Down-regulation in the production of matrix metalloproteinase 1 by human aortic intimal smooth muscle cells.

: Effects of dexamethasone, retinoic acid, prostaglandin E2 (PGE2), and Iloprost as a agonist of prostacyclin (A-PGI2) on DNA synthesis and production of a precursor of matrix metalloproteinase 1 (tissue procollagenase/proMMP-1) by human aortic smooth muscle cells were investigated. When after treatment with platelet-derived growth factor (PDGF), these agents were added to the cultures, DNA synthesis and production of proMMP-1 were inhibited in a dose-dependent manner. These results suggest that these agents are negative regulators of PDGF. Since these agents are present in the blood or produced in the blood wall, in addition, since PDGF plays the most important role in the process of atherosclerosis, we propose that these agents function in vivo as a systems of protection against atherosclerosis.