Interleukin-lβ Induces Migration of Rat Arterial Smooth Muscle Cells Through a Mechanism Involving Increased Matrix Metalloproteinase-2 Activity

Background. Interleukin-l beta (IL-l beta) is associated with vascular smooth muscle cell (VSMC) migration during neointimal formation following arterial injury, of which matrix metalloproteinase-2 (MMP-2) may have an important role. We investigated whether IL-l beta stimulated migration and MMP-2 production in VSMC, and, if so, whether migration correlated with MMP-2 activity. Materials and Methods. Modified Boyden chamber assay quantified cultured rat aorta VSMC migration. Methyl-thiazolyl-tetrazoliumassayassessed cell growth. Gelatin zymography and Western blotting determined MMP-2 activity and protein levels, respectively. Results. IL-l beta (0.1 - 10 ng/mL) induced migration of VSMC in a concentration-dependent manner without cell proliferation. VSMC released increasing levels of active MMP-2 in a dose-response fashion at IL-l beta 1-10 ng/mL (P < 0.05) while significantly increased levels of latent MMP-2 (pro-MMP-2) were attained more gradually (10 ng/mL, P < 0.05). There was a dose-dependent increase in the ratio of active MMP-2 to pro-MMP-2 in response to IL-l beta (1-10 ng/mL, P < 0.05), suggesting extracellular activation of pro-MMP-2. Protein levels on Western blot paralleled enzyme activity, with the synthesis of more active MMP-2 than pro-MMP-2 in response to IL-l beta. IL-l beta-stimulated VSMC migration was significantly attenuated by both the pan-selective MMP inhibitor GM6001 and cis-9-octadecenoyl-N-hydroxylamide, a MMP-2-selective inhibitor. Conclusions. IL-l beta increases MMP-2 activity in VSMC through increased protein synthesis and activation of pro-MMP-2. VSMC migration induced by IL-l beta requires active MMP-2. IL-l beta may play a role in arterial remodeling following injury. (C) 2011 Elsevier Inc. All rights reserved. Key Words: interleukin-l beta; matrix metalloproteinase-2; vascular smooth muscle cells; cell migration.