1289 Topical retinoids induce fibrillin-rich microfibril deposition in photoaged skin of color

Photoaging describes complex cutaneous changes that occur over time due to chronic exposure to solar radiation. The clinical ‘gold standard’ for the treatment of photoaged white skin is all-trans retinoic acid (ATRA); however, cosmetic retinol (ROL) has also proven efficacious. Our recent work has identified that black skin is also susceptible to photodamage; in particular, disintegration of fibrillin-rich microfibrils (FRMs) at the dermal-epidermal junction (DEJ). However, the histologic impact of topical retinoids on black skin has not been well investigated. Here we assessed the potential of topical ATRA and ROL to remodel photodamaged dermis of chronically sun-exposed black volunteers. Using the Manchester Patch-Test Assay, extensor forearms of healthy but photodamaged black volunteers (> 45 years) were occluded with either 0.025% ATRA (n = 6; 4-day application due to irritancy) or ROL (12-day treatment protocol for a cosmetic) at concentrations of 0.3% (n = 6) or 1% (n = 6). Resultant punch biopsies were processed for histologic analyses. Treatment with ATRA and both concentrations of ROL produced significant acanthosis (all P < 0.001) accompanied by a significant increase in keratinocyte proliferation (Ki67; all P < 0.01) as compared to occluded baseline control. Furthermore, significant restoration of the FRMs at the DEJ was apparent following treatment with ATRA (P < 0.01) and both concentrations of ROL (P < 0.01). This study confirms that topical ATRA has utility for the repair of photodamaged black skin and that ROL induces comparable effects on epidermal characteristics and dermal remodeling, albeit over a longer timeframe than ATRA; further investigation of their efficacy in daily use is therefore warranted.