P53,Bax,Bcl-2蛋白表达及细胞凋亡在急性放射性皮肤溃疡发生发展过程中的作用探讨

The role of P53, Bax, Bcl-2 expression and cell apoptosis in the formation and development of acute radiation-induced skin ulcers

目的 :研究细胞凋亡及一些凋亡相关基因 (p53,bcl 2 ,bax)的表达在急性放射性皮肤溃疡发生发展过程中的作用。方法 :采用Wistar大鼠以6 0 Coγ射线进行局部照射 ,建立急性放射性皮肤溃疡动物模型 ,观察病变 4 0d ,然后采用免疫组化方法检测皮肤溃疡组织中P53,Bcl 2 ,Bax蛋白表达 ,并采用原位末端标记法 (TUNEL)检测细胞凋亡。结果 :照后 14d照射野内开始出现皮肤溃疡 ,之后逐渐扩大、融合、加深 ;照后 11～ 4 0d ,P53蛋白表达明显增强 ,主要定位于血管内皮细胞和小血管平滑肌中 ;照后 14～ 2 1d为Bax蛋白表达高峰 ,之后逐渐减弱 ,主要定位于血管内皮细胞、部分成纤维细胞及新生表皮细胞中 ;Bcl 2则在照后 1～ 11d呈弱或中度阳性 ,定位于表皮、毛囊上皮及血管内皮中 ,之后为阴性或可疑阳性 ;照后 11～ 35d ,上述细胞特别是血管内皮细胞凋亡率较正常伤口愈合早期增高。结论 :辐射诱导的P53,Bax ,Bcl 2表达的变化及细胞凋亡率特别是血管内皮细胞凋亡率的增高与放射性皮肤溃疡发生、发展及难愈合 (不能形成有效肉芽组织 )

Objective:To study the expression of P53, Bax, Bcl 2 proteins and the role of cell apoptosis in the formation and development of acute radiation induced skin ulcers.Methods:A rat model which was locally irradiated with 60 Co γ rays was used, and the pathological changes were observed for 40 days. Immunohistochemistry and TUNEL assay were performed which enabled the detection of P53, Bax, Bcl 2 and cell apoptosis during the formation and development of radiation skin ulcers.Results: Skin ulcers were found on day 14 after irradiation, and enlarged and deepened gradually during the observation period. P53 was over expressed during days 11 to 40 after irradiation and was localized in vascular endotheliocytes and smooth muscle cells. Bax was moderately positive during days 14 to 21 and weakly positive during days 28 to 35, and was localized in vascular endotheliocytes, some fibroblasts and proliferating keratinocytes. Bcl 2 was weakly positive during days 1 to 11 after irradiation, and was located in keratinocytes, hair follicular cells and some vascular endotheliocytes. Bcl 2 was negative during days 11 to 40.The rate of cell apoptosis, especially of vascular endotheliocytes,was higher than that in the early process of normal wound healing. Conclusions:After irradiation,the increased expression of the apoptosis inducing protein P53, Bax and the decreased expression of the apoptosis inhibiting protein Bcl 2 might be associated with the high rate of apoptotic events, and play important roles in the formation and development of radiation skin ulcers. [