长期铅暴露对小鼠胸腺细胞活化后诱导细胞凋亡的影响

Influence of long-term lead exposure on the activated induced cell death of thymocytes in mice

为探讨铅暴露对小鼠胸腺T细胞活化后诱导细胞凋亡的影响,将24只健康初断乳21日龄清洁级雄性KM小鼠随机分为4组:对照(蒸馏水)组和低(200 mg·L-1)、中(400 mg·L-1)、高(800 mg·L-1)剂量乙酸铅染毒组,每组6只.采用自由饮水方式进行染毒,连续染毒12周.染毒结束后,分离胸腺细胞,采用脂质体介导法将NFκB、AP-1、NFAT的荧光素酶报告基因转染到胸腺T细胞,刺激48 h后,检测荧光素酶活性.刺激胸腺细胞后,采用流式细胞仪检测凋亡相关膜分子Fas、FasL活性及细胞凋亡率.结果表明,与健康对照组小鼠相比,中、高剂量铅暴露组小鼠胸腺T细胞膜表面Fas及FasL表达明显增强(p<0.05),细胞凋亡率明显增加(p<0.05);相对于刺激前,anti-CD3刺激后各组小鼠胸腺T细胞的NFκB、AP-1、NFAT转录活性明显增加(p<0.05),Fas/FasL的表达明显增强(p<0.05),细胞凋亡率明显增加(p<0.05),但相对于刺激后健康对照组,各剂量铅暴露组小鼠胸腺T细胞3种核因子转录活性明显下降(p<0.05),Fas及FasL表达明显减弱(p<0.05),细胞凋亡率明显降低(p<0.05),且随着染铅剂量增加,均呈现下降趋势.

This study explored the effect of lead exposure on activated induced cell death of thymocytes in mice. A total of 24 healthy 21-day-old male KM mice were randomly and evenly divided into four groups, labeled as control group （distilled water） , low （200 mg·L^-1） , medium （400 mg·L^-1 ） and high （ 800 mg·L^-1 ） doses of lead acetate exposure group. Mice were continuously exposed to lead acetate in drink water for 12 weeks. At the end of the exposure, thymoeytes were separated, then the lueiferase reporter gene plasmid of NFKB, AP-1 and NFAT was transfeeted into thymoeytes by Tfx-50- mediated transfection. Luciferase activity of thymocytes, apoptotic membrane molecule Fas/FasL and apoptosis were assessed by flow cytometry after stimulating with antibody for 48h. The results showed that expression of apoptosis associated membrane molecule Fas/FasL was significantly enhanced and apoptosis increased in thymocytes of medium and high doses of lead acetate exposure group mice （p 〈 0.05）. The transcriptional activity of NFKB, AP- 1, NFAT, expression of Fas/FasL and apoptosis in thymocytes from all groups increased significantly after antibody stimulation; but compared with healthy controls, the transcriptional activity of NFKB, AP-1, 5/FAT, expression of Fas/FasL and apoptosis all significantly decreased in thymocytes fromvarious doses of lead exposure group after antibody stimulation （p 〈 0.05）. Along with increasing dose of lead acetate, all these factors displayed a downward trend.