Extracellular matrix metalloproteinase inducer (EMMPRIN) is present in smooth muscle cells of human aneurysmal aorta and is induced by angiotensin II in vitro

The aim of the present study was to determine whether EMMPRIN (extracellular matrix metalloproteinase inducer) is present and is up-regulated in human aneurysmal aortas, and to assess a possible association with AngII (angiotensin II)-induced aneurysm formation. The presence of EMMPRIN was assessed in 41 surgical specimens from patients with a TAA (thoracic aortic aneurysm) (Type A aortic dissection, n=12; Type B aortic dissection, n=7; and TAA without dissection, n=7) or an AAA (abdominal aortic aneurysm, n=15) by immunohistochemistry. EMMPRIN expression in aortic aneurysm tissues was compared with 12 aortas obtained during autopsy (free of any vascular diseases), and scored for both staining intensity and the percentage of vascular cells stained. EMMPRIN protein levels in cultured human aortic SMCs (smooth muscle cells) following stimulation of AngII were analysed by Western blotting. Significant EMMPRIN immunoreactivity was detected in aortic aneurysm lesions from patients with TAAs and AAAs. In the aneurysmal wall, α-actin-positive SMCs were the main source of EMMPRIN. The frequency of EMMPRIN overexpression was significantly higher (P=0.026) in TAAs with dissection (68.4%) than TAAs without dissection (14.3%). AngII stimulation up-regulated the expression of EMMPIRN in cultured human aortic SMCs, which was suppressed by the addition of the AT₁R (AngII type 1 receptor) antagonist losartan. In conclusion, the present study is the first to report the expression of EMMPRIN in aortic aneurysmal diseases, and we speculate that EMMPRIN may be important in the pathogenesis of these diseases. Whether these abnormalities are potential therapeutic targets deserve further investigation.