Advances in understanding of the role of lecithin cholesterol acyltransferase (LCAT) in cholesterol transport

The Plasma Lipidomic Landscape in Patients with Sepsis due to Community-acquired Pneumonia

Rationale: The plasma lipidome has the potential to reflect many facets of the host status during severe infection. Previous work is limited to specific lipid groups or was focused on lipids as prognosticators.Objectives: To map the plasma lipidome during sepsis due to community-acquired pneumonia (CAP) and determine the disease specificity and associations with clinical features.Methods: We analyzed 1,833 lipid species across 33 classes in 169 patients admitted to the ICU with sepsis due to CAP, 51 noninfected ICU patients, and 48 outpatient controls. In a paired analysis, we reanalyzed patients still in the ICU 4 days after admission (n = 82).Measurements and Main Results: A total of 58% of plasma lipids were significantly lower in patients with CAP-attributable sepsis compared with outpatient controls (6% higher, 36% not different). We found strong lipid class-specific associations with disease severity, validated across two external cohorts, and inflammatory biomarkers, in which triacylglycerols, cholesterol esters, and lysophospholipids exhibited the strongest associations. A total of 36% of lipids increased over time, and stratification by survival revealed diverging lipid recovery, which was confirmed in an external cohort; specifically, a 10% increase in cholesterol ester levels was related to a lower odds ratio (0.84; P = 0.006) for 30-day mortality (absolute mortality, 18 of 82). Comparison with noninfected ICU patients delineated a substantial common illness response (57.5%) and a distinct lipidomic signal for patients with CAP-attributable sepsis (37%).Conclusions: Patients with sepsis due to CAP exhibit a time-dependent and partially disease-specific shift in their plasma lipidome that correlates with disease severity and systemic inflammation and is associated with higher mortality.

A High-Throughput NMR Method for Lipoprotein-X Quantification

Lipoprotein X (LP-X) is an abnormal cholesterol-rich lipoprotein particle that accumulates in patients with cholestatic liver disease and familial lecithin-cholesterol acyltransferase deficiency (FLD). Because there are no high-throughput diagnostic tests for its detection, a proton nuclear magnetic resonance (NMR) spectroscopy-based method was developed for use on a clinical NMR analyzer commonly used for the quantification of lipoproteins and other cardiovascular biomarkers. The LP-X assay was linear from 89 to 1615 mg/dL (cholesterol units) and had a functional sensitivity of 44 mg/dL. The intra-assay coefficient of variation (CV) varied between 1.8 and 11.8%, depending on the value of LP-X, whereas the inter-assay CV varied between 1.5 and 15.4%. The assay showed no interference with bilirubin levels up to 317 mg/dL and was also unaffected by hemolysis for hemoglobin values up to 216 mg/dL. Samples were stable when stored for up to 6 days at 4 °C but were not stable when frozen. In a large general population cohort (n = 277,000), LP-X was detected in only 50 subjects. The majority of LP-X positive cases had liver disease (64%), and in seven cases, had genetic FLD (14%). In summary, we describe a new NMR-based assay for LP-X, which can be readily implemented for routine clinical laboratory testing.

Disulfidptosis-related signature predicts prognosis and characterizes the immune microenvironment in hepatocellular carcinoma

BACKGROUND

Disulfidptosis is a type of programmed cell death caused by excessive cysteine-induced disulfide bond denaturation leading to actin collapse. Liver cancer has a poor prognosis and requires more effective intervention strategies. Currently, the prognostic and therapeutic value of disulfidptosis in liver cancer is not clear.

METHODS

We investigated the features of 16 disulfidptosis-related genes (DRGs) of HCC patients in the TCGA and classified the patients into two disulfidptosis pattern clusters by consensus clustering analysis. Then, we constructed a prognostic model using LASSO Cox regression. Next, the microenvironment and drug sensitivity were evaluated. Finally, we used qPCR and functional analysis to verify the reliability of hub DRGs.

RESULTS

Most of the DRGs showed significantly higher expression in cancer tissues than in adjacent tissues. Our prognostic model, the DRG score, can well predict the survival of HCC patients. There were significant differences in survival, features of the microenvironment, effects of immunotherapy, and drug sensitivity between the high- and low-DRG score groups. Ultimately, we demonstrated that a few hub DRGs have differential mRNA expression between liver cancer cells and normal cells and that the protective gene LCAT can inhibit liver cancer metastasis in vitro.

CONCLUSION

We established a novel risk model based on DRG scores to predict HCC patient prognosis, drug sensitivity and immunotherapy efficacy, which provides new insight into the relationship between disulfidptosis and HCC and provides valuable assistance for the personalized treatment of HCC.

Impaired Reverse Cholesterol Transport is Associated with Changes in Fatty Acid Profile in Children and Adolescents with Abdominal Obesity

BACKGROUND

Abdominal obesity is an important cardiovascular disease risk factor. Plasma fatty acids display a complex network of both pro and antiatherogenic effects. High density lipoproteins (HDL) carry out the antiatherogenic pathway called reverse cholesterol transport (RCT), which involves cellular cholesterol efflux (CCE), and lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) activities.

OBJECTIVES

Our aim was to characterize RCT and its relation to fatty acids present in plasma in pediatric abdominal obesity.

METHODS

Seventeen children and adolescents with abdominal obesity and 17 healthy controls were studied. Anthropometric parameters were registered. Glucose, insulin, lipid levels, CCE employing THP-1 cells, LCAT and CETP activities, plus fatty acids in apo B-depleted plasma were measured.

RESULTS

The obese group showed a more atherogenic lipid profile, plus lower CCE (Mean±Standard Deviation) (6 ± 2 vs. 7 ± 2%; P < 0.05) and LCAT activity (11 ± 3 vs. 15 ±5 umol/dL.h; P < 0.05). With respect to fatty acids, the obese group showed higher myristic (1.1 ± 0.3 vs. 0.7 ± 0.3; P < 0.01) and palmitic acids (21.5 ± 2.8 vs. 19.6 ± 1.9; P < 0.05) in addition to lower linoleic acid (26.4 ± 3.3 vs. 29.9 ± 2.6; P < 0.01). Arachidonic acid correlated with CCE (r = 0.37; P < 0.05), myristic acid with LCAT (r = -0.37; P < 0.05), palmitioleic acid with CCE (r = -0.35; P < 0.05), linoleic acid with CCE (r = 0.37; P < 0.05), lauric acid with LCAT (r = 0.49; P < 0.05), myristic acid with LCAT (r = -0.37; P < 0.05) ecoisatrienoic acid with CCE (r = 0.40; P < 0.05) and lignoseric acid with LCAT (r = -0.5; P < 0.01).

CONCLUSIONS

Children and adolescents with abdominal obesity presented impaired RCT, which was associated with modifications in proinflammatory fatty acids, such as palmitoleic and myristic, thus contributing to increased cardiovascular disease risk.

HDL-like-Mediated Cell Cholesterol Trafficking in the Central Nervous System and Alzheimer's Disease Pathogenesis

The main aim of this work is to review the mechanisms via which high-density lipoprotein (HDL)-mediated cholesterol trafficking through the central nervous system (CNS) occurs in the context of Alzheimer’s disease (AD). Alzheimer’s disease is characterized by the accumulation of extracellular amyloid beta (Aβ) and abnormally hyperphosphorylated intracellular tau filaments in neurons. Cholesterol metabolism has been extensively implicated in the pathogenesis of AD through biological, epidemiological, and genetic studies, with the APOE gene being the most reproducible genetic risk factor for the development of AD. This manuscript explores how HDL-mediated cholesterol is transported in the CNS, with a special emphasis on its relationship to Aβ peptide accumulation and apolipoprotein E (ApoE)-mediated cholesterol transport. Indeed, we reviewed all existing works exploring HDL-like-mediated cholesterol efflux and cholesterol uptake in the context of AD pathogenesis. Existing data seem to point in the direction of decreased cholesterol efflux and the impaired entry of cholesterol into neurons among patients with AD, which could be related to impaired Aβ clearance and tau protein accumulation. However, most of the reviewed studies have been performed in cells that are not physiologically relevant for CNS pathology, representing a major flaw in this field. The ApoE4 genotype seems to be a disruptive element in HDL-like-mediated cholesterol transport through the brain. Overall, further investigations are needed to clarify the role of cholesterol trafficking in AD pathogenesis.

HDL and Oxidation

In this chapter, we will focus on HDLs' activity of inhibiting LDL oxidation and neutralizing some other oxidants. ApoA-I was known as the main antioxidant component in HDLs. The regulation of antioxidant capacity of HDL is mainly exhibited in regulation of apoA-I and alterations at the level of the HDL lipidome and the modifications of the proteome, especially MPO and PON1. HDL oxidation will influence the processes of inflammation and cholesterol transport, which are important processes in atherosclerosis, metabolic diseases, and many other diseases. In a word, HDL oxidation might be an effective antioxidant target in treatment of many diseases.

Vascular inflammation and impaired reverse cholesterol transport and lipid metabolism in obese children and adolescents

BACKGROUND AND AIMS

Childhood obesity is associated to complications such as insulin resistance and dyslipidemia. High density lipoproteins (HDL) constitute the only lipoprotein fraction with ateroprotective properties. The aim of the present study was to analyze inflammatory markers, carbohydrate metabolism, lipid profile and HDL functionality in obese children and adolescents compared to healthy controls.

METHODS AND RESULTS

Twenty obese children and adolescents (Body mass index z score >3.0) (9-15 years old) and 20 age and sex similar controls were included in the study. Triglyceride (TG), total cholesterol (TC), HDL-C, LDL-C, apolipoproteins (apo) A-I and B, glucose and insulin levels were quantified. Lipid indexes and HOMA-IR were calculated. Cholesterol efflux (CEC), lipoprotein associated phospholipase A₂ (Lp-PLA₂), lecithin-cholesterol acyl transferase (LCAT) and cholesteryl ester transfer protein, plus paraoxonase and arylesterase (ARE) activities were evaluated. Obese children and adolescents showed significantly higher TG [69 (45-95) vs 96 (76-121); p < 0.05], non-HDL-C [99 ± 34 vs 128 ± 26; p < 0.01], TC/HDL-C [2.8 ± 0.6 vs 4.7 ± 1.5; p < 0.01], TG/HDL-C [1.1 (1.0-1.8) vs 2,2 (1.4-3.2); p < 0.01], and HOMA-IR [1.5 (1.1-1.9) vs. 2.6 (2.0-4.5); p < 0.01] values, plus Lp-PLA₂ activity [8.3 ± 1.9 vs 7.1 ± 1.7 umol/ml.h; p < 0,05] in addition to lower HDL-C [57 ± 10 vs 39 ± 9; p < 0.01], apo A-I [143 ± 25 vs 125 ± 19; p < 0.05], and CEC [6.4 (5.1-6.8) vs. 7.8 (5.7-9.5); p < 0.01] plus LCAT [12.6 ± 3.3 vs 18.7 ± 2.6; p < 0.05] and ARE [96 ± 19 vs. 110 ± 19; p < 0.05] activities. Lp-PLA₂ activity correlated with LDL-C (r = 0.72,p < 0.01), non-HDL-C (r = 0.76,p < 0.01), and apo B (r = 0.60,p < 0.01). LCAT activity correlated with triglycerides (r = -0.78,p < 0.01), HDL-C (r = 0.64,p < 0.01), and apo A-I (r = 0.62, p < 0.05). ARE activity correlated with HDL-C (r = 0.32,p < 0.05) and apoA-I (r = 0.43,p < 0.01). CEC was negatively associated with BMI z-score (r = -0.36,p < 0.05), and triglycerides (r = -0.28,p < 0.05), and positively with LCAT activity (r = 0.65,p < 0.05). In multivariate analysis, BMI z-score was the only parameter significantly associated to CEC (r2 = 0.43, beta = -0.38, p < 0.05).

CONCLUSION

The obese group showed alterations in carbohydrate and lipid metabolism, which were associated to the presence of vascular specific inflammation and impairment of HDL atheroprotective capacity. These children and adolescents would present qualitative alterations in their lipoproteins which would determine higher risk of suffering premature cardiovascular disease.

Potential role of hepatic lipase in the accretion of docosahexaenoic acid (DHA) by the brain

DHA (docosahexaenoic acid) is an essential fatty acid that is required for the normal development and function of the brain. Because of its inability to synthesize adequate amounts of DHA from the precursors, the brain has to acquire DHA from plasma through the blood brain barrier (BBB). Recent studies demonstrated the presence of a transporter at the BBB that specifically transports DHA into the brain in the form of lysophosphatidylcholine (LPC-DHA). However, the mechanism by which LPC-DHA is generated in the plasma is not known. Our previous studies showed that there are at least three different enzymes - lecithin cholesterol acyltransferase (LCAT), endothelial lipase (EL), and hepatic lipase (HL), which can generate LPC-DHA from sn-2 DHA phosphatidylcholine. Here we determined the relative contributions of these enzymes in the delivery of DHA to the brain by measuring the brain DHA levels in the mice deficient in each of these enzymes. The results show that the brain DHA levels of LCAT-deficient mice or EL-deficient mice were not significantly lower than those of their littermates. However, brain DHA was significantly decreased in HL deficient mice (13.5% of total fatty acids) compared to their littermates (17.1%) (p < 0.002), and further decreased to 8.3% of total fatty acids in mice deficient in both HL and EL. These results suggest that HL activity may be the major source for the generation of LPC-DHA in the plasma necessary for transport into the brain, and EL might contribute to this process in the absence of HL.

Common plasma protein marker LCAT in aggressive human breast cancer and canine mammary tumor

Breast cancer is one of the most frequently diagnosed cancers. Although biomarkers are continuously being discovered, few specific markers, rather than classification markers, representing the aggressiveness and invasiveness of breast cancer are known. In this study, we used samples from canine mammary tumors in a comparative approach. We subjected 36 fractions of both canine normal and mammary tumor plasmas to high-performance quantitative proteomics analysis. Among the identified proteins, LCAT was selectively expressed in mixed tumor samples. With further MRM and Western blot validation, we discovered that the LCAT protein is an indicator of aggressive mammary tumors, an advanced stage of cancer, possibly highly metastatic. Interestingly, we also found that LCAT is overexpressed in high-grade and lymphnode-positive breast cancer in silico data. We also demonstrated that LCAT is highly expressed in the sera of advanced-stage human breast cancers within the same classification. In conclusion, we identified a possible common plasma protein biomarker, LCAT, that is highly expressed in aggressive human breast cancer and canine mammary tumor.

Downregulation of apolipoprotein A-IV in plasma & impaired reverse cholesterol transport in individuals with recent acts of deliberate self-harm

Background & objectives:

The major limiting factor in the prevention of suicide is the limited knowledge on molecular insights in individuals at risk. Identification of peripheral protein markers which can classify individuals at high-risk of suicide might aid in early diagnosis and effective medical intervention. The aim of the present study was, therefore, to analyze the differential regulation of plasma proteins in individuals with deliberate self-harm compared to controls.

Methods:

Using two-dimensional gel electrophoresis coupled with matrix-assisted laser desorption-ionization mass spectrometry, differentially expressed plasma proteins were identified in study participants with deliberate self-harm compared to age- and gender-matched controls. The finding was validated using mass spectrometry-based isotope-labelled relative quantification and Western blot analysis in a new set of individuals with deliberate self-harm and controls.

Results:

The plasma proteomic analysis showed that apolipoprotein A-IV (Apo A-IV) was downregulated by 2.63-fold (confidence interval: 1.52-4.54) in individuals with deliberate self-harm (n=10) compared to matched controls, which was consistent in mass spectrometry-based relative quantification and Western blot analysis performed in an independent set of individuals with deliberate self-harm (n=18). In addition, plasma levels of total cholesterol, esterified cholesterol and high-density lipoprotein (HDL) were observed to be significantly lower individuals with deliberate self-harm compared to controls.

Interpretation & conclusions:

Apo A-IV, which plays a crucial role in the esterification of free cholesterol, was found to be downregulated with concomitantly decreased levels of HDL, esterified cholesterol and total cholesterol in individuals with deliberate self-harm compared to matched controls. The present findings might provide a link between the differential regulation of plasma proteins and the previously reported results on altered cholesterol levels in individuals with deliberate self-harm.

Visualized Metabolic Disorder and Its Chemical Inducer in Wild Crucian Carp from Taihu Lake, China

A variety of anthropogenic chemicals can disrupt the equilibrium of intrinsic biological metabolites in organisms, leading to metabolic disorders and an increased risk of metabolic syndromes. However, exposure to pollutants that induce metabolic disorders in wildlife as a cause of adverse effects is unknown. In this study, approximately 3108 compounds, including 11 groups of metabolites and 388 pollutants, were simultaneously identified in the blood of wild crucian carp (Carassius auratus) captured in three bays of Taihu Lake, China. A visualized network linking thousands of co-regulated metabolites was automatically produced for the screened signals. This comprehensive view of the differences in blood metabolite profiles in carp from the north and south bays showed that triglycerides (TGs) were the intrinsic molecules most affected by differing environmental pollution in each bay. The regional differences in metabolite profiles were linked to exposure to screened perfluorinated compounds that displayed corresponding regional differences in concentrations and effects on TGs in in vivo exposure tests. Perfluoroundecanoic acid (PFUnDA) was the key pollutant responsible for the variation in blood TGs in wild crucian carp, and exposure to PFUnDA resulted in extremely high biological activity on lipid deposition in the liver tissues of crucian carp at environmental levels.

Visualized Networking of Co-Regulated Lipids in Human Blood Based on High-Throughput Screening Data: Implications for Exposure Assessment

Exposure to environmental chemicals could disturb lipidome homeostasis in biotas. Comprehensive identification and interpretation of lipid molecules in biological samples are of great importance to elucidate the potential changes in lipid homeostasis upon exposure to various environmental stimuli. In this study, a total of 156 human blood samples were collected including 108 general citizens (control group) and 48 employees in a municipal solid waste incineration (MSWI) plant (occupational exposure group). More than 1500 lipid molecules, belonging to five lipid classes, were screened in the blood samples by UPLC-QTOF-MS in the MS^E acquisition mode. All of the coupled compounds with correlation coefficients ( R) of 0.7 or higher were selected for automated network correlation analysis. A global visual network was automatically produced from thousands of coregulated lipid species in the blood samples. In the automatically produced molecular network, the distributions of the major correlated lipids were in accordance with their metabolic pathways in the KEGG map. Different lipidomic profiles in the blood samples from the two groups of people were easily observed by this visualization technique. Among the intrinsic lipid classes, glycererides and sterol lipids might represent the most sensitively affected lipids upon exposure to various pollutants emitted from the MSWI plant. The visualized network of coregulated lipids identified in human blood presents a new approach for interpreting the metabolic relationships among the thousands of metabolites identified in toxicological and epidemiological studies.

Green tea extract attenuates non alcoholic fatty liver disease by decreasing hyperlipidemia and enhancing Superoxide dismutase activity in cholesterol-fed rats

BACKGROUND/AIM: Health benefits of green tea for a wide variety of ailments, including the cancer, heart disease, and liver disease, were reported. It is believed to have beneficial effects in the prevention and treatment of many diseases, one of which is non-alcoholic fatty liver disease (NAFLD). This study inspects the protective effect of green tea against atherosclerosis and NAFLD in comparative approach between curative and preventive models. MATERIALS AND METHODS: Twenty four of Wistar rats were studied for 150 days. After 15 days of adaptation period, rats were divided into four groups including normal Group (NG), control Hypercholesterolemic diet Group (CHDG), preventive Group (PG) and curative Group (CG) that followed respectively the following regimens: 1 mL/kg of sunflower oil for 150 days, 1 mL/kg of cholesterol solution prepared at 1.5% (w/v) in sunflower oil span 150 days, 1 ml/kg of cholesterol solution at 1.5% (w/v) in sunflower oil with 3 mL/kg GTLE for 60 days and 1 mL/kg of cholesterol solution at 1.5% (w/v) in sunflower oil for 30 days followed by 3 mL/kg of GTLE for 30 days. These both PG and CG groups were ingested with cholesterol 1.5% (w/v) during remaining period. RESULTS: The results showed significant increase, except for NG, during the 30 first days (p≤0.001) in lipid serum profiles including Total Cholesterol (TC), Triacylglycerol (TG) and Low-Density Lipoprotein cholesterol (LDL-c). However, the High-Density Lipoprotein cholesterol (HDL-c) profile decreased during the treatment (p≤0.001). The ingestion of GTLE in treated groups (CG and PG) declined significantly (p≤0.001) in blood lipid concentrations (TC: 67%, TG: 23%, LDL-c: 81.12%) except for the HDL-c that increased up to 15%. The Atherogenic Index (AI) also decreased significantly (p≤0.001) up to 48%, in CG and PG. PG and NG marked same SOD activity values (130.91±7.66 versus 141.31±8.21 U/mL), while CG showed the lowest level. Liver sections were well protected in protective model than curative one.

Current and future therapies for addressing the effects of inflammation on HDL cholesterol metabolism

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Inflammatory processes arising from metabolic abnormalities are known to precipitate the development of CVD. Several metabolic and inflammatory markers have been proposed for predicting the progression of CVD, including high density lipoprotein cholesterol (HDL-C). For ~50 years, HDL-C has been considered as the atheroprotective 'good' cholesterol because of its strong inverse association with the progression of CVD. Thus, interventions to increase the concentration of HDL-C have been successfully tested in animals; however, clinical trials were unable to confirm the cardiovascular benefits of pharmaceutical interventions aimed at increasing HDL-C levels. Based on these data, the significance of HDL-C in the prevention of CVD has been called into question. Fundamental in vitro and animal studies suggest that HDL-C functionality, rather than HDL-C concentration, is important for the CVD-preventive qualities of HDL-C. Our current review of the literature positively demonstrates the negative impact of systemic and tissue (i.e. adipose tissue) inflammation in the healthy metabolism and function of HDL-C. Our survey indicates that HDL-C may be a good marker of adipose tissue health, independently of its atheroprotective associations. We summarize the current findings on the use of anti-inflammatory drugs to either prevent HDL-C clearance or improve the function and production of HDL-C particles. It is evident that the therapeutic agents currently available may not provide the optimal strategy for altering HDL-C metabolism and function, and thus, further research is required to supplement this mechanistic approach for preventing the progression of CVD.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Antioxidative activity of high-density lipoprotein (HDL): Mechanistic insights into potential clinical benefit

Uptake of low-density lipoprotein (LDL) particles by macrophages represents a key step in the development of atherosclerotic plaques, leading to the foam cell formation. Chemical modification of LDL is however necessary to induce this process. Proatherogenic LDL modifications include aggregation, enzymatic digestion and oxidation. LDL oxidation by one-electron (free radicals) and two-electron oxidants dramatically increases LDL affinity to macrophage scavenger receptors, leading to rapid LDL uptake and fatty streak formation. Circulating high-density lipoprotein (HDL) particles, primarily small, dense, protein-rich HDL3, provide potent protection of LDL from oxidative damage by free radicals, resulting in the inhibition of the generation of pro-inflammatory oxidized lipids. HDL-mediated inactivation of lipid hydroperoxides involves their initial transfer from LDL to HDL and subsequent reduction to inactive hydroxides by redox-active Met residues of apolipoprotein A-I. Several HDL-associated enzymes are present at elevated concentrations in HDL3 relative to large, light HDL2 and can be involved in the inactivation of short-chain oxidized phospholipids. Therefore, HDL represents a multimolecular complex capable of acquiring and inactivating proatherogenic lipids. Antioxidative function of HDL can be impaired in several metabolic and inflammatory diseases. Structural and compositional anomalies in the HDL proteome and lipidome underlie such functional deficiency. Concomitant normalization of the metabolism, circulating levels, composition and biological activities of HDL particles, primarily those of small, dense HDL3, can constitute future therapeutic target.

Atherogenic Impact of Lecithin-Cholesterol Acyltransferase and Its Relation to Cholesterol Esterification Rate in HDL (FERHDL) and AIP [log(TG/HDL-C)] Biomarkers: The Butterfly Effect?

The atherogenic impact and functional capacity of LCAT was studied and discussed over a half century. This review aims to clarify the key points that may affect the final decision on whether LCAT is an anti-atherogenic or atherogenic factor. There are three main processes involving the efflux of free cholesterol from peripheral cells, LCAT action in intravascular pool where cholesterol esterification rate is under the control of HDL, LDL and VLDL subpopulations, and finally the destination of newly produced cholesteryl esters either to the catabolism in liver or to a futile cycle with apoB lipoproteins. The functionality of LCAT substantially depends on its mass together with the composition of the phospholipid bilayer as well as the saturation and the length of fatty acyls and other effectors about which we know yet nothing. Over the years, LCAT puzzle has been significantly supplemented but yet not so satisfactory as to enable how to manipulate LCAT in order to prevent cardiometabolic events. It reminds the butterfly effect when only a moderate change in the process of transformation free cholesterol to cholesteryl esters may cause a crucial turn in the intended target. On the other hand, two biomarkers – FERHDL (fractional esterification rate in HDL) and AIP [log(TG/HDL-C)] can offer a benefit to identify the risk of cardiovascular disease (CVD). They both reflect the rate of cholesterol esterification by LCAT and the composition of lipoprotein subpopulations that controls this rate. In clinical practice, AIP can be calculated from the routine lipid profile with help of AIP calculator www.biomed.cas.cz/fgu/aip/calculator.php.

Hypolipidemic effect and activation of Lecithin Cholesterol Acyl Transferase (LCAT) by aqueous extract of Spirulina platensis during toxicological investigation

BACKGROUND

Spirulina platensis produced in Nomayos (Cameroon) is used as a dietary supplement. S. platensis is known as a neutraceutical with many beneficial effects on humans like lipid-lowering action. This study aims to investigate the mechanism of hypolipidemic action of aqueous extract of Spirulina platensis (S. platensis) through the toxicological studies.

METHODS

In this study, we included two month old Wistar rats, weighing between 180 and 200 g. Aqueous S. platensis was extracted and prepared using standard methods. The rats received a supplementation of S. platensis at 5000 mg/Kg of body weight as single dose in acute toxicity whereas different doses (250, 500, 1000 mg / kg body weight) were administered in subacute toxicity compared to control. Acute and subacute toxicities were determined according to the guidelines 420 (14 days) and 407 (28 days) of the Organization for Economic Cooperation and Development (OECD) respectively. Biochemical parameters such as urea, creatinine, total and direct bilirubin, lipid profile and transaminases; and histopathological analysis of the liver and kidneys were used to evaluate the toxicity of S. platensis on these Wistar rats. Plasmatic hydroxymethyl glutaryl coenzyme A reductase (HMG CoA reductase) and lecithine cholesterol acyl transferase (LCAT) were performed to explain the lipid-lowering action of S. platensis. Histopathological analysis of the liver and kidneys was performed.

RESULTS

Our results show a decrease in total cholesterol for male rats (from 84 to 74 mg/dl) when the dose of S. platensis increased; this reduction of the total cholesterol level in male rats was significant at 500 mg/kg. There was also a significant inhibition of HMG CoA reductase in a dose dependent manner between 25 and 84.5 fold compared to the control in both male and female groups. At the dose of 250 mg/kg bw, the level of LCAT was higher compared with other groups and control, but the difference was not statistically significant. A slight inflammation in the liver and the mesangial hyperplasia of the renal glomeruli was revealed by the histopathological investigation in subacute toxicity.

CONCLUSION

Spirulina platensis from Cameroon appears to have little toxic effects and may demonstrate hypolipidemic activity through the activation of LCAT.

Circulating sterols as predictors of early allograft dysfunction and clinical outcome in patients undergoing liver transplantation

INTRODUCTION

Sensitive and specific assessment of the hepatic graft metabolism after liver transplantation (LTX) is essential for early detection of postoperative dysfunction implying the need for consecutive therapeutic interventions.

OBJECTIVES

Here, we assessed circulating liver metabolites of the cholesterol pathway, amino acids and acylcarnitines and evaluated their predictive value on early allograft dysfunction (EAD) and clinical outcome in the context of LTX.

METHODS

The metabolites were quantified in the plasma of 40 liver graft recipients one day pre- and 10 days post-LTX by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Plant sterols as well as cholesterol and its precursors were determined in the free and esterified form; lanosterol in the free form only. Metabolites and esterification ratios were compared to the model for early allograft function scoring (MEAF) which is calculated at day 3 post-LTX from routine parameters defining EAD.

RESULTS

The hepatic esterification ratio of all sterols, but not amino acids and acylcarnitine concentrations, showed substantial metabolic disturbances post-LTX and correlated to the MEAF. In ROC analysis, the low esterification ratio of β-sitosterol and stigmasterol from day 1 and of the other sterols from day 3 were predictive for a high MEAF, i.e. EAD. Additionally, the ratio of esterified β-sitosterol and free lanosterol were predictive for all days and the esterification ratio of the other sterols at day 3 or 4 post-LTX for 3-month mortality.

CONCLUSION

Low ratios of circulating esterified sterols are associated with a high risk of EAD and impaired clinical outcome in the early postoperative phase following LTX.

Co-existence of classic familial lecithin-cholesterol acyl transferase deficiency and fish eye disease in the same family

We report a family with a rare genetic disorder arising out of mutation in the gene that encodes for the enzyme lecithin-cholesterol acyltransferase (LCAT). The proband presented with nephrotic syndrome, hemolytic anemia, cloudy cornea, and dyslipidemia. Kidney biopsy showed certain characteristic features to suggest LCAT deficiency, and the enzyme activity in the serum was undetectable. Mother and younger sister showed corneal opacity and dyslipidemia but no renal or hematological involvement. These two members had a milder manifestation of the disease called fish eye disease. This case is presented to emphasize the importance of taking family history and doing a good clinical examination in patients with nephrotic syndrome and carefully analyze the lipid fractions in these subset of patients.

A review on lecithin:cholesterol acyltransferase deficiency

Lecithin cholesterol acyl transferase (LCAT) is a plasma enzyme which esterifies cholesterol, and plays a key role in the metabolism of high-density lipoprotein cholesterol (HDL-C). Genetic disorders of LCAT are associated with lipoprotein abnormalities including low levels of HDL-C and presence of lipoprotein X, and clinical features mainly corneal opacities, changes in erythrocyte morphology and renal failure. Recombinant LCAT is being developed for the treatment of patients with LCAT deficiency.

Computationally Modeling Lipid Metabolism and Aging: A Mini-review

One of the greatest challenges in biology is to improve the understanding of the mechanisms which underpin aging and how these affect health. The need to better understand aging is amplified by demographic changes, which have caused a gradual increase in the global population of older people. Aging western populations have resulted in a rise in the prevalence of age-related pathologies. Of these diseases, cardiovascular disease is the most common underlying condition in older people. The dysregulation of lipid metabolism due to aging impinges significantly on cardiovascular health. However, the multifaceted nature of lipid metabolism and the complexities of its interaction with aging make it challenging to understand by conventional means. To address this challenge computational modeling, a key component of the systems biology paradigm is being used to study the dynamics of lipid metabolism. This mini-review briefly outlines the key regulators of lipid metabolism, their dysregulation, and how computational modeling is being used to gain an increased insight into this system.

Characteristic, polymorphism and expression distribution of LCAT gene in a Mongolian gerbil model for hyperlipidemia

This study aims to evaluate the genetic basis and activity of lecithin cholesterol acyltransferase (LCAT) in a novel Mongolian gerbil model for hyperlipidemia. Gerbils may be susceptible to high fat and cholesterol (HF/HC) diets, which can rapidly lead to the development of hyperlipidemia. Approximately 10-30% of gerbils that are over 8months old and fed controlled diets spontaneously develop hyperlipidemia. Using the HF/HC diet model, we detected triglycerides (TG), total cholesterol (TC), HDL (high density lipoprotein)-C, LDL (low density lipoprotein)-C and LCAT in both old (>8months) and young gerbils. The TC and HDL-C levels were two times higher in old gerbils compared with young gerbils (P<0.01). However, in the old group the LCAT activity fell slightly compared with the normal lipidemia group. It is reasonable to hypothesize that this may be associated with single nucleotide polymorphisms of the LCAT gene. We cloned this gene to investigate the sensitivity of the gerbil to the HF/HC diet and spontaneous hyperlipidemia. The entire LCAT gene was cloned by splicing sequences of RACE (rapid amplification of cDNA ends) and nest-PCR products (AN: KC533867.1). The results showed that the 3683base pair gene consists of six exons and five introns. The LCAT protein consists of 444 amino acid (AA) residues, which are analogous to the human LCAT gene, and includes 24 signal peptide AA and 420 mature protein AA. Expression of LCAT was detected in the kidney, spleen and adrenal tissue, apart from the liver, by immunohistochemistry. The abundance of the protein was greater in the older group compared with the control group. Polymorphisms were analyzed by PCR-SSCP (PCR-single-strand conformation polymorphism) but none were found in 444 animals of the ZCLA closed population (a Chinese cultured laboratory gerbil population).

Lecithin:cholesterol acyltransferase: old friend or foe in atherosclerosis?

Lecithin:cholesterol acyltransferase (LCAT) is a key enzyme that catalyzes the esterification of free cholesterol in plasma lipoproteins and plays a critical role in high-density lipoprotein (HDL) metabolism. Deficiency leads to accumulation of nascent preβ-HDL due to impaired maturation of HDL particles, whereas enhanced expression is associated with the formation of large, apoE-rich HDL(1) particles. In addition to its function in HDL metabolism, LCAT was believed to be an important driving force behind macrophage reverse cholesterol transport (RCT) and, therefore, has been a subject of great interest in cardiovascular research since its discovery in 1962. Although half a century has passed, the importance of LCAT for atheroprotection is still under intense debate. This review provides a comprehensive overview of the insights that have been gained in the past 50 years on the biochemistry of LCAT, the role of LCAT in lipoprotein metabolism and the pathogenesis of atherosclerosis in animal models, and its impact on cardiovascular disease in humans.

Small molecule activation of lecithin cholesterol acyltransferase modulates lipoprotein metabolism in mice and hamsters

The objective was to assess whether pharmacological activation of lecithin cholesterol acyltransferase (LCAT) could exert beneficial effects on lipoprotein metabolism. A putative small molecule activator (compound A) was used as a tool compound in in vitro and in vivo studies. Compound A increased LCAT activity in vitro in plasma from mouse, hamster, rhesus monkey, and human. To assess the acute pharmacodynamic effects of compound A, C57Bl/6 mice and hamsters received a single dose (20 mg/kg) of compound A. Both species displayed a significant increase in high-density lipoprotein cholesterol (HDLc) and a significant decrease in non-HDLc and triglycerides acutely after dosing; these changes tracked with ex vivo plasma LCAT activity. To examine compound A's chronic effect on lipoprotein metabolism, hamsters received a daily dosing of vehicle or of 20 or 60 mg/kg of compound A for 2 weeks. At study termination, compound treatment resulted in a significant increase in HDLc, HDL particle size, plasma apolipoprotein A-I level, and plasma cholesteryl ester (CE) to free cholesterol ratio, and a significant reduction in very low-density lipoprotein cholesterol. The increase in plasma CE mirrored the increase in HDL CE. Triglycerides trended toward a dose-dependent decrease in very low-density lipoprotein and HDL, with multiple triglyceride species reaching statistical significance. Gallbladder bile acids content displayed a significant and more than 2-fold increase with the 60 mg/kg treatment. We characterized pharmacological activation of LCAT by a small molecule extensively for the first time, and our findings support the potential of this approach in treating dyslipidemia and atherosclerosis; our analyses also provide mechanistic insight on LCAT's role in lipoprotein metabolism.

Synthesis of carboxymethylated and quaternized chitosans and their therapeutic effect on nonalcoholic Fatty liver disease

O-Carboxymethyl chitosan (O-CMCs) and N-((2-hydroxy-3-N,N-dimethylhexadecylammonium)propyl)chitosan chloride (N-CQCs) were synthesized for nonalcoholic fatty liver disease (NAFLD) treatment. The weight-average weight and substitution degree of O-CMCs and N-CQCs were 6.5 × 10(4) and 0.72 and 7.9 × 10(4) and 0.21, respectively. O-CMCs was negatively charged with a zeta-potential value of -31.82 mV, whereas that of N-CQCs was +36.1 mV, and both showed low cytotoxcity. Serum lipid level and liver fat accumulation were reduced with chitosan and its two derivatives. Furthermore, mRNA and protein expression assay of hepatic lipid metabolism enzymes and low-density lipoprotein receptor (LDL-R) were observed by RT-PCR and Western blot. Results showed that N-CQCs exhibited a more evident desired effect than chitosan and O-CMCs, indicating that amphiphilicity, solubility, and surface charge of chitosan and its two derivatives played roles in the expression of hepatic lipid metabolism enzymes and LDL-R. Therefore, dietary supplementation of O-CMCs and N-CQCs can alleviate the high fat diet induced aberrations related to NAFLD by their antilipidemic property.

AAV8-mediated long-term expression of human LCAT significantly improves lipid profiles in hCETP;Ldlr(+/-) mice

Lecithin:cholesterol acyltransferase (LCAT) is the key circulating enzyme responsible for high-density lipoprotein (HDL) cholesterol esterification, HDL maturation, and potentially reverse cholesterol transport. To further explore LCAT's mechanism of action on lipoprotein metabolism, we employed adeno-associated viral vector (AAV) serotype 8 to achieve long-term (32-week) high level expression of human LCAT in hCETP;Ldlr(+/-) mice, and characterized the lipid profiles in detail. The mice had a marked increase in HDL cholesterol, HDL particle size, and significant reduction in low-density lipoprotein (LDL) cholesterol, plasma triglycerides, and plasma apoB. Plasma LCAT activity significantly increased with humanized substrate specificity. HDL cholesteryl esters increased in a fashion that fits human LCAT specificity. HDL phosphatidylcholines trended toward decrease, with no change observed for HDL lysophosphatidylcholines. Triglycerides reduction appeared to reside in all lipoprotein particles (very low-density lipoprotein (VLDL), LDL, and HDL), with HDL triglycerides composition highly reflective of VLDL, suggesting that changes in HDL triglycerides were primarily driven by the altered triglycerides metabolism in VLDL. In summary, in this human-like model for lipoprotein metabolism, AAV8-mediated overexpression of human LCAT resulted in profound changes in plasma lipid profiles. Detailed lipid analyses in the lipoprotein particles suggest that LCAT's beneficial effect on lipid metabolism includes not only enhanced HDL cholesterol esterification but also improved metabolism of apoB-containing particles and triglycerides. Our findings thus shed new light on LCAT's mechanism of action and lend support to its therapeutic potential in treating dyslipidemia.

Reverse cholesterol transport revisited: contribution of biliary versus intestinal cholesterol excretion

Reverse cholesterol transport (RCT) is usually defined as high-density lipoprotein-mediated transport of excess cholesterol from peripheral tissues, including cholesterol-laden macrophages in vessel walls, to the liver. From the liver, cholesterol can then be removed from the body via secretion into the bile for eventual disposal via the feces. According to this paradigm, high plasma high-density lipoprotein levels accelerate RCT and hence are atheroprotective. New insights in individual steps of the RCT pathway, in part derived from innovative mouse models, indicate that the classical concept of RCT may require modification.

Mechanism of cholesterol efflux in humans after infusion of reconstituted high-density lipoprotein

OBJECTIVES

Infusion of reconstituted HDL (rHDL) leads to changes in HDL metabolism as well as to an increased capacity of plasma to support cholesterol efflux providing an opportunity to investigate mechanisms linking cholesterol efflux to changes in plasma HDL.

METHODS AND RESULTS

Patient plasmas after infusion of rHDL were tested ex vivo for their capacity to stimulate cholesterol efflux. Reconstituted HDL enhanced mobilization of cholesterol from tissues in vivo as shown by rising HDL cholesterol concentrations over the infusion period. Infusion of rHDL in vivo led to increased cholesterol efflux ex vivo; surprisingly, removing apoB-containing lipoproteins while preserving all HDL subfractions eliminated this increase. Infusion of rHDL led to the remodelling of plasma HDL; however, the capacity of plasma to support cholesterol efflux did not correlate with changes in the concentrations of any of HDL subfractions. Unmodified rHDL accounted for only a proportion of the increment in cholesterol efflux capacity. Furthermore, studies using HeLa and BHK cells overexpressing ABCA1, ABCG1, and SR-B1 showed that the contribution of these cellular mediators of cholesterol efflux to the enhanced capacity of plasma for the efflux was minimal.

CONCLUSION

Enhanced cholesterol efflux from tissues requires the presence of apoB-containing lipoproteins and may involve enhanced flow of cholesterol through multiple components of the reverse cholesterol transport pathway rather than being determined by a specific HDL subfraction.

Adenoviral expression of human lecithin-cholesterol acyltransferase in nonhuman primates leads to an antiatherogenic lipoprotein phenotype by increasing high-density lipoprotein and lowering low-density lipoprotein

Lecithin-cholesterol acyltransferase (LCAT), a key enzyme in high-density lipoprotein (HDL) metabolism, has been proposed to have atheroprotective properties by promoting reverse cholesterol transport. Overexpression of LCAT in various animal models, however, has led to conflicting results on its overall effect on lipoproteins and atherosclerosis. In this study, the effect of overexpression of LCAT in nonhuman primates on lipoprotein metabolism is examined. Human LCAT was expressed with adenovirus in squirrel monkeys (n = 8), resulting on day 4 in a 22-fold increase of LCAT activity (257 +/- 23 vs 5618 +/- 799 nmol mL(-1) h(-1), P < .0001). At its peak, LCAT was found to nearly double the level of HDL cholesterol from baseline (113 +/- 7 vs 260 +/- 24 mg/dL, P < .01). High-density lipoprotein formed after treatment with the adenovirus was larger in size, as assessed by fast protein liquid chromatography (FPLC) analysis. By kinetic studies, it was determined that there was a decrease in apolipoprotein (Apo) A-I resident time (0.373 +/- 0.027 vs 0.685 +/- 0.045 d(-1), P < .0001) and almost a doubling in the ApoA-I synthetic rate (22 +/- 2 vs 41 +/- 3 mg kg(-1) d(-1), P < .0001), but no overall change in ApoA-I levels. In addition, increased expression of LCAT was associated with a 37% reduction of ApoB levels (12 +/- 1 vs 19 +/- 1 mg/dL, P < .05) due to increased low-density lipoprotein catabolism (fractional catabolic rate = 1.7 +/- 0.1 d(-1) in controls vs 4.2 +/- 0.3 d(-1) in LCAT-treated group, P < .05). In summary, overexpression of LCAT in nonhuman primates leads to an antiatherogenic lipoprotein profile by increasing HDL cholesterol and lowering ApoB, thus making LCAT a potential drug target for reducing atherosclerosis.

Inhibition of Cholesteryl Ester Transfer Protein Activity by JTT-705 Increases Apolipoprotein E–Containing High-Density Lipoprotein and Favorably Affects the Function and Enzyme Composition of High-Density Lipoprotein in Rabbits

Background— Inhibition of cholesteryl ester transfer protein (CETP) is an efficient way to increase high-density lipoprotein (HDL) levels in humans. We investigated the effects of the inhibition of CETP activity by a CETP inhibitor, JTT-705, on the function and composition of HDL particles.

Methods and Results— Japanese white rabbits were fed either normal rabbit chow LRC-4 (n=10) or a food admixture of LRC-4 and 0.75% JTT-705 (n=10) for 7 months. JTT-705 significantly inhibited CETP activities, increased HDL cholesterol (HDL-C) levels and the ratio of HDL 2 -C/HDL 3 -C, and decreased the fractional esterification rate of cholesterol in HDL, indicating preferentially increased large HDL particles. Treatment with JTT-705 increased all of the 3 charge-based HDL subfractions as determined by capillary isotachophoresis: fast-migrating, intermediate-migrating, and slow-migrating HDL. The percentage of slow HDL, ie, apolipoprotein E (apoE)-containing HDL and levels of apoE in HDL fraction, was also increased. JTT-705 treatment increased serum paraoxonase activity and HDL-associated platelet-activating factor acetylhydrolase activity, but decreased the plasma lysophosphatidylcholine concentration.

Conclusion— Inhibition of CETP activity by JTT-705 not only increased the quantity of HDL, including HDL-C levels and charge-based HDL subfractions, but also favorably affected the size distribution of HDL subpopulations and the apolipoprotein and enzyme composition of HDL in rabbits.

Selective uptake of high density lipoproteins cholesteryl ester in the dog, a species lacking in cholesteryl ester transfer protein activity

Amongst the processes involved in the reverse cholesterol transport (RCT) from organs to liver, including high density lipoproteins-apolipoprotein AI (HDL-apoAI) dependent tissue uptake and cholesteryl ester transfer protein (CETP)-mediated transfers, the selective uptake of cholesteryl ester (CE) is of increasing interest through its antiatherogenic role. The purpose of this report is to develop a simple protocol allowing study of this process in an animal model with easier quantification of CE selective uptake. The dog was chosen essentially because this animal has a low CETP activity and an appropriate size to conduce a kinetic study. Tracer kinetics were performed to estimate in vivo the contributions of the pathways involved in HDL-CE turnover in dogs. Stable isotopes, 13C-acetate and D3-leucine as labeled precursors of CE and apoAI, were infused to fasting dogs. Isotopic enrichments were monitored in plasma unesterified cholesterol and in HDL-CE and apoAI by mass spectrometry. Kinetics were analyzed using compartmental modeling. Results concerned the measurement of the activity of cholesterol esterification (0.13+/-0.032 h(-1)), rate of HDL-apoAI catabolism (0.024+/-0.012 h(-1)), HDL-CE turnover (0.062+/-0.010 h(-1)) and CE selective uptake (0.038+/-0.014 h(-1)). Our results show that CE in dogs is mainly eliminated by selective uptake of HDL-CE (60% of HDL-CE turnover), unlike in other species studied by similar methods in our laboratory. This study shows that among species used to analyze cholesterol metabolism, the dog appears to be the animal in whom HDL-CE selective uptake represents the largest part of HDL-CE turnover.

[Alterations in cholesterol, triglyceride and total phospholipid levels in plasma of Callithrix jacchus (sagüi) reinfected by Schistosoma mansoni]

Little information is available on the lipid changes caused by Schistosoma mansoni reinfection. In this work it was evaluated alteration in the plasma lipids due to one reinfection by Schistosoma mansoni in the non human primate Callithrix jacchus (sagüi). Blood samples from C. jacchus, prior and after 60 days infection and reinfection, were collected by intravenous puncture, anticoagulated with EDTA (1mg/mL) and centrifuged at 2,500 xg, in order to obtain the plasma. Total cholesterol, cholesteryl ester, total phospholipid and triglyceride levels were determined by spectrophotometer methods. The results showed that there are significant reduction in cholesterol total, cholesteryl ester, total phospholipid and triglyceride concentrations in plasma of animals reinfected by Schistosoma mansoni, in comparison to the same animals prior and after one infection. This study showed that a second infection of Callithrix jacchus by Schistosoma mansoni causes plasma lipid alterations, which are more significant than after a single infection.

The effects of oral anti-hyperglycaemic medications on serum lipid profiles in patients with type 2 diabetes

AIM

Patients with type 2 diabetes often have dyslipidaemia, putting them at risk of cardiovascular disease, and are frequently treated with oral anti-hyperglycaemic medications (OAMs). This review compares the effects of OAMs on serum lipids [total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TGs) and free fatty acids (FFAs)] in patients with type 2 diabetes.

METHODS

medline was searched for entries indexed from January 1966 to November 2002; search terms included the names of OAMs and serum lipids, limited to English language and human subjects. We selected clinical studies in type 2 diabetes of OAM monotherapy that included serum lipid data, treated all patients in a treatment group with the same drug, used therapeutic OAM doses not higher than the maximum recommended in the USA, compared therapy with baseline or placebo and specified statistical tests used. One unblinded investigator selected studies for inclusion. Data reported include number of patients, study length, OAM dose, serum lipid data at baseline and endpoint, p-values and statistical tests.

RESULTS

Data on the serum lipid effects of sulphonylureas, repaglinide, nateglinide and miglitol were inconclusive. Acarbose increased HDL-C and decreased LDL-C and voglibose reduced TC. Metformin at higher doses reduced TC; data on its effects on other lipids were inconclusive. Rosiglitazone increased LDL-C, HDL-C and TC and reduced FFAs but had no effect on TGs. Pioglitazone increased HDL-C and reduced TGs and FFAs but did not affect LDL-C or TC.

CONCLUSIONS

Lipid changes as a result of improved glycaemic control are not uniform findings associated with anti-diabetic therapy. Only metformin, acarbose, voglibose, rosiglitazone and pioglitazone had significant effects on the lipid profile. These effects should be considered when selecting OAMs for patients with type 2 diabetes.

The levels of soluble amyloid beta in different high density lipoprotein subfractions distinguish Alzheimer's and normal aging cerebrospinal fluid: implication for brain cholesterol pathology?

Several previous studies reported the association of the soluble form of amyloid beta (sA beta) protein, a major constituent of amyloid deposits in Alzheimer's disease (AD), with normal blood, cerebrospinal fluid (CSF) and central nervous system high density lipoproteins (HDLs). The present report aimed to elucidate the pattern of sA beta and apolipoprotein (apo) distribution in AD CSF-HDL subfractions. We studied AD CSF-HDL subfractions by SDS/PAGE and immunoblot analysis after CSF fractionation via density flotation ultracentrifugation. AD CSF was characterized by (i) increased sA beta and apo content of the HDL(1), and (ii) sA beta association with apoE and apoJ in HDL(2), HDL(3) and very high density lipoproteins. The finding supports our proposed hypothesis that upregulation of brain cholesterol dynamics is a fundamental event in the pathophysiology of AD and that sA beta binding to apo and lipid may have important structure-functional consequences.

Lecithin-cholesterol acyltransferase: role in lipoprotein metabolism, reverse cholesterol transport and atherosclerosis

In the past several years significant advances have been made in our understanding of lecithin-cholesterol acyltransferase (LCAT) function. LCAT beneficially alters the plasma concentrations of apolipoprotein B-containing lipoproteins, as well as HDL. In addition, its proposed role in facilitating reverse cholesterol transport and modulating atherosclerosis has been demonstrated in vivo. Analysis of LCAT transgenic animals has established the importance of evaluating HDL function, as well as HDL plasma levels, to predict atherogenic risk.