Applegate L A, Frenk E
Department of Dermatology, University Hospital, Lausanne, Switzerland.
Photodermatol Photoimmunol Photomed. 1995 Jun;11(3):95-101. doi: 10.1111/j.1600-0781.1995.tb00146.x.
Skin fibroblasts and keratinocytes cultivated from chronically light-exposed skin sites have higher levels of the protective protein ferritin than cells derived from unexposed areas of the body, suggesting an adaptive response of cells exposed to chronic external insults. In the same line, ferritin levels were always found to be 2- to 7-fold higher in epidermal keratinocytes than in the underlying dermal fibroblasts of the same person thus providing the keratinocyte with continuous protection by the higher cellular ferritin content. The activation of ferritin by oxidative stress including UVA radiation could represent an important cellular defense mechanism that operates in human skin. Following low fluences of UVA radiation (2-4 x 10(5) J/m2), ferritin levels increased by 20-30% in normal adult skin fibroblasts and showed a subsequent decrease at higher UVA fluences. In contrast, skin keratinocytes were not perturbed by UVA radiation exposure except for very high fluences (1.25 x 10(6) J/m2) where slight decreases in cellular ferritin were noted in 7 of the 12 cell lines. Fibroblasts derived from light-exposed skin sites that possessed higher levels of cellular ferritin were highly protected against UVA-induced membrane damage as measured by lactate dehydrogenase release compared with fibroblasts from nonexposed body sites with lower levels of ferritin. It is clear from our results that ferritin plays an important role in protection at the cellular level in human skin cells, but the role of this putative protective protein in vivo remains to be defined.
从长期暴露于光照的皮肤部位培养的皮肤成纤维细胞和角质形成细胞，其保护性蛋白铁蛋白的水平高于从身体未暴露部位获取的细胞，这表明暴露于慢性外部损伤的细胞会产生适应性反应。同样，人们发现，在同一个人的表皮角质形成细胞中，铁蛋白水平总是比其下方的真皮成纤维细胞高2至7倍，因此较高的细胞铁蛋白含量为角质形成细胞提供了持续保护。包括紫外线A辐射在内的氧化应激对铁蛋白的激活，可能是人类皮肤中起作用的一种重要细胞防御机制。在低剂量紫外线A辐射（2 - 4×10⁵ J/m²）后，正常成人皮肤成纤维细胞中的铁蛋白水平增加了20 - 30%，在较高的紫外线A剂量下随后下降。相比之下，皮肤角质形成细胞不受紫外线A辐射暴露的影响，除非剂量非常高（1.25×10⁶ J/m²），在12个细胞系中有7个细胞系的细胞铁蛋白出现轻微下降。与来自身体未暴露部位、铁蛋白水平较低的成纤维细胞相比，从具有较高细胞铁蛋白水平的光照暴露皮肤部位获取的成纤维细胞，对紫外线A诱导的膜损伤具有高度保护作用，这通过乳酸脱氢酶释放来衡量。从我们的结果可以清楚地看出，铁蛋白在人类皮肤细胞的细胞水平保护中起重要作用，但这种假定的保护蛋白在体内的作用仍有待确定。
