Profile of Lipoprotein Subclasses in Chinese Primary Open-Angle Glaucoma Patients.

To investigate the plasma lipoprotein subclasses in patients with primary open-angle glaucoma (POAG), a total of 20 Chinese POAG patients on intraocular pressure (IOP)-lowering treatment and 20 age-matched control subjects were recruited. Based on the levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), the study subjects were divided into elevated- and normal-level subgroups. The plasma lipoprotein, lipoprotein subclasses, and oxidized LDL (oxLDL) levels were quantitatively measured. The discrimination potential of the lipoproteins was evaluated using the area under the receiver operating characteristic curve (AUC), and their correlation with clinical parameters was also evaluated. Compared to the control subjects with elevated TC and/or LDL-C levels, the levels of TC, LDL-C, non-high-density lipoprotein cholesterol (non-HDL), LDL subclass LDL3 and small dense LDL (sdLDL), and oxLDL were significantly higher in POAG patients with elevated TC and/or LDL-C levels. No differences in any lipoproteins or the subclasses were found between the POAG patients and control subjects with normal TC and LDL-C levels. Moderate-to-good performance of TC, LDL-C, non-HDL, LDL3, sdLDL, and oxLDL was found in discriminating between the POAG patients and control subjects with elevated TC and/or LDL-C levels (AUC: 0.710-0.950). Significant negative correlations between LDL3 and sdLDL with retinal nerve fiber layer (RNFL) thickness in the superior quadrant and between LDL3 and average RNFL thickness were observed in POAG patients with elevated TC and/or LDL-C levels. This study revealed a significant elevation of plasma lipoproteins, especially the LDL subclasses, in POAG patients with elevated TC and/or LDL-C levels, providing insights on monitoring specific lipoproteins in POAG patients with elevated TC and/or LDL-C.

Lipoprotein subtypes after testosterone therapy in transmasculine adolescents.

Differences in lipoprotein-particle subclasses between men and women start in puberty and narrow after menopause, suggesting a role for sex steroids. In this cross-sectional cohort study, we examined lipoprotein subtype profiles in transmasculine adolescents treated with testosterone. Transmasculine adolescents (n = 17) had lipoprotein profiles that were similar to those of cisgender males (n = 33) and more atherogenic than those of cisgender females (n = 32), with higher concentrations of small low-density lipoprotein (LDL) particles (435 ± 222 nmol/L vs. 244 ± 163 nmol/L, p = 0.008) and lower concentrations of large high-density lipoprotein (HDL) particles (1.5 ± 1.3 µmol/L vs 2.7 ± 1.2 µmol/L, p = 0.003) when compared to cisgender females. Thus, testosterone appears to be a major contributor to differences in lipoprotein profiles, a surrogate for cardiovascular disease risk, between cisgender women and both transgender and cisgender men.

Comparing dietary score associations with lipoprotein particle subclass profiles: A cross-sectional analysis of a middle-to older-aged population.

BACKGROUND AND OBJECTIVES: Lipoprotein particle concentrations and size are associated with increased risk for atherosclerosis and premature cardiovascular disease. Studies also suggest that certain dietary behaviours may be cardioprotective. Limited comparative data regarding any dietary score/index-lipoprotein particle subclass associations exist. Thus, our objective was to assess relationships between the Dietary Approaches to Stop Hypertension (DASH), Health Eating Index-2015 (HEI-2015), Mediterranean Diet (MD) and Energy-adjusted Dietary Inflammatory Index (E-DII™) scores and plasma lipids and lipoprotein profiles to test the hypothesis that healthier diet (better quality and more anti-inflammatory) would be associated with a more favourable lipoprotein profile. MATERIALS AND METHODS: This was a cross-sectional study of 1862 men and women aged 46-73 years, randomly selected from a large primary care centre in Ireland. DASH, HEI-2015, MD and E-DII scores were derived from food frequency questionnaires. Lipoprotein subclass particle concentrations and size were determined using nuclear magnetic resonance spectroscopy. Correlation and multivariate-adjusted linear regression analyses with correction for multiple testing were performed to examine dietary score relationships with lipoprotein particle subclasses. RESULTS: In fully adjusted models, higher diet quality or a more anti-inflammatory diet was associated with less large and medium very low-density lipoprotein (VLDL) (DASH and HEI-2015), intermediate-density lipoprotein (IDL) (DASH, MD and E-DII) and small high-density lipoprotein (HDL) (DASH, HEI-2015 and E-DII) particles. After accounting for multiple testing, relationships with large VLDL (DASH: ß = -0.102, p = .037), IDL (DASH: ß = -0.089, p = .037) and small HDL (DASH: ß = -0.551, p = .014 and E-DII: ß = 0.483, p = .019) concentrations persisted. CONCLUSIONS: These findings provide evidence that better diet quality, determined by the DASH score, may be more closely associated with a more favourable lipoprotein particle subclass profile in middle-to older-aged adults than the HEI-2015, MD and E-DII scores. A less pro-atherogenic lipoprotein status may be a potential mechanism underlying the cardioprotective effects of higher dietary quality.

Effect of a dietary intervention with functional foods on LDL-C concentrations and lipoprotein subclasses in overweight subjects with hypercholesterolemia: Results of a controlled trial.

BACKGROUND & AIMS: Cardiovascular diseases (CVDs) are the leading cause of global death. Hypercholesterolemia is among the main risk factors for developing cardiovascular events, and is highly prevalent in the Mexican population. The primary objective of the present work was to assess the effect of a dietary portfolio (DP) with functional foods containing dehydrated nopal, soy protein, chia seeds, inulin, and oats in LDL-C and TC concentrations of subjects with mild hypercholesterolemia. Also, we explored the changes in the profile of the lipoprotein subclasses measured by nuclear magnetic resonance spectroscopy (NMR). METHODS: Sixty-two subjects (47 women, 15 men) with mild hypercholesterolemia (LDL-C, ≥130 ≤ 190 mg/dL, TC > 200 mg/dL) completed the randomized, parallel, controlled study. The dietary intervention was given in two stages. First, a dietary standardization stage with a low saturated fat diet (LSFD) which matched the habitual energy intake of the volunteers for 2-weeks, followed by 2.5 months of dietary intervention with a LSFD plus placebo (PL) or DP. RESULTS: Subjects who consumed the LSFD + DP interventions had a significantly higher reduction of LDL-C (-18.05%, P = 0.003) and TC (-17.08%, P = 0.02) compared to volunteers who consumed an LSFD for the same period. Furthermore, the lipoprotein subclass profiling showed that the small low-density-lipoproteins, and the small high-density-lipoproteins significantly decreased (P = 0.04, P < 0.001, respectively), conveying a less atherogenic state. At the end of the study, 78% of the subjects who consumed LSFD + DP reduced their LDL-C below 160 mg/dL, and of these, 47% reduced it below 130 mg/dL. CONCLUSIONS: Based on the results obtained from this study, the inclusion of functional foods as part of the lifestyle modifications is recommended to treat mild hypercholesterolemia and reduce cardiovascular risk. Registered under ClinicalTrials.gov Identifier no. NCT04148976.

DpaA Detaches Braun's Lipoprotein from Peptidoglycan.

Gram-negative bacteria have a unique cell envelope with a lipopolysaccharide-containing outer membrane that is tightly connected to a thin layer of peptidoglycan. The tight connection between the outer membrane and peptidoglycan is needed to maintain the outer membrane as an impermeable barrier for many toxic molecules and antibiotics. Enterobacteriaceae such as Escherichia coli covalently attach the abundant outer membrane-anchored lipoprotein Lpp (Braun's lipoprotein) to tripeptides in peptidoglycan, mediated by the transpeptidases LdtA, LdtB, and LdtC. LdtD and LdtE are members of the same family of ld-transpeptidases but they catalyze a different reaction, the formation of 3-3 cross-links in the peptidoglycan. The function of the sixth homologue in E. coli, LdtF, remains unclear, although it has been shown to become essential in cells with inhibited lipopolysaccharide export to the outer membrane. We now show that LdtF hydrolyzes the Lpp-peptidoglycan linkage, detaching Lpp from peptidoglycan, and have renamed LdtF to peptidoglycan meso-diaminopimelic acid protein amidase A (DpaA). We show that the detachment of Lpp from peptidoglycan is beneficial for the cell under certain stress conditions and that the deletion of dpaA allows frequent transposon inactivation in the lapB (yciM) gene, whose product downregulates lipopolysaccharide biosynthesis. DpaA-like proteins have characteristic sequence motifs and are present in many Gram-negative bacteria, of which some have no Lpp, raising the possibility that DpaA has other substrates in these species. Overall, our data show that the Lpp-peptidoglycan linkage in E. coli is more dynamic than previously appreciated.IMPORTANCE Gram-negative bacteria have a complex cell envelope with two membranes and a periplasm containing the peptidoglycan layer. The outer membrane is firmly connected to the peptidoglycan by highly abundant proteins. The outer membrane-anchored Braun's lipoprotein (Lpp) is the most abundant protein in E. coli, and about one-third of the Lpp molecules become covalently attached to tripeptides in peptidoglycan. The attachment of Lpp to peptidoglycan stabilizes the cell envelope and is crucial for the outer membrane to function as a permeability barrier for a range of toxic molecules and antibiotics. So far, the attachment of Lpp to peptidoglycan has been considered to be irreversible. We have now identified an amidase, DpaA, which is capable of detaching Lpp from peptidoglycan, and we show that the detachment of Lpp is important under certain stress conditions. DpaA-like proteins are present in many Gram-negative bacteria and may have different substrates in these species.

Changes in lipoprotein particle subclasses, standard lipids, and apolipoproteins after supplementation with n-3 or n-6 PUFAs in abdominal obesity: A randomized double-blind crossover study.

BACKGROUND & AIMS: Marine-derived omega-3 (n-3) polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower circulating levels of triacylglycerols (TAGs), and the plant-derived omega-6 (n-6) PUFA linoleic acid (LA) may reduce cholesterol levels. Clinical studies on effects of these dietary or supplemental PUFAs on other blood fat fractions are few and have shown conflicting results. This study aimed to determine effects of high-dose supplemental n-3 (EPA + DHA) and n-6 (LA) PUFAs from high-quality oils on circulating lipoprotein subfractions and standard lipids (primary outcomes), as well as apolipoproteins, fatty acids, and glycemic control (secondary outcomes), in females and males with abdominal obesity. METHODS: This was a randomized double-blind crossover study with two 7-wk intervention periods separated by a 9-wk washout phase. Females (n = 16) were supplemented with 3 g/d of EPA + DHA (TAG fish oil) or 15 g/d of LA (safflower oil), while males (n = 23) received a dose of 4 g/d of EPA + DHA or 20 g/d of LA. In fasting blood samples, we investigated lipoprotein particle subclasses by nuclear magnetic resonance spectroscopy, as well as standard lipids, apolipoproteins, fatty acid profiles, and glucose and insulin. Data were analyzed by linear mixed-effects modeling with 'subjects' as the random factor. RESULTS: The difference between interventions in relative change scores was among the lipoprotein subfractions significant for total very-low-density lipoproteins (VLDLs) (n-3 vs. n-6: -38%∗ vs. +16%, p < 0.001; ∗: significant within-treatment change score), large VLDLs (-58%∗ vs. -0.91%, p < 0.001), small VLDLs (-57%∗ vs. +41%∗, p < 0.001), total low-density lipoproteins (LDLs) (+5.8%∗ vs. -4.3%∗, p = 0.002), large LDLs (+23%∗ vs. -2.1%, p = 0.004), total high-density lipoproteins (HDLs) (-6.0%∗ vs. +3.7%, p < 0.001), large HDLs (+11%∗ vs. -5.3%, p = 0.001), medium HDLs (-24%∗ vs. +6.2%, p = 0.030), and small HDLs (-9.9%∗ vs. +9.6%∗, p = 0.002), and among standard lipids for TAGs (-16%∗ vs. -2.6%, p = 0.014), non-esterified fatty acids (-19%∗ vs. +5.5%, p = 0.033), and total cholesterol (-0.28% vs. -4.4%∗, p = 0.042). A differential response in relative change scores was also found for apolipoprotein (apo)B (+0.40% vs. -6.0%∗, p = 0.008), apoA-II (-6.0%∗ vs. +1.5%, p = 0.001), apoC-II (-11%∗ vs. -1.7%, p = 0.025), and apoE (+3.3% vs. -3.8%, p = 0.028). CONCLUSIONS: High-dose supplementation of high-quality oils with n-3 (EPA + DHA) or n-6 (LA) PUFAs was followed by reductions in primarily TAG- or cholesterol-related markers, respectively. The responses after both interventions point to changes in the lipoprotein-lipid-apolipoprotein profile that have been associated with reduced cardiometabolic risk, also among people with TAG or LDL-C levels within the normal range. REGISTRATION: Registered under ClinicalTrials.gov Identifier: NCT02647333. CLINICAL TRIAL REGISTRATION: Registered at https://clinicaltrials.gov/ct2/show/NCT02647333.

Association between postprandial lipoprotein subclasses and Framingham cardiovascular disease risk stratification.

OBJECTIVE: To determine the ability of postprandial lipoprotein subclass concentrations to stratify patients with respect to their risk for cardiovascular disease (CVD). METHODS: Using the Framingham cardiovascular disease risk score (FRS) algorithm, a total of 112 consecutive patients referred for community health screening were stratified into two groups: (a) low-risk (FRS < 10%) and (b) intermediate/high-risk (FRS ≥ 10%). Serum lipoprotein subclass concentrations were determined by Vertical Auto Profile (VAP-II). RESULTS: Fasting and postprandial levels of LDL4, HDL2, VLDL1 + 2, VLDL3, and RLP, as well as fasting levels of ApoB and postprandial levels of LDL3 and IDL1, were significantly different in the intermediate/high risk FRS group vs. the low-risk group (P < 0.05). Correlations between Framingham CVD risk and LDL3, LDL4, IDL1, VLDL1 + 2, VLDL3, RLP, and ApoB were positive while negative for HDL2 in both the fasting and postprandial states. Intermediate/high risk for CVD was shown to be significantly associated with both fasting and postprandial levels of VLDL1 + 2 and RLP, as well as with postprandial LDL4 and VLDL3, as determined using forward conditional logistic regression analysis. Postprandial levels of VLDL1 + 2 were better at identifying patients in the intermediate/high-risk FRS group than fasting levels, although the differences were not significant due to overlapping reference intervals. In addition, the association between RLP and VLDL subclasses relative to Framingham CVD risk increased significantly in the postprandial state (ΔR2 = 0.023; ΔF = 7.178; ΔP = 0.025) but not in the fasting state. CONCLUSIONS: The use of postprandial lipoprotein subclass concentrations is not inferior to the use of fasting levels in identifying intermediate/high-risk FRS individuals. In addition, changes in RLP and VLDL subclass concentrations in fasting vs. postprandial states may reveal lipid metabolic mechanisms associated with CVD.

Effects of Acute Cocoa Supplementation on Postprandial Apolipoproteins, Lipoprotein Subclasses, and Inflammatory Biomarkers in Adults with Type 2 Diabetes after a High-Fat Meal.

Dyslipidemia and inflammation exacerbate postprandial metabolic stress in people with diabetes. Acute dietary supplementation with polyphenols shows promise in improving postprandial metabolic stress in type 2 diabetes (T2D). Cocoa is a rich source of dietary polyphenols with demonstrated cardioprotective effects in adults without diabetes. To date, the acute effects of cocoa on postprandial lipids and inflammation have received little attention in the presence of T2D. This report expands on our earlier observation that polyphenol-rich cocoa, given as a beverage with a fast-food-style, high-fat breakfast, increased postprandial high-density lipoprotein-cholesterol (HDL-C) in adults with T2D. We now test whether polyphenol-rich cocoa modulated postprandial apolipoproteins (Apo-A1, B), non-esterified fatty acids, nuclear magnetic resonance (NMR)-derived lipoprotein subclass profiles, and select biomarkers of inflammation following the same dietary challenge. We found that cocoa decreased NMR-derived concentrations of total very low-density lipoprotein and chylomicron particles and increased the concentration of total HDL particles over the 6-hour postprandial phase. Serum interleukin-18 was decreased by cocoa vs. placebo. Thus, polyphenol-rich cocoa may alleviate postprandial dyslipidemia and inflammation following a high-fat dietary challenge in adults with T2D. The study was registered at clinicaltrials.gov as NCT01886989.

Lipoprotein signatures of cholesteryl ester transfer protein and HMG-CoA reductase inhibition.

Cholesteryl ester transfer protein (CETP) inhibition reduces vascular event risk, but confusion surrounds its effects on low-density lipoprotein (LDL) cholesterol. Here, we clarify associations of genetic inhibition of CETP on detailed lipoprotein measures and compare those to genetic inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR). We used an allele associated with lower CETP expression (rs247617) to mimic CETP inhibition and an allele associated with lower HMGCR expression (rs12916) to mimic the well-known effects of statins for comparison. The study consists of 65,427 participants of European ancestries with detailed lipoprotein subclass profiling from nuclear magnetic resonance spectroscopy. Genetic associations were scaled to 10% reduction in relative risk of coronary heart disease (CHD). We also examined observational associations of the lipoprotein subclass measures with risk of incident CHD in 3 population-based cohorts totalling 616 incident cases and 13,564 controls during 8-year follow-up. Genetic inhibition of CETP and HMGCR resulted in near-identical associations with LDL cholesterol concentration estimated by the Friedewald equation. Inhibition of HMGCR had relatively consistent associations on lower cholesterol concentrations across all apolipoprotein B-containing lipoproteins. In contrast, the associations of the inhibition of CETP were stronger on lower remnant and very-low-density lipoprotein (VLDL) cholesterol, but there were no associations on cholesterol concentrations in LDL defined by particle size (diameter 18-26 nm) (-0.02 SD LDL defined by particle size; 95% CI: -0.10 to 0.05 for CETP versus -0.24 SD, 95% CI -0.30 to -0.18 for HMGCR). Inhibition of CETP was strongly associated with lower proportion of triglycerides in all high-density lipoprotein (HDL) particles. In observational analyses, a higher triglyceride composition within HDL subclasses was associated with higher risk of CHD, independently of total cholesterol and triglycerides (strongest hazard ratio per 1 SD higher triglyceride composition in very large HDL 1.35; 95% CI: 1.18-1.54). In conclusion, CETP inhibition does not appear to affect size-specific LDL cholesterol but is likely to lower CHD risk by lowering concentrations of other atherogenic, apolipoprotein B-containing lipoproteins (such as remnant and VLDLs). Inhibition of CETP also lowers triglyceride composition in HDL particles, a phenomenon reflecting combined effects of circulating HDL, triglycerides, and apolipoprotein B-containing particles and is associated with a lower CHD risk in observational analyses. Our results reveal that conventional composite lipid assays may mask heterogeneous effects of emerging lipid-altering therapies.

Tofu and fish oil independently modulate serum lipid profiles in rats: Analyses of 10 class lipoprotein profiles and the global hepatic transcriptome.

Soy protein and fish oil are food components that decrease the risk of cardiovascular disease. Previous studies demonstrated that these food components reduced serum cholesterol levels and suppressed hepatic lipogenesis. However, the underlying mechanisms of action of these food components remain unclear. Ten classes of serum lipoprotein profiles showed that dietary tofu, a soybean curd, suppressed cholesterol absorption, while fish oil reduced most of the lipoprotein classes in rats. Tofu and fish oil both halved the level of the lipoprotein class LAC1 (LDL-anti-protease complex), a 15-nm LDL-anti-protease complex, which is speculated to be a cause of atherosclerosis. Moreover, a global transcriptome analysis revealed that tofu inhibited the mRNA expression of genes involved in hepatic lipogenesis, while fish oil stimulated that of genes related to fatty acid degradation. Therefore, tofu and fish oil independently regulate lipid metabolism. The decrease observed in LAC1 may have been due to reduced cholesterol absorption in the tofu diet group and the interference of lipogenesis via the activation of polyunsaturated fatty acid detoxification in the fish oil group.

Lipoprotein Sub-Fractions by Ion-Mobility Analysis and Its Association with Subclinical Coronary Atherosclerosis in High-Risk Individuals.

AIMS: There is limited knowledge about the association of lipoprotein particles and markers of coronary atherosclerosis such as coronary artery calcification (CAC) in relatively young high-risk persons. This study examines the association of lipoprotein subfractions and CAC in high cardiometabolic risk individuals. METHODS: The study presents analysis from baseline data of a randomized trial targeted at high-risk workers. Employees of Baptist Health South Florida with metabolic syndrome or diabetes were recruited. At baseline, all 182 participants had lipoprotein subfraction analysis using the ion mobility technique and participants above 35 years (N=170) had CAC test done. Principal components (PC) were computed for the combination of lipoprotein subclasses. Multiple bootstrapped regression analyses (BSA) were conducted to assess the relationship between lipoprotein subfractions and CAC. RESULTS: The study population (N=170) was largely female (84%) with a mean age of 58 years. Three PCs accounted for 88% variation in the sample. PC2, with main contributions from VLDL particles in the positive direction and large LDL particles in the negative direction was associated with a 22% increase in CAC odds (P value ＜0.05 in 100% of BSA). PC3, with main contributions from HDL lipoprotein particles in the positive direction and small/medium LDL and large IDL particles in the negative direction, was associated with a 9% reduction in CAC odds (P＜0.05 in 88% of BSA). PC1, which had approximately even contributions from HDL, LDL, IDL and VLDL lipoprotein subfractions in the positive direction, was not associated with CAC. CONCLUSION: In a relatively young but high-risk population, a lipoprotein profile predominated by triglyceride-rich lipoproteins was associated with increased risk of CAC, while one predominated by HDL lipoproteins offered modest protection. Lipoprotein sub-fraction analysis may help to further discriminate patients who require more intensive cardiovascular work-up and treatment.

Characterization of 1H NMR Plasma Glycoproteins as a New Strategy To Identify Inflammatory Patterns in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease associated with a high index of morbidity and mortality from cardiovascular diseases. We used 1H NMR to characterize the plasma glycoprotein and lipoprotein profiles of a cohort of patients with RA ( n = 210) versus healthy individuals ( n = 203) to associate them with the RA disease and its severity. Using 1H NMR, we developed a line-shape method to characterize the two peaks associated with glycoproteins (GlycA and GlycB) and its derived variables: areas of GlycB (Area GlycB) and GlycA (Area GlycA), shape factors of these two peaks (H/W = height/width), and the distance between them (Distance GlycB-GlycA). We also used the advanced lipoprotein test Liposcale (CE) to characterize the lipoprotein subclasses. The standard lipid panel and traditional inflammatory markers such as C-reactive protein, the erythrocyte sedimentation rate, fibrinogen, the rheumatoid factor, anticitrullinated peptide antibodies, and the DAS28 index have also been determined. RA patients presented a significant 10.65% increase in the GlycA associated area compared with the control group ( p = 2.21 × 10-10). They also presented significantly higher H/W GlycA and GlycB ratios than the control population (H/W GlycB p = 7.88 × 10-8; H/W GlycA p = 5.61 × 10-8). The prediction model that uses the traditional inflammatory variables and the 1H NMR-derived parameters presented an AUC that was almost 10% higher than the model that only uses the traditional inflammatory variables (from 0.7 to 0.79 AUC). We have demonstrated that GlycA and GlycB variables derived from 1H NMR, along with classic inflammatory parameters, help to improve the classification of individuals with high RA disease activity.

Current Therapies Focused on High-Density Lipoproteins Associated with Cardiovascular Disease.

High-density lipoproteins (HDL) comprise a heterogeneous family of lipoprotein particles divided into subclasses that are determined by density, size and surface charge as well as protein composition. Epidemiological studies have suggested an inverse correlation between High-density lipoprotein-cholesterol (HDL-C) levels and the risk of cardiovascular diseases and atherosclerosis. HDLs promote reverse cholesterol transport (RCT) and have several atheroprotective functions such as anti-inflammation, anti-thrombosis, and anti-oxidation. HDLs are considered to be atheroprotective because they are associated in serum with paraoxonases (PONs) which protect HDL from oxidation. Polyphenol consumption reduces the risk of chronic diseases in humans. Polyphenols increase the binding of HDL to PON1, increasing the catalytic activity of PON1. This review summarizes the evidence currently available regarding pharmacological and alternative treatments aimed at improving the functionality of HDL-C. Information on the effectiveness of the treatments has contributed to the understanding of the molecular mechanisms that regulate plasma levels of HDL-C, thereby promoting the development of more effective treatment of cardiovascular diseases. For that purpose, Scopus and Medline databases were searched to identify the publications investigating the impact of current therapies focused on high-density lipoproteins.

LpA-II:B:C:D:E: a new immunochemically-defined acute phase lipoprotein in humans.

BACKGROUND: Previous studies of lipoproteins in patients with sepsis have been performed on density fractions isolated by conventional ultracentrifugation that are heterogeneous and provide no information about the cargo of apoproteins present in the immunochemically distinct subclasses that populate the density classes. Since apoproteins are now known to have important roles in host defense, we have separated these subclasses according to their apoprotein content and characterized their changes during experimental endotoxemia in human volunteers. METHODS: We have studied apoB- and apoA containing lipoprotein subclasses in twelve healthy male volunteers before and for 8 h after a single dose of endotoxin (ET; 2 µg/kg) to stimulate inflammation. RESULTS: After endotoxin, TG, TC, apoB and the apoB-containing lipoprotein cholesterol-rich subclass LpB and two of the three triglyceride-rich subclasses (TGRLP: Lp:B:C, LpB:C:E+ LpB:E) all declined. In contrast, the third TGRLP, LpA-II:B:C:D:E ("complex particle"), after reaching a nadir at 4 h rose 49% above baseline, p = .006 at 8 h and became the dominant particle in the TGRLP pool. This increment exceeds the threshold of > 25% change required for designation as an acute phase protein. Simultaneous decreases in LpA-I:A-II and LpB:C:E + LpB:E suggest that these subclasses undergo post-translational modification and contribute to the formation of new LpA-II:B:C:D:E particles. CONCLUSIONS: We have identified a new acute phase lipoprotein whose apoprotein constituents have metabolic and immunoregulatory properties applicable to host defense that make it well constituted to engage in the APR.

Lipoproteins comprise at least 10 different classes in rats, each of which contains a unique set of proteins as the primary component.

Although lipoproteins are conventionally separated into a few classes using density gradient centrifugation, there may be a much higher number of physical classes that differ in origin or phase. Comprehensive knowledge of the classes of lipoproteins is rather limited, which hinders both the study of their functions and the identification of the primary causes of related diseases. This study aims to determine the number of classes of lipoproteins that can be practically distinguishable and identify the differences between them. We separated rat serum samples by gel filtration. The elution was continuously monitored for triglyceride (TG), cholesterol, and protein, and fractionated for further SDS-PAGE and immunological detection of apoprotein A-I (ApoA1) and apoprotein B (ApoB). The elution patterns were analyzed using a parsimonious method, i.e., the estimation of the least number of classes. Ten classes were recognized that contained different amounts of TG and cholesterol, as well as a unique protein content. Each of the classes contained much more protein than that observed previously, especially in low-density lipoproteins (LDL) classes. In particular, two major antiproteases formed complexes with specific classes of LDL; because these classes exclusively carry cholesterol and antiproteases, they may lead to the progression of atheroma by supplying materials that enlarge fatty streaks and protecting thrombi from enzymatic digestion. The separated classes may have specific biological functions. The attribution of protein species to certain classes will help understand the functions. A distinction among lipoprotein classes may provide important information in the field of vascular pathology.

Coronary heart disease risk associated with the dyslipidaemia of chronic kidney disease.

OBJECTIVE: This study sought to characterise the main dyslipidaemic phenotypes present in chronic kidney disease (CKD) and their association with coronary heart disease (CHD) risk. METHODS: Analyses included 6612 individuals in the multiethnic study of atherosclerosis free of CHD at baseline. CKD was defined as an estimated glomerular filtration rate (eGFR) of 15 to <60 mL/min/1.73 m2 (stages 3-4). Principal component analyses were used to characterise the main dyslipidaemic phenotypes of CKD accounting for the correlation among different lipoproteins and lipoprotein particles. CHD was defined as incident myocardial infarction, angina followed by revascularisation, resuscitated cardiac arrest or CHD death. RESULTS: CHD developed in 303 individuals (5%) with eGFR ≥60 and in 72 individuals (12%) with CKD (p for difference <0.001). A dyslipidaemic phenotype (principal component 1 (PC1)) consisting of elevations in triglycerides, triglyceride-rich lipoproteins (VLDL particles), small LDL particles and reductions in HDL particles, was more common in those with CKD, compared with those without CKD (p for difference <0.001). This phenotype was also more strongly associated with CHD in those with CKD: adjusted HRs (95% CIs) per SD increase in PC1 1.13 (95% CI 1.00 to 1.27; P=0.05) and 1.51 (95% CI 1.17 to 1.94; P<0.001) in eGFR ≥60 and CKD, respectively (P for interaction=0.05). CONCLUSION: In individuals with mainly stage 3 CKD, a dominant lipid phenotype consisting of triglyceride-rich lipoproteins and other closely correlated lipoproteins is strongly associated with CHD risk. Future studies should investigate whether modification of the components of this phenotype leads to a reduction in the CHD burden in individuals with CKD.

Particle number analysis of lipoprotein subclasses by gel permeation HPLC in patients with cholesteryl ester transfer protein deficiency.

OBJECTIVE: We previously reported that patients with cholesteryl ester transfer protein (CETP) deficiency (CETP-D) have a higher prevalence of atherosclerotic cardiovascular disease, in spite of increased HDL-C levels. However, characterization of HDL in CETP-D has not been well described. Therefore, we examined HDL particle number (PN) rather than HDL-C level. APPROACH AND RESULTS: Nine patients with CETP-D and 9 normolipidemic subjects were enrolled. We performed gel permeation high-performance liquid chromatography (GP-HPLC) analysis, determined the cholesterol and triglyceride composition of all lipoprotein subclasses, and calculated the PN of each subclass, which consisted of 3 VLDL (large, medium, and small), 4 LDL (large, medium, small, and very small), and 5 HDL (very large, large, medium, small, and very small) subclasses. The PNs of large and medium LDL were significantly lower in CETP-D than that in healthy subjects (0.66- and 0.63-fold decrease, respectively; p<0.001), whereas the PN of very small LDL, which is known to be atherogenic, was significantly higher (1.36-fold increase, p = 0.016). The PNs of very large and large HDL in CETP-D were markedly higher than that in healthy subjects (19.9- and 4.5-fold increase, respectively; p<0.001), whereas the PNs of small and very small HDL, which have more potent anti-atherogenic functions, were significantly lower (0.76- and 0.61-fold decrease, respectively; p<0.001). CONCLUSION: We have assessed the PNs of detailed subclasses of patients with CETP-D for the first time. The PN of larger HDL was markedly increased, that of smaller HDL was decreased, and that of very small LDL was increased, suggesting that CETP-D has pro-atherogenic lipoprotein properties.

Metabolomics reveals distinct, antibody-independent, molecular signatures of MS, AQP4-antibody and MOG-antibody disease.

The overlapping clinical features of relapsing remitting multiple sclerosis (RRMS), aquaporin-4 (AQP4)-antibody (Ab) neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG)-Ab disease mean that detection of disease specific serum antibodies is the gold standard in diagnostics. However, antibody levels are not prognostic and may become undetectable after treatment or during remission. Therefore, there is still a need to discover antibody-independent biomarkers. We sought to discover whether plasma metabolic profiling could provide biomarkers of these three diseases and explore if the metabolic differences are independent of antibody titre. Plasma samples from 108 patients (34 RRMS, 54 AQP4-Ab NMOSD, and 20 MOG-Ab disease) were analysed by nuclear magnetic resonance spectroscopy followed by lipoprotein profiling. Orthogonal partial-least squares discriminatory analysis (OPLS-DA) was used to identify significant differences in the plasma metabolite concentrations and produce models (mathematical algorithms) capable of identifying these diseases. In all instances, the models were highly discriminatory, with a distinct metabolite pattern identified for each disease. In addition, OPLS-DA identified AQP4-Ab NMOSD patient samples with low/undetectable antibody levels with an accuracy of 92%. The AQP4-Ab NMOSD metabolic profile was characterised by decreased levels of scyllo-inositol and small high density lipoprotein particles along with an increase in large low density lipoprotein particles relative to both RRMS and MOG-Ab disease. RRMS plasma exhibited increased histidine and glucose, along with decreased lactate, alanine, and large high density lipoproteins while MOG-Ab disease plasma was defined by increases in formate and leucine coupled with decreased myo-inositol. Despite overlap in clinical measures in these three diseases, the distinct plasma metabolic patterns support their distinct serological profiles and confirm that these conditions are indeed different at a molecular level. The metabolites identified provide a molecular signature of each condition which is independent of antibody titre and EDSS, with potential use for disease monitoring and diagnosis.

Differences in expression of serum protein in patients with psoriasis vulgaris and blood heat syndrome and healthy volunteers.

To explore the mechanism of psoriasis vulgaris (PV), serum protein expression profiles between PV patients with blood-heat syndrome and healthy volunteers were detected by isobaric tags for relative and absolute quantitation (iTRAQ). First, sera from 15 PV patients with blood-heat syndrome and 10 healthy volunteers were collected; then, serum proteins were separated and hydrolyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and a specific iTRAQ marker enzyme respectively after further purification and protein abundance treatment. Compared with the control group, differentially expressed proteins in PV patients with blood-heat syndrome were identified and analyzed by tandem mass spectrometry. A total of 787 proteins were identified and 718 proteins had a functional annotation with gene ontology (GO) by iTRAQ in the current study. Significant differences (P <0.05) and great differences (P <0.01) were found in 681 proteins and 536 proteins respectively between the patient group and healthy group. ). Different protein expression profiles in serum existed between PV patients with blood-heat syndrome and healthy volunteers; the differences largely involved immune-related proteins and lipoproteins. The proteins specific for PV with blood-heat syndrome deserves further investigation.

Human Lipoproteins at Model Cell Membranes: Effect of Lipoprotein Class on Lipid Exchange.

High and low density lipoproteins (HDL and LDL) are thought to play vital roles in the onset and development of atherosclerosis; the biggest killer in the western world. Key issues of initial lipoprotein (LP) interactions at cellular membranes need to be addressed including LP deposition and lipid exchange. Here we present a protocol for monitoring the in situ kinetics of lipoprotein deposition and lipid exchange/removal at model cellular membranes using the non-invasive, surface sensitive methods of neutron reflection and quartz crystal microbalance with dissipation. For neutron reflection, lipid exchange and lipid removal can be distinguished thanks to the combined use of hydrogenated and tail-deuterated lipids. Both HDL and LDL remove lipids from the bilayer and deposit hydrogenated material into the lipid bilayer, however, the extent of removal and exchange depends on LP type. These results support the notion of HDL acting as the 'good' cholesterol, removing lipid material from lipid-loaded cells, whereas LDL acts as the 'bad' cholesterol, depositing lipid material into the vascular wall.