Hellemans Lieveke, Corstjens Hugo, Neven Ann, Declercq Lieve, Maes Daniel
Biological Research Department Europe, Estée Lauder Coordination Center, Oevel, Belgium.
J Invest Dermatol. 2003 Mar;120(3):434-9. doi: 10.1046/j.1523-1747.2003.12056.x.
The stratum corneum, as the body's principal barrier to the environment, is continuously exposed to environmental sources of reactive oxygen species like ultraviolet light, ozone, and pollution. Reactive oxygen species are believed to be involved in cancer, aging, and inflammatory skin disorders. We have developed a method to measure catalase and superoxide dismutase activity on tape strippings from the human stratum corneum and demonstrated a gradient of antioxidant enzyme activity across the stratum corneum with decreasing levels towards the skin surface. Sun exposure resulted in a seasonal variation of the catalase activity in stratum corneum, with low activities in summer and higher activities in winter for the same person, whereas superoxide dismutase activity in stratum corneum did not seem to vary in those conditions. Exposure of human skin to broadband ultraviolet-A resulted in a dose-dependent deactivation of the catalase activity in stratum corneum within 24 h, whereas exposure to ultraviolet-B had no effect. Superoxide dismutase activity in stratum corneum was not affected by ultraviolet-A or ultraviolet-B irradiation within 24 h. After exposure to a dose of 15 J per cm2 broadband ultraviolet-A, full recovery of the catalase activity occurred in 3-4 wk at an age-dependent rate. We conclude that sun exposure results in a disturbed catalase to superoxide dismutase ratio in the stratum corneum. This may lead to an increased vulnerability to oxidative damage in stratum corneum barrier components. These results therefore stress the importance of providing efficient protection for this internal defense mechanism in sun-exposed areas of the skin.
角质层作为人体与外界环境的主要屏障，持续暴露于紫外线、臭氧和污染等环境性活性氧来源中。活性氧被认为与癌症、衰老及炎症性皮肤病有关。我们已开发出一种方法来测量人角质层胶带剥离样本中的过氧化氢酶和超氧化物歧化酶活性，并证明了整个角质层中抗氧化酶活性呈梯度变化，朝着皮肤表面活性水平逐渐降低。阳光照射导致角质层中过氧化氢酶活性出现季节性变化，同一个人在夏季活性较低，冬季活性较高，而角质层中的超氧化物歧化酶活性在这些条件下似乎没有变化。人体皮肤暴露于宽带紫外线A下，24小时内角质层中的过氧化氢酶活性会出现剂量依赖性失活，而暴露于紫外线B则没有影响。24小时内，角质层中的超氧化物歧化酶活性不受紫外线A或紫外线B照射的影响。暴露于每平方厘米15焦耳的宽带紫外线A剂量后，过氧化氢酶活性会以年龄依赖性速率在3至4周内完全恢复。我们得出结论，阳光照射会导致角质层中过氧化氢酶与超氧化物歧化酶的比例失调。这可能会导致角质层屏障成分更容易受到氧化损伤。因此，这些结果强调了对皮肤暴露于阳光下区域的这种内部防御机制提供有效保护的重要性。
