CCl_4诱导大鼠肝硬化形成过程中Caspase-12蛋白表达与肝细胞凋亡的相关性

Correlation between expression of Caspase-12 protein and apoptosis of hepatocytes during rat liver cirrhosis induced by carbon tetrachloride

目的:探讨CCl_4大鼠肝硬化形成过程中Caspase-12蛋白表达与肝细胞凋亡的相关性.方法:首次CCl_4 3 mL/kg sc,以后500 mL/L CCl_4橄榄油溶液2 mL/kg sc,2次/wk,共计12 wk制备大鼠肝硬化模型.设4wk、8wk、12 wk 3个时间点,动态观察肝细胞凋亡指数、肝组织Caspase-12免疫组织化学及蛋白表达.结果:模型大鼠4wk时呈典型的急性肝损伤改变,8wk时大鼠呈典型的慢性肝损伤肝纤维化的病理改变,12wk时已形成肝硬化;随着肝损伤加重和肝硬化形成,肝细胞凋亡指数显著增加,模型对照4wk与正常组、模型对照8 wk比较有显著差异(70.4±11.59 vs 9.6±1.14,95.8±10.94,P<0.01),模型对照12wk与模型对照8wk比较有统计学意义(122.8±17.51 vs 95.8±10.94,P<0.05).Caspase-12蛋白表达亦显著增加,模型对照4wk与正常组、模型对照8wk比较有显著差异(0.071±0.014 vs 0.014±0.007,1.172±0.028,P<0.01),模型对照12 wk与模型对照8wk比较亦有显著差异(1.84±0.083 vs 1.172±0.028,P<0.01):且肝细胞凋亡指数和Caspase-12蛋白表达量之间呈正相关(r=0.89,t=9.125,P<0.01).结论:内质网凋亡通路参与CCl_4大鼠肝硬化形成过程中肝细胞凋亡事件,其关键的凋亡酶Caspage-12蛋白表达量基本能够反映肝细胞的凋亡程度.

AIM： To investigate the correlation between expression of Caspase-12 protein and apoptosis of hepatocytes during rat liver cirrhosis induced by carbon tetrachloride （CCl4）. METHODS： Liver cirrhosis in male Wistar rats was induced by subcutaneous injection of undiluted CCl4 （3 mL/kg body wt） followed by 500 mL/L CCl4-olive solution （2 mL/kg body wt） twice a week for 12 weeks. Hepatocyte apoptosis indices （TUNEL staining）, immunohistochemistry and expression of Caspase-12 protein were observed dynamically at wk 4, 8, 12 during the modeling course. RESULTS： Typical acute liver injury was observed at wk 4, typical chronic liver injury and fibrosis at wk 8 and typical cirrhosis at wk 12, respectively. When the liver injury and cirrhosis became aggravated, hepatocyte apoptotic index increased significantly in the 4-week model group, compared with normal group and 8-week model group （70.4 ± 11.59 vs 9.6 ± 1.14, 95.8 ± 10.94, P 〈 0.01）. There were significant differences in hepatocyte apoptotic index between 12- and 8- week model groups （122.8 ± 17.51 vs 95.8 ± 10.94, P 〈 0.05）. Caspase protein expression increased significantly in the 4-week model group, compared with the normal group and 8-week model group （0.071 ± 0.014 vs 0.014 ± 0.007 and 1.172 ± 0.028, P 〈 0.01）. There were significant differences in Caspase-12 protein expression between 12- and 8- week model groups （1.84 ± 0.083 vs 1.172 ± 0.028, P 〈 0.01）. Furthermore, hepatocyte apoptotic index was positively correlated to Caspase-12 protein expression （r = 0.89, t = 9.125, P 〈 0.01）. CONCLUSION： Endoplastic reticulum apoptosis pathway is involved in hepatocyte apoptosis during rat liver cirrhosis induced by CCl4. Expression of Caspase-12 protein, the key molecule in this pathway, represents the degree of hepatocyte apoptosis.