Abstract 17296: Aortic Elastolysis is Reduced by AP-1 Oligodeoxynucleotide-mediated Downregulation of Matrix Metalloproteinases in a Murine Model of Marfan Syndrome
The vascular phenotype of Marfan syndrome is characterized by high expression and activity of matrix metalloproteinases (MMPs) in aortic smooth muscle cells leading to medial elastolysis and aortic root aneurysm. The transcription factor activating factor-1 (AP-1) plays a pivotal role in the regulation of MMP expression. We hypothesized that decoy oligodeoxynucleotides (dODN) are capable of neutralizing AP-1, leading to decreased MMP expression and therefore reduced aortic elastolysis in a Marfan mouse model.
Murine aortal smooth muscle cells (mAoSMC) from fibrillin-1 deficient Marfan (mgR/mgR) and wildtype (wt) mice were isolated and cultured. MMP expression and activity were assessed by western blotting and immunoprecipitation combined with zymography. Gel electrophoresis mobility shift assay was used to determine AP-1 binding activity in nuclear extracts. Aortic grafts from young (6-9 weeks old) donor mgR/mgR mice were treated with AP-1 dODN or mutated controls ex vivo and implanted as infrarenal aortic interposition grafts in mgR/mgR mice. Grafts were explanted after 30 days for Elastica-van-Giesson staining to visualize elastolysis.
AP-1 was increased in nuclear extracts of Marfan mAoSMCs as compared to wt mAoSMCs (n=3, p=0.03), resulting in higher MMP expression of Marfan mAoSMCs, too (n=3, p=0.016). Pretreatment of wt mAoSMCs with AP-1 dODN resulted in a reduction of MMP-9 expression by 87% (n=6, p=0.016), and decreased MMP-9 activity by 50% (n=4, p=0.025) as compared to untreated controls. In Marfan mAoSMCs, pretreatment resulted in reduced MMP-2 expression and activity by 80% (n=5, p=0.025) and 70% (n=7, p=0.002), respectively. MMP-9 expression was down-regulated by 70% (n=5, p=0.041) in these cells. First in vivo experiments indicate a significantly (n=3, p<0.0001) reduced elastolysis in explanted aortic grafts of mgR/mgR mice pretreated with AP-1 dODN compared to untreated mgR/mgR aortas.
In conclusion, AP-1 neutralization results in a significant inhibition of both MMP expression and activity in targeted aortic smooth muscle cells. Subsequently, medial elastolysis was reduced in aortic grafts of Marfan mice. The findings may lead to a new nucleic-acid based therapeutic concept for the vascular phenotype of Marfan syndrome.
- © 2013 by American Heart Association, Inc.