The effects of epigallocatechin-3-gallate on extracellular matrix metabolism

Background: Anti-oxidants have attracted a Lot of interest on account of their function to protect the skin from oxidative stress by ultraviolet (UV) radiation. Objective: This study examined the effects of epigallocatechin-3-gallate (EGCG), which is a green tea extract, on the extracellular matrix (ECM) changes induced by UV radiation and showed the comparative results with retinoic acid (RA). Methods: The ECM metabolism is tightly controlled by the collagen degrading matrix metalltoprotienases (MMPs) and their tissue inhibitors (TIMPs). Therefore, the expression of MMPs and TIMP-1 was investigated to evaluate the effects of EGCG and RA. Artificial skin was made using three-dimensionally cultured keratinocytes on a collagen matrix populated with fibroblasts. EGCG and RA were added into the medium of the fibroblasts and keratinocytes culture and also applied topically on artificial skins prior to UVA irradiation. The MMPs and TIMP-1 expression levels were measured using Western blot and a zymogram. Results: EGCG, like RA, decreased the level of MMPs production and increased TIMP-1 expression level. However, EGCG suppressed the activities of the gelatinases and augmented the expressions of the TIMP-1 more than RA did. RA decreased the MMP-1 and MMP-3 expression levels to a greater extent than EGCG. ECM alterations as a result of UVA appeared to be prevented more effectively using the EGCG treatment. Conclusion: EGCG can reverse the ECM degradation induced by IJV even with a topical application of a practical-use concentration. In particular, EGCG proved to be much more effective in ROS-related conditions, such as UVA exposure. (c) 2005 Japanese Society for Investigative Dermatology.