Lipoprint adequately estimates LDL size distribution, but not absolute size, versus polyacrylamide gradient gel electrophoresis

Effects of turmeric extract supplementation on the lipid and lipoprotein subfraction profile in hemodialysis patients: A randomised, double-blind, crossover and controlled trial

Dyslipidemia is common in patients with chronic kidney disease. Curcumin, a bioactive polyphenol from Curcuma longa, can improve lipid profile. This study aims to analyze the effects of Curcuma Longa extract supplementation on lipid profile and lipoprotein subfractions in hemodialysis (HD) patients. This is a longitudinal, double-blind, washout-period randomized clinical trial. The patients were randomized into two groups: the curcumin group (n = 10) (orange and carrot juice with 2.5 g of Curcuma Longa extract) and the control group (n = 11) (juice without curcumin) 3x/w during HD sessions for 3 months. After the washout period, patients continued the supplementation as a crossover for the same period. The lipid profile was measured using enzymatic assays. The high-density lipoprotein and low-density lipoprotein subfractions analyses were performed using LipoprintTM. In the curcumin group, the triglyceride values tended to decrease with a different triglyceride variation between the pre and post-intervention for the control and curcumin groups of 38.5 (19.8) mg/dL (p = 0.06). There was no statistical difference in the others parameters. In conclusion, Curcuma longa extract may be a good nutritional strategy to reduce triglyceride plasma levels in hemodialysis patients, but it seems ineffective for the other parameter.

The Oxidized Lipoproteins In Vivo: Its Diversity and Behavior in the Human Circulation

A high concentration of low-density lipoproteins (LDLs) in circulation has been well-known as a major risk factor for cardiovascular diseases. The presence of oxidized LDLs (oxLDLs) in atherosclerotic lesions and circulation was demonstrated using anti-oxLDL monoclonal antibodies. The so-called “oxLDL hypothesis”, as a mechanism for atherosclerosis development, has been attracting attention for decades. However, the oxLDL has been considered a hypothetical particle since the oxLDL present in vivo has not been fully characterized. Several chemically modified LDLs have been proposed to mimic oxLDLs. Some of the subfractions of LDL, especially Lp(a) and electronegative LDL, have been characterized as oxLDL candidates as oxidized phospholipids that stimulate vascular cells. Oxidized high-density lipoprotein (oxHDL) and oxLDL were discovered immunologically in vivo. Recently, an oxLDL-oxHDL complex was found in human plasma, suggesting the involvement of HDLs in the oxidative modification of lipoproteins in vivo. In this review, we summarize our understanding of oxidized lipoproteins and propose a novel standpoint to understand the oxidized lipoproteins present in vivo.

Changes in lipoproteins associated with lipid-lowering and antiplatelet strategies in patients with acute myocardial infarction

Background

Despite lipid-lowering and antiplatelet therapy, the pattern of residual lipoproteins seems relevant to long-term cardiovascular outcomes. This study aims to evaluate the effects of combined therapies, commonly used in subjects with acute myocardial infarction, in the quality of low-density lipoprotein (LDL) particles.

Methods

Prospective, open-label trial, included patients with acute myocardial infarction. Patients were randomized to antiplatelet treatment (ticagrelor or clopidogrel) and subsequently to lipid-lowering therapy (rosuvastatin or simvastatin/ezetimibe) and were followed up for six months. Nonlinear optical properties of LDL samples were examined by Gaussian laser beam (Z-scan) to verify the oxidative state of these lipoproteins, small angle X-ray scattering (SAXS) to analyze structural changes on these particles, dynamic light scattering (DLS) to estimate the particle size distribution, ultra violet (UV)-visible spectroscopy to evaluate the absorbance at wavelength 484 nm (typical from carotenoids), and polyacrylamide gel electrophoresis (Lipoprint) to analyze the LDL subfractions.

Results

Simvastatin/ezetimibe with either clopidogrel or ticagrelor was associated with less oxidized LDL, and simvastatin/ezetimibe with ticagrelor to lower cholesterol content in the atherogenic subfractions of LDL, while rosuvastatin with ticagrelor was the only combination associated with increase in LDL size.

Conclusions

The quality of LDL particles was influenced by the antiplatelet/lipid-lowering strategy, with ticagrelor being associated with the best performance with both lipid-lowering therapies. Trial registration: NCT02428374.

Anorexia Nervosa Is Associated with a Shift to Pro-Atherogenic Low-Density Lipoprotein Subclasses

Anorexia nervosa (AN) is a severe eating disorder affecting primarily female adolescents and younger adults. The energy deprivation associated with AN has been shown to alter lipoprotein metabolism, which may affect cardiovascular risk. However, the mechanisms leading to alterations in the composition, structure, and function of lipoproteins in AN patients are not well-understood yet. Here, we investigated the lipid abnormalities associated with AN, particularly changes in the distribution, composition, metabolism, and function of lipoprotein subclasses. In this exploratory study, we analyzed serum samples of 18 women diagnosed with AN (BMI < 17.5 kg/m2) and 24 normal-weight women (BMI from 18.5−24.9 kg/m2). Using the Quantimetrix Lipoprint® system, we determined low-density lipoprotein (LDL) subclass distribution, including quantitative measurements of very low-density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and high-density lipoprotein (HDL) subclass distribution. We quantified the most abundant apolipoproteins of HDL and assessed lecithin-cholesterol acyltransferase (LCAT) and cholesteryl-ester transfer protein (CETP) activities. In addition, anti-oxidative capacity of apoB-depleted serum and functional metrics of HDL, including cholesterol efflux capacity and paraoxonase activity were assessed. The atherogenic lipoprotein subclasses VLDL and small LDL particles were increased in AN. Levels of VLDL correlated significantly with CETP activity (rs = 0.432, p = 0.005). AN was accompanied by changes in the content of HDL-associated apolipoproteins involved in triglyceride catabolism, such as apolipoprotein C-II (+24%) and apoA-II (−27%), whereas HDL-associated cholesterol, phospholipids, and triglycerides were not altered. Moreover, AN did not affect HDL subclass distribution, cholesterol efflux capacity, and paraoxonase activity. We observed a shift to more atherogenic lipoprotein subclasses in AN patients, whereas HDL functionality and subclass distribution were not altered. This finding underpins potential detrimental effects of AN on lipid metabolism and the cardiovascular system by increasing atherosclerotic risk factors.

Association between small dense low-density lipoprotein cholesterol and neuroimaging markers of cerebral small vessel disease in middle-aged and elderly Chinese populations

BACKGROUND

Cerebral small vascular disease (CSVD) is one of the leading causes of death in the aged population and is closely related to abnormalities in low-density lipoprotein cholesterol (LDL-C). Our study aims to clarify the relationship between small and dense low-density lipoprotein cholesterol (sdLDL-C) (a subcomponent of LDL-C) and neuroimaging markers of CSVD.

METHODS

In total, 1211 Chinese adults aged ≥45 years with cranial magnetic resonance imaging (MRI) were recruited in this retrospective study from January 2018 to May 2021. Serum lipids and other baseline characteristics were investigated in relation to the occurrence of CSVD. A logistic regression model was performed to analyze the relationships between LDL subtypes and CSVD risk, and the Pearson correlation coefficient was used to analyze the correlation between clinical characteristics and CSVD risk. ROC curves and AUCs were created and depicted to predict the best cutoff value of LDL-C subtypes for CSVD risk. Based on these data, we performed comprehensive analyses to investigate the risk factors for CSVD.

RESULTS

Ultimately, 623 eligible patients were included in the present study. Of the 623 eligible patients, 487 were included in the CSVD group, and 136 were included in the group without CSVD (control group). We adjusted for confounders in the multivariate logistic regression model, and LDL-C3 was still higher in the CSVD patients than in the group of those without CSVD (OR (95% CI), 1.22(1.08-1.38), P < 0.05). Pearson correlation showed that there was a positive correlation between the levels of LDL-C3, LDL-C4, LDL-C5, glucose, age, hypertension, previous ischemic stroke and CSVD risk (r > 0.15, P < 0.01). Moreover, the best cutoff value of LDL-C3 to predict CSVD was 9.5 mg/dL with 68.4% sensitivity and 72.8% specificity, and the best cutoff value of LDL-C4 to predict CSVD was 5.5 mg/dL with 50.5% sensitivity and 90.4% specificity.

CONCLUSION

The results indicate that LDL-C3 is an independent risk factor for CSVD. A new prediction model based on LDL-C3 and LDL-C4 can help clinicians identify high-risk CSVD, even in people with normal LDL-C levels. The levels of sdLDL-C should be considered in the assessment and management of CSVD.

Main differences between two highly effective lipid-lowering therapies in subclasses of lipoproteins in patients with acute myocardial infarction

Background

Large observational studies have shown that small, dense LDL subfractions are related to atherosclerotic cardiovascular disease. This study assessed the effects of two highly effective lipid-lowering therapies in the atherogenic subclasses of lipoproteins in subjects with ST-segment elevation myocardial infarction (STEMI).

Methods

Patients of both sexes admitted with their first myocardial infarction and submitted to pharmacoinvasive strategy (N = 101) were included and randomized using a central computerized system to receive a daily dose of simvastatin 40 mg plus ezetimibe 10 mg or rosuvastatin 20 mg for 30 days. Intermediate-density lipoprotein (IDL) and low-density lipoprotein (LDL) subfractions were analysed by polyacrylamide gel electrophoresis (Lipoprint System) on the first (D1) and 30th days (D30) of lipid-lowering therapy. Changes in LDL and IDL subfractions between D1 and D30 were compared between the lipid-lowering therapies (Mann-Whitney U test).

Results

The classic lipid profile was similar in both therapy arms at D1 and D30. At D30, the achievement of lipid goals was comparable between lipid-lowering therapies. Cholesterol content in atherogenic subclasses of LDL (p = 0.043) and IDL (p = 0.047) decreased more efficiently with simvastatin plus ezetimibe than with rosuvastatin.

Conclusions

Lipid-lowering therapy with simvastatin plus ezetimibe was associated with a better pattern of lipoprotein subfractions than rosuvastatin monotherapy. This finding was noted despite similar effects in the classic lipid profile and may contribute to residual cardiovascular risk.

Trial registration

ClinicalTrials.gov, NCT02428374, registered on 28/09/2014.

Estimation of the LDL subclasses in ischemic stroke as a risk factor in a Chinese population

Background

Acute ischemic stroke (AIS) is one of the leading causes of mortality and long-term disability worldwide. Our study aims to clarify the role of low-density lipoproteins (LDL) subclasses in the occurrence of AIS and develop a risk xprediction model based on these characteristics to identify high-risk people.

Methods

Five hundred and sixty-six patients with AIS and 197 non-AIS controls were included in this study. Serum lipids and other baseline characteristics including fasting blood glucose (GLU), serum creatinine (Scr), and blood pressure were investigated in relation to occurrence of AIS. The LDL subfractions were classified and measured with the Lipoprint System by a polyacrylamide gel electrophoresis technique.

Results

Levels of LDL-3, LDL-4 and LDL-5 subclasses were significantly higher in the AIS group compared to the non-AIS group and lower level of LDL-1 was prevalent in the AIS patients. Consistently, Spearman correlation coefficient demonstrated that sd-demonevels, especially LDL-3 and LDL-4 levels, were significantly positively correlated with AIS. Furthermore, there is a significant positive correlation between small dense LDL (sd-LDL, that is LDL-3 to 7) levels and serum lipids including total cholesterol (TC), Low density lipoprotein cholesterol (LDL-C), and Triglyceride (TG). Increased LDL-3 and LDL-4 as well as decreased LDL-1 and LDL-2 were correlated to the occurrence of AIS, even in the people with normal LDL-C levels. A new prediction model including 12 variables can accurately predict the AIS risk in Chinese patients (AUC = 0.82 ± 0.04).

Conclusions

Levels of LDL subclasses should be considered in addition to serum LDL-C in assessment and management of AIS. A new prediction model based on clinical variables including LDL subtractions can help clinicians identify high of AIS, even in the people with norm.

Changes in High-Density Lipoproteins Related to Outcomes in Patients with Acute Stroke

Modifications in high-density lipoprotein (HDL) particle sizes and HDL-binding proteins have been reported in stroke patients. We evaluated whether the lipoprotein profile, HDL composition and functionality were altered in stroke patients according to their clinical outcome using the modified Rankin Score at 3 months. Plasma samples were obtained from stroke patients treated with intravenous thrombolysis. Levels of cardiovascular and inflammatory markers in plasma were measured using the Human CVD Panel 1 (Milliplex^® MAP). Lipoprotein subfractions from plasma were quantified by non-denaturing acrylamide gel electrophoresis, using the Lipoprint^®-System (Quantimetrix^®), and HDLs were isolated by ultracentrifugation. Relative amounts of paraoxonase-1 (PON1) and alpha-1 anti-trypsin (AAT) in the isolated HDLs were determined by Western blot. HDL anti-inflammatory function was evaluated in human blood-brain barrier endothelial cells stimulated with 100 ng/mL TNFα, and HDL antioxidant function was evaluated via their capacity to limit copper-induced low-density lipoprotein oxidation. Stroke patients with unfavorable outcomes had a lower proportion of small-sized HDLs and increased plasma levels of E-selectin (SELE) and the intercellular adhesion molecule 1 (ICAM1). HDLs from patients with unfavorable outcomes had lower levels of PON1 and displayed a blunted capacity to reduce the expression of SELE, interleukin 8 (IL8) and the monocyte chemoattractant protein-1 (MCP1) mRNA induced by TNFα in endothelial cells. These HDLs also had a reduced antioxidant capacity relative to HDLs from healthy donors. In conclusion, an increased ratio of large/small HDLs with impaired anti-inflammatory and antioxidant capacities was associated with unfavorable outcomes in stroke patients. Alteration of HDL functionality was mainly associated with a low amount of PON1 and high amount of AAT.

Advanced lipoprotein testing for cardiovascular diseases risk assessment: a review of the novel approaches in lipoprotein profiling

With the increasing prevalence of cardiovascular diseases (CVD) worldwide, finding reliable and clinically relevant biomarkers to predict acute cardiovascular events has been a major aim of the scientific and medical community. Improvements of the understanding of the pathophysiological pathways of the disease highlighted the major role of lipoprotein particles, and these past decades have seen the emergence of a number of new methodologies to separate, measure and quantitate lipoproteins. Those methods, also known as advanced lipoprotein testing methods (ALT), have gained acceptance in the field of CVD risk assessment and have proven their clinical relevance. In the context of worldwide standardization and harmonization of biological assays, efforts have been initiated toward standardization of ALT methods. However, the complexity of lipoprotein particles and the multiple approaches and methodologies reported to quantify them have rendered these initiatives a critical issue. In this context and to better understand these challenges, this review presents a summary of the major methods available for ALT with the aim to point out the major differences in terms of procedures and quantities actually measured and to discuss the resulting comparability issues.

LDL particle number and size and cardiovascular risk: anything new under the sun?

PURPOSE OF REVIEW

We provide here an up-to-date perspective on the potential use of LDL particle number and size as complementary risk factors to predict and manage cardiovascular disease (CVD) risk in the clinical realm.

RECENT FINDINGS

Studies show that a significant proportion of the population has discordant LDL particle number and cholesterol indices [non-HDL cholesterol (HDL-C)]. Data also show that risk prediction may be improved when using information on LDL particle number in patients with discordant particle number and cholesterol data. Yet, most of the current CVD guidelines conclude that LDL particle number is not superior to cholesterol indices, including non-HDL-C concentrations, in predicting CVD risk. LDL particle size, on the other hand, has not been independently associated with CVD risk after adjustment for other risk factors such as LDL cholesterol, triglycerides, and HDL-C and that routine use of information pertaining to particle size to determine and manage patients' risk is not yet justified.

SUMMARY

Additional studies are required to settle the debate on which of cholesterol indices and LDL particle number is the best predictor of CVD risk, and if such measures should be integrated in clinical practice.

Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial

BACKGROUND

Alternate day fasting (ADF; ad libitum "feed day", alternated with 25% energy intake "fast day"), is effective for weight loss and cardio-protection in obese individuals. Whether these effects occur in normal weight and overweight individuals remains unknown. This study examined the effect of ADF on body weight and coronary heart disease risk in non-obese subjects.

METHODS

Thirty-two subjects (BMI 20-29.9 kg/m2) were randomized to either an ADF group or a control group for 12 weeks.

RESULTS

Body weight decreased (P < 0.001) by 5.2 ± 0.9 kg (6.5 ± 1.0%) in the ADF group, relative to the control group, by week 12. Fat mass was reduced (P < 0.001) by 3.6 ± 0.7 kg, and fat free mass did not change, versus controls. Triacylglycerol concentrations decreased (20 ± 8%, P < 0.05) and LDL particle size increased (4 ± 1 Å, P < 0.01) in the ADF group relative to controls. CRP decreased (13 ± 17%, P < 0.05) in the ADF group relative to controls at week 12. Plasma adiponectin increased (6 ± 10%, P < 0.01) while leptin decreased (40 ± 7%, P < 0.05) in the ADF group versus controls by the end of the study. LDL cholesterol, HDL cholesterol, homocysteine and resistin concentrations remained unchanged after 12 weeks of treatment.

CONCLUSION

These findings suggest that ADF is effective for weight loss and cardio-protection in normal weight and overweight adults, though further research implementing larger sample sizes is required before solid conclusion can be reached.

LOW-DENSITY LIPOPROTEIN SUBFRACTIONS AND VARYING DEGREE OF CORONARY STENOSIS

Aim.To investigate whether low and intermediate density lipoprotein (LDL, IDL) subfractions are associated with a degree of angiographically verified coronary atherosclerosis, as well as with other biochemical risk factors of coronary heart disease (CHD), and hypertriglyceridemia (HTG) in particular.

Material and methods.The study included 129 patients (76 men and 53 women), aged 33–75 years, who were referred for coronary angiography. All participants were divided into three groups by the degree of coronary artery (CA) stenosis: 0–20%, 21–70%, and >70%. LDL and IDL subfractions were measured with the Lipoprint LDL System (electrophoresis in 3% polyacrylamide gel).

Results.All groups were similar by the levels of lipid and apoprotein parameters. The levels of high-sensitive C-reactive protein and glucose, as well as HOMA-IR index, were higher in Group 3 patients. In most cases of severe CA stenosis, small dense LDL particles were detected. In HTG patients, higher levels of small dense LDL3 particles were registered only together with the CA stenosis of at least 21–70%.

Conclusion.The findings on lipoprotein subfractions, obtained with the Lipoprint LDL System, have demonstrated that in patients with verified coronary atherosclerosis, there is a link between the levels of more atherogenic small dense LDL3 particles, the degree of CA stenosis, and blood TG levels. The combination of HTG and high LDL3 levels could be considered an additional marker of severe CA atherosclerosis. 

Tracking fatty acid kinetics in distinct lipoprotein fractions in vivo: a novel high-throughput approach for studying dyslipidemia in rodent models

Isotopic tracers have been used to examine lipid trafficking for many years, and data from those studies have typically yielded novel insight regarding the pathophysiology of dyslipidemia. Previous experimental designs were suitable for studies in humans because relatively large volumes of plasma could be regularly sampled. We have expanded on the earlier logic by applying high-throughput analytical methods that require reduced sample volumes. Specifically, we have examined the possibility of coupling gel-based separations of lipoproteins (e.g., lipoprint) with LC-MS/MS analyses of complex lipid mixtures as a way to routinely measure the labeling profiles of distinct lipids in discrete lipoprotein subfractions. We demonstrate the ability to measure the incorporation of [U-(13)C]oleate into triglycerides (TG), PLs (PL), and cholesterol esters (CE) in VLDL, LDL, and HDL particles in mice. Although rodent models of dyslipidemia are inherently different from humans because of alterations in enzyme activities and underlying metabolism, rodent models can be used to screen novel compounds for efficacy in altering a given biochemical pathway and therein enable studies of target engagement in vivo. We expect that it is possible to translate our approach for application in other systems, including studies in humans.