Comparison of Adiposomal Lipids between Obese and Non-Obese Individuals

Our recent findings revealed that human adipose tissues (AT)-derived extracellular vesicles (adiposomes) vary in cargo among obese and lean individuals. The main objective of this study was to investigate the adiposomal lipid profiles and their correlation with cardiometabolic risk factors. AT samples were collected from obese subjects and lean controls and analyzed for their characteristics and lipid content. In addition, we measured the correlation between adiposomal lipid profiles and body composition, glucose and lipid metabolic profiles, brachial artery vasoreactivity, AT arteriolar flow-induced dilation, and circulating markers such as IL-6, C-reactive protein, and nitric oxide (NO). Compared to lean controls, adiposomes isolated from obese subjects were higher in number after normalization to AT volume. The two major lipid classes differentially expressed were lysophosphatidylcholine/phosphatidylcholine (LPC/PC) and ceramides (Cer). All lipids in the LPC/PC class were several-fold lower in adiposomes from obese subjects compared to lean controls, on top of which were PC 18:2, PC 18:1, and PC 36:3. Most ceramides were markedly upregulated in the obese group, especially Cer d37:0, Cer d18:0, and Cer d39:0. Regression analyses revealed associations between adiposomal lipid profiles and several cardiometabolic risk factors such as body mass index (BMI), fat percentage, insulin resistance, arteriolar and brachial artery vasoreactivity, NO bioavailability, and high-density lipoproteins (HDL-C). We conclude that the ability of adiposomes from obese subjects to disrupt cardiometabolic function could be partly attributed to the dysregulated lipid cargo.

Integrated Multi-Omics Analysis of Cerebrospinal Fluid in Postoperative Delirium

Preoperative risk biomarkers for delirium may aid in identifying high-risk patients and developing intervention therapies, which would minimize the health and economic burden of postoperative delirium. Previous studies have typically used single omics approaches to identify such biomarkers. Preoperative cerebrospinal fluid (CSF) from the Healthier Postoperative Recovery study of adults ≥ 63 years old undergoing elective major orthopedic surgery was used in a matched pair delirium case-no delirium control design. We performed metabolomics and lipidomics, which were combined with our previously reported proteomics results on the same samples. Differential expression, clustering, classification, and systems biology analyses were applied to individual and combined omics datasets. Probabilistic graph models were used to identify an integrated multi-omics interaction network, which included clusters of heterogeneous omics interactions among lipids, metabolites, and proteins. The combined multi-omics signature of 25 molecules attained an AUC of 0.96 [95% CI: 0.85-1.00], showing improvement over individual omics-based classification. We conclude that multi-omics integration of preoperative CSF identifies potential risk markers for delirium and generates new insights into the complex pathways associated with delirium. With future validation, this hypotheses-generating study may serve to build robust biomarkers for delirium and improve our understanding of its pathophysiology.

Circulating perturbation of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) is associated to cardiac remodeling and NLRP3 inflammasome in cardiovascular patients with insulin resistance risk

Lipidome perturbation occurring during meta-inflammation is associated to left ventricle (LV) remodeling though the activation of the NLRP3 inflammasome, a key regulator of chronic inflammation in obesity-related disorders. Little is known about phosphatidylcholine (PC) and phosphatidylethanolamine (PE) as DAMP-induced NLRP3 inflammasome. Our study is aimed to evaluate if a systemic reduction of PC/PE molar ratio can affect NLRP3 plasma levels in cardiovascular disease (CVD) patients with insulin resistance (IR) risk. Forty patients from IRCCS Policlinico San Donato were enrolled, and their blood samples were drawn before heart surgery. LV geometry measurements were evaluated by echocardiography and clinical data associated to IR risk were collected. PC and PE were quantified by ESI-MS/MS. Circulating NLRP3 was quantified by an ELISA assay. Our results have shown that CVD patients with IR risk presented systemic lipid impairment of PC and PE species and their ratio in plasma was inversely associated to NLRP3 levels. Interestingly, CVD patients with IR risk presented LV changes directly associated to increased levels of NLRP3 and a decrease in PC/PE ratio in plasma, highlighting the systemic effect of meta-inflammation in cardiac response. In summary, PC and PE can be considered bioactive mediators associated to both the NLRP3 and LV changes in CVD patients with IR risk.

Mitochondrial ALDH2 improves ß-cell survival and function against doxorubicin-induced apoptosis by targeting CK2 signaling

AIMS

The aim of this study was to better understand how the chemotherapy drug doxorubicin contributes to the development of β-cell dysfunction and to explore its relationship with mitochondrial aldehyde dehydrogenase-2 (ALDH2).

MATERIALS AND METHODS

In order to investigate this hypothesis, doxorubicin was administered to INS-1 cells, a rat insulinoma cell line, either with or without several target protein activators and inhibitors. ALDH2 activity was detected with a commercial kit and protein levels were determined with western blot. Mitochondrial ROS, membrane potential, and lipid ROS were determined by commercial fluorescent probes. The cell viability was measured by CCK-assay.

RESULTS

Exposure of INS-1 cells to doxorubicin decreased active insulin signaling resulting in elevated ALDH2 degradation, compared with control cells by the induction of acid sphingomyelinase mediated ceramide induction. Further, ceramide induction potentiated doxorubicin induced mitochondrial dysfunction. Treatment with the ALDH2 agonist, ALDA1, blocked doxorubicin-induced acid sphingomyelinase activation which significantly blocked ceramide induction and mitochondrial dysfunction mediated cell death. Treatment with the ALDH2 agonist, ALDA1, stimulated casein kinase-2 (CK2) mediated insulin signaling activation. CK2 silencing neutralized the function of ALDH2 in the doxorubicin treated INS-1 cells.

CONCLUSIONS

Mitochondrial ALDH2 activation could inhibit the progression of doxorubicin induced pancreatic β-cell dysfunction by inhibiting the acid sphingomyelinase induction of ceramide, by regulating the activation of CK2 signaling. Our research lays the foundation of ALDH2 activation as a therapeutic target for the precise treatment of chemotherapy drug induced β-cell dysfunction.

Lipidomes in Cadaveric Decomposition and Determination of the Postmortem Interval: A Systematic Review

Lipids are a large group of natural compounds, together with proteins and carbohydrates, and are essential for various processes in the body. After death, the organism's tissues undergo a series of reactions that generate changes in some molecules, including lipids. This means that determining the lipid change profile can be beneficial in estimating the postmortem interval (PMI). These changes can also help determine burial sites and advance the localization of graves. The aim was to explore and analyze the decomposition process of corpses, focusing on the transformation of lipids, especially triglycerides (TGs) and fatty acids (FAs), and the possible application of these compounds as markers to estimate PMI and detect burial sites. A systematic review of 24 scientific articles from the last 23 years (2000-2023) was conducted. The results show that membrane glycerophospholipids (such as phosphatidylcholine and phosphatidylglycerol, among others) are the most studied, and the most promising results are obtained, with decreasing patterns as PMI varies. Fatty acids (FAs) are also identified as potential biomarkers owing to the variations in their postmortem concentration. An increase in saturated fatty acids (SFAs), such as stearic acid and palmitic acid, and a decrease in unsaturated fatty acids (UFAs), such as oleic acid and linoleic acid, were observed. The importance of intrinsic and extrinsic factors in decomposition is also observed. Finally, as for the burial sites, the presence of fatty acids and some sterols in burial areas of animal and human remains can be verified. In conclusion, glycerophospholipids and fatty acids are good markers for estimating PMI. It has been observed that there are still no equations for estimating the PMI that can be applied to forensic practice, as intrinsic and extrinsic factors are seen to play a vital role in the decomposition process. As for determining burial sites, the importance of soil and textile samples has been demonstrated, showing a direct relationship between saturated fatty acids, hydroxy fatty acids, and some sterols with decomposing remains.

Lipid Profiling Reveals Lipidomic Signatures of Weight Loss Interventions

Obesity is an epidemic all around the world. Weight loss interventions that are effective differ from each other with regard to various lipidomic responses. Here, we aimed to find lipidomic biomarkers that are related to beneficial changes in weight loss. We adopted an untargeted liquid chromatography with tandem mass spectrometry (LC-MS/MS) method to measure 953 lipid species for Exercise (exercise intervention cohort, N = 25), 1388 lipid species for LSG (laparoscopic sleeve gastrectomy cohort, N = 36), and 886 lipid species for Cushing (surgical removal of the ACTH-secreting pituitary adenomas cohort, N = 25). Overall, the total diacylglycerol (DG), triacylglycerol (TG), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and sphingomyelin (SM) levels were associated with changes in BMI, glycated hemoglobin (HbA1c), triglyceride, and total cholesterol according to weight loss interventions. We found that 73 lipid species changed among the three weight loss interventions. We screened 13 lipid species with better predictive accuracy in diagnosing weight loss situations in either Exercise, LSG, or Cushing cohorts (AUROC > 0.7). More importantly, we identified three phosphatidylcholine (PC) lipid species, PC (14:0_18:3), PC (31:1), and PC (32:2) that were significantly associated with weight change in three studies. Our results highlight potential lipidomic biomarkers that, in the future, could be used in personalized approaches involving weight loss interventions.

Almond Consumption for 8 Weeks Altered Host and Microbial Metabolism in Comparison to a Control Snack in Young Adults

Almond consumption can improve cardiometabolic (CM) health. However, the mechanisms underlying those benefits are not well characterized. This study explored the effects of consuming a snack of almonds vs. crackers for 8 weeks on changes in metabolomic profiles in young adults (clinicaltrials.gov ID: NCT03084003).

Participants (n = 73, age: 18-19 years, BMI: 18-41 kg/m2) were randomly assigned to consume either almonds (2 oz/d, n = 38) or an isocaloric control snack of graham crackers (325 kcal/d, n = 35) daily for 8 weeks. Blood samples were collected at baseline prior to and at 4 and 8 weeks after the intervention. Metabolite abundances in the serum were quantified by hydrophilic interaction chromatography quadrupole (Q) time-of-flight (TOF) mass spectrometry (MS/MS), gas chromatography (GC) TOF MS, CSH-ESI (electrospray) QTOF MS/MS, and targeted analyses for free PUFAs, total fatty acids, oxylipins and endocannabinoids. Linear mixed model analyses with baseline-adjustment were conducted, and those results were used for enrichment and network analyses. Microbial community pathway predictions from 16S rRNA sequencing of fecal samples was done using PICRUST2.

Almond consumption enriched unsaturated triglycerides, unsaturated phosphatidylcholines, saturated and unsaturated lysophosphatidylcholines, tricarboxylic acids, and tocopherol clusters (p < 0.05). Targeted analyses reveal lower levels of omega-3 total fatty acids (TFAs) overall in the almond group compared to the cracker group (p < 0.05). Microbial amino acid biosynthesis, and amino sugar and nucleotide sugar metabolism pathways were also differentially enriched at the end of the intervention (p < 0.05).

The study demonstrates the differential effects of almonds on host tocopherol, lipid, and TCA cycle metabolism with potential changes in microbial metabolism, which may interact with host metabolism to facilitate the CM benefits.

Lipidomics in gestational diabetes mellitus

PURPOSE OF REVIEW

Epidemiological and mechanistic studies have reported relationships between blood lipids, mostly measured by traditional method in clinical settings, and gestational diabetes mellitus (GDM). Recent advances of high-throughput lipidomics techniques have made available more comprehensive lipid profiling in biological samples. This review aims to summarize evidence from prospective studies in assessing relations between blood lipids and GDM, and discuss potential underlying mechanisms.

RECENT FINDINGS

Mass spectrometry and nuclear magnetic resonance spectroscopy-based analytical platforms are extensively used in lipidomics research. Epidemiological studies have identified multiple novel lipidomic biomarkers that are associated with risk of GDM, such as certain types of fatty acids, glycerolipids, glycerophospholipids, sphingolipids, cholesterol, and lipoproteins. However, the findings are inconclusive mainly due to the heterogeneities in study populations, sample sizes, and analytical platforms. Mechanistic evidence indicates that abnormal lipid metabolism may be involved in the pathogenesis of GDM by impairing pancreatic β-cells and inducing insulin resistance through several etiologic pathways, such as inflammation and oxidative stress.

SUMMARY

Lipidomics is a powerful tool to study pathogenesis and biomarkers for GDM. Lipidomic biomarkers and pathways could help to identify women at high risk for GDM and could be potential targets for early prevention and intervention of GDM.

Distinctive serum lipidomic profile of IVIG-resistant Kawasaki disease children before and after treatment

Kawasaki Disease (KD) is an acute inflammatory disorder associated with systemic vasculitis. Intravenous immunoglobulin (IVIG) is an effective therapy for KD, yet, about 20% of cases show IVIG resistance with persistent inflammation. The lipid profile in IVIG-resistant KD patients and the relationship between lipid characteristics and IVIG resistance remain unknown. In this study, serum samples from twenty KD patients with different IVIG responses (sensitive, intermediate, or resistant) were collected both before and after treatment, and lipidomic analysis was performed using high-performance liquid chromatography-mass spectrometry. As a result, before treatment, six lipid species were found as the most variant features, in which all the top decreased lipids in the IVIG-resistant group were lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE), suggesting the potential to be IVIG-resistant markers in pretreatment diagnosis. During treatment, lipidomic changes showed a weaker response in the IVIG-resistant group. After treatment, LPC and LPE species exhibited lower in the IVIG-resistant group and negative correlation with the inflammatory markers, indicating that the unique metabolism may occur among IVIG-responsiveness. These results might contribute to diagnosing IVIG-resistant patients more accurately for alternative therapy and to a better understanding of how lipid metabolism is associated with IVIG sensitiveness/resistance in KD.

Action mechanism of hypoglycemic principle 9-(R)-HODE isolated from cortex lycii based on a metabolomics approach

The 9-(R)-HODE is an active compound isolated from cortex lycii that showed significant hypoglycemic effects in our previous in vitro study. In this study, 9-(R)-HODE’s in vivo hypoglycemic activity and effect on alleviating diabetic complications, together with its molecular mechanism, was investigated using a metabolomics approach. The monitored regulation on dynamic fasting blood glucose, postprandial glucose, body weight, biochemical parameters and histopathological analysis confirmed the hypoglycemic activity and attenuation effect, i.e., renal lesions, of 9-(R)-HODE. Subsequent metabolomic studies indicated that 9-(R)-HODE induced metabolomic alterations primarily by affecting the levels of amino acids, organic acids, alcohols and amines related to amino acid metabolism, glucose metabolism and energy metabolism. By mediating the related metabolism or single molecules related to insulin resistance, e.g., kynurenine, myo-inositol and the branched chain amino acids leucine, isoleucine and valine, 9-(R)-HODE achieved its therapeutic effect. Moreover, the mediation of kynurenine displayed a systematic effect on the liver, kidney, muscle, plasma and faeces. Lipidomic studies revealed that 9-(R)-HODE could reverse the lipid metabolism disorder in diabetic mice mainly by regulating phosphatidylinositols, lysophosphatidylcholines, lysophosphatidylcholines, phosphatidylserine, phosphatidylglycerols, lysophosphatidylglycerols and triglycerides in both tissues and plasma. Treatment with 9-(R)-HODE significantly modified the structure and composition of the gut microbiota. The SCFA-producing bacteria, including Rikenellaceae and Lactobacillaceae at the family level and Ruminiclostridium 6, Ruminococcaceae UCG 014, Mucispirillum, Lactobacillus, Alistipes and Roseburia at the genus level, were increased by 9-(R)-HODE treatment. These results were consistent with the increased SCFA levels in both the colon content and plasma of diabetic mice treated with 9-(R)-HODE. The tissue DESI‒MSI analysis strongly confirmed the validity of the metabolomics approach in illustrating the hypoglycemic and diabetic complications-alleviation effect of 9-(R)-HODE. The significant upregulation of liver glycogen in diabetic mice by 9-(R)-HODE treatment validated the interpretation of the metabolic pathways related to glycogen synthesis in the integrated pathway network. Altogether, 9-(R)-HODE has the potential to be further developed as a promising candidate for the treatment of diabetes.

Metabolic signatures in human follicular fluid identify lysophosphatidylcholine as a predictor of follicular development

In order to investigate the metabolic characteristics of human follicular fluid (FF) and to reveal potential metabolic predictors of follicular development (FD) with clinical implications, we analyzed a total of 452 samples based on a two-stage study design. In the first stage, FF samples from both large follicles (LFs) and matched-small follicles (SFs) of 26 participants were analyzed with wide-spectrum targeted metabolomics. The metabolic signatures were described by multi-omics integration technology including metabolomic data and transcriptomic data. In the second stage, the potential biomarkers of FD were verified using enzyme-linked immunoassay with FF and blood serum from an independent 200 participants. We describe the FF metabolic signatures from ovarian follicles of different developmental stages. Lysophosphatidylcholine (LPC) can be used as a biomarker of FD and ovarian sensitivity, advancing the knowledge of metabolic regulation during FD and offering potential detection and therapeutic targets for follicle and oocyte health improvements in humans.

A two-stage metabolomic analysis for human follicular fluid characteristics and predictors of follicular development yields metabolic signatures and proposes lysophosphatidylcholine (LPC) as a biomarker for follicular development.

Longitudinal associations of pre-pregnancy BMI and gestational weight gain with maternal urinary metabolites: an NYU CHES study

BACKGROUND/OBJECTIVES

Excessive gestational weight gain (GWG) and pre-pregnancy obesity affect a significant portion of the US pregnant population and are linked with negative maternal and child health outcomes. The objective of this study was to explore associations of pre-pregnancy body mass index (pBMI) and GWG with longitudinally measured maternal urinary metabolites throughout pregnancy.

SUBJECTS/METHODS

Among 652 participants in the New York University Children's Health and Environment Study, a longitudinal pregnancy cohort, targeted metabolomics were measured in serially collected urine samples throughout pregnancy. Metabolites were measured at median 10 (T1), 21 (T2), and 29 (T3) weeks gestation using the Biocrates AbsoluteIDQ® p180 Urine Extension kit. Acylcarnitine, amino acid, biogenic amine, phosphatidylcholine, lysophosphatidylcholine, sphingolipid, and sugar levels were quantified. Pregnant people 18 years or older, without type 1 or 2 diabetes and with singleton live births and valid pBMI and metabolomics data were included. GWG and pBMI were calculated using weight and height data obtained from electronic health records. Linear mixed effects models with interactions with time were fit to determine the gestational age-specific associations of categorical pBMI and continuous interval-specific GWG with urinary metabolites. All analyses were corrected for false discovery rate.

RESULTS

Participants with obesity had lower long-chain acylcarnitine levels throughout pregnancy and lower phosphatidylcholine and glucogenic amino acids and higher phenylethylamine concentrations in T2 and T3 compared with participants with normal/underweight pBMI. GWG was associated with taurine in T2 and T3 and C5 acylcarnitine species, C5:1, C5-DC, and C5-M-DC, in T2.

CONCLUSIONS

pBMI and GWG were associated with the metabolic environment of pregnant individuals, particularly in relation to mid-pregnancy. These results highlight the importance of both preconception and prenatal maternal health.

Circulating metabolite profile in young adulthood identifies long-term diabetes susceptibility: the Coronary Artery Risk Development in Young Adults (CARDIA) study

AIMS/HYPOTHESIS

The aim of this work was to define metabolic correlates and pathways of diabetes pathogenesis in young adults during a subclinical latent phase of diabetes development.

METHODS

We studied 2083 young adults of Black and White ethnicity in the prospective observational cohort Coronary Artery Risk Development in Young Adults (CARDIA) study (mean ± SD age 32.1 ± 3.6 years; 43.9% women; 42.7% Black; mean ± SD BMI 25.6 ± 4.9 kg/m2) and 1797 Framingham Heart Study (FHS) participants (mean ± SD age 54.7 ± 9.7 years; 52.1% women; mean ± SD BMI 27.4 ± 4.8 kg/m2), examining the association of comprehensive metabolite profiles with endophenotypes of diabetes susceptibility (adipose and muscle tissue phenotypes and systemic inflammation). Statistical learning techniques and Cox regression were used to identify metabolite signatures of incident diabetes over a median of nearly two decades of follow-up across both cohorts.

RESULTS

We identified known and novel metabolites associated with endophenotypes that delineate the complex pathophysiological architecture of diabetes, spanning mechanisms of muscle insulin resistance, inflammatory lipid signalling and beta cell metabolism (e.g. bioactive lipids, amino acids and microbe- and diet-derived metabolites). Integrating endophenotypes of diabetes susceptibility with the metabolome generated two multi-parametric metabolite scores, one of which (a proinflammatory adiposity score) was associated with incident diabetes across the life course in participants from both the CARDIA study (young adults; HR in a fully adjusted model 2.10 [95% CI 1.72, 2.55], p<0.0001) and FHS (middle-aged and older adults; HR 1.33 [95% CI 1.14, 1.56], p=0.0004). A metabolite score based on the outcome of diabetes was strongly related to diabetes in CARDIA study participants (fully adjusted HR 3.41 [95% CI 2.85, 4.07], p<0.0001) but not in the older FHS population (HR 1.15 [95% CI 0.99, 1.33], p=0.07).

CONCLUSIONS/INTERPRETATION

Selected metabolic abnormalities in young adulthood identify individuals with heightened diabetes risk independent of race, sex and traditional diabetes risk factors. These signatures replicate across the life course.

LA-ICP-MS and MALDI-MS image registration for correlating nanomaterial biodistributions and their biochemical effects

Laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) imaging and matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) are complementary methods that measure distributions of elements and biomolecules in tissue sections. Quantitative correlations of the information provided by these two imaging modalities requires that the datasets be registered in the same coordinate system, allowing for pixel-by-pixel comparisons. We describe here a computational workflow written in Python that accomplishes this registration, even for adjacent tissue sections, with accuracies within ±50 μm. The value of this registration process is demonstrated by correlating images of tissue sections from mice injected with gold nanomaterial drug delivery systems. Quantitative correlations of the nanomaterial delivery vehicle, as detected by LA-ICP-MS imaging, with biochemical changes, as detected by MALDI-MSI, provide deeper insight into how nanomaterial delivery systems influence lipid biochemistry in tissues. Moreover, the registration process allows the more precise images associated with LA-ICP-MS imaging to be leveraged to achieve improved segmentation in MALDI-MS images, resulting in the identification of lipids that are most associated with different sub-organ regions in tissues.

Lipidomic profiling reveals distinct differences in plasma lipid composition in overweight or obese adolescent students

INTRODUCTION

The relationship between dyslipidemia and obesity has been widely reported, but the global lipid profiles associated with the development of obesity still need to be clarified. An investigation into the association between the lipidomic plasma profile and adolescent obesity may provide new insights into the development of obesity.

METHODS

Mass spectrometry coupled with liquid chromatography was applied to detect the global lipidome in the fasting plasma from 90 Chinese adolescents, including 34 obese adolescents, 26 overweight adolescents, and 30 adolescents with a normal body mass index (BMI). All participants underwent anthropometric measurements by using InBody. Clinical biochemical indicators were measured by Cobas Elecsys.

RESULTS

Both qualitative and quantitative analyses revealed a gradual change in plasma lipid features among obese students, exhibiting characteristics close to overweight students, but differing significantly from normal students. Compared with normal and overweight students, levels of triglyceride (TG), 18-hydroxycortisol, isohumulinone A, and 11-dihydro-12-norneoquassin were up-regulated in the obese group, while phosphatidylcholine (PC), phosphatidylethanolamine (PE), lysoPC (LPC), lysoPE (LPE), and phosphatidylinositol (PI) were significantly down-regulated in the obese group. Then, we conducted Venn diagrams and selected 8 significant metabolites from the 3 paired comparisons. Most of the selected features were significantly correlated with the anthropometric measurements.

CONCLUSIONS

This study demonstrated evidence for a relationship between the eight significant metabolites with obese adolescents. These lipid features may provide a basis for evaluating risk and monitoring the development of obesity.

Lipid changes in extrapulmonary organs and serum of rats after chronic exposure to ambient fine particulate matter

Fine particulate matter (PM_2.5) is able to pass through the respiratory barrier to enter the circulatory system and can consequently spread to the whole body to cause toxicity. Although our previous studies have revealed significantly altered levels of phosphorylcholine-containing lipids in the lungs of rats after chronic inhalation exposure to PM_2.5, the effects of PM_2.5 on phosphorylcholine-containing lipids in the extrapulmonary organs have not yet been elucidated. In this study, we examined the lipid effects of chronic PM_2.5 exposure on various organs and serum by using a rat inhalation model followed by a mass spectrometry-based lipidomic approach. Male Sprague-Dawley rats were continuously exposed at the whole body level to nonfiltered and nonconcentrated ambient air from the outside environment of Taipei city for 8 months, while the control rats inhaled filtered air simultaneously. After exposure, serum samples and various organs, including the testis, pancreas, heart, liver, kidney, spleen, and epididymis, were collected for lipid extraction and analysis to examine the changes in phosphorylcholine-containing lipids after exposure. The results from the partial least squares discriminant analysis models demonstrated that the lipid profiles in the PM_2.5 exposure group were different from those in the control group in the rat testis, pancreas, heart, liver, kidney and serum. The greatest PM_2.5-induced lipid effects were observed in the testes. Decreased lyso-phosphatidylcholines (PCs) as well as increased unsaturated diacyl-PCs and sphingomyelins in the testes may be related to maintaining the membrane integrity of spermatozoa, antioxidation, and cell signaling. Additionally, our results showed that decreased PC(16:0/18:1) was observed in both the serum and testes. In conclusion, exposure to chronic environmental concentrations of PM_2.5 caused lipid perturbation, especially in the testes of rats. This study highlighted the susceptibility of the testes and suggested possible molecular events for future study.

Nanodelivery vehicles induce remote biochemical changes in vivo

Nanomaterial-based platforms are promising vehicles for the controlled delivery of therapeutics. For these systems to be both efficacious and safe, it is essential to understand where the carriers accumulate and to reveal the site-specific biochemical effects they produce in vivo. Here, a dual-mode mass spectrometry imaging (MSI) method is used to evaluate the distributions and biochemical effects of anti-TNF-α nanoparticle stabilized capsules (NPSCs) in mice. It is found that most of the anticipated biochemical changes occur in sub-organ regions that are separate from where the nanomaterials accumulate. In particular, TNF-α-specific lipid biomarker levels change in immune cell-rich regions of organs, while the NPSCs accumulate in spatially isolated filtration regions. Biochemical changes that are associated with the nanomaterials themselves are also observed, demonstrating the power of matrix-assisted laser desorption/ionization (MALDI) MSI to reveal markers indicating possible off-target effects of the delivery agent. This comprehensive assessment using MSI provides spatial context of nanomaterial distributions and efficacy that cannot be easily achieved with other imaging methods, demonstrating the power of MSI to evaluate both expected and unexpected outcomes associated with complex therapeutic delivery systems.

Metabolic profile distinguishes laminitis-susceptible and -resistant ponies before and after feeding a high sugar diet

Background

Insulin dysregulation (ID) is a key risk factor for equine endocrinopathic laminitis, but in many cases ID can only be assessed accurately using dynamic tests. The identification of other biomarkers could provide an alternative or adjunct diagnostic method, to allow early intervention before laminitis develops. The present study characterised the metabolome of ponies with varying degrees of ID using basal and postprandial plasma samples obtained during a previous study, which examined the predictive power of blood insulin levels for the development of laminitis, in ponies fed a high-sugar diet. Samples from 10 pre-laminitic (PL – subsequently developed laminitis) and 10 non-laminitic (NL – did not develop laminitis) ponies were used in a targeted metabolomic assay. Differential concentration and pathway analysis were performed using linear models and global tests.

Results

Significant changes in the concentration of six glycerophospholipids (adj. P ≤ 0.024) and a global enrichment of the glucose-alanine cycle (adj. P = 0.048) were found to characterise the response of PL ponies to the high-sugar diet. In contrast, the metabolites showed no significant association with the presence or absence of pituitary pars intermedia dysfunction in all ponies.

Conclusions

The present results suggest that ID and laminitis risk are associated with alterations in the glycerophospholipid and glucose metabolism, which may help understand and explain some molecular processes causing or resulting from these conditions. The prognostic value of the identified biomarkers for laminitis remains to be investigated in further metabolomic trials in horses and ponies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02763-7.

Metabolic impact of weight variations in Icelandic horses

Background

Insulin dysregulation (ID) is an equine endocrine disorder, which is often accompanied by obesity and various metabolic perturbations. The relationship between weight variations and fluctuations of the insulin response to oral glucose tests (OGT) as well as the metabolic impact of ID have been described previously. The present study seeks to characterize the concomitant metabolic impact of variations in the insulin response and bodyweight during repeated OGTs using a metabolomics approach.

Methods

Nineteen Icelandic horses were subjected to five OGTs over one year and their bodyweight, insulin and metabolic response were monitored. Analysis of metabolite concentrations depending on time (during the OGT), relative bodyweight (rWeight; defined as the bodyweight at one OGT divided by the mean bodyweight across all OGTs) and relative insulin response (rAUC_ins; defined accordingly from the area under the insulin curve during OGT) was performed using linear models. Additionally, the pathways significantly associated with time, rWeight and rAUC_ins were identified by rotation set testing.

Results

The results suggested that weight gain and worsening of ID activate distinct metabolic pathways. The metabolic profile associated with weight gain indicated an increased activation of arginase, while the pathways associated with time and rAUC_ins were consistent with the expected effect of glucose and insulin, respectively. Overall, more metabolites were significantly associated with rWeight than with rAUC_ins.

Analysis of Serum Metabolomics in Obese Mice Induced by High-Fat Diet

BACKGROUND

Obesity is a public health problem all over the world, and dietary habits are considered one of the important reasons.

METHODS

In this study, serum metabolites of mice fed a normal or high-fat diet (HFD) were analyzed using UPLC-QTOF-MS.

RESULTS

A significant increase in body weight was noted in HFD mice. The HFD and control groups were significantly different from each other on OPLS-DA scores. The major metabolites contributing to obesity were lipid metabolites (phosphatidylcholines, phosphatidylethanolamine, and lysophosphatidylcholines). In addition, this study revealed that glycerophospholipid metabolism, α-linolenic acid metabolism, and linoleic acid metabolism were related to obesity and obesity-associated diseases.

CONCLUSION

These results can be used to better understand obesity and assess its risk, which will provide new ideas for treatment.

Metabolomic and Lipidomic Profiling of Preoperative CSF in Elderly Hip Fracture Patients With Postoperative Delirium

Objective

To investigate dysregulated molecules in preoperative cerebrospinal fluid (CSF) of elderly hip fracture patients with postoperative delirium (POD), in order to identify potential pathological mechanisms and biomarkers for pre-stage POD.

Materials and Methods

This nested case control study used untargeted metabolomic and lipidomic analysis to profile the preoperative CSF of patients (n = 40) who developed POD undergone hip fracture surgery (n = 10) and those who did not (n = 30). Thirty Non-POD patients were matched to 10 POD patients by age (± 2 years) and Mini Mental State Examination score (± 2 points). CSF was collected after successful spinal anesthesia and banked for subsequent analysis. On the first two postoperative days, patients were assessed twice daily using the Confusion Assessment Method-Chinese Revision. CSF samples from the two groups were analyzed to investigate possible relevant pathological mechanisms and identify candidate biomarkers.

Results

Demographic characteristics of the groups were matched. Eighteen metabolites and thirty-three lipids were dysregulated in the preoperative CSF of POD patients. Pathway enrichment analysis revealed perturbations in D-glutamine and D-glutamate metabolism; glycerophospholipid metabolism; alanine, aspartate and glutamate metabolism; sphingolipid metabolism; histidine metabolism; and arginine biosynthesis at the pre-delirium stage. Receiver operating characteristic curve analysis indicated that phosphatidylethanolamine (PE, 40:7e), with an area under the curve value of 0.92, is a potential biomarker for POD.

Conclusion

Multiple pathological mechanisms in the POD group were involved before surgery, including neuroinflammation, oxidative stress, and energy metabolism disorders induced by hypoxia, as well as neurotransmitter imbalances such as increased dopamine and glutamate, and decreased glutamine. These metabolic abnormalities potentially increase the fragility of the brain, thus contributing to POD. PE (40:7e) might be a potential biomarker for POD. Not only do our results provide potential biomarkers for POD, but also provide information for deep pathological research.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier ChiCTR1900021533.

Non-Targeted Metabolomic Analysis Reveals Serum Phospholipid Alterations in Patients with Early Stages of Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is a common complication of type 2 diabetes mellitus (T2DM) characterized by ulcer formation, which can lead to the amputation of lower extremities. However, the metabolic alterations related to this complication are not completely elucidated. Therefore, we carried out a metabolomic analysis of serum samples obtained from T2DM adult patients diagnosed with diabetic foot ulcer in a cross-sectional, observational, and comparative study. Eighty-four volunteers were classified into the following groups: without T2DM (control group, n = 30) and with T2DM and different stages of diabetic foot ulcer according to Wagner-Meggitt classification system: DFU G0 (n = 11), DFU G1 (n = 14), DFU G2 (n = 16), and DFU G3 (n = 13). The non-target metabolomic profile followed by chemometric analysis revealed that lysophosphatidylethanolamine (16:1) could be proposed as key metabolite related to the onset of diabetic foot ulcer; however, this phospholipid was not affected by diabetic foot ulcer progression. Therefore, further studies are necessary to validate these phospholipids as biomarker candidates for the early diagnosis of diabetic foot ulcer in T2DM patients.

Perspective: The Potential Role of Circulating Lysophosphatidylcholine in Neuroprotection against Alzheimer Disease

Alzheimer disease (AD), the most common cause of dementia, is a progressive disorder involving cognitive impairment, loss of learning and memory, and neurodegeneration affecting wide areas of the cerebral cortex and hippocampus. AD is characterized by altered lipid metabolism in the brain. Lower concentrations of long-chain PUFAs have been described in the frontal cortex, entorhinal cortex, and hippocampus in the brain in AD. The brain can synthesize only a few fatty acids; thus, most fatty acids must enter the brain from the blood. Recent studies show that PUFAs such as DHA (22:6) are transported across the blood-brain barrier (BBB) in the form of lysophosphatidylcholine (LPC) via a specific LPC receptor at the BBB known as the sodium-dependent LPC symporter 1 (MFSD2A). Higher dietary PUFA intake is associated with decreased risk of cognitive decline and dementia in observational studies; however, PUFA supplementation, with fatty acids esterified in triacylglycerols did not prevent cognitive decline in clinical trials. Recent studies show that LPC is the preferred carrier of PUFAs across the BBB into the brain. An insufficient pool of circulating LPC containing long-chain fatty acids could potentially limit the supply of long-chain fatty acids to the brain, including PUFAs such as DHA, and play a role in the pathobiology of AD. Whether adults with low serum LPC concentrations are at greater risk of developing cognitive decline and AD remains a major gap in knowledge. Preventing and treating cognitive decline and the development of AD remain a major challenge. The LPC pathway is a promising area for future investigators to identify modifiable risk factors for AD.

Understanding the Physiological Links Between Physical Frailty and Cognitive Decline

Declines in both physical and cognitive function are associated with increasing age. Understanding the physiological link between physical frailty and cognitive decline may allow us to develop interventions that prevent and treat both conditions. Although there is significant epidemiological evidence linking physical frailty to cognitive decline, a complete understanding of the underpinning biological basis of the two disorders remains fragmented. This narrative review discusses insights into the potential roles of chronic inflammation, impaired hypothalamic-pituitary axis stress response, imbalanced energy metabolism, mitochondrial dysfunction, oxidative stress, and neuroendocrine dysfunction linking physical frailty with cognitive decline. We highlight the importance of easier identification of strategic approaches delaying the progression and onset of physical frailty and cognitive decline as well as preventing disability in the older population.

Phytosterols and Inflammation

Besides the well-characterized effect of foods and supplements enriched with plant sterols/stanols on serum LDL-C concentrations, evidence is now emerging that phytosterols exert beneficial effects on non-lipid variables such as inflammatory and oxidative stress markers, coagulation parameters and endothelial function. This makes sterols and stanols an attractive alternative for dietary interventions in cardiovascular disease prevention, particularly in populations at low or medium risk. This review aims to summarize the current knowledge derived from experimental studies and human data on the anti-inflammatory effects of phytosterols/stanols and their relevance in promoting atheroprotection and preventing cardiovascular disease. The anti-inflammatory effects induced by plant sterols/stanols have been demonstrated in in vitro studies and in experimental animal models. However, not all the beneficial effects seen at an experimental level have translated into clinical benefit. Indeed, clinical studies that evaluate the association between phytosterols consumption and inflammatory variables (CRP and cytokines) are inconsistent and have not yet provided a solid answer. Plant sterols have been proposed as useful adjuncts to statin therapy to further reduce the risk of cardiovascular disease. However, there is limited available data and more research needs to be done.

Dual Mass Spectrometric Tissue Imaging of Nanocarrier Distributions and Their Biochemical Effects

Nanomaterial-based drug delivery vehicles are able to deliver therapeutics in a controlled, targeted manner. Currently, however, there are limited analytical methods that can detect both nanomaterial distributions and their biochemical effects concurrently. In this study, we demonstrate that matrix assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) and laser ablation inductively coupled plasma mass spectrometry imaging (LA-ICP-MSI) can be used together to obtain nanomaterial distributions and biochemical consequences. These studies employ nanoparticle-stabilized capsules (NPSCs) loaded with siRNA as a testbed. MALDI-MSI experiments on spleen tissues from intravenously injected mice indicate that NPSCs loaded with anti-TNF-α siRNA cause changes to the lipid composition in white pulp regions of the spleen, as anticipated, based on pathways known to be affected by TNF-α, whereas NPSCs loaded with scrambled siRNA do not cause the predicted changes. Interestingly, LA-ICP-MSI experiments reveal that the NPSCs primarily localize in the red pulp, suggesting that the observed changes in lipid composition are due to diffusive rather than localized effects on TNF-α production. Such information is only accessible by combining data from the two modalities, which we accomplish by using the heme signals from MALDI-MSI and iron signals from LA-ICP-MSI to overlay the images. Several unexpected changes in lipid composition also occur in regions where the NPSCs are found, suggesting that the NPSCs themselves can influence tissue biochemistry as well.

Lipidomic Profile Revealed the Association of Plasma Lysophosphatidylcholines with Adolescent Obesity

Objective

The human lipidomic profile reflects lipid metabolism, including the early phase of pathophysiological changes associated with diseases. An investigation of the association between the plasma lipidomic profile and adolescent obesity might provide new insights into the biological mechanisms of obesity. Therefore, we aimed to investigate the association of the plasma lipidome with obesity in Chinese adolescents using lipidomics.

Methods

Using a combination of liquid chromatography and electrospray ionization tandem mass spectrometry, we quantified 328 lipid species from 24 lipid classes and subclasses in 100 male adolescents aged 14–16 years who were categorized into four groups: (1) normal weight with traditional normal clinical plasma lipid levels (NN); (2) normal weight with traditional abnormal clinical plasma lipid levels (NA); (3) obese with traditional normal clinical plasma lipid levels (ON); and (4) obese with traditional abnormal clinical plasma lipid levels (OA). The concentrations of all the lipid species were compared between obese and normal-weight adolescents at different traditional clinical plasma lipid levels using the Kruskal–Wallis test followed by the Mann–Whitney U test. A partial least squares discriminant analysis (PLS-DA) was applied to select lipids with a significant ability to discriminate adolescent obesity.

Results

The lipidomic profile distinguished obese adolescents from normal-weight subjects. Regardless of whether traditional clinical plasma lipid levels were normal or abnormal, we observed a significant reduction in the levels of five lysophosphatidylcholines (LPC) species (LPC18:2, LPC18:1, LPC20:2, LPC20:1, and LPC20:0) in the obese group compared with the normal-weight group (difference = −31.29% to −13.19%; P=9.91 × 10⁻⁵ to 2.28 × 10⁻²). The ability of these five LPC species to discriminate adolescent obesity was confirmed in the PLS-DA model.

Conclusions

The findings provided evidence for the association of some LPC species with adolescent obesity. The discriminatory effects of five LPC species were identified between normal-weight and obese adolescents, independent of traditional clinical plasma lipid levels. These results will provide a basis for validation in subsequent studies.

Transgenerational cycle of obesity and diabetes: investigating possible metabolic precursors in cord blood from the PREOBE study

AIMS

Offspring of mothers suffering from obesity and/or gestational diabetes mellitus (GDM) were reported to be at risk of higher birth weight (BW), later obesity and diabetes. We hypothesize that infant anthropometry changes related to maternal pathological status are due to dysregulated infant metabolism.

METHODS

First, we inspected differences in BMI z-scores (z-BMI) between three infant groups: born to normal weight (NW; n = 49), overweight/obese (OV/OB; n = 40) and GDM mothers (n = 27) at birth and 1 year. Then, we inspected associations between cord blood metabolites and 1-year Δ z-BMI in the three infant groups at birth and 1 year.

RESULTS

No statistically significant difference was detected in z-BMI between the study groups at birth; however, GDM was associated with heavier infants at 1 year. Regarding the associations between the metabolites and z-BMI, phospholipids, especially those containing polyunsaturated fatty acids, were the species most impacted by the maternal metabolic status, since numerous phosphatidylcholines-PUFA were positively associated with z-BMI in NW but negatively in OV/OB and GDM groups at birth. Conversely, the sum of lysophosphatidylcholines was only positively associated with z-BMI in NW at birth but of no relation in the other two groups. At 1 year, most of the associations seen at birth were reversed in NW and lost in OV/OB and GDM groups. In the NW group, PC-PUFA were found to be negatively associated with Δ z-BMI at 1 year in addition to some medium-chain acylcarnitines, tricarboxylic acid metabolites, Asp and Asn-to-Asp ratio. In OV/OB and GDM groups, the non-esterified fatty acid (NEFA26:0) and His correlated with Δ z-BMI at 1 year in negative and positive directions, respectively.

CONCLUSIONS

GDM was associated with overweight in offspring at 1 year, independent of the BW with lack of evidence on existing correlation of this finding with metabolic alterations detected in cord blood metabolome. Associations were found between cord blood metabolites and infant anthropometry at birth and were influenced by maternal OB and GDM. However, an extension of the findings monitored at birth among the three groups was not detected longitudinally showing a lack of predictive power of cord blood metabolome for later development at least 1 year.

Pre-meal protein intake alters postprandial plasma metabolome in subjects with metabolic syndrome

PURPOSE

We examined the effect on the postprandial plasma metabolome of protein pre-meals before a fat-rich main meal.

METHODS

Two randomized, cross-over meal studies were conducted to test the dose-response effect (0 g, 10 g, 20 g) of a pre-meal with whey protein (WP) (PREMEAL I), and the effect of protein quality (10 g WP, casein, or gluten) and timing (- 15 min vs - 30 min) of the pre-meal (PREMEAL II). Participants with metabolic syndrome received one of the test meals on each test day, - 15 min (or - 30 min) prior to a standardized fat-rich breakfast. Plasma samples were collected at - 15 min (or - 30 min), 0, 120, 240 a nd 360 min and analyzed using liquid chromatography-mass spectrometry with an untargeted method.

RESULTS

Pre-meal WP intake elevated plasma branched-chain amino acids (BCAA), aromatic amino acids and methionine and decreased plasma LPC (16:0) and PC (32:1) levels before the main meal. Early (- 15 to 0 min) aromatic amino acids and BCAA in response to pre-meal WP partially predict the glucose and insulin response after the main meal. A pre-meal with WP altered the postprandial plasma metabolic pattern of acyl-carnitines, specific PCs, LPCs and LPEs, betaine, citric acid, linoleic acid, and β-hydroxypalmitic acid compared to no pre-meal. The casein and WP pre-meals exhibited similar postprandial amino acid responses whereas a pre-meal with gluten resulted in lower levels of plasma amino acids and its metabolites.

CONCLUSION

A pre-meal with protein affects the postprandial metabolic pattern indicating facilitated glucose and lipid disposal from plasma in participants with metabolic syndrome.

Integrated Lipidomics and Proteomics Point to Early Blood-Based Changes in Childhood Preceding Later Development of Psychotic Experiences: Evidence From the Avon Longitudinal Study of Parents and Children

BACKGROUND

The identification of early biomarkers of psychotic experiences (PEs) is of interest because early diagnosis and treatment of those at risk of future disorder is associated with improved outcomes. The current study investigated early lipidomic and coagulation pathway protein signatures of later PEs in subjects from the Avon Longitudinal Study of Parents and Children cohort.

METHODS

Plasma of 115 children (12 years of age) who were first identified as experiencing PEs at 18 years of age (48 cases and 67 controls) were assessed through integrated and targeted lipidomics and semitargeted proteomics approaches. We assessed the lipids, lysophosphatidylcholines (n = 11) and phosphatidylcholines (n = 61), and the protein members of the coagulation pathway (n = 22) and integrated these data with complement pathway protein data already available on these subjects.

RESULTS

Twelve phosphatidylcholines, four lysophosphatidylcholines, and the coagulation protein plasminogen were altered between the control and PEs groups after correction for multiple comparisons. Lipidomic and proteomic datasets were integrated into a multivariate network displaying a strong relationship between most lipids that were significantly associated with PEs and plasminogen. Finally, an unsupervised clustering approach identified four different clusters, with one of the clusters presenting the highest case-control ratio (p < .01) and associated with a higher concentration of smaller low-density lipoprotein cholesterol particles.

CONCLUSIONS

Our findings indicate that the lipidome and proteome of subjects who report PEs at 18 years of age are already altered at 12 years of age, indicating that metabolic dysregulation may contribute to an early vulnerability to PEs and suggesting crosstalk between these lysophosphatidylcholines, phosphatidylcholines, and coagulation and complement proteins.

Identification of metabolic profiles associated with human exposure to perfluoroalkyl substances

Recent epidemiological studies suggest that human exposure to perfluoroalkyl substances (PFASs) may be associated with type 2 diabetes and other metabolic phenotypes. To gain further insights regarding PFASs exposure in humans, we here aimed to characterize the associations between different PFASs and the metabolome. In this cross-sectional study, we investigated 965 individuals from Sweden (all aged 70 years, 50% women) sampled in 2001-2004. PFASs were analyzed in plasma using isotope-dilution ultra-pressure liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Non-target metabolomics profiling was performed in plasma using UPLC coupled to time-of-flight mass spectrometry (UPLC-QTOFMS) operated in positive electrospray mode. Multivariate linear regression analysis was used to investigate associations between circulating levels of PFASs and metabolites. In total, 15 metabolites, predominantly from lipid pathways, were associated with levels of PFASs following adjustment for sex, smoking, exercise habits, education, energy, and alcohol intake, after correction for multiple testing. Perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUnDA) were strongly associated with multiple glycerophosphocholines and fatty acids including docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). We also found that the different PFASs evaluated were associated with distinctive metabolic profiles, suggesting potentially different biochemical pathways in humans.

Plasma metabolites predict both insulin resistance and incident type 2 diabetes: a metabolomics approach within the Prevención con Dieta Mediterránea (PREDIMED) study

BACKGROUND

Insulin resistance is a complex metabolic disorder and is often associated with type 2 diabetes (T2D).

OBJECTIVES

The aim of this study was to test whether baseline metabolites can additionally improve the prediction of insulin resistance beyond classical risk factors. Furthermore, we examined whether a multimetabolite model predicting insulin resistance in nondiabetics can also predict incident T2D.

METHODS

We used a case-cohort study nested within the Prevención con Dieta Mediterránea (PREDIMED) trial in subsets of 700, 500, and 256 participants without T2D at baseline and 1 and 3 y. Fasting plasma metabolites were semiquantitatively profiled with liquid chromatography-tandem mass spectrometry. We assessed associations between metabolite concentrations and the homeostasis model of insulin resistance (HOMA-IR) through the use of elastic net regression analysis. We subsequently examined associations between the baseline HOMA-IR-related multimetabolite model and T2D incidence through the use of weighted Cox proportional hazard models.

RESULTS

We identified a set of baseline metabolites associated with HOMA-IR. One-year changes in metabolites were also significantly associated with HOMA-IR. The area under the curve was significantly greater for the model containing the classical risk factors and metabolites together compared with classical risk factors alone at baseline [0.81 (95% CI: 0.79, 0.84) compared with 0.69 (95% CI: 0.66, 0.73)] and during a 1-y period [0.69 (95% CI: 0.66, 0.72) compared with 0.57 (95% CI: 0.53, 0.62)]. The variance in HOMA-IR explained by the combination of metabolites and classical risk factors was also higher in all time periods. The estimated HRs for incident T2D in the multimetabolite score (model 3) predicting high HOMA-IR (median value or higher) or HOMA-IR (continuous) at baseline were 2.00 (95% CI: 1.58, 2.55) and 2.24 (95% CI: 1.72, 2.90), respectively, after adjustment for T2D risk factors.

CONCLUSIONS

The multimetabolite model identified in our study notably improved the predictive ability for HOMA-IR beyond classical risk factors and significantly predicted the risk of T2D.

Lipidomic profiling reveals early-stage metabolic dysfunction in overweight or obese humans

BACKGROUND

Advances in mass spectrometry and lipidomics techniques are providing new insights into the role of lipid metabolism in obesity-related diseases. However, human lipidomic studies have been inconsistent, owing to the use of indirect proxy measures of metabolic outcomes and relatively limited coverage of the lipidome. Here, we employed comprehensive lipid profiling and gold-standard metabolic measures to test the hypothesis that distinct lipid signatures in obesity may signify early stages of pathogenesis toward type 2 diabetes.

METHODS

Using high-performance liquid chromatography-electrospray tandem mass spectrometry, we profiled >450 lipid species across 26 classes in 65 overweight or obese non-diabetic individuals. Intensive metabolic testing was conducted using direct gold-standard measures of adiposity (% body fat by dual X-ray absorptiometry), insulin sensitivity (hyperinsulinaemic-euglycaemic clamps), and insulin secretion (intravenous glucose tolerance tests), as well as measurement of serum inflammatory cytokines and adipokines (multiplex assays; flow cytometry). Univariable and multivariable linear regression models were computed using Matlab R2011a, and all analyses were corrected for multiple testing using the Benjamini-Hochberg method.

RESULTS

We present new evidence showing a strong and independent positive correlation between the lysophosphatidylinositol (LPI) lipid class and insulin secretion in vivo in humans (β [95% CI] = 781.9 [353.3, 1210.4], p = 0.01), supporting the insulinotropic effects of LPI demonstrated in mouse islets. Dihydroceramide, a sphingolipid precursor, was independently and negatively correlated with insulin sensitivity (β [95% CI] = -1.9 [-2.9, -0.9], p = 0.01), indicating a possible upregulation in sphingolipid synthesis in obese individuals. These associations remained significant in multivariable models adjusted for age, sex, and % body fat. The dihexosylceramide class correlated positively with interleukin-10 before and after adjustment for age, sex, and % body fat (p = 0.02), while the phosphatidylethanolamine class and its vinyl ether-linked (plasmalogen) derivatives correlated negatively with % body fat in both univariable and age- and sex-adjusted models (all p < 0.04).

CONCLUSIONS

Our data suggest that these lipid classes may signify early pathogenesis toward type 2 diabetes and could serve as novel therapeutic targets or biomarkers for diabetes prevention.

Menstrual cycle rhythmicity: metabolic patterns in healthy women

The menstrual cycle is an essential life rhythm governed by interacting levels of progesterone, estradiol, follicular stimulating, and luteinizing hormones. To study metabolic changes, biofluids were collected at four timepoints in the menstrual cycle from 34 healthy, premenopausal women. Serum hormones, urinary luteinizing hormone and self-reported menstrual cycle timing were used for a 5-phase cycle classification. Plasma and urine were analyzed using LC-MS and GC-MS for metabolomics and lipidomics; serum for clinical chemistries; and plasma for B vitamins using HPLC-FLD. Of 397 metabolites and micronutrients tested, 208 were significantly (p < 0.05) changed and 71 reached the FDR 0.20 threshold showing rhythmicity in neurotransmitter precursors, glutathione metabolism, the urea cycle, 4-pyridoxic acid, and 25-OH vitamin D. In total, 39 amino acids and derivatives and 18 lipid species decreased (FDR < 0.20) in the luteal phase, possibly indicative of an anabolic state during the progesterone peak and recovery during menstruation and the follicular phase. The reduced metabolite levels observed may represent a time of vulnerability to hormone related health issues such as PMS and PMDD, in the setting of a healthy, rhythmic state. These results provide a foundation for further research on cyclic differences in nutrient-related metabolites and may form the basis of novel nutrition strategies for women.

Alterations in postmenopausal plasmatic lipidome

BACKGROUND

Menopause consists of a physiological process in women between 40 and 50 years of age, and it has substantial consequences for health, ranging from disturbances in lipid and glycidic metabolism to psychological stress and sleep alterations, thereby increasing women's risk of cardiovascular diseases. Here, we attempted to identify potential lipid alterations not identified by the classic methods.

METHODS AND RESULTS

We analyzed the serum lipid profile in 40 women in pre- and post-menopause using a lipidomic approach and mass spectrometry. Lipid species presented increased concentrations, with a difference of more than 25% post-menopause and with the ceramides (N.C23:0.Cer, N.C23:0(OH).Cer and N.C24:0(OH).Cer) standing out with a fold change of 1.68, 1.59, and 1.58, respectively. It was also observed that 14 metabolites presented a significant difference in the average concentrations between pre- and post-menopause, especially the ceramide species. Strong and positive correlations were identified between various metabolites and fasting glucose, glycated hemoglobin, total cholesterol, LDL, and triglycerides. Of note were the association ceramide (N.C10:0.Cer) and lysophosphatidylethanolamine (LPE.a.C18:0) between fasting glucose and glycated hemoglobin.

CONCLUSION

This study detected lipid alterations, especially in ceramides, post-menopause, as well as correlations with glycidic and lipid markers, which may in the future be useful to investigate diseases associated with menopause.

A proteomic signature that reflects pancreatic beta-cell function

AIM

Proteomics has the potential to enhance early identification of beta-cell dysfunction, in conjunction with monitoring the various stages of type 2 diabetes onset. The most routine method of assessing pancreatic beta-cell function is an oral glucose tolerance test, however this method is time consuming and carries a participant burden. The objectives of this research were to identify protein signatures and pathways related to pancreatic beta-cell function in fasting blood samples.

METHODS

Beta-cell function measures were calculated for MECHE study participants who completed an oral glucose tolerance test and had proteomic data (n = 100). Information on 1,129 protein levels was obtained using the SOMAscan assay. Receiver operating characteristic curves were used to assess discriminatory ability of proteins of interest. Subsequent in vitro experiments were performed using the BRIN-BD11 pancreatic beta-cell line. Replication of findings were achieved in a second human cohort where possible.

RESULTS

Twenty-two proteins measured by aptamer technology were significantly associated with beta-cell function/HOMA-IR while 17 proteins were significantly associated with the disposition index (p ≤ 0.01). Receiver operator characteristic curves determined the protein panels to have excellent discrimination between low and high beta-cell function. Linear regression analysis determined that beta-endorphin and IL-17F have strong associations with beta-cell function/HOMA-IR, β = 0.039 (p = 0.005) and β = -0.027 (p = 0.013) respectively. Calcineurin and CRTAM were strongly associated with the disposition index (β = 0.005 and β = 0.005 respectively, p = 0.012). In vitro experiments confirmed that IL-17F modulated insulin secretion in the BRIN-BD11 cell line, with the lower concentration of 10 ng/mL significantly increasing glucose stimulated insulin secretion (p = 0.043).

CONCLUSIONS

Early detection of compromised beta-cell function could allow for implementation of nutritional and lifestyle interventions before progression to type 2 diabetes.

Plasma trimethylamine-N-oxide and related metabolites are associated with type 2 diabetes risk in the Prevención con Dieta Mediterránea (PREDIMED) trial

Background

The role of trimethylamine-N-oxide (TMAO) in type 2 diabetes (T2D) is currently partially understood and controversial.

Objective

The aim of this study was to investigate associations between TMAO and related metabolites with T2D risk in subjects at high risk of cardiovascular disease.

Design

This is a case-cohort design study within the Prevención con Dieta Mediterránea (PREDIMED) study, with 251 incident T2D cases and a random sample of 694 participants (641 noncases and 53 overlapping cases) without T2D at baseline (median follow-up: 3.8 y). We used liquid chromatography-tandem mass spectrometry to measure plasma TMAO, l-carnitine, betaine, lyso-phosphatidylcholine (LPC) and lyso-phosphatidylethanolamine (LPE) species, phosphocholine, α-glycerophosphocholine, and choline at baseline and after 1 y. We examined associations with the use of weighted Cox proportional hazard models, accounting for the weighted case-cohort design by the Barlow method.

Results

After adjustment for recognized T2D risk factors and multiple testing, individuals in the highest quartile of baseline TMAO and α-glycerophosphocholine had a lower risk of T2D [HR (95% CI): 0.52 (0.29, 0.89) and 0.46 (0.24, 0.89), respectively]. The HR (95% CI) comparing the extreme quartiles of betaine was 0.41 (0.23, 0.74). Similar trends were observed for C16:0 LPC, C18:1 LPC, C18:0 LPC, C20:4 LPC, C22:6 LPC, C18:1 LPC plasmalogen, and C16:0 LPE. After correcting for multiple comparisons, participants in the highest quartile of 1-y changes in oleic acid LPC plasmalogen concentrations had a lower T2D risk than the reference quartile.

Conclusion

Whether the associations between plasma TMAO and certain metabolite concentrations with T2D risk reflect its pathophysiology or represent an epiphenomenon needs to be elucidated. This trial is registered at http://www.controlled-trials.com as ISRCTN35739639.

Metabotypes of response to bariatric surgery independent of the magnitude of weight loss

Objective

Bariatric surgery is considered the most efficient treatment for morbid obesity and its related diseases. However, its role as a metabolic modifier is not well understood. We aimed to determine biosignatures of response to bariatric surgery and elucidate short-term metabolic adaptations.

Methods

We used a LC- and FIA-ESI-MS/MS approach to quantify acylcarnitines, (lyso)phosphatidylcholines, sphingomyelins, amino acids, biogenic amines and hexoses in serum samples of subjects with morbid obesity (n = 39) before and 1, 3 and 6 months after bariatric surgery. K-means cluster analysis allowed to distinguish metabotypes of response to bariatric surgery.

Results

For the first time, global metabolic changes following bariatric surgery independent of the baseline health status of the subjects have been revealed. We identify two metabolic phenotypes (metabotypes) at the interval 6 months-baseline after surgery, which presented differences in the levels of compounds of urea metabolism, gluconeogenic precursors and (lyso)phospholipid particles. Clinically, metabotypes were different in terms of the degree of improvement in insulin resistance, cholesterol, low-density lipoproteins and uric acid independent of the magnitude of weight loss.

Conclusions

This study opens new perspectives and new hypotheses on the metabolic benefits of bariatric surgery and understanding of the biology of obesity and its associated diseases.

Adipose tissue and metabolic and inflammatory responses to stroke are altered in obese mice

Obesity is an independent risk factor for stroke, although several clinical studies have reported that obesity improves stroke outcome. Obesity is hypothesised to aid recovery by protecting against post-stroke catabolism. We therefore assessed whether obese mice had an altered metabolic and inflammatory response to stroke. Obese ob/ob mice underwent a 20-min middle cerebral artery occlusion and 24-h reperfusion. Lipid metabolism and expression of inflammatory cytokines were assessed in the plasma, liver and adipose tissue. The obese-specific metabolic response to stroke was assessed in plasma using non-targeted ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) metabolomics coupled with univariate and multivariate analysis. Obesity had no effect on the extent of weight loss 24 h after stroke but affected the metabolic and inflammatory responses to stroke, predominantly affecting lipid metabolism. Specifically, obese mice had increases in plasma free fatty acids and expression of adipose lipolytic enzymes. Metabolomics identified several classes of metabolites affected by stroke in obese mice, including fatty acids and membrane lipids (glycerophospholipids, lysophospholipids and sphingolipids). Obesity also featured increases in inflammatory cytokines in the plasma and adipose tissue. Overall, these results demonstrate that obesity affected the acute metabolic and inflammatory response to stroke and suggest a potential role for adipose tissue in this effect. These findings could have implications for longer-term recovery and also further highlight the importance of considering comorbidities in preclinical stroke research, especially when identifying biomarkers for stroke. However, further work is required to assess whether these changes translate into long-term effects on recovery.

Summary: Obesity, a co-morbidity for stroke, affected the acute metabolic and inflammatory response to stroke, highlighting the importance of considering comorbidities in preclinical stroke research, especially when identifying biomarkers.

Combined untargeted and targeted metabolomic profiling reveals urinary biomarkers for discriminating obese from normal-weight adolescents

BACKGROUND

Childhood and adolescent obesity may lead to obesity and related complications in adulthood. Biomarkers of obesity can be useful for screening for obesity complications and promoting early intervention during school age. Thus, the metabolomic differences in obese children and adolescents should be investigated for identification of potential biomarkers.

OBJECTIVES

We investigated urinary biomarkers to distinguish metabolomic characteristics between obesity and normal weight in adolescents.

METHODS

Adolescent subjects were divided into non-obese (n = 91) and obese (n = 93) groups according to body mass index. Untargeted and targeted metabolomic profiling of urine was performed using high-performance liquid chromatography (LC)-quadrupole time-of-flight mass spectrometry (MS), LC-MS/MS and flow injection analysis-MS/MS systems, respectively.

RESULTS

Multivariate statistical analysis showed clear discrimination between the untargeted metabolomes of non-obese and obese groups. Seven endogenous metabolites were distinguished in the obese group, and inflammation-related metabolite markers showed strong predictive power for group classification. From targeted metabolomics, 45 metabolites mostly related to inflammation were significantly different in the obese group.

CONCLUSIONS

Significantly different metabolome signatures were identified between normal-weight and obese adolescents. Combined untargeted and targeted metabolomics demonstrated that inflammation-driven insulin resistance, ammonia toxicity and oxidative stress may represent crucial metabolomic signatures in obese adolescents.

Lysophosphatidylcholines activate PPARδ and protect human skeletal muscle cells from lipotoxicity

Metabolomics studies of human plasma demonstrate a correlation of lower plasma lysophosphatidylcholines (LPC) concentrations with insulin resistance, obesity, and inflammation. This relationship is not unraveled on a molecular level. Here we investigated the effects of the abundant LPC(16:0) and LPC(18:1) on human skeletal muscle cells differentiated to myotubes. Transcriptome analysis of human myotubes treated with 10μM LPC for 24h revealed enrichment of up-regulated peroxisome proliferator-activated receptor (PPAR) target transcripts, including ANGPTL4, PDK4, PLIN2, and CPT1A. The increase in both PDK4 and ANGPTL4 RNA expression was abolished in the presence of either PPARδ antagonist GSK0660 or GSK3787. The induction of PDK4 by LPCs was blocked with siRNA against PPARD. The activation of PPARδ transcriptional activity by LPC was shown as PPARδ-dependent luciferase reporter gene expression and enhanced DNA binding of the PPARδ/RXR dimer. On a functional level, further results show that the LPC-mediated activation of PPARδ can reduce fatty acid-induced inflammation and ER stress in human skeletal muscle cells. The protective effect of LPC was prevented in the presence of the PPARδ antagonist GSK0660. Taking together, LPCs can activate PPARδ, which is consistent with the association of high plasma LPC levels and PPARδ-dependent anti-diabetic and anti-inflammatory effects.

Exploring the Inflammatory Metabolomic Profile to Predict Response to TNF-α Inhibitors in Rheumatoid Arthritis

In clinical practice, approximately one-third of patients with rheumatoid arthritis (RA) respond insufficiently to TNF-α inhibitors (TNFis). The aim of the study was to explore the use of a metabolomics to identify predictors for the outcome of TNFi therapy, and study the metabolomic fingerprint in active RA irrespective of patients’ response. In the metabolomic profiling, lipids, oxylipins, and amines were measured in serum samples of RA patients from the observational BiOCURA cohort, before start of biological treatment. Multivariable logistic regression models were established to identify predictors for good- and non-response in patients receiving TNFi (n = 124). The added value of metabolites over prediction using clinical parameters only was determined by comparing the area under receiver operating characteristic curve (AUC-ROC), sensitivity, specificity, positive- and negative predictive value and by the net reclassification index (NRI). The models were further validated by 10-fold cross validation and tested on the complete TNFi treatment cohort including moderate responders. Additionally, metabolites were identified that cross-sectionally associated with the RA disease activity score based on a 28-joint count (DAS28), erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Out of 139 metabolites, the best-performing predictors were sn1-LPC(18:3-ω3/ω6), sn1-LPC(15:0), ethanolamine, and lysine. The model that combined the selected metabolites with clinical parameters showed a significant larger AUC-ROC than that of the model containing only clinical parameters (p = 0.01). The combined model was able to discriminate good- and non-responders with good accuracy and to reclassify non-responders with an improvement of 30% (total NRI = 0.23) and showed a prediction error of 0.27. For the complete TNFi cohort, the NRI was 0.22. In addition, 88 metabolites were associated with DAS28, ESR or CRP (p<0.05). Our study established an accurate prediction model for response to TNFi therapy, containing metabolites and clinical parameters. Associations between metabolites and disease activity may help elucidate additional pathologic mechanisms behind RA.

Impairment of lysophospholipid metabolism in obesity: altered plasma profile and desensitization to the modulatory properties of n-3 polyunsaturated fatty acids in a randomized controlled trial

BACKGROUND

Plasma lysophospholipids have emerged as signaling molecules with important effects on inflammation, insulin resistance, and fatty liver disease, each of which is linked closely to obesity. Dietary n-3 (ω-3) polyunsaturated fatty acids (PUFAs) may be able to improve these conditions.

OBJECTIVE

The objective of this study was to assess the response of plasma lysophospholipids to obesity, n-3 PUFA consumption, and a high-fat meal challenge to better understand the role of lysophospholipid metabolism in the progression of obesity-related disorders.

DESIGN

We determined the concentrations of 8 lysophosphatidylcholines, 11 lysophosphatidylethanolamines, and 7 lysophosphatidylinositols in the plasma of 34 normal-weight and 38 obese subjects randomly assigned to consume corn oil (control) or n-3 PUFA-rich fish oil (3 g/d; n = 15-19/group) for 90 d. Blood samples were collected on the last day of the study under fasting conditions and 6 h after a high-fat meal (1135 kcal, 86 g fat) challenge. The profile of secreted lysophospholipids was studied in HepG2 cells under palmitate-induced steatosis.

RESULTS

Obese and normal-weight subjects had different profiles of plasma lysophospholipids. A multivariate combination of the 26 lysophospholipids could discriminate between normal-weight and obese subjects with an accuracy of 98%. The high-fat meal challenge altered the concentration of plasma lysophosphatidylcholines in an oil treatment-dependent manner in normal-weight but not obese subjects, suggesting that obesity impairs the sensitivity of lysophospholipid metabolism to n-3 PUFAs. Noncytotoxic steatosis in HepG2 cells affected the secretion pattern of lysophospholipids, partially resembling the changes observed in the plasma of obese subjects.

CONCLUSIONS

Obesity has a substantial impact on lysophospholipid metabolism, altering the plasma lysophospholipid profile and abolishing its sensitivity to dietary n-3 PUFAs. These effects could contribute to the onset or progression of alterations associated with obesity, such as inflammation, insulin resistance, and fatty liver disease. This trial was registered at www.controlled-trials.com as ISRCTN96712688.

Association of Metabolites with Obesity and Type 2 Diabetes Based on FTO Genotype

The single nucleotide polymorphism rs9939609 of the gene FTO, which encodes fat mass and obesity–associated protein, is strongly associated with obesity and type 2 diabetes (T2D) in multiple populations; however, the underlying mechanism of this association is unclear. The present study aimed to investigate FTO genotype–dependent metabolic changes in obesity and T2D. To elucidate metabolic dysregulation associated with disease risk genotype, genomic and metabolomic datasets were recruited from 2,577 participants of the Korean Association REsource (KARE) cohort, including 40 homozygous carriers of the FTO risk allele (AA), 570 heterozygous carriers (AT), and 1,967 participants carrying no risk allele (TT). A total of 134 serum metabolites were quantified using a targeted metabolomics approach. Through comparison of various statistical methods, seven metabolites were identified that are significantly altered in obesity and T2D based on the FTO risk allele (adjusted p < 0.05). These identified metabolites are relevant to phosphatidylcholine metabolic pathway, and previously reported to be metabolic markers of obesity and T2D. In conclusion, using metabolomics with the information from genome-wide association studies revealed significantly altered metabolites depending on the FTO genotype in complex disorders. This study may contribute to a better understanding of the biological mechanisms linking obesity and T2D.

Insulin resistance in prepubertal obese children correlates with sex-dependent early onset metabolomic alterations

Background:

Insulin resistance (IR) is usually the first metabolic alteration diagnosed in obese children and the key risk factor for development of comorbidities. The factors determining whether or not IR develops as a result of excess body mass index (BMI) are still not completely understood.

Objectives:

This study aimed to elucidate the mechanisms underpinning the predisposition toward hyperinsulinemia-related complications in obese children by using a metabolomic strategy that allows a profound interpretation of metabolic profiles potentially affected by IR.

Methods:

Serum from 60 prepubertal obese children (30 girls/30 boys, 50% IR and 50% non-IR in each group, but with similar BMIs) were analyzed by using liquid chromatography–mass spectrometry, gas chromatography–mass spectrometry and capillary electrophoresis–mass spectrometry following an untargeted metabolomics approach. Validation was then performed on a group of 100 additional children with the same characteristics.

Results:

When obese children with and without IR were compared, 47 metabolites out of 818 compounds (P<0.05) obtained after data pre-processing were found to be significantly different. Bile acids exhibit the greatest changes (that is, approximately a 90% increase in IR). The majority of metabolites differing between groups were lysophospholipids (15) and amino acids (17), indicating inflammation and central carbon metabolism as the most altered processes in impaired insulin signaling. Multivariate analysis (OPLS-DA models) showed subtle differences between groups that were magnified when females were analyzed alone.

Conclusions:

Inflammation and central carbon metabolism, together with the contribution of the gut microbiota, are the most altered processes in obese children with impaired insulin signaling in a sex-specific fashion despite their prepubertal status.