Immunohistochemical analysis of the plasminogen activation system and the matrix metalloproteinases in normal and atherosclerotic human vessels

Abstract

In this study we examined the localization of the plasminogen activation system and the matrix metalloproteinases in normal human arteries, arteries with diffuse intimal thickenings and atherosclerotic arteries. We found that MMP-1, MMP-2, MMP-3, TIMP-1 and TIMP-2 did not stain differently in normal arteries, arteries with intimal thickening and atherosclerotic arteries. MMP-9 staining was, however, increased in atherosclerotic arteries as compared to normal arteries and arteries with diffuse intimal thickening. For u-PA there were no differences between normal arteries, arteries with intimal thickening and atherosclerotic arteries. t-PA staining was decreased in the media of atherosclerotic arteries as compared to both normal and intima-thickened arteries. In contrast, PAI-1 staining was elevated in the intima of atherosclerotic arteries as compared to the media. While u-PAR was elevated in the intima of arteries with intimal thickening, staining was weaker in the intima of atherosclerotic arteries, as compared to the intima of normal arteries. These results suggest that both the plasminogen activation system and the MMP system might be involved in the process of atherosclerosis most likely in different steps and stages in this process.