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Title: Stimulation of mast cells leads to cholesterol accumulation in macrophages in vitro by a mast cell granule-mediated uptake of low density lipoprotein

Abstract

The uptake of low density lipoprotein (LDL) by cultured mouse macrophages was markedly promoted by isolated rat mast cell granules present in the culture medium. The granule-mediated uptake of /sup 125/I-LDL enhanced the rate of cholesteryl ester synthesis in the macrophages, the result being accumulation of cholesteryl esters in these cells. Binding of LDL to the granules was essential for the granule-mediated uptake of LDL by macrophages, for the uptake process was prevented by treating the granules with avidin or protamine chloride or by treating LDL with 1,2-cyclohexanedione, all of which inhibit the binding of LDL to the granules. Inhibition of granule phagocytosis by the macrophages with cytochalasin B also abolished the granule-mediated uptake of LDL. Finally, mouse macrophage monolayers and LDL were incubated in the presence of isolated rat serosal mast cells. Stimulation of the mast cells with compound 48/80, a degranulating agent, resulted in dose-dependent release of secretory granules from the mast cells and a parallel increase in /sup 14/C cholesteryl ester synthesis in the macrophages. The results show that, in this in vitro model, the sequence of events leading to accumulation of cholesteryl esters in macrophages involves initial stimulation of mast cells, subsequent release of their secretorymore » granules, binding of LDL to the exocytosed granules, and, finally, phagocytosis of the LDL-containing granules by macrophages.« less

Authors:
;
Publication Date:
Research Org.:
Wihuri Research Institute, Helsinki, Finland
OSTI Identifier:
5903667
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States); Journal Volume: 84:8
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ARTERIOSCLEROSIS; PATHOGENESIS; CARBON 14 COMPOUNDS; BIOSYNTHESIS; CHOLESTEROL; LABELLED COMPOUNDS; UPTAKE; LIPOPROTEINS; IN VITRO; IODINE 125; MACROPHAGES; MAST CELLS; OLEIC ACID; PHAGOCYTOSIS; SODIUM IODIDES; SULFATES; SULFUR 35; ALKALI METAL COMPOUNDS; ANIMAL CELLS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CARBOXYLIC ACIDS; CARDIOVASCULAR DISEASES; CONNECTIVE TISSUE CELLS; DAYS LIVING RADIOISOTOPES; DISEASES; ELECTRON CAPTURE RADIOISOTOPES; EVEN-ODD NUCLEI; HALIDES; HALOGEN COMPOUNDS; HYDROXY COMPOUNDS; INORGANIC PHOSPHORS; INTERMEDIATE MASS NUCLEI; IODIDES; IODINE COMPOUNDS; IODINE ISOTOPES; ISOTOPES; LIGHT NUCLEI; LIPIDS; MONOCARBOXYLIC ACIDS; NUCLEI; ODD-EVEN NUCLEI; ORGANIC ACIDS; ORGANIC COMPOUNDS; OXYGEN COMPOUNDS; PHAGOCYTES; PHOSPHORS; PROTEINS; RADIOISOTOPES; SODIUM COMPOUNDS; SOMATIC CELLS; STEROIDS; STEROLS; SULFUR COMPOUNDS; SULFUR ISOTOPES; SYNTHESIS; VASCULAR DISEASES; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Kokkonen, J.O., and Kovanen, P.T. Stimulation of mast cells leads to cholesterol accumulation in macrophages in vitro by a mast cell granule-mediated uptake of low density lipoprotein. United States: N. p., 1987. Web. doi:10.1073/pnas.84.8.2287.
Kokkonen, J.O., & Kovanen, P.T. Stimulation of mast cells leads to cholesterol accumulation in macrophages in vitro by a mast cell granule-mediated uptake of low density lipoprotein. United States. doi:10.1073/pnas.84.8.2287.
Kokkonen, J.O., and Kovanen, P.T. 1987. "Stimulation of mast cells leads to cholesterol accumulation in macrophages in vitro by a mast cell granule-mediated uptake of low density lipoprotein". United States. doi:10.1073/pnas.84.8.2287.
@article{osti_5903667,
title = {Stimulation of mast cells leads to cholesterol accumulation in macrophages in vitro by a mast cell granule-mediated uptake of low density lipoprotein},
author = {Kokkonen, J.O. and Kovanen, P.T.},
abstractNote = {The uptake of low density lipoprotein (LDL) by cultured mouse macrophages was markedly promoted by isolated rat mast cell granules present in the culture medium. The granule-mediated uptake of /sup 125/I-LDL enhanced the rate of cholesteryl ester synthesis in the macrophages, the result being accumulation of cholesteryl esters in these cells. Binding of LDL to the granules was essential for the granule-mediated uptake of LDL by macrophages, for the uptake process was prevented by treating the granules with avidin or protamine chloride or by treating LDL with 1,2-cyclohexanedione, all of which inhibit the binding of LDL to the granules. Inhibition of granule phagocytosis by the macrophages with cytochalasin B also abolished the granule-mediated uptake of LDL. Finally, mouse macrophage monolayers and LDL were incubated in the presence of isolated rat serosal mast cells. Stimulation of the mast cells with compound 48/80, a degranulating agent, resulted in dose-dependent release of secretory granules from the mast cells and a parallel increase in /sup 14/C cholesteryl ester synthesis in the macrophages. The results show that, in this in vitro model, the sequence of events leading to accumulation of cholesteryl esters in macrophages involves initial stimulation of mast cells, subsequent release of their secretory granules, binding of LDL to the exocytosed granules, and, finally, phagocytosis of the LDL-containing granules by macrophages.},
doi = {10.1073/pnas.84.8.2287},
journal = {Proc. Natl. Acad. Sci. U.S.A.; (United States)},
number = ,
volume = 84:8,
place = {United States},
year = 1987,
month = 4
}
  • Incubation of fibroblasts derived from patients with type-C Niemann-Pick disease with low density lipoprotein results in excessive intracellular accumulation of unesterified cholesterol. Cytochemical techniques revealed that this abnormal cholesterol accumulation is associated not only with a massive storage of cholesterol in lysosomes but also with a premature cholesterol enrichment of the Golgi complex. Cholesterol appeared also in the Golgi complex of some normal fibroblasts after 24 hr of low density lipoprotein loading. These findings indicate that components of the Golgi complex play a role in the intracellular translocation of exogenously derived cholesterol and that disruptions of the cholesterol transport pathwaymore » at the Golgi may, in part, be responsible for the deficiency in cholesterol utilization in type-C Niemann-Pick fibroblasts.« less
  • 4-Chlorotetrazolo[1,5-a]quinoxaline is a quinoxaline derivative. We aimed to study the effects of 4-chlorotetrazolo[1,5-a]quinoxaline on activation of mast cells in vitro and in mice. 4-Chlorotetrazolo[1,5-a]quinoxaline reversibly inhibited degranulation of mast cells in a dose-dependent manner, and also suppressed the expression and secretion of TNF-{alpha} and IL-4 in mast cells. Mechanistically, 4-chlorotetrazolo[1,5-a]quinoxaline inhibited activating phosphorylation of Syk and LAT, which are crucial for early Fc{epsilon}RI-mediated signaling events, as well as Akt and MAP kinases, which play essential roles in the production of various pro-inflammatory cytokines in mast cells. Notably, although 4-chlorotetrazolo[1,5-a]quinoxaline inhibited the activation of Fyn and Syk, minimal inhibition was observedmore » in mast cells in the case of Lyn. Furthermore, consistent with its in vitro activity, 4-chlorotetrazolo[1,5-a]quinoxaline significantly suppressed mast cell-mediated passive cutaneous anaphylaxis in mice. In summary, the results from this study demonstrate that 4-chlorotetrazolo[1,5-a]quinoxaline shows an inhibitory effect on mast cells in vitro and in vivo, and that this is mediated by inhibiting the activation of Syk in mast cells. Therefore, 4-chlorotetrazolo[1,5-a]quinoxaline could be useful in the treatment of mast cell-mediated allergic diseases. -- Highlights: Black-Right-Pointing-Pointer 4-chlorotetrazolo[1,5-a]quinoxaline is a quinoxaline derivative. Black-Right-Pointing-Pointer The effect of 4-chlorotetrazolo[1,5-a]quinoxaline on mast cells was investigated. Black-Right-Pointing-Pointer 4-chlorotetrazolo[1,5-a]quinoxaline reversibly inhibited Syk activation. Black-Right-Pointing-Pointer 4-chlorotetrazolo[1,5-a]quinoxaline could be useful for IgE-mediated allergy.« less
  • Hepatic lipase can enhance the delivery of high-density lipoprotein (HDL) cholesterol to cells by a process which does not involve apoprotein catabolism. The incorporation of HDL-free (unesterified) cholesterol, phospholipid, and cholesteryl ester by cells has been compared to establish the mechanism of this delivery process. Human HDL was reconstituted with /sup 3/H-free cholesterol and (/sup 14/C)sphingomyelin, treated with hepatic lipase in the presence of albumin to remove the products of lipolysis, reisolated, and then incubated with cultured rat hepatoma cells. Relative to control HDL, modification of HDL with hepatic lipase stimulated both the amount of HDL-free cholesterol taken up bymore » the cell and the esterification of HDL-free cholesterol but did not affect the delivery of sphingomyelin. Experiments utilizing HDL reconstituted with /sup 14/C-free cholesterol and (/sup 3/H)cholesteryl oleoyl ether suggest that hepatic lipase enhances the incorporation of HDL-esterified cholesterol. However, the amount of free cholesterol delivered as a result of treatment with hepatic lipase was 4-fold that of esterified cholesterol. On the basis of HDL composition, the cellular incorporation of free cholesterol was about 10 times that which would occur by the uptake and degradation of intact particles. The preferential incorporation of HDL-free cholesterol did not require the presence of lysophosphatidylcholine. To correlate the events observed at the cellular level with alterations in lipoprotein structure, high-resolution, proton-decoupled /sup 13/C nuclear magnetic resonance spectroscopy (90.55 MHz) was performed on HDL3 in which the cholesterol molecules were replaced with (4-/sup 13/C)cholesterol by particle reconstitution.« less
  • The metabolism of infused /sup 111/In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t/sub 1/2/) for clearance of /sup 111/In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits. By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue sores.more » Disappearance of excess plasma cholesterol was > 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative ..gamma.. camera imaging, hepatic trapping of /sup 111/In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance. Aortic uptake of /sup 111/In was < 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, the results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.« less
  • Normal human monocyte-macrophages were cholesterol-loaded, and the rates of uptake and degradation of several lipoproteins were measured and compared to rates in control cells. Receptor activities for SVI-rabbit beta-very low density lipoproteins (beta-VLDL), SVI-human low density lipoprotein, and SVI-human chylomicrons were down-regulated in cholesterol-loaded cells; however, the rate of uptake and degradation of SVI-human chylomicron remnants was unchanged from control cells. Cholesterol-loaded alveolar macrophages from a Watanabe heritable hyperlipidemic rabbit, which lack low density lipoprotein receptors, showed receptor down-regulation for SVI-beta-VLDL but not for SVI-human chylomicron remnants. In addition to chylomicron remnants, apo-E-phospholipid complexes competed for SVI-chylomicron remnant uptake, butmore » apo-A-I-phospholipid complexes did not. Chylomicron remnants and beta-VLDL were equally effective in competing for SVI-beta-VLDL and SVI-chylomicron remnant uptake in cholesterol-loaded macrophages. The authors conclude: 1) specific lipoprotein receptor activity persists in cholesterol-loaded cells; 2) this receptor activity recognizes lipo-proteins (at least in part) by their apo-E content; and 3) cholesteryl ester accumulation can occur in monocyte-macrophages incubated with chylomicron remnants.« less