Monocyte chemotactic protein-1 (MCP-1)-directed transendothelial migration of monocytes plays a key role in the development of inflammatory diseases. Infiltration of tissues by monocytes requires degradation of extracellular matrices, a process that involves matrix metalloproteinases. We studied the effects of peroxisome proliferator-activated receptor (PPAR) gamma, alpha, and retinoid X receptor alpha (RXRalpha) ligands on MCP-1-directed migration and matrix metalloproteinase expression of a human acute monocytic leukemia cell line (THP-1). PPARgamma ligands attenuated MCP-1-induced migration, with 50% inhibition (IC(50)) at 2.8 microM for troglitazone and 4.8 microM for rosiglitazone. PPARalpha ligands WY-14643 (IC(50): 0.9 microM) and 5,8,11,14-eicosatetranoic acid (IC(50): 9.9 microM), and the potent RXRalpha ligand AGN 4204 (IC(50): 3.6 nM) also blocked monocyte migration. Troglitazone, rosiglitazone, or AGN 4204 inhibited phorbol 12-myristate 13-acetate (PMA)-induced matrix metalloproteinase-9 expression. PPARalpha activators WY-14643 and 5,8,11,14-eicosatetraynoic acid, however, had no inhibitory effect. AGN 4204 increased PMA-induced tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) expression, whereas all PPAR ligands showed no effect. All PPAR and RXRalpha ligands blocked chemotaxis of THP-1 monocytes in the absence of a matrix barrier. This study demonstrates that activated PPARs and RXRalpha, block MCP-1-directed monocyte migration, mediated, at least in part, through their effects on matrix metalloproteinase-9 or TIMP-1 production, or chemotaxis.