scholarly journals Regulation of the metabolism of lipoprotein-proteoglycan complexes in human monocyte-derived macrophages

1994 ◽  
Vol 301 (3) ◽  
pp. 675-681 ◽  
Author(s):  
P Vijayagopal
Keyword(s):  
Cholesteryl Ester ◽  
Conditioned Medium ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Cholesterol Esterification ◽  
Human Aorta ◽  
Ester Synthesis ◽  
Fibrous Plaque

Studies were performed to evaluate the effect of several factors on the metabolism of lipoprotein-proteoglycan complexes in human monocyte-derived macrophages. In vivo apoB-lipoprotein-proteoglycan complex was isolated from human aorta fibrous-plaque lesions and low-density lipoprotein (LDL)-proteoglycan complex was formed in vitro. Degradation of LDL-proteoglycan complex and cholesteryl ester synthesis mediated by the in vivo and in vitro complexes were lowest in freshly isolated monocytes. With the maturation of monocytes into macrophages, there was a dramatic rise in both. The degradation of the complex and the resultant stimulation of cholesterol esterification increased significantly with increasing cell density. Preincubation of macrophages in medium containing lipoprotein cholesterol did not down-regulate the subsequent degradation of LDL-proteoglycan complex. Macrophage-conditioned medium had a profound stimulatory effect on the degradation of LDL-proteoglycan complex and cholesterol esterification by mature macrophages and freshly isolated monocytes. The conditioned medium lost its stimulatory activity after boiling, dialysis and trypsin digestion. Macrophage activation with phorbol ester and bacterial lipopolysaccharide resulted in a marked suppression of the binding and degradation of the complex, as well as the complex-mediated cholesteryl ester synthesis. These results demonstrate that several factors regulate the metabolism of lipoprotein-proteoglycan complexes in human monocyte-derived macrophages.

scholarly journals Human monocyte-derived macrophages bind low-density-lipoprotein-proteoglycan complexes by a receptor different from the low-density-lipoprotein receptor

1993 ◽  
Vol 289 (3) ◽  
pp. 837-844 ◽  
Author(s):  
P Vijayagopal ◽  
S R Srinivasan ◽  
B Radhakrishnamurthy ◽  
G S Berenson
Keyword(s):  
Cholesteryl Ester ◽  
Proteolytic Enzymes ◽  
Chondroitin Sulphate ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Human Aorta ◽  
Minor Role ◽  
Low Density ◽  
Ester Synthesis

We have shown recently that lipoprotein-proteoglycan complexes isolated from human atherosclerotic lesions stimulated cholesteryl ester synthesis in human monocyte-derived macrophages [Vijayagopal, Srinivasan, Radhakrishnamurthy and Berenson (1992) Arterioscler. Thromb. 12, 237-249]. The present study was conducted to determine the mechanism of cellular uptake of the complexes. A chondroitin sulphate-dermatan sulphate proteoglycan was isolated from normal human aorta and complexed to 125I-labelled human low-density lipoprotein (LDL). The binding and degradation of 125I-LDL-proteoglycan complex were then studied in human monocyte-derived macrophages. The specific binding and degradation of the complex showed saturability and concentration-dependency. The Kd for binding was 1.5 x 10(-8) M, which was greater than that reported for LDL in monocyte-derived macrophages. Binding of the complex was not subject to down-regulation. Chloroquine inhibited degradation of the complex and the resultant stimulation of cholesteryl ester synthesis. Limited treatment of macrophages with proteolytic enzymes abolished binding and degradation of the complex significantly. Macrophages bound 125I-methyl-LDL-proteoglycan complex to the same extent as 125I-LDL-proteoglycan complex. Excess LDL and proteoglycan did not compete against the binding of the complex; however, excess acetyl-LDL competed for 61% of the binding. Likewise, excess LDL-proteoglycan complex inhibited the binding of 125I-acetyl-LDL by 64%. Polyinosinic acid and cytochalasin D inhibited the binding of 125I-LDL-proteoglycan complex by 60% and 36% respectively. Compared with that of acetyl-LDL, the degradation of LDL-proteoglycan complex was retarded in human macrophages. The results indicate that the uptake of LDL-proteoglycan complex in human monocyte-derived macrophages is not mediated through binding to the LDL receptor; but occurs predominantly via the scavenger receptor, with phagocytosis playing a minor role in the process.

Rapid transformation of [3H]cholesteryl ester m rat high-density lipoprotein: in vivo and in vitro studies

Steroids ◽  
1990 ◽  
Vol 55 (7) ◽  
pp. 308-313
Author(s):  
I.J. Goldberg ◽  
R.S. Rosenfeld ◽  
I. Paul ◽  
L.K. Miller ◽  
M.L. Tiell
Keyword(s):  
High Density Lipoprotein ◽  
Cholesteryl Ester ◽  
Density Lipoprotein ◽  
High Density ◽  
In Vitro Studies ◽  
Rapid Transformation

scholarly journals Inhibition of in vitro macrophage-induced low density lipoprotein oxidation by thyroid compounds

2003 ◽  
Vol 177 (1) ◽  
pp. 137-146 ◽  
Author(s):  
L Oziol ◽  
P Faure ◽  
N Bertrand ◽  
P Chomard
Keyword(s):  
Cell Viability ◽  
Antioxidant Capacity ◽  
Density Lipoprotein ◽  
Thiobarbituric Acid ◽  
Human Monocyte ◽  
Ldl Oxidation ◽  
Low Density ◽  
Redox Systems

Oxidized low density lipoproteins (LDL) are highly suspected of initiating the atherosclerosis process. Thyroid hormones and structural analogues have been reported to protect LDL from lipid peroxidation induced by Cu2+ or the free radical generator 2,2'-azobis-'2-amidinopropane' dihydrochloride in vitro. We have examined the effects of thyroid compounds on macrophage-induced LDL oxidation. Human monocyte-derived macrophages (differentiated U937 cells) were incubated for 24 h with LDL and different concentrations (0-20 microM) of 3,5,3'-triiodo-l -thyronine (T3), 3,5,3',5'-tetraiodo-L-thyronine (T4), 3,3',5'-tri-iodo-l -thyronine (rT3), the T3 acetic derivative (3,5,3'-tri-iodothyroacetic acid; TA3) or L-thyronine (T0) (experiment 1). Cells were also preincubated for 24 h with 1 or 10 microM of the compounds, washed twice, then incubated again for 24 h with LDL (experiment 2). Oxidation was evaluated by measurement of thiobarbituric acid-reactive substances (TBARS) and cell viability by lactate deshydrogenase release. In experiment 1, T0 had no effect, whereas the other compounds decreased LDL TBARS production, but T3 and TA3 were less active than T4 and rT3 (IC50: 11.0 +/- 2.6 and 8.1 +/- 0.8 vs 1.4 +/- 0.5 and 0.9 +/- 0.3 microM respectively). In experiment 2, the compounds at 1 microM had no effect; at 10 microM, T3 and rT3 slightly reduced LDL TBARS production, whereas TA3 and T4 inhibited it by about 50% and 70% respectively. TBARS released by the cells were also highly decreased by T3, T4, rT3 and TA3 in experiment 1, but only by T3 (30%) and T4 (70%) in experiment 2. Cell viability was not affected by the compounds except slightly by TA3 at 10 microM. The data suggested that the physico-chemical antioxidant capacity of thyroid compounds was modulated by their action on the intracellular redox systems of macrophage. Overall cellular effects of T3 led to a reduction of its antioxidant capacity whereas those of T4 increased it. Thus T4 might protect LDL against cellular oxidation in vivo more than T3.

scholarly journals An alternative procedure for incorporating radiolabelled cholesteryl ester into human plasma lipoproteins in vitro

1985 ◽  
Vol 226 (1) ◽  
pp. 319-322 ◽  
Author(s):  
D C K Roberts ◽  
N E Miller ◽  
S G L Price ◽  
D Crook ◽  
C Cortese ◽  
...  
Keyword(s):  
Cholesteryl Ester ◽  
Human Plasma ◽  
Specific Radioactivity ◽  
Density Lipoprotein ◽  
Plasma Lipoproteins ◽  
Cholesteryl Esters ◽  
Simple Method ◽  
High Specific Radioactivity

A simple method has been developed for labelling human plasma lipoproteins to high specific radioactivity with radioactive cholesteryl esters in vitro. After isolation by preparative ultracentrifugation, the selected lipoprotein was incubated for 30 min at 4 degrees C in human serum (d greater than 1.215) that had been prelabelled with [4-14C]cholesteryl oleate or [1,2-3H]cholesteryl linoleate, and was then re-isolated by ultracentrifugation. All major lipoprotein classes were labelled by the procedure. Specific radioactivities of up to 18 d.p.m. pmol-1 (46 d.p.m. ng-1) were achieved. When radiolabelled high-density lipoprotein was infused intravenously, the radioactive cholesteryl ester behaved in vivo indistinguishably from endogenous cholesteryl esters produced by the lecithin (phosphatidylcholine): cholesterol acyltransferase reaction.

scholarly journals Increased selective uptake in vivo and in vitro of oxidized cholesteryl esters from high-density lipoprotein by rat liver parenchymal cells

1996 ◽  
Vol 319 (2) ◽  
pp. 471-476 ◽  
Author(s):  
Kees FLUITER ◽  
Helene VIETSCH ◽  
Eric A. L. BIESSEN ◽  
Gert M. KOSTNER ◽  
Theo J. C. van BERKEL ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
Cholesteryl Ester ◽  
Density Lipoprotein ◽  
High Density ◽  
Biliary Secretion ◽  
Liver Uptake ◽  
Selective Uptake ◽  
Parenchymal Cells

Oxidation of low-density lipoprotein (LDL) leads initially to the formation of LDL-associated cholesteryl ester hydroperoxides (CEOOH). LDL-associated CEOOH can be transferred to high-density lipoprotein (HDL), and HDL-associated CEOOH are rapidly reduced to the corresponding hydroxides (CEOH) by an intrinsic peroxidase-like activity. We have now performed in vivo experiments to quantify the clearance rates and to identify the uptake sites of HDL-associated [3H]Ch18:2-OH in rats. Upon injection into rats, HDL-associated [3H]Ch18:2-OH is removed more rapidly from the circulation than HDL-associated [3H]Ch18:2. Two minutes after administration of [3H]Ch18:2-OH-HDL, 19.6±2.6% (S.E.M.; n = 4) of the label was taken up by the liver as compared with 2.4±0.25% (S.E.M.; n = 4) for [3H]Ch18:2-HDL. Organ distribution studies indicated that only the liver and adrenals exhibited preferential uptake of [3H]Ch18:2-OH as compared with [3H]Ch18:2, with the liver as the major site of uptake. A cell-separation procedure, employed 10 min after injection of [3H]Ch18:2-OH-HDL or [3H]Ch18:2-HDL, demonstrated that within the liver only parenchymal cells take up HDL-CE by the selective uptake pathway. Selective uptake by parenchymal cells of [3H]Ch18:2-OH was 3-fold higher than that of [3H]Ch18:2, while Kupffer and endothelial cell uptake of the lipid tracers reflected HDL holoparticle uptake (as analysed with iodinated versus cholesteryl ester-labelled HDL). The efficient uptake of [3H]Ch18:2-OH by parenchymal cells was coupled to a 3-fold increase in rate of radioactive bile acid secretion from [3H]Ch18:2-OH-HDL as compared with [3H]Ch18:2-HDL. In vitro studies with freshly isolated parenchymal cells showed that the association of [3H]Ch18:2-OH-HDL at 37 °C exceeded [3H]Ch18:2-HDL uptake almost 4-fold. Our results indicate that HDL-associated CEOH are efficiently and selectively removed from the blood circulation by the liver in vivo. The selective liver uptake is specifically exerted by parenchymal cells and coupled to a rapid biliary secretion pathway. The liver uptake and biliary secretion route may allow HDL to function as an efficient protection system against potentially atherogenic CEOOH.

Glycosylation of Low-Density Lipoprotein Enhances Cholesteryl Ester Synthesis in Human Monocyte-Derived Macrophages

Diabetes ◽  
1988 ◽  
Vol 37 (5) ◽  
pp. 550-557 ◽  
Author(s):  
M. F. Lopes-Virella ◽  
R. L. Klein ◽  
T. J. Lyons ◽  
H. C. Stevenson ◽  
J. L. Witztum
Keyword(s):  
Cholesteryl Ester ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Low Density ◽  
Ester Synthesis

Glycosylation of low-density lipoprotein enhances cholesteryl ester synthesis in human monocyte-derived macrophages

Diabetes ◽  
1988 ◽  
Vol 37 (5) ◽  
pp. 550-557 ◽  
Author(s):  
M. F. Lopes-Virella ◽  
R. L. Klein ◽  
T. J. Lyons ◽  
H. C. Stevenson ◽  
J. L. Witztum
Keyword(s):  
Cholesteryl Ester ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Low Density ◽  
Ester Synthesis

1,25-Dihydroxyvitamin D3-induced alterations of lipid metabolism in human monocyte-macrophages

1989 ◽  
Vol 257 (2) ◽  
pp. E290-E295
Author(s):  
J. B. Roullet ◽  
M. Haluska ◽  
O. Morchoisne ◽  
D. A. McCarron
Keyword(s):  
Lipid Metabolism ◽  
Cholesteryl Ester ◽  
Human Monocyte ◽  
Dietary Vitamin ◽  
Triglyceride Synthesis ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Triglyceride Accumulation

An in vivo atherogenic role of dietary vitamin D has been postulated. To address this hypothesis we sought to determine the in vitro effects of its active circulating metabolite, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on lipid metabolism in human monocyte-derived macrophages. When cultured 6 days in the presence of 10(-8) M 1,25(OH)2D3 monocyte-macrophages accumulated significantly more triglycerides than control cells: 987.6 +/- 26.8 vs. 779.3 +/- 24.1 micrograms/mg protein (P less than 0.001). Triglyceride accumulation was associated with a hormone-induced stimulation of triglyceride synthesis as determined by [3H]oleate incorporation into cellular triglycerides. The effect of the hormone was significant after 24 h and dose dependent [10(-11) to 10(-8) M 1,25(OH)2D3]. It was specific since 10(-7) M 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 did not stimulate triglyceride synthesis, and its magnitude decreased from 1 to 9 days of culture. 1,25(OH)2D3 (10(-8) M) modified the cholesteryl ester metabolism of monocyte-macrophages only in the presence of acetylated low-density lipoproteins (50 micrograms/ml); it induced a significant increase of cellular cholesteryl ester content (21.9 +/- 1.1 vs. 11.7 +/- 1.7 micrograms/mg protein; P less than 0.001) and of esterification rate of cholesterol measured by [3H]oleate incorporation into cellular cholesteryl esters (17.2 +/- 0.9 vs. 6.5 +/- 0.3 nmol.mg protein-1.24 h-1; P less than 0.001) by comparison with control cells. These results show that 1,25(OH)2D3 alters in vitro lipid metabolism in the human monocyte-macrophage and suggest a new in vivo role for the hormone.

scholarly journals Conditioned medium-preconditioned EPCs enhanced the ability in oligovascular repair in cerebral ischemia neonatal rats

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ning Zhou ◽  
Lei Wang ◽  
Ping Fu ◽  
Zihao Cui ◽  
Yuhang Ge ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Western Blot ◽  
Conditioned Medium ◽  
Cognitive Outcome ◽  
Adult Brain ◽  
Neonatal Rat ◽  
Vascular Density ◽  
Cxcr4 Axis

Abstract Background Oligovascular niche mediates interactions between cerebral endothelial cells and oligodendrocyte precursor cells (OPCs). Disruption of OPC-endothelium trophic coupling may aggravate the progress of cerebral white matter injury (WMI) because endothelial cells could not provide sufficient support under diseased conditions. Endothelial progenitor cells (EPCs) have been reported to ameliorate WMI in the adult brain by boosting oligovascular remodeling. It is necessary to clarify the role of the conditioned medium from hypoxic endothelial cells preconditioned EPCs (EC-pEPCs) in WMI since EPCs usually were recruited and play important roles under blood-brain barrier disruption. Here, we investigated the effects of EC-pEPCs on oligovascular remodeling in a neonatal rat model of WMI. Methods In vitro, OPC apoptosis induced by the conditioned medium from oxygen-glucose deprivation-injured brain microvascular endothelial cells (OGD-EC-CM) was analyzed by TUNEL and FACS. The effects of EPCs on EC damage and the expression of cytomokine C-X-C motif ligand 12 (CXCL12) were examined by western blot and FACS. The effect of the CM from EC-pEPCs against OPC apoptosis was also verified by western blot and silencing RNA. In vivo, P3 rat pups were subjected to right common carotid artery ligation and hypoxia and treated with EPCs or EC-pEPCs at P7, and then angiogenesis and myelination together with cognitive outcome were evaluated at the 6th week. Results In vitro, EPCs enhanced endothelial function and decreased OPC apoptosis. Meanwhile, it was confirmed that OGD-EC-CM induced an increase of CXCL12 in EPCs, and CXCL12-CXCR4 axis is a key signaling since CXCR4 knockdown alleviated the anti-apoptosis effect of EPCs on OPCs. In vivo, the number of EPCs and CXCL12 protein level markedly increased in the WMI rats. Compared to the EPCs, EC-pEPCs significantly decreased OPC apoptosis, increased vascular density and myelination in the corpus callosum, and improved learning and memory deficits in the neonatal rat WMI model. Conclusions EC-pEPCs more effectively promote oligovascular remodeling and myelination via CXCL12-CXCR4 axis in the neonatal rat WMI model.

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