Plasma Lipidome Research Articles

Simulated Night-Shift Schedule Disrupts the Plasma Lipidome and Reveals Early Markers of Cardiovascular Disease Risk.

IntroductionThe circadian system coordinates daily rhythms in lipid metabolism, storage and utilization. Disruptions of internal circadian rhythms due to altered sleep/wake schedules, such as in night-shift work, have been implicated in increased risk of cardiovascular disease and metabolic disorders. To determine the impact of a night-shift schedule on the human blood plasma lipidome, an in-laboratory simulated shift work study was conducted.MethodsFourteen healthy young adults were assigned to 3 days of either a simulated day or night-shift schedule, followed by a 24-h constant routine protocol with fixed environmental conditions, hourly isocaloric snacks, and constant wakefulness to investigate endogenous circadian rhythms. Blood plasma samples collected at 3-h intervals were subjected to untargeted lipidomics analysis.ResultsMore than 400 lipids were identified and quantified across 21 subclasses. Focusing on lipids with low between-subject variation per shift condition, alterations in the circulating plasma lipidome revealed generally increased mean triglyceride levels and decreased mean phospholipid levels after night-shift relative to day-shift. The circadian rhythms of triglycerides containing odd chain fatty acids peaked earlier during constant routine after night-shift. Regardless of shift condition, triglycerides tended to either peak or be depleted at 16:30 h, with chain-specific differences associated with the direction of change.DiscussionThe simulated night-shift schedule was associated with altered temporal patterns in the lipidome. This may be premorbid to the elevated cardiovascular risk that has been found epidemiologically in night-shift workers.

Bacille Calmette-Guérin vaccine reprograms human neonatal lipid metabolism invivo and invitro.

SUMMARYVaccines have generally been developed with limited insight into their molecular impact. While systems vaccinology enables characterization of mechanisms of action, these tools have yet to be applied to infants, who are at high risk of infection and receive the most vaccines. Bacille Calmette-Guérin (BCG) protects infants against disseminated tuberculosis (TB) and TB-unrelated infections via incompletely understood mechanisms. We employ mass-spectrometry-based metabolomics of blood plasma to profile BCG-induced infant responses in Guinea-Bissau in vivo and the US in vitro. BCG-induced lysophosphatidylcholines (LPCs) correlate with both TLR-agonist- and purified protein derivative (PPD, mycobacterial antigen)-induced blood cytokine production in vitro, raising the possibility that LPCs contribute to BCG immunogenicity. Analysis of an independent newborn cohort from The Gambia demonstrates shared vaccine-induced metabolites, such as phospholipids and sphingolipids. BCG-induced changes to the plasma lipidome and LPCs may contribute to its immunogenicity and inform the development of early life vaccines.

Validation of a multiplexed and targeted lipidomics assay for accurate quantification of lipidomes

A major challenge of lipidomics is to determine and quantify the precise content of complex lipidomes to the exact lipid molecular species. Often, multiple methods are needed to achieve sufficient lipidomic coverage to make these determinations. Multiplexed targeted assays offer a practical alternative to enable quantitative lipidomics amenable to quality control standards within a scalable platform. Herein, we developed a multiplexed normal phase liquid chromatography-hydrophilic interaction chromatography multiple reaction monitoring method that quantifies lipid molecular species across over 20 lipid classes spanning wide polarities in a single 20-min run. Analytical challenges such as in-source fragmentation, isomer separations, and concentration dynamics were addressed to ensure confidence in selectivity, quantification, and reproducibility. Utilizing multiple MS/MS product ions per lipid species not only improved the confidence of lipid identification but also enabled the determination of relative abundances of positional isomers in samples. Lipid class-based calibration curves were applied to interpolate lipid concentrations and guide sample dilution. Analytical validation was performed following FDA Bioanalytical Method Validation Guidance for Industry. We report repeatable and robust quantitation of 900 lipid species measured in NIST-SRM-1950 plasma, with over 700 lipids achieving inter-assay variability below 25%. To demonstrate proof of concept for biomarker discovery, we analyzed plasma from mice treated with a glucosylceramide synthase inhibitor, benzoxazole 1. We observed expected reductions in glucosylceramide levels in treated animals but, more notably, identified novel lipid biomarker candidates from the plasma lipidome. These data highlight the utility of this qualified lipidomic platform for enabling biological discovery.

Effects of a 0.3% cholesterol diet and a 20% fat diet on plasma lipids and lipoproteins in Quaker parrots (Myiopsitta monachus).

Lipid disorders are common in captive psittacine birds, but associated changes in blood lipids and lipoproteins have not been well characterized. The Quaker parrot is prone to dyslipidemia and has been extensively used as an experimental model. We aimed to study the effects of a 0.3% cholesterol diet and a 20% fat diet on plasma lipids and lipoproteins in Quaker parrots. Two crossover studies were performed with each diet. During each study, 12 parrots were divided into two groups fed the treatment or control diet for 2weeks. After a 2-month wash-out period, the groups were reversed. At the end of each period, plasma lipidomics and lipoprotein profiling were performed. Data were analyzed by univariate tests adjusted for false discovery rates, volcano plots, and enrichment analyses. The cholesterol diet induced changes in many plasma lipids and lipoproteins. Total cholesterol and cholesteryl esters were significantly and markedly elevated. Ceramides were the second subclass of lipids that were elevated. Several glycerophosphocholines, sphingomyelins, and one diacylglycerol were also significantly elevated, albeit to a lesser magnitude. All lipoproteins were elevated, with the greatest increase seen in non-HDL. The fat diet mainly resulted in a decrease in plasma glycerolipids and an increase in acylcarnitines. Lipoprotein plasma levels remained unchanged. Quaker parrots fed a 0.3% cholesterol diet showed profound and complex dyslipidemic changes that could be used to further study lipid disorders and their management in psittacine birds. A 20% fat diet higher in n-6 polyunsaturated fatty acids did not lead to dyslipidemia.

Plasma lipidome acts as diagnostic marker and predictor for cyclosporin response in patients with aplastic anemia.

The lipid metabolomic profile has been well defined in the pathogenesis and differential diagnosis in patients with different myeloid diseases. We assumed that the serum lipid metabolites could also help the diagnosis and prognostic prediction of aplastic anemia (AA). In this study, serum lipid profiles were explored in AA patients before and after cyclosporin (CsA) treatment. Meanwhile, hypocellular myelodysplastic syndrome (h-MDS) patients and the healthy volunteers were compared as controls. 15 AA patients, 11h-MDS patients and 20 age and sex matched health controls were enrolled. All the AA patients were diagnosed to be non-severe aplastic anemia with transfusion dependency and were treated by CsA 3-5mg/kg/d for at least 6months. AA patients had decreased arachidonic acid pathway metabolites and retinol metabolism-related metabolites as compared with h-MDS and the health (P < 0.05), whereas h-MDS patients had increased metabolism of proline and threonine and abnormal sphingolipid metabolism compared with AA patients and the normal controls. After 6month of CsA treatment, serum arachidonic acid, PGE2, PGJ2, 15(S)-HETE, leukotriene B4 and Protectin D1 decreased significantly. Patients who had response to CsA had higher levels of baseline protectin D1 (P = 0.011), leukotriene B4 (P = 0.011), 15(S)-HETE (P = 0.004) and all-trans-retinal (P = 0.000) than those who had no response.

Variants in mitochondrial amidoxime reducing component 1 and hydroxysteroid 17-beta dehydrogenase 13 reduce severity of nonalcoholic fatty liver disease in children and suppress fibrotic pathways through distinct mechanisms.

Genome‐wide association studies in adults have identified variants in hydroxysteroid 17‐beta dehydrogenase 13 (HSD17B13) and mitochondrial amidoxime reducing component 1 (MTARC1) as protective against nonalcoholic fatty liver disease (NAFLD). We aimed to test their association with pediatric NAFLD liver histology and investigate their function using metabolomics. A total of 1450 children (729 with NAFLD, 399 with liver histology) were genotyped for rs72613567T>TA in HSD17B13, rs2642438G>A in MTARC1, and rs738409C>G in patatin‐like phospholipase domain‐containing protein 3 (PNPLA3). Genotype–histology associations were tested using ordinal regression. Untargeted hepatic proteomics and plasma lipidomics were performed in a subset of children. We found rs72613567T>TA in HSD17B13 to be associated with lower odds of NAFLD diagnosis (odds ratio, 0.7; 95% confidence interval, 0.6–0.9) and a lower grade of portal inflammation (p < 0.001). rs2642438G>A in MTARC1 was associated with a lower grade of hepatic steatosis (p = 0.02). Proteomics found reduced expression of HSD17B13 in carriers of the protective ‐TA allele. MTARC1 levels were unaffected by genotype. Both variants were associated with down‐regulation of fibrogenic pathways. HSD17B13 perturbs plasma phosphatidylcholines and triglycerides. In silico modeling suggested p.Ala165Thr disrupts the stability and metal binding of MTARC1. Conclusion: Both HSD17B13 and MTARC1 variants are associated with less severe pediatric NAFLD. These results provide further evidence for shared genetic mechanisms between pediatric and adult NAFLD.

Changes in the Cerebrospinal Fluid and Plasma Lipidome in Patients with Rett Syndrome

Rett syndrome (RTT) is defined as a rare disease caused by mutations of the methyl-CpG binding protein 2 (MECP2). It is one of the most common causes of genetic mental retardation in girls, characterized by normal early psychomotor development, followed by severe neurologic regression. Hitherto, RTT lacks a specific biomarker, but altered lipid homeostasis has been found in RTT model mice as well as in RTT patients. We performed LC-MS/MS lipidomics analysis to investigate the cerebrospinal fluid (CSF) and plasma composition of patients with RTT for biochemical variations compared to healthy controls. In all seven RTT patients, we found decreased CSF cholesterol levels compared to age-matched controls (n = 13), whereas plasma cholesterol levels were within the normal range in all 13 RTT patients compared to 18 controls. Levels of phospholipid (PL) and sphingomyelin (SM) species were decreased in CSF of RTT patients, whereas the lipidomics profile of plasma samples was unaltered in RTT patients compared to healthy controls. This study shows that the CSF lipidomics profile is altered in RTT, which is the basis for future (functional) studies to validate selected lipid species as CSF biomarkers for RTT.

Alterations in the Plasma Lipidome of Adult Women With Bipolar Disorder: A Mass Spectrometry-Based Lipidomics Research.

Lipidomics has become a pivotal tool in biomarker discovery for the diagnosis of psychiatric illnesses. However, the composition and quantitative analysis of peripheral lipids in female patients with bipolar disorder (BD) have been poorly addressed. In this study, plasma samples from 24 female patients with BD and 30 healthy controls (HCs) were analyzed by comprehensive lipid profiling and quantitative validation based on liquid chromatography–mass spectrometry. Clinical characteristics and a correlation between the level of lipid molecules and clinical symptoms were also observed. We found that the quantitative alterations in several lipid classes, including acylcarnitine, lysophosphatidylethanolamine, GM2, sphingomyelin, GD2, triglyceride, monogalactosyldiacylglycerol, phosphatidylinositol phosphate, phosphatidylinositol 4,5-bisphosphate, phosphatidylethanolamine, phosphatidylserine, and lysophosphatidylinositol, were remarkably upregulated or downregulated in patients with BD and were positively or negatively correlated with the severity of psychotic, affective, or mania symptoms. Meanwhile, the composition of different carbon chain lengths and degrees of fatty acid saturation for these lipid classes in BD were also different from those of HCs. Moreover, 55 lipid molecules with significant differences and correlations with the clinical parameters were observed. Finally, a plasma biomarker set comprising nine lipids was identified, and an area under the curve of 0.994 was obtained between patients with BD and the HCs. In conclusion, this study provides a further understanding of abnormal lipid metabolism in the plasma and suggests that specific lipid species can be used as complementary biomarkers for the diagnosis of BD in women.

Lipidomics and Transcriptomics in Neurological Diseases.

Lipids serve as the primary interface to brain insults or stimuli conducive to neurological diseases and are a reservoir for the synthesis of lipids with various signaling or ligand function that can underscore the onset and progression of diseases. Often changing at the presymptomatic level, lipids are an emerging source of drug targets and biomarkers. Many neurological diseases exhibit neuroinflammation, neurodegeneration, and neuronal excitability as common hallmarks, partly modulated by specific lipid signaling systems. The interdependence and interrelation of synthesis of various lipids prompts a multilipid, multienzyme, and multireceptor analysis in order to derive the commonalities and specificities of neurological contexts and to expedite the unravelling of mechanistic aspects of disease onset and progression. Ascribing lipid roles to distinct brain regions advances the determination of lipid molecular phenotype and morphology associated with a neurological disease. Presented here is a modular protocol suitable for the analysis of membrane lipids and downstream lipid signals along with mRNA of enzymes and mediators underlying their functionality, extracted from discrete brain regions that are relevant for a particular neurological disease and/or condition. To ensure accurate comparative lipidomic profiling, the workflows and operating criteria were optimized and standardized for: i) brain sampling and dissection of regions of interest, ii) co-extraction of multiple lipid signals and membrane lipids, iii) dual lipid/mRNA extraction, iv) quantification by liquid chromatography multiple reaction monitoring (LC/MRM), and v) standard mRNA profiling. This workflow is amenable for the low tissue amounts obtained by sampling of the functionally discrete brain subregions (i.e. by brain punching), thus preventing bias in multimolecular analysis due to tissue heterogeneity and/or animal variability. To reveal peripheral consequences of neurological diseases and establish translational molecular readouts of neurological disease states, peripheral organ sampling, processing, and their subsequent lipidomic analysis, as well as plasma lipidomics, are also pursued and described. The protocol is demonstrated on an acute epilepsy mouse model.

Determination of tissue contributions to the circulating lipid pool in cold exposure via systematic assessment of lipid profiles

Plasma lipid levels are altered in chronic conditions such as type 2 diabetes and cardiovascular disease as well as during acute stresses such as fasting and cold exposure. Advances in MS-based lipidomics have uncovered a complex plasma lipidome of more than 500 lipids that serve functional roles, including as energy substrates and signaling molecules. This plasma lipid pool is maintained through regulation of tissue production, secretion, and uptake. A major challenge in understanding the lipidome complexity is establishing the tissues of origin and uptake for various plasma lipids, which is valuable for determining lipid functions. Using cold exposure as an acute stress, we performed global lipidomics on plasma and in nine tissues that may contribute to the circulating lipid pool. We found that numerous species of plasma acylcarnitines (ACars) and ceramides (Cers) were significantly altered upon cold exposure. Through computational assessment, we identified the liver and brown adipose tissue as major contributors and consumers of circulating ACars, in agreement with our previous work. We further identified the kidney and intestine as novel contributors to the circulating ACar pool and validated these findings with gene expression analysis. Regression analysis also identified that the brown adipose tissue and kidney are interactors with the plasma Cer pool. Taken together, these studies provide an adaptable computational tool to assess tissue contribution to the plasma lipid pool. Our findings have further implications in understanding the function of plasma ACars and Cers, which are elevated in metabolic diseases.

Ontogeny of circulating lipid metabolism in pregnancy and early childhood - a longitudinal population study.

There is mounting evidence that in utero and early life exposures may predispose an individual to metabolic disorders in later life; and dysregulation of lipid metabolism is critical in such outcomes. However, there is limited knowledge about lipid metabolism and factors causing lipid dysregulation in early life that could result in adverse health outcomes in later life. We studied the effect of antenatal factors such as gestational age, birth weight, and mode of birth on lipid metabolism at birth; changes in the circulating lipidome in the first 4 years of life and the effect of breastfeeding in the first year of life. From this study, we aim to generate a framework for deeper understanding into factors effecting lipid metabolism in early life, to provide early interventions for those at risk of developing metabolic disorders including cardiovascular diseases. We performed comprehensive lipid profiling of 1074 mother-child dyads in the Barwon Infant Study (BIS), a population-based pre-birth cohort and measured 776 distinct lipid features across 39 lipid classes using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). We measured lipids in 1032 maternal serum samples at 28 weeks' gestation, 893 cord serum samples at birth, 793, 735, and 511 plasma samples at 6, 12 months, and 4 years, respectively. Cord serum was enriched with long chain poly-unsaturated fatty acids (LC-PUFAs), and corresponding cholesteryl esters relative to the maternal serum. We performed regression analyses to investigate the associations of cord serum lipid species with antenatal factors: gestational age, birth weight, mode of birth and duration of labour. The lipidome differed between mother and newborn and changed markedly with increasing child's age. Alkenylphosphatidylethanolamine species containing LC-PUFAs increased with child's age, whereas the corresponding lysophospholipids and triglycerides decreased. Majority of the cord serum lipids were strongly associated with gestational age and birth weight, with most lipids showing opposing associations. Each mode of birth showed an independent association with cord serum lipids. Breastfeeding had a significant impact on the plasma lipidome in the first year of life, with up to 17-fold increases in a few species of alkyldiaclylglycerols at 6 months of age. This study sheds light on lipid metabolism in infancy and early childhood and provide a framework to define the relationship between lipid metabolism and health outcomes in early childhood. This work was supported by the A*STAR-NHMRC joint call funding (1711624031).

Abstract EP35: Longitudinal Lipidomic Profiling Of Left Ventricular Mass In American Indians: The Strong Heart Study

Background: Dyslipidemia is a major risk factor for CVD. Left ventricular mass (LVM) is an independent predictor of heart failure and other cardiovascular events. It is unclear whether and how altered plasma lipidome (all lipids in a plasma sample) affects LVM. The relationship between longitudinal change in plasma lipidome and change in LVM is also unstudied in any racial/ethnic group. Objective: To identify molecular lipid species associated with LVM, independent of traditional risk factors. Methods: Using an untargeted LC-MS, we repeatedly measured 1,542 lipids in 3,162 fasting plasma samples collected at two time points (2001-2003, 2006-2009, mean 5.5 years apart) from 1,581 American Indians in the Strong Heart Family Study. All participants were free of overt CVD at both time points. LVM was measured by M-mode echocardiography and LVM index (LVMI) was calculated as LVM/height 2.7 . Lipids associated with LVMI were identified by generalized estimating equation (GEE) models, adjusting for age, sex, center, BMI, smoking, blood pressure, renal function, LDL-c, and diabetes. We first conducted the analysis at each time point, separately, and then combined the results by meta-analysis. The longitudinal association between change in lipids and change in LVMI was examined by GEE, adjusting for the same covariates plus baseline lipids and LVMI. Multiple testing was controlled by false discovery rate at 0.05. Results: The mean age of participants was 39.8 years (62.5% women) at baseline and 45.1 years at follow-up. We identified 325 lipids (125 known), largely fatty acyls, sterol lipids, sphingolipids, glycerolipids, and glycerophospholipids, significantly associated with LVMI at both time points. Longitudinal changes in 17 lipids, including glycerolipids, glycerophospholipids, and sphingolipids, were either positively (ORs: 1.09 -1.95) or negatively (ORs: 0.50 - 0.69) associated with change in LVMI over 5 years of follow-up. Changes in lipids explain up to 1.58% of the variability in the change of LVMI during follow-up. Additional adjustments for use of anti-hypertensive and lipid-lowering drugs did not change the results. Conclusion: Altered fasting plasma lipidome and its longitudinal change over time were significantly associated with LVMI beyond clinical factors and baseline lipids. Our results shed light on the mechanisms through which dyslipidemia may affect LV remodeling, thereby contributing to heart failure or other cardiovascular events.

Abstract EP33: Plasma Lipidomic Signatures And Potential Biomarkers For Risk Of Depression: A Longitudinal Study In A Large Sample Of Community-dwelling American Indians In The Strong Heart Study

Background: Depression is an independent risk factor for CVD. Dyslipidemia, an established risk factor for CVD, has also been associated with depression, but a full spectrum of plasma lipidome for risk of depression is still lacking in any racial/ethnic groups. Objective: To identify lipids associated with risk of depression, independent of known clinical factors. Methods: We studied 2,498 fasting plasma samples from 1,249 American Indians attending two exams (2001-2003, 2006-2009, average 5-year apart) in the Strong Heart Study. Plasma lipids were repeatedly measured by LC-MS. Depressive symptoms were assessed using the Center for Epidemiologic Studies for Depression Scale (CES-D). Depression was defined as total CES-D score ≥ 16. All participants were free of overt depression at baseline. Generalized estimating equation was used to identify lipids associated with risk of depression in a discovery sample (N=875), followed by replication in an independent sample (N=374). Results from discovery and replication samples were combined by meta-analysis. The model adjusted for age, sex, study center, BMI, and presence/absence of chronic diseases (e.g., diabetes, hypertension, CVD, CKD). Longitudinal analysis was conducted by regressing changes in lipids on changes in the CES-D score and related psychometric measures (e.g., quality of life, perceived stress, and social support), adjusting for clinical factors and baseline lipids. Network analysis was performed to identify differential lipid networks associated with risk of depression. Multiple testing was controlled at FDR&lt;0.05. Results: Of 1,249 non-depressive participants at baseline (mean age 41, 66% women), 201 individuals (141 in discovery, 60 in replication) developed incident depression after 5-year follow-up. Our lipidomics detected 1,542 lipids (518 known) in 14 lipid classes. Of the 518 known lipids, baseline levels of 9 lipids (e.g., PI(18:1/18:2), SM(d39:1), SM(d41:2)) were associated with a 28-40% decreased risk of depression in both discovery and replication samples. Meta-analysis identified 7 glycerophospholipids (e.g., PC(40:6), PE(16:0/22:5), PI(18:1/18:2)) and 8 sphingomyelins (e.g., SM(d36:3), SM(d40:2), SM(d41:2)) associated with incident depression. Longitudinal changes in long-chain unsaturated fatty acids (e.g., FA(16:1), FA(18:1)) were inversely, while changes in saturated acylcarnitines (e.g., AC(24:0), AC(26:0)) were positively, associated with changes in CES-D score. Network analysis identified two differential lipid modules associated with risk of depression. Conclusion: Novel plasma lipids and lipidomic signatures significantly predict risk of depression beyond clinical factors. Our findings shed light on the mechanisms through which dyslipidemia contributes to depression and provide instrumental data for risk prediction, stratification, and potential therapeutics.

Comparison of the Lipidomic Signature of Fatty Liver in Children and Adults: A Cross-Sectional Study.

ObjectiveNon-alcoholic fatty liver disease (NAFLD) is an increasingly common condition in children characterized by insulin resistance and altered lipid metabolism. Affected patients are at increased risk of cardiovascular disease (CVD) and children with NAFLD are likely to be at risk of premature cardiac events. Evaluation of the plasma lipid profile of children with NAFLD offers the opportunity to investigate these perturbations and understand how closely they mimic the changes seen in adults with cardiometabolic disease.MethodsWe performed untargeted liquid chromatography mass spectrometry (LC-MS) plasma lipidomics on 287 children: 19 lean controls, 146 from an obese cohort, and 122 NAFLD cases who had undergone liver biopsy. Associations between lipid species and liver histology were assessed using regression adjusted for age and sex. Results were then replicated using data from 9,500 adults with metabolic phenotyping.ResultsMore severe paediatric NAFLD was associated with lower levels of long chain, polyunsaturated phosphatidylcholines (PC) and triglycerides (TG). Similar trends in PC and TG chain length and saturation were seen in adults with hepatic steatosis. However, many of the specific lipids associated with NAFLD differed between children and adults. Five lipids replicated in adults (including PC(36:4)) have been directly linked to death and cardiometabolic disease, as well as indirectly via genetic variants.ConclusionThese findings suggest that, whilst similar pathways of lipid metabolism are perturbed in paediatric NAFLD as in cardiometabolic disease in adults, the specific lipid signature in children is different.

Albumin Lipidomics Reveals Meaningful Compositional Changes in Advanced Cirrhosis and Its Potential to Promote Inflammation Resolution.

Albumin infusions are therapeutically used to revert hypoalbuminemia and to replace the extensively oxidized albumin molecule circulating in patients with acutely decompensated (AD) cirrhosis. Because albumin has high affinity for lipids, here we characterized the albumin lipidome in patients with AD and explored the albumin effects on the release of fatty acid (FA)–derived lipid mediators by peripheral leukocytes. Lipids and lipid mediators were measured by liquid chromatography–tandem mass spectrometry in albumin‐enriched and albumin‐depleted plasma fractions separated by affinity chromatography and in leukocyte incubations from 18 patients with AD and 10 healthy subjects (HS). Lipid mediators were also measured in 41 patients with AD included in an albumin therapy trial. The plasma lipidome associated with AD cirrhosis was characterized by generalized suppression of all lipid classes except FAs. In contrast to HS, albumin from patients with AD had lower content of polyunsaturated FAs (PUFAs), especially of the omega‐3‐PUFA docosahexaenoic acid. Consistent with this, the PUFA‐derived lipid mediator landscape of albumin from patients with AD was dominated by lower content of monohydroxy FA precursors of anti‐inflammatory/pro‐resolving lipid mediators (i.e., 15‐hydroxyeicosatetraenoic acid [15‐HETE]). In addition, albumin from patients with AD was depleted in prostaglandin (PG) E2, suggesting that this proinflammatory PG primarily travels disassociated to albumin in these patients. Incubation of leukocytes with exogenous albumin reduced PG production while inducing 15‐lipoxygenase expression and 15‐HETE release. Similar effects were seen under lipopolysaccharide plus N‐formylmethionyl‐leucyl‐phenylalanine‐stimulated conditions. Finally, PG levels were lower in patients with AD receiving albumin therapy, whereas 15‐HETE was increased after albumin treatment compared with baseline. Conclusion: Our findings indicate that the albumin lipid composition is severely disorganized in AD cirrhosis and that administration of exogenous albumin has the potential to redirect leukocyte biosynthesis from pro‐inflammatory to pro‐resolving lipid mediators.

Abstract P2-08-05: Plasma lipidomics analysis to identify potential non-invasive biomarkers for breast white adipose inflammation and aromatase expression levels

Abstract Background: The presence of white adipose tissue inflammation (WATi) in the breast has been associated with increased breast cancer risk and a worse clinical course. Elevated body mass index (BMI) and the post-menopausal state are both associated with breast WATi. Breast WATi has also been associated with increased expression of aromatase, the rate-limiting enzyme for estrogen biosynthesis. Currently, WATi is diagnosed in surgical samples of breast tissue by the identification of crown-like structures (CLS), which are comprised of a dead or dying adipocyte enveloped by macrophages. In contrast to surgical specimens, core biopsies have been shown to be inadequate for assessing WATi. Hence, there is an unmet need for strategies to non-invasively diagnose WATi. Here we used a novel lipidomics platform to identify potential non-invasive blood signatures of breast WATi. Methods: We conducted a cross-sectional study which included 100 patients who underwent mastectomy for breast cancer treatment or risk reduction. WATi was detected by CD68 immunohistochemistry to identify CLS. Breast aromatase expression levels were measured by qPCR. Clinicopathologic data were abstracted from electronic medical records. Lipidomic data were measured from blood plasma in collaboration with Waters Technologies Corporation. Lipid levels in association with breast WATi (presence/absence) and levels of aromatase expression (high/low) in non-tumorous breast tissue were examined using Welch’s t-test. P-values were adjusted for multiple comparisons by controlling the false discovery rate (FDR) using the Benjamini-Hochberg method. A logistic regression model was used to develop predictive models that evaluated potential lipid biomarkers of the presence of breast WATi and high breast aromatase expression levels. Stepwise regression was used for variable selection. AUC of the ROC curves was used to evaluate the performance of the predictive models. Results: Among 140 lipids analyzed, 13 were identified to be associated with breast WATi (P&amp;lt;0.05, |log2FC|&amp;gt;0.3). Specifically, 8 lipids had lower levels, and 6 lipids had higher levels in patients with breast WATi compared to those without. Levels of 7 lipids were significantly higher in patients with an increased level of aromatase (P&amp;lt;0.05, |log2FC|&amp;gt;0.3). After variable selection, LPE(22:6) (P=0.018), LPE(20:3) ES-(P=0.006), along with menopausal status and BMI provided an 86.0% (95% CI, 77.6%-94.5%) accuracy in predicting higher breast aromatase levels. Combining the effect of two lipids improved the accuracy by 10.4%(P=0.030) compared to the model only using menopausal status and BMI. A model with 5 lipids and menopausal status provided an 88.8%(95% CI, 81.9%-95.8%) accuracy for predicting breast WATi. The model performance improved by 9.2% (P=0.026) compared to the model only using menopausal status and BMI. Conclusions: Our study identified several lipid species that showed significant changes in association with breast WATi and levels of aromatase expression. Further validation of these blood signatures could provide non-invasive assessment of WATi and aromatase levels. The availability of such a diagnostic algorithm could help, in turn, to both identify women at elevated risk for breast cancer and for monitoring the efficacy of interventions aimed at reducing inflammation and aromatase levels. Citation Format: Xiao Cai, Siqi Wei, Zizhuo Xu, Xi K Zhou, Andrew Peck, Steven Lai, Giorgis Isaac, Hernando Olivos, Nayasha Munjoma, Suraj Dhungana, Rob Plumb, Andrew J Dannenberg, Neil M Iyengar. Plasma lipidomics analysis to identify potential non-invasive biomarkers for breast white adipose inflammation and aromatase expression levels [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-08-05.

Effect of Omega-3 Polyunsaturated Fatty Acids on Lipid Metabolism in Patients With Metabolic Syndrome and NAFLD.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. n‐3 polyunsaturated fatty acids (n‐3‐PUFAs) have been reported to ameliorate the progression of NAFLD in experimental studies; however, clinical trials have yielded contradictory results. The aim of our study was to assess the effects of n‐3‐PUFA administration on lipid metabolism and the progression of NAFLD in patients with metabolic syndrome. Sixty patients with metabolic syndrome and NAFLD were randomized in a double‐blind placebo‐controlled trial (3.6 g/day n‐3‐PUFA vs. placebo). During the 1‐year follow‐up, the patients underwent periodic clinical and laboratory examinations, liver stiffness measurements, magnetic resonance spectroscopy of the liver, and plasma lipidomic analyses. After 12 months of n‐3‐PUFA administration, a significant decrease in serum GGT activity was recorded compared with the placebo group (2.03 ± 2.8 vs. 1.43 ± 1.6; P < 0.05). Although no significant changes in anthropometric parameters were recorded, a significant correlation between the reduction of liver fat after 12 months of treatment—and weight reduction—was observed; furthermore, this effect was clearly potentiated by n‐3‐PUFA treatment (P < 0.005). In addition, n‐3‐PUFA treatment resulted in substantial changes in the plasma lipidome, with n‐3‐PUFA‐enriched triacylglycerols and phospholipids being the most expressed lipid signatures. Conclusion: Twelve months of n‐3‐PUFA treatment of patients with NAFLD patients was associated with a significant decrease in GGT activity, the liver fat reduction in those who reduced their weight, and beneficial changes in the plasma lipid profile.

Plasma lipidomics analysis reveals altered lipids signature in patients with osteonecrosis of the femoral head.

Although studies have established a link between lipid metabolism disorder and osteonecrosis of the femoral head (ONFH), the characteristics of the circulating lipidome signature of ONFH have not yet been investigated and need to be explored. We aimed to explore the plasma lipidome signatures in patients with ONFH, and to identify specific lipid biomarkers of ONFH. In this study, a comprehensive detection and analysis of plasma lipidomics was conducted in clinical human cohort, including 32 healthy normal control (NC) subjects and 91 ONFH patients in different subgroups [alcohol-induced ONFH (AONFH), steroid-induced ONFH (SONFH), and traumatic-induced ONFH (TONFH)] or at different disease stages (stage I, II, III and IV of ONFH) using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Overall, the plasma lipidome profile differs between ONFH and NC samples. Lipidome signature including 22 common differentially expressed lipids (DELs) in all three subgroups (variable importance in projection > 1, P < 0.05, fold change > 1.5 or < 0.67, compared to the NC group) was identified. Besides, the subtype-specific lipidome profiles for each ONFH subgroup were also analyzed. Generally, the AONFH subgroup has the largest number of DELs, and the plasma levels of triacylglycerol lipid compounds increased obviously in the AONFH samples. In the subgroup of SONFH, the relative abundance of lipid 4-Aminobenzoic acid increased significantly with changes in the expression of several of its interactive genes. We have identified that 9 stage-positive and 2 stage-negative lipids may function as novel biomarkers predicting the progression of ONFH. Our study presents an overview of the phenotype-related plasma lipidome signature of patients with ONFH. The results will provide insight into the mechanisms underlying the metabolism of lipids in the pathogenesis and progression of ONFH and help identify novel lipids biomarkers or disease diagnosis and treatment targets.

Impact of myocardial reperfusion on human plasma lipidome

SummaryThe primary aim of the study is to investigate the temporal changes in plasma lipidome before and after reperfusion in patients with ST-segment elevation myocardial infarction (STEMI) and their association with myocardial injury. We found that 56% of the identified lipid species were significantly altered (corrected p< 0.05) in the first 24 h following reperfusion in patients with STEMI. Three lipid species, namely, acylcarnitine 18:2, TG 51:0, and LPC 17:1 were associated with a change in troponin concentration (delta troponin) and in-hospital cardiovascular events. Of these, acylcarnitine 18:2, and LPC 17:1 and their respective whole class levels, were significantly higher (p < 0.05) in the STEMI population than the age/sex-matched control subjects. Overall, our analyses showed a large shift in plasma lipidome in patients that undergo myocardial reperfusion. The differences found for acylcarnitines and LPC species and their association with both cardiac markers and cardiac outcomes need further validation.

Fetal lipidome and incident risk of food allergy: A prospective birth cohort study.

Lipids are proposed to be important in developing adaptive immunity and allergy. However, studies to date reported inconsistent findings. To examine newborn lipidome (a comprehensive profiling of circulating lipid metabolites) on child's risk of developing food allergy (FA). The maternal-cord joint effects of lipid metabolites on FA development were also investigated. This study included 647mother-child pairs from the Boston Birth Cohort and analyzed 202lipid metabolites in cord plasma profiled by liquid chromatography tandem mass spectrometry. FA was defined based on standard clinical criteria. Logistic regression was applied to examine the relationships between individual metabolites and risk of FA. Of the 647 children, 61 developed FA. Cord triacylglycerols of long carbon chains and multiple double bonds were significantly associated with decreased risk of FA. These associations were comparable across strata of pertinent maternal and child covariates, and were independent of maternal triacylglycerols when assessed simultaneously. Besides, cord and maternal triacylglycerols had an additive effect in association with risk of FA: Children having high (≥Median) C56:8 triacylglycerol levels in both cord and maternal plasma were at the lowest risk of developing FA (OR=0.24, 95% CI=0.10-0.56, p=.001), compared to those having low levels in both cord and maternal plasma. This is the first birth cohort study to link altered cord plasma lipidome with future risk of development FA during childhood. It calls for further investigation on triacylglycerols of long carbon chains and multiple double bonds as potential novel predictive biomarkers and therapeutic targets for FA.