Type A dissection and chronic dilatation: tenascin-C as a key factor in destabilization of the aortic wall

Abstract

OBJECTIVES: Tenascin-C plays an important role in myocardial and vascular remodelling. We hypothesized that tenascin-C is a key factor in the development of degenerative disease of the ascending aorta, leading to chronic dilatation and acute aortic dissection. METHODS: Ascending aortic wall specimens were obtained during surgery for chronic dilatation (n=52) and acute Type A dissection (n=30). Patients (n=12) undergoing aortic valve replacement served as controls. Tenascin-C expression was evaluated by immunostaining and semi-quantitatively assessed using the ImageJ software. TN-C levels in peripheral blood were determined by enzyme-linked immunosorbent assay. RESULTS: Histological examination showed a clear difference between chronic dilatation and acute dissection. In chronic dilatation, tenascin-C staining was homogenously distributed throughout the media parallel to vascular smooth muscle cells. In acute dissection, a strong staining with a heterogenous and spotty distribution was detected. Control aortas showed no tenascin-C staining. Tenascin-C expression was significantly higher in Type-A dissection compared with chronic dilatation. This was accompanied by a significant elevation of tenascin-C levels in peripheral blood in acute dissection. There was no statistical correlation between the tenascin-C level in peripheral blood and the aortic diameter either in dissection or in dilatation. CONCLUSIONS: Tenascin-C is a marker of progressive destabilization of the aortic wall independent of size in chronic dilatation and acute dissection. Therefore, it might be a valuable tool in guiding intervention strategies in patients with disease of the ascending aorta.