胆总管结扎致肝纤维化模型大鼠肝脏内源性AcSDKP及其调控因子水平的变化

Changes of levels of endogenous AcSDKP and its regulatory factors in liver tissue of model rats with liver fibrosis induced by bile duct ligation

目的:探讨胆总管结扎致肝纤维化模型大鼠肝脏组织中内源性N-乙酰基-丝氨酰-天门冬酰-赖氨酰-脯氨酸(AcSDKP)及相关调控因子水平的变化,阐明AcSDKP在肝纤维化过程中的作用。方法:45只普通级大鼠随机分为模型组、阻断组和对照组,每组15只。模型组采用胆总管结扎建立肝纤维化动物模型;阻断组应用血管紧张素转化酶抑制剂(ACEI)后建立肝纤维化动物模型;对照组予以开腹,但不结扎胆总管。分别在1、2和4周后留取血清及肝组织,检测各组大鼠肝功能指标、肝组织纤维化程度以及肝组织中AcSDKP水平,应用Western blotting法检测各组大鼠肝组织中胸腺素β4、赖氨酸寡肽酶(POP)和血管紧张素转换酶(ACE)水平。结果:自第1周开始,模型组大鼠血清中丙氨酸氨基转移酶(ALT)、门冬氨酸氨基转移酶(AST)、总胆红素(TB)和白蛋白(ALB)水平高于其他2组(P<0.05),而阻断组与对照组比较差异无统计学意义(P>0.05)。自第2周开始,模型组大鼠血清中ALB及肝组织中AcSDKP水平低于其他2组(P<0.05),而阻断组与对照组比较差异无统计学意义(P>0.05)。第1周,3组大鼠肝组织中Ⅲ型前胶原(PCⅢ)、Ⅳ型胶原(CⅣ)和透明质酸(HA)水平比较差异无统计学意义(P>0.05);第2周,模型组大鼠肝组织中PCⅢ、CⅣ和HA水平高于其他2组(P<0.05),阻断组与对照组上述指标比较差异无统计学意义(P>0.05)。第2周开始,模型组大鼠肝组织中胸腺素β4和ACE蛋白表达水平高于其他2组(P<0.05),而POP蛋白表达水平低于其他2组(P<0.05);阻断组与对照组上述指标比较差异无统计学意义(P>0.05)。模型组大鼠肝组织中第1周结构基本正常,第2周时呈现小灶状坏死,第4周时呈现片状坏死;阻断组与对照组大鼠肝组织各时间点结构基本正常。结论:胆总管结扎致肝纤维化大鼠肝组织中内源性AcsDKP水平降低可能是通过Tβ4-POP-AcsDKP轴实现的。

Objective:To explore the changes of levels of endogenous N-acetyl-seryl-aspartyl-lysylproline(AcSDKP)and its regulatory factors in liver tissue of rats with liver fibrosis induced by bile duct ligation,and to elucidate the effect of endogenous AcSDKP in the pathologic process of liver fibrosis.Methods:Forty-five healthy male rats were randomly divided into model group(the liver fibrosis rat models were set up by bile duct ligation),blocking group(the liver fibrosis rat models were treated with angiotensin-converting enzyme inhibitor before)and control group(the rats received laparotomy but not bile duct ligation);each group had 15 rats.The serum and liver tissue of the rats in various groups were gained at the 1st week,2nd week and 4th week.The differences in the indexes of liver function,the liver fibrosis degrees,and the AcSDKP levels in liver tissue of the rats in various groups were analyzed.The levels of thymosin beta 4(Tβ4),prolyl oligopeptidase(POP)and angiotensin converting enzyme(ACE)in liver tissue of the rats in various groups were detected by Western blotting.Results:The levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST)and total bilirubin(TB)of the rats in model group were higher than those in other two groups from the 1st week(P<0.05),and there were no differences between blocking group and control group(P>0.05).The ALB and the AcSDKP level in liver tissue of the rats in model group were lower than those in other two groups from the 2nd week(P<0.05),and there were no differences between blocking group and control group(P>0.05).The levels procollagen typeⅢ(PCⅢ),collagen typeⅣ(CⅣ)and hyaluronic acid(HA)in three groups had no differences at the 1st week(P>0.05).The levels of PCⅢ,CⅣ,and HA of the rats in model group were higher than those in other two groups from the 2nd week(P<0.05),and there were no differences between blocking group and control group(P>0.05).The levels of Tβ4 and ACE in liver tissue of the rats in model group were higher than those in other two groups from the 2nd week(P<0.05),and the level of POP of model group were lower than those in other two groups from the 2nd week(P<0.05),but there were no differences between blocking group and control group(P>0.05).The liver tissue of the rats in model group was basically normal at the 1st week,showed the focal necrosis at the 2nd week,and showed the flake necrosis at the 4th week.The liver tissue of the rats in blocking group and control group were basically normal at all time points.Conclusion:The endogenous AcSDKP level in the liver fibrosis rats induced by bile duct ligation is down-regulated through the axis of Tβ4-POP-AcsDKP.