TitleCholesterol loading reprograms the microRNA-143/145-myocardin axis to convert aortic smooth muscle cells to a dysfunctional macrophage-like phenotype.
Publication TypeJournal Article
Year of Publication2015
AuthorsVengrenyuk, Y, Nishi, H, Long, X, Ouimet, M, Savji, N, Martinez, FO, Cassella, CP, Moore, KJ, Ramsey, SA, Miano, JM, Fisher, EA
JournalArterioscler Thromb Vasc Biol
Volume35
Issue3
Pagination535-46
Date Published2015 Mar
ISSN1524-4636
KeywordsAnimals, Aorta, Thoracic, Apolipoproteins E, Atherosclerosis, Binding Sites, Cell Lineage, Cell Transdifferentiation, Cholesterol, Cholesterol, HDL, Coculture Techniques, Disease Models, Animal, Foam Cells, Gene Expression Profiling, Gene Expression Regulation, Humans, Jurkat Cells, Mice, Inbred C57BL, Mice, Knockout, MicroRNAs, Muscle, Smooth, Vascular, Myocytes, Smooth Muscle, Necrosis, Nuclear Proteins, Oligonucleotide Array Sequence Analysis, Phagocytosis, Phenotype, Plaque, Atherosclerotic, Signal Transduction, Sterol Regulatory Element Binding Protein 2, Time Factors, Trans-Activators, Transfection
Abstract

OBJECTIVE: We previously showed that cholesterol loading in vitro converts mouse aortic vascular smooth muscle cells (VSMC) from a contractile state to one resembling macrophages. In human and mouse atherosclerotic plaques, it has become appreciated that ≈40% of cells classified as macrophages by histological markers may be of VSMC origin. Therefore, we sought to gain insight into the molecular regulation of this clinically relevant process.

APPROACH AND RESULTS: VSMC of mouse (or human) origin were incubated with cyclodextrin-cholesterol complexes for 72 hours, at which time the expression at the protein and mRNA levels of contractile-related proteins was reduced and of macrophage markers increased. Concurrent was downregulation of miR-143/145, which positively regulate the master VSMC differentiation transcription factor myocardin. Mechanisms were further probed in mouse VSMC. Maintaining the expression of myocardin or miR-143/145 prevented and reversed phenotypic changes caused by cholesterol loading. Reversal was also seen when cholesterol efflux was stimulated after loading. Notably, despite expression of macrophage markers, bioinformatic analyses showed that cholesterol-loaded cells remained closer to the VSMC state, consistent with impairment in classical macrophage functions of phagocytosis and efferocytosis. In apoE-deficient atherosclerotic plaques, cells positive for VSMC and macrophage markers were found lining the cholesterol-rich necrotic core.

CONCLUSIONS: Cholesterol loading of VSMC converts them to a macrophage-appearing state by downregulating the miR-143/145-myocardin axis. Although these cells would be classified by immunohistochemistry as macrophages in human and mouse plaques, their transcriptome and functional properties imply that their contributions to atherogenesis would not be those of classical macrophages.

DOI10.1161/ATVBAHA.114.304029
Alternate JournalArterioscler Thromb Vasc Biol
PubMed ID25573853
PubMed Central IDPMC4344402
Grant ListR01 HL117907 / HL / NHLBI NIH HHS / United States
HL098055 / HL / NHLBI NIH HHS / United States
R01 HL117334 / HL / NHLBI NIH HHS / United States
T32 HL098129 / HL / NHLBI NIH HHS / United States
R01 HL108182 / HL / NHLBI NIH HHS / United States
HL112793 / HL / NHLBI NIH HHS / United States
P01 HL098055 / HL / NHLBI NIH HHS / United States
HL108182 / HL / NHLBI NIH HHS / United States
R01 HL132574 / HL / NHLBI NIH HHS / United States
HL098807 / HL / NHLBI NIH HHS / United States
R01 HL112793 / HL / NHLBI NIH HHS / United States
R01 HL084312 / HL / NHLBI NIH HHS / United States
HL084312 / HL / NHLBI NIH HHS / United States
K25 HL098807 / HL / NHLBI NIH HHS / United States
HL117334 / HL / NHLBI NIH HHS / United States
HL117907 / HL / NHLBI NIH HHS / United States