Composition and distribution of lipoproteins after evolocumab in familial dysbetalipoproteinemia: A randomized controlled trial.

BACKGROUND: Proprotein convertase subtilisin kexin type 9 (PCSK9) monoclonal antibodies (mAbs) reduce fasting and post fat load cholesterol in non-HDL and intermediate density lipoprotein (IDL) in familial dysbetalipoproteinemia (FD). However, the effect of PCSK9 mAbs on the distribution and composition of atherogenic lipoproteins in patients with FD is unknown. OBJECTIVE: To evaluate the effect of the PCSK9 mAb evolocumab added to standard lipid-lowering therapy in patients with FD on fasting and post fat load lipoprotein distribution and composition. METHODS: Randomized placebo-controlled double-blind crossover trial comparing evolocumab (140 mg subcutaneous every 2 weeks) with placebo during two 12-week treatment periods. Patients received an oral fat load at the start and end of each treatment period. Apolipoproteins (apo) were measured with ultracentrifugation, gradient gel electrophoresis, retinyl palmitate and SDS-PAGE. RESULTS: PCSK9 mAbs significantly reduced particle number of all atherogenic lipoproteins, with a stronger effect on smaller lipoproteins than on larger lipoproteins (e.g. IDL-apoB 49%, 95%confidence interval (CI) 41-59 and very low-density lipoprotein (VLDL)-apoB 33%, 95%CI 16-50). Furthermore, PCSK9 mAbs lowered cholesterol more than triglyceride (TG) in VLDL, IDL and low-density lipoprotein (LDL) (e.g. VLDL-C 48%, 95%CI 29-63%; and VLDL-TG 20%, 95%CI 6.3-41%). PCSK9 mAbs did not affect the post fat load response of chylomicrons. CONCLUSION: PCSK9 mAbs added to standard lipid-lowering therapy in FD patients significantly reduced lipoprotein particle number, in particular the smaller and more cholesterol-rich lipoproteins (i.e. IDL and LDL). PCSK9 mAbs did not affect chylomicron metabolism. It seems likely that the observed effects are achieved by increased hepatic lipoprotein clearance, but the specific working mechanism of PCSK9 mAbs in FD patients remains to be elucidated.

Low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol measurement in Familial Dysbetalipoproteinemia.

AIM: To compare LDL-C concentrations using the Friedewald formula, the Martin-Hopkins formula, a direct assay and polyacrylamide gradient gel electrophoresis (PGGE) to the reference standard density gradient ultracentrifugation in patients with Familial Dysbetalipoproteinemia (FD) patients. We also compared non-HDL-cholesterol concentrations by two methods. METHODS: For this study data from 28 patients with genetically confirmed FD from the placebo arm of the EVOLVE-FD trial were used. Four different methods for determining LDL-C were compared with ultracentrifugation. Non-HDL-C was measured with standard assays and compared to ultracentrifugation. Correlation coefficients and Bland-Altman plots were used to compare the methods. RESULTS: Mean age of the 28 FD patients was 62 ± 9 years, 43 % were female and 93 % had an ɛ2ɛ2 genotype. LDL-C determined by Friedewald (R2 = 0.62, p <0.01), Martin-Hopkins (R2 = 0.50, p = 0.01) and the direct assay (R2 = 0.41, p = 0.03) correlated with density gradient ultracentrifugation. However, Bland-Altman plots showed considerable over- or underestimation by the four methods compared to ultracentrifugation. Non-HDL-C showed good correlation and agreement. CONCLUSION: In patients with FD, all four methods investigated over- or underestimated LDL-C concentrations compared with ultracentrifugation. In contrast, standard non-HDL-C assays performed well, emphasizing the use of non-HDL-C in patients with FD.

Establishing the relationship between familial dysbetalipoproteinemia and genetic variants in the APOE gene.

Familial Dysbetalipoproteinemia (FD) is the second most common monogenic dyslipidemia and is associated with a very high cardiovascular risk due to cholesterol-enriched remnant lipoproteins. FD is usually caused by a recessively inherited variant in the APOE gene (ε2ε2), but variants with dominant inheritance have also been described. The typical dysbetalipoproteinemia phenotype has a delayed onset and requires a metabolic hit. Therefore, the diagnosis of FD should be made by demonstrating both the genotype and dysbetalipoproteinemia phenotype. Next Generation Sequencing is becoming more widely available and can reveal variants in the APOE gene for which the relation with FD is unknown or uncertain. In this article, two approaches are presented to ascertain the relationship of a new variant in the APOE gene with FD. The comprehensive approach consists of determining the pathogenicity of the variant and its causal relationship with FD by confirming a dysbetalipoproteinemia phenotype, and performing in vitro functional tests and, optionally, in vivo postprandial clearance studies. When this is not feasible, a second, pragmatic approach within reach of clinical practice can be followed for individual patients to make decisions on treatment, follow-up, and family counseling.

Modern prevalence of dysbetalipoproteinemia (Fredrickson-Levy-Lees type III hyperlipoproteinemia).

INTRODUCTION: Dysbetalipoproteinaemia (HLP3) is a disorder characterized by excess cholesterol-enriched, triglyceride-rich lipoprotein remnants in genetically predisposed individuals that powerfully promote premature cardiovascular disease if untreated. The current prevalence of HLP3 is largely unknown. MATERIAL AND METHODS: We performed cross-sectional analysis of 128,485 U.S. adults from the Very Large Database of Lipids (VLDbL), using four algorithms to diagnose HLP3 employing three Vertical Auto Profile ultracentrifugation (UC) criteria and a previously described apolipoprotein B (apoB) method. We evaluated 4,926 participants from the 2011-2014 National Health and Nutrition Examination Survey (NHANES) with the apoB method. We examined demographic and lipid characteristics stratified by presence of HLP3 and evaluated lipid characteristics in those with HLP3 phenotype discordance and concordance as determined by apoB and originally defined UC criteria 1. RESULTS: In U.S. adults in VLDbL and NHANES, a 1.7-2.0% prevalence is observed for HLP3 with the novel apoB method as compared to 0.2-0.8% prevalence in VLDbL via UC criteria 1-3. Participants who were both apoB and UC criteria HLP3 positive had higher remnant particles as well as more elevated triglyceride/apoB and total cholesterol/apoB ratios (all p < 0.001) than those who were apoB method positive and UC criteria 1 negative. CONCLUSIONS: HLP3 may be more prevalent than historically and clinically appreciated. The apoB method increases HLP3 identification via inclusion of milder phenotypes. Further work should evaluate the clinical implications of HLP3 diagnosis at various lipid algorithm cut-points to evaluate the ideal standard in the modern era.

Triglycerides, hypertension, and smoking predict cardiovascular disease in dysbetalipoproteinemia.

BACKGROUND: Dysbetalipoproteinemia (DBL) is an autosomal recessive lipid disorder associated with a reduced clearance of remnant lipoproteins and is associated with an increased cardiovascular disease (CVD) risk. The genetic cause of DBL is apoE2 homozygosity in 90% of cases. However, a second metabolic hit must be present to precipitate the disease. However, no study has investigated the predictors of CVD, peripheral artery disease and coronary artery disease in a large cohort of patients with DBL. OBJECTIVE: The objectives of this study were to describe the clinical characteristics of a DBL cohort and to identify the predictors of CVD, peripheral artery disease, and coronary artery disease in this population. METHODS: The inclusion criteria included age ≥ 18 years, apoE2/E2, triglycerides (TG) > 135 mg/dL and VLDL-C/plasma TG ratio > 0.30. RESULTS: We studied 221 adult DBL patients, of which 51 (23%) had a history of CVD. We identified 3 independent predictors of CVD, namely hypertension (OR 5.68, 95% CI 2.13-15.16, P = .001), pack year of smoking (OR 1.03, 95% CI 1.01-1.05, P = .01) and TG tertile (OR 1.82, 95% CI 1.09-3.05, P = .02). The CVD prevalence was 51% in patients with hypertension and 18% in those without hypertension (P = .00001), and 30% in the highest TG tertile vs 15% in the lowest tertile (P = .04). Similarly, the CVD prevalence was higher in heavy smokers compared with nonsmokers (36% vs 13%, P = .006). CONCLUSION: Hypertension, smoking, and TG are independently associated with CVD risk in patients with DBL. Aggressive treatment should be initiated in patients with DBL because of the increased risk of CVD.

A Boy with Yellowish Striae on the Palmar Crease / 대한피부과학회지

No abstract available.

A case of nephrotic syndrome showing contemporary presence of apolipoprotein E2 homozygote glomerulopathy and membranous nephropathy-like findings modified by apolipoprotein E Toyonaka.

A 79-year-old man was admitted to our hospital for proteinuria due to nephrotic syndrome. Renal biopsy revealed focal sclerosis and foam cell infiltration in the glomerulus. In addition, electron microscopic findings (EM) revealed peculiar electron-dense deposits (EDDs) in both sides of the glomerular basement membrane. Although subepithelial deposits had spike formation highly resembling those seen in membranous nephropathy (MN), immunoglobulins and complements were not identified by immunofluorescence study, and microbubbles appeared in high magnification of EM different from the immune disease. The analysis of apolipoprotein (Apo) E showed an elevated concentration of plasma ApoE. The phenotype, genotype, and DNA sequence studies revealed homozygous ApoE2/2 and a novel missense mutation called ApoE Toyonaka (Ser197Cys). This case may confirm the independent responsibility of ApoE2/2 and ApoE Toyonaka for ApoE2 homozygote glomerulopathy and MN-like EDD findings, respectively.

The spectrum of type III hyperlipoproteinemia.

BACKGROUND: Type III hyperlipoproteinemia is a highly atherogenic dyslipoproteinemia characterized by hypercholesterolemia and hypertriglyceridemia due to markedly increased numbers of cholesterol-enriched chylomicron and very-low-density lipoprotein (VLDL) remnant lipoprotein particles. Type III can be distinguished from mixed hyperlipidemia based on a simple diagnostic algorithm, which involves total cholesterol, triglycerides, and apolipoprotein B (apoB). However, apoB is not measured routinely. OBJECTIVE: The objective of the present study was to determine if patients with type III could be distinguished from mixed hyperlipidemia based on lipoprotein lipids. METHODS: Classification was based first on total cholesterol and triglyceride and then on the apoB diagnostic algorithm using apoB plus total cholesterol plus triglycerides, and validated by sequential ultracentrifugation. Four hundred and forty normals, 637 patients with hypertriglyceridemia, and 714 with hypertriglyceridemia and hypercholesterolemia were studied. Plasma lipoproteins were separated by sequential ultracentrifugation and heparin-manganese precipitation. Cholesterol, triglyceride, and apoB were measured in plasma and isolated lipoprotein fractions. RESULTS: Of the 1351 patients with hypertriglyceridemia, 49 had type III hyperlipoproteinemia, as diagnosed by the apoB algorithm and validated by ultracentrifugation. Plasma triglycerides were higher in the type III subjects: 4.16 mmol/L (3.35-6.08, 25th-75th percentile), but there was considerable overlap with the hypertriglyceridemic subjects 2.65 mmol/L (1.91-4.20, 25th-75th percentile) and the combined hyperlipidemic subjects 3.02 mmol/L (2.07-5.32, 25th-75th percentile). Similarly, total cholesterol was 4.79 mmol/L (4.31-5.58, 25th-75th percentile) for type III vs 5.5 mmol/L (4.64-5.78, 25th-75th percentile) and 7.02 mmol/L (6.39-7.96, 25th-75th percentile), respectively. By contrast, as identified by the apoB algorithm, the VLDL-C/TG, VLDL-C/VLDL-TG, VLDL-C/VLDL apoB, and VLDL apoB/LDL apoB ratios were all higher in type III than in the other hypertriglyceridemic dyslipoproteinemias with the exception of type V as diagnosed by the apoB algorithm. CONCLUSION: Cholesterol and triglycerides cannot reliably distinguish type III hyperlipoproteinemia from mixed hyperlipidemia. Adding apoB and applying the apoB algorithm makes reliable diagnosis possible and easy. However, unless apoB is introduced into routine clinical care, type III hyperlipoproteinemia will often not be recognized. Given the cardiovascular risk associated with type III and its responsiveness to treatment, this should not be acceptable.

A Case of Type III Hyperlipoproteinemia Accompanied by Xanthoma Striatum Palmare / 대한피부과학회지

Xanthomas are localized lipid deposits within organs that may manifest as papules, plaques, or nodules in skin. They are commonly associated with all types of hyperlipidemia. Xanthoma striatum palmare characterized by xanthomas of the palmar creases is a rare but important diagnostic physical sign of dysbetalipoproteinemia, also known as type III hyperlipoproteinemia. Type III hyperlipoproteinemia is characterized by the early onset of cardiovascular disease and peripheral vascular disease. We describe herein the case of a 51-year-old female patient affected by xanthoma striatum palmare associated with elevated plasma levels of triglycerides and cholesterol and a lipoprotein electrophoresis pattern consistent with type III hyperlipoproteinemia.

Effect of adding bezafibrate to standard lipid-lowering therapy on post-fat load lipid levels in patients with familial dysbetalipoproteinemia. A randomized placebo-controlled crossover trial.

Familial dysbetalipoproteinemia (FD) is a genetic disorder associated with impaired postprandial lipid clearance. The effect of adding bezafibrate to standard lipid-lowering therapy on postprandial and fasting lipid levels in patients with FD is unknown. In this randomized placebo-controlled double-blind crossover trial, 15 patients with FD received bezafibrate and placebo for 6 weeks in randomized order in addition to standard lipid-lowering therapy (statin, ezetimibe, and/or lifestyle). We assessed post-fat load lipids, expressed as incremental area under the curve (iAUC) and area under the curve (AUC), as well as fasting levels and safety, and found that adding bezafibrate did not reduce post-fat load non-HDL-cholesterol (non-HDL-C) iAUC (1.78 ± 4.49 mmol·h/l vs. 1.03 ± 2.13 mmol·h/l, P = 0.57), but did reduce post-fat load triglyceride (TG) iAUC (8.05 ± 3.32 mmol·h/l vs. 10.61 ± 5.92 mmol·h/l, P = 0.03) and apoB (0.64 ± 0.62 g·h/l vs. 0.93 ± 0.71 g·h/l, P = 0.01). Furthermore, bezafibrate significantly improved AUC and fasting levels of non-HDL-C, TG, total cholesterol, HDL-C, and apoB. Bezafibrate was associated with lower estimated glomerular filtration rate (78.4 ± 11.4 ml/min/1.73 m2 vs. 86.1 ± 5.85 ml/min/1.73 m2, P = 0.002). In conclusion, in patients with FD, the addition of bezafibrate to standard lipid-lowering therapy resulted in improved post-fat load and fasting plasma lipids. Combination therapy of statin/fibrate could be considered as standard lipid-lowering treatment in FD.

Apolipoprotein E - A Multifunctional Protein with Implications in Various Pathologies as a Result of Its Structural Features.

Apolipoprotein E (apoE), a 34 kDa glycoprotein, mediates hepatic and extrahepatic uptake of plasma lipoproteins and cholesterol efflux from lipid-laden macrophages. In humans, three structural different apoE isoforms occur, with subsequent functional changes and pathological consequences. Here, we review data supporting the involvement of apoE structural domains and isoforms in normal and altered lipid metabolism, cardiovascular and neurodegenerative diseases, as well as stress-related pathological states. Studies using truncated apoE forms provided valuable information regarding the regions and residues responsible for its properties. ApoE3 renders protection against cardiovascular diseases by maintaining lipid homeostasis, while apoE2 is associated with dysbetalipoproteinemia. ApoE4 is a recognized risk factor for Alzheimer's disease, although the exact mechanism of the disease initiation and progression is not entirely elucidated. ApoE is also implicated in infections with herpes simplex type-1, hepatitis C and human immunodeficiency viruses. Interacting with both viral and host molecules, apoE isoforms differently interfere with the viral life cycle. ApoE exerts anti-inflammatory effects, switching macrophage phenotype from the proinflammatory M1 to the anti-inflammatory M2, suppressing CD4+ and CD8+ lymphocytes, and reducing IL-2 production. The anti-oxidative properties of apoE are isoform-dependent, modulating the levels of various molecules (Nrf2 target genes, metallothioneins, paraoxonase). Mimetic peptides were designed to exploit apoE beneficial properties. The "structure correctors" which convert apoE4 into apoE3-like molecules have pharmacological potential. Despite no successful strategy is yet available for apoE-related disorders, several promising candidates deserve further improvement and exploitation.

Possible involvement of PCSK9 overproduction in hyperlipoproteinemia associated with hepatocellular carcinoma: A case report.

Herein, we describe a 69-year-old Japanese man with massive type III hyperlipoproteinemia (total cholesterol, 855 mg/dL; triglyceride, 753 mg/dL) presenting as a paraneoplastic manifestation of hepatitis B virus-associated hepatocellular carcinoma. The messenger RNA expression of sterol regulatory element-binding protein-2 and proprotein convertase subtilisin/kexin 9 in the tumor tissue was increased by 13-fold and 4-fold, respectively, compared with the non-tumor tissue. Serum level of active form of PCSK9 was 382 ng/mL (reference range: 253 ± 79 ng/mL). The non-tumor tissue had extremely low expression of low-density lipoprotein receptor and low-density lipoprotein receptor-related protein 1. Together, we speculate that marked overexpression of sterol regulatory element-binding protein-2 in the tumor may stimulate the secretion of PCSK9, which inhibits the lipoprotein receptors in the non-tumor tissue, thereby causing paraneoplastic hyperlipoproteinemia.

Type III Hyperlipoproteinemia: Still Worth Considering?

Familial type III hyperlipoproteinemia (HLP) was first recognized as a distinct entity over 60 years ago. Since then, it has proven to be instructive in identifying the key role of apolipoprotein E (apoE) in removal of the remnants of very low density lipoproteins and chylomicrons produced by the action of lipoprotein lipase on these triglyceride-transporting lipoproteins. It has additionally shed light on the potent atherogenicity of the remnant lipoproteins. This review describes the history of development of our understanding of type III HLP, discusses the several genetic variants of apoE that play roles in the genesis of type III HLP, and describes the remarkable responsiveness of this fascinating disorder to lifestyle modification, especially carbohydrate restriction and calorie restriction, and, when required, the addition of pharmacotherapy.

apoE3[K146N/R147W] acts as a dominant negative apoE form that prevents remnant clearance and inhibits the biogenesis of HDL.

The K146N/R147W substitutions in apoE3 were described in patients with a dominant form of type III hyperlipoproteinemia. The effects of these mutations on the in vivo functions of apoE were studied by adenovirus-mediated gene transfer in different mouse models. Expression of the apoE3[K146N/R147W] mutant in apoE-deficient (apoE(-/-)) or apoA-I-deficient (apoA-I(-/-))×apoE(-/-) mice exacerbated the hypercholesterolemia and increased plasma apoE and triglyceride levels. In apoE(-/-) mice, the apoE3[K146N/R147W] mutant displaced apoA-I from the VLDL/LDL/HDL region and caused the accumulation of discoidal apoE-containing HDL. The WT apoE3 cleared the cholesterol of apoE(-/-) mice without induction of hypertriglyceridemia and promoted formation of spherical HDL. A unique property of the truncated apoE3[K146N/R147W]202 mutant, compared with similarly truncated apoE forms, is that it did not correct the hypercholesterolemia. The contribution of LPL and LCAT in the induction of the dyslipidemia was studied. Treatment of apoE(-/-) mice with apoE3[K146N/R147W] and LPL corrected the hypertriglyceridemia, but did not prevent the formation of discoidal HDL. Treatment with LCAT corrected hypertriglyceridemia and generated spherical HDL. The combined data indicate that the K146N/R147W substitutions convert the full-length and the truncated apoE3[K146N/R147W] mutant into a dominant negative ligand that prevents receptor-mediated remnant clearance, exacerbates the dyslipidemia, and inhibits the biogenesis of HDL.

Effect of eicosapentaenoic acid agent on aggravated hypertriglyceridemia during pregnancy.

Aggravated hypertriglyceridemia with a serum triglyceride of more than 1000 mg/dL is a risk of acute pancreatitis during pregnancy. However, there have been few reports on the administration of an eicosapentaenoic acid (EPA) agent for aggravated hypertriglyceridemia during pregnancy. A 29-year-old multiparous Japanese woman was transferred to our hospital at 29 + 0 weeks of gestation due to hypertriglyceridemia of 898 mg/dL. Because diet control was not enough, we decided to use an EPA agent, resulting in a reduction in triglyceride levels to 550 mg/dL. A male infant, weighing 2667 g, was born at 37 + 2 weeks transabdominally, and was complicated with respiratory distress syndrome. The final diagnosis was type III hyperlipoproteinemia with the apolipoprotein E3/2 phenotype and a broad ß-migrating lipoprotein on polyacrylamide gel electrophoresis of serum lipoproteins. In conclusion, an EPA agent may be a possible therapeutic approach for aggravated hypertriglyceridemia during pregnancy, although it may increase a risk of respiratory distress syndrome.

Glomerulopathy with homozygous apolipoprotein e2: a report of three cases and review of the literature.

Most cases of type III hyperlipoproteinemia are accounted for by apolipoprotein E2 (apoE2) homozygotes, a genetic mutation of apoE (Arg158Cys). Glomerulopathy with homozygous apoE2 is rare and characterized by marked foam cell infiltration in the glomerular capillaries and mesangium. Here, we report 3 cases of apoE2 homozygote glomerulopathy diagnosed by renal biopsy and DNA analysis. All 3 cases were middle-aged or elderly males complicated with diabetes for at least a decade. The kidney biopsies showed massive foam cell infiltration in the glomerular capillaries and expanded mesangium accompanied by histological findings of diabetic glomerulosclerosis. The lipid profiles showed type III hyperlipoproteinemia and phenotypic/genetic analyses revealed homozygosity of apoE2. Two of the cases showed nephrotic proteinuria and progressed to renal failure in 3 and 8 years after the diagnosis of kidney disease.

Type III hyperlipoproteinemia associated with generalized tuberoeruptive xanthomas / 대한임상병리학회지

A 61-year-old female patient presented with the type III hyperlipoproteinemia (HLP) in association with generalized eruptive and tuberous xanthomas. She had hypercholesterolemia and hypertriglyceridemia, and extensive coronary atherosclerosis. Further studies revealed a positive standing plasma test, abnormal beta-very low density lipoprotein (VLDL) on lipoprotein electrophoresis, markedly elevated very low density lipoprotein-cholesterol (VLDL-C) to plasma triglycerides (TG) ratio (0.86) and homozygosity for apolipoprotein E2. After about one year of therapy with lipid-lowering agents and diet restriction, a significant reduction of serum cholesterol and TG was observed and the yellowish orange discolorations of palmar creases disappeared from her palms.

A Case of Generalized Plane Xanthoma Associated with Multiple Myeloma and Hyperlipoproteinemia / 대한피부과학회지

Generalized plane xanthoma is a group of plane xanthomas that appear as yellow to yellow-brown flat patches or slightly elevated plaques with a wide-spread distribution. The disease is frequently associated with multiple myeloma or other reticulo-endothelial malignancies and monoclonal gammopathy with unknown significance, and when accompanied by these hematologic malignancies, normolipoproteinemia is invariably associated. We present a case of generalized plane xanthoma associated with multiple myeloma and type III hyperlipoproteinemia in a 48 year-old woman, and this is the first report in Korean literature.