Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 2018 Sep 4;115(36):E8499-E8508. doi: 10.1073/pnas.1810724115. Epub 2018 Aug 20.

Macrophages release plasma membrane-derived particles rich in accessible cholesterol.

Author information

1
Department of Medicine, University of California, Los Angeles, CA 90095.
2
Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA 90095.
3
Centre for Microscopy, Characterisation and Analysis, University of Western Australia, 6009 Perth, WA, Australia.
4
School of Biomedical Sciences, University of Western Australia, 6009 Perth, WA, Australia.
5
Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095.
6
Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095.
7
Department of Biochemistry, National Centre of Competence in Research in Chemical Biology, University of Geneva, 1205 Geneva, Switzerland.
8
Department of Medicine, University of California, Los Angeles, CA 90095; haibo.jiang@uwa.edu.au sgyoung@mednet.ucla.edu.
9
School of Molecular Sciences, University of Western Australia, 6009 Perth, WA, Australia.
10
Department of Human Genetics, University of California, Los Angeles, CA 90095.

Abstract

Macrophages are generally assumed to unload surplus cholesterol through direct interactions between ABC transporters on the plasma membrane and HDLs, but they have also been reported to release cholesterol-containing particles. How macrophage-derived particles are formed and released has not been clear. To understand the genesis of macrophage-derived particles, we imaged mouse macrophages by EM and nanoscale secondary ion mass spectrometry (nanoSIMS). By scanning EM, we found that large numbers of 20- to 120-nm particles are released from the fingerlike projections (filopodia) of macrophages. These particles attach to the substrate, forming a "lawn" of particles surrounding macrophages. By nanoSIMS imaging we showed that these particles are enriched in the mobile and metabolically active accessible pool of cholesterol (detectable by ALO-D4, a modified version of a cholesterol-binding cytolysin). The cholesterol content of macrophage-derived particles was increased by loading the cells with cholesterol or by adding LXR and RXR agonists to the cell-culture medium. Incubating macrophages with HDL reduced the cholesterol content of macrophage-derived particles. We propose that release of accessible cholesterol-rich particles from the macrophage plasma membrane could assist in disposing of surplus cholesterol and increase the efficiency of cholesterol movement to HDL.

KEYWORDS:

accessible cholesterol; cholesterol efflux; nanoSIMS

PMID:
30127022
PMCID:
PMC6130402
[Available on 2019-03-04]
DOI:
10.1073/pnas.1810724115
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center