Short-chain Acylcarnitine Levels Research Articles

Metabolic predictors of COVID-19 mortality and severity: a survival analysis.

The global healthcare burden of COVID-19 pandemic has been unprecedented with a high mortality. Metabolomics, a powerful technique, has been increasingly utilized to study the host response to infections and to understand the progression of multi-system disorders such as COVID-19. Analysis of the host metabolites in response to SARS-CoV-2 infection can provide a snapshot of the endogenous metabolic landscape of the host and its role in shaping the interaction with SARS-CoV-2. Disease severity and consequently the clinical outcomes may be associated with a metabolic imbalance related to amino acids, lipids, and energy-generating pathways. Hence, the host metabolome can help predict potential clinical risks and outcomes. In this prospective study, using a targeted metabolomics approach, we studied the metabolic signature in 154 COVID-19 patients (males=138, age range 48-69 yrs) and related it to disease severity and mortality. Blood plasma concentrations of metabolites were quantified through LC-MS using MxP Quant 500 kit, which has a coverage of 630 metabolites from 26 biochemical classes including distinct classes of lipids and small organic molecules. We then employed Kaplan-Meier survival analysis to investigate the correlation between various metabolic markers, disease severity and patient outcomes. A comparison of survival outcomes between individuals with high levels of various metabolites (amino acids, tryptophan, kynurenine, serotonin, creatine, SDMA, ADMA, 1-MH and carnitine palmitoyltransferase 1 and 2 enzymes) and those with low levels revealed statistically significant differences in survival outcomes. We further used four key metabolic markers (tryptophan, kynurenine, asymmetric dimethylarginine, and 1-Methylhistidine) to develop a COVID-19 mortality risk model through the application of multiple machine-learning methods. Metabolomics analysis revealed distinct metabolic signatures among different severity groups, reflecting discernible alterations in amino acid levels and perturbations in tryptophan metabolism. Notably, critical patients exhibited higher levels of short chain acylcarnitines, concomitant with higher concentrations of SDMA, ADMA, and 1-MH in severe cases and non-survivors. Conversely, levels of 3-methylhistidine were lower in this context.

Serum acylcarnitines levels as a potential predictor for gestational diabetes: a systematic review and meta-analysis.

Gestational diabetes mellitus (GDM) stands as a prevalent obstetric complication bearing consequential health implications for both mother and child. While existing studies have probed the alterations in acylcarnitines during GDM, an updated systematic meta-analysis is needed to consolidate these findings. Hence, this study endeavours to furnish a comprehensive systematic review and meta-analysis delineating the association between acylcarnitines and GDM, aimed at bolstering diagnostic accuracy and preventive measures against GDM. To extract pertinent studies for this meta-analysis, we meticulously scoured databases such as PubMed, Web of Science, Embase, and Cochrane Library up until May 2023. The inclusion criteria were studies contrasting plasma metabolomics between two cohorts: women diagnosed with GDM and normoglycemic pregnant women. Weighted mean differences (SMDs) and 95% confidence intervals (CIs) were calculated using random-effects models. The I2 index was employed to quantify heterogeneity amongst the studies. All meta-analyses were executed using Stata version 12.0. Our meta-analysis included eight studies encompassing 878 pregnant women. The analysis disclosed that relative to normoglycemic pregnant women, women with GDM exhibited significantly elevated levels of Short-Chain Acylcarnitines (SCAC) (SMD: 0.19, 95% CI: 0.02-0.36, I2 = 71.3%). No substantial difference was discerned in fasting total carnitine levels (SMD: 0.15, 95% CI: -0.16-0.31, I2 = 68.2%), medium-chain acylcarnitines (MCAC) (SMD: 0.08, 95% CI: -0.02-0.36, I2 = 79.0%), and long-chain acylcarnitines (LCAC) (SMD: 0.04, 95% CI: -0.06-0.15, I2 = 0%). Neither funnel plot assessment nor Egger's regression and Begg's rank correlation tests indicated any evidence of publication bias. Our meta-analysis suggests that elevated levels of SCAC may heighten the risk of GDM onset. Given GDM's deleterious impact on pregnant women and their offspring, these findings underscore the clinical imperative of managing this condition. Early surveillance of plasma metabolomic profiles, particularly serum acylcarnitine concentrations, may equip clinicians with a valuable tool for timely diagnosis and intervention in GDM.

Metabolic profiling of COVID-19 severity and mortality: A targeted metabolomics approach

Abstract The analysis of metabolites in response to SARS-CoV-2 infection provides a snapshot of the endogenous host metabolism and its role in shaping the interaction with SARS-CoV-2. In this study, using a targeted metabolomics approach, the metabolic signatures of severity and mortality were studied in COVID-19 patients. Our analysis revealed survival and severity-associated shifts in the metabolome of COVID-19 patients, where amino acids, particularly tryptophan and arginine, and fatty acid metabolism were altered in severe patients as compared to mild and asymptomatic cases. Herein, we also report alterations in the sums and ratios of several essential amino acids as well as kynurenine to tryptophan ratio, which is an indicator of indoleamine-2,3-dioxygenase (IDO) activity. Our findings suggest that metabolites of creatine including symmetric dimethylarginine, asymmetric dimethylarginine, and 1-methylhistidine can be used as biomarkers to identify patients at risk of poor outcomes in COVID-19, and that lower levels of these metabolites are associated with higher survival probabilities. Additionally, elevated levels of short chain acylcarnitines and carnitine palmitoyltransferase 1 and 2 enzymes indicators have been observed in critically ill COVID-19 patients, indicating their potential usefulness as predictors of hospital mortality and poor survival outcome, likely due to increased demand for energy, inflammation, and mitochondrial dysfunction. The metabolome analysis of COVID-19 patients can improve our understanding of disease severity by providing insight into the relationship between metabolites and disease progression, which can lead to the development of potential therapeutics and clinical risk models. This work was supported by Emergency Response Grant ID: 252

The association between acylcarnitine and amino acids profile and metabolic syndrome and its components in Iranian adults: Data from STEPs 2016.

Evidence, albeit with conflicting results, has suggested that cardiometabolic risk factors, including obesity, type 2 diabetes (T2D), dyslipidemia, and hypertension, are highly associated with changes in metabolic signature, especially plasma amino acids and acylcarnitines levels. Here, we aimed to evaluate the association of circulating levels of amino acids and acylcarnitines with metabolic syndrome (MetS) and its components in Iranian adults. This cross-sectional study was performed on 1192 participants from the large-scale cross-sectional study of Surveillance of Risk Factors of non-communicable diseases (NCDs) in Iran (STEP 2016). The circulating levels of amino acids and acylcarnitines were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in individuals with MetS (n=529) and without MetS (n=663). The higher plasma levels of branched-chain amino acids (Val, Leu), aromatic amino acids (Phe, Tyr), Pro, Ala, Glu, and the ratio of Asp to Asn were significantly associated with MetS, whereas lower circulating levels of Gly, Ser, His, Asn, and citrulline were significantly associated with MetS. As for plasma levels of free carnitine and acylcarnitines, higher levels of short-chain acylcarnitines (C2, C3, C4DC), free carnitine (C0), and long-chain acylcarnitines (C16, C18OH) were significantly associated with MetS. Principal component analysis (PCA) showed that factor 3 (Tyr, Leu, Val, Met, Trp, Phe, Thr) [OR:1.165, 95% CI: 1.121-1.210, P<0.001], factor 7 (C0, C3, C4) [OR:1.257, 95% CI: 1.150-1.374, P<0.001], factor 8 (Gly, Ser) [OR:0.718, 95% CI: 0.651-0.793, P< 0.001], factor 9 (Ala, Pro, C4DC) [OR:1.883, 95% CI: 1.669-2.124, P<0.001], factor 10 (Glu, Asp, C18:2OH) [OR:1.132, 95% CI: 1.032-1.242, P= 0.009], factor 11 (citrulline, ornithine) [OR:0.862, 95% CI: 0.778-0.955, P= 0.004] and 13 (C18OH, C18:1 OH) [OR: 1.242, 95% CI: 1.042-1.480, P= 0.016] were independently correlated with metabolic syndrome. Change in amino acid, and acylcarnitines profiles were seen in patients with MetS. Moreover, the alteration in the circulating levels of amino acids and acylcarnitines is along with an increase in MetS component number. It also seems that amino acid and acylcarnitines profiles can provide valuable information on evaluating and monitoring MetS risk. However, further studies are needed to establish this concept.

APOE ε4 and Alzheimer's disease diagnosis associated differences in L-carnitine, GBB, TMAO, and acylcarnitines in blood and brain

The apolipoprotein E (APOE) ε4 allele, involved in fatty acid (FA) metabolism, is a major genetic risk factor for Alzheimer's disease (AD). This study examined the influence of APOE genotypes on blood and brain markers of the L-carnitine system, necessary for fatty acid oxidation (FAO), and their collective influence on the clinical and pathological outcomes of AD. L-carnitine, its metabolites γ-butyrobetaine (GBB) and trimethylamine-n-oxide (TMAO), and its esters (acylcarnitines) were analyzed in blood from predominantly White community/clinic-based individuals (n = 372) and in plasma and brain from the Religious Order Study (ROS) (n = 79) using liquid chromatography tandem mass spectrometry (LC-MS/MS). Relative to total blood acylcarnitines, levels of short chain acylcarnitines (SCAs) were higher whereas long chain acylcarnitines (LCAs) were lower in AD, which was observed pre-clinically in APOE ε4s. Plasma medium chain acylcarnitines (MCAs) were higher amongst cognitively healthy APOE ε2 carriers relative to other genotypes. Compared to their respective controls, elevated TMAO and lower L-carnitine and GBB were associated with AD clinical diagnosis and these differences were detected preclinically among APOE ε4 carriers. Plasma and brain GBB, TMAO, and acylcarnitines were also associated with post-mortem brain amyloid, tau, and cerebrovascular pathologies. Alterations in blood L-carnitine, GBB, TMAO, and acylcarnitines occur early in clinical AD progression and are influenced by APOE genotype. These changes correlate with post-mortem brain AD and cerebrovascular pathologies. Additional studies are required to better understand the role of the FAO disturbances in AD.

Correlation between Acylcarnitine and Peripheral Neuropathy in Type 2 Diabetes Mellitus.

Objective In patients with type 2 diabetes mellitus (T2DM), it is unknown whether acylcarnitine changes in the patient's plasma as diabetic peripheral neuropathy (DPN) occurs. The purpose of the present study was to investigate the correlation between acylcarnitines and DPN in Chinese patients with T2DM. Methods A total of 508 patients admitted to the First Affiliated Hospital of Jinzhou Medical University were included in this study, and all of whom were hospitalized for T2DM from January 2018 to December 2020. The diagnostic criteria for DPN were based on the 2017 Chinese Guidelines for the Prevention of Type 2 Diabetes. The contents of 25 acylcarnitine metabolites in fasting blood were determined by mass spectrometry. The measured acylcarnitines were classified by factor analysis, and the factors were extracted. To determine the correlation between acylcarnitines and DPN, binary logistic regression analysis was applied. Results Among the 508 T2DM patients, 270 had DPN. Six factors were extracted from 25 acylcarnitines, and the cumulative contribution rate of variance was 61.02%. After the adjustment for other potential confounding factors, such as other carnitines and conventional risk factors, Factor 2 was positively associated with an increased risk of DPN (OR: 1.38, 95% CI: 1.13-1.69). Factor 2 contained acetylcarnitine (C2), propionylcarnitine (C3), butylcarnitine (C4), and isovalerylcarnitine (C5). Conclusions Plasma levels of short-chain acylcarnitines (C2, C3, C4, and C5) were positively associated with DPN risk.

Alterations in acylcarnitines, amines, and lipids inform about the mechanism of action of citalopram/escitalopram in major depression

Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for major depressive disorder (MDD), yet their mechanisms of action are not fully understood and their therapeutic benefit varies among individuals. We used a targeted metabolomics approach utilizing a panel of 180 metabolites to gain insights into mechanisms of action and response to citalopram/escitalopram. Plasma samples from 136 participants with MDD enrolled into the Mayo Pharmacogenomics Research Network Antidepressant Medication Pharmacogenomic Study (PGRN-AMPS) were profiled at baseline and after 8 weeks of treatment. After treatment, we saw increased levels of short-chain acylcarnitines and decreased levels of medium-chain and long-chain acylcarnitines, suggesting an SSRI effect on β-oxidation and mitochondrial function. Amines—including arginine, proline, and methionine sulfoxide—were upregulated while serotonin and sarcosine were downregulated, suggesting an SSRI effect on urea cycle, one-carbon metabolism, and serotonin uptake. Eighteen lipids within the phosphatidylcholine (PC aa and ae) classes were upregulated. Changes in several lipid and amine levels correlated with changes in 17-item Hamilton Rating Scale for Depression scores (HRSD17). Differences in metabolic profiles at baseline and post-treatment were noted between participants who remitted (HRSD17 ≤ 7) and those who gained no meaningful benefits (<30% reduction in HRSD17). Remitters exhibited (a) higher baseline levels of C3, C5, alpha-aminoadipic acid, sarcosine, and serotonin; and (b) higher week-8 levels of PC aa C34:1, PC aa C34:2, PC aa C36:2, and PC aa C36:4. These findings suggest that mitochondrial energetics—including acylcarnitine metabolism, transport, and its link to β-oxidation—and lipid membrane remodeling may play roles in SSRI treatment response.

Dysregulated Lipid and Fatty Acid Metabolism link Perfluoroalkyl Substances Exposure and Impaired Glucose Metabolism in Young Adults

The aim of this project is to investigate the association between perfluoroalkyl substances (PFAS) exposure and altered metabolic pathways linked to increased cardiometabolic risk in young adults. The study population comprised 102 young adults (17-22 years, 60% Hispanic) enrolled in Southern California during 2014-2017. A spectrum of cardiometabolic outcomes were measured including oral glucose tolerance test (OGTT) measures, body fat percent, ectopic fat, and lipid profiles. High-resolution metabolomics was used to quantify plasma exposure levels of three PFAS congeners and intensity profiles of the untargeted metabolome. Fasting concentrations of 45 targeted metabolites involved in key metabolic pathways including fatty acid and lipid were used to replicate untargeted metabolomics findings. Bayesian Kernel Machine Regression (BKMR) was used to examine the associations between PFAS exposure mixture and cardiometabolic outcomes adjusting for covariates. Metabolome-wide association analysis followed by Mummichog pathway analysis were used to explore PFAS-associated metabolic pathways. Furthermore, the effect of PFAS exposure on the entire metabolic network including metabolomic profiles and multiple cardiometabolic traits were investigated by integrated network analysis. Higher exposure to perfluorooctanoic acid (PFOA) was associated with higher 30-minute glucose levels and glucose AUC during OGTTs (p&lt;0.001). These associations were stronger among Hispanic participants. PFAS exposure was also associated with altered lipid pathways, including glycerophospholipid, glycosphingolipid and unsaturated fatty acids, which could contribute to the link between PFOA and higher glucose levels after OGTTs. Targeted metabolomics analysis further supported the findings that higher PFOA exposure was associated with higher levels of glycerol and short-chain acylcarnitines (p=0.004 and 0.046, respectively), which themselves were also associated with higher 30-min glucose (p&lt;0.01). In conclusion, increased lipolysis and fatty acid oxidation could contribute to the biological mechanism linking PFAS exposure and impaired glucose metabolism among youth. The Hispanic population may be more susceptible to the adverse effect of PFAS on glucose metabolism.

Intramuscular short-chain acylcarnitines in elderly people are decreased in (pre-)frail females, but not in males.

This study tested the hypothesis that in human aging, a decreased intramuscular acylcarnitine status is associated with (pre-)frailty, reduced physical performance, and altered mitochondrial function. We used a cross-sectional study design with well-matched fit and (pre-)frail old males and females, using young males and females as healthy controls. Frailty was assessed according to the Fried criteria and physical performance was determined by 400m walk test, short physical performance battery and handgrip strength. Muscle and plasma acylcarnitine status, and muscle mitochondrial gene expression was analyzed. Results showed that intramuscular total carnitine levels and short-chain acylcarnitine levels were lower in (pre-)frail old females compared to fit old females and young females, whereas no differences were observed in males. The low intramuscular short-chain acylcarnitine levels in females correlated with low physical performance, even after correction for muscle mass (%), and were accompanied with lowered expression of genes involved in mitochondrial energy production and functionality. It is, therefore, concluded that in (pre-)frail old females, intramuscular total carnitine levels and short-chain acylcarnitine levels are decreased, and this decrease is associated with reduced physical performance and low expression of a wide range of genes critical for mitochondrial function. The results stress the importance of taking sex differences into account in aging research.

Functional changes of the liver in the absence of growth hormone (GH) action – Proteomic and metabolomic insights from a GH receptor deficient pig model

ObjectiveThe liver is a central target organ of growth hormone (GH), which stimulates the synthesis of insulin-like growth factor 1 (IGF1) and affects multiple biochemical pathways. A systematic multi-omics analysis of GH effects in the liver has not been performed. GH receptor (GHR) deficiency is a unique model for studying the consequences of lacking GH action. In this study, we used molecular profiling techniques to capture a broad spectrum of these effects in the liver of a clinically relevant large animal model for Laron syndrome. MethodsWe performed holistic proteome and targeted metabolome analyses of liver samples from 6-month-old GHR-deficient (GHR-KO) pigs and GHR-expressing controls (four males, four females per group). ResultsGHR deficiency resulted in an increased abundance of enzymes involved in amino acid degradation, in the urea cycle, and in the tricarboxylic acid cycle. A decreased ratio of long-chain acylcarnitines to free carnitine suggested reduced activity of carnitine palmitoyltransferase 1A and thus reduced mitochondrial import of fatty acids for beta-oxidation. Increased levels of short-chain acylcarnitines in the liver and in the circulation of GHR-KO pigs may result from impaired beta-oxidation of short-chain fatty acids or from increased degradation of specific amino acids. The concentration of mono-unsaturated glycerophosphocholines was significantly increased in the liver of GHR-KO pigs without morphological signs of steatosis, although the abundances of several proteins functionally linked to non-alcoholic fatty liver disease (fetuin B, retinol binding protein 4, several mitochondrial proteins) were increased. Moreover, GHR-deficient liver samples revealed distinct changes in the methionine and glutathione metabolic pathways, in particular, a significantly increased level of glycine N-methyltransferase and increased levels of total and free glutathione. Several proteins revealed a sex-related abundance difference in the control group but not in the GHR-KO group. ConclusionsOur integrated proteomics/targeted metabolomics study of GHR-deficient and control liver samples from a clinically relevant large animal model identified a spectrum of biological pathways that are significantly altered in the absence of GH action. Moreover, new insights into the role of GH in the sex-related specification of liver functions were provided.

Acylcarnitine metabolomic profiles inform clinically-defined major depressive phenotypes

BackgroundAcylcarnitines have important functions in mitochondrial energetics and β-oxidation, and have been implicated to play a significant role in metabolic functions of the brain. This retrospective study examined whether plasma acylcarnitine profiles can help biochemically distinguish the three phenotypic subtypes of major depressive disorder (MDD): core depression (CD+), anxious depression (ANX+), and neurovegetative symptoms of melancholia (NVSM+). MethodsDepressed outpatients (n = 240) from the Mayo Clinic Pharmacogenomics Research Network were treated with citalopram or escitalopram for eight weeks. Plasma samples collected at baseline and after eight weeks of treatment with citalopram or escitalopram were profiled for short-, medium- and long-chain acylcarnitine levels using AbsoluteIDQ®p180-Kit and LC-MS. Linear mixed effects models were used to examine whether acylcarnitine levels discriminated the clinical phenotypes at baseline or eight weeks post-treatment, and whether temporal changes in acylcarnitine profiles differed between groups. ResultsCompared to ANX+, CD+ and NVSM+ had significantly lower concentrations of short- and long-chain acylcarnitines at both baseline and week 8. In NVSM+, the medium- and long-chain acylcarnitines were also significantly lower in NVSM+ compared to ANX+. Short-chain acylcarnitine levels increased significantly from baseline to week 8 in CD+ and ANX+, whereas medium- and long-chain acylcarnitines significantly decreased in CD+ and NVSM+. ConclusionsIn depressed patients treated with SSRIs, β-oxidation and mitochondrial energetics as evaluated by levels and changes in acylcarnitines may provide the biochemical basis of the clinical heterogeneity of MDD, especially when combined with clinical characteristics.

Higher dietary protein intake preserves lean body mass, lowers liver lipid deposition, and maintains metabolic control in participants with long-chain fatty acid oxidation disorders.

Medical nutrition therapy for long-chain fatty acid oxidation disorders (LC-FAODs) currently emphasizes fasting avoidance, restricted dietary long-chain fatty acid intake, supplementation with medium chain triglycerides, and increased carbohydrate intake. We hypothesize that increasing dietary protein intake relative to carbohydrate intake would preserve metabolic control yet induce physical benefits including reduced hepatic lipogenesis. Therefore, we compared two dietary approaches with similar fat intake but different carbohydrate to protein ratios in participants diagnosed with LC-FAODs. Thirteen participants were enrolled and randomized into either a high-protein (PRO) or a high-carbohydrate (CHO) diet for 4 months. Baseline and 4-month assessments included body composition, ectopic lipid deposition, and resting energy expenditure. End of study assessments also included total energy expenditure, metabolic responses to oral feedings, and whole-body fatty acid oxidation capacity. At the end of the dietary intervention, both groups had similar energy expenditure, fat and glucose oxidation rates, and glucolipid responses to mixed meal and oral glucose loads. Neither dietary group experienced worsening symptoms related to their LC-FAOD. Compared to the CHO group, the PRO group exhibited increased blood levels of short-chain acylcarnitines, reduced intrahepatic lipid content, and maintained lean body mass while the CHO group lost lean mass. In patients with LC-FAODs, increasing protein intake maintained metabolic control, reduced liver fat without risk of metabolic decompensation, and helped preserve lean body mass. We propose that a modest increase in dietary protein along with fasting avoidance and fat restriction may improve body composition and energy expenditure in patients with LC-FAODs.

Associations Between Dietary Protein Sources, Plasma BCAA and Short-Chain Acylcarnitine Levels in Adults.

Elevated plasma branched-chain amino acids (BCAA) and C3 and C5 acylcarnitines (AC) levels observed in individuals with insulin resistance (IR) might be influenced by dietary protein intakes. This study explores the associations between dietary protein sources, plasma BCAA levels and C3 and C5 ACs in normal weight (NW) or overweight (OW) individuals with or without metabolic syndrome (MS). Data from 199 men and women aged 18–55 years with complete metabolite profile were analyzed. Associations between metabolic parameters, protein sources, plasma BCAA and AC levels were tested. OW/MS+ consumed significantly more animal protein (p = 0.0388) and had higher plasma BCAA levels (p < 0.0001) than OW/MS− or NW/MS− individuals. Plasma BCAA levels were not associated with BCAA intakes in the whole cohort, while there was a trend for an association between plasma BCAA levels and red meat or with animal protein in OW/MS+. These associations were of weak magnitude. In NW/MS− individuals, the protein sources associated with BCAA levels varied greatly with adjustment for confounders. Plasma C3 and C5 ACs were associated with plasma BCAA levels in the whole cohort (p < 0.0001) and in subgroups based on OW and MS status. These results suggest a modest association of meat or animal protein intakes and an association of C3 and C5 ACs with plasma BCAA levels, obesity and MS.

Abstract P201: Associations of Plasma Acylcarnitines With Incident Carotid Artery Plaque in Individuals With or at Risk of HIV Infection

Introduction: Altered acylcarnitine concentrations may reflect impaired mitochondrial metabolism and are implicated in cardiovascular disease (CVD). Disturbances in carnitine metabolism have been observed in HIV infection, but it is unknown whether this is related to CVD risk in HIV infected people. Methods: Twenty-six acylcarnitine species were profiled with ultrahigh-performance liquid chromatography/tandem mass spectrometry in 705 men and women with or at risk of HIV infection in the Multicenter AIDS Cohort Study and the Women’s Interagency HIV Study. Using a weighted score approach to define aggregate levels of plasma acylcarnitines, we assessed the associations of short-chain (C2-C7), medium-chain (C8-C14) and long-chain acylcarnitine (C16-C26) with incident carotid plaque, over 7-year follow-up, defined as a carotid artery region with focal intima-media thickness&gt;1.5mm among those with no baseline carotid plaque. Results: The mean age was 45 years and 70% were non-white. The majority (70%) had HIV, and 68% of 394 participants on antiretroviral therapy (ART) had undetectable HIV viral load. Over 7 years, 108 participants developed carotid plaque. Comparing HIV-infected with HIV-uninfected participants, some individual acylcarnitines were higher (C3, C16, C20, C26) while others were lower (C8, C10, C20:4) (all P &lt;0.05), but no significant differences were found in aggregate levels of short-chain, medium-chain, or long-chain acylcarnitines. After adjusted for demographic, behavioral, and HIV infection related factors (HIV serostatus, CD4 cell count and ART), plasma levels of short-chain (risk ratio [RR] = 1.26 [95% CI 1.06-1.50] per standard deviation increment; P=0.008), medium-chain(RR=1.20 [1.01-1.43]; P=0.04) and long-chain acylcarnitines (RR=1.18 [1.00-1.40]; P=0.05) were associated with increased risk of carotid plaque. After further adjusting for traditional CVD risk factors (BMI, total- and HDL-cholesterol, blood pressure, lipid-lowering medication and antihypertensive medication use), the association of short-chain acylcarnitines, but not medium-chain or long-chain acylcarnitines, with carotid plaque remained significant (RR=1.23 [1.04-1.46]; P=0.01). Results were consistent between men and women. Further analyses indicated that the association of short-chain acylcarnitines and carotid plaque was stronger in individuals with HIV infection (RR=1.29 [1.08-1.54]) than those without HIV infection (RR=0.98 [0.66-1.45]), and stronger among HIV+ individuals with detectable viral load (RR =1.42 [1.15-1.75]) than those who had continuous virus suppression (RR =1.02 [0.71-1.47]). Conclusion: Plasma short-chain acylcarnitines were associated with increased risk of carotid plaque formation, independent of traditional CVD risk factors, especially in HIV-infected individuals and those with poor control of HIV viral load.

Similarities between acylcarnitine profiles in large for gestational age newborns and obesity

Large for gestational age (LGA) newborns have an increased risk of obesity, insulin resistance, and metabolic syndrome. Acylcarnitine profiles in obese children and adults are characterized by increased levels of C3, C5, and certain medium-chain (C12) and long-chain (C14:1 and C16) acylcarnitines. C2 is also increased in insulin-resistant states. In this 1-year observational study of 2514 newborns (246 LGA newborns, 250 small for gestational age (GA) newborns, and 2018 appropriate for GA newborns), we analyzed and compared postnatal acylcarnitine profiles in LGA newborns with profiles described for obese individuals. Acylcarnitine analysis was performed by tandem mass spectrometry on dried-blood spots collected on day 3 of life. LGA newborns had higher levels of total short-chain acylcarnitines (p < 0.001), C2 (p < 0.01) and C3 (p < 0.001) acylcarnitines, and all C12, C14, and C16 acylcarnitines except C12:1. They also had a higher tendency towards carnitine insufficiency (p < 0.05) and carnitine deficiency (p < 0.001). No significant differences were observed between LGA newborns born to mothers with or without a history of gestational diabetes. This novel study describes a postnatal acylcarnitine profile in LGA with higher levels of C2, C3, total acylcarnitines, and total short-chain acylcarnitines that is characteristic of childhood and adult obesity and linked to an unhealthy metabolic phenotype.

Treatment of Swedish Patients with Graves' Hyperthyroidism Is Associated with Changes in Acylcarnitine Levels.

Hyperthyroidism is associated with alterations in metabolism that are currently only partially understood. The objective of the study was to investigate changes in metabolism associated with reinstatement of euthyroidism in Swedish patients. Eighty metabolites in plasma were profiled from 10 subjects with Graves' disease (GD) at baseline and after 9 and 15 months of treatment to reinstate euthyroidism. Thyroid parameters, thyrotropin (TSH), TSH receptor antibodies, free triiodothyronine, and free thyroxine were followed. Main findings were validated in plasma from 20 subjects with GD at baseline and at three, six, and nine months. The study was conducted at the endocrinology clinic in Malmö, Sweden. Euthyroidism was reinstated at three months, and thyroid status did not change further during the 15-month follow-up. This was paralleled by altered levels of 9/19 detected acylcarnitines (p < 0.05 after adjustment for multiple testing). Levels of short-chain acylcarnitines were decreased, intermediate-chain acylcarnitines elevated, and long-chain acylcarnitines unaltered. GD and treatment of the disease is associated with pronounced acyl chain length-dependent alterations in acylcarnitine levels. These changes may be impacted by ethnicity and or dietary differences.

A metabolomics-driven approach reveals metabolic responses and mechanisms in the rat heart following myocardial infarction

BackgroundMyocardial infarction (MI) is caused by myocardial necrosis resulting from prolonged ischemia. However, the biological mechanisms underlying MI remain unclear. MethodsWe evaluated metabolic and lipidomic changes in rat heart tissue from sham and MI at 1h, 1day and 10day after coronary ligation, using global profiling based on metabolomics. ResultsA time-dependent increase or decrease in polar and lipid metabolite levels was measured. The S-adenosylmethionine (SAM) concentration and the SAM/S-adenosylhomocysteine (SAH) ratio gradually decreased in a time-dependent manner and were significantly downregulated 10days after MI. Transcriptome analysis revealed that the levels of coenzyme Q (Coq)-3 and Coq5, both of which are SAM-dependent methyltransferases, were decreased in the MI groups. These results suggested that dysregulation of SAM may be related to down regulated COQ biosynthetic pathway. In addition, short-chain (C3) and medium-chain (C4–C12) acylcarnitine levels gradually decreased, whereas long-chain acylcarnitine (C14–18) levels increased, owing to a defect in β-oxidation during ischemia. These changes are related to energy-dependent metabolic pathways, and a subsequent decrease in adenosine triphosphate concentration was observed. ConclusionsThe comprehensive integration of various omics data provides a novel means of understanding the underlying pathophysiological mechanisms of MI.

Abstract LB-200: Integrating dynamic 18F-FDG PET-CT, tumor metabolomics and functional genomics to understand metformin's pharmacodynamic effects in breast cancer: results of a phase 0 clinical trial

Abstract There is growing interest in the anticancer effect of the diabetes drug, metformin, and over 100 clinical trials are underway worldwide. However it is still not determined as to whether metformin has significant direct effects on cancer cells or solely indirect effects via modulation of host metabolism. We recruited 41 non-diabetic patients with primary breast cancer to a neoadjuvant window trial. Patients received an escalating dose of metformin (500mg up to 1500mg) for 2 weeks with pre- and post-metformin pharmacodynamic assessments including, dynamic 18F-FDG PET-CT scans, serum metabolic markers, and tumour biopsies for whole transcriptome RNASeq, tumour metabolomics and immunohistochemistry. Assessment of tumour FDG kinetics using a classic 2-tissue compartment model with three rate constants showed a 1.3 fold change (FC) post-metformin in the composite 18F-FDG flux constant, Kflux (p = 0.041, on paired t-test). There was a non-statistically significant 1.1 fold increase in the variable, metabolic rate of glucose utilization (MRglu) (p = 0.141). Mass spectrometry analysis revealed a decrease in intra-tumoral levels of the short-chain acyl-carnitines, propionylcarnitine (FC -0.50, p = 0.039) and acetylycarnitine (FC -0.40, p = 0.046) consistent with inhibition of fatty acid oxidation (wilcoxon rank test). This effect on fatty acid oxidation was validated in pre-clinical in vitro and in vivo breast cancer cell line models. There was a statistically significant positive correlation between the actual difference in Kflux and intratumoral levels of acetylcarnitine (p = 0.012, Spearman's rank test). Small but consistent falls in the levels of serum glucose (p = 0.032), c-peptide (p = 0.001), insulin (p = 0.005), IGF1 (p = 0.048) and IGF2 (p = 0.040) were observed following metformin treatment (paired t-test) but there was no correlation with change in Kflux or short chain acyl-carnitine levels. Pathway annotation analysis using GeneCodis revealed several pathways associated with mitochondrial and fatty acid metabolism that were upregulated. Immunohistochemical intratumoral nuclear expression of pAMPK increased 1.5 fold (p = 0.037, paired t-test) but this did not correlate with change in Kflux or levels of short-chain acyl-carnitines. Peak serum metformin levels correlated with intratumoral metformin levels (p = 0.012, Spearman's rank test) but did not correlate with change in Kflux or short-chain acyl-carnitine levels. Our data shows that metformin treatment alters FDG kinetics, inhibits fatty acid oxidation and leads to altered gene expression in the mitochondrial (nuclear encoded) transcriptome but that these effects do not correlate with changes in host metabolism. This data provides strong evidence that metformin has a direct effect on breast cancer metabolism at clinical doses. Citation Format: Simon Lord, Daniel Liu, Syed Haider, Edoardo Gaude, Eugene Teoh, Patel Neel, Qifeng Zhang, Fergus Gleeson, Michael Wakelam, Christian Frezza, Francesca Buffa, Fenwick John, Adrian Harris. Integrating dynamic 18F-FDG PET-CT, tumor metabolomics and functional genomics to understand metformin's pharmacodynamic effects in breast cancer: results of a phase 0 clinical trial. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-200.

Metabolic heritability at birth: implications for chronic disease research.

Recent genome-wide association studies of the adult human metabolome have identified genetic variants associated with relative levels of several acylcarnitines, which are important clinical correlates for chronic conditions such as type 2 diabetes and obesity. We have previously shown that these same metabolite levels are highly heritable at birth; however, no studies to our knowledge have examined genetic associations with these metabolites measured at birth. Here, we examine, in 743 newborns, 58 single nucleotide polymorphisms (SNPs) in 11 candidate genes previously associated with differing relative levels of short-chain acylcarnitines in adults. Six SNPs (rs2066938, rs3916, rs3794215, rs555404, rs558314, rs1799958) in the short-chain acyl-CoA dehydrogenase gene (ACADS) were associated with neonatal C4 levels. Most significant was the G allele of rs2066938, which was associated with significantly higher levels of C4 (P = 1.5 × 10(-29)). This SNP explains 25 % of the variation in neonatal C4 levels, which is similar to the variation previously reported in adult C4 levels. There were also significant (P < 1 × 10(-4)) associations between neonatal levels of C5-OH and SNPs in the solute carrier family 22 genes (SLC22A4 and SLC22A5) and the 3-methylcrotonyl-CoA carboxylase 1 gene (MCCC1). We have replicated, in newborns, SNP associations between metabolic traits and the ACADS and SLC22A4 genes observed in adults. This research has important implications not only for the identification of rare inborn errors of metabolism but also for personalized medicine and early detection of later life risks for chronic conditions.

Distribution of endogenous and exogenous carnitine inrats with sepsis and acute liver failure

The distribution of carnitine was investigated in male Wistar rats with sepsis or acute liver failure. Sepsis was produced by cecal ligation and puncture, while acute liver failure was induced by intraperitoneal injection of carbon tetrachloride. Then 14C-carnitine or L-carnitine was injected intravenously. In healthy control rats and rats with sepsis, both 14C-radioactivity and carnitine were increased in the liver and kidneys. When the carnitine fractions were investigated, it was found that free carnitine and short-chain acylcarnitine were increased. In the rats with acute liver failure, 14C-radioactivity decreased in the liver, but carnitine increased, with free carnitine and short-chain acylcarnitine levels rising. These findings suggested that exogenous free carnitine accumulated directly in the organs with carnitine deficiency in rats with sepsis and acute liver failure. In addition, there was differential regulation of the fractions of both exogenous and endogenous carnitine (free carnitine, short-chain acylcarnitine, and long-chain acylcarnitine). Furthermore, the distribution of exogenous carnitine differed between sepsis and acute liver failure.