抑制Yes相关蛋白通过抑制上皮间质转化减轻CCl_(4)诱导的小鼠肝纤维化

Inhibiting Yes-associated protein alleviates CCl_(4) liver fibrosis in mice by reducing epithelial mesenchymal transition

目的探索Yes相关蛋白(YAP)可否通过调控上皮间质转化影响肝纤维化的发生发展。方法将8周龄C57BL/6小鼠18只随机分为对照组、肝纤维化模型组和YAP抑制剂维替泊芬干预组,6只/组。肝纤维化模型采用四氯化碳(CCl_(4))溶液腹腔注射8周造模;维替泊芬干预组在CCl_(4)基础上第7~9周采用维替泊芬腹腔注射干预。HE染色、Masson染色、肝脏生化学检测观察小鼠肝脏纤维化程度;转录组、蛋白组学测序及联合生信分析探明肝纤维化过程中上皮间质转化通路是否受YAP调控;免疫组化染色和Western blotting检测YAP及上皮间质转化关键基因E-cadherin、N-cadherin、Twist等表达变化。采集健康体检、慢性乙型肝炎、乙肝肝硬化患者血清各60例,酶联免疫吸附法检测其中YAP、N-cadherin、Vimentin、Twist血清表达水平。C57BL/6小鼠24只随机分为对照组、肝纤维化模型组、Twist抑制剂干预组和Twist抑制剂与YAP激动剂共同干预组,6只/组。HE染色、Masson染色、网状纤维染色观察小鼠肝脏纤维化程度,Western blotting检测各组α-SMA、YAP和Twist表达变化。结果小鼠肝组织病理学结果提示肝纤维化小鼠与对照组相比肝小叶结构破坏、假小叶形成,维替泊芬干预组纤维间隔变性,部分小叶结构恢复。随肝纤维化发生,血浆ALT、AST水平显著升高(P<0.01),维替泊芬干预组肝功能改善(P<0.01)。采用肝组织转录组、蛋白组测序及联合分析找到在肝纤维化形成和维替泊芬干预过程中同时在mRNA和蛋白水平差异表达的基因,发现了N-cadherin和Twist在3组间差异具有统计学意义(P<0.05),并进行PPI分析显示YAP与E-cadherin、N-cadherin存在关联。免疫组化和Western blotting结果提示N-cadherin、Twist、Vimentin随肝纤维化形成升高,E-cadherin在肝纤维化组织中表达下降(P<0.01)。抑制YAP可下调肝组织N-cadherin、Twist蛋白表达(P<0.01)。慢性乙型肝炎患者血清YAP、N-cadherin、Vimentin和Twist水平均随肝炎及肝硬化发生升高,在APRI>0.5或FIB-4>1.45患者中显著升高(P<0.01)。血清YAP在健康对照、肝炎、肝硬化患者中平均水平分别为4.09、5.69和5.36 ng/mL(P<0.01),其与N-cadherin、Vimentin、Twist水平均呈显著正相关,相关系数分别为0.626、0.435、0.526。采用Harmine抑制小鼠肝组织Twist表达,并在Harmine基础上予以YAP激动剂XMU-MP-1干预,肝组织病理学结果提示抑制Twist使肝纤维化小鼠肝组织炎症及纤维化程度减轻,同时激活YAP表达可再次加重胶原纤维沉积。Western blotting检测结果提示Harmine下调肝纤维化小鼠肝组织中α-SMA、YAP及Twist蛋白表达,同时激活YAP使肝组织α-SMA和YAP表达升高(P=0.079,P<0.05)。结论上皮间质转化是肝纤维化发生的重要机制之一,抑制YAP可通过减少上皮间质转化发生减轻肝纤维化。

Objective To explore whether Yes-associated protein(YAP)affects occurrence and progression of liver fibrosis by regulating epithelial-mesenchymal transition(EMT).Methods In a 8-week-old C57BL/6 mouse model of CCl_(4)-induced liver fibrosis,the effect of verteporfin(a YAP inhibitor)intervention was assessed with HE staining and by detecting liver biochemistry and expressions of YAP and EMT-related genes using immunohistochemistry and Western blotting.Transcriptome and proteomic sequencing and informatics analysis were used to investigate the main downstream pathways of YAP in liver fibrosis.Serum levels of YAP,N-cadherin,vimentin and Twist were examined in 60 healthy individuals,60 patients with chronic hepatitis B(CHB),and 60 patients with HBV-related liver cirrhosis.In another 24 C57BL/6 mice,the effects of Twist inhibitor alone or in combination with harmine(a YAP activator)on CCl_(4)-induced liver fibrosis were evaluated by histopathological examination and Western blotting.Results The mouse models of liver fibrosis showed obvious structural damages of the liver lobes with formation of pseudolobules,and verteporfin treatment significantly improved these pathologies and lowered plasma ALT and AST levels of the mice.Transcriptome and proteomic sequencing and informatics analysis suggested that N-cadherin and Twist were differentially expressed in liver fibrosis in close correlation with YAP.Inhibition of YAP obviously downregulated hepatic N-cadherin and Twist protein expressions in the mice with liver fibrosis.In patients with CHB and liver cirrhosis,serum levels of YAP elevated obviously with the severity of liver fibrosis and were significantly correlated with N-cadherin,vimentin and Twist levels.In mice with liver fibrosis,inhibiting Twist effectively improved liver inflammation and fibrosis,while the combined treatment with YAP activator worsened hepatic collagen fiber deposition and increased hepatic YAP andα-SMA expressions.Conclusion EMT is an important pathogenic mechanism of liver fibrosis,and inhibiting YAP can alleviate liver fibrosis by reducing EMT.