Abstract 16789: Loss of Endothelial Barrier in Fibrillin-1-Deficient Marfan Mice (mgR/mgR) Results in Severe Inflammation After Adenoviral Gene Therapy

Abstract

Introduction: Nowadays surgery still remains option of choice for therapy of aneurysm in Marfan syndrome. Aortic tissue of Marfan patients shows elastolysis enhanced by proteolytic activity of Matrix Metalloproteinases (MMPs). In this study we performed adenoviral gene transfer of Tissue Inhibitor of MMP-1 (TIMP-1) in aortic grafts of Fibrillin-1-deficient Marfan mice (mgR/mgR) in order to reduce aortic elastolysis. Methods: We performed heterotopic infrarenal transplantation of thoracic aorta in female mice (n=35, n=7/group). MgR/mgR and wild-type (WT) aorta (C57BL/6) was either incubated ex vivo with adenoviral vector coding for human TIMP-1 or ß-Galactosidase (5x10^9pfu/ml) or as control with culture medium. 30 days after surgery overexpression of transgene was assessed by immunohistochemistry (IHC) and collagen in situ zymography (ISZ). Histologic staining was performed to outline elastin breaks, signs of inflammation and Neointimal Index (NI). Endothelial barrier was evaluated with the use of transmission electron microscope (TEM) and perfusion of fluorescent albumin. Results: IHC and ISZ revealed sufficient expression of transgene. Severe intimal hyperplasia and distinctive signs of cellular inflammation were solely observed in mgR/mgR aorta after adenoviral transduction (NI: ß-Gal 0.23; TIMP-1 0.43), but not in WT aorta (NI: Native 0.01; TIMP-1 0.00). Compared to native mgR/mgR and TIMP-1 treated WT aorta, NI in TIMP-1 treated mgR/mgR aorta was highly significantly larger (p=0.001; p=0.001). Native mgR/mgR grafts presented with severe elastolysis compared to WT (p=0.001). Regardless of the vector transduced elastolysis in mgR/mgR aorta after adenoviral gene therapy was more pronounced compared to WT aorta (ß-Gal p=0.001; TIMP-1 p=0.001). Albumin diffusion through the endothelial barrier was increased in native mgR/mgR aorta compared to native WT aorta (p=0.037). TEM analysis of mgR/mgR aorta displayed reconstruction of the basement membrane and basolateral space. Conclusions: Murine Marfan aortic grafts developed severe inflammation after adenoviral exposure. Fibrillin-1-deficiency is associated with dysfunction of endothelial barrier which could be a target for alternative therapies in Marfan syndrome.