Niggli H J, Applegate L A
BioFoton AG, Institut für ganzheitliche Photobiologie, Ependes, Switzerland.
Photochem Photobiol. 1997 Apr;65(4):680-4. doi: 10.1111/j.1751-1097.1997.tb01911.x.
Since Hayflick's pioneering work in the early sixties, human diploid fibroblasts have become a widely accepted in vitro model system. Recently, Bayreuther and co-workers extended this experimental approach showing that fibroblasts in culture resemble, in their design, the hemopoietic stem-cell differentiation system. They found that the chemical agent mitomycin C accelerates the differentiation pathway from mitotic to postmitotic fibroblasts. We measured the response of endogenous glutathione levels after UVA irradiation (320-400 nm) in mitotic and mitomycin C-induced postmitotic human skin fibroblasts and foreskin-derived keratinocytes. The initial levels in mitotic foreskin derived human fibroblasts were 14.4 nmol glutathione per mg protein, whereas a 30% higher value was obtained in matching foreskin-derived keratinocytes. Similar elevated levels of this important intracellular free radical scavenging system were found in fibroblasts of a donor suffering from xeroderma pigmentosum. Furthermore, three to four times higher levels of glutathione in mitomycin C-treated mitotic fibroblasts have been determined. In mitotic skin fibroblasts, UVA irradiation resulted in a depletion of glutathione up to 90% following a fluence of 1.0 MJ/m2 UVA radiation. Higher initial glutathione levels were found in keratinocytes and mitomycin C-treated skin fibroblasts. In these fibroblasts a 70% depletion was detected and a much lower depletion (10-20%) was seen in some keratinocyte cell lines following fluences up to 1.0 MJ/m2. The depletion in skin fibroblasts was retained after 24 h following a fluence of 0.75 MJ/m2 UVA light. In view of the fact that glutathione has been shown to be involved in a variety of metabolic processes and plays a role in cellular protection against UVA radiation, our results imply that the fibroblast differentiation system is a very useful tool to unravel the complex mechanism of UVA-induced oxidative stress.
自20世纪60年代初海弗利克的开创性工作以来，人二倍体成纤维细胞已成为一种被广泛接受的体外模型系统。最近，拜罗伊特及其同事扩展了这一实验方法，表明培养中的成纤维细胞在设计上类似于造血干细胞分化系统。他们发现化学试剂丝裂霉素C加速了从有丝分裂型成纤维细胞到有丝分裂后型成纤维细胞的分化途径。我们测量了有丝分裂型和丝裂霉素C诱导的有丝分裂后型人皮肤成纤维细胞以及包皮来源的角质形成细胞在紫外线A（UVA，320 - 400纳米）照射后的内源性谷胱甘肽水平反应。包皮来源的有丝分裂型人成纤维细胞的初始水平为每毫克蛋白质含14.4纳摩尔谷胱甘肽，而在匹配的包皮来源的角质形成细胞中获得的值高30%。在患有色素性干皮病的供体的成纤维细胞中也发现了这种重要的细胞内自由基清除系统的类似升高水平。此外，已确定丝裂霉素C处理的有丝分裂型成纤维细胞中的谷胱甘肽水平高出三到四倍。在有丝分裂型皮肤成纤维细胞中，UVA照射在1.0兆焦/平方米UVA辐射通量后导致谷胱甘肽消耗高达90%。角质形成细胞和丝裂霉素C处理的皮肤成纤维细胞中发现了更高的初始谷胱甘肽水平。在这些成纤维细胞中检测到70%的消耗，而在一些角质形成细胞系中，在高达1.0兆焦/平方米的通量后观察到的消耗要低得多（10 - 20%）。在0.75兆焦/平方米UVA光通量后24小时，皮肤成纤维细胞中的消耗仍然存在。鉴于谷胱甘肽已被证明参与多种代谢过程并在细胞对UVA辐射的保护中起作用，我们的结果表明成纤维细胞分化系统是揭示UVA诱导的氧化应激复杂机制的非常有用的工具。
