COUNTERACTING AGING PHENOMENA BY NEW PURE TETRAPEPTIDES WITH TARGETED EFFICACY

Summary In the skin, proteoglycans are present both in the epidermjs and the dermis. In the latter layer, a group of small proteoglycans ( < 60 kDa) plays an important role in fibrillogenesis, growth factors modula­ tion and derma! homeostasis. The epidermis also synthesizes severa! small proteoglycans, in volved in keratinocyte functionality. The knowledge about the alteration of the synthesis and the structure of such small proteoglycans during skin aging used to be rather lirillted in the past. In fundamental studies, Laboratoires Serobiologiques could recentl y identify two small proteoglycans whose influence in skin proper fun­ ctioning is significant, and whose synthesis decreases with agi ng. Lumican is located in the dermjs, where it is in vo lved in the formation of the coll agen fibers and consequently in the skin firmness and thickness. Syndecan-l occurs preferentially in the supra-basai layers of the epidermis; it is jointly implicated in the epidermal cohesion. The dermo-epidermal junction assures the connection between dermis and epiderrills. With certain anchor molecules like collagen XVII, hemidesmosomes attach the basai cell s to the basai membra­ ne. The stimulation of the synthesis of lumican in derma! cell s, of syndecan- l in epidermal cells and of collagen XVII in the basai layer counteracts the aging process on three different levels in the skin . In order to identify ingredients with a corresponding activity, skin specific DNA-arrays were used, allo­ wing to selectively analyze the expression of genes highly implicated in the skin physiology. Two efficient acetylated tetrapeptides (respectively AcTPl and AcTP2) were selected. The efficacy of both peptides was further demonstrated on celi cultures, skin models and finally in clinica] studies.