Characterization of antioxidant/anti-inflammatory properties and apoA-I-containing subpopulations of HDL from family subjects with monogenic low HDL disorders (original) (raw)

Defective functionality of HDL particles in familial apoA-I deficiency: relevance of alterations in HDL lipidome and proteome

Journal of lipid research, 2014

Defective functionality of HDL particles in familial apolipoprotein A-I deficiency 2 To evaluate functional and compositional properties of high-density lipoprotein (HDL) in subjects from a kindred of genetic apolipoprotein (apo) A-I deficiency, two homozygotes and six heterozygotes, with a nonsense mutation at APOA1 codon -2, Q[-2]X, were recruited together with age-and sex-matched healthy controls (n=11). Homozygotes displayed undetectable plasma levels of apoA-I and reduced levels of HDL-cholesterol and apoC-III (5.4% and 42.6% of controls, respectively). Heterozygotes displayed low HDL-cholesterol (21±9 mg/dl), low apoA-I (79±24 mg/dl), normal low-density lipoprotein-cholesterol (132±25 mg/dl) and elevated triglyceride (130±45 mg/dl) levels. Cholesterol efflux capacity of ultracentrigufally-isolated HDL subpopulations was reduced (up to -25%, p<0.01, on a phospholipid basis) in heterozygotes vs. controls. Small, dense HDL3 and total HDL from heterozygotes exhibited diminished antioxidative activity (up to -48%, p<0.001 on a total mass basis) vs. controls. HDL subpopulations from both homozygotes and heterozygotes displayed altered chemical composition, with depletion in apoA-I, phospholipid and cholesteryl ester, enrichment in apoA-II, free cholesterol and triglyceride, and altered phosphosphingolipidome. The defective atheroprotective activities of HDL were correlated with altered lipid and apolipoprotein composition. These data reveal that atheroprotective activities of HDL particles are impaired in homozygous and heterozygous apoA-I deficiency and are intimately related to marked alterations in protein and lipid composition.

The influence of apoE-deficiency and LDL-receptor-deficiency on the HDL subpopulation profile in mice and in humans

Atherosclerosis, 2014

As apoE(-/-) and LDL-Receptor(-/-) mice are commonly used in atherosclerosis research; our objective was to point out the differences in HDL metabolism between mice and humans regarding the roles of apoE and LDLR. We examined HDL particles obtained from wild type (WT), LDLR(-/-), and apoE(-/-) mice, as well as from normal, homozygous familial hypercholesterolemic (FH), and apoE-deficient human subjects by 2-dimensional non-denaturing PAGE followed by immunoblot and image analysis. In WT mice, the majority of apoA-I was in large (9.0-12.0 nm), α-mobility HDL with trace amounts of apoA-I in small, preβ-1 HDL. In LDL(-/-) mice, both apoA-I- and apoE-containing HDL looked normal. About one-third of apoE was associated with large apoA-I-containing HDL (LpA-I:E) and two-thirds formed large HDL without apoA-I (LpE). In apoE(-/-) mice, apoA-I was detected in multiple, β-preβ-mobility, tightly-packed bands (7.0-13.0 nm) indicating that apoA-I in these animals was present only in poorly-lipidated, discoidal particles. Neither FH nor apoE-deficient humans showed significant alterations in apoA-I-containing HDL particles as compared to non-carriers. Our data indicate that apoE is necessary for the formation of spherical, lipidated HDL particles in mice, but not in humans, probably because mice lack CETP. Based on our data, we hypothesize that apoE(-/-) mice have little or no functional HDL, therefore results from apoE(-/-) mice cannot be extrapolated to humans without taking this significant difference into consideration.

Human Apolipoprotein A-II Enrichment Displaces Paraoxonase From HDL and Impairs Its Antioxidant Properties: A New Mechanism Linking HDL Protein Composition and Antiatherogenic Potential

Circulation Research, 2004

Apolipoprotein A-II (apoA-II), the second major high-density lipoprotein (HDL) apolipoprotein, has been linked to familial combined hyperlipidemia. Human apoA-II transgenic mice constitute an animal model for this proatherogenic disease. We studied the ability of human apoA-II transgenic mice HDL to protect against oxidative modification of apoB-containing lipoproteins. When challenged with an atherogenic diet, antigens related to low-density lipoprotein (LDL) oxidation were markedly increased in the aorta of 11.1 transgenic mice (high human apoA-II expressor). HDL from control mice and 11.1 transgenic mice were coincubated with autologous very LDL (VLDL) or LDL, or with human LDL under oxidative conditions. The degree of oxidative modification of apoB lipoproteins was then evaluated by measuring relative electrophoretic mobility, dichlorofluorescein fluorescence, 9-and 13hydroxyoctadecadienoic acid content, and conjugated diene kinetics. In all these different approaches, and in contrast to control mice, HDL from 11.1 transgenic mice failed to protect LDL from oxidative modification. A decreased content of apoA-I, paraoxonase (PON1), and platelet-activated factor acetyl-hydrolase activities was found in HDL of 11.1 transgenic mice. Liver gene expression of these HDL-associated proteins did not differ from that of control mice. In contrast, incubation of isolated human apoA-II with control mouse plasma at 37°C decreased PON1 activity and displaced the enzyme from HDL. Thus, overexpression of human apoA-II in mice impairs the ability of HDL to protect apoB-containing lipoproteins from oxidation. Further, the displacement of PON1 by apoA-II could explain in part why PON1 is mostly found in HDL particles with apoA-I and without apoA-II, as well as the poor antiatherogenic properties of apoA-II-rich HDL. (Circ Res. 2004;95:789-797.)

ApoE and apoC-III-defined HDL subtypes: a descriptive study of their lecithin cholesterol acyl transferase and cholesteryl ester transfer protein content and activity

Lipids in Health and Disease

Background: The functionality of high-density lipoproteins (HDL) is a better cardiovascular risk predictor than HDL concentrations. One of the key elements of HDL functionality is its apolipoprotein composition. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are enzymes involved in HDL-mediated reverse cholesterol transport. This study assessed the concentration and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans. Methods: Eighteen adults (ten women and eight men, mean age 55.6, BMI 26.9 Kg/m 2 , HbA1c 5.4%) were studied. HDL from each participant were isolated and divided into four subspecies containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E + C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E + C+). The concentration and enzymatic activity of LCAT and CETP were measured within each HDL subspecies using immunoenzymatic and fluorometric methods. Additionally, the size distribution of HDL in each apolipoprotein-defined fraction was determined using nondenaturing electrophoresis and anti-apoA-I western blotting. Results: HDL without apoE or apoC-III was the predominant HDL subtype. The size distribution of HDL was very similar in all the four apolipoprotein-defined subtypes. LCAT was most abundant in E-C-HDL (3.58 mg/mL, 59.6% of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8, 12.2 and 8.37% of plasma LCAT respectively for E + C-, E-C+ and E + C+). LCAT mass was lower in E + C-HDL relative to E-C-HDL, but LCAT activity was similar in both fractions, signaling a greater activity-to-mass ratio associated with the presence of apoE. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and concentrations of both E-C+ pre-beta HDL (r = − 0.55, P = 0.017) and E-C-alpha 1 HDL (r = − 0.49, P = 0.041). Conversely, there was a direct correlation between plasma CETP activity and concentrations of E-C+ alpha 1 HDL (r = 0.52, P = 0.025).

Recurrent mutations of the apolipoprotein AI gene in three kindreds with severe HDL deficiency

Atherosclerosis, 2003

Two siblings with high density lipoprotein (HDL) deficiency and no plasma apolipoprotein A-I (Apo A-I) were found to be homozygous for a cytosine deletion in exon 3 of Apo A-I gene (c.85 del C, Q5FsX11). This mutation causes a frameshift leading to a premature stop codon and abolishes the synthesis of Apo A-I. Although both siblings had corneal opacifications and planar xanthomas, only one of them had premature coronary artery disease, probably as the result of mildly elevated LDL levels. In two other unrelated subjects HDL deficiency was due to heterozygosity for a nucleotide substitution in exon 4 of Apo A-I gene (c.494 T/G, L141R). Both Apo A-I mutations were reported previously in an Italian kindred which included compound heterozygotes and simple heterozygotes. We investigated all carriers of these mutations in the three kindreds and in the one previously reported. Plasma Apo A-I and HDL-C levels were lower in the mutation carriers than in non-carrier family members. These levels, however, were lower in L141R carriers than in carriers of c.85 del C. Haplotype analysis performed using several polymorphisms suggested that both the c.85 del C and L141R are likely to be recurrent mutations. #

Distribution of ApoA-I-Containing HDL Subpopulations in Patients With Coronary Heart Disease

2010

High density lipoproteins (HDLs) and their subspecies play a role in the development of coronary heart disease (CHD). HDL subpopulations were measured by 2-dimensional nondenaturing gel electrophoresis in 79 male control subjects and 76 male CHD patients to test the hypothesis that greater differences in apolipoprotein (apo)A-I-containing HDL subpopulations would exist between these 2 groups than for traditional lipid levels. In CHD subjects, HDL cholesterol (HDL-C) was lower (Ϫ14%, PϽ0.001), whereas total cholesterol and the low density lipoprotein cholesterol/HDL-C ratio were higher (9% [PϽ0.05] and 21% [PϽ0.01], respectively) compared with control levels. No significant differences were found for low density lipoprotein cholesterol, triglyceride, and apoA-I levels. In CHD subjects, there were significantly (PϽ0.001) lower concentrations of the large lipoprotein (Lp)A-I ␣ 1 (Ϫ35%), pre-␣ 1 (Ϫ50%), pre-␣ 2 (Ϫ33%), and pre-␣ 3 (Ϫ31%) subpopulations, whereas the concentrations of the small LpA-I/A-II ␣ 3 particles were significantly (PϽ0.001) higher (20%). Because ␣ 1 was decreased more than HDL-C and plasma apoA-I concentrations in CHD subjects, the ratios of HDL-C to ␣ 1 and of apoA-I to ␣ 1 were significantly (PϽ0.001) higher by 36% and 57%, respectively, compared with control values. Subjects with low HDL-C levels (Յ35 mg/dL) have different distributions of apoA-I-containing HDL subpopulations than do subjects with normal HDL-C levels (Ͼ35 mg/dL). Therefore, we stratified participants according to HDL-C concentrations into low and normal groups. The differences in lipid levels between controls and HDL-C-matched cases substantially decreased; however, the significant differences in HDL subspecies remained. Our research findings support the concept that compared with control subjects, CHD patients not only have HDL deficiency but also have a major rearrangement in the HDL subpopulations with significantly lower ␣ 1 and pre-␣ 1-3 (LpA-I) and significantly higher ␣ 3 (LpA-I/A-II) particles. (Arterioscler Thromb

A complex phenotype in a child with familial HDL deficiency due to a novel frameshift mutation in APOA1 gene (apoA-I Guastalla )

Journal of Clinical Lipidology, 2015

BACKGROUND: We describe a kindred with high-density lipoprotein (HDL) deficiency due to APOA1 gene mutation in which comorbidities affected the phenotypic expression of the disorder. METHODS: An overweight boy with hypertriglyceridemia (HTG) and HDL deficiency (HDL cholesterol 0.39 mmol/L, apoA-I 40 mg/dL) was investigated. We sequenced the candidate genes for HTG (LPL, APOC2, APOA5, GPIHBP1, LMF1) and HDL deficiency (LCAT, ABCA1 and APOA1), analyzed HDL subpopulations, measured cholesterol efflux capacity (CEC) of sera and constructed a model of the mutant apoA-I. RESULTS: No mutations in HTG-related genes, ABCA1 and LCAT were found. APOA1 sequence showed that the proband, his mother and maternal grandfather were heterozygous of a novel frameshift mutation (c.546_547delGC), which generated a truncated protein (p.[L159Afs*20]) containing 177 amino acids with an abnormal C-terminal tail of 19 amino acids. Trace amounts of this protein were detectable in plasma. Mutation carriers had reduced levels of LpA-I, preb-HDL and large HDL and no detectable HDL-2 in their plasma; their sera had a reduced CEC specifically the ABCA1-mediated CEC. Metabolic syndrome in the proband explains the extremely low HDL cholesterol level (0.31 mmol/L), which was half of that found in the other carriers. The proband's mother and grandfather, both presenting low plasma low-density lipoprotein cholesterol, were carriers of the b-thalassemic trait, a condition known to be associated with a reduced low-density lipoprotein cholesterol and a reduced prevalence of cardiovascular disease. This trait might have delayed the development of atherosclerosis related to HDL deficiency.

Human Apolipoprotein A-II Enrichment Displaces Paraoxonase From HDL and Impairs Its Antioxidant Properties

Circulation Research, 2004

Apolipoprotein A-II (apoA-II), the second major high-density lipoprotein (HDL) apolipoprotein, has been linked to familial combined hyperlipidemia. Human apoA-II transgenic mice constitute an animal model for this proatherogenic disease. We studied the ability of human apoA-II transgenic mice HDL to protect against oxidative modification of apoB-containing lipoproteins. When challenged with an atherogenic diet, antigens related to low-density lipoprotein (LDL) oxidation were markedly increased in the aorta of 11.1 transgenic mice (high human apoA-II expressor). HDL from control mice and 11.1 transgenic mice were coincubated with autologous very LDL (VLDL) or LDL, or with human LDL under oxidative conditions. The degree of oxidative modification of apoB lipoproteins was then evaluated by measuring relative electrophoretic mobility, dichlorofluorescein fluorescence, 9- and 13-hydroxyoctadecadienoic acid content, and conjugated diene kinetics. In all these different approaches, and in ...

Increased Production of HDL ApoA-I in Homozygous Familial Defective ApoB-100

Arteriosclerosis, Thrombosis, and Vascular Biology, 2000

Familial defective apolipoprotein (apo) B-100 (FDB) is a frequent cause of hypercholesterolemia. Hypercholesterolemia in homozygous FDB is less severe than in homozygotes for familial hypercholesterolemia. Recently, we showed decreased low density lipoprotein (LDL) apoB-100 fractional catabolism and decreased production of LDL due to an enhanced removal of apoE-containing precursors in a patient with homozygous FDB. The effects of defective apoB-100 on high density lipoprotein (HDL) metabolism are unknown. We studied HDL apoA-I metabolism in this FDB patient and in 6 control subjects by using 2 H 3 -L-leucine as a tracer. ApoA-I levels were normal in all study subjects. However, the fractional catabolic rate and the production rate of apoA-I were increased, by 79% and 70%, respectively, in FDB; the fractional catabolic rate of apoA-I in FDB was 0.34 day Ϫ1 compared with 0.19Ϯ0.03 day Ϫ1 in normal controls. The production rate of apoA-I in FDB was 18.4 mg ⅐ kg Ϫ1 ⅐ d Ϫ1 compared with 10.8Ϯ2.3 mg ⅐ kg Ϫ1 ⅐ d Ϫ1 in controls. Thus, we have shown for the first time that defective apoB-100 may influence HDL kinetics. The increase in total HDL turnover might enhance reverse cholesterol transport and could contribute to the seemingly benign clinical course of FDB compared with that of familial hypercholesterolemia. (Arterioscler Thromb Vasc Biol. 2000;20:1796-1799.)