scholarly journals Oxidation of low-density lipoprotein with hypochlorite causes transformation of the lipoprotein into a high-uptake form for macrophages

1993 ◽  
Vol 290 (1) ◽  
pp. 165-172 ◽  
Author(s):  
L J Hazell ◽  
R Stocker
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Fold Increase ◽  
Oxidative Modification ◽  
Lipid Hydroperoxides ◽  
Low Density ◽  
High Uptake ◽  
Apoprotein B ◽  
Lysine Residues

Oxidation of low-density lipoprotein (LDL) lipid is thought to represent the initial step in a series of oxidative modification reactions that ultimately transform this lipoprotein into an atherogenic high-uptake form that can cause lipid accumulation in cells. We have studied the effects of hypochlorite, a powerful oxidant released by activated monocytes and neutrophils, on isolated LDL. Exposure of LDL to reagent hypochlorite (NaOCl) at 4 degrees C resulted in immediate and preferential oxidation of amino acid residues of apoprotein B-100, the single protein associated with LDL. Neither lipoprotein lipid nor LDL-associated antioxidants, except ubiquinol-10, represented major targets for this oxidant. Even when high concentrations of NaOCl were used, only low levels of lipid hydroperoxides could be detected with the highly sensitive h.p.l.c. post-column chemiluminescence detection method. Lysine residues of apoprotein B-100 quantitatively represented the major target, scavenging some 68% of the NaOCl added, with tryptophan and cysteine together accounting for an additional 10% of the oxidant. Concomitant with the loss of LDL's amino groups, chloramines were formed and the anionic surface charge of the lipoprotein particle increased, indicated by a 3-4-fold increase in electrophoretic mobility above that of native LDL on agarose gels. While both these changes could be initially reversed by physiological reductants such as ascorbic acid and methionine, incubation of the NaOCl-modified LDL at 37 degrees C resulted in increasing resistance of the modified lysine residues against reductive reversal. Exposure of mouse peritoneal macrophages to NaOCl-oxidized LDL resulted in increased intracellular concentrations of cholesterol and cholesteryl esters. These findings suggest that lipid-soluble antioxidants associated with LDL do not efficiently protect the lipoprotein against oxidative damage mediated by hypochlorite, and that extensive lipid oxidation is not a necessary requirement for oxidative LDL modification that leads to a high-uptake form of the lipoprotein.

scholarly journals Oxidation of low-density lipoprotein by hypochlorite causes aggregation that is mediated by modification of lysine residues rather than lipid oxidation

1994 ◽  
Vol 302 (1) ◽  
pp. 297-304 ◽  
Author(s):  
L J Hazell ◽  
J J M van den Berg ◽  
R Stocker
Keyword(s):  
Lipid Peroxidation ◽  
Lipid Oxidation ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Size Exclusion ◽  
Lipid Hydroperoxides ◽  
Low Density ◽  
Lysine Residues

Peroxidation of low-density lipoprotein (LDL) lipid is generally thought to represent the initial step in a series of modification reactions that ultimately transform the protein moiety of the lipoprotein into a form recognized by receptors different from those that bind native LDL. Uptake of LDL via these alternative receptors can lead to the formation of lipid-laden cells, which are typical for the early stages of atherogenesis. We have studied the oxidative modification of LDL by hypochlorite (-OCl), a powerful oxidant produced from H2O2 and chloride via the action of myeloperoxidase which is released from activated neutrophils and monocytes. Exposure of LDL to reagent or enzymically generated -OCl at 4 or 37 degrees C resulted in immediate and preferential oxidation of amino acid residues of apolipoprotein B-100, the single protein associated with LDL. Lysine residues quantitatively represented the major target and, like tryptophan, were oxidized to approximately the same extent with reagent or enzymically generated -OCl. In contrast, LDL lipid oxidation was less favoured than protein oxidation, as judged by the amounts of lipid hydroperoxides, chlorohydrins, cholesterol or fatty acid oxidation products formed. Treatment with -OCl caused aggregation of LDL, as shown by an increased turbidity of the oxidized LDL solution and elution from a size-exclusion h.p.l.c. column of high-molecular-mass LDL complexes. Chemical modification of lysine residues before oxidation with -OCl prevented aggregation, while it enhanced the extent of lipid peroxidation. Treatment of LDL with -OCl also caused the formation of carbonyl groups and release of ammonia; both these modifications were inhibited by lysine-residue modification before oxidation. These results demonstrate that aggregation reactions are dependent on initial lysine oxidation by -OCl, followed by deamination and carbonyl formation, but do not involve lipid (per)oxidation. We propose that the observed -OCl-mediated aggregation of LDL is caused, at least in part, by cross-linking of apoproteins by Schiff-base formation independently of lipid peroxidation.

scholarly journals Detection of new epitopes formed upon oxidation of low-density lipoprotein, lipoprotein (a) and very-low-density lipoprotein. Use of an antiserum against 4-hydroxynonenal-modified low-density lipoprotein

1990 ◽  
Vol 265 (2) ◽  
pp. 605-608 ◽  
Author(s):  
G Jürgens ◽  
A Ashy ◽  
H Esterbauer
Keyword(s):  
Unsaturated Fatty Acids ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Lipid Hydroperoxides ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Dependent Manner ◽  
Lipoprotein A

4-Hydroxynonenal (HNE) is a major aldehydic propagation product formed during peroxidation of unsaturated fatty acids. The aldehyde was used to modify freshly prepared human low-density lipoprotein (LDL). A polyclonal antiserum was raised in the rabbit and absorbed with freshly prepared LDL. The antiserum did not react with human LDL, but reacted with CuCl2-oxidized LDL and in a dose-dependent manner with LDL, modified with 1, 2 and 3 mM-HNE, in the double-diffusion analysis. LDL treated with 4 mM of hexanal or hepta-2,4-dienal or 4-hydroxyhexenal or malonaldehyde (4 or 20 mM) did not react with the antiserum. However, LDL modified with 4 mM-4-hydroxyoctenal showed a very weak reaction. Lipoprotein (a) and very-low-density lipoprotein were revealed for the first time to undergo oxidative modification initiated by CuCl2. This was evidenced by the generation of lipid hydroperoxides and thiobarbituric acid-reactive substances, as well as by a marked increase in the electrophoretic mobility. After oxidation these two lipoproteins also reacted positively with the antiserum against HNE-modified LDL.

scholarly journals Treatment of macrophages with oxidized low-density lipoprotein increases their intracellular glutathione content

1991 ◽  
Vol 278 (2) ◽  
pp. 429-434 ◽  
Author(s):  
V M Darley-Usmar ◽  
A Severn ◽  
V J O'Leary ◽  
M Rogers
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Cell Types ◽  
Oxidative Modification ◽  
Glutathione Depletion ◽  
Lipid Phase ◽  
Low Density ◽  
Oxidized Low Density Lipoprotein

Macrophages derived from the human monocyte cell line THP-1 or isolated from the peritoneum of C3H/HEJ mice were incubated with oxidized low-density lipoprotein (LDL) and the total glutathione content (oxidized plus reduced) was measured. An initial depletion of glutathione was followed by an increase, such that after a period of 24 h the glutathione content has approximately doubled. This response required the oxidation of the lipid phase of the LDL molecule, since both native LDL and acetylated LDL had little effect on glutathione levels. The response of the cells to oxidized LDL was dependent on the extent of oxidative modification of the protein. It was also found that 4-hydroxynonenal had a similar effect on THP-1 cells, and we suggest that this or other aldehydes present in oxidized LDL causes the induction of glutathione synthesis in response to an initial oxidative stress and consequent glutathione depletion. In addition, we found that both cell types possess transferases and peroxidases capable of detoxifying aldehydes and peroxides. However, treatment of cells with oxidized LDL or 4-hydroxynonenal for a period of 24 h had no effect on the activities of these enzymes.

Hydrogen sulfide destroys lipid hydroperoxides in oxidized LDL

2009 ◽  
Vol 420 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Markus K. Muellner ◽  
Sabine M. Schreier ◽  
Hilde Laggner ◽  
Marcela Hermann ◽  
Harald Esterbauer ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Hplc Analysis ◽  
Octadecadienoic Acid ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipid Hydroperoxides ◽  
Low Density ◽  
The Third ◽  
Haem Oxygenase

LOOHs (lipid hydroperoxides) in oxLDL [oxidized LDL (low-density lipoprotein)] are potentially atherogenic compounds. Recently, H2S was identified as the third endogenous gasotransmitter in the vasculature. H2O2 is known to be destroyed by H2S. Assuming that H2S may also react with LOOHs, the results show that H2S can destroy LOOHs in oxLDL. The ability of LOOH-enriched LDL to induce HO-1 (haem oxygenase 1) in endothelial cells was abolished by H2S pretreatment. HPLC analysis showed that 9-HPODE [(9S)-hydroperoxy-(10E,12Z)-octadecadienoic acid], a compound found in oxLDL, was reduced to 9-HODE [(9S)-hydroxy-(10E,12Z)-octadecadienoic acid] in the presence of H2S. Thus H2S may act as an antiatherogenic agent by reducing LOOHs to the less reactive LOHs and could abrogate the pathobiological activity of oxLDL.

scholarly journals GLYCATED LOW-DENSITY LIPOPROTEIN IN DIABETIC AND NON-DIABETIC PATIENTS

2019 ◽  
pp. 123-126
Author(s):  
OMAR ABDULWAHID AL-ANI ◽  
ABDURRAHMAN AL-BAZZAZ
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Diabetic Group ◽  
Enzyme Linked Immunosorbent Assay ◽  
Diabetic Patients ◽  
Low Density ◽  
Serum Samples ◽  
Diabetes Center

Objective: The importance of measuring the blood level of modified low-density lipoprotein (LDL) molecules is an effective method of identifying people at risk of coronary atherosclerosis; this is because, in the early stages of atherosclerosis, lipolysis and oxidative modification have a role in promoting the uptake of these lipids through macrophages; therefore, this research aims to measure the level of glycated LDL (Gly-LDL) in the blood and its association with metabolic parameters of diabetic patients (diabetes mellitus) and non-diabetic (hyperlipidemia). Methods: At a University Diabetes Center in Riyadh, we using routine automatic analysis methods, fasting serum samples were analyzed for 31 patients with Type-2 diabetes and 31 non-diabetic patients for LDL, high-density lipoprotein (HDL), total cholesterol, glycated hemoglobin, glucose, and triglycerides (TG), and using enzyme-linked immunosorbent assay to analyze Gly-LDL for the same sample. Results: The level of serum Gly-LDL in non-diabetic was higher than in diabetic patients (p=0.037). Gly-LDL level correlated significantly with LDL in the diabetic group (p=0.035) and was insignificant with other parameters; moreover, it is significantly correlated with HDL (p=0.048), TG (p=0.035), and very LDL (p=0.03) in the non-diabetic group and insignificant with other parameters. Conclusion: Measuring rates of Gly-LDL can be used in the early detection of cardiovascular disease, especially in people with diabetes, as they are more susceptible to modified and oxidized LDL.

scholarly journals Pro-oxidant and cytotoxic effects of circulating heme

Blood ◽  
2002 ◽  
Vol 100 (3) ◽  
pp. 879-887 ◽  
Author(s):  
Viktória Jeney ◽  
József Balla ◽  
Akihiro Yachie ◽  
Zsuzsa Varga ◽  
Gregory M. Vercellotti ◽  
...  
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Heme Oxygenase 1 ◽  
Lipid Hydroperoxides ◽  
Human Patient ◽  
Free Heme ◽  
The Central Nervous System ◽  
Deficient Child

Abstract Numerous pathologies may involve toxic side effects of free heme and heme-derived iron. Deficiency of the heme-catabolizing enzyme, heme oxygenase-1 (HO-1), in both a human patient and transgenic knockout mice leads to an abundance of circulating heme and damage to vascular endothelium. Although heme can be directly cytotoxic, the present investigations examine the possibility that hemoglobin-derived heme and iron might be indirectly toxic through the generation of oxidized forms of low-density lipoprotein (LDL). In support, hemoglobin in plasma, when oxidized to methemoglobin by oxidants such as leukocyte-derived reactive oxygen, causes oxidative modification of LDL. Heme, released from methemoglobin, catalyzes the oxidation of LDL, which in turn induces endothelial cytolysis primarily caused by lipid hydroperoxides. Exposure of endothelium to sublethal concentrations of this oxidized LDL leads to induction of both HO-1 and ferritin. Similar endothelial cytotoxicity was caused by LDL isolated from plasma of an HO-1–deficient child. Spectral analysis of the child's plasma revealed a substantial oxidation of plasma hemoglobin to methemoglobin. Iron accumulated in the HO-1–deficient child's LDL and several independent assays revealed oxidative modification of the LDL. We conclude that hemoglobin, when oxidized in plasma, can be indirectly cytotoxic through the generation of oxidized LDL by released heme and that, in response, the intracellular defense—HO-1 and ferritin—is induced. These results may be relevant to a variety of disorders—such as renal failure associated with intravascular hemolysis, hemorrhagic injury to the central nervous system, and, perhaps, atherogenesis—in which hemoglobin-derived heme may promote the formation of fatty acid hydroperoxides.

scholarly journals Decomposition of lipid hydroperoxides enhances the uptake of low density lipoprotein by macrophages.

1999 ◽  
Vol 46 (1) ◽  
pp. 31-42 ◽  
Author(s):  
A V Babiy ◽  
J M Gebicki
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Lipid Hydroperoxide ◽  
Significant Proportion ◽  
Density Lipoprotein ◽  
Scavenger Receptors ◽  
Lipid Hydroperoxides ◽  
Strictly Anaerobic ◽  
Low Density ◽  
Apo B

This study examined the roles of low-density lipoprotein (LDL) lipid oxidation and peroxide breakdown in its conversion to a form rapidly taken up by mouse peritoneal macrophages. Oxidation of the LDL without decomposition of the hydroperoxide groups was performed by exposure to gamma radiation in air-saturated solutions. Virtually complete decomposition of the hydroperoxides was achieved by treatment of the irradiated LDL with Cu2+ under strictly anaerobic conditions. No uncontrolled LDL uptake by macrophages occurred when the lipoprotein contained less than 150 hydroperoxide groups per particle. More extensively oxidized LDL was taken up and degraded by mouse macrophages significantly faster than the native lipoprotein. The uptake was greatly enhanced by treatment of the oxidized LDL with Cu2+. A significant proportion of the LDL containing intact or copper-decomposed LDL hydroperoxide groups accumulated within the macrophages without further degradation. Treatment of the radiation-oxidized LDL with Cu2+ was accompanied by aggregation of the particles. Competition studies showed that the oxidized LDL was taken up by macrophages via both the LDL and the scavenger receptors, whereas the copper-treated lipoprotein entered the cells only by the scavenger pathway. Phagocytosis also played an important role in the metabolism of all forms of the extensively modified LDL. Our results suggest that minimally-oxidized LDL is not recognized by the macrophage scavenger receptors unless the lipid hydroperoxide groups are decomposed to products able to derivatize the apo B protein.

scholarly journals Oxidative Modification of Lipoproteins: A Potential Role of Oxidized Small dense LDL in Enhanced Atherogenicity

2021 ◽  
pp. 118-140
Author(s):  
Mohammed Alsaweed
Keyword(s):  
Arterial Wall ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Predictive Marker ◽  
Oxidative Modification ◽  
Cholesterol Homeostasis ◽  
Low Density ◽  
Small Dense Ldl ◽  
Ldl Particles ◽  
Apoprotein B

Atherosclerosis (AS) is a multifaceted inflammatory syndrome of the arterial wall to which number of mediators have been implicated in lesion progression. Triglyceride (TG)-rich lipoproteins consist of the large diversity of lipoprotein particles that fluctuate in density, size, and apolipoprotein composition. Two foremost phenotypes, on basis of size, chemical configuration, and density, of low-density-lipoprotein (LDL) have been recognized i.e., pattern A, having LDL diameter greater than 25.5nm (large buoyant LDL or lb-LDL) and pattern B, having LDL diameter less than or equal to 25.5nm (small-dense LDL or sd-LDL). Small-dense low-density-lipoprotein (sd-LDL) particles are produced by potential intravascular hydrolysis of TG-rich VLDL particles via lipoprotein lipases (LPLs), hepatic lipases (HLs) and cholesterol ester transfer protein (CETP). sd-LDL is more atherogenic due to its smaller size, increased penetration into the arterial wall, extended plasma half-life, lesser binding affinity for LDL receptors (LDL-R) as well as lower resistance to oxidative stress when equated with lb-LDL. The higher atherogenic potential of sd-LDL is due to its enhanced susceptibility to oxidation, owing to high polyunsaturated fatty acids (PUFA), low cholesterol and Apoprotein B (ApoB) content. An enhanced understanding of sd-LDL metabolism at the molecular level, transport and clearance may result in the development of sd-LDL as an independent predictive marker for AS events and may be used to maintain cholesterol homeostasis and prevent the succession of AS.

scholarly journals Quantification of malondialdehyde and 4-hydroxynonenal adducts to lysine residues in native and oxidized human low-density lipoprotein

1997 ◽  
Vol 322 (1) ◽  
pp. 317-325 ◽  
Author(s):  
Jesús R. REQUENA ◽  
Min Xin FU ◽  
Mahtab U. AHMED ◽  
Alicia J. JENKINS ◽  
Timothy J. LYONS ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gas Chromatography ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Thiobarbituric Acid ◽  
Low Density ◽  
Lysine Residues

Malondialdehyde (MDA) and 4-hydroxynonenal (HNE) are major end-products of oxidation of polyunsaturated fatty acids, and are frequently measured as indicators of lipid peroxidation and oxidative stress in vivo. MDA forms Schiff-base adducts with lysine residues and cross-links proteins in vitro; HNE also reacts with lysines, primarily via a Michael addition reaction. We have developed methods using NaBH4 reduction to stabilize these adducts to conditions used for acid hydrolysis of protein, and have prepared reduced forms of lysine-MDA [3-(Nε-lysino)propan-1-ol (LM)], the lysine-MDA-lysine iminopropene cross-link [1,3-di(Nε-lysino)propane (LML)] and lysine-HNE [3-(Nε-lysino)-4-hydroxynonan-1-ol (LHNE)]. Gas chromatography/MS assays have been developed for quantification of the reduced compounds in protein. RNase incubated with MDA or HNE was used as a model for quantification of the adducts by gas chromatography/MS. There was excellent agreement between measurement of MDA bound to RNase as LM and LML, and as thiobarbituric acid-MDA adducts measured by HPLC; these adducts accounted for 70Ő80% of total lysine loss during the reaction with MDA. LM and LML (0.002Ő0.12mmol/mol of lysine) were also found in freshly isolated low-density lipoprotein (LDL) from healthy subjects. LHNE was measured in RNase treated with HNE, but was not detectable in native LDL. LM, LML and LHNE increased in concert with the formation of conjugated dienes during the copper-catalysed oxidation of LDL, but accounted for modification of < 1% of lysine residues in oxidized LDL. These results are the first report of direct chemical measurement of MDA and HNE adducts to lysine residues in LDL. LM, LML and LHNE should be useful as biomarkers of lipid peroxidative modification of protein and of oxidative stress in vitro and in vivo.

scholarly journals Non-oxidative modification of native low-density lipoprotein by oxidized low-density lipoprotein

1996 ◽  
Vol 316 (2) ◽  
pp. 377-380 ◽  
Author(s):  
Min YANG ◽  
David S. LEAKE ◽  
Catherine A. RICE-EVANS
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Low Density ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Process Studies

The oxidative modification of low-density lipoprotein (LDL) has been implicated in the pathogenesis of atherosclerosis, although little is known as yet about the precise mechanism of oxidation in vivo. The studies presented here demonstrate that, in the absence of cells or transition metals, oxidized LDL can modify native LDL through co-incubation in vitro such as to increase its net negative charge, in a concentration-dependent manner. The interaction is not inhibited by peroxyl radical scavengers or metal chelators, precluding the possibility that the modification of native LDL by oxidized LDL is through an oxidative process. Studies with radioiodinated oxidized LDL showed no transfer of radioactivity to the native LDL, demonstrating that fragmentation of protein and the transfer of some of the fragments does not account for the modified charge on the native LDL particle. The adjacency of native to oxidized LDL in the arterial wall may be a potential mechanism by which the altered recognition properties of the apolipoprotein B-100 may arise rapidly without oxidation or extensive modification of the native LDL lipid itself.

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