| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
|
|---|
| Research Abstract |
The purpose of this study was to evaluate the potential roles of matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases, TIMPs) in disruption of atherosclerotic plaques and to understand the cellular and molecular mechanisms of plaque disruption. The results revealed :
1. Studies using immunohistochemistry and in situ hybridization showed that MNP-1, MMP-2, MMP-3, MMP-9, TIMP-1 andTIMP-2 mRNA and protein were localized in both macrophages and smooth muscle celis in all plaques. MT1-MMP mRNA and protein, an activator of proMMP-2, colocalized with proMMP-2. MMP-7 and MNP-12, which can degrade elastin, were also detected in the plaques ;
2. The predominant cells is expressing MMP-1 and MMP-2 in Plaques' shoulder region, where disruption most frequently occurs, were macrophages. In lipid core, MMP-1 was also predominantly expressed in macrophages ;
3. On enzyme assay with 14C-gelatin, 14C-collagen or 3H-elastin as a substrate, each proteolytic activity could be detected in all plaques. The gelatinolytic and collagenolytic activitie were significantly higher in fibrous caps and shoulder regions than in lipid cores. Elastinolytic activity in fibrous caps and lipid cores was significantly higher than in shoulder regions of the plaques ;
4. To test directly whether plaques actually contain active matrix - degrading enzymes in situ, enzymatic activity was analysed directly in tissue sections by in situ zymography and film in situ zymography (FIZ). A major area of gelatin lysis localized in the shoulders of plaques. The gelatinolytic activity detected by FIZ showed similar distribution to those of expression of MMP-2 and MT1-MMP proteins demonstrated by the immunohistochemistry. Furthermore, FIZ and immunohistochemistry localized gelatinolytic activity around the macrophages indicating that proMMP-2 produced mostly by macrophages might be activated by MT1-MMP in the shoulder regions.
|
