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 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 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.

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 Very-Low-Density Lipoprotein Receptor Fragment Shed from HeLa Cells Inhibits Human Rhinovirus Infection

1998 ◽  
Vol 72 (12) ◽  
pp. 10246-10250 ◽  
Author(s):  
Thomas C. Marlovits ◽  
Christina Abrahamsberg ◽  
Dieter Blaas
Keyword(s):  
Hela Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Intercellular Adhesion Molecule ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Dependent Manner ◽  
Low Density Lipoprotein Receptor ◽  
Density Lipoprotein Receptor

ABSTRACT The large family of human rhinoviruses, the main causative agents of the common cold, is divided into the major and the minor group based on receptor specificity. Major group viruses attach to intercellular adhesion molecule 1 (ICAM-1), a member of the immunoglobulin superfamily, whereas minor group viruses use low-density lipoprotein receptors (LDLR) for cell entry. During early attempts aimed at isolating the minor group receptor, we discovered that a protein with virus binding activity was released from HeLa cells upon incubation with buffer at 37°C (F. Hofer, B. Berger, M. Gruenberger, H. Machat, R. Dernick, U. Tessmer, E. Kuechler, and D. Blaas, J. Gen. Virol. 73:627–632, 1992). In light of the recent discovery of several new members of the LDLR family, we reinvestigated the nature of this protein and present evidence for its being derived from the human very-low density lipoprotein receptor (VLDLR). A soluble VLDLR fragment encompassing the eight complement type repeats and representing the N-terminal part of the receptor was then expressed in the baculovirus system; both the shed protein and the recombinant soluble VLDLR bind minor group viruses and inhibit viral infection of HeLa cells in a concentration-dependent manner.

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.

Effect of α-Tocopherol on the Oxidative Modification of Apolipoprotein E in Human Very-low-density Lipoprotein

2003 ◽  
Vol 67 (2) ◽  
pp. 402-405 ◽  
Author(s):  
Hirofumi ARAI ◽  
Koji UCHIDA ◽  
Kenji FUKUNAGA ◽  
Yuji NAGASAKA ◽  
Satoshi MOHRI ◽  
...  
Keyword(s):  
Apolipoprotein E ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Very Low Density Lipoprotein ◽  
Low Density

scholarly journals Low-density lipoprotein is the major carrier of lipid hydroperoxides in plasma. Relevance to determination of total plasma lipid hydroperoxide concentrations

1996 ◽  
Vol 313 (3) ◽  
pp. 781-786 ◽  
Author(s):  
Jaffar NOUROOZ-ZADEH ◽  
Jarad TAJADDINI-SARMADI ◽  
K. L. Eddie LING ◽  
Simon P. WOLFF
Keyword(s):  
Total Lipid ◽  
Xylenol Orange ◽  
Low Density Lipoprotein ◽  
Lipid Hydroperoxide ◽  
Plasma Lipid ◽  
Density Lipoprotein ◽  
Ldl Oxidation ◽  
Lipid Hydroperoxides ◽  
Very Low Density Lipoprotein ◽  
Low Density

High-density lipoprotein (HDL) has been proposed as the principal carrier of hydroperoxides in plasma, based upon data gathered with an HPLC-chemiluminescence technique. To test this hypothesis we have measured total lipid hydroperoxides in native plasma using the ferrous oxidation in Xylenol Orange (FOX) assay and then fractionated plasma into very-low-density lipoprotein, low-density lipoprotein (LDL) and HDL fractions. Hydroperoxides were found to accumulate principally (more than 65%) in LDL, as judged by hydroperoxide content per amount of protein or cholesterol, or expressed as a proportion of total hydroperoxide in plasma. Plasma was also incubated at 37 °C in the presence and absence of 2,2´-azo-bis-(2-amidinopropane) hydrochloride (AAPH), an azo-initiator of lipid peroxidation. The majority of hydroperoxides generated in plasma were recovered in the LDL fraction. Furthermore, when isolated lipoproteins were subject to oxidation initiated by AAPH, very-low-density lipoprotein and LDL showed the greatest propensity for hydroperoxide accumulation, whereas HDL seemed relatively resistant. Estimates for plasma and LDL peroxidation based upon techniques which measure total lipid hydroperoxides suggest that levels of hydroperoxides in plasma and LDL are far higher than that those estimates generated by ostensibly more selective techniques. Higher levels of hydroperoxides in LDL than those reported by HPLC-chemiluminescence also seem in greater accordance with other available data concerning LDL oxidation.

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