Optimization of time interval for the measurement of plasma lipids for cardiovascular disease risk assessment.

BACKGROUND: Lipid testing for atherosclerotic cardiovascular disease (ASCVD) risk is often performed every 4-6 years, but we hypothesized that the optimum time interval may vary depending on baseline risk. RESEARCH DESIGN AND METHODS: Using lipid values and other risk factors from the National Health and Nutrition Examination Survey (NHANES) (n = 9,704), we calculated a 10-year risk score with the pooled-cohort equations. Future risk scores were predicted by increasing age and projecting systolic blood pressure (SBP) and lipid changes, using the mean-percentile age group change in NHANES for SBP (n = 17,329) and the Lifelines Cohort study for lipids (n = 133,540). The crossing of high and intermediate-risk thresholds were calculated by time to determine optimum intervals for lipid testing. RESULTS: Time to crossing risk thresholds depends on baseline risk, but the mean increase in the risk score plateaus at 1% per year for those with a baseline 10-year risk greater than 15%. Based on these findings, we recommend the following maximum time intervals for lipid testing: baseline risk < 15%: 5-years, 16%: 4-years, 17%: 3-years, 18%: 2-years, and 19%: ≤1-year. CONCLUSIONS: Testing patients for lipids who have a higher baseline risk more often could identify high-risk patients sooner, allowing for earlier and more effective therapeutic intervention.

Approach to the Patient With a Suboptimal Statin Response: Causes and Algorithm for Clinical Management.

CONTEXT: Statins are the lipid-lowering therapy of choice for the prevention of atherosclerotic cardiovascular disease (ASCVD) but their effectiveness in lowering low-density lipoprotein cholesterol (LDL-C) can substantially differ between individuals. In this mini-review, we describe the different causes for a suboptimal statin response and an algorithm for the diagnosis and clinical management of these patients. EVIDENCE ACQUISITION: A PubMed search using the terms "statin resistance," "statin sensitivity," "statin pharmacokinetics," "cardiovascular disease," and "lipid-lowering therapies" was performed. Published papers in the past 10 years that were relevant to the topic were examined to provide content for this mini-review. EVIDENCE SYNTHESIS: Suboptimal lowering of LDL-C by statins is a major problem in the clinical management of patients and limits the value of this therapeutic approach. There are multiple causes of statin hyporesponsiveness with compliance being the most common explanation. Other causes, such as analytical issues with LDL-C measurement and the presence of common lipid disorders (familial hypercholesterolemia, elevated lipoprotein[a] and secondary dyslipidemias) should be excluded before considering primary statin resistance from rare genetic variants in lipoprotein-related or drug-metabolism genes. A wide variety of nonstatin lipid-lowering drugs are now available and can be added to statins to achieve more effective LDL-C lowering. CONCLUSIONS: The evaluation of statin hyporesponsiveness is a multistep process that can lead to the optimization of lipid-lowering therapy for the prevention of ASCVD. It may also lead to the identification of distinct types of dyslipidemias that require specific therapies and/or the genetic screening of family members.

Estimated Atherosclerotic Cardiovascular Disease Risk Score: An Automated Decision Aid for Statin Therapy.

BACKGROUND: Estimation of atherosclerotic cardiovascular disease (ASCVD) risk is a key step in cardiovascular disease (CVD) prevention, but it requires entering additional risk factor information into a computer. We developed a simplified ASCVD risk score that can be automatically calculated by the clinical laboratory when a fasting standard lipid panel is reported. METHODS: Equations for an estimated ASCVD (eASCVD) risk score were developed for 4 race/sex groups (non-Hispanic White/Black, men/women), using the following variables: total cholesterol, high-density lipoprotein cholesterol, triglycerides, and age. The eASCVD score was derived using regression analysis to yield similar risk estimates as the standard ASCVD risk equations for non-diabetic individuals not on lipid-lowering therapy in the National Health and Nutrition Examination Survey (NHANES) (n = 6027). RESULTS: At a cutpoint of 7.5%/10-year, the eASCVD risk score had an overall sensitivity of 69.1% and a specificity of 97.5% for identifying statin-eligible patients with at least intermediate risk based on the standard risk score. By using the sum of other risk factors present (systolic blood pressure >130 mmHg, blood pressure medication use, and cigarette use), the overall sensitivity of the eASCVD score improved to 93.7%, with a specificity of 92.3%. Furthermore, it showed 90% concordance with the standard risk score in predicting cardiovascular events in the Atherosclerosis Risk in Communities (ARIC) study (n = 14 742). CONCLUSIONS: Because the automated eASCVD risk score can be computed for all patients with a fasting standard lipid panel, it could be used as an adjunctive tool for the primary prevention of ASCVD and as a decision aid for statin therapy.

Complex association of apolipoprotein E-containing HDL with coronary artery disease burden in cardiovascular disease.

BackgroundAlthough traditional lipid parameters and coronary imaging techniques are valuable for cardiovascular disease (CVD) risk prediction, better diagnostic tests are still needed.MethodsIn a prospective, observational study, 795 individuals had extensive cardiometabolic profiling, including emerging biomarkers, such as apolipoprotein E-containing HDL-cholesterol (ApoE-HDL-C). Coronary artery calcium (CAC) score was assessed in the entire cohort, and quantitative coronary computed tomography angiography (CCTA) characterization of total burden, noncalcified burden (NCB), and fibrous plaque burden (FB) was performed in a subcohort (n = 300) of patients stratified by concentration of ApoE-HDL-C. Total and HDL-containing apolipoprotein C-III (ApoC-III) were also measured.ResultsMost patients had a clinical diagnosis of coronary artery disease (CAD) (n = 80.4% of 795), with mean age of 59 years, a majority being male (57%), and about half on statin treatment. The low ApoE-HDL-C group had more severe stenosis (11% vs. 2%, overall P < 0.001), with higher CAC as compared with high ApoE-HDL-C. On quantitative CCTA, the high ApoE-HDL-C group had lower NCB (ß = -0.24, P = 0.0001), which tended to be significant in a fully adjusted model (ß = -0.32, P = 0.001) and altered by ApoC-III in HDL levels. Low ApoE-HDL-C was significantly associated with LDL particle number (ß = 0.31; P = 0.0001). Finally, when stratified by FB, ApoC-III in HDL showed a more robust predictive value of CAD over ApoE-HDL-C (AUC: 0.705, P = 0.0001) in a fully adjusted model.ConclusionApoE-containing HDL-C showed a significant association with early coronary plaque characteristics and is affected by the presence of ApoC-III, indicating that low ApoE-HDL-C and high ApoC-III may be important markers of CVD severity.Trial RegistrationClinicalTrials.gov: NCT01621594.FundingThis work was supported by the NHLBI at the NIH Intramural Research Program.

A new phenotypic classification system for dyslipidemias based on the standard lipid panel.

BACKGROUND: Dyslipoproteinemias can be classified by their distinct lipoprotein patterns, which helps determine atherosclerotic cardiovascular disease (ASCVD) risk and directs lipid management but this has required advanced laboratory testing. OBJECTIVE: To develop a new algorithm for classifying lipoprotein disorders that only relies on the standard lipid panel. METHODS: Lipid thresholds for defining the different lipoprotein phenotypes were derived for Non-High-Density Lipoprotein-Cholesterol (NonHDL-C) and Triglycerides (TG) to be concordant when possible with the current US Multi-Society guidelines for blood cholesterol management. RESULTS: The new classification method categorizes patients into all the classical Fredrickson-like phenotypes except for Type III dysbetalipoproteinemia. In addition, a new hypolipidemic phenotype (Type VI) due to genetic mutations in apoB-metabolism is described. The validity of the new algorithm was confirmed by lipid analysis by NMR (N = 11,365) and by concordance with classification by agarose gel electrophoresis/beta-quantification (N = 5504). Furthermore, based on the Atherosclerosis Risk in Communities (ARIC) cohort (N = 14,742), the lipoprotein phenotypes differ in their association with ASCVD (TypeV>IIb > IVb > IIa > IVa > normolipidemic) and can be used prognostically as risk enhancer conditions in the management of patients. CONCLUSIONS: We describe a clinically useful lipoprotein phenotyping system that is only dependent upon the standard lipid panel. It, therefore, can be easily implemented for increasing compliance with current guidelines and for improving the care of patients at risk for ASCVD.

Apolipoprotein Mimetic Peptides: Potential New Therapies for Cardiovascular Diseases.

Since the seminal breakthrough of treating diabetic patients with insulin in the 1920s, there has been great interest in developing other proteins and their peptide mimetics as therapies for a wide variety of other medical disorders. Currently, there are at least 60 different peptides that have been approved for human use and over 150 peptides that are in various stages of clinical development. Peptides mimetic of the major proteins on lipoproteins, namely apolipoproteins, have also been developed first as tools for understanding apolipoprotein structure and more recently as potential therapeutics. In this review, we discuss the biochemistry, peptide mimetics design and clinical trials for peptides based on apoA-I, apoE and apoC-II. We primarily focus on applications of peptide mimetics related to cardiovascular diseases. We conclude with a discussion on the limitations of peptides as therapeutic agents and the challenges that need to be overcome before apolipoprotein mimetic peptides can be developed into new drugs.

SR-BI mediates neutral lipid sorting from LDL to lipid droplets and facilitates their formation.

SR-BI binds various lipoproteins, including HDL, LDL as well as VLDL, and mediates selective cholesteryl ester (CE) uptake. HDL derived CE accumulates in cellular lipid droplets (LDs), which also store triacylglycerol (TAG). We hypothesized that SR-BI could significantly facilitate LD formation, in part, by directly transporting LDL derived neutral lipids (NL) such as CE and TAG into LDs without lipolysis and de novo lipid synthesis. SR-BI overexpression greatly increased LDL uptake and LD formation in stably transfected HeLa cells (SR-BI-HeLa). LDs isolated from SR-BI-HeLa contained 4- and 7-times more CE and TAG, respectively, than mock-transfected HeLa (Mock-HeLa). In contrast, LDL receptor overexpression in HeLa (LDLr-HeLa) greatly increased LDL uptake, degradation with moderate 1.5- and 2-fold increases of CE and TAG, respectively. Utilizing CE and TAG analogs, BODIPY-TAG (BP-TAG) and BODIPY-CE (BP-CE), for tracking LDL NL, we found that after initial binding of LDL to SR-BI-HeLa, apoB remained at the cell surface, while BP-CE and BP-TAG were sorted and simultaneously transported together to LDs. Both lipids demonstrated limited internalization to lysosomes or endoplasmic reticulum in SR-BI-HeLa. In LDLr-HeLa, NLs demonstrated clear lysosomal sequestration without their sorting to LDs. An inhibition of TAG and CE de novo synthesis by 90-95% only reduced TAG and CE LD content by 45-50%, and had little effect on BP-CE and BP-TAG transport to LDs in SR-BI HeLa. Furthermore, intravenous infusion of 1-2 mg of LDL increased liver LDs in normal (WT) but not in SR-BI KO mice. Mice transgenic for human SR-BI demonstrated higher liver LD accumulation than WT mice. Finally, Electro Spray Infusion Mass Spectrometry (ESI-MS) using deuterated d-CE found that LDs accumulated up to 40% of unmodified d-CE LDL. We conclude that SR-BI mediates LDL-induced LD formation in vitro and in vivo. In addition to cytosolic NL hydrolysis and de novo lipid synthesis, this process includes selective sorting and transport of LDL NL to LDs with limited lysosomal NL sequestration and the transport of LDL CE, and TAG directly to LDs independently of de novo synthesis.

Effect of niacin monotherapy on high density lipoprotein composition and function.

BACKGROUND: Niacin has modest but overall favorable effects on plasma lipids by increasing high density lipoprotein cholesterol (HDL-C) and lowering triglycerides. Clinical trials, however, evaluating niacin therapy for prevention of cardiovascular outcomes have returned mixed results. Recent evidence suggests that the HDL proteome may be a better indicator of HDL's cardioprotective function than HDL-C. The objective of this study was to evaluate the effect of niacin monotherapy on HDL protein composition and function. METHODS: A 20-week investigational study was performed with 11 participants receiving extended-release niacin (target dose = 2 g/day) for 16-weeks followed by a 4-week washout period. HDL was isolated from participants at weeks: 0, 16, and 20. The HDL proteome was analyzed at each time point by mass spectrometry and relative protein quantification was performed by label-free precursor ion intensity measurement. RESULTS: In this cohort, niacin therapy had typical effects on routine clinical lipids (HDL-C + 16%, q < 0.01; LDL-C - 20%, q < 0.01; and triglyceride - 15%, q = 0.1). HDL proteomics revealed significant effects of niacin on 5 proteins: serum amyloid A (SAA), angiotensinogen (AGT), apolipoprotein A-II (APOA2), clusterin (CLUS), and apolipoprotein L1 (APOL1). SAA was the most prominently affected protein, increasing 3-fold in response to niacin (q = 0.008). Cholesterol efflux capacity was not significantly affected by niacin compared to baseline, however, stopping niacin resulted in a 9% increase in efflux (q < 0.05). Niacin did not impact HDL's ability to influence endothelial function. CONCLUSION: Extended-release niacin therapy, in the absence of other lipid-modifying medications, can increase HDL-associated SAA, an acute phase protein associated with HDL dysfunction.

Comparison of Omega-3 Eicosapentaenoic Acid Versus Docosahexaenoic Acid-Rich Fish Oil Supplementation on Plasma Lipids and Lipoproteins in Normolipidemic Adults.

BACKGROUND: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have both shared and different cardiovascular effects, and commonly used fish oil supplements have considerably varied EPA/DHA ratios. AIMS: We compared the effects of fish oil supplements with different EPA/DHA ratios on lipoprotein metabolism. METHODS: In a double-blind, randomized cross-over study, normolipidemic adults (n = 30) consumed 12 g/day of EPA-rich (EPA/DHA: 2.3) or DHA-rich (EPA/DHA: 0.3) fish oil for 8-weeks, separated by an 8-week washout period. RESULTS: Both fish oil supplements similarly lowered plasma TG levels and TG-related NMR parameters versus baseline (p < 0.05). There were no changes in plasma cholesterol-related parameters due to either fish oil, although on-treatment levels for LDL particle number were slightly higher for DHA-rich oil compared with EPA-rich oil (p < 0.05). Both fish oil supplements similarly altered HDL subclass profile and proteome, and down regulated HDL proteins related to inflammation, with EPA-rich oil to a greater extent. Furthermore, EPA-rich oil increased apoM abundance versus DHA-rich oil (p < 0.05). CONCLUSIONS: Overall, fish oil supplements with varied EPA/DHA ratios had similar effects on total lipids/lipoproteins, but differences were observed in lipoprotein subfraction composition and distribution, which could impact on the use of EPA versus DHA for improving cardiovascular health.

A New Equation for Calculation of Low-Density Lipoprotein Cholesterol in Patients With Normolipidemia and/or Hypertriglyceridemia.

Importance: Low-density lipoprotein cholesterol (LDL-C), a key cardiovascular disease marker, is often estimated by the Friedewald or Martin equation, but calculating LDL-C is less accurate in patients with a low LDL-C level or hypertriglyceridemia (triglyceride [TG] levels ≥400 mg/dL). Objective: To design a more accurate LDL-C equation for patients with a low LDL-C level and/or hypertriglyceridemia. Design, Setting, and Participants: Data on LDL-C levels and other lipid measures from 8656 patients seen at the National Institutes of Health Clinical Center between January 1, 1976, and June 2, 1999, were analyzed by the ß-quantification reference method (18 715 LDL-C test results) and were randomly divided into equally sized training and validation data sets. Using TG and non-high-density lipoprotein cholesterol as independent variables, multiple least squares regression was used to develop an equation for very low-density lipoprotein cholesterol, which was then used in a second equation for LDL-C. Equations were tested against the internal validation data set and multiple external data sets of either ß-quantification LDL-C results (n = 28 891) or direct LDL-C test results (n = 252 888). Statistical analysis was performed from August 7, 2018, to July 18, 2019. Main Outcomes and Measures: Concordance between calculated and measured LDL-C levels by ß-quantification, as assessed by various measures of test accuracy (correlation coefficient [R2], root mean square error [RMSE], mean absolute difference [MAD]), and percentage of patients misclassified at LDL-C treatment thresholds of 70, 100, and 190 mg/dL. Results: Compared with ß-quantification, the new equation was more accurate than other LDL-C equations (slope, 0.964; RMSE = 15.2 mg/dL; R2 = 0.9648; vs Friedewald equation: slope, 1.056; RMSE = 32 mg/dL; R2 = 0.8808; vs Martin equation: slope, 0.945; RMSE = 25.7 mg/dL; R2 = 0.9022), particularly for patients with hypertriglyceridemia (MAD = 24.9 mg/dL; vs Friedewald equation: MAD = 56.4 mg/dL; vs Martin equation: MAD = 44.8 mg/dL). The new equation calculates the LDL-C level in patients with TG levels up to 800 mg/dL as accurately as the Friedewald equation does for TG levels less than 400 mg/dL and was associated with 35% fewer misclassifications when patients with hypertriglyceridemia (TG levels, 400-800 mg/dL) were categorized into different LDL-C treatment groups. Conclusions and Relevance: The new equation can be readily implemented by clinical laboratories with no additional costs compared with the standard lipid panel. It will allow for more accurate calculation of LDL-C level in patients with low LDL-C levels and/or hypertriglyceridemia (TG levels, ≤800 mg/dL) and thus should improve the use of LDL-C level in cardiovascular disease risk management.

A dual apolipoprotein C-II mimetic-apolipoprotein C-III antagonist peptide lowers plasma triglycerides.

Recent genetic studies have established that hypertriglyceridemia (HTG) is causally related to cardiovascular disease, making it an active area for drug development. We describe a strategy for lowering triglycerides (TGs) with an apolipoprotein C-II (apoC-II) mimetic peptide called D6PV that activates lipoprotein lipase (LPL), the main plasma TG-hydrolyzing enzyme, and antagonizes the TG-raising effect of apoC-III. The design of D6PV was motivated by a combination of all-atom molecular dynamics simulation of apoC-II on the Anton 2 supercomputer, structural prediction programs, and biophysical techniques. Efficacy of D6PV was assessed ex vivo in human HTG plasma and was found to be more potent than full-length apoC-II in activating LPL. D6PV markedly lowered TG by more than 80% within a few hours in both apoC-II-deficient mice and hAPOC3-transgenic (Tg) mice. In hAPOC3-Tg mice, D6PV treatment reduced plasma apoC-III by 80% and apoB by 65%. Furthermore, low-density lipoprotein (LDL) cholesterol did not accumulate but rather was decreased by 10% when hAPOC3-Tg mice lacking the LDL-receptor (hAPOC3-Tg × Ldlr-/- ) were treated with the peptide. D6PV lowered TG by 50% in whole-body inducible Lpl knockout (iLpl-/- ) mice, confirming that it can also act independently of LPL. D6PV displayed good subcutaneous bioavailability of about 80% in nonhuman primates. Because it binds to high-density lipoproteins, which serve as a long-term reservoir, it also has an extended terminal half-life (42 to 50 hours) in nonhuman primates. In summary, D6PV decreases plasma TG by acting as a dual apoC-II mimetic and apoC-III antagonist, thereby demonstrating its potential as a treatment for HTG.

LCAT protects against Lipoprotein-X formation in a murine model of drug-induced intrahepatic cholestasis.

Familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is a rare genetic disease characterized by low HDL-C levels, low plasma cholesterol esterification, and the formation of Lipoprotein-X (Lp-X), an abnormal cholesterol-rich lipoprotein particle. LCAT deficiency causes corneal opacities, normochromic normocytic anemia, and progressive renal disease due to Lp-X deposition in the glomeruli. Recombinant LCAT is being investigated as a potential therapy for this disorder. Several hepatic disorders, namely primary biliary cirrhosis, primary sclerosing cholangitis, cholestatic liver disease, and chronic alcoholism also develop Lp-X, which may contribute to the complications of these disorders. We aimed to test the hypothesis that an increase in plasma LCAT could prevent the formation of Lp-X in other diseases besides FLD. We generated a murine model of intrahepatic cholestasis in LCAT-deficient (KO), wild type (WT), and LCAT-transgenic (Tg) mice by gavaging mice with alpha-naphthylisothiocyanate (ANIT), a drug well known to induce intrahepatic cholestasis. Three days after the treatment, all mice developed hyperbilirubinemia and elevated liver function markers (ALT, AST, Alkaline Phosphatase). The presence of high levels of LCAT in the LCAT-Tg mice, however, prevented the formation of Lp-X and other plasma lipid abnormalities in WT and LCAT-KO mice. In addition, we demonstrated that multiple injections of recombinant human LCAT can prevent significant accumulation of Lp-X after ANIT treatment in WT mice. In summary, LCAT can protect against the formation of Lp-X in a murine model of cholestasis and thus recombinant LCAT could be a potential therapy to prevent the formation of Lp-X in other diseases besides FLD.

Supplementation with saury oil, a fish oil high in omega-11 monounsaturated fatty acids, improves plasma lipids in healthy subjects.

BACKGROUND: Fish oil enriched in omega-11 long-chain monounsaturated fatty acids (LCMUFAs; C20:1 and C22:1 isomers combined) have shown lipid-lowering and atheroprotective effects in animal models. OBJECTIVE: To perform a first-in-human trial of LCMUFA-rich saury fish oil supplementation to test its safety and possible effect on plasma lipids. METHODS: A double-blind, randomized, crossover clinical trial was carried out in 30 healthy normolipidemic adults (BMI <25 kg/m2; mean TG, 84 mg/dL). Treatment periods of 8 weeks were separated by an 8-week washout period. Subjects were randomized to receive either 12 g of saury oil (3.5 g of LCMUFA and 3.4 g of omega-3 FAs) or identical capsules with control oil (a mixture of sardine and olive oil; 4.9 g of shorter-chain MUFA oleate and 3 g of omega-3 FAs). RESULTS: Saury oil supplementation was safe and resulted in LDL particle counts 12% lower than control oil (P < .001). Saury oil also had a minor effect on increasing HDL particle size (9.8 nm vs 9.7 nm; P < .05) based on a linear mixed effect model. In contrast, control oil, but not saury oil, increased LDL-C by 7.5% compared with baseline (P < .05). Saury oil had similar effects compared with control oil on lowering plasma TG levels, VLDL, and TG-rich lipoprotein particle counts (by ∼16%, 25%, and 35%, respectively; P < .05), and increasing HDL-C and cholesterol efflux capacity (by ∼6% and 8%, respectively; P < .05) compared with baseline. CONCLUSION: Saury oil supplementation is well tolerated and has beneficial effects on several cardiovascular parameters, such as LDL particle counts, HDL particle size, and plasma TG levels.

Apolipoprotein C-II Mimetic Peptide Promotes the Plasma Clearance of Triglyceride-Rich Lipid Emulsion and the Incorporation of Fatty Acids into Peripheral Tissues of Mice.

AIM: Plasma apolipoprotein C-II (apoC-II) activates lipoprotein lipase (LPL) and thus lowers plasma triglycerides (TG). We previously reported that a human apoC-II mimetic peptide (C-II-a) decreased plasma TG in apoC-II mutant mice, as well as in apoE-knockout mice. Because it is unknown what tissues take up free fatty acids (FFAs) released from TG after C-II-a peptide administration, we investigated in mice TG plasma clearance and tissue incorporation, using 3H-triolein as a tracer, with and without C-II-a treatment. METHODS AND RESULTS: Intralipid® fat emulsion was labeled with 3H-triolein and then mixed with or without C-II-a. Addition of the peptide did not alter mean particle size of the lipid emulsion particles (298 nm) but accelerated their plasma clearance. After intravenous injection into C57BL/6N mice, the plasma half-life of the 3H-triolein for control and C-II-a treated emulsions was 18.3 ± 2.2 min and 14.8 ± 0.1 min, respectively. In apoC-II mutant mice, the plasma half-life of 3H-triolein for injected control and C-II-a treated emulsions was 30.1 ± 0.1 min and 14.8 ± 0.1 min, respectively. C57BL/6N and apoC-II mutant mice at 120 minutes after the injection showed increased tissue incorporation of radioactivity in white adipose tissue when C-II-a treated emulsion was used. Higher radiolabeled uptake of lipids from C-II-a treated emulsion was also observed in the skeletal muscle of C57BL/6N mice only. In case of apoC-II mutant mice, decreased uptake of radioactive lipids was observed in the liver and kidney after addition of C-II-a to the lipid emulsion. CONCLUSIONS: C-II-a peptide promotes the plasma clearance of TG-rich lipid emulsions in wild type and apoC-II mutant mice and promotes the incorporation of fatty acids from TG in the lipid emulsions into specific peripheral tissues.

Dietary Palmitoleic Acid Attenuates Atherosclerosis Progression and Hyperlipidemia in Low-Density Lipoprotein Receptor-Deficient Mice.

SCOPE: Palmitoleic acid (palmitoleate; C16:1 n-7), an omega-7 monounsaturated fatty acid (MUFA) found in plants and marine sources, has been shown to favorably modulate lipid and glucose metabolism. However, its impact on atherosclerosis has not been examined in detail. METHODS AND RESULTS: LDL receptor knock out (LDLR-KO) mice are fed a Western diet supplemented with 5% (w/w) palmitoleate concentrate, oleic-rich olive oil, or none (control) for 12 weeks. Dietary palmitoleate increases hepatic C16:1 levels, improves plasma and hepatic lipid/lipoprotein profiles (≈40% decrease in triglycerides), and reduces the atherosclerotic plaque area by ≈45% compared with control or olive oil group (p < 0.05). These favorable changes are accompanied by the downregulation of key genes, such as Srebp1c, Scd1, Il-1ß, and Tnfα. ApoB-depleted plasma from mice fed palmitoleate has increased cholesterol efflux capacity by 20% from ABCA1-expressing cells (p < 0.05). A beneficial effect of palmitoleate on glucose metabolism (54% decreased in HOMA-IR, p < 0.05) is also observed. CONCLUSIONS: Dietary-supplemented palmitoleate reduces atherosclerosis development in LDLR-KO mice, and is associated with improvement of lipid and glucose metabolism and favorable changes in regulatory genes involved in lipogenesis and inflammation. These findings imply the potential role of dietary palmitoleate in the prevention of cardiovascular disease and diet-induced metabolic disorders.

Intravenous toxicity and toxicokinetics of an HDL mimetic, Fx-5A peptide complex, in cynomolgus monkeys.

Fx-5A peptide complex (Fx-5A), a High Density Lipoproteins (HDL) mimetic, has been shown to reduce atherosclerosis. The safety and toxicokinetics of Fx-5A administered IV by 30 min infusion at 8, 25 or 75 mg/kg body weight or vehicle, once every other day for 27 days, were assessed in cynomolgus monkeys. The Fx-5A was well tolerated at all doses. At the highest dose, there were statistically significant effects on hematology and clinical chemistry parameters that were considered non-adverse. Dose-dependent recoverable non-adverse erythrocytes morphological changes (acanthocytes, echinocytes, spherocytes, microcytes, and/or schistocytes) were observed. Fx-5A was not hemolytic in in-vitro fresh NHP or human blood assay. There were no Fx-5A-related statistically significant changes for any cardiovascular function, ECG or respiratory parameters, when compared to control. In addition, there were no Fx-5A-related effects on organ weights, macroscopic or microscopic endpoints. Finally, Fx-5A exhibited sporadic non-appreciable detection of anti-Fx-5A antibodies and a dose-dependent linear toxicokinetics with T1/2 value ranges from 2.7 to 6.2 h. In conclusion, the No Observed Adverse Effect Level was considered to be 75 mg/kg/day with associated exposures average Cmax and AUC0-last of 453 µg/mL and 2232 h µg/mL, respectively, on Day 27.

Apolipoprotein C-II: New findings related to genetics, biochemistry, and role in triglyceride metabolism.

Apolipoprotein C-II (apoC-II) is a small exchangeable apolipoprotein found on triglyceride-rich lipoproteins (TRL), such as chylomicrons (CM) and very low-density lipoproteins (VLDL), and on high-density lipoproteins (HDL), particularly during fasting. ApoC-II plays a critical role in TRL metabolism by acting as a cofactor of lipoprotein lipase (LPL), the main enzyme that hydrolyses plasma triglycerides (TG) on TRL. Here, we present an overview of the role of apoC-II in TG metabolism, emphasizing recent novel findings regarding its transcriptional regulation and biochemistry. We also review the 24 genetic mutations in the APOC2 gene reported to date that cause hypertriglyceridemia (HTG). Finally, we describe the clinical presentation of apoC-II deficiency and assess the current therapeutic approaches, as well as potential novel emerging therapies.

Human SR-BII mediates SAA uptake and contributes to SAA pro-inflammatory signaling in vitro and in vivo.

Serum amyloid A (SAA) is an acute phase protein with cytokine-like and chemotactic properties, that is markedly up-regulated during various inflammatory conditions. Several receptors, including FPRL-1, TLR2, TLR4, RAGE, class B scavenger receptors, SR-BI and CD36, have been identified as SAA receptors. This study provides new evidence that SR-BII, splice variant of SR-BI, could function as an SAA receptor mediating its uptake and pro-inflammatory signaling. The uptake of Alexa Fluor488 SAA was markedly (~3 fold) increased in hSR-BII-expressing HeLa cells when compared with mock-transfected cells. The levels of SAA-induced interleukin-8 secretion by hSR-BII-expressing HEK293 cells were also significantly (~3-3.5 fold) higher than those detected in control cells. Moderately enhanced levels of phosphorylation of all three mitogen-activated protein kinases, ERK1/2, and p38 and JNK, were observed in hSR-BII-expressing cells following SAA stimulation when compared with control wild type cells. Transgenic mice with pLiv-11-directed liver/kidney overexpression of hSR-BI or hSR-BII were used to assess the in vivo role of each receptor in SAA-induced pro-inflammatory response in these organs. Six hours after intraperitoneal SAA injection both groups of transgenic mice demonstrated markedly higher (~2-5-fold) expression levels of inflammatory mediators in the liver and kidney compared to wild type mice. Histological examinations of hepatic and renal tissue from SAA-treated mice revealed moderate level of damage in the liver of both transgenic but not in the wild type mice. Activities of plasma transaminases, biomarkers of liver injury, were also moderately higher in hSR-B transgenic mice when compared to wild type mice. Our findings identify hSR-BII as a functional SAA receptor that mediates SAA uptake and contributes to its pro-inflammatory signaling via the MAPKs-mediated signaling pathways.

A Novel APOC2 Missense Mutation Causing Apolipoprotein C-II Deficiency With Severe Triglyceridemia and Pancreatitis.

Context: Familial chylomicronemia syndrome (FCS) is a rare heritable disorder associated with severe hypertriglyceridemia and recurrent pancreatitis. Lipoprotein lipase deficiency and apolipoprotein C-II deficiency are two well-characterized autosomal recessive causes of FCS, and three other genes have been described to cause FCS. Because therapeutic approaches can vary according to the underlying etiology, it is important to establish the molecular etiology of FCS. Case Description: A man originally from North Africa was referred to the University of Pennsylvania Lipid Clinic for severe hypertriglyceridemia and recurrent pancreatitis, consistent with the clinical diagnosis of FCS. Molecular analyses of FCS-associated genes revealed a homozygous missense variant R72T in APOC2. Molecular modeling of the variant predicted that the apolipoprotein C-II R72T peptide has reduced lipid binding affinity. In vitro studies of the patient's plasma confirmed the lack of functional apoC-II activity. Moreover, the apoC-II protein was undetectable in the patient's plasma, quantitatively as well as qualitatively. Conclusions: We identified a missense APOC2 variant causing apoC-II deficiency in a patient with severe hypertriglyceridemia and recurrent pancreatitis. Beyond dietary management and usual pharmacologic therapies, an apoC-II mimetic peptide may become an optional therapy in patients with apoC-II deficiency in the future.