Role of platelet secretory products in modified lipoprotein metabolism in macrophages.
Macrophage-derived foam cells and platelets are found in many lesions of atherosclerosis. Macrophages possess scavenger receptors that take up modified low density lipoproteins (LDL) like acetylated or acetoacetylated LDL (aLDL, aaLDL) resulting in accumulation of esterified cholesterol (EC) and acquisition of the characteristics of foam cells. We obtained a certain platelet secretory product from washed platelet-rich plasma which had been frozen and thawed three times (PSP alpha). We studied the effect of PSP alpha in modified lipoprotein metabolism in macrophages. When mouse or human macrophages were incubated with aaLDL and PSP alpha, much more EC was accumulated than with aaLDL only. Though the increase in EC of macrophages was dependent on the concentration of PSP alpha, it declined in high concentrations of PSP alpha. PSP alpha moderately increased 125I-aaLDL binding and cellular metabolism. PSP alpha also affected 125I-oxidized LDL binding and cellular metabolism, but it did not affect the metabolism of 125I beta-migrating very low density lipoprotein (beta VLDL). These results suggest that substances shed by activated platelets play a role in atherosclerosis as potent mediators of EC accumulation in macrophages and by affecting the receptor-mediated endocytosis of modified lipoproteins.
Department of Geriatrics, Nagoya University, School of Medicine, Japan.
T
T
Hayashi
M
M
Naito
M
M
Kuzuya
C
C
Funaki
T
T
Tateishi
K
K
Asai
F
F
Kuzuya
D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D002784:Cholesterol / Q000378:metabolism; D002788:Cholesterol Esters / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008074:Lipoproteins / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000097:blood / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000097:blood / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D011817:Rabbits
D002788:Cholesterol Esters; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D002784:Cholesterol