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Proteoglycans produced by cholesterol-enriched macrophages bind plasma low density lipoprotein
1Department of Comparative Medicine, Bowman Gray School of Medicine, Winston-Salem, NC 27157-1040.
Atherosclerosis
|December 1, 1991
Summary
Macrophage proteoglycans (PG) bind low-density lipoprotein (LDL), suggesting they trap LDL in artery walls and promote foam cell formation in atherosclerosis.
Area of Science:
- Cardiovascular Biology
- Atherosclerosis Research
- Macrophage Biochemistry
Background:
- Proteoglycans (PG) play roles in extracellular matrix structure and cell signaling.
- Macrophage accumulation of lipids contributes to foam cell formation in atherosclerosis.
- Cholesterol-enriched macrophages from pigeons provide a model for studying atherosclerosis.
Purpose of the Study:
- To characterize proteoglycans (PG) synthesized by cholesterol-enriched macrophages from atherosclerosis-susceptible (White Carneau) and -resistant (Show Racer) pigeons.
- To assess the capacity of these macrophage PGs to bind low-density lipoprotein (LDL).
Main Methods:
- Macrophage cultures from pigeons were labeled with [35S]sulfate and [3H]serine.
- Proteoglycans were analyzed using Sepharose CL-4B chromatography.
- LDL binding capacity was assessed using LDL-substituted Sepharose.
Main Results:
- Macrophage cultures produced both large and small proteoglycans, primarily chondroitin sulfate-PGs.
- Small PGs showed higher binding affinity to LDL (86-93%) compared to large PGs (32-34%).
- Heparin and soluble LDL inhibited PG-LDL interactions, and intact PGs were crucial for binding.
Conclusions:
- Macrophage proteoglycans, particularly small chondroitin sulfate-PGs, effectively bind LDL.
- These PG-LDL interactions may facilitate LDL trapping in the artery intima.
- This mechanism could contribute to foam cell formation and the development of atherosclerosis.