemic failure were generated using elastic net regression and compared with clinical risk factors. Loss of glycemic control (HbA1c ≥8% or insulin therapy) occurred in 179 of 393 participants (mean 12.4 months). Baseline levels of 33 metabolites were associated with loss of glycemic control (q < 0.05). Associations of hexose and xanthurenic acid with treatment failure differed by treatment randomization; youths with higher baseline levels of these two compounds had a lower risk of treatment failure with metformin alone. For three metabolites, changes from 0 to 36 months were associated with loss of glycemic control (q < 0.05). Changes in d-gluconic acid and 1,5-AG/1-deoxyglucose, but not baseline levels of measured metabolites, predicted treatment failure better than changes in HbA1c or measures of β-cell function. Metabolomics provides insight into circulating small molecules associated with loss of glycemic control and may highlight metabolic pathways contributing to treatment failure in youth-onset diabetes.

Metabolomics research on treatment of primary liver cancer with Cortex Juglandis Mandshuricae on LC-MS/MS technology

Diethylnitrosamine (DEN) was applied to create the primary liver cancer (PLC) animal model. In the study, the normal group, model group, cyclophosphamide (CTX) group, Cortex Juglandis Mandshuricae (CJM) extract group, myricetin group and myricitrin group were divided. LC-MS/MS technology was applied to determine the metabolites of liver tissue samples from different locations (nodular and non-nodular parts of liver tissue) in each group of rats. Through metabolomics research, the connection and difference of anti-PLC induced by the CJM extract, myricetin and myricitrin was analyzed. The surface of the liver tissues of rats in the model group was rough, dimly colored, inelastic, on which there were scattered gray white cancer nodules and blood stasis points. The number of cancer nodules was significantly reduced, and the degree of cell malignancy was low, but there were some inflammatory cell infiltrations, necrosis area and karyokinesis in the CJM extract group, myricetin group, myricitrin group and CTX group. The result of metabolic research indicated that 45 potential biomarkers of the PLC were found, as gamma-aminoisobutyrate, taurochenodeoxycholate, xanthurenic acid, etc. There were 22 differential metabolites in the CTX group, 16 differential metabolites in the CJM extract group, 14 differential metabolites in the myricetin group, 14 differential metabolites in the myricitrin group.

Eight-day fasting modulates serum kynurenines in healthy men at rest and after exercise.

Tryptophan's (Trp) metabolites are undervalued markers of human health. Their serum concentrations are modified by physical exercise and other factors, among which fasting has a well-documented role. Although this mechanism is hardly explored, thus, the study aimed to determine the effect of the 8-day fasting period and the impact of such a procedure on a single bout of an endurance exercise on the concentration of kynurenine pathway (KP) metabolites. 10 participants fasted for 8 days, and 10 as a control group participated in the study. The exercise was performed at baseline after an overnight fast and repeated post 8 days. The 8 days of fasting increased the resting 3-hydroxy-L-kynurenine (3HK), picolinic acid (PA), kynurenic acid (KYNA), and xanthurenic acid (XA) serum concentration. Also elevated phenylalanine (Phe) and tyrosine (Tyr) levels were recorded, suggesting expanded proteolysis of muscle proteins. In turn, physical activity caused a decrease in the concentration of 3-hydroxyanthranilic acid (3HAA) and PA after fasting. The obtained results were not recorded in controls. The results of this study show that the health-promoting effects of fasting are associated with changes in the KYN pathway. The increase in the concentration of PA and XA metabolites following fasting is capable of penetrating the blood-brain barrier, and KYNA, which initiates several beneficial changes, supports this assumption.

Longitudinal associations of plasma kynurenines and ratios with fatigue and quality of life in colorectal cancer survivors up to 12 months post-treatment.

Fatigue is prevalent in colorectal cancer (CRC) survivors, impacting their health-related quality of life (HRQoL). Inflammation-induced activation of the kynurenine pathway may play a role in cancer-related fatigue and HRQoL, but evidence is scarce. Therefore, we aimed to investigate longitudinal associations of plasma tryptophan, kynurenines, and ratios with fatigue and HRQoL in CRC survivors up to 12 months post-treatment. Repeated measurements at 6 weeks, 6 months, and 12 months post-treatment were performed in 249 stage I-III CRC survivors. Plasma tryptophan and eight kynurenines were analyzed using liquid chromatography-tandem mass spectrometry (LC/MS-MS). Fatigue and HRQoL outcomes were evaluated using validated questionnaires. Confounder-adjusted linear mixed models were conducted to analyze longitudinal associations, with false discovery rate (FDR) correction. Higher tryptophan (Trp), kynurenic acid (KA), and xanthurenic acid (XA) concentrations, as well as a higher kynurenic acid-to-quinolinic acid ratio (KA/QA), were associated with less fatigue and better functioning, while a higher kynurenine-to-tryptophan ratio (KTR) and 3-hydroxykynurenine ratio (HKr) were associated with more fatigue and worse functioning. Finally, higher KA and XA concentrations and a higher KA/QA ratio were associated with a higher overall HRQoL summary score, while a higher HKr was associated with a lower overall HRQoL summary score. In conclusion, we observed that tryptophan and several kynurenines were longitudinally associated with fatigue and HRQoL in CRC survivors up to 12 months post-treatment. Future research is needed to validate our findings and explore the potential of the kynurenine pathway as intervention target for reducing fatigue and enhancing HRQoL after CRC treatment.

#1984 Extracellular vesicles drive loss of endothelial homeostasis in pediatric chronic kidney disease

Abstract Background and Aims Cardiovascular disease (CVD) is the main cause of mortality in chronic kidney disease (CKD). However, the pathogenesis of CVD in CKD remains incompletely understood. Extracellular vesicles (EVs) emerged as mediators of inter-organ cross-talk and endothelial EVs (EC-EVs) were previously associated with CVD. We hypothesized that CKD drives endothelial EV release in CKD and that these EC-EVs drive CVD in CKD. Method A cohort of 94 children (mean age 10.9 years) at different stages of CKD (patients with or without dialysis and after kidney transplantation (KTx)) and age-matched healthy donors was recruited, offering the unique opportunity to analyze cardiovascular effects of CKD and EV dynamics in absence of age-related comorbidities. Thorough characterization of plasma EVs by electron microscopy, nanoparticle tracking analysis (NTA), flow cytometry and miRNA sequencing was carried out. Functional properties of patient EVs and CKD-specific EV release mechanisms were tested in vitro. Results EC-EVs were elevated in hemodialysis (HD) patients (as measured by flow cytometry) while total EV counts showed higher concentrations in peritoneal dialysis patients (according to NTA). Longitudinal follow-ups revealed that EC-EVs decreased after receiving KTx. EV small RNA sequencing showed lower abundance of 30 microRNAs in EVs from CKD patients, most pronounced in HD patients compared to both healthy donors and KTx recipients. Downregulation of let-7d-5p, miR-19a-3p, miR-24-3p, miR-103a-3p and miR-142-3p was confirmed using RT-qPCR. Gene enrichment analyses predicted angiogenesis and smooth muscle cell (SMC) proliferation as targets of differentially regulated miRNAs in CKD. In vitro, angiogenesis of Human Umbilical Vein Endothelial Cells (HUVECs) was decreased upon treatment with CKD EVs as indicated by decreased vascular tube formation, endothelial migration and proliferation while SMC proliferation remained unchanged. To assess the putative role of uremic toxins for EV release in CKD, we focused on tryptophan metabolites and performed targeted plasma metabolomics that showed stage-dependent increases of uremic toxins of indole and kynurenine pathways in children with CKD, with highest levels in dialysis patients and almost normal levels after KTx. Uremic toxins indoxyl sulfate, formylkynurenine and xanthurenic acid correlated positively with EC-EVs in our cohort, but were not sufficient to trigger EV release from aortic endothelial cells alone. However, high shear stress together with indoxyl sulfate increased EV release from venous endothelial cells corresponding to higher endothelial EV concentrations in HD patients with arterio-venous fistulas (AVF) and recapitulated EV miRNA changes in vitro observed in CKD in vivo (lower abundance of let-7d-5p and miR-24-3p). Conclusion Endothelial EV release and decreased EV miRNAs associate with advanced CKD while increased endothelial shear stress and indoxyl sulfate form potential causative factors of altered EV phenotype. CKD EVs inhibit angiogenesis in vitro, potentially caused by dysregulated EV miRNAs that could form novel therapeutical targets to reduce CVD burden in CKD.

Exploring the kynurenine pathway in mild traumatic brain injury: A longitudinal study.

A potential source of novel biomarkers for mTBI is the kynurenine pathway (KP), a metabolic pathway of tryptophan (Trp), that is up-regulated by neuroinflammation and stress. Considering that metabolites of the KP (kynurenines) are implicated in various neuropsychiatric diseases, exploration of this pathway could potentially bridge the gap between physiological and psychological factors in the recovery process after mTBI. This study, therefore, set out to characterize the KP after mTBI and to examine associations with long-term outcome. Patients were prospectively recruited at the emergency department (ED), and blood samples were obtained in the acute phase (<24 h; N = 256) and at 1-month follow-up (N = 146). A comparison group of healthy controls (HC; N = 32) was studied at both timepoints. Trp, kynurenines, and interleukin (IL)-6 and IL-10 were quantified in plasma. Clinical outcome was measured at six months post-injury. Trp, xanthurenic acid (XA), and picolinic acid (PA) were significantly reduced in patients with mTBI relative to HC, corrected for age and sex. For Trp (d = -0.57 vs. d = -0.29) and XA (d = -0.98 vs. d = -0.32), larger effects sizes were observed during the acute phase compared to one-month follow-up, while for PA (d = -0.49 vs. d = -0.52) effect sizes remained consistent. Findings for other kynurenines (e.g., kynurenine, kynurenic acid, and quinolinic acid) were non-significant after correction for multiple testing. Within the mTBI group, lower acute Trp levels were significantly related to incomplete functional recovery and higher depression scores at 6 months post-injury. No significant relationships were found for Trp, XA, and PA with IL-6 or IL-10 concentrations. In conclusion, our findings indicate that perturbations of the plasma KP in the hyperacute phase of mTBI and 1 month later are limited to the precursor Trp, and glutamate system modulating kynurenines XA and PA. Correlations between acute reductions of Trp and unfavorable outcomes may suggest a potential substrate for pharmacological intervention.

The Mediating Role of Kynurenine Pathway Metabolites on the Relationship Between Inflammation and Muscle Mass in Oldest-Old Men.

Tryptophan (TRP) metabolites along the kynurenine (KYN) pathway (KP) have been found to influence muscle. Proinflammatory cytokines are known to stimulate the degradation of TRP down the KP. Given that both inflammation and KP metabolites have been connected with loss of muscle, we assessed the potential mediating role of KP metabolites on inflammation and muscle mass in older men. Five hundred and five men (85.0 ± 4.2 years) from the Osteoporotic Fractures in Men cohort study with measured D3-creatine dilution (D3Cr) muscle mass, KP metabolites, and inflammation markers (C-reactive protein [CRP], alpha-1-acid glycoprotein [AGP] and a subsample [n = 305] with interleukin [IL-6, IL-1β, IL-17A] and tumor necrosis factor-α [TNF-α]) were included in the analysis. KP metabolites and inflammatory markers were measured using liquid chromatography-tandem mass spectrometry and immunoassays, respectively. 23%-92% of the inverse relationship between inflammatory markers and D3Cr muscle mass was mediated by KP metabolites (indirect effect p < .05). 3-hydroxyanthranilic acid (3-HAA), quinolinic acid (QA), TRP, xanthurenic acid (XA), KYN/TRP, 3-hydroxykynurenine (3-HK)/3-HAA, QA/3-HAA, and nicotinamide (NAM)/QA mediated the AGP relationship. 3-HAA, QA, KYN/TRP, 3-HK/XA, HKr ratio, 3-HK/3-HAA, QA/3-HAA, and NAM/QA mediated the CRP. KYN/TRP, 3-HK/XA, and NAM/QA explained the relationship for IL-6 and 3-HK/XA and QA/3-HAA for TNF-α. No mediation effect was observed for the other cytokines (indirect effect p > .05). KP metabolites, particularly higher ratios of KYN/TRP, 3-HK/XA, 3-HK/3-HAA, QA/3-HAA, and a lower ratio of NAM/QA, mediated the relationship between inflammation and low muscle mass. Our preliminary cross-sectional data suggest that interventions to alter D3Cr muscle mass may focus on KP metabolites rather than inflammation per se.

Antibody-blocking of a tick transporter impairs Anaplasma phagocytophilum colonization in Haemaphysalis longicornis ticks

The invasive Asian longhorned tick Haemaphysalis longicornis that vectors and transmits several animal pathogens is significantly expanding in the United States. Recent studies report that these ticks also harbor human pathogens including Borrelia burgdorferi sensu lato, Babesia microti, and Anaplasma phagocytophilum. Therefore, studies that address the interactions of these ticks with human pathogens are important. In this study, we report the characterization of H. longicornis organic anion-transporting polypeptides (OATPs) in interactions of these ticks with A. phagocytophilum. Using OATP-signature sequence, we identified six OATPs in the H. longicornis genome. Bioinformatic analysis revealed that H. longicornis OATPs are closer to other tick orthologs rather than to mammalian counterparts. Quantitative real-time PCR analysis revealed that OATPs are highly expressed in immature stages when compared to mature stages of these ticks. In addition, we noted that the presence of A. phagocytophilum upregulates a specific OATP in these ticks. We also noted that exogenous treatment of H. longicornis with xanthurenic acid, a tryptophan metabolite, influenced OATP expression in these ticks. Immunoblotting analysis revealed that antibody generated against Ixodes scapularis OATP cross-reacted with H. longicornis OATP. Furthermore, treatment of H. longicornis with OATP antibody impaired colonization of A. phagocytophilum in these ticks. These results not only provide evidence that the OATP-tryptophan pathway is important for A. phagocytophilum survival in H. longicornis ticks but also indicate OATP as a promising candidate for the development of a universal anti-tick vaccine to target this bacterium and perhaps other rickettsial pathogens of medical importance.

Self-signal electrochemical identification of circulating tumor DNA employing poly-xanthurenic acid assembled on black phosphorus nanosheets

A self-signal electrochemical identification interface was prepared for the determination of circulating tumor DNA (ctDNA) in peripheral blood based on poly-xanthurenic acid (PXTA) assembled on black phosphorus nanosheets (BPNSs) acquired through simple ultrasonication method. The BPNSs with large surface area could be integrated with the xanthurenic acid (XTA) monomers by right of physisorption, and hence improved the electropolymerization efficiency and was beneficial to the enlargement of the signal response of PXTA. The assembled PXTA/BPNSs composite with attractive electrochemical activity was adopted as a platform for the recognition of DNA immobilization and hybridization. The probe ssDNA was covalently fixed onto the PXTA/BPNSs composite with plentiful carboxyl groups through the terminate free amines of DNA probes by use of the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydrosulfosuccinimide cross-linking reaction, accompanied with the decline of the self-signal response. When the hybridization between the probe ssDNA and the target DNA was accomplished, the self-signal response of the composite interface reproduced by virtue of the shaping of helix construction. The determination limit of the assembled DNA identification interface was 2.1 × 10−19 mol/L, and the complementary target DNA concentrations varied from 1.0 × 10−18 mol/L to 1.0 × 10−12 mol/L. The DNA identification platform displayed magnificent sensitivity, specificity and stability, and was efficaciously implemented to the mensuration of ctDNA derived from colorectal cancer.

Altered neopterin and IDO in kynurenine metabolism based on LC-MS/MS metabolomics study: Novel therapeutic checkpoints for type 2 diabetes mellitus

BackgroundThis study assessed the alternations of kynurenine pathway (KP) and neopterin in type 2 diabetes mellitus (T2DM) and explored possible differential metabolites. MethodsA fresh residual sera panel was collected from 80 healthy control (HC) individuals and 72 T2DM patients. Metabolites/ratios of interest including tryptophan (TRP), kynurenine (KYN), 5-hydroxytryptamine (5HT), kynurenic acid (KA), xanthurenic acid (XA), neopterin (NEO), KA/KYN ratio and KYN/TRP ratio were determined using a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics approach, and the difference between groups was assessed. Supervised orthogonal partial least squares-discriminant analysis and differential metabolite screening with fold change (FC) were performed to identify distinct biomarkers. The diagnostic performance of KP metabolites in T2DM was evaluated. ResultsSignificant decreases of TRP, 5HT, KA, XA, and KA/KYN and increases of KYN/TRP and NEO in T2DM compared to HC group were observed (P < 0.05). The KP metabolites panel significantly changed between T2DM and HC groups (Q2: 0.925, P < 0.005). 5HT (FC: 0.63, P < 0.01) and NEO (FC: 3.27, P < 0.01) were proven to be distinct differential metabolites. A combined testing of fasting plasma glucose and KYN/TRP showed good value in the prediction of T2DM (AUC: 0.904, 95% CI 0.843–0.947). ConclusionsThe targeted LC-MS/MS metabolomics study is a powerful tool for evaluating the status of T2DM. This study facilitated the application of KP metabolomics into future clinical practice. 5HT and NEO are promising biomarkers in T2DM. KYN/TRP was highly associated with the development of T2DM and may serve as a potential treatment target.

Xanthurenic acid: A role in brain intercellular signaling.

Xanthurenic acid (XA) raises a growing multidisciplinary interest based upon its oxidizing properties, its ability to complex certain metal ions, and its detoxifier capacity of 3-hydroxykynurenine (3-HK), its brain precursor. However, little is still known about the role and mechanisms of action of XA in the central nervous system (CNS). Therefore, many research groups have recently investigated XA and its central functions extensively. The present paper critically reviews and discusses all major data related to XA properties and neuronal activities to contribute to the improvement of the current knowledge on XA's central roles and mechanisms of action. In particular, our data showed the existence of a specific G-protein-coupled receptor (GPCR) for XA localized exclusively in brain neurons exhibiting Ca2+-dependent dendritic release and specific electrophysiological responses. XA properties and central activities suggest a role for this compound in brain intercellular signaling. Indeed, XA stimulates cerebral dopamine (DA) release contrary to its structural analog, kynurenic acid (KYNA). Thus, KYNA/XA ratio could be fundamental in the regulation of brain glutamate and DA release. Cerebral XA may also represent an homeostatic signal between the periphery and several brain regions where XA accumulates easily after peripheral administration. Therefore, XA status in certain psychoses or neurodegenerative diseases seems to be reinforced by its brain-specific properties in balance with its formation and peripheral inputs.

Tangshen Formula alleviates inflammatory injury against aged diabetic kidney disease through modulating gut microbiota composition and related amino acid metabolism

Diabetic kidney disease (DKD) is leading causes and one of the fastest growing causes of chronic kidney disease worldwide, and leads to high morbidity and mortality. Emerging evidences have revealed gut microbiota dysbiosis and related metabolism dysfunction play a dominant role in DKD progression and treatment through modulating inflammation. Our previous studies showed that Tangshen Formula (TSF), a Chinese herbal prescription, exhibited anti-inflammatory effect on DKD, but underlying mechanism that involved gut microbiota and related metabolism in aged model remained obscure. Here, BTBR ob/ob mice were used to establish aged DKD model, and 16S rRNA sequence and untargeted metabolomic analyses were employed to investigate the correlation between colonic microbiota and serum metabolism. The aged ob/ob mice exhibited obvious glomerular and renal tubule injury and kidney function decline in kidney, while TSF treatment significantly attenuated these abnormalities. TSF also exhibited potent anti-inflammatory effect in aged ob/ob mice indicating by reduced proinflammatory factor IL-6 and TNF-α, MCP-1 and COX-2 in serum, kidney and intestine, which suggested the involvement of gut microbiota with TSF effect. The 16S rDNA sequencing of the colonic microbiome and untargeted serum metabolomics analysis revealed significant differences in gut microbiota structure and serum metabolomic profiles between WT and ob/ob mice. Notably, TSF treatment reshaped the structure of gut microbiota and corrected the disorder of metabolism especially tryptophan metabolism and arginine biosynthesis. TSF increased Anaeroplasma and Barnesiella genera and decreased Romboutsia, Akkermansia, and Collinsella genera, and further elevated tryptophan, 5-hydroxyindoleacetate, glutamic acid, aspartate and reduced 4-hydroxy-2-quinolinecarboxylic acid, indole-3-acetic acid, xanthurenic acid, glutamine. Further correlation analysis indicated that disturbed gut microbiota was linked to tryptophan metabolism and arginine biosynthesis to regulate inflammation in aged DKD. Our data revealed that TSF attenuated renal inflammation by modulating gut microbiota and related amino acid metabolism in aged DKD model, highlighting gut microbiota and related metabolism functioned as potential therapeutic target for DKD in elderly patients.