Sex-specific trajectories of molecular cardiometabolic trait concentrations through childhood, adolescence and young adulthood: a cohort study

Background: Causal risk factors and predictive biomarkers for cardiometabolic diseases are increasingly being identified from comprehensive metabolomic profiling in epidemiological studies. The changes which typically occur in molecular cardiometabolic traits across early life are not well characterised. Methods: We quantified sex-specific trajectories of 148 metabolic trait concentrations including various lipoprotein subclasses from age 7y to 25y. Data were from offspring of the Avon Longitudinal Study of Parents and Children birth cohort study. Outcomes included concentrations of 148 traits quantified using nuclear magnetic resonance spectroscopy measured at 7y, 15y, 18y and 25y. Sex-specific trajectories of each trait concentration were modelled using linear spline multilevel models with robust standard errors. Findings: 7,065-7,626 participants (11,702-14,797 repeated measures) were included in analyses. Females had higher very-low-density lipoprotein (VLDL) particle concentrations at 7y. VLDL particle concentrations decreased from 7y to 25y with larger decreases in females, leading to lower VLDL particle concentrations at 25y in females. For example, females had 0.25 SD (95% Confidence Interval (CI), 0.20, 0.31) higher very small VLDL particle concentration at 7y; mean levels decreased by 0.06 SDs (95% CI, -0.01, 0.13) in males and 0.85 SDs (95% CI, 0.79, 0.90) in females from 7y to 25y leading to 0.42 SD (95% CI, 0.35, 0.48) lower very small VLDL particle concentrations in females at 25y. Females also had higher low-density lipoprotein (LDL) particle concentrations at 7y; these increased from 7y to 25y in both sexes and increases were larger among males. By age 25y, LDL particle concentrations remained higher in females but the sex difference was smaller than in early childhood. Females had lower high-density lipoprotein (HDL) particle concentrations at 7y. HDL particle concentrations increased from 7y to 25y with larger increases among females leading to higher HDL particle concentrations in females at 25y. Interpretation: Childhood and adolescence are important periods for the emergence of sex differences in atherogenic lipids and predictive biomarkers for cardiometabolic disease, mostly to the detriment of males.

Endotoxemia is associated with an adverse metabolic profile

Our aim was to analyze whether endotoxemia, i.e. translocation of LPS to circulation, is reflected in the serum metabolic profile in a general population and in participants with cardiometabolic disorders. We investigated three Finnish cohorts separately and in a meta-analysis ( n = 7178), namely population-based FINRISK97, FinnTwin16 consisting of young adult twins, and Parogene, a random cohort of cardiac patients. Endotoxemia was determined as serum LPS activity and metabolome by an NMR platform. Potential effects of body mass index (BMI), smoking, metabolic syndrome (MetS), and coronary heart disease (CHD) status were considered. Endotoxemia was directly associated with concentrations of VLDL, IDL, LDL, and small HDL lipoproteins, VLDL particle diameter, total fatty acids (FA), glycoprotein acetyls (GlycA), aromatic and branched-chain amino acids, and Glc, and inversely associated with concentration of large HDL, diameters of LDL and HDL, as well as unsaturation degree of FAs. Some of these disadvantageous associations were significantly stronger in smokers and subjects with high BMI, but did not differ between participants with different CHD status. In participants with MetS, however, the associations of endotoxemia with FA parameters and GlycA were particularly strong. The metabolic profile in endotoxemia appears highly adverse, involving several inflammatory characters and risk factors for cardiometabolic disorders.

Use of Centrifugation to Reduce the Interference Rate of an NMR-Based Lipoprotein Assay

Physicians are increasingly using nuclear magnetic resonance (NMR) analysis of lipoproteins to assess patients’ cardiovascular disease risk. For certain lipid measurements, like the standard lipid panel, which includes cholesterol, HDL-C, LDL-C, and triglycerides, there is debate about the necessity of fasting prior to a blood draw because the results may still be useful in the nonfasting state. Unfortunately, nonfasting specimens are poorly tolerated in NMR spectroscopy due to spectral overlap of chylomicrons and free fatty acids with other lipoprotein particles. However, it is unknown if valid lipoprotein levels can be extracted from these specimens. Approximately 5% of patient samples submitted for analysis have interferences that prevent analytical deconvolution of the NMR spectral data with the Numares Health AXINON LipoFIT assay. Retrospective review of patient samples from our laboratory showed that the interference rate increased with increasing triglyceride concentrations. Therefore, we hypothesized that sample centrifugation would reduce interference by low-density lipids on the NMR measurement. Preanalytical treatment consisted of centrifugation of 1 mL of serum at 13,000 rcf for 20 minutes followed by carefully pipetting 750 to 800 μL of serum from the lower half of the tube for the NMR measurement, thus avoiding the low-density chylomicrons and lipids at the top. To ensure that centrifugation does not disrupt the measured lipoproteins, a control set of 20 deidentified samples with previous NMR results received our preanalytical treatment and were reanalyzed. To test if centrifugation reduced interferences, a test set of 20 deidentified samples without NMR results due to interference were subjected to the preanalytical treatment and reanalyzed. The pre- and postspin results were analyzed, and the pre- and postspin spectra were compared. Our results showed that, for the control set, the average percent differences for all eight parameters determined by NMR (LDL, HDL, small-LDL, large-HDL, and large-VLDL particle numbers, and particle sizes of LDL, HDL, and VLDL) were within our acceptable limits of ≤10%. The pre- and postspin spectra of the controls were nearly identical. Fourteen of the 20 test samples (70%) achieved results after the preanalytical treatment. Visual inspection of test samples suggested that some, but not all, test samples had chylomicrons present due to the appearance of an upper white layer after centrifugation. The spectral comparison of pre- and postspin samples showed slight changes in the lipoprotein region. In conclusion, our study demonstrates that centrifugation is a promising preanalytical treatment to reduce the interference rate for NMR measurements of lipoproteins. Future goals include expanding this study to a larger sample set and determining if we can better identify samples that may benefit from this preanalytical treatment. In addition, the results suggest that there are other sources of interferences to investigate to improve the performance of the LipoFIT assay.

Association of lipoprotein subfractions and glycoprotein acetylation with coronary plaque burden in SLE

ObjectiveSubjects with SLE display an enhanced risk of atherosclerotic cardiovascular disease (CVD) that is not explained by Framingham risk. This study sought to investigate the utility of nuclear MR (NMR) spectroscopy measurements of serum lipoprotein particle counts and size and glycoprotein acetylation (GlycA) burden to predict coronary atherosclerosis in SLE.MethodsCoronary plaque burden was assessed in SLE subjects and healthy controls using coronary CT angiography. Lipoproteins and GlycA were quantified by NMR spectroscopy.ResultsSLE subjects displayed statistically significant decreases in high-density lipoprotein (HDL) particle counts and increased very low-density lipoprotein (VLDL) particle counts compared with controls. Non-calcified coronary plaque burden (NCB) negatively associated with HDL subsets whereas it positively associated with VLDL particle counts in multivariate adjusted models. GlycA was significantly increased in SLE sera compared with controls. In contrast to high-sensitivity C reactive protein, elevations in GlycA in SLE significantly associated with NCB and insulin resistance (IR), though the association with NCB was no longer significant after adjusting for prednisone use.ConclusionsPatients with SLE display a proatherogenic lipoprotein profile that may significantly contribute to the development of premature CVD. The results demonstrate that NMR measures of GlycA and lipoprotein profiles, beyond what is captured in routine clinical labs, could be a useful tool in assessing CVD risk in patients with SLE.

Diet quality as assessed by the Healthy Food Intake Index and relationship with serum lipoprotein particles and serum fatty acids in pregnant women at increased risk for gestational diabetes

The importance of overall diet in modifying circulating lipoprotein particles and fatty acids during pregnancy is unclear. We examined the relationships of diet quality as assessed by the validated Healthy Food Intake Index (HFII) with serum HDL, LDL and VLDL particle concentrations and sizes and proportions of serum fatty acids in pregnant women at high risk for gestational diabetes mellitus (GDM). Overall, 161 women with a BMI of ≥30 kg/m2 and/or a history of GDM were drawn from the Finnish Gestational Diabetes Prevention Study, which is a dietary and exercise intervention trial to prevent GDM. At baseline, the HFII score was inversely related to concentrations of HDL particles (P=0·010) and MUFA (P=0·010) and positively related to concentrations of n-3 (P<0·001) and n-6 (P=0·003) PUFA. The significance for MUFA disappeared after adjustments. An increase in the HFII score from the first to second trimester of pregnancy correlated with reduced VLDL particle size (r −0·16, 95 % CI −0·31, −0·01), decreased MUFA concentrations (r −0·17, 95 % CI −0·31, −0·01) and elevated n-6 PUFA concentrations (r 0·16, 95 % CI 0·01, 0·31). In the maximum-adjusted model, the results remained significant except for VLDL particle size. These findings suggest that higher diet quality as defined by the HFII is related to a more favourable serum fatty acid profile, whereas the relationship with serum lipoprotein profile is limited in pregnant women at increased GDM risk.

ChREBP Rather than SHP Regulates Hepatic VLDL Secretion

The regulation of hepatic very-low-density lipoprotein (VLDL) secretion plays an important role in the pathogenesis of dyslipidemia and fatty liver diseases. VLDL is controlled by hepatic microsomal triglyceride transfer protein (MTTP). Mttp is regulated by carbohydrate response element binding protein (ChREBP) and small heterodimer partner (SHP). However, it is unclear whether both coordinately regulate Mttp expression and VLDL secretion. Here, adenoviral overexpression of ChREBP and SHP in rat primary hepatocytes induced and suppressed Mttp mRNA, respectively. However, Mttp induction by ChREBP was much more potent than suppression by SHP. Promoter assays of Mttp and the liver type pyruvate kinase gene revealed that SHP and ChREBP did not affect the transactivity of each other. Mttp mRNA and protein levels of Shp/&ndash; mice were similar to those of wild-type; however, those of Chrebp&ndash;/&ndash;Shp&ndash;/&ndash; and Chrebp&ndash;/&ndash; mice were much lower. Consistent with this, the VLDL particle number and VLDL secretion rates in Shp&ndash;/&ndash;- mice were similar to wild-type, but were much lower in Chrebp&ndash;/&ndash; and Chrebp&ndash;/&ndash;Shp&ndash;/&ndash;- mice. These findings suggested that ChREBP rather than SHP regulates VLDL secretion and that ChREBP and SHP do not affect the transactivities of each other.

Moderate dyslipoproteinemia induced inflammation and remodeling HDL and VLDL particles in post-renal transplant patients

The aim of this paper was to examine whether moderate dyslipoproteinemia can cause an increase of hsCRP and LPO levels in Tx patients who had received immunosuppressive therapy and were without acute inflammatory diseases. Herein, the lipid levels, hsCRP, LPO, apolipoprotein (apo)B, AI, AII, AIInonB, apoB-containing AII (apoB:AII), apoCIII, apoCIIInonB, apoB:CIII, LCAT level, as well as CETP and PON1 activity were determined. All examined Tx patients had moderate dyslipidemia and slightly increased hsCRP, LPO, apoB:AII and apoCIII levels, but decreased LCAT mass, PON1 activity and lipoprotein ratios. Tx patients with apoAI<150 mg/dl (n=28) had worse lipoprotein profiles than did Tx patients with apoAI>150mg/dl (n=39), but no difference in CETP activity was indicated. Multiple ridge forward regression and Spearman’s correlation test were used. The results of the presented study, show for the first time that higher apoAI/apoB and apoAI/apoCIII ratios induced a decrease of the hsCRP concentration. Moreover, the composition of apoCIIInonB, LDL-C and apoAI brought about an increase of LCAT mass and PON1 activity. In Tx patients with lower concentration of apoAI, an increase of concentration of apoB:AII in VLDL generated a mild oxidation of lipoprotein and an elevated concentration of LPO. However, lower ApoAI/apoB ratio resulted in an increase of PON1 activity and apoB, as well as nonHDL-C levels, and in turn, PON1 activity increased LCAT mass. These disorders rearranged the HDL particle, and, simultaneously, remodeled the VLDL particle. This may prevent antioxidant activity, reverse cholesterol transport and accelerate the rejection of the transplant, as well as bringing about cardiovascular diseases in Tx patients with lower apoAI. Such metabolic pathways can be used as potentially novel targets for pharmacological intervention.

Abstract 239: LDL Apheresis Is Associated With a Reduction in Markers of Chronic Inflammation in Patients With Familial Hypercholesterolemia

Background: Familial Hypercholesterolemia is an inherited disease characterized by severely elevated levels of LDL cholesterol (LDL-C) and associated with premature coronary artery disease (CAD). LDL apheresis (LA) is indicated for management of CAD patients with LDL-C>200 mg/dl despite medical therapy. LA may reduce LDL-C concentrations by up to 70%; this in turn has been associated with regression of atherosclerosis. NMR measurement of signals corresponding to methyl group protons of glycoproteins (GlycA and GlycB) has recently been validated in prediction of atherosclerosis and chronic systemic inflammation. Studies have demonstrated a reduction in inflammatory cytokines with LA, but no study to date has evaluated the impact of LA on levels of glycoproteins as markers of chronic inflammation. Objective: To determine the effect of LA on plasma levels of glycoproteins using a novel NMR based technique, and to correlate these findings with changes in lipoprotein subclasses. Methods: Comprehensive NMR lipoprotein analysis was performed on serum obtained from seven subjects prior to and following LA sessions performed at two-week intervals (N = 47 paired samples). Three subjects had homozygous FH, three had heterozygous FH with CAD and/or LDL-C > 200 mg/dL, one patient had severe mixed dyslipidemia with CAD and LDL-C > 200 mg/dL. Results: Mean GlycA and GlycB levels were 335±91 μmol/L and 125±31 μmol/L respectively prior to LA. Following LA treatment, there was a significant reduction in GlycA to 277±73 μmol/L (P<0.001) and in GlycB to 102±28 μmol/L (P<0.001). The reduction in GlycA was strongly correlated with a decrease in total small LDL particle number (r = 0.68, p < 0.001) and with a reduction in medium VLDL particle number (r = 0.52, P < 0.001). GlycB level was weakly correlated with small LDL (r = 0.39, P = 0.007) and IDL particle numbers (r = 0.32, P = 0.028). In addition, GlycA and GlycB levels were correlated to each other (r = 0.49, P < 0.001). Conclusion: This is the first report of NMR detection of glycoproteins as inflammatory biomarkers in patients with severe dyslipidemia undergoing LA. LA was associated with a significant reduction in levels of both GlycA and GlycB, which correlated with reductions in LDL and VLDL particle number.