Protein carbonyls damage the water-holding capacity of the stratum corneum

Background: Acrolein is a degradation product of lipid peroxide as well as a well-known environmental pollutant. As a hallmark of oxidatively damaged protein, protein carbonyl, including acrolein-protein adduct, has been observed in the skin. However, the influence of protein carbonylation on the stratum corneum (SC) has not yet been clarified. Objectives: We explored the influence of oxidative protein modification, focusing on the major function of the SC, the water-holding capacity, by introducing experimental protein carbonylation. Methods: The level of carbonyls in the SC was evaluated by reaction with a labeled hydrazide. The water-holding capacities of the SC or keratin gels were evaluated by measurement of the surface conductance. The bound water (nonfreezing water) content in the SC was measured by the heat of fusion of frozen SC. Results: Acrolein caused protein carbonylation, decreased the water-holding capacity and the bound water of the porcine SC in vitro. The water-holding capacity of the keratin gels prepared from human SC was also decreased by acrolein in vitro. Water content in the human SC in vivo was decreased by sodium hypochlorite and accompanied by the increase in carbonyls. Conclusion: Exposure of SC to the oxidative environment damages the waterholding capacity of the SC through the modification of protein-water interaction. Copyright (C) 2008 S. Karger AG, Basel.