Abstract: Objective To analyze quantitatively the alteration of matrix metalloproteinases-1, -8(MMP-1, MMP-8), tissue inhibitor of metalloproteinase-1(TIMP-1) after radiation with intense pulsed light(IPL) technique in clinic. And to partly explain the treatment mechanism of IPL on sun-damaged human skin and provide a theoretical basis of mechanism, course of therapy and interval time for treatment of IPL on photo aging skin. Methods Volunteers older than 20-years of age whose skin type is Fitzpatrick Ⅲ~Ⅳ were selected. One site of each volunteer was radiated respectively with IPL system at different parameters. Skin specimens were taken at both non-treated and treated locations on days 14 and 21 after IPL irradiation of about the size of 5 mm×5 mm×5 mm. All skin specimens were fixed in formaldehyde fixative buffer. Immunohistochemical staining was performed on each specimen, including observations on changes of MMP-1, MMP-8, TIMP-1 proteins expression after IPL irradiation in order to know their action in dermis remodeling. Results The expressions of MMP-1, MMP-8 and TIMP-1 were detected after treatments. To weeks 2 after treatment. The expressions of MMP-1, MMP-8 became weaker at weeks 3. Expression of TIMP-1 was not significantly different between weeks 2 and 3. There were no expressions in normal skin. Conclusion IPL irradiation could promote the expression of MMP-1, MMP-8 and TIMP-1 in human skin directly.

Key words: intense pulsed light, matrix metalloproteinase-1, matrix metalloproteinase-8, tissue inhibitor of metalloproteinase-1