Increased expression of urotensin II and its cognate receptor GPR14 in atherosclerotic lesions of the human aorta

Urotensin II (U-II), a novel vasoactive peptide, possesses a wide range of cardiovascular effects. U-II binds a seven transmembrane spanning G-protein coupled receptor termed GPR14. In the present study, we have characterized U-II expression in both carotid and aortic atherosclerotic plaques. Using immunohistochemistry we demonstrated U-II immunoreactivity in endothelial, smooth muscle and inflammatory cells of both carotid and aortic plaques, with a clear propensity for intimal staining. Using quantitative real-time RT-PCR we observed both increased U-II and GPR14 mRNA expression in tissue extracts from abdominal aortic aneurysms. We also extended our PCR analysis to include leukocyte expression of U-II and GPR14. We found that lymphocytes were by far the largest producers of U-II mRNA. In contrast monocytes and macrophages were the largest producers of GPR14 mRNA, with relatively little expression in foam cells, lymphocytes, and platelets. Our findings qualitatively and quantitatively demonstrate increased expression of U-II in atherosclerosis with a large degree of inflammatory cell involvement. These findings suggest a possible role for U-II in the pathophysiology of atherosclerosis.