Oxidized VLDL induces less triglyceride accumulation in J774 macrophages than native VLDL due to an impaired extracellular lipolysis.

The present study examined the relative contributions of the different pathways by which oxidatively modified VLDL (oxVLDL) promotes the uptake and intracellular accumulation of lipids in J774 macrophages. VLDL was oxidized for a maximum of 4 hours, resulting in an increase in thiobarbituric acid-reactive substances and an increased electrophoretic mobility on agarose gel. The lipid composition of the relatively moderately oxidized VLDL samples did not differ significantly from that of nonoxidized VLDL samples.

Effect of macrophage-derived mouse ApoE, human ApoE3-Leiden, and human ApoE2 (Arg158-->Cys) on cholesterol levels and atherosclerosis in ApoE-deficient mice.

The effect of monocyte/macrophage-derived wild-type mouse apolipoprotein E (apoE), human apoE3-Leiden, and human apoE2 on serum cholesterol levels and the development of atherosclerosis in apoE-deficient (apoe-/-) mice was investigated by using bone marrow transplantation (BMT). At 4 weeks after BMT, murine apoe+/+ bone marrow reduced serum cholesterol levels by 87% in apoe-/- mice, whereas macrophage-derived human apoE3-Leiden and human apoE2 induced a maximal, transient reduction of 35% and 48%, respectively. At 4 months after BMT, atherosclerosis was 23-fold (P<0.

Hyperlipidemia of ApoE2(Arg(158)-Cys) and ApoE3-Leiden transgenic mice is modulated predominantly by LDL receptor expression.

To investigate the relative roles of the LDL receptor- and non-LDL receptor-mediated pathways in the clearance of apolipoprotein E (apoE) variants in vivo, we have generated apoE2(Arg(158)-Cys) (apoE2) and apoE3-Leiden transgenic mice deficient for the endogenous mouse Apoe and Ldl receptor genes (Apoe-/-.Ldlr-/- mice). Unexpectedly, on the Apoe-/-.

Apolipoprotein E participates in the regulation of very low density lipoprotein-triglyceride secretion by the liver.

ApoE-deficient mice on low fat diet show hepatic triglyceride accumulation and a reduced very low density lipoprotein (VLDL) triglyceride production rate. To establish the role of apoE in the regulation of hepatic VLDL production, the human APOE3 gene was introduced into apoE-deficient mice by cross-breeding with APOE3 transgenics (APOE3/apoe-/- mice) or by adenoviral transduction. APOE3 was expressed in the liver and, to a lesser extent, in brain, spleen, and lung of transgenic APOE3/apoe-/- mice similar to endogenous apoe.

An extrahepatic receptor-associated protein-sensitive mechanism is involved in the metabolism of triglyceride-rich lipoproteins.

We have used adenovirus-mediated gene transfer in mice to investigate low density lipoprotein receptor (LDLR) and LDLR-related protein (LRP)-independent mechanisms that control the metabolism of chylomicron and very low density lipoprotein (VLDL) remnants in vivo. Overexpression of receptor-associated protein (RAP) in mice that lack both LRP and LDLR (MX1cre(+)LRP(flox/flox)LDLR(-/-)) in their livers elicited a marked hypertriglyceridemia in addition to the pre-existing hypercholesterolemia in these animals, resulting in a shift in the distribution of plasma lipids from LDL-sized lipoproteins to large VLDL-sized particles. This dramatic increase in plasma lipids was not due to a RAP-mediated inhibition of a unknown hepatic high affinity binding site involved in lipoprotein metabolism, because no RAP binding could be detected in livers of MX1cre(+)LRP(flox/flox)LDLR(-/-) mice using both membrane binding studies and ligand blotting experiments.

Macrophage specific overexpression of the human macrophage scavenger receptor in transgenic mice, using a 180-kb yeast artificial chromosome, leads to enhanced foam cell formation of isolated peritoneal macrophages.

Macrophage scavenger receptors class A (MSR) are thought to play an important role in atherogenesis by mediating the unrestricted uptake of modified lipoproteins by macrophages in the vessel wall leading to foam cell formation. To investigate the in vivo role of the MSR in this process, a transgenic mouse model expressing both isoforms of the human MSR was generated. A 180-kb yeast artificial chromosome (YAC) containing the human MSR gene (MSR1) with 60- and 40-kb flanking sequence at the 5' and 3' end, respectively, was obtained by reducing the size of a 1050-kb YAC by homologous recombination.

Severe hyperlipidemia in apolipoprotein E2 homozygotes due to a combined effect of hyperinsulinemia and an SstI polymorphism.

More than 90% of patients with type III hyperlipoproteinemia are homozygous carriers of the apolipoprotein (apo) E*2 allele. The great majority of these apoE2(Arg158-->Cys) homozygotes in the general population, however, are normolipidemic. Apparently, expression of the hyperlipidemic state requires additional genetic and/or environmental factors, suggesting a multifactorial etiology.

Physical activity modulates the effect of a lipoprotein lipase mutation (D9N) on plasma lipids and lipoproteins.

We investigated interactions between a mutation (D9N) in the lipoprotein lipase (LPL) gene and physical activity, as well as other lifestyle factors, on lipid traits in a population-based sample of Dutch men and women (n = 379). We used questionnaire information to classify physical activity, alcohol consumption, and smoking habits, while overweight was defined as a body mass index (BMI) > 25 kg/m2. Non-fasting blood samples were used for the determination of lipid traits and the D9N genotype.

Increased clearance explains lower plasma levels of tissue-type plasminogen activator by estradiol: evidence for potently enhanced mannose receptor expression in mice.

Several clinical studies have demonstrated an inverse relationship between circulating levels of estrogen and tissue-type plasminogen activator (t-PA). The present study was designed to test the hypothesis that estrogens lower plasma levels of t-PA by increasing its clearance from the bloodstream. 17alpha-Ethinyl estradiol (EE) treatment resulted in a significant increase in the clearance rate of recombinant human t-PA in mice (0.

Scavenger receptor deficiency leads to more complex atherosclerotic lesions in APOE3Leiden transgenic mice.

Apolipoprotein (apo) E3Leiden is a dysfunctional apo E variant associated with familial dysbetalipoproteinemia in humans. Transgenic mice carrying the APOE3Leiden gene develop hyperlipidemia and are highly susceptible to diet-induced atherosclerosis. An early step in atherosclerosis is foam cell formation, which is thought to result from the unrestricted uptake of modified lipoproteins by macrophages.

Progression and regression of atherosclerosis in APOE3-Leiden transgenic mice: an immunohistochemical study.

Apolipoprotein E3-Leiden (APOE3-Leiden) transgenic mice develop hyperlipidemia and are highly susceptible to diet-induced atherosclerosis. We have studied the progression and regression of atherosclerosis using immunohistochemistry. Female transgenic mice were fed a moderate fat diet to study atherosclerosis over a longer time period.

Binding of beta-VLDL to heparan sulfate proteoglycans requires lipoprotein lipase, whereas ApoE only modulates binding affinity.

The binding of beta-VLDL to heparan sulfate proteoglycans (HSPG) has been reported to be stimulated by both apoE and lipoprotein lipase (LPL). In the present study we investigated the effect of the isoform and the amount of apoE per particle, as well as the role of LPL on the binding of beta-VLDL to HSPG. Therefore, we isolated beta-VLDL from transgenic mice, expressing either APOE*2(Arg158-->Cys) or APOE*3-Leiden (E2-VLDL and E3Leiden-VLDL, respectively), as well as from apoE-deficient mice containing no apoE at all (Enull-VLDL).

Reversal of hyperlipidaemia in apolipoprotein C1 transgenic mice by adenovirus-mediated gene delivery of the low-density-lipoprotein receptor, but not by the very-low-density-lipoprotein receptor.

We have shown previously that human apolipoprotein (apo)C1 transgenic mice exhibit hyperlipidaemia, due primarily to an impaired clearance of very-low-density lipoprotein (VLDL) particles from the circulation. In the absence of at least the low-density-lipoprotein receptor (LDLR), it was shown that APOC1 overexpression in transgenic mice inhibited the hepatic uptake of VLDL via the LDLR-related protein. In the present study, we have now examined the effect of apoC1 on the binding of lipoproteins to both the VLDL receptor (VLDLR) and the LDLR.

In LDL receptor-deficient mice, catabolism of remnant lipoproteins requires a high level of apoE but is inhibited by excess apoE.

To investigate the quantitative requirement for apolipoprotein (apo) E in the clearance of lipoproteins via the non-low density lipoprotein (LDL) receptor mediated pathway, human APOE was overexpressed at various levels in the livers of mice deficient for both the endogenous Apoe and Ldlr genes (Apoe -/-. Ldlr -/-) using adenovirus-mediated gene transfer. We found that a low level of APOE expression, that was capable of reducing the hyperlipidemia in Apoe -/- mice, did not result in a reduction of the hyperlipidemia in Apoe -/-.

Atherosclerosis in APOE*3-Leiden transgenic mice: from proliferative to atheromatous stage.

Background: This study documents (1) the progression of atherosclerosis along the entire arterial tree in APOE*3-Leiden mice after 1, 4, 6, 9, and 12 months of a high-fat/high-cholesterol (HFC) diet and (2) the amount and phenotype of DNA-synthesizing and apoptotic cells in different lesion types after 6 months of HFC diet.

Methods And Results: Diet duration was correlated with a craniocaudal progression of lesion development and with an increase in severity of the lesion. Typically, the lesions contained smooth muscle cells, macrophages, and T lymphocytes and were covered by an intact endothelium.

Effects of fenofibrate on hyperlipidemia and postprandial triglyceride metabolism in human apolipoprotein C1 transgenic mice.

To study the in vivo role of apolipoprotein (apo) C1 in lipoprotein metabolism, we have generated transgenic mice expressing the human apo C1 gene. Apo C1 is a small 6.6 kDa protein that is primarily synthesized by the liver and is present on chylomicrons, very low density lipoproteins (VLDL) and high density lipoproteins (HDL).

Increased risk for endogenous hypertriglyceridaemia is associated with an apolipoprotein C3 haplotype specified by the SstI polymorphism.

Background: Hypertriglyceridaemia is a common metabolic disorder frequently found in patients with coronary heart disease. Numerous studies have revealed an association between the SstI polymorphism in the APOC3 gene and increased plasma apoC3 and triglyceride levels. In addition, two different variants within the promoter region have been recently suggested to be the mutations of the APOC3 gene leading to hypertriglyceridaemia.

Reduced levels of cholesterol, phospholipids, and fatty acids in cerebrospinal fluid of Alzheimer disease patients are not related to apolipoprotein E4.

Apolipoprotein E4 (apoE4) has been identified as a major risk factor for Alzheimer disease (AD). Previously it has been reported that levels of apoE are reduced in cerebrospinal fluid (CSF) of AD patients. Because it is known that apoE4 affects plasma lipid metabolism, we examined whether the presence of apoE4 might correlate with an altered lipid metabolism in the CSF of control subjects and AD patients.

Association between apolipoprotein E epsilon4 and the rate of cognitive decline in community-dwelling elderly individuals with and without dementia.

Objective: To determine whether the apolipoprotein E epsilon4 allele (apoE epsilon4) is associated with cognitive decline in individuals with and without dementia, we conducted a 4-year longitudinal study of subjects with a range of cognitive function.

Setting: At baseline, respondents (n=511) were randomly selected according to age and Mini-Mental State Examination score from a community-based study of dementia among noninstitutionalized persons aged 65 to 84 years. Respondents were examined at baseline and followed up in 3 annual visits.

Apolipoprotein E genotype, atherosclerosis, and cognitive decline: the Rotterdam Study.

The apolipoprotein E4 allele (APOE epsilon 4) and atherosclerosis are risk factors for cognitive decline. We investigated whether the effects of APOE epsilon 4 and atherosclerosis on cognitive decline are independent. A population-based follow-up study was performed on 838 subjects who were non-demented at baseline.

Gender-related association between the -93T-->G/D9N haplotype of the lipoprotein lipase gene and elevated lipid levels in familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) is a frequent cause of premature coronary artery disease. Affected family members are characterized by different combinations of elevated cholesterol and/or triglyceride levels. A reduction in lipoprotein lipase (LPL) activity has been observed in a subgroup of FCHL patients.

Serum apolipoprotein E level is not increased in Alzheimer's disease: the Rotterdam study.

The APOE*4 allele of the apolipoprotein E gene (APOE) is an important risk factor for Alzheimer's disease. It has been suggested that levels of apolipoprotein E (apoE) in plasma are increased in Alzheimer's disease. In this population-based study, we found that serum apoE levels were lower in Alzheimer patients compared to non-demented controls (0.

Adenovirus mediated overexpression of human phospholipid transfer protein alters plasma HDL levels in mice.

To study the function of plasma phospholipid transfer protein (PLTP) in vivo, a liver directed adenoviral gene transfer system was used to overexpress human PLTP in mice. For the experiments, two strains of mice, wild type (C57/B1) and mice transgenic for the human apoA-I gene (HuApoA-ITg), were utilized. Five days after injection of the recombinant PLTP adenovirus, wild type mice showed a 4-fold increase in serum PLTP activity in (12.

Effects of dietary fish oil on serum lipids and VLDL kinetics in hyperlipidemic apolipoprotein E*3-Leiden transgenic mice.

Studying the effects of dietary fish oil on VLDL metabolism in humans is subject to both large intra- and interindividual variability. In the present study we therefore used hyperlipidemic apolipoprotein (APO) E*3-Leiden mice, which have impaired chylomicron and very low density lipoprotein (VLDL) remnant metabolism, to study the effects of dietary fish oil on serum lipids and VLDL kinetics under highly standardized conditions. For this, female APOE*3-Leiden mice were fed a fat- and cholesterol-containing diet supplemented with either 0, 3 or 6% w/w (i.