Gender-dependent associations of metabolite profiles and body fat distribution in a healthy population with central obesity: towards metabolomics diagnostics

The metabolomic profiling of total fat and fat distribution in a multi-cohort study of women and men

Currently studies aiming for the comprehensive metabolomics profiling of measured total fat (%) as well as fat distribution in both sexes are lacking. In this work, bioimpedance analysis was applied to measure total fat (%) and fat distribution (trunk to leg ratio). Liquid chromatography-mass spectrometry-based untargeted metabolomics was employed to profile the metabolic signatures of total fat (%) and fat distribution in 3447 participants from three Swedish cohorts (EpiHealth, POEM and PIVUS) using a discovery-replication cross-sectional study design. Total fat (%) and fat distribution were associated with 387 and 120 metabolites in the replication cohort, respectively. Enriched metabolic pathways for both total fat (%) and fat distribution included protein synthesis, branched-chain amino acids biosynthesis and metabolism, glycerophospholipid metabolism and sphingolipid metabolism. Four metabolites were mainly related to fat distribution: glutarylcarnitine (C5-DC), 6-bromotryptophan, 1-stearoyl-2-oleoyl-GPI (18:0/18:1) and pseudouridine. Five metabolites showed different associations with fat distribution in men and women: quinolinate, (12Z)-9,10-dihydroxyoctadec-12-enoate (9,10-DiHOME), two sphingomyelins and metabolonic lactone sulfate. To conclude, total fat (%) and fat distribution were associated with a large number of metabolites, but only a few were exclusively associated with fat distribution and of those metabolites some were associated with sex*fat distribution. Whether these metabolites mediate the undesirable effects of obesity on health outcomes remains to be further investigated.

Application of Metabolomics in Obesity-Related Childhood Asthma Subtyping: A Narrative Scoping Review

Obesity-related asthma is a heterogeneous childhood asthma phenotype with rising prevalence. Observational studies identify early-life obesity or weight gain as risk factors for childhood asthma development. The reverse association is also described, children with asthma have a higher risk of being obese. Obese children with asthma have poor symptom control and an increased number of asthma attacks compared to non-obese children with asthma. Clinical trials have also identified that a proportion of obese children with asthma do not respond as well to usual treatment (e.g., inhaled corticosteroids). The heterogeneity of obesity-related asthma phenotypes may be attributable to different underlying pathogenetic mechanisms. Although few childhood obesity-related asthma endotypes have been described, our knowledge in this field is incomplete. An evolving analytical profiling technique, metabolomics, has the potential to link individuals' genetic backgrounds and environmental exposures (e.g., diet) to disease endotypes. This will ultimately help define clinically relevant obesity-related childhood asthma subtypes that respond better to targeted treatment. However, there are challenges related to this approach. The current narrative scoping review summarizes the evidence for metabolomics contributing to asthma subtyping in obese children, highlights the challenges associated with the implementation of this approach, and identifies gaps in research.

Graduate Student Literature Review: A scoping review on the impact of consumption of dairy products on phosphatidylcholine and lysophosphatidylcholine in circulation and the liver in human studies and animal models

Dairy consumption is inversely related to the risk of developing type 2 diabetes in epidemiological research. One proposed hypothesis is that phospholipid (PL) species associated with dairy consumption mediate this relationship. This scoping review aimed to identify the existing literature in animal and human trials investigating the impact of dairy products, including milk, yogurt, and cheese as well as dairy-derived PL supplementation on PL and its species in the circulation, summarizing the characteristics of these studies and identifying research gaps. A systematic search was conducted across 3 databases (PubMed, Scopus, and Web of Science) in March 2021. Of 2,427 identified references, 15 studies (7 humans and 8 animal studies) met the eligibility criteria and were included in the final narrative synthesis. The evidence base was heterogeneous, involving a variety of clinical and preclinical studies, metabolically healthy or obese/diabetic participants or animal models, and displayed mixed findings. Circulating postprandial concentrations of total PL were elevated acutely but unchanged after longer intervention with dairy products. The PL concentration remained stable even after a high dosage of milk supplemented with dairy-derived PL, which may be related to increased fecal excretion; however, certain phosphatidylcholine (PC) or lysophosphatidylcholine species were increased in circulation by interventions. These include several PC species with 32 to 38 total carbons in addition to the dairy biomarkers C15:0 and C17:0. The results of this scoping review demonstrate a small body of literature indicating that dairy products can influence blood concentrations of PC and lysophosphatidylcholine species in both rodents and humans without alteration of total PL and PC. There is a lack of well-designed trials in humans and animals that explore the potential differences between individual dairy foods on PL species. In addition, trials to understand the bioactive properties of PC and lysophosphatidylcholine species on cardiometabolic risk are needed.

Validation of the Metabolite Ergothioneine as a Forensic Marker in Bloodstains

Ergothioneine, which is a naturally occurring metabolite, generally accumulates in tissues and cells subjected to oxidative stress, owing to its structural stability at physiological pH; therefore, it has been attracting attention in various biomedical fields. Ergothioneine has also been suggested as a potential forensic marker, but its applicability has not yet been quantitatively validated. In this study, quantitative analysis of ergothioneine in bloodstains was conducted to estimate the age of bloodstains and that of bloodstain donors. Blood from youth and elderly participants was used to generate bloodstains. After extracting metabolites from the bloodstains under prevalent age conditions, ergothioneine levels were quantified by mass spectrometry via multiple reaction monitoring. The concentration of ergothioneine in day 0 bloodstains (fresh blood), was significantly higher in the elderly group than in the youth group, but it did not differ by sex. Statistically significant differences were observed between the samples from the two age groups on days 0, 5 and 7, and on days 2 and 3 compared with day 0. The findings suggest that ergothioneine can be used to estimate the age of bloodstains and of the donor; it could be useful as a potential marker in reconstructing crime scenes.

Evaluation of the Value of Waist Circumference and Metabolomics in the Estimation of Visceral Adipose Tissue

Visceral adipose tissue (VAT) is a strong prognostic factor for cardiovascular disease and a potential target for cardiovascular risk stratification. Because VAT is difficult to measure in clinical practice, we estimated prediction models with predictors routinely measured in general practice and VAT as outcome using ridge regression in 2,501 middle-aged participants from the Netherlands Epidemiology of Obesity study, 2008-2012. Adding waist circumference and other anthropometric measurements on top of the routinely measured variables improved the optimism-adjusted R2 from 0.50 to 0.58 with a decrease in the root-mean-square error (RMSE) from 45.6 to 41.5 cm2 and with overall good calibration. Further addition of predominantly lipoprotein-related metabolites from the Nightingale platform did not improve the optimism-corrected R2 and RMSE. The models were externally validated in 370 participants from the Prospective Investigation of Vasculature in Uppsala Seniors (PIVUS, 2006-2009) and 1,901 participants from the Multi-Ethnic Study of Atherosclerosis (MESA, 2000-2007). Performance was comparable to the development setting in PIVUS (R2 = 0.63, RMSE = 42.4 cm2, calibration slope = 0.94) but lower in MESA (R2 = 0.44, RMSE = 60.7 cm2, calibration slope = 0.75). Our findings indicate that the estimation of VAT with routine clinical measurements can be substantially improved by incorporating waist circumference but not by metabolite measurements.

Metabolomics-based understanding of the olanzapine-induced weight gain in female first-episode drug-naïve patients with schizophrenia

Previous studies have demonstrated that patients with schizophrenia (SZ) have greater rate of metabolic disorder as compared with the control population, which likely be the consequence of use of atypical antipsychotics. Olanzapine is a widely used antipsychotic, which increases the weight of SZ patients. However, the underlying mechanism remains poorly understood. Here we report the metabolomics-based understanding of the weight gain induced by olanzapine. 57 first-episode drug-naïve patients (FEDN) were recruited, of whom 27 patients completed a 4-week clinical trial. We then profiled the metabolomes of their plasma with the LC-MS-based nontargeted metabolomics approach at the baseline and after olanzapine monotherapy for 4 weeks. We observed that the plasma of the olanzapine-treated patient had significantly higher lysophosphatidylcholine (LysoPC), lysophosphatidylethanolamine (LysoPE) and lower carnitine as compared with that of the baseline plasma samples. Moreover, regression analyses indicated that the change of LysoPC(14:0) level was an independent contributor to the olanzapine-induced weight gain. Our study suggests that the metabolomics-based approach may facilitate the identification of biomarkers associated with the metabolic disorder causing by antipsychotic in schizophrenia patients.

Distinct metabolite profiles of adiposity indices and their relationships with habitual diet in young adults

BACKGROUND AND AIMS

Obesity is characterized as overall or regional adiposity accumulation. However, the metabolic status underlying fat accumulation was not well understood. We sought to identify metabolite profiles based on their correlations with body mass index (BMI), body fat percentage (BFP), waist circumference (WC), and visceral adiposity index (VAI) in young Chinese adults (19-37 years old), and their associations with dietary consumption were also explored.

METHODS AND RESULTS

A total of 86 plasma samples were analyzed using untargeted lipidomics and metabolomics approaches. Metabolite profiles of adiposity indices were identified using random forest modelling. Ridge regression was used to generate metabolite scores. Overall, 30, 46, 30, and 20 metabolites correlated with BMI, BFP, WC, and VAI, respectively, which resulted in metabolite scores for each index. Top three enriched categories of the identified metabolites were glycerophospholipids, glycerolipids, and sphingolipids, with some specific metabolites (such as phosphatidylserine (37:2), phatidylethanolamine (42:4), and ceramide (40:0)) exclusively associated with overall adiposity, and some other metabolites exclusively associated with abdominal adiposity indices, e.g., triradylglycerol (45:0, 52:4, and 35:0) and diacylglycerol (38:4, 36:3, and 36:5). Moreover, metabolite scores were negatively associated with the intake of food rich in protein or fiber, while they were positively associated with food rich in carbohydrate, with similar results for adiposity indices.

CONCLUSION

We observed unique metabolite profiles of regional or overall fat deposition in young adults. Glycerophospholipids, glycerolipids, or sphingolipids may be involved in the regulation of adiposity accumulation, affected by dietary exposures.

Exploration of Blood Lipoprotein and Lipid Fraction Profiles in Healthy Subjects through Integrated Univariate, Multivariate, and Network Analysis Reveals Association of Lipase Activity and Cholesterol Esterification with Sex and Age

In this study, we investigated blood lipoprotein and lipid fraction profiles, quantified using nuclear magnetic resonance, in a cohort of 844 healthy blood donors, integrating standard univariate and multivariate analysis with predictive modeling and network analysis. We observed a strong association of lipoprotein and lipid main fraction profiles with sex and age. Our results suggest an age-dependent remodulation of lipase lipoprotein activity in men and a change in the mechanisms controlling the ratio between esterified and non-esterified cholesterol in both men and women.

Metabolic footprint of aging and obesity in red blood cells

Aging is a physiological process whose underlying mechanisms are still largely unknown. The study of the biochemical transformations associated with aging is crucial for understanding this process and could translate into an improvement of the quality of life of the aging population. Red blood cells (RBCs) are the most abundant cells in humans and are involved in essential functions that could undergo different alterations with age. The present study analyzed the metabolic alterations experienced by RBCs during aging, as well as the influence of obesity and gender in this process. To this end, the metabolic profile of 83 samples from healthy and obese patients was obtained by Nuclear Magnetic Resonance spectroscopy. Multivariate statistical analysis revealed differences between Age-1 (≤45) and Age-2 (>45) subgroups, as well as between BMI-1 (<30) and BMI-2 (≥30) subgroups, while no differences were associated with gender. A general decrease in the levels of amino acids was detected with age, in addition to metabolic alterations of glycolysis, the pentose phosphate pathway, nucleotide metabolism, glutathione metabolism and the Luebering-Rapoport shunt. Obesity also had an impact on the metabolomics profile of RBCs; sometimes mimicking the alterations induced by aging, while, in other cases, its influence was the opposite, suggesting these changes could counteract the adaptation of the organism to senescence.

A Predictive Model of Metabolic Syndrome by Medical Examination: Evidence from an 8-Year Chinese Cohort

PURPOSE

To develop a predictive model for the risk of metabolic syndrome (MetS).

PATIENTS AND METHODS

Totally, 1556 residents without MetS were finally included in 2006 and they were observed for 8 years to check who developed MetS. Univariate and multivariate logistic regression analyses was adopted to explore the risk factors of MetS and develop the predictive model that used the medical examination information of MetS risk after 8 years. The receiver operating characteristic (ROC) curve was drawn to assess the predictive capacity of the model.

RESULTS

The risk of MetS in overweight, prehypertension, hypertension subjects were 4.610 [95% confidence interval (CI): 2.415 to 8.800], 2.759 (95% CI: 1.519 to 5.011) and 3.589 (95% CI: 1.672 to 7.706) times higher than that in controls, respectively. The risk of MetS in people with high-density lipoprotein (HDL) <1.10 mmol/L was 3.716-fold in comparison with HDL ≥1.55 mmol/L [odds risk (OR) = 3.716, 95% CI: 1.483 to 9.313]. Individuals with fatty liver had a higher risk of MetS (OR = 2.577, 95% CI: 1.472 to 4.512). The AUC of the predictive model was 0.831 (95% CI: 0.798 to 0.865), with the sensitivity of 0.898 (95% CI: 0.831 to 0.941) and the specificity of 0.676 (95% CI: 0.651 to 0.700).

CONCLUSION

The model performed well predictive power for the risk of MetS, which may provide a reference for clinicians to identify high-risk groups early.

Prevalence of and lifestyle factors associated with metabolic syndrome determined using multi-level models in Chinese adults from a cross-sectional survey

People living in the same area are more likely to experience similar socioeconomic characteristics, which leads to cluster effect and influences the generalizability of data regarding metabolic syndrome (MetS). However, previous studies did not consider or adjust for the cluster effect of living circumstances. The aim of this study was to determine the prevalence of MetS and associated lifestyle factors in Chinese adults 18 to 80 years of age, using multi-level generalized estimation equation (GEE).The participants came from a large-scale cross-sectional population survey. A total of 28,062 participants underwent all the blood tests. Participants meeting at least 3 of the 5 diagnostic criteria were defined as having MetS. Multi-level GEE was used to evaluate the relationship between MetS and lifestyle covariates to control the cluster effect of living circumstances. Odds ratios (ORs) and their 95% confidence intervals (CIs) were used to assess the strength of each relationship.A total of 65.70% of the participants had at least 1 clinical feature of MetS, and 2926 were diagnosed with MetS (prevalence 14.03%). 32.74%, 18.93%, 10.25%, 3.25%, and 0.53% of the participants had 1, 2, 3, 4, and 5 components, respectively. The prevalence of MetS in men (12.31%) was lower than in women (15.57%). After controlling for the cluster effect of living circumstances, many demographic and lifestyle characteristics were associated with MetS. Overweight (OR = 1.670, 95%CI: 1.600-1.743), obesity (OR = 2.287, 95% CI: 2.136-2.449), current alcohol consumption (OR = 1.053, 95% CI: 1.020-1.086), physical labor (OR=1.070, 95% CI: 1.040-1.101), a high-salt diet (OR=1.040, 95% CI: 1.009-1.071), hyperuricemia (OR=1.264, 95% CI: 1.215-1.316), short sleep duration (OR=1.032, 95% CI: 1.009-1.055), and a family history of cardiovascular disease (OR=1.065, 95% CI: 1.019-1.113), or cerebrovascular disease (OR=1.055, 95% CI: 1.007-1.104) increased the risk of MetS. The risk of MetS increased 6.9% (OR = 1.069, 95% CI: 1.053-1.085) with each 5% increase in body fat percentage.MetS has become a serious public health challenge in China. Many lifestyle factors have been found to be closely associated with MetS, including obesity, a high-salt diet, alcohol consumption, and short sleep duration. Therefore, changes in lifestyle are very important for adults to reduce the prevalence of MetS.

Metabolomics profiling of visceral and abdominal subcutaneous adipose tissue in colorectal cancer patients: results from the ColoCare study

PURPOSE

Underlying mechanisms of the relationship between body fatness and colorectal cancer remain unclear. This study investigated associations of circulating metabolites with visceral (VFA), abdominal subcutaneous (SFA), and total fat area (TFA) in colorectal cancer patients.

METHODS

Pre-surgery plasma samples from 212 patients (stage I-IV) from the ColoCare Study were used to perform targeted metabolomics. VFA, SFA, and TFA were quantified by computed tomography scans. Partial correlation and linear regression analyses of VFA, SFA, and TFA with metabolites were computed and corrected for multiple testing. Cox proportional hazards were used to assess 2-year survival.

RESULTS

In patients with metastatic tumors, SFA and TFA were statistically significantly inversely associated with 16 glycerophospholipids (SFA: pFDR range 0.017-0.049; TFA: pFDR range 0.029-0.048), while VFA was not. Doubling of ten of the aforementioned glycerophospholipids was associated with increased risk of death in patients with metastatic tumors, but not in patients with non-metastatic tumors (phet range: 0.00044-0.049). Doubling of PC ae C34:0 was associated with ninefold increased risk of death in metastatic tumors (Hazard Ratio [HR], 9.05; 95% confidence interval [CI] 2.17-37.80); an inverse association was observed in non-metastatic tumors (HR 0.17; 95% CI 0.04-0.87; phet = 0.00044).

CONCLUSION

These data provide initial evidence that glycerophospholipids in metastatic colorectal cancer are uniquely associated with subcutaneous adiposity, and may impact overall survival.

Influence of combinations of drugs that act on the CYP2D6 metabolic pathway in the treatment of major depressive disorder: A population-based study

Objective

To describe the frequency of drug combinations (substrate-substrate or substrate-inhibitor) with the potential to interfere with the CYP2D6 metabolic pathway in patients receiving antidepressant medication for major depressive disorder.

Methods

We carried out an observational study using outpatient medical records. We included adult subjects who initiated antidepressant medication during 2008–2010. Patients were assigned to three study groups: no combination, substrate-substrate, and substrate-inhibitor. Follow-up period was 12 months. Main measures: demographics, comorbidity and medication persistence. Statistical analysis included a logistic regression model, P < 0.05.

Results

Five thousand six hundred and thirty patients were recruited (61.9 years, 76.9% female), 24.4% (CI: 23.8 – 26.0%) received some kind of drug combination (substrate-substrate: 15.4%, substrate-inhibitor: 9.0%). Variables significantly associated with drugs combinations that may act on the CYP2D6 metabolic pathway were: dementia (OR = 4.2), neuropathy (OR = 4.2) and stroke (OR = 1.9), P < 0.001. Medication persistence at 12 months was longer in patients with no combination (55.3%) than in patients receiving substrate-substrate (50.5%) or substrate-inhibitor (45.0%) combinations, P < 0.001.

Conclusions

Twenty-five percent of major depressive disorder patients received a combination of drugs with the potential to interfere with CYP2D6 metabolic pathway. These combinations increased with comorbidity and resulted in shorter medication persistence of antidepressant treatment.

Lipidomic profiling identifies signatures of metabolic risk

BACKGROUND

Metabolic syndrome (MetS), the clustering of metabolic risk factors, is associated with cardiovascular disease risk. We sought to determine if dysregulation of the lipidome may contribute to metabolic risk factors.

METHODS

We measured 154 circulating lipid species in 658 participants from the Framingham Heart Study (FHS) using liquid chromatography-tandem mass spectrometry and tested for associations with obesity, dysglycemia, and dyslipidemia. Independent external validation was sought in three independent cohorts. Follow-up data from the FHS were used to test for lipid metabolites associated with longitudinal changes in metabolic risk factors.

RESULTS

Thirty-nine lipids were associated with obesity and eight with dysglycemia in the FHS. Of 32 lipids that were available for replication for obesity and six for dyslipidemia, 28 (88%) replicated for obesity and five (83%) for dysglycemia. Four lipids were associated with longitudinal changes in body mass index and four were associated with changes in fasting blood glucose in the FHS.

CONCLUSIONS

We identified and replicated several novel lipid biomarkers of key metabolic traits. The lipid moieties identified in this study are involved in biological pathways of metabolic risk and can be explored for prognostic and therapeutic utility.

Sphingolipid serum profiling in vitamin D deficient and dyslipidemic obese dimorphic adults

Recent studies on Saudi Arabians indicate a prevalence of dyslipidemia and vitamin D deficiency (25(OH)D) in both normal weight and obese subjects. In the present study the sphingolipid pattern was investigated in 23 normolipidemic normal weight (NW), 46 vitamin D deficient dyslipidemic normal weight (-vitDNW) and 60 vitamin D deficient dyslipidemic obese (-vitDO) men and women by HPTLC-primuline profiling and LC-MS analyses. Results indicate higher levels of total ceramide (Cer) and dihydroceramide (dhCers C18–22) and lower levels of total sphingomyelins (SMs) and dihydrosphingomyelin (dhSM) not only in -vitDO subjects compared to NW, but also in –vitDNW individuals. A dependency on body mass index (BMI) was observed analyzing specific Cer acyl chains levels. Lower levels of C20 and 24 were observed in men and C24.2 in women, respectively. Furthermore, LC-MS analyses display dimorphic changes in NW, -vitDNW and –vitDO subjects. In conclusion, LC-MS data identify the independency of the axis high Cers, dhCers and SMs from obesity per se. Furthermore, it indicates that long chains Cers levels are specific target of weight gain and that circulating Cer and SM levels are linked to sexual dimorphism status and can contribute to predict obese related co-morbidities in men and women.

Metabolomics: a search for biomarkers of visceral fat and liver fat content

INTODUCTION

Excess visceral and liver fat are known risk factors for cardiometabolic disorders. Metabolomics might allow for easier quantification of these ectopic fat depots, instead of using invasive and costly tools such as MRI or approximations such as waist circumference.

OBJECTIVE

We explored the potential use of plasma metabolites as biomarkers of visceral adipose tissue (VAT) and hepatic triglyceride content (HTGC).

METHODS

We performed a cross-sectional analysis of a subset of the Netherlands Epidemiology of Obesity study. Plasma metabolite profiles were determined using the Biocrates AbsoluteIDQ p150 kit in 176 individuals with normal fasting plasma glucose. VAT was assessed with magnetic resonance imaging and HTGC with proton-MR spectroscopy. We used linear regression to investigate the associations of 190 metabolite variables with VAT and HTGC.

RESULTS

After adjustment for age, sex, total body fat, currently used approximations of visceral and liver fat, and multiple testing, three metabolite ratios were associated with VAT. The strongest association was the lysophosphatidylcholines to total phosphatidylcholines (PCs) ratio [- 14.1 (95% CI - 21.7; - 6.6) cm² VAT per SD of metabolite concentration]. Four individual metabolites were associated with HTGC, especially the diacyl PCs of which C32:1 was the strongest at a 1.31 (95% CI 1.14; 1.51) fold increased HTGC per SD of metabolite concentration.

CONCLUSION

Metabolomics may be a useful tool to identify biomarkers of visceral fat and liver fat content that have added diagnostic value over current approximations. Replication studies are required to validate the diagnostic value of these metabolites.

Near-roadway air pollution exposure and altered fatty acid oxidation among adolescents and young adults - The interplay with obesity

BACKGROUND

Air pollution exposure has been shown to increase the risk of obesity and metabolic dysfunction in animal models and human studies. However, the metabolic pathways altered by air pollution exposure are unclear, especially in adolescents and young adults who are at a critical period in the development of cardio-metabolic diseases.

OBJECTIVES

The aim of this study was to examine the associations between air pollution exposure and indices of fatty acid and amino acid metabolism.

METHODS

A total of 173 young adults (18-23 years) from eight Children's Health Study (CHS) Southern California communities were examined from 2014 to 2018. Near-roadway air pollution (NRAP) exposure (freeway and non-freeway) and regional air pollution exposure (nitrogen dioxide, ozone and particulate matter) during one year before the study visit were estimated based on participants' residential addresses. Serum concentrations of 64 targeted metabolites including amino acids, acylcarnitines, non-esterified fatty acid (NEFA) and glycerol were measured in fasting serum samples. Principal component analysis of metabolites was performed to identify metabolite clusters that represent key metabolic pathways. Mixed effects models were used to analyze the associations of air pollution exposure with metabolomic principal component (PC) scores and individual metabolite concentrations adjusting for potential confounders.

RESULTS

Higher lagged one-year averaged non-freeway NRAP exposure was associated with higher concentrations of NEFA oxidation byproducts and higher NEFA-related PC score (all p's ≤ 0.038). The effect sizes were larger among obese individuals (interaction p = 0.047). Among females, higher freeway NRAP exposure was also associated with a higher NEFA-related PC score (p = 0.042). Among all participants, higher freeway NRAP exposure was associated with a lower PC score for lower concentrations of short- and median-chain acylcarnitines (p = 0.044).

CONCLUSIONS

Results of this study indicate that NRAP exposure is associated with altered fatty acid metabolism, which could contribute to the metabolic perturbation in obese youth.

Multi-disciplinary weight management compared to routine care in youth with obesity: what else should be monitored?

PURPOSE

Efficacy of multi-disciplinary weight management (MDM) in youth has not been compared to their routine care.

OBJECTIVES

To compare body mass index z-score (zBMI) and blood test (lab) changes (Δ) in youth before and after MDM and to correlate bio-impedance analysis (BIA) and lab measurements.

METHODS

We compared zBMI Δ (from referring providers' records), within 3 months prior to MDM, to monthly zBMI Δ after MDM, in a retrospective cohort of youth at a tertiary MDM center. BIA and lab measurements after 6 months, MDM were compared to baseline.

RESULTS

We reviewed 316 records (12.9 ± 3.5 years, 49% males, 104.8 ± 35.1 kgs). The pre-MDM zBMI Δ (0.02 ± 0.1) was reversed after MDM (-0.03 ± 0.09, visit 2, P < 0.001). The zBMI Δ progressed on follow-up (-0.14 ± 0.05, visit 6). Baseline BIA components correlated with Homeostatic Model Assessment of Insulin resistance (HOMA-IR), triglycerides, and systolic blood pressure. HbA1c, HOMA-IR, and liver functions significantly improved on follow-up. MDM participation showed progressive attrition and dropped to 11.6% at visit 6.

CONCLUSION

MDM in youth resulted in zBMI and lab improvements compared to their pre-MDM measurements. BIA provided additional outcome measures that correlated with metabolic markers. MDM follow-up was limited by the progressive participant drop-out. Behavioral economic strategies are needed to improve adherence.

Metabolomic correlates of central adiposity and earlier-life body mass index

BMI is correlated with circulating metabolites, but few studies discuss other adiposity measures, and little is known about metabolomic correlates of BMI from early life. We investigated associations between different adiposity measures, BMI from childhood through adulthood, and metabolites quantified from serum using ¹H NMR spectroscopy in 900 British men and women aged 60-64. We assessed BMI, waist-to-hip ratio (WHR), android-to-gynoid fat ratio (AGR), and BMI from childhood through adulthood. Linear regression with Bonferroni adjustment was performed to assess adiposity and metabolites. Of 233 metabolites, 168; 126; and 133 were associated with BMI, WHR, and AGR at age 60-64, respectively. Associations were strongest for HDL, particularly HDL particle size-e.g., there was 0.08 SD decrease in HDL diameter (95% CI: 0.07-0.10) with each unit increase in BMI. BMI-adjusted AGR or WHR were associated with 31 metabolites where there was no metabolome-wide association with BMI. We identified inverse associations between BMI at age 7 and glucose or glycoprotein at age 60-64 and relatively large LDL cholesteryl ester with postadolescent BMI gains. In summary, we identified metabolomic correlates of central adiposity and earlier-life BMI. These findings support opportunities to leverage metabolomics in early prevention of cardiovascular risk attributable to body fatness.

HDL Subclass Distribution Shifts with Increasing Central Adiposity

Although cross-sectional studies have shown that obesity is associated with lower concentrations of large high-density lipoprotein (HDL) subclasses, it is unknown if changes in HDL subclasses are related to changes in body fat and its distribution over time. We therefore assessed changes in HDL subclass distribution over a 5.5-year free-living follow-up period in 24 black South African women. At baseline and follow-up, body composition and body fat distribution were measured using anthropometry, dual X-ray absorptiometry, and computerized tomography. HDL subclass distribution was quantified using Lipoprint®. Over the 5.5-year follow-up period, body fat (+17.3 ± 4.5 kg, p < 0.05) and trunk fat mass (+7.4 ± 1.9%, % fat mass, FM, p < 0.05) increased, while leg fat mass (-2.53 ± 0.56%, % FM, p < 0.001) and the distribution of large (-6.43 ± 2.12%, p < 0.05) HDL subclasses decreased. A percentage decrease in large HDL subclasses was associated with a percentage increase in central fat mass (visceral adipose tissue (VAT) area, p < 0.05) and a percentage decrease in peripheral fat mass (leg fat mass). These preliminary findings suggest that a relative redistribution of body fat from the periphery to the abdominal region were associated with a decrease HDL subclass size in black South African women and provide a novel link between body fat distribution and lipidology in this population.

Biomarkers of Individual Foods, and Separation of Diets Using Untargeted LC-MS-based Plasma Metabolomics in a Randomized Controlled Trial

SCOPE

Self-reported dietary intake does not represent an objective unbiased assessment. The effect of the new Nordic diet (NND) versus average Danish diet (ADD) on plasma metabolic profiles is investigated to identify biomarkers of compliance and metabolic effects.

METHODS AND RESULTS

In a 26-week controlled dietary intervention study, 146 subjects followed either NND, a predominantly organic diet high in fruit, vegetables, whole grains, and fish, or ADD, a diet higher in imported and processed foods. Fasting plasma samples are analyzed with untargeted ultra-performance liquid chromatography-quadruple time-of-flight. It is demonstrated that supervised machine learning with feature selection can separate NND and ADD samples with an average test set performance of up to 0.88 area under the curve. The NND plasma metabolome is characterized by diet-related metabolites, such as pipecolic acid betaine (whole grain), trimethylamine oxide, and prolyl hydroxyproline (both fish intake), while theobromine (chocolate) and proline betaine (citrus) were associated with ADD. Amino acid (i.e., indolelactic acid and hydroxy-3-methylbutyrate) and fat metabolism (butyryl carnitine) characterize ADD whereas NND is associated with higher concentrations of polyunsaturated phosphatidylcholines.

CONCLUSIONS

The plasma metabolite profiles are predictive of dietary patterns and reflected good compliance while indicating effects of potential health benefit, including changes in fat metabolism and glucose utilization.

Android fat as a determinant of metabolic syndrome: Sex differences

OBJECTIVES

Regional fat accumulation may play an important role in the pathogenesis of metabolic syndrome (MetS) and cardiovascular diseases, yet the results are controversial. The aim of this study was to determine the relationship between regional fat accumulation and MetS as well as the underlying mechanism in Chinese adults.

METHODS

We conducted a cross-sectional study of 428 Chinese adults (166 men and 262 women). Android and gynoid fat percentage (AFP and GFP) were measured by dual energy x-ray absorptiometry. Fasting lipid parameters were analyzed by chemistry analyzer COBAS.

RESULTS

Forty-six (28%) men and 34 (13%) women had MetS according to the modified National Cholesterol Education Panel Adult Treatment Panel III definition for South Asia. AFP was strongly correlated with more metabolic risk factors than GFP in men. In women, AFP and GFP showed significant opposite effects on triacylglycerol, high-density lipoprotein cholesterol, and waist circumference. On multivariate regression, AFP was an independent determinant of MetS in men after adjustment for confounding factors. For women, both AFP and the homeostatic model assessment for insulin resistance were predictors for MetS.

CONCLUSIONS

Increased android fat may play a direct role in the development of MetS in Chinese adults. However, the associations between android fat, insulin resistance, and MetS are sex-dependent. This is probably due to different effects of sex hormones on adipose tissue or by genetic factors between sexes. Knowing the sex differences in developing MetS may help design sex-specific preventive strategies that will benefit the overall population health.

Blood Metabolic Signatures of Body Mass Index: A Targeted Metabolomics Study in the EPIC Cohort

Metabolomics is now widely used to characterize metabolic phenotypes associated with lifestyle risk factors such as obesity. The objective of the present study was to explore the associations of body mass index (BMI) with 145 metabolites measured in blood samples in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Metabolites were measured in blood from 392 men from the Oxford (UK) cohort (EPIC-Oxford) and in 327 control subjects who were part of a nested case-control study on hepatobiliary carcinomas (EPIC-Hepatobiliary). Measured metabolites included amino acids, acylcarnitines, hexoses, biogenic amines, phosphatidylcholines, and sphingomyelins. Linear regression models controlled for potential confounders and multiple testing were run to evaluate the associations of metabolite concentrations with BMI. 40 and 45 individual metabolites showed significant differences according to BMI variations, in the EPIC-Oxford and EPIC-Hepatobiliary subcohorts, respectively. Twenty two individual metabolites (kynurenine, one sphingomyelin, glutamate and 19 phosphatidylcholines) were associated with BMI in both subcohorts. The present findings provide additional knowledge on blood metabolic signatures of BMI in European adults, which may help identify mechanisms mediating the relationship of BMI with obesity-related diseases.

Erythritol is a pentose-phosphate pathway metabolite and associated with adiposity gain in young adults

Metabolomic markers associated with incident central adiposity gain were investigated in young adults. In a 9-mo prospective study of university freshmen (n = 264). Blood samples and anthropometry measurements were collected in the first 3 d on campus and at the end of the year. Plasma from individuals was pooled by phenotype [incident central adiposity, stable adiposity, baseline hemoglobin A1c (HbA1c) > 5.05%, HbA1c < 4.92%] and assayed using GC-MS, chromatograms were analyzed using MetaboliteDetector software, and normalized metabolite levels were compared using Welch's t test. Assays were repeated using freshly prepared pools, and statistically significant metabolites were quantified in a targeted GC-MS approach. Isotope tracer studies were performed to determine if the potential marker was an endogenous human metabolite in men and in whole blood. Participants with incident central adiposity gain had statistically significantly higher blood erythritol [P < 0.001, false discovery rate (FDR) = 0.0435], and the targeted assay revealed 15-fold [95% confidence interval (CI): 13.27, 16.25] higher blood erythritol compared with participants with stable adiposity. Participants with baseline HbA1c > 5.05% had 21-fold (95% CI: 19.84, 21.41) higher blood erythritol compared with participants with lower HbA1c (P < 0.001, FDR = 0.00016). Erythritol was shown to be synthesized endogenously from glucose via the pentose-phosphate pathway (PPP) in stable isotope-assisted ex vivo blood incubation experiments and through in vivo conversion of erythritol to erythronate in stable isotope-assisted dried blood spot experiments. Therefore, endogenous production of erythritol from glucose may contribute to the association between erythritol and obesity observed in young adults.

Relation between metabolic syndrome and body compositions among Chinese adolescents and adults from a large-scale population survey

Background

Few nationally representative surveys regarding body composition and metabolic syndrome (MetS) have been done in a large-scale representative Chinese population to explore the prediction of body composition indicators for MetS. The objective of this study was to examine the relation of body composition and MetS and to determine the optimal cut-off values of body composition indicators that predict MetS in a large representative Chinese sample based on multiple provinces and ethnicities, covering a broad age range from 10 to 80 years old.

Methods

The subjects came from a large-scale population survey on Chinese physiological constants and health conditions conducted in six provinces. 32,036 subjects completed all blood biochemical testing and body composition measure. Subjects meeting at least 3 of the following 5 criteria qualify as having MetS: elevated blood pressure, lower high density lipoprotein cholesterol level, higher triglyceride level, higher fasting glucose level and abdominal obesity.

Results

The total prevalence rate of MetS for males (9.29%) was lower than for females (11.58%). The prevalence rates were 12.03% for male adults and 15.57% for female adults respectively. The risk of MetS increased 44.6% (OR = 1.446, 95%CI: 1.414–1.521) for males and 53.4% (OR = 1.534, 95%CI: 1.472–1.598) for females with each 5% increase of percentage of body fat. The risk of MetS increased two-fold (OR = 2.020, 95%CI: 1.920–2.125 for males; OR = 2.047, 95%CI: 1.954–2.144 for females respectively) with each 5% increase of waist-hip ratio. The risk of MetS increased three-fold (OR = 2.915, 95%CI: 2.742–3.099 for males; OR = 2.950, 95%CI: 2.784–3.127 for females respectively) with each 5% increase of Waist-to-Height Ratio (WHtR). Areas under the receiver operating curve (AUC) of most body composition indicators were larger than 0.70 and the sensitivities and the specificities of most cut-off values were larger than 0.65. AUCs of WHR and WHtR were the largest. The optimal cut-off values of WHtR were 0.51 for males and 0.53 for females.

Conclusion

MetS has become a serious public health challenge in China. Body composition variables were closely related to MetS and they were reliable indicators in the screening of the presence of MetS.

Visceral adipose tissue but not subcutaneous adipose tissue is associated with urine and serum metabolites

Obesity is a complex multifactorial phenotype that influences several metabolic pathways. Yet, few studies have examined the relations of different body fat compartments to urinary and serum metabolites. Anthropometric phenotypes (visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), the ratio between VAT and SAT (VSR), body mass index (BMI), waist circumference (WC)) and urinary and serum metabolite concentrations measured by nuclear magnetic resonance spectroscopy were measured in a population-based sample of 228 healthy adults. Multivariable linear and logistic regression models, corrected for multiple testing using the false discovery rate, were used to associate anthropometric phenotypes with metabolites. We adjusted for potential confounding variables: age, sex, smoking, physical activity, menopausal status, estimated glomerular filtration rate (eGFR), urinary glucose, and fasting status. In a fully adjusted logistic regression model dichotomized for the absence or presence of quantifiable metabolite amounts, VAT, BMI and WC were inversely related to urinary choline (ß = -0.18, p = 2.73*10⁻³), glycolic acid (ß = -0.20, 0.02), and guanidinoacetic acid (ß = -0.12, p = 0.04), and positively related to ethanolamine (ß = 0.18, p = 0.02) and dimethylamine (ß = 0.32, p = 0.02). BMI and WC were additionally inversely related to urinary glutamine and lactic acid. Moreover, WC was inversely associated with the detection of serine. VAT, but none of the other anthropometric parameters, was related to serum essential amino acids, such as valine, isoleucine, and phenylalanine among men. Compared to other adiposity measures, VAT demonstrated the strongest and most significant relations to urinary and serum metabolites. The distinct relations of VAT, SAT, VSR, BMI, and WC to metabolites emphasize the importance of accurately differentiating between body fat compartments when evaluating the potential role of metabolic regulation in the development of obesity-related diseases, such as insulin resistance, type 2 diabetes, and cardiovascular disease.

Emerging role and recent applications of metabolomics biomarkers in obesity disease research

Metabolomics is a promising approach for the identification of metabolites which serve for early diagnosis, prediction of therapeutic response and prognosis of disease.

Cardiovascular Risk Factors Associated With Blood Metabolite Concentrations and Their Alterations During a 4-Year Period in a Population-Based Cohort

Background—

The effects of lifestyle risk factors considered collectively on the human metabolism are to date unknown. We aim to investigate the association of these risk factors with metabolites and their changes during 4 years.

Methods and Results—

One hundred and sixty-three metabolites were measured in serum samples with the AbsoluteIDQ kit p150 (Biocrates) following a targeted metabolomics approach, in a population-based cohort of 1030 individuals, aged 45 to 83 years at baseline. We evaluated associations between metabolite concentrations (28 acylcarnitines, 14 amino acids, 9 lysophosphocholines, 72 phosphocholines, 10 sphingomyelins and sum of hexoses) and 5 lifestyle risk factors (body mass index [BMI], alcohol consumption, smoking, diet, and exercise). Multilevel or simple linear regression modeling adjusted for relevant covariates was used for the evaluation of cross-sectional or longitudinal associations, respectively; multiple testing correction was based on false discovery rate. BMI, alcohol consumption, and smoking were associated with lipid metabolism (reduced lyso- and acyl-alkyl-phosphatidylcholines and increased diacylphosphatidylcholines concentrations). Smoking showed positive associations with acylcarnitines, and BMI correlated inversely with nonessential amino acids. Fewer metabolites showed relative changes that were associated with baseline risk factors: increases in 5 different acyl-alkyl phosphatidylcholines were associated with lower alcohol consumption and BMI and with a healthier diet. Increased levels of tyrosine were associated with BMI. Sex-specific effects of smoking and BMI were found specifically related to acylcarnitine metabolism: in women higher BMI and in men more pack-years were associated with increases in acylcarnitines.

Conclusions—

This study showed sex-specific effects of lifestyle risks factors on human metabolism and highlighted their long-term metabolic consequences.

Metabolomics-guided insights on bariatric surgery versus behavioral interventions for weight loss

OBJECTIVE

To review the metabolomic studies carried out so far to identify metabolic markers associated with surgical and dietary treatments for weight loss in subjects with obesity.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed.

RESULTS

Thirty-two studies successfully met the eligibility criteria. The metabolic adaptations shared by surgical and dietary interventions mirrored a state of starvation ketoacidosis (increase of circulating ketone bodies), an increase of acylcarnitines and fatty acid β-oxidation, a decrease of specific amino acids including branched-chain amino acids (BCAA) and (lyso)glycerophospholipids previously associated with obesity, and adipose tissue expansion. The metabolic footprint of bariatric procedures was specifically characterized by an increase of bile acid circulating pools and a decrease of ceramide levels, a greater perioperative decline in BCAA, and the rise of circulating serine and glycine, mirroring glycemic control and inflammation improvement. In one study, 3-hydroxybutyrate was particularly identified as an early metabolic marker of long-term prognosis after surgery and proposed to increase current prognostic modalities and contribute to personalized treatment.

CONCLUSIONS

Metabolomics helped in deciphering the metabolic response to weight loss treatments. Moving from association to causation is the next challenge to move to a further level of clinical application.

Dietary carbohydrate intake, insulin resistance and gastro-oesophageal reflux disease: a pilot study in European- and African-American obese women

BACKGROUND

Although obesity rates are higher in African-American than European-American women, gastro-oesophageal reflux disease (GERD) and its comorbidities are more prevalent in European-American women. A common denominator for increased adiposity, and consequent insulin resistance, is excess dietary macronutrient intake - which may promote greater prevalence and severity of GERD in women.

AIM

To investigate whether GERD is more robustly associated with dietary carbohydrate intake, particularly dietary simple carbohydrate intake, and insulin resistance in European-American women.

METHODS

About 144 obese women were assessed at baseline and 16 weeks after consuming a high-fat/low-carbohydrate diet. GERD diagnosis and medication usage was confirmed in medical records with symptoms and medications assessed weekly.

RESULTS

About 33.3% (N = 33) of European-American and 20.0% (N = 9) of African-American women had GERD at baseline. Total carbohydrate (r = 0.34, P < 0.001), sugars (r = 0.30, P = 0.005), glycaemic load (r = 0.34, P = 0.001) and HOMA_IR (r = 0.30, P = 0.004) were associated with GERD, but only in European-American women. In response to high-fat/low-carbohydrate diet, reduced intake of sugars was associated with reduced insulin resistance. By the end of diet week 10, all GERD symptoms and medication usage had resolved in all women.

CONCLUSIONS

GERD symptoms and medication usage was more prevalent in European-American women, for whom the relationships between dietary carbohydrate intake, insulin resistance and GERD were most significant. Nevertheless, high-fat/low-carbohydrate diet benefited all women with regard to reducing GERD symptoms and frequency of medication use.

Deconstructing the pig sex metabolome: Targeted metabolomics in heavy pigs revealed sexual dimorphisms in plasma biomarkers and metabolic pathways

Metabolomics has opened new possibilities to investigate metabolic differences among animals. In this study, we applied a targeted metabolomic approach to deconstruct the pig sex metabolome as defined by castrated males and entire gilts. Plasma from 545 performance-tested Italian Large White pigs (172 castrated males and 373 females) sampled at about 160 kg live weight were analyzed for 186 metabolites using the Biocrates AbsoluteIDQ p180 Kit. After filtering, 132 metabolites (20 AA, 11 biogenic amines, 1 hexose, 13 acylcarnitines, 11 sphingomyelins, 67 phosphatidylcholines, and 9 lysophosphatidylcholines) were retained for further analyses. The multivariate approach of the sparse partial least squares discriminant analysis was applied, together with a specifically designed statistical pipeline, that included a permutation test and a 10 cross-fold validation procedure that produced stability and effect size statistics for each metabolite. Using this approach, we identified 85 biomarkers (with metabolites from all analyzed chemical families) that contributed to the differences between the 2 groups of pigs ( < 0.05 at the stability statistic test). All acylcarnitines and almost all biogenic amines were higher in castrated males than in gilts. Metabolites involved in tryptophan catabolism had the largest differences (i.e., delta = 20% for serotonin) between castrated males (higher) and gilts (lower). The level of several AA (Ala, Arg, Gly, His, Lys, Ser, Thr, and Trp) was higher in gilts (delta was from approximately 1.0 to approximately 4.8%) whereas products of AA catabolism (taurine, 2-aminoadipic acid, and methionine sulfoxide) were higher in castrated males (delta was approximately 5.0-6.0%), suggesting a metabolic shift in castrated males toward energy storage and lipid production. Similar general patterns were observed for most sphingomyelins, phosphatidylcholines, and lysophosphatidylcholines. Metabolomic pathway analysis and pathway enrichment identified several differences between the 2 sexes. This metabolomic overview opened new clues on the biochemical mechanisms underlying sexual dimorphism that, on one hand, might explain differences in terms of economic traits between castrated male pigs and entire gilts and, on the other hand, could strengthen the pig as a model to define metabolic mechanisms related to fat deposition.

The Karlsruhe Metabolomics and Nutrition (KarMeN) Study: Protocol and Methods of a Cross-Sectional Study to Characterize the Metabolome of Healthy Men and Women

Background

The human metabolome is influenced by various intrinsic and extrinsic factors. A precondition to identify such biomarkers is the comprehensive understanding of the composition and variability of the metabolome of healthy humans. Sample handling aspects have an important impact on the composition of the metabolome; therefore, it is crucial for any metabolomics study to standardize protocols on sample collection, preanalytical sample handling, storage, and analytics to keep the nonbiological variability as low as possible.

Objective

The main objective of the KarMeN study is to analyze the human metabolome in blood and urine by targeted and untargeted metabolite profiling (gas chromatography-mass spectrometry [GC-MS], GC×GC-MS, liquid chromatography-mass spectrometry [LC-MS/MS], and¹H nuclear magnetic resonance [NMR] spectroscopy) and to determine the impact of sex, age, body composition, diet, and physical activity on metabolite profiles of healthy women and men. Here, we report the outline of the study protocol with special regard to all aspects that should be considered in studies applying metabolomics.

Methods

Healthy men and women, aged 18 years or older, were recruited. In addition to a number of anthropometric (height, weight, body mass index, waist circumference, body composition), clinical (blood pressure, electrocardiogram, blood and urine clinical chemistry) and functional parameters (lung function, arterial stiffness), resting metabolic rate, physical activity, fitness, and dietary intake were assessed, and 24-hour urine, fasting spot urine, and plasma samples were collected. Standard operating procedures were established for all steps of the study design. Using different analytical techniques (LC-MS, GC×GC-MS,¹H NMR spectroscopy), metabolite profiles of urine and plasma were determined. Data will be analyzed using univariate and multivariate as well as predictive modeling methods.

Results

The project was funded in 2011 and enrollment was carried out between March 2012 and July 2013. A total of 301 volunteers were eligible to participate in the study. Metabolite profiling of plasma and urine samples has been completed and data analysis is currently underway.

Conclusions

We established the KarMeN study applying a broad set of clinical and physiological examinations with a high degree of standardization. Our experimental approach of combining scheduled timing of examinations and sampling with the multiplatform approach (GC×GC-MS, GC-MS, LC-MS/MS, and¹H NMR spectroscopy) will enable us to differentiate between current and long-term effects of diet and physical activity on metabolite profiles, while enabling us at the same time to consider confounders such as age and sex in the KarMeN study.

Trial Registration

German Clinical Trials Register DRKS00004890; https://drks-neu.uniklinik-freiburg.de/drks_web/navigate.do? navigationId=trial.HTML&TRIAL_ID=DRKS00004890 (Archived by WebCite at http://www.webcitation.org/6iyM8dMtx)

Associations of anthropometric markers with serum metabolites using a targeted metabolomics approach: results of the EPIC-potsdam study

Background/Objectives:

The metabolic consequences of type of body shape need further exploration. Whereas accumulation of body mass in the abdominal area is a well-established metabolic risk factor, accumulation in the gluteofemoral area is controversially debated. We evaluated the associations of anthropometric markers of overall body mass and body shape with 127 serum metabolites within a sub-sample of the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort.

Subjects/Methods:

The cross-sectional analysis was conducted in 2270 participants, randomly drawn from the EPIC-Potsdam cohort. Metabolites were measured by targeted metabolomics. To select metabolites related with both waist circumference (WC) (abdominal subcutaneous and visceral fat) and hip circumference (HC) (gluteofemoral fat, muscles and bone structure) correlations (r) with body mass index (BMI) as aggregating marker of body mass (lean and fat mass) were calculated. Relations with body shape were assessed by median metabolite concentrations across tertiles of WC and HC, mutually adjusted to each other.

Results:

Correlations revealed 23 metabolites related to BMI (r⩾I0.20 I). Metabolites showing relations with BMI were showing similar relations with HC adjusted WC (WC_HC). In contrast, relations with WC adjusted HC (HC_WC) were less concordant with relations of BMI and WC_HC. In both sexes, metabolites with concordant relations regarding WC_HC and HC_WC included tyrosine, diacyl-phosphatidylcholine C38:3, C38:4, lyso-phosphatidylcholine C18:1, C18:2 and sphingomyelin C18:1; metabolites with opposite relations included isoleucine, diacyl-phosphatidylcholine C42:0, acyl–alkyl-phosphatidylcholine C34:3, C42:4, C42:5, C44:4 and C44:6. Metabolites specifically related to HC_WC included acyl–alkyl-phosphatidylcholine C34:2, C36:2, C38:2 and C40:4, and were solely observed in men. Other metabolites were related to WC_HC only.

Conclusions:

The study revealed specific metabolic profiles for HC_WC as marker of gluteofemoral body mass differing from those for BMI and WC_HC as markers of overall body mass and abdominal fat, respectively. Thus, the study suggests that gluteofemoral mass may have less-adverse metabolic implications than abdominal fat.

Metabolite Signatures of Metabolic Risk Factors and their Longitudinal Changes

CONTEXT

Metabolic dysregulation underlies key metabolic risk factors—obesity, dyslipidemia, and dysglycemia.

OBJECTIVE

To uncover mechanistic links between metabolomic dysregulation and metabolic risk by testing metabolite associations with risk factors cross-sectionally and with risk factor changes over time.

DESIGN

Cross-sectional—discovery samples (n = 650; age, 36–69 years) from the Framingham Heart Study (FHS) and replication samples (n = 670; age, 61–76 years) from the BioImage Study, both following a factorial design sampled from high vs low strata of body mass index, lipids, and glucose. Longitudinal—FHS participants (n = 554) with 5–7 years of follow-up for risk factor changes.

SETTING

Observational studies.

PARTICIPANTS

Cross-sectional samples with or without obesity, dysglycemia, and dyslipidemia, excluding prevalent cardiovascular disease and diabetes or dyslipidemia treatment. Age- and sex-matched by group.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

Gas chromatography-mass spectrometry detected 119 plasma metabolites. Cross-sectional associations with obesity, dyslipidemia, and dysglycemia were tested in discovery, with external replication of 37 metabolites. Single- and multi-metabolite markers were tested for association with longitudinal changes in risk factors.

RESULTS

Cross-sectional metabolite associations were identified with obesity (n = 26), dyslipidemia (n = 21), and dysglycemia (n = 11) in discovery. Glutamic acid, lactic acid, and sitosterol associated with all three risk factors in meta-analysis (P < 4.5 × 10−4). Metabolites associated with longitudinal risk factor changes were enriched for bioactive lipids. Multi-metabolite panels explained 2.5–15.3% of longitudinal changes in metabolic traits.

CONCLUSIONS

Cross-sectional results implicated dysregulated glutamate cycling and amino acid metabolism in metabolic risk. Certain bioactive lipids were associated with risk factors cross-sectionally and over time, suggesting their upstream role in risk factor progression. Functional studies are needed to validate findings and facilitate translation into treatments or preventive measures.

Weight loss predictability by plasma metabolic signatures in adults with obesity and morbid obesity of the DiOGenes study

OBJECTIVE

Aim is to predict successful weight loss by metabolic signatures at baseline and to identify which differences in metabolic status may underlie variations in weight loss success.

METHODS

In DiOGenes, a randomized, controlled trial, weight loss was induced using a low-calorie diet (800 kcal) for 8 weeks. Men (N = 236) and women (N = 431) as well as groups with overweight/obesity and morbid obesity were studied separately. The relation between the metabolic status before weight loss and weight loss was assessed by stepwise regression on multiple data sets, including anthropometric parameters, NMR-based plasma metabolites, and LC-MS-based plasma lipid species.

RESULTS

Maximally, 57% of the variation in weight loss success can be predicted by baseline parameters. The most powerful predictive models were obtained in subjects with morbid obesity. In these models, the metabolites most predictive for weight loss were acetoacetate, triacylglycerols, phosphatidylcholines, specific amino acids, and creatine and creatinine. This metabolic profile suggests that high energy metabolism activity results in higher amounts of weight loss.

CONCLUSIONS

Possible predictive (pre-diet) markers were found for amount of weight loss for specific subgroups.

A longitudinal analysis of the effects of age on the blood plasma metabolome in the common marmoset, Callithrix jacchus

Primates tend to be long-lived for their size with humans being the longest lived of all primates. There are compelling reasons to understand the underlying age-related processes that shape human lifespan. But the very fact of our long lifespan that makes it so compelling, also makes it especially difficult to study. Thus, in studies of aging, researchers have turned to non-human primate models, including chimpanzees, baboons, and rhesus macaques. More recently, the common marmoset, Callithrix jacchus, has been recognized as a particularly valuable model in studies of aging, given its small size, ease of housing in captivity, and relatively short lifespan. However, little is known about the physiological changes that occur as marmosets age. To begin to fill in this gap, we utilized high sensitivity metabolomics to define the longitudinal biochemical changes associated with age in the common marmoset. We measured 2104 metabolites from blood plasma at three separate time points over a 17-month period, and we completed both a cross-sectional and longitudinal analysis of the metabolome. We discovered hundreds of metabolites associated with age and body weight in both male and female animals. Our longitudinal analysis identified age-associated metabolic pathways that were not found in our cross-sectional analysis. Pathways enriched for age-associated metabolites included tryptophan, nucleotide, and xenobiotic metabolism, suggesting these biochemical pathways might play an important role in the basic mechanisms of aging in primates. Moreover, we found that many metabolic pathways associated with age were sex specific. Our work illustrates the power of longitudinal approaches, even in a short time frame, to discover novel biochemical changes that occur with age.

Trend of Body Compositions with Aging among Chinese Adolescents, Adults and Elders

INTRODUCTION

Rare reports can be found about sex- and age-specific body composition survey among Chinese population. The aim of this study is to explore the change of sex-specific body compositions with aging among Chinese adolescents, adults and elders.

METHODS

In a large-scale population survey about physiological constants and health conditions, 75,714 subjects who aged from 8 to 80 completed body composition array. Body mass index (BMI), percentage body fat (PBF), water percentage of body weight (WPBW), water percentage of lean body mass (WPLBM), fat-free mass index (FFMI) and basic metabolic rate were examined with Biodynamics BI-310 body composition analyzer. General obesity is defined as BMI equal to or greater than 28 kg/m2.

RESULTS

The prevalence rates of general obesity were 9.4% for males and 7.7% for females respectively. With aging, PBF and FMI showed a U-shape curvilinear trend and WPBW showed a parabolic trend for males. At same age group: 18-19 age groups, PBF and FMI declined to the valley and WPBW rose to the peak. For females, PBF, WPBW and FMI changed in a linear trend. The values of WPLBM and FFMI showed same curvilinear trend for two genders. WPLBM changed in a U-shape trend and touched the valley in twenties for males and in 18-19 age groups for females. The value of FFMI was larger for older age groups in the younger generation but smaller in the older generation. A parabolic trend peaking was seen in the thirties for males and in the forties for females. Regression models with age as independent variable showed that the larger rate of increase of PBF and smaller rates of increase for WPBM and WPLBM with aging for males.

CONCLUSION

This study presents detailed data about sex-specific body composition conditions. Different change trend with aging was found about body composition conditions.

Metabolomics and Personalized Medicine

Current clinical practice strongly relies on the prognosis, diagnosis, and treatment of diseases using methods determined and averaged for the specific diseased cohort/population. Although this approach complies positively with most patients, misdiagnosis, treatment failure, relapse, and adverse drug effects are common occurrences in many individuals, which subsequently hamper the control and eradication of a number of diseases. These incidences can be explained by individual variation in the genome, transcriptome, proteome, and metabolome of a patient. Various "omics" approaches have investigated the influence of these factors on a molecular level, with the intention of developing personalized approaches to disease diagnosis and treatment. Metabolomics, the newest addition to the "omics" domain and the closest to the observed phenotype, reflects changes occurring at all molecular levels, as well as influences resulting from other internal and external factors. By comparing the metabolite profiles of two or more disease phenotypes, metabolomics can be applied to identify biomarkers related to the perturbation being investigated. These biomarkers can, in turn, be used to develop personalized prognostic, diagnostic, and treatment approaches, and can also be applied to the monitoring of disease progression, treatment efficacy, predisposition to drug-related side effects, and potential relapse. In this review, we discuss the contributions that metabolomics has made, and can potentially still make, towards the field of personalized medicine.

Alterations of plasma metabolite profiles related to adipose tissue distribution and cardiometabolic risk

Metabolomic profiling of obese individuals revealed altered concentrations of many metabolites, especially branched-chain amino acids (BCAA), possibly linked to altered adipose tissue BCAA catabolism. We tested the hypothesis that some features of this metabolite signature relate closely to visceral obesity and concomitant alterations in cardiometabolic risk factors. We also postulated that alterations in BCAA-catabolizing enzymes are predominant in visceral adipose tissue. Fifty-nine women (BMI 20-41 kg/m(2)) undergoing gynecologic surgery were recruited and characterized for overall and regional adiposity, blood metabolite levels using targeted metabolomics, and cardiometabolic risk factors. Adipose samples (visceral and subcutaneous) were obtained and used for gene expression and Western blot analyses. Obese women had significantly higher circulating BCAA and kynurenine/tryptophan (Kyn/Trp) ratio than lean or overweight women (P < 0.01). Principal component analysis confirmed that factors related to AA and the Kyn/Trp ratio were positively associated with BMI, fat mass, visceral or subcutaneous adipose tissue area, and subcutaneous adipocyte size (P ≤ 0.05). AA-related factor was positively associated with HOMA-IR (P ≤ 0.01). Factors reflecting glycerophospholipids and sphingolipids levels were mostly associated with altered blood lipid concentrations (P ≤ 0.05). Glutamate level was the strongest independent predictor of visceral adipose tissue area (r = 0.46, P < 0.001). Obese women had lower expression and protein levels of BCAA-catabolizing enzymes in visceral adipose tissue than overweight or lean women (P ≤ 0.05). We conclude that among metabolites altered in obesity plasma concentrations of BCAA and the Kyn/Trp ratio are closely related to increased adiposity. Alterations in expression and protein levels of BCAA-catabolizing enzymes are predominant in visceral adipose tissue.

Polymorphism in miR-31 and miR-584 binding site in the angiotensinogen gene differentially influences body fat distribution in both sexes

Angiotensinogen (AGT), its active fragments and microRNA-31 (miR-31) play an important role in adipocyte differentiation. AGT contains a miR-31 polymorphic binding site. We hypothesize that the rs7079 polymorphism in the miR-31/584 binding site of the AGT gene could influence body fat distribution. A total of 751 subjects (195 men, 556 women) were enrolled in the study. The rs7079 genotypes were determined by qRT-PCR. Anthropometric measurements were taken on all subjects, who were subsequently divided into two groups: obese (>30 kg m(-2)) and non-obese (<30 kg m(-2)). Linear regression models were created to determine the contributions of sex, obesity status and rs7079 to all measured parameters. Adding the rs7079 genotype significantly contributed to the linear regression model for waist circumference (p = 0.013), hip circumference (p = 0.018) and supraspinal skin-fold thickness (p = 1 × 10(-3)). Differences between sexes and between the obese and non-obese groups were observed. Waist circumference was lower in men carrying the A allele (p = 0.022); hip circumference was higher only in obese women carrying the A allele (p = 0.015). While men carrying the A allele had lower supraspinal skin-fold thickness (p = 0.022), this parameter was found to be higher in A allele carrying women (p = 3 × 10(-3)). The higher total sum of skin-fold thickness in A allele carrying women was restricted to obese individuals (p = 0.028). The presence of the A allele was associated with both lower tricipital skin-fold thickness in non-obese women (p = 0.023) and a trend of higher thickness in non-obese men (p = 0.065). Significant associations of rs7079 in the AGT gene and body fat distribution were observed. The distribution followed opposing patterns in both sexes.

Association of hypertension and obesity with renal cell carcinoma risk: a report from the Shanghai Men's and Women's Health Studies

PURPOSE

Consistently reported associations between hypertension and obesity and renal cell carcinoma (RCC) risk have largely come from studies in Western populations. These associations were examined in a case-control study nested in the Shanghai Women's Health Study (SWHS, 1996-2000) and Shanghai Men's Health Study (SMHS, 2001-2006).

METHODS

Overall, 271 incident RCC cases (124 women, 147 men) were identified through 31 December 2011, and 2,693 controls were individually matched by sex, age, and calendar time at cohort enrollment, and menopausal status (for women). Participants completed a structured questionnaire by in-person interview at baseline, and conditional logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs).

RESULTS

Self-reported hypertension was associated with a significant 40 % increased risk of RCC among women and men (95 % CI 1.1, 1.9). Body mass index (BMI), modeled continuously, was associated with an elevated risk of RCC among men, with an OR of 1.5 (95 % CI 1.1, 2.0) per 5 kg/m(2) increase in BMI, but not among women.

CONCLUSIONS

Hypertension is independently associated with risk of RCC among both women and men in Shanghai, while overweight and obesity appear to be associated with risk of RCC in Chinese men only.

NMR-based metabolomics highlights differences in plasma metabolites in pigs exhibiting diet-induced differences in adiposity

PURPOSE

A better understanding of the control of body fat mass and distribution is required for both human health and animal production. The current study investigates plasma parameters in response to changes in body fat mass.

METHODS

Pigs from two lines divergently selected for residual feed intake were fed diets contrasted in energy sources and nutrients. Between 74 and 132 days of age, pigs (n = 12 by diet and by line) received isoproteic and isoenergetic diets, either rich in starch (LF) or in lipids and fibres (HF). At the end of the feeding trial, plasma samples were analysed by (1)H NMR spectroscopy and standard hormonal and biochemical assays.

RESULTS

Pigs fed the HF diet had lower (P < 0.01) perirenal and subcutaneous adipose tissue relative masses than pigs fed the LF diet. Metabolomic approach showed a clear discrimination between diets, with lower (P < 0.05) plasma levels of creatinine-lysine, creatine, tyrosine, proline, histidine, lysine, phenylalanine and formate but higher (P < 0.001) plasma VLDL-LDL levels in HF pigs than in LF pigs. Plasma concentrations of triglycerides were higher (P < 0.001), while plasma concentrations of β-hydroxybutyrate, leptin, glucose, insulin and urea were lower (P ≤ 0.05) in HF pigs than in LF pigs. Plasma levels of leptin, creatine and urea were positively correlated (r = 0.3, P < 0.05) with relative adipose tissue masses.

CONCLUSION

These data indicate that metabolites associated with energy and protein metabolism were involved in the response to a high-fat, high-fibre diet. Relevant plasma indicators of metabolic flexibility related to changes in body adiposity were then proposed.

Blood plasma lipidomic signature of epicardial fat in healthy obese women

OBJECTIVES

A lipidomic approach was employed in a clinically well-defined cohort of healthy obese women to explore blood lipidome phenotype ascribed to body fat deposition, with emphasis on epicardial adipose tissue (EAT).

METHODS

The present investigation delivered a lipidomics signature of epicardial adiposity under healthy clinical conditions using a cohort of 40 obese females (age: 25-45 years, BMI: 28-40 kg/m(2) ) not showing any metabolic disease traits. Lipidomics analysis of blood plasma was employed in combination with in vivo quantitation of mediastinal fat depots by computerized tomography.

RESULTS

All cardiac fat depots correlated to indicators of hepatic dysfunctions (ALAT and ASAT), which describe physiological connections between hepatic and cardiac steatosis. Plasma lipidomics encompassed overall levels of lipid classes, fatty acid profiles, and individual lipid species. EAT and visceral fat associated with diacylglycerols (DAG), triglycerides, and distinct phospholipid and sphingolipid species. A pattern of DAG and phosphoglycerols was specific to EAT.

CONCLUSIONS

Human blood plasma lipidomics appears to be a promising clinical and potentially diagnostic readout for patient stratification and monitoring. Association of blood lipidomics signature to regio-specific mediastinal and visceral adiposity under healthy clinical conditions may help provide more biological insights into obese patient stratification for cardiovascular disease risks.

The metabolite profiles of the obese population are gender-dependent

Studies have identified that several amino acids, in particular, branched-chain amino acids (BCAAs), have increased significantly in obese individuals when compared to lean individuals. Additionally, these metabolites were strongly associated with future diabetes, which rendered them prognostic markers suitable for obese populations. Here we report a metabonomic study that reveals new findings on the role of these amino acid markers, particularly BCAAs, in a Chinese cohort including 106 healthy obese and 105 healthy lean participants. We found that the BCAAs were correlated with insulin resistance and differentially expressed in obese men, but not in obese women. The results were verified with two independent groups of participants (Chinese, n = 105 and American, n = 72) and demonstrate that the serum metabolite profiles of the obese population are gender-dependent. The study supports the previous findings of a panel of several key metabolites as prognostic markers of the obese population and highlights the need to take into account gender differences when using these markers for risk assessment.