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 New Scavenger Receptor-Like Receptors for the Binding of Lipopolysaccharide to Liver Endothelial and Kupffer Cells

1998 ◽  
Vol 66 (11) ◽  
pp. 5107-5112 ◽  
Author(s):  
Marijke van Oosten ◽  
Erika van de Bilt ◽  
Theo J. C. van Berkel ◽  
Johan Kuiper
Keyword(s):  
Endothelial Cells ◽  
Kupffer Cells ◽  
Binding Sites ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Scavenger Receptors ◽  
Liver Endothelial Cells ◽  
Parenchymal Cells

ABSTRACT Lipopolysaccharide (LPS) is cleared from the blood mainly by the liver. The Kupffer cells are primarily responsible for this clearance; liver endothelial and parenchymal cells contribute to a lesser extent. Although several binding sites have been described, only CD14 is known to be involved in LPS signalling. Among the other LPS binding sites that have been identified are scavenger receptors. Scavenger receptor class A (SR-A) types I and II are expressed in the liver on endothelial cells and Kupffer cells, and a 95-kDa receptor, identified as macrosialin, is expressed on Kupffer cells. In this study, we examined the role of scavenger receptors in the binding of LPS by the liver in vivo and in vitro. Fucoidin, a scavenger receptor ligand, significantly reduced the clearance of 125I-LPS from the serum and decreased the liver uptake of 125I-LPS about 40%. Within the liver, the in vivo binding of 125I-LPS to Kupffer and liver endothelial cells was decreased 72 and 71%, respectively, while the binding of 125I-LPS to liver parenchymal cells increased 34% upon fucoidin preinjection. Poly(I) inhibited the binding of 125I-LPS to Kupffer and endothelial cells in vitro 73 and 78%, respectively, while poly(A) had no effect. LPS inhibited the binding of acetylated low-density lipoprotein (acLDL) to Kupffer and liver endothelial cells 40 and 55%, respectively, and the binding of oxidized LDL (oxLDL) to Kupffer and liver endothelial cells 65 and 61%, respectively. oxLDL and acLDL did not significantly inhibit the binding of LPS to these cells. We conclude that on both endothelial cells and Kupffer cells, LPS binds mainly to scavenger receptors, but SR-A and macrosialin contribute to a limited extent to the binding of LPS.

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.

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

scholarly journals Characterization of the interaction both in vitro and in vivo of tissue-type plasminogen activator (t-PA) with rat liver cells. Effects of monoclonal antibodies to t-PA

1992 ◽  
Vol 284 (2) ◽  
pp. 545-550 ◽  
Author(s):  
M Otter ◽  
J Kuiper ◽  
R Bos ◽  
D C Rijken ◽  
T J van Berkel
Keyword(s):  
Endothelial Cells ◽  
Mannose Receptor ◽  
Liver Cells ◽  
Tissue Type ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Liver Endothelial Cells ◽  
Parenchymal Cells

The interaction of 125I-labelled tissue-type plasminogen activator (125I-t-PA) with freshly isolated rat parenchymal and endothelial liver cells was studied. Binding experiments at 4 degrees C with parenchymal cells and endothelial liver cells indicated the presence of 68,000 and 44,000 high-affinity t-PA-binding sites, with an apparent Kd of 3.5 and 4 nM respectively. Association of 125I-t-PA with parenchymal cells was Ca(2+)-dependent and was not influenced by asialofetuin, a known ligand for the galactose receptor. Association of 125I-t-PA with liver endothelial cells was Ca(2+)-dependent and mannose-specific, since ovalbumin (a mannose-terminated glycoprotein) inhibited the cell association of t-PA. Association of 125I-t-PA with liver endothelial cells was inhibited by anti-(human mannose receptor) antiserum. Anti-(galactose receptor) IgG had no effect on 125I-t-PA association with either cell type. Degradation of 125I-t-PA at 37 degrees C by both cell types was inhibited by chloroquine or NH4Cl, indicating that t-PA is degraded lysosomally. in vitro experiments with three monoclonal antibodies (MAbs) demonstrated that anti-t-PA MAb 1-3-1 specifically decreased association of 125I-t-PA with the endothelial cells, and anti-t-PA Mab 7-8-4 inhibited association with the parenchymal cells. Results of competition experiments in rats in vivo with these antibodies were in agreement with findings in vitro. Both antibodies decreased the liver uptake of 125I-t-PA, while a combination of the two antibodies was even more effective in reducing the liver association of 125I-t-PA and increasing its plasma half-life. We conclude from these data that clearance of t-PA by the liver is regulated by at least two pathways, one on parenchymal cells (not galactose/mannose-mediated) and another on liver endothelial cells (mediated by a mannose receptor). Results with the MAbs imply that two distinct sites on the t-PA molecule are involved in binding to parenchymal cells and liver endothelial cells.

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