Dual Regulation of Tumor Necrosis Factor-alpha-lnduced CCL2/ Monocyte Chemoattractant Protein-1 Expression in Vascular Smooth Muscle Cells by Nuclear Factor-kappaB and Activator Protein-1:Modulation by Type III Phosphodiesterase Inhibition

摘要

Monocyte/macrophage infiltration to the subendothelial space of arterial wall is a critical initial step in atherogenesis,in which CC chemokine ligand 2 (CCL2)/monocyte Chemoattractant protein-1 (MCP-1) is thought to play a key role.This study investigated the effectiveness of phosphodiesterase inhibitors,including the nonselective pentoxifylline (PTX) and the selective type III (cilos-tamide) and type IV (denbufylline) inhibitors,on cytokine-in-duced CCL2/MCP-1 production in cultured rat vascular smooth muscle cells (VSMCs),and the signal transduction mechanisms whereby they act.Our results showed that tumor necrosis factor (TNF)-alpha induced a marked increase in CCL2/MCP-1 production in dose- and time-dependent manners.2-(2-Amino-3-methoxy-phenyl)-4H-1-benzopyran-4-one (PD98059),1,4-diamino-2,3-di-cyano-1,4-bis(2-aminophenylthio) butadiene (U0126) [both inhibitors of p42/44 mitogen-activated protein kinase (MAPK) kinase],and anthra[1hyphen]9-cd]pyrazol-6(2H)-one (SP600125) [an inhibitor of c-Jun NH_2-terminal kinases (JNKs)] attenuated TNF-alpha-induced CCL2/MCP-1 production,without affecting l-kappaBalpha degradation or p65uclear factor-kappaB (NF-kappaB) nuclear translocation.PD98059 abolished TNF-alpha-activated p42/44 MAPK phosphory-lation and c-Fos up-regulation,whereas SP600125 inhibited TNF-alpha-activated JNK and c-Jun phosphorylation.The NF-kappaB inhibitor carbobenzoxy-L-leucyl-L-leucyl-L-leucinal (MG132) attenuated TNF-alpha-induced CCL2/MCP-1 production in the presence of increased phospho-JNK and phospho-c-Jun levels.When SP600125 was added simultaneously,MG132 completely inhibited TNF-alpha-induced CCL2/MCP-1 production.Finally,the pre-treatment of VSMCs with PTX or cilostamide,but not denbufylline,reduced TNF-alpha-induced CCL2/MCP-1 production,which was preceded by attenuation of p65/NF-kappaB nuclear translocation,p42/44 MAPK,and JNK-c-Jun phosphorylation,and c-Fos up-regulation.These data indicate that TNF-alpha-stimulated CCL2/ MCP-1 production in rat VSMCs is dually regulated by activator protein-1 (AP-1) and NF-kappaB pathways,and inhibition of type III phosphodiesterase contributes substantially to the suppressive effect of PTX on CCL2/MCP-1 production via down-regulation of AP-1 and NF-kappaB signals.