Cholesteryl ester transfer protein and its inhibition

Vitamin D and Atherosclerosis: Unraveling the Impact on Macrophage Function

Vitamin D plays a crucial role in preventing atherosclerosis and in the regulation of macrophage function. This review aims to provide a comprehensive summary of the clinical evidence regarding the impact of vitamin D on atherosclerotic cardiovascular disease, atherosclerotic cerebrovascular disease, peripheral arterial disease, and associated risk factors. Additionally, it explores the mechanistic studies investigating the influence of vitamin D on macrophage function in atherosclerosis. Numerous findings indicate that vitamin D inhibits monocyte or macrophage recruitment, macrophage cholesterol uptake, and esterification. Moreover, it induces autophagy of lipid droplets in macrophages, promotes cholesterol efflux from macrophages, and regulates macrophage polarization. This review particularly focuses on analyzing the molecular mechanisms and signaling pathways through which vitamin D modulates macrophage function in atherosclerosis. It claims that vitamin D has a direct inhibitory effect on the formation, adhesion, and migration of lipid-loaded monocytes, thus exerting anti-atherosclerotic effects. Therefore, this review emphasizes the crucial role of vitamin D in regulating macrophage function and preventing the development of atherosclerosis.

Mechanism of Glycans Modulating Cholesteryl Ester Transfer Protein: Unveiled by Molecular Dynamics Simulation

Inhibition of the cholesteryl ester transfer protein (CETP) has been considered as a promising way for the treatment of cardiovascular disease (CVD) for three decades. However, clinical trials of several CETP inhibitors with various potencies have been marginally successful at best, raising doubts on the target drugability of CETP. The in-depth understanding of the glycosylated CETP structure could be beneficial to more definitive descriptions of the CETP function and the underlying mechanism. In this work, large-scale molecular dynamics simulations were performed to thoroughly explore the mechanism of glycans modulating CETP. Here, the extensive simulation results intensely suggest that glycan88 tends to assist CETP in forming a continuous tunnel throughout interacting with the upper-right region of the N-barrel, while it also could prevent the formation of a continuous tunnel by swinging toward the right-rear of the N-barrel. Furthermore, glycan240 formed stable H-bonds with Helix-B and might further stabilize the central cavity of CETP. Furthermore, the nonspecific involvement of the hydroxyl groups from the various glycans with protein core interactions and the similar influence of different glycans trapped at similar regions on the protein structure suggest that physiological glycan may lead to a similar effect. This study would provide valuable insights into devising novel methods for CVD treatment targeting CETP and functional studies about glycosylation for other systems.

Obeticholic acid raises LDL-cholesterol and reduces HDL-cholesterol in the Diet-Induced NASH (DIN) hamster model

The use of rat and mouse models limits the translation to humans for developing novel drugs targeting nonalcoholic steatohepatitis (NASH). Obeticholic acid (OCA) illustrates this limitation since its dyslipidemic effect in humans cannot be observed in these rodents. Conversely, Golden Syrian hamsters have a lipoprotein metabolism mimicking human dyslipidemia since it does express the cholesteryl ester transfer protein (CETP). We therefore developed a Diet-Induced NASH (DIN) hamster model and evaluated the impact of OCA. Compared with chow fed controls, hamsters fed for 20 weeks with a free-choice (FC) diet, developed obesity, insulin resistance, dyslipidemia and NASH (microvesicular steatosis, inflammation, hepatocyte ballooning and perisinusoidal to bridging fibrosis). After 20 weeks of diet, FC fed hamsters were treated without or with obeticholic acid (15mg/kg/day) for 5 weeks. Although a non-significant trend towards higher dietary caloric intake was observed, OCA significantly lowered body weight after 5 weeks of treatment. OCA significantly increased CETP activity and LDL-C levels by 20% and 27%, and reduced HDL-C levels by 20%. OCA blunted hepatic gene expression of Cyp7a1 and Cyp8b1 and reduced fecal bile acids mass excretion by 64% (P < 0.05). Hamsters treated with OCA showed a trend towards higher scavenger receptor Class B type I (SR-BI) and lower LDL-receptor hepatic protein expression. OCA reduced NAS score for inflammation (P < 0.01) and total NAS score, although not significantly. Compared to mouse and rat models, the DIN hamster replicates benefits and side effects of OCA as observed in humans, and should be useful for evaluating novel drugs targeting NASH.

Hypertension, lipoprotein subclasses and lipid transfer proteins in obese children and adolescents

BACKGROUND

Obesity-related childhood hypertension is associated with disturbances of serum lipids, but less is known about distribution of lipoprotein subclasses and activities of proteins involved in reverse cholesterol transport in hypertensive obese children. Our objective was to determine low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclasses distribution and activities of lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) in hypertensive and non-hypertensive obese children.

METHODS

A total of 40 hypertensive and 25 non-hypertensive obese children were enrolled. Lipoprotein subclasses were assessed by polyacrylamide gradient gel electrophoresis. LCAT and CETP activities were determined as a rate of formation and a rate of transfer of cholesteryl esters.

RESULTS

Despite of comparable values of serum lipid parameters, a shift toward smaller LDL and HDL subclasses was observed in hypertensive compared to normotensive obese children. Activities of LCAT were similar, but proatherogenic CETP activities were significantly higher in the hypertensive group (p = 0.036). LCAT/net CETP ratio inversely correlated with relative proportion of small, dense LDL particles (ρ = -0.423; p = 0.025) in the group with hypertension.

CONCLUSIONS

The results of our study demonstrated a tendency toward altered distribution of lipoprotein subclasses in favor of more proatherogenic particles in childhood hypertension. Also, hypertensive obese children had increased proatherogenic CETP activity.

Systematic review of CETP inhibitors for increasing high-density lipoprotein cholesterol: where do these agents stand in the approval process?

The role that low levels of high-density lipoprotein cholesterol (HDL-C) plays in coronary artery disease and ischemic heart disease is well established. As such, therapies targeting low HDL-C levels have been of great therapeutic interest. These therapies include nonpharmacological methods such as exercise, tobacco cessation, weight reduction, moderate alcohol intake, and increasing dietary monounsaturated fatty acids and polyunsaturated fatty acids. Additionally, pharmacological methods of increasing HDL-C have been of great interest, with 2 classes of drugs, fibric acid derivatives and nicotinic acid, and have mixed trial results when used on top of standard lipid therapy. However, a new class of medications, cholesteryl ester transfer protein inhibitors, has shown increases in HDL-C of over 100%. However, early trial results with torcetrapib showed an increase in mortality, although this was attributed to off-target toxicity. Dalcetrapib was found to be safer than torcetrapib, but data released in 2012 showed no additional benefit in patients suffering an acute coronary syndrome event. Two newer agents, anacetrapib and evacetrapib, in early-phase clinical trials have shown to be safer than torcetrapib and significantly more potent than dalcetrapib (both increase HDL-C by a greater amount and both have a significant effect on low-density lipoprotein cholesterol). It remains to be seen whether the use of cholesteryl ester transfer protein inhibitors will result in clinical benefit in large, randomized double-blind trials and whether any agents in this class will ever be approved for clinical use.

New Diterpenes from Cultures of the Fungus Engleromyces goetzii and Their CETP Inhibitory Activity

One new cleistanthane-type diterpene named engleromycenolic acid A (1), one new rosane-type diterpene named engleromycenolic acid B (2) and one new natural rosane-type diterpene, engleromycenol (3), along with three known rosane-type diterpenes, rosololactone (4), rosenonolactone (5) and 7-deoxyrosenonolactone (6) were isolated from cultures of the fungus Engleromyces goetzii, where it naturally grows on Alpine bamboo culms. The new compounds were elucidated based on their spectroscopic data. In addition, compounds 1-6 were evaluated for their cholesterol ester transfer protein (CETP) inhibition activity. This paper reports the isolation, structural elucidation, and CETP inhibition activity of these compounds.

Addressing phenoconversion: the Achilles' heel of personalized medicine

Phenoconversion is a phenomenon that converts genotypic extensive metabolizers (EMs) into phenotypic poor metabolizers (PMs) of drugs, thereby modifying their clinical response to that of genotypic PMs. Phenoconversion, usually resulting from nongenetic extrinsic factors, has a significant impact on the analysis and interpretation of genotype-focused clinical outcome association studies and personalizing therapy in routine clinical practice. The high phenotypic variability or genotype-phenotype mismatch, frequently observed due to phenoconversion within the genotypic EM population, means that the real number of phenotypic PM subjects may be greater than predicted from their genotype alone, because many genotypic EMs would be phenotypically PMs. If the phenoconverted population with genotype-phenotype mismatch, most extensively studied for CYP2D6, is as large as the evidence suggests, there is a real risk that genotype-focused association studies, typically correlating only the genotype with clinical outcomes, may miss clinically strong pharmacogenetic associations, thus compromising any potential for advancing the prospects of personalized medicine. This review focuses primarily on co-medication-induced phenoconversion and discusses potential approaches to rectify some of the current shortcomings. It advocates routine phenotyping of subjects in genotype-focused association studies and proposes a new nomenclature to categorize study populations. Even with strong and reliable data associating patients' genotypes with clinical outcome(s), there are problems clinically in applying this knowledge into routine pharmacotherapy because of potential genotype-phenotype mismatch. Drug-induced phenoconversion during routine clinical practice remains a major public health issue. Therefore, the principal challenges facing personalized medicine, which need to be addressed, include identification of the following factors: (i) drugs that are susceptible to phenoconversion; (ii) co-medications that can cause phenoconversion; and (iii) dosage amendments that need to be applied during and following phenoconversion.

Hepatic triglyceride lipase plays an essential role in changing the lipid metabolism in genotype 1b hepatitis C virus replicon cells and hepatitis C patients

AIM

Recently, several studies have shown the existence of associations between lipoprotein profiles and hepatitis C virus (HCV), although only a limited amount of information is available about the mechanisms underlying the changes in the lipoprotein profiles associated with HCV. In this study, we investigated the association between lipoprotein profile, classified according to the particle size, and lipoprotein metabolism.

METHODS

We used four kinds of cells for this experiment; full-length genome HCV RNA replicon cells (OR6), sub-genomic HCV RNA replicon cells (sO), and OR6c cells and sOc cells, which were the same cell lines treated with interferon-α. The triglyceride (TG) levels in the lipoprotein subclasses of the culture medium were measured by high-performance liquid chromatography. The mRNA expression levels of several molecules associated with lipoprotein metabolism were measured in the OR6, OR6c, sO and sOc cells. To confirm some of the results obtained using the in vitro system, liver biopsy samples obtained from the patients were also examined.

RESULTS

The content of TG in the large low-density lipoprotein (LDL) and medium LDL in the culture medium was increased only in the OR6 cells. The hepatic triglyceride lipase (HTGL) mRNA expression levels were lower in the OR6 cells than in the OR6c cells (P < 0.01). Examination of the HTGL expression levels in the patients' livers revealed a decrease in HTGL expression in the chronic hepatitis C liver as compared with that in the chronic hepatitis B or non-alcoholic steatohepatitis liver (P < 0.01).

CONCLUSION

We showed that HCV inhibits HTGL production in hepatocytes, inducing a change of the lipoprotein profile.

Evidence from case-control and longitudinal studies supports associations of genetic variation in APOE, CETP, and IL6 with human longevity

In this study, we investigated 102 single-nucleotide polymorphisms (SNPs) covering the common genetic variation in 16 genes recurrently regarded as candidates for human longevity: APOE; ACE; CETP; HFE; IL6; IL6R; MTHFR; TGFB1; APOA4; APOC3; SIRTs 1, 3, 6; and HSPAs 1A, 1L, 14. In a case-control study of 1,089 oldest-old (ages 92-93) and 736 middle-aged Danes, the minor allele frequency (MAF) of rs769449 (APOE) was significantly decreased in the oldest-old, while the MAF of rs9923854 (CETP) was significantly enriched. These effects were supported when investigating 1,613 oldest-old (ages 95-110) and 1,104 middle-aged Germans. rs769449 was in modest linkage equilibrium (R (2)=0.55) with rs429358 of the APOE-ε4 haplotype and adjusting for rs429358 eliminated the association of rs769449, indicating that the association likely reflects the well-known effect of rs429358. Gene-based analysis confirmed the effects of variation in APOE and CETP and furthermore pointed to HSPA14 as a longevity gene. In a longitudinal study with 11 years of follow-up on survival in the oldest-old Danes, only one SNP, rs2069827 (IL6), was borderline significantly associated with survival from age 92 (P-corrected=0.064). This advantageous effect of the minor allele was supported when investigating a Dutch longitudinal cohort (N=563) of oldest-old (age 85+). Since rs2069827 was located in a putative transcription factor binding site, quantitative RNA expression studies were conducted. However, no difference in IL6 expression was observed between rs2069827 genotype groups. In conclusion, we here support and expand the evidence suggesting that genetic variation in APOE, CETP, and IL6, and possible HSPA14, is associated with human longevity.

Genistein as a potential inducer of the anti-atherogenic enzyme paraoxonase-1: studies in cultured hepatocytes in vitro and in rat liver in vivo

A number of cardioprotective effects, including the reduced oxidation of the low-density lipoprotein (LDL) particles, have been attributed to dietary soy isoflavones. Paraoxonase 1 (PON1), an enzyme mainly synthesized in the liver, may exhibit anti-atherogenic activity by protecting LDL from oxidation. Thus, dietary and pharmacological inducers of PON1 may decrease cardiovascular disease risk. Using a luciferase reporter gene assay we screened different flavonoids for their ability to induce PON1 in Huh7 hepatocytes in culture. Genistein was the most potent flavonoid with regard to its PON1-inducing activity, followed by daidzein, luteolin, isorhamnetin and quercetin. Other flavonoids such as naringenin, cyanidin, malvidin and catechin showed only little or no PON1-inducing activity. Genistein-mediated PON1 transactivation was partly inhibited by the oestrogen-receptor antagonist fulvestrant as well as by the aryl hydrocarbon receptor antagonist 7-ketocholesterol. In contrast to genistein, the conjugated genistein metabolites genistein-7-glucuronide, genistein-7-sulfate and genistein-7,4'-disulfate were only weak inducers of PON1 transactivation. Accordingly, dietary genistein supplementation (2 g/kg diet over three weeks) in growing rats did not increase hepatic PON1 mRNA and protein levels as well as plasma PON1 activity. Thus, genistein may be a PON1 inducer in cultured hepatocytes in vitro, but not in rats in vivo.

Resveratrol attenuates oxidative stress and prevents steatosis and hypertension in obese rats programmed by early weaning

We hypothesized that resveratrol, a natural phytoalexin found in grapes, can prevent oxidative stress, obesity and its related disturbances in obese rats programmed by early weaning. Lactating Wistar rats were separated into two groups: early weaning (EW) - dams who were wrapped with a bandage to interrupt the lactation in the last 3 days of lactation; control - dams whose pups had free access to milk during all lactation. At the 150th day, EW offspring were randomly subdivided into EW+resveratrol (EW+Res) - resveratrol (30 mg/kg/day); EW+vehicle (EW) - rats that received 0.5% (w/v) aqueous methylcellulose. The control group received vehicle. Rats were treated by gavage daily for 30 days. EW offspring developed hyperphagia, higher body weight, visceral obesity, higher systolic (SBP) and diastolic blood pressure (DBP) (+15% and +20%, respectively; P<.05) and higher serum triglycerides (TG) and low-density lipoprotein but lower high-density lipoprotein (+55%, +33% and -13%, respectively; P<.05). Resveratrol normalized food intake, SBP and DBP and prevented obesity and dyslipidemia in EW+Res. EW rats had higher plasma and liver thiobarbituric-acid-reactive substances (TBARS) and lower plasma superoxide dismutase (SOD) and liver glutathione peroxidase activities (+51%, +18%, -58%, -31%, respectively; P<.05), and resveratrol normalized both plasma and liver TBARS and increased the activity of SOD and catalase in plasma. EW rats presented liver steatosis and higher liver TG, and resveratrol prevented these hepatic alterations. In conclusion, this study demonstrated a potential therapeutic use of resveratrol in preventing obesity and oxidative stress and reducing the risk of hypertension, dyslipidemia and steatosis in adult rats programmed by early weaning.

Characterization of lipid and lipoprotein metabolism in primary human hepatocytes

Primary rodent hepatocytes and hepatoma cell lines are commonly used as model systems to elucidate and study potential drug targets for metabolic diseases such as obesity and atherosclerosis. However, if therapies are to be developed, it is essential that our knowledge gained from these systems is translatable to that of human. Here, we have characterized lipid and lipoprotein metabolism in primary human hepatocytes for comparison to rodent primary hepatocytes and human hepatoma cell lines. Primary human hepatocytes were maintained in collagen coated dishes in confluent monolayers for up to 3 days. We found primary human hepatocytes were viable, underwent lipid synthesis, and were able to secret lipoproteins up to 3 days in culture. Furthermore, the lipoprotein profile secreted by primary human hepatocytes was comparable to that found in human plasma; this contrasts with primary rodent hepatocytes and human hepatoma cells. We also investigated the pharmacological effects of nicotinic acid (niacin, NA), a potent dyslipidemic drug, on hepatic lipid synthesis and lipoprotein secretion. We found NA increased the expression of ATP-binding cassette transporter A1 in primary human hepatocytes, which may potentially explain how NA increases plasma high-density lipoproteins in humans. In conclusion, primary human hepatocytes are a more relevant model to study lipid synthesis and lipoprotein secretion than hepatoma cells or rodent primary hepatocyte models. Further research needs to be done to maintain liver specific functions of primary human hepatocytes in prolonged cultures for these cells to be a viable model.

Resveratrol in cardiovascular disease: what is known from current research?

Resveratrol is a well-known antioxidant that exists in grape skin/seed, red wine, and the root of Polygonum cuspidatum, a traditional Chinese and Japanese medicinal material. Studies have found that resveratrol has many interesting properties, including anti-carcinogenic properties, anti-microbial and antiviral effects, the ability to reverse dyslipidemia and obesity, the ability to attenuate hyperglycemia and hyperinsulinemia, and the ability to protect endothelial function. Heart failure is the final consequence of the majority of cardiovascular diseases, and resveratrol has been shown to directly attenuate heart contraction. The cardiovascular protective capacities of resveratrol are associated with multiple molecular targets and may lead to the development of novel therapeutic strategies for atherosclerosis, ischemia/reperfusion, metabolic syndrome, and heart failure. This article will mainly review recently published basic researches about the protective cardiovascular effects of resveratrol because these results may lead to the development of new clinical therapeutics in patients.

Prediction of a potentially effective dose in humans for BAY 60-5521, a potent inhibitor of cholesteryl ester transfer protein (CETP) by allometric species scaling and combined pharmacodynamic and physiologically-based pharmacokinetic modelling

AIMS

The purpose of this work was to support the prediction of a potentially effective dose for the CETP-inhibitor, BAY 60-5521, in humans.

METHODS

A combination of allometric scaling of the pharmacokinetics of the CETP-inhibitor BAY 60-5521 with pharmacodynamic studies in CETP-transgenic mice and in human plasma with physiologically-based pharmacokinetic (PBPK) modelling was used to support the selection of the first-in-man dose.

RESULTS

The PBPK approach predicts a greater extent of distribution for BAY 60-5521 in humans compared with the allometric scaling method as reflected by a larger predicted volume of distribution and longer elimination half-life. The combined approach led to an estimate of a potentially effective dose for BAY 60-5521 of 51 mg in humans.

CONCLUSION

The approach described in this paper supported the prediction of a potentially effective dose for the CETP-inhibitor BAY 60-5521 in humans. Confirmation of the dose estimate was obtained in a first-in-man study.

CETP inhibitor torcetrapib promotes reverse cholesterol transport in obese insulin-resistant CETP-ApoB100 transgenic mice

Insulin resistance and type 2 diabetes are associated with low HDL-cholesterol (HDL-c) levels, which would impair reverse cholesterol transport (RCT). A promising therapeutic strategy is to raise HDL with cholesteryl ester transfer protein (CETP) inhibitors, but their effects on RCT remains to be demonstrated in vivo. We therefore evaluated the effects of CETP inhibitor torcetrapib in CETP-apolipoprotein (apo)B100 mice made obese and insulin resistant with a 60% high-fat diet. High-fat diet over 3 months increased body weight and homeostasis model of insulin resistance index by 30% and 846%, respectively (p < 0.01 for both vs. chow-fed mice). Total cholesterol (TC) increased by 46% and HDL-c/TC ratio decreased by 28% (both p < 0.05). Compared to vehicle, high-fat-fed mice treated with torcetrapib (30 mg/kg/day, 3 weeks) showed increased HDL-c levels and HDL-c/TC ratio by 41% and 37% (both p < 0.05). Torcetrapib increased in vitro macrophage cholesterol efflux by 22% and in vivo RCT through a 118% increase in (3) H-bile acids fecal excretion after (3) H-cholesterol labeled macrophage injection (p < 0.01 for both). Fecal total bile acids mass was also increased by 158% (p < 0.001). In conclusion, CETP inhibition by torcetrapib improves RCT in CETP-apoB100 mice. These results emphasize the potential of CETP inhibition to prevent cardiovascular diseases.

Dancing with the sterols: critical roles for ABCG1, ABCA1, miRNAs, and nuclear and cell surface receptors in controlling cellular sterol homeostasis

ATP binding cassette (ABC) transporters represent a large and diverse family of proteins that transport specific substrates across a membrane. The importance of these transporters is illustrated by the finding that inactivating mutations within 17 different family members are known to lead to specific human diseases. Clinical data from humans and/or studies with mice lacking functional transporters indicate that ABCA1, ABCG1, ABCG4, ABCG5 and ABCG8 are involved in cholesterol and/or phospholipid transport. This review discusses the multiple mechanisms that control cellular sterol homeostasis, including the roles of microRNAs, nuclear and cell surface receptors and ABC transporters, with particular emphasis on recent findings that have provided insights into the role(s) of ABCG1. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).

An expanded family of proteins with BPI/LBP/PLUNC-like domains in trypanosome parasites: an association with pathogenicity?

Trypanosomatids are protozoan parasites that cause human and animal disease. Trypanosoma brucei telomeric ESs (expression sites) contain genes that are critical for parasite survival in the bloodstream, including the VSG (variant surface glycoprotein) genes, used for antigenic variation, and the SRA (serum-resistance-associated) gene, which confers resistance to lysis by human serum. In addition, ESs contain ESAGs (expression-site-associated genes), whose functions, with few exceptions, have remained elusive. A bioinformatic analysis of the ESAG5 gene of T. brucei showed that it encodes a protein with two BPI (bactericidal/permeability-increasing protein)/LBP (lipopolysaccharide-binding protein)/PLUNC (palate, lung and nasal epithelium clone)-like domains and that it belongs to a multigene family termed (GR)ESAG5 (gene related to ESAG5). Members of this family are found with various copy number in different members of the Trypanosomatidae family. T. brucei has an expanded repertoire, with multiple ESAG5 copies and at least five GRESAG5 genes. In contrast, the parasites of the genus Leishmania, which are intracellular parasites, have only a single GRESAG5 gene. Although the amino acid sequence identity between the (GR)ESAG5 gene products between species is as low as 15-25%, the BPI/LBP/PLUNC-like domain organization and the length of the proteins are highly conserved, and the proteins are predicted to be membrane-anchored or secreted. Current work focuses on the elucidation of possible roles for this gene family in infection. This is likely to provide novel insights into the evolution of the BPI/LBP/PLUNC-like domains.

High LDL levels are associated with increased lipoprotein-associated phospholipase A(2) activity on nitric oxide synthesis and reactive oxygen species formation in human endothelial cells

OBJECTIVE

To evaluate in vitro the effects of serum and LDL fractions isolated from hypercholesterolemic patients on nitric oxide (NO) synthesis and reactive oxygen species (ROS) production by human umbilical vein endothelial cells (HUVECs).

DESIGN AND METHODS

Serum and LDL isolated from subjects with high (n=18) and normal (n=21) LDL-cholesterol levels were analyzed on NO synthesis and ROS production in vitro models of HUVECs. LDL was furthers characterized in their chemical composition and activities of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), cholesteryl ester transfer protein (CETP) and paraoxonase.

RESULTS

NO bioavailability was significantly lower and ROS production higher in HUVECs incubated with serum samples from patients with high LDL-cholesterol levels in comparison to control subjects. Moreover, hypercholesterolemic patients presented higher CETP and Lp-PLA(2) activities than control subjects. LDL fractions isolated from patients and controls were not different in their chemical composition, Lp-PLA(2) activity, and their capacity to reduce NO synthesis and increase ROS production.

CONCLUSION

Alterations of serum from hypercholesterolemic patients could be due to the increment in LDL concentration, main Lp-PLA(2) carrier, and not to LDL composition or intrinsic Lp-PLA(2) activity.