Effect of Topical Retinoic Acids on the Levels of Collagen mRNA During the Repair of UVB-Induced Dermal Damage in the Hairless Mouse and the Possible Role of TGF-β as a Mediator

Topically applied retinoic acids have been found to enhance the gene expression for collagen types I and III in the skin of UVB irradiated hairless mice. Prior damage is required because the effect is not observed in the skin of age matched, non irradiated control animals. Immunochemical methods have shown an increase in TGF-β1, and to lesser extent, of TGF-β2 in the epidermis following retinoic acid treatment, There were no changes in mRNA levels for any of the isotypes of TGF-β induced by retinoic acid treatment. This study suggests that TGF-β may mediate the effect of retinoic acids on dermal repair through the stimulation of collagen gene expression.