Cardiovascular Research Advance Access originally published online on July 1, 2009
Cardiovascular Research 2009 84(2):326-335; doi:10.1093/cvr/cvp220
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Arterial gene transfer of the TGF-β signalling protein Smad3 induces adaptive remodelling following angioplasty: a role for CTGF
1 Division of Vascular Surgery, Weill Medical College of Cornell University, Columbia College of Physicians and Surgeons, New York Presbyterian Hospital, New York, NY, USA
2 Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, WIMR 5137, Madison, WI 53705, USA
* Corresponding author. Tel: +1 608 265 5139; fax: +1 608 262 3333. E-mail address: liub{at}surgery.wisc.edu
Aims: Although transforming growth factor-beta (TGF-β) is believed to stimulate intimal hyperplasia after arterial injury, its role in remodelling remains unclear. We investigate whether Smad3, a TGF-β signalling protein, might facilitate its effect on remodelling.
Methods and results: Using the rat carotid angioplasty model, we assess Smad3 expression following arterial injury. We then test the effect of arterial Smad3 overexpression on the response to injury, and use a conditioned media experimental design to confirm an Smad3-dependent soluble factor that mediates this response. We use small interfering RNA (siRNA) to identify this factor as connective tissue growth factor (CTGF). Finally, we attempt to replicate the effect of medial Smad3 overexpression through adventitial application of recombinant CTGF. Injury induced medial expression of Smad3; overexpression of Smad3 caused neointimal thickening and luminal expansion, suggesting adaptive remodelling. Smad3 overexpression, though exclusively medial, caused adventitial changes: myofibroblast transformation, proliferation, and collagen production, all of which are associated with adaptive remodelling. Supporting the hypothesis that Smad3 initiated remodelling and these adventitial changes via a secreted product of medial smooth muscle cells (SMCs), we found that media conditioned by Smad3-expressing recombinant adenoviral vector (AdSmad3)-infected SMCs stimulated adventitial fibroblast transformation, proliferation, and collagen production in vitro. This effect was attenuated by pre-treatment of SMCs with siRNA specific for CTGF, abundantly produced by AdSmad3-infected SMCs, and significantly up-regulated in Smad3-overexpressing arteries. Moreover, periadventitial administration of CTGF replicated the effect of medial Smad3 overexpression on adaptive remodelling and neointimal hyperplasia.
Conclusion: Medial gene transfer of Smad3 promotes adaptive remodelling by indirectly influencing the behaviour of adventitial fibroblasts. This arterial cell–cell communication is likely to be mediated by Smad3-dependent production of CTGF.
KEYWORDS TGF-β; Smad3; Connective tissue growth factor; Restenosis; Remodelling; Adventitia
Time for primary review: 36 days