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PubMed1994

Metabolism of chylomicron phosphatidylinositol in the rat: fate in vivo and hydrolysis with lipoprotein lipase and hepatic lipase in vitro.

Phosphatidylinositol (PI), mainly stearoyl-arachidonyl PI, occurs as a minor phospholipid constituent in both chyle and plasma lipoproteins. The kinetics and the pathway by which plasma and chyle PI is metabolized have not been investigated. The role of lipoprotein PI in the supply of arachidonic acid (20:4) and inositol lipid components to different tissues is thus unknown. In this study we examined the fate of chyle PI in vivo and its hydrolysis by lipoprotein lipase (LPL), hepatic lipase (HL), and postheparin plasma in vitro. Chyle and chylomicrons were labeled in the PI portion by feeding [3H]myo-inositol and in the phosphatidylcholine (PC) portion by feeding [14C]choline in a linoleate-rich fat meal (Intralipid) to mesenteric duct-cannulated rats. After intravenous injection of doubly labeled chyle into normal rats, [3H]PI disappeared from plasma at a slower rate than [14C]PC; after 60 min 41.6 +/- 2.7% 3H and 24.3 +/- 1.8% 14C (means +/- SEM, n = 4, P < 0.01) remained in plasma lipids. About 15% of both isotopes were in liver lipids after 60 min. Previous injection of a blocking antiserum against rat HL did not significantly influence the serum and liver radioactivity after 60 min. Radioactive PI was rapidly transferred to high density lipoproteins (HDL) during the metabolism of chylomicrons. Analysis of 3H and 14C in different molecular species of PI and PC in chyle and in serum indicated that there was no significant difference in disappearance rates between various species, stearoyl-arachidonyl PI thus disappearing at the same rate as total [3H]PI. Both lipoprotein lipase (LPL) and HL catalyzed formation of lyso-PI in vitro, the rate being increased by the addition of serum. About 60% of the lyso-PI formation catalyzed by postheparin plasma in 60 min could be blocked by antiserum to HL, which almost completely blocked the hydrolysis occurring after the first 10 min. The study thus shows that both LPL and HL hydrolyze chylomicron PI in vitro. LPL and HL may, however, be of limited importance for the clearance of chyle PI in vivo, most of the chylomicron PI being transferred to HDL, and thereafter eliminated from plasma at a slow rate mainly by other mechanisms.

Animals↗

PubMed1977

Lipoprotein lipase and uptake of triacylglycerol, cholesterol and phosphatidylcholine from chylomicrons by mammary and adipose tissue of lactating rats in vivo.

The relationship between lipoprotein lipase activity and uptake of triacylglycerol, cholesterol and phosphatidylcholine from chylomicrons was studied in mammary gland and adipose tissue of rats lactating 6--7 days. 60% of triacylglycerol [14C]oleic acid, 13% of [3H]cholesterol and 8% of [32P]phosphatidylcholine in chylomicrons injected intravenously were taken up within 11 min by mammary gland whereas negligible amounts were taken up by adipose tissue. Non-suckling for 44 h decreased markedly uptake of all lipids by mammary gland and retarded clearance of chylomicrons from blood, while it increased significantly uptake of triacylglycerol fatty acids and cholesterol by adipose tissue. Non-suckling also decreased lipoprotein lipase activity in mammary gland from 7.7 to 0.4 units/g, while it increased activity in adipose tissue from 0.1 to 2.7 units/g. These findings indicate that lipoprotein lipase is involved in uptake of chylomicron triacyglycerol and cholesterol by mammary gland and adipose tissue, and also in uptake of chylomicron phosphatidylcholine by mammary gland. They also show that reciprocal changes in lipoprotein lipase activity in mammary gland and adipose tissue, as occur during lactation, result in diversion of chylomicron lipids from one tissue to the other.

Adipose Tissue↗

PubMed2004

Induction of lipoprotein lipase gene expression in Chlamydia pneumoniae-infected macrophages is dependent on Ca2+ signaling events.

Unregulated uptake of low density lipoprotein (LDL) in macrophages is the hallmark of early atherogenic lesions, and Chlamydia pneumoniae infection of macrophages induces this process by an unknown mechanism. It was therefore aimed in this study to investigate (i) the role of C. pneumoniae in macrophage expression of the lipoprotein lipase (LpL) gene, (ii) the probable role of Ca2+ influx signals and (iii) the effect of the process on LDL uptake. Lipoprotein lipase mRNA expression and LpL activity in infected RAW-264.7 cells were significantly upregulated. A biphasic Ca2+ influx signal was observed in infected cells with a moderate influx (303 nM Ca2+) favoring optimal LpL gene expression. Also, the antagonists of L-type Ca2+ channel in macrophages significantly down-regulated LpL gene expression and the biomolecular content of C. pneumoniae responsible for the observed events was in part found to be Chlamydia lipopolysaccharide (cLPS). Investigations aimed at determining the specific relevance of Ca(2+)-dependent lipoprotein lipase gene expression in C. pneumoniae-infected macrophages showed that the condition caused enhanced uptake of LDL which was abrogated by Calphostin-C-mediated down-regulation of LpL. This discovery of a specialized Ca2+ influx signal-mediated LpL upregulation in C. pneumoniae-infected macrophages provides a mechanistic insight into early events involving C. pneumoniae in macrophage foam cell formation resulting from LDL uptake.

Animals↗

PubMed1997

Variation at the lipoprotein lipase and apolipoprotein AI-CIII gene loci are associated with fasting lipid and lipoprotein traits in a population sample from Iceland: interaction between genotype, gender, and smoking status.

The effects of polymorphisms in the lipoprotein lipase (LPL) gene (HindIII and S447X) and in the apolipoprotein (apo) AI-CIII gene cluster (G75A and C1100T) on levels of fasting plasma triglycerides, apoCIII, high density lipoprotein cholesterol (HDL-C), and apoAI were examined in 315 healthy men and women from Iceland. Non-smoking and smoking men and women were examined separately because of the strong effects of smoking status and gender on lipoproteins. For the LPL gene, there were no significant associations between plasma traits and genotypes of the S447X polymorphism, but the LPL-HindIII polymorphism was associated with significant effects on levels of all traits, with the effect of genotype on triglycerides and apoAI being modulated by smoking status, (genotype x smoking interaction, P < .02). The H- allele was generally associated with slightly lower levels of apoCIII, with a lowering effect on triglycerides only in smokers and with a raising effect on ApoAI in non-smoking and smoking men and in non-smoking women. For the apoCIII C1100T polymorphism, smoking and non-smoking men with one or more T alleles had levels of triglycerides roughly 10% higher than those with only the C allele; in contrast, the women with the T allele had lower levels of triglycerides (15.7% lower in non-smokers, P = .04; gender x genotype interaction, P = .02). In males and females and in smokers and non-smokers, the T allele was associated with levels of apoCIII that were 9-20% higher than those with only the C allele (P = .004 overall). In the non-smoking men, nonlinear additive effects were observed with combinations of genotypes at the LPL and apoAI-CIII loci, with the HDL-C and apoAI raising effect associated with the A75 allele and H- allele seen only in those men with both alleles, and the apoCIII raising effect associated with the H+ and T alleles seen only in those with both alleles. Thus, variations at both of the LPL and apoAI-apoCIII loci influence levels of triglycerides, apoCIII, HDL-C, and apoAI, but these effects are strongly modulated by smoking and are different between men and women. The mechanisms for these interactions between smoking or gender and genes are unknown, but future studies should take such interactions into account.

Adolescent↗

PubMed1998

Effects of heterozygous lipoprotein lipase deficiency on diet-induced atherosclerosis in mice.

Heterozygous lipoprotein lipase deficiency (LPL+/-) is common and has been implicated in premature atherosclerosis in epidemiologic studies. However, in vitro data suggest that LPL deficiency in the vascular wall may be antiatherogenic. To address the role of LPL in atherosclerosis, LPL+/- mice in the C57BL/6J background were fed an atherogenic diet for 8 months. LPL+/- mice were more dyslipidemic than +/+ animals due to increased concentrations of non-HDL lipoproteins. There was no difference in aortic origin atherosclerosis between LPL+/- (n=56) and +/+ (n=55) mice. LPL+/- mice in the low density lipoprotein receptor knockout (LDLR-/-) background were fed the same atherogenic diet for 3 months. LPL+/-LDLR-/- mice were more dyslipidemic than LPL+/+LDLR-/- animals. There was no difference in atherosclerosis assayed for the entire aorta and no difference in aortic sterol content between LPL+/-LDLR-/- (n=28) and LPL+/+LDLR-/- (n=15) mice. LPL protein was detected in murine lesions in a consistent layered pattern. More luminal, lipid-laden macrophages generally did not stain for LPL, but deeper, lipid-poor macrophages as well as necrotic core regions contained immunoreactive LPL. LPL protein was more abundant in lesions from LPL+/+ LDLR-/- than LPL+/-LDLR-/- mice. After eating an atherogenic diet, LPL+/- as compared to LPL+/+ mice have more dyslipidemia, but no more atherosclerosis, and less LPL protein in atherosclerotic lesions. These data suggest that lipoprotein lipase deficiency in the vascular wall could prevent the retention of atherogenic lipoproteins.

Animals↗

PubMed1996

ApoE enhances lipid uptake by macrophages in lipoprotein lipase deficiency during pregnancy.

A woman with primary lipoprotein lipase (LPL) deficiency developed marked hypertriglyceridemia, pancreatitis, eruptive xanthomas, and unusual palmar xanthomas during pregnancy. Hypotheses to account for the palmar xanthomas were that oxidative modification of triglyceride (TG)-rich lipoproteins occurred due to increased plasma residence time, or that their apolipoprotein E (apoE) content was abnormally elevated. Indices of oxidation of her TG-rich lipoproteins did not support the hypothesis that oxidative changes were a causative factor for her xanthomata. However, degradation of her TG-rich lipoproteins by macrophages was markedly increased (1844 ng/mg protein) during pregnancy as compared to hypertriglyceridemic (with normal LPL) and normotriglyceridemic controls (352 and 126 ng/mg protein, respectively). Post pregnancy the degradation of the subject's TG-rich lipoproteins fell to 289 ng/mg protein. Compositional analysis showed significant enrichment of the particles with apoE (0.97 mass ratio of apoE:apoB during pregnancy, in contrast to 0.38 for normolipidemic controls), and was correlated with the rate of degradation of the TG-rich lipoproteins. Thus, the increased uptake of the TG-rich lipoproteins by macrophages appears to be the result of an unusual enrichment of these lipoproteins with apoE.

Adult↗

PubMed1979

Lipoprotein lipase of cultured mesenchymal rat heart cells. IV. Modulation of enzyme activity by VLDL added to the culture medium.

Lipoprotein lipase activity was studied in rat heart cell cultures grown in the presence of 20% fetal calf and horse serum and a medium concentration of triacylglycerol of 0.03 mg/ml. After 6--8 days, when the enzyme activity had reached high levels, the cells were incubated for 24 h in a medium containing 20% serum derived from fasted or fed rats. No change in enzyme activity occurred in the presence of fasted rat serum, but a 50% fall was observed with fed rat serium. When the complete culture medium was supplemented with rat plasma VLDL (0.075--0.75 mg triacylglycerol) a pronounced decrease in lipoprotein lipase activity occurred after 3--5 h of incubation. Similar extent of enzyme fall was observed also in the presence of triacylglycerol-rich lipoproteins isolated from rat plasma after feeding of safflower oil or lard, even though the fatty acid composition of the triacylgylcerol varied markedly. As the addition of VLDL to the culture medium resulted in a lesser fall of heparin releasable than residual activity it seems that there was no direct inhibition of surface bound enzyme activity and that the transport of the enzyme to the cell surface was not affected. These data indicate that addition of VLDL to the culture medium resulted in a fall in enzyme synthesis, while total protein synthesis as determined by incorporation of [3H]leucine, remained unchanged. This inhibition could be reproduced by increasing free fatty acid concentration of the medium, however addition of excess albumin to VLDL-containing medium did not prevent the fall in enzyme activity. The present results obtained with cultured rat hearts cells suggest that in vivo plasma levels of triacylglycerol-rich lipoproteins could modulate the lipoproteins could modulate the lipoprotein lipase activity of the heart.

Animals↗

PubMed1986

Muscle lipoprotein lipase activity in voluntarily exercising rats.

Voluntary exercise of rats in freely rotating work wheels has been extensively used, but muscle adaptations that result from such exercise training are poorly documented. The purpose of this study was to determine whether the exercise performed by voluntarily active rats would increase succinate dehydrogenase or lipoprotein lipase activities in the soleus muscle (SM) or the red portion of the vastus lateralis muscle (RV). In SM the activities of these two enzymes were not increased after 7 or 16 wk of voluntary exercise. Succinate dehydrogenase activity in RV was moderately increased after 7 and 16 wk of voluntary activity (P less than 0.05). Substantial increases occurred in RV lipoprotein lipase activity (P less than 0.01). The increase in RV lipoprotein lipase activity was positively related to distance run by the rats. The results indicate that only small muscle-dependent increases in mitochondrial enzymes occur in rats allowed to exercise voluntarily in rodent work wheels. Voluntary exercise training induced a selective increase in lipoprotein lipase activity in a muscle containing a high percentage of fast-twitch red fibers, a response absent in a muscle containing a predominance of slow-twitch red fibers. It is unlikely that this differential response can be explained by exercise-induced changes in plasma hormone concentrations involved in the regulation of lipoprotein lipase.

Animals↗

PubMed1994

Hormone-sensitive lipase is closely related to several bacterial proteins, and distantly related to acetylcholinesterase and lipoprotein lipase: identification of a superfamily of esterases and lipases.

We have sequenced a gene from Bacillus acidocaldarius which encodes an open reading frame (ORF3) of 310 amino acids. The ORF3 was found to be related to the mammalian hormone-sensitive lipase (HSL). Searching the protein data base revealed five other bacterial proteins related to the HSL. Upon further sequence comparisons this HSL-group was found to be related to the family of carboxylesterases, and to a family of lipases (lipoprotein, hepatic and pancreatic lipases). The evolutionary relationship of these serine-dependent hydrolytic enzymes has not been studied previously, and it has not been known that these proteins belong to the same superfamily. Finally, the alignment of the HSL with the bacterial proteins allowed us to infer the location of the hormone-sensitive regulatory domain of the HSL-protein.

Acetylcholinesterase↗

PubMedDate not supplied

Uptake of lipids by developing oocytes of the hawkmoth Manduca sexta. The possible role of lipoprotein lipase.

A plasma membrane preparation of Manduca sexta ovarian follicles was shown to contain lipoprotein lipase activity that hydrolyzes the diacylglycerol moiety of the hemolymph lipoprotein, lipophorin. Kinetic analysis demonstrated that low density lipophorin (LDLp) is a better substrate for the identified lipase activity than high density lipophorin (HDLp). The activity has a pH optimum of 9-9.5 and is partially inhibited by NaCl concentrations higher than 0.5 M. Diisopropylfluorophosphate (DFP) inhibits the membrane bound lipoprotein lipase activity completely and irreversibly. Incubation of follicle plasma membranes with [3H]-DFP radiolabels a 100-kDa membrane protein that may represent the lipoprotein lipase. The present results suggest that lipoprotein lipase activity may play an important role in the uptake of lipids by M. sexta oocytes.

Animals↗

PubMed1994

Effects of alcohol on lipoprotein lipase, hepatic lipase, cholesteryl ester transfer protein, and lecithin:cholesterol acyltransferase in high-density lipoprotein cholesterol elevation.

The mechanism whereby alcohol increases high-density lipoprotein cholesterol (HDL-C) levels is unclear. Lipoprotein lipase (LPL), hepatic lipase (HL), cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyltransferase (LCAT) act on lipoprotein metabolism. The purpose of the present study is to determine which one or what combination of these factors is responsible for the rise in HDL-C levels following alcohol ingestion. After 3 weeks of abstinence, 12 men consumed 0.5 g/kg bw of alcohol per day for 4 weeks; 13 abstaining men served as controls. Mean plasma total cholesterol (TC) levels were unchanged in either group throughout the study. Among the alcohol consumers, plasma triglycerides (TG), HDL-C, apolipoprotein (apo) A-I and A-II levels increased significantly after 3 weeks of alcohol loading but were unchanged in the control group. High-density lipoprotein3 cholesterol (HDL3-C) levels increased significantly in the alcohol consumers after 4 weeks of alcohol loading whereas high-density lipoprotein2 cholesterol (HDL2-C) levels were unaffected. In the controls, neither HDL2-C nor HDL3-C changed significantly. Post-heparin plasma (PHP) LPL activity and mass increased significantly (P < 0.01) after the alcohol ingestion (controls remained unchanged) without changing LPL specific activity. HL, CETP and LCAT activities were unaffected in both groups. We conclude that of the factors considered, LPL contributed the most to the alcohol-induced rise in HDL-C.

Adult↗

PubMed1984

Acute increase in lipoprotein lipase following prolonged exercise.

We investigated the acute effects of prolonged exercise on lipoprotein metabolism. Serum lipid and lipoprotein concentrations and plasma postheparin lipolytic activity were measured in ten well-trained men (ages 21 to 39) the day before and after a 42 km foot race. LDL cholesterol decreased by 10% (113 +/- 31 to 103 +/- 32 mg/dL, P less than 0.01) and total HDL-cholesterol levels increased by 9% (65 +/- 18 to 71 +/- 19 mg/dL, P less than 0.01) the day after the race. No changes in the concentration of apolipoprotein A-I or A-II occurred. Triglyceride levels decreased by 39% (95 +/- 38 to 58 +/- 23 mg/dL, P less than 0.001). Two days after the race, total HDL cholesterol (74 +/- 21 mg/dL, P less than 0.05) and the HDL2 subfraction (37 +/- 19 mg/dL, P less than 0.05) remained significantly elevated compared to pre-race values. Most dramatically, the level of lipoprotein lipase activity measured in postheparin plasma nearly doubled after the race, demonstrating that vigorous exercise acutely increases this enzyme activity. The increase in lipoprotein lipase activity probably mediated the fall in serum triglycerides after exercise and may also account for the increase in HDL cholesterol.

Adult↗

PubMed1993

Lipid content and lipoprotein lipase activity in skeletal muscle of lactating and weaned rats.

The aim of the investigation was to study the changes in lipid content and lipoprotein lipase (LPL) activity of skeletal muscle of lactating and weaned rats, in order to gain insight on the role of skeletal muscle in the metabolism of triacylglycerols not used by the mammary gland after weaning. Sprague-Dawley rats fed ad libitum were killed 0, 8, 12, and 24 h after litter separation on the 14th day of lactation. Electron microscopy, as well as determinations of the total fat and phospholipid content were performed on muscles of the right hind limb. Lipoprotein lipase activity was determined in extracts of acetone powder of skeletal muscle, mammary gland, and adipose tissue using dibutyryl fluorescine as substrate. Fat droplets were identified in the muscle interfiber spaces of weaning rats. Muscle total fat and phospholipids were higher in weaned than in lactating rats. After litter separation, lipoprotein lipase activity increased significantly in muscle and in adipose tissue (fourfold), while activity in the mammary gland decreased. The increased muscle lipoprotein lipase activity in the weaned rats seems to be associated with the higher content of fat and with the presence of fat droplets.

Adipose Tissue↗

PubMed2002

Lipoprotein lipase: genetics, lipid uptake, and regulation.

Lipoprotein lipase (LPL) regulates the plasma levels of triglyceride and HDL. Three aspects are reviewed. 1) Clinical implications of human LPL gene variations: common mutations and their effects on plasma lipids and coronary heart disease are discussed. 2) LPL actions in the nervous system, liver, and heart: the discussion focuses on LPL and tissue lipid uptake. 3) LPL gene regulation: the LPL promoter and its regulatory elements are described.

Chylomicrons↗

PubMed2001

Decreased activities of lipoprotein lipase and hepatic triglyceride lipase in patients with gout.

Postheparin plasma lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) activities were measured in 30 male primary gout patients as well as in control subjects. The activities of these lipolytic enzymes were significantly decreased in the patients as compared with the controls (gout v control; LPL, 5.4 +/- 0.4 v 7.9 +/- 0.9 U; HTGL, 14.6 +/- 2.0 v 17.9 +/- 3.4 U) when matched with serum triglyceride concentration. Further, LPL activity was negatively correlated with serum- and very-low-density lipoprotein (VLDL)-triglyceride in gout patients, while that of HTGL was negatively correlated with low-density lipoprotein (LDL)-triglyceride in both gout patients and control subjects. These results suggest that decreased activities of LPL and HTGL may contribute, in part, to the increased concentrations of serum-, VLDL-, and LDL-triglyceride seen in gout patients, leading to a higher risk for coronary atherosclerotic diseases in gout.

Adult↗

PubMed1991

Transcriptional regulation of the human lipoprotein lipase gene in 3T3-L1 adipocytes.

Lipoprotein lipase (LPL), a key enzyme in normal lipoprotein metabolism, has a complex pattern of regulation and tissue-specific expression. Several potential binding sites for transcription factors, including the recognition sequences for CCAAT/enhancer-binding protein and octamer-binding proteins (Oct) have been described in the 5'-flanking region of the human LPL gene. To identify elements which regulate the expression of LPL in adipocytes, plasmids containing deletion mutants of the 5'-LPL promoter region and the luciferase reporter gene were transfected in 3T3-L1 adipocytes. Deletions at -724, -565, -461, -368, -232, -167, -92, -35, and -17 relative to the transcriptional start site modified transcription from 100 to 162, 194, 185, 128, 63, 53, 29, and 0%, respectively, indicating the presence of negative (-724 to -565) and positive (-368 to -35) cis-acting regulatory elements. Transfection of HepG2 cells, which do not synthesize LPL, with the same constructs resulted in a similar pattern of expression for the majority of the deletions. However, deletions between -724 and -368 base pairs resulted in a 75-100% increase in transcription in 3T3 adipocytes but not in HepG2 cells, indicating the presence of tissue-specific regulatory element(s) in this region. An important regulatory element affecting LPL transcription in adipocytes was identified by gel mobility shift assays and DNase I footprint analysis. Using these techniques, a nuclear protein(s) in 3T3-L1 adipocytes was shown to bind specifically to a fragment which included the proximal octamer recognition site (from -46 to -39) present in the LPL promoter. The DNA-protein complex comigrates with an electrophoretic band containing the Oct-1-DNA complex in BJA-B nuclear extracts and the DNA-protein complex was selectively competed only by DNA fragments containing the octamer sequence. Preincubation of 3T3-L1 nuclear extracts with an antibody directed against the POU domain of Oct-1 inhibited the formation of the DNA-protein complex. Deletion of the proximal octanucleotide motif from the plasmid containing the -461 fragment of the LPL promoter, resulted in a 79 and 76% decrease in the level of expression in transfected 3T3-L1 adipocytes and HepG2 hepatocytes, respectively. These combined results have established that the expression of LPL in adipocytes is modulated by multiple positive and negative regulatory elements within the 5'-flanking region of the LPL gene. A proximal octamer binding sequence which specifically interacts with a nuclear protein(s) that exhibits the characteristics of Oct-1 has been identified.(ABSTRACT TRUNCATED AT 400 WORDS)

3T3 Cells↗

PubMed1987

An enzyme-linked immunoassay for lipoprotein lipase.

Polyclonal antibodies against bovine milk lipoprotein lipase (LPL) were used to generate an enzyme-linked immunosorbent assay (ELISA) for rat LPL. The antibodies to LPL were affinity purified on bovine LPL columns and were shown to be specific for LPL by immunoprecipitation and enzyme inhibition. The solid-phase ELISA was sensitive from 1.0 to 20 ng/ml of LPL and paralleled enzyme activity. Denatured rat LPL showed the same LPL mass as undenatured samples, allowing LPL mass to be quantitated effectively in a variety of rat tissue extracts.

Adipose Tissue↗

PubMed1999

Overexpressed lipoprotein lipase protects against atherosclerosis in apolipoprotein E knockout mice.

Lipoprotein lipase (LPL) is known to play a crucial role in lipoprotein metabolism by hydrolyzing triglycerides; however its role in atherogenesis has yet to be determined. We have previously shown that low density lipoprotein receptor knockout mice overexpressing LPL are resistant to diet-induced atherosclerosis due to the suppression of remnant lipoproteins. Plasma lipoproteins and atherosclerosis of apolipoprotein (apo) E knockout mice which overexpress the human LPL transgene (LPL/APOEKO) were compared with those of control apoE knockout mice (APOEKO). On a normal chow diet, LPL/APOEKO mice showed marked suppression of the plasma triglyceride levels compared with APOEKO mice (54 vs. 182 mg/dl), but no significant changes in plasma cholesterol and apoB levels. Non-high density lipoproteins (HDL) from LPL/APOEKO mice had lower triglyceride content, a smaller size, and a more positive charge compared with those from APOEKO mice. Cholesterol, apoA-I, and apoA-IV were increased in HDL. Although both groups developed hypercholesterolemia to a comparable degree in response to an atherogenic diet, the LPL/APOEKO mice developed 2-fold smaller fatty streak lesions in the aortic sinus compared to the APOEKO mice. In conclusion, overproduction of LPL is protective against atherosclerosis even in the absence of apoE.

Animals↗