(The) effect of α-Lipoic acid on the MMP-1 and MMP-9 activity induced by UVB irradiation

Abstract

UVB induces the matrix metalloproteinase (MMP) collagenase, 92-kD gelatinase, and stromelysin, which degrade skin connective tissue and may contribute to premature skin aging (photoageing). α-Lipoic acid (LA) is well known as a potent antioxidant. Due largely to its antioxidant properties, LA has recently been reported to afford protection against oxidative injury. Zymography and Western blot experiments displayed that MMP-1 and MMP-9 protein were increased significantly in UVB irradiated HaCaT cells. However, LA had effects on expressions and activities of MMP-1 and MMP-9 induced by UVB and also attenuated UVB irradiation-induced oxidative stress. We investigated upstream signal transduction pathways of MMPs induction by UVB irradiation. LA inhibited activation of the mitogen-activated protein (MAP) kinases, extracellular signal-regulated kinase (ERK), c-JUN amino-terminal kinase (JNK) and transcription factor AP-1 (cFOS/cJUN) . Our study demonstrates that LA significantly blocks the up-regulation of MMP-1 and MMP-9 by UVB irradiation through the change in redox system.