Abstract 511: Nitric Oxide Attenuates Matrix Metalloproteinase-9 Production by Endothelial Cells

Abstract

Impaired nitric oxide (NO) bioavailability and imbalanced matrix metalloproteinase (MMP) activity are key pathogenetic mechanisms involved in cardiovascular diseases. However, there is little evidence supporting a direct link between these mechanisms, although NO is known to interfere with nuclear factor kappa B (NFB) activity, an important modulator of MMP-9 expression. Moreover, it is not known whether the possible effects of NO on MMPs is dependent on cyclic GMP formation. Objective: We examined the effect of NO donors on MMP-9 production by endothelial cells, and if this effect is dependent on cGMP formation or NFB activation. Methods: Human umbilical vein endothelial cells were cultured in appropriate medium and treated for 24 hours with 10 nM phorbol myristate acetate (PMA; a MMP-9 inducer) and other drugs: NO donors (S-nitroso-N-acetylpenicillamine; SNAP, or DetaNONOate), 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; a soluble guanylyl cyclase inhibitor), BAY 11-7082 (a NFB inhibitor), or their vehicles. Conditioned media were analyzed by gelatin zimography. Results: PMA increased MMP-9 activity from 0.10±0.08 arbitrary units (AU) to 0.94±0.18 AU ( P< 0.05). Treatment with SNAP (200 or 320 μM) attenuated the increases in MMP-9 activity induced by PMA (0.52±0.16 AU or 0.25±0.10 AU, respectively; both P< 0.05 vs. PMA). DetaNONOate (320 or 400 μM) exerted similar inhibitory effects on MMP-9 activity (0.57±0.13 AU and 0.45±0.06 AU, respectively; both P< 0.05 vs. PMA). Conversely, treatment with ODQ (10 or 32 μM) had no effects on 200 μM SNAP-induced inhibition of PMA-stimulated MMP-9 activity (0.25±020 AU and 0.14±0.11 AU, respectively; both P< 0.05 vs. PMA). Nevertheless, 3.2 and 5 μM BAY 11-7082 decreased PMA-stimulated MMP-9 activity (0.54±0.07 AU and 0.27±0.09 AU, respectively; both P< 0.05 vs. PMA). Conclusion: Our results suggest that NO attenuates MMP-9 production by endothelial cells in a concentration-dependent manner. While this effect is independent of soluble guanylate cyclase activation, it apparently involves inhibition of NFB activity.