DERMO-EPIDERMAL STIMULATION ELICITED BY A BETA-LIPOHYDROXYACID - A COMPARISON WITH SALICYLIC-ACID AND ALL-TRANS-RETINOIC ACID

Although ageing has been thought to be irreversible, studies made duri ng the last decade have shown that a few topical compounds may limit o r improve the age-related skin damages. The efficacy of tretinoin (all -trans-retinoic acid) in treating photoageing is well established. Ide ntifying other compounds with similar effect and improved tolerance wo uld be greatly valued. In this double-blind study, a new beta-lipohydr oxyacid compound was evaluated. To address a comparison between produc ts, 6 volunteers completed a 4-week study using twice daily 0.025% tre tinoin, 5% salicylic acid, 1.5% beta-lipohydroxyacid or vehicle. Immun ohistochemistry and computerized image analysis were performed on skin sections from biopsies taken after treatment. We searched for changes in epidermal renewal (Ki-67 labeling), modifications in cytokeratin ( 56-65 kD) and filaggrin patterns, and in tumor necrosis factor alpha ( TNF-alpha), Ulex europaeus and factor XIIIa expressivity. The vehicle- and salicylic-acid-treated areas had an aspect similar to untreated c ontrol sites. Both beta-lipohydroxyacid and tretinoin induced enhanced epidermal proliferation and thickness with activation of factor XIIIa +dendrocytes. The effects were more pronounced at the tretinoin-treate d site. We speculate that TNF-alpha might mediate some of the dermal e ffects. The beta-lipohydroxyacid mimics some of the stimulatory effect s of tretinoin on the epidermis and dermis. This new compound should b e listed among topical products boosting the skin tissues affected by ageing.