Effect of TGF-β₁ Antisense S-Oligonucleotide on Synthesis and Accumulation of Matrix Proteoglycans in Balloon Catheter-Injured Neointima of Rabbit Carotid Arteries

Abstract

Arterial matrix proteoglycans (PG) are necessary for the maintenance of viscoelastic properties of the vessel wall, but excess levels, particularly of versican and biglycan in primary and restenotic intimal thickenings, are correlated with increased tissue volume and with atherogenicity. There is good evidence that the primary stimulus to increased PG synthesis, including versican and biglycan, is transforming growth factor-β₁ (TGF-β₁). The aim of this study was to determine the effects of reducing endogenous TGF-β₁ on rates and patterns of PG synthesis and on versican, biglycan and decorin accumulation in vivo. Rabbit common carotid arteries subjected to balloon catheter injury were treated with a TGF-β₁ antisense phosphorothioate oligonucleotide applied in a pluronic gel to the adventitia. Control animals received a nonsense oligonucleotide or gel alone. TGF-β₁ antisense (1) significantly (p < 0.005) inhibited, at day 2, the balloon catheter-induced increase in TGF-β₁ mRNA relative to β-actin mRNA; (2) inhibited intimal thickening at 23 days by ∼40% (p < 0.05); (3) inhibited (p < 0.05) PG synthesis, measured by autoradiographic detection of [³H]glucosamine, in the media of day 2 ballooned carotids and in the subendothelial zone of day 23 neointima, and (4) decreased immunostaining intensity for versican (p < 0.03) and TGF-β₁ (p < 0.001) in the neointima. Biglycan was reduced to a lesser extent but not significantly and decorin was not affected. Proliferating cell nuclear antigen indices were variable and not significantly changed. These findings confirm a role for TGF-β₁ in developing neointima and demonstrate a specific effect on the synthesis, distribution, and accumulation of matrix PG, particularly versican.

Estrogen decreases biglycan mRNA expression in resistance blood vessels

“…If the content of a structural protein, such as biglycan, is increased in the blood vessel wall, it will decrease the compliance of that vessel and will create a stiffer vessel. Abnormal expression of biglycan has been identified in the development and progression of cardiovascular pathologies (8,31). Biglycan, in particular, has been shown to bind extracellular proteins such as growth factors (10,20) and large macromolecules such as low-density lipoproteins (14,35,36,43) in the subendothelium of the vessel wall.…”

“…Biglycan, in particular, has been shown to bind extracellular proteins such as growth factors (10,20) and large macromolecules such as low-density lipoproteins (14,35,36,43) in the subendothelium of the vessel wall. Increased concentrations of biglycan have been found in arterial plaques in experimental animal models (31,32,57) as well as in human vessel biopsies (18). Moreover, the application of mechanical deformation or shear forces on vascular smooth muscle cells has been shown to upregulate biglycan mRNA expression (26).…”

“…Matrix proteoglycans such as biglycan are important in modulating the vessel wall structural integrity (24) and would be expected to influence biophysical properties such as compliance. Abnormal expression of some of these proteoglycans in the vasculature has been identified in the development and progression of cardiovascular pathologies (8,31). Given the potential importance of biglycan in regulating vascular function, this gene was chosen for followup studies using semiquantitative RT-PCR to confirm and quantitate estrogen-regulated biglycan mRNA expression.…”

Subendothelial Lipoprotein Retention as the Initiating Process in Atherosclerosis

“…If such manipulation resulted in decreased synthesis of the most highly retentive proteoglycans, lipoprotein retention and ensuing atherogenesis could be suppressed. 110 However, the evidence that retentive mechanisms differ between early atherogenesis versus established lesion progression makes these strategies extremely challenging. Moreover, interference with endothelial lipolysis or hepatic catabolism of triglyceride-rich lipoproteins, which also involve lipoproteinproteoglycan interactions, 71,111 needs to be avoided.…”

SM16, an Orally Active TGF-β Type I Receptor Inhibitor Prevents Myofibroblast Induction and Vascular Fibrosis in the Rat Carotid Injury Model

“…The subsequent interaction of this complex with their respective type I receptors, ALK5 and ALK4, allows the interaction with and phosphorylation of type I receptor-associated signaling proteins, Smad2 and Smad3. 11,12 Blockade of TGF-␤ signaling with either the soluble TGF-␤ type II receptor extracellular domain-Fc fusion protein (sTGF-␤RII:Fc), 5,7 antibodies to TGF-␤1, 13 decorin, 14 TGF-␤ antisense oligonucleotides, [15][16][17] or adenovirus Smad7 18 was shown previously to inhibit vascular fibrosis in animal models. Here, we identified SM16, a potent, selective and orally active ALK5/ALK4 kinase inhibitor which potently inhibits TGF-␤-induced phosphorylation of Smad2 and Smad3 in cells and neointimal thickening and vascular remodeling in the rat carotid balloon injury model.…”