Macrophage accumulation has been implicated in the pathogenesis of Inflammatory glomerular disease Monocyte chemoattractant protein-1 (MCP-1) plays a central role in recruiting monocytes to the glomeruli Tumor necrosis factor-alpha (TNF-alpha) has been shown to Induce MCP-1 expression in mesangial cells although the precise mechanisms remain unclear We previously demonstrated that RhoA and its effector Rho-kinase (Rho-associated coiled-coil containing protein kinase ROCK) are involved in the pathogenesis of diabetic nephropathy However its role in MCP-1 induction by TNF-alpha has not been elucidated In the present study we investigated whether the Rho/Rho-kinase signaling pathway regulates the TNF alpha-mediated induction of MCP-1 in mesangial cells Exposure of mouse mesangial cells (MES-13) to TNF-alpha resulted in an increase of MCP-1 expression (by RT-PCR) and secretion into the medium (by ELISA) Pull down and Western blot analysis revealed that TNF-alpha activated RhoA and Rho-kinase Based on these observations we speculated that the Rho/Rho-kinase signaling pathway may be involved in MCP-1 induction by TNF-alpha In agreement with this concept Y-27632 a specific Rho-kinase inhibitor attenuated TNF-alpha-mediated induction of MCP-1 We demonstrated that Y-27632 inhibited TNF-alpha-mediated monocyte migration and attenuated TNF-alpha-mediated p38 MAPK activation Based on these data we Infer that Y-27632 inhibits TNF-alpha-induced MCP-1 expression secretion and function through inhibition of Rho-kinase and p38 MAPK activity Our study suggests that Rho/Rho-kinase is an important therapeutic target of monocyte recruitment and accumulation within the glomerulus in inflammatory renal disease (C) 2010 Elsevier Inc All rights reserved