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 during the last decade have shown that a few topical compounds may limit or improve the age-related skin damages. The efficacy of tretinoin (all-trans-retinoic acid) in treating photoageing is well established. Identifying other compounds with similar effect and improved tolerance would be greatly valued. In this double-blind study, a new beta-lipohydroxyacid compound was evaluated. To address a comparison between products, 6 volunteers completed a 4-week study using twice daily 0.025% tretinoin, 5% salicylic acid, 1.5% beta-lipohydroxyacid or vehicle. Immunohistochemistry 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 expressively. The vehicle- and salicylic-acid-treated areas had an aspect similar to untreated control 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-treated site. We speculate that TNF-alpha might mediate some of the dermal effects. The beta-lipohydroxyacid mimics some of the stimulatory effects of tretinoin on the epidermis and dermis. This new compound should be listed among topical products boosting the skin tissues affected by ageing.