自身免疫性肝炎患者肝组织纤维化机制的研究

目的 探讨自身免疫性肝炎(AIH)肝纤维化的机制。方法 以突触素(SYN)标记36例AIH患者肝穿刺标本的肝星状细胞(HSC)，采用免疫组化方法检测HSC、Ⅰ型胶原(ColD、Ⅳ型胶原(ColⅣ)及膜型基质金属蛋白酶1(MT-MMP-1)的表达，原位分子杂交方法(ISH)检测MT-MMP-1 mRNA及组织型金属蛋白酶1(TIMP-1)mRNA的表达。结果 36例AIH肝组织内SYN阳性HSC主要分布于汇管区、细胞纤维间隔及肝小叶炎症活动部位，尤其活动性界面炎部位往往呈聚集性分布，周围易见胶原纤维沉积，SYN阳性HSC数量与AIH肝组织活动指数(HAl，Knodell)呈正相关关系。ColⅠ、ColⅣ的表达量随AIH肝纤维化程度的增加而增加。ColⅣ主要分布于活动性炎症区域并随塌陷窦壁呈聚集性分布，ColⅠ主要见于纤维间隔及汇管区内，为S5～6期(Knodell)AIH肝组织内主要的细胞外基质(ECM)成分。MT-MMP-1及其mRNA阳性细胞主要见于汇管区周围界面炎及细胞纤维间隔边缘部位间质细胞内，周围少部分肝细胞亦呈阳性表达。MT-MMP-1及其mRNA表达与AIH肝组织HAI密切相关，且随AIH肝纤维化分期而增强，于S4～5期(Knodell)表达量最高，其后有所下降。AIH肝组织内TIMP-1的表达随肝纤维化的进展大致呈递增趋势。结论 AIH免疫损伤致反复持续性活动性炎症引起HSC的大量活化、增殖，进而引起ECM的沉积可能是AIH肝纤维化发生和进展的重要原因之一；MT-MMP-1引起ColⅣ的降解，改变HSC周围的微环境而诱导HSC的激活可能是HSC活化、增殖的机制之一；AIHECM的降解水平相对低下可能是AIH肝纤维化进展的另一重要机制。此外，本实验结果显示，SYN是研究肝纤维化组织内HSC的一个较好的标志物。

Study on the mechanism of fibrosis in autoimmune hepatitis

Objective To explore the mechanism of fibrosis in autoimmune hepatitis(AIH). Methods By using synaptophysin (SYN) as a new marker for hepatic stellate cells (HSCs),HSCs,collagen I,collagen IV,and MT-MMP-1 were detected by immunohistochemistry,and the expressions of MT-MMP-1 and TIMP-1 mRNA were assessed by in situ hybridization in liver tissues obtained by needle biopsy from 36 AIH patients. Results The HSCs were observed in the portal tracts,fibrotic septa and lobules of AIH liver tissues where inflammation was active,especially in the interface of inflammatory and non-inflammatory areas. The number of HSCs increased in proportion to the increase in histoligical active index (HAI,Knodell),while the deposition of Col I and Col IV were increased with increase in hepatic fibrosis stages (Knodell). MT-MMP-1 and its mRNA were mainly expressed in mesenchymal cells which were distributed in the areas of interface of inflammation and borders of fibrotic septa. It was also observed in a few hepatocytes. The expression of MT-MMP-1 was parallel to collagen IV distribution,and increased with advancement of HAI and fibrosis stages,reaching the peak at S4-5 stage. In addition,the expression of TIMP-1 mRNA was similar to that of MT-MMP-1 mRNA. Conclusions The results of immunohistochemistry and in situ hybridization suggested persistant active inflammation,triggering the activation and proliferation of HSC,and the resultant deposition of extracellular matrix such as collagen IV and I might be one of pathogenetic mechnisms of hepatic fibrosis in AIH. The increased expression of MT-MMP-1 in liver tissues of AIH in parallel with the advancement fibrotic stages also suggested that the relative lower level of ECM degeneration due to metalloproteinase suppression might be another reason for fibrogenesis and development of fibrosis in AIH. In addition,it was shown that synaptophysin was another good marker for HSC.