Acylcarnitines Research Articles

Plasma Acylcarnitines as Metabolic Signatures of Declining Health-Related Quality of Life Measure in Community-Dwelling Older Adults: A Combined Cross-sectional and Longitudinal Pilot Study.

Health-related quality of life (HRQoL) measures are predictors of adverse health outcomes in older adults. Studies have demonstrated cross-sectional associations between HRQoL measures and blood-based biochemical markers. Acylcarnitines (ACs) are a class of metabolites generated in the mitochondria and are predictive of multiple geriatric syndromes. Changes in ACs reflect alterations in central carbon metabolic pathways. However, the prospective relationship between plasma ACs and declining HRQoL has not been examined. This study aimed to investigate both cross-sectional and longitudinal associations of baseline ACs with baseline and declining EuroQol-5 Dimension/EuroQol Visual Analogue Scale (EQ-5D/EQ-VAS) in community-dwelling older adults. One hundred and twenty community-dwelling older adults with EQ-5D/EQ-VAS measurements at baseline and follow-up were included. We quantified ACs at baseline using targeted plasma metabolomics profiling. Multivariate regressions were performed to examine cross-sectional and longitudinal associations between the measures. Cross-sectionally, ACs showed no significant associations with either EQ-5D index or EQ-VAS scores. Longitudinally, multiple baseline short-chain ACs were significantly and inversely associated with declining EQ-5D index score, explaining up to 8.5% of variance in the decline. Within a cohort of community-dwelling older adults who had high HRQoL at baseline, we showed that higher levels of short-chain ACs are longitudinally associated with declining HRQoL. These findings reveal a novel association between central carbon metabolic pathways and declining HRQoL. Notably, dysregulation in mitochondrial central carbon metabolism could be detected prior to clinically important decline in HRQoL, providing the first evidence of objective biomarkers as novel predictors to monitor HRQoL in nonpharmacological interventions and epidemiology.

Lymphocyte Medium-Chain Acyl-CoA Dehydrogenase Activity and Its Potential as a Diagnostic Confirmation Tool in Newborn Screening Cases.

The determination of acylcarnitines (AC) in dried blood spots (DBS) by tandem mass spectrometry in newborn screening (NBS) programs has enabled medium-chain acyl-coA dehydrogenase deficiency (MCADD) to be identified in presymptomatic newborns. Nevertheless, different confirmatory tests must be performed to confirm the diagnosis. In this work, we have collected and analyzed the NBS results and confirmatory test results (plasma AC, molecular findings, and lymphocyte MCAD activity) of forty individuals, correlating them with clinical outcomes and treatment, with the aim of obtaining useful diagnostic information that could be applied in the follow-up of the patients. Our results led us to classify patients into two groups. The first group (14 cases) had high increased octanoylcarnitine (C8) levels, biallelic pathogenic variants, and severe impaired enzyme activity (<10% of the intra-assay control (IAC)); all of these cases received nutritional therapy and required carnitine supplementation during follow-up, representing the most severe form of the disease. The second group (16 patients) was a heterogeneous group presenting moderate increases in C8, biallelic likely pathogenic/pathogenic variants, and intermediate activity (<41% IAC). All of them are currently asymptomatic and could be considered as having a milder form of the disease. Finally, eight cases presented a normal–mild increase in plasma C8, with only one pathogenic variant detected, and high–intermediate residual activity (15–100%). Based on our results, we confirm that combined evaluation of acylcarnitine profiles, genetic findings, and residual enzyme activities proves useful in predicting the risk of future metabolic decompensation, in making decisions regarding future treatment or follow-up, and also in confirming the clinical effects of unknown clinical variants.

Serum Microelements, Amino Acids and Acyl Carnitines Levels in Pregnancies Complicated with Preeclampsia: A Prospective Study

Background: To evaluate the feasibility of serum microelements, amino acids and acyl carnitine levels to predict maternal complications and adverse infant outcomes in pregnancies complicated by preeclampsia. Methods: We launched a prospective study including 81 pregnant patients. Serum microelements, amino acids and acyl carnitine levels were tested using external calibration technique or high-performance liquid chromatography tandem mass spectrometry. Concentrations of metabolites were compared between the preeclampsia and control groups. Logistic regression models were used to assess the relevance between the metabolites and pregnancy outcomes in preeclampsia patients without severe features. Results: Concentrations of some microelements, amino acids and acyl carnitines were significantly higher or lower in preeclampsia patients. Women with severe preeclampsia had significantly lower (hexadecanoyl carnitine + octadecenoyl carnitine)/acetyl carnitine [(C16 + C18:1)/C2] compared to mothers without severe features. Lower (C16 + C18:1)/C2 was found in women who developed maternal complications (p = 0.07) or experienced adverse infant outcomes (p &lt; 0.01) compared with those who did not in patients without severe features. Levels of (C16 + C18:1)/C2 at enrollment resulted in moderate prediction rates for maternal outcomes [areas under the curves (AUC) 0.746, 95% Confidence Interval (CI) 0.543, 0.948] and perinatal outcomes (AUC 0.871, 95% CI 0.729, 1.000). Conclusions: Maternal levels of microelements, amino acids and acyl carnitines were associated with preeclampsia. Levels of (C16 + C18:1)/C2 seemed to be a potential biomarker in the prediction of maternal complications and adverse infant outcomes in preeclampsia patients without severe features. Further studies are needed to validate its predictive application.

Metabolomic Profiling in Patients with Heart Failure and Exercise Intolerance: Kynurenine as a Potential Biomarker.

Aims: Metabolic and structural perturbations in skeletal muscle have been found in patients with heart failure (HF) both with preserved (HFpEF) and reduced (HFrEF) ejection fraction in association with reduced muscle endurance (RME). We aimed in the current study to create phenotypes for patients with RME and HFpEF compared to RME HFrEF according to their metabolomic profiles and to test the potential of Kynurenine (Kyn) as a marker for RME. Methods: Altogether, 18 HFrEF, 17 HFpEF, and 20 healthy controls (HC) were prospectively included in the current study. The following tests were performed on all participants: isokinetic muscle function tests, echocardiography, spiroergometry, and varied blood tests. Liquid chromatography tandem mass spectrometry was used to quantify metabolites in serum. Results: Except for aromatic and branched amino acids (AA), patients with HF showed reduced AAs compared to HC. Further perturbations were elevated concentrations of Kyn and acylcarnitines (ACs) in HFpEF and HFrEF patients (p < 0.05). While patients with HFpEF and RME presented with reduced concentrations of ACs (long- and medium-chains), those with HFrEF and RME had distorted AAs metabolism (p < 0.05). With an area under the curve (AUC) of 0.83, Kyn shows potential as a marker in HF and RME (specificity 70%, sensitivity 83%). In a multiple regression model consisting of short-chain-ACs, spermine, ornithine, glutamate, and Kyn, the latest was an independent predictor for RME (95% CI: −13.01, −3.30, B: −8.2 per 1 µM increase, p = 0.001). Conclusions: RME in patients with HFpEF vs. HFrEF proved to have different metabolomic profiles suggesting varied pathophysiology. Kyn might be a promising biomarker for patients with HF and RME.

Defects in the Proteome and Metabolome in Human Hypertrophic Cardiomyopathy.

Defects in energetics are thought to be central to the pathophysiology of hypertrophic cardiomyopathy (HCM); yet, the determinants of ATP availability are not known. The purpose of this study is to ascertain the nature and extent of metabolic reprogramming in human HCM, and its potential impact on contractile function. We conducted proteomic and targeted, quantitative metabolomic analyses on heart tissue from patients with HCM and from nonfailing control human hearts. In the proteomic analysis, the greatest differences observed in HCM samples compared with controls were increased abundances of extracellular matrix and intermediate filament proteins and decreased abundances of muscle creatine kinase and mitochondrial proteins involved in fatty acid oxidation. These differences in protein abundance were coupled with marked reductions in acyl carnitines, byproducts of fatty acid oxidation, in HCM samples. Conversely, the ketone body 3-hydroxybutyrate, branched chain amino acids, and their breakdown products, were all significantly increased in HCM hearts. ATP content, phosphocreatine, nicotinamide adenine dinucleotide and its phosphate derivatives, NADP and NADPH, and acetyl CoA were also severely reduced in HCM compared with control hearts. Functional assays performed on human skinned myocardial fibers demonstrated that the magnitude of observed reduction in ATP content in the HCM samples would be expected to decrease the rate of cross-bridge detachment. Moreover, left atrial size, an indicator of diastolic compliance, was inversely correlated with ATP content in hearts from patients with HCM. HCM hearts display profound deficits in nucleotide availability with markedly reduced capacity for fatty acid oxidation and increases in ketone bodies and branched chain amino acids. These results have important therapeutic implications for the future design of metabolic modulators to treat HCM.

Effects of aging and type 2 diabetes on cardiac structure and function: Underlying mechanisms

This study characterized long‐term changes in cardiac structure and function in a high‐fat diet/streptozotocin mouse model of aging and type 2 diabetes mellitus (T2D) and how the intersection of both conditions alters plasma metabolomics. Furthermore, we wanted to assess the possible mechanistic roles played by oxidative stress, increases in arginase activity and pro‐inflammatory cytokines levels. For this purpose, 38, 13‐month‐old C57BL/6 male mice were utilized. Control animals (n=13) were fed a regular chow for a period of 10 months. T2D (n=25) animals were provided a single injection of streptozotocin (75 mg/kg/IP) and fed a 60% high fat diet (HFD) for the same period of time. To track changes in cardiac structure and function serial echocardiography was performed. At the end of the study, blood samples were collected via a cardiac puncture and plasma samples frozen. Hearts were sectioned and allocated for either rapid freezing (biochemical studies) or fixed in formalin for histological analysis. Biochemical assays using blood and/or tissue samples included determinations for arginase activity, pro‐inflammatory cytokines, protein carbonylation, glucose tolerance tests, Western blots and plasma metabolomics. Glucose tolerance tests confirmed the development of T2D in the HFD animal group. Serial echo yielded moderate increases in cardiac mass with aging that were greater in T2D animals. Fractional shortening (figure) significantly decreased by 16 months of age in T2D animals yielding a value of 28% at 23 months vs. 40% in aged controls. Ejection fraction also significantly decreased by 16 months of age in T2D animals yielding 55% at 23 months vs. aged animals (70%). Western blots of myocardium samples documented increases in fibronectin, type III collagen and smooth muscle actin with T2D which were confirmed by immunohistochemistry. Significant increases in plasma protein carbonyls, TGF‐β1, TNF‐α, IL1β and IFN‐γ occurred with aging and further increased with T2D. Untargeted metabolomics and cheminformatics revealed clear differences in the plasma metabolome of the HFD mice vs. controls. Multiple lipid metabolites linked to insulin resistance were dysregulated, including C16:0 and C18:0 acyl carnitines (up‐modulated) and saturated and unsaturated phosphocholine‐containing lipids (up and down‐modulated). In summary, we document the development of cardiac hypertrophy with aging that is aggravated by T2D. Systolic dysfunction occurred as a late age associated event with T2D. Increases in OS markers and pro‐inflammatory cytokines occurred with aging and were aggravated with T2D. These changes were accompanied by increases in myocardial and blood arginase activity and TGF‐β1 levels which may account for the development of fibrosis and may be associated with altered plasma metabolomics.

Carnitine and Depression.

Depression has become one of the most common mental diseases in the world, but the understanding of its pathogenesis, diagnosis and treatments remains insufficient. Carnitine is a natural substance that exists in organisms, which can be synthesized in vivo or supplemented by intake. Relationships of carnitine with depression, bipolar disorder and other mental diseases have been reported in different studies. Several studies show that the level of acylcarnitines (ACs) changes significantly in patients with depression compared with healthy controls while the supplementation of acetyl-L-carnitine is beneficial to the treatment of depression. In this review, we aimed to clarify the effects of ACs in depressive patients and to explore whether ACs might be the biomarkers for the diagnosis of depression and provide new ideas to treat depression.

Abstract EP07: A Longitudinal Lipidomics Profiling For Risk Of Chronic Kidney Disease In American Indians: The Strong Heart Family Study

Background: Dyslipidemia is associated with and often precedes the onset of chronic kidney disease (CKD). However, standard lipid panels fail to describe the full spectrum of blood lipidome. A longitudinal profiling of the full spectrum of blood lipidome associated with the risk of CKD is still lacking in any racial/ethnic group, including American Indians, a population that suffered a disproportionately high burden of CKD. Objective: To identify novel lipids and lipidomic signatures associated with risk of CKD in American Indians, independent of traditional risk factors. Methods: We included 1,910 American Indians who attended two examinations (~5.5 years apart) and were free of CKD and cardiovascular disease (CVD) at baseline. CKD was defined based on the estimated glomerular filtration rate (eGFR) calculated by the CKD-EPI formula. Fasting plasma levels of 1,542 lipids in 3,916 samples at two-time points were repeatedly measured by untargeted LC-MS. Machine learning (elastic net) was used to identify lipidomic predictors of CKD beyond traditional risk factors (age, sex, center, BMI, hypertension, diabetes, urinary albumin/creatinine ratio, HDL, triglyceride, and use of lipid-lowering medications). Mixed-effect linear models were used to examine the relationship between changes (baseline to 5-year follow-up) in lipidome and change in kidney function (eGFR), adjusting for traditional risk factors mentioned above, baseline lipid, and baseline eGFR. Multivariate analysis was conducted to identify discriminatory lipidomic signatures that can differentiate between high- and low-risk individuals. Results: Of 1,910 participants free of CKD and CVD (17.8% diabetic) at baseline, 55 (2.9%) developed incident CKD by the end of a 5-year follow-up. Elastic net identified 106 (24 known) lipids, largely glycerophospholipids (GPs), sphingomyelins (SMs), triacylglycerols (TAGs), fatty acids (FAs), and acylcarnitines (ACs), whose altered baseline levels were associated with the risk of CKD, independent of traditional risk factors. A composite lipid score composed of the 24 known lipids improved CKD risk prediction beyond traditional risk factors (AUROC improved from 0.944 to 0.963, P = 0.006). Longitudinal changes in 182 lipids (75 known) lipids, largely GPs, FAs, SMs, TAGs, ACs, and diacylglycerols (DAGs), explained up to 4.8% of the variation of the eGFR change. Multivariate analysis identified distinct lipidomic signatures that separated high- from low-risk participants. Conclusion: We identified novel molecular lipids that significantly predict CKD onset and progression among American Indians beyond traditional risk factors. Our findings shed light on the mechanisms by which dyslipidemia affects CKD and provide instrumental data for biomarker identification, risk prediction and stratification, prognosis, and potential therapeutics.

Lipidomic Profiling Identifies Serum Lipids Associated with Persistent Multisite Musculoskeletal Pain.

Lipid mediators have been suggested to have a role in pain sensitivity and response; however, longitudinal data on lipid metabolites and persistent multisite musculoskeletal pain (MSMP) are lacking. This study was to identify lipid metabolic markers for persistent MSMP. Lipidomic profiling of 807 lipid species was performed on serum samples of 536 participants from a cohort study. MSMP was measured by a questionnaire and defined as painful sites ≥4. Persistent MSMP was defined as having MSMP at every visit. Logistic regression was used with adjustment for potential confounders. The Benjamini–Hochberg method was used to control for multiple testing. A total of 530 samples with 807 lipid metabolites passed quality control. Mean age at baseline was 61.54 ± 6.57 years and 50% were females. In total, 112 (21%) of the participants had persistent MSMP. Persistent MSMP was significantly associated with lower levels of monohexosylceramide (HexCer)(d18:1/22:0 and d18:1/24:0), acylcarnitine (AC)(26:0) and lysophosphatidylcholine (LPC)(18:1 [sn1], 18:2 [sn1], 18:2 [sn2], and 15-MHDA[sn1] [104_sn1]) after controlling for multiple testing. After adjustment for age, sex, body mass index, comorbidities, and physical activity, HexCer(d18:1/22:0 and d18:1/24:0) and LPC(15-MHDA [sn1] [104_sn1]) were significantly associated with persistent MSMP [Odds Ratio (OR) ranging from 0.25–0.36]. Two lipid classes—HexCer and LPC—were negatively associated with persistent MSMP after adjustment for covariates (OR = 0.22 and 0.27, respectively). This study identified three novel lipid signatures of persistent MSMP, suggesting that lipid metabolism is involved in the pathogenesis of persistent pain.

Distinguishing the molecular diversity, nutrient content, and energetic potential of exometabolomes produced by macroalgae and reef-building corals

Metabolites exuded by primary producers comprise a significant fraction of marine dissolved organic matter, a poorly characterized, heterogenous mixture that dictates microbial metabolism and biogeochemical cycling. We present a foundational untargeted molecular analysis of exudates released by coral reef primary producers using liquid chromatography-tandem mass spectrometry to examine compounds produced by two coral species and three types of algae (macroalgae, turfing microalgae, and crustose coralline algae [CCA]) from Mo'orea, French Polynesia. Of 10,568 distinct ion features recovered from reef and mesocosm waters, 1,667 were exuded by producers; the majority (86%) were organism specific, reflecting a clear divide between coral and algal exometabolomes. These data allowed us to examine two tenets of coral reef ecology at the molecular level. First, stoichiometric analyses show a significantly reduced nominal carbon oxidation state of algal exometabolites than coral exometabolites, illustrating one ecological mechanism by which algal phase shifts engender fundamental changes in the biogeochemistry of reef biomes. Second, coral and algal exometabolomes were differentially enriched in organic macronutrients, revealing a mechanism for reef nutrient-recycling. Coral exometabolomes were enriched in diverse sources of nitrogen and phosphorus, including tyrosine derivatives, oleoyl-taurines, and acyl carnitines. Exometabolites of CCA and turf algae were significantly enriched in nitrogen with distinct signals from polyketide macrolactams and alkaloids, respectively. Macroalgal exometabolomes were dominated by nonnitrogenous compounds, including diverse prenol lipids and steroids. This study provides molecular-level insights into biogeochemical cycling on coral reefs and illustrates how changing benthic cover on reefs influences reef water chemistry with implications for microbial metabolism.

UCP1 Knockin Induces Lipid Dynamics and Transcriptional Programs in the Skeletal Muscles of Pigs.

Uncoupling protein 1 (UCP1), the hallmark protein responsible for nonshivering thermogenesis in adipose tissue (especially brown adipose tissue) has regained researchers’ attention in the context of metabolic disorders following the realization that UCP1 can be activated in adult humans and reconstituted in pigs. Both skeletal muscle and adipose tissue are highly dynamic tissues that interact at the metabolic and hormonal level in response to internal and external stress, and they coordinate in maintaining whole-body metabolic homeostasis. Here, we utilized lipidomics and transcriptomics to identify the altered lipid profiles and regulatory pathways in skeletal muscles from adipocyte-specific UCP1 knock-in (KI) pigs. UCP1 KI changed the contents of glycerophospholipids and acyl carnitines of skeletal muscles. Several metabolic regulatory pathways were more enriched in the UCP1 KI skeletal muscle. Comparison of the transcriptomes of adipose and skeletal muscle suggested that nervous system or chemokine signaling might account for the crosstalk between these two tissues in UCP1 KI pigs. Comparison of the lipid biomarkers from UCP1 KI pigs and other mammals suggested associations between UCP1 KI-induced metabolic alternations and metabolic and muscle dysfunction. Our study reveals the lipid dynamics and transcriptional programs in the skeletal muscle of UCP1 KI pigs and suggests that a network regulates metabolic homeostasis between skeletal muscle and adipose tissue.

Stability of amino acids, free and acyl-carnitine in stored dried blood spots.

BackgroundNewborn screening of inborn errors of metabolism using tandem mass spectrometry has become a public health strategy in many developed countries. Retrospective analyses using stored dried blood specimens have been limited, mainly due to a lack of biochemical information on the long‐term stability of acylcarnitines and amino acids in stored specimens. We studied the characteristic profiles of the stability of amino acid, free carnitine, and acyl carnitines in dried blood specimens stored in a refrigerator after newborn screening.MethodsDried blood specimens from 198 healthy newborns, which had been stored in a refrigerator at 5 °C after newborn screening, were prospectively subjected to tandem mass spectrometry analyses after 1, 3, 6 months, 1 and 2 years of storage. We also retrospectively re‐analyzed the stored samples from 90 newborns, which had been analyzed and stored at 5 °C for 4 years.ResultsWe found that proline (Pro) and tyrosine (Tyr) were stable for 2 years, and that alanine (Ala), arginine (Arg), and phenylalanine (Phe) decayed with linear regression. The C0 increased during the time‐course of 2 years, whereas most acylcarnitines gradually decayed and some showed a linear correlation. The retrospective analysis of samples stored for 4 years revealed that Ala, Phe, Pro and Tyr were almost stable, leucine (Leu), valine (Val) decayed with linear regression, C0 increased, and C10, C12, C14, C14:1, C16, C18, C18:1 decreased, while maintaining a linear correlation.ConclusionsThese data suggested that some metabolic parameters from refrigerator‐stored dried blood specimens were applicable for the detection of inborn errors of metabolism.

Clinical metabolomics for inborn errors of metabolism.

Metabolism is a highly regulated process that provides nutrients to cells and essential building blocks for the synthesis of protein, DNA and other macromolecules. In healthy biological systems, metabolism maintains a steady state in which the concentrations of metabolites are relatively constant yet are subject to metabolic demands and environmental stimuli. Rare genetic disorders, such as inborn errors of metabolism (IEM), cause defects in regulatory enzymes or proteins leading to metabolic pathway disruption and metabolite accumulation or deficiency. Traditionally, the laboratory diagnosis of IEMs has been limited to analytical methods that target specific metabolites such as amino acids and acyl carnitines. This approach is effective as a screening method for the most common IEM disorders but lacks the comprehensive coverage of metabolites that is necessary to identify rare disorders that present with nonspecific clinical symptoms. Fortunately, advancements in technology and data analytics has introduced a new field of study called metabolomics which has allowed scientists to perform comprehensive metabolite profiling of biological systems to provide insight into mechanism of action and gene function. Since metabolomics seeks to measure all small molecule metabolites in a biological specimen, it provides an innovative approach to evaluating disease in patients with rare genetic disorders. In this review we provide insight into the appropriate application of metabolomics in clinical settings. We discuss the advantages and limitations of the method and provide details related to the technology, data analytics and statistical modeling required for metabolomic profiling of patients with IEMs.

Metabolomics study reveals the alteration of fatty acid oxidation in the hearts of diabetic mice by empagliflozin.

Empagliflozin (Empa, SGLT2 inhibitor) is widely used in clinical situations for the management of diabetes. It has beneficial effects in reducing cardiac dysfunction and heart failure. However, rare studies have reported the potential mechanisms of Empa reaction. Here, we treated db/db diabetic mice with Empa and collected the heart tissue for metabolomics study. We found that db/db mice showed obvious differences in metabolomics profile compared with db/m mice. Many amino acid metabolism pathways and glycerophospholipids and fatty acyl carnitines were significantly enriched in db/db mice. Detailed analysis revealed the alteration of fatty acid oxidation in db/db mice. Interestingly, many metabolites in the fatty acid oxidation pathway, such as myristoleic acid, 12-hydroxydodecanoic acid, (15-carboxypentadecanoyl)carnitine, decanoylcarnitine, and propionylcarnitine, were significantly rescued by Empa treatment. These results suggest that fatty acid oxidation is one of the targets for Empa treatment in the heart of db/db mice. This study provided new possibilities for the development of therapeutic interventions for diabetic cardiomyopathy.

Serum carnitine as a biomarker of sarcopenia and nutritional status in preoperative gastrointestinal cancer patients.

BackgroundSarcopenia is an important factor in the postoperative outcome of gastrointestinal cancer patients. However, little research has been carried out on potential biomarkers of sarcopenia. Carnitine is an amino acid derivative that is stored in skeletal muscle and is essential for muscle energy metabolism. The primary purpose of this study was to investigate whether serum carnitine level is a biomarker of sarcopenia in preoperative patients with gastrointestinal cancer. The secondary purposes were (i) to examine the associations between carnitine, nutritional status, and albumin level, and (ii) to determine whether carnitine is a prognostic factor for postoperative complications.MethodsOne hundred fourteen patients scheduled to undergo gastroenterological surgery between August 2016 and January 2017 were enrolled. Their mean age was 68.4 ± 10.5, and 64.9% were male. Serum carnitine fractions [total carnitine (TC), free l‐carnitine (FC), and acylcarnitine (AC)] were measured prior to surgery. The correlation between carnitine level and a variety of clinical features was analysed, including skeletal muscle index (SMI), sarcopenia, prognostic nutritional index (PNI), and postoperative complications.ResultsTumour locations included the oesophagus (n = 17), stomach (n = 16), pancreas (n = 20), bile duct (n = 9), liver [n = 33; primary liver cancer (n = 18), liver metastasis (n = 15)], and colorectal region (n = 19). TC and FC levels varied significantly by tumour location. TC and FC showed significant positive correlations with SMI [TC (r = 0.295, P = 0.0014), FC (r = 0.286, P = 0.0020)] and PNI [TC (P = 0.0178, r = 0.222), FC (P = 0.0067, r = 0.2526)]. These levels were significantly lower in the sarcopenia group (TC, P = 0.0124; FC, P = 0.0243). In addition, TC and FC showed significant positive correlations with ALB level [TC (P = 0.038 r = 0.19), FC (P = 0.016 r = 0.23)]. When patients were divided into high ALB (≥3.5 g/dL, 96 patients) and low ALB (<3.5 g/dL, 18 patients) groups, these correlations were no longer significant, but in the low ALB group there was a tendency towards a negative relationship between ALB level and both TC and FC. No significant relationship was found between postoperative complications and carnitine level.ConclusionsThis study suggests that carnitine level is a biomarker of sarcopenia and nutritional status. However, it did not find an association between carnitine level and postoperative complications.

Evaluation of lipid metabolism imbalance in HIV-infected patients with metabolic disorders using high-performance liquid chromatography-tandem mass spectrometry

Human immunodeficiency virus (HIV) infection and highly active antiretroviral therapy use are associated with the disruption of lipid and glucose metabolism. Herein, a sensitive and robust high-performance liquid chromatography–tandem mass spectrometry method for the quantitation of lysophosphatidylcholines (LPCs) and acylcarnitines (ACs) in human blood serum was developed and validated to investigate them as markers of metabolic disorders in HIV-infected patients. Under optimal extraction and detection conditions, the lower limits of quantification reached 5 ng/mL (LPCs) and 0.1 ng/mL (ACs), and precision and accuracy for both intra- and inter-day analyses were generally below 15%. Serum samples were stable for at least six months when stored at − 80 °C and for at least 12 h when stored at 4 °C or 25 °C. We investigated inter-group differences and associations between the biomarkers and observed a particular volatilitytrend of LPCs and ACs for HIV-infected patients with metabolic disorders. Thus, the developed method can be used for the rapid and sensitive quantitation of LPCs and ACs in vivo to further appraise the process of HIV infection, evaluate interveningmeasures, conduct mechanistic investigations, and further study the utility of LPCs and ACs as biomarkers of HIV infection coupled with metabolic disorders.

Serum metabolomic and lipidomic profiling identifies diagnostic biomarkers for seropositive and seronegative rheumatoid arthritis patients

BackgroundDiagnosing seronegative rheumatoid arthritis (RA) can be challenging due to complex diagnostic criteria. We sought to discover diagnostic biomarkers for seronegative RA cases by studying metabolomic and lipidomic changes in RA patient serum.MethodsWe performed comprehensive metabolomic and lipidomic profiling in serum of 225 RA patients and 100 normal controls. These samples were divided into a discovery set (n = 243) and a validation set (n = 82). A machine-learning-based multivariate classification model was constructed using distinctive metabolites and lipids signals.ResultsTwenty-six metabolites and lipids were identified from the discovery cohort to construct a RA diagnosis model. The model was subsequently tested on a validation set and achieved accuracy of 90.2%, with sensitivity of 89.7% and specificity of 90.6%. Both seropositive and seronegative patients were identified using this model. A co-occurrence network using serum omics profiles was built and parsed into six modules, showing significant association between the inflammation and immune activity markers and aberrant metabolism of energy metabolism, lipids metabolism and amino acid metabolism. Acyl carnitines (20:3), aspartyl-phenylalanine, pipecolic acid, phosphatidylethanolamine PE (18:1) and lysophosphatidylethanolamine LPE (20:3) were positively correlated with the RA disease activity, while histidine and phosphatidic acid PA (28:0) were negatively correlated with the RA disease activity.ConclusionsA panel of 26 serum markers were selected from omics profiles to build a machine-learning-based prediction model that could aid in diagnosing seronegative RA patients. Potential markers were also identified in stratifying RA cases based on disease activity.

Exposure to a mixture of legacy, alternative, and replacement per- and polyfluoroalkyl substances (PFAS) results in sex-dependent modulation of cholesterol metabolism and liver injury.

Epidemiological studies have shown Per- and polyfluoroalkyl substances (PFAS) to be associated with diseases of dysregulated lipid and sterol homeostasis such as steatosis and cardiometabolic disorders. However, the majority of mechanistic studies rely on single chemical exposures instead of identifying mechanisms related to the toxicity of PFAS mixtures. The goal of the current study is to investigate mechanisms linking exposure to a PFAS mixture with alterations in lipid metabolism, including increased circulating cholesterol and bile acids. Male and female wild-type C57BL/6J mice were fed an atherogenic diet used in previous studies of pollutant-accelerated atherosclerosis and exposed to water containing a mixture of 5 PFAS representing legacy, replacement, and alternative subtypes (i.e., PFOA, PFOS, PFNA, PFHxS, and GenX), each at a concentration of 2mg/L, for 12weeks. Changes at the transcriptome and metabolome level were determined by RNA-seq and high-resolution mass spectrometry, respectively. We observed increased circulating cholesterol, sterol metabolites, and bile acids due to PFAS exposure, with some sexual dimorphic effects. PFAS exposure increased hepatic injury, demonstrated by increased liver weight, hepatic inflammation, and plasma alanine aminotransferase levels. Females displayed increased lobular and portal inflammation compared to the male PFAS-exposed mice. Hepatic transcriptomics analysis revealed PFAS exposure modulated multiple metabolic pathways, including those related to sterols, bile acids, and acyl carnitines, with multiple sex-specific differences observed. Finally, we show that hepatic and circulating levels of PFOA were increased in exposed females compared to males, but this sexual dimorphism was not the same for other PFAS examined. Exposure of mice to a mixture of PFAS results in PFAS-mediated modulation of cholesterol levels, possibly through disruption of enterohepatic circulation.

Diagnosis of atypical myopathy based on organic acid and acylcarnitine profiles and evolution of biomarkers in surviving horses

BackgroundAtypical myopathy (AM), an acquired multiple acyl-CoA dehydrogenase deficiency (MADD) in horses, induce changes in mitochondrial metabolism. Only few veterinary laboratories offer diagnostic testing for this disease. Inborn and acquired MADD exist in humans, therefore determination of organic acids (OA) in urine and acylcarnitines (AC) in blood by assays available in medical laboratories can serve as AM diagnostics. The evolution of OA and AC profiles in surviving horses is unreported. MethodsAC profiles using electrospray ionization tandem mass spectrometry (ESI-MS/MS) and OA in urine using gas chromatography mass spectrometry (GC–MS) were determined in dried blot spots (DBS, n = 7) and urine samples (n = 5) of horses with AM (n = 7) at disease presentation and in longitudinal samples from 3/4 survivors and compared to DBS (n = 16) and urine samples (n = 7) from control horses using the Wilcoxon test. ResultsAll short- (C2-C5) and medium-chain (C6-C12) AC in blood differed significantly (p < 0.008) between horses with AM and controls, except for C5:1 (p = 0.45) and C5OH + C4DC (p = 0.06). In AM survivors the AC concentrations decreased over time but were still partially elevated after 7 days. 14/62 (23%) of OA differed significantly between horses with AM and control horses. Concentrations of ethylmalonic acid, 2-hydroxyglutaric acid and the acylglycines (butyryl-, valeryl-, and hexanoylglycine) were highly elevated in the urine of all horses with AM at the day of disease presentation. In AM survivors, concentrations of those metabolites were initially lower and decreased during remission to approach normalization after 7 days. ConclusionOA and AC profiling by specialized human medical laboratories was used to diagnose AM in horses. Elevation of specific metabolites were still evident several days after disease presentation, allowing diagnosis via analysis of samples from convalescent animals.

Internal carbohydrates and lipids as reserved energy supply in the pubertal molt of Scylla paramamosain

Pubertal molt is critical for the reproductive process of mud crab Scylla paramamosain, during which female crabs molt and mate with males, and subsequently, ovarian development is initiated. Since fasting occurs during pubertal molt, the mechanism underlying how the internal energy reserves support crabs' survival is unclear. In this study, the hepatopancreas and ovaries were collected for metabolomics analyses. The results show 11 carbohydrate and 4 lipid metabolic pathways were remarkably modulated in hepatopancreas, suggesting carbohydrates and lipids may be the main energy reserves in hepatopancreas postmolt. Further analysis showed that the levels of glucose, glucose 6-phosphate, glucose 1-phosphate, and fructose 6-phosphate were increased, indicating glycolysis was upregulated for energy supply. Meanwhile, 65 lipids were significantly changed, including 16 glycerophospholipids and 33 fatty acids, suggesting lipids might be another main energy supplier in the hepatopancreas. In the ovary, 7 carbohydrate and 1 lipid metabolic pathways were obviously affected, and 12 carbohydrates and 23 lipids were also significantly changed postmolt. Differently from the changes in the hepatopancreas, the glucose level was significantly decreased in the ovary, whereas the levels of eight glycerophospholipids and four unsaturated fatty acids were increased in the ovary but decreased in the hepatopancreas, suggesting lipids might be major energy reserves for ovarian development, and they were possibly exported from hepatopancreas. Moreover, the obvious changes in seven fatty acyl carnitines in the ovary indicate they were consumed via β-oxidation postmolt. Taken together, carbohydrates and fatty acyl carnitines were clearly the major energy reserves in pubertal molt. The hepatopancreas played a central role in the supply of energy reserves and nutrients. Numerous glycerophospholipids and unsaturated fatty acids may have accumulated in the ovary for the biosynthesis of egg yolk during ovarian development. This study suggests that proper increases in carbohydrate and lipid levels in crab feed ahead of pubertal molt may alleviate the effects of fasting and enhance successful reproduction.