TGF-β1、Smad2在胆道闭锁肝纤维化中的作用

The effects of TGF-β1 and Smad2 on liver fibrosis of biliary atresia

目的研究转化生长因子(TGF)-β1与Smad2蛋白在胆道闭锁(BA)肝组织中的表达情况及在肝纤维化进程中的作用。方法选取2010年1月—2014年7月尸检(患儿死于非肝胆疾病,正常对照组)5例,胆管扩张症肝活检(胆扩组)10例,BA肝活检(早期肝纤维化组)19例,BA晚期进行肝移植患者自体肝活检(晚期肝硬化组)11例,采用HE染色观察并评价肝标本纤维化程度,免疫组化染色检测TGF-β1与Smad2蛋白在肝组织中的表达,实时荧光定量聚合酶链式反应(qRT-PCR)方法检测肝组织中TGF-β1与Smad2基因表达情况。结果 (1)HE。正常对照组肝组织无胶原纤维增生,胆扩组有轻度纤维细胞增生,早期肝纤维化组胶原纤维增生、桥接纤维化现象显著,而晚期肝硬化组假小叶显著。(2)免疫组化。TGF-β1蛋白平均光密度值在早期肝纤维化组表达最高(P<0.05);Smad2蛋白在4组间表达差异无统计学意义。(3)q RT-PCR。胆扩组、早期肝纤维化组和晚期肝硬化组3组肝内TGF-β1、Smad2 m RNA含量比较早期肝纤维化组均最高(P<0.017)。结论 BA肝纤维化早期TGF-β1、Smad2促进纤维化至门管区-门管区(P-P)、门管区-中央静脉(P-C)型桥样结构形成;随着纤维化程度加重,TGF-β1、Smad2表达促纤维化作用逐渐减弱。

Objective To investigate the expression and function of transforming growth factor (TGF)-β1 and Smad2 in liver fibrosis of biliary atresia (BA). Methods Liver biopsy specimens were collected from autopsy (normal group, n=5), congenital biliary dilatation (CBD group, n=10), BA patients underwent Kasai procedure (early hepatic fibrosis group, n=19) and liver transplantation (transplantation group, n=11). The first three groups were collected from January 2010 to July 2014 in Tianjin Children’s Hospital, and the last group was collected from January 2013 to January 2014 in Tianjin First Central Hospital. The hematoxylin and eosin (HE) stain were used to observe the degree of liver fibrosis of four groups. Immunohistochemistry (IHC) was used to observe expressions of TGF-β1 and Smad2 in liver tissues of these samples. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to test the quantitative mRNA of TGF-β1 and Smad2 in these samples. Results Results of HE showed that no fibrosis in autopsy group, mild fiber cell hyperplasia in CBD group, severe fibrosis in Kasai group and significant pseudolobule in transplantation group. Results of IHC showed that TGF-β1 was expressed in the cytoplasm of hepatocytes, bile duct cells, lymphocytes and neutrophils. The average optical density of TGF-β1 was the highest in Kasai group compared with that of other three groups (P < 0.05). There was no significant difference in Smad2 expression in cytoplasm of hepatocytes, bile duct cells and lymphocytes between four groups (P>0.05). Results of qRT-PCR showed that both TGF-β1 mRNA and Smad2 mRNA were the highest in early hepatic fibrosis group than those of CBD group and transplantation group (P<0.017). Conclusion In early stage of BA, TGF-β1 and Smad2 promote liver fibrosis until the formation of P-P,P-C desmosome structure. However, with BA fibrosis becomes more serious, the pro-fibrogenic function of TGF-β1 and Smad2 becomes less.