Lipoprotein Function Research Articles

Fully automated immunoassay for cholesterol uptake capacity to assess high-density lipoprotein function and cardiovascular disease risk

High-density lipoprotein (HDL) cholesterol efflux capacity (CEC), which is a conventional metric of HDL function, has been associated with coronary heart disease risk. However, the CEC assay requires cultured cells and takes several days to perform. We previously established a cell-free assay to evaluate cholesterol uptake capacity (CUC) as a novel measure of HDL functionality and demonstrated its utility in coronary risk stratification. To apply this concept clinically, we developed a rapid and sensitive assay system based on a chemiluminescent magnetic particle immunoassay. The system is fully automated, providing high reproducibility. Measurement of CUC in serum is completed within 20 min per sample without HDL isolation, a notably higher throughput than that of the conventional CEC assay. CUC decreased with myeloperoxidase-mediated oxidation of HDL or in the presence of N-ethylmaleimide, an inhibitor of lecithin: cholesterol acyltransferase (LCAT), whereas CUC was enhanced by the addition of recombinant LCAT. Furthermore, CUC correlated with CEC even after being normalized by ApoA1 concentration and was significantly associated with the requirement for revascularization due to the recurrence of coronary lesions. Therefore, our new assay system shows potential for the accurate measurement of CUC in serum and permits assessing cardiovascular health.

Glycation of LDL: AGEs, impact on lipoprotein function, and involvement in atherosclerosis.

Atherosclerosis is a complex disease, and there are many factors that influence its development and the course of the disease. A deep understanding of the pathological mechanisms underlying atherogenesis is needed to develop optimal therapeutic strategies and treatments. In this review, we have focused on low density lipoproteins. According to multiple studies, their atherogenic properties are associated with multiple modifications of lipid particles. One of these modifications is Glycation. We considered aspects related to the formation of modified particles, as well as the influence of modification on their functioning. We paid special attention to atherogenicity and the role of glycated low-density lipoprotein (LDL) in atherosclerosis.

Dipeptidyl Peptidase-4 Inhibitor Sitagliptin Phosphate Accelerates Cellular Cholesterol Efflux in THP-1 Cells.

Cholesterol efflux is a major atheroprotective function of high-density lipoproteins (HDLs) which removes cholesterol from the foam cells of lipid-rich plaques in Type 2 diabetes. The dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin phosphate increases plasma glucagon-like peptide-1 (GLP-1) concentrations and is used to treat Type 2 diabetes. GLP-1 plays an important role in regulating insulin secretion and expression via the GLP-1 receptor (GLP-1R), which is expressed in pancreatic islets as well as freshly isolated human monocytes and THP-1 cells. Here, we identified a direct role of GLP-1 and DPP-4 inhibition in HDL function. Cholesterol efflux was measured in cultivated phorbol 12-myristate 13-acetate-treated THP-1 cells radiolabeled with 3H-cholesterol and stimulated with liver X receptor/retinoid X receptor agonists. Contrary to vildagliptin, sitagliptin phosphate together with GLP-1 significantly (p < 0.01) elevated apolipoprotein (apo)A1-mediated cholesterol efflux in a dose-dependent manner. The sitagliptin-induced increase in cholesterol efflux did not occur in the absence of GLP-1. In contrast, adenosine triphosphate-binding cassette transporter A1 (ABCA1) mRNA and protein expressions in the whole cell fraction were not changed by sitagliptin in the presence of GLP-1, although sitagliptin treatment significantly increased ABCA1 protein expression in the membrane fraction. Furthermore, the sitagliptin-induced, elevated efflux in the presence of GLP-1 was significantly decreased by a GLP-1R antagonist, an effect that was not observed with a protein kinase A inhibitor. To our knowledge, the present study reports for the first time that sitagliptin elevates cholesterol efflux in cultivated macrophages and may exert anti-atherosclerotic actions that are independent of improvements in glucose metabolism. Our results suggest that sitagliptin enhances HDL function by inducing a de novo HDL synthesis via cholesterol efflux.

Associations between Endothelial Lipase, High-Density Lipoprotein, and Endothelial Function Differ in Healthy Volunteers and Metabolic Syndrome Patients.

Metabolic syndrome (MS) is characterized by endothelial- and high-density lipoprotein (HDL) dysfunction and increased endothelial lipase (EL) serum levels. We examined the associations between EL serum levels, HDL (serum levels, lipid content, and function), and endothelial function in healthy volunteers (HV) and MS patients. Flow-mediated dilation (FMD), nitroglycerin-mediated dilation (NMD), serum levels of HDL subclasses (measured by nuclear magnetic resonance (NMR) spectroscopy), and EL serum levels differed significantly between HV and MS patients. The serum levels of triglycerides in large HDL particles were significantly positively correlated with FMD and NMD in HV, but not in MS patients. Cholesterol (C) and phospholipid (PL) contents of large HDL particles, calculated as HDL1-C/HDL1-apoA-I and HDL1-PL/HDL1-apoA-I, respectively, were significantly negatively correlated with FMD in HV, but not in MS patients. Cholesterol efflux capacity and arylesterase activity of HDL, as well as EL, were correlated with neither FMD nor NMD. EL was significantly negatively correlated with HDL-PL/HDL-apoA-I in HV, but not in MS patients, and with serum levels of small dense HDL containing apolipoprotein A-II in MS patients, but not in HV. We conclude that MS modulates the association between HDL and endothelial function, as well as between EL and HDL. HDL cholesterol efflux capacity and arylesterase activity, as well as EL serum levels, are not associated with endothelial function in HV or MS patients.

Very low HDL levels: clinical assessment and management.

In individuals with very low high-density lipoprotein (HDL-C) cholesterol, such as Tangier disease, LCAT deficiency, and familial hypoalphalipoproteinemia, there is an increased risk of premature atherosclerosis. However, analyzes based on comparisons of populations with small variations in HDL-C mediated by polygenic alterations do not confirm these findings, suggesting that there is an indirect association or heterogeneity in the pathophysiological mechanisms related to the reduction of HDL-C. Trials that evaluated some of the HDL functions demonstrate a more robust degree of association between the HDL system and atherosclerotic risk, but as they were not designed to modify lipoprotein functionality, there is insufficient data to establish a causal relationship. We currently have randomized clinical trials of therapies that increase HDL-C concentration by various mechanisms, and this HDL-C elevation has not independently demonstrated a reduction in the risk of cardiovascular events. Therefore, this evidence shows that (a) measuring HDL-C as a way of estimating HDL-related atheroprotective system function is insufficient and (b) we still do not know how to increase cardiovascular protection with therapies aimed at modifying HDL metabolism. This leads us to a greater effort to understand the mechanisms of molecular action and cellular interaction of HDL, completely abandoning the traditional view focused on the plasma concentration of HDL-C. In this review, we will detail this new understanding and the new horizon for using the HDL system to mitigate residual atherosclerotic risk.

HDL cholesterol efflux capacity and phospholipid content are associated with the severity of acute ischemic stroke and predict its outcome

Background/AimsImpaired high-density lipoprotein (HDL) function and composition are more strongly related to cardiovascular morbidity than HDL concentration. However, it is unclear whether HDL function and composition predict ischemic stroke severity and outcome. We aimed to evaluate these associations. MethodsWe prospectively studied 199 consecutive patients who were admitted with acute ischemic stroke. The severity of stroke was evaluated at admission with the National Institutes of Health Stroke Scale (NIHSS). Severe stroke was defined as NIHSS ≥ 5. The outcome was assessed with dependency at discharge (modified Rankin scale 2–5) and in-hospital mortality. Cholesterol efflux capacity (CEC), phospholipid levels, lecithin:cholesterol acyl transferase (LCAT)-phospholipase activity, paraoxonase-1 (PON1)-arylesterase activity and serum amyloid A1 (SAA1) content of HDL were measured. ResultsCEC, phospholipid levels and LCAT-phospholipase activity of HDL were lower and SAA1 content of HDL was higher in patients with severe stroke. Patients who were dependent at discharge had lower CEC, PON1-arylesterase activity, phospholipid content and LCAT-phospholipase activity of HDL and higher HDL-SAA1 content. Independent predictors of dependency at discharge were the NIHSS at admission (RR 2.60, 95% CI 1.39–4.87), lipid-lowering treatment (RR 0.17, 95% CI 0.01–0.75), HDL-CEC (RR 0.21, 95% CI 0.05–0.87) and HDL-associated PON1-arylesterase activity (RR 0.95, 95% CI 0.91–0.99). In patients who died during hospitalization, phospholipids, LCAT-phospholipase and PON1-arylesterase activities of HDL were lower. ConclusionsChanges in CEC and composition of HDL appear to be associated with the severity and outcome of acute ischemic stroke and could represent biomarkers that may inform risk stratification and management strategies in these patients.

Blood lipids after COVID-19 infection

Blood lipids after COVID-19 infection

Probucol will become a new model for treating cerebral infarction with a high risk of hemorrhage: A narrative review.

Lipid-lowering agents are relevant in stroke prevention. Probucol (PU) is an antioxidative and lipid-lowering drug that has been used to treat atherosclerotic cardiovascular diseases and xanthomas. The drug penetrates the core of low-density lipoprotein cholesterol (LDL-C) particles, enhancing the activity of plasma cholesterol l ester transfer protein (CETP) and strengthening the liver scavenger receptor type I, resulting in reducing LDL-C; by increasing the activity of paraoxonase 1, upregulating the antioxidant function of high-density lipoprotein (HDL), and it decreases the serum HDL-cholesterol (HDL-C) level. This drug has been retired from the Western markets for lowering HDL-C levels and Q-interval prolongation. The latter side effect has been rarely reported and may be transient. Recent clinical evidence supports the effectiveness of PU in preventing cardiovascular events and in reducing mortality, irrespective of the reduction of HDL-C. Based on basic research and clinical studies, it appears that PU might be a valuable alternative when statins are ineffective or contraindicated, in patients at high risk of recurrence of cerebral ischemia and hemorrhage.

High density lipoprotein heterogeneity & function among Indians with coronary artery disease.

Impaired high density lipoprotein (HDL) functionality has been shown to be associated with cardiovascular disease risk. The study was aimed to identify the alterations in HDL function [antioxidative activity (AOA)] and subfraction distribution between acute coronary syndrome (ACS) and stable coronary artery disease (SCAD) individuals and analysing the accuracy of HDL parameters to discriminate between the groups. HDL subfraction distribution analysis was performed in 200 coronary artery disease patients (ACS and SCAD) and 60 control individuals using dextran sulphate, heparin and manganese chloride precipitation method. In terms of HDL function, AOA was evaluated by dihydrorhodamine-based fluorescent cell-free assay and paraoxonase (PON1) enzyme paraoxonase and arylesterase activity. We found that higher AOA [odds ratio (95% confidence interval {CI})]: 0.09 (0.02-0.44), P<0.01 for SCAD; 0.008 (0.001-0.07), P<0.001 for ACS and higher PON1 activity [0.22 (0.8-0.59), P<0.01 for SCAD; 0.16 (0.06-0.4), P<0.001 for ACS] were associated with a lower odds of developing coronary artery disease (CAD). AOA of apoB-depleted serum was significantly correlated with HDL2-C/HDL3-C (HDL-cholesterol) ratio in controls (r=-0.31, P=0.01) and ACS (r=-0.18, P=0.04). It was observed that AOA and HDL subfraction distribution together could discriminate between the two groups of CAD with an accuracy of 72.8 per cent (P=0.004). Impaired AOA and altered subfraction distribution of HDL may be responsible for its diminished anti-athero protective activity and can discriminate between the two groups of CAD individuals.

Are There Any Pleiotropic Benefits of Vitamin D in Patients With Diabetic Kidney Disease? A Systematic Review of Randomized Controlled Trials.

Type 2 diabetes (T2D) and kidney disease are risk factors for vitamin D deficiency. Native forms of vitamin D have a lower risk of hypercalcemia than calcitriol, the active hormone. The enzyme responsible for activating native vitamin D is now known to be expressed throughout the body; therefore, native vitamin D may have clinically relevant effects in many body systems. The objective of this systematic review was to examine the effect of native vitamin D supplementation on clinical outcomes and surrogate laboratory measures in patients with T2D and diabetic kidney disease (DKD). Systematic review. Randomized controlled trials (RCTs) conducted in any country. Adults with T2D and DKD receiving supplementation with any form of native vitamin D (eg, ergocalciferol, cholecalciferol, calcifediol). Clinical outcomes and surrogate clinical and laboratory measures reported in each of the trials were included in this review. The following databases were searched from inception to January 31, 2023: Embase, MEDLINE, Cochrane CENTRAL, Web of Science, ProQuest Dissertations and Theses, and medRxiv. Only RCTs examining supplementation with a native vitamin D form with a control or placebo comparison group were included. We excluded studies reporting only vitamin D status or mineral metabolism parameters, without any other outcomes of clinical relevance or surrogate laboratory measures. Study quality was evaluated using the Cochrane risk-of-bias tool (RoB2). Results were synthesized in summary tables for each type of outcome with the P values from the original studies displayed. Nine publications were included, corresponding to 5 separate RCTs (377 participants total). Mean age ranged from 40 to 63. All trials administered vitamin D3. Intervention groups experienced improvements in vitamin D status and a reduction in proteinuria in 4 of the 5 included RCTs. There was a decrease in low-density lipoprotein and total cholesterol in the 2 trials in which they were measured. Improvements in bone mass, flow-mediated dilation, and inflammation were also reported, but each was only measured in 1 RCT. Effects on glucose metabolism, high-density lipoprotein, triglycerides, blood pressure, oxidative stress, and kidney function were mixed. No serious adverse effects were reported. Limitations include the small number of RCTs and lack of information on the use of drugs that affect measured outcomes (eg, proteinuria-lowering renin-angiotensin-aldosterone system inhibitors and lipid-lowering medication) in most studies. Our study is also limited by the absence of a prestudy protocol and registration. Native vitamin D is a safe treatment that improves vitamin D status in patients with DKD. Vitamin D may modify proteinuria and lipid metabolism in DKD, but further well-designed trials that include well-established treatments are necessary. Overall, there is limited evidence for beneficial pleiotropic effects of vitamin D in patients with DKD.

Gestational Hypertension and High-Density Lipoprotein Function: An Explorative Study in Overweight/Obese Women of the DALI Cohort.

Gestational hypertension (GHTN) is associated with an increased cardiovascular risk for mothers and their offspring later in life. High-density lipoproteins (HDL) are anti-atherogenic by promoting efflux of cholesterol from macrophages and suppression of endothelial cell activation. Functional impairment of HDL in GHTN-complicated pregnancies may affect long-term health of both mothers and offspring. We studied functional parameters of maternal and neonatal HDL in 192 obese women (pre-pregnancy BMI ≥ 29), who were at high risk for GHTN. Maternal blood samples were collected longitudinally at &lt;20 weeks, at 24-28 and 35-37 weeks of gestation. Venous cord blood was collected immediately after birth. Maternal and cord blood were used to determine functional parameters of HDL, such as HDL cholesterol efflux capacity, activity of the vaso-protective HDL-associated enzyme paraoxonase-1, and levels of the HDL-associated anti-inflammatory apolipoprotein (apo)M. In addition, we determined serum anti-oxidative capacity. Thirteen percent of the women were diagnosed with GHTN. While we found no changes in measures of HDL function in mothers with GHTN, we observed impaired HDL cholesterol efflux capacity and paraoxonase-1 activity in cord blood, while serum antioxidant capacity was increased. Of particular interest, increased maternal paraoxonase-1 activity and apoM levels in early pregnancy were associated with the risk of developing GHTN. GHTN significantly impairs HDL cholesterol efflux capacity as well as HDL PON1 activity in cord blood and could affect vascular health in offspring. Maternal paraoxonase-1 activity and apoM levels in early pregnancy associate with the risk of developing GHTN.

ApoJ/Clusterin concentrations are determinants of cerebrospinal fluid cholesterol efflux capacity and reduced levels are associated with Alzheimer’s disease

BackgroundAlzheimer’s disease (AD) shares risk factors with cardiovascular disease (CVD) and dysregulated cholesterol metabolism is a mechanism common to both diseases. Cholesterol efflux capacity (CEC) is an ex vivo metric of plasma high-density lipoprotein (HDL) function and inversely predicts incident CVD independently of other risk factors. Cholesterol pools in the central nervous system (CNS) are largely separate from those in blood, and CNS cholesterol excess may promote neurodegeneration. CEC of cerebrospinal fluid (CSF) may be a useful measure of CNS cholesterol trafficking. We hypothesized that subjects with AD and mild cognitive impairment (MCI) would have reduced CSF CEC compared with Cognitively Normal (CN) and that CSF apolipoproteins apoA-I, apoJ, and apoE might have associations with CSF CEC.MethodsWe retrieved CSF and same-day ethylenediaminetetraacetic acid (EDTA) plasma from 108 subjects (40 AD; 18 MCI; and 50 CN) from the Center for Neurodegenerative Disease Research biobank at the Perelman School of Medicine, University of Pennsylvania. For CSF CEC assays, we used N9 mouse microglial cells and SH-SY5Y human neuroblastoma cells, and the corresponding plasma assay used J774 cells. Cells were labeled with [3H]-cholesterol for 24 h, had ABCA1 expression upregulated for 6 h, were exposed to 33 μl of CSF, and then were incubated for 2.5 h. CEC was quantified as percent [3H]-cholesterol counts in medium of total counts medium+cells, normalized to a pool sample. ApoA-I, ApoJ, ApoE, and cholesterol were also measured in CSF.ResultsWe found that CSF CEC was significantly lower in MCI compared with controls and was poorly correlated with plasma CEC. CSF levels of ApoJ/Clusterin were also significantly lower in MCI and were significantly associated with CSF CEC. While CSF ApoA-I was also associated with CSF CEC, CSF ApoE had no association with CSF CEC. CSF CEC is significantly and positively associated with CSF Aβ. Taken together, ApoJ/Clusterin may be an important determinant of CSF CEC, which in turn could mitigate risk of MCI and AD risk by promoting cellular efflux of cholesterol or other lipids. In contrast, CSF ApoE does not appear to play a role in determining CSF CEC.

Relationship between circulating adipokines and cholesterol efflux in subjects with severe carotid atherosclerosis

AimsCholesterol efflux capacity (CEC) as a measure of high-density lipoprotein functionality is independently and inversely associated with increased risk of cardiovascular events and mortality, and advanced plaque morphology. Adipokines, adipose tissue-derived factors, can influence systemic lipoprotein metabolism, and participate in the regulation of vascular function and inflammation. We aimed to investigate the association between CEC and circulating adipokine levels (anti-inflammatory adiponectin, and pro-inflammatory chemerin and resistin) in subjects with severe carotid atherosclerotic disease and evaluate its impact on post-surgical outcomes. Methods and resultsThis is a cross-sectional study with a 5-year follow-up component. Consecutive patients with severe carotid atherosclerosis scheduled for a carotid endarterectomy were recruited from hospital-based centres in Montreal, Canada (n = 285). Fasting blood samples were collected pre-operatively and used to measure plasma total and high-molecular weight (HMW) adiponectin, chemerin, and resistin, and to perform cholesterol efflux assays in J774 macrophage-like cells. Five-year post-surgery outcomes were obtained through medical chart review. Subjects had a mean age of 70.1 ± 9.4, were 67.0 % male, had various comorbidities (hypercholesterolemia [85.3 %], hypertension [83.5 %], type 2 diabetes [34.5 %], coronary artery disease [38.6 %]), and previously experienced cerebrovascular symptomatology (77.9 %). CEC was independently and positively associated with total and HMW adiponectin levels (ß [95 % confidence interval]; 0.216 [0.134–0.298] and 0.107 [0.037–0.176], respectively) but not with chemerin or resistin. Total adiponectin had the greatest association accounting for 8.3 % of the variance in CEC. Interaction regression models demonstrated a significant interaction between adiponectin and chemerin in increasing CEC. Notably, with each unit increase in CEC there was a 93.9 % decrease in the odds of having an ischemic cerebrovascular event 5 years post-surgery (0.061 [0.007–0.561]). ConclusionsOur findings demonstrated circulating adiponectin to have a strong association with increased CEC in subjects with severe carotid atherosclerosis and high CEC to be associated with more favourable post-surgical outcomes. These findings reflect the importance of adipose tissue health in influencing CEC levels and atherosclerotic cardiovascular disease risk.

Effects of Antirheumatic Treatment on Cell Cholesterol Efflux and Loading Capacity of Serum Lipoproteins in Spondylarthropathies.

Spondyloarthropathies (SpA) are associated with increased cardiovascular risk. Among possible mechanisms is the dysfunction of serum lipoproteins in regulating cell cholesterol homeostasis. Cholesterol efflux capacity (CEC)-the atheroprotective ability of HDL (high density lipoproteins) to accept cholesterol from macrophages-might predict cardiovascular disease independently of HDL-cholesterol levels. We aimed at evaluating modifications of CEC and of the atherogenic cholesterol loading capacity (CLC) of serum lipoproteins in psoriatic arthritis (PsA) and ankylosing spondylitis (AS) following anti-rheumatic treatment. A total of 62 SpA patients (37 PsA and 25 AS) were evaluated before and after treatment with tumor necrosis factor inhibitor and/or methotrexate. CEC and CLC were measured by radioisotopic and fluorometric techniques, respectively. Endothelial function was assessed by finger plethysmography (Endopat). In the whole SpA group, total and HDL-cholesterol increased after treatment, while lipoprotein(a) decreased and CLC was unchanged. Treatment was associated with increased Scavenger Receptor class B type I (SR-BI)-mediated CEC in the AS group. SR-BI- and ABCG1-mediated CEC were negatively associated with inflammatory parameters and positively related to coffee consumption. SR-BI CEC and CLC were positively and negatively associated with endothelial function, respectively. Our pilot study suggests that anti-rheumatic treatment is associated with favorable modulation of lipoprotein quality and function in SpA, particularly in AS, in spite of the induced increase in total cholesterol levels. If confirmed in a larger population, this might represent an atheroprotective benefit beyond what is reflected by conventional serum lipid profile.

Proteomic analysis of postprandial high-density lipoproteins in healthy subjects

The relationship between the functionality and composition of high-density lipoproteins (HDL) is yet not fully studied, and little is known about the influence of the diet in HDL proteome. Therefore, the aim of this research was to elucidate the HDL proteome associated to postprandial hyperlipidemia. Male volunteers were recruited for an interventional study with high fatty acid-based meals. Blood samples were collected before the intake (baseline), and 2–3 (postprandial peak) and 5–6 (postprandial post peak) hours later. HDL were purified and the protein composition was quantified by LC-MS/MS. Statistical analysis was performed by lineal models (amica) and by ANOVA and multi-t-test of the different conditions (MetaboAnalyst). Additionally, a clustering of the expression profiles of each protein was done with coseq R package (RStudio). Initially, 320 proteins were identified but only 119 remained after the filtering. APOM, APOE, APOB, and APOA2, proteins previously identified in the HDL proteome, were the only proteins with a statistically significant altered expression in postprandial hyperlipidemia when compared to baseline (p values <0.05 and logFC >1). In conclusion, we have been able to describe several behaviors of the whole HDL proteome during the postprandial hyperlipidemic metabolism.

Abstract 14231: Egg Consumption Induces Sex-Specific Changes in High-Density Lipoprotein Composition and Function

Introduction: HDL composition is an important determinant of cardioprotective functions. Importantly, sex-specific differences in HDL composition and function have been observed. While diet represents a promising therapeutic strategy to optimize HDL composition and function, it is unclear whether the capacity to modulate HDL profiles through diet is sex-specific. Hypothesis: We hypothesized that daily consumption of different egg-based diets, which differentially impact HDL particle profiles and efflux capacity, would alter HDL composition and function in a sex-dependent manner. Methods: Healthy men and women (n = 26) participated in a 16-week randomized, crossover intervention trial (NCT03577223), in which they consumed a 4-week egg-free diet, followed by a 4-week diet containing either 3 whole eggs or 3 egg whites per day. Participants then followed a 4-week egg-free washout diet, before switching to the alternative whole egg or egg white diet treatment. Fasted blood samples were collected after each diet period to determine HDL particle profiles by NMR, serum paraoxonase 1 (PON1) lactonase activity, cholesterol efflux capacity, and HDL lipid and protein composition. Results: We observed sex-specific differences in HDL profiles following egg intake. In women, whole egg intake increased HDL-phosphatidylcholine and phosphatidylethanolamine content, whereas HDL-phosphatidylinositol and sphingomyelin were increased and decreased, respectively, in men. Similarly, egg diets differentially and sex-dependently altered HDL proteins implicated in cholesterol efflux capacity and cardiovascular disease risk. Whole egg intake increased HDL-apoAII, apoL1, apoM, and lowered serum amyloid P compared to the egg-free and egg white diets in women, whereas HDL-PON3 was increased by egg white intake in men. PON1 activity and cholesterol efflux capacity were increased following whole egg intake in women only. Independent of sex, changes in cholesterol efflux capacity between the egg white and whole egg periods were positively correlated with the number of total and small HDL particles. Conclusions: Modulation of HDL profiles by diet are sex-specific, with whole egg intake promoting more significant changes in HDL composition and function in women.

Abstract 11756: Tracking High-Density Lipoprotein Functionality in Diabetic and Non-Diabetic Patients With Toe Amputations

Introduction: High-density lipoprotein cholesterol (HDL-c) levels have an established inverse association with cardiovascular event risk. More recently, the focus has shifted to HDL functionality as an improved metric of its predictive value and is impaired in patients with coronary arterial disease. HDL-c levels have been reported to inversely associate with the risk of amputation in patients with diabetic foot ulcers (DFUs), but whether HDL functionality is predictive of wound closure success is currently unknown. Methods: Eighteen diabetic and eight non-diabetic patients with toe/s amputations had blood collected at: (1) the time of surgery, (2) four weeks and (3) six months post-amputation. Wound areas were tracked until closure by 3D camera. Blood was collected from 20 healthy age and gender-matched participants. From blood, HDL was isolated and its functionality tested via (1) cholesterol efflux from macrophages, and (2) anti-inflammatory and (3) pro-angiogenic effects in endothelial cells. Results: Wound closure was faster in non-diabetic than diabetic amputation patients at four weeks (186.6%, P =0.12). Diabetic HDL promoted less cholesterol efflux at four-weeks (37.8%, P &lt;0.05) and six-months (45.6%, P &lt;0.01) post-amputation, compared to non-diabetic HDL. Incubation of non-diabetic HDL with endothelial cells caused greater reductions in inflammatory markers RELA (51.4%, P &lt;0.01), CCL5 (46.9%, P &lt;0.01), CCL2 (15.3%, P &lt;0.05) and ICAM-1 (33.1%, P &lt;0.05) than non-diabetic HDL. Non-diabetic HDL elicited greater endothelial cell angiogenesis with increased Matrigel tubule number at four weeks post amputation (46.15%, P &lt;0.05), compared to diabetic HDL. There were significant correlations between the rate of wound closure and HDL-c levels (R 2 = +0.62, P &lt;0.05), CCL2 (R = -0.64, P &lt;0.05) and ICAM-1 (R = -0.71, P &lt;0.05). Conclusion: In toe amputation patients, HDL-c levels and inflammatory HDL functionality markers associate with the rate of wound closure. HDL from diabetic patients had impaired cholesterol efflux capacity, reduced anti-inflammatory effects and was less able to promote angiogenesis, compared to non-diabetic HDL.

Why are brown bears protected against atherosclerosis even though their plasma cholesterol levels are twice that of humans?

Plasma cholesterol and triglyceride levels are twice as high in hibernating brown bears (Ursus arctos) than in healthy humans. Yet, bears display no sign of atherosclerosis development. To explore this apparent paradox, we analyzed lipoproteins from same ten individual bears plasma collected during winter (hibernation; February) and summer (active; June) in the same year. Plasma from fourteen healthy humans were analyzed as comparator. We used standard methods for lipoprotein isolation, composition and functional investigation. The results shows that in brown bears the absence of atherosclerosis despite elevated cholesterol is likely associated with two main athero-protective properties of circulating lipoproteins. First, a significant ten times lower affinity of low-density-lipoprotein (LDL) particles for arterial proteoglycans and secondly, an elevated plasma cholesterol efflux capacity. What does the brown bear data tell us? That elevated total cholesterol and apoB-containing lipoproteins not always associates with atherosclerosis disease. We need to look also at the lipoprotein biochemical features and functionality as they are relevant for arterial pathophysiology. What is the translatability into human of these results? We humans need to control our total and LDL-cholesterol levels. We are not brown bears!

OR02-1 Differences in HDL Particle Composition in Patients with Nonalcoholic Fatty Liver Disease (NAFLD) and Advanced Liver Fibrosis May Explain Higher Cardiovascular Risk

Abstract The severity of liver fibrosis in patients with NAFLD is a strong predictor of cardiovascular mortality, independently of other well-known cardiovascular risk factors. However, the exact mechanisms leading to cardiovascular disease in patients with advanced liver fibrosis remain incompletely understood. As many of the apolipoproteins are synthesized in the liver, we hypothesized that lipoprotein composition may explain the association between liver disease and cardiovascular disease. Patients (n=185) underwent a liver proton magnetic resonance spectroscopy (1H-MRS) to measure intrahepatic triglyceride accumulation and a percutaneous liver biopsy if they had NAFLD. Advanced lipid testing and lipoprotein subfractions were measured by ion mobility. ApoA-I containing particles (i.e., HDL) were isolated and a novel targeted proteomic approach utilizing multiple reaction monitoring (MRM) by liquid chromatography and tandem mass spectrometry (LC-MS/MS) was undertaken to measure HDL-bound proteins that are associated with lipid metabolism. Forty-five patients did not have NAFLD by 1H-MRS and were used as controls for comparisons. One-hundred and forty patients had a liver biopsy, and 26 were diagnosed with advanced fibrosis. Patients with vs. without advanced fibrosis had similar clinical characteristics (Age: 54±9 vs. 52±11 years; sex: 77% vs. 76% males; BMI: 34.2±4.3 vs. 34.5±4.6 kg/m2). Patients with advanced fibrosis had lower HDL-C (34±8 vs. 38±9 mg/dl, p=0.024) and higher A1c (7.3±1.3% vs. 6.5±1.0%, p&amp;lt;0.001). No differences were observed in LDL or VLDL particle number or size between the groups. Patients with advanced fibrosis showed a mild reduction in HDL particle number, mainly driven by a reduction of small HDL particles (17269±3705 vs. 19057±4052 nmol/L, p=0.042). Despite this small difference in HDL particle number, a significant difference was observed in the proteomic signature of these particles. A panel of twenty-eight HDL-bound proteins were targeted and quantified by MRM LC-MS/MS. After adjustment for multiple comparisons based on a false discovery rate set at 10% (method of Benjamini-Krieger-Yekutieli), five proteins were found to be decreased in patients with advanced fibrosis (ApoC-I, ApoC-IV, ApoM, LCAT, and SAA4; all p&amp;lt;0.017). No differences were observed in these proteins in patients with vs. without NAFLD or steatohepatitis (NASH). The pCAD index [range from 0-100] is a well-validated model based on measurement of 5 HDL-associated apolipoproteins (Apolipoproteins A-I, C-I, C-II, C-III, and C-IV) that is associated with presence of coronary artery disease and cardiovascular mortality. We observed a stepwise increase in pCAD index with every stage of fibrosis among patients with NAFLD (F0: 84±3; F1: 88±3; F2: 90±6; F3-4: 97±1, p=0.037). Conclusion Patients with NAFLD with advanced fibrosis showed significant differences in the apolipoproteomic composition of HDL particles, and this translated into increased cardiovascular risk based on pCAD index. Different lipoprotein composition and function may explain the link between liver disease and increased cardiovascular mortality in these patients. Presentation: Saturday, June 11, 2022 11:30 a.m. - 11:45 a.m.

High-Density Lipoprotein Particle Size and Function Predict Cardiovascular Events in Patients With CKD

High-Density Lipoprotein Particle Size and Function Predict Cardiovascular Events in Patients With CKD