scholarly journals Human ApoA-I Overexpression Enhances Macrophage-Specific Reverse Cholesterol Transport but Fails to Prevent Inherited Diabesity in Mice

2019 ◽  
Vol 20 (3) ◽  
pp. 655 ◽  
Author(s):  
Karen Méndez-Lara ◽  
Núria Farré ◽  
David Santos ◽  
Andrea Rivas-Urbina ◽  
Jari Metso ◽  
...  
Keyword(s):  
Weight Gain ◽  
Fatty Liver ◽  
Reverse Cholesterol Transport ◽  
Caloric Intake ◽  
Density Lipoprotein ◽  
Ldl Oxidation ◽  
Cholesterol Transport ◽  
Metabolic Complications ◽  
Hdl Function

Human apolipoprotein A-I (hApoA-I) overexpression improves high-density lipoprotein (HDL) function and the metabolic complications of obesity. We used a mouse model of diabesity, the db/db mouse, to examine the effects of hApoA-I on the two main functional properties of HDL, i.e., macrophage-specific reverse cholesterol transport (m-RCT) in vivo and the antioxidant potential, as well as the phenotypic features of obesity. HApoA-I transgenic (hA-I) mice were bred with nonobese control (db/+) mice to generate hApoA-I-overexpressing db/+ offspring, which were subsequently bred to obtain hA-I-db/db mice. Overexpression of hApoA-I significantly increased weight gain and the incidence of fatty liver in db/db mice. Weight gain was mainly explained by the increased caloric intake of hA-I-db/db mice (>1.2-fold). Overexpression of hApoA-I also produced a mixed type of dyslipidemia in db/db mice. Despite these deleterious effects, the overexpression of hApoA-I partially restored m-RCT in db/db mice to levels similar to nonobese control mice. Moreover, HDL from hA-I-db/db mice also enhanced the protection against low-density lipoprotein (LDL) oxidation compared with HDL from db/db mice. In conclusion, overexpression of hApoA-I in db/db mice enhanced two main anti-atherogenic HDL properties while exacerbating weight gain and the fatty liver phenotype. These adverse metabolic side-effects were also observed in obese mice subjected to long-term HDL-based therapies in independent studies and might raise concerns regarding the use of hApoA-I-mediated therapy in obese humans.

scholarly journals Evidence for reverse cholesterol transport in vivo from liver endothelial cells to parenchymal cells and bile by high-density lipoprotein

1990 ◽  
Vol 268 (3) ◽  
pp. 685-691 ◽  
Author(s):  
H F Bakkeren ◽  
F Kuipers ◽  
R J Vonk ◽  
T J C Van Berkel
Keyword(s):  
Endothelial Cells ◽  
High Density Lipoprotein ◽  
Kupffer Cells ◽  
Reverse Cholesterol Transport ◽  
Density Lipoprotein ◽  
Cholesterol Transport ◽  
Cholesterol Esters ◽  
Liver Endothelial Cells ◽  
Parenchymal Cells

Acetylated low-density lipoprotein (acetyl-LDL), biologically labelled in the cholesterol moiety of cholesteryl oleate, was injected into control and oestrogen-treated rats. The serum clearance, the distribution among the various lipoproteins, the hepatic localization and the biliary secretion of the [3H]cholesterol moiety were determined at various times after injection. In order to monitor the intrahepatic metabolism of the cholesterol esters of acetyl-LDL in vivo, the liver was subdivided into parenchymal, endothelial and Kupffer cells by a low-temperature cell-isolation procedure. In both control and oestrogen-treated rats, acetyl-LDL is rapidly cleared from the circulation, mainly by the liver endothelial cells. Subsequently, the cholesterol esters are hydrolysed, and within 1 h after injection, about 60% of the cell- associated cholesterol is released. The [3H]cholesterol is mainly recovered in the high-density lipoprotein (HDL) range of the serum of control rats, while low levels of radioactivity are detected in serum of oestrogen-treated rats. In control rats cholesterol is transported from endothelial cells to parenchymal cells (reverse cholesterol transport), where it is converted into bile acids and secreted into bile. The data thus provide evidence that HDL can serve as acceptors for cholesterol from endothelial cells in vivo, whereby efficient delivery to the parenchymal cells and bile is assured. In oestrogen-treated rats the radioactivity from the endothelial cells is released with similar kinetics as in control rats. However, only a small percentage of radioactivity is found in the HDL fraction and an increased uptake of radioactivity in Kupffer cells is observed. The secretion of radioactivity into bile is greatly delayed in oestrogen-treated rats. It is concluded that, in the absence of extracellular lipoproteins, endothelial cells can still release cholesterol, although for efficient transport to liver parenchymal cells and bile, HDL is indispensable.

scholarly journals Reverse cholesterol transport in the rat. Studies using the isolated perfused spleen in conjunction with the perfused liver

1991 ◽  
Vol 279 (2) ◽  
pp. 503-508 ◽  
Author(s):  
M A Mindham ◽  
P A Mayes
Keyword(s):  
Reverse Cholesterol Transport ◽  
Liver Perfusion ◽  
Density Lipoprotein ◽  
Cholesterol Transport ◽  
Perfused Liver ◽  
Unesterified Cholesterol ◽  
Rapid Exchange ◽  
Net Release ◽  
Complete Process

1. A new method combining the use of an isolated perfused extrahepatic tissue with a perfused liver was developed as a model system for the study of reverse cholesterol transport. Rat spleens, initially labelled in vivo with [3H]cholesterol, were perfused for 3 h with whole blood. The spleen was then replaced with an isolated rat liver, whose uptake of cholesterol from the spleen-derived blood and excretion of cholesterol into bile constituents were determined. 2. During spleen perfusion, a net release of cholesterol mass and radioactivity to lipoproteins was observed. 3. During liver perfusion, there was also a rapid exchange or transport of unesterified cholesterol between high-density lipoprotein (HDL) and the liver, in particular with HDL2 (d = 1.085-1.125). 4. The liver showed an increased uptake of cholesteryl ester from serum that had previously been used in spleen perfusion. 5. Approximately half of the [3H]cholesterol released by the spleen was recovered in erythrocytes. During subsequent liver perfusion there was a substantial uptake of radioactivity from the erythrocytes, although less than that recorded from serum lipoproteins. 6. In all experiments there was significant excretion of [3H]cholesterol into bile; most (85%) was in bile acids. Thus the complete process of reverse cholesterol transport is observed in this dual-perfusion system.

Abstract P220: The Effect of Diet-Induced Weight Loss on HDL Functionality in Individuals with Metabolic Syndrome: Investigating Alteration of the Initial Step in Reverse Cholesterol Transport as a Function of Plasma Lipoprotein Composition

Circulation ◽  
2012 ◽  
Vol 125 (suppl_10) ◽  
Author(s):  
Madhuri M Vasudevan ◽  
Urban Tchoua ◽  
Baiba Gillard ◽  
Hu Yu Lin ◽  
Peter Jones ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Weight Loss ◽  
Reverse Cholesterol Transport ◽  
Cholesterol Efflux ◽  
Density Lipoprotein ◽  
Lipoprotein Cholesterol ◽  
Atherogenic Dyslipidemia ◽  
Cholesterol Transport ◽  
Hdl Function ◽  
Macrophage Cholesterol Efflux

The prevalence of metabolic syndrome (MetS) with obesity-linked diabetes continues to increase globally and is associated with atherogenic dyslipidemia characterized by high triglycerides (TG), small, dense low-density lipoprotein cholesterol (LDL-C), and low high-density lipoprotein cholesterol (HDL-C) levels. HDL orchestrates the reverse cholesterol transport (RCT) process, initiated by macrophage cholesterol efflux (MCE). The traditional hypothesis is that individuals with dyslipidemia have impaired RCT that leads to atherogenesis. However, a recent study showed that one metric of HDL function, macrophage cholesterol efflux (MCE) to diluted patient plasma, inversely correlated with atherosclerotic burden, independent of plasma HDL-C levels. Moreover, cholesterol efflux from ABCA1-upregulated macrophage cell lines to sera of diabetic hypertriglyceridemic subjects is enhanced compared to normolipidemic (NL) controls. The effect of weight loss on MCE in obese individuals with MetS is unknown. The purpose of this study is to evaluate MCE in obese individuals with MetS as a function of plasma dyslipidemia, and to determine the effect of weight loss on the RCT process. We measured the rate of MCE from human monocytic leukemia THP1 cells to plasma of NL controls (n=24) and obese MetS (n=24) patients before and after 4 to 6 weeks of very low calorie, diet-induced weight loss. Weight loss in the MetS patients was significant, averaged 21.3 lbs, with concurrent significant decreases in TG, apoB, TC, LDL-C and non-HDL-C. Measures of insulin resistance, systolic blood pressure and kidney function improved with weight loss. HDL-C was not significantly altered, but apoA-I decreased with weight loss. MCE to plasma of obese MetS patients was higher than MCE to control plasma ((7.44 + 1.36) % vs (6.39 + 1.23) %, p=0.0069). MCE to plasma of obese MetS patients significantly decreased after weight loss (6.23 + 1.69) %, comparable to control values. MCE was strongly correlated to apoB levels (r 2 = 0.13 - 0.38), consistent with apoB lipoprotein function as a cholesterol sink. This was confirmed by size exclusion chromatography analysis of the distribution of effluxed cholesterol among plasma lipoproteins in 1 control and 2 Mets patients. In conclusion, obese patients with MetS demonstrate increased MCE, a measure of HDL function, compared to NL controls, which significantly decreases in response to diet-induced weight loss, concurrent with a reduction in triglyceride and apoB levels. These results suggest that the high apoB lipoprotein levels in MetS pateints facilitate MCE, and may at least partially compensate for the low HDL-C to promote RCT in these patients.

scholarly journals Effects of Native and Myeloperoxidase-Modified Apolipoprotein A-I on Reverse Cholesterol Transport and Atherosclerosis in Mice

2014 ◽  
Vol 34 (4) ◽  
pp. 779-789 ◽  
Author(s):  
Bernd Hewing ◽  
Saj Parathath ◽  
Tessa Barrett ◽  
Wing Ki Kellie Chung ◽  
Yaritzy M. Astudillo ◽  
...  
Keyword(s):  
Reverse Cholesterol Transport ◽  
Density Lipoprotein ◽  
Cholesterol Transport ◽  
Atherosclerotic Plaques ◽  
Beneficial Effects ◽  
Atp Binding Cassette Transporter ◽  
Apolipoprotein A ◽  
Deficient Mice ◽  
Mediated Oxidation

Objective— Preclinical and clinical studies have shown beneficial effects of infusions of apolipoprotein A-I (ApoA-I) on atherosclerosis. ApoA-I is also a target for myeloperoxidase-mediated oxidation, leading in vitro to a loss of its ability to promote ATP-binding cassette transporter A1-dependent macrophage cholesterol efflux. Therefore, we hypothesized that myeloperoxidase-mediated ApoA-I oxidation would impair its promotion of reverse cholesterol transport in vivo and the beneficial effects on atherosclerotic plaques. Approach and Results— ApoA-I −/− or apolipoprotein E–deficient mice were subcutaneously injected with native human ApoA-I, oxidized human ApoA-I (myeloperoxidase/hydrogen peroxide/chloride treated), or carrier. Although early postinjection (8 hours) levels of total ApoA-I in plasma were similar for native versus oxidized human ApoA-I, native ApoA-I primarily resided within the high-density lipoprotein fraction, whereas the majority of oxidized human ApoA-I was highly cross-linked and not high-density lipoprotein particle associated, consistent with impaired ATP-binding cassette transporter A1 interaction. In ApoA-I −/− mice, ApoA-I oxidation significantly impaired reverse cholesterol transport in vivo. In advanced aortic root atherosclerotic plaques of apolipoprotein E–deficient mice, native ApoA-I injections led to significant decreases in lipid content, macrophage number, and an increase in collagen content; in contrast, oxidized human ApoA-I failed to mediate these changes. The decrease in plaque macrophages with native ApoA-I was accompanied by significant induction of their chemokine receptor CCR7. Furthermore, only native ApoA-I injections led to a significant reduction of inflammatory M1 and increase in anti-inflammatory M2 macrophage markers in the plaques. Conclusions— Myeloperoxidase-mediated oxidation renders ApoA-I dysfunctional and unable to (1) promote reverse cholesterol transport, (2) mediate beneficial changes in the composition of atherosclerotic plaques, and (3) pacify the inflammatory status of plaque macrophages.

scholarly journals Phospholipid transfer protein deficiency in mice impairs macrophage reverse cholesterol transport in vivo

2016 ◽  
Vol 241 (13) ◽  
pp. 1466-1472 ◽  
Author(s):  
Yanhong Si ◽  
Ying Zhang ◽  
Xiaofeng Chen ◽  
Lei Zhai ◽  
Guanghai Zhou ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
Reverse Cholesterol Transport ◽  
Density Lipoprotein ◽  
High Density ◽  
Protein Deficiency ◽  
Cholesterol Transport ◽  
Phospholipid Transfer Protein ◽  
Transfer Protein ◽  
Phospholipid Transfer

Phospholipid transfer protein is expressed in various cell types and secreted into plasma, where it transfers phospholipids between lipoproteins and modulates the composition of high-density lipoprotein particles. Phospholipid transfer protein deficiency in vivo can lower high-density lipoprotein cholesterol level significantly and impact the biological quality of high-density lipoprotein. Considering high-density lipoprotein was a critical determinant for reverse cholesterol transport, we investigated the role of systemic phospholipid transfer protein deficiency in macrophage reverse cholesterol transport in vivo. After the littermate phospholipid transfer protein KO and WT mice were fed high-fat diet for one month, they were injected intraperitoneally with 3H-cholesterol-labeled and acLDL-loaded macrophages. Then the appearance of 3H-tracer in plasma, liver, bile, intestinal wall, and feces over 48 h was determined. Plasma lipid analysis indicated phospholipid transfer protein deficiency lowered total cholesterol, high-density lipoprotein-C and apolipoprotein A1 levels significantly but increased triglyceride level in mice. The isotope tracing experiment showed 3H-cholesterol of plasma was decreased by 68% for male and 62% for female, and 3H-tracer of bile was decreased by 37% for male and 21% for female in phospholipid transfer protein KO mice compared with WT mice. However, there was no difference in liver, and 3H-tracer of intestinal wall was increased by 43% for male and 27% for female. Finally, 3H-tracer of fecal excretion in phospholipid transfer protein KO mice was reduced significantly by 36% for male and 43% for female during 0–24 h period, but there was no significant difference during 24–48 h period. Meanwhile, Western Blot analysis showed the expressions of reverse cholesterol transport -related protein liver X receptor α (LXRα), ATP binding cassette transporter A1, and cholesterol 7α-hydroxylase A1 were upregulated in liver of phospholipid transfer protein KO mice compared with WT mice. These data reveal that systemic phospholipid transfer protein deficiency in mice impairs macrophage-specific reverse cholesterol transport in vivo.

Abstract 29: Alpha-1-antitrypsin Protects High Density Lipoprotein From Functional Inactivation by Elastase

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Scott M Gordon ◽  
Denis Sviridov ◽  
Toshihiro Sakurai ◽  
Lita Freeman ◽  
Alan T Remaley
Keyword(s):  
Reverse Cholesterol Transport ◽  
Density Lipoprotein ◽  
High Density ◽  
Beta Particle ◽  
High Density Lipoproteins ◽  
Cholesterol Transport ◽  
Important Species ◽  
Hdl Function ◽  
Functional Inactivation ◽  
Alpha 1 Antitrypsin

High density lipoproteins (HDL) are complexes of lipid and protein with several known atheroprotective functions. These functions are driven by specific lipids and proteins contained on the HDL particle and include reverse cholesterol transport, suppression of inflammation, and modulation of endothelial function. These activities are most important within atherosclerotic plaque, a harsh environment where HDL interact with macrophage foam cells, activated neutrophils, and dysfunctional endothelial cells. Neutrophils and macrophages secrete proteases, such as elastase, which damage structural components and soluble proteins and propagate inflammatory signaling. It has been suggested that, in plaque, HDL become damaged and dysfunctional. We recently characterized a subspecies of HDL that carries the protein alpha-1-antitrypsin (A1AT), an abundant plasma serine protease inhibitor. In the current study, we tested the hypothesis that A1AT enriched HDL are protected from proteolytic damage and functional inactivation by elastase, the main protease inhibited by A1AT. Human HDL was isolated by ultracentrifugation and was enriched with A1AT by co-incubation and unbound A1AT was removed. Treatment of native HDL with elastase resulted in significant proteolytic degradation of both apoA-I and apoA-II, visualized by coomassie stained SDS-PAGE. Analysis of lipoprotein size by one dimensional native gel electrophoresis revealed that pre-beta HDL were completely degraded by elastase. Compared to native HDL, A1AT enriched HDL samples were protected from protein and pre-beta particle degradation by elastase. We next tested the effect of elastase treatment on HDL function. In native HDL, elastase had damaging effects on ABCA1 mediated cholesterol efflux (-32%; p<0.0001) and the ability to esterify free cholesterol (-14%; p<0.02). A1AT enriched HDL displayed no loss of functionality upon treatment with elastase. Both of these activities are required for HDL to perform what is thought to be its most important function, reverse cholesterol transport. In conclusion, the data presented indicate that HDL particles which contain A1AT may represent a functionally important species of HDL, which have an advantage in the protease-rich plaque environment.

Smoking prevents the intravascular remodeling of high-density lipoprotein particles: implications for reverse cholesterol transport

Metabolism ◽  
2004 ◽  
Vol 53 (7) ◽  
pp. 858-862 ◽  
Author(s):  
Águeda C.M Zaratin ◽  
Eder C.R Quintão ◽  
Andrei C Sposito ◽  
Valéria S Nunes ◽  
Ana Maria Lottenberg ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
Reverse Cholesterol Transport ◽  
Density Lipoprotein ◽  
High Density ◽  
Cholesterol Transport ◽  
Lipoprotein Particles
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