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Int J Clin Exp Pathol 2011;4(3):287-294

Original Article
Smooth muscle homeostasis in human atherosclerotic plaques through Interleukin 15

Jelger J. van der Meer, Onno J. de Boer, Peter Teeling, Chris M. van der Loos, Mark C. Dessing, Allard C. van der Wal

Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands

Received March 10, 2011; accepted March 18, 2011; Epub March 22; published March 31, 2011

Abstract: Interleukin (Il)-15 is a cytokine that has a broad tissue distribution and is important in maintaining homeostasis of cells and stability
of tissues. When Il-15 is also expressed by vascular smooth muscle cells (SMC), which are the dominant type of cells in most atherosclerotic
plaques, it could be important in maintaining plaque tissue integrity and hence resistance of plaques towards development of clinically relevant
complications such as plaque rupture and thrombosis. In this study, Il-15 and Il-15Rα in vitro expression by coronary artery SMC  was
investigated using RT-PCR and FACS analysis. Immunohistochemistry was used to study in situ expression of Il-15 and Il-15R by SMC of
human carotid artery atherosclerotic plaques. Multiplex ligand-dependent probe amplification (MLPA) was used to investigate the mRNA
expression of 40 pro- and anti inflammatory genes after stimulating coronary SMC with Il-15. We found that atherosclerotic SMC express both Il-
15 and its receptor Il-15R, and IFN-γ and TNF-α enhance Il-15R expression in cultured SMC. MLPA studies on SMC revealed enhanced
expression of PDGF beta mRNA after Il15 stimulation. In conclusion, our data suggest that IL-15 may contribute to atherosclerotic plaque
integrity by stimulation of smooth muscle cells, probably in a PDGF dependent fashion. (IJCEP1103005).

Keywords: Atherosclerosis, Smooth muscle cells, cytokines, plaque stability

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Address all correspondence to:
Dr. Allard C van der Wal
Department of Pathology, Academic Medical Center
Meibergdreef 9,1105AZ Amsterdam, the Netherlands.
Tel: +31 (0)20-566 5633. Fax: +31 (0)20-566 9523.