Ultraviolet Damage: which layer do the Cytotoxic molecules come from ?

• Ultraviolet damage mostly comes from the generation of Reactive Oxygen Species (ROS)

• The enzymes responsible for the synthesis of ROS (oxygen singulets, O2. and 1O2) are Superoxide Dismutase (SOD) and Catalase. They are present in higher quantities in in the Stratum Corneum (SC) than in the lower epidermis and dermis
• Carbonylated Proteins (CP) are the result of aldehyde fragments from peroxides reacting with amino acid residues of SOD

• In this study:
  • increased CP levels are observed after Ultraviolet type A irradiation (UVA)(and acrolein treatment)
  • When stripping the irradiated SC and transferring it to glass slides, high levels of oxygen singulets are were found (Method used: measurement of increased chemiluminescence intensity of MCLA to detect O2. and 1O2)

• Comments
  • The study is done in vitro from mice skin as well as in human volunteers
  • However the results suggest that ROS are mostly generated in the stratum corneum of the skin. This is the most superficial layer and the one which might most benefit from sunscreen topical application

Contributors

Dr Christophe Hsu – dermatologist. Geneva, Switzerland

Source of information: p12-06 Mizutani T et al.. ROS generation from the stratum corneum under UV irradiation. JSID Annual Meeting (Japanese Society of Investigative Dermatology, 日本研究皮膚科学会) 2014 – Osaka, Japan