Bcl-2、Bax基因表达在大鼠免疫性肝损伤中作用的探讨

目的研究细胞凋亡调节基因bcl2bax在免疫性大鼠肝损伤中的作用和血清铁的影响。方法通过放血或去铁胺(DFO)处理建立低铁动物模型。采用卡介苗加脂多糖(BCG+LPS)诱导法复制免疫性肝损伤模型。检测血清铁(SI)、转铁蛋白(TRF)、总蛋白(TP)含量及天门冬氨酸氨基转移酶(AST)活性,肝组织中丙二醛(MDA)和铁(HIC)含量,细胞凋亡调节蛋白基因bcl2和bax表达量的变化,计算细胞凋亡指数(AI)、细胞增殖指数(PI)和bax与bcl2(baxbcl2)比值。结果(1)单纯肝损伤大鼠凋亡相关基因bax的表达显著增加,bcl2不变,baxbcl2比值和AI增大;AST活性和MDA含量增加,TP含量降低。(2)血清铁降低大鼠的AST活性和TP含量不变,bax和bcl2的表达显著高于空白对照,baxbcl2比值和AI亦显著增大;但baxbcl2比值和AI增大的程度显著低于单纯肝损伤动物。(3)放血或注射DFO背景下肝损伤动物的bcl2、bax表达明显升高,但baxbcl2比值和AI显著低于单纯肝损伤动物;MDA含量低于单纯肝损伤动物,AST增高的幅度小于单纯肝损伤动物,TP含量不变。结论免疫性肝损伤时,细胞凋亡过程增强,易化肝细胞损伤;铁在调节免疫性肝损伤的细胞凋亡过程中起重要作用。

Study on the roles of the expression of bcl-2 and bax in experimental immunological liver injury in rats

ObjectiveTo elucidate the roles of Bcl-2 and Bax in experimental immunological liver injury in rat and the effect of lowering serum levels on the expression and the injury.Methods 48 male Wistar rats were divided into six groups randomly. The animal model of iron low-load was created by intravenation of deferoxamine (DFO) or phlebotomy respectively, and immunological liver damage model was reproduced by injection of BCG (Bacilli Calmette Guein) and lipopolysaccharide (LPS). Then the following parameters were determined such as serum iron (SI) concentration, transferrin (TRF) concentration, total proteins (TP) volume, the serum activity of aspartate aminotransferase (AST), malondialdehyde (MDA) content, iron content (HIC), the expression of Bcl-2 and Bax proteins in liver tissue were assayed; the ratio of Bax to Bcl-2, apoptotic index (AI), and proliferative index (PI) were also calculated.Results (1) The amount of Bax expression in liver injury group was significantly higher than that of control one, but no change in Bcl-2 expression. The ratio of Bax to Bcl-2 and AI augmented significantly, along with increased serum activities of AST and level of MDA, reduced volume of TP in liver injury animals. (2) The serum activity of AST and TP volume in both of the control groups with DFO and phlebotomy pretreatment remained at control level. Although the expression of Bax and Bcl-2, Bax/Bcl-2 ratio and AI were all higher than those of blank controls, the increased magnitudes of Bax/Bcl-2 ratio and AI were significantly lower than those of the liver injury animals. (3) The expression amounts of Bcl-2 and Bax increased in the injury animals induced after injecting DFO or phlebotomy, thus Bax/Bcl-2 ratio and AI increased. However, Bax/Bcl-2 ratio and AI of them were less than those of the injuries without lowered SI, and the magnitude of increased serum activity of AST was lower than that of the injuries, but no change in TP volume in the rats with lowered SI. The MDA levels in the injuries with lower value of serum iron were lower than those of the animals without lower SI.Conclusion The results show that the apoptotic process of hepatocyte accelerates in immunological liver injury, apoptosis may facilitate hepatocyte damage. Effect of iron on the expression of apoptosis regulating proteins have played an important role in apoptosis of immunological hepatic injury.