Using lipid profiling to better characterize metabolic differences in apolipoprotein E (APOE) genotype among community-dwelling older Black men.

Apolipoprotein E (APOE) allelic variation is associated with differences in overall circulating lipids and risks of major health outcomes. Lipid profiling provides the opportunity for a more detailed description of lipids that differ by APOE, to potentially inform therapeutic targets for mitigating higher morbidity and mortality associated with certain APOE genotypes. Here, we sought to identify lipids, lipid-like molecules, and important mediators of fatty acid metabolism that differ by APOE among 278 Black men ages 70-81. Using liquid chromatography-mass spectrometry methods, 222 plasma metabolites classified as lipids, lipid-like molecules, or essential in fatty acid metabolism were detected. We applied principal factor analyses to calculate a factor score for each main lipid category. APOE was categorized as ε4 carriers (n = 83; ε3ε4 or ε4ε4), ε2 carriers (n = 58; ε2ε3 or ε2ε2), or ε3 homozygotes (n = 137; ε3ε3). Using analysis of variance, the monoacylglycerol factor, cholesterol ester factor, the factor for triacylglycerols that consist mostly of polyunsaturated fatty acids, sphingosine, and free carnitine significantly differed by APOE (p < 0.05, false discovery rate < 0.30). The monoacylglycerol factor, cholesterol ester factor, and sphingosine were lower, whereas the factor for triacylglycerols that consisted mostly of polyunsaturated fatty acids was higher among ε2 carriers than remaining participants. Free carnitine was lower among ε4 carriers than ε3 homozygotes. Lower monoacylglycerols and cholesteryl esters and higher triacylglycerols that consist mostly of polyunsaturated fatty acids may be protective metabolic characteristics of APOE ε2 carriers, whereas lower carnitine may reflect altered mitochondrial functioning among ε4 carriers in this cohort of older Black men.

Associations between fatty acid composition in serum cholesteryl esters and liver fat, basal fat oxidation, and resting energy expenditure: a population-based study.

BACKGROUND: We have repeatedly shown in short-term feeding trials that a high intake of dietary n-6 PUFAs, i.e. linoleic acid, prevents liver fat accumulation compared with saturated fat. However, population-based data is lacking and the mechanisms behind such effects are unclear. OBJECTIVE: To investigate associations between serum cholesteryl ester (CE) fatty acids and liver fat, basal fat oxidation [respiratory quotient (RQ)], and resting energy expenditure (REE). We hypothesized that PUFA in particular is inversely associated with liver fat and that such a relation is partly explained by a PUFA-induced increase in basal fat oxidation or REE. METHODS: Cross-sectional analyses using linear regression models in a population-based cohort with data on serum CE fatty acid composition and liver fat (n = 308). RESULTS: Linoleic acid (18:2n-6) (ß = -0.03, 95% CI: -0.06, -0.001) and Δ5 desaturase index were inversely associated, whereas, γ-linolenic acid (18:3n-6) (ß = 0.59, 95% CI: 0.28, 0.90), dihomo-γ-linolenic acid (20:3n-6) (ß = 1.20, 95% CI: 0.65, 1.75), arachidonic acid (20:4n-6) (ß = 0.08, 95% CI: 0.002, 0.16), palmitoleic acid (16:1n-7) (ß = 0.37, 95% CI: 0.04, 0.70), Δ6 desaturase, and stearoyl CoA desaturase-1 (SCD-1) index were directly associated with liver fat after adjustment for confounders. Several serum CE fatty acids were correlated with both liver fat and REE, but only the association between DHA (22:6n-3) and liver fat was clearly attenuated after adjustment for REE (from ß = -0.63 95% CI: -1.24, -0.02 to ß = -0.34, 95% CI: -0.95, 0.27). Palmitoleic acid and SCD-1 were weakly inversely correlated with RQ but could not explain a lower liver fat content. CONCLUSIONS: Several serum CE fatty acids are associated with liver fat, among them linoleic acid. Although we identified novel associations between individual fatty acids and RQ and REE, our findings imply that PUFAs might prevent liver fat accumulation through mechanisms other than enhanced whole-body energy metabolism.

Intraperitoneal Administration of Short-Chain Fatty Acids Improves Lipid Metabolism of Long-Evans Rats in a Sex-Specific Manner.

Short-chain fatty acids (SCFAs) are microbial metabolites, mainly generated by the action of gut microbiota on dietary fibers. Acetate, propionate, and butyrate are the three main SCFAs produced typically in a 60:20:20 molar ratio in the colon. Acetate, propionate, and butyrate, when given individually as supplements, have shown a protective role in obesity and hyperglycemia; however, the sex-specific effects of a mixture of SCFAs, when given in 60:20:20 ratio, on the regulation of lipid metabolism and lipid profile are not known. Male and female Long-Evans rats were given a mixture of SCFAs (acetate, propionate, and butyrate; molar ratio 60:20:20) each day for seven days intraperitoneally; plasma and hepatic lipids, gene expression, and lipidomics profile were analyzed. SCFAs significantly decreased plasma and hepatic triglycerides and cholesterol in males, whereas the fatty acyl composition of cholesteryl esters, triglycerides, and phospholipids was modulated in females. SCFAs decreased the mRNA expression of hepatic acetyl-CoA carboxylase-1 in both males and females. Our findings demonstrate for the first time that SCFAs (60:20:20) improved plasma and hepatic lipid levels and fatty acyl composition in a manner that may provide cardio-protective and anti-inflammatory effects in both sexes, via independent mechanisms.

Comprehensive lipid and metabolite profiling in healthy adults with low and high consumption of fatty fish: a cross-sectional study.

Fish consumption is associated with reduced risk of CVD, which may be partly mediated by alterations in plasma lipids, such as HDL-cholesterol. However, comprehensive analyses of associations between fatty fish consumption and lipoprotein subclass profile are limited and show inconsistent results. Therefore, the aim of the present exploratory study was to investigate the association between fatty fish consumption and lipoprotein subclass particle concentrations and composition, with an emphasis on HDL. We performed a comprehensive plasma metabolite profiling in 517 healthy adults, using a targeted high-throughput NMR spectroscopy platform. The participants were divided into tertiles based on consumption of fatty fish, reported through a validated FFQ. We compared the concentration of metabolites between the participants in the lowest and highest tertiles of fatty fish consumption. We show that high consumers of fatty fish (>223 g/week, median intake 294 g/week) had higher particle concentrations and content of total lipids, free cholesterol and phospholipids in large and extra-large HDL particles and higher content of total cholesterol, cholesteryl esters and TAG in large HDL particles than low consumers (<107 g/week, median intake 58 g/week). Using fatty fish consumption as a continuous variable, we found that fatty fish consumption was associated with lower levels of the inflammation marker glycoprotein acetyls. In conclusion, high consumers of fatty fish seem to have a more favourable HDL-cholesterol-related lipoprotein profile and anti-inflammatory phenotype than low consumers of fatty fish. Thus, these data support the current Norwegian dietary recommendations for fish consumption regarding CVD risk.

Toward reliable low-density lipoprotein ultrastructure prediction in clinical conditions: A small-angle X-ray scattering study on individuals with normal and high triglyceride serum levels.

Atherosclerosis is the main killer in the west and therefore a major health challenge today. Total serum cholesterol and lipoprotein concentrations, used as clinical markers, fail to predict the majority of cases, especially between the risk scale extremes, due to the high complexity in lipoprotein structure and composition. In particular, low-density lipoprotein (LDL) plays a key role in atherosclerosis development, with LDL size being a parameter considered for determining the risk for cardiovascular diseases. Determining LDL size and structural parameters is challenging to address experimentally under physiological-like conditions. This article describes the biochemistry and ultrastructure of normolipidemic and hypertriglyceridemic LDL fractions and subfractions using small-angle X-ray scattering. Our results conclude that LDL particles of hypertriglyceridemic compared to healthy individuals 1) have lower LDL core melting temperature, 2) have lower cholesteryl ester ordering in their core, 3) are smaller, rounder and more spherical below melting temperature, and 4) their protein-containing shell is thinner above melting temperature.

SR-BI deficiency disassociates obesity from hepatic steatosis and glucose intolerance development in high fat diet-fed mice.

Scavenger receptor BI (SR-BI) has been suggested to modulate adipocyte function. To uncover the potential relevance of SR-BI for the development of obesity and associated metabolic complications, we compared the metabolic phenotype of wild-type and SR-BI deficient mice fed an obesogenic diet enriched in fat. Both male and female SR-BI knockout mice gained significantly more weight as compared to their wild-type counterparts in response to 12 weeks high fat diet feeding (1.5-fold; P < .01 for genotype). Plasma free cholesterol levels were ~2-fold higher (P < .001) in SR-BI knockout mice of both genders, whilst plasma cholesteryl ester and triglyceride concentrations were only significantly elevated in males. Strikingly, the exacerbated obesity in SR-BI knockout mice was paralleled by a better glucose handling. In contrast, only SR-BI knockout mice developed atherosclerotic lesions in the aortic root, with a higher predisposition in females. Biochemical and histological studies in male mice revealed that SR-BI deficiency was associated with a reduced hepatic steatosis degree as evident from the 29% lower (P < .05) liver triglyceride levels. Relative mRNA expression levels of the glucose uptake transporter GLUT4 were increased (+47%; P < .05), whilst expression levels of the metabolic PPARgamma target genes CD36, HSL, ADIPOQ and ATGL were reduced 39%-58% (P < .01) in the context of unchanged PPARgamma expression levels in SR-BI knockout gonadal white adipose tissue. In conclusion, we have shown that SR-BI deficiency is associated with a decrease in adipocyte PPARgamma activity and a concomitant uncoupling of obesity development from hepatic steatosis and glucose intolerance development in high fat diet-fed mice.

Comparison of the Postprandial Metabolic Fate of U-13C Stearic Acid and U-13C Oleic Acid in Postmenopausal Women.

OBJECTIVE: Compare the postprandial fatty acid metabolism of isotopically labeled stearate (U-13C18:0) and oleate (U-13C18:1). Approach and Results: In conjunction with a randomized-controlled crossover trial, 6 hypercholesterolemic postmenopausal women (≥50 years; body mass index: 25.6±3.0 kg/m2; LDL [low-density lipoprotein]-cholesterol ≥110 mg/dL) consumed isocaloric diets enriched in 18:0 or 18:1 (10%-15% E) for 5 weeks each. On day 1 of week 5, following a 12-hour fast, participants receive their experimental diet divided into 13 hourly meals beginning at 8 am. U-13C18:0 or U-13C18:1 was incorporated into the 1:00 pm meal (1.0 mg/kg body weight). Serial blood and breath samples were collected over 12 hours and fasting samples at 24 and 48 hours. Plasma and lipid subfraction fatty acid profiles were assessed by gas chromatography-flame ionization detector, isotope-enrichment by liquid chromatography time-of-flight mass spectrometry, and fatty acid oxidation rate (expired 13CO2) by isotope ratio mass spectrometry. Both diets resulted in similar plasma LDL-cholesterol concentrations. Kinetic curves showed that U-13C18:0 had a higher plasma area under the curve (66%), lower plasma clearance rate (-46%), and a lower cumulative oxidation rate (-34%) than U-13C18:1. Three labeled plasma metabolites of U-13C18:0 were detected: 13C16:0, 13C16:1, and 13C18:1. No plasma metabolites of U-13C18:1 were detected within the study time-frame. Higher incorporation of 18:0 in cholesteryl ester and triglyceride fractions was observed on the 18:0 compared with the 18:1 diet. CONCLUSIONS: The neutrality of 18:0 on plasma LDL-cholesterol concentrations is not attributable to a single factor. Compared with 18:1, 18:0 had higher plasma area under the curve because of lower clearance and oxidation rates, underwent both a direct and a multistage conversion to 18:1, and was preferentially incorporated into cholesteryl esters and triglycerides.

Plasma Lipidomics Reveals Insights into Anti-Obesity Effect of Chrysanthemum morifolium Ramat Leaves and Its Constituent Luteolin in High-Fat Diet-Induced Dyslipidemic Mice.

The Chrysanthemum morifolium Ramat (CM) is widely used as a traditional medicine and herbal tea by the Asian population for its health benefits related to obesity. However, compared to the flowers of CM, detailed mechanisms underlying the beneficial effects of its leaves on obesity and dyslipidemia have not yet been elucidated. Therefore, to investigate the lipidomic biomarkers responsible for the pharmacological effects of CM leaf extract (CLE) in plasma of mice fed a high-fat diet (HFD), the plasma of mice fed a normal diet (ND), HFD, HFD plus CLE 1.5% diet, and HFD plus luteolin 0.003% diet (LU) for 16 weeks were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with multivariate analysis. In our analysis, the ND, HFD, CLE, and LU groups were clearly differentiated by partial least-squares discriminant analysis (PLS-DA) score plots. The major metabolites contributing to this differentiation were cholesteryl esters (CEs), lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), ceramides (CERs), and sphingomyelins (SMs). The levels of plasma CEs, LPCs, PCs, SMs, and CERs were significantly increased in the HFD group compared to those in the ND group, and levels of these lipids recovered to normal after administration of CLE or LU. Furthermore, changes in hepatic mRNA expression levels involved in the Kennedy pathway and sphingolipid biosynthesis were also suppressed by treatment with CLE or LU. In conclusion, this study examined the beneficial effects of CLE and LU on obesity and dyslipidemia, which were demonstrated as reduced synthesis of lipotoxic intermediates. These results may provide valuable insights towards evaluating the therapeutic effects of CLE and LU and understanding obesity-related diseases.

Androgen deprivation therapy improves the in vitro capacity of high-density lipoprotein (HDL) to receive cholesterol and other lipids in patients with prostate carcinoma.

BACKGROUND: Androgen deprivation therapy (ADT) is widely used in the treatment of testosterone-dependent prostate carcinomas. ADT often increases plasma LDL and HDL cholesterol and triglycerides. The aim was to test whether ADT changes the transfer of lipids to HDL, an important aspect of this metabolism and HDL protective functions, and related parameters. METHODS: Sixteen volunteers with advanced prostate carcinoma submitted to pharmacological ADT or orchiectomy had plasma collected shortly before and after 6 months of ADT. In vitro transfer of lipids to HDL was performed by incubating plasma with donor emulsion containing radioactive lipids by 1 h at 37 °C. After chemical precipitation of apolipoprotein B-containing lipoprotein, the radioactivity of HDL fraction was counted. RESULTS: ADT reduced testosterone to nearly undetectable levels and markedly diminished PSA. ADT increased the body weight but glycemia, triglycerides, LDL and HDL cholesterol, HDL lipid composition and CETP concentration were unchanged. However, ADT increased the plasma unesterified cholesterol concentration (48 ± 12 vs 56 ± 12 mg/dL, p = 0.019) and LCAT concentration (7.15 ± 1.81 vs 8.01 ± 1.55µg/mL, p = 0.020). Transfer of unesterified (7.32 ± 1.09 vs 8.18 ± 1.52%, p < 0.05) and esterified cholesterol (6.15 ± 0.69 vs 6.94 ± 1.29%, p < 0.01) and of triglycerides (6.37 ± 0.43 vs 7.18 ± 0.91%, p < 0.001) to HDL were increased after ADT. Phospholipid transfer was unchanged. CONCLUSION: Increase in transfer of unesterified and esterified cholesterol protects against cardiovascular disease, as shown previously, and increased LCAT favors cholesterol esterification and facilitates the reverse cholesterol transport. Thus, our results suggest that ADT may offer anti-atherosclerosis protection by improving HDL functional properties. This could counteract, at least partially, the eventual worse effects on plasma lipids.

Consumption of a diet high in dairy leads to higher 15:0 in cholesteryl esters of healthy people when compared to diets high in meat and grain.

BACKGROUND AND AIMS: A higher dairy product intake has been associated to higher blood concentrations of 15:0 (pentadecanoic acid), 17:0 (margaric acid), and 14:0 (myristic acid). This study investigates whether a diet high in dairy products influences cholesteryl ester fatty acid concentrations of these specific fatty acids (FA). METHODS AND RESULTS: In a randomized multiple cross-over study, 13 men and 17 women aged 22 ± 4 years with a BMI of 21.6 ± 2.2 kg/m2 received 3 isocaloric intervention diets (dairy, meat or grain) in random order. For this post-hoc analysis, FA in plasma cholesteryl esters were measured using gas chromatography. We performed a linear mixed model per centered log-ratio transformed FA, adjusting for period, and the interaction between diet and period. Consumed total fat intake per controlled intervention diet was 31.0 ± 0.9 en%/day (dairy), 31.5 ± 0.6 en%/day (meat), and 28.4 ± 1.2 en%/day (grain), respectively. The dairy diet led to higher relative concentrations of 15:0 when compared to diets high in meat and grain, (ß; 0.27, 95%CI: 0.18,0.37; p = 1.2 × 10-5, and ß: 0.15; 95%CI: 0.06,0.24; p = 1.2 × 10-2, respectively). The dairy diet also led to higher 14:0 when compared to the meat diet (ß: 0.34; 95%CI: 0.21,0.46; p = 6.0 × 10-5), but not when compared to the grain diet. 17:0 did not differ between diets. CONCLUSION: The plasma cholesteryl ester fraction after a diet high in dairy was characterized by higher 15:0 levels. Concentrations of 14:0 were only higher when comparing the FA profile after a diet high in dairy when compared to a diet high in meat. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT01314040.

LIPA gene mutations affect the composition of lipoproteins: Enrichment in ACAT-derived cholesteryl esters.

BACKGROUND AND AIMS: Cholesteryl ester storage disease (CESD) due to LIPA gene mutations is characterized by hepatic steatosis, hypercholesterolemia and hypoalphalipoproteinemia, exposing affected patients to an increased cardiovascular risk. Further insights into the impact of LIPA gene mutations on lipid/lipoprotein metabolism are limited. Aim of the study was to investigate the effect of carrying one or two mutant LIPA alleles on lipoprotein composition and function. METHODS: Lipoproteins were isolated from 6 adult CESD patients, 5 relatives carrying one mutant LIPA allele (carriers) and 12 sex/age matched controls. Lipid profile, lipoprotein mass composition and the fatty acid distribution of cholesteryl esters (CEs) were assessed. HDL function was evaluated as the ability to promote nitric oxide release by endothelial cells. RESULTS: Despite the lipid-lowering therapy, total cholesterol, LDL-cholesterol and triglycerides were increased in CESD patients compared to controls, while HDL-cholesterol was reduced. Carriers also displayed elevated total and LDL-cholesterol. Very low and intermediate density lipoproteins from CESD patients and carriers were enriched in CEs compared to the control ones, with a concomitant reduction of triglycerides. Fatty acid composition of CEs in serum and lipoproteins showed a depletion of linoleate content in CESD patients, due to the reduced LCAT activity. In CESD HDL, fatty acid distribution of CEs was shifted towards saturated ones, if compared to control HDL. The changes in HDL composition did not affect HDL ability to promote nitric oxide release by endothelial cells. CONCLUSIONS: LIPA gene mutations significantly affected plasma levels and lipid composition of lipoproteins, likely contributing to the increased cardiovascular risk of affected patients.

Disruption of Phospholipid Transfer Protein-Mediated High-Density Lipoprotein Maturation Reduces Scavenger Receptor BI Deficiency-Driven Atherosclerosis Susceptibility Despite Unexpected Metabolic Complications.

OBJECTIVE: We tested the hypothesis that enlarged, dysfunctional HDL (high-density lipoprotein) particles contribute to the augmented atherosclerosis susceptibility associated with SR-BI (scavenger receptor BI) deficiency in mice. Approach and Results: We eliminated the ability of HDL particles to fully mature by targeting PLTP (phospholipid transfer protein) functionality. Particle size of the HDL population was almost fully normalized in male and female SR-BI×PLTP double knockout mice. In contrast, the plasma unesterified cholesterol to cholesteryl ester ratio remained elevated. The PLTP deficiency-induced reduction in HDL size in SR-BI knockout mice resulted in a normalized aortic tissue oxidative stress status on Western-type diet. Atherosclerosis susceptibility was-however-only partially reversed in double knockout mice, which can likely be attributed to the fact that they developed a metabolic syndrome-like phenotype characterized by obesity, hypertriglyceridemia, and a reduced glucose tolerance. Mechanistic studies in chow diet-fed mice revealed that the diminished glucose tolerance was probably secondary to the exaggerated postprandial triglyceride response. The absence of PLTP did not affect LPL (lipoprotein lipase)-mediated triglyceride lipolysis but rather modified the ability of VLDL (very low-density lipoprotein)/chylomicron remnants to be cleared from the circulation by the liver through receptors other than SR-BI. As a result, livers of double knockout mice only cleared 26% of the fractional dose of [14C]cholesteryl oleate after intravenous VLDL-like particle injection. CONCLUSIONS: We have shown that disruption of PLTP-mediated HDL maturation reduces SR-BI deficiency-driven atherosclerosis susceptibility in mice despite the induction of proatherogenic metabolic complications in the double knockout mice.

Serum paraoxonase-1 activity in tail and mammary veins of ketotic dairy cows.

The objective of this study was to evaluate the association between ketonemia and serum paraoxonase-1 (PON1), malondialdehyde (MDA), and other blood components in tail and mammary veins of dairy cows. Forty-two Holstein dairy cows with decreased feed intake were divided into HIGH (≥ 1.2 mM; n = 31) and LOW (< 1.2 mM; n = 11) groups based on the ß-hydroxybutyrate concentration in plasma collected from the tail vein. The HIGH group had a significantly greater plasma non-esterified fatty acid (NEFA) concentration, but significantly lower serum PON1 activity and phospholipid concentration, and a tendency to have a lower cholesterol ester concentration than the LOW group. Serum PON1 activity was not correlated with the MDA concentration but was positively correlated with serum concentrations of cholesterol esters and phospholipids, and negatively correlated with the plasma NEFA concentration. These results suggest that serum PON1 activity is reduced by hyperketonemia and the relevance of PON1 to MDA seems to not be direct, though it is involved.

L'objectif de la présente étude était d'évaluer l'association entre l'acétonémie et la paraoxonase-1 (PON1), le malondialdéhyde (MDA), et d'autres composés du sang dans les veines caudale et mammaire de vaches laitières. Quarante-deux vaches laitières de race Holstein présentant une diminution de l'ingestion d'aliments furent divisées en groupes ÉLEVÉ (≥ 1,2 mM; n = 31) et BAS (< 1,2 mM; n = 11) basés sur la concentration de ß-hydroxybutyrate de plasma prélevé de la veine caudale. Le groupe ÉLEVÉ avait une concentration plasmatique significativement plus grande d'acides gras non-estérifiés (NEFA), mais le sérum présentait une activité PON1 et une concentration de phospholipides significativement réduite, et une tendance à avoir une concentration d'esters de cholestérol plus faible que le groupe BAS. L'activité de PON1 sérique n'était pas corrélée avec la concentration de MDA mais était corrélée positivement avec les concentrations sériques d'esters de cholestérol et de phospholipides, et corrélée négativement avec la concentration plasmatique de NEFA. Ces résultats suggèrent que l'activité de PON1 sérique est réduite par l'hypercétonémie et la pertinence de PON1 envers MDA ne semble pas être directe, bien qu'elle semble impliquée.(Traduit par Docteur Serge Messier).

Hyperalphalipoproteinemic scavenger receptor BI knockout mice exhibit a disrupted epidermal lipid barrier.

Scavenger receptor class B type I (SR-BI) mediates the selective uptake of cholesteryl esters (CE) from high-density lipoproteins (HDL). An impaired SR-BI function leads to hyperalphalipoproteinemia with elevated levels of cholesterol transported in the HDL fraction. Accumulation of cholesterol in apolipoprotein B (apoB)-containing lipoproteins has been shown to alter skin lipid composition and barrier function in mice. To investigate whether these hypercholesterolemic effects on the skin also occur in hyperalphalipoproteinemia, we compared skins of wild-type and SR-BI knockout (SR-BI-/-) mice. SR-BI deficiency did not affect the epidermal cholesterol content and induced only minor changes in the ceramide subclasses. The epidermal free fatty acid (FFA) pool was, however, enriched in short and unsaturated chains. Plasma CE levels strongly correlated with epidermal FFA C18:1 content. The increase in epidermal FFA coincided with downregulation of cholesterol and FFA synthesis genes, suggesting a compensatory response to increased flux of plasma cholesterol and FFAs into the skin. Importantly, the SR-BI-/- epidermal lipid barrier showed increased permeability to ethyl-paraminobenzoic acid, indicating an impairment of the barrier function. In conclusion, increased HDL-cholesterol levels in SR-BI-/- mice can alter the epidermal lipid composition and lipid barrier function similarly as observed in hypercholesterolemia due to elevated levels of apoB-containing lipoproteins.

Multivariate Analysis for Molecular Species of Cholesteryl Ester in the Human Serum.

Cholesteryl ester (CE) is an ester of cholesterol and fatty acid (FA). Plasma CE reflects complicated metabolisms of cholesterol, phospholipids, lipoproteins, and dietary FAs. An informatics approach could be useful for analysis of the CE species. In this study, two basic dimension reduction methods, principal component analysis (PCA) and factor analysis, were applied to serum CE species determined by LC-MS/MS in a Japanese population (n = 545). PCA and factor analysis both reflected the size (concentration), food source, fat solubility, and biological aspect of the CE species. In a comparison between PCA (PC4) and factor analysis (factor 4), the latter was found to be more suggestive from a biological aspect of n-6 FAs. Cholesteryl docosahexaenoate (DHA) was found to be unique by a factor analysis, possibly relevant to the unique accumulation of DHA in the brain. An informatics approach, especially factor analysis, might be useful for the analysis of complicated metabolism of CE species in the serum.

Relationship between the lipid composition of maternal plasma and infant plasma through breast milk.

INTRODUCTION: This study was motivated by the report that infant development correlates with particular lipids in infant plasma. OBJECTIVE: The hypothesis was that the abundance of these candidate biomarkers is influenced by the dietary intake of the infant. METHODS: A cohort of 30 exclusively-breastfeeding mother-infant pairs from a small region of West Africa was used for this observational study. Plasma and milk from the mother and plasma from her infant were collected within 24 h, 3 months post partum. The lipid, sterol and glyceride composition was surveyed using direct infusion MS in positive and negative ion modes. Analysis employed a combination of univariate and multivariate tests. RESULTS: The lipid profiles of mother and infant plasma samples are similar but distinguishable, and both are distinct from milk. Phosphatidylcholines (PC), cholesteryl esters (CEs) and cholesterol were more abundant in mothers with respect to their infants, e.g. PC(34:1) was 5.66% in mothers but 3.61% in infants (p = 3.60 × 10-10), CE(18:2) was 8.05% in mothers but 5.18% in infants (p = 1.37 × 10-11) whilst TGs were lower in mothers with respect to their infants, e.g. TG(52:2) was 2.74% in mothers and 4.23% in infants (p = 1.63 × 10-05). A latent structure model showed that four lipids in infant plasma previously shown to be biomarkers clustered with cholesteryl esters in the maternal circulation. CONCLUSION: This study found evidence that the abundance of individual lipid isoforms associated with infant development are associated with the abundance of individual molecular species in the mother's circulation.

Comparison of the Utility of Total Plasma Fatty Acids Versus those in Cholesteryl Ester, Phospholipid, and Triglyceride as Biomarkers of Fatty Acid Intake.

Total plasma fatty acids or those in cholesteryl ester and phospholipids are often used to reflect fatty acid intake in epidemiological studies, but their relative performance as biomarkers of intake has not been clearly evaluated within a single population. The assessment of fatty acids in plasma fractions is more labor intensive. Thus, their use as biomarkers of dietary intake needs to be justified. Dietary intake was assessed in 200 population-based controls from a case-control study of diet and heart disease in Costa Rica by a validated food frequency questionnaire (FFQ). Fatty acids in fasting whole plasma and plasma fractions (cholesteryl ester, phospholipid, and triglyceride + free fatty acid) were measured in the 200 controls by the same laboratory using gas chromatography with flame ionization detection (GC-FID). We compared the plasma and plasma fractions data with the FFQ and adipose fatty acid profile using partial Spearman correlations to assess utility as biomarkers of intake and exposure. We found that whole plasma was equally or more strongly correlated with the FFQ and adipose fatty acid profile than either cholesteryl ester or phospholipid in most of the established markers of dietary intake, including dairy (15:0 and 17:0) and seafood (eicosapentaenoic acid and docosahexaenoic acid). Of the three plasma fractions, only fatty acids in the plasma triglyceride + free fatty acid fraction had stronger correlations with dietary intake than whole plasma. In our study population, fatty acids measured in fasting whole plasma perform as good as or better than those measured in plasma fractions as biomarkers for dietary fatty acid intake. Thus, the fractionation of plasma to evaluate long-term fatty acid intake may not be warranted.

Serum lipidomics for exploring biomarkers of bortezomib therapy in patients with multiple myeloma.

Although the proteasome inhibitor bortezomib (BTZ) shows excellent efficacy in multiple myeloma (MM), a fraction of patients has a suboptimal or no response to this agent. In addition, BTZ-induced peripheral neuropathy (BiPN), a frequent side-effect of this therapy, limits its use in some patients. This study aimed to explore serum lipid biomarker candidates to predict the response to BTZ and the severity of BiPN. Fifty-nine serum samples were collected from patients with MM prior to receiving BTZ plus low-dose dexamethasone therapy. Serum levels of phospholipids, sphingolipids, neutral lipids, and polyunsaturated fatty acids and their oxidation products were measured by a comprehensive lipidomic study. Overall, 385 lipid metabolites were identified in patients' sera; lower levels of several glycerophospholipids, sphingolipids, and cholesteryl esters were associated with a poor treatment response. Metabolites related to platelet-activating factor biosynthesis and cholesterol metabolism appeared particularly relevant. Furthermore, several lysophosphatidylcholines, phosphatidylcholines, ceramides, neutral lipids, and oxidative fatty acids were significantly increased or decreased in patients with BiPN grades ranging from G0 to G3. Among these compounds, mediators reportedly inducing myelin breakdown and stimulating inflammatory responses were prominent. Although further study is necessary to validate these biomarker candidates, our results contribute to the development of predictive biomarkers for response to BTZ treatment, or ensuing severe BiPN, in patients with MM.

Mapping Unsaturation in Human Plasma Lipids by Data-Independent Ozone-Induced Dissociation.

Over 1500 different lipids have been reported in human plasma at the sum composition level. Yet the number of unique lipids present is surely higher, once isomeric contributions from double bond location(s) and fatty acyl regiochemistry are considered. In order to resolve this ambiguity, herein, we describe the incorporation of ozone-induced dissociation (OzID) into data-independent shotgun lipidomics workflows on a high-resolution hybrid quadrupole-Orbitrap platform. In this configuration, [M + Na]+ ions generated by electrospray ionization of a plasma lipid extract were transmitted through the quadrupole in 1 Da segments. Reaction of mass-selected lipid ions with ozone in the octopole collision cell yielded diagnostic ions for each double bond position. The increased ozone concentration in this region significantly improved ozonolysis efficiency compared with prior implementations on linear ion-trap devices. This advancement translates into increased lipidome coverage and improvements in duty cycle for data-independent MS/MS analysis using shotgun workflows. Grouping all precursor ions with a common OzID neutral loss enables straightforward classification of the lipidome by unsaturation position (with respect to the methyl terminus). Two-dimensional maps obtained from this analysis provide a powerful visualization of structurally related lipids and lipid isomer families within plasma. Global profiling of lipid unsaturation in plasma extracts reveals that most unsaturated lipids are present as isomeric mixtures. These new insights provide a unique picture of underlying metabolism that could in the future provide novel indicators of health and disease.