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Clinical Chemistry and Laboratory... Dec 2014Research into lipoprotein metabolism has developed because understanding lipoprotein metabolism has important clinical indications. Lipoproteins are risk factors for... (Review)
Review
Research into lipoprotein metabolism has developed because understanding lipoprotein metabolism has important clinical indications. Lipoproteins are risk factors for cardiovascular disease. Recent advances include the identification of factors in the synthesis and secretion of triglyceride rich lipoproteins, chylomicrons (CM) and very low density lipoproteins (VLDL). These included the identification of microsomal transfer protein, the cotranslational targeting of apoproteinB (apoB) for degradation regulated by the availability of lipids, and the characterization of transport vesicles transporting primordial apoB containing particles to the Golgi. The lipase maturation factor 1, glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 and an angiopoietin-like protein play a role in lipoprotein lipase (LPL)-mediated hydrolysis of secreted CMs and VLDL so that the right amount of fatty acid is delivered to the right tissue at the right time. Expression of the low density lipoprotein (LDL) receptor is regulated at both transcriptional and post-transcriptional level. Proprotein convertase subtilisin/kexin type 9 (PCSK9) has a pivotal role in the degradation of LDL receptor. Plasma remnant lipoproteins bind to specific receptors in the liver, the LDL receptor, VLDL receptor and LDL receptor-like proteins prior to removal from the plasma. Reverse cholesterol transport occurs when lipid free apoAI recruits cholesterol and phospholipid to assemble high density lipoprotein (HDL) particles. The discovery of ABC transporters (ABCA1 and ABCG1) and scavenger receptor class B type I (SR-BI) provided further information on the biogenesis of HDL. In humans HDL-cholesterol can be returned to the liver either by direct uptake by SR-BI or through cholesteryl ester transfer protein exchange of cholesteryl ester for triglycerides in apoB lipoproteins, followed by hepatic uptake of apoB containing particles. Cholesterol content in cells is regulated by several transcription factors, including the liver X receptor and sterol regulatory element binding protein. This review summarizes recent advances in knowledge of the molecular mechanisms regulating lipoprotein metabolism.
Topics: ATP-Binding Cassette Transporters; Apolipoproteins; Cardiovascular Diseases; Cholesterol Ester Transfer Proteins; Chylomicrons; Humans; Lipoproteins; Lipoproteins, HDL; Lipoproteins, VLDL; Phospholipid Transfer Proteins; Receptors, Scavenger
PubMed: 23940067
DOI: 10.1515/cclm-2013-0358 -
Cells Jan 2023Alterations in lipid composition and disturbed lipoprotein metabolism are involved in the pathomechanism of Huntington's disease (HD). Here, we measured 112 lipoprotein...
Alterations in lipid composition and disturbed lipoprotein metabolism are involved in the pathomechanism of Huntington's disease (HD). Here, we measured 112 lipoprotein subfractions and components in the plasma of 20 normal controls, 24 symptomatic (sympHD) and 9 presymptomatic (preHD) HD patients. Significant changes were found in 30 lipoprotein subfractions and components in all HD patients. Plasma levels of total cholesterol (CH), apolipoprotein (Apo)B, ApoB-particle number (PN), and components of low-density lipoprotein (LDL) were lower in preHD and sympHD patients. Components of LDL4, LDL5, LDL6 and high-density lipoprotein (HDL)4 demonstrated lower levels in preHD and sympHD patients compared with controls. Components in LDL3 displayed lower levels in sympHD compared with the controls, whereas components in very low-density lipoprotein (VLDL)5 were higher in sympHD patients compared to the controls. The levels of components in HDL4 and VLDL5 demonstrated correlation with the scores of motor assessment, independence scale or functional capacity of Unified Huntington's Disease Rating Scale. These findings indicate the potential of components of VLDL5, LDL3, LDL4, LDL5 and HDL4 to serve as the biomarkers for HD diagnosis and disease progression, and demonstrate substantial evidence of the involvement of lipids and apolipoproteins in HD pathogenesis.
Topics: Humans; Triglycerides; Huntington Disease; Lipoproteins; Lipoproteins, LDL; Apolipoproteins B; Biomarkers
PubMed: 36766727
DOI: 10.3390/cells12030385 -
European Heart Journal Nov 2023The aims of this study were to investigate lipid parameters during the first 14-16 months of life, to identify influential factors, and to test whether high...
BACKGROUND AND AIMS
The aims of this study were to investigate lipid parameters during the first 14-16 months of life, to identify influential factors, and to test whether high concentrations at birth predict high concentrations at 2- and 14-16 months.
METHODS
The Copenhagen Baby Heart Study, including 13,354 umbilical cord blood samples and parallel venous blood samples from children and parents at birth (n = 444), 2 months (n = 364), and 14-16 months (n = 168), was used.
RESULTS
Concentrations of lipids, lipoproteins, and apolipoproteins in umbilical cord blood samples correlated highly with venous blood samples from newborns. Concentrations of low-density lipoprotein (LDL) cholesterol, non-high-density lipoprotein (HDL) cholesterol, apolipoprotein B, and lipoprotein(a) increased stepwise from birth to 2 months to 14-16 months. Linear mixed models showed that concentrations of LDL cholesterol, non-HDL cholesterol, and lipoprotein(a) above the 80th percentile at birth were associated with significantly higher concentrations at 2 and 14-16 months. Finally, lipid concentrations differed according to sex, gestational age, birth weight, breastfeeding, and parental lipid concentrations.
CONCLUSIONS
Lipid parameters changed during the first 14-16 months of life, and sex, gestational age, birth weight, breastfeeding, and high parental concentrations influenced concentrations. Children with high concentrations of atherogenic lipid traits at birth had higher concentrations at 2 and 14-16 months. These findings increase our knowledge of how lipid traits develop over the first 14-16 months of life and may help in deciding the optimal child age for universal familial hypercholesterolaemia screening.
Topics: Child; Infant, Newborn; Humans; Birth Weight; Triglycerides; Lipids; Apolipoproteins; Cholesterol; Apolipoproteins B; Cholesterol, LDL; Lipoprotein(a); Cholesterol, HDL
PubMed: 37632410
DOI: 10.1093/eurheartj/ehad547 -
European Journal of Nutrition Oct 2021Dyslipidemia is a major health concern associated with an increased risk of cardiovascular mortality. Long-term fasting (LF) has been shown to improve plasma lipid... (Observational Study)
Observational Study
PURPOSE
Dyslipidemia is a major health concern associated with an increased risk of cardiovascular mortality. Long-term fasting (LF) has been shown to improve plasma lipid profile. We performed an in-depth investigation of lipoprotein composition.
METHODS
This observational study included 40 volunteers (50% men, aged 32-65 years), who underwent a medically supervised fast of 14 days (250 kcal/day). Changes in lipid and lipoprotein levels, as well as in lipoprotein subclasses and particles, were measured by ultracentrifugation and nuclear magnetic resonance (NMR) at baseline, and after 7 and 14 fasting days.
RESULTS
The largest changes were found after 14 fasting days. There were significant reductions in triglycerides (TG, - 0.35 ± 0.1 mmol/L), very low-density lipoprotein (VLDL)-TG (- 0.46 ± 0.08 mmol/L), VLDL-cholesterol (VLDL-C, - 0.16 ± 0.03 mmol/L) and low-density lipoprotein (LDL)-C (- 0.72 ± 0.14 mmol/L). Analysis of LDL subclasses showed a significant decrease in LDL1-C (- 0.16 ± 0.05 mmol/L), LDL2-C (- 0.30 ± 0.06 mmol/L) and LDL3-C (- 0.27 ± 0.05 mmol/L). NMR spectroscopy showed a significant reduction in large VLDL particles (- 5.18 ± 1.26 nmol/L), as well as large (- 244.13 ± 39.45 nmol/L) and small LDL particles (- 38.45 ± 44.04 nmol/L). A significant decrease in high-density lipoprotein (HDL)-C (- 0.16 ± 0.04 mmol/L) was observed. By contrast, the concentration in large HDL particles was significantly raised. Apolipoprotein A1 decreased significantly whereas apolipoprotein B, lipoprotein(a), fibrinogen and high-sensitivity C-reactive protein were unchanged.
CONCLUSION
Our results suggest that LF improves lipoprotein levels and lipoprotein subclasses and ameliorates the lipoprotein-associated atherogenic risk profile, suggesting a reduction in the cardiovascular risk linked to dyslipidemia.
TRIAL REGISTRATION
Study registration number: DRKS-ID: DRKS00010111 Date of registration: 03/06/2016 "retrospectively registered".
Topics: Atherosclerosis; Fasting; Female; Humans; Lipoproteins; Lipoproteins, LDL; Lipoproteins, VLDL; Male; Triglycerides
PubMed: 33963431
DOI: 10.1007/s00394-021-02578-0 -
International Journal of Molecular... Oct 2022Alzheimer's disease (AD) is the most common form of dementia in the elderly and has been associated with changes in lipoprotein metabolism. We performed quantitative...
Alzheimer's disease (AD) is the most common form of dementia in the elderly and has been associated with changes in lipoprotein metabolism. We performed quantitative lipoprotein analysis in a local cohort of cognitively impaired elderly and control subjects using standardized nuclear magnetic resonance (NMR) spectroscopy. A commercially available quantitative NMR-based assay covering 112 lipoprotein main and subtype variables was used to investigate blood serum samples from a moderate cohort size of 161 persons (71 female, 90 male), including measures of quality control. Additionally, clinical metadata and cerebrospinal fluid AD biomarkers were collected and used for analysis. High-density lipoprotein (HDL) HDL-4 subfraction levels were mostly high in female individuals with mild cognitive impairment (MCI), followed by AD. Low-density lipoprotein (LDL) LDL-2 cholesterol was slightly elevated in male AD patients. HDL-2 apolipoprotein Apo-A1, HDL-2 phospholipids, and HDL-3 triglycerides were highly abundant in AD and MCI women compared to men. When considering clinical biomarkers (Aβ, tau), very low-density lipoprotein (VLDL) VLDL-1 and intermediate-density lipoprotein (IDL) triglycerides were substantially higher in AD compared to MCI. In addition, triglyceride levels correlated positively with dementia. Different lipoprotein serum patterns were identified for AD, MCI, and control subjects. Interestingly, HDL-4 and LDL-2 cholesterol parameters revealed strong gender-specific changes in the context of AD-driven dementia. As gender-based comparisons were based on smaller sub-groups with a low n-number, several statistical findings did not meet the significance threshold for multiple comparisons testing. Still, our finding suggests that serum HDL-4 parameters and various triglycerides correlate positively with AD pathology which could be a read-out of extended lipids traveling through the blood-brain barrier, supporting amyloid plaque formation processes. Thereof, we see herein a proof of concept that this quantitative NMR-based lipoprotein assay can generate important and highly interesting data for refined AD diagnosis and patient stratification, especially when larger cohorts are available.
Topics: Humans; Female; Male; Aged; Triglycerides; Lipoproteins, IDL; Alzheimer Disease; Serum; Lipoproteins, HDL2; Lipoproteins, HDL3; Lipoproteins; Lipoproteins, LDL; Cholesterol; Cholesterol, LDL; Apolipoproteins; Biomarkers; Magnetic Resonance Spectroscopy; Cholesterol, HDL
PubMed: 36293327
DOI: 10.3390/ijms232012472 -
International Journal of Molecular... Nov 2019Apolipoprotein C1 (apoC1), the smallest of all apolipoproteins, participates in lipid transport and metabolism. In humans, gene is in linkage disequilibrium with gene... (Review)
Review
Apolipoprotein C1 (apoC1), the smallest of all apolipoproteins, participates in lipid transport and metabolism. In humans, gene is in linkage disequilibrium with gene on chromosome 19, a proximity that spurred its investigation. Apolipoprotein C1 associates with triglyceride-rich lipoproteins and HDL and exchanges between lipoprotein classes. These interactions occur via amphipathic helix motifs, as demonstrated by biophysical studies on the wild-type polypeptide and representative mutants. Apolipoprotein C1 acts on lipoprotein receptors by inhibiting binding mediated by apolipoprotein E, and modulating the activities of several enzymes. Thus, apoC1 downregulates lipoprotein lipase, hepatic lipase, phospholipase A2, cholesterylester transfer protein, and activates lecithin-cholesterol acyl transferase. By controlling the plasma levels of lipids, apoC1 relates directly to cardiovascular physiology, but its activity extends beyond, to inflammation and immunity, sepsis, diabetes, cancer, viral infectivity, and-not last-to cognition. Such correlations were established based on studies using transgenic mice, associated in the recent years with GWAS, transcriptomic and proteomic analyses. The presence of a duplicate gene, pseudogene , stimulated evolutionary studies and more recently, the regulatory properties of the corresponding non-coding RNA are steadily emerging. Nonetheless, this prototypical apolipoprotein is still underexplored and deserves further research for understanding its physiology and exploiting its therapeutic potential.
Topics: Amino Acid Motifs; Apolipoprotein C-I; Apolipoproteins E; Chromosome Mapping; Gene Expression Regulation; Humans; Lipid Metabolism; Lipoproteins, HDL; Lipoproteins, VLDL; Protein Binding; Pseudogenes; Receptors, Lipoprotein
PubMed: 31779116
DOI: 10.3390/ijms20235939 -
Journal of Clinical Lipidology 2022Mutations in genes encoding lipoprotein lipase (LPL) or its regulators can cause severe hypertriglyceridemia (HTG). Thus far, the effect of genetic HTG on the lipid...
BACKGROUND
Mutations in genes encoding lipoprotein lipase (LPL) or its regulators can cause severe hypertriglyceridemia (HTG). Thus far, the effect of genetic HTG on the lipid profile has been mainly determined via conventional techniques.
OBJECTIVE
To show detailed differences in the (apo)lipoprotein profile of patients with genetic HTG by combining LC-MS and NMR techniques.
METHODS
Fasted serum from 7 patients with genetic HTG and 10 normolipidemic controls was used to measure the concentration of a spectrum of apolipoproteins by LC-MS, and to estimate the concentration and size of lipoprotein subclasses and class-specific lipid composition using NMR spectroscopy.
RESULTS
Patients with genetic HTG compared to normolipidemic controls had higher levels of apoB48 (fold change [FC] 11.3, P<0.001), apoC-I (FC 1.5, P<0.001), apoC-II (FC 4.3, P=0.007), apoC-III (FC 3.4, P<0.001), and apoE (FC 4.3, P<0.001), without altered apoB100. In addition, patients with genetic HTG had higher concentrations of TG-rich lipoproteins (i.e., chylomicrons and very low-density lipoproteins [VLDL]; FC 3.0, P<0.001), but lower LDL (FC 0.4, P=0.001), of which medium and small-sized LDL particles appeared even absent. While the correlation coefficient between NMR and enzymatic analysis in normolipidemic controls was high, it was considerably reduced in patients with genetic HTG.
CONCLUSION
The lipoprotein profile of patients with genetic HTG is predominated with large lipoproteins (i.e., chylomicrons, VLDL), explaining high levels of apoC-I, apoC-II, apoC-III and apoE, whereas small atherogenic LDL particles are absent. The presence of chylomicrons in patients with HTG weakens the accuracy of the NMR-based model as it was designed for normolipidemic fasted individuals.
Topics: Apolipoprotein C-III; Apolipoproteins; Apolipoproteins E; Chromatography, Liquid; Chylomicrons; Humans; Hyperlipidemias; Hypertriglyceridemia; Lipoproteins, VLDL; Magnetic Resonance Spectroscopy; Tandem Mass Spectrometry; Triglycerides
PubMed: 35568684
DOI: 10.1016/j.jacl.2022.04.004 -
Analytical Chemistry Oct 2018We report an extensive 600 MHz NMR trial of quantitative lipoprotein and small-molecule measurements in human blood serum and plasma. Five centers with eleven 600 MHz...
We report an extensive 600 MHz NMR trial of quantitative lipoprotein and small-molecule measurements in human blood serum and plasma. Five centers with eleven 600 MHz NMR spectrometers were used to analyze 98 samples including 20 quality controls (QCs), 37 commercially sourced, paired serum and plasma samples, and two National Institute of Science and Technology (NIST) reference material 1951c replicates. Samples were analyzed using rigorous protocols for sample preparation and experimental acquisition. A commercial lipoprotein subclass analysis was used to quantify 105 lipoprotein subclasses and 24 low molecular weight metabolites from the NMR spectra. For all spectrometers, the instrument specific variance in measuring internal QCs was lower than the percentage described by the National Cholesterol Education Program (NCEP) criteria for lipid testing [triglycerides <2.7%; cholesterol <2.8%; low-density lipoprotein (LDL) cholesterol <2.8%; high-density lipoprotein (HDL) cholesterol <2.3%], showing exceptional reproducibility for direct quantitation of lipoproteins in both matrixes. The average relative standard deviations (RSDs) for the 105 lipoprotein parameters in the 11 instruments were 4.6% and 3.9% for the two NIST samples, whereas they were 38% and 40% for the 37 commercially sourced plasmas and sera, respectively, showing negligible analytical compared to biological variation. The coefficient of variance (CV) obtained for the quantification of the small molecules across the 11 spectrometers was below 15% for 20 out of the 24 metabolites analyzed. This study provides further evidence of the suitability of NMR for high-throughput lipoprotein subcomponent analysis and small-molecule quantitation with the exceptional required reproducibility for clinical and other regulatory settings.
Topics: Humans; Laboratories; Lipoproteins; Molecular Weight; Nuclear Magnetic Resonance, Biomolecular; Protons; Quality Control
PubMed: 30211542
DOI: 10.1021/acs.analchem.8b02412 -
Journal of the American Heart... Oct 2023Background Associations of coronary heart disease (CHD) with plasma lipids are well described, but the associations with characteristics of lipoproteins (which transport...
Background Associations of coronary heart disease (CHD) with plasma lipids are well described, but the associations with characteristics of lipoproteins (which transport lipids) remain unclear. Methods and Results UK Biobank is a prospective study of 0.5 million adults. Analyses were restricted to 89 422 participants with plasma lipoprotein and apolipoprotein measures from Nightingale nuclear magnetic resonance spectroscopy and without CHD at baseline. CHD risk was positively associated with concentrations of very-low-density lipoproteins, intermediate-density lipoproteins, and low-density lipoproteins (LDL), and inversely associated with high-density lipoproteins. Hazard ratios (99% CIs) per SD were 1.22 (1.17-1.28), 1.16 (1.11-1.21), 1.20 (1.15-1.25), and 0.90 (0.86-0.95), respectively. Larger subclasses of very-low-density lipoproteins were less strongly associated with CHD risk, but associations did not materially vary by size of LDL or high-density lipoprotein. Given lipoprotein particle concentrations, lipid composition (including cholesterol) was not strongly related to CHD risk, except for triglyceride in LDL particles. Apolipoprotein B was highly correlated with LDL concentration (=0.99), but after adjustment for apolipoprotein B, concentrations of very-low-density lipoprotein and high-density lipoprotein particles remained strongly related to CHD risk. Conclusions This large-scale study reliably quantifies the associations of nuclear magnetic resonance-defined lipoprotein characteristics with CHD risk. CHD risk was most strongly related to particle concentrations, and separate measurements of lipoprotein concentrations may be of greater value than the measurement by apolipoprotein B, which was largely determined by LDL concentration alone. Furthermore, there was strong evidence of positive association with mean triglyceride molecules per LDL particle but little evidence of associations with total triglycerides or other lipid and lipoprotein fractions after accounting for lipoprotein concentrations.
Topics: Adult; Humans; Prospective Studies; Biological Specimen Banks; Cholesterol, LDL; Lipoproteins; Coronary Disease; Lipoproteins, LDL; Lipoproteins, HDL; Lipoproteins, VLDL; Triglycerides; Apolipoproteins B; United Kingdom
PubMed: 37815053
DOI: 10.1161/JAHA.123.029552 -
Biochimica Et Biophysica Acta Jan 2013Negative-staining (NS), a rapid, simple and conventional technique of electron microscopy (EM), has been commonly used to initially study the morphology and structure of... (Review)
Review
BACKGROUND
Negative-staining (NS), a rapid, simple and conventional technique of electron microscopy (EM), has been commonly used to initially study the morphology and structure of proteins for half a century. Certain NS protocols however can cause artifacts, especially for structurally flexible or lipid-related proteins, such as lipoproteins. Lipoproteins were often observed in the form of rouleau as lipoprotein particles appeared to be stacked together by conventional NS protocols. The flexible components of lipoproteins, i.e. lipids and amphipathic apolipoproteins, resulted in the lipoprotein structure being sensitive to the NS sample preparation parameters, such as operational procedures, salt concentrations, and the staining reagents.
SCOPE OF REVIEW
The most popular NS protocols that have been used to examine lipoprotein morphology and structure were reviewed.
MAJOR CONCLUSIONS
The comparisons show that an optimized NS (OpNS) protocol can eliminate the rouleau artifacts of lipoproteins, and that the lipoproteins are similar in size and shape as statistically measured from two EM methods, OpNS and cryo-electron microscopy (cryo-EM). OpNS is a high-throughput, high-contrast and high-resolution (near 1nm, but rarely better than 1nm) method which has been used to discover the mechanics of a small protein, 53kDa cholesterol ester transfer protein (CETP), and the structure of an individual particle of a single protein by individual-particle electron tomography (IPET), i.e. a 14Å-resolution IgG antibody three-dimensional map.
GENERAL SIGNIFICANCE
It is suggested that OpNS can be used as a general protocol to study the structure of proteins, especially highly dynamic proteins with equilibrium-fluctuating structures.
Topics: Animals; Cryoelectron Microscopy; Humans; Lipoproteins; Negative Staining
PubMed: 23032862
DOI: 10.1016/j.bbagen.2012.09.016