Cited by 59Cholesterol and Lipid MetabolismAtherosclerosis and Cardiovascular DiseasesLipid metabolism and disorders

Uptake of type III hypertriglyceridemic VLDL by macrophages is enhanced by oxidation, especially after remnant formation

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Whitman, Stewart C., Miller, David B., Wolfe, Bernard M., Hegele, Robert A., Huff, Murray W.·1997·Arteriosclerosis, Thrombosis, and Vascular Biology

Abstract

Abstract We previously showed that hypertriglyceridemic VLDL (HTG-VLDL, Sf 60 to 400) from subjects with type III (E2/E2) hyperlipoproteinemia do not induce appreciable cholesteryl ester (CE) accumulation in cultured macrophages (J774A.1). In the present study, we examined whether oxidation of type III HTG-VLDL would enhance their uptake by J774A.1 cells. Type III HTG-VLDL were oxidized as measured by both conjugated-diene formation and increased electrophoretic mobility on agarose gels. Both LDL and type III HTG-VLDL undergo oxidation, albeit under different kinetic parameters. From the conjugated-diene curve, type III HTG-VLDL, compared with LDL, were found to have a 6-fold longer lag time, to take 6-fold longer to reach maximal diene production, and to produce a 2-fold greater amount of dienes but at half the rate (all P <.005). Incubation of macrophages with either native type III HTG-VLDL or LDL (50 μg lipoprotein cholesterol/mL media for 16 hours) caused small increases (4-fold and 2.7-fold, respectively) in cellular CE levels relative to control cells (both P =.0001). After 24 hours of CuSO 4 exposure, we found that oxidized type III HTG-VLDL and LDL caused a 9.4-fold and 10.5-fold increase, respectively, in cellular CE levels ( P =.0001). We next examined whether extending the exposure period for type III HTG-VLDL to CuSO 4 beyond 24 hours would further enhance its ability to induce macrophage CE accumulation. After 48 hours of CuSO 4 exposure, type III HTG-VLDL and LDL caused 21.3-fold and 11.6-fold increases, respectively, in cellular CE levels ( P =.0001). The cellular CE loading achieved with 48 hour–oxidized type III HTG-VLDL was significantly higher than either 24 hour–oxidized type III HTG-VLDL (2.3-fold, P =.003) or 48 hour–oxidized LDL (1.8-fold, P =.012). There was no significant difference between the CE loading achieved by incubation of cells with either 24 hour–oxidized type III HTG-VLDL, 24 hour–oxidized LDL, or 48 hour–oxidized LDL ( P ≥.518). In this study, we also examined whether partial lipolysis (19% to 50% triglyceride hydrolysis) of type III HTG-VLDL to produce remnants would increase the susceptibility of the lipoprotein to oxidative modification and subsequent cellular CE loading. Forty-eight hour–oxidized type III VLDL-remnants stimulated CE accumulation 30.4-fold over baseline ( P =.0001). In contrast, nonoxidized type III VLDL-remnants caused the same very low level of CE loading as did native type III HTG-VLDL ( P =.680). The increase in cellular CE levels achieved with 48 hour–oxidized type III VLDL-remnants was significantly higher than that achieved with 48 hour–oxidized type III HTG-VLDL ( P =.047). In conclusion, we have shown that oxidized type III HTG-VLDL will induce macrophage CE accumulation well above levels achieved with oxidized LDL. In addition, we also showed that by forming a VLDL-remnant before oxidative modification, we can further enhance macrophage CE accumulation. These results provide a potential mechanism for the atherogenicity of type III HTG-VLDL and their remnants.

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Research works printed but not linked: 6

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Authors
Whitman, S. C., Miller, D. B., Wolfe, B. M., Hegele, R. A., & Huff, M. W.
Affiliations
Western University (CA)
Venue
Arteriosclerosis, Thrombosis, and Vascular Biology
Published
1997-09
Volume
17
Issue
9
Pages
1707-1715
ISSN
  • 1079-5642 (ISSN-L)
  • 1524-4636
OpenAlex
W2075141316
Cited by
59
References
63
Citations by year
2026: 1 · 2025: 2 · 2024: 3 · 2023: 5 · 2022: 1 · 2021: 3 · 2020: 4 · 2019: 1 · 2015: 1 · 2014: 3 · 2013: 2 · 2012: 3
FWCI
3.45
Type
journal article
Language
en
Open access
Locations
  • Arteriosclerosis Thrombosis and Vascular Biology (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Heart and Stroke Foundation of Canada
  • Medical Research Council Canada
  • Medical Research Council
Topics
  • Health Sciences › Medicine › Surgery › Cholesterol and Lipid Metabolism
  • Life Sciences › Immunology and Microbiology › Immunology › Atherosclerosis and Cardiovascular Diseases
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Lipid metabolism and disorders
Keywords
type III hyperlipoproteinemia, macrophage uptake, cholesteryl ester accumulation, remnant lipoproteins, copper-induced oxidation, LDL oxidation, atherosclerosis, foam cell formation, J774A.1 macrophages, conjugated dienes
MeSH terms
Animals, Cattle, Cell Line, Cells, Cultured, Cholesterol Esters, Electrophoresis, Agar Gel, Foam Cells, Humans, Lipoproteins, LDL, Lipoproteins, VLDL, Macrophages, Oxidation-Reduction, Time Factors, Hypertriglyceridemia, Copper Sulfate, Mice

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