Tenascin expression is associated with a chronic inflammatory process in abdominal aortic aneurysms.

Abstract

This study was performed to test whether tenascin, a large oligomeric glycoprotein of the extracellular matrix, is present in AAA disease and whether it could play a pathophysiologic role in the development of this disease. Tenascin immunoreactivity was investigated from samples of the aneurysmal walls of 17 patients with AAAs, and the results were compared with the results of those of six patients with aortoiliac occlusive disease (AOD) and one normal control patient. To study the source of tenascin mRNA synthesis, some tissue samples were also examined with a tenascin RNA probe by in situ hybridization. The difference in immunoreactivity between the AODs and AAAs was especially prominent in the adventitial layer, where the specimens from AAAs displayed strong diffuse and reticular immunostaining. In AAAs the immunostaining was clearly associated with the degree of mononuclear inflammatory cell infiltrate and with the neovascularization of the adventitial layer. Tenascin expression is evident in AAA disease and is distinctly associated with mononuclear inflammatory cells. The adhesive properties of tenascin may offer a relevant explanation for the mechanism by which monocytes transmigrate into the aortic wall. The definitive role of tenascin in AAA process may be more complex, however, and will necessitate further investigation.