Rapid and reliable HILIC-MS/MS method for monitoring allantoin as a biomarker of oxidative stress

Metabolomics-based search for lung cancer markers among patients with different smoking status

Tobacco smoking is the main etiological factor of lung cancer (LC), which can also cause metabolome disruption. This study aimed to investigate whether the observed metabolic shift in LC patients was also associated with their smoking status. Untargeted metabolomics profiling was applied for the initial screening of changes in serum metabolic profile between LC and chronic obstructive pulmonary disease (COPD) patients, selected as a non-cancer group. Differences in metabolite profiles between current and former smokers were also tested. Then, targeted metabolomics methods were applied to verify and validate the proposed LC biomarkers. For untargeted metabolomics, a single extraction-dual separation workflow was applied. The samples were analyzed using a liquid chromatograph-high resolution quadrupole time-of-flight mass spectrometer. Next, the selected metabolites were quantified using liquid chromatography-triple-quadrupole mass spectrometry. The acquired data confirmed that patients' stratification based on smoking status impacted the discriminating ability of the identified LC marker candidates. Analyzing a validation set of samples enabled us to determine if the putative LC markers were truly robust. It demonstrated significant differences in the case of four metabolites: allantoin, glutamic acid, succinic acid, and sphingosine-1-phosphate. Our research showed that studying the influence of strong environmental factors, such as tobacco smoking, should be considered in cancer marker research since it reduces the risk of false positives and improves understanding of the metabolite shifts in cancer patients.

Distinct Metabolic Profiles of Ocular Hypertensives in Response to Hypoxia

Glaucoma is a neurodegenerative disease that affects the retinal ganglion cells (RGCs). The main risk factor is elevated intraocular pressure (IOP), but the actual cause of the disease remains unknown. Emerging evidence indicates that metabolic dysfunction plays a central role. The aim of the current study was to determine and compare the effect of universal hypoxia on the metabolomic signature in plasma samples from healthy controls (n = 10), patients with normal-tension glaucoma (NTG, n = 10), and ocular hypertension (OHT, n = 10). By subjecting humans to universal hypoxia, we aim to mimic a state in which the mitochondria in the body are universally stressed. Participants were exposed to normobaric hypoxia for two hours, followed by a 30 min recovery period in normobaric normoxia. Blood samples were collected at baseline, during hypoxia, and in recovery. Plasma samples were analyzed using a non-targeted metabolomics approach based on liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS). Multivariate analyses were conducted using principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA), and univariate analysis using the Wilcoxon signed-rank test and false discovery rate (FDR) correction. Unique metabolites involved in fatty acid biosynthesis and ketone body metabolism were upregulated, while metabolites of the kynurenine pathway were downregulated in OHT patients exposed to universal hypoxia. Differential affection of metabolic pathways may explain why patients with OHT initially do not suffer or are more resilient from optic nerve degeneration. The metabolomes of NTG and OHT patients are regulated differently from control subjects and show dysregulation of metabolites important for energy production. These dysregulated processes may potentially contribute to the elevation of IOP and, ultimately, cell death of the RGCs.

An AI-powered patient triage platform for future viral outbreaks using COVID-19 as a disease model

Over the last century, outbreaks and pandemics have occurred with disturbing regularity, necessitating advance preparation and large-scale, coordinated response. Here, we developed a machine learning predictive model of disease severity and length of hospitalization for COVID-19, which can be utilized as a platform for future unknown viral outbreaks. We combined untargeted metabolomics on plasma data obtained from COVID-19 patients (n = 111) during hospitalization and healthy controls (n = 342), clinical and comorbidity data (n = 508) to build this patient triage platform, which consists of three parts: (i) the clinical decision tree, which amongst other biomarkers showed that patients with increased eosinophils have worse disease prognosis and can serve as a new potential biomarker with high accuracy (AUC = 0.974), (ii) the estimation of patient hospitalization length with ± 5 days error (R2 = 0.9765) and (iii) the prediction of the disease severity and the need of patient transfer to the intensive care unit. We report a significant decrease in serotonin levels in patients who needed positive airway pressure oxygen and/or were intubated. Furthermore, 5-hydroxy tryptophan, allantoin, and glucuronic acid metabolites were increased in COVID-19 patients and collectively they can serve as biomarkers to predict disease progression. The ability to quickly identify which patients will develop life-threatening illness would allow the efficient allocation of medical resources and implementation of the most effective medical interventions. We would advocate that the same approach could be utilized in future viral outbreaks to help hospitals triage patients more effectively and improve patient outcomes while optimizing healthcare resources.

A Systematic Review and Meta-Analysis of the Association between Uric Acid and Allantoin and Rheumatoid Arthritis

Alterations in the circulating concentrations of uric acid and its degradation product, allantoin, might account for the systemic pro-oxidant state and the increased cardiovascular risk in rheumatoid arthritis (RA). We sought to address this issue by conducting a systematic review and meta-analysis of the association between the plasma/serum concentrations of uric acid and allantoin and RA. We searched PubMed, Scopus, and Web of Science from inception to 20 June 2023 for studies comparing plasma/serum concentrations of uric acid and allantoin between RA patients and healthy controls. We assessed the risk of bias with the JBI Critical Appraisal Checklist for analytical studies and the certainty of evidence with the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group system. In the 19 studies selected for analysis, there were non-significant differences in uric acid concentrations between RA patients and controls (standard mean difference, SMD = 0.11, 95% CI -0.07 to 0.30, p = 0.22; I2 = 87.9%, p < 0.001; low certainty of evidence). By contrast, the concentrations of allantoin were significantly higher in RA patients (SMD = 1.10, 95% CI 0.66 to 1.55, p < 0.001; I2 = 55.6%, p = 0.08; extremely low certainty of evidence). In meta-regression, a significant association was observed between the SMD of uric acid concentrations and body mass index, a risk factor for atherosclerosis and cardiovascular disease (t = 3.35, p = 0.007). Our study has shown a significant increase in the concentrations of the oxidative stress biomarker allantoin in patients with RA. Further research is warranted to investigate the interplay between uric acid, allantoin, redox balance, and cardiovascular disease in this group. (PROSPERO registration number: CRD42023441127).

Integrated microbiome and metabolome analysis reveals novel urinary microenvironmental signatures in interstitial cystitis/bladder pain syndrome patients

BACKGROUND

The pathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS) has not been elucidated, but urinary microorganisms and metabolites have been shown to be closely associated with the inflammatory response of IC/BPS. Nevertheless, the exact mechanisms related to this response have not been clarified.

METHODS

16S rRNA sequencing and untargeted metabolomics techniques were used to analyse the urinary microbial and metabolite profiles of 30 IC/BPS patients and 30 healthy controls, and correlation analyses were performed to explore the mechanisms by which they might be involved in the inflammatory response of IC/BPS.

RESULTS

Twenty-eight differential genera, such as Lactobacillus and Sphingomonas, were identified. A total of 44 differential metabolites such as 1,3,7-trimethyluric acid and theophylline were screened. The abundance of Lactobacillus and Escherichia-Shigella was significantly higher in the urine of female IC/BPS patients and healthy controls compared to males, while Bacteroides and Acinetobacter were lower than in males. The results of the Pearson correlation analysis suggested that differential microorganisms may influence the composition of metabolites. The Lactobacillus genus may be a protective bacterium against IC/BPS, whereas Sphingomonas may be a pathogenic factor. The differential metabolite theophylline, as an anti-inflammatory substance, may downregulate the inflammatory response of IC/BPS.

CONCLUSIONS

This study revealed microbial and metabolite profiles in the urine of IC/BPS patients versus healthy controls in both males and females. We also found some microorganisms and metabolites closely related to the inflammatory response of IC/BPS, which provided directions for future aetiological and therapeutic research.

Serum but not cerebrospinal fluid levels of allantoin are increased in de novo Parkinson's disease

Oxidative stress supposedly plays a role in the pathogenesis of Parkinson's disease (PD). Uric acid (UA), a powerful antioxidant, is lowered in PD while allantoin, the oxidation product of UA and known biomarker of oxidative stress, was not systematically studied in PD. We aim to compare serum and cerebrospinal fluid (CSF) levels of UA, allantoin, and allantoin/UA ratio in de novo PD patients and controls, and evaluate their associations with clinical severity and the degree of substantia nigra degeneration in PD. We measured serum and CSF levels of UA, allantoin, and allantoin/UA ratio in 86 PD patients (33 females, mean age 57.9 (SD 12.6) years; CSF levels were assessed in 51 patients) and in 40 controls (19 females, 56.7 (14.1) years). PD patients were examined using Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Montreal Cognitive Assessment (MoCA), Scales for Outcomes in Parkinson Disease-Autonomic (SCOPA-AUT), the University of Pennsylvania Smell Identification Test (UPSIT), one-night video-polysomnography, and dopamine transporter single-photon emission computed tomography (DAT-SPECT). Serum allantoin and allantoin/UA ratio were significantly increased in the PD group compared to controls (p < 0.001 and p = 0.002, respectively). Allantoin/UA ratios in serum and CSF were positively associated with the SCOPA-AUT score (p = 0.005 and 0.031, respectively) and RBD presence (p = 0.044 and 0.028, respectively). In conclusion, serum allantoin and allantoin/UA ratio are elevated in patients with de novo PD. Allantoin/UA ratio in serum and CSF is associated with autonomic dysfunction and RBD presence, indicating that higher systemic oxidative stress occurs in PD patients with more diffuse neurodegenerative changes.

Developmental programming: Preconceptional and gestational exposure of sheep to a real-life environmental chemical mixture alters maternal metabolome in a fetal sex-specific manner

BACKGROUND

Everyday, humans are exposed to a mixture of environmental chemicals some of which have endocrine and/or metabolism disrupting actions which may contribute to non-communicable diseases. The adverse health impacts of real-world chemical exposure, characterized by chronic low doses of a mixture of chemicals, are only recently emerging. Biosolids derived from human waste represent the environmental chemical mixtures humans are exposed to in real life. Prior studies in sheep have shown aberrant reproductive and metabolic phenotypes in offspring after maternal biosolids exposure.

OBJECTIVE

To determine if exposure to biosolids perturbs the maternal metabolic milieu of pregnant ewes, in a fetal sex-specific manner.

METHODS

Ewes were grazed on inorganic fertilizer (Control) or biosolids-treated pastures (BTP) from before mating and throughout gestation. Plasma from pregnant ewes (Control n = 15, BTP n = 15) obtained mid-gestation were analyzed by untargeted metabolomics. Metabolites were identified using Agilent MassHunter. Multivariate analyses were done using MetaboAnalyst 5.0 and confirmed using SIMCA.

RESULTS

Univariate and multivariate analysis of 2301 annotated metabolites identified 193 differentially abundant metabolites (DM) between control and BTP sheep. The DM primarily belonged to the super-class of lipids and organic acids. 15-HeTrE, oleamide, methionine, CAR(3:0(OH)) and pyroglutamic acid were the top DM and have been implicated in the regulation of fetal growth and development. Fetal sex further exacerbated differences in metabolite profiles in the BTP group. The organic acids class of metabolites was abundant in animals with male fetuses. Prenol lipid, sphingolipid, glycerolipid, alkaloid, polyketide and benzenoid classes showed fetal sex-specific responses to biosolids.

DISCUSSION

Our study illustrates that exposure to biosolids significantly alters the maternal metabolome in a fetal sex-specific manner. The altered metabolite profile indicates perturbations to fatty acid, arginine, branched chain amino acid and one‑carbon metabolism. These factors are consistent with, and likely contribute to, the adverse phenotypic outcomes reported in the offspring.

Screening method for the simultaneous determination of allantoin and uric acid from dried blood spots

Uric acid and its oxidation product allantoin are excellent biomarkers of oxidative stress in humans. Currently, there are high requirements not only for tests monitoring oxidative stress but also for screening laboratory tests in general. The highest demand is imposed on the simplest sampling, easy transport of the sample, and the shortest possible analysis time. The possible solution how to fulfil the requirements is sampling by dried blood spot technique with subsequent HPLC-MS/MS analysis. A fast, sensitive, and reliable HPLC-MS/MS method for the simultaneous determination of uric acid and allantoin from dried blood spots using stable isotopically labelled analogs as internal standards was developed. The separation took place in the reversed phase within 3 min, with protein precipitation and extraction in a one-step procedure. The analytical parameters of the method were satisfactory with an excellent linear range. The presented method was used to determine allantoin and uric acid levels in dried blood spot samples from 100 healthy volunteer donors. The median uric acid concentration in the cohort was 239.3 µmol/L and the median allantoin concentration was 5.6 µmol/L. The presented analytical protocol and method are suitable for screening and monitoring allantoin and uric acid levels as biomarkers of oxidative stress in clinical practice.

Predictive Value of Preoperative Profiling of Serum Metabolites for Emergence Agitation After General Anesthesia in Adult Patients

Background: Emergence agitation (EA) in adult patients under general anesthesia leads to increased postoperative complications and heavy medical burden. Unfortunately, its pathogenesis has not been clarified until now. The purpose of the present study was to explore the relationship between preoperative serum metabolites and EA. Methods: We used an untargeted metabolic analysis method to investigate the different metabolomes in the serum of EA patients and non-EA patients undergoing elective surgical procedures after the induction of general anesthesia. A Richmond Agitation-Sedation Scale score ≥ +2 was diagnosed as EA during postoperative emergence. Non-EA patients were matched with EA patients according to general characteristics. Preoperative serum samples of the two groups were collected to investigate the association between serum metabolites and EA development. Results: The serum samples of 16 EA patients with 34 matched non-EA patients were obtained for metabolic analysis. After screening and alignment with databases, 31 altered metabolites were detected between the two groups. These metabolites were mainly involved in the metabolism of lipids, purines, and amino acids. Analyses of receiver-operating characteristic curves showed that the preoperative alterations of choline, cytidine, glycerophosphocholine, L-phenylalanine, oleamide, and inosine may be associated with adult EA. Conclusion: Multiple metabolic abnormalities (including those for lipids, purines, and amino acids) and other pathological processes (e.g., neurotransmitter imbalance and oxidative stress) may contribute to EA. Several altered metabolites in serum before surgery may have predictive value for EA diagnosis. This study might afford new metabolic clues for the understanding of EA pathogenesis.

Patients with REM sleep behavior disorder have higher serum levels of allantoin

INTRODUCTION

Rapid eye movement (REM) sleep behavior disorder (RBD) is associated with an increased risk of developing Parkinson's disease (PD). Low uric acid (UA) levels are associated with the risk of development and progression of PD. Allantoin is the major oxidation product of UA and is considered as a biomarker of oxidative stress. We aimed to compare serum levels of UA, allantoin, and allantoin/UA ratio in RBD patients with those in healthy controls, and to examine their associations with clinical severity.

METHODS

We evaluated serum levels of UA, allantoin, and allantoin/UA ratio in 38 RBD patients (one female, mean age 66.8 (SD 6.3) years) and in 47 controls (four females, 66.8 (7.6) years). All RBD patients were assessed according to an examination protocol, which included structured interview, Montreal Cognitive Assessment (MoCA), Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), and dopamine transporter single-photon emission computed tomography (DAT-SPECT). The lower putaminal binding ratio from both hemispheres was used for analysis.

RESULTS

Mean serum allantoin concentration and allantoin/UA ratio were significantly increased in the RBD group compared to controls (2.6 (1.8) vs. 1.4 (0.7) μmol/l, p = 0.0004, and 0.008 (0.004) vs. 0.004 (0.002), p < 0.0001, respectively). There were no significant differences in UA levels between the two groups. No significant associations between any biochemical parameter and RBD duration, putaminal binding ratio on DAT-SPECT, MDS-UPDRS, or MoCA score were found.

CONCLUSION

Serum allantoin and allantoin/UA ratio are increased in RBD patients in comparison to controls, which may reflect increased systemic oxidative stress in prodromal synucleinopathy.

Decreased serum uric acid in patients with traumatic brain injury or after cerebral tumor surgery

Objectives:

To investigate changes in sUA in patients with TBI or patients after cerebral tumor surgery and the possible mechanism of these changes.

Methods:

This prospective cohort study enrolled patients with TBI or underwent cerebral tumor surgery at West China Hospital, China, from November 2014 to May 2018. Serum UA (sUA) levels, urine excretion, UA oxidant product allantoin and other clinical parameters were assessed.

Results:

100 patients were enrolled for analysis. sUA in patients with TBI or underwent cerebral tumor surgery started to decline from day 1 after injury or surgery compared to control. This decreasing trend continued from day 3 (143.2±59.3 μmol/L, 188.8±49.4 μmol/L vs 287.3±80.2 μmol/L, p<0.0001) until day 7. No difference in urinary UA excretion was found in the TBI group or cerebral tumor surgery group. Urine allantoin and the allantoin to sUA ratio of the TBI group decreased on day 3 compared with the control group. The structural equation model showed that the sUA level was related to the Glasgow coma score (GCS) (r=0.5383, p<0.0001), suggesting the potential association of UA with consciousness level, as well as serum protein and electrolytes including albumin, calcium and phosphate.

Conclusion:

The sUA was decreased in patients with TBI or underwent cerebral tumor surgery.