Macrophages release plasma membrane-derived particles rich in accessible cholesterol

Cuiwen He, Xuchen Hu, Thomas A. Weston, Rachel S. Jung, Jaspreet Sandhu, Song Huang, Patrick Heizer, Jason Kim, Rochelle Ellison, Jiake Xu, Matthew Kilburn, Steven J. Bensinger, Howard Riezman, Peter Tontonoz, Loren G. Fong, Haibo Jiang, Stephen G. Young

Research output: Contribution to journalArticle

16 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)E8499-E8508
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number36
DOIs
Publication statusPublished - 4 Sep 2018

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