慢性紫外线损伤小鼠模型皮肤角质形成细胞中CK5和CK14表达研究

Expression of CK5 and CK14 on epidermal keratinocytes of chronic UV-damaged mice

目的:观察慢性紫外线(utraviolet,UV)损伤对小鼠角质形成细胞CK5和CK14表达的调控效应。方法:采用模拟日光UV(UVA+UVB)光源对实验小鼠进行照射,照射从最小红斑量(MED,UVB0.07.J/cm^2,UVA0.7 J/cm^2),每周增加0.5个MED,每日1次,每周照射5 d,共9周,UVB总剂量达9.45 J/cm^2,UVA总剂量达94.5.J/cm^2,通过组织学观察、特殊化学染色和表皮厚度测量确定皮肤损伤,应用免疫组化法分别对照射前后(W0和W9)CK5和CK14的表达进行检测。应用Wilcoxon符号秩和检验和Spear-man秩相关系数进行统计分析。结果:对照组小鼠实验前、后CK5和CK14表达差异均无统计学意义(P>0.05)。损伤组小鼠实验前CK5和CK14的表达差异均有统计学意义(P<0.05),并且损伤组小鼠的CK5和CK14表达呈现明显的定位改变,在增厚的表皮中呈现弥漫的表达,失去在正常表皮中表达于基底细胞层的定位特点。损伤组小鼠表皮角质形成细胞内的CK5和CK14表达均显著上调,且二者的表达呈现正相关性(r=0.840,P<0.05)。结论:重复UV暴露导致小鼠角质形成细胞中CK5和CK14表达上调和定位异常。以上述两种角蛋白为标志物的基底层细胞过度增殖可能参与了慢性UV皮肤损伤出现表皮增厚的发生。

Objective： To investigate the expression of CK5 and CK14 on keratinocytes of mice skin exposed to chronic ul- traviolet irradiation. Methods： We have constituted the model of chronic UV-damaged mice, which were irradiated with UVA plus UVB by using simulated solar light. The irradiation began from the MED （UVB 0.07 J/cm2, UVA 0.7 J/cm2）, and in- creased 0.5 MED per week. The protocol was 1 irradiation per day and 5 irradiation per week for 9 weeks, the total doses of UVB and UVA were 9.45 J/cm2 and 94.5 J/cm2 respectively. The expression of CK5 and CK14 on epidermal keratinocytes of two groups was studied with immunohistochemistry before and after the end of irradiation（W0 $~I W9）. Wilcoxon signed ranks text and Spearman rank correlation coefficient were performed for statistics. Results： The average expression level of CK5 and CK 14 in the control group was of no statistical significance （P〉 0.05）. The average expression levels of CK5 and CK14 in chronic UV-damaged mice had statistical significance （P〈0.05）. There were diffuse expression of CK5 and CK14 in the thick- ened epidermis of the mice of UV-damaged group, while the expression of CK5 and CK14 in the control group was confined to the basal layer. The expression levels of CK5 and CK14 were upregulated significantly in the keratinocytes of the UV- damaged group, and the upregulation of the two proteins showed positive correlation （r = 0.840, P〈 0.05）. Conclusions： Our study indicates that chronic UV irradiation induces upregulation and abnormal localization of expression of CK5 and CKI4 in the keratinocytes of the mice. The over-proliferation of basal ceils, upregulation of CK5 and CK14 may be involved in the epidermal thickening caused by the chronic UV exposure.