English
Gabriella Doronzo, Isabella Russo, Luigi Mattiello, Mariella Trovati, Giovanni Anfossi
Diabetes Unit, Department of Clinical and Biological Sciences of the University of Turin, San Luigi Gonzaga Hospital, Orbassano (Turin), Italy
Summary
In this study we aimed to test the hypothesis that in human vascular smooth muscle cells (VSMC) homocysteine influences synthesis and release of matrix metalloproteinase-2 (MMP-2), which is deeply involved in vascular remodeling and atherosclerotic plaque instabilization. Experiments were carried out in cultured human VSMC exposed to 50–500 µ mol/l homocysteine after a 24-hour culture with MEM containing 0.1% BSA. Both in supernatants and cell lysates we evaluated MMP-2 activity (gelatin zimography), MMP-2 and TIMP-2 protein synthesis (Western immunoblotting). Homocysteine effects were investigated also after cell exposure to i) specific MEK inhibitor PD98059 (30 µ mol/l) to evaluate the involvement of Mitogen-Activated Protein Kinase (MAPK) and ii) specific phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002 (100 µ mol/l) to evaluate the involve ment of PI3-K pathway. Gelatin zimography evidenced that MMP-2 activity is increased both in conditioned media and in cell lysates starting from 8-hour incubation with 100 µ mol/l homocysteine. Western blot analysis evidenced increased MMP-2 levels in both conditioned media and cell lysates. Cell exposure to PD98059 and LY294002 prevented homocysteine effects on MMP-2 synthesis. Homocysteine, at concentrations associated with increased risk of cardiovascular events, increases MMP-2 activity, synthesis and secretion in VSMC through a mechanism involving the activation of MAPK and PI3-K pathways.These data suggest that homocysteine is directly involved in mechanisms leading to remodelling and instabilization of atherosclerotic plaques.
DOI
10.1160/TH05-04-0221
PDF 469.2 kb
Download für Abonnenten / Download for subscribers
Kostenpflichtiger Download für Nicht-Abonnenten / Charged download for non-subscribers