title: UV-irradiation depletes antioxidants and causes oxidative damage in a model of human skin.
abstract: The degree to which antioxidant loss occurs in human skin after UV irradiation is unknown, as is the cascade of events that might occur. We have, therefore, evaluated a tissue culture model of human skin for its usefulness for studying oxidative injury by UV-irradiation. Human skin equivalents, a tissue culture model, were irradiated using a full solar UV spectrum (UVA and UVB, 280-400 nm) (0 to 16.8 J/cm2, 0-12 minimal erythemal dose, MED), then incubated from 1 to 24 h. Ubiquinol was the most UV-light sensitive antioxidant and was depleted by 2.1 J/cm2 (1.5 MED, p < .004); ubiquinone decreased with 4.2 J/cm2 (3 MED, p < .0007). A linear decrease in alpha-tocopherol occurred--approximately 1.7 pmol tocopherol/cm2 surface were destroyed per J/cm2 UV-light. Urate was depleted by irradiation with 8.4 J/cm2 (6 MED), while ascorbate was depleted by 16.8 J/cm2 (12 MED). Cellular protein carbonyls and lactic dehydrogenase (LDH) leakage into the medium were only increased at 1 h incubation following exposure to 16.8 J/cm2 (12 MED). At 24 h incubation, PGE2 was increased in the medium of cells exposed to UV-irradiation at 0.35 J/cm2 (0.25 MED) compared with sham-exposed cells (p < .04); higher UV exposures lead to significant increases in both PGE2 (p < .001) and LDH (p < .001) in the medium. In conclusion, human skin equivalents respond to suberythemal levels of UV-irradiation by increasing production of PGE2; higher levels of UV-irradiation (at least 1 MED) were needed to deplete cellular antioxidants and induce immediately detectable oxidative damage.
authors.affiliation: University of California Berkeley, Department of Molecular and Cell Biology, 94720-3200, USA.
authors.forename: M
authors.initials: M
authors.lastname: Podda
authors.forename: M G
authors.initials: MG
authors.lastname: Traber
authors.forename: C
authors.initials: C
authors.lastname: Weber
authors.forename: L J
authors.initials: LJ
authors.lastname: Yan
authors.forename: L
authors.initials: L
authors.lastname: Packer
mesh_terms: D000704:Analysis of Variance; D000975:Antioxidants / Q000378:metabolism*; D046508:Culture Techniques; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008954:Models, Biological; D018384:Oxidative Stress / Q000528:radiation effects*; D012867:Skin / Q000378:metabolism / Q000528:radiation effects*; D012995:Solubility; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
chemical_list: D000975:Antioxidants; D008055:Lipids; D014867:Water