Abstract
The osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) cytokine system, not only controls bone homeostasis, but has been implicated in regulating vascular calcification. TNF-related apoptosis-inducing ligand (TRAIL) is a second ligand for OPG, and although its effect in vascular calcification in vitro is controversial, its role in vivo is not yet established. This study aimed to investigate the role of TRAIL in vascular calcification in vitro using vascular smooth muscle cells (VSMCs) isolated from TRAIL(-/-) and wild-type mice, as well as in vivo, in advanced atherosclerotic lesions of TRAIL(-/-)ApoE(-/-) mice. The involvement of OPG and RANKL in this process was also examined. TRAIL dose-dependently inhibited calcium-induced calcification of human VSMCs, while TRAIL(-/-) VSMCs demonstrated accelerated calcification induced by multiple concentrations of calcium compared to wild-type cells. Consistent with this, RANKL mRNA was significantly elevated with 24 h calcium treatment, while OPG and TRAIL expression in human VSMCs was inhibited. Brachiocephalic arteries from TRAIL(-/-)ApoE(-/-) and ApoE(-/-) mice fed a high fat diet for 12 w demonstrated increased chondrocyte-like cells in atherosclerotic plaque, as well as increased aortic collagen II mRNA expression in TRAIL(-/-)ApoE(-/-) mice, with significant increases in calcification observed at 20 w. TRAIL(-/-)ApoE(-/-) aortas also had significantly elevated RANKL, BMP-2, IL-1β, and PPAR-γ expression at 12 w. Our data provides the first evidence that TRAIL deficiency results in accelerated cartilaginous metaplasia and calcification in atherosclerosis, and that TRAIL plays an important role in the regulation of RANKL and inflammatory markers mediating bone turn over in the vasculature.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Aorta / metabolism*
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Aorta / pathology
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Apolipoproteins E / deficiency
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Apolipoproteins E / genetics
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Atherosclerosis / genetics*
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Atherosclerosis / metabolism
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Atherosclerosis / pathology
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Brachiocephalic Trunk / metabolism*
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Brachiocephalic Trunk / pathology
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Calcium / metabolism
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Calcium / pharmacology
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Cells, Cultured
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Chondrocytes / drug effects
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Chondrocytes / metabolism
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Chondrocytes / pathology
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Collagen Type II / genetics
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Collagen Type II / metabolism
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Diet, High-Fat
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Gene Expression Regulation
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Humans
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Mice
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Mice, Knockout
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Muscle, Smooth, Vascular / drug effects
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Muscle, Smooth, Vascular / metabolism
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Muscle, Smooth, Vascular / pathology
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Myocytes, Smooth Muscle / drug effects
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Myocytes, Smooth Muscle / metabolism
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Myocytes, Smooth Muscle / pathology
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Osteoprotegerin / genetics
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Osteoprotegerin / metabolism
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Plaque, Atherosclerotic / genetics*
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Plaque, Atherosclerotic / metabolism
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Plaque, Atherosclerotic / pathology
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RANK Ligand / genetics*
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RANK Ligand / metabolism
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Signal Transduction
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TNF-Related Apoptosis-Inducing Ligand / deficiency
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TNF-Related Apoptosis-Inducing Ligand / genetics*
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TNF-Related Apoptosis-Inducing Ligand / pharmacology
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Vascular Calcification / genetics*
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Vascular Calcification / metabolism
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Vascular Calcification / pathology
Substances
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Apolipoproteins E
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Collagen Type II
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Osteoprotegerin
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RANK Ligand
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RNA, Messenger
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TNF-Related Apoptosis-Inducing Ligand
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TNFRSF11B protein, human
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Calcium
Grants and funding
This project was supported by NHMRC Project Grant 568627. MMK is supported by a Heart Foundation of Australia Career Development Fellowship. BAD is supported by an NHMRC Early Career Fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.