No abstract

Sunlight induces actinic keratosis, skin cancers and photoaging. Photoprotection is thus a major issue in public health to prevent the harmful effects of solar ultraviolet (UV) radiations. Recent data have shown that the visible (VIS) and infrared (IR) radiations can lead to skin damage by oxidative stress, suggesting that a balanced protection across the entire spectrum of sunlight is necessary to prevent cutaneous alterations. In this context, we developed a new generation of sunfilter called Phenylene Bis-Diphenyltriazine or TriAsorB (CAS N°55514-22-2). The aim of the present study was to assess the photoprotective efficacy of TriAsorB from UV to IR light. Spectrophotometric assays were performed to measure absorption and reflectance of TriAsorB in the different spectral ranges of sunlight: UV, VIS including blue light or high energy visible (HEV) and IR. DNA damage was evaluated using reconstructed human epidermis (RHE): 8-hydroxy-2′-deoxyguanosine (8OHdG) in response to HEV exposure, pyrimidine dimers (CPDs) and (6-4) photoproducts following solar-simulated radiation (SSR). TriAsorB is a broad spectrum UVB + UVA filter including long UVA. Interestingly, it also absorbs VIS radiations, especially in the HEV region. These radiations are also reflected. Protection in the IR spectral range is weak. Furthermore, the sunfilter specifically protects the skin against the oxidative lesions 8OHdG induced by HEV and prevents SSR-induced DNA damage. Thus, TriAsorB is an innovative sunfilter that might be used in sun care products for skin photoprotection from UV to VIS radiations. Finally, it prevents sunlight genotoxicity and protected the skin against solar radiations, especially blue light.

No abstract

Human skin provides protection from the environment and facilitates flexibility by the reversible deformation of its structure. In this study, we used cutometry to characterise the consequences of chronological (intrinsic) skin ageing and chronic sun exposure on the biomechanical properties of skin from young (n¼21; 18-30 years) and old (n¼18; >65 years) black African-American subjects. We then related these findings to underlying skin histological architecture. We found that skin from buttock and forearm of young African-American subjects has similar biomechanical properties: resilience (capable of returning to its original position following deformation); exhibits minimal fatigue; and is highly elastic. Histologically, skin from young individuals exhibits strong interdigitation of rete ridges and an abundance of candelabra-like arrays of elastic fibres (immuno-positive for fibrillin-rich microfibrils [FRM] and elastin). Intrinsically aged skin is significantly less resilient (P<0.01) and less elastic (P<0.001) than young skin and is characterised by modest effacement of rete ridges (P<0.05) and reduced deposition of FRM (P<0.001). In chronically sun-exposed forearm, significant impairment of all biomechanical properties (P<0.001) with flattening of rete ridges (P<0.001) and depletion of elastic fibres (both FRM (P<0.001) and elastin (P<0.001)) was apparent. This study identifies that disruption to the highly organised elastic fibre network and effacement of rete ridge structure in aged black African-American forearm and buttock coincides with a marked decline in biomechanical function. We conclude that in skin of colour, despite the photoprotective properties of melanin, chronic sun-exposure exacerbates skin ageing at both the histological and functional level. 640 Keap1 knockdown in melanocytes induces cell proliferation and survival via HO-1-associated b-catenin signaling