Carvedilol inhibits platelet-derived growth factor-induced extracellular matrix synthesis by inhibiting cellular reactive oxygen species and mitogen-activated protein kinase activation

Background: Vascular smooth muscle cell (VSMC) proliferation, migration, and extracellular matrix (ECM) synthesis are major pathologic features of chronic allograft vasculopathy. Carvedilol, an antihypertensive agent, might be an effective agent for preventing the development and progression of chronic, allograft vasculopathy, since it can inhibit VSMC proliferation and migration. The present study was designed to examine the effect of carvedilol on platelet-derived growth factor (PDGF)induced ECM synthesis in rat VSMCs. Furthermore, we evaluated whether carvedilol inhibits PDGF-induced cellular reactive oxygen species (ROS) and the activation of mitogen-activated protein kinase (MAPK). Methods: Primary cultured rat VSMCs were stimulated with PDGF-BB (10 ng/ml) in the presence or absence of carvedilol, and the effects of carvedilol were compared with those of ROS or MAPK inhibitors. Fibronectin secretion, proliferating cell nuclear antigen (PCNA) expression, and each MAPK activation were determined. by Western blot analysis, total collagen synthesis by [H-3]-proline incorporation, and cellular ROS by flow cytometry. Results: PDGF significantly increased PCNA expression, fibronectin secretion, total collagen synthesis, cellular ROS, and MAPK activation in rat VSMCs. Carvedilol at doses that inhibited PDGF-induced cell proliferation, inhibited ECM synthesis, cellular ROS, or subsequent MAPK activation. Structurally different anti-oxidants and extracellular signal-regulated protein kinase or p38 MAPK inhibitor effectively inhibited PDGF-induced fibronectin secretion and total collagen synthesis. Conclusions: These results suggest that carvedilol inhibits PDGF-induced VSMC proliferation and matrix protein synthesis by inhibiting cellular ROS and the subsequent activation of MAPK. Thus the targeted inhibition of cellular ROS and MAPK might provide an effective therapeutic strategy to treat chronic allograft vasculopathy.