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Circadian clock function declines with ageing, which can aggravate ageing‐related diseases such as type 2 diabetes and neurodegenerative disorders. Understanding age‐related changes in the circadian system at a systemic level can contribute to the development of strategies to promote healthy ageing. The goal of this study was to investigate the impact of ageing on 24‐h rhythms in amine metabolites across four tissues in young (2 months of age) and old (22–25 months of age) mice using a targeted metabolomics approach. Liver, plasma, the suprachiasmatic nucleus (SCN; the location of the central circadian clock in the hypothalamus) and the paraventricular nucleus (PVN; a downstream target of the SCN) were collected from young and old mice every 4 h during a 24‐h period (n = 6–7 mice per group). Differential rhythmicity analysis revealed that ageing impacts 24‐h rhythms in the amine metabolome in a tissue‐specific manner. Most profound changes were observed in the liver, in which rhythmicity was lost in 60% of the metabolites in aged mice. Furthermore, we found strong correlations in metabolite levels between the liver and plasma and between the SCN and the PVN in young mice. These correlations were almost completely abolished in old mice. These results indicate that ageing is accompanied by a severe loss of the circadian coordination between tissues and by disturbed rhythmicity of metabolic processes. The tissue‐specific impact of ageing may help to differentiate mechanisms of ageing‐related disorders in the brain versus peripheral tissues and thereby contribute to the development of potential therapies for these disorders. [ABSTRACT FROM AUTHOR]

Trimethylamine N‐oxide (TMAO) is a circulating microbiome‐derived metabolite implicated in the development of atherosclerosis and cardiovascular disease (CVD). We investigated whether plasma levels of TMAO, its precursors (betaine, carnitine, deoxycarnitine, choline), and TMAO‐to‐precursor ratios are associated with clinical outcomes, including CVD and mortality. This was followed by an in‐depth analysis of their genetic, gut microbial, and dietary determinants. The analyses were conducted in five Dutch prospective cohort studies including 7834 individuals. To further investigate association results, Mendelian Randomization (MR) was also explored. We found only plasma choline levels (hazard ratio [HR] 1.17, [95% CI 1.07; 1.28]) and not TMAO to be associated with CVD risk. Our association analyses uncovered 10 genome‐wide significant loci, including novel genomic regions for betaine (6p21.1, 6q25.3), choline (2q34, 5q31.1), and deoxycarnitine (10q21.2, 11p14.2) comprising several metabolic gene associations, for example, CPS1 or PEMT. Furthermore, our analyses uncovered 68 gut microbiota associations, mainly related to TMAO‐to‐precursors ratios and the Ruminococcaceae family, and 16 associations of food groups and metabolites including fish‐TMAO, meat‐carnitine, and plant‐based food‐betaine associations. No significant association was identified by the MR approach. Our analyses provide novel insights into the TMAO pathway, its determinants, and pathophysiological impact on the general population. Highlights: Exploration of microbiome‐related metabolites (trimethylamine N‐oxide [TMAO], choline, betaine, l‐carnitine, and deoxycarnitine) in 7834 participants from five population cohorts.Cardiovascular risk was associated with elevated choline concentrations, but not with TMAO concentrations.Characterization of the genetic architecture behind metabolite concentration variability.Identification of gut microbial taxonomic abundance associated with metabolite's plasma concentration levels.Fish intake is the major dietary driver of TMAO concentrations, and betaine is related to grains and vegetable intake. [ABSTRACT FROM AUTHOR]

The increasing prevalence of IgE‐mediated cow's milk allergy (CMA) in childhood is a worldwide health concern. There is a growing awareness that the gut microbiome (GM) might play an important role in CMA development. Therefore, treatment with probiotics and prebiotics has gained popularity. This systematic review provides an overview of the alterations of the GM, metabolome, and immune response in CMA children and animal models, including post‐treatment modifications. MEDLINE, PubMed, Scopus, and Web of Science were searched for studies on GM in CMA‐diagnosed children, published before 1 March 2023. A total of 21 articles (13 on children and 8 on animal models) were included. The studies suggest that the GM, characterized by an enrichment of the Clostridia class and reductions in the Lactobacillales order and Bifidobacterium genus, is associated with CMA in early life. Additionally, reduced levels of short‐chain fatty acids (SCFAs) and altered amino acid metabolism were reported in CMA children. Commonly used probiotic strains belong to the Bifidobacterium and Lactobacillus genera. However, only Bifidobacterium levels were consistently upregulated after the intervention, while alterations of other bacteria taxa remain inconclusive. These interventions appear to contribute to the restoration of SCFAs and amino acid metabolism balance. Mouse models indicate that these interventions tend to restore the Th2/Th1 balance, increase the Treg response, and/or silence the overall pro‐ and anti‐inflammatory cytokine response. Overall, this systematic review highlights the need for multi‐omics‐related research in CMA children to gain a mechanistic understanding of this disease and to develop effective treatments and preventive strategies. [ABSTRACT FROM AUTHOR]

Objective: Impaired amine metabolism has been associated with the etiology of migraine, that is, why patients continue to get migraine attacks. However, evidence from cerebrospinal fluid (CSF) is lacking. Here, we evaluated individual amine levels, global amine profiles, and amine pathways in CSF and plasma of interictal migraine patients and healthy controls. Methods: CSF and plasma were sampled between 8:30 am and 1:00 pm, randomly and interchangeably over the time span to avoid any diurnal and seasonal influences, from healthy volunteers and interictal migraine patients, matched for age, sex, and sampling time. The study was approved by the local medical ethics committee. Individual amines (n = 31), global amine profiles, and specific amine pathways were analyzed using a validated ultraperformance liquid chromatography mass spectrometry platform. Results: We analyzed n = 99 participants with migraine with aura, n = 98 with migraine without aura, and n = 96 healthy volunteers. Univariate analysis with Bonferroni correction indicated that CSF L‐arginine was reduced in migraine with aura (10.4%, p < 0.001) and without aura (5.0%, p = 0.03). False discovery rate‐corrected CSF L‐phenylalanine was also lower in migraine with aura (6.9%, p = 0.011) and without aura (8.1%, p = 0.001), p = 0.088 after Bonferroni correction. Multivariate analysis revealed that CSF global amine profiles were similar for both types of migraine (p = 0.64), but distinct from controls (p = 0.009). Global profile analyses were similar in plasma. The strongest associated pathways with migraine were related to L‐arginine metabolism. Interpretation: L‐Arginine was decreased in the CSF (but not in plasma) of interictal patients with migraine with or without aura, and associated pathways were altered. This suggests that dysfunction of nitric oxide signaling is involved in susceptibility to getting migraine attacks. ANN NEUROL 2023;93:715–728 [ABSTRACT FROM AUTHOR]

The majority of disease modifying therapies for multiple sclerosis (MS) reduce inflammation, but do no't target remyelination. Development of remyelinating therapies will benefit from a method to quantify myelin kinetics in patients with MS. We labeled myelin in vivo with deuterium, and modeled kinetics of myelin breakdown products β‐galactosylceramide (β‐GalC) and N‐Octadecanoyl‐sulfatide (NO‐Sulf). Five patients with MS received 120 ml 70% D2O daily for 70 days and were compared with six healthy subjects who previously received the same procedure. Mass spectrometry and compartmental modeling were used to quantify the turnover rate of β‐GalC and NO‐Sulf in cerebrospinal fluid (CSF). Turnover rate constants of the fractions of β‐GalC and NO‐Sulf with non‐negligible turnover were 0.00186 and 0.00714, respectively, in both healthy subjects and patients with MS. The turnover half‐life of β‐GalC and NO‐Sulf was calculated as 373 days and 96.5 days, respectively. The effect of MS on the NO‐Sulf (49.4% lower fraction with non‐negligible turnover) was more pronounced compared to the effect on β‐GalC turnover (18.3% lower fraction with non‐negligible turnover). Kinetics of myelin breakdown products in the CSF are different in patients with MS compared with healthy subjects. This may be caused by slower myelin production in these patients, by a higher level of degradation of a more stable component of myelin, or, most likely, by a combination of these two processes. Labeling myelin breakdown products is a useful method that can be used to quantify myelin turnover in patients with progressive MS and can therefore be used in proof‐of‐concept studies with remyelination therapies. [ABSTRACT FROM AUTHOR]

The simultaneous analysis of a broad range of polar ionogenic metabolites using capillary electrophoresis‐mass spectrometry (CE‐MS) can be challenging, as two different analytical methods are often required, that is, one for cations and one for anions. Even though CE‐MS has shown to be an effective method for cationic metabolite profiling, the analysis of small anionic metabolites often results in relatively low sensitivity and poor repeatability. In this work, a novel derivatization strategy based on trimethylmethaneaminophenacetyl bromide was developed to enable CE‐MS analysis of carboxylic acid metabolites using normal CE polarity (i.e., cathode in the outlet) and detection by mass spectrometry in positive ionization mode. Optimization of derivatization conditions was performed using a response surface methodology after which the optimized method (incubation time 50 min, temperature 90°C, and pH 10) was used for the analysis of carboxylic acid metabolites in extracts from HepG2 cells. For selected metabolites, detection limits were down to 8.2 nM, and intraday relative standard deviation values for replicates (n = 3) for peak areas were below 21.5%. Metabolites related to glycolysis, tricarboxylic acid cycle, and anaerobic respiration pathways were quantified in 250,000 cell lysates, and could still be detected in extracts from only 25,000 HepG2 cell lysates (∼70 cell lysates injected). [ABSTRACT FROM AUTHOR]

Objective: Omega-6 and omega-3 oxylipins are known to play a role in inflammation and cardiometabolic diseases in preclinical models. The associations between plasma levels of omega-6 and omega-3 polyunsaturated fatty acid-derived oxylipins and body composition and cardiometabolic risk factors in young adults were assessed.Methods: Body composition, brown adipose tissue, traditional serum cardiometabolic risk factors, inflammatory markers, and a panel of 83 oxylipins were analyzed in 133 young adults (age 22.1[SD 2.2] years, 67% women).Results: Plasma levels of four omega-6 oxylipins (15-HeTrE, 5-HETE, 14,15-EpETrE, and the oxidative stress-derived 8,12-iso-iPF2α -VI) correlated positively with adiposity, prevalence of metabolic syndrome, fatty liver index, and homeostatic model assessment of insulin resistance index and lipid parameters. By contrast, the plasma levels of three omega-3 oxylipins (14,15-DiHETE, 17,18-DiHETE, and 19,20-DiHDPA) were negatively correlated with adiposity, prevalence of metabolic syndrome, fatty liver index, homeostatic model assessment of insulin resistance index, and lipid parameters. The panel of seven oxylipins predicted adiposity better than traditional inflammatory markers such as interferon gamma or tumor necrosis factor-alpha. Pathway analyses revealed that individuals with obesity had higher plasma levels of omega-6 and lower plasma levels of omega-3 oxylipins than normal-weight individuals.Conclusion: Plasma levels of seven omega-6 and omega-3 oxylipins may have utility as early markers of cardiometabolic risk in young adults. [ABSTRACT FROM AUTHOR]

A limited understanding of intersubject and intrasubject variability hampers effective biomarker translation from in vitro/in vivo studies to clinical trials and clinical decision support. Specifically, variability of biomolecule concentration can play an important role in interpretation, power analysis, and sampling time designation. In the present study, a wide range of 749 plasma metabolites, 62 urine biogenic amines, and 1,263 plasma proteins were analyzed in 10 healthy male volunteers measured repeatedly during 12 hours under tightly controlled conditions. Three variability components in relative concentration data are determined using linear mixed models: between (intersubject), time (intrasubject), and noise (intrasubject). Biomolecules such as 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropanoate, platelet‐derived growth factor C, and cathepsin D with low noise potentially detect changing conditions within a person. If also the between component is low, biomolecules can easier differentiate conditions between persons, for example cathepsin D, CD27 antigen, and prolylglycine. Variability over time does not necessarily inhibit translatability, but requires choosing sampling times carefully. [ABSTRACT FROM AUTHOR]

Background: Rheumatoid arthritis (RA) is a complex, chronic autoimmune disease characterized by various inflammatory symptoms, including joint swelling, joint pain, and both structural and functional joint damage. The most commonly used animal model for studying RA is mice with collagen‐induced arthritis (CIA); the wide use of this model is due primarily to many similarities with RA in human patients. Metabolomics is used increasingly in biological studies for diagnosing disease and for predicting and evaluating drug interventions, as a large number of disease‐associated metabolites can be analyzed and interpreted from a biological perspective. Aim: To profile free amino acids and their biogenic metabolites in CIA mice plasma. Method: Ultra‐high‐performance liquid chromatography/tandem mass spectrometry coupled with multiple reaction monitoring (MRM) was used for metabolomics study. Results: Profile of 45 amine metabolites, including free amino acids and their biogenic metabolites in plasma was obtained from CIA mice. We found that the plasma levels of 20 amine metabolites were significantly decreased in the CIA group. Conclusion: The results suggest that a disordered amine response is linked to RA‐associated muscle wasting and energy expenditure. [ABSTRACT FROM AUTHOR]

Carboxylesterase 1 (CES1) metabolizes methylphenidate and other drugs. CES1 gene variation only partially explains pharmacokinetic (PK) variability. Biomarkers predicting the PKs of drugs metabolized by CES1 are needed. We identified lipids in plasma from 44 healthy subjects that correlated with CES1 activity as determined by PK parameters of methylphenidate including a ceramide (q value = 0.001) and a phosphatidylcholine (q value = 0.005). Carriers of the CES1 143E allele had decreased methylphenidate metabolism and altered concentration of this phosphatidylcholine (q value = 0.040) and several high polyunsaturated fatty acid lipids (PUFAs). The half‐maximal inhibitory concentration (IC50) values of chenodeoxycholate and taurocholate were 13.55 and 19.51 μM, respectively, consistent with a physiological significance. In silico analysis suggested that bile acid inhibition of CES1 involved both binding to the active and superficial sites of the enzyme. We initiated identification of metabolites predicting PKs of drugs metabolized by CES1 and suggest lipids to regulate or be regulated by this enzyme. [ABSTRACT FROM AUTHOR]

Objective: The study aimed to investigate whether markers of endocannabinoid signaling differed between men with overweight of South Asian and white Caucasian descent.Methods: We included South Asian (n = 10) and white Caucasian (n = 10) men with overweight and prediabetes aged 35 to 50 years. Plasma samples were analyzed for endocannabinoids, their congeners, and lipids. In white adipose tissue (WAT) and skeletal muscle biopsies, mRNA expression of genes involved in the endocannabinoid system (ECS) was assessed using quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Fasting lipid oxidation and glucose oxidation were determined with indirect calorimetry.Results: Compared to white Caucasians, South Asians had higher levels of plasma 2-linoleoyl glycerol (P < 0.01) and N-linoleoylethanolamine (P < 0.05). Interestingly, in skeletal muscle of South Asians, expression of cannabinoid receptors CB1 and CB2 was 10-fold lower (P < 0.001) and that of the endocannabinoid degradation enzyme fatty acid amide hydrolase 2 (FAAH2) was 5-fold lower (P < 0.001) compared to white Caucasians. Expression of genes involved in the ECS in WAT were not different between the two ethnicities. After pooling of both ethnicities, plasma 2-arachidonoylglycerol (2-AG) positively correlated with plasma triglycerides (R = 0.77, P < 0.001) and lipid oxidation (R = 0.55, P < 0.05).Conclusions: South Asian men with overweight have higher plasma 2-linoleoyl glycerol and N-linoleoylethanolamine levels and lower expression of CB receptors and the endocannabinoid degradation enzyme FAAH2 in skeletal muscle compared to white Caucasians. [ABSTRACT FROM AUTHOR]

Oxylipins play important roles in various biological processes and are considered as mediators of inflammation for a wide range of diseases such as rheumatoid arthritis (RA). The purpose of this research was to study differences in oxylipin levels between a widely used collagen induced arthritis (CIA) mice model and healthy control (Ctrl) mice. DBA/1J male mice (age: 6-7 weeks) were selected and randomly divided into two groups, namely, a CIA and a Ctrl group. The CIA mice were injected intraperitoneally (i.p.) with the joint cartilage component collagen type II (CII) and an adjuvant injection of lipopolysaccharide (LPS). Oxylipin metabolites were extracted from plasma for each individual sample using solid phase extraction (SPE) and were detected with high performance liquid chromatography/tandem mass spectrometry (HPLC-ESI-MS/MS), using dynamic multiple reaction monitoring (dMRM). Both univariate and multivariate statistical analyses were applied. The results in univariate Student’s t-test revealed 10 significantly up- or downregulated oxylipins in CIA mice, which were supplemented by another 6 additional oxylipins, contributing to group clustering upon multivariate analysis. The dysregulation of these oxylipins revealed the presence of ROS-generated oxylipins and an increase of inflammation in CIA mice. The results also suggested that the collagen induced arthritis might associate with dysregulation of apoptosis, possibly inhibited by activated NF-κB because of insufficient PPAR-γ ligands. [ABSTRACT FROM AUTHOR]

Abstract: The establishment of symbiosis between leguminous plants and rhizobial bacteria requires rapid metabolic changes in both partners. We utilized untargeted quantitative mass spectrometry to perform metabolomic profiling of small molecules in extracts of the model legume Medicago truncatula treated with rhizobial Nod factors. One metabolite closely resembling the 9(R)-HODE class of oxylipins reproducibly showed a decrease in concentration within the first hour of in planta nod factor treatment. Oxylipins are precursors of the jasmonic acid biosynthetic pathway and we showed that both this metabolite and jasmonic acid inhibit Nod factor signaling. Since, oxylipins have been implicated as antimicrobial compounds produced by plants, these observations suggest that the oxylipin pathway may play multiple roles in facilitating Nod factor signaling during the early stages of symbiosis. [Copyright &y& Elsevier]

ABSTRACT Sample collection can significantly affect lipid concentration measurements in cell line panels, concealing intrinsic differences between cancer subtypes. Most quality control steps in lipidomic data analysis focus on controlling technical variation. Correcting for the total amount of biological material remains an additional challenge for cell line panels. Here, we investigated how we can normalize lipidomic data acquired from multiple cell lines to correct for differences in sample biomass. We studied how commonly used data normalization and transformation strategies influence the resulting lipid data distributions. We compared normalization by biological properties including cell count and total protein concentration, to statistical and data‐based approaches, such as median, mean, or probabilistic quotient‐based normalization. We used intraclass correlations to estimate how normalization influenced the similarity between replicates. Normalizing lipidomic data by cell count improved the similarity between replicates but only for cell lines with similar morphologies. When comparing cell line panels with diverse morphologies neither cell count nor protein concentration was sufficient to increase the similarity of lipid abundances between cell line replicates. Data‐based normalizations increased these similarities but resulted in a bias towards the large and variable lipid class of triglycerides. These artifacts are reduced by normalizing for the abundance of only structural lipids. We conclude that there is a delicate balance between improving the similarity between replicates and avoiding artifacts in lipidomic data and emphasize the importance of an appropriate normalization strategy in studying biological phenomena using lipidomics. [ABSTRACT FROM AUTHOR]