IPL irradiation rejuvenates skin collagen via the bidirectional regulation of MMP-1 and TGF-β1 mediated by MAPKs in fibroblasts

The efficacy of intense pulsed light (IPL) in remodeling the extracellular matrix of aged skin had been proven by an increasing number of clinical trials. However, because of the lack of research about the underlying molecular and signaling mechanisms, its efficiency had not been accepted universally. A potential mechanism of IPL rejuvenation effects is due to its different effects on diverse cytokines, the impact of IPL on them may determine the phenotype and prognosis of the aged skin. We designed this study to evaluate the impact of IPL on the secretion of matrix metalloproteinase-1 (MMP-1), transforming growth factor-β1 (TGF-β1), and the mitogen-activated protein kinase (MAPK) signaling pathway in human skin fibroblasts, and tried to study the respective functions of MAPKs as mediators of the MMP-1, TGF-β1 secretion. Results showed that the MMP-1 secretion was only enhanced by IPL at 10 J/cm 2 ; while the TGF-β1 secretion was inhibited by IPL when the fluence was below 36 J/cm 2 , but enhanced at 72 J/cm 2 . Meanwhile, ERK inhibitor PD98059 decreased MMP-1 secretion, but did not show a significant influence on TGF-β1; JNK inhibitor SP600125 increased the secretion of MMP-1 and decreased the TGF-β1 secretion; P38 inhibitor SB203580 had no significant influence on MMP-1 but increased the secretion of TGF-β1. Our findings indicated that the bidirectional influence of IPL on the secretion of MMP-1 and TGF-β1 is a potential mechanism of its skin rejuvenation effect; and the secretion of these two cytokines can be mediated by MAPKs.