Skin Cellular Retinoid-Binding Proteins and Retinoid-Responsive Dermatoses

Abstract
We have previously found an important increase of cellular retinoic acid-binding protein (CRABP) in psoriatic plaques whereas the cellular retinol-binding protein (CRBP) was not elevated compared to normal human skin and nonlesional psoriatic skin. In the present study we analyzed CRABP and CRBP levels in a panel of dermatoses in order to address several questions raised by the above findings. Three observations were made: (1) CRBP showed little or no variations whereas CRABP was either normal (seborrheic keratosis, lichenification, nonlesional psoriatic and nonlesional Darier disease skin) or elevated (psoriatic plaques, lamellar ichthyosis, lesional Darier disease, pityriasis rubra pilaris, keratosis pilaris); (2) high levels of CRABP might indicate a greater sensitivity of the lesions to systemic synthetic retinoids with a carboxyl group in the C15 position, and (3) systemic administration of etretin increased the levels of CRABP but not CRBP. These observations suggest that CRABP might be the receptor for synthetic retinoids in the skin and that its analysis might be useful in monitoring retinoid therapy.